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doc. Ing. Martin Hromčík, Ph.D.

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Advanced Algorithms for Verification and Validation of Flexible Aircraft with Adaptive Control

  • DOI: 10.2514/1.G006151
  • Link: https://doi.org/10.2514/1.G006151
  • Department: Department of Control Engineering
  • Annotation:
    The verification and validation (VV) of model reference adaptive control (MRAC) in aerospace remains an open challenge. Existing approaches rely heavily on Lyapunov stability analysis and its dual certificate. Here we propose an additional numerical certificate that relies on robust MRAC modifications and the moment sum-of-squares (SOS) hierarchies with off-the-shelf-software. This approach serves as an alternative to Monte-Carlo.

Aircraft controllability through High-lift propellers

  • Authors: Belák, J., Beňo, D., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Proceedings of 24th International Conference on Process Control. Bratislava: Slovak University of Technology, 2023. p. 78-83. ISBN 979-8-3503-4763-0.
  • Year: 2023
  • DOI: 10.1109/PC58330.2023.10217691
  • Link: https://doi.org/10.1109/PC58330.2023.10217691
  • Department: Department of Control Engineering
  • Annotation:
    The current era of electrification of the aerospace industry brings many challenges, but also brings forward radically new aircraft designs. The new eVTOL and eSTOL concepts were enabled by the distributed electric propulsion. Even though eVTOL and eSTOL projects are gaining a lot of attention, another concept is also notable. The so-called High-Lift propulsion is based on the increase of airflow over the wing, thus reducing landing speed. Most notable example is NASA’s X-57 Maxwell. However, this concept can be used to control the aircraft as well. This paper introduces new approach of aircraft control using distributed High-Lift propulsion concept. The controller uses differential thrust to completely control the aircraft states and therefore eliminates the need for traditional control surfaces.

Decentralized active damping control for aeroelastic morphing wing

  • DOI: 10.1016/j.ast.2023.108415
  • Link: https://doi.org/10.1016/j.ast.2023.108415
  • Department: Department of Control Engineering
  • Annotation:
    This paper introduces a novel decentralized control design procedure for an aeroelastic morphing wing. The control goal is active damping of this flexible system. The model is developed as a multi-agent system with inherent interconnections between the agents. The control system then takes advantage of the model structure and interconnections rather than relying on the entire system's model. This brings benefits, especially with a growing number of agents where the control design dimension remains low. Therefore, the proposed control design is especially suitable for morphing wings with a large number of actuation points. The result is presented in the Linear Matrix Inequalities (LMIs) form. A numerical example shows the application of the proposed algorithm.

Unified attitude control strategy for tilt-rotor VTOL aircraft

  • Authors: Belák, J., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Proceedings of the American Control Conference. NEW YORK: The Institute of Electrical and Electronics Engineers, 2023. p. 2830-2835. ISSN 2378-5861. ISBN 979-8-3503-2806-6.
  • Year: 2023
  • DOI: 10.23919/ACC55779.2023.10156090
  • Link: https://doi.org/10.23919/ACC55779.2023.10156090
  • Department: Department of Control Engineering
  • Annotation:
    This paper introduces a unified approach to attitude control of tilt-rotor aircraft. The method utilizes moments-based actuation, based on real-time local linearization and LTI feedback systems. The main advantage of our approach is that it relies on fixed gain control laws throughout the entire flight envelope, including the transition from hover to cruise. This is achieved through sophisticated control allocation and model-matching algorithms. The method is designed with simple reconfiguration in case of an actuator failure, minimal computing power and future certification in mind. As a result, the developed algorithms were included in the development of the fly-by-wire system by a collaboration company.

Decentralized control for large scale systems with inherently coupled subsystems

  • DOI: 10.1177/10775463211034953
  • Link: https://doi.org/10.1177/10775463211034953
  • Department: Department of Control Engineering
  • Annotation:
    This paper brings a novel scalable control design methodology for Large-Scale Systems. Such systems are considered as multi-agent systems with inherent interactions between neighboring agents. The presented design methodology uses single-agent dynamics and their interaction topology, rather than relying on the model of the entire system. The dimension of the design problem therefore remains the same with growing number of agents. This allows a feasible control design even for large systems. Moreover, the proposed design is based on simple Linear Matrix Inequalities, efficiently solvable using standard computational tools. Numerical results validate the proposed approach.

Adaptive control design for the aeroelastic wing

  • DOI: 10.1109/PC52310.2021.9447451
  • Link: https://doi.org/10.1109/PC52310.2021.9447451
  • Department: Department of Control Engineering
  • Annotation:
    The design of adaptive control for an aeroelastic wing using structured H∞ synthesis is presented in this paper. The algorithm uses a polynomial interpolation of controller parameters for a wide airspeed range. The structure of control law is fixed, with its parameters determined for a given airspeed range. We demonstrate the possibilities of such a controller for active flutter suppression on the linear parameter-varying (LPV) servoaeroelastic wing model with two ailerons.

Command Shaping with Feedback Loop for Morphing Wings Control

  • Authors: Beneš, P., Balon, A., doc. Ing. Martin Hromčík, Ph.D., Šika, Z.
  • Publication: 2021 9th International Conference on Control, Mechatronics and Automation, ICCMA 2021. Piscataway: Institute of Electrical and Electronics Engineers, 2021. p. 116-119. ISBN 978-1-6654-1073-1.
  • Year: 2021
  • DOI: 10.1109/ICCMA54375.2021.9646199
  • Link: https://doi.org/10.1109/ICCMA54375.2021.9646199
  • Department: Department of Control Engineering
  • Annotation:
    This paper deals with the design and simulation verification of a SHAVO (SHAper+serVO) controller used for morphing wing control. The SHAVO control approach combines the advantages of forward command shaping and feedback control. The command shaping part based on the system model can quickly and efficiently eliminate residual vibrations, while the feedback part ensures stability and resistance to unmodeled model failures, deviations and external disturbances. The time length of this shaper can be set arbitrarily. The aircraft simulation model used for experiments has the fuselage and tail wings modelled as rigid bodies. The morphing wings are modelled using the aeroservoelastic model based on Euler - Bernoulli beam elements and simplified unstable aerodynamics.

Internal Model Control with Distributed-Delay-Compensator to Attenuate Multi-Harmonic Periodic Disturbance of Time-Delay System

  • Authors: Yuksel, C., Bušek, J., Vyhlídal, T., Niculescu, S.-I., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Proceedings of the 60th IEEE Conference on Decision and Control (CDC). Piscataway: IEEE, 2021. p. 5477-5483. ISSN 2576-2370. ISBN 978-1-6654-3659-5.
  • Year: 2021
  • DOI: 10.1109/CDC45484.2021.9683105
  • Link: https://doi.org/10.1109/CDC45484.2021.9683105
  • Department: Department of Control Engineering
  • Annotation:
    A distributed-delay based compensator for the Internal Model Control scheme is introduced as an alternative to the repetitive control structure to attenuate periodic disturbance with multiple harmonics. Besides the periodic signal attenuation, the scheme is derived to compensate an input time-delay of the controlled system. Next, the performance requirements on the spectral, frequency, and time domain characteristics are used for an optimization-based design. The task is to minimize the H∞ norm of the weighted sensitivity, while the spectral and structural properties comply with the constraints. The proposed design is tested on a model of a hot rolling process, which motivates the research. Numerical analysis and simulation-based verification complete the presentation.

Measures and lmis for validation of an aircraft with mrac and uncertain actuator dynamics

  • Department: Department of Control Engineering
  • Annotation:
    It is well known that actuator dynamics with degraded performance can lead to poor stability and tracking for adaptive control. In this paper, we use occupation measures and LMI relaxations (called the moment sums of squares or Lasserre hierarchy) for verification and validation of a longitudinal F-16 aircraft model with MRAC and higher order actuator dynamics with uncertain parameters and deflection saturation. These uncertain parameters are represented explicitly in the space of occupation measures. To improve numerical scalability, we exploit sparsity for ordinary differential equations (ODEs) using parsimony to partition the dynamics. We finally compare these main results to those obtained using Monte-Carlo methods.

Driving Envelope Definition and Envelope Protection Using Model Predictive Control

  • DOI: 10.23919/ACC45564.2020.9147211
  • Link: https://doi.org/10.23919/ACC45564.2020.9147211
  • Department: Department of Control Engineering
  • Annotation:
    Drive-by-wire technology opens a possibility to help the driver to drive a vehicle safely with support made by electronic control units. This paper presents an approach for defining a Driving Envelope that excludes any not welldefined vehicle states both for longitudinal and lateral dynamics. The second contribution is the design of a Model Predictive Controller for envelope protection that prevents critical situations such as the spinning of the vehicle, blocking of a wheel, and loss of the wheel traction. Validation results demonstrating the performance of the approach are obtained from a fixedsimulator with implemented high-fidelity twin-track model.

Dual-stage Soft Landing for a Pick-and-place Manipulator

  • DOI: 10.1016/j.ifacol.2020.12.2131
  • Link: https://doi.org/10.1016/j.ifacol.2020.12.2131
  • Department: Department of Control Engineering
  • Annotation:
    In this paper we document a systematic solution to a particular motion control problem called soft landing encountered in the design of pick-and-place machines for the semiconductor industry. The problem has already been studied for a single actuator, and a solution for the case of voice-coil motors has already been implemented in commercial drivers. Here we investigate a more complex setup consisting of two translation stages, which make the problem over-actuated; furthermore, the inner stage (actuated by a voice coil motor) is preloaded with a weight- compensating spring. Our systematic approach is based on the concept of reaction force observer. Its functionality is demonstrated using numerical simulations and laboratory experiments. We compare the proposed method with a baseline solution based on a simple extension of an existing method. A related Simulink model and Matlab scripts are available for free download to help reproduce the results. Copyright (C) 2020 The Authors.

Measures and LMIs for Lateral F-16 MRAC Validation

  • DOI: 10.23919/ACC45564.2020.9147855
  • Link: https://doi.org/10.23919/ACC45564.2020.9147855
  • Department: Department of Control Engineering
  • Annotation:
    Occupation measures and linear matrix inequality (LMI) relaxations (called the moment sums of squares or Lasserre hierarchy) are state-of-the-art methods for verification and validation (VV) in aerospace. In this document, we extend these results to a full F-16 closed-loop nonlinear dutch roll polynomial model complete with model reference adaptive control (MRAC). This is done through a new technique of approximating the reference trajectory by exploiting sparse ordinary differential equations (ODEs) with parsimony. The VV problem is then solved directly using moment LMI relaxations and off-the-shelf-software. The main results are then compared to their numerical counterparts obtained using traditional Monte-Carlo simulations.

Model Predictive Control of a Vehicle using Koopman Operator

  • DOI: 10.1016/j.ifacol.2020.12.2469
  • Link: https://doi.org/10.1016/j.ifacol.2020.12.2469
  • Department: Department of Control Engineering
  • Annotation:
    This paper continues in the work from Cibulka et al. (2019) where a nonlinear vehicle model was approximated in a purely data-driven manner by a linear predictor of higher order, namely the Koopman operator. The vehicle system typically features a lot of nonlinearities such as rigid-body dynamics, coordinate system transformations and most importantly the tire. These nonlinearities are approximated in a predefined subset of the state-space by the linear Koopman operator and used for a linear Model Predictive Control (MPC) design in the highdimension state space where the nonlinear system dynamics evolve linearly. The result is a nonlinear MPC designed by linear methodologies. It is demonstrated that the Koopman-based controller is able to recover from a very unusual state of the vehicle where all the aforementioned nonlinearities are dominant. The controller is compared with a controller based on a classic local linearization and shortcomings of this approach are discussed.

Safety-extended Explicit MPC for Autonomous Truck Platooning on Varying Road Conditions

  • DOI: 10.1016/j.ifacol.2020.12.1381
  • Link: https://doi.org/10.1016/j.ifacol.2020.12.1381
  • Department: Department of Control Engineering
  • Annotation:
    Automotive platooning can significantly improve traffic safety and efficiency, but many control challenges need to be solved to function properly under realistic driving conditions. This paper proposes a novel multi-rate explicit model-predictive controller (eMPC) for safe autonomous distributed vehicle platooning in varying road friction conditions. A safety-augmented distributed predictive control formulation ensures safe vehicle spacing versus emergency braking of preceding vehicles given current friction estimates. This complex control problem is carefully formulated into an efficiently parametrized optimization problem realized as eMPC. The resulting platoon shows excellent performance in a complex vehicle dynamics co-simulation validation with low communication and computation demands.

Visually Assisted Anti-lock Braking System

  • DOI: 10.1109/IV47402.2020.9304807
  • Link: https://doi.org/10.1109/IV47402.2020.9304807
  • Department: Department of Control Engineering, Visual Recognition Group
  • Annotation:
    The concept of a visually-assisted anti-lock braking system (ABS) is presented. The road conditions in front of the vehicle are assessed in real time based on camera data. The surface type classification (tarmac, gravel, ice, etc.) and related road friction properties are provided to the braking control algorithm in order to adjust the vehicle response accordingly. The system was implemented and tested in simulations as well as on an instrumented sub-scale vehicle. Simulations and experimental results quantitatively demonstrate the benefits of the proposed system in critical maneuvers, such as emergency braking and collision avoidance.

Active flutter suppression by means of fixed-order H-infinity control: results for the Benchmark Active Control Technology (BACT) wing

  • DOI: 10.23919/ECC.2019.8795733
  • Link: https://doi.org/10.23919/ECC.2019.8795733
  • Department: Department of Control Engineering
  • Annotation:
    The Benchmark Active Control Technology model based on NASA research and wind tunnel tests is used to demonstrate the possibilities of modern fixed-order controllers for active flutter suppression. Direct design methods based on nonsmooth, nonconvex optimization are utilized that give rise to H∞ optimal control laws with prescribed structure and complexity. We compare achieved performance with classical unconstrained H∞ design.

Construction of the smooth morphing trailing edge demonstrator

  • DOI: 10.1109/PC.2019.8815050
  • Link: https://doi.org/10.1109/PC.2019.8815050
  • Department: Department of Control Engineering
  • Annotation:
    This paper describes the development of the smart morphing trailing edge demonstrator intended for wind tunnel experiments and control laws validations. Our design puts great emphasis on smooth transitions between individual actuated segments. The technology of 3D printing has been used for wing parts production. Trailing edge actuation is ensured by macro fiber composite (MFC).

Data-driven identification of vehicle dynamics using Koopman operator

  • DOI: 10.1109/PC.2019.8815104
  • Link: https://doi.org/10.1109/PC.2019.8815104
  • Department: Department of Control Engineering
  • Annotation:
    This paper presents the results of identification of vehicle dynamics using the Koopman operator. The basic idea is to transform the state space of a nonlinear system (a car in our case) to a higher-dimensional space, using so-called basis functions, where the system dynamics is linear. The selection of basis functions is crucial and there is no general approach on how to select them, this paper gives some discussion on this topic. Two distinct approaches for selecting the basis functions are presented. The first approach, based on Extended Dynamic Mode Decomposition, relies heavily on expert basis selection and is completely data-driven. The second approach utilizes the knowledge of the nonlinear dynamics, which is used to construct eigenfunctions of the Koopman operator which are known by definition to evolve linearly along the nonlinear system trajectory. The eigenfunctions are then used as basis functions for prediction. Each approach is presented with a numerical example and discussion on the feasibility of the approach for a nonlinear vehicle system.

Introduction of Driving Envelope and Full-Time-Full-Authority Control for Vehicle Stabilization Systems

  • DOI: 10.1109/PC.2019.8815305
  • Link: https://doi.org/10.1109/PC.2019.8815305
  • Department: Department of Control Engineering
  • Annotation:
    This paper introduces the idea of the full-time-fullauthority control, known from the flight control field, for the automotive industry. Also, it provides a derivation of a nonlinear single-track vehicle model for an over-actuated car and introduces the vehicle states feasibility set, called here driving envelope, inspired by aircraft flight envelope, providing safe operation zone limits for a vehicle. As an addition, authors show proof based on vehicle dynamic physics, what practical pros can bring the usage of the steered rear axle together with the front axle.

Measures and LMIs for Adaptive Control Validation

  • DOI: 10.1109/CDC40024.2019.9029254
  • Link: https://doi.org/10.1109/CDC40024.2019.9029254
  • Department: Department of Control Engineering
  • Annotation:
    Occupation measures and linear matrix inequality (LMI) relaxations (called the moment sums of squares or Lasserre hierarchy) have been used previously as a means for solving control law verification and validation (VV) problems. However, these methods have been restricted to relatively simple control laws and a limited number of states. In this document, we extend these methods to model reference adaptive control (MRAC) configurations typical of the aircraft industry. The main contribution is a validation scheme that exploits the specific nonlinearities and structure of MRAC. A nonlinear F-16 plant is used for illustration. LMI relaxations solved by off-the-shelf-software are compared to traditional Monte-Carlo simulations.

Structural load alleviation using distributed delay shaper: Application to flexible aircraft

  • DOI: 10.1016/j.conengprac.2019.05.005
  • Link: https://doi.org/10.1016/j.conengprac.2019.05.005
  • Department: Department of Control Engineering
  • Annotation:
    Lightweight flexible aircraft suffers from unwanted oscillatory vibrations during aircraft manoeuvres. A recently developed distributed-delay signal (DZV) shaper is therefore proposed to be applied as a feedforward controller to alleviate the manoeuvre loads, as an alternative to traditional structural filters used routinely in this context. Structural filters are essentially linear low-pass filters with bandwidth below the significant flexible modes, applied to control signals generated either by the pilot’s direct input or by the flight control system. It has been showed that if instead a properly tuned signal shaper is used, better performance can be achieved: first, the target modes are significantly attenuated while the responsiveness of the aircraft is less compromised and secondly, the oscillatory nature of the vibrations are reduced. The high fidelity simulation results on a full scaled dynamic model of a highly flexible blended wing–body (BWB) aircraft show that in comparison to traditional structural filters, signal shapers significantly reduce the wing root loading (forces and moments) which provides potential structural benefits.

Structure-preserving low-order modeling approach of laminated composite plates integrated with macro-fiber composite transducers for dynamic applications

  • DOI: 10.1016/j.compstruct.2018.09.062
  • Link: https://doi.org/10.1016/j.compstruct.2018.09.062
  • Department: Department of Control Engineering
  • Annotation:
    An Equivalent Substructure Modeling (ESM) approach of laminated composite plates with integrated macro-fiber composite (MFC) transducers is described. The proposed approach generates structure-preserving low-order system models for dynamic applications such as vibration suppression and energy harvesting. The direct piezoelectric effect of MFC transducers is derived from the electrical boundary conditions and it has the same coupling patterns as equivalent forces which describe the inverse piezoelectric effect. Hence, the reversibility of the piezoelectric effect is ensured and the electrical dynamics of the system can be simulated. The dual electromechanical couplings are assigned to a low-order structural model generated by an equivalent substructure concept. A laminated composite plate with integrated MFC transducers is used for validations and the simulated results agree well with experimental data. Two given study cases demonstrated that the ESM approach not only can generate accurate low-order system models but also provides a flexible fashion to design piezoelectric composite systems.

Vehicle longitudinal dynamics control based on LQ

  • DOI: 10.1109/PC.2019.8815044
  • Link: https://doi.org/10.1109/PC.2019.8815044
  • Department: Department of Control Engineering
  • Annotation:
    Trend of autonomous vehicles and e-mobility is in favor of an advanced control system development and deployment. Vehicle dynamics level control systems providing safety limits and high performance response, especially during high dynamics maneuvers, are necessary. This work provides solution for vehicle longitudinal dynamics (vehicle acceleration) considering physical limits given by road, tire and vehicle dynamics respectively. The goal is to maximize vehicle longitudinal acceleration by controlling each wheel longitudinal slip ratio. Considered mathematical model is non-linear single track model incorporating non-linear Pacejka magic formula as a tire model. Design model for control system is derived as a linearized state-space model at constant acceleration operation point. Therefore, the common linearization approach, at system equilibrium, is not possible and the linearization along system trajectory is used. Such solution results in involvement of LPV techniques, as vehicle velocity is state variable. Finally, the LQ optimal control framework is employed to deliver control algorithms providing constant vehicle acceleration trajectory tracing. This is accomplished by longitudinal slip ratio control for each wheel.

Control design with inverse feedback shaper for quadcopter with suspended load

  • Authors: Bušek, J., Kuře, M., doc. Ing. Martin Hromčík, Ph.D., Vyhlídal, T.
  • Publication: Proceedings of ASME 2018 Dynamic Systems and Control Conference. Michigan: ASME Dynamic Systems and Control Division, 2018. vol. 3. ISSN 2151-1853. ISBN 978-0-7918-5191-3.
  • Year: 2018
  • DOI: 10.1115/DSCC2018-9052
  • Link: https://doi.org/10.1115/DSCC2018-9052
  • Department: Department of Control Engineering
  • Annotation:
    A control design and numerical study is presented for the problem of maneuvering a quadcopter with suspended load. An inverse shaper with a distributed time delay is applied to the feedback path in order to pre-compensate the oscillatory mode of the two-body system. As the first step, the mode to be targeted by the inverse shaper is determined, which is neither the oscillatory mode of the overall system dynamics, nor the oscillatory mode of the suspended load. Next, the established cascade control scheme for UAVs with slave PD pitch angle controller and master PID velocity controller is adopted and supplemented by the inverse shaper tuned to the isolated flexible mode. The numerical and simulation based analysis reveals the key design aspects and dynamics features - due to including the inverse shaper with time delays, the closed loop system becomes infinite dimensional. As the main result, the positive effects of including the inverse shaper in the loop feedback are demonstrated. First of all, the oscillatory mode is well compensated when excited by both the set-point and disturbance changes. Besides, it is shown that the mode compensation is preserved even when reaching the saturation limits at the control actions.

Control of Vibration Suppression of Planar Structures Using Actuation by Clusters of Piezopatches

  • Authors: Volech, J., Šika, Z., Ing. Filip Svoboda, Ph.D., doc. Ing. Martin Hromčík, Ph.D., Zavřel, J., Karlíček, J.
  • Publication: Proceedings of the SMS EUROPE 2018, Italy, International Conference. Paříž: Science, Engineering, Technology Conferences Organisers, 2018. p. 1-4.
  • Year: 2018
  • Department: Department of Control Engineering
  • Annotation:
    “Intelligent materials” are nowadays the perspective subject of research. Thanks to piezo material price developments, one type of this material could be the common material with heavily distributed piezo elements. Such material can still have lightness, flexibility and approximately other aspects of the original material, but with the added energy these properties may be partially modified. The paper deals with optimization and control of vibration suppression of the planar flexible systems equipped by regular and dense matrix of multiple sensors and actuators. The proposed concept consists from the steel cantilever beam with three piezoelectric patches. FEM model of such concept was created to test its accuracy compared to reality. A detailed description of this problem could be seen in [1]. On this model, the H-infinity controller was designed and subsequently tested on the real experiment with promising results. Based on these results, the model was extended to a square plate with distributed piezo patches in the 5x5 grid. The results from decentralized control law synthetized by the h-infinity will be presented. Results are promising, but such a heavily distributed grid still leads to demands on the initial expense. The actuators and sensors are not that big problem, the problem occurs with the amplifiers needed to power individual piezo elements. In order of further savings, four more concepts were proposed and will be presented. There are formed several groups “clusters” of piezo patches which are powered with a single amplifier and single control voltage. These clusters are then subject of an analysis based on total energy loss using the Hankel matrix and controllability criteria. The results showed that the system can be controlled with minimal energy loss for each mode with only nine amplifiers and nine different inputs voltages. That leads to saving the 16 amplifiers and open the possibilities of further improvements.

Decentralized and Distributed MIMO H-infinity Robust Control of Vibration Suppression of Planar Structures

  • Authors: Šika, Z., doc. Ing. Martin Hromčík, Ph.D., Volech, J., Ing. Filip Svoboda, Ph.D., Zavřel, J., Karlíček, J.
  • Publication: Proceedings of ISMA2018 International Conference on Noise and Vibration Engineering USD2018 International Conference on Uncertainty in Structural Dynamics. KU Leuven, 2018. p. 309-323. ISBN 9789073802995.
  • Year: 2018
  • Department: Department of Control Engineering
  • Annotation:
    Distributed control is nowadays a very active field of research, thanks to potential applications which require high scalability and reliability. The paper deals with the optimization of active vibration suppression of the planar flexible systems equipped by regular and dense matrix of multiple sensors and actuators. The H infinity design with predefined controller structure has been chosen as an appropriate control method. At first, performance of H-infinity regulator was experimentally tested on simple beam demonstrator with piezoelectric patches as sensors and actuators. The simulation model of larger planar demonstrator has been firstly modelled by FEM and then exported into the state space form. Decentralized and distributed control laws have been investigated. The feasibility of attenuation of a large set of flexible modes has been demonstrated for the model of the demonstrator. The demonstrator itself has been prepared for the ongoing experiments. The possibility of alternative actuation by clusters of actuators has been also analyzed.

Distributed State Feedback Control for Aeroelastic Morphing Wing Flutter Supression

  • DOI: 10.1109/MED.2018.8442815
  • Link: https://doi.org/10.1109/MED.2018.8442815
  • Department: Department of Control Engineering
  • Annotation:
    This paper offers a novel approach at flutter suppression problem on morphing wing and relates to current research of morphing aircraft. The active flutter suppression task is formulated as a state synchronization in a network of identical Linear Time-Invariant (LTI) systems. These systems consist of wing segments which can be actuated separately. Finite Element Method (FEM) approach and unsteady aerodynamics represented by Theodorsen function are used for flexible morphing wing modeling. An example of distributed Linear-Quadratic Regulator (LQR) state synchronization is shown in this paper. Comparison in time-domain, frequency-domain, and flutter speeds has been done for the system with distributed LQR and the original system.

Low-Complexity Decentralized Active Damping of One-Dimensional Structures

  • DOI: 10.1155/2018/6421604
  • Link: https://doi.org/10.1155/2018/6421604
  • Department: Department of Control Engineering
  • Annotation:
    In the paper, we propose distributed feedback control laws for active damping of one-dimensional mechanical structures equipped with dense arrays of force actuators and position and velocity sensors. We consider proportional position and velocity feedback from the neighboring nodes with symmetric gains. Achievable control performance with respect to stability margin and damping ratio is discussed. Compared to full-featured complex controllers obtained by modern design methods like LQG, H-infinity, or mu-synthesis, these simplistic controllers are more suitable for experimental fine tuning and are less case-dependent, and they shall be easier to implement on the target future smart-material platforms.

Cloth-like Structures with Distributed Active Damping

  • Authors: Beneš, P., Šika, Z., doc. Ing. Martin Hromčík, Ph.D., Krejza, R.
  • Publication: Proceedings of the 8th ECCOMAS Thematic Conference on MULTIBODY DYNAMICS 2017. Praha: CTU PH. Production, 2017. p. 511-514. 1. ISBN 978-80-01-06174-9.
  • Year: 2017
  • Department: Department of Control Engineering
  • Annotation:
    This paper deals with the modelling and control of a thin and light (cloth-like) material. The basic structure of the model is based on a spring-damper-mass approach but the active components are added into this structure in order to control mechanical properties of the cloth, especially the damping. The identification of unknown parameters is based on experimental results. The control strategy is a decentralized collocated control with velocity-feedback loops. Different distributions of active elements in the structure were compared and optimized in order to improve damping characteristics of the structure.

Equivalent force modeling of macro fiber composite actuators integrated into nonhomogeneous composite plates for dynamic applications

  • DOI: 10.1088/1361-665X/aa7bd0
  • Link: https://doi.org/10.1088/1361-665X/aa7bd0
  • Department: Department of Control Engineering
  • Annotation:
    Smart structures with integrated macro fiber composite (MFC) piezoelectric transducers have been increasingly investigated in engineering. A simple but elaborate system model of such smart structure not only can predict system dynamics, but also can reduce challenges in application. Therefore, the equivalent force (EF) modeling approach is presented to model the plate-type structures with integrated piezoelectric actuators in a semi-analytical fashion: analytical EF is applied to finite element (FE) structural models. The EF is derived from the bending effort balance between the equivalent loads, and the equivalent loads are developed by introducing the spatial distribution into a generalized Hamilton's principle. The proposed approach is validated by cantilever aluminum beams with integrated MFC actuators and it is consistent with existing alternative approaches from literature. Then, it is validated on a non-homogeneous composite plate for dynamic applications: a laminated composite plate with integrated MFC actuators was manufactured and both an impact test and MFC drive test were elaborately carried out. The modal validation shows the high fidelity of the EF model and the predicted velocity frequency responds functions (FRFs) agree well with experimental measurement. Being applicable to both numerical and analytical modeling approaches, the EF is actually assigned to the out-plane displacement on the structure and distributed along the edges of the actuators. Therefore, it is convenient to use in EF models. The rotational degrees of freedom could also be eliminated in the EF models without losing structure complexity, since they neither link to the electromechanical coupling nor have a significant kinetic contribution to the system.

Finite element method based modeling of a flexible wing structure

  • DOI: 10.1109/PC.2017.7976217
  • Link: https://doi.org/10.1109/PC.2017.7976217
  • Department: Department of Control Engineering
  • Annotation:
    The finite element based structural model of a flexible wing is presented. The structural model will be a part of a servoelastic wing used for flutter analysis and designing flutter suppression control systems. It also allows modal analysis of a wing with given parameters. A finite element model consists of Euler-Bernoulli beams joined together. This approach is able to reach high accuracy and various properties of a particular wing element can be modeled.

Flexible Mode Compensation by Inverse Shaper in the Loop with Magnitude Saturated Actuators

  • Authors: Alikoç, B., Bušek, J., Vyhlídal, T., doc. Ing. Martin Hromčík, Ph.D., Ergenç, A.F.
  • Publication: Proceedings of the IFAC 2017 World Congress. Kidlington Oxford OX GB: Elsevier, 2017. p. 1251-1256. ISSN 2405-8963.
  • Year: 2017
  • DOI: 10.1016/j.ifacol.2017.08.350
  • Link: https://doi.org/10.1016/j.ifacol.2017.08.350
  • Department: Department of Control Engineering
  • Annotation:
    An input shaping architecture for vibration suppression of flexible systems controlled with magnitude saturated actuators is considered. It is shown that the distributed-delay shapers with the inverse form in the feedback path have the capability of canceling the undesired vibration caused by saturation limit of actuators. The main idea is to treat the saturation effect as a disturbance on the control input of the actuator which can be canceled by the shapers in the feedback control loop. The inverse form of a recently proposed distributed-delay shaper is utilized to dispose of the undesired vibrations subject to saturation. The theoretical results are compared with an existing solution and verified on a laboratory set-up.

Input Shaper Optimization with a Constraint on the Spectrum Distribution

  • DOI: 10.1016/j.ifacol.2017.08.1893
  • Link: https://doi.org/10.1016/j.ifacol.2017.08.1893
  • Department: Department of Control Engineering, Intelligent Data Analysis
  • Annotation:
    This paper presents a procedure to parametrize input shapers with piecewise equally distributed time delays. The procedure seeks to minimize residual vibrations around an undesirable frequency but at the same time avoids introducing zeros in the right half plane. This ensures that the introduction of the inverse of the input shaper in a closed feedback loop does not introduce unstable poles in the system. The requirement of stable spectra for the input shaper appears as an additional constraint in a constrained optimization problem that includes minimizing the response time and residual vibrations while preserving required properties of the shaper. The novel introduction of a spectral constraint makes the optimization problem nonsmooth and nonconvex, necessitating special optimization algorithms for its reliable solution. The framework is outlined in detail and the results of the optimization are presented indicating the success of the procedure.

Input shaping solutions for drones with suspended load: First results

  • Authors: Homolka, P., doc. Ing. Martin Hromčík, Ph.D., Vyhlídal, T.
  • Publication: Proceedings of the 2017 21st International Conference on Process Control. IEEE (Institute of Electrical and Electronics Engineers), 2017. p. 30-35. ISBN 978-1-5386-4011-1.
  • Year: 2017
  • DOI: 10.1109/PC.2017.7976184
  • Link: https://doi.org/10.1109/PC.2017.7976184
  • Department: Department of Control Engineering
  • Annotation:
    In this paper our first achievements are reported on application of input command shapers for control of quadcopters with suspended load. Simulation results are presented for a free 2DoF quadcopter. The flight control system, consisting of two PID controllers and of a static nonlinearity mapping the propellers thrusts to particular degrees of freedom, is augmented by input shapers in the feedforward path. Properties of the resulting control law are presented and further research proposals are elaborated.

Inverse Feedback Shapers for Coupled Multibody Systems

  • DOI: 10.1109/TAC.2017.2688179
  • Link: https://doi.org/10.1109/TAC.2017.2688179
  • Department: Department of Control Engineering
  • Annotation:
    The concept of inverse feedback shapers is fully developed in this report for the case of multibody systems with strongly coupled dynamics. The presented results constitute a non-trivial extension of the previous papers by the authors on input shaping focusing on effectively decoupled controlled and flexible parts. As the main technical result, the target mode for the inverse shaper design is identified based on an input-output transformation of the multibody system into the controlled subsystem, the attached residual oscillatory dynamics, and an internal feedback loop representing the dynamical coupling. A state feedback controller, applied for the selected generalized coordinate, is considered throughout this paper.

Linear analysis of lateral vehicle dynamics

  • Authors: Mondek, M., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Proceedings of the 2017 21st International Conference on Process Control. IEEE (Institute of Electrical and Electronics Engineers), 2017. p. 240-246. ISBN 978-1-5386-4011-1.
  • Year: 2017
  • DOI: 10.1109/PC.2017.7976220
  • Link: https://doi.org/10.1109/PC.2017.7976220
  • Department: Department of Control Engineering
  • Annotation:
    Systematic analysis of lateral dynamics of a ground vehicle (e.g. passenger car) is presented in this paper. The results are based on the simplest possible single-track model. Effects of variations in the physical parameters-mass, the moment of inertia, tire priorities, vehicle geometry-on the response times, damping ratios, natural frequencies and other dynamical characteristics are presented and confronted with intuitive and 'common sense' expectations and with real-life experience of race car drivers and constructors. We believe that such a report is quite unique and useful by itself: We are not aware of any similar existing report which would provide this systems- A nd-controls viewpoint on the vehicle dynamics phenomena. In addition, future plans are to apply modern systematic model-based control design approaches to come up with active dynamics modifications solutions-using for instance torque vectoring-surpassing current approaches based mainly on mechanical redesigns and, to some extent, simplest possible local feedback controllers.

Mixed-sensitivity design of a dynamic controller for systems pre-compensated by input shapers

  • Authors: Pilbauer, D., Michiels, W., Vyhlídal, T., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Proceedings of the IFAC 2017 World Congress. Kidlington Oxford OX GB: Elsevier, 2017. p. 1304-1309. ISSN 2405-8963.
  • Year: 2017
  • DOI: 10.1016/j.ifacol.2017.08.108
  • Link: https://doi.org/10.1016/j.ifacol.2017.08.108
  • Department: Department of Control Engineering
  • Annotation:
    We employ recent control design algorithms for delay systems to address the mixed sensitivity design of a dynamic controller for multiple degree of freedom systems interconnected with an inverse signal shaper. A delay based inverse shaper is included within a feedback loop in order to eliminate oscillatory modes due to an attached flexible substructure, which has been shown to be advantageous to inducing directly the filtering property by an appropriate controller design. Due to the presence of the inverse shaper, the closed loop dynamics become infinite dimensional. Furthermore we design fixed-order controllers, aiming at an easy implementation. As a consequence of these two features standard techniques from H-infinity control can no longer be used. We present a two-stage method, which firstly makes the closed-loop system asymptotically stable and, secondly, computes a low-order controller that minimizes the H-infinity norm of the weighted closed-loop transfer functions. The approach is grounded in recent methods for fixed-order H-infinity control of delay systems, and the delay-differential algebraic equations (DDAE) modelling and control framework.

Robust pitch attitude hold with MRAC for a nonlinear light combat aircraft model

  • Authors: Wagner, D., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Proceedings of the 2017 21st International Conference on Process Control. IEEE (Institute of Electrical and Electronics Engineers), 2017. p. 71-75. ISBN 978-1-5386-4011-1.
  • Year: 2017
  • DOI: 10.1109/PC.2017.7976191
  • Link: https://doi.org/10.1109/PC.2017.7976191
  • Department: Department of Control Engineering
  • Annotation:
    In this paper, we implement a robust model reference adaptive control (MRAC) as part of an ongoing effort to demonstrate practical application of a nonlinear control system to the pitch-attitude hold of an aircraft model. We show that MRAC can improve transient performance and compensate changes in the performance characteristics of the aircraft mid-flight by evaluating an example where a change in center of gravity of the aircraft is coupled with decreased control effectiveness.

Vibration Control of cantilever Beam using collocated piezoelectric sensor/actuator Pair

  • Department: Department of Control Engineering
  • Annotation:
    This paper presents an approach to active vibration suppression of cantilever beam using collocated pair of piezo-patches. Thin steel plate equipped with three piezo-patches is modeled using ANSYS software. Experimental structure is build and based on measured data state-space model using experimental identification procedure was developed. Eigenfrequencies of identified and finite element model are compared. Based on identified model H-infinity regulator is designed using HIFOO package. Experimental results are presented.

Active flutter suppression with fixed-order H∞ controller

  • Department: Department of Control Engineering
  • Annotation:
    The simulation model of a flexible wing is used to demonstrate the possibilities of modern fixed-order controllers for active flutter suppression. Direct design methods based on nonsmooth, nonconvex optimization, are utilized that give rise to H∞ optimal control laws with prescribed structure and complexity. We compare achieved performance with classical unconstrained H∞ design, both of full-order and after controller order reduction.

Design, Analysis and Implementation of Smoothed Input Shapers with Distributed Delays

  • Authors: Vyhlídal, T., Kučera, V., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Recent Results on Time-Delay Systems: Analysis and Control. Cham: Springer International Publishing AG, 2016. p. 229-248. Advances in Delays and Dynamics. vol. 5. ISSN 2197-117X. ISBN 978-3-319-26367-0.
  • Year: 2016
  • DOI: 10.1007/978-3-319-26369-4_12
  • Link: https://doi.org/10.1007/978-3-319-26369-4_12
  • Department: Department of Control Engineering
  • Annotation:
    Zero vibration input shapers with distributed delays are considered with the objective to compensate the undesirable oscillatory modes of the system under consideration. Next to the lumped delay, which has been used in the input shapers so far, equally and triangularly distributed delays are considered as the key elements in the shaper design. These delays provide signal smoothing of the Trapezoidal and S-curve like smoothers, whereas the full compensation of the undesirably oscillatory mode is guaranteed for the nominal case.

Elektron I

Low-complexity control laws for active damping of smart structures with heavily distributed actuators and sensors

  • Department: Department of Control Engineering
  • Annotation:
    First results are reported on feasibility of simple feedback control laws for active damping of mechanical structures equipped with dense arrays of force actuators and velocity sensors. Proportional decentralized and distributed control laws, characterized by a very small number of parameters (one or two) are considered. Compared to full-featured complex controllers, obtained by modern design methods like LQG, H-infinity, musynthesis, these simplistic controllers are more suitable for experimental finetuning, are less case-dependent, and they shall be easier to implement on the target future smart-material platforms.

Modeling and Experimental Test Study of a Multilayer Piezoelectric Actuator

  • Authors: Dong, Z., Faria, C.T., Desmet, W., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Conference Proceedings of the Society for Experimental Mechanics Series. Cham: Springer International Publishing, 2016. pp. 327-336. ISSN 2191-5644. ISBN 978-3-319-29753-8.
  • Year: 2016
  • DOI: 10.1007/978-3-319-29754-5_32
  • Link: https://doi.org/10.1007/978-3-319-29754-5_32
  • Department: Department of Control Engineering
  • Annotation:
    In order to increase the performance of piezoelectric actuators/sensors, a common practice is to stack thin layers of active materials with electrodes in between such that higher electric fields are achieved inside the piezoelectric elements. Modeling this composite material requires either a detailed description of the layers components or the use of equivalent properties. The work presented in this paper achieved a comparative study between these two modeling approaches. The predictions are verified against experimental result. It shows that the both modeling approaches obtain similar results in modal analysis, and in each numerical model, a consistent natural frequency mismatch was found to compare with the experimental modal analysis. A Frequency Response Function (FRF) comparison between experimental measurement and equivalent properties modeling approach also carried out to check its dynamic prediction capability. A simple model updating has been carried out at the end; the updated numerical models exhibit a good consistency with experimental measurement.

On Feedback Architectures With Zero-Vibration Signal Shapers

  • Authors: Vyhlídal, T., doc. Ing. Martin Hromčík, Ph.D., Kučera, V., Anderle, M.
  • Publication: IEEE Transactions on Automatic Control. 2016, 61(8), 2049-2064. ISSN 0018-9286.
  • Year: 2016
  • DOI: 10.1109/TAC.2015.2492502
  • Link: https://doi.org/10.1109/TAC.2015.2492502
  • Department: Department of Control Engineering
  • Annotation:
    The classical and recent feedback solutions for signal shapers are reviewed and critically analyzed in this paper. Based on this assessment, a new effective feedback control architecture is proposed, suitable for manipulation of weakly damped flexible structures. More specifically, we propose to include the inverse of a signal shaper’s dynamics in the feedback path, and we justify this architecture by analysis of important feedback loop channels, namely the feedback responses from input disturbance to output and from reference to output. Both the classical ZV shaper with one lumped delay, and more recent shapers with distributed delays are considered and analyzed. The most appreciated features of suitable distributed-delay shapers are retarded characteristics—the closed-loop spectrum does not exhibit highfrequency roots close to the imaginary axis (in contrast to ZV shapers)—and at the same time reduced sensitivity of the closed loop interconnection to output disturbances. Feedback performance is demonstrated by two laboratory experiments.

Optimization of control law for vibration suppression of planar structure with collocated actuators and sensors

  • Authors: Krejza, R., Šika, Z., Beneš, P., doc. Ing. Martin Hromčík, Ph.D., Zavřel, J.
  • Publication: Bulletin of Applied Mechanics. 2016, 12(41), 17-20. ISSN 1801-1217.
  • Year: 2016
  • Department: Department of Control Engineering
  • Annotation:
    The paper describes the investigation of using collocated control for active vibration suppression. Simple proportional velocity-feedback loops are applied to each sensor/actuator pair. Several variant with different densities of collocated pair have been tested for planar mass-spring system. Two version of objective function have been used for optimization. Main targets are the efficiency, power consumption and stability of the system.

Active Gust Load Alleviation System for Flexible Aircraft: Mixed Feedforward/Feedback Approach

  • DOI: 10.1016/j.ast.2014.12.020
  • Link: https://doi.org/10.1016/j.ast.2014.12.020
  • Department: Department of Control Engineering
  • Annotation:
    Lightweight flexible blended-wing-body (BWB) aircraft concept seems as a highly promising configuration for future high capacity airliners which suffers from reduced stiffness for disturbance loads such as gusts. A robust feedforward gust load alleviation system (GLAS) was developed to alleviate the gust loading. This paper focuses on designing a feedback controller which would improve the robust performance of the feedforward controller in reducing the peaks in wing root moments at very short gust lengths. The simulation results show that when the new feedback compensator is engaged with the feedforward controller, the performance of the GLAS system is improved significantly in terms of reduction in wing root moments for shorter as well as for longer gusts. This reduction in the wing root moment's peaks provides potential structural benefits and weight savings.

Feed-Forward Control Designs

  • DOI: 10.1007/978-3-319-10792-9_7
  • Link: https://doi.org/10.1007/978-3-319-10792-9_7
  • Department: Department of Control Engineering
  • Annotation:
    The potential advantages of blended wing body (BWB) aircrafts in terms of fuel efficiency are opposed by technical challenges such as the alleviaton of gust loads. Due to low wing loading, gusts generally have a more severe impact on BWB aircraft than on conventional aircraft wing tube aircraft.

INVESTIGATION OF LINEAR QUADRATIC REGULATOR DECENTRALIZATION PROPERTIES FOR A CLAMPED-CLAMPED BEAM

  • Department: Department of Control Engineering
  • Annotation:
    Heavy computational burden is imposed on centralized controllers when dampening vibration for large-scale flexible structures. For homogeneous flexible structures, the structure of controllers shall be investigated to simplify the control loop design. In this work, firstly a linear-quadratic regulator (LQR) is designed for a normalized infinite-dimensional beam model under a clamped-clamped boundary condition, to demonstrate the decentralization property of the controller. A finite element model (FEM) based on Euler-Bernoulli beam theory is then considered, an LQR is designed with distributed actuators and isolated point-actuators respectively, providing all the states can be measured. Control simulations have shown a decentralization property in both cases, which motivates a decentralized controller inherited from the LQR design. Simulation results have shown that the performance of decentralized controller and the LQR is comparable.

On zero-vibration signal shapers and a wave-absorbing controller for a chain of multi-agent dynamical systems

  • DOI: 10.1109/ECC.2015.7330676
  • Link: https://doi.org/10.1109/ECC.2015.7330676
  • Department: Department of Control Engineering
  • Annotation:
    The paper brings together two different approaches for control of chain of oscillatory lumped-parameter multi-agent systems. Namely, the multi-mode zero-vibration input shaper and the wave-absorbing controller are recalled and the similarities and links between them are broadly discussed. The special case of identical agents with a double-integrator character is at the focus throughout the paper. The report reveals that the two approaches are closely related in spite of the fact that they differ significantly in all aspects, from motivation through computational algorithms to target implementation. In addition, the presented numerical results, mostly based on numerical simulations at this moment, show that the two methods can be combined together, to take advantage of both an appropriate initial excitation of the system by the input shaper and of increased robustness coming from the wave-absorber feedback architecture. Such a combined control law is based on a special property of the multi-mode zero vibration input shaper - namely the convergence of its impulse response, as the number of agents increases, to a double bell-shaped function.

On-line on-board wind estimation system for small UAVs

  • Authors: Mondek, M., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Proceedings of the 20th International Conference on Process Control. Piscataway: IEEE, 2015. pp. 369-374. ISBN 978-1-4673-6627-4.
  • Year: 2015
  • Department: Department of Control Engineering
  • Annotation:
    This paper describes the status, achieved results and future research plans related to a student's project of an on-line on-board wind estimation system. The system is planned to augment functionality and improve performance of existing small UAV flight control system units, developed within students activities at the Department of Control Engineering, Faculty of Electrical Engineering, Czech Technical University in Prague. Simulated data are prepared based on realistic flight mechanics models. Simple algorithms are adopted from literature and tailored for our case and their sensitivity to measurement errors is carefully analyzed. Finally, performance of the algorithms is demonstrated in realistic simulation scenarios. Related hardware components are also introduced and discussed in brief and the future plans are elaborated.

Parameterization of input shapers with delays of various distribution

  • DOI: 10.1016/j.automatica.2015.06.025
  • Link: https://doi.org/10.1016/j.automatica.2015.06.025
  • Department: Department of Control Engineering
  • Annotation:
    The paper introduces a new concept for composing the input shapers by combining lumped and distributed delays. Particularly, an analytical method is proposed to parametrize zero vibration shapers with delays of various distribution. Involving these delays in the shaper structure, the accommodation part of the shaped response can be smoothened in a predefined manner, retarded spectral properties can be achieved and the response length can be optionally adjusted within the given range. Next, following the analytical developments, a numerical algorithm based on the constrained linear least squares optimization is proposed for direct design of robust distributed delay shapers.

Double oscillatory mode compensation by inverse signal shaper with distributed delays

  • Authors: Vyhlídal, T., doc. Ing. Martin Hromčík, Ph.D., Kučera, V., Anderle, M.
  • Publication: Proceedings of the European Control Conference. Piscataway: IEEE, 2014. pp. 1121-1126. ISBN 978-3-9524269-1-3.
  • Year: 2014
  • DOI: 10.1109/ECC.2014.6862561
  • Link: https://doi.org/10.1109/ECC.2014.6862561
  • Department: Department of Control Engineering
  • Annotation:
    Signal shaping technique can be distinguished as a very effective tool for suppressing both single and multiple oscillatory modes of system linked with the shaper. Utilizing the concept of inverse signal shapers placed in the feedback loop, the double oscillatory mode suppression is addressed, considering that the oscillations induced by both the reference signal and the disturbance changes are to be compensated. In order to avoid the closed loop neutrality of the dynamics, the lumped delay that is usually considered in the shaper structure is substituted by a distributed delay. Next to the theoretical analysis, both the numerical and experimental examples are included.

ZERO VIBRATION DERIVATIVE SHAPERWITH DISTRIBUTED DELAY FOR BOTH FEED-FORWARD AND FEEDBACK INTERCONNECTIONS

  • Authors: Vyhlídal, T., doc. Ing. Martin Hromčík, Ph.D., Kučera, V., Anderle, M.
  • Publication: Proceedings of the 6th International Symposium on Communications, Control and Signal Processing. University of Patras, 2014, pp. 270-273. ISBN 978-1-4799-2890-3.
  • Year: 2014
  • DOI: 10.1109/ISCCSP.2014.6877866
  • Link: https://doi.org/10.1109/ISCCSP.2014.6877866
  • Department: Department of Control Engineering
  • Annotation:
    Using a distributed delay as the key element, a novel zero vibration derivative (DZVD) shaper is introduced with the objective to suppress effectively and robustly an undesirable oscillatory mode of a controlled system. Compared to the classical ZVD shaper with a lumped delay, the DZVD shaper is less sensitive to system-model mismatch in higher frequency range. Various aspects of the novel shaper are studied, particularly the spectral patterns, time responses, and sensitivity features. Next, the closed loop architecture with an inverse implementation of the shaper is considered with the aim to suppress robustly the vibrations induced by both the set-point and disturbance changes.

Experimental comparison of signal shapers with lumped and distributed delays

  • Authors: Kučera, V., doc. Ing. Martin Hromčík, Ph.D., Vyhlídal, T.
  • Publication: Proceedings of the 2013 International Conference on Process Control. Piscataway: IEEE, 2013, pp. 371-376. ISBN 978-1-4799-0927-8.
  • Year: 2013
  • DOI: 10.1109/PC.2013.6581439
  • Link: https://doi.org/10.1109/PC.2013.6581439
  • Department: Department of Control Engineering
  • Annotation:
    This paper presents some applications of the techniques well known as input shaping, focused on control of flexible structures. Zero Vibration (ZV) shaper defined by a sequence of two impulses can drive a system without undesirable vibrations. Such shaper can be regarded as a time delay system with a standard lumped delay. Alternatively, though, new shapers with increased robustness and more natural response can be devoloped as described in the paper if a distributed delay element is used instead. Performance of the distributed-delay shaper is demonstrated by means of a laboratory experiment and it is compared to the standard limped-delay solution. A setup composed of a lightweight flexible beam attached to the Quanser rotating table is utilized.

Inverse signal shapers in effective feedback architecture

  • Authors: Vyhlídal, T., doc. Ing. Martin Hromčík, Ph.D., Kučera, V.
  • Publication: Proceedings of the European Control Conference. Zurich: European Control Association, 2013. p. 4418-4423. ISBN 978-3-033-03962-9.
  • Year: 2013
  • Department: Department of Control Engineering
  • Annotation:
    New feedback control architecture is proposed in this paper suitable for manipulation of weakly damped flexible structures. Delay-based signal shapers are considered since they are very popular in such applications for their simple implementation and very good performance. Unlike the classical approach where the shapers are used just to filter the reference command, we consider placing it inside the closed loop. Compared to previous attempts, we propose to include the inverse of the signal shaper’s dynamics in the feedback path. This architecture is justified by thorough analysis of important feedback loop channels, namely the feedback response from input disturbance to the output. As results from the spectral properties, classical ZV shapers with lumped delays are very inconvenient for the shaper inverse operation, leading to neutrality of the dynamics with the associated risks of stability loss due to high frequency unstable modes. Therefore, a recently introduced DZV shaper with a distributed delay element is utilized in the feedback loop. Results are verified by simulations and experiments.

Signal shaper with a distributed delay: Spectral analysis and design

  • DOI: 10.1016/j.automatica.2013.08.029
  • Link: https://doi.org/10.1016/j.automatica.2013.08.029
  • Department: Department of Control Engineering
  • Annotation:
    Input shapers with time delays have proved useful in many applications related to controls for various oscillatory devices, for example flexible manipulators and cranes. In the paper, a novel approach for designing a zero-vibration signal shaper based on equally distributed delay is proposed. The parameter assessment of the shaper is based on the spectral approach. Various characteristics of the shaper are analyzed and compared with the classical zero-vibration shaper with a lumped delay. The analysis shows that the novel shaper is a slower, but more robust alternative to the classical shaper. Besides, the discrete implementation of the shaper is proposed and tested. It includes zero placement based parameter adjustment with the objective to preserve full compensation of the oscillatory mode by the discrete algorithm.

Spectral features of ZVD shapers with lumped and distributed delays

  • Authors: Vyhlídal, T., Kučera, V., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Proceedings of the 9th Asian Control Conference (ASCC 2013). New York: IEEE Control System Society, 2013. ISBN 978-1-4673-5769-2.
  • Year: 2013
  • DOI: 10.1109/ASCC.2013.6606315
  • Link: https://doi.org/10.1109/ASCC.2013.6606315
  • Department: Department of Control Engineering
  • Annotation:
    An interesting spectral property, related to sensitivity of ZVD shaper zeros with respect to small deviations of involved delays, is presented in the paper. Consequences concern namely feedback interconnections as indicated in the report. Compared to the lumped-delay case, the recently proposed distributed delay alternative - ZVD shaper with distributed delay - is a more robust option, as explained and demonstrated by means of roots diagrams. Several examples are presented to demonstrate the phenomena.

Zero vibration shapers with distributed delays of various types

  • Authors: Vyhlídal, T., Kučera, V., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Proceedings of the 52nd IEEE Conference on Decision and Control. Piscataway: IEEE, 2013. pp. 940-945. ISSN 0191-2216. ISBN 978-1-4673-5717-3.
  • Year: 2013
  • DOI: 10.1109/CDC.2013.6760003
  • Link: https://doi.org/10.1109/CDC.2013.6760003
  • Department: Department of Control Engineering
  • Annotation:
    The paper deals with design and analysis of novel zero-vibration (ZV) signal shapers. The shaper structure is based on replacing the lumped delay of the classical ZV shaper by a series of lumped and either equally or triangularly distributed delays. For the parametrization purposes, the spectral theory of time delay systems is applied with the aid of numerical tool for computation of rightmost part of infinite spectra of shaper zeros. In the analysis performed, the novel shapers show better spectral, step response and robustness features compared to the classical ZV shaper in some aspects. An experimental example is included to demonstrate the novel shaper performance.

BWB Aircraft Control System of Fixed Structure

  • Department: Department of Control Engineering
  • Annotation:
    Optimal and robust control laws for upcoming high-capacity passenger aircraft are proposed in the paper. The delivered controllers are obtained by modern non-convex non-smooth optimization approach and feature very good performance, low complexity, and respect prescribed structure of the control architecture. Simulation results for a BWB near-future airliner are presented and discussed.

Delay-Based Shapers for Controlling Vibration in Future Aircraft

  • Authors: Kučera, V., doc. Ing. Martin Hromčík, Ph.D., Vyhlídal, T.
  • Publication: Proceedings of the 13th Mechatronics Conference. Linz: Universität Linz, 2012. pp. 267-272. ISBN 978-3-99033-042-5.
  • Year: 2012
  • Department: Department of Control Engineering
  • Annotation:
    Signal shapers are powerful tool for control vibration of mechanical systems. This approach shapes reference command so that response is without vibration in ideal case. No disturbance rejection is proposed by this technique. In airspace application is commonly used low pass filters of any type. Signal shapers are alternatives with can reach better performance and also satisfying robustness against uncertainty parameters in different flight condition. Case study of ACFA 2020 flexible aircraft in our control strategy proposed several levels of control system.

Dynamic Causal Modeling and subspace identification methods

  • Authors: Nováková, J., doc. Ing. Martin Hromčík, Ph.D., Jech, R.
  • Publication: Biomedical Signal Processing and Control. 2012, 7(4), 365-370. ISSN 1746-8094.
  • Year: 2012
  • DOI: 10.1016/j.bspc.2011.07.002
  • Link: https://doi.org/10.1016/j.bspc.2011.07.002
  • Department: Department of Control Engineering
  • Annotation:
    The main contribution of the paper is in formulating the problem of detection of brain regions structure within the framework of dynamic system theory. The motivation is to see if the mature domain of experimental identification of dynamic systems can provide a methodology alternative to Dynamic Causal Modeling (DCM) which is currently used as an exclusive tool to estimate the structure of interconnections among a given set of brain regions using the measured data from functional magnetic resonance imaging (fMRI). The key tool proposed for modeling the structure of brain interconnections in this paper is subspace identification methods which produce linear state-space model, thus neglecting the bilinear term from DCM. The procedure is illustrated using a simple two-region model with maximally simplified linearized hemodynamics. We assume that the underlying system can be modeled by a set of linear differential equations, and identify the parameters (in terms of state space matrices).

Flexible aircraft lateral control law of low order

  • Department: Department of Control Engineering
  • Annotation:
    Overview of European collaborative project is presented in this paper and some results on lateral control law design for Blended Wing Body (BWB) type aircraft are given. Rigid body motions as well as flexible dynamic of the aircraft are considered. Recently developed H∞ optimization tools for fixed order robust controller are used to device lateral control augmentation system (CAS) with extremely low complexity.

Input shapers with uniformly distributed delays

  • Authors: Vyhlídal, T., Kučera, V., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Proceedings of the 10th IFAC Workshop on Time Delay Systems. New York: IFAC, 2012. p. 91-96. Time Delay Systems. ISSN 1474-6670. ISBN 978-3-902823-04-5.
  • Year: 2012
  • DOI: 10.3182/20120622-3-US-4021.00034
  • Link: https://doi.org/10.3182/20120622-3-US-4021.00034
  • Department: Department of Control Engineering
  • Annotation:
    Input shapers with time delays have proved useful in many applications related to controls for various flexible devices, for example flexible manipulators and cranes. In the paper, modifications of classical signal shapers ZV (zero vibration) and ZVD (zero vibration derivative) that use uniformly distributed delays instead of lumped delays are proposed. The shaper parameters, i.e. gains and time delays, are determined using spectral approach. The objective is to compensate the undesired oscillatory couple of system poles by the dominant couple of shaper zeros. Next, the spectral and frequency features as well as robustness issues are investigated. In all these aspects, the shapers with distributed delays show better characteristics compared to classical signal shapers. The theoretical results are verified on a laboratory crane system.

Optimal sensors placement and spillover suppression

  • DOI: 10.1016/j.ymssp.2011.12.007
  • Link: https://doi.org/10.1016/j.ymssp.2011.12.007
  • Department: Department of Control Engineering
  • Annotation:
    A newapproachtooptimalplacementofsensors(OSP)inmechanicalstructuresis presented.Incontrasttoexistingmethods,thepresentedprocedureenablesadesigner to seekforatrade-offbetweenthepresenceofdesirablemodesincaptured measure- ments and theeliminationofinfluenceofthosemodeshapesthatarenotofinterestina givensituation.Anefficientnumericalalgorithmispresented,developedfroman existingroutinebasedontheFischerinformationmatrixanalysis.Weconsidertwo requirementsintheoptimalsensorplacementprocedure.OntopoftheclassicalEFI approach,thesensorsconfigurationshouldalsominimizespilloverofunwantedhigher modes.WeusetheinformationapproachtoOSP,basedontheeffectiveindependent method(EFI),andmodifytheunderlyingcriteriontomeetbothofour requirements-to maximizeusefulsignalsandminimizespilloverofunwantedmodesatthesametime. Performanceofourapproachisdemonstratedbymeansofexamples,andaflexible BlendedWingBody(BWB)aircraftcasestudyrelatedtoarunningEuropean-levelFP7 researchproject'ACFA2020-ActiveControlforFlexible

Delay-based input command shapers: frequency properties and finite-dimensional alternatives

  • Authors: Kučera, V., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Proceedings of the 18th IFAC World Congress, 2011. Bologna: IFAC, 2011, pp. 7565-7570. ISSN 1474-6670. ISBN 978-3-902661-93-7.
  • Year: 2011
  • Department: Department of Control Engineering
  • Annotation:
    ZV, ZVD, EI, and other related delay-based input command shapers have been in the center of attention for decades and have given rise to many papers focusing on new more robust and/or optimal additions to the classical Smiths 1950s PosiCast idea. All considerations are nevertheless based almost purely on the time-domain reasoning, accompanied by some simple zero-pole plots. However, these shapers are in fact ordinary LTI systems (linear, time invariant), though infinite-dimensional (w/o finite state space representation, due to presence of delays), and feature interesting frequency notch-filter-like behaviour. The paper is devoted to presentation and discussion of the shapers' frequency responses, and to suggestions for finite dimensional (read: low order rational-transfer-function) alternatives, with implications towards practical implementation and feedback interconnections with input shapers. Performance of such filters is then assesed by means of a case study.

Delay-based input shapers in feedback interconnections

  • Authors: Kučera, V., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Proceedings of the 18th IFAC World Congress, 2011. Bologna: IFAC, 2011, pp. 7577-7582. ISSN 1474-6670. ISBN 978-3-902661-93-7.
  • Year: 2011
  • Department: Department of Control Engineering
  • Annotation:
    A design method for a feedback controller with integrated delay-based command shaper is presented in this paper, based on the Smith predictor concept. PosiCast and related input command shapers (ZV, ZVD, EI etc.) are primarily intended as feedforward filters for reference (set point) signals. Nevertheless, due to their superior effectiveness in suppressing vibrations, there is a good motivation to incorporate them directly into positioning feedback loops for flexible structures. Compared to a purely feedforward setup, the feedback control system is commanded not to excite flexible vibrations by aggressive response of the controller, designed purely for the rigid body dynamics, to unmeasurable disturbances, not only to known reference command. If the shaper is tuned carefully to the flexible mode(-s) of interest, the overall feedback appears fast and responsive compared to the conventional approach of a simple high-frequency-roll-off compensator.

Delay-based signal shapers and ACFA 2020 BWB aircraft FCS

  • Department: Department of Control Engineering
  • Annotation:
    The purpose of this report is twofold. First: results related to application of signal shapers, imposed on pilot's commands, in cooperation with feedback flight control system (FCS) are reported for the case of ACFA 2020 blended-wing-body design. The results suggest that signal shapers can cooperate nicely both with FCS focused on the rigid body dynamics only. In both cases, the amount of vibrations due to pilot's inputs (manoeuvres) can be substantially reduced. Second: combination of signal shapers and rate-limiters is discussed in detail. Rate-limiters, representing finite achievable rates of servos for control surfaces, deteriorate considerably performance of the delay-based shapers. Standard versions of the shapers cannot be therefore directly applied, especially for higher control surfaces deflections. Instead, two efficient alternatives can be used, suggested in the paper, that take the rate limitations into account at the design stage already.

Feed-Forward Delay-based Input Shaper Confrontation With Active Feedback Control

  • Authors: Kučera, V., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: IDAACS'2011 - Proceedings of the 6th IEEE International Cnonference on Intelligent Data Acquisition and Advanced Computing Systems. Prague: IEEE, THEY, CTU, 2011, pp. 1-5. ISBN 978-1-4577-1423-8.
  • Year: 2011
  • Department: Department of Control Engineering
  • Annotation:
    The main focus of this paper is confrontation and summarize advantages and disadvantages of a passive feed-forward control based on impulse input shapers and active feedback approach for vibration control design for flexible structures [5], [10] like robotics arms, flexible beams, manipulator [11], [14], and so on. ZV, ZVD, EI [2], [6], [7] and other input command shapers have been studied for last two decades and have given rise to many papers and applications oriented on feed-forward, non-measurable disturbances vibration reduction in machines controlled by computer. The main advantages are optimal response, in a sense of dead beat compensation, with the fastest response respect to bounded actin command and easy implementation

Information-based sensor placement optimization for BWB aircraft

  • Department: Department of Control Engineering
  • Annotation:
    Information approach to optimal sensor placement is called to assign accelerometers as effective indicators of flexible vibrations in a next-generation large passenger blended-wing-body aircraft (BWB). This step presents a crucial prerequisite for the subsequent design of active dampers, either separately or as a part of integrated flight controls / active damping systems. Results of the classical Fisher information matrix algorithm (FIM) are presented first. Their interpretation in terms of spillover of higher modes leads to a modification of the FIM routine that explicitly cares for the spillover issues and gives rise to slightly different and more convenient suggestions for the BWB sensor positions.

Lateral control for flexible BWB high-capacity passenger aircraft

  • Department: Department of Control Engineering
  • Annotation:
    Two different approaches for design of lateral control augmentation system for large blended-wing-body aircraft (BWB) with flexible structure are presented and asses in this paper. The most challenging issue is handling of rigid-body dynamics and flexible modes coupling. First, a more classical approach is employed giving rise to separate flight dynamics controller (H2 optimal, with sufficient roll-off) and an active damper for most prominent lateral flexible modes on top of that (mixed-sensitivity Hinf design). This approach proves successful and has obvious advantages related to the design process complexity, or implementation and testing issues. On the other hand, there is always a risk of potentially significant performance loss compared to a fully integrated design. For this reason, fully integrated design is also presented in the form of a fixed-order MIMO Hinf optimal FCS controller, obtained by means of direct non-convex non-smooth optimization package HIFOO.

Lateral Flight Dynamic Controller for Flexible BWB Aircraft

  • Department: Department of Control Engineering
  • Annotation:
    Two different approaches for design of lateral control augmentation system for large blended-wing-body aircraft (BWB) with flexible structure are presented and asses in this paper. The most challenging issue is handling of rigid-body dynamics and flexible modes coupling. First, a more classical approach is employed giving rise to separate flight dynamics controller (H2 optimal, with sufficient roll-off) and an active damper for most prominent lateral flexible modes on top of that (mixed-sensitivity H∞ design). This approach proves successful and has obvious advantages related to the design process complexity, or implementation and testing issues. On the other hand, there is always a risk of potentially significant performance loss compared to a fully integrated design. For this reason, fully integrated design is also presented in the form of a fixed-order MIMO H∞ optimal FCS controller, obtained by means of direct non-convex non-smooth optimization package HIFOO.

Lobster eye optics for nano-satellite X-ray monitor

  • Authors: Tichý, V., Barbera, M., Collura, A., doc. Ing. Martin Hromčík, Ph.D., prof. RNDr. René Hudec, CSc., Inneman, A., Maršík, J., Maršíkova, V., Pína, L., Šimon, V., Varisco, S.
  • Publication: EUV AND X-RAY OPTICS: SYNERGY BETWEEN LABORATORY AND SPACE II. Bellingham (stát Washington): SPIE, 2011. Proceedings of SPIE. ISSN 0277-786X. ISBN 9780819486660.
  • Year: 2011
  • DOI: 10.1117/12.886809
  • Link: https://doi.org/10.1117/12.886809
  • Department: Department of Control Engineering, Department of Radioelectronics
  • Annotation:
    The Lobster eye design for a grazing incidence X-ray optics provides wide field of view of the order of many degrees, for this reason it would be a convenient approach for the construction of space X-ray monitors. In this paper, we compare previously reported measurements of prototype lobster eye X-ray optics called P-25 with computer simulations and discuss differences between the theoretical end experimentally obtained results. Usability of this prototype lobster eye and manufacturing technology for the nano-satellite mission is assessed. The specific scientific goals are proposed.

Low Order H∞Optimal Control for ACFA Blended Wing Body

  • Department: Department of Control Engineering
  • Annotation:
    Advanced non-convex non-smooth optimization techniques for fixed-order H infinity robust control are proposed in this paper for design of flight control systems (FCS) with prescribed structure. Compared to classical techniques - tuning of and successive closures of particular single-input single-output (SISO) loops like dampers, attitude stabilizers etc. - all loops are designed simultaneously by means of quite intuitive weighting filters selection. In contrast to standard optimization techniques, though (H2, H∞ optimization), the resulting controller respects the prescribed structure in terms of engaged channels and orders (e.g. P, PI, PID controllers). In addition, robustness w.r.t. multi model uncertainty is also addressed which is of most importance for aerospace applications as well

Preliminary tests of commercial imagers for nano-satellite attitude determination

  • Authors: Tichý, V., Fullmer, Rees, Fowler, David, doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Proceedings of SPIE Vol. 8073 - Optical Sensors 2011; and Photonic Crystal Fibers V. Bellingham: SPIE, 2011. pp. 1-9. Proceedings of SPIE. ISSN 0277-786X. ISBN 978-0-8194-8663-9.
  • Year: 2011
  • DOI: 10.1117/12.886743
  • Link: https://doi.org/10.1117/12.886743
  • Department: Department of Control Engineering
  • Annotation:
    Star cameras represent a well-known class of attitude determination sensors. At this time, they achieve excellent accuracy within arc-seconds. However their size, mass, power, and cost make current commercial versions unacceptable for use on nano-satellites. Here, the concept of developing a small star camera with very modest accuracy requirements for future nano-satellite missions is studied. A small commercial cmos sensor with minimal commercial optics is presented. This camera\'s field-of-view is approximately 50 × 40 degrees and can capture stars of magnitudes smaller than 3 with acquisition times of 100ms. The accuracy of attitude determination methods using data collected by this camera was tested by taking photos of the night sky under terrestrial conditions. The camera attitude was determined using offline image processing and star field attitude determination algorithms. Preliminary attitude accuracy results were determined and they are presented.

Signal Shapers for BWB Aircraft Control

  • Authors: Kučera, V., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Proceedings of the 18th International Conference on Process Control. Bratislava: Slovenská technická univerzita, 2011, pp. 307-311. ISBN 978-80-227-3517-9. Available from: http://www.kirp.chtf.stuba.sk/pc11/data/abstracts/074.html
  • Year: 2011
  • Department: Department of Control Engineering
  • Annotation:
    This article shows results related to application of impulse signal shapers (ZV, ZVD, EI), applied on reference signal as a feed-forward vibration compensator for pilot commands incorporated with feedback control system (FCS) design for blended-wing-body aircraft (ACFA 2020). The results are nicely indicating ability of connection feed-forward approach for reducing vibration cooperation with active damping. Other goals are study signal shapers design for hard nonlinearities in elevator and ailerons like saturation and rate limiters, induce by finite rates and deflection of servomechanism of control surface. Standard design can't be directly used for higher deflection of elevator and ailerons, because nonlinearities deform shaped command. Two efficient modifications used as alternatives to standard shapers configuration, suggested in the article, permit application of the feed-forward compensation in respect of this setup.

Tests of Lobster Eye Optics for Small Space X-ray Telescope

  • Authors: Tichý, V., Barbera, M., Collura, A., doc. Ing. Martin Hromčík, Ph.D., prof. RNDr. René Hudec, CSc., Inneman, A., Jakůbek, J., Maršík, J., Maršíková, V., Pína, L., Varisco, S.
  • Publication: Nuclear Instruments and Methods in Physics Research, Section A, Accelerators, Spectrometers, Detectors and Associated Equipment. 2011, 633(1), S169-S171. ISSN 0168-9002.
  • Year: 2011
  • DOI: 10.1016/j.nima.2010.06.157
  • Link: https://doi.org/10.1016/j.nima.2010.06.157
  • Department: Department of Control Engineering, Department of Radioelectronics
  • Annotation:
    The Lobster eye design for a grazing incidence X-ray optics provides wide field of view of the order of many degrees, for this reason it can be a convenient approach for the construnction of space all-sky X-ray monitors. We present preliminary results of tests of prototype lobster eye X-ray optics in quasi parallel beam full imaging mode conducted using the 35 meters long X-ray beam-line of INAF-OAPA in Palermo (Italy). X-ray images at the focal plane have been taken with a MCP detector at several energy values from 0.3 keV to 8 keV. The gain, the field of view and the angular resolution have been measured and compared with theoretical values.

Complete Fast Analytical Solution of the Optimal Odd Single-Phase Multilevel Problem

  • DOI: 10.1109/TIE.2009.2034677
  • Link: https://doi.org/10.1109/TIE.2009.2034677
  • Department: Department of Control Engineering
  • Annotation:
    In this paper we focus on computation of optimal switching angles for general multilevel odd symmetry waveforms. We show that this problem is similar to (but more general than) the PWM modulation problem which is an established method of generating PWM waveforms with low base-band distortion. We introduce a new general modulation strategy for multilevel inverters which takes an analytic form and is very fast with the complexity of only O(n log^2 n) arithmetic operations where n is the num. of controlled harmonics. This alg. is based on a transf. of appropriate trigonometric eqs. for each controlled harmonics to a poly. system of eqs. that is further transformed to a special sys. of composite sum of powers. The solution of this sys. is carried out by a modification of the Newton's identity via Pade approx., formal ortho. poly. theory, and properties of symmetric poly. Finally, the optimal switching sequence is obtained by computing zeros of two formal ortho. poly. in one variable.

Repetitive TMS of the somatosensory cortex improves writer's cramp and enhances cortical activity

  • Authors: Havránková, P., Jech, R., Walker, Nolan D., Operto, G., Nováková, J., Vymazal, J., Dušek, P., doc. Ing. Martin Hromčík, Ph.D., Růžička, E.
  • Publication: Neuroendocrinology Letters. 2010, 31(1), 73-86. ISSN 0172-780X.
  • Year: 2010
  • Department: Department of Control Engineering
  • Annotation:
    We focused on the modulation of the primary somatosensory cortex (SI) induced by repetitive transcranial magnetic stimulation (rTMS) in order to improve symptoms of writer's cramp. Patients with writer's cramp were treated with 30-minute 1 Hz real- or sham-rTMS of the SI cortex every day for 5 days. 1.5 T fMRI was examined during simple hand movements. While in the pilot study the rTMS coil was navigated over the SI cortex, patients in the advanced study had the coil above the postcentral sulcus. After real-rTMS, 4 pilot study patients and 10 advanced study patients experienced subjective and objective improvement in writing. Patients exhibited a rTMS-induced BOLD signal increase bilaterally in the SI cortex, posterior parietal cortex and in the supplementary motor area (P<0.001 corrected). After sham-rTMS, no BOLD signal changes were observed. In conclusion, 1 Hz rTMS of the SI cortex can improve writer's cramp while increasing the cortical activity in both hemispheres.

Active x-ray optics

  • Authors: prof. RNDr. René Hudec, CSc., doc. Ing. Martin Hromčík, Ph.D., Elvis, M., Gedeon, O.
  • Publication: Proc. SPIE 7360, EUV and X-Ray Optics: Synergy between Laboratory and Space. Bellingham (stát Washington): SPIE, 2009. p. 736009-736009-8. Proceedings of SPIE. vol. 7360. ISSN 0277-786X. ISBN 978-0-8194-7634-0.
  • Year: 2009
  • Department: Department of Control Engineering, Department of Radioelectronics
  • Annotation:
    There is a growing need for multiply nested large area X-ray mirrors with very fine angular resolution in future X-ray astrophysics experiments. Despite of promising results of several exploited technologies, it is not demonstrated yet that these technologies will provide the required angular resolutions of order of few arcsec. The alternative approach described in this paper is the method of active X-ray optics. In addition, active approaches based on computer control may be applied directly during manufacturing of advanced X-ray optics elements. We propose these methods as an alternative for the IXO project recently under study by ESA/NASA/JAXA.

Applications of the Medipix Type Detectors Combined with X-Ray Optics

  • Authors: Tichý, V., doc. Ing. Martin Hromčík, Ph.D., Jakůbek, J.
  • Publication: Workshop 09 CTU REPORTS. Praha: České vysoké učení technické v Praze, 2009. pp. 136-137. ISBN 978-80-01-04286-1.
  • Year: 2009
  • Department: Department of Control Engineering
  • Annotation:
    Experimental results showing applicability of Medipix2 and Timepix devices to be used as detectors for the lobster eye X-ray optics are presented. Measurements shows that the Medipix and Timepix devices operates with the lobster eye optics at chosen energy 8keV. Field of view, spatial resolution, image distortion as function of source position were been estimated. Image distortion is compared with the simulations.

Effective solution of a linear system with Chebyshev coefficients

  • DOI: 10.1080/10652460902727938
  • Link: https://doi.org/10.1080/10652460902727938
  • Department: Department of Control Engineering
  • Annotation:
    This paper presents an efficient algorithm for a special triangular linear system with Chebyshev coefficients. We present two methods of derivations, the first is based on formulae where the nth power of x is solved as the sum of Chebyshev polynomials and modified for a linear system. The second deduction is more complex and is based on the Gauss-Banachiewicz decomposition for orthogonal polynomials and the theory of hypergeometric functions which are well known in the context of orthogonal polynomials. The proposed procedure involves O(nm) operations only, where n is matrix size of the triangular linear system L and m is number of the nonzero elements of vector b. Memory requirements areO(m), and no recursion formula is needed. The linear system is closely related to the optimal pulse-wide modulation problem.

Hardware in the Loop Simulation of FBW components

  • Authors: Doubrava, J., Hanzálek, Z., Waszniowski, L., Hospodář, P., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Proceedings of the AIAA Modeling and Simulation Technologies Conference 2009. Reston: American Institute of Aeronautics and Astronautics, 2009. pp. 240-257.
  • Year: 2009
  • Department: Department of Control Engineering
  • Annotation:
    The paper presents hardware in the loop simulator developed for validation of control algorithms and electro-hydraulic servo actuators designed for flight by wire control system of a small jet plane. The architecture and functionality of the flight by wire system is briefly described and requirements on validation tests to carry out on the hardware in the loop simulator are mentioned. The flight by wire control system under development consist of dual channel flight control computer and dual channel electronic control unite controlling dual channel electro hydraulic servo actuator with mechanical redundancy. It support several control modes as autopilot and recovery mode. An architecture and software and hardware components of the developed simulator and hydraulic stand are described. The simulator instrumentation is based on distributed peripherals communicating via CANopen industrial field bus.

HYBRID CONTROLLER FOR GUST LOAD ALLEVIATION AND RIDE COMFORT IMPROVEMENT USING DIRECT LIFT CONTROL FLAPS

  • Department: Department of Control Engineering
  • Annotation:
    In this paper two robust H(infinite) feedback control laws are designed, one for active wing bending damping, and one for active damping of the wing and hull bending modes. For the latter, not only symmetrically commanded ailerons are used, but also the elevator and direct lift control (DLC) flaps. The control objective of these feedback laws is the reduction of fatigue of the wing roots, as well as the improvement of ride comfort. Two different H(infinite) control design methods, DK iteration and HIFOO, are applied and compared. For the additional compensation of turbulence excited peak loads, the active wing bending damper is augmented by an adaptive feed-forward controller which uses the modified output of an alpha probe mounted at the front fuselage as reference signal. Numeric simulations with a state-space model of the symmetric dynamics of a large airliner are performed for validation of the controllers' performances.

Optimal Sensor placement in flexible structures: Energy vs. Information Based criteria

  • Department: Department of Control Engineering
  • Annotation:
    This paper is concerned with the optimal placement of sensors (OSP) on flexible dynamical structures. In order to get as much information as possible about the system state at any given time - also in terms of robustness with respect to numerical issues and modeling errors or sensor noise - the optimal placement of the sensors is an important system design task. Two different approaches for OSP are considered: The first one maximizes the output information using an iterative elimination algorithm, while the second one evaluates the signal output energy that can be received by the sensors. The contribution of this paper is to emphasize the basic mathematical consistency of these two approaches as well as their application on a simple theoretical example.

Optimal sensors placement and elimination of undesirable mode shapes

  • Department: Department of Control Engineering
  • Annotation:
    A new approach to optimal placement of sensors in mechanical structures is presented. In contrast to existing methods, the presented procedure enables a designer to seek for a trade-off between the presence of desirable modes in captured measurements, and the elimination of influence of those mode shapes that are not of interest in a given situation. An efficient numerical algorithm is presented, developed from an existing routine based on the Fischer information matrix analysis. Performance of our approach is demonstrated be means of two simple textbook examples.

Small X-Ray Telescope Based on Lobster Eye X-Ray Optics and Pixel Detector

  • Authors: Tichý, V., doc. Ing. Martin Hromčík, Ph.D., prof. RNDr. René Hudec, CSc., Inneman, A., Jakůbek, J., Maršík, J., Pína, L., Semencová, V., Švéda, L.
  • Publication: Proc. SPIE 7360, EUV and X-Ray Optics: Synergy between Laboratory and Space. Bellingham (stát Washington): SPIE, 2009. p. 736011-736011-7. Proceedings of SPIE. vol. 7360. ISSN 0277-786X. ISBN 978-0-8194-7634-0.
  • Year: 2009

Tests of Imaging with Lobster-Eye X-Ray Optics and MEDIPIX2 Detector

  • Department: Department of Control Engineering
  • Annotation:
    The results of preliminary experiments with the Medipix2 detector and the lobster-eye optics are presented and discussed. Tests are performed with X-rays having a photon energy of about 8 keV. The field of view and the spatial resolution are determined. The dependence of the image distortion and the intensity on the source position is investigated.

Tests of Lobster-Eye Optics for a Small X-Ray Telescope

  • Department: Department of Control Engineering, Department of Radioelectronics
  • Annotation:
    Two experimental lobster-eye specimens, called P25 and P90, are described. These lobster eyes are built in simple modules, their length does not exceed 1 m and a future version can be held on a small satellite. The results of tests of these modules in visible light are presented.

The first results of systems identification methods for fMRI data

  • Authors: Tauchmanová, J., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: 17th International Conference on Process Control´09. Bratislava: Slovak University of Technology, 2009, pp. 26. ISBN 978-80-227-3081-5. Available from: http://www.kirp.chtf.stuba.sk/pc09/
  • Year: 2009
  • Department: Department of Control Engineering
  • Annotation:
    The main goal of this paper is using identification methods as a certain alternative to Dynamic Casual Modeling (DCM) analysis which detects the so-called intrinsic connections among selected brain areas. In recent years it has been shown that the similar problems, as there appear in functional Magnetic Resonance Imaging(fMRI) area, are formulated in dynamic system identification and estimation tasks. The subspace identification methods were chosen for this identification procedure because they prove good results for Multiple Input Multiple Output (MIMO) systems identification. These methods produce state space description of identified system. The main part of this paper deals with the quality of identification results depending on some important data parameters. Consequently the processing of final state space description into more suitable form follows.

Automatic flight guidance

  • Authors: Hospodář, P., doc. Ing. Martin Hromčík, Ph.D., Pech, Z.
  • Publication: Proceedings of the 8th International Scientific-Technical Conference Process Control 2008. Pardubice: Univerzita Pardubice, 2008, pp. 94. ISBN 978-80-7395-077-4.
  • Year: 2008
  • Department: Department of Control Engineering
  • Annotation:
    Flight guidance belongs to the third hierarchical level of automatic flight control which is accomplished by means of flight control systems in both vertical and horizontal plane as well. Flight guidance consists of numerous flight phases or flight modus, this article deals with several of them. The most important flight phase influencing successfulness the whole flight is final approach with its flight modes LOC, GS, which are controlled by means of radio beams of the Instrument Landing System ILS. Information about angular deviation for simulation in both levels is obtained from following figure. RW system of coordinates is transformed from NED system with using initial conditions (course of runway, initial distance between threshold of runway and position of aircraft). The finish phase after leaving of glide slope beam and before aircraft touchdown - FLARE is here solved by two different arts.

DCM Analysis for Real fMRI Data

  • Authors: Tauchmanová, J., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Proceedings of the 8th International Scientific-Technical Conference Process Control 2008. Pardubice: Univerzita Pardubice, 2008, pp. 103. ISBN 978-80-7395-077-4.
  • Year: 2008

Imaging properties of the lobster eye optics - theory vs. experiment

  • Department: Department of Control Engineering
  • Annotation:
    Lobster eye is a wide field x-ray optics suitable especially for all sky monitors for x-ray astronomy. Two experiments studying the geomterical distortions and source spectrum modifications are described and compared to the simulation.

Inertial Stabilized Camera Platform for UAV

  • Department: Department of Control Engineering
  • Annotation:
    This article introduces a project of an inertially stabilized camera platform featuring an automatic computer-vision based tracking. The device is by most aspects rather standard: double gimbal (azimuth and elevation), direct drives, sliprings, MEMS gyros, incremental encoders, payload formed by a RGB and IR cameras and a laser range-finder.

Numerical algorithms for polynomial plus/minus factorization

  • Department: Department of Control Engineering
  • Annotation:
    Two new algorithms are presented in the paper for the plus/minus factorization of a scalar discrete-time polynomial. The first method is based on the discrete Fourier transform theory (DFT) and its relationship to the Z-transform. Involving DFT computational techniques and the famous fast Fourier transform routine brings high computational efficiency and reliability. The method is applied in the case study of H-2-optimal inverse dynamic filter to an audio equipment. The second numerical procedure originates in a symmetric spectral factorization routine, namely the Bauer's method of the 1950s. As a by-product, a recursive LU factorization procedure for Toeplitz matrices is devised that is of more general impact and can be of use in other areas of applied mathematics as well. Performance of the method is demonstrated by an l(1) optimal controller design example. Copyright (c) 2006 John Wiley & Sons, Ltd.

Optimal PWM problem

  • Department: Department of Control Engineering
  • Annotation:
    Optimal pulse width modulation (PWM) problem, or as sometimes called selected harmonic elimination (SHE) problem, is an established method of generating pulse width modulation waveforms with low baseband distortion. Key issue is to determine the switching times (angles) so as to produce the signal portion (baseband) and not generate specific higher order harmonics. A spectral gap (guard band or zero band) separates the signal portion which has to be identical to the required output signal, from a uncontrolled frequency portion. The required output signal can be recovered by means of a analog low-pass filter (LPF) with cutoff frequency in guard band.

Single-Phase Optimal Odd PWM Problem

  • Department: Department of Control Engineering
  • Annotation:
    Optimal pulse width modulation (PWM) problem is an established method of generating PWM waveforms with low baseband distortion. In this paper we focused on computation of optimal switching angles of a odd PWM waveform for generating general odd symmetric waveforms. We introduce an exact and fast algorithm with the complexity of only O(n log(2) n) arithmetic operations. This algorithm is based on transformation of appropriate trigonometric equations for each harmonies to a polynomial system of equations that is transferred to a special system of sum of powers. The solution of this system is carried out by modification of Newton's identity via Pade approximation and orthogonal polynomials theory and property of symmetric polynomials. Finally, the optimal switching sequence is obtained by computing the zeros of two orthogonal polynomials in one variable

Solving the optimal PWM problem for odd symmetry waveforms

  • Department: Department of Control Engineering
  • Annotation:
    Optimal pulse width modulation (PWM) problem is an established method of generating PWM waveforms with low baseband distortion. In this paper we focused on computation of optimal switching angles of a PWM waveform for generating general odd symmetric waveforms with applications in control. We introduce an exact and fast algorithm with the complexity of only O(n^2) arithmetic operations. This algorithm is based on transformation of appropriate trigonometric equations for each harmonics to a polynomial system of equations that is transferred to a special system of power sums. The solution of this system is carried out by modification of Newton's identity via Pade approximation and orthogonal polynomials theory and property of symmetric polynomials. Finally, the optimal switching sequence is obtained by computing the zeros of two orthogonal polynomials in one variable.

SPM Matlab toolbox

  • Authors: Tauchmanová, J., doc. Ing. Martin Hromčík, Ph.D., Jech, R.
  • Publication: Technical Computing Prague 2008. Praha: Humusoft, 2008, ISBN 978-80-7080-692-0. Available from: http://www.humusoft.cz/akce/matlab08
  • Year: 2008
  • Department: Department of Control Engineering
  • Annotation:
    The SPM toolbox is a noncommercial software for processing fMRI data. The toolbox is developed at the Department of Imaging Neuroscience, University College London. The common application of the SPM toolbox is the first level analysis consisting in the detection of active brain regions for one patient. The second level analysis, also covered by the SPM toolbox, is related to processing of fMRI data across the whole patients group. Besides these functions, the toolbox offers tools for DCM analysis, such as the parameters estimation routines, tools for comparison of resulting models, and a function for averaging models across the whole patients group.

Subspace identification methods and fMRI analysis

  • Authors: Tauchmanová, J., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: IEEE Engineering in Medicine and Biology Society. Piscataway NJ: EMBS Executive Office, 2008. ISSN 1557-170X. ISBN 978-1-4244-1814-5.
  • Year: 2008
  • Department: Department of Control Engineering
  • Annotation:
    The main goal of this paper is to propose application of modern multidimensional systems identification algorithms of the subspace identification theory in the context of fMRI data analysis. The methods originated in 1990s in the field of process control and identification and yield robust linear model parameter estimates for systems with many inputs, outputs and states. Our ultimate goal is to establish an alternative to the DCM analysis procedure which would eliminate its main drawbacks, namely the need to pre-define the models structure. The paper discusses results based on simulated data provided by the DCM simulator in the SPM toolbox. Several scenarios are presented, with varying amount of noise and number of data samples.

Construction of New System of Polynomial Equations for 3-Phase Multilevel Voltage Converter

  • Department: Department of Control Engineering
  • Annotation:
    The main aim of this contribution is presentation a new construction method of a new set of polynomial equations leading to the optimal solution of switching angles which minimize the total harmonic distortion (THD) of a three-phase multilevel converter. The number of equations obtained by this method is lower compared to previous methods. It is possible to solve the problem more simply. This method is based on solution of the single-phase PWM problem which is fast and effcient and gives the conjunction between both problems.

Minimization of l-2 Norm of the Error Signal in Posicast Input Command Shaping: a Polynomial Approach

  • DOI: 10.1002/rnc.1128
  • Link: https://doi.org/10.1002/rnc.1128
  • Department: Department of Control Engineering
  • Annotation:
    In this paper, design of a posicast input command shaper is formulated in discrete-time domain as minimization of l-2 norm of the error sequence. This optimization task is solved by simple algebraic manipulation with polynomials, namely, solving two-sided linear equations with polynomials and modular shift of a polynomial. Numerical examples are given to demonstrate properties of the optimal design in contrast with the classical Smith's design technique achieving complete cancellation of residual vibrations.

New Special System of Polynomial Equations for 3-phase Multilevel Voltage Converter Derived from the PWM Problem for 1-Phase Inverters

  • Department: Department of Control Engineering
  • Annotation:
    This paper contains a new construction method of a new set of polynomial equations leading to the optimal solution of switching angles which minimize the total harmonic distortion (THD) of a three-phase multilevel converter. The number of equations obtained by this method is lower compared to previous methods. It is possible to solve the problem more simply. This method is based on solution of the single-phase PWM problem which is fast and effcient and gives the conjunction between both problems.

Numerical Algorithms for Polynomial Plus/Minus Factorization

  • Department: Department of Control Engineering
  • Annotation:
    Two new algorithms are presented in the paper for the plus/minus factorization of a scalar discrete-time polynomial. The first method is based on the discrete Fourier transform theory (DFT) and its relationship to the Z-transform. Involving DFT computational techniques and the famous fast Fourier transform routine brings high computational efficiency and reliability. The method is applied in the case study of H2-optimal inverse dynamic filter to an audio equipment. The second numerical procedure originates in a symmetric spectral factorization routine, namely the Bauer's method of the 1950s. As a by-product, a recursive LU factorization procedure for Toeplitz matrices is devised that is of more general impact and can be of use in other areas of applied mathematics as well. Performance of the method is demonstrated by an l1 optimal controller design example.

Polynomial Design Methods

  • Department: Department of Control Engineering
  • Annotation:
    Polynomial methods are design techniques for complex multivariable systems, signals and processes encountered in Control, Communications and Computing ("C3" technologies) that are based on manipulations and equations with polynomials, polynomial matrices and similar objects. Systems are described by input-output relations in fractional form and processed using algebraic methodology and tools. The design procedure is thus reduced to algebraic operations with polynomial matrices and similar algebraic objects, typically to solving algebraic polynomial equations. This approach not only makes it possible to solve many existing control problems in an elegant and unifying manner but it also provides further insight into the structure of the control systems and reveals new relationships between various control problems.

Polynomial Toolbox 3.0 and an H2 Optimal Control Case Study

  • Authors: doc. Ing. Martin Hromčík, Ph.D., Kučera, V.
  • Publication: Proceedings of 16th Interantional Conference of Process Control 2007. Slovenská technická univerzita v Bratislave, 2007, ISBN 978-80-227-2677-1.
  • Year: 2007
  • Department: Department of Control Engineering
  • Annotation:
    The purpose of this paper is to introduce the upcoming Version 3 of the Polynomial Toolbox for MATLAB. Researchers within the algebraic control community have been extensively using the Polynomial Toolbox for many years to implement their control design ideas or to process practical control applications. The upcoming new version features many new functions and concepts that were motivated by the users' demands. Next to a brief overview of the Polynomial Toolbox features and functionality, the report contains a case study of the H2 controller design for a MIMO fighter aircraft using the Polynomial Toolbox 3.0 tools. A new approach proposed recently by Kucera (European Journal of Control, to appear) has been employed instead of the traditional H2 polynomial routines of the 1970's and 80's.

Polynomial Toolbox 3.0: A Preview and a Case Study

  • Authors: doc. Ing. Martin Hromčík, Ph.D., Kučera, V.
  • Publication: Proceedings of the European Control Conference 2007. Athens: Technical University Athens, 2007. ISBN 978-960-89028-5-5.
  • Year: 2007
  • Department: Department of Control Engineering
  • Annotation:
    Researchers within the algebraic control community have been extensively using the Polynomial Toolbox for many years to implement their control design ideas or to process practical control applications.The upcoming new version features many new functions and concepts that were motivated by the users' demands. Next to a brief overview of the Polynomial Toolbox features and functionality, the report contains a case study of the H2 controller design for a MIMO fighter aircraft using the Polynomial Toolbox 3.0 tools. A new approach proposed recently by Kucera has been employed instead of the traditional H2 polynomial routens of the 1970's and 1980's.

Report on the 9th European Control Conference ECC'2007

  • Department: Department of Control Engineering
  • Annotation:
    European Control Conference je nejvýznamnější evropské symposium věnované automatickému řízení, pořádané každé dva roky pod záštitou "Asociace EU pro řídící techniku" (European Union Control Association - EUCA). Konference pokrývá všechny aspekty návrhu řídicích systémů. Přednášené příspěvky se týkají jak nových teoretických výsledků teorie řídicích systémů, tak i průmyslových aplikací moderních metod návrhu, modelování a simulace, numerických a symbolických výpočetních metod, nových teoretických poznatků, univerzitního vzdělávání nových inženýrů a dalších oblastí.

Banded Matrix Solvers and Polynomial Diophantine Equations

  • Department: Department of Control Engineering
  • Annotation:
    Numerical procedures and codes for linear Diophantine polynomial equations are proposed in this paper based on the banded matrix algorithms and solvers. Both the scalar and matrix cases are covered. The algorithms and programs developed are based on the observation that a set of constant linear equations resulting from the polynomial problem features a special structure. This structure, known as Sylvester, or block Syelvester in the matrix case, can in turn be accommodated in the banded matrix framework. Reliable numerical algorithms and programs for banded matrices are readily available at present, for instance in the well known LAPACK package.

Banded Matrix Solvers and Polynomial Diophantine Equations

  • Department: Department of Control Engineering
  • Annotation:
    Numerical procedures and programs for linear Diophantine polynomial equations are proposed in this paper based on the banded matrix algorithms and solvers. Both the scalar and matrix cases are covered. The algorithms and programs developed are based on the observation that a set of constant linear equations resulting from the polynomial problem features a special structure. This structure, known as Sylvester, or block Sylvester in the matrix case, can in turn be accommodated in the banded matrix framework. Reliable numerical algorithms and programs for banded matrices are readily available at present, for instance in the well known LAPACK package. Software routines based on dedicated LAPACK band matrix solvers were programmed in the C language and linked to MATLAB, mainly for two reasons: to provide prospective users with an environment most of them are familiar with, and to gain the possibility of direct comparison with related functions of the Polynomial Toolbox for MATLAB.

On Rational Bezout Equation

  • Department: Department of Control Engineering
  • Annotation:
    In this paper the rational Bezout equation is studied. A relationship between the rational Bezout equation and a specific interconnection of linear systems is established and then a numerical procedure for finding a particular solution of the concerned equation is derived. The devised algorithm is applicable to problems of small-to-medium size as demonstrated by numerical experiments.

Rational Bezout Equation and Interconnection of Linear Systems

  • Department: Department of Control Engineering
  • Annotation:
    The Bezout equation over the rings of proper stable rational functions and matrices is studied in this paper. First, a relationship between the rational Bezout equation and a combined serial/parallel interconnection of linear systems is established. The controllability and observability properties that this scheme has to full in order the Bezout equation to be satisfied yield a numerical procedure for finding a particular solution of the concerned equation. This routine is usable for problems of small-to-medium size as demonstrated by numerical experiments.

Web-based MATHEMATICA Platform for Systems and Control Education

  • Department: Department of Control Engineering
  • Annotation:
    MATHEMATICA benefits from its high-level user interface, graphical abilities, as well as numerical and symbolic computational power and dedicated packages for control systems analysis and design (Control Systems Professional and Advanced Numerical Methods). In addition, MATHEMATICA provides a webbased platform for publication of results and presenting usercallable routines (webMATHEMATICA). In the Czech Republic a project financed by the Ministry of Education and called PUMA (Power User Mathematic Array) has been started recently, focused on creation of webaccessible software tools to support education at technical universities. The authors have been involved in these efforts and would like to contribute by creating a web site based on webMATHEMATICA dedicated to numerical and symbolic computations for systems and controls. This paper is the first report on this topic. The work is in rapid progress now and the paper summarizes the authors' plans and first results.

Effective computations with 2-variable polynomial matrices in Mathematica

Effective computations with 2-variable polynomial matrices in Mathematica

New algorithms for doubly comprime faktorization based on ordered real Schur form

  • Department: Department of Control Engineering
  • Annotation:
    A new algorithm for the doubly coprime factorization over the ring of stable proper rational matrices is presented in this report. The method is based on the statespace description of the involved rational functions and relies on previously published algorithms for pole assignment and for the left-to-right matrix fraction conversion by Varga [3], [2]. Numerical properties are demonstrated by means of examples and numerical experiments.

Numerical properties of a polynomial algorithm for solving scalar rational Bezout identity

  • Department: Department of Control Engineering
  • Annotation:
    Numerical properties of a computational algorithm for the scalar Bezout identity in the ring of proper stable rational functions is studied in this paper. The method has been implemented in the MATLAB 6.5 computational environment using the pre-release version 3.0 of the Polynomnial Toolbox and exposed to extensive numerical testing. The results are summarized and some useful guidelines for using this well known algorithm are given.

Using LAPACK Solvers for Structured Matrices within Matlab

  • Department: Department of Control Engineering
  • Annotation:
    Linear polynomial equations, also called Diophantine in the systems and control literature, are often needed to design a dynamic feedback controller or compensator. Solving these equations numerically leads to special Toeplitz type sets of linear equations. To solve them, one can naturally call the general purpose solvers build in the standard MATLAB distribution. Another, and potentially more effective way, is to employ dedicated routines of the well known LAPACK library that exploit the structure of the problem to save computational time and memory requirements. This paper describes the experience of the authors with this approach.

FFT Based Algorithm for Polynomial Plus-minus Factorization

MATLAB Function for Polynomial Plus/Minus Factorization Based on Band Structured Matrix Decomposition

MATLAB Implementation of an FFT Based Algorithm for Polynomial Plus/Minus Factorization

New Algorithm for Plus-Minus Factorization

New Algorithm for Polynomial Plus-Minus Factorization Based on Band Structured Matrix Decomposition

New Package for Effective Polynomial Computation in MATHEMATICA

  • Authors: Kujan, P., doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: Proceedings of the 11th Mediterranean Conference Control and Automation. Athens: Mediterranean Control Assotion, 2003, ISBN 960-87706-0-2.
  • Year: 2003

New Package for effective Polynomial Computation in Mathematica

New Package for Effective Polynomial Computation in Mathematica

Polynomial Matrix Fraction as Models Linear Systems: Theory and Software Tools

Applying the Polynomial Toolbox for Matlab in Mobile Communication Problems

Complex Polynomial Matrices in Signal Processing

  • Authors: doc. Ing. Martin Hromčík, Ph.D.,
  • Publication: POSTER 2002 - Book of Extended Abstracts. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 2002, pp. IC20.
  • Year: 2002

Complex Polynomial Matrices in Signals and Control

Complez Polynomials in Communications: Motivation Algorithms, Software

Effective Polynomial Computations in Mathematica

New Results on FFT-based Methods for Polynomial Matrices

On Computing the l1 Norm of a Polynomial matrix Fraction

Polynomial Spectral Factorization with Complex Coeficients

Fast Fourier Transform and Linear Polynomial Matrix Equations

Linear Polynomial Matrix Equations and FFT

New Algorithm for Spectral Factorization and Its Practical Application

On Computing the H-infinity Norm of a Polynomial Matrix Fraction

On Robust Stability of Complex Polynomial

On Robust Stability of Complex Polynomials

Polynomial Toolbox for Matlab and Complex Polynomials in Communications

Polynomial Toolbox in Control Education

Robust Control Analysis and Design with Polynomial

Some Algorithms Used in the Polynomial Toolbox for Matlab

Fast Fourier Transform and Robustness Analysis with Respect to Parametric uncertainties

Numerical Algorithms for Polynomial Matrices

Polynomial Design Methods and a Signal Processing Application

Polynomial Toolbox 2.5 and Systems with Parametric Uncertainties

Polynomial Toolbox and Control Education

Spectral Factorization by Means of Discrete Fourier Transform

New Algorithm for Polynomial Matrix determinant Based on FFT

Numerical and Symbolic Computation of Polynomial Matrix Determinant

Polynomial Toolbox 2.0 and Simulink

Responsible person Ing. Mgr. Radovan Suk