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doc. Ing. Zdeněk Hurák, Ph.D.

Garant programu Kybernetika a robotika - magisterský

Všechny publikace

Feedback Control in Molecular Dynamics Simulations using LAMMPS

  • DOI: 10.23919/ECC64448.2024.10591082
  • Odkaz: https://doi.org/10.23919/ECC64448.2024.10591082
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    LAMMPS, an acronym for Large-scale Atomic and Molecular Massively Parallel Simulator, is a widely used open-source tool for high-fidelity molecular dynamics (MD) simulations. In this paper, we take the initial steps towards using LAMMPS for synthesis and validation of feedback control in nanoscale manipulation. We begin by introducing the field of MD itself, discussing the specific challenges related to control synthesis, applications of nanoscale manipulation, and the intricacies of high-fidelity MD simulations. Then, we explain the main steps in modeling a molecular system in LAMMPS and provide an illustrative example. In the example, we consider a nanoscale flake of molybdenum disulfide manipulated with the tip of an atomic force microscope over an atomic surface. We designed a simple PID controller to slide the flake with the microscope tip into a desired position. To run LAMMPS simulations with closed-loop control, we utilized the official Python wrapper for LAMMPS, upon which we implemented additional functionalities. We share the code of the simulations freely with the research community through a public repository.

Tram Localization using Soft-Constrained Iterated Kalman Filter with Optimal Step Size Control

  • DOI: 10.1109/MFI62651.2024.10705771
  • Odkaz: https://doi.org/10.1109/MFI62651.2024.10705771
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper describes a way to incorporate soft constraints to iterated Kalman filter and its application to tram localization. The localization task is motivated by a suboptimal performance of a currently used hard-constrained localization solution and is then tackled by introducing a framework allowing to insert various constraints into the Kalman filter scheme. The filtering (data update) step of the iterated Kalman filter is interpreted as an instance of a non-linear least squares problem for which the step size in each iteration can be chosen in the optimal manner, improving the overall state estimate convergence. The described estimation framework is showcased on real-life data and compared against a hardconstrained Kalman filter scheme which resembles the one originally motivating the task. While the presented solution does not provide a substantial quantifiable improvement in quality of estimate in this particular case, it is much more versatile and does not require prior specific choice of tramway tracks. Finally, the introduced scheme is employed on the motivating example with a discussion of possible further enhancements.

Alternating direction method of multipliers-based distributed control for distributed manipulation by shaping physical force fields

  • DOI: 10.1177/02783649231153958
  • Odkaz: https://doi.org/10.1177/02783649231153958
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    This paper proposes an algorithm for decomposing and possibly distributing an optimization problem that naturally emerges in distributed manipulation by shaping physical force fields through actuators distributed in space (arrays of actuators). One or several manipulated objects located in this field can "feel the force" and move simultaneously and independently. The control system has to produce commands for all actuators so that desired forces are developed at several prescribed places. This can be formulated as an optimization problem that has to be solved in every sampling period. Exploiting the structure of the optimization problem is crucial for platforms with many actuators and many manipulated objects, hence the goal of decomposing the huge optimization problem into several subproblems. Furthermore, if the platform is composed of interconnected actuator modules with computational capabilities, the decomposition can give guidance for the distribution of the computation to the modules. We propose an algorithm for decomposing/distributing the optimization problem using Alternating Direction Method of Multipliers (ADMM). The proposed algorithm is shown to converge to modest accuracy for various distributed platforms in a few iterations. We demonstrate our algorithm through numerical experiments corresponding to three physical experimental platforms for distributed manipulation using electric, magnetic, and pressure fields. Furthermore, we deploy and test it on real experimental platforms for distributed manipulation using an array of solenoids and ultrasonic transducers.

Controlled synchronization of coupled pendulums by Koopman Model Predictive Control

  • DOI: 10.1016/j.conengprac.2023.105629
  • Odkaz: https://doi.org/10.1016/j.conengprac.2023.105629
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    We propose a method to solve a class of control problems arising from a system of coupled pendulums. The system considered in this work is a one-dimensional array of pendulums pivoting around a single axis with adjacent pendulums coupled through torsion springs. Only a single torque motor attached to one of the two boundary pendulums actuates the system. This setup of coupled pendulums is a mechanical realization of the Frenkel–Kontorova (FK) model – a spatially discrete version of the sine-Gordon equation describing (nonlinear) waves. The main challenges of controlling this system are high order (the number of pendulums can be high), nonlinear and oscillatory dynamics, and only one actuator. The proposed class of problems can be characterized as controlled synchronization – designing a closed-loop controller that synchronizes the motion of the pendulums. Controlled synchronization is a special case of reference tracking, where all pendulums reach a common point or a trajectory. One can formulate many practically motivated problems within this class; here, we identify three problems: a vibration control of a flexible structure, swing-up control of all pendulums in the array, and low-friction sliding of an atomic-scale structure. We show that the presented problems can be dealt with by the Koopman Model Predictive Control (KMPC). The KMPC allows for controlling nonlinear systems by combining the classical linear model predictive control (MPC) with the Koopman operator approach for nonlinear dynamical systems. The main idea of the method is to construct a linear predictor of a nonlinear system in a higher-dimensional, lifted space and use the predictor within the linear MPC. The optimization problem formulation within the KMPC can then be tailored to a specific problem in the class. Simulations and experiments on a hardware platform realizing the FK model show the effectiveness of the method.

Experimental Platform for Boundary Control of Mechanical Frenkel-Kontorova Model

  • DOI: 10.1109/CDC51059.2022.9992448
  • Odkaz: https://doi.org/10.1109/CDC51059.2022.9992448
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    In this paper, we present a laboratory mechatronic platform for experimental demonstration and verification of various dynamical and control system phenomena exhibited by the Frenkel-Kontorova (FK) model – a spatially discretized version of the sine-Gordon equation. The platform consists of an array of spring-coupled pendulums pivoting around a single axis with the first and the last pendulums controlled by motors and all pendulums’ angles measured electronically. We first introduce and describe the platform, providing details of its mechatronic design and software architecture. All the design files are freely shared with the research community under an open-source license through a public repository. The platform can be used as a testbed for various control algorithms, e.g., for distributed control or control of flexible structures. In the second part of the paper, we showcase the platform using two control problem formulations tailored to the FK model. We discuss the practical motivation for studying these problems, propose methods for solving them, and experimentally demonstrate their functionality. In particular, the first control formulation deals with non-collocated stabilization of a single pendulum through one boundary of the array in the presence of a disturbance sent from the other boundary; the second control problem consists in synchronizing pendulums’ angular speeds. Other problems can certainly be formulated, solved, and demonstrated using the proposed platform whether for research or education purposes.

Převrácená výuka a nová role učitele

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    Co je a co určitě není převrácená výuka? Jaké jsou její cíle? Pokusím se vyvrátit několik oblíbených mýtů a nabídnu vlastní učitelské zkušenosti s tímto typem výuky inženýrských předmětů na vysoké škole.

Synchronization in the Frenkel-Kontorova Model with Application to Control of Nanoscale Friction

  • DOI: 10.1016/j.ifacol.2021.10.388
  • Odkaz: https://doi.org/10.1016/j.ifacol.2021.10.388
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    This paper tailors synchronization of multi-agent systems to motion control of the Frenkel-Kontorova (FK) model, a one-dimensional chain of harmonically coupled identical particles in a spatially periodic potential field. In particular, the goal is to drive all particles in the FK model to the desired trajectory by controlling only a single—boundary—particle. The proposed solution augments harmonic coupling in the FK model with dissipative inter-particle interactions, allowing all particles in the chain to synchronize to a particular reference trajectory. The boundary control represents a special case of pinning control. Moreover, as the FK model describes the frictional dynamics of a nanosheet sliding over a surface, we use its synchronization for controlling the nanoscale sliding friction. The key idea is to introduce a sliding reference trajectory that allows particles to move near synchrony. Synchronization effectively increases the system’s stiffness, so less energy ends up dissipated through inter-particle relative motion, thus reducing the frictional force. We validate the proposed solution through numerical simulations.

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

  • DOI: 10.1016/j.ifacol.2020.12.2131
  • Odkaz: https://doi.org/10.1016/j.ifacol.2020.12.2131
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    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.

Electrorotation of Arbitrarily Shaped Micro-Objects: Modeling and Experiments

  • Autoři: Michálek, T., Bolopion, A., doc. Ing. Zdeněk Hurák, Ph.D., Gauthier, M.
  • Publikace: IEEE-ASME TRANSACTIONS ON MECHATRONICS. 2020, 25(2), 828-836. ISSN 1083-4435.
  • Rok: 2020
  • DOI: 10.1109/TMECH.2019.2959828
  • Odkaz: https://doi.org/10.1109/TMECH.2019.2959828
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    In this paper, we study the electrorotational behavior of non-spherical micro-objects. We extend a control-oriented model of general dielectrophoresis to incorporate also the hydrodynamics so that we can predict the motion of non-spherical micro-objects in fluidic environments. Such mathematical (computational) model enables model-based feedback control of a position and orientation of particles by real-time (online) computation of voltages applied to the electrodes. We use the measured data from experiments with electrorotation of an artificial micro-object having a Tetris-like shape, to evaluate the performance of the proposed model. We also demonstrate the qualitative difference in behavior from the commonly performed electrorotation of a sphere advocating the necessity for model-based control. Further analysis of the simulation results for other than the experimentally explored scenarios provides additional useful insight into the electrorotational behavior of non-spherical objects.

Onboard Model-based Prediction of Tram Braking Distance

  • Autoři: Ing. Loi Do, Herman, I., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Proceedings of the IFAC World Congress 2020. Laxenburg: IFAC, 2020. p. 15047-15052. IFAC-PapersOnLine. vol. 53. ISSN 2405-8963.
  • Rok: 2020
  • DOI: 10.1016/j.ifacol.2020.12.2006
  • Odkaz: https://doi.org/10.1016/j.ifacol.2020.12.2006
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    In this paper, we document a design of a computational method for an onboard prediction of a breaking distance for a city rail vehicle|a tram. The method is based on an onboard simulation of tram braking dynamics. Inputs to this simulation are the data from a digital map and the estimated (current) position and speed, which are, in turn, estimated by combining a mathematical model of dynamics of a tram with the measurements from a GNSS/GPS receiver, an accelerometer and the data from a digital map. Experiments with real trams verify the functionality, but reliable identification of the key physical parameters turns out critically important. The proposed method provides the core functionality for a collision avoidance system based on vehicle-to-vehicle (V2V) communication.

Queue discharge-based emergency vehicle traffic signal preemption

  • Autoři: Obrusník, V., Herman, I., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: IFAC PAPERSONLINE - 21st IFAC World Congress on Automatic Control. Amsterodam: Elsevier, 2020. p. 14997-15002. ISSN 2405-8963.
  • Rok: 2020
  • DOI: 10.1016/j.ifacol.2020.12.1998
  • Odkaz: https://doi.org/10.1016/j.ifacol.2020.12.1998
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    In this paper, we document a novel method for emergency vehicle preemption at an intersection controlled by traffic lights. The method relies on wireless vehicle-to-infrastructure (V2I) communication between the emergency vehicle and the traffic lights controller, availability of an accurate estimate of the number of vehicles in the queue, and a mathematical model of dynamics of discharging of the queue. Unlike some occasionally deployed methods that trigger the preemption the instant that the emergency vehicle appears at a prespecified distance from the intersection, the proposed method adapts the activation moment to the actual traffic conditions so that the preemption is as short as possible, thus reducing the impact on the other traffic. The method has been finetuned using numerical simulations in SUMO simulator and experimentally verified in real urban traffic. Copyright (C) 2020 The Authors.

Rijke Organ: Modeling and Control of Array of Rijke Tubes

  • DOI: 10.1016/j.ifacol.2020.12.1404
  • Odkaz: https://doi.org/10.1016/j.ifacol.2020.12.1404
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    Rijke tube is a popular physical experiment demonstrating a spontaneous generation of sound in an open vertical pipe with a heat source. This laboratory instance of thermoacoustic instability has been researched due to its significance in practical thermoacoustic systems. We revisit the experiment, focusing on the possible use of the Rijke tube as a musical instrument. The novelty presented in this paper consists in shifting the goal from sound suppression to active sound generation. This called for modifying the previously investigated methods for stabilization of thermoacoustic oscillations into their excitation and control of their amplitude. On our way towards this goal, we developed a time-domain mathematical model that considers the nonlinear and time-varying aspects of the Rijke tube. The model extends the existing modeling and analysis approaches, which are mainly based in frequency domain. We also present an extension of the basic laboratory setup in the form of an array of Rijke tubes equipped with a single speaker used to control multiple Rijke tubes with different natural frequencies simultaneously.

Control-oriented model of dielectrophoresis and electrorotation for arbitrarily shaped objects

  • DOI: 10.1103/PhysRevE.99.053307
  • Odkaz: https://doi.org/10.1103/PhysRevE.99.053307
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The most popular modeling approach for dielectrophoresis (DEP) is the effective multipole (EM) method. It approximates the polarization-induced charge distribution in an object of interest by a set of multipolar moments. The Coulombic interaction of these moments with the external polarizing electric field then gives the DEP force and torque acting on the object. The multipolar moments for objects placed in arbitrary harmonic electric fields are, however, known only for spherical objects. This shape restriction significantly limits the use of the EM method. We present an approach for online (in real time) computation of multipolar moments for objects of arbitrary shapes having even arbitrary internal composition (inhomogeneous objects, more different materials, etc.). We exploit orthonormality of spherical harmonics to extract the multipolar moments from a numerical simulation of the polarized object. This can be done in advance (offline) for a set of external electric fields forming a basis so that the superposition principle can then be used for online operation. DEP force and torque can thus be computed in fractions of a second, which is needed, for example, in model-based control applications. We validate the proposed model against reference numerical solutions obtained using Maxwell stress tensor. We also analyze the importance of the higher-order multipolar moments using a sample case of a Tetris-shaped micro-object placed inside a quadrupolar microelectrode array and exposed to electrorotation. The implementation of the model in Matlab and Comsol is offered for free download.

Optimization-based Feedback Manipulation Through an Array of Ultrasonic Transducers

  • DOI: 10.1016/j.ifacol.2019.11.722
  • Odkaz: https://doi.org/10.1016/j.ifacol.2019.11.722
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    In this paper we document a novel laboratory experimental platform for noncontact planar manipulation (positioning) of millimeter-scale objects using acoustic pressure. The manipulated objects are either floating on a water surface or rolling on a solid surface. The pressure field is shaped in real time through an 8-by-8 array (matrix) of ultrasonic transducers. The transducers are driven with square voltages whose phase-shifts are updated periodically every 20 milliseconds based on the difference between the desired and true (estimated from video) position. Numerical optimization is used within every period of a discrete-time feedback loop to determine the phase shifts for the voltages. The platform can be used as an affordable testbed for algorithms for non-contact manipulation through arrays of actuators as all the design and implementation details for the presented platform are shared with the public through a dedicated git repository. The platform can certainly be extended towards higher numbers of simultaneously yet independently manipulated objects and larger manipulation areas by expanding the transducer array.

Phase-shift feedback control for dielectrophoretic micromanipulation

  • DOI: 10.1039/c8lc00113h
  • Odkaz: https://doi.org/10.1039/c8lc00113h
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    In this paper, we present a novel approach to noncontact micromanipulation by controlled dielectrophoresis (DEP). To steer micro-objects in the desired way, the solutions reported in the literature use either DEP cages or amplitude modulation of the voltages applied to the electrodes. In contrast, we modulate the phases, that is, we control the phase shifts of the voltages applied to the electrodes, which simplifies the hardware implementation and extends the set of feasible forces. Furthermore, we introduce an innovative micro-electrode array layout, composed of four sectors with parallel (colinear) electrodes, which is capable of inducing an arbitrary movement in the manipulation area and is easy to fabricate using just an affordable one-layer technology. We then propose a closed-loop cascade control strategy based on real-time numerical optimization and deploy it to our experimental set-up. Numerical simulations and laboratory experiments demonstrate the manipulation capabilities such as positioning and steering of one or several microscopic objects (microspheres with a diameter of 50 μm) and even bringing two objects together and then separating them again. The results from simulations and experiments are compared and the positioning accuracy is evaluated in the whole manipulation area. The error in position is 8 μm in the worst case, which corresponds to 16% of the microsphere size or 0.7% of the manipulation range.

Green's function-based control-oriented modeling of electric field for dielectrophoresis

  • DOI: 10.1063/1.4997725
  • Odkaz: https://doi.org/10.1063/1.4997725
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    In this paper, we propose a novel approach to obtain a reliable and simple mathematical model of dielectrophoretic force for model-based feedback micromanipulation. Any such model is expected to sufficiently accurately relate the voltages (electric potentials) applied to the electrodes to the resulting forces exerted on microparticles at given locations in the workspace. This model also has to be computationally simple enough to be used in real time as required by model-based feedback control. Most existing models involve solving two- or three-dimensional mixed boundary value problems. As such, they are usually analytically intractable and have to be solved numerically instead. A numerical solution is, however, infeasible in real time, hence such models are not suitable for feedback control. We present a novel approximation of the boundary value data for which a closed-form analytical solution is feasible; we solve a mixed boundary value problem numerically off-line only once, and based on this solution, we approximate the mixed boundary conditions by Dirichlet boundary conditions. This way, we get an approximated boundary value problem allowing the application of the analytical framework of Green's functions. The thus obtained closed-form analytical solution is amenable to real-time use and closely matches the numerical solution of the original exact problem.

Scaling in bidirectional platoons with dynamic controllers and proportional asymmetry

  • DOI: 10.1109/TAC.2016.2594169
  • Odkaz: https://doi.org/10.1109/TAC.2016.2594169
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    We consider platoons composed of identical vehicles with an asymmetric nearest-neighbor interaction. We restrict ourselves to intervehicular coupling realized with dynamic arbitrary-order onboard controllers such that the coupling to the immediately preceding vehicle is proportional to the coupling to the immediately following vehicle. Each vehicle is modeled using a transfer function and we impose no restriction on the order of the vehicle. The only requirement on the controller and vehicle model is that the platoon is stable for any number of vehicles. The platoon is described by a transfer function in a convenient product form. We investigate how the H-infinity norm and the steady-state gain of the platoon scale with the number of vehicles. We conclude that if the open-loop transfer function of the vehicle contains two or more integrators and the second smallest eigenvalue of the graph Laplacian is uniformly bounded from below, the norm scales exponentially with the growing distance in the graph. If there is just one integrator in the open loop, we give a condition under which the norm of the transfer function is bounded by its steady-state gain-the platoon is string-stable. Moreover, we argue that in this case it is always possible to design a controller for the extreme asymmetry-the predecessor following strategy.

Time-Optimal Control for Bilinear Nonnegative-In-Control Systems: Application to Magnetic Manipulation

  • DOI: 10.1016/j.ifacol.2017.08.1916
  • Odkaz: https://doi.org/10.1016/j.ifacol.2017.08.1916
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper describes a simple time-optimal control strategy for a class of second-order bilinear systems with nonnegative inputs. The structure of the model is motivated by the task of noncontact manipulation of an object in a planar force field generated by a single source; such setup constitutes a basic building block for a planar manipulation by an array of force field sources. The nonnegative-in-control property means that an object (particle) placed freely in the field can only feel an attractive force towards the source. In this paper we further restrict the control inputs to a binary signal---the field can be switched on and off. The control objective is to bring the object to the origin (where the source of the force field is located) as fast as possible. The optimal switching strategy is proposed using geometric arguments and verified using numerical simulations and experiments with a laboratory platform for noncontact magnetic manipulation.

Vehicular platooning experiments using autonomous slot cars

  • Autoři: Lád, M., Herman, I., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Proceedings of the IFAC 2017 World Congress. Kidlington Oxford OX GB: Elsevier, 2017. p. 12596-12603. ISSN 2405-8963.
  • Rok: 2017
  • DOI: 10.1016/j.ifacol.2017.08.2201
  • Odkaz: https://doi.org/10.1016/j.ifacol.2017.08.2201
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper reports on an affordable experimental platform for vehicular platooning. The experimental platoon consists of several autonomous slot cars (typical experiments take 5 to 20 slot cars), hence it fits into an indoor laboratory. Each car is equipped with an onboard controller and it can measure its own velocity, acceleration, and distances to its nearest neighbors. Furthermore, each car can communicate with other vehicles including the leader of the platoon. A convenient user interface allows to store, analyze and visualize the experimental data in Matlab. The platform can be used for demonstrating various decentralized and distributed control strategies for vehicular platoons, such as predecessor following, (a)symmetric bidirectional control or cooperative adaptive cruise control. Moreover, the phenomenon of string instability can be observed in experiments due to the fast dynamics of slot cars. The technical design details including the source codes and electronic schematics are shared with the public.

Feedback control for noise-aided parallel micromanipulation of several particles using dielectrophoresis

  • DOI: 10.1002/elps.201400521
  • Odkaz: https://doi.org/10.1002/elps.201400521
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper describes a novel control strategy for simultaneous manipulation of several microscale particles over a planar microelectrode array using dielectrophoresis. The approach is based on a combination of numerical nonlinear optimization, which gives a systematic computational procedure for finding the voltages applied to the individual electrodes, and exploitation of the intrinsic noise, which compensates for the loss of controllability when two identical particles are exposed to identical forces. Although interesting on its own, the proposed functionality can also be seen as a preliminary achievement in a quest for a technique for separation of two particles. The approach is tested experimentally with polystyrene beads (50 microns in diameter) immersed in deionized water on a flat microelectrode array with parallel electrodes. A digital camera and computer vision algorithm are used to measure the positions. Two distinguishing features of the proposed control strategy are that the range of motion is not limited to interelectrode gaps and that independent manipulation of several particles simultaneously is feasible even on a simple microelectrode array.

Nonzero Bound on Fiedler Eigenvalue Causes Exponential Growth of H-Infinity Norm of Vehicular Platoon

  • DOI: 10.1109/TAC.2014.2366980
  • Odkaz: https://doi.org/10.1109/TAC.2014.2366980
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    We consider platoons composed of identical vehicles and controlled in a distributed way, that is, each vehicle has its own onboard controller. The regulation errors in spacing to the immediately preceeding and following vehicles are weighted differently by the onboard controller, which thus implements an asymmetric bidirectional control scheme. The weights can vary along the platoon. We prove that such platoons have a nonzero uniform bound on the second smallest eigenvalue of the graph Laplacian matrix— the Fiedler eigenvalue. Furthermore, it is shown that existence of this bound always signals undesirable scaling properties of the platoon. Namely, the H-infinity norm of the transfer function of the platoon grows exponentially with the number of vehicles regardless of the controllers used. Hence the benefits of a uniform gap in the spectrum of a Laplacian with an asymetric distributed controller are paid for by poor scaling as the number of vehicles grows.

On benchmark problems, challenges, and competitions in electrokinetics - A review

  • DOI: 10.1002/elps.201400520
  • Odkaz: https://doi.org/10.1002/elps.201400520
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    In this critical review, we comment on the absence of widely shared benchmark problems and relevant challenges or even attractive competitions in the field of electrokinetics. We argue that in some other scientific domains that are, similarly as electrokinetics, strongly multidisciplinary, the existence of these tools is very beneficial because it stimulates the discussion about what constitutes the bottleneck of further progress, allows easier exploitation of results provided by other scientific and engineering disciplines, and, last but not least, makes the research domain attractive and visible to a broader public, including students. The goal of this review is to provoke some discussion that might perhaps lead to compensating for these shortcomings.

Dielectrophoretic actuation strategy for micromanipulation along complex trajectories

  • DOI: 10.1109/AIM.2014.6878040
  • Odkaz: https://doi.org/10.1109/AIM.2014.6878040
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper presents application of dielectrophoresis for manipulation of a microparticle in a liquid medium above a planar surface. The force on the microparticle is exerted by a non-uniform AC electric field. The field is generated by a set of micro-electrodes patterned on the planar surface and connected to a multi-channel voltage waveform generator. An novel yet simple control approach based on changing the phase delays among voltages on the electrodes is introduced together with a description of an efficient hardware implementation. Laboratory experiments with a 250-micron polystyrene bead are documented. This work was partly motivated by the series of international competitions called Mobile Microrobotics Challenge and organized by NIST and taken over by IEEE RAS recently.

Harmonic instability of asymmetric bidirectional control of a vehicular platoon

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    This paper deals with harmonic instability of asymmetric control of vehicular platoons. The considered platoons are composed of identical linear models of arbitrary order but there must be at least two integrators in the open loop. Each vehicle only responds to the movement of its immediate neighbors—the predecessor and the follower—and these two couplings are nonidentical. We show that for arbitrary asymmetry of intervehicular coupling, there is an exponential growth of the peak in the platoon’s magnitude frequency responses as the number of vehicles grows—a phenomenon called harmonic instability in the literature. Whereas it has been already shown for some particular cases that the beneficial effects of having the Laplacian eigenvalues lower-bounded by a nonzero constant come at the cost of harmonic instability, here we generalize this result to any linear controllers.

Refinement of a bidirectional platooning controller by wave absorption at the leader

  • DOI: 10.1109/ECC.2014.6862263
  • Odkaz: https://doi.org/10.1109/ECC.2014.6862263
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper tailors the so-called wave-based control known in the field of flexible mechanical structures to the problem of distributed control of vehicular platoons. The proposed solution is based on refinement of the popular symmetric bidirectional distributed controller which enables the platoon leader to actively absorb any incoming (backwards running) wave of positional changes in the platoon. In order to accomplish this, the platoon leader only needs to measure the distance to its immediate follower. This minor augmentation results in significant attenuation of undesirable long transients during the platoon manoeuvres like acceleration/deceleration or during the commanded change of the inter-vehicle distances. Numerical simulations show that the wave-absorbing controller works efficiently even for platoons with a very large number of vehicles and outperforms the known platoon control schemes such as predecessor following or bidirectional control algorithm.

Wave-absorbing vehicular platoon controller

  • DOI: 10.1016/j.ejcon.2014.06.001
  • Odkaz: https://doi.org/10.1016/j.ejcon.2014.06.001
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper tailors the so-called wave-based control, popular in the field of flexible mechanical structures, to the field of distributed control of vehicular platoons. The proposed solution augments the symmetric bidirectional control algorithm with a wave-absorbing controller implemented on the leader, and/or on the rear-end vehicle. The wave-absorbing controller actively absorbs an incoming wave of positional changes in the platoon and thus prevents oscillations of inter-vehicle distances. The proposed controller significantly improves the performance of platoon manoeuvrers such as acceleration/deceleration or changing the distances between vehicles without making the platoon string unstable. Numerical simulations show that the wave-absorbing controller performs efficiently even for platoons with a large number of vehicles, for which other platooning algorithms are inefficient or require wireless communication between vehicles.

Distributed stabilisation of spatially invariant systems: positive polynomial approach

  • Autoři: Augusta, P., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Multidimensional Systems and Signal Processing. 2013, 24(1), 3-21. ISSN 0923-6082.
  • Rok: 2013
  • DOI: 10.1007/s11045-011-0152-5
  • Odkaz: https://doi.org/10.1007/s11045-011-0152-5
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper gives a computationally feasible characterisation of spatially distributed controllers stabilising a linear spatially invariant system, that is, a system described by linear partial differential equations with coefficients independent on time and location. With one spatial and one temporal variable such a system can be modelled by a 2-D transfer function. Stabilising distributed feedback controllers are then parametrised as a solution to the Diophantine equation ax + by = c for a given stable bi-variate polynomial c. The paper is built on the relationship between stability of a 2-D polynomial and positiveness of a related polynomial matrix on the unit circle. Such matrices are usually bilinear in the coefficients of the original polynomials. For low-order discrete-time systems it is shown that a linearising factorisation of the polynomial Schur-Cohn matrix exists. For higher order plants and/or controllers such factorisation is not possible as the solution set is non-convex and one has to resort to some relaxation. For continuous-time systems, an analogue factorisation of the polynomial Hermite-Fujiwara matrix is not known. However, for low-order systems and/or controller, positivity conditions on the closed-loop polynomial coefficients can be invoked. Then the computational framework of linear matrix inequalities can be used to describe the stability regions in the parameter space using a convex constraint.

Equalization of intervehicular distances in platoons on a circular track

  • DOI: 10.1109/PC.2013.6581381
  • Odkaz: https://doi.org/10.1109/PC.2013.6581381
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    We consider a circular track and a platoon of vehicles driving on it. Our goal is to design a distributed (onboard) control system that will keep uniform spacing between any car and its predecessor without knowing the length of the track. Quite naturally the distributed control problem is posed as a double consensus task, wherein individual cars have to agree on the cruising velocity and the gaps between two consecutive cars. We study the feasibility of the consensus and its convergence properties. We prove that the cars will converge to equal distances and the resulting velocity will be the average of the velocity references of individual cars. We also consider the stability of this circularly connected system.

Magnetic manipulator (MagMan): Design and Implementation in Matlab

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The prototype of a novel experimental platform for education and research on distributed manipulation by shaping physical force fields through arrays of sources will be presented. Description of both the hardware realization and (an example of) the control system implementation in Matlab/Simulink will be given. Some experimental results will be shown. The platform uses an array of coils to create and shape the magnetic field. One or several iron balls are placed into the field on a flat horizontal surface and they roll in response to the field. Positions of the balls are sensed in real time and these measurements can be used for closing the feedback loop commanding the current flowing through the coils. The controller can bring the objects to desired locations as well as steer them along predefined trajectories. Design of the platform is modular and allows for simple reconfiguring and expanding. Each module consists of four coils, driving and measuring electronics, a processor and connectors. Modules are interconnected by an RS-485 bus and commanded from PC. It is possible to control both the polarity and the magnitude of the current flowing though each coil. Position of the ball is measured using a resistive touch foil. Alternatively/additionally it can be obtained using image processing, which is a bit slower but allows for tracking of several balls. The mathematical model of the platform was built by experimental system identification while Matlab was used to gather the measured data and find the parameters of model that fit the measurements. Based on the model, a controller was designed. The controller keeps the popular cascade structure with the innermost loop responsible for achieving the forces requested by the higher-level control loops. Numerical optimization problem had to be solved in real time to find suitable setting of currents. Finally, a convenience of the use of iPad as a graphical user interface was demonstrated.

PDdE-based analysis of vehicular platoons with spatio-temporal decoupling

  • Autoři: Herman, I., Martinec, D., doc. Ing. Zdeněk Hurák, Ph.D., prof. Ing. Michael Šebek, DrSc.,
  • Publikace: Preprints of the 4th IFAC Workshop on Distributed Estimation and Control in Networked Systems :Estimation and Control of Networked Systems. Laxenburg: IFAC, 2013, pp. 144-151. ISSN 1474-6670. ISBN 978-3-902823-55-7.
  • Rok: 2013
  • DOI: 10.3182/20130925-2-DE-4044.00019
  • Odkaz: https://doi.org/10.3182/20130925-2-DE-4044.00019
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper provides exact analytical solutions of wave-like PDdE-based (partial differential-difference equation) models of several popular vehicular platooning problems with bidirectional distributed control. Efficient evaluation of eigenvalues, eigenfunctions and wave velocities is proposed for a finite vehicular platoon without an approximation by a continuum model. Thanks to the decoupling of spatial and temporal dynamics, closed-loop stability can be analyzed by looking at a characteristic polynomial using a root-locus-like graphical technique. Although the paper only contains discussions for static state feedback controllers (using measurements of inter-vehicular distances and relative velocities), extensiona to higherorder (dynamic) controllers is straighforward and will be included in the extended version of the paper.

Structured MIMO H-infinity design for dual-stage inertial stabilization: Case study for HIFOO and Hinfstruct solvers

  • DOI: 10.1016/j.mechatronics.2013.08.003
  • Odkaz: https://doi.org/10.1016/j.mechatronics.2013.08.003
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper reports on application of two available numerical solvers for structured and fixed-order controller design to a realistic laboratory MIMO electromechanical system. Namely, an experimental platform consisting of two coaxial motorized gimbals that stabilize an angular motion of an optical payload around a single axis is considered. Inertial angular rate of the payload is measured using a MEMS gyro and the mechanically constrained misalignment between the two gimbals is measured with an incremental encoder. This represents a simplified testbed for the more practically useful multi-axis line-of-sight inertial stabilization systems. The paper defends the choice of the control system structure and argues that the recent Matlab-based computational MIMO control design procedures which are capable of enforcing some structural constraints upon the controller transfer function matrix HIFOO and Hinfstruct constitute efficient and practical design tools. They only lose little in the optimality of the full unrestricted MIMO controllers computed by standard H-infinity optimization, and yet they produce controllers which are easy to implement and fine-tune within a standard motion control infrastructure based on PID feedback and feedforward terms. Numerical simulations and laboratory experiments were used to validate the findings.

Vehicular Platoons: Survey of Control Algorithms and Experiments

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper surveys various spatial strategies for control of vehicular platoons in future automated highway systems. The strategies are described in space /time domain as well as by local and global transfer functions. Their efficiency, applicability as well as other properties are discussed theoretically. They are also verified on a nice simple based on commercially available racing slot cars equipped with an on-board microcontroller-based control system with additional components such as an infrared range sensor and a wireless communication module.

Constant Time Headway Control Policy in Leader Following Vehicular Platoons: 2-D Polynomial Approach

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    Constant time headway policy is considered for control of vehicular platoons in future automated highway systems. 2-D polynomial approach is applied, hence dynamics is described using a fraction of two bivariate polynomials. In contrast to some previous works, the platoon here assumes a leader and an infinite number of followers. The usual bilateral z-transform used for doubly infinite vehicular strings is replaced here by a special unilateral z-transform. This naturally brings the boundary conditions into consideration through which the leader vehicle comes into the scene.

Experimentally Verified Iterative Learning Control based on Repetitive Process Stability Theory

  • Autoři: Dabkowski, P., Galkowski, K., Rogers, E., Cai, Z., Freeman, Ch., Lewin, P., doc. Ing. Zdeněk Hurák, Ph.D., Kummert, A.
  • Publikace: 2012 American Control Conference (ACC 2012). Piscataway: IEEE, 2012, pp. 604-609. ISSN 0743-1619. ISBN 978-1-4577-1096-4.
  • Rok: 2012
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    This paper gives new results on the design and experimental evaluation of an Iterative Learning Control (ILC) law in a repetitive process setting. The experimental results given are from a gantry robot facility that has been extensively used in the benchmarking of linear model based ILC designs. An example is also given to demonstrate that this new design offers much superior performance in comparison to some previous designs based on the Roesser model for 2D linear systems.

Feedback linearization approach to distributed feedback manipulation

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    This report formulates the problem of a distributed planar manipulation realized by shaping a spatially continuous force field. It also suggests a control strategy based on feedback linearization. Force fields derived from potential fields are considered. The potentials are "shaped" by a set of spatially discrete "actuators" such as electrodes in the case of dielectrophoresis, electromagnets in the case of planar magnetic manipulators, or linear piezoelectric actuators in the case of deformable flat surfaces. The actuators form arrays. Distinguished feature of such force fields is that the contribution from an individual actuator usually affects the situation in the neighboring zones too, but usually not in too remote zones. As an idealization, the spatial domain is considered unbounded, which enables examination of asymptotic behavior of the manipulation scheme.

Image-Based Pointing and Tracking for Inertially Stabilized Airborne Camera Platform

  • Autoři: doc. Ing. Zdeněk Hurák, Ph.D., Řezáč, M.
  • Publikace: IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY. 2012, 20(5), 1146-1159. ISSN 1063-6536.
  • Rok: 2012
  • DOI: 10.1109/TCST.2011.2164541
  • Odkaz: https://doi.org/10.1109/TCST.2011.2164541
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    This paper describes a novel image-based pointing-tracking feedback control scheme for an inertially stabilized double-gimbal airborne camera platform combined with a computer vision system. The key idea is to enhance the intuitive decoupled controller structure with measurements of the camera inertial angular rate around its optical axis. The resulting controller can also compensate for the apparent translation between the camera and the observed object, but then the velocity of this mutual translation must be measured or estimated. Even though the proposed controller is more robust against longer sampling periods of the computer-vision system then the decoupled controller, a sketch of a simple compensation of this delay is also given. Numerical simulations are accompanied by laboratory experiments with a real benchmark system.

Vehicular platooning experiments with racing slot cars

  • DOI: 10.1109/CCA.2012.6402709
  • Odkaz: https://doi.org/10.1109/CCA.2012.6402709
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper reports on an affordable platform for indoor experimental verification of algorithms for distributed control of platoons of vehicles. The platform is based on commercially available racing slot cars (by Carrera) equipped with an on-board 32-bit microcontroller-based control system. The assembled PCB board was provided by Freescale Semiconductor, Rožnov pod Radhošťem, Czech Republic, within their Freescale Race Challenge 2012 competition of individual autonomous slot cars organized for student teams in Czech and Slovak republics. The documentation is freely available online. Some extra components such as an infrared range sensor and a wireless communication module have been added to the original system. The capabilities and potentials of the proposed platform are demonstrated on platooning experiments using two of the most popular platoon control schemes: predecessor following and leader following. Some technical parameters of the platform as well as design experience are shared in the report. It is hoped to encourage other teams to build a similar setup and possibly expose their new distributed control algorithms to an experimental competition.

2-D polynomial approach to control of leader following vehicular platoons

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    This paper formulates the problems of stabilization and asymptotic following in infinite platoons of vehicles within the 2-D polynomial framework, that is, the dynamics of the problem are described using a fraction of two bivariate polynomials. In contrast to some previous works, the platoon here assumes a leader (and an infinite number of followers), therefore the often used bilateral z-transform should not be used here since it assumes a doubly infinite vehicular strings. The unilateral z-transform seems better suited. However, it brings about the need to take the boundary conditions into consideration; among other, the leader vehicle comes into the scene. The necessary formalism is introduced in the paper and used to provide elegant alternative proofs of some well-known facts about the platooning problem.

Advanced Control of a Quadrotor Using Eigenaxis Rotation

  • Autoři: Dvořák, J., De Lellis, M., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: IEEE Multi-Conference on Systems and Control. Piscataway, NJ: IEEE, 2011. p. 153-158. ISSN 1085-1992. ISBN 978-1-4577-1061-2.
  • Rok: 2011
  • DOI: 10.1109/CCA.2011.6044355
  • Odkaz: https://doi.org/10.1109/CCA.2011.6044355
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    This paper describes a novel strategy for reorientation of an indoor micro quadrotor consisting in combination of an LQ-optimal state-feedback and an eigenaxis rotation. The proposed control scheme is capable of performing large scale maneuvers with no path constraints or singularities while achieving short settling times and high energy efficiency. A suitable interface to the translation controller is introduced.

Hybrid charge control for stick-slip piezoelectric actuators

  • DOI: 10.1016/j.mechatronics.2010.09.002
  • Odkaz: https://doi.org/10.1016/j.mechatronics.2010.09.002
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The article describes an analog electronic circuit for driving stick-slip piezoelectric linear actuators. The task for the amplifier is to provide a high-voltage asymmetric sawtooth-like signal and feed it into a capacitive load. Generation of excessive heat must be avoided while maximizing the slew rate. In order to guarantee a steady translation, the hysteretic behaviour of the piezoelectric material must be compensated. Combination of a charge control scheme with switching is proposed as an efficient solution. Laboratory experiments confirm the superiority of this tailored solution over other existing techniques based on versatile linear voltage amplifiers.

New Mathematical Tools for Analysis and Control of Platoons of Cars in Future Automated Highway Systems

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    This paper introduces new mathematical tools for stabilization and asymptotic following in infinite platoons of vehicles in future automated highway systems. The platoon description, behavior analysis and control is approached in 2-D polynomial framework, that is, the dynamics of the problem are described using a fraction of two bivariate polynomials. In contrast to some previous works, the platoon here assumes a leader (and an infinite number of followers), therefore the often used bilateral z -transform should not be used here since it was developed for doubly infinite vehicular strings. The unilateral z -transform seems better suited. However, it brings about the need to take the boundary conditions into consideration; among other, the leader vehicle comes into the scene. The necessary formalism is introduced in the paper and used to provide elegant alternative proofs of some well-known facts about the platooning problem.

Structured MIMO H-Infinity Design for Dual-Stage Inertial Stabilization: Case Study for HIFOO

  • Autoři: Řezáč, M., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Proceedings of the 18th IFAC World Congress, 2011. Bologna: IFAC, 2011, pp. 7456-7461. ISBN 978-3-902661-93-7. Available from: http://www.ifac-papersonline.net/Detailed/49933.html
  • Rok: 2011
  • DOI: 10.3182/20110828-6-IT-1002.02242
  • Odkaz: https://doi.org/10.3182/20110828-6-IT-1002.02242
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper reports on a control design for an experimental platform that contains two aligned motorized gimbals stabilizing an optical payload around a single axis using measurements from an inertial angular rate sensor (MEMS gyro). Such a laboratory system represents a simplified testbed for the more practically useful line-of-sight stabilization. The paper defends the choice of the control configuration and argues that when using MIMO design procedures, enforcing some structure upon the transfer function matrix makes the controller implementation and fine-tuning easier. Such structural constraints were taken into consideration in the computational Hinf design by using the publicly available HIFOO solver based on algorithms for non-convex and non-smooth optimization. Results are contrasted with the controllers designed with classical methods and full MIMO Hinf optimization.

Tremor analysis by decomposition of acceleration into gravity and inertial acceleration using inertial measurement unit

  • Autoři: Šprdlík, O., doc. Ing. Zdeněk Hurák, Ph.D., Hoskovcová, M., Ulmanová, O., Růžička, E.
  • Publikace: Biomedical Signal Processing and Control. 2011, 6(3), 269-279. ISSN 1746-8094.
  • Rok: 2011
  • DOI: 10.1016/j.bspc.2010.09.004
  • Odkaz: https://doi.org/10.1016/j.bspc.2010.09.004
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    Decomposition of acceleration was investigated as an alternative to direct spectral analysis of measured acceleration or angular velocity for tremor quantification. An orientation estimation algorithm was devised to decompose the measured acceleration into the gravitational artifact and the inertial acceleration caused by sensor movement in an inertial frame. Resulting signals were used to assess tremor amplitude and frequency by spectral peak detection. The algorithm was tested on experimental data from a clinical study including patients with essential tremor. The testing comprised of the classification of measurements to come from a patient or a healthy control and of the regression of the visual assessment of tremor amplitude. Small improvements in performance measures were achieved. The regression accuracy was comparable to the accuracy in other works. The influence of sensor calibration and connections of results to an analytic approach were analyzed briefly.

Vehicular Platooning Experiments with LEGO MINDSTORMS NXT

  • Autoři: Martinec, D., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: IEEE Multi-Conference on Systems and Control. Piscataway, NJ: IEEE, 2011. pp. 927-932. ISSN 1085-1992. ISBN 978-1-4577-1061-2.
  • Rok: 2011
  • DOI: 10.1109/CCA.2011.6044393
  • Odkaz: https://doi.org/10.1109/CCA.2011.6044393
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper reports on experimenting with a popular introductory robotics toolkit LEGO MINDSTORMS NXT that was aimed at demonstrating a few algorithms for distributed control of a long platoon of autonomous vehicles. The configuration used in this report measures the distance to the vehicle ahead and the velocity of the vehicle itself. The acquired technical experience with this platform is shared in the report, including recommendation towards improvements.

Vibration rejection for inertially stabilized double gimbal platform using acceleration feedforward

  • Autoři: Řezáč, M., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: IEEE Multi-Conference on Systems and Control. Piscataway, NJ: IEEE, 2011. p. 363-368. ISSN 1085-1992. ISBN 978-1-4577-1061-2.
  • Rok: 2011
  • DOI: 10.1109/CCA.2011.6044442
  • Odkaz: https://doi.org/10.1109/CCA.2011.6044442
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper documents a computational design and an experimental verification of a vibration rejection scheme for an inertially stabilized platform mounted on a mobile base. The mechanical configuration of the platform is that of a standard double gimbal, which realizes a mass stabilization of the line of sight of an optoelectronic payload such as a camera an/or laser ranger finder. Nonideal static balancing of the payload gives rise to projection of the carrier vibrations onto a disturbing torque acting on the payload around the joint axes. This disturbance can be left for the existing inertial angular rate feedback to attenuate but a better solution can be devised. The cause of this disturbing torque - the linear acceleration of the carrier - can be measured, filtered and fed forward to the two direct drive motors. Experiments prove that significant vibration rejection is achieved with this feedforward compensation scheme.

2D polynomial approach to stability of platoons of vehicles

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    This paper formulates the problems of stability testing and stabilization of an infinite platoon of vehicles within the 2D polynomial framework, that is, the dynamics of the problem is described using a fraction of two bivariate polynomials. Recent computational tools for testing positivity of polynomial matrices are suggested for stability testing and stabilization.

Control design for image tracking with an inertially stabilized airborne camera platform

  • Autoři: doc. Ing. Zdeněk Hurák, Ph.D., Řezáč, M.
  • Publikace: Automatic Target Recognition XX; Acquisition, Tracking, Pointing, and Laser Systems Technologies XXIV; and Optical Pattern Recognition XXI,. Bellingham (stát Washington): SPIE, 2010. p. 76961H. ISSN 0277-786X. ISBN 978-0-8194-8160-3.
  • Rok: 2010
  • DOI: 10.1117/12.849902
  • Odkaz: https://doi.org/10.1117/12.849902
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper reports on a few control engineering issues related to design and implementation of an image-based pointing and tracking system for an inertially stabilized airborne camera platform. A medium-sized platform has been developed within a joint project coordinated by Czech Air Force Research Institute. The resulting experimental platform is based on a common double gimbal configuration with two direct drive motors and MEMS gyros. Automatic vision-based tracking system is built on top of the inertial stabilization. Choice of a suitable control configuration is discussed first, because the decoupled structure for the inner inertial rate controllers does not extend easily to the outer imagebased tracking loop. It appears that the pointing and tracking controller can benefit much from availability of measurements of an inertial rate of the camera around its optical axis. The proposed pointing and tracking controller relies on feedback linearization well known in visual servoing.

Delay compensation in a dual-rate cascade visual servomechanism

  • Autoři: doc. Ing. Zdeněk Hurák, Ph.D., Řezáč, M.
  • Publikace: Proceedings of the 49th IEEE Conference on Decision and Control. Madison: Omnipress, 2010. ISSN 0191-2216. ISBN 978-1-4244-7744-9.
  • Rok: 2010
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper presents a simple technique for a compensation of a one-sampling-period delay in the outer (position) loop in a cascade visual servomechanism with the inner feedback loop taking care of a velocity. The result presented in the paper is mainly relevant for visual servoing applications, since the velocity sensors such as tachometers or gyros usually achieve much higher sampling rate compared to computer vision systems playing the role of position sensors. The technique is based on the concept of a modified Smith compensator wherein the undelayed output of a mathematical model is replaced by a measured value of a signal from the inner loop. Casting this intuitive solution as a special instance of a theoretical methodology not only gives an insight but also suggests a generalization based on a multirate estimation theory, which might offer yet some more improvement.

Distributed stabilization of spatially invariant systems: positive polynomial approach

  • Autoři: Augusta, P., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Proceedings of the 19th International Symposium on Mathematical Theory of Networks and Systems - MTNS 2010. Budapest: MTA SZTAKI - Hungarian Academy of Sciences, 2010, pp. 773-779. ISBN 978-963-311-370-7.
  • Rok: 2010
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper gives a computationally feasible characterisation of spatially distributed discrete-time controllers stabilising a spatially invariant system. This gives a building block for convex optimisation based control design for these systems. Mathematically, such systems are described by partial differential equations with coefficients independent on time and location. In this paper, a situation with one spatial and one temporal variable is considered. Models of such systems can take a form of a 2-D transfer function. Stabilising distributed feedback controllers are then parametrised as a solution to the Diophantine equation ax + by = c for a given stable bivariate polynomial c. This paper brings a computational characterisation of all such stable 2-D polynomials exploiting the relationship between a stability of a 2-D polynomial and positiveness of a related polynomial matrix on the unit circle. Such matrices are usually bilinear in the coefficients of the original polynomials.

Hybrid Charge Control for Grounded Stick-Slip Piezoelectric Actuators

  • Autoři: Špiller, M., doc. Ing. Zdeněk Hurák, Ph.D., Honců, J.
  • Publikace: Proceedings of the 12th International Conference on New Actuators. Bremen: WFB Wirtschaftsförderung Bremen GmbH, Division Messe Bremen, 2010, pp. 963-966. ISBN 978-3-933339-12-6. Available from: http://www.actuator.de
  • Rok: 2010
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The article describes an analog electronic circuit for driving grounded stick-slip piezoelectric actuators. The task for the amplifier is to produce a high-voltage asymmetric sawtooth-like signal and feed it into a rather capacitive piezo leg. Generation of excessive heat must be avoided while maximizing the slew rate, which is necessary to minimize backlash. Hysteretic behaviour of the piezoelectric material must also be compensated in order to guarantee a smooth linear motion. Combination of a charge control scheme with switching is proposed as an efficient solution. A modification to the conventional charge control scheme had to be made, though. Having the load (piezo) grounded enables driving several channels from a single device, which is needed, for example, when controlling x-y actuator stages but requires use of a differential amplifier in the loop. Laboratory experiments with piezoelectric stick-slip microactuators confirm superiority over existing and known techniques.

Inerciálně stabilizovaná kamerová základna pro bezpilotní letoun s automatickým sledováním pozemních cílů

  • Pracoviště: Katedra kybernetiky, Katedra řídicí techniky
  • Anotace:
    Článek představuje vývojový projekt inerciálně a a obrazově stabilizované kamerové základny, který je právě řešen týmem na ČVUT ve spolupráci s Vojenským technickým ústavem letectva a PVO a pražskou firmou ESSA. Konkrétní údaje uvedené v článku se týkají již ukončené fáze projektu, ve které byl vyvinut první funkční vzor založený na použití dvou direct drive motorů a MEMS gyroskopů. V současné době probíhá vývoj druhé vylepšené verze, která využívá dvoustupňovou stabilizaci optické osy a vyhýbá se použití atraktivní avšak drahé technologie direct drive motorů.

Low-cost inertial estimation unit based on extended Kalman filtering

  • Autoři: Řezáč, M., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Automatic Target Recognition XX; Acquisition, Tracking, Pointing, and Laser Systems Technologies XXIV; and Optical Pattern Recognition XXI,. Bellingham (stát Washington): SPIE, 2010, pp. 76961F. ISSN 0277-786X. ISBN 978-0-8194-8160-3. Available from: http://spiedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PSISDG00769600000176961F000001&idtype=cvips&gifs=yes&ref=no
  • Rok: 2010
  • DOI: 10.1117/12.850030
  • Odkaz: https://doi.org/10.1117/12.850030
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper describes some design and implementation aspects of a low-cost inertial estimation unit based on comercially available inertial sensors (3-axis rate gyro combined in a single package with a 3-axis accelerometer and a 3-axis magnetometer). The data measured by the three sensors are fused using the Extended Kalman filtering paradigm. No model of the dynamics of the carrier (aircraft, mobile robot) is relied upon, the only modeled dynamics is that of sensors, such as the bias and noise. The choice of extended Kalman filtering methodology was dictated by strong requirements on computational simplicity. Some experience with implementation of the proposed scheme on a digital hardware (ARM7 based microcontroller) is shared in the paper. Finally, functionality of the presented device is demonstrated in experiments. Besides simple indoor tests, fly experiments were conducted using a small UAV helicopter.

Robust control of distributed parameter mechanical systems using a multidimensional systems approach

  • Autoři: Cichy, B., Augusta, P., Rogers, E., Galkowski, K., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Bulletin of the Polish Academy of Sciences - Technical Sciences. 2010, 58(1), 67-75. ISSN 0239-7528.
  • Rok: 2010
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The unique characteristic of a repetitive processes is a series of sweeps, termed passes, through a set of dynamics defined over a finite duration. On each pass an output, termed the pass profile is produced which acts as on forcing function, and hence contributes to, the dynamics of the next pass profile. This leads to the possibility that the output, i.e. the sequence of pass profiles, will contain oscillations that increase in amplitude in the pass-to-pass direction. Such behavior cannot be controlled by application of standard linear systems control laws and instead they must be treated as two-dimensional (2D) systems where information propagation in two independent directions, termed passto- pass and along the pass respectively, is the defining feature. Physical examples of such processes include long-wall coal cutting and metal rolling.

Towards planar micromanipulators based on dielectric elastomers in thickness mode

  • Autoři: Řezáč, M., doc. Ing. Zdeněk Hurák, Ph.D., Bellouard, Y.
  • Publikace: Proceedings of the 12th International Conference on New Actuators. Bremen: WFB Wirtschaftsförderung Bremen GmbH, Division Messe Bremen, 2010, pp. 901-904. ISBN 978-3-933339-12-6.
  • Rok: 2010
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper describes the authors' initial steps in the domain of advanced micromanipulators based on dielectric elastomers. Namely, local deformation of a thin (~10um) elastomer film as a result of Maxwell pressure on the surface is analyzed. The ultimate goal of this initiating research is to develop a deformable surface that could be used for planar manipulation with flat objects. Induced surface travelling wave, for instance, could be used to achieve simple transportation of samples in the style of common linear ultrasonic motors. The early achievements presented in this paper include trivial yet tedious fabrication procedures of a PDMS film sandwiched between two sputtered gold electrodes, and some laboratory experiments. Deformation observed with an optical microscope partially agrees with the computational model developed in a FEM modeler/solver. The deviations from the model are discussed.

An often missed detail: Formula relating peek sensitivity with gain margin less than one

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    An inequality relating gain margin with sensitivity peek value is presented in numberous basic control textbooks. In fact, this inequality fails to hold as soon as the open-loop Nyquist plot crosses the negative real axis on the left of the critical point. This opposite case is usually ignored by the textbook authors. A simple alternative inequality is derived in the paper to cover the not so popular opposite case. This fills a small gap one often encounters in basic control courses.

Combined line-of-sight inertial stabilization and visual tracking: application to an airborne camera platform

  • Autoři: doc. Ing. Zdeněk Hurák, Ph.D., Řezáč, M.
  • Publikace: Proceedings of the 48th IEEE Conference on Decision and Control. Piscataway, NJ: IEEE, 2009. p. 8458-8463. ISSN 0191-2216. ISBN 978-1-4244-3872-3.
  • Rok: 2009
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper describes a novel pointing&tracking feedback algorithm for an inertially stabilized double gimbal airborne camera system equipped with a computer vision system. The key idea is to enhance the intuitive decoupled controller structure with measurements of the camera inertial angular rate around its optical axis. The resulting controller can also compensate for the apparent translation between the camera and the observed object, but then the velocity of this mutual translational motion must be measured or estimated. The proposed algorithm turns out to be more insensitive to longer sampling periods of the computer vision system.

Noncontact Parallel Manipulation with Meso- and Microscale Particles Using Dielectrophoresis

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper gives a short overview of the authors' recent research activities at the intersection of microfluidics, electrokinetics and self-assembly. The particular research introduced in the paper aims at developing an electric-field-assisted self-assembly procedure for meso- and micro- (and possibly nano-) scale systems. The goal is to steer tiny particles such as LED chips, thick film resistors or microbeads submerged in a shallow liquid pool around by controlling electric voltage applied to an electrode array at the bottom of the pool. Dielectrophoresis as the major tool is introduced first, a brief report on numerical simulations using a commercially available FEM solver is then given, design and fabrication of the microfluidic chamber featuring microelectrode array is described in some detail, and finally laboratory experiments are presented. As an outcome of the experiments, a series of videos demonstrating various responses of particles were captured.

On stability tests of spatially distributed systems

  • Autoři: Augusta, P., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: 17th International Conference on Process Control´09. Bratislava: Slovak University of Technology, 2009, ISBN 978-80-227-3081-5.
  • Rok: 2009
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper describes tests of stability of spatially distributed shift-invariant systems discrete in both time and space. The systems are considered to be described by multivariate polynomial fractions, so, the tests based on manipulation with polynomials are taken into account. Method of root maps is depicted. Methods based on the Schur-Cohn criterion, originally formulated for systems with lumped parameters, are extended to multidimensional systems with support on a symmetric half-plane. Furthermore, the problem of stability of multivariate polynomial is formulated as a problem of stability of interval polynomial, which leads to use Kharitonov's theorem. Numerical examples are included.

POLMAT library now within Symbolic Math Toolbox for Matlab in multidimensional systems computations

  • Autoři: Augusta, P., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Proceedings of the 6th International Workshop on Multidimensional (nD) Systems. Thessaloniki: Aristotle University of Thessaloniki, 2009. pp. 55-57. ISBN 978-1-4244-2797-0.
  • Rok: 2009
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    This paper demonstrates convenient use of freely available Polmat library for computations with transfer function models of multidimensional systems within Matlab environment. Polmat functions rely on MuPAD, a computer algebra system, which has become the core engine for symbolic computations in Matlab. Basic manipulations with multivariate two-sided polynomials are illustrated, test of stability of spatially distributed systems and solution of linear (Diophantine) equations with multivariate polynomials are demonstrated by means of a few examples.

Towards array micromanipulators based on dielectric elastomers

  • Autoři: Řezáč, M., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Nanocon 2009 Conference Proceedings. Ostrava: Technická universita Ostrava - Vysoká škola báňská, 2009. ISBN 978-80-87294-13-0.
  • Rok: 2009
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper describes the authors' initial steps in the domain of advanced microactuators based on dielectric elastomers. Namely, local deformation of a thin (~10um) elastomer film as a result of Maxwell pressure on the surface is analyzed. The pressure results from attractive forces between the opposite charges on the conducting electrodes deposited on both sides of the polymer film. When at least one of the two electrodes is compliant, repulsive forces among the alike charges also contribute to the surface deformation. Compared to the conventional materials such as piezoelectric ceramics, DEA promise much higher strain (nearly 10%) while keeping reasonable values of other parameters such as efficiency and time response. The ultimate goal of this initiating research is to develop a deformable surface that could be used for planar manipulation with flat objects placed on top of it.

Tremor Analysis by Decomposition of Acceleration into Gravity and Inertial Acceleration Using Inertial Measurement Unit

  • Autoři: Šprdlík, O., doc. Ing. Zdeněk Hurák, Ph.D., Hoskovcová, M., Růžička, E.
  • Publikace: Proceedings of 9th Intrenational Conference on Information Technology and Applications in Biomedicine. Piscataway: IEEE, 2009. ISBN 978-1-4244-5378-8.
  • Rok: 2009
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    Decomposition of acceleration was investigated as an alternative to commonly used direct spectral analysis of measured acceleration or angular velocity for tremor quantification. Orientation estimation algorithm was devised to decompose the measured acceleration into inertial acceleration caused by sensor movement in inertial reference frame and gravitational artifact. Resulting signals, beside measured acceleration and angular velocity, were used to assess tremor amplitude and frequency by spectral peak detection. The algorithm was tested on experimental data from a clinical study including patients with essential tremor. Influence of sensor calibration and connections of results to analytic approach are analyzed briefly.

Algebraic approach to LQ-optimal control of spatially distsributed systems: 2-D case

  • Autoři: Augusta, P., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Proceedings of the 17th IFAC World Congress. Seoul: IFAC, 2008, ISSN 1474-6670. ISBN 978-3-902661-00-5.
  • Rok: 2008
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    In this paper we develop new results on control systems design for spatially distributed linear systems using an n-D systems approach. The basic ideas are explained using as an example heat conduction in a rod where the measurements and control action applied are based on an array of sensors and heaters. The first part of the analysis given shows how the process dynamics for this case can be approximately described by a 2-D transfer-function, i.e. a fraction of two bivariate polynomials. This is followed by stability analysis and tests. Finally, a simple algorithm for design of LQ controller is proposed.

Inerciálně stabilizovaná kamerová základna pro bezpilotní letoun

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    Tento článek představuje projekt gyroskopicky a vizuálně stabilizované kamerové základny pro bezpilotní letoun s automatickým sledováním poyemních cílů. Hlavním cílem článku je seznámit odbornou veřejnost s dosaženými výsledky projektu i s konw-how získaným řešitelským týmem.

On the control of distributed parameter systems using a multidimensional systems setting

  • Autoři: Cichy, B., Augusta, P., Rogers, E., Galkowski, K., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Mechanical Systems and Signal Processing. 2008, 22(7), 1566-1581. ISSN 0888-3270.
  • Rok: 2008

2-D Non-Causal Systems: Control of Tempterature Variation in a Rod

  • Autoři: Augusta, P., Frízel, R., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Proceedings of 16th Interantional Conference of Process Control 2007. Slovenská technická univerzita v Bratislave, 2007, ISBN 978-80-227-2677-1.
  • Rok: 2007
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    In this paper, we present polynomial approach to so-called non-causal linear systems. A variation of temperature in a rod is simulated. The rod with array of sensors and actuators placed along the rod is supposed to be a non-causal system and is described by fraction of two two-sided polynomials. Stability is found out, Youla-Kučera parametrisation is given and fixed-structure controller and optimal controller minimising H2 norm for variation of temperature in the rod are designed via polynomial techniques and numerically simulated. This development is motivated by need to describe and control spatially-distributed systems with application in, for instance, adaptive optics.

Ambulatory Assessment in Parkinson's Disease: Use of Inertial Sensors and Identification Filtering Techniques

  • Autoři: Šprdlík, O., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Proceedings of 16th Interantional Conference of Process Control 2007. Slovenská technická univerzita v Bratislave, 2007, ISBN 978-80-227-2677-1.
  • Rok: 2007
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    Paper gives a brief survey of existing methods for assessment of parkinsonian symptoms with focus on ambulatory assessment using body-worn sensors. Next part of paper deals with particular problem - in-use calibration of accelerometers based on detection of quasistatic states. Several methods are proposed and compared in simulations. An example of use of calibrated data is given.

An Algebraic Approach to the Control of Spatially Distributed Systems --- the 2-D Systems Case with a Physical Application

  • Autoři: Augusta, P., doc. Ing. Zdeněk Hurák, Ph.D., Rogers, E.
  • Publikace: Preprints of the 3rd IFAC Symposium on System, Structure and Control. Foz do Iguassu: Universidade Federal do Rio Grande do Sul - UFRGS, 2007, ISBN 978-3-902661-36-4.
  • Rok: 2007
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    In this paper we develop new results on control systems design for spatially distributed linear systems using an n-D systems approach. The basic ideas are explained using as an example heat conduction in a rod where the measurements and control action applied are based on an array of sensors and heaters. The first part of the analysis given shows how the process dynamics for this case can be approximately described by a 2-D transfer function, i.e. a fraction of two bivariate polynomials. This is followed by stability analysis and tests. Finally, a Youla-Kučera parametrization of all stabilizing controllers is used to develop a simple design procedure for H2-optimal control laws.

An Algebraic Approach to the Control of Spatially Distributed Systems: (2+1)D Case with a Deformable Mirror Example

  • Autoři: Augusta, P., doc. Ing. Zdeněk Hurák, Ph.D., Rogers, E.
  • Publikace: Proceedings of the 2007 International Workshop on Multidimensional (nD) Systems. Aveiro: University of Aveiro, 2007. ISBN 1-4244-1112-2.
  • Rok: 2007
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    In this paper we develop new results on control design for spatially distributed linear systems using an n-D systems approach. As a possible application example, we consider a deformable mirror used as a wavefront corrector in adaptive optical system. The first new results consist of stability analysis plus stability tests. This is followed by control law design in a polynomial setting where a Youla-Kučera parametrization of all stabilizing controllers is specialized to the objective of reducing vibrations of the mirror based on minimization of the H2 system norm.

Feedback Control for a High Precision Linear Stage

  • Autoři: Holub, O., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Proceedings of 16th Interantional Conference of Process Control 2007. Slovenská technická univerzita v Bratislave, 2007, ISBN 978-80-227-2677-1.
  • Rok: 2007
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper describes a computational design, software implementation and laboratory tests of a feedback position controller for a new type of monolithic "hybrid" ultrasonic motor. The motor has been developed at the collaborating High-Precision Robotics Group at EPFL. In a collaboration with this group we designed an advanced fast and precise position feedback controller. Tracking of 1 mm steps in reference with 30 nm error in down to 100 ms has been achieved.

Input Command Shaping for Piezoelectric Micro-Manipulators

  • Autoři: Špiller, M., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Proceedings of 16th Interantional Conference of Process Control 2007. Slovenská technická univerzita v Bratislave, 2007, ISBN 978-80-227-2677-1.
  • Rok: 2007
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper reports on applications of a special open-loop control technique called input command shaping to different types of piezoelectric micro-manipulators. First, we present a control design for bimorph piezoelectric actuator used for precise tactile stimulation of a whisker of a mouse. We describe a heuristic modification of a standard input shaping method allowing increase in the frequency of stimulating pulses. Second, we present a control design for a stick-slip piezoelectric positioner designed for a commercial electron microscope to increase the speed and repeatability of positioning.

Input Shaping for Whisker Stimulator

  • Autoři: Špiller, M., doc. Ing. Zdeněk Hurák, Ph.D., Kaegi, F.
  • Publikace: Proceedings of 2007 IEEE Muti-conference on Systems and Control. Singapore: National University of Singapore, 2007. ISSN 1085-1992.
  • Rok: 2007
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    In this paper, we report on a practical (laboratory) application of an input shaping method to a special piezoelectric actuator that is used to stimulate a whisker of a mouse. Precisely controlled tactile stimulation is necessary for neurological experiments studying cerebral processes of a mouse. Standard motivation for input (command) shaping is to suppress lightly damped modes of the actuator. Additionally, an extra requirement on minimizing the width of stimulation pulse appears in this application.

Localization of Hemodynamic Response from FMRI Data Using System Identification and Estimation Techniques

  • Autoři: doc. Ing. Zdeněk Hurák, Ph.D., Tauchmanová, J.
  • Publikace: Proceedings of 16th Interantional Conference of Process Control 2007. Slovenská technická univerzita v Bratislave, 2007, ISBN 978-80-227-2677-1.
  • Rok: 2007
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper reports on our early attempts to approach the problem of modeling and localization of human brain neural response as a system identification and estimation task. It also brings a comprehensive survey of research literature, mainly from outside the systems and control field.

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

  • DOI: 10.1002/rnc.1128
  • Odkaz: https://doi.org/10.1002/rnc.1128
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    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.

Řízení piezoelektrických motorů pro mikropolohování

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    Článek stručně přibližuje návrh a implementaci řídicích algoritmů piezoelektrických pohonů určených pro velmi přené nastavení polohy v malém rozsahu pohybů.

Banded Matrix Solvers and Polynomial Diophantine Equations

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    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.

Dynamical Modelling and Position Control of Ultrasonic MonolithicPiezoelectric Actuator for Mobile Microrobots

  • Autoři: Holub, O., Cimprich, T., Ferreira, A., doc. Ing. Zdeněk Hurák, Ph.D., Breguet, J.-M.
  • Publikace: Proceedings of the 2006 IEEE International Ultrasonics Symposium. New Jersey: IEEE, 2006, ISBN 1-4244-0201-8.
  • Rok: 2006
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper describes development of a feedback position controller for a new type of monolithic "hybrid" ultrasonic motor. The goal of the controller design was to demonstrate the main advantage of this piezoelectric motor - high speed and high accuracy at the same time. Tracking of 1 mm steps with 30 nm error in down to 100 ms has been achieved.

Input Command Shaping For a Stick-Slip Piezoelectric Micro Positioning Stage

  • Autoři: Špiller, M., Holub, O., doc. Ing. Zdeněk Hurák, Ph.D., Honců, J.
  • Publikace: Proceedings of International Control Conference. Glasgow: University of Strathclyde, 2006.
  • Rok: 2006
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    This paper reports on a laboratory application of a special type of feedforward control design technique, which is named input command shaping, or posicast control. The actual laboratory platform described in this paper is a three-axis piezoelectric stick-slip micropositioning stage custom-designed by an industrial partner for their commercial transmission electron microscope.

Inverse iteration for total least squares interpretted as combination of least squares problem and rotation of coordinates

  • Autoři: Šprdlík, O., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Fourth Total Least Squares and Errors-in-Variables Modeling Workshop. Leuven: Katolieke Universiteit Leuven, 2006, pp. 66-68.
  • Rok: 2006
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    Inverse iteration method is one of the most powerful methods for computing selected eigenvectors. It can also be used for finding numerical solution to total least squares problem (TLS) . Recently, some new algorithms appeared in literaturethat approach the numerical computation of TLS problem via iterative algorithm in which at each iteration standard least squares problem (LS) is solved and the orthogonal coordinate system is rotated such that it is aligned with the solution vector. However promising such QR-based approach appears because of its easy extensibility for recursive computation in system identification, it is shown in this note, that such approach is in the view of iteration results equivalent to the inverse iteration method.

Minimum Distance to The Range of a Banded Lower Triangular Toeplitz Operator in l1 and Application in L1-Optimal Control

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The subject of the paper is the best approximation in l1 of a given infnite sequence by sequences in the range of a given banded lower-triangular Toeplitz operator. Necessary and sufficient conditions for the existence of a minimizing solution are established and a numerical algorithm for finding such a solution is designed and theoretically founded. It is also shown that an optimal error sequence is only fnitely nonzero. The relevancy of the problem in systems theory is outlined and numerical examples are presented.

Multidimensional Transfer Function Model of a Deformable Mirror in Adaptive Optics Systems

  • Autoři: Augusta, P., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Proceedings 17th International Symposium on: Mathematical Theory of Networks and Systems. Kyoto: Kyoto University, 2006, pp. 1556-1561.
  • Rok: 2006
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    This paper reports on the first attempts to obtain a control-oriented model of the adaptive optics system in the framework of multidimensional systems. The concrete outcome of this work is a 3D transfer function describing dynamics of the deformable mirror playing the role of a wavefront corrector, the most important part of an adaptive optics system. The motivation for this development was application of advanced theoretical and computational results from the multidimensional system theory to the task of analysis and synthesis of spatially distributed control system for adaptive optics.

Stick-Slip Based Micropositioning Stage for Transmission Electron Microscope

  • Autoři: Holub, O., Špiller, M., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Proceedings of the 9th IEEE International Workshop on Advanced Motion Control. New Jersey: IEEE, 2006. ISBN 0-7803-9511-1.
  • Rok: 2006
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    This paper presents work that has been done on design of a micropositioning stage for a transmission electron microscope. Topics covered include mechanical design of the positioning stage, sawtooth-like high voltage generator, report on experimental identification of the system, some thoughts and experience with input command shaping, finite-element analysis and design of capacitive 2-axis position sensor and design of signal processing circuitry for this sensor.

Uživatelské rozhraní pro návrh frekvenčních filtrů

  • Autoři: Řezáč, M., Holub, O., Augusta, P., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Proceedings of Process Control 2006. Pardubice: University of Pardubice, 2006,
  • Rok: 2006
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    Cˇ la´nek popisuje graficke´ uzˇivatelske´ rozhranı´ pro balı´k Matlab, slouzˇı´cı´ k pohodlne´mu na´vrhu frekvencˇnı´ch filtru°. Prˇı´nos tohoto GUI spocˇı´va´ v mozˇnosti zada´vat parametry va´hovy´ch filtru° pro optimalizaci tvaru citlivostnı´ch funkcı´ zpeˇtnovazebnı´ho syste´mu zalozˇenou na minimalizaci jejich va´hovany´ch H1 norem. Parametry vhodne´ pro tento prˇı´pad se lisˇı´ od specifikace beˇzˇneˇ pouzˇı´vane´ v oblasti zpracova´nı´ signa´lu°. Navrzˇene´ GUI tak z uzˇivatele, inzˇeny´ra navrhujı´cı´ho regulacˇnı´ obvod, sejı´ma´ potrˇebu ovla´dat analyticka´ vyja´drˇenı´ prˇenosu° va´hovacı´ch filtru°, cozˇ zrychluje a zpohodlnˇuje jeho pra´ci. Pouzˇitelnost GUI je demonstrova´na na prˇı´kladu na´vrhu regula´toru polohy koncove´ho bodu pruzˇne´ho ramene, prˇipojene´ho na hrˇı´del stejnosmeˇrne´ho motoru.

Banded Matrix Solvers and Polynomial Diophantine Equations

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    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.

Detekce prokluzu kola a odhad rychlosti kolejového vozidla s užitím Kalmanova filtru

  • Autoři: Holub, O., Augusta, P., Roubal, J., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: 15th International Conference on Process Control 05. Bratislava: Slovak University of Technology, 2005, ISBN 80-227-2235-9.
  • Rok: 2005
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    Kolejová vozidla, vedle svých výhod, jako je např. malý jízdní odpor, majízásadní nevýhodu pramenící z malého součinitele adheze mezi ocelovým kolem a kolejnicí. Celá tažná či brzdná síla, kterou je pohon schopen poskytnout, mnohdy nemůže být z kola na kolejnici přenesena. Při jízdě tak dochází ke skluzu, případně ke smyku a měřená rychlost kola neodpovídá rychlosti vozidla. Metoda identifikace tohoto jevu použitá v článku vychází z prahování diference měřené rychlosti. Diference měřeného signálu je citlivá na šum měření. Vliv šumu je potlačován pomocí Kalmanova filtru, jehož účinnost je dále zvýšena vyhlazováním. K získání co nejlepšího odhadu rychlosti vozidla jsou současně využívány měřené rychlosti všech náprav vozidla. Praktická použitelnost uvedeného přístupu je demonstrována na reálných datech.

FEM Simulace převodní charakteristiky kapacitního senzoru polohy

  • Autoři: Holub, O., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Technical Computing Prague 2005: 13th Annual Conference Proceedings. Praha: VŠCHT, 2005, ISBN 80-7080-577-3.
  • Rok: 2005
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    Článek podává zprávu o simulacích závislosti kapacity senzoru polohy na měřenévýchylce. Očekávané využití pro polohování stolku elektronového mikroskopu klade na senzor značná omezení. Není proto možné využít standardních výsledků z oblasti návrhu kapacitních snímačů. Místo toho byly provedeny simulace pro získání představy o vlivu některých parametrů senzoru na jeho převodní charakteristiku. Na základě pořízených výsledků byl navržen a je v současné době konstruován senzor odpovídajících parametrů.

H_Infinity-Optimization Based Loopshaping Control Design for a Laboratory Flexible Arm

  • Autoři: Holub, O., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: 15th International Conference on Process Control 05. Bratislava: Slovak University of Technology, 2005, ISBN 80-227-2235-9.
  • Rok: 2005
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper describes in detail a complete control design procedure for a commercial laboratory servosystem with flexible arm. Covered are: mathemacial modelling using Hamilton principle and Euler-Bernoulli assumpitions, experimental identification in time and frequency domain, design of a noncollocated robust feedback controller using H_infinity optimization and experimental laboratory verification. The lesson learnt might be of use for a person involved in design of control for flexible structures.

Polmat: MuPAD Library for Polynomial Matrices

  • Autoři: Augusta, P., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: 15th International Conference on Process Control 05. Bratislava: Slovak University of Technology, 2005, ISBN 80-227-2235-9.
  • Rok: 2005
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper presents a new freely available library for symbolic computationwith polynomial matrices. The library is developed for MuPAD, which is an easilyaccessible efficient programming language and comfortable environment for symbolicmath. The Polmat library is focused on algorithms useful in control and filter designsuch as solvers for linear equations with polynomials and polynomial matrices andspectral factorisation of polynomial matrices.

Polmat: MuPAD Library for Polynomial Matrices

  • Autoři: Augusta, P., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Proceedings of the 16th World Congress of the International Federation of Automatic Control. Praha: IFAC, 2005. ISSN 1474-6670. ISBN 978-0-08-045108-4.
  • Rok: 2005
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper presents a new freely available library for symbolic computationwith polynomial matrices. The library is developed for MuPAD, which is an easilyaccessible efficient programming language and comfortable environment for symbolic math. The Polmat library is focused on algorithms useful in control and filter design such as solvers for linear equations with polynomials and polynomial matrices and spectral factorisation of polynomial matrices.

Soudobý návrh regulátoru pro teleskop VLT pomocí optimalizace Hinf

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    Pro návrh regulátoru polohy obřího teleskopu VLT, který provozuje mezinárodní organizace ESO na hoře Cerro Paranal v chilské poušti Atacama, byly použity moderní výpočetní metody robustního a optimálního řízení. Tyto metody jsou založeny na minimalizaci normy Hinf přenosu systému, což je úloha lehce řešitelná běžnými sadami programů pro návrh řízení.

Fixed-order robust controller design with the Polynomial Toolbox 3.0

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    With the help of numerical examples, this paper describes new fixed-order robust controller design functions implemented in version 3.0 of the Polynomial Toolbox for Matlab. The functions use convex optimization over linear matrix inequalities (LMIs) solved with the SeDuMi solver.

MIMO l1-optimal control via block Toeplitz operators

  • Autoři: doc. Ing. Zdeněk Hurák, Ph.D., Boetcher, A.
  • Publikace: Proceedings Sixteenth International Symposium on: Mathematical Theory of Networks and Systems. Leuven: Katholieke Universiteit, 2004, ISBN 90-5682-517-8.
  • Rok: 2004
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    The paper is devoted to the standard problem of l1-optimalcontrol for MIMO systems, that is, to the design of a feedback compensatorthat minimizes peaks in the amplitude of the regulated variablesunder the assumption that the exogenous variables are bounded in magnitude andpersistent. The solution proposed avoids interpolationcompletely and is therefore distinguished by fine numerical properties.An alternative proof for the finiteness of the impulseresponse in the square (one-block) case is given, while both lowerand upper bounds for the optimal value of the norm areestablished in the general multiblock case.

Time to go Hinf?

  • Autoři: doc. Ing. Zdeněk Hurák, Ph.D., Erm, T., Bauvir, B.
  • Publikace: Advanced Software, Control, and Communication Systems for Astronomy. Bellingham, WA: The International Society for Optical Engineering, 2004, pp. 68-78. ISSN 0277-786X. ISBN 0-8194-5428-1.
  • Rok: 2004
  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    This paper describes a complete controller design procedure for an altitude axis of the 8.2m Very Large Telescope (VLT) at European Southern Observatory (ESO) at Cerro Paranal, Chile. The design relies on minimization of the Hinf norm of a frequency weighted closed-loop transfer function. Computational routines from Robust Control Toolbox for Matlab have been used and the paper demonstrates their usage. The results are compared with the existing solution based on a two-loop PI controller with notch filters.

Using LAPACK Solvers for Structured Matrices within Matlab

  • Pracoviště: Katedra řídicí techniky
  • Anotace:
    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.

Algebraic Approach to I1-Optimal Control: SISO case

Discussion on: "Frequency weighted Balanced Truncation: Hankel Singular Values and Error Bounds" by T. Van Gestel, B. de Moor, b.D.O. Anderson and P. Van Overschee

MATHML for Data Exchange

MathML for Data Exchange

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

Tool for Visualization of Stability Area for a Polynomial with Two Uncertain Parameters

  • Autoři: Urban, P., doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: Proceedings of Process Control '03. Bratislava: Slovak University of Technology, 2003, pp. 94-1-94-3. ISBN 80-227-1902-1.
  • Rok: 2003

Algorithm for Computing l1 Norm of a Polynomial matrix Fraction

  • Autoři: doc. Ing. Zdeněk Hurák, Ph.D.,
  • Publikace: POSTER 2002 - Book of Extended Abstracts. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 2002, pp. IC21.
  • Rok: 2002

Algorithm for Computing l1 Norm of a Polynomial Matrix Fraction

Algorithm for Computing the Induced Gain of LTI System

MathML in Polynomial Toolbox for Matlab

MathML in Polynomial Toolbox for Matlab

Návrh l1 optimalního regulátoru

On Computing the l1 Norm of a Polynomial matrix Fraction

Polynomial Spectral Factorization with Complex Coeficients

Robust Control of a Laboratory Servomechanism

On Robust Stability of Complex Polynomial

On Robust Stability of Complex Polynomials

Polynomial Toolbox in Control Education

Robust Control Analysis and Design with Polynomial

Stability of Sampled-data Systems with Uncertain Delays

Za stránku zodpovídá: Ing. Mgr. Radovan Suk