Ing. Filip Svoboda

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

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

The design of adaptive control for an aeroelastic wing using structured H∞ synthesis is presented in this paper. The algorithm uses a polynomial interpolation of controller parameters for a wide airspeed range. The structure of control law is fixed, with its parameters determined for a given airspeed range. We demonstrate the possibilities of such a controller for active flutter suppression on the linear parameter-varying (LPV) servoaeroelastic wing model with two ailerons.

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

This paper describes the development of the smart morphing trailing edge demonstrator intended for wind tunnel experiments and control laws validations. Our design puts great emphasis on smooth transitions between individual actuated segments. The technology of 3D printing has been used for wing parts production. Trailing edge actuation is ensured by macro fiber composite (MFC).

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

Distributed control is nowadays a very active field of research, thanks to potential applications which require high scalability and reliability. The paper deals with the optimization of active vibration suppression of the planar flexible systems equipped by regular and dense matrix of multiple sensors and actuators. The H infinity design with predefined controller structure has been chosen as an appropriate control method. At first, performance of H-infinity regulator was experimentally tested on simple beam demonstrator with piezoelectric patches as sensors and actuators. The simulation model of larger planar demonstrator has been firstly modelled by FEM and then exported into the state space form. Decentralized and distributed control laws have been investigated. The feasibility of attenuation of a large set of flexible modes has been demonstrated for the model of the demonstrator. The demonstrator itself has been prepared for the ongoing experiments. The possibility of alternative actuation by clusters of actuators has been also analyzed.

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

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

The finite element based structural model of a flexible wing is presented. The structural model will be a part of a servoelastic wing used for flutter analysis and designing flutter suppression control systems. It also allows modal analysis of a wing with given parameters. A finite element model consists of Euler-Bernoulli beams joined together. This approach is able to reach high accuracy and various properties of a particular wing element can be modeled.

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

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

The article deals with developing a mathematical model of non-rigid aircraft lifting surface with control surface controlled by pilot and supplementary control surface driven by control law. The purpose of this model is to determine if such as concept of control surface and supplementary control surface can be used for active flutter suppression on an aircraft structure. The supplementary control surface is placed next to the control surface at outboard side. The lifting surface is representing by an airfoil placed at 70% of a wing span. A structural model is developed by means of Lagrange differential equations of second kind. Theodorsen model of thin oscillation airfoil with control surface is used for unsteady aerodynamic. Duhamel’s integral of Wagner function is carried out for transformation of unsteady aerodynamic to a time domain. The mathematical model is present in state space representation. There is exemplification of the critical flutter velocity calculation and a dynamical response of the structure. The supplementary control surface for flutter suppression with simplified model is added. Closed-loop feedback control system is formed and a several control laws are presents. The verification of open-loop model is done on behalf of the critical flutter speed comparison with FEM software for flutter analysis MSC.Nastran and flutter analysis program developed at CTU in Prague. The article also presents work on an experimental verification of the open-loop model in aerodynamic tunnel.

The article deals with developing a mathematical model of non-rigid aircraft lifting surface with control surface controlled by pilot and supplementary control surface driven by control law. The purpose of this model is to determine if such as concept of control surface and supplementary control surface can be used for active flutter suppression on an aircraft structure. The supplementary control surface is placed next to the control surface at outboard side. The lifting surface is representing by an airfoil placed at 70% of a wing span. A structural model is developed by means of Lagrange differential equations of second kind. Theodorsen model of thin oscillation airfoil with control surface is used for unsteady aerodynamic. Duhamel’s integral of Wagner function is carried out for transformation of unsteady aerodynamic to a time domain. The mathematical model is present in state space representation. There is exemplification of the critical flutter velocity calculation and a dynamical response of the structure. The supplementary control surface for flutter suppression with simplified model is added. Closed-loop feedback control system is formed and a several control laws are presents. The verification of open-loop model is done on behalf of the critical flutter speed comparison with FEM software for flutter analysis MSC.Nastran and flutter analysis program developed at CTU in Prague. The article also presents work on an experimental verification of the open-loop model in aerodynamic tunnel.

ELEKTRON I je reaktivní nosič určený pro výuku aerodynamiky a ověřování elektroniky, měřících a řídících algoritmů na létajících prostředcích s vysokou dynamikou pohybu.