Dynamic Output Feedback Controller Research Articles

Multiple delay-dependent finite-time fault-tolerant control for switched fuzzy systems

The work is concerned with this issue of multiple delay-dependent finite-time fault-tolerant control (FTC) for uncertain switched Takagi-Sugeno (T-S) fuzzy systems against state and input constraints. There exist intermittent faults (IFs), exogenous disturbances along with measurement noise in the models. There are few attempts for this theme. A nonlinear dynamic output feedback controller is explored for these uncertain switched T-S fuzzy systems first. And an augmented system with respect to realizing FTC is acquired. Moreover, sufficient conditions of robust finite-time H∞ control are constructed by piecewise fuzzy Lyapunov function. At the same time, finite-time boundedness (FTB) as well as input-output finite-time stability (IO-FTS) is achieved. The effectiveness as well as feasibility of this approach is verified through an example.

$$H_{{\infty }}$$ dynamic output feedback control for time-varying delay singular Markovian jump systems based on variable elimination technique

$$H_{{\infty }}$$ dynamic output feedback control for time-varying delay singular Markovian jump systems based on variable elimination technique

Non-cooperative differential game based output feedback control for spacecraft attitude regulation

Retired spacecraft attitude takeover control using two types of cellular space modules, namely orientation cellular space module (OCSM) and rate cellular space module (RCSM), is considered in this paper. Both the OCSM and the RCSM are endowed with identical mechanical actuators for providing 3-axis torques for attitude regulation. The difference is: the OCSM is equipped with orientation sensors which provide unit-length vector measurements to determine attitude, while the RCSM is mounted with rate sensors which measure angular velocities. Correspondingly, the attitude takeover controller is composed of a pre-wrap proportional control part and an output (angular velocity) feedback control part, which are executed by the OCSM and the RCSM respectively. A gain-scheduled control framework is adopted in order to formulate the rate feedback control part as subcontrollers for RCSMs. Two kinds of output feedback subcontrollers are proposed: a static output feedback control scheme with constant gains which are yielded from the linear–differential-game-based output feedback control; and a dynamic output feedback control scheme which is developed using the Kalman–Yakubovich–Popov Lemma and the linear–differential-game-based state feedback control. Both output feedback control schemes possess robustness to modeling errors, since the stability of the closed-loop systems hinge on the passivity theorem rather than the inertia properties of the retired spacecraft. Numerical simulation results show the effectiveness of the proposed controllers for attitude takeover control of a retired spacecraft fixed with the OCSM and the RCSM. A comparison between the proposed methods and an existing method is carried out to show the benefits of the proposed controllers.

Robust dynamic output feedback stabilization for uncertain singular Markovian jump systems with time‐varying delays

AbstractThe article investigates robust dynamic output feedback (DOF) stabilization for uncertain time‐varying delays singular Markovian jump systems (SMJSs). First, by using improved Lyapunov–Krasovskii functional, sufficient conditions of robust admissibility (namely regularity, non‐impulsiveness, and asymptotic stability) for unforced nominal time‐varying delays SMJSs are given. Second, by constructing a DOF controller such that the resulting closed‐loop system satisfies robust admissibility, the robust DOF stabilization problem is solved in terms of linear matrix inequalities via orthogonal complement technique. Finally, the availability and practicality of the prime results are certified by two numerical examples and a practical example of the oil catalytic cracking process.

Robust $H_{\infty }$ Dynamic Output-Feedback Control for CACC With ROSSs Subject to RODAs

This paper is concerned with the problem of dynamic output feedback control design for the cooperative adaptive cruise control (CACC) system with randomly occurring sensor saturations (ROSSs) subject to randomly occurring deception attacks (RODAs). The dynamics of the vehicle equipped with CACC system behave like a linear model in which the deviation of the position and velocity are chosen as the state variables. Sensor saturations and deception attacks are simultaneously taken into account, and two sets of Bernoulli random variables are utilized to characterize their nature of random occurrence. The main objective of this article is to develop a robust dynamic output feedback controller (RDOFC) such that, for all possible parameter uncertainties, sensor saturations as well as deception attacks, all the states can still be exponentially mean square stable and the <inline-formula><tex-math notation="LaTeX">$H_{\infty }$</tex-math></inline-formula> performance index is guaranteed. In light of the Lyapunov stability theory, a sufficient condition of the desired controller is firstly constructed, then the controller parameters are obtained relying on the solutions to a set of linear matrix inequalities (LMIs). Finally, the three-car platoon system is evaluated to validate the usefulness of the developed algorithm.

Strong γc - γcl H∞ Stabilization for Networked Control System Based on Lyapunov Function and DoS Attacks

This paper is concerned with the strong γc - γcl H∞ stabilization for networked control system under DoS attacks with limited communication bandwidths. The quantizer is employed to the network transmission channel from sensor-to-controller in order to reduce the unnecessary data transmissions. In the network environment, it is assumed that there exist DoS attacks in the transmission channel from controller-to-actuator. By describing DoS attacks as the probability models subject to the Bernoulli distribution, the network control system is modeled as the system with random parameters. With this model, a dynamic output feedback controller is designed, which satisfies the given H∞ bound norm γc . Under the action of the controller, the closed-loop system is exponential stable in the mean-square sense and satisfies H∞ bound norm γcl . Especially, a Lyapunov function based on quantization error and attack probability is proposed in the stability analysis. Finally, the effectiveness of the proposed method is verified by a simulation example.

Dynamic output feedback control for networked control systems: A sum-based discrete event-triggered approach

This paper investigates the event-based dynamic output feedback control for networked control system with actuator failures. A novel sum-based discrete event-triggered mechanism (SDETM) is proposed, whose triggering condition includes not only the current sample of system states but also previous samples. With the proposed SDETM, a dynamic output feedback controller (DOFC) is developed under a general networked control system (NCS) structure. We consider a general system structure where two network channels are involved, and the proposed SDETM is employed to both networks to extensively save network resources. A novel stability criteria is established for the closed-loop system based on the Lyapunov-Krasovskii functional method. By using the Cone-complimentarity Linearization (CCL) approach, sufficient conditions are derived to co-design the DOFC and triggering parameters. The effectiveness and advantage of the proposed method is verified by a satellite control system.

Controller Synthesis of Asynchronous Periodic Event-Triggered Networked Control Systems Subject to Quantization Effects

This paper aims at analyzing the input-to-state stability (ISS) of the networked control systems (NCSs) where the sensor-to-controller and the controller-to-actuator channels are equipped with different dynamic quantizers and event-triggering laws. In the scenarios of quantization effects and external disturbances, we propose to use an asynchronous periodic event-triggering mechanism (PETM) and an improved dynamic quantization scheme. The PETM has potential to reduce the network transmissions compared with the time-based one on the one hand, and is natural for the practical applications (e.g. the digital platforms) on the other hand. The asynchronous PETM, dynamic quantization effects and external disturbances are incorporated by a hybrid dynamical framework. With the help of a technique combining the hybrid system theory and a novel constructed Lyapunov function, the co-design problem of asynchronous periodic event-triggering conditions, dynamic output-feedback control and dynamic quantizer is firstly addressed thereby ensuring the ISS of the NCSs. Moreover, the proposed controller has an intuitive and explicit form, which can be solved easily. To assess the feasibility of the proposed method, a simulation is provided.

TDS-CONTROL: a MATLAB package for the analysis and controller-design of time-delay systems*

This paper presents TDS-CONTROL, a MATLAB package for the analysis and design of controllers for linear time-invariant systems with discrete delays. The code is based on a state-space representation of such systems in terms of delay-differential algebraic equations with input, output, and state delays. As such, a broad class of (interconnected) systems can be considered, including neutral systems. The controller design algorithms are based on optimizing a certain objective function, such as the spectral abscissa, the H-infinity norm, or the pseudo-spectral abscissa, with respect to the controller parameters. For example, to design a stabilizing controller the spectral abscissa, i.e., the real part of the right-most characteristic root, is minimized. As a strictly negative spectral abscissa is a necessary and sufficient condition for stability, the presented design method is not conservative and a stabilizing controller can be computed whenever it exits. This comes however at the cost of having to solve a non-smooth, non-convex optimization problem. The class of considered controllers consists of static and dynamic output-feedback controllers. By allowing to fix certain entries in the controller matrices, it is also possible to design structured controllers such as decentralized, overlapping and PID controllers. Finally, as a wide-range of delay systems can be considered, the software package takes the sensitivity of certain quantities, such as the spectral abscissa and the H-infinity norm, with respect to infinitesimal delay perturbations explicitly into account.

Dynamic output-feedback control of continuous-time Lur'e systems using Zames-Falb multipliers by means of an LMI-based algorithm

This paper investigates the problems of stability analysis and control design for continuous-time Lur'e systems with slope bounded nonlinearities. Starting from a stability analysis condition from the literature, based on the real positivity and a bound to the L1 norm of a certain transfer function, new sufficient conditions are proposed in an augmented parameter space for the simultaneous existence of a stabilizing dynamic output-feedback controller and a Zames-Falb multiplier certifying the closed-loop stability. The matrices of the controller realization as well as of the Zames-Falb multiplier appear affinely in the conditions, being dealt with as optimization variables. Furthermore, no line search is required to enforce the L1 norm constraint. An iterative algorithm is constructed to solve the problem through semidefinite programming, providing dynamic controllers of any given order. The controller can take into account both the output of the linear part of the system and of the nonlinearity. Numerical examples illustrate the results.

On Robustification of Sampled-Data Dynamic Output-Feedback Stabilizers for Control-Affine Nonlinear Systems

In this paper, the robust sampled&#x2013;data stabilization of nonlinear systems is investigated. In particular, a methodology for the design of robust sampled&#x2013;data Dynamic Output Feedback Controllers (DOFCs) is provided for control&#x2013;affine nonlinear systems affected by actuation disturbances and measurement errors. The notion of dynamic output steepest descent feedback, continuous or not, induced by suitably Control Lyapunov functions is used together with the ISS redesign methodology for the development of the proposed robust sampled&#x2013;data stabilizer. Under the assumption that the actuation disturbances and measurement errors are bounded with a&#x2013;priori known bounds and that the measurement error affects marginally the control term designed via the ISS redesign methodology it is proved that: there exists a suitably fast sampling such that the proposed sampled&#x2013;data DOFC yields semi&#x2013;global practical stability of the related closed&#x2013;loop system regardless of the above actuation disturbances and measurement errors. In the methodology here proposed, time&#x2013;varying sampling periods are allowed and the intersampling system behaviour is taken into account. The provided results are validated on a chemical reactor system.

DrStabilization: A Matlab-based Software to Design Structured Time-delay Controllers

A new Matlab-based software called DrStabilization is introduced. The main purpose of the software is to stabilize multi-input multi-output linear time-invariant systems which may have an arbitrary number of discrete time-delays. The stabilization problem is formulated as the minimization of spectral abscissa function over the controller parameters. By modifying this problem, it is also possible to consider strong stability, i.e., stability achieved by a stable controller. The software allows designing structured dynamic output feedback controllers. By structuring the controller matrices, one can design decentralized controllers and/or well-known servocompansators such as PI/PID/PIR. Furthermore, the software also allows designing time-delay controllers in which case an arbitrary number of artificial time-delays can be introduced both to the I/O channels and the dynamics of the controller itself. The utilization of the software is illustrated through an example.

Design of Robust Dynamic Output Feedback Event-Triggering Controllers for Nonlinear Uncertain Systems

This paper presents a design of dynamic output feedback event-triggering control for nonlinear uncertain networked control systems. The plant and actuator asynchronously transmit the measurement and control signals over two different communication channels. We address the norm-bounded time-varying parameter uncertainties in a nonlinear plant. First, considering the exogenous disturbances and noises in the control and measurement signals, sufficient conditions for the <i>L</i>₂ stability of the nonlinear networked control systems are given in the presence of the uncertainties. Then, we propose design conditions to choose the dynamic output feedback control and triggering laws in terms of linear matrix inequalities (LMIs). The proposed conditions enable the controller and event-triggering parameters to be jointly optimized to lessen the number of transmissions, guaranteeing a certain level of <i>L</i>₂ gain. Numerical examples demonstrate the effectiveness of the proposed method.

A sum-based discrete event-triggered dynamic output feedback control for interval type-2 fuzzy systems

The current study concentrates on the event-based controller design for nonlinear networked systems characterized by the interval type-2 (IT2) fuzzy model. An innovative sum-based discrete event-triggered mechanism (SDETM), whose triggering condition includes several previous measurement samples, is proposed. Compared to the traditional event-triggered mechanism (ETM), the novel SDETM requires less network resources consumption. A dynamic output feedback controller (DOFC) is designed to achieve stability of the system. A novel stability criteria is established via the Lyapunov–Krasovskii functional method with the prescribed H∞ performance. Co-design of the DOFC and SDETM parameters is carried out using the cone complimentarity linearization (CCL) algorithm. The effectiveness of the proposed method is demonstrated with two practical cases.

An improved approach to fuzzy dynamic output feedback H ∞ control of continuous-time Takagi–Sugeno fuzzy systems

This paper studies the problem of dynamic output feedback control for continuous-time Takagi–Sugeno fuzzy systems. Based on the fuzzy Lyapunov functions without the special structure, a controller design method is developed and the relaxed stabilisation conditions are proposed. First, some shortcomings of the existing results are improved and a new approach is proposed for bounding the time derivatives of the membership functions. Then, less conservative conditions are obtained by introducing regulable parameters and applying the matrix decoupling techniques, which guarantee the prescribed performance. Moreover, the relaxation technique proposed in this paper is also suitable for the fuzzy system with immeasurable premise variables. Finally, some examples are provided to demonstrate the validity of the approach.

Frequency information based memory dynamic output feedback control for discrete‐time systems

AbstractThis article studies the problem of frequency information based memory dynamic output feedback (MDOF) control for discrete‐time systems. A novel design method for MDOF controllers is proposed based on not only the current output measurements and controller states, but also useful past output measurements and controller states, which tend to be less conservative than conventional memoryless controllers. Sufficient conditions are derived to guarantee the asymptotic stability with finite frequency specifications of the closed loop system, and then MDOF controller synthesis results are obtained in the form of linear matrix inequalities, which include the conventional memoryless and/or non‐frequency information based control methods as their special cases. It is also proved that the control performance can be enhanced with the increase of the memory capacity of the MDOF controller. Finally, simulation studies are given to show the effectiveness and advantages of the proposed MDOF controller design method over the conventional memoryless and/or non‐frequency information control approaches.

Observer-Based Control of LPV Systems with Input Delay and Saturation and Matched Disturbances via a Generalized Sector Condition

This paper examines the control design for parameter-dependent input-delay linear parameter-varying (LPV) systems with saturation constraints and matched input disturbances. A gain-scheduled dynamic output feedback controller, coupled with a disturbance observer to cancel out input disturbance effects, was augmented with an anti-windup compensator to locally stabilize the input-delay LPV system under saturation, model uncertainty, and exogenous disturbances. Sufficient delay-dependent conditions to asymptotically stabilize the closed-loop system were derived using Lyapunov-Krasovskii functionals and a modified generalized sector condition to address the input saturation nonlinearity. The level of disturbance rejection was characterized via the closed-loop inducedL2-norm of the closed-loop system in the form of linear matrix inequality (LMI) constraints. The results are examined in the context of the mean arterial pressure (MAP) control in the clinical resuscitation of critical hypotensive patients. The MAP variation response to the injection of vasopressor drugs was modeled as an LPV system with a varying input delay and was susceptible to model uncertainty and input/output disturbances. A Bayesian filtering method known as the cubature Kalman filter (CKF) was used to estimate the instantaneous values of the parameters. The varying delay was estimated via a multiple-model approach. The proposed input-delay LPV control was validated in closed-loop simulations to demonstrate its merits and capabilities in the presence of drug administration constraints.

Memory dynamic output feedback controller based on asynchronous event‐triggered robust H‐infinity control for nonlinear ICPSs under data injection attacks

AbstractAiming at reducing the influence caused by data injection attacks, an asynchronous event‐triggered robust H‐infinity control (AERHC) is proposed for the stability of nonlinear ICPSs suffering from data injection attacks. A robust H‐infinity memory dynamic feedback control technique is designed to guarantee asymptotic stability of the closed‐loop system under a Lyapunov functional and the robust stability criterion. Furthermore, a memory dynamic feedback controller which has five controller gains different from each other for mitigating the conservative of nonlinear ICPSs and for resisting data injection attacks in ICPSs. Meanwhile, an asynchronous event‐triggered strategy is adopted to reduce the data communication frequency among nonlinear ICPSs components, and it effectively handle the influence of coupling problem between the measurement channel and the control channel. Finally, simulation tests are conducted by using MATLAB to control the robustness of the motor angle position of electromechanical system by using AERHC, which verify that the correctness and effectiveness of the proposed method.

Optimal Frequency Regulation in AC Mobile Power Grids Exploiting Bilinear Matrix Inequalities

By day-to-day improvement in a microgrid (MG) control, frequency regulation in the shipboard alternating current (ac) MGs has received much interest in the past decade. The shipboard MGs involve renewable energy sources (RESs) that are unable to produce reliable and constant energy. This important fact vividly demonstrates the requirement of modern frequency regulation techniques. This article proposes a novel dynamic output feedback controller (DOFC) for load frequency control (LFC) in a sample shipboard MG. The considered ac MG involves fuel cell, gas turbine, and diesel generator as the controllable power generators; photovoltaic array and sea wave energy converter as the renewable energy sources; and batteries and flywheels as the storage units. The existing approaches almost exploit linearization for solving the problem, which imposes restrictions on the problem and raises conservative constraints resulting in shrinking the solution space. This article suggests a simple approach that effectively reduces such limitations through the formulation of sufficient conditions on the controller design in the form of bilinear matrix inequalities (BMIs). This consequences in a more exact solution compared to the previous methods. To show the merits of the developed approach, OPAL real-time (RT) simulations are executed, and the results are compared to the other state-of-the-art-methods that prove the efficacy of the suggested approach. Also, the results of our proposed method (DOFC; <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n=2$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n=3$ </tex-math></inline-formula> ) are compared to the typical <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm {H}_{\infty }$ </tex-math></inline-formula> optimization, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mu }$ </tex-math></inline-formula> -synthesis, fuzzy type-1, and intelligent-PI methods. The comparisons between norms of the frequency deviation verify the efficacy of the proposed controller in this article.

Output Feedback Sliding Mode Control of Markovian Jump Systems and Its Application to Switched Boost Converter

This paper presents a sliding mode dynamic output feedback controller design for Markovian jump systems under a communication network. For the inaccessible states and uncertain parts of Markovian jump systems, a novel integral-type sliding mode output feedback controller combined with system states and dynamic controller states is proposed. An event-triggered mechanism is introduced to reduce network bandwidth and resources requirements. The augmented dynamic system and complete control framework are presented together. The reachability of the novel integral-type sliding mode is proved. Then, based on delay-dependent Lyapunov functions, free-weighting matrices, and a singular value decomposition approach, a less conservative sufficient condition is proposed to ensure exponential stability with a weighted <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathcal {L}_{2}$ </tex-math></inline-formula> - <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathcal{ L}_{\infty}$ </tex-math></inline-formula> disturbance performance. Finally, a numerical and a DC-DC switched boost converter circuit simulations that verify the feasibility and effectiveness of the proposed controller are presented.