Dynamic Output Feedback Controller Research Articles

Distributed robust group output synchronization control for heterogeneous uncertain linear multi-agent systems

This paper investigates the distributed robust group output synchronization problem of heterogeneous uncertain linear leader-follower multi-agent systems (MASs), whose followers have nonidentical and parameter uncertain dynamics. To achieve cooperative tracking with multiple targets, a new group synchronization framework based upon the output regulation technique is established. In the underlying directed communication topology, all nonidentical followers are divided into several subgroups. Meanwhile, each subgroup has its output tracking objective generated by an autonomous exosystem which is seen as the leader of each subgroup. Since not all followers can access their exosystems directly, the distributed exosystem observer based on the algebraic Riccati inequality (ARI) is designed to obtain the information of exosystems. Moreover, to compensate for parameter uncertainties for different group topologies, the p-copy internal model is synthesized into distributed control laws, i.e., dynamic state feedback control protocol under an acyclic directed graph and dynamic output feedback control protocol under a general directed graph. It is shown that group synchronization can be respectively achieved with these controllers under acyclic and general partitions regardless of parameter uncertainties. Finally, some examples are provided to verify the validity of the analytic results.

Finite frequency domain H ∞ consensus control of neutral multi-agent systems with input delay

The finite frequency domain consensus control problem of neutral multi-agent systems with the input delay is investigated in this paper for the first time. According to the linear transformation, the problem of consensus is converted into a set of stability problems. Through the Lyapunov theory, combined with the time-delay interval decomposition method, a less conservative controller design method for the state feedback controller is presented. And the obtained controller can ensure closed-loop multi-agent systems to fulfil the consensus. Utilizing the generalised Kalman-Yakubovich-Popov (GKYP) lemma, the sufficient condition is derived for multi-agent systems achieving the performance in the finite frequency domain (FFD). Then, via the orthogonal spatial information of the input matrix, the conservativeness of obtained design approach is further declined. Moreover, the design method with less conservativeness is proposed for the dynamic output feedback controller. Finally, a numerical case and a multi-pendulum system controlled by the multi-motor system are presented in this paper to demonstrate the availability and applicability of the proposed methods.

Stabilization for a Class of Fractional-order Reaction Diffusion Systems by Dynamic Non-collocated Robust Piecewise Output Feedback Control

Stabilization for a Class of Fractional-order Reaction Diffusion Systems by Dynamic Non-collocated Robust Piecewise Output Feedback Control

An event-triggered round-robin protocol to dynamic output feedback control for nonhomogeneous Markov switching systems

This paper addresses the dynamic output feedback control issue for nonhomogeneous Markov switching systems with an event-triggered round-robin protocol. The transition probability matrix of the nonhomogeneous Markov process is time-varying, which can be characterized by a polytopic structure. To alleviate the communication burden in a shared network, as a first effort, a novel dynamic event-triggered round-robin protocol is forwarded to regulate whether to release the measurements and which ones to release. In light of the dynamic event-triggered round-robin protocol, an asynchronous dynamic output feedback control law is constructed, which reflects the mismatching phenomenon of modes switching between the nonhomogeneous Markov switching systems and the desired controllers. By resorting to a novel Lyapunov functional, sufficient conditions are attained to guarantee the stochastic stability of the augmented dynamic. At last, two examples are addressed to verify the effectiveness and applicability of the theoretic results.

H ∞ Load Frequency Control for Power Systems Under Communication Delays: An Event-Triggered Dynamic Output Feedback Scheme

In this brief, the problem of the load frequency control for power systems suffered from communication delays is discussed based on a dynamic output feedback scheme. An output-based event detection mechanism, where the error signal is defined as the difference between the latest transmitted data and the average value of the currently sampled data and the latest transmitted data, is introduced to reduce the triggering rate while ensuring the control performance. Combining such an event-triggered control scheme with dynamic output feedback control strategy, the concerned closed-loop system is established. After that, with the aid of Lyapunov-Krasovskii functional and appropriate matrix decoupling technique, some sufficient criteria for the performance analysis and controller design are deduced. Finally, the availability of the developed control strategy is verified through a simulation example with two cases.

An improved output feedback controller design for linear discrete‐time systems using a matrix decomposition method

SummaryThis paper presents the design of output feedback controllers for discrete‐time (DT) linear systems. New sufficient LMI conditions are derived for designing static and controllers using decomposition of an auxiliary matrix. The decomposition facilitates linearization of nonlinear term of reduced size to obtain linear matrix inequality criteria. This leads to less conservative results as shown in the numerical examples. In addition, the proposed static output feedback criteria is also used for designing dynamic output feedback controllers for DT systems. Furthermore, a comparative study is also made for the proposed design method with the results existing in the literature. Finally, a DT static output feedback controller is designed for a quarter‐car suspension system. Simulation results are provided to show the efficacy of the proposed design method.

Adaptive dynamic surface output feedback control for a class of quadrotor aircraft with actuator faults

PurposeThe purpose of this study is to propose an adaptive fault-tolerant control approach based on output feedback for a class of quadrotor unmanned aerial vehicles system. In the event of a controlled actuator failure, a stable flying of the aircraft can be achieved by selecting an appropriate sliding mode surface.Design/methodology/approachAiming at the actuator failure of quadrotor aircraft during flight in the controllable range, a dynamic surface sliding mode passive fault-tolerant controller based on output feedback is designed based on the strong robustness of sliding mode method. Due to the unknown nonlinearity dynamics and parameter uncertainties in the system, a nonlinear observer is used to estimate them online.FindingsThe stability of the suggested algorithm is established using appropriate Lyapunov functions, and the performance of the proposed control approach is demonstrated using hardware-in-the-loop simulation.Originality/valueAn error performance function is introduced into the controller to ensure the convergence speed and accuracy of errors are within the predetermined range. By using the norm estimation method, there is only one parameter that needs to be updated in each step of the control process, which considerably minimizes the calculation burden. Finally, the validity of the proposed control scheme is verified on the hardware-in-the-loop simulation, and the results show that the proposed control method has achieved the desired results.

Design of output feedback proportional–integral controller for polynomial fuzzy systems

AbstractIn this paper, the design of dynamic output feedback control law for polynomial fuzzy systems is studied. The main purpose is to design a tracker control law for fuzzy polynomial systems that are subject to external bounded disturbances. The structure of the control law is considered as fuzzy proportional–integral control. The conditions for deriving the control law are formulated in the form of a sum of square (SOS) feasibility problem. The designed control law will be able to force the system state vector to follow the state vector of a stable reference model in addition to guaranteeing the performance measure. The simulation results show the efficiency of the proposed method exposed to external disturbance.

Polynomial Dynamic Output-feedback Controllers for Positive Polynomial Fuzzy Systems with Time Delay

Polynomial Dynamic Output-feedback Controllers for Positive Polynomial Fuzzy Systems with Time Delay

Dynamic-output-feedback based interval type-2 fuzzy control for nonlinear active suspension systems with actuator saturation and delay

This paper proposes a fuzzy dynamic output feedback (DOF) controller for uncertain nonlinear active suspension systems (ASSs) with actuator saturation and time-varying delay. Firstly, given the time-delay and nonlinear characteristics of the suspension systems, an interval type-2 (IT-2) Takagi-Sugeno (T-S) fuzzy model is introduced to characterize the uncertain nonlinear ASSs with actuator saturation. Secondly, with the Lyapunov-Krasovskii function and the reciprocally convex technique, a series of sufficient delay-dependent conditions are derived to make sure that the control system with optimized H∞ performance and mechanical constraints is asymptotically stable. Thirdly, a DOF controller is designed to estimate the unmeasurable parameters of the system. Finally, the performance evaluation of the proposed controller is conducted through numerical and experimental tests.

A Characterization of approximate decentralized fixed modes of time‐delay systems

AbstractThe concept of decentralized fixed mode (DFM) is crucial in determining the output feedback stabilizability by linear time‐invariant (LTI) decentralized controllers. However, in some cases, although a system has no DFMs, some of its modes may be very close to being fixed. It is thus important to characterize these modes, which are called approximate DFMs (ADFMs). In this paper, the characterization of ADFMs is discussed for LTI neutral (possibly descriptor‐type) time‐delay systems under static and dynamic decentralized output feedback control laws, and a mode mobility measure is proposed to provide quantitative information about ADFMs. To analytically compare the proposed measure, some of the commonly used quantitative measures for the characterization of ADFMs of finite‐dimensional systems have also been extended to the considered type of systems. The herein proposed approach allows multiple time delays and does not require additional expansions or preliminaries for multi‐input multi‐output systems, like some other commonly used methods. Thus, characterization with this measure, in general, requires less computational load, while it can provide more explicit information about the controller effort than the other considered measures.

On designing the hybrid-triggered dynamic output feedback guaranteed cost control for uncertain T-S fuzzy networked control systems with cyber attack and actuator saturation

In this paper, we study the hybrid-triggered dynamic output feedback-based guaranteed cost control issue for uncertain Takagi-Sugeno (T-S) fuzzy networked control systems (NCSs) with cyber attack and actuator saturation. The hybrid-triggered mechanism comprising of time-triggered mechanism (TTM) and event-triggered mechanism (ETM) is provided to adjust the trigger strategy due to the variety in network resource utilization. Both the switching between two trigger mechanisms and the cyber attack phenomenon in communication network are respectively represented by two Bernoulli distributions. The data quantization is characterized by the sector bound technique and actuator saturation is addressed by invoking an auxiliary matrix. The stability of closed-loop NCSs with bounded disturbance and cyber attack is expressed by the methodology of quadratic boundedness (QB). The existence criteria and design strategies for minimizing the upper bound of performance in view of dynamic output feedback controller are constructed for any admissible uncertainties. Subsequently, in the light of the cone complementarity linearization (CCL) algorithm, the controller design issue is cast into the convex optimization issue which is capable of solving by the technique about linear matrix inequalities (LMIs). Finally, simulation example is employed to demonstrate the validity of designed controller.

Stability analysis and robust controller design for systems with mixed time-delays and stochastic nonlinearity via cone complementarity linearization

The stochastic Takagi-Sugeno (T-S) fuzzy discrete dynamic output feedback control is investigated for a class of stochastic T-S fuzzy discrete networked control systems. Firstly, the T-S fuzzy model and stochastic Bernoulli theory are employed to approximate the discrete system plant. Secondly, the T-S fuzzy model and stochastic Bernoulli theory are employed to design the stochastic T-S fuzzy discrete dynamic output feedback controller. Thirdly, the stochastic Bernoulli theory is employed to describe the characteristics of random occurrence for multipath packet dropouts. The delay-dependent discrete Lyapunov functional and Schur complement are employed, the closed-loop system is stochastically finite-time bounded stable subject to (c1,c2,ω¯,N,R). The Schur complement and congruence transformation matrix are introduced to determine controller gain matrices. The cone complementarity linearization is applied to convert controller design into nonlinear minimization constraints for solving the nonconvex problem caused by fuzzy-basis-dependent LMIs. Simulations are given to show the effectiveness of proposed methods.

Designing an Optimal Reset Controller for TS Fuzzy Systems

This study considers the problem of designing a reset dynamic output feedback controller (R-DOFC) for continuous-time nonlinear dynamics modeled by a Takagi-Sugeno (TS) fuzzy form. The exponential convergence of the closed-loop system state trajectories to the equilibrium point is satisfied by designing the fuzzy dynamic output feedback controller (DOFC) without reset action via the linear matrix inequality (LMI) technique. After that, by developing an optimization problem, the after-reset value is designed by using system output measurements at each reset time. In this approach, a genetic algorithm is adopted to minimize the proposed cost function of certain transient performances to achieve the best reset time instants. Moreover, sufficient conditions for choosing the DOFC after-reset value are formulated in the form of LMIs. The proposed reset fuzzy DOFC is applied to two nonlinear systems. The merits of the proposed reset DOFC are demonstrated by comparing the obtained results with those of other approaches.

ℓ₂-ℓ∞ Control of Discrete-Time State-Delay Interval Type-2 Fuzzy Systems via Dynamic Output Feedback.

This article investigates the design of the l2-l∞ dynamic output-feedback (DOF) controller for interval type-2 (IT2) T-S fuzzy systems with state delay. For nonlinear systems, the IT2 fuzzy model is an efficient modeling method which can better express uncertainties than the (type-1) fuzzy model. In addition, state delay is also a general factor that affects system performance. After analyzing the stability of the system, based on convex linearization and the projection theorem, this article proposes a delay-dependent output-feedback controller design method. The IT2 membership functions (MFs) of the fuzzy controller are chosen to be different from those of the model so as to increase the freedom of controller selection. A membership-function-dependent (MFD) method based on the staircase MFs is applied to relax the stability analysis results. Finally, a numerical simulation example is given to illustrate the effectiveness of the results.

Quantized Fault-Tolerant Control for Descriptor Systems with Intermittent Actuator Faults, Randomly Occurring Sensor Non-Linearity, and Missing Data

This paper examines the fault-tolerant control problem for discrete-time descriptor systems that are susceptible to intermittent actuator failures, nonlinear sensor data, and probability-based missing data. The discrete-time non-homogeneous Markov chain was adopted to describe the stochastic behavior of actuator faults. Moreover, Bernoulli-distributed stochastic variables with known conditional probabilities were employed to describe the practical features of random sensor non-linearity and missing data. In this study, the output signals were quantized and a dynamic output feedback controller was synthesized such that the closed-loop system was stochastically admissible and satisfied the strictly (Q,S,R)-γ-dissipative performance index. The theoretical developments are illustrated through numerical simulations of an infinite machine bus.

Fuzzy dynamic output feedback control for nonlinear networked multirate sampled-data systems: An integral inequality method

This paper is devoted to fuzzy dynamic output feedback control for nonlinear networked multirate sampled-data systems based on T-S fuzzy systems. Using asynchronous multirate sampled-data, a multirate fuzzy controller is designed. The resultant closed-loop system is modeled as a perturbed system with two perturbed terms which include multirate sampling and the asynchronous membership functions between the controlled plant and the controller. A novel refined integral inequality is developed, and it improves Jensen's inequality and extends Wirtinger's inequalities by considering the sawtooth structure of time-varying delays. By applying the inequality to the perturbed system and constructing a new storage function, a stability criterion and two fuzzy dynamic output feedback controller design methods are presented for the nonlinear networked multirate sampled-data systems. Finally, three illustrative examples show the effectiveness of the proposed method.

Robust H∞$H_\infty$ dynamic output feedback control of the DC–AC converter with a neutral leg

This paper investigates the problem of robust H ∞ $H_\infty$ dynamic output feedback control of 3-phase 4-wire converter with neutral bridge arm in the application of smart grid and distributed generation. Based on Lyapunov functions, a novel sufficient Linear Matrix Inequality condition analysis was performed on the dynamic output feedback stabilisation controllers. Meanwhile, some auxiliary slack variables with special structure and well-established performance conditions are employed to reduce design conservatism. This topology along with the H ∞ $H_\infty$ controller can solve the DC link balancing problem and maintain the deviation between the neutral point and the midpoint of DC supply very small. The achievable performance is analysed quantitatively and the controller design method was conducted and verified both in MATLAB simulation and the real-time simulation platform built by StarSim and MT, respectively.

Gain-scheduled output-feedback control of uncertain input-delay LPV systems with saturation via polytopic differential inclusion

This paper examines the control design for parameter-dependent input-delay linear parameter-varying (LPV) systems with saturation constraints. A linear differential inclusion approach is implemented to formulate the saturation nonlinearity. Subsequently, a gain-scheduled dynamic output-feedback controller is structured to conform to the saturation representation. By means of a Lyapunov–Krasovskii functional, sufficient delay-dependent conditions are derived for the analysis and feedback control synthesis of the closed-loop system in the presence of uncertainties and exogenous disturbances. Disturbance rejection objectives following an induced -norm and an norm formulation are examined. Estimation of the domain of attraction with the parametrisation of the admissible LPV controllers is presented. Three different optimisation objectives with respect to disturbance rejection, disturbance tolerance, and domain of attraction expansion are formulated. The proposed design methodology is examined in the context of the air-fuel ratio (AFR) regulation in a spark ignition (SI) engine with a speed-dependent delay and model parameters in the presence of canister purge disturbances and AFR dynamics uncertainty. The injector is restricted in the amount of fuel it can deliver to the cylinder. The three-way catalytic converter's performance in terms of oxygen storage and emission reduction is taken into consideration. Closed-loop simulation results are provided to validate the methodology.

Co-design of output-based security control and dynamic event-triggered mechanism for NCSs under hybrid cyber attacks

This paper investigates output-based dynamic event-triggered control for networked control systems (NCSs), in which hybrid cyber attacks randomly occur in communication network. First, a gain adjustable dynamic output feedback (DOF) controller is designed for NCSs and relaxes state-available constraint in presence of three types of attacks, including stochastic deception attacks, replay attacks and aperiodic denial-of-service (DoS) attacks. Second, a output-based dynamic event-triggered mechanism (DETM) is designed to optimize limited network resources under the cyber attacks. Third, a new switched system is established to describe the effect of hybrid cyber attacks, the DOF controller and the DETM simultaneously. Then, criteria for guaranteeing asymptotically stability of the switched system are obtained. Furthermore, the co-design method of DETM and DOF controller is provided to maintain the NCSs stability. Finally, an example is presented to show the effectiveness of the proposed methods in this paper.