Design of decentralized robust H∞ state feedback controller

The design of decentralized robust H∞ state feedback controller for large-scale interconnected systems with value bounded uncertainties existing in the state, control input and interconnected matrices was investigated. Based on the bounded real lemma a sufficient condition for the existence of a decentralized robust H∞ state feedback controller was derived. This condition is expressed as the feasibility problem of a certain nonlinear matrix inequality. The controller, which makes the closed-loop large-scale system robust stable and satisfies the given H∞ performance, is obtained by the offered homotopy iterative linear matrix inequality method. A numerical example is given to demonstrate the effectiveness of the proposed method.     

H2 Output Feedback Control for Airborne Dispenser Uncertain Generalized System

The problem of H2 output feedback control for generalized system with structural uncertainties is studied using linear matrix inequality approach. A sufficient condition Of linear matrix inequality is presented such that the closed-loop system is stable and satisfies H2 performance for all admissible uncertainties. Furthermore, the solution of the controller is given. An H2 output feedback controller is designed in the airborne dispenser pitch channel, and the simulation results show that the controller is effective.     

Non-fragile delay-dependent H ∞ control of linear time-delay system with uncertainties in state and control input

The problem of designing a non-fragile delay-dependent H∞ state-feedback controller was investigated for a linear time-delay system with uncertainties in state and control input. First, a recently derived integral inequality method and Lyapunov-Krasovskii stability theory were used to derive new delay-dependent bounded real lemmas for a non-fragile state-feedback controller containing additive or multiplicative uncertainties. They ensure that the closed-loop system is internally stable and has a given H∞ disturbance attenuation level. Then, methods of designing a non-fragile H∞ state feedback controller were presented. No parameters need to be tuned and can be easily determined by solving linear matrix inequalities. Finally, the validity of the proposed methods was demonstrated by a numerical example with the asymptotically stable curves of system state and controller output under the initial condition of x（0）=[1 0 -1]^T and h=0.8 time-delay boundary.     

Delay-dependent static output feedback control of nonlinear system

The static output feedback control problem for time-delay nonlinear system is studied based on T-S fuzzy bilinear model. The objective is to design a delay-dependent static output feedback controller via the parallel distributed compensation (PDC) approach such that the closed-loop system is delay-dependent asymptotically stable. A sufficient condition for the existence of such a controller is derived via the linear matrix inequality (LMI) approach and the design problem of the fuzzy controller is formulated as an LMI problem. The simulation examples show the effectiveness of the proposed approach.     

Robust H∞ and H2 Static Output Feedback Control of Discrete-time Piecewise Affine Singular Systems with Norm-bounded Uncertainties

This paper is concerned with the problem of designing robust H∞and H2static output feedback controllers for a class of discrete-time piecewise-affine singular systems with norm-bounded time-varying parameters uncertainties. Based on a piecewise singular Lyapunov function combined with S-procedure,Projection lemma and some matrix inequality convexifying techniques,sufficient conditions in terms of linear matrix inequalities are given for the existence of an output-feedback controller for the discrete-time piecewiseaffine singular systems with a prescribed H∞disturbance attenuation level,and the H2norm is smaller than a given positive number. It is shown that the controller gains can be obtained by solving a family of LMIs parameterized by one or two scalar variables. The numerical examples are given to illustrate the effectiveness of the proposed design methods.     

Decentralized H∞ state feedback control for large-scaleinterconnected uncertain systems with multiple delays

Decentralized H∞ control was studied for a class of interconnected uncertain systems with multiple delays in the state and control and time varying but norm-bounded parametric uncertainties. A sufficient condition which makes the closed-loop system decentralized asymptotically stable with H∞ performance was derived based on Lyapunov stability theorem. This condition is expressed as the solvability problem of linear matrix inequalities. The method overcomes the limitations of the existing algebraic Riccati equation method. Finally, a numerical example was given to demonstrate the design procedure for the decentralized H∞ state feedback controller.     

Robust reliable H_∞ control for a class of uncertain time-delay systems

This paper deals with the problem of robust reliable H∞ control for a class of uncertain nonlinear systems with time-varying delays and actuator failures. The uncertainties in the system are norm-bounded and time-varying. Based on Lyapunov methods, a sufficient condition on quadratic stabilization independent of delay is obtained. With the help of LMIs (linear matrix inequalities) approaches, a linear state feedback controller is designed to quadratically stabilize the given systems with a H∞ performance constraint of disturbance attenuation for all admissible uncertainties and all actuator failures occurred within the prespecified subset. A numerical example is given to demonstrate the effect of the proposed design approach.     

Stabilization of Fractional Order Hyperchaotic Systems with Uncertainties via Output Feedback Sliding Mode Control

An output feedback sliding mode controller is designed for the stabilization of fractional order hyperchaotic systems including uncertainties in the state matrix and the output matrix. On the basis of auxiliary system,a sliding mode control law with output feedback characteristics is researched by studying the structure decomposition of fractional order hyperchaotic systems. Based on fractional order Lyapunov stability theorem,a switching surface is designed by using linear matrix inequality( LMI) method. Using a simple adaptation,an improved sliding mode controller is given to guarantee the existence of the sliding mode. Moreover,numerical simulations are performed to confirm the effectiveness and feasibility of the stabilization control scheme.     

Delay-independent decentralized H ∞ control for multi-channel discrete-time systems with uncertainties

A robust decentralized H∞ control problem was considered for uncertain multi-channel discrete-time systems with time-delay. The uncertainties were assumed to be time-invariant, norm-bounded, and exist in the system, the time-delay and the output matrices. Dynamic output feedback was focused on. A sufficient condition for the multi-channel uncertain discrete time-delay system to be robustly stabilizable with a specified disturbance attenuation level was derived based on the theorem of Lyapunov stability theory. By setting the Lyapunov matrix as block diagonal appropriately according to the desired order of the controller, the problem was reduced to a linear matrix inequality （LMI） which is sufficient to existence condition but much more tractable. An example was given to show the efficiency of this method.     

Fuzzy gain-scheduling output feedback controller design for saturated linear plants

In this paper, the control design problem for linear systems subject to actuator saturations is considered. A fuzzy gain-scheduling output feedback controller is proposed to guarantee the stability of the closed-loop system as well as providing disturbance/error attenuation measured in L2 norm. The synthesis condition is cast as a convex optimization problem in terms of linear matrix inequalities (LMIs) and can be solved efficiently. The ball-beam system is used to demonstrate the proposed saturation control approach.     

H infinity Control for Sandwiched Maglev Stage with Dynamic Damping

An H infinity (H∞) controller for a sandwiched maglev positioning stage is proposed. The maglev positioning stage has a special structure:a sandwiched maglev stage, consisting of repulsive linear motors and attractive linear motors, which have better levitation performance. Forces on the sandwiched maglev stage are analyzed and modeled. The positioning controller is designed based on the feedback linearized model with a dynamic damping system. The design of the H infinity controller for stage positioning is derived as a series of linear matrix inequalities (LMIs) which are efficiently solved in Matlab. The proposed controller and its effectiveness is demonstrated compared to PID method.     

Improved H_∞ control for networked control systems with network-induced delay and packet dropout

The H_∞ performance analysis and controller design for linear networked control systems(NCSs) are presented.The NCSs are considered a linear continuous system with time-varying interval input delay by assuming that the sensor is time-driven and the logic Zero-order-holder(ZOH) and controller are event-driven.Based on this model,the delay interval is divided into two equal subintervals for H_∞ performance analysis.An improved H_∞ stabilization condition is obtained in linear matrix inequalities(LMIs) framework by adequately considering the information about the bounds of the input delay to construct novel Lyapunov–Krasovskii functionals(LKFs).For the purpose of reducing the conservatism of the proposed results,the bounds of the LKFs differential cross terms are properly estimated without introducing any slack matrix variables.Moreover,the H_∞ controller is reasonably designed to guarantee the robust asymptotic stability for the linear NCSs with an H_∞ performance level γ.Numerical simulation examples are included to validate the reduced conservatism and effectiveness of our proposed method.     

Output Feedback Controller Design for Discrete-time Switched Singular Systems

This paper is concerned with the problems of robust admissibility and static output feedback （SOF） stabilization for a class of discrete-time switched singular systems with norm-bounded parametric uncertainties.The objective is to design a suitable robust SOF controller guaranteeing the regularity,causality and asymptotic stability of the resulting closed-loop system under arbitrary switching laws.Based on the basic matrix inequality sufficient condition for checking the admissibility of switched singular systems,together with some matrix inequality convexifying techniques,the SOF controller synthesis is developed for the underlying systems.It is shown that the controller gains can be obtained by solving a set of strict linear matrix inequalities （LMIs）.A simulation example is given to show the effectiveness of the proposed method.     

Fuzzy robust path tracking strategy of an active pelagic trawl system with coordinated ship and winch regulation简

A fuzzy robust path tracking strategy of an active pelagic trawl system with ship and winch regulation is proposed. First, nonlinear mathematic model of the pelagic trawl system was derived using Lagrange equation and further simplified as a low order model for the convenience of controller design. Then, an active path tracking strategy of pelagic trawl system was investigated to improve the catching efficiency of the target fish near the sea bottom. By means of the active tracking control, the pelagic trawl net can be positioned dynamically to follow a specified trajectory via the coordinated winch and ship regulation. In addition, considering the system nonlinearities, modeling uncertainties and the unknown exogenous disturbance of the trawl system model, a nonlinear robust H2/H~ controller based on Takagi-Sugeno （T-S） fuzzy model was presented, and the simulation comparison with linear robust H2/H∞ controller and PID method was conducted for the validation of the nonlinear fuzzy robust controller. The nonlinear simulation results show that the average tracking error is 0.4 m for the fuzzy robust H2/H∞ control and 125.8 m for the vertical and horizontal displacement, respectively, which is much smaller than linear H2/H∞ controller and the PID controller. The investigation results illustrate that the fuzzy robust controller is effective for the active path tracking control of the pelagic trawl system.     

Industrial applications of advanced control techniques

This paper discusses two industrial control applications using advanced control techniques. They are the optimal-tuning nonlinear PID control of hydraulic systems and the neural predictive control of combustor acoustic of gas turbines. For hydraulic control systems, an optimal PID controller with inverse of dead zone is introduced to overcome the dead zone and is designed to satisfy desired time-domain performance requirements. Using the adaptive model, an optimal-tuning PID control scheme is proposed to provide optimal PID parameters even in the case where the system dynamics is time variant. For combustor acoustic control of gas turbines, a neural predictive control strategy is presented, which consists of three parts: an output model, output predictor and feedback controller. The output model of the combustor acoustic is established using neural networks to predict the output and overcome the time delay of the system, which is often very large, compared with the sampling period. The output-feedback c     

Robustness-tracking control based on sliding mode and H∞ theory for linear servo system

A robustness-tracking control scheme based on combining H∞ robust control and sliding mode control is proposed for a direct drive AC permanent-magnet linear motor servo system to solve the conflict between tracking and robustness of the linear servo system. The sliding mode tracking controller is designed to ensure the system has a fast tracking characteristic to the command, and the H∞ robustness controller suppresses the disturbances well within the close loop( including the load and the end effect force of linear motor etc. ) and effectively minimizes the chattering of sliding mode control which influences the steady state performance of the system. Simulation results show that this control scheme enhances the track-command-ability and the robustness of the linear servo system, and in addition, it has a strong robustness to parameter variations and resistance disturbances.     

Vibration control of flexible spacecraft actuated by piezoceramics via variable structure strategy

This paper presented a hybrid control scheme to vibration reduction of flexible spacecraft during rotational maneuver by using variable structure output feedback control (VSOFC) and piezoelectric materials. The control configuration included the attitude controller based on VSOFC method and vibration attenuator designed by constant-gain negative velocity feedback control. The attitude controller consisted of a linear feedback term and a discontinuous feedback term. With the presence of this attitude controller, an additional flexible control system acting on the flexible parts can be designed for vibration control. Compared with conventional proportional-derivative (PD) control, the developed control scheme guarantees not only the stability of the closed-loop system, but also yields better performance and robustness in the presence of parametric uncertainties and external disturbance. Simulation results are presented for the spacecraft model to show the effectiveness of the proposed control techniques.     

Robust Stabilization of Discrete time Constrained Singular Piecewise affine Systems with Norm bounded Uncertainties

In this paper,the problem of designing robust H-infinity output feedback controller and l2-gain controller are investigated for a class of discrete-time singular piecewise-affine systems with input saturation and state constraints. Based on a singular piecewise Lyapunov function combined with S-procedure and some matrix inequality convexifying techniques,the H-infinity stabilization condition is established and the l2-gain controller is investigated,and meanwhile,the input saturation disturbance tolerance condition is proposed. Under energy bounded disturbance,the domain of attraction is well estimated and the l2-gain controller is designed in some restricted region. It is shown that the controller gains can be obtained by solving a family of LMIs parameterized by one or two scalar variables. Meanwhile,by using the corresponding optimization methods,the domain of attraction and the disturbance tolerance level is maximized,and the H-infinity performance γ is minimized.Finally,numerical examples are given to illustrate the effectiveness of the proposed design methods.     

On a novel non-smooth output feedback controller for the attitude control of a small float satellite antenna

A novel non-smooth controller of the second order double integrator system with a bounded disturbance is proposed, which stability is proved and which disturbance rejection capability is analyzed by MATLAB simulation experiments. The novel non-smooth output feedback controller and tracking differentiator are applied to control the azimuth servo system of the small floating satellite antenna. The MATLAB simulation and hardware in the loop simulation experiments are conducted. The experiment results validate that the non-smooth output feedback controller with stronger surge and sudden disturbance rejection capability can realize the stable azimuth servo control of the small floating antenna to ensure the communication between the target satellite and the antenna with high quality.