Feedback Controller Design Method Research Articles

A Design of Gain-scheduled Congestion Controllers using State Predictive Observers

Abstract In this paper, a design problem of congestion controllers is discussed for TCP/AQM(Transmission Control Protocol/Active Queue Management) networks. The proposed method consists of two control techniques. First one is based on a gain-scheduling technique considering nonlinearities of TCP/AQM networks. But the designed congestion controller is a state feedback controller and it is impossible to embed the congestion controller in real computer networks. To avoid this problem, second one is based on a design technique of state predictive observer for linear time-delay systems. Thus it can be possible to embed the congestion controller in real networks by combining these methods. Firstly dynamical models of TCP/AQM are described as linear systems with self-scheduling parameters, which also depend on information delay. Here it is distinguishing to focus on constraints on the maximum queue length and TCP window-size, which are the network resources in TCP/AQM networks. And a design method of memoryless state feedback controllers is shown for linear system with a self-scheduling parameter and an information delay. But the designed gain- scheduled congestion controller is a state feedback controller and it is impossible to apply this controller to computer networks directly. Thus observers are also designed and the observer-based congestion controllers are derived.

A simple state feedback controller design method of networked control systems with time delay and packet dropout

This paper presents a simple yet effective method to design state feedback controller for networked control systems (NCSs). By introducing the lifting technique into NCSs and by considering the balance between effectiveness and simplicity, a novel discrete-time switch model is proposed with the consideration of time delay and packet dropout during the transmission of packets. In terms of the given model, we give sufficient conditions for the existence of state feedback controller such that the closed-loop NCSs are asymptotically stable. Based on the obtained stability conditions, a homotopy-based iterative LMI algorithm is developed to get the state feedback gain. Simulation and experimental results are given to demonstrate the effectiveness of the proposed approaches.

Output Feedback Strict Passivity of Discrete-time Nonlinear Systems and Adaptive Control System Design

In this paper, a necessary and sufficient condition for a discrete-time nonlinear system to be strictly passive is derived and OFSP (Output Feedback Strictly Passive) conditions will be established. Based on the obtained OFSP conditions, an adaptive output feedback controller design method which can solve causality problems will be proposed for a discrete-time nonlinear system.

Improved stabilisation method for networked control systems

The controller design problem for networked control systems (NCSs) is investigated. By considering the relationship between the network-reduced delay and its upper bound, an improved stability criterion for networked closed-loop system is proposed without ignoring any terms in the derivative of Lyapunov–Krasovskii function. As a result, a state feedback controller design method is established using a modified cone complementary linearisation (CCL) algorithm with a new stopping condition. A numerical example is given to demonstrate the effectiveness and the benefits of the proposed method.

Delay-dependent robust [formula omitted] control for uncertain discrete-time singular systems with time-delays

The robust memoryless state feedback H ∞ control problem for uncertain time-delay discrete-time singular systems is discussed. Under a series of equivalent transformation, the equivalence of this problem and the robust state feedback H ∞ control problem for standard state-space uncertain time-delay discrete-time systems is presented. In terms of matrix inequality, the delay-dependent sufficient condition for the solution of this problem is given, the design method of the memoryless state feedback controller and the controller are also given.

Globally stabilizing feedback control of process systems in generalized Lotka–Volterra form

In the present paper a globally stabilizing feedback controller design method is proposed for process systems when the feedback structure is also assumed to be in a quasi-polynomial form. It is shown that such feedback structure can always be achieved for process systems. By exploiting the special structure of the controller design problem, the existent iterative linear matrix inequality (ILMI) algorithm of [Y.-Y. Cao, J. Lam, Y.-X. Sun, Static output feedback stabilization: an ILMI approach, Automatica 12 (1998) 1641–1645] is applied to solve the BMI feasibility problem underlying the design. In addition, some partial results on placing the globally stable equilibrium point with respect to the positive orthant have also been proposed that is only possible in a fully actuated situation when the input variables are the intensive variables at the inlet. Furthermore, some preliminary results in selecting the structure of the QP-type feedback have also been presented.

A full delayed feedback controller design method for time-delay chaotic systems

A full delayed feedback controller (FDFC) design method is proposed to stabilize unstable fixed points (UFPs) for a class of continuous time-delay chaotic systems. Unlike the existing methods where the controller delay is usually determined by trial-and-error, it is shown in FDFC that both the upper bound of the controller delay and the controller gain can be obtained computationally. The simulation result demonstrates the effectiveness of the proposed FDFC design method.

Decentralized adaptive output feedback control via input/output inversion

A decentralized adaptive output feedback control design method is presented for control of large-scale interconnected systems. It is assumed that all the controllers share prior information about the subsystem reference models. Based on that information, a linear dynamic output feedback compensator and linearly parameterized neural network (NN) are introduced for each subsystem to partially cancel the effect of the interconnections on the tracking performance. Boundedness of error signals is shown through Lyapunov's direct method.

Synthesis Method for the Modelling and Robust Control of Coating Weight at Galvanizing Process

In this paper, we propose a new practical synthesis model for coating weight control and robust design method of feedback controller in galvanizing process. Firstly, we propose a new model, which combines both long term and short term model. Long term model has a good accuracy to predict the next distance and pressure of air knife for wide range of target coating weight, because it has the functions of classification, averaging and learning based on real measured data. Short term model has variational form based on linear change of inputs and outputs and is used at all controls except preset control. Based on this model, we propose a set of practical controller and a robust design method of feedback controller so that it can attenuate quickly the errors caused by time-delay and modelling error. The proposed model with controller were applied to continuous galvanizing line (CGL) at Kwang Yang Steel Works and we obtained good experimental results on the deviation control of coating weight at top of coil and uniform coating weight on the surface of strip.

A Feedback Enlargement of Stability Radius Using Non-differentiable Optimization

In controller design of dynamical systems, it is desirable that the controllers can guarantee the stability for not only nominal plants but also perturbed ones, because the plant models may have some uncertainties in their parameters. By this motivation, several researches for the robust controller design have been conducted. In this paper, a feedback controller design method is considered, which achieves enlarging the degree of robust stability for the linear SISO closed-loop systems. Choosing stability radius for the plant parameters as the degree of robust stability, and regarding this as an object function, we formulated this maximization as an optimization problem with constraints coming from prescribed pole placement. The difficulty of this formulation is that while pole placements give linear constraints, the object function is not a smooth one, which calls for an optimization technique for non-differentiable functions. To cope with this, we successfully used the bundle method. We show some numerical examples to illustrate our proposed design method.

Convex controller design applied to AC induction motor to satisfy multiple simultaneous specifications

The application of a closed-loop specification oriented feedback control design method, which addresses the design of controllers to satisfy multiple simultaneous conflicting closed-loop performance specifications is presented. The proposed approach is well suited to the design of controllers which must meet a set of conflicting performance specifications. Gain tuning is central to the design process, however, the tuning process is greatly simplified over that presented by the problem of tuning a PID controller for example. The proposed control method is applied to an AC induction motor, with an inner-loop flux vector controller applied to design a position control system. Experimental results verify the effectiveness of this method.

A stabilization method of chaotic systems based on full delayed feedback controller design

A full delayed feedback controller (FDFC) design method is proposed to stabilize the unstable fixed points (UFPs) for continuous chaotic systems. It is shown that the two parameters of a FDFC, i.e., the controller gain and the upper bound of controller time delay, can be simultaneously obtained by solving some linear matrix inequalities. Two examples are presented to show the effectiveness of proposed method.

Stabilization of switched linear systems with time-delay in detection of switching signal

A feedback stabilization problem for switched linear systems with time-delay in detection of switching signal is formulated. First, online state feedback controller design method for asymptotic stability and exponential stability is given. Then, offline state feedback controller design method for asymptotic stability and exponential stability is given as well.

CHAOTIFICATION OF DISCRETE-TIME DYNAMICAL SYSTEMS: AN EXTENSION OF THE CHEN–LAI ALGORITHM

In this article, we propose and study an extension of the Chen–Lai algorithm for chaotification of discrete-time dynamical systems. The proposed method is a simple but mathematically rigorous feedback control design method that can gradually make all the Lyapunov exponents of the controlled system strictly positive for any given n-dimensional dynamical system that has a uniformly bounded Jacobian but otherwise could be originally nonchaotic or even asymptotically stable.

Regional pole assignment for uncertain delta-operator systems

The pole assignment in a specified disk by state feedback for uncertain delta-operator systems is studied. By making use of algebra Riccati equations, a sufficient and necessary condition of pole assignment for a kind of parameter uncertain delta-operator system in a specified disk by state feedback is presented. And the design method of state feedback controller is also developed. The proposed method can unify some previous related results of continuous and discrete time systems into the delta framework. The efficiency of the design method is illustrated by a numerical example.

Controlling chaotic Chua's circuit based on piecewise quadratic Lyapunov functions method

Abstract In this paper, we present a linear feedback controller design method for controlling chaotic Chua's circuit based on piecewise quadratic Lyapunov functions. Firstly, we get the piecewise linear differential inclusions (pwLDIs) model of tracking error dynamics, then we design a linear state feedback controller to stabilize it based on the piecewise quadratic Laypunov functions. Finally, we give some numerical simulations to demonstrate the effectiveness of our theoretical results.

Interval Criterion of Robust Stability for Nonlinear System and Its Application to Flight Control

Robust stability for a series of nonlinear systems is presented in this paper. Through different region descriptions, the problem of stability for a complex nonlinear system is transformed into ones of the robust stabilities of several linear time-invariant systems. To get useful robust stability conditions, an expression for interval system is given, and the relationship between the internal stability and low- or supper-bound stability of interval systems is discussal. Thus, the polynomial matrix inequality for the determination of system robust stability is developed. Based on the equivalency transformation of the inequality, the solvable condition of the inequality is obtained. By means of the condition, robust stability theorem for interval systems is presented and a new design method of feedback control for nonlinear system is achieved. Applications to flight controller design show that the new method is efficient for uncertain system design.

A Design Method for 2-Degree-of-Freedom Repetitive Control Systems

In the present paper, we examine, a design method for 2-degree-of-freedom repetitive control systems. The 2-degree-of-freedom control has good characteristics, such as the input-output characteristics for the reference input and feedback control characteristics can be independently settled. 2-degree-of-freedom controllers consist of the feed-forward controller and the feedback controller. Design method of feedback controller for the repetitive control systems has been considered sufficiently, but design of feed-forward controllers for the repetitive control system has not been considered yet. In order to design feed-forward controller for the repetitive control system, we must solve the interpolation problem. In addition, the interpolation problem for feed-forward controller for the repetitive control system has many interpolation points. No method has been proposed to solve the interpolation problem for feed-forward controller for the repetitive control system. The purpose of this paper is to give a design method for feed-forward controllers and to propose a design method of 2-degree-of-freedom repetitive control systems.

Nonlinear Feedback Control of a Coupled Kinetic Monte Carlo-Finite Difference Code

Abstract Product quality variables for many electronics and materials processes are set at the nanoscale and smaller length scales. Although the control of these processes is of scientific and industrial interest, there is a shortage of feedback controller design methods based on the noncontinuum models that describe such nanoscopic phenomena. In this study, linear, gain-scheduled, and nonlinear feedback controllers are designed for a coupled kinetic Monte Carlo-finite difference code that simulates the manufacture of copper interconnects. The feedback controller designs incorporate a low order stochastic model constructed from the coupled continuum-noncontinuum code

Linear matrix inequality based model predictive controller

A model predictive controller based on linear matrix inequalities (LMIs) is presented. As in standard model predictive control (MPC) algorithms, at each (sampling) time, a convex optimisation problem is solved to compute the control law. The optimisation involves constraints written as LMIs, including those normally associated with MPC problems, such as input and output limits. Even though a state-space representation is used, only the measurable output and the extreme values of the unmeasurable states are used to determine the controller, hence, it is an output feedback control design method. Stability of the closed-loop system is demonstrated. Based on this MPC, a Lyapunov matrix is built and the controller computation is set in a more standard MPC framework. The design techniques are illustrated with numerical examples.