Linear pole-placement anti-windup control for input saturation nonlinear system based on Takagi Sugeno fuzzy model

An anti-windup controller for multi-input nonlinear system is proposed in this paper. The proposed method does not need to calculate every time for every fuzzy rules comparing with traditional linear pole placement of T-S(Takagi-Sugeno) fuzzy. This means fewer LMIs(linear matrix inequality) will be needed and its solution will be guaranteed as much as possible. For different saturation limit, different D-stable disk center and radius of pole placement can be selected to eliminate input saturation effect directly. Nonlinear system will be transferred to T-S fuzzy model first. Then, by employing a series of transition matrix, nonlinear system will be transferred into a nearly linear format accompanied by a nonlinear part. Finally, by designing a proper controller, linear pole placement method can be used and the controller gains can be calculated out with LMIs.

     

Semiglobal stabilization of linear systems using constrained controls: a parametric optimization approach

A bounded feedback control for asymptotic stabilization of linear systems is derived. The designed control law increases the feedback gain as the controlled trajectory converges towards the origin. A sequence of invariant sets of decreasing size, associated with a (quadratic) Lyapunov function, are defined and related to each of them, the corresponding possible highest gain is chosen, while maintaining the input bounded. Gains as functions of the position are designed by explicitly solving a c-parameterized programming problem. The proposed method allows global asymptotic stabilization of open-loop stable systems, with inputs subject to magnitude bounds and globally bounded rates. In the general case of linear systems that are asymptotic null controllable with bounded input, the semiglobal stabilization is also addressed taking into account the problem of semiglobal rate-limited actuators. The method is illustrated with the global stabilization of an inertial navigator, and the stabilization of a nonlinear model of a crane with hanging load. Copyright © 1999 John Wiley & Sons, Ltd.     

Semiglobal synchronization of multiple generic linear agents with input saturation

This paper investigates the semiglobal synchronization problem for a group of agents with input saturation under directed interaction topology, where each agent is modeled as a generic linear system rather than the single‐integrator or double‐integrator dynamics. The main result is the construction of a feedback coupling gain that achieves semiglobal synchronization if all the agents have identically saturated linear dynamics, which can be of any order. It is shown that the coupling gain obtained via parametric Lyapunov equations can semiglobally synchronize any directed network provided that the interaction topology has a directed spanning tree. Furthermore, due to the use of parametric Lyapunov equations, a convergence rate is analytically obtained. Finally, a simulation example is provided to demonstrate the effectiveness and advantages of our theoretical findings. Copyright © 2013 John Wiley & Sons, Ltd.     

On the theory of state-covariance assignment for single-inputlinear discrete systems

An alternative method for state-covariance assignment for discrete single-input linear systems is proposed. This method is based on the inverse solution of the Lyapunov equation, and the resulting formulas are similar in structure to the formulas for pole placement. Further, the set of all covariance matrices assignable to a single-input discrete system is also characterized. The proposed method is illustrated by a numerical example     

Guaranteed Cost Anti-windup Stabilization of Discrete Delayed Cellular Neural Networks

This paper studies the problem of guaranteed cost anti-windup stabilization of discrete delayed cellular neural networks. Saturation degree function is initially presented and the convex hull theory is applied to handle the saturated terms of discrete delayed cellular neural networks. Accordingly, after choosing a common quadratic performance function, the paper designs a guaranteed cost stabilization controller in the absence of input saturation on the basis of Lyapunov–Krasovskii theorem and linear matrix inequality formulation. Then a static state feedback anti-windup compensation is derived, which guarantee a guaranteed cost and the estimation of the asymptotic stability region for the closed-loop system. Finally, numerical examples are presented to demonstrate the effectiveness of the proposed design technique.     

不确定离散切换系统具有极点约束的保性能控制

对一类含有范数有界不确定性的离散切换系统和一个二次型性能指标，研究其具有闭环极点约束的鲁棒状态反馈保性能控制问题．利用二次Lyapunov函数方法和线性矩阵不等式技术，给出了鲁棒保性能控制器存在的一个充分条件，在所构造切换规则下，闭环系统二次D稳定，且满足给定的性能指标．在此基础上，将次优保性能控制器设计问题转化为一组线性矩阵不等式约束下的凸优化问题．数值例子说明了所提方法的有效性．     

混沌系统不稳定平衡点的镇定及其在蔡氏电路中的应用

基于混沌系统的遍历性和状态PI调节器理论, 提出一类混沌系统不稳定平衡点的镇定和设定点跟踪新方法, 给出用于控制器参数设计的Lyapunov矩阵不等式. 对于分段线性混沌系统, 如蔡氏电路, 可通过控制理论中的极点配置技术来设计控制器参数. 该方法对系统参数变化具有很强的鲁棒性, 能够消除外部定值扰动. 将该方法用于蔡氏混沌电路不稳定平衡点的镇定, 取得了满意的结果.     

Robust Static Output Feedback H2/H∞ Control Synthesis with Pole Placement Constraints: An LMI Approach

This paper studies the robust static output feedback (SOF) problem considering pole placement constraints for linear systems with polytopic uncertainty as well as linear parameter varying (LPV) systems. New linear matrix inequality (LMI) approaches are proposed for the SOF controller design while the pole placement, H₂, and H_∞ constraints are guaranteed. In addition, the gain-scheduled SOF controller will be designed for LPV systems if system parameters are measured. The proposed methods can be applied to general linear systems without imposing any constraints on system matrices. The performance and effectiveness of the proposed methods are shown using two examples.

     

Adaptive Observer‐Based Global Sliding Mode Control for Uncertain Discrete‐Time Nonlinear Systems with Time‐Delays and Input Nonlinearity

A new discrete‐time adaptive global sliding mode control (SMC) scheme combined with a state observer is proposed for the robust stabilization of uncertain nonlinear systems with mismatched time delays and input nonlinearity. A state observer is developed to estimate the unmeasured system states. By using Lyapunov stability theorem and linear matrix inequality (LMI), the condition for the existence of quasi‐sliding mode is derived and the stability of the overall closed‐loop system is guaranteed. Finally, simulation results are presented to demonstrate the validity of the proposed scheme.     

Continuous pole placement for delay equations

In this paper, we describe a stabilization method for linear time-delay systems which extends the classical pole placement method for ordinary differential equations. Unlike methods based on finite spectrum assignment, our method does not render the closed loop system, finite dimensional but consists of controlling the rightmost eigenvalues. Because these are moved to the left half plane in a (quasi-)continuous way, we refer to our method as continuous pole placement. We explain the method by means of the stabilization of a linear finite dimensional system in the presence of an input delay and illustrate its applicability to more general stabilization problems.     

Distributed MPC of constrained linear systems with time-varying terminal sets

This paper proposes a decoupling strategy for the Distributed Model Predictive Control (DMPC) for a network of dynamically-coupled linear systems. Like most DMPC approaches, the proposed approach has a terminal set and uses a Lyapunov matrix for the terminal cost in the online optimization problem for each system. Unlike them, the terminal set changes at every time step and the Lyapunov matrix is not block-diagonal. These features result in a less conservative DMPC formulation. The proposed method is easy to implement when the network is strongly connected (or when a central collector is used). Otherwise, the computations of the terminal set require the online solutions of a series of linear programming problems but can be speeded up significantly by preprocessing. Numerical examples showing these results are provided.     

Input-to-state stability for discrete-time time-varying systems with applications to robust stabilization of systems in power form

Input-to-state stability (ISS) of a parameterized family of discrete-time time-varying nonlinear systems is investigated. A converse Lyapunov theorem for such systems is developed. We consider parameterized families of discrete-time systems and concentrate on a semiglobal practical type of stability that naturally arises when an approximate discrete-time model is used to design a controller for a sampled-data system. An application of our main result to time-varying periodic systems is presented, and this is used to solve a robust stabilization problem, namely to design a control law for systems in power form yielding semiglobal practical ISS (SP-ISS).     

Semiglobal practical stabilization of nonholonomic wheeled mobile robots with saturated inputs

In the practical design of nonholonomic control systems, saturated input is an important issue to consider. A number of stabilizing controllers for chained forms with bounded inputs have been proposed by different researchers. Under some conditions, nonholonomic wheeled mobile robots (NWMR) can be transformed into chained forms by state and input transformations. In this paper, we propose semiglobal practical stabilizing control schemes for a class of NWMR with saturated inputs. These schemes are given not based on chained forms, but based on a kind of new systems which are converted from NWMR by using state transformations without any input transformation. The advantage for doing this is involved in two points: first, the stabilizers proposed are semiglobal. Second, for the methods exploited here, the original system inputs (in the sense of kinematics) can be guaranteed to stay within the desired upper bounds. Finally, the simulation is given.     

An eigenvalue based approach for the stabilization of linear time-delay systems of neutral type

An eigenvalue based approach for the stabilization of linear neutral functional differential equations is presented, which extends the recently developed continuous pole placement method for delay equations of retarded type. The approach consists of two steps. First the stability of the associated difference equation is determined and a procedure is applied to compute the supremum of the real parts of its characteristic roots, which corresponds to computing the radius of the essential spectrum of the solution operator of the neutral equation. No restrictions are made on the dimension of the system and the number of delays. Also the effect of small delay perturbations is explicitly taken into account. As a result of this first step the stabilization problem of the neutral equation is reduced to a problem involving only a finite number of characteristic roots. As a second step, stabilization is achieved by shifting the rightmost or unstable characteristic roots to the left half plane in a quasi-continuous way, by applying small changes to the controller parameters, and meanwhile monitoring other characteristic roots with a large real part. A numerical example is presented.     

State Feedback Control for a Class of Fractional Order Nonlinear Systems

Using the Lyapunov function method, this paper investigates the design of state feedback stabilization controllers for fractional order nonlinear systems in triangular form, and presents a number of new results. First, some new properties of Caputo fractional derivative are presented, and a sufficient condition of asymptotical stability for fractional order nonlinear systems is obtained based on the new properties. Then, by introducing appropriate transformations of coordinates, the problem of controller design is converted into the problem of finding some parameters, which can be certainly obtained by solving the Lyapunov equation and relevant matrix inequalities. Finally, based on the Lyapunov function method, state feedback stabilization controllers making the closed-loop system asymptotically stable are explicitly constructed. A simulation example is given to demonstrate the effectiveness of the proposed design procedure.      

Backstepping control integrated with Lyapunov-based model predictive control

In this study, backstepping control integrated with Lyapunov-based model predictive control (BS-MPC) is proposed for nonlinear systems in a strict-feedback form. The virtual input of the first step is designed by solving the finite-horizon optimal control problem (FHOCP), and the real input is designed by the backstepping method. BS-MPC guarantees (semiglobal) ultimate boundedness of the closed-loop system when the control is implemented in a zero-order hold manner. When the robustness of BS-MPC is analyzed for uniformly bounded disturbances, the ultimate boundedness of the solution of perturbed system is guaranteed. BS-MPC can provide a better desired value of the virtual input of the first step by solving the FHOCP, resulting in a faster stabilization of the system compared with the backstepping control. In addition, BS-MPC requires less computational load compared with MPC because the dimension of the states considered in the on-line optimization problem of BS-MPC is lower than that of MPC.     

输入饱和系统的离散增益调度控制及其在在轨交会中的应用

基于参量Lyapunov方法和不变集理论,针对具有输入饱和非线性约束的线性系统,提出了一种离散增益调度控制方法. 通过逐渐 增大代表闭环系统收敛速率参数的值,所提出的离散增益调度控制方法逐步加快闭环系统的收敛速度,达到改善闭环系统 动态性能的目的. 如果开环系统是非指数不稳定的,则所提出的离散增益调度控制器可实现半全局镇定;反之可实现局部镇定,并均可保证闭环系统的指数稳定性. 最后,将 所提出的方法应用于空间合作目标在轨交会控制系统的控制器设计,并直接在原始非线 性系统模型上进行仿真,结果验证了所提方法的有效性.     

基于观测器的不确定广义时滞系统保成本控制

讨论了基于观测器的一类不确定广义时滞系统的保成本控制问题,给出了系统保成本控制器的设计方法.控制器的构造使得闭环系统是鲁棒稳定的.利用线性矩阵不等式以及Lyapunov函数方法,给出了鲁棒保成本控制器存在的充分条件以及相应的可保成本指标,并证明了这个条件等价于一组线性矩阵不等式(LM Is)的可解性问题,同时推广了已知的相关结果.最后以算例验证了设计方法的有效性.     

基于观测器的广义时滞系统弹性保成本控制

在同时考虑系统矩阵参数不确定性和控制器不确定性对系统性能影响的前提下,研究了一类基于观测器的不确定广义时滞系统的弹性保成本控制问题.基于Lvapunov稳定性理论,通过构造广义Lyapunov函数和广义二次性能指标函数,以线性矩阵不等式的形式给出了基于观测器状态反馈的弹性保成本控制器的设计方法.该控制器不仅保证了广义时滞系统是鲁棒稳定而且使其具有相应的性能指标上界.采用一种新方法将系统弹性保成本控制器设计和状态观测器增益矩阵求取转化为两组严格线性矩阵不等式的可行解问题.最后通过算例验证了该方法的可行性和有效性.