THE LIMIT CYCLES AND HOPF BIFURCATION OF A CLASS OF SIMPLIFIED HOLLING TYPE-IV PREDATOR-PREY SYSTEM WITH LINEAR STATE FEEDBACK

In this paper, a class of simplified Type-IV predator-prey system with linear state feedback is investigated. We prove the boundedness of the positive solutions to this system, and analyze the quality of the equilibria and the existence of limit cycles of the system surrounding the positive equilibra. By Hopf bifurcation theory, the result of having two limit cycles to the system is obtained.

On Asymptotic Stabilization of Linear Discrete-time Systems with Saturated State Feedback

As saturation is involved in the stabilizing feedback control of a linear discrete-time system, the original global-asymptotic stabilization (GAS) may drop to region-asymptotic stabilization (RAS). How to test if the saturated feedback system is GAS or RAS? The paper presents a criterion to answer this question, and describes an algorithm to calculate an invariant attractive ellipsoid for the RAS case. At last, the effectiveness of the approach is shown with examples.

Robust H_∞ Stabilization of Uncertain Linear Time-Delay System with Delayed/Undelayed State Feedback Controllers

This paper focuses on the H∞ controller design for linear systems with time-varying delays and norm-bounded parameter perturbations in the system state and control/disturbance. On the existence of delayed/undelayed full state feedback controllers, we present a sufficient condition and give a design method in the form of Riccati equation. The controller can not only stabilize the time-delay system, but also make the H∞ norm of the closed-loop system be less than a given bound. This result practically generalizes the related results in current literature.

Finite-time State Feedback Stabilization Method for a Class of Flexible Manipulators

Aimed at the finite-time stabilization problem of a class of flexible manipulators,a finite-time state feedback stabilization controller was proposed in this paper.Firstly,the nonlinear model of flexible manipulators was transformed into linear system through the exact state feedback linearization,and then using the finite time stabilization control method of the linear system,a finite-time state feedback stabilization controller was designed for the flexible manipulators.Furthermore,it was proved that all the states of flexible manipulators could be stabilized to equilibrium in finite-time under the proposed controller.The simulation results show that the performance of the flexible manipulators under the proposed finite-time state feedback controller is better than the traditional state-feedback controller.The proposed finite-time stabilization controller can improve the performance of the flexible manipulators.

Switching Feedback Stabilization for Discrete Linear Multiple-input Systems

New idea of stabilization for discrete linear multiple-input system is proposed based on switching technique and single-input control. The system discussed here denotes coupled singleinput objects to be controlled. The central processing unit chooses an object at each discrete instant according to periodic switching strategy and controls it by local state feedback. Stabilization of a multiple-input system is turned into stabilization of single-input systems under periodic switching strategy, which is easy to be realized in practice. On the other hand, only one central processing unit can realize all local controllers, which decreases the cost and increases the usage of the resources.

Robust Control System Design Using Proportional Plus Partial Derivative State Feedback

经由为矩阵对的概括特征值敏感问题的比例的正部分衍生物状态反馈和结果把线性系统基于为描述符建议的一般参量的 eigenstructure 赋值结果，到在开环的系统矩阵的使不安的元素的靠近环的特征值敏感的参量的表示被获得。为有在经由反馈当时是的比例的正部分衍生物状态的线性系统建议了的描述符的最小的敏感的特征值赋值的一个有效算法。算法不包含回到过程，并且允许靠近环的特征值方便地在需要的区域以内被优化。一个例子表明它的有效性和简洁。

基于扰动和输入饱和限制的连续时间系统预见跟踪控制

本文研究一类带有外部干扰和输入饱和的连续时间系统的预见控制问题.为了能成功地构造出连续时间输入饱和系统的误差系统,与以往对系统方程求导不同,本文利用状态平移方法代替状态求导,使得输入饱和连续时间系统的误差系统的构造成为可能.这样原系统的预见饱和控制就转化为误差系统的标准饱和控制问题.另外,针对原系统的误差系统,分别引入状态反馈和静态输出反馈,并改写输入向量以便利用可预见信号的未来信息.利用Lyapunov函数及LMI技巧,导出了闭环系统渐近稳定的充分条件.最后仿真例子表明了本文结果的有效性.

Study on the Application of Iterative Learning Control to Terminal Control of Linear Time-varying Systems

An iterative learning control algorithm based on shifted Legendre orthogonal polynomials is proposed to address the terminal control problem of linear time-varying systems. First, the method parameterizes a linear time-varying system by using shifted Legendre polynomials approximation. Then, an approximated model for the linear time-varying system is deduced by employing the orthogonality relations and boundary values of shifted Legendre polynomials. Based on the model, the shifted Legendre polynomials coefficients of control function are iteratively adjusted by an optimal iterative learning law derived. The algorithm presented can avoid solving the state transfer matrix of linear time-varying systems. Simulation results illustrate the effectiveness of the proposed method.

Singular linear quadratic performance with the worst disturbance rejection for descriptor systems

This paper deals with the problem of singular linear quadratic performance with the worst-disturbance rejection for descriptor systems. Under the conditions we give, the worst-disturbance and the optimal control-state pair are unique respectively, the optimal control can be synthesized as state feedback and the closed-loop system is regular, stable and impulse-free.

Delay-dependent robust stabilization for a class ofneutral systems with nonlinear perturbations

This note deals with the problem of stabilization/stability for neutral systems with nonlinear perturbations. A new stabilization/stability scheme is presented. Using improved Lyapunov functionals, less conservative stabilization/stability conditions are derived for such systems based on linear matrix inequalities （LMI）. Numerical examples are provided to show that the proposed results significantly improve the allowed upper bounds of the delay size over some existing ones in the literature.

Analysis and control of a class of uncertain linear periodic discrete-time systems

Feedback control problems for linear periodic systems （LPSs） with interval- type parameter uncertainties are studied in the discrete-time domain. First, the stability analysis and stabilization problems are addressed. Conditions based on the linear matrices inequality （LMI） for the asymptotical stability and state feedback stabilization, respec-tively, are given. Problems of L2-gain analysis and control synthesis are studied. For the L2-gain analysis problem, we obtain an LMI-based condition such that the autonomous uncertain LPS is asymptotically stable and has an L2-gain smaller than a positive scalar γ. For the control synthesis problem, we derive an LMI-based condition to build a state feedback controller ensuring that the closed-loop system is asymptotically stable and has an L2-gain smaller than the positive scalar γ. All the conditions are necessary and sufficient.

Adaptive practical output tracking of a class of nonlinear systems

Focus is laid on the adaptive practical output-tracking problem of a class of nonlinear systems with high-order lower-triangular structure and uncontrollable unstable linearization. Using the modified adaptive addition of a power integrator technique as a basic tool, a new smooth adaptive state feedback controller is designed. This controller can ensure all signals of the closed-loop systems are globally bounded and output tracking error is arbitrary small.

Robust Optimal H∞ Control for Uncertain 2-D Discrete State-Delayed Systems Described by the General Model

This paper investigates the problem of robust optimal H∞ control for uncertain two-dimensional (2-D) discrete state-delayed systems described by the general model (GM) with norm-bounded uncertainties. A sufficient condition for the existence of g-suboptimal robust H∞ state feedback controllers is established, based on linear matrix inequality (LMI) approach. Moreover, a convex optimization problem is developed to design a robust optimal state feedback controller which minimizes the H∞ noise attenuation level of the resulting closed-loop system. Finally, two illustrative examples are given to demonstrate the effectiveness of the proposed method.

Delay-dependent robust H-infinity control for discrete-time uncertain systems with time-varying state delays

This paper examines the delay-dependent H-infinity control problem for discrete-time linear systems with time-varying state delays and norm-bounded uncertainties. A new inequality for the finite sum of quadratic terms is first established. Then, some new delay-dependent criteria are derived by employing the new inequality to guarantee the robust stability of a closed-loop system with a prescribed H-infinity norm bound for all admissible uncertainties and bounded time-vary delays. A numerical example demonstrates that the proposed method is an improvement over existing ones.

基于LMI的水轮机调节系统扰动观测状态反馈控制策略研究

为进一步提高水轮机的调节性能和控制精度,针对水轮机调节系统提出了一种基于线性矩阵不等式(LMI)的扰动观测状态反馈控制策略。首先,对水轮机调节系统进行了建模,并设计了一种基于LMI的扰动观测状态反馈控制策略,该策略综合考虑了水轮机的运行状态及扰动观测值;然后通过LMI完成了该控制器的设计与分析;最后,为了验证所提控制策略的有效性和鲁棒性,通过仿真试验进行了测试。结果表明,与传统的控制方法相比,该扰动观测状态反馈控制策略可有效提高水轮机调节系统的响应速度、准确性和稳定性,且降低了系统对扰动的敏感性。

无人直升机部分姿态约束安全飞行控制

针对无人直升机系统,在保证姿态约束在指定范围的前提下,研究其全自由度控制问题。考虑到系统的强非线性、强耦合性、欠驱动性以及中间控制变量需保证有界等特点,文中通过反馈线性化方法降低非线性和耦合性的强度,设计控制器直接控制3个位置自由度和偏航角。同时,利用障碍Lyapunov函数方法局部约束中间变量来间接控制滚转角和俯仰角,保证直升机姿态有界。结合非线性系统控制理论,在保证跟踪误差系统有界的同时对系统进行稳定性分析。最后通过模拟实例验证了该方法的有效性。

基于LPV模型的挠性航天器保性能姿态控制方法

针对带转动挠性帆板航天器的动力学参数存在不确定性的问题,提出一种利用线性变参数理论(LPV)的鲁棒保性能姿态控制器设计方法。以太阳帆板转角作为变参数,建立挠性航天器姿态动力学LPV模型。考虑输入受限及输入信号变化率受限的约束,并将二次型控制指标上限最优化,通过线性矩阵不等式(LMI)方法求解得到随变参数调度的LPV状态反馈控制器,所求得的控制器能够在系统参数大范围变化的情况下保持鲁棒稳定性,并具备抗干扰能力。用数值方法进行仿真验证,并与定常鲁棒保性能控制器相比较,验证了所提出的LPV鲁棒保性能控制器的适应性与鲁棒性。

基于LESO的DFIG-GSC反馈线性化直接功率控制

为了提高双馈风力发电机网侧变换器(DFIG-GSC)这个强耦合非线性系统的性能,提出了一种反馈线性化直接功率控制策略。首先在αβ坐标系下建立以有功功率、无功功率为变量的DFIG-GSC的数学模型,针对模型中的强耦合项采用反馈线性化进行解耦,得到其线性模型,再结合滑模控制理论设计出功率内环的控制律。由于功率内环控制律中未建模部分和不确定因素会对控制效果产生影响,采用线性扩张状态观测器对其进行观测并对其控制量进行修正。同时电压外环采用滑模控制来提高直流侧电压的响应速度。最后搭建仿真模型与传统PI控制以及直接功率控制进行比较,验证了所提控制策略的合理性和有效性。

基于LESO的MMC-RPC反馈线性化直接功率控制

模块化多电平铁路功率调节器作为一个耦合的多变量非线性系统,传统PI控制的直接功率控制难以实现对系统的精确解耦.本文提出了一种基于线性扩张状态观测器的反馈线性化直接功率控制方法,根据Lie导数构建了模块化多电平铁路功率调节器(MMC-RPC)两输入/两输出功率仿射模型,设计了精确反馈线性化功率解耦控制器.针对不确定因素等扰动对精确反馈线性化控制效果的影响,设计了线性扩张状态观测器对扰动进行观测和补偿,实现了功率的精确跟踪控制.最后,通过MATLAB/Simulink平台搭建仿真模型对所提控制方法进行了验证.