Global Output-Feedback Tracking for Nonlinear Cascade Systems with Unknown Growth Rate and Control Coefficients

This paper deals with the global practical tracking problem by output-feedback for a class of uncertain cascade systems with zero-dynamics and unmeasured states dependent growth.The systems investigated are substantially different from the closely related works,and have zero-dynamics,unknown growth rate,and unknown time-varying control coefficients.This makes the problem much more difficult to solve.Motivated by the authors' recent works,this paper proposes a new adaptive control scheme to achieve the global practical tracking.It is shown that the designed controller guarantees that the state of the resulting closed-loop system is globally bounded and the tracking error converges to a prescribed arbitrarily small neighborhood of the origin after a finite time.This is achieved by combining the methods of universal control and dead zone with backstepping technique,and using the framework of performance analysis in the closely related works.A numerical example demonstrates the effectiveness of the theoretical results.     

Adaptive Tracking Control for Mobile Manipulators with Stochastic Disturbances

This paper investigates adaptive tracking control for mobile manipulators with stochastic disturbances and parametric uncertainties. Based on an appropriate reduced dynamic model and an adaptive law, a controller, which is provided by incorporating stochastic control theory with related adaptive technique, overcomes the problem of over-parametrization. It is shown that the designed state-feedback controllers can guarantee that the mean square of the tracking errors can be made arbitrarily small by choosing suitable design parameters. Simulation studies on the control of 2-DOF mobile manipulator shows the effectiveness of the proposed scheme.     

Adaptive practical tracking control by output feedback for a class of nonlinear systems

This paper investigates the problem of adaptive practical tracking control by output feedback for a class of nonlinear systems in which the nonlinearities are restricted to be upper bounded by a constant plus a polynomial function of the output multiplied by unmeasured states. To solve the problem, an observer with a dynamic high-gain is first introduced, and then an adaptive output feedback tracking controller is successfully designed using the universal control methodology. It is shown that all the states of the closed-loop system are bounded, and the tracking error can be made arbitrarily small by an appropriate choice of the design parameters after some large enough time. A simulation example is also provided to illustrate the correctness of the theoretical results.     

Combined indirect and direct method for adaptive fuzzy output feedback control of nonlinear system

A novel control method for a general class of nonlinear systems using fuzzy logic systems (FLSs) is presertted. Indirect and direct methods are combined to design the adaptive fuzzy output feedback controller and a high-gain observer is used to estimate the derivatives of the system output. The closed-loop system is proven to be semiglobally uniformly ultimately bounded. In addition, it is shown that if the approximation accuracy of the fuzzy logic system is high enough and the observer gain is chosen sufficiently large, an arbitrarily small tracking error can be achieved. Simulation results verify the effectiveness of the newly designed scheme and the theoretical discussion.     

Chaos and Nonlinear Feedback Control of the Arch Micro-Electro-Mechanical System

This paper addresses a nonlinear feedback control problem for the chaotic arch microelectro- mechanical system with unknown parameters, immeasurable states and partial state-constraint subjected to the distributed electrostatic actuation. To reflect inherent properties and design controller, the phase diagrams, bifurcation diagram and Poincare section are presented to investigate the nonlinear dynamics. The authors employ a symmetric barrier Lyapunov function to prevent violation of constraint when the arch micro-electro-mechanical system faces some limits. An RBF neural network system integrating with an update law is adopted to estimate unknown function with arbitrarily small error. To eliminate chaotic oscillation, a neuro-adaptive backstepping control scheme fused with an extended state tracking differentiator and an observer is constructed to lower requirements on measured states and precise system model. Besides, introducing an extended state tracking differentiator avoids repeated derivative for the virtual control signal associated with conventional backstepping. Finally, simulation results are presented to illustrate feasibility of the proposed scheme.     

欠驱动VTOL飞行器的位置反馈动态面控制

针对非最小相位欠驱动垂直起降飞行器系统,提出一种位置反馈动态面控制算法。首先设计高增益观测器,估计系统未知状态;然后采用动态面控制方法避免Backstepping设计存在的“微分爆炸”现象,同时简化控制律设计过程;最后采用Lyapunov直接法证明闭环系统所有信号一致有界,且跟踪误差通过调节控制器参数可以达到任意小。理论分析和仿真表明,所提方法能减轻计算负担,降低对系统状态的测量要求,实现飞行器位置准确跟踪,并对非线性建模的参数不确定性具有鲁棒性。     

Neural adaptive sliding mode speed tracking control of a DC motor

We propose a BPNN based adaptive sliding mode control scheme for speed tracking of a DC motor with unknown system nonlinearities. The input-output linearization technique is used to cancel the nonlinearities, and output of the BPNN is incorporated into the controller in the proposed scheme. It is shown that the rotor speed of a DC motor can follow any arbitrarily selected trajectories under variable load torque. Then the application of the approach is tested via some simulations.     

A NOTE ON NONLINEAR ROBUST H∞ ALMOST DISTURBANCE DECOUPLING PROBLEM WITH STABILITY

1 IntroductionThe problem of a1most disturbance deco1lpling with stability(ADDPS fOr short) was orig-inally formulated and solved fOr linear systems by Willems in l98l([ll). Since then variousgeneralizations to nonlinear systems have been xnade(see, fOr e…     

QFT control based on zero phase error compensation for flight simulator

To improve the robustness of high-precision servo systems, quantitative feedback theory (QFT) which aims to achieve a desired robust design over a specified region of plant uncertainty is proposed. The robust design problem can be solved using QFT but it fails to guarantee a high precision tracking. This problem is solved by a robust digital QFT control scheme based on zero phase error (ZPE) feed forward compensation. This scheme consists of two parts: a QFT controller in the closed-loop system and a ZPE feed-forward compensator. Digital QFT controller is designed to overcome the uncertainties in the system. Digital ZPE feed forward controller is used to improve the tracking precision. Simulation and real-time examples for flight simulator servo system indicate that this control scheme can guarantee both high robust performance and high position tracking precision.     

ADAPTIVE PRACTICAL OUTPUT MANEUVERING CONTROL FOR A CLASS OF NONLINEAR SYSTEMS

This paper deals with the adaptive practical output maneuvering control problems for a class of nonlinear systems with uncontrollable unstable linearization. The objective is to design a smooth adaptive maneuvering controller to solve the geometric and dynamic tasks with an arbitrary small steady tracking error. The method of adding a power integrator and the robust recursive design technique are employed to force the system output to track a desired path and make the tracking speed to follow a desired speed along the path. An example is considered and simulation results are given. The proposed design procedure can be illustrated by the use of this example.     

一类严格反馈时滞系统的自适应输出反馈控制

针对一类单输入单输出的严格反馈时滞系统研究跟踪控制问题。该控制系统包含不确定项、输出约束、未知死区特性和未知时间延迟。首先,设计一个状态观测器来估计无法测量的系统状态;其次,利用径向基函数(radial basis function,RBF)神经网络去逼近未知的系统内部动态;同时,利用障碍李雅普诺夫(Lyapunov)函数确保输出约束及Lyapunov-Krasovskii方法消除时滞项对系统的影响;最后,基于Lyapunov稳定性理论,构造一个鲁棒自适应神经网络输出反馈控制器,并且克服了过参数问题。结果显示,设计的神经网络输出反馈控制器可以保证闭环系统中的所有信号都是半全局最终一致有界的,跟踪误差能收敛到零值小的领域内。文中通过两个例子进一步验证了提出方法的有效性。     

FINITE TIME TRACKING CONTROL FOR RIGID ROBOTIC MANIPULATORS WITH FRICTION AND EXTERNAL DISTURBANCES

1.Introduction Variable structure control is well known for its robustness to system uncertainties and external disturbances and has been successfully applied to the rigid robotic manipulator systems(Utkin(1992),Zinober(1990)).Generally,a linear sliding mode is firstly designed to describe the desired system error dynamics,a robust controller drives the switching plane variables to reach the sliding mode,and the error dynamics will asymptotically converge to zero on the linear sliding mode.Si…     

Best tracking performance for integrator and dead time plant

The optimal tracking performance for integrator and dead time plant in the case where plant uncertainty and control energy constraints axe to be considered jointly is inrestigated.Firstly,an average cost function of the tracking error and the plant input energy over a class of stochastic model errors are defined.Then,we obtain an internal model controller design method that minimizes the average performance and further studies optimal tracking performance for integrator and dead time plant in the simultaneous presence of plant uncertainty and control energy constraint.The results can be used to evaluate optimal tracking performance and control energy in practical designs.     

基于MATLAB的非完整动力学系统跟踪控制的动态仿真

本文详细阐述了如何用MATLAB进行非完整动力学系统轨迹跟踪控制的仿真。基本思想是将MATLAB中的Simulink和S函数相结合构造了非完整动力学系统的模型模块和控制器模块,将它们搭成仿真模型,其中包含了难于处理的非完整约束问题。该模型清晰地表达了系统中所有变量之间的数学关系,仿真结果表明该模型的有效性和可行性。本文为非完整动力学系统跟踪控制的仿真提供了新的途径,对非完整系统的设计和优化有一定的参考意义。     

Adaptive control of system with hysteresis using neural networks

1.INTRODUCTIONThe piezoelectric actuators are well suited for micro-position devices in precision engineering because oftheir fast response,nanometer resolution and biggerdriving force[1].However,hysteresis inherent topiezoelectric actuator severely li mits system’s perfor-mance such as giving rise to undesirable accuracy oroscillations,even leading to instability.Hysteresischaracteristics are generally nondifferentiable andusually unknown.It is a difficult task to mitigate itsharmful ef…     

空空导弹控制系统鲁棒动态逆设计

将导弹动力学分离为快变状态动力学子系统和慢变状态动力学子系统,分别进行非线性动态逆控制设计。应用基于李雅普诺夫稳定性的鲁棒控制方法,设计出期望的慢变动力学和快变动力学,以保证动态逆控制系统对气动系数摄动的鲁棒稳定性。给出了通过构造动态反插值表,由力矩系数指令反解舵偏角指令的反插值方法。动态逆方法所需要的速度指令、滚动角指令及其一、二阶导数通过滤波器得到。对过载回路的稳定性问题和跟踪误差进行了定性分析,给出了过载回路的无静差设计方案,作为对动态逆的补充设计。给出了导弹控制系统六自由度数学仿真结果。     

Decentralized model reference adaptive sliding mode control based on fuzzy model

1.INTRODUCTIONIn recent years,decentralized control of interconnect-ed systems has become an i mportant and challengingtopic[1~3].However,it is usually difficult to modelthe systemexactly due to the complex real environ-ment.In the past several years,active research hasbeen carried out in controller design based on univer-sal approxi mators,such as fuzzy control and neuralnetwork control[4~6].For a class of SISO nonlinearsystems,adaptive fuzzy control approaches were pro-posed based on …     

多变量非线性系统的直接自适应模糊预测控制

对一类多变量非线性系统提出了直接自适应模糊预测控制方法,此方法首先对被控对象提出了线性时变子模型加非线性子模型的预测模型,然后直接利用模糊系统设计预测控制器,并基于时变增益自适应律对控制器中的未知向量和逼近误差估计值进行自适应调整。证明了此方法可使跟踪误差收敛到原点的一个邻域内,仿真结果验证了此方法的有效性。     

基于DSC和MLP的欠驱动船舶自适应滑模轨迹跟踪控制

针对存在船舶动态不确定和外界干扰的欠驱动水面船舶轨迹跟踪控制问题,提出一种基于动态面控制(dynamic surface control,DSC)和最小学习参数法(minimal learning parameter,MLP)的自适应滑模控制方法。在控制律的设计过程中,为实现位置跟踪误差的收敛,利用反步法设计船舶前向速度和横漂速度的虚拟控制律镇定轨迹跟踪误差;引入DSC技术,用于消除反步法对虚拟控制求导引起的“微分爆炸”问题;另外,采用MLP技术,以单参数在线学习代替所有权值在线学习,减少控制器的计算量,避免出现“维数灾难”问题,并结合带有“σ-修正”的自适应律,防止参数漂移,易于工程的实现。稳定性分析证明了所设计控制律可以保证轨迹跟踪船舶闭环系统中轨迹跟踪误差信号一致最终有界,仿真结果验证了所设计控制器的有效性。     

新型六旋翼飞行器的轨迹跟踪控制

针对新型六旋翼飞行器,提出一种轨迹跟踪控制策略。首先,给出了六旋翼飞行器的运动学模型和动力学模型,同时给出存在复合干扰情况下的运动学模型,并提出了一种新的复合干扰估计算法,该算法是由干扰估计误差驱动而非传统的状态跟踪或者预测误差。随后,设计了飞行器动力学和运动学模型的backstepping控制器,在动力学模型的控制器设计中将指令滤波和线性跟踪微分器用于其中,以提高系统对控制指令的响应速度。最后,通过仿真验证实验,验证了所提干扰估计算法和轨迹跟踪策略的正确性和有效性。