Adaptive terminal sliding mode control for high-order nonlinear dynamic systems

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Sliding mode identifier for parameter uncertain nonlinear dynamic systems with nonlinear input

This paper presents a sliding mode (SM) based identifier to deal with the parameter identification problem for a class of parameter uncertain nonlinear dynamic systems with input nonlinearity. A sliding mode controller (SMC) is used to ensure the global reaching condition of the sliding mode for the nonlinear system; an identifier is designed to identify the uncertain parameter of the nonlinear system. A numerical example is studied to show the feasibility of the SM controller and the asymptotical convergence of the identifier. Project supported by the National Natural Science Foundation of China(No. 69974035) and Zhejiang Provincial Natural Science Key Foundation of China (ZD9905)     

基于积分型李亚普诺夫函数的直接自适应模糊控制

针对一类具有未知下三角形函数控制增益矩阵的非线性系统，根据滑模控制原理，并利用I型模糊系统的逼近能力，提出了一种直接自适应模糊控制器设计的新方案．通过引入积分型李亚普诺夫函数及逼近误差自适应补偿项，证明了闭环系统是全局稳定的，跟踪误差收敛到零．仿真结果表明了该方法的有效性．     

基于终端滑模控制的四轮独立驱动汽车转矩分配方法

研究目的：四轮独立驱动汽车四个车轮的电机转矩可以正、反向输出,有必要对其底盘集成控制系统进行针对性设计以保证各车轮间的协调运作。集成控制系统一般可以分为上层运动控制器和下层力分配器。对于运动控制器的设计,同类研究一般采用滑模控制方法来处理汽车运动的非线性特征,其中终端滑模控制因具有高的稳态精度和有限时间收敛的特点而成为研究热点。对于力分配器的设计,通常方法不能在保证运算效率的同时考虑到执行器的约束,从而很难应用于实际。本文采用终端滑模控制方法来设计运动控制器,通过分析驾驶员操作行为从而更好地追踪理想的车辆运动目标;并提出一种简单有效的转矩分配控制策略,通过考虑轮胎附着极限从而将运动总力分配至四个车轮上。创新要点：本文创新性地将终端滑模控制应用到底盘集成控制系统以实现车辆纵向、侧向及横摆运动的联合控制;本文提出了一种新颖的转矩分配控制策略,将复杂的有约束控制分配问题分解至若干个简单的无约束分配子问题。研究方法：本文采用分层式协调控制方案（图1）,应用非奇异和全局快速终端滑模控制方法设计运动控制器,提出一种基于伪逆矩阵的有约束转矩分配策略,应用驾驶员最优预瞄加速度模型来描述和分析人-车闭环系统的运动响应,通过MATLAB/Simulink和CarSim的联合仿真对所设计的四轮独立驱动汽车转矩分配方法进行对比验证。所设定的三个仿真工况包括：开环方向盘角阶跃输入（图6、7及表2）、闭环双移线工况（图8–10）和闭环对开路面制动（图11–15）,分别用以测试车辆横摆、侧向及纵向方向上的动力学响应。重要结论：本文提出的基于终端滑模控制的四轮独立驱动汽车转矩分配方法将车辆的稳态转向特性由不足转向转变为中性转向,驾驶员从而?     

Adaptive backstepping sliding mode control for nonlinear systems with input saturation

An adaptive backstepping sliding mode control is proposed for a class of uncertain nonlinear systems with input saturation.A command filtered approach is used to prevent input saturation from destroying the adaptive capabilities of neural networks (NNs).The control law and adaptive updating laws of NNs are derived in the sense of Lyapunov function,so the stability can be guaranteed even under the input saturation.The proposed control law is robust against the disturbance,and it can also eliminate the impact of input saturation.Simulation results indicate that the proposed controller has a good performance.     

基于RBF神经网络和积分型高阶滑模控制的永磁同步电机位置伺服系统

本文主要研究永磁同步电机伺服系统的位置跟踪问题。根据矢量控制原理,针对d轴电压,设计了一阶滑模控制器,将使d轴电流在有限时间到达0。针对q轴电压,基于滑模控制理论,设计了积分型高阶滑模控制器。由于系统中存在不确定性参数,设计了基于神经网络的q轴电压滑模控制器。理论分析表明,在所设计的控制器作用下,可以保证位置系统的精确跟踪控制。仿真结果表明了该控制方案具有较好的收敛性和抗干扰性能。     

基于多层神经网络的饱和非线性输入自适应控制

针对一类具有未知饱和模型的单输入单输出非线性系统的控制问题,根据滑模控制原理和多层神经网络的逼近能力,提出了一种直接自适应神经网络控制器的设计新方案。该方法将控制增益推广到未知函数,通过补偿饱和模型方法取消了饱和模型各参数已知的条件。鲁棒项的引入消除了建模误差和参数估计误差的影响。理论分析证明了闭环系统是半全局一致终结有界,跟踪误差收敛到零的邻域内。仿真结果进一步表明所提控制方法的有效性。     

Decentralized Control Based on FNNSMC for Interconnected Uncertain Nonlinear Systems

针对一类具有高阶关联项的大系统提出了一种新型控制器———模糊神经网络滑模控制器,该控制器将模糊神经网络与滑模控制器有机结合,消除了一般滑模控制器中的高频颤动现象,同时不需要知道系统中的不确定性和扰动的上界．实例仿真说明了控制器不仅能得到好的控制效果,而且具有比一般滑模控制器强的鲁棒性     

Continuous robust tracking controllers for a class of uncertain nonlinear dynamical systems

Robust tracking controller for a class of uncertain nonlinear dynamical systems, which are linearizable by input-output feedback with matching uncertainties, was investigated. In this study, uniform ultimate bound or uniformly asymptotic stability of tracking errors were obtained by different choice of the control gain. A simulation to determine the effectiveness of the proposed approach showed that the control performance was better than that of VSC (Variable Structure Control). Project(69934030) supported by Natural Science Foundation of China.     

Passive control of Permanent Magnet Synchronous Motor chaotic system based on state observer

INTRODUCTION Many people paid attention to passive theory and used it to control chaotic dynamical systems (Byrnes and Isidori, 1991; Yu, 1999). Yu (1999) studied the passive equivalence of the Lorenz chaotic system and presented the method of passive control of chaotic system. Using passive theory, Qi and Zhao (2005) researched on the control of Permanent Magnet Synchronous Motor chaotic system, and stabilized the system at different equilibrium points. However, in order to design th…     

一类高阶关联大系统的分散自适应模糊控制

针对一类关联项的上界是高阶多项式的关联大系统,设计了一种新的分散自适应模糊控制方法。该方法无须假设未知增益函数与子系统的最后一个分量无关,并且取消了未知增益导函数有界的前提假设,各个子系统仅根据自己的信息就能确定相应的控制量,真正实现了分散控制。基于Lyapunov稳定理论,分析证明了闭环系统一致终结有界,跟踪误差渐近收敛到零。仿真结果表明了所设计方法的有效性。     

一类非线性系统的自适应模糊滑模控制

针对一类不确定非线性系统提出了一种自适应模糊控制方法。该方法用模糊逻辑系统(FLS)逼近理想控制器；用滑模补偿控制器(SMCC)全局补偿逼近误差和系统的不确定性并消除外部干扰的影响，能够保证闭环系统全局渐近稳定，跟踪误差收敛到原点的邻域内。在闭环系统的稳定性分析中取消了文[1-4]中要求的逼近误差平方可积的条件。     

A new controller for the semi-active suspension system with magnetorheological dampers

~~under the sliding mode controller. It shows that the sliding mode controller yield almost perfect tracking to the reference model. It can be seen in Fig.6 that the acceleration of sprung mass under sliding mode controller is controlled within ?.7 m/s2. Fig.7 shows the robustness and stability of the sliding mode controller to the parameter variations of the system to be controlled, in this case, a relative decrease of 10 % in the sprung mass and a relative increase of 15 % in the stiffness o…     

A new controller for the seni-active suspension system with magnetor heological dampers

A new sliding mode controller for semi-active suspension system with magnetorheological (MR) damper is presented in this paper. In the proposed sliding mode controller, a semi-active suspension based on the skyhook damper system is chosen as the reference model to be followed, and the control law is so determined that the asymptotically stable error dynamics occurs between the controlled state and the reference model state. Numerical simulations are carried out to study the performance of the new sliding mode controller. The results show that the proposed controller yields almost perfect tracking to the reference model and has a high robustness against model parameter uncertainties and disturbances.     

Nonlinear dynamics analysis of a new autonomous chaotic system

In this paper,a new nonlinear autonomous system introduced by Chlouverakis and Sprott is studied further,to present very rich and complex nonlinear dynamical behaviors. Some basic dynamical properties are studied either analytically or nu-merically,such as Poincaré map,Lyapunov exponents and Lyapunov dimension. Based on this flow,a new almost-Hamilton chaotic system with very high Lyapunov dimensions is constructed and investigated. Two new nonlinear autonomous systems can be changed into one another by adding or omitting some constant coefficients.     

Hybrid adaptive compensation control scheme for high-precision servo system

In this paper,a hybrid adaptive compensation control scheme is proposed to compensate the friction occurrence and other nonlinear disturbance factors that exist in the high-precision servo system.An adaptive compensation controller with a dual-observer structure is designed,while the LuGre dynamic friction model with non-uniform parametric uncertainties characterizes the friction torque.Considering the influence of the periodic disturbance torque and parametric uncertainties,fuzzy systems and a robust term are employed.In this way,the whole system can be treated as a simple linear model after being compensated,then the proportional-derivative (PD) control law is applied to enhancing the control performance.On the basis of Lyapunov stability theory,the global stability and the asymptotic convergence of the tracking error are proved.Numerical simulations demonstrate that the proposed scheme has potentials to restrain the impact of disturbance and improving the tracking performance.     

Robust Adaptive Control Design for Rotorcraft Unmanned Aerial Vehicles Based on Sliding Mode Approach

This paper presents a nonlinear robust control design method for a generic rotorcraft unmanned aerial vehicle（RUAV）. The control objective is to let the RUAV track some pre-defined time-varying position and headingtrajectories. The proposed controller employs feedback linearization process to realize the dynamic decoupling controland applies adaptive sliding mode control to compensate for the parametric uncertainties and external disturbances.The global asymptotical stability is proved via stability analysis. Compared with the cascaded controller, the proposedcontroller demonstrates a superior tracking performance and robustness through numerical simulation in the presenceof parametric uncertainties and unknown disturbances.     

基于DSC的自适应补偿神经网络控制

针对一类可转化为“标准块控制形”的MIMO非线性系统,基于动态面控制技术,提出一种鲁棒自适应神经网络控制算法。采用径向基函数神经网络逼近不确定性模型,通过引入一阶滤波器,消除后推设计中由于反复对虚拟控制的求导而导致的复杂性问题,同时补偿项的引入可避免反馈线性化方法中可能出现的控制器奇异性问题,无需控制增益矩阵正定、可逆的条件。利用李亚普诺夫方法,证明了闭环系统是半全局一致终结有界,适当选取设计常数,跟踪误差可收敛到原点的一个小邻域内。计算机仿真结果表明此法的有效性。     

新型混联式输送机构的有限时间收敛滑模控制研究

针对一种新型混联式汽车电泳涂装输送机构控制方法存在收敛时间较长问题,提出一种有限时间收敛滑模控制方法。首先采用解析法对机构进行运动学分析,并基于拉格朗日法建立输送机构动力学模型;提出一种快速终端滑模有限时间收敛控制方法,实现新型混联式输送机构控制的有限时间收敛;然后设计有限时间滑模观测器,实时观测被控对象模型中的不确定参数以及外部随机干扰并加以前馈补偿,以进一步提高系统鲁棒性,同时解决快速终端滑模控制存在的抖振问题;最后运用Lyapunov稳定性理论证明该控制方法的稳定性,利用MATLAB对控制方法进行仿真,并将其应用于新型混联式输送机构样机进行实验,结果表明该控制器具有跟踪误差小、稳态精度高、响应速度快、鲁棒性好的特点。     

Control uncertain continuous-time chaotic dynamical system

The new chaos control method presented in this paper is useful for taking advantage of chaos. Based on sliding mode control theory, this paper provides a switching manifold controlling strategy of chaotic system, and also gives a kind of adaptive parameters estimated method to estimate the unknown systems' parameters by which chaotic dynamical system can be synchronized. Taking the Lorenz system as example, and with the help of this controlling strategy, we can synchronize chaotic systems with unknown parameters and different initial conditions. Project supported by Doctoral Subject Research Fund of Ministry of Education of China (1999033512) and Science and Technology Plan Fund of Zhejiang Province (991110412)