Contour Tracking of a Redundant Robot Using Integral Variable Structure Control with Output Feedback

This work examines the contour tracking problem of redundant robot on a path with singularity. Using an optimal quadratic programming method is to solve the singularity problem and the computing load of motion planning is reduced by a novel hybrid motion planning method. To achieve contour tracking with output feedback, an integral sliding mode control with a high-gain observer is employed to eliminate the chattering due to discontinuous switching control of the sliding-mode control and maintain robustness of the ideal sliding mode.     

不确定离散时间系统积分滑模保性能控制

针对不确定离散时间系统,研究其积分滑模（ＩＳＭ）保性能控制的设计问题．将最优保性能积分滑模面设计问题,转化为一个具有线性矩阵不等式（ＬＭＩ）约束的目标函数凸优化问题,给出了最优保性能积分滑模面存在的充分条件,并结合干扰估计器设计相应的保性能控制器．与传统滑模控制相比较,积分滑模保性能控制系统具有全阶滑动模态,系统的鲁棒性得到加强,消除了控制抖振和稳态抖振．仿真结果验证了该方法的有效性．     

不确定统一混沌系统平衡点的渐近稳定

研究不确定统一混沌系统平衡点的渐近稳定问题.利用滑模控制理论,给出了此类系统的滑模控制器的设计新方法和控制律算法.该控制器使得误差空间任一点出发的运动都在有限时间到达滑动模态,并沿切换面渐近到达原点,以达到将统一混沌系统控制到平衡点的目的.与现有文献所得结论相比,该文所设计的控制器算法具有抖振小、平稳性好和保守性小等优点.运动方程分析和仿真结果都验证了结论的有效性.     

基于分数阶滑模控制技术的永磁同步电机控制

针对传统整数阶滑模控制系统中存在的抖震问题,本文提出了分数阶滑模控制策略并应用到永磁同步电机的速度控制.传统滑模控制器中的开关函数由作用在切换流型或其整数阶导数面推广到其分数阶导数面,利用分数阶系统的特性,缓慢地传递系统的能量,有效地削减抖震.本文采用模糊逻辑推理算法,实现软开关切换增益的自整定.仿真和实验证明,本文提出的分数阶滑模控制系统不但能有效地削减抖震,而且能保持滑模控制器对系统参数变化和外部扰动的鲁棒性.     

不确定非线性系统的高阶滑模控制器设计

针对一类不确定非线性SISO系统,结合系统有限时间稳定理论与积分滑模控制理论,提出了一种新的高阶滑模控制器设计方法,改善了现有高阶滑模控制中存在的缺陷.积分滑模保证了系统初始时刻就具有抗扰能力,同时采用有限时间稳定观测器实现了高阶滑模的输出反馈控制.仿真结果表明该控制器可使系统在有限时间内收敛,并有效地减小了系统抖振.     

基于离散模糊滑模的飞行器角度跟踪控制

为解决某型飞行器的角度跟踪控制问题,设计了离散模糊滑模角度跟踪控制算法.以飞行器在空间的姿态运动方程为基础建立了其短周期运动模型.基于离散时间模糊滑模算法,设计了双入双出的模糊控制器,将滑模切换函数及其变化率作为模糊控制器的输入,以模糊控制器的二维输出信号为依据调整滑模趋近律的参数,该算法在减小了系统的抖振同时,保持了...     

带攻击角度约束的非奇异快速终端滑模制导律

本文利用先进的终端滑模控制和李雅普诺夫稳定性理论设计了一种非奇异、本质上连续和有限时间收敛的带攻击角度约束的制导律,它可用于打击固定、匀速运动和机动目标.为了在有限时间内高精度地获得给定的攻击角度并不出现奇异问题,非奇异快速终端滑模函数被用于设计滑模面.快速终端滑模函数被用于设计趋近律,在整个到达阶段系统轨迹可以从任意初始状态快速地收敛到滑模面并形成本质上连续的制导律.由于非奇异、本质上连续和全局快速收敛的特性,和传统的终端滑模制导律相比,本文方法可以在更短时间内以更高精度的攻击角度对目标实施打击.大量的仿真算例表明了本文制导律的有效性.     

Super-twisting second-order sliding mode control for a synchronous reluctance motor

This article presents the design and implementation of a super-twisting second-order sliding-mode controller (SOSMC) for a synchronous reluctance motor. Second-order sliding-mode control is an effective tool for the control of uncertain nonlinear systems since it overcomes the main drawbacks of the classical sliding-mode control, i.e., the large control effort and the chattering phenomenon. Its real implementation implies simple control laws, and ensures an improvement in the sliding accuracy with respect to conventional sliding-mode control. This article proposes a novel scheme that is based on the technique of super-twisting second-order sliding-mode control. First, SOSMC is derived mathematically, and then the performance of the proposed method is verified by simulations. The proposed SOSMC shows robustness for variations in the motor parameters and an improvement in the chattering phenomenon.     

Analysis of Chattering in Systems With Second-Order Sliding Modes

A systematic approach to the chattering analysis in systems with second-order sliding modes is developed. The neglected actuator dynamics is considered to be the main cause of chattering in real systems. The magnitude of oscillations in nonlinear systems with unmodeled fast nonlinear actuators driven by second-order sliding-mode control generalized suboptimal (2-SMC G-SO) algorithms is evaluated. Sufficient conditions for the existence of orbitally stable periodic motions are found in terms of the properties of corresponding Poincare maps. For linear systems driven by 2-SMC G-SO algorithms, analysis tools based on the frequency-domain methods are developed. The first of these techniques is based on the describing function method and provides for a simple approximate approach to evaluate the frequency and the amplitude of possible periodic motions. The second technique represents a modified Tsypkin's method and provides for a relatively simple, theoretically exact, approach to evaluate the periodic motion parameters. Examples of analysis and simulation results are given throughout this paper.     

H∞ tracking-based sliding mode control foruncertain nonlinear systems via an adaptive fuzzy-neural approach

A novel adaptive fuzzy-neural sliding-mode controller with H(infinity) tracking performance for uncertain nonlinear systems is proposed to attenuate the effects caused by unmodeled dynamics, disturbances and approximate errors. Because of the advantages of fuzzy-neural systems, which can uniformly approximate nonlinear continuous functions to arbitrary accuracy, adaptive fuzzy-neural control theory is then employed to derive the update laws for approximating the uncertain nonlinear functions of the dynamical system. Furthermore, the H(infinity) tracking design technique and the sliding-mode control method are incorporated into the adaptive fuzzy-neural control scheme so that the derived controller is robust with respect to unmodeled dynamics, disturbances and approximate errors. Compared with conventional methods, the proposed approach not only assures closed-loop stability, but also guarantees an H(infinity) tracking performance for the overall system based on a much relaxed assumption without prior knowledge on the upper bound of the lumped uncertainties. Simulation results have demonstrated that the effect of the lumped uncertainties on tracking error is efficiently attenuated, and chattering of the control input is significantly reduced by using the proposed approach.     

Multi-Input Second-Order Sliding-Mode Hybrid Control of Constrained Manipulators

This paper deals withthe hybrid position/force control of constrainedmanipulators subjected to uncertainties. A solution is proposedthat is based on sliding-mode control theory, which proved tobe highly effective in counteracting uncertainties for some classesof nonlinear systems. Specific problems involved in this techniqueare chattering elimination and the algebraic coupling betweenconstraint forces and possibly discontinuous control signals.Both the problems are addressed in this paper by exploiting therobustness properties of a second-order sliding-mode controlalgorithm. This algorithm, recently proposed by the authors forsolving the single-input hybrid control problem, is generalizedin this paper to deal with the class of multi-input differentialalgebraic systems describing the behaviour of constrained mechanicalsystems.     

一种基于自适应2阶终端滑模控制算法的理论和实验研究

针对一类非线性多变量被控对象的控制问题,设计了一种基于自适应2阶终端滑模的自主控制方法．与传统滑模控制方法相比,该控制方案保留了其结构简单、鲁棒性强的优点,并有效削弱了传统滑模控制引发的抖振问题．利用基于李亚普诺夫的分析方法进行闭环系统的稳定性分析,确保了闭环系统的稳定性以及控制误差有限时间收敛．通过在3自由度控制实验平台上进行姿态镇定和跟踪实验,表明本文所提出的控制方法具有良好的姿态控制效果.     

光滑滑模控制在汽车防抱死制动系统中的应用

在这个研究中,一种光滑滑模控制设计方法被应用在ABS中。在分析了单轮汽车模型的基础上,采用光滑滑模控制和传统滑模控制两种方法分别对汽车ABS进行仿真,仿真结果证明光滑滑模变结构控制可以有效地消除传统滑模控制中存在的抖振现象,达到更好的控制效果。     

带有内动态的离散不确定非线性系统的滑模预测跟踪控制

对于一类带有内动态的单输入-单输出不确定离散非线性系统,基于滑模预测控制技术设计了一个控制器.通过反馈校正和滚动优化技术,可以及时补偿不确定性的影响,提高了匹配和不匹配不确定项的鲁棒性.然后,通过滚动优化技术得到期望的滑模控制律.特别地,通过预测控制,滑模控制的抖振现象可以消除.最后,在不确定项的界未知的情况下,得到闭环系统的所有信号都是有界的,并且跟踪误差是鲁棒稳定的.仿真例子说明所提出控制方法的有效性.     

On Discretization of Continuous-Time Terminal Sliding Mode

In terminal sliding-mode control, the system states are brought to the origin in finite time using the concept of sliding-mode control. Though the theory of terminal sliding mode is well studied for continuous time systems, a discrete-time terminal sliding mode concept has not been investigated. This note analyses the applicability of terminal sliding-mode control in the discrete-time framework and discusses the problems involved in the discretization of continuous-time terminal sliding mode. The note also suggests a method to approach the discrete-time terminal sliding-mode control problem.     

Adaptive fuzzy-neural-network control for maglev transportation system

A magnetic-levitation (maglev) transportation system including levitation and propulsion control is a subject of considerable scientific interest because of highly nonlinear and unstable behaviors. In this paper, the dynamic model of a maglev transportation system including levitated electromagnets and a propulsive linear induction motor (LIM) based on the concepts of mechanical geometry and motion dynamics is developed first. Then, a model-based sliding-mode control (SMC) strategy is introduced. In order to alleviate chattering phenomena caused by the inappropriate selection of uncertainty bound, a simple bound estimation algorithm is embedded in the SMC strategy to form an adaptive sliding-mode control (ASMC) scheme. However, this estimation algorithm is always a positive value so that tracking errors introduced by any uncertainty will cause the estimated bound increase even to infinity with time. Therefore, it further designs an adaptive fuzzy-neural-network control (AFNNC) scheme by imitating the SMC strategy for the maglev transportation system. In the model-free AFNNC, online learning algorithms are designed to cope with the problem of chattering phenomena caused by the sign action in SMC design, and to ensure the stability of the controlled system without the requirement of auxiliary compensated controllers despite the existence of uncertainties. The outputs of the AFNNC scheme can be directly supplied to the electromagnets and LIM without complicated control transformations for relaxing strict constrains in conventional model-based control methodologies. The effectiveness of the proposed control schemes for the maglev transportation system is verified by numerical simulations, and the superiority of the AFNNC scheme is indicated in comparison with the SMC and ASMC strategies.     

Nonsingular fast terminal sliding‐mode control for nonlinear dynamical systems

This paper investigates fast finite‐time control of nonlinear dynamics using terminal sliding‐mode (TSM) scheme. Some new norms of fast TSM strategies are proposed, and a faster convergence rate is established in comparison with the conventional fast TSM. A novel concept of nonsingular fast TSM, which is able to avoid the possible singularity during the control phase, is adopted in the robust high‐precision control of uncertain nonlinear systems. Numerical simulation on a two‐link rigid robot manipulator demonstrates the effectiveness of the proposed algorithm. Copyright © 2010 John Wiley & Sons, Ltd.     

基于模糊干扰观测器的自适应二阶动态滑模控制

针对一类存在不确定性和外干扰的非线性系统滑模控制的抖振问题,本文首先证明了以高斯函数为隶属度函数的模糊基向量对状态向量的偏导在任意情况下有界,解决了模糊辨识同二阶动态滑模结合的关键问题.然后设计了二阶动态Terminal滑模,有效克服了滑模抖振,且能保证滑模面上的滑动在有限时间内收敛.再基于模糊干扰观测器的输出设计自适应鲁棒补偿项.基于李雅普诺夫理论证明了系统稳定性.最后将本文提出的控制方案用于近空间飞行器姿态角跟踪仿真,并分析了高阶动态滑模收敛时间增加的问题.结果表明本文提出的控制方案跟踪速度快、精度高,且有效去除了抖振.与常规Terminal滑模相比,二阶动态Terminal滑模增加的收敛时间非常有限,适于工程应用.     

全景式航空相机的离散滑模控制

为了提高全景式航空相机镜筒速度控制系统的动态特性,使其具有响应速度快且超调小的特点,本文提出一种基于降维状态观测器的离散滑模控制方法,对镜筒角速度、角加速度进行观测,并对其速度系统进行控制.针对高氏趋近律带来的控制抖振和稳态抖振问题,本文采用幂次函数趋近律的方法,并对这种方法进行了无抖振理论分析以及稳定性证明.最后以某全景式航空相机作为实验平台,将基于幂次函数趋近律的离散滑模控制应用到镜筒速度控制系统中.实验结果表明,本文提出的控制方法能够有效地减小系统的抖振,使镜筒速度控制系统表现出良好的动态品质.     

SECOND‐ORDER TERMINAL SLIDING MODE CONTROL OF INPUT‐DELAY SYSTEMS

This paper proposes a second‐order terminal sliding mode control for a class of uncertain input‐delay systems. The input‐delay systems are firstly converted into the input‐delay free systems and further converted into the regular forms. A linear sliding mode manifold is predesigned to represent the ideal dynamics of the system. Another terminal sliding mode manifold surface is presented to drive the linear sliding mode to reach zeros in finite time. In order to eliminate the chattering phenomena, a second‐order sliding mode method is utilized to filter the high frequency switching control signal. The uncertainties of the systems are analysed in detail to show the effect to the systems. The simulation results validate the method presented in the paper.