非匹配不确定系统的滑模控制及在电机控制中的应用

针对具有匹配与非匹配不确定的非线性系统,设计基于干扰观测器和多幂次趋近律的滑模控制策略.首先,通过干扰观测器估计系统的不确定,实现估计误差在有限时间内收敛;其次,基于积分型滑模面,并结合多幂次趋近律,设计了连续滑模控制律,避免了传统滑模的抖振问题.与基于单幂次和双幂次趋近律的滑模控制策略相比,所设计的基于多幂次趋近律的控制策略,提高了系统的收敛速度.最后,通过数值仿真和永磁同步电机控制仿真验证了所设计的控制策略的有效性.     

一类不确定离散Markov 跳变系统滑模状态反馈控制

针对具有不确定的离散Markov跳变系统,研究其滑模状态反馈控制问题.考虑系统的不确定满足匹配条件,以线性矩阵不等式形式给出了离散滑模面存在的充分条件,设计了具有指数趋近律的滑模控制器,保证了系统状态到达滑模面并在滑模带上随机镇定.数值仿真验证了所提出的控制方案的有效性.     

基于预见与PI补偿的不确定非线性系统鲁棒滑模控制

针对一类匹配不确定非线性连续时间系统,本文提出一种具有预见与PI补偿的鲁棒滑模控制设计方法.首先,为提高系统的跟踪性能和鲁棒性,在常规的滑模控制基础上,引入前馈预见与PI控制器.然后,通过增加扩展系统状态变量方法,构造一个包含可预见的目标信号的不确定增广系统,并将控制器的设计问题转化为增广系统的稳定性问题.在此基础上,针对标称增广系统,应用最优控制原理,设计最优预见PI控制器;针对不确定增广系统,应用变结构控制方法,设计最优预见PI滑模控制器,实现不确定系统的鲁棒调节.所得结果推广和包含了已有文献中的一些结果.最后,数值仿真验证所提方法的有效性.     

带有不匹配干扰的多智能体系统有限时间积分滑模控制

针对动态多智能体系统协同控制问题，本文研究了带有不匹配干扰的二阶多智能体系统的有限时间包容控制，提出了基于非线性积分滑模控制（Integral sliding-mode control，ISMC）的复合分布式包容控制算法.首先利用Lyapunov稳定性和齐次性定理，分析了未受扰系统的有限时间包容控制问题；然后针对存在不匹配干扰的多智能体动态系统，设计非线性有限时间干扰观测器估算智能体的状态和干扰，提出基于干扰观测器的复合分布式积分滑模控制协议，结合现代控制理论和滑模控制理论，研究了带有不匹配干扰的多智能体系统有限时间包容控制问题.最后数值仿真证明了控制算法的有效性.     

非匹配不确定高阶非线性系统递阶Terminal滑模控制

对于高阶非线性系统,首先采用改进的高阶滑模微分器作为间接干扰观测器,获得前n-1个子系统中的非匹配复合干扰的估计值,证明了估计误差可任意小. 为避免代数环,设计了三种方案获得最后一个子系统中非匹配复合干扰的估计值,并证明了估计误差有界. 在此基础上设计递阶Terminal滑模控制器,证明了控制器参数非奇异及结构非奇异,并给出所需条件. 最后,证明了系统稳定,跟踪误差可任意小. 近空间飞行器姿态控制仿真验证了本文结论.     

一类非线性不确定系统的自适应积分滑模控制

针对一类具有不确定参数的复杂非线性系统,提出了一种自适应积分滑模控制方法。控制器的设计分两步进行：首先,基于被控对象模型构造一个简化子系统,设计出该子系统的一个全局渐近稳定控制律;然后构造一个积分滑模面,设计自适应积分滑模补偿器以处理系统中含有不确定参数的部分,保证了滑模面的可达性和原系统的闭环稳定性。补偿后,系统的完整自适应控制律由简化子系统的控制律加补偿控制器两部分组成。所提设计方法简单,便于工程实现。最后,通过仿真结果验证了设计方案的有效性。     

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.     

含有非线性不确定参数的电液系统滑模自适应控制

针对含有非线性不确定参数的电液控制系统, 提出了一种滑模自适应控制方法. 该控制方法主要是为了解决由于初始控制容积的不确定性而引起的, 非线性不确定参数自适应律设计的难题. 其主要特点为, 通过定义一个新型的特Lyapunov 函数, 进而构建系统的自适应控制器及参数自适应律, 并结合滑模控制方法及一种简单的鲁棒设计方法, 给出整个电液系统的滑模自适应控制器, 及所有不确定参数的自适应律. 试验结果表明, 采用该控制方法能够取得良好的性能, 尤其可以补偿非线性不确定参数对系统的影响.     

Buck变换器的改进型互补滑模控制

针对Buck变换器系统中存在匹配和不匹配干扰的问题, 本文提出了一种基于干扰观测器(DOB)的改进型互补滑模控制(CSMC)策略. 首先, 建立存在多重干扰的Buck变换器数学模型, 将模型改写为标准二阶积分型控制对象, 将式中干扰统一为匹配干扰和不匹配干扰. 其次, 设计2个DOB分别估计匹配干扰和不匹配干扰, 实现有限时间内跟踪干扰信号, 以抵消各种不确定性对系统的影响. 然后, 设计互补滑模面, 提出基于等效控制的改进型互补滑模控制律, 保留边界层内鲁棒性的同时, 提升控制器的动态性能, 减小静态误差, 拓宽边界层参数选择范围. 最后, 基于李雅普诺夫理论证明所提出控制器的稳定性. 数字仿真表明, 提出的改进型CSMC控制器结合DOB的总体控制方案能够有效抑制系统匹配和不匹配干扰, 同时获得更快的收敛速度以及更高的跟踪精度.     

非匹配不确定离散系统的无抖振积分滑模控制

针对一类非匹配不确定离散系统, 设计一种无抖振离散积分滑模控制器. 为了抑制非匹配不确定性对系统的影响, 采用线性矩阵不等式方法设计一种新型的切换函数和对应的滑模控制律, 并证明了闭环系统的Lyapunov 稳定性. 同时, 引入饱和函数设计控制器, 使系统状态在积分滑模面的某个小邻域内做准滑模运动, 并通过合理选择饱和函数的边界层厚度, 使控制信号不含任何抖振. 理论分析和数值仿真验证了所提出方法的有效性.

     

Nonlinear integral-type sliding surface for both matched and unmatched uncertain systems

This note presents a new nonlinear integral-type sliding surface which incorporates a virtual nonlinear nominal control to achieve prescribed specifications. First, the plant with matched uncertainties is considered. The resultant closed-loop system during ideal sliding mode behaves exactly like the nominal plant under the nonlinear nominal control, which completely ifies the matched uncertainties and consequently satisfies the prescribed specifications. Second, the stability analysis of the proposed sliding mode for the systems with unmatched uncertainties is performed to exploit the stability conditions. Numerical results demonstrate the validity of the proposed concept.     

Integral Sliding Mode Fault‐Tolerant Control for Spacecraft With Uncertainties and Saturation

An integral sliding mode fault‐tolerant control method is proposed to deal with faults with matched uncertainties, unmatched uncertainties, and input saturation. Integral sliding mode, control allocation, and parameter identification are included in this method. The Lyapunov stability conditions of the integral sliding mode control for uncertainties and input saturation, respectively, are obtained, which denote the robustness extent of the controller. The direct method for control allocation is improved by adding a judgement before calculating for each facet. Finally, the fault‐tolerant scheme is applied to a six‐wheel spacecraft and simulations are given to show its effectiveness.     

Mini-max integral sliding-mode control for multimodel linear uncertain systems

An original linear time-varying system with matched and unmatched disturbances and uncertainties is replaced by a finite set of dynamic models such that each one describes a particular uncertain case including exact realizations of possible dynamic equations as well as external unmatched bounded disturbances. Such a tradeoff between an original uncertain linear time varying dynamic system and a corresponding higher order multimodel system containing only matched uncertainties leads to a linear multi-model system with known unmatched bounded disturbances and unknown matched disturbances as well. Each model from a given finite set is characterized by a quadratic performance index. The developed minimax integral sliding mode control strategy gives an optimal minimax linear quadratic (LQ)-control with additional integral sliding mode term. The design of this controller is reduced to a solution of an equivalent mini-max LQ problem that corresponds to the weighted performance indices with weights from a finite dimensional simplex. The additional integral sliding mode controller part completely dismisses the influence of matched uncertainties from the initial time instant. Two numerical examples illustrate this study.     

Robust stabilization of a class of uncertain system via block decomposition and VSC

In this paper, a block decomposition procedure for sliding mode control of a class of nonlinear systems with matched and unmatched uncertainties, is proposed. Based on the nonlinear block control principle, a sliding manifold design problem is divided into a number of sub‐problems of lower dimension which can be solved independently. As a result, the nominal parts of the sliding mode dynamics is linearized. A discontinuous feedback is then used to compensate the matched uncertainty. Finally, a step‐by‐step Lyapunov technique and a high gain approach is applied to obtain hierarchical fast motions on the sliding manifolds and to achieve the robustness property of the closed‐loop system motion with respect to unmatched uncertainty. Copyright © 2002 John Wiley & Sons, Ltd.     

Unmatched uncertainties compensation based on high‐order sliding mode observation

The problem of compensation of the effects of unmatched uncertainties ∕ perturbations is considered. High‐order sliding mode observers are employed for exact state and uncertainties ∕ perturbations reconstruction. A sliding mode control design is proposed ensuring theoretically exact compensation of the uncertainties ∕ perturbations for the corresponding unmatched states based on the identified perturbation values. An inverted pendulum simulation example is considered illustrating the feasibility of the proposed approach.Copyright © 2012 John Wiley & Sons, Ltd.     

A New Adaptive Sliding Mode Control of Uncertain Nonlinear Systems

In this paper, a new adaptive sliding mode control is proposed to control nonlinear systems with parametric uncertainties and matched and unmatched external disturbances. The proposed method first combines immersion and invariance (I&I) adaptive scheme with sliding mode control (SMC), which preserves the advantages of the two methods. The proposed method is different from the approach of combining the backstepping adaptive scheme and sliding mode control in the parameter estimation law, which allows for prescribed dynamics to be assigned to the estimation error and is easier to tune. Finally, the method is applied to control a class of power systems, and simulation results show the advantages of the proposed method.     

Decomposition of the min–max multi‐model problem via integral sliding mode

The concept of the integral sliding mode (ISM) is revised and applied for robustification of a linear time invariant min–max multi‐model problem with uncertainties. Modified version of ISM ensures the insensitivity of the designed min–max control law with respect to matched uncertainty, starting from the beginning of the process, and guarantees that the unmatched part of uncertainties is minimized and not amplified. Proposed ISM dynamics allows to reduce the dimension [Nn] of the min–max control design problem to the space of unmatched uncertainties only of [Nn?(N?1)m] size. A numerical example illustrates that the suggested modification of the ISM dynamics does not change the min–max control as well as the value of the corresponding performance index. Copyright © 2005 John Wiley & Sons, Ltd.     

一类不确定离散时间系统的积分滑模控制

针对一类同时存在匹配和非匹配不确定性的离散时间系统,提出一种基于幂次函数的离散积分滑模控制方法.理论分析表明,所提出的方法可以消除离散积分滑模控制系统的抖振,而且能够保证对系统的匹配和非匹配不确定性具有强鲁棒性.在系统不确定性的界未知的情况下,通过引入一步延时干扰估计完成了控制器的设计,并给出了闭环系统稳定性证明.仿真结果验证了所提出方法的有效性.     

Integral Sliding‐Mode Observation and Control for Switched Uncertain Linear Time Invariant Systems: a Robustifying Strategy

A robustifying methodology for switched systems with matched and unmatched uncertainties/perturbations and autonomous location transitions is presented. We avail of such methodology to design a control strategy based on integral sliding modes, thereby ensuring theoretically exact compensation of the matched uncertainties/perturbations and the minimization of the effects of the unmatched ones. An output integral sliding‐mode control technique, based on a switched algebraic hierarchical observer is also proposed. This approach allows the theoretically exact compensation of the matched uncertainties/perturbations right after the first moment. The proposed approach is illustrated via numerical simulations.     

Dynamic output feedback sliding mode design for a class of linear unmatched uncertain systems

This paper investigates the output feedback stabilization problem for a class of multi-input/multi-output (MIMO) systems with matched/unmatched uncertainties by the variable structure system (VSS) with a new sliding mode control. In dynamic systems, a new idea of a sliding sector that consists of two sets of switching surfaces is proposed. A new invariance condition is derived such that the reduced-order system in the new sliding mode is completely invariant to both matched and unmatched uncertainties. Additionally, to demonstrate the effectiveness of the proposed scheme and to reduce the drawbacks of conventional VSS design, a modified dynamic variable structure controller using only the output variables is applied to perform the sliding mode. Furthermore, a stability analysis of the overall system is also provided. Finally, an example is given to illustrate the effectiveness of the control scheme.