On adaptive sliding mode control without switching gain overestimation

This paper presents some further results on adaptive sliding mode control (ASMC) for a class of nonlinear systems with bounded uncertain parameters. Given a large initial tracking error, current ASMC design generally produces an unnecessarily large switching gain, consequently leading to a serious chattering problem or a large‐amplitude control jump for the continuous counterpart. To solve such an overadaptation problem, the switching gain adaptation mechanism is first analyzed in this paper, and the adaptation induced by the initial tracking error is suggested to be removed. Then, by exploiting the global sliding mode feature of time‐varying sliding mode control and integral sliding mode control, we present two effective methodologies for ASMC design. The proposed ASMC algorithms ensure that there is no overestimation of the switching gain and the system response is not slowed down when a small switching gain is generated. The validity of the proposed methods is verified by both theoretical analysis and simulation results. Copyright © 2012 John Wiley & Sons, Ltd.     

永磁直线电机自适应区间二型模糊滑模控制

针对永磁直线同步电机伺服系统受到系统参数变化、负载扰动而降低其性能的问题,考虑端部效应以及摩擦力的存在,提出一种自适应区间二型模糊滑模控制方法.采用自适应区间二型模糊系统逼近滑模控制等效控制部分,把传统的一型模糊系统扩展到区间二型模糊系统,提高系统面临参数变化、不确定性扰动时的处理能力.基于Lyapunov函数设计切换项增益调整的自适应律,保证系统的稳定性.仿真结果表明,该方法提高了系统的鲁棒性,有效地削弱了系统的抖振.     

滑模变结构控制的抖振问题研究

文章在分析变结构控制（VSC）系统抖振发生机理基础上，讨论了几种消除或削弱抖振的途径。提出了一种类似于模糊推理的VSC方法，并给出了在加工过程控制中的应用实例，仿真结果表明，该方法能够有效地削弱系统抖振，而不会影响控制器的鲁棒性能。     

Chattering reduction of sliding mode control by low‐pass filtering the control signal

The conventional approach to reducing control signal chattering in sliding mode control is to use the boundary layer design. However, when there is high‐level measurement noise, the boundary layer design becomes ineffective in chattering reduction. This paper, therefore, proposes a new design for chattering reduction by low‐pass filtering the control signal. The new design is non‐trivial since it requires estimation of the sliding variable via a disturbance estimator. The new sliding mode control has the same performance as the boundary layer design in noise‐free environments, and outperforms the boundary layer design in noisy environments. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

集成神经网络与自适应算法的分数阶滑模控制

针对被控对象的参数时变和外部扰动问题,本文融合神经网络的万能逼近能力和自适应控制技术,并结合分数阶微积分理论,提出了基于神经网络和自适应控制算法的分数阶滑模控制策略.本文采用等效控制的方法设计滑模控制律,并利用神经网络的万能逼近能力估测控制律的变化,结合自适应控制算法和分数阶微积分理论抑制传统滑模控制系统的抖震,同时根据Lyapunov稳定性理论分析了系统的稳定性,最后给出了实验结果.实验结果表明,本文提出的基于神经网络和自适应控制算法的分数阶滑模控制系统,能保持滑模控制器对系统外部扰动和参数变化鲁棒性的同时,也能有效地抑制抖震,使得系统获得较高的控制性能.     

高阶滑模微分器的分析与改进

首先采用Terminal吸引子函数代替原不连续函数,以避免滑模微分器的抖振;然后针对现有文献中高阶滑模微分器设计参数选取苛刻这一问题,放宽了设计参数选择范围,并分不同情况证明了高阶滑模微分器的稳定性．在此基础上,给出了高阶滑模微分器估计误差的上界与设计参数和滑模微分器阶次的关系式;通过对设计参数的选取和系统整体结构的分析,提出了高阶滑模微分器减小估计误差且更适于工程应用的设计方法,并给出所需条件．仿真结果表明了所得结论的正确性和有效性．     

一种积分型切换函数的滑模控制算法在倒立摆系统中的仿真应用

针对实际控制系统的非线性和某种程度上存在扰动的特点,采用基于积分切换函数的滑模变结构控制算法不仅能减小由于扰动带来的稳态误差,同时对抑制抖振现象有很好的效果。另一方面为了使系统能够快速到达切换面,在指数趋近律的基础上增加变速部分保证整个趋近过程用时很短。将此算法应用到一级倒立摆系统中进行仿真验证,仿真结果显示了此算法克服抖振的效果。     

FREQUENCY DOMAIN ANALYSIS OF FAST AND SLOW MOTIONS IN SLIDING MODES

A frequency domain approach to analysis of fast and slow motions in sliding modes is proposed in the paper. The proposed approach is based on the construction of a relay system that is equivalent to the original sliding mode control system and on the application of the locus of a perturbed relay system method. A precise model of the fast motions and a non‐reduced order model of the slow motions for the SISO linear time‐invariant case are obtained as a result of the proposed approach.     

基于切换函数超前补偿的滑模变结构控制

本文分析了计算机滑模变结构控制系统采样周期和计算时间的存在所导致的颤振现象，提出了一种削弱其颤振幅值的方法——切换函数超前补偿法。理论分析和仿真结果均表明了这种方法的有效性和可行性。     

采用鲁棒微分器的永磁直线同步电机二阶滑模控制

针对永磁直线同步电机伺服系统容易受到参数变化、端部效应和负载扰动等不确定性因素影响的问题，采用二阶滑模控制中的螺旋算法设计直线伺服系统的速度和电流控制器。在出现参数变化和阻力扰动时，为保证动子速度严格跟踪其参考信号，同时消除磁阻作用和推力波动的影响，分别独立选取速度和直轴电流的滑模量，并利用基于二阶滑模的鲁棒速度微分器来估计螺旋算法所需要的加速度信号。仿真结果表明该策略对负载和参数的变化具有很强的鲁棒性，同时有效地削弱了抖振现象。