一类不确定非线性系统的改进积分型滑模控制

针对一类不确定非线性系统的传统滑模控制,推导了滑模误差和稳态误差的范围．为了减小系统的稳态误差,同时防止积分饱和,设计了一种改进积分型滑模面．在边界层外,通过调节因子对积分项进行削弱,以防止在初始误差较大的条件下积分饱和引起的超调较大和调节时间较长的问题;在边界层内,采用传统积分以减小系统稳态误差．理论分析和仿真研究表明了所提改进积分型滑模控制方法的有效性．

     

一种改进积分滑模面在飞控中的应用

针对传统积分型滑模面容易产生积分饱和从而导致超调量大的缺点,在seshagin和Khalil设计的条件积分型滑模面的基础上,提出了一种改进积分型滑模面,其可以根据系统的状态通过调节因子对积分项进行削弱来防止积分饱和.同时对调节因子的取值范围进行了讨论.并将改进积分型滑模面应用到导弹的俯仰角速度跟踪滑模控制器设计中,对舵机输出受到干扰的情况进行了仿真.理论分析和仿真研究表明,改进积分型滑模面形式简单,便于工程实现,在其基础上设计的滑模控制器在受到类似脉冲干扰的情况下几乎没有超调和具有较短的调节时间.     

非线性积分滑模控制方法

针对一类不确定非线性系统的滑模控制,提出了一类具有"小误差放大,大误差饱和"功能的光滑非线性饱和函数来改进传统的积分滑模控制,以形成非线性积分滑模控制.在保持传统积分滑模控制跟踪精度的同时获得更好的暂态性能.应用Lyapunov稳定性理论和LaSalle不变性原理证明了对最终常值干扰可以完全抑制.考虑控制受限时,所设计...     

限定初始状态非线性取代积分滑模算法的研究

针对常规滑模控制算法抑制抖振的边界层方法存在稳态误差的缺点,考虑在常规滑膜面基础上加一个跟踪误差的积分项,这就是常规积分滑膜控制器。积分项的引入虽然可以减少稳态误差,补偿模型的不确定性,但是在大的初始误差条件下,大的超调和长的调节时间会使系统的暂态性能恶化甚至可能出现积分windup效应导致整个系统的不稳定,同时为了克服常规滑模控制在到达阶段不具有鲁棒性的缺点,又设计了限定初始状态非线性取代积分滑模控制器。通过仿真结果可以看出这种滑模控制器不但能够较好地削弱稳态误差和抑制抖振,而且也具有较好的鲁棒性。     

非线性系统的改进型自适应积分控制算法

针对传统非线性系统的积分控制,为减小稳态跟踪误差和防止积分饱和,设计了一种改进型的自适应积分控制。采用反馈线性化消去系统的非线性,在初始误差较大的条件下,引入惩罚函数根据误差动态调节比例系数和积分系数可抑制较大的超调量。应用Lyapunov稳定性理论,证明了在外部扰动有界的条件下,闭环控制系统一致最终有界。闭环系统稳定性的理论分析和仿真结果都验证了上述策略的可行性。     

一类非线性系统准滑模控制的稳态误差分析

针对一类具有未知控制增益的不确定非线性系统准滑模跟踪控制,通过分析跟踪误差和滑模变量之间的关系,利用有界输入有界输出稳定的思想,分别推导了采用Slotine形式的传统滑模面和传统积分滑模面时系统的稳态跟踪误差的界.将其与现有的几种方法进行比较,该方法求得的稳态跟踪误差界更精确.根据给定的稳态跟踪误差要求,可设计出适合抑制抖振的饱和函数.通过仿真算例验证了所提出方法的有效性.     

一类非线性变结构系统减小稳态误差的方法

本文分析了系统的稳态误差与滑模平面斜率的关系，推导出其数学表达式，在此基础上，提出了一种改进的滑模平面设计方法，用以减小系统的稳态误差，该方法与饱和特性平滑策略结合起来，可以使系统既能满足稳态误差的要求，又能满足平滑变结构系统指挥量的要求，最后的仿真结果证明了该方法的可行性。     

一种改进的AUVs变结构滑模控制策略研究

针对现有的变结构滑模控制切换面单一性会导致系统状态在原点处收敛缓慢的缺陷,对自主式水下机器人(AUVs)变结构滑模控制设计了折线型的切换面,并且进一步改进实现了速度控制和定点定速控制;改进的切换面由斜率不同的自线段构成,并在拐点处通过S型函数光滑过渡;将切换面的斜率减小到0时,则可以实现速度控制,同时为了消除速度控制的稳态误差,引进了采用能智积分方法的积分项;最后在某AUV上进行仿真实验,结果证实了应用折线型切换面可以减少控制系统的上升时间,提高反应速度;速度控制的稳态误差接近0,并很好地实现定点定速的控制效果.该方法可以有效用于AUVs的控制.     

基于比例积分微分的电机滑模变结构同步控制

针对电机滑模变结构同步控制存在超调量较大、调节耗时长、导致滑模变结构脉动过大的问题,提出基于比例积分微分的电机滑模变结构控制方法.根据电机的物理模型与负载模型,获取PID控制器传递函数,并分析影响控制性能的参数;在积分增益、微分增益基础上改进PID,结合抗积分饱和算法,改善误差反应速度和灵敏度,确定最后P控制方式.仿真结果证明,所提方法的超调量较小,调节耗时短,可以较好控制电机的滑模变结构波动,滑模变结构的脉动较小,响应速度得到提高,有望更好地实现对电机滑模变结构的同步控制.     

采用双滑模平面减小一类非线性系统稳态误差

分析了系统的稳态误差与滑模平面斜率的关系,推导出其数学表达式,在此基础上,提出了改进的滑模平面设计方法。该方法与饱和特性平滑策略相结合可使系统既能满足稳态误差的要求,又能满足平滑控制量的要求。仿真结果证明了该方法的可行性。     

一种基于指数趋近律的非线性系统变结构轨迹跟踪控制新方法

针对多输入多输出二阶不确定非线性机械系统中轨迹跟踪控制的问题,提出一种新的基于指数趋近律的滑模变结构控制方法,用于提高系统的平稳性和快速性。在滑模变结构控制器设计过程中采用一种新的指数趋近律以改进闭环系统的暂态和稳态响应性能,使系统跟踪误差收敛速度加快,特别是减少轨迹跟踪误差到达滑模面的时间,同时提高了系统轨迹跟踪过程的平稳性。通过采用边界层方法消除滑模控制输入抖振问题,避免控制过程中执行器的频繁切换,进一步提高所提出滑模控制器在实际系统中的实用性。基于李雅普诺夫稳定性理论证明了闭环系统的稳定性和跟踪误差的收敛性。数值仿真验证了所提出的控制方法的有效性。     

Coordinating optimization-based sliding mode variable structure control for electro-hydraulic servo system

A sliding mode variable structure control （SMVSC） based on a coordinating optimization algorithm has been developed. Steady state error and control switching frequency are used to constitute the system performance indexes in the coordinating optimization, while the tuning rate of boundary layer width （BLW） is employed as the optimization parameter. Based on the mathematical relationship between the BLW and steady-state error, an optimized BLW tuning rate is added to the nonlinear control term of SMVSC. Simulation experiment results applied to the positioning control of an electro-hydraulic servo system show the comprehensive superiority in dynamical and static state performance by using the proposed controller is better than that by using SMVSC without optimized BLW tuning rate. This succeeds in coordinately considering both chattering reduction and high-precision control realization in SMVSC.     

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     

Coordinating optimization-based sliding mode variable structure control for electro-hydraulic servo system

A sliding mode variable structure control (SMVSC) based on a coordinating optimization algorithm has been developed. Steady state error and control switching frequency are used to constitute the system performance indexes in the coordinating optimization, while the tuning rate of boundary layer width (BLW) is employed as the optimization parameter. Based on the mathematical relationship between the BLW and steady-state error, an optimized BLW tuning rate is added to the nonlinear control term of SMVSC. Simulation experiment results applied to the positioning control of an electro-hydraulic servo system show the comprehensive superiority in dynamical and static state performance by using the proposed controller is better than that by using SMVSC without optimized BLW tuning rate. This succeeds in coordinately considering both chattering reduction and high-precision control realization in SMVSC.     

非匹配不确定系统的自适应反演准滑模控制

对于一类n阶非线性系统,提出一种自适应反演准滑模控制方法,控制的前n-1步采用自适应反演算法消除非匹配不确定性的影响,在最后一步,为改进跟踪效果,结合了可变边界层的思想,设计了准滑模控制方法,达到系统的n个状态快速收敛的目的.最终系统中不满足匹配条件的部分也具有较好的鲁棒性.与自适应反演线性滑模方法相比具有更好的跟踪性,理论分析证明了控制系统在削弱抖振的同时也能保证稳态精度,仿真实验证明了该方法的可行性.     

Existence of solutions to a class of nonlinear convergentchattering-free sliding mode control systems

Sliding mode control is a nonlinear control technique, which is robust against some classes of uncertainties and disturbances. However, this control produces chattering which can cause instability due to unmodeled dynamics and can also cause damage to actuators or the plant. There are essentially two ways to counter the chattering phenomenon. One way is to use higher order sliding mode, and the other way is to add a boundary layer around the switching surface and use continuous control inside the boundary. The problem with the first method is that the derivative of a certain state variable is not available for measurement, and therefore methods have to be used to observe that variable. In the second method, it is important that the trajectories inside the boundary layer do not try to come outside the boundary after entering the boundary layer. Control laws producing chattering-free sliding mode using a boundary layer have been proposed and the existence of solutions to the system using these control laws are presented     

采用幂次趋近律的滑模控制稳态误差界

对一类不确定非线性系统采用幂次趋近律的滑模跟踪控制,分别推导了采用Slotine形式的传统滑模面和积分滑模面时的稳态跟踪误差的界.首先,基于Lyapunov方法求出了滑模误差的最终界和系统不确定性、幂次趋近律参数之间定量的数学关系.其次,利用有界输入有界输出稳定的方法,分别求出了采用Slotine形式的传统滑模面和积分...     

基于量子遗传算法的模糊滑模控制

针对一类具有不确定性的非线性系统,提出了一种新的基于量子遗传算法的模糊滑模控制器的设计方法.将模糊控制与滑模控制相结合,利用滑模控制使系统跟踪误差进入边界层内;启用模糊控制替代切换控制,并在边界层上通过监督函数平滑控制作用.在滑动模态产生条件下,通过量子遗传算法优化模糊控制器的控制规则,有效地解决了模糊滑模控制中模糊控制规则的确定问题,从而削弱了系统的抖振,改善了控制器的控制性能.仿真结果表明了该方法的有效性.     

An LTR-observer-based dynamic sliding mode control for chattering reduction

Two important approaches to alleviation of control chattering in sliding mode control are the boundary layer control (BLC) and the dynamic sliding mode control (DSMC). The DSMC is superior to the BLC since in DSMC chattering is alleviated without sacrificing the control accuracy. However, the design of DSMC is more challenging because its sliding variable contains an unknown system uncertainty. This paper proposes a robust two-dimensional LTR observer for estimation of the state-dependent uncertainty in the sliding variable. This paper also shows, via simulation examples, that the DSMC can better reduce chattering than the BLC especially in noisy environments.