基于离散时变趋近律的准滑模控制

针对不确定离散时间系统,提出一种基于离散时变趋近律的准滑模控制方法.该方法不仅能够加快系统趋近模态的趋近速度,缩短到达时间,而且能够减小准滑动模态带宽,有效改善系统动态品质,增强系统鲁棒性,并无控制抖振和稳态抖振产生.控制律形式简单、利于实现.仿真结果表明了所提出方法的有效性.     

基于粒子群算法改进SVM的滑模控制研究

为了提高离散时间系统的控制品质以及削弱系统抖振,提出了基于粒子群算法(particle swarm optimization,PSO)改进支持向量机(support vector machine,SVM)的滑模控制方法并进行了仿真研究;通过SVM识辨参量模型与PSO寻优处理,获得趋于理想滑模运动的趋近律参数,确保寻优处理时间短、精度高;利用PSO和SVM在线调整滑模趋近律参数,可以克服常规滑模控制中需要事先设定趋近律参数限制的弊端,加快跟踪速度,削弱系统抖振,完善控制质量;仿真实验表明,该方法可以克服因PSO寻优过程中的寻优时间过长等不足,又可解决SVM精度不高或计算量大的缺点;该方法用于离散时间系统是可行、有效的,工程实用性强。     

基于扰动补偿趋近律的准滑模控制

针对不确定离散时间系统,提出了一种基于扰动补偿趋近律的准滑模控制方法.该方法不仅能够加快系统趋近模态的趋近速度,缩短到达时间,而且能够缩窄系统的准滑动模态带宽,增强系统鲁棒性,有效改善系统动态品质,并无控制抖振和稳态抖振产生.仿真结果表明了该方法的有效性.     

基于干扰补偿趋近律的离散滑模多周期重复控制

针对离散时间系统的多周期干扰抑制问题,提出一种离散滑模多周期重复控制器设计方法.利用非线性幂次函数设计新型离散趋近律,将周期差分等效干扰以加权形式嵌入到趋近律中,构造带干扰补偿作用的离散趋近律,并据此设计离散滑模多周期重复控制器.为了进行控制器参数整定和表征闭环系统的收敛性能,推导准滑模域边界层的表达式.所提出控制方法既能够消除多周期干扰信号,也能够减小准滑模域边界层.数值仿真验证了所提出控制方法的有效性.     

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。     

基于频域辨识模型的新型幂次趋近律滑模控制

针对刚柔耦合系统传统理论建模过程复杂、模型不准确问题,采用频域子空间方法来辨识实验系统中的电机模型和压电片模型。同时针对传统趋近律的到达时间较长以及抖振问题,提出一种新型幂次趋近律的滑模控制。理论分析表明在不影响抖振情况下可缩短到达时间和扩大传统幂次趋近律参数α的范围。考虑柔性梁振动特性对系统性能的影响,采用子滑模面的方法来设计滑模控制器。最终,实验结果表明所设计控制器能够实现对中心刚体角度的快速跟踪,并且能够快速抑制柔性梁的振动。     

一种离散变结构控制趋近律

提出一种符合高氏6个特点的离散变结构控制的趋近律.应用该趋近律设计的变结构控制系统,可保证系统在有限步到达准滑模带,系统运动最终趋于原点,并有降低抖动及保持快速趋近的品质.仿真结果说明了该方法的可行性和有效性.     

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...     

一种离散全程滑模变结构控制方法

针对离散时间系统提出了一种全程滑模变结构控制器设计方法。通过选择合适的滑模切换函数，使系统的轨线一开始便落在滑模面上，有效地缩短了系统状态到达滑动模态的时间，使系统从初始状态到平衡点的全过程都具有鲁棒性。针对利用离散趋近律方法设计全程滑模变结构控制器系统存在抖振的缺点，本文利用常规等效控制方法设计离散全程滑模变结构控制器，消除了系统的抖振，改善了系统的动态性能。并基于倒立摆模型进行了仿真，结果验证了其有效性。     

不确定离散时间系统的复合非线性反馈积分滑模控制

针对不确定离散时间系统,提出一种基于离散复合非线性反馈的积分滑模(DCNF-ISM)控制策略,并将该算法应用于扰动下的磁盘跟踪问题.该算法由离散复合非线性反馈(DCNF)控制律与积分滑模(ISM)控制律两部分组成,其中DCNF控制律用于保证系统具有较好瞬态性能,基于改进的离散趋近律设计的ISM控制律用于保证系统鲁棒性.基于Lyapunov稳定性理论对本文提出的控制策略的稳定性进行了推导证明,证明了离散时间系统的一致最终有界性.仿真结果表明,本文提出的控制策略能保证系统在扰动下仍然能够精确跟踪给定的参考信号,与传统的DCNF控制相比,该算法能够保证系统具有响应速度快超调量小、鲁棒性强等优点.     

Arbitrary settling time control with prescribed performance for high-order nonlinear systems

This paper studies an arbitrary convergence time tracking controller design problem for high-order nonlinear systems. Our aim is to enhance the existing free-will arbitrary time control (FATC), which cannot track time-varying reference signals. To do so, a new nonautonomous equation is firstly introduced to enable an arbitrary settling time stability for one-order systems. Then, a prescribed performance control (PPC) technology is integrated for general high order systems. By a backstepping Lyapunov analysis with iteratively contructed nonautonomous equations, it is proved that the closed-loop system satisfies the prescribed performance and all signals of the closed-loop system are arbitrary settling time stable (ASTS). Compared with the existing results, the tracking control problem with arbitrary convergence time is addressed by a continuous control law, which shows a better transient performance also. Simulation results confirm the effectiveness of the proposed control method.     

Fast sliding-mode seek control of hard disk servos

A nonlinear controller is presented for both seeking control and following control in hard disk servos. Usually, a switching mechanism is used for mode transit from seeking to following. As a result, the seeking time and settling time are lengthened very much, especially for short seeks. Based on time-varying sliding surfaces, the proposed nonlinear control approach eliminates the switching mechanism and thus realizes the smooth mode transit. Its effectiveness is demonstrated in simulation and experiments. In particular, the seek time is improved up to 50%.Paper presented at the 13th Annual Symposium on Information Storage and Processing Systems, Santa Clara, CA, USA, 17–18 June, 2002     

永磁同步电动机高动态响应电流控制

永磁同步电动机系统广泛采用矢量控制策略实现转矩控制,电流控制环是其核心部分.电流环一般采用PI型控制,但PI型电流控制动态响应动态特性受到制约,参数整定必须在超调量及响应时间等指标之间折衷选择.为了改进PI型电流控制的动态响应性能,在输入误差较大时,采用滑模变结构控制,输入误差较小时,切换到PI型电流控制.结合滑模变结构和PI型电流控制,可以充分利用滑模变结构控制动态响应快,以及PI型电流控制无稳态误差的特点,并能解决滑模变结构控制的抖颤问题.实验结果表明该电流控制方法响应时间短而且超调量小,同时获得良好的动态响应和控制精度.     

最小能量有限拍鲁棒控制系统的设计

本文采用2自由度控制器,以传递函数分式分解理论为基础,提出了一种在保证系统内部稳定和最佳鲁棒性前提下,实现最小能量控制的有限拍系统设计法。设计过程本质上是控制能量与响应时间的折衷。本文导出了折衷的最终界限,并给出了确定最佳响应时间的方法。     

Radial Pole Paths SVSC for Linear Time Invariant Multi Input Systems with Constrained Inputs

In this article a novel soft variable structure control method is proposed to reduce the settling time of liner time‐invariant multi‐input systems with constrained inputs. The method is a generalized pole placement technique which extends the desired pole locations to radial pole paths to reduce settling time while satisfying input constraints. The control signal obtained by this method is soft and is therefore suited to industrial applications. The paper provides a test for the stability of the control system based on the multivariable circle criterion and the Kalman‐Yakubovich‐Popov lemma. Simulation results where the method is applied to an aviation example, and comparison with pole placement, demonstrate how the method significantly increases the speed of response in spite of the input constraints.     

Command Filtered Finite/Fixed-time Heading Tracking Control of Surface Vehicles

This paper investigates the heading tracking problem of surface vehicles with unknown model parameters. Based on finite/fixed-time control theories and in the context of command filtered control, two novel adaptive control laws are developed by which the vehicle can track the desired heading within settling time with all signals of the closed-loop system are uniformly bounded. The effectiveness and performance of the schemes are demonstrated by simulations and comparison studies.      

A pivot nonlinearity compensation by use of variable structure estimator for hard disk drives

This paper discusses robust seeking control of hard disk drives by the use of a variable structure multi-rate estimator (VSME). Compensation of pivot nonlinearity is one concern in the design of the seeking control, systems. Pivot nonlinearity is subject to uncertainties, and is difficult to deal with by a linear controller. The VSME estimates a class of uncertain disturbances and nonlinearities and yields compensation current through the linear feedback gain, which reduces the residual vibration and error during settling. Several experiments were carried out on several drives including a 3.5 in. 7,200 rpm drive. These experiments confirmed that the off-track probability after settling, which is defined by the number of seek failures over all trials, is much reduced to less than 1% when the drive is operated under a special temperature condition that increases pivot nonlinearity while the corresponding performance of a conventional linear controller is 12%. The seek failure is defined as the case when the position cannot be maintained within ±2.5% of a track pitch for a certain duration after track seeking mode.     

Iterative learning control of heat-up phase for a batch polymerization reactor

This paper describes a novel method for heat-up phase control of an industrial batch polymerization reactor where heat transfer characteristics change with batches due to fouling of the polymer products on the reactor wall. The main objective of the control is to settle the reactor temperature on a target value within ± 0.1°C in a minimum possible time. To achieve this goal utilizing the repetitive nature of batch operation, the control problem was defined as a tracking problem and feedback-assisted iterative learning control (FBALC) was employed as the underlying control technique. The proposed control method was applied to an industrial batch reactor polymerizing ABS resin. After on-site evaluation for an extended period of time, it was found that the proposed method gives a pronounced improvement in heat-up phase operation. Consistent heat-up profiles with a minimized settling time are obtained.     

Fixed-time Sliding Mode Formation Control of AUVs Based on a Disturbance Observer

In this paper,we investigate formation tracking control of autonomous underwater vehicles(AUVs)with model parameter uncertainties and external disturbances.The external disturbances due to the wind,waves,and ocean currents are combined with the model parameter uncertainties as a compound disturbance.Then a disturbance observer(DO)is introduced to estimate the compound disturbance,which can be achieved within a finite time independent of the initial estimation error.Based on a DO,a novel fixed-time sliding control scheme is developed,by which the follower vehicle can track the leader vehicle with all the states globally stabilized within a given settling time.The effectiveness and performance of the method are demonstrated by numerical simulations.     

硬磁盘驱动器数字伺服控制系统的设计

根据硬磁盘驱动器磁头驱动机构的状态空间模型,运用极点配置技术和最优控制技术,分别设计了磁头定位系统在寻道模式和定道模式下的数字伺服控制器,以满足磁头定位系统寻道时间、定道精度等的性能要求,同时充分考虑了功牦限制、寻道残余振荡等影响。仿真结果表明其具有较好的控制性能。