一类高阶非线性系统的终端滑模复合控制

研究干扰观测器的控制与自适应终端滑模控制思想相结合,针对调整非线性系统跟踪误差,为了提高控制性能,提出一种适用于一类岛阶非线性系统的复合控制策略.通过引入干扰观测器对系统中存在的不确定进行估计,并利用估计结果对滑模控制输出进行补偿.根据干扰观测器的估计值设计自适应律,实现终端滑模控制器中的切换增益,根据系统扰动的大小进行自适应调节,从而改善由于固定切换增益所造成的滑模控制器输出量过大以及抖振等现象.基于Lyapunov理论证明了复合控制的稳定性,最后通过仿真进一步验证了控制策略的可行性及有效性.     

基于LQR直升机模糊滑模跟踪控制

研究直升机系统稳定性优化问题,由于直升机系统的强耦合和非线性特性的影响,使飞行的稳定性和实时跟踪性差。为解决上述问题,对直升机原始数学模型进行近似线性化和解耦处理,采用模糊滑模控制方法实现直升机姿态角度的跟踪控制。首先,在滑模面的设计中引入最优线性二次型调节器,构建一种积分型切换面。其次,以切换面及导数的乘积和滑模切换增益的变化量为模糊系统的变量,实时调整变结构控制项的切换增益。仿真结果表明,通过控制器设计能够实现直升机姿态角度跟踪的稳定性,对外界不确定干扰具有强鲁棒性且控制器输出抖振问题得到明显改善。     

观测器基于自适应滑模控制的半马尔科夫跳变系统

在许多工业系统中都存在时滞的现象,会使得系统控制性能降低,影响系统的稳定,在实际系统中,滑模依赖时变时滞更值得研究,而滑模控制对于外界干扰,非线性和参数不确定具有很好的鲁棒性,并且控制结构简单,视如上情况,针对观测器基于滑模控制的Markov切换系统,设计积分滑模面,并通过估计变量得到误差系统,通过解线性矩阵不等式使得...     

三轴微机电系统陀螺仪自适应干扰补偿方法

三轴微机电系统(micro-electro-mechanical systems,MEMS)陀螺仪在制造和应用过程中会受到系统参数不确定和外界干扰的影响,降低MEMS陀螺仪的检测精度.本文提出一种基于自适应干扰估计的滑模控制策略对MEMS陀螺仪进行参数不确定和干扰补偿,同时实现轴向轨迹跟踪,从而提高检测精度.相比传统滑模控制方法,该策略利用趋近律概念描述滑模趋近运动,改善趋近运动阶段的动态品质,同时利用干扰观测器在线实时估计系统未知干扰,大大降低滑模面的切换增益,有效地降低滑模面抖振.最后利用Lyapunov直接法证明了系统的渐进稳定性和干扰估计的收敛性.仿真结果表明了该策略的有效性.     

基于嵌入积分滑模策略的船舶运动控制

针对船舶模型的不确定和海浪干扰问题,为实现船舶航向控制,提出了一种嵌入积分滑模控制方法,此方法结合了积分滑模和嵌入滑模的控制思想。积分滑模是用来减小滑模函数的增益,嵌入滑模用来补偿系统匹配和不匹配的扰动。并利用基于极点配置的状态估计方法实现了对高频海浪扰动的滤波。最后进行仿真试验,结果表明设计的控制器具有船舶操纵的良好动态特性,具有超调小鲁棒性强的优点,更适合船舶航向控制的工程要求。     

基于Smith预估器的积分切换增益滑模控制

许多化工过程的传递函数往往包含积分环节和一阶惯性加纯时延环节.由于纯时延的存在,一般的控制方法很难使之稳定,即使能,也需要很长的调节时间且会出现振荡,因此在过程控制中这类系统被公认是一挑战性课题.Smith预估控制能克服纯时延,然而对模型非常依赖,当建模出现误差而不确定时,就会出现较大的振荡,甚至发散.特别是系统有常值干扰时,使用Smith预估控制方法,含积分环节的一阶惯性加纯时延系统则会出现余差.因此,本文提出1种基于Smith预估器的积分切换增益滑模控制,该方法使用1种超前一滞后网络前馈补偿常值干扰,利用滑模控制的鲁棒性以克服系统模型的不确定,系统能够实现渐趋稳定.积分型切换增益减小了系统抖动.仿真研究表明本文提出的方法能够控制好包含积分环节的一阶惯性加纯时延系统,是1种有应用潜力的控制方法.     

一类控制输入饱和受限的不确定系统滑模控制

本文研究控制输入饱和受限情况下不确定系统的滑模控制问题,其中,被控对象同时存在状态矩阵不确定性和控制增益矩阵不确定性.设计了一种积分型切换面和一个具有特殊结构的滑模控制律,可以在参数不确定和控制受限影响下保证系统状态轨迹有限时间内到达指定的切换面,利用等价控制律方法给出了滑模动态渐近稳定的充分条件.数值仿真例子验证了本文算法的有效性.     

跷跷板系统干扰补偿的分层滑模控制策略研究

为提高跷跷板系统在外部干扰下的平衡控制性能,提出一种基于指数收敛干扰观测器与切换增益模糊自适应分层滑模控制相结合的复合控制策略。首先,设计一种指数收敛干扰观测器,对系统受到的外部扰动等不确定因素进行估计补偿,以改善控制器鲁棒性。该观测器不需要状态变量二阶导的信息,可以应对实际工程中难以通过求导的方式获取加速度信号的问题。然后,针对跷跷板这类强耦合欠驱动系统提出一种分层滑模控制算法,并进一步针对滑模控制算法在未知大干扰下切换增益过大的问题,通过模糊规则的设计将切换增益模糊化,以降低系统抖振。最后,仿真和试验结果表明,相较于传统的滑模控制算法,该分层滑模控制算法抗干扰能力更强、切换增益更低。该策略可应用于类跷跷板平衡控制的实际系统。     

近空间飞行器变增益非线性切换控制器设计

针对变后掠翼近空间飞行器大包络、多工作模态和模型不确定的特点,研究其模态切换过程中姿态的鲁棒跟踪控制问题.首先建立含扰动项的飞行器非线性切换模型,基于反步滑模方法和非线性干扰观测器设计鲁棒控制器,通过公共Lyapunov函数理论证明所设计的控制律能够保证闭环切换系统的稳定性;采用变增益切换控制策略为不同飞行模态设计合适的控制增益,用以提高系统的动态性能.仿真结果验证了所提出方法的有效性和必要性.     

无刷直流电机调速系统神经网络自适应滑模变结构控制

为了提高无刷直流电机调速驱动系统的性能,提出神经网络自适应滑模变结构控制策略。推导无刷直流电机端电压与转速之间的微分方程,运用滑模变结构控制理论,通过调节端电压来实现转速控制;为了有效抑制系统在滑模切换面上的抖振采用自适应算法调整滑模增益的大小;从实际应用的角度出发,利用神经网络对非线性函数的任意精度拟合性,设计径向基函数神经网络估计器对控制量中广义扰动进行动态估计。仿真和实验结果表明采用本文提出的方法控制无刷直流电机,超调量小,速度响应快,控制精度高,且系统对各种干扰和参数摄振具有较强的鲁棒性,动、静态性能均优于PID控制。     

基于风速估计的风力机状态反馈滑模容错控制

针对风力机变桨距执行机构突变故障,提出了基于风速估计的自适应状态反馈滑模容错控制策略.首先,设计了基于自适应状态反馈滑模理论的鲁棒主动容错控制器,并结合全阶补偿器对控制律进行设计;然后,利用基于变速灰狼优化算法的组合径向基函数神经网络实现风速估计,可以改善风速测量精度并提高控制系统可靠性;最后,根据线性矩阵不等式和Lyapunov理论对控制器稳定性进行讨论,并与现有控制策略进行比较.仿真结果表明,在健康/故障的变桨距执行机构条件下,所提容错控制方法均能获得较好的控制效果.     

Frequency Regulation of Power Systems With a Wind Farm by Sliding-Mode-Based Design

Load frequency regulation is an essential auxiliary service used in dealing with the challenge of frequency stability in power systems that utilize an increasing proportion of wind power. We investigate a load frequency control method for multi-area interconnected power systems integrated with wind farms, aimed to eliminate the frequency deviation in each area and the tie-line power deviation between different areas. The method explores the derivative and integral terminal sliding mode control technology to solve the problem of load frequency regulation. Such technology employs the concept of relative degrees. However, the subsystems of wind-integrated interconnected power systems have different relative degrees, complicating the control design. This study develops the derivative and integral terminal sliding-mode-based controllers for these subsystems, realizing the load frequency regulation. Meanwhile, closed-loop stability is guaranteed with the theory of Lyapunov stability. Moreover, both a thermal power system and a wind power system are applied to provide frequency support in this study. Considering both constant and variable external disturbances, several numerical simulations were carried out in a two-area thermal power system with a wind farm. The results demonstrate the validity and feasibility of the developed method.      

火车制动防滑控制的滑模变结构控制方法研究

采用传统的滑模变结构控制方法设计的火车制动防滑控制系统动态性能较差且由于系统的非线性会造成系统产生高频率抖振的控制信号.为此采用改进指数趋近律法对传统的滑模变结构控制方法进行改进.首先构建车轮制动时相应的数学模型,然后对传统的防滑系统滑模变结构控制器进行设计,接着对传统的防滑系统滑模变结构控制器进行改进.分别应用Simulink对传统的车轮制动防滑系统和改进的车轮制动防滑系统进行仿真与分析研究.通过对比仿真结果发现应用改进的滑模变结构控制方法设计的高速列车制动防滑系统有更好的动态性能,并且消除了抖振现象,加快了系统响应速度.     

Uncertain Saturated Discrete‐Time Sliding Mode Control for A Wind Turbine Using A Two‐Mass Model

The aim of this paper is to propose a new design variable speed wind turbine control by discrete‐time sliding mode approach. The control objective is to obtain a maximum extraction of wind energy, while reducing mechanical loads and rotor speed tracking combined with an electromagnetic torque. For this application, we designed a discrete time sliding mode control using the equivalent discrete time reaching law. Furthermore, a systematic and improved design procedure for uncertainties discrete‐time sliding mode control (SMC) with saturation problem is provided in this paper. The saturation constraint is reported on inputs vector. LMI technique and polytopic models are used in the design of the switching surface. To achieve some performance requirements and good robustness, in the sliding mode, the pole clustering method is investigated. Based on the unit vector control approach, a robust control is developed, then, to direct and maintain the system states onto the sliding manifold in finite time. Finally, a systematic design procedure for DSMC required to achieve a given performance level is provided and its effectiveness is varied by applying it to variable speed wind turbine systems.     

快速收敛的非线性SISO系统变结构控制设计

讨论了SISO非线性系统的两种滑模变结构控制设计.分别从线性滑模的趋近率及非线性滑模设计提出了新的方法及相应控制方案.文中设计的线性滑模趋近率,其趋近速度及滑动状态随系统状态变化而变化;非线性滑模从系统收敛速度及动静态性能综合考虑进行了设计.研究结果表明,相比于终端滑模,系统具有显著的快速性,并具有良好的动静态性能.最后通过三个仿真实例验证了该方案的有效性.     

Sliding Mode Observer Controller Design for a Two Dimensional Aeroelastic System with Gust Load

The aim of this paper is to develop state estimation and sliding mode control schemes for the vibration suppression of an underactuated wing aeroelastic system in the presence of a gust load disturbance. Ignoring structural elastic deformation and using the concentrated elastic system (spring) to simulate the overall elastic deformation, this aeroelastic model consists of a straight wing and spring system, describing flap and pitch freedoms. The corresponding dynamic motion equation is established using the Lagrange method, and the gust is modeled as a typical “1‐cosine” gust. The aerodynamic lift and moment on the wing are computed by strip theory. The open loop system exhibits the limit cycle oscillations (LCOs) at a certain freestream velocity. The objective is to design a control system for suppressing the LCOs. For the purpose of control, a single trailing‐edge control surface is used. It is assumed that only the pitch angle is measured and the remaining state variables needed for full state feedback are estimated by the designed observer. Then an integral sliding surface is put forward on the estimation space; a new continuous reaching law is proposed to reduce the chattering phenomena. The finite‐time reachability of the predesigned sliding surface is proved and guaranteed by the designed sliding mode control law. The sufficient condition for the asymptotic stability of the closed‐loop system composed of the sliding mode dynamics and the error dynamical system is derived in terms of linear matrix inequality (LMI). The effectiveness of the proposed strategy is finally demonstrated by simulation results.     

基于积分滑动流形的高阶滑模控制器设计

滑模变结构控制方法因其易实现,鲁棒性强等优点广泛应用于实际控制系统中,讨论了具有积分滑动流形的高阶滑模控制器的设计方法.通过设计含积分滑动流形的高阶滑模面,使系统状态在一阶乃至高阶滑模面上均能达到滑动模态.同时利用高阶滑模面为状态变量设计新的状态空间系统,将原先促使系统状态接近并停留在滑模面上的控制目标,拓展为使高阶滑模状态变量趋近于零的控制目标,并结合最优控制方法来设计等效控制量,利用积分流形设计切换控制的切换面,通过严格证明来证实控制器设计的稳定性.在仿真验证部分采用了一阶倒立摆模型,通过比较常规趋近律滑模控制方法和本文方法的仿真结果,可以得出本文方法在减小系统控制量抖振方面的重要作用和优异效果.     

Robust Wind Speed Estimation and Control of Variable Speed Wind Turbines

In this work, a robust control scheme for variable speed wind turbine system that incorporates a doubly feed induction generator is described. The sliding mode controller is designed in order to track the optimum wind turbine speed value that produces the maximum power extraction for different wind speed values. A robust sliding mode observer for the aerodynamic torque is also proposed in order to avoid the wind speed sensors in the control scheme. The controller uses the estimated aerodynamic torque in order to calculate the reference value for the wind turbine speed. Another sliding mode control is also proposed in order to maintain the dc‐link voltage constant regardless of the direction of the rotor power flow. The stability analysis of the proposed controller under disturbances and parameter uncertainties is provided using the Lyapunov stability theory. Finally, the simulation results show that the proposed control scheme provides a high‐performance turbine speed control, in order to obtain the maximum wind power generation, and a high‐performance dc‐link regulation in the presence of system uncertainties.     

A Novel Sliding Mode Control for a Class of Second‐order Mechanical Systems

This paper considers the tracking control problem of a class of second‐order mechanical systems involving parametric uncertainty and external disturbance by a sliding mode control (SMC) without reaching phase. Specifically, an SMC strategy with modified variable‐gain proportional–integral–derivative (PID)‐type sliding function is proposed, by which the existence of a sliding mode throughout an entire response of the system starting from the initial time instance is ensured. Meanwhile, the introduction of a variable gain in the sliding function design effectively solves the dilemma between quicker response and smaller overshoot. The effectiveness of the proposed strategy is verified by both theoretical analysis and simulation results.     

基于反馈线性化的TCSC滑模控制

针对含可控串联补偿(Thyristor Controlled Series Compensation,TCSC)的电力系统非线性强及易受外部扰动的特点,应用反馈线性化方法和滑模变结构控制理论,设计了提高系统稳定性的可控串联补偿滑模控制器。通过引入反馈控制变量,基于状态反馈线性化理论实现了对非线性模型的精确线性化。采用极点配置方法设计滑模切换函数,从理论上保证发电机转子方程具有期望的极点。为了减小抖振采用指数趋近律和准滑动模态方法求取滑模控制律,使得设计的可控串联补偿非线性控制律形式简洁,鲁棒性好。为了验证该控制策略的有效性,在Matlab/Simulink环境下建立了基于反馈线性化的可控串联补偿滑模控制系统仿真模型,进行了仿真研究。仿真结果表明,与传统的控制方式相比,设计的控制器能有效地阻尼系统振荡,增强系统的暂态稳定性。