基于无源性的全方位移动机器人自抗扰控制

针对全方位移动机器人轨迹跟踪控制中存在的外界干扰和系统参数不确定性问题,提出基于无源性的自抗扰控制方法.该方法通过扩张状态观测器对系统扰动进行估计,并在基于无源性的控制器中加入扰动补偿项以减小外界干扰和参数不确定性对系统的影响;进而,利用系统的无源特性和Lyapunov 理论证明在该控制器作用下闭环系统有界输入有界输出稳定.仿真结果表明,所提出的控制方法响应速度较快,控制精度较高,对系统外扰和模型参数不确定性具有较强的鲁棒性     

于非仿射非线性模型的AC/DC系统H∞鲁棒控制器设计

讨论了交直流联合输电系统的 H∞ 鲁棒控制问题. 首先对交直流输电系统提出一种五阶非仿射非线性不确定控制模型, 该模型能综合反映交直流系统的动态特性. 基于该模型采用分层控制思想设计了系统的 H∞ 鲁棒控制器, 通过对直流系统换流器触发角的控制实现系统内部稳定和鲁棒性能的提高. 仿真结果验证了控制策略的有效性.     

基于耗散理论的机器人神经网络鲁棒控制

为了更好地解决机器人系统中存在的参数不确定和外部干扰的鲁棒控制问题,提出一种基于耗散性理论的神经网络自适应鲁棒控制器,首先应用无源性理论对名义模型设计镇定控制器,然后利用RBF神经网络自适应学习系统的不确定部分,将神经网络逼近误差作为外部干扰,基于H∞控制理论使干扰对系统输出的影响抑制到所要求的最小程度,并用Lyapunov稳定性理论推导出RBF神经网络的权重矩阵调节律以及相关的鲁棒控制器,证明了系统的全局稳定性.仿真结果表明,这种控制器对机器人系统可能受到的干扰具有较好的抑制能力,提高了系统的鲁棒性,实现了系统轨迹的快速准确跟踪,又能很好地消除控制器的抖振,进而提高机器人工作性能.     

矩阵变换器输入侧端口受控耗散哈密尔顿算子建模及无源控制

矩阵变换器无中间直流环节,易受电网扰动和负载扰动的影响.针对这一问题,本文设计了矩阵变换器输入侧无源性控制器以改善控制系统特性.首先,在直–交坐标系下建立输入侧的端口受控耗散哈密尔顿(port-controlled Hamiltonian with dissipation,PCHD)算子模型.然后,设计了基于互联和阻尼配置的无源性控制器,用来实现对输入电流快速准确的跟踪.重新配置了系统的平衡点,通过注入阻尼提高系统的收敛速度,并从理论上对闭环系统的渐进稳定性进行了分析.仿真结果表明,系统在非正常工况下仍能保证输入电流为正弦,相比传统偏差修正法,该控制策略具有更好的动态性能和抗干扰能力.     

无刷直流电机智能控制系统的研究

基于对无刷直流(BLDC)电机的工作和控制原理的分析,提出了无刷直流电机的双闭环自适应模糊PID控制方案.采用模糊控制逻辑实现PID控制器参数的在线自整定,详细说明了自适应模糊PID控制器的设计方法.算法简单有效,易于实现无刷直流电机交流伺服系统的全数字化.用Matlab/Simulink对系统进行了仿真,仿真结果显示系统具有良好的静动态性能和较快的响应速度.     

不平衡电网电压下MMC-UPQC的无源超螺旋二阶滑模控制策略

基于模块化多电平换流器(modular multilevel converter,MMC)的统一电能质量调节器(unified power quality conditioner,UPQC)在电网电压不平衡时,采用传统控制方法存在补偿效率和精确性较低的问题.针对这一情况,提出一种无源超螺旋二阶滑模控制策略.首先,基于MMC-UPQC的数学模型和无源控制理论,设计不平衡电网电压下基于欧拉-拉格朗日模型的正负序无源控制器;然后,加入超螺旋二阶滑模控制对无源控制器进行改善,抑制常规滑模存在的抖振,并解决无源控制对系统精度要求高的问题,提高系统的响应速度、补偿精度和抗干扰能力,提升系统的整体性能;最后,在Matlab/Simulink平台上进行仿真,并与PI控制和单独的无源控制对比,仿真结果验证了所提无源超螺旋二阶滑模控制策略的有效性和优越性.     

直升机智能PID控制研究

针对直升机俯仰角度控制和旋转轴速度控制需求,对模糊PID控制、神经网络PID控制和免疫PID控制在不同控制规律下的系统控制效果进行了对比研究。仿真实验表明,神经网络PID控制器准确性最高,系统响应无误差,稳定性较好,但响应时间较长;模糊PID控制器系统动态响应时间较快,系统稳定性相对最好,但存在微量误差;免疫PID控制器控制直升机旋转轴时,系统响应速度和稳定性明显优于其他两类控制器,但对俯仰角控制效果差。     

交直流并联输电系统的非线性鲁棒控制

针对含有常参数不确定性的交直流输电系统,使用自适应逆推方法设计了直流系统的非线性鲁棒控制器.基于该方法的设计,无需对原系统进行反馈线性化,并能保证闭环误差系统渐近稳定.设计过程表明逆推方法设计的控制器拥有更优越的性能.     

新型直流输电系统的非线性控制研究

为了进一步改善新型直流输电系统的控制性能,提高系统运行的稳定性,首先简要分析了新型直流输电系统的原理及其控制特性,在此基础上,将非线性控制理论中逆系统方法设计控制器的理论引入到新型直流输电系统的控制策略中,提出了利用逆系统方法的新型直流输电系统非线性控制方式,并相应地设计了逆系统方法的非线性控制器及传统直流输电PID控制器。通过对新型直流输电系统控制性能进行仿真实验,将所设计的两种控制器进行比较,结果表明,对于逆系统方法的非线性控制器较之传统直流输电PID控制器,具有更为优良的控制性能。     

一类未知参数非线性系统的自适应无源控制

对一类含有未知参数的本质非线性系统,通常的Backstepping方法无法应用.为此,提出一种基于状态反馈的自适应无源控制对策,通过对非线性系统进行反馈无源化控制,设计自适应无源镇定控制器和自适应无源输出跟踪控制器.设计中适当调节自适应无源控制器参数,能够保证闭环系统稳定且所有信号全局一致有界,从而解决了此类含有未知参数非线性系统的稳定性和输出跟踪问题.仿真算例验证了提出控制方案的有效性,表明系统具有较强的稳定性和跟踪特性.     

Adaptive coordinated passivation control for generator excitation and thyristor controlled series compensation system

The problem of transient stability for a single machine infinite bus system with the generator excitation and thyristor controlled series compensation (TCSC) is addressed via the coordinated passivation method. The system does not need to be linearized. Two types of uncertainties, namely, the damping coefficient uncertainty and the modeling error of TCSC, are considered. First, an excitation control input and a parameter updating law are obtained simultaneously via adaptive back-stepping and Lyapunov methods to achieve stability of the zero dynamics subsystem. Then, a reactance modulated input is derived to ensure the feedback passivity of the whole system, based on which a stabilizing controller for the closed-loop system is designed. Simulation results show that the proposed controller produces better transient performance than the conventional direct feedback linearization controller.     

Wave-based passive control for transparent micro-teleoperation system

A wave-based bilateral controller for a micro-teleoperation system is presented for stability and transparency via a passivity approach. We showed that the application of wave variable formalism allows the passivity of the system in spite of external perturbations and environment uncertainties. While most of the existing wave-based approach assumes LTI and fixed time-delay, this paper extends the research domain to a scaled teleoperation system with variable time-delay, asymmetric gains in force and velocity variables or model uncertainties in the microenvironment. Based on the wave-based analysis of a time-varying system, a variable gain controller is proposed in order to guarantee the passivity of the system. Furthermore, in scaled teleoperation there exist positive gain matrices (scaling position and force factors) that preserve its passivity only if gain matrices are equal, which is hard to find in a real system. In case the equality condition is not satisfied, we introduced filter functions with a set of conditions for two operating cases: a structurally dominated system and a surface-dominated system. Finally, as the nonlinear nature of small scale environments with unknown dynamic passivity condition can not be satisfied, we analyzed the constraints inevitably occurring in a micro-teleoperation system and derived conditions between the parameters. The stability is analyzed based on the passivity of the resultant operator–telemanipulator–environment system. The experimental results show clearly that the proposed passivity conditions ensure stability and transparency performances against variable time-delays and scaling factors.     

Some remarks on the stability of Mamdani fuzzy control systems

This paper presents a passivity approach to the stability analysis of Mamdani fuzzy control systems. The main idea of the paper is that the fuzzy controller can be considered from an input-output viewpoint as a nonlinear dissipative operator. An input-output approach is provided by considering a dynamical dependency of inputs of the fuzzy controller. Then the passivity theory is applied in order to obtain conditions for absolute stability of the closed-loop control system     

大时延遥操作系统的波变量双边自适应控制

针对通信时延对遥操作系统稳定性和透明性的影响,研究了一种基于双边自适应控制和波变量理论的控制方法。通过设计波控制器保证通信传输模块的无源性,在保证系统稳定的基础上,调节波阻抗系数来提高系统的透明性,并在时延10 s的情况下进行主从端速度、位置和力的跟踪仿真实验,结果表明该方法和已有的双边自适应方法相比既能保证系统稳定且透明性好,达到较好的控制效果。     

非线性机电换能器混沌系统的无源化控制

针对一类相对阶为2的非线性机电换能器混沌系统,研究其无源化控制问题．所分析的系统具有标准链式结构,利用逆步（Backstepping）方法及无源性与稳定性之间的等价关系,设计并证明了系统的反馈镇定控制器．仿真算例验证了所提出方法的有效性．     

基于时域无源性控制的六足机器人双边触觉遥操作

随着六足机器人研究工作的深入,针对其遥操作系统的开发面临诸多挑战.为了弥补松软接触条件对系统可控性及稳定性的影响,提出一种基于时域无源性控制(time-domain passivity control,TDPC)的六足机器人双边触觉遥操作方法.其主从两端采取位置-速度的交互模式,通过分析足-地柔性接触的作用机理,构建无源观测器和无源控制律以补偿足底滑移所导致环境系统的潜在有源性,采用速度跟踪模式设计基于触觉力反馈的系统控制架构,并利用Llewellyn准则确定控制律参数的稳定范围.最后,搭建半物理仿真实验平台并验证所提出的双边触觉遥操作方法在松软地形条件下能够保证六足机器人遥操作系统的稳定,且兼具较好的持续跟踪能力.     

Passivity-based tracking control of an omnidirectional mobile robot using only one geometrical parameter

This paper presents an output feedback tracking control scheme for a three-wheeled omnidirectional mobile robot, based on passivity property and a modified generalized proportional integral (GPI) observer. The proposed control approach is attractive from an implementation point of view, since only one robot geometrical parameter (i.e., contact radius) is required. Firstly, a nominal dynamic model is given and the passivity property is analyzed. Then the controller is designed based on passivity property and a modified GPI observer. The controller design objective is to preserve the passivity property of the robot system in the closed-loop system, which is conceptually different from the traditional model-based control methodology. Particularly, the designed control system takes full advantage of the robot natural damping. Therefore, only considerably small or non differential feedback is needed. In addition, theoretical analysis is given to show the closed-loop stability behavior. Finally, experiments are conducted to validate the effectiveness of the proposed control system design in both tracking and robustness performance.     

Robust passivity and feedback passification of a class of uncertain fractional-order linear systems

Theoretical results on robust passivity and feedback passification of a class of uncertain fractional-order (FO) linear systems are presented in the paper. The system under consideration is subject to time-varying norm-bounded parameter uncertainties in both the state and controlled output matrices. Firstly, some suitable notions of passivity and dissipativity for FO systems are proposed, and the relationship between passivity and stability is obtained. Then, a sufficient condition in the form of linear matrix inequality (LMI) for such system to be robustly passive is given. Based on this condition, the design method of state feedback controller is proposed when the states are available. Moreover, by using matrix singular value decomposition and LMI techniques, the existing condition and method of designing a robust observer-based passive controller for such systems are derived. Numerical simulations demonstrate the effectiveness of the theoretical formulation.     

Intelligent control of SVC using wavelet neural network to enhance transient stability

In order to enhance transient stability in a power system, a new intelligent controller is proposed to control a Static VAR compensator (SVC) located at center of the transmission line. This controller is an online trained wavelet neural network controller (OTWNNC) with adaptive learning rates derived by the Lyapunov stability. During the online control process, the identification of system is not necessary, because of learning ability of the proposed controller. One of the proposed controller features is robustness to different operating conditions and disturbances. The test power system is a two-area two-machine system power. The simulation results show that the oscillations are satisfactorily damped out by the OTWNNC.     

Event-triggered synchronization for stochastic delayed neural networks: Passivity and passification case

This article investigates the event-triggered synchronization problem of stochastic neural networks under passivity and passification cases. For saving communication resources, an event-triggered approach is engaged in the design of synchronization for the delayed stochastic neural networks. To decrease network trouble, an event-triggered scheme is suggested between the sampler and communication network. A nonfragile event-triggered controller is intended to guarantee the finite-time stability of the subsequent closed-loop system. By applying the Lyapunov–Krasovkii functional (LKF) and the novel integral inequalities, a stability criteria for an interval-time varying delay error system ensure the designed controller can fulfill the necessities of passivity and passification performance. The desired control gain and event-triggered parameters are then found based on the linear matrix inequalities (LMIs). Finally, illustrative examples are given to show the benefits and validity of the desired control law.