An adaptive regulation method for a class of uncertain time‐delay systems

In this paper, a new adaptive robust stabilization scheme is proposed for uncertain neutral time‐delay systems. No upper bounds on the uncertainties are assumed to be available. An update law is first used to find estimates of these upper bounds. A state‐feedback controller is then designed, which is shown to stabilize the underlying system under some mild conditions. The asymptotic stability of the state trajectories is proved using the Lyapunov–Krasovskii approach. An example is provided, which demonstrates the efficacy of the proposed adaptive control scheme. Copyright © 2012 John Wiley & Sons, Ltd.     

网络控制系统的事件触发与量化控制协同设计

针对信道带宽受限的无线网络控制系统(NCSs),提出了包含事件触发机制、信号量化和状态反馈L2控制的协同设计方法.首先,针对无线网络时变延时,提出一种事件触发机制,并建立了线性系统的量化控制数学模型.其次,基于该模型,并利用李亚普若夫泛函和线性矩阵不等式方法,证明了系统时滞独立的L2量化控制的稳定性,并给出了求解事件触发器参数和L2量化控制的协同设计方法.最后,通过仿真验证了所提方法的有效性.     

Passivity‐based control for stabilization,regulation and tracking purposes of a class of nonlinear systems

In this paper, a new passivity‐based control (PBC) scheme based on state feedback is proposed in order to solve tracking, regulation and stabilization problems for a class of multi‐input multi‐output (MIMO) nonlinear systems expressed in the normal form, with time‐invariant parameters and locally bounded reference weakly minimum phase. For the proposed control scheme two new different state feedbacks, one non‐adaptive for the case when the system parameters are assumed to be known and the other adaptive for the case of unknown parameters, are developed. For the adaptive case it is assumed that the unknown parameters appear linearly in the equations. Analysis of the transient behaviour of the proposed control schemes is presented through the simulation of two examples. Copyright © 2006 John Wiley & Sons, Ltd.     

Adaptive global stabilization of chained-form systems with multiple disturbance and strong nonlinear drifts

This article investigates the stabilization of chained-form nonholonomic systems with strong drifts, multidisturbances, and unknown constant parameters. The disturbances include the matched disturbance with bounded variation and the unknown time-varying unmatched disturbance. A nonlinear disturbance observer is skillfully constructed to evaluate the matched disturbance and a disturbance estimation is used in the virtual controls to compensate the unmatched disturbance. By using a new input-to-state scaling scheme, the original nonholonomic system is transformed into a strict feedback form. Combining back-stepping technique with disturbance observer-based control (DOBC), a composite DOBC and global adaptive stabilization controller is proposed. A switching strategy based on control input magnitude instead of time is proposed to avoid uncontrollability. By using Lyapunov tools, all the states in the system are proved to be uniformly ultimate bounded. Simulations demonstrate the effectiveness of the proposed strategies.     

基于权重自适应更新径向基函数神经网络的水下游动机械臂镇定控制

水下游动机械臂（underwater swimming manipulator, USM）是一种由水下蛇形机器人和矢量推进器组成的新型水下机器人。USM系统具有高度非线性、强耦合以及不确定性等特点,其动力学模型难以精确建立。因此,实现USM的高精度镇定控制存在挑战。针对这一问题,本文基于反馈线性化和自适应径向基函数神经网络（radial basis function neural network, RBFNN）,设计了一种动力学控制方案以实现USM的镇定控制。首先,介绍了USM平台结构,基于Lagrange方程给出了USM的动力学模型,并推导了USM的矢量推力系统模型。然后,设计了基于反馈线性化和RBFNN的动力学控制器,并通过反步法自适应更新RBFNN的权重。其中,权重自适应更新RBFNN用于实时估计系统未建模部分、参数误差以及外部扰动,从而对动力学控制器进行补偿。此外,为了将动力学控制器提供的广义力和力矩转换成各个执行器的控制输入,给出了推力分配策略。最后,进行了湖泊实验,分别对USM的I构型和C构型镇定控制,文章所提出的控制方案在两种构型下的稳态误差均小于0.08 m和10°,验证了所提出的USM六自由度镇定控制器的有效性。     

A convex optimization approach to adaptive stabilization of discrete‐time LTI systems with polytopic uncertainties

This paper suggests a simple convex optimization approach to state‐feedback adaptive stabilization problem for a class of discrete‐time LTI systems subject to polytopic uncertainties. The proposed method relies on estimating the uncertain parameters by solving an online optimization at each time step, such as a linear or quadratic programming, and then, on tuning the control law with that information, which can be conceptually viewed as a kind of gain‐scheduling or indirect adaptive control. Specifically, an admissible domain of stabilizing state‐feedback gain matrices is designed offline by means of linear matrix inequality problems, and based on the online estimation of the uncertain parameters, the state‐feedback gain matrix is calculated over the set of stabilizing feedback gains. The proposed stabilization algorithm guarantees the asymptotic stability of the overall closed‐loop control system. An example is given to show the effectiveness of the proposed approach. Copyright © 2014 John Wiley & Sons, Ltd.     

Adaptive neural network output feedback stabilization of nonlinear non‐minimum phase systems

This paper presents an adaptive output feedback stabilization method based on neural networks (NNs) for nonlinear non‐minimum phase systems. The proposed controller comprises a linear, a neuro‐adaptive, and an adaptive robustifying parts. The NN is designed to approximate the matched uncertainties of the system. The inputs of the NN are the tapped delays of the system input–output signals. In addition, an appropriate reference signal is proposed to compensate the unmatched uncertainties inherent in the internal system dynamics. The adaptation laws for the NN weights and adaptive gains are obtained using Lyapunov's direct method. These adaptation laws employ a linear observer of system dynamics that is realizable. The ultimate boundedness of the error signals are analytically shown using Lyapunov's method. The effectiveness of the proposed scheme is shown by applying to a translation oscillator rotational actuator model. Copyright © 2009 John Wiley & Sons, Ltd.     

基于端口受控哈密顿方法的PMSM最大转矩/电流控制

永磁同步电动机(PMSM)可看作是二端口的能量变换装置。基于能量成形方法和端口受控哈密顿(PCH)系统原理,研究了永磁同步电机(PMSM)的建模与速度控制问题。从能量平衡的观点,建立了PMSM的PCH系统数学模型。利用互联和阻尼配置的能量成形方法,给出了PMSM系统的反馈镇定原理。根据最大转矩/电流(MTPA)控制原理确定了系统期望的平衡点,分析了PMSM系统平衡点的稳定性,并设计了负载转矩恒定已知情况下的控制器。针对负载转矩恒定未知的情形,研究了负载转矩的实时估计与控制器设计方法。仿真结果表明所设计的控制器具有很好的性能和应用前景。     

Robust disturbance attenuation with unknown input observer and sliding mode controller

For a linear system with mismatched disturbance, a robust sliding mode control algorithm using only output feedback is developed in this paper. Although the system with intrinsic issues of unknown input and nonminimum phase is inherited, an improved reduced-order unknown input observer is to be presented in estimating the state of the system. The manipulation of H _∞ control theory along with the implementation of estimated system state can result in robust stabilization with disturbance attenuation when designing integral sliding surface of a system in the sliding mode. A controller is also designed to satisfy the reaching and sliding condition in line with the estimated system state. Finally, a numerical example is explained for showing the applicability of the proposed scheme.     

基于电压微分反馈控制和重复控制的逆变电源控制技术

本文提出一种基于输出电压微分反馈控制和重复控制的逆变电源波形数字化控制方案.内层的电压微分反馈补偿器可以在离散域任意配置逆变电源极点位置,极大地改善了逆变电源动态性能,外层的重复控制则致力于提高稳态精度.该方案在一台基于DSP TMS320F240控制系统的PWM逆变电源上得到验证,实验结果证明在仅使用输出电压反馈的前提下,该方案能得到高质量的输出波形.     

STABILIZATION OF A CLASS OF INTERCONNECTED SYSTEMS USING AGGREGATION MODEL VIA SCHUR APPROACH

ABSTRACT

An output feedback controller based on the aggregation model via Schur approch is presented. Equivalent aggreation models for global and each decoupled subsystem are obtained via Schur decomposion technique in order to generate global and local output feedback control signals. The effect of sub-sysyem state interactions is reduced by employing a global signal while the transient response of the system is regulated using a local control signal. Stability analysis of the proposed control scheme is discussed. The effectiveness of the proposed control scheme based on the aggregation model is studied by considering an interconnected power systems.     

基于dq变换和正反馈的孤岛效应检测策略

孤岛检测是分布式发电并网研究的难点,特别是在逆变器输出与负载功率平衡时难以检测出孤岛.为了检测孤岛效应,本文提出了基于由变换和正反馈的新检测策略,基于这个策略,提出了基于dq变换的电压正反馈和频率正反馈两种检测方法.该两种方法具有无检测盲区,对电能质量影响小,检测速度快等优点.仿真结果证实了两种方法的有效性.     

Experience replay–based output feedback Q‐learning scheme for optimal output tracking control of discrete‐time linear systems

This paper focuses on solving the adaptive optimal tracking control problem for discrete‐time linear systems with unknown system dynamics using output feedback. A Q‐learning‐based optimal adaptive control scheme is presented to learn the feedback and feedforward control parameters of the optimal tracking control law. The optimal feedback parameters are learned using the proposed output feedback Q‐learning Bellman equation, whereas the estimation of the optimal feedforward control parameters is achieved using an adaptive algorithm that guarantees convergence to zero of the tracking error. The proposed method has the advantage that it is not affected by the exploration noise bias problem and does not require a discounting factor, relieving the two bottlenecks in the past works in achieving stability guarantee and optimal asymptotic tracking. Furthermore, the proposed scheme employs the experience replay technique for data‐driven learning, which is data efficient and relaxes the persistence of excitation requirement in learning the feedback control parameters. It is shown that the learned feedback control parameters converge to the optimal solution of the Riccati equation and the feedforward control parameters converge to the solution of the Sylvester equation. Simulation studies on two practical systems have been carried out to show the effectiveness of the proposed scheme.     

A probabilistic approach to stability and stabilization of networked control systems

In this paper, a probabilistic approach is proposed to study the modeling, stability, and stabilization problems for networked control systems (NCSs) with simultaneous random network communication delay and data dropout. Different from existing modeling approaches, the proposed NCSs model naturally captures the stochastic characteristics of the considered NCSs by taking into account the effects of the random network communication delay and data dropout. Based on the developed NCSs model, necessary and sufficient conditions of stability analysis, state, and output feedback stabilization problems are tackled. Moreover, necessary and sufficient stability and stabilization conditions are also presented for the case when the occurrence probabilities of delay and data dropout are partially known. Finally, three numerical examples are provided to demonstrate the effectiveness and the reduced conservatism of the proposed method. Copyright © 2014 John Wiley & Sons, Ltd.     

一种基于非线性反馈重复控制策略的磁通切换直线电机推力波动抑制方法

针对初级永磁型磁通切换直线(LFSPM)电机,研究其定动子双凸极结构引起的与位移相关的定位力、摩擦力及参数变化等不确定性对伺服系统的影响,提出一种基于非线性反馈的重复控制策略。首先,在分析LFSPM电机定位力的基础上,通过设计重复控制器对定位力引起的推力波动进行抑制;随后设计非线性反馈控制器,对因摩擦力及参数变化等不确定性因素引起的推力波动进行补偿,同时使逼近误差随周期数的累加而呈现减小的趋势,保证了系统的全局渐近稳定性。最后,通过AD5435半实物系统搭建了控制模型,实验结果表明,该控制方案有效抑制了因定位力及其他不确定因素引起的推力波动。     

基于线性状态反馈的直流微电网稳定方法

直流微电网中含有大量的电力电子变换器,这些变换器在闭环控制下表现为恒功率负载特性,可能会引起直流微电网的稳定问题。提出基于线性状态反馈的直流微电网稳定方法。该方法通过引入线性状态反馈支路,抵消了恒功率负载的影响,从而确保了整个直流微电网稳定运行。仿真实验结果验证了所提方法的可行性和有效性。     

Adaptive control for high‐order time‐delay uncertain nonlinear system and application to chemical reactor system

This paper focuses on global adaptive state‐feedback stabilization for a class of high‐order uncertain nonlinear systems with multiple delays. Restriction on system growth is relaxed. Two dynamic gains are introduced to deal with uncertainty and nonlinear growth rate of the system. Without precise information about time‐delay being needed and only by like Lyapunov function, a new control strategy is presented based on homogeneous domination idea and two necessary transformations. As an application, the developed scheme is utilized to control design of a two‐stage chemical reactor with delayed recycle streams. Copyright © 2014 John Wiley & Sons, Ltd.     

高性能单相电压源逆变器的输出控制

提出了一种多环反馈加电流前馈的单相逆变器控制方案,该方案使单相逆变器在空载和负载情况下输出电压的幅值和相位均能完全跟踪正弦给定.文中介绍了该方案的理论依据,给出了参数计算方法,并搭建了一台40kVA的实验样机,实验结果验证了该方案的有效性.     

Improvement of Wind-Generator Stability by Fuzzy-Logic-Controlled SMES

This paper proposes a fuzzy-logic-controlled superconducting magnetic energy storage (SMES) scheme for the stabilization of grid-connected wind-generator systems. The control scheme of SMES is based on a sinusoidal pulsewidth-modulation voltage-source converter and a two-quadrant dc–dc chopper using an insulated-gate bipolar transistor. A comparative study is carried out between the proposed fuzzy-logic-controlled SMES and the fuzzy-logic-based pitch controller to improve the wind-generator stability. Simulation results demonstrate that the performance of the proposed fuzzy-logic-controlled SMES is better than that of the fuzzy-logic-based pitch controller in order to stabilize the wind generator.