Finite-Control-Set Model Predictive Control of Permanent Magnet Synchronous Motor Drive Systems — An Overview

Permanent magnet synchronous motors (PMSMs) have been widely employed in the industry. Finite-control-set model predictive control (FCS-MPC), as an advanced control scheme, has been developed and applied to improve the performance and efficiency of the holistic PMSM drive systems. Based on the three elements of model predictive control, this paper provides an overview of the superiority of the FCS-MPC control scheme and its shortcomings in current applications. The problems of parameter mismatch, computational burden, and unfixed switching frequency are summarized. Moreover, other performance improvement schemes, such as the multi-vector application strategy, delay compensation scheme, and weight factor adjustment, are reviewed. Finally, future trends in this field is discussed, and several promising research topics are highlighted.      

Control of Non-Deterministic Systems With μ-Calculus Specifications Using Quotienting

The supervisory control problem for discrete event system(DES) under control involves identifying the supervisor, if one exists, which, when synchronously composed with the DES,results in a system that conforms to the control specification. In this context, we consider a non-deterministic DES under complete observation and control specification expressed in action-based propositional μ-calculus. The key to our solution is the process of quotienting the control specification against the plan resulting in a new μ-calculus formula such that a model for the formula is the supervisor. Thus the task of control synthesis is reduced a problem of μ-calculus satisfiability. In contrast to the existing μ-calculus quotienting-based techniques that are developed in deterministic setting, our quotienting rules can handle nondeterminism in the plant models. Another distinguishing feature of our technique is that while existing techniques use a separate μ-calculus formula to describe the controllability constraint(that uncontrollable events of plants are never disabled by a supervisor), we absorb this constraint as part of quotienting which allows us to directly capture more general state-dependent controllability constraints. Finally, we develop a tableau-based technique for verifying satisfiability of quotiented formula and model generation. The runtime for the technique is exponential in terms of the size of the plan and the control specification. A better complexity result that is polynomial to plant size and exponential to specification size is obtained when the controllability property is state-independent. A prototype implementation in a tabled logic programming language as well as some experimental results are presented.     

H_∞ Control for 2-D Discrete State Delayed Systems in the Second FM Model

This paper is concerned with the problem of H_∞control for two-dimensional (2-D) discrete state delay systems described by the second Fornasini and Marchesini (FM) state- space model.A sufficient condition to have an H_∞noise atten- uation for this 2-D system is given in terms of a certain linear matrix inequality (LMI).The optimal H_∞controller is obtained by solving a convex optimization problem.Finally,a simulation example is given to illustrate the effectiveness of the proposed result.     

Adaptive H_∞ Control for Nonlinear Hamiltonian Systems with Time Delay and Parametric Uncertainties

This paper addresses the adaptive H∞ control problem for a class of nonlinear Hamiltonian systems with time delay and parametric uncertainties. The uncertainties under consideration are some small parameter perturbations involved in the structure of the Hamiltonian system. Both delay-independent and delay-dependent criteria are established based on the dissipative structural properties of the Hamiltonian systems and the Lyapunov-Krasovskii functional approach. In order to construct the adaptive H∞controller, the situation that the parameter perturbation is inexistent in the system is also studied and the controller is designed.The adaptive H∞ control problem is solved under some sufficient conditions which ensure the asymptotic stability and the L2 gain performance of the resulted closed-loop system. Numerical example is given to illustrate the applicability of the theoretical results.     

H_∞ Synchronization of Chaotic Systems via Delayed Feedback Control

The H∞ synchronization problem for a class of delayed chaotic systems with external disturbance is investigated. A novel delayed feedback controller is established under which the chaotic master and slave systems are synchronized with a guaranteed H∞ performance. Based on the Lyapunov stability theory, a delay-dependent condition is derived and formulated in the form of linear matrix inequality (LMI). A numerical simulation is also presented to validate the effectiveness of the developed theoretical results...     

Improved Results on Robust H_∞ Control of Uncertain Discrete-time Systems with Time-varying Delay

In this paper, the robust H∞ control problem for uncertain discrete-time systems with time-varying state delay is con- sidered. Based on the Lyapunov functional method, and by resorting to the new technique for estimating the upper bound of the difference of the Lyapunov functional, a new less conservative sufficient condition for the existence of a robust H∞ controller is obtained. Moreover, the cone complementary linearisation procedure is employed to solve the nonconvex feasibility problem. Finally, several numerical examples are presented to show the effectiveness and less conservativeness of the proposed method.     

H_∞ Control with Multiple Delays in Measurements

Based on an innovation analysis method in the Krein space,a sufficient and necessary condition is given for the existence of the solution of H_∞control problem for a linear continuous- time system with multiple delays.By introducing a re-organized innovation sequence,the H_∞control problem with delayed measurements is converted into a linear quadratic(LQ)problem and a delay- free H_2 estimation problem in the Krein space.The controller is given in terms of two forward Riccati equations and a backward Riccati equation.     

Improved Results on Robust H∞ Control of Uncertain Discrete-time Systems with Time-varying Delay

In this paper,the robust H∞ control problem for uncertain discrete-time systems with time-varying state delay is considered.Based on the Lyapunov functional method,and by resorting to the new technique for estimating the upper bound of the difference of the Lyapunov functional,a new less conservative sufficient condition for the existence of a robust H∞ controller is obtained.Moreover,the cone complementary linearisation procedure is employed to solve the nonconvex feasibility problem.Finally,several numerical examples are presented to show the effectiveness and less conservativeness of the proposed method.     

Leader-following consensus for uncertain second-order nonlinear multi-agent systems

This paper studies the leader-following consensus problem for a class of second-order nonlinear multi-agent systems subject to linearly parameterized uncertainty and disturbance. The problem is solved by integrating the adaptive control technique and the adaptive distributed observer method. The design procedure is illustrated by an example with a group of Van der Pol oscillators as the followers and a harmonic system as the leader.     

导弹控制系统的容错控制研究

为了提高导弹姿态控制系统的可靠性,防止由于传感器失效而引起导弹自毁,提出基于信号重构的容错控制方法．为了对姿态控制系统中的传感器进行信号重构,首先考虑弹体弹性振动的影响,分析了弹体弹性振动与姿态角之间的关系;然后分析了传感器输出信号之间的关系;最后,通过解析冗余方法,用正常工作的传感器输出信号重构出现故障的传感器的正常信号．仿真实验表明了该方法的有效性．     

多性能约束下的模糊容错控制系统设计: 离散系统情形

研究了模糊离散系统在同时具有极点指标、H∞指标和方差指标约束下的容错控制器设计问题. 利用分解和等价原理, 将非线性系统多指标约束下的可靠控制问题, 转换为一系列线性极限子系统多性能指标约束下的容错控制器设计问题; 提出了一种新的多指标约束容错控制系统设计方法, 详细分析了各相容指标的取值范围; 并给出了相容指标约束下的容错控制器设计步骤.     

一类不确定网络控制系统的鲁棒容错控制

研究了含有数据包丢失的不确定网络控制系统的鲁棒容错控制问题. 在执行器连续增益故障下,考虑前向网络通道和后向网络通道中存在满足马尔可夫性质的数据包丢失情况,将含有结构不确定性的闭环故障网络控制系统建模为马尔可夫跳变线性系统.基于这个模型,利用Lyapunov稳定性理论和矩阵不等式技术,给出了闭环故障系统随机稳定的充分条件,同时采用锥补线性化方法,给出了控制器设计方法.最后数例仿真验证了该设计方法的有效性.     

Fault-tolerant control for a class of nonlinear sampled-data systems via a Euler approximate observer

In this paper, a fault-tolerant control (FTC) scheme is developed for a class of nonlinear sampled-data systems. First, a Euler approximate discrete model is used to describe the plant under the sampling. Under this model, an observer-based fault estimation method is proposed. To guarantee the accuracy of both the state and fault estimation values, the conditions to make the approximate model consistent with the exact model are presented. Then, an active fault-tolerant controller, which has a constraint condition for the sampling time, is designed to make the faulty system stable. Finally, an inverted pendulum is used to show the efficiency of the proposed method.     

实时协同编辑系统的容错流量控制研究

为了有效利用网络带宽、降低网络流量,并在保持逻辑向量时钟的检查点全局一致基础上,使得系统在恢复复制进程时,做到网络流量小、等待时间短、用户费用少,容错系统将依据编辑文档的编辑距离、编辑相似度,以最小的代价为恢复进程提供最新检查点和最新文档,实现广域网环境下优化的实时协同编辑系统。提出流量控制的算法,并通过OPNET建模和实验测试,对整个系统容错时的流量进行了分析。     

基于滑模控制的卫星姿态控制算法研究

针对卫星姿态控制系统存在外部扰动和执行器故障的情况下,提出一种基于非线性观测器技术和滑模控制理论的容错控制器设计方案。首先,建立含有外部扰动和执行器故障的刚体卫星姿态控制系统运动学方程和动力学方程。然后,通过非线性干扰观测器估计系统中的未知故障,进而利用故障信息基于滑模控制策略设计容错控制器。通过Lyapunov函数证明闭环姿态控制系统的稳定性。最后通过数值仿真验证该容错控制方案的鲁棒性和可行性。     

含时滞记忆的非线性时滞系统满意容错控制

针对一类基于T-S模糊模型描述的非线性时滞系统,研究在一般执行器故障模式下的含时滞记忆的鲁棒H∞容错控制器设计问题.针对任意连续型执行器故障模式,采用并行分布式补偿原理设计含记忆型状态反馈控制器,给出非线性时滞系统在执行器发生故障情况下的鲁棒镇定准则.然后给出H∞性能指标约束下的满意容错控制器的设计方法和设计步骤.提出的含时滞记忆的状态反馈控制方法可以确保当执行器发生故障时,闭环系统不仅具有渐近稳定性,而且有一定的抗扰动性能,状态反馈控制器设计的保守性较不含时滞记忆控制器设计方法大大降低.仿真实例验证了鲁棒容错控制策略的有效性.     

不确定时滞系统相容指标下的鲁棒容错控制器设计

研究了一类同时具有非线性不确定特性、干扰输入和时滞特性的线性系统鲁棒容错控制问题.在更实际、更一般的执行器故障模式下,利用线性矩阵不等式方法,分析了与鲁棒稳定性能相容的H∞扰动衰减性能指标的取值范围;在指标相容的基础上,给出了鲁棒H∞容错控制器存在的充分条件,以及容错控制器的构造性设计方法.仿真实例验证了方法的有效性.     

执行器故障及外界干扰下动态系统的容错控制

研究执行器故障和外界扰动同时存在时动态系统的容错控制问题, 推广和改进了现有相关结果. 具体包括以下几方面: 所提方法不涉及求解含执行器故障变量(时变且未知)的Lyapunov方程; 在设计和实现本文提出的控制方案时, 不需要对执行器故障范围界值进行人工估算; 能有效抑制执行器故障及有界和无界外部干扰对系统性能的影响. 在一定意义上, 现有相关结果仅是本文的一个特例, 且本文所提方案更有效、更易于设计和实现, 因为它不依赖于故障的任何解析信息, 无需知道执行器故障发生的时间及界值大小等.     

Fault-tolerant atomic computations in an object-based distributed system

A distributed system can support fault-tolerant applications by replicating data and computation at nodes that have independent failure modes. We present a scheme called parallel execution threads (PET) which can be used to implement fault-tolerant computations in an object-based distributed system. In a system that replicates objects, the PET scheme can be used to replicate a computation by creating a number of parallel threads which execute with different replicas of the invoked objects. A computation can be completed successfully if at least one thread does not encounter any failed nodes and its completion preserves the consistency of the objects. The PET scheme can tolerate failures that occur during the execution of the computation as long as all threads are not affected by the failures. We present the algorithms required to implement the PET scheme and also address some performance issues. Mustaque Ahamad received his B.E. (Hons.) degree in Electrical Engineering from the Birla Institute of Technology and Science, Pilani, India. He obtained his M.S. and Ph.D. degrees in Computer Science from the State University of New York at Stony Brook in 1983 and 1985 respectively. Since September 1985, he is an Assistant Professor in the School of Information and Computer Science at the Georgia Institute of Technology, Atlanta. His research interests include distributed operating systems, distributed algorithms, faulttolerant systems and performance evaluation. Partha Dasgupta is an Assistant Professor at Georgia Tech since 1984. He has a Ph.D. in Computer Science from the State University of New York at Stony Brook. He is the technical project director of the Clouds distributed operating systems project, as well as a coprincipal investigator of Georgia Tech's NSF-CER award. His research interests include building distributed operating systems, distributed algorithms, fault-tolerant systems and distributed programming support. Richard J. LeBlanc, Jr. received the B.S. degree in physics from Louisiana State University in 1972 and the M.S. and Ph.D. degrees in computer sciences from the University of Wisconsin-Madison in 1974 and 1977, respectively. He is currently a Professor in the School of Information and Computer Science of the Georgia Institute of Technology. His research interests include programming language design and implementation, programming environments, and software engineering. Dr. LeBlanc's current research work involves application of these interests in distributed processing systems. As co-director of the Clouds Project, he is studying language concepts and software engineering methodology for utilizing a highly reliable, object-based distributed system. He is also interested in specification-based software development methodologies and tools. Dr. LeBlanc is a member of the Association for Computing Machinery, the IEEE Computer Society and Sigma Xi.This work was supported in part by NSF grants CCR-8619886 and CCR-8806358, and RADC contract number F30602-86-C-0032