MATRIXx软件在离散事件仿真中的应用研究

MATRIXx是现今控制领域中一个比较实用的工程软件，尤其在结构复杂的大系统仿真中的应用前景更为可观。本文讨论了MATRIXx仿真软件在离散事件系统仿真中的应用方法，并以冷连轧生产过程中的离散事件系统仿真实例，应用MATRIXx软件中的层次化设计思想以及触发机制建立了仿真模型，给出了仿真效果。     

基于分布对象的离散事件仿真系统

分布对象技术将面向对象的概念揉合到分布计算中,使得基于对象的软件成员在分布异构环境中可重用、可移植和可互操作。文章把分布对象技术用于离散事件系统仿真中,通过对离散事件系统中分布对象的标识,分布对象间同步机制的讨论,提出了基于分布对象离散事件仿真系统的结构,定义了分布仿真对象的接口。     

离散事件系统分布式仿真的集中并行控制

详细介绍了离散事件系统异步仿真中的一种保守的事件／时间管理策略。包括集中式并行控制机制的基本框架、一些概念、定律以及相应的并行算法,最后举例说明了集中式并行算法的控制流程。     

分级调度的分布离散事件系统仿真策略

分布离散事件系统仿真中的仿真策略,是离散事件系统仿真领域研究的一个关键问题。文章提出了基于事件分级调度的仿真调度算法,并详细介绍了算法的基本思想,给出了算法的步骤和流程图,最后对算法进行了简要的分析。     

离散事件系统分布仿真的集中并行控制

详细介绍了离散事件系统异步仿真中的一种保守的事件／时间管理策略。包括集中式并行控制机制的基本框架、一些概念、定律以及相应的并行算法,最后举例说明了集中式并行算法的控制流程。     

面向对象的离散事件仿真建模与实现

该文论述了面向对象方法在离散事件仿真中的应用，提出了一种建模与开发仿真程序的新方法，其特点是易于在单进程操作系统、普通编程平台上实现对并发事件的准确描述和仿真执行。     

EXCEL在离散事件系统仿真中的应用研究

该文将Ｍｉｃｒｏｓｏｆｔ Ｅｘｃｅｌ应用于离散事件系统仿真中,以Ｅｘｃｅｌ的工作表作为输入和输出界面,采用宏语言（ＶＢＡ）编写仿真代码,对单服务排队系统进行了仿真研究,文中内容可为离散事件为系统仿真和教学提供参考。     

DotNet环境下分布式并发离散事件仿真建模与实现

DotNet环境对多线程技术提供了良好的支持，对于分布式离散事件，多线程技术能够以最少代价、最便捷的方式实现其并发活动的仿真。异步多线程仿真编程中的主要问题是线程的引入与控制、对各结点间的仿真时钟同步问题、线程间活动的同步与消息传递、临界变量的访问与保护机制等。从系统实现角度对这些问题进行分析是建模的必要条件件。本文进一步讨论了各结点间通过消息交互的加工过程，最后以控制台方式将分布式离散事件仿真中的主要关键活动编程实现。通过对仿真实现全过程的讨论可以看出，多线程技术能够有效地实现分布式并发离散事件的仿真。     

交通噪声地图仿真中的线声源离散化方法

在城市交通噪声地图仿真中,线声源是一类最主要的声源,其在计算过程中需要被离散成一系列等效点声源后才能运用噪声传播模型进行仿真计算。首先提出了理想线声源模型,探讨了线声源优化预处理方法,通过降低线声源的几何复杂度来提高求解效率。着重介绍了两种线声源离散化方法:静态离散和动态离散。静态离散算法简单,但在近声线区域会出现较为明显的局部高值。动态离散通过对离散因子的调整,能够比较好地兼顾求解速度和求解质量。     

离散相似法中限幅环节的数字仿真

在文献(1)中已经指出离散相似法数字仿真中,积分环节(包括比例积分等积分环节)后面带有非经线环节时,不仅要对输出量y作非线性处理,而且还必须对状态变量x也作非线性处理。不过该文中心不在此点,故言有未尽处,本文对此点作较详细的阐述。     

Discrete Car‐Following Model and its Feedback Control Scheme

In this paper, we discretize continuous car‐following model into a difference equation. With the use of discrete control theory, the discrete car‐following model was linearized and the impulse transfer function was obtained. Based on the definition of traffic jam, one Lemma was proposed to judge system stability and two theorems were given to judge the non‐jam conditions for controlled and uncontrolled systems. Moreover, the feedback gain was designed for a controlled system. Numerical simulations were conducted to show the validity of the discrete car‐following model and control scheme. The results are in agreement with the theoretical results.     

Continuous‐ and discrete‐time fixed‐gain controller designs for the control of vehicle lateral dynamics

In this paper, fixed‐gain feedback linearization controls are presented to stabilize the vehicle lateral dynamics at bifurcation points for both continuous‐time and discrete‐time cases. Based on the assumption of constant driving speed, a second‐order nonlinear lateral dynamics model is adopted for controller design. Via the feedback linearization scheme and the first‐order Taylor series expansion, a time‐invariant feedback linearization control is proposed as a fixed‐gain linear version of the previously proposed nonlinear one. Furthermore, the conventional linear quadratic regulator (LQR) design is applied to facilitate the choice of the fixed‐gain matrix. Refined controls to compensate the model uncertainty and their local stability analysis are provided. Extension of the continuous‐time design results to discrete‐time cases is also addressed. Numerical simulations for an example model demonstrate the effectiveness of the proposed continuous‐time and discrete‐time design results. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

基于改进离散占空比控制技术的异步电机直接转矩控制方案

传统直接转矩控制的主要缺点之一是产生的转矩脉动较大.采用离散占空比控制技术的直接转矩控制能够在减小输出转矩脉动的同时保持算法简单的特性.提出了离散占空比控制技术的改进方案.分析了零电压矢量在不同转速范围内对转矩的减小作用,并设计了新的选择表.对所提出的基于改进离散占空比控制技术的直接转矩控制系统进行了仿真实验.从仿真结果可以看出,改进的离散占空比控制技术能够进一步减小系统输出转矩的脉动.     

Migration Processes II: The Discrete Case

Following the study of migration processes in the continuous domain in Part I of this paper, we reformulate the concept of migration in the discrete domain (Z^m) and define Discrete Migration Processes (DMP). We demonstrate that this model is a natural discrete representation of the continuous model and maintains the model's features in a qualitative sense. We show that under discrete migration any discrete set shrinks to a limit in finitely many iterations. The discrete representation provides an advantageous basis for digitally implementing the MP model. Using this implementation we illustrate the discrete migration of various types of sets under various types of constraints.     

Using discrete models with continuous design packages

An algorithm is derived for converting a discrete state-space model to an equivalent continuous form. Both approximate and exact solutions are presented. A new discrete model is also derived, for which the continuous design will be valid. The principles are illustrated using an example of optimal control, and the discrete and continuous designs are compared. These techniques have particular relevance for computer aided design of feedback control systems.     

Coordinate frame free Dubins vehicle circumnavigation using only range‐based measurements

The paper presents a feedback control design that allows a Dubins vehicle to enter a circular trajectory using only range‐based measurements from the vehicle to the center of the trajectory. The controller is derived and analyzed based on a novel state space kinematic model, with the state that is composed of two continuous and one discrete state variables.The evolution of the discrete state variable is not completely defined by the model and the control design has to deal with the ambiguity of this value. Based on the conditions that need to be satisfied for the controller to work, the closed loop dynamics analysis can be performed based on 2D phase portraits, and it can be shown that the controller can work in the case of the bounded turning rate of the vehicle. The conditions define only bounds for the controller parameters and not their specific values. Therefore, the parameters can be selected based on the maximal working range of the controller and linear quadratic regulator design. The proposed control design is illustrated by 2D phase portraits and simulations describing the control implementation, which is based only on range measurements. Copyright © 2016 John Wiley & Sons, Ltd.     

Results and perspectives on fault tolerant control for a class of hybrid systems

This article addresses the fault tolerant control (FTC) issue for a class of hybrid systems (HS) modelled by hybrid automata. Two kinds of faults are considered: continuous fault that affects each continuous system mode; discrete fault that affects the switching conditions. In these two faulty cases, the FTC design has two main objectives: (1) maintain the continuous performances including various stabilities of the origin and the output tracking/regulation behaviours along the trajectories of HS; (2) maintain the discrete specifications that have to be followed by HS, e.g. a desired switching sequence. The following three FTC methodologies are considered: FTC for HS with continuous stability goal; FTC for HS with discrete specifications; supervisory FTC design via hybrid control techniques. Some perspectives are also provided. This article provides the readers a survey on the main techniques that can be used to achieve these FTC goals of HS.     

Sliding mode control of a discrete system

Conventional sliding mode control designed on the basis of a continuous system is known to be robust to the plant uncertainties. A realized digital system, however, not only yields chattering, but also may become unstable by a long sampling interval. This paper presents a stable discrete sliding mode control insensitive to the choice of sampling interval and not yielding chattering. The control system is designed on the basis of a discrete Lyapunov function and a sufficient condition of the control gain to make the system stable is given. Contrary to the continuous case, the derived switching plane of the control law is different from the sliding mode, and in its neighborhood, the control law is given by the linear state feedback. Simulations show the effectiveness of the proposed method.     

连续属性离散化算法的时间复杂性分析

对几个常用的连续属性离散化算法的时间复杂性进行分析,并纠正文献[3]第107页与第111页中几处对离散化算法的时间复杂性分析的缺陷。     

混合动态系统中连续状态系统用离散事件系统描述的一致性

混合动态系统起因于离散事件系统用于监控连续状态系统的行。本文用抽象语言方法描述连续状态系统，研究状态离散事件系统描述的一致性。基于输入输出观点简要地 讨论了离散控制器综合。