Design of a sliding mode control system for chemical processes

This paper considers the non-linear regulation control of chemical processes. A novel and systematic sliding mode control system design methodology is proposed, which integrates an identified second-order plus dead-time (SOPDT) model, an optimal sliding surface and a delay-ahead predictor. The convergence property of the closed-loop system is guaranteed theoretically by means of satisfying a sliding condition and the control system performance is examined with some typical chemical processes. Besides, with the concept of delay equivalent, the proposed sliding mode control scheme can be utilized directly to the regulation control of a non-minimum phase process. As a special case the proposed scheme is further extended to the control of chemical processes whose dynamics are simply described by a first-order plus dead-time (FOPDT) model. In addition, the decentralized sliding mode control scheme for multivariable processes is also explored in this paper. Extensive simulation results reveal that the proposed sliding mode control system design methodology is applicable and promising for the non-linear regulation of time-delay chemical processes.     

Qi系统的Hopf分叉分析与幅值控制

通过非线性状态反馈,不改变Hopf分叉点,实现对四维Qi系统极限环的幅值控制.推导出Qi系统在第一类非零平衡点上产生Hopf分叉的条件,绘制第一类平衡点的分叉图.采用washout filter非线性控制律,利用中心流形定理对受控系统降维,得到极限环的幅值与控制增益之间的近似解析式.通过数值模拟以及幅值解析解与数值解的比较,验证幅值预测的正确性与控制的有效性.     

多自由度 Van der Pol 型系统振幅增大控制

研究多自由度Van der Pol型非线性振动系统振幅增大的控制,设计反馈控制器,用数值方法对控制系统的幅值进行了计算,绘制了在不同控制参数下,系统响应的时间历程曲线和极限环.研究表明通过调整控制参数,能够增大极限环的幅值,有工程应用价值,对高维系统的分岔控制研究有一定的理论意义.     

基于虚拟仪器的机载蒸发循环性能试验台

为研究机载蒸发循环的动态特性,建立了基于虚拟仪器的机载蒸发循环性能试验台.试验台由冷却水循环、制冷剂循环和载冷水循环构成,采用SCXI信号调理设备构成试验台测控硬件,LabVIEW编写了测控软件,实现了对该试验台的参数测量和控制.通过对试验台的调试运行使其具备了模拟机载热负荷环境的测控能力.     

Geometric synthesis of a hybrid limit cycle for the stabilizing control of a class of nonlinear switched dynamical systems

This paper proposes a new constructive method for synthesizing a hybrid limit cycle for the stabilizing control of a class of switched dynamical systems in R², switching between two discrete modes and without state discontinuity. For each mode, the system is continuous, linear or nonlinear. This method is based on a geometric approach. The first part of this paper demonstrates a necessary and sufficient condition of the existence and stability of a hybrid limit cycle consisting of a sequence of two operating modes in R² which respects the technological constraints (minimum duration between two successive switchings, boundedness of the real valued state variables). It outlines the established method for reaching this hybrid limit cycle from an initial state, and then stabilizing it, taking into account the constraints on the continuous variables. This is then illustrated on a Buck electrical energy converter and a nonlinear switched system in R². The second part of the paper proposes and demonstrates an extension to Rⁿ for a class of systems, which is then illustrated on a nonlinear switched system in R³.     

基于Simulink连续系统仿真驱动噪声生成

对噪声驱动的连续系统仿真,由于连续系统往往含有积分运算,不能直接输入通常的噪声信号,必须产生适合的输入信号.针对这种情况,研究了噪声驱动的连续系统仿真时的噪声生成问题,得到了输入噪声信号表达式;分析了Simulink中噪声源模块产生的数据,提出利用Simulink白噪声模块构成的等效带限白噪声模型来产生连续系统仿真需要的典型噪声;通过分析比较认为,Simulink带限白噪声模块和等效带限白噪声模型的参数意义不同但两种方法等价,能够产生连续系统仿真需要的输入信号,为噪声驱动的连续系统仿真研究奠定了基础.     

Structural parameter estimation in power systems

A new class of algorithms for the estimation of structural parameters of a continuous-time linear system excited by random natural disturbances is presented in the paper. All these algorithms are based on fitting the autocorrelation function of the system output; differences among them arise from the various possible formulations of the fit-criterion. Thus, the asymptotic statistical properties of the estimate are analyzed in order to have a choice tool among the class of algorithms and to compare them with other existing estimation methods. A further relevant subject is the statement of a robust test to verify the correctness of the tentative model assumed for the sake of the estimation procedure. Then the above algorithm is applied to the problem of estimating structural parameters (i.e. natural frequencies and damping factors) of the Italian and Yugoslavian power systems by recording some main electrical quantities during the normal operation of the system.Capability of dealing with structural systems affected by an unknown number of oscillatory modes and simplicity of use by non-statistical people are interesting features of the present approach, emphasized by the application.     

某雷达航迹仿真系统设计和实现

本文主要介绍了一种雷达航迹仿真系统的设计和实现,并在此基础上提出了雷达航迹仿真的关键技术,在验证和测试雷达情报处理功能方面具有应用价值.     

液位测量传感器系统的设计与实现

为测量深井液面的高度,针对其口径小、深度大等特点,克服了一般传感器在其测量上的缺点,设计了一种电容式液位传感器系统;它利用被测液体的导电率,通过传感器测量电路将液位高度变化转换成相应的电压脉冲宽度变化,再由单片机进行测量并转换成相应的液位高度进行显示,详细描述了传感器的结构、原理、硬件设计及测量方法,同时对电路波形、实验数据进行了分析;模拟实验表明,该系统对液位深度、时间、温湿度等具有测量、显示与设定功能,并具有结构简单、成本低廉、性能稳定等优点。     

两种基于测量噪声的PID控制整定方法

测量噪声能够产生非期望的控制行为,这些行为能够降低执行机构的损坏程度和系统性能.噪声的影响可以通过滤波测量信号来降低.控制设计是一个复杂的问题,它需要一个在性能和鲁棒性之间的折衷的方法.反馈的缺点是将测量噪声带入到系统中,噪声产生的非期望控制行为可以用滤波器来减少.在控制设计中必须考虑滤波器产生的额外动态.主要讨论两种降低测量信号滤波对由噪声引起的非期望控制行为以及负载扰动响应和过程不确定性鲁棒性的影响的方法.     

Integral-based event triggering controller design for stochastic LTI systems via convex optimisation

The presence of measurement noise in the event-based systems can lower system efficiency both in terms of data exchange rate and performance. In this paper, an integral-based event triggering control system is proposed for LTI systems with stochastic measurement noise. We show that the new mechanism is robust against noise and effectively reduces the flow of communication between plant and controller, and also improves output performance. Using a Lyapunov approach, stability in the mean square sense is proved. A simulated example illustrates the properties of our approach.     

一类模糊比例微分控制器的改进

针对解决模糊控制中出现的输入信号精度的问题,提出了一类简单的混合模糊比例微分控制器,它把一个非线性的跟踪微分器和传统的模糊比例微分控制器有机地结合起来,从而实现了信号精度的改变。该控制器主要的改进还在于对噪声具有非常高的鲁棒性。仿真试验表明了所提出控制器的高效性和实用性。     

球－杆系统的非线性问题

球－杆系统真正的问题并不是大行程下的非线性现象, 而是平衡点上的自振荡问题. 分析指出自振荡是由于球在滚动时存在一种滞环特性而引起的. 提出了一种极点配置的方法来避免自振荡. 仿真和实验验证了这一判断. 所采取的稳定措施也是正确的.     

移动机器人向目标点运动的变增益控制方法

针对控制量受限的移动机器人,研究其向目标点运动的控制问题,提出了移动机器人有效控制的概念,并采用交增益控制方法,使系统的状态单调收敛,最终到达目标点．该方法可有效避免系统收敛于极限环上的情况,仿真结果验证了交增益控制器的有效性。     

基于粒子群优化算法的极限环极值搜索控制

提出一种利用粒子群优化算法进行在线寻优的自适应控制算法,该方法可抑制极限环的振荡幅值．应用极值搜索控制的思想,在线测量极限环的振荡幅度,并将其作为优化目标,利用粒子群优化算法寻找最优控制量,使得极限环的振荡幅值最小．针对粒子群优化和极限环控制的特点,提出一种加快收敛的算法．数值实验表明,提出的算法不仅与传统基于摄动方法...     

电梯轿厢噪声主动控制系统与实验

针对高速电梯运行过程中所产生的轿厢噪声,基于主动噪声控制(ANC)技术,设计并开发了一个3入1出的多通道DSP自适应控制系统。利用该系统在模拟电梯环境中,分别针对130 Hz单频正弦噪声,正弦加白噪声和录取的电梯轿厢嗓声进行了控制实验,获得了20 dB,12 dB,8 dB的降噪效果,验证了本文系统在高速电梯轿厢噪声控制中的可用性和有效性。