Chattering reduction of sliding mode control by low‐pass filtering the control signal

The conventional approach to reducing control signal chattering in sliding mode control is to use the boundary layer design. However, when there is high‐level measurement noise, the boundary layer design becomes ineffective in chattering reduction. This paper, therefore, proposes a new design for chattering reduction by low‐pass filtering the control signal. The new design is non‐trivial since it requires estimation of the sliding variable via a disturbance estimator. The new sliding mode control has the same performance as the boundary layer design in noise‐free environments, and outperforms the boundary layer design in noisy environments. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Delay distribution based robust H∞ control of networked control systems with uncertainties

Network induced delay in networked control systems (NCS) is inherently non‐uniformly distributed and behaves with multifractal nature. However, such network characteristics have not been well considered in NCS analysis and synthesis. Making use of the information of the statistical distribution of NCS network induced delay, a delay distribution based stochastic model is adopted to link Quality‐of‐Control and network Quality‐of‐Service for NCS with uncertainties. From this model together with a tighter bounding technology for cross terms, H_∞ NCS analysis is carried out with significantly improved stability results. Furthermore, a memoryless H_∞ controller is designed to stabilize the NCS and to achieve the prescribed disturbance attenuation level. Numerical examples are given to demonstrate the effectiveness of the proposed method. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Design of liveness‐enforcing supervisors via transforming plant petri net models of FMS

This paper focuses on the deadlock prevention problems in a class of Petri nets, systems of simple sequential process with resources, S³PR for short. By structure analysis, we propose an approach that can transform a plant net model into a weighted S³PR (WS³PR) that is behaviorally equivalent to the plant model. The WS³PR is made to be live by properly reconfiguring its weight distribution such that its all strict minimal siphons are self‐max'‐controlled. The resulting WS³PR can serve as a liveness‐enforcing Petri net supervisor for the plant model after removing some idle and operation places. A live controlled system can be accordingly obtained by synchronizing a plant model and the places whose weights are regulated. This research shows that a small number of monitors is obtained, leading to more permissive behavior of the controlled system. Examples are used to demonstrate the proposed concepts and methods. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Observer‐based controller design of discrete‐time piecewise affine systems

This paper presents a novel observer‐based controller design method for discrete‐time piecewise affine (PWA) systems. The basic idea is as follows: at first, a piecewise linear (without affine terms) state feedback controller and a PWA observer are designed separately, and then it is proved that the output feedback controller constructed by the resulting observer and state feedback controller gains can guarantee the stability of the closed‐loop system. During the controller design, the piecewise‐quadratic Lyapunov function technique is used. Moreover, the region information is taken into account to treat the affine terms, so the controller gains can be obtained by solving a set of linear matrix inequalities, which are numerically feasible with commercially available software. Three simulation examples are given finally to verify the proposed theoretical results. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

基于无线网桥的煤矿防火注浆监测系统远程通信的实现

针对现有煤矿防火注浆监测系统有线数据传输方式存在布线复杂、成本高的问题,提出了一种基于无线网桥的煤矿防火注浆监测系统远程通信的实现方案,介绍了无线网桥的3种桥接模式以及无线传输的特点,阐述了基于AX9800 11A无线网桥、采用点对点桥接模式实现济宁二号煤矿防火注浆监测系统远程通信功能的方案。测试结果表明,该方案无线通信的有效距离≥10 km,有效传输速率达10 Mbit/s,视频信号延迟时间≤5 s,数据传输性能可靠,通信质量好。     

模糊控制动态过程能耗分析与优化

为计算和降低模糊控制算法影响下系统动态过程能量消耗,提出了模糊控制系统动态过程的能耗计算公式和一种节能优化设计算法.能耗计算公式采用模糊控制器输出量作为积分对象、采用动态过程调节时间作为积分区间;模糊控制系统节能优化设计算法包括4步;首先,在规定的性能指标下根据系统响应曲线的一般形式拟合出目标曲线;再根据目标曲线计算此时模糊控制系统动态过程能耗;然后,根据上升时间、超调对能耗的影响,调整目标曲线减小系统能耗;最后,用相平面法调整模糊规则使实际响应曲线符合节能目标曲线,从而得到节能的模糊控制算法;在温度控制系统设计中使用该能耗计算公式和优化算法,系统动态过程实际能耗降低15%,验证了公式的正确性和优化算法的有效性.     

新型中功率电法信号发送机设计与实现

针对传统频率域激电仪发送机的不足,利用CPLD及温补晶体产生高精度、高稳定激发极化矩形波驱动信号;采用新型IPM智能功率模块中的4个桥臂,组成H型桥式逆变开关,研究实现一种新型中功率频率域激电信号发送机;实验结果表明,该发送机不仅结构紧凑、携带方便、工作稳定可靠,而且输出功率、频率稳定度均有显著提高,应用效果很好.     

CDIO模式下高等工程教育的改革与探索

高等工程教育存在的一个共性问题即重视理论轻实践,强调个人的知识能力和学术能力,忽视团队协作能力,这与现今的国际人才培养模式不符。文章介绍了CDIO模式的标准及原理,并就此分析了CDIO模式给高等工程教育的改革与探索带来的启示。     

网络工程专业通信类课程设置

网络工程专业与通信工程专业的课程体系既有共同点也有明显的区别。网络工程专业的通信类专业课程主要来源于通信工程专业的有关课程。如何根据网络工程专业的培养目标来进行取舍,是一个值得探讨的问题。本文在对网络工程专业和通信工程专业特点进行对比分析的基础上,给出网络工程专业开设通信类系列课程的建议。     

稀有类分类问题探讨

分类是数据挖掘中的重要任务之一,稀有类分类问题是分类中的一个重要分支,可以描述为从一个分布极不平衡的数据集中标识出那些具有显著意义却很少发生的实例,在现实生活中的很多领域都有广泛的应用.详细地介绍了稀有类分类的问题,探讨了稀有类分类的一些特征、影响稀有类分类的一些因素和对稀有类分类进行评估的标准,介绍了当前分类稀有类的主要方法:基于数据集的方法和基于算法的方法.介绍了当前几种流行的稀有类分类算法.