数字式2D比例换向阀控制器的研究

为使所开发的2D比例换向阀达到较好的性能,设计一款基于DSP芯片的数字式比例控制器,将高频PWM波作用于反接卸荷式H桥驱动电路以控制线圈电流变化,并且内置PID模块实现电流闭环控制。同时,在PID模块增加线性回归算法对线圈电流进行校正。为了减小2D比例换向自身的摩擦力,内置颤振模块,可实现颤振幅值和频率的独立调节。实验结果表明,该控制器具有良好的稳态控制性能,由其控制的比例阀性能得到极大提高。     

比例阀控电液系统抗扰换向滞后补偿反步控制

针对比例阀存在换向滞后,电液系统受到的外部干扰,液压油弹性模量随渗入的空气变化、未建模动态,这些因素增加了设计电液位置控制器的难度,本文使用线性扩张状态观测器(LESO)对比例阀控电液系统的内部扰动、外部扰动、未建模动态进行估计,将虚拟控制量的非线性函数纳入抗扰反步控制器设计,实现比例阀控电液系统换向滞后补偿.分析了闭环系统的稳定性,证明当扰动导数有界时,观测误差和跟踪误差都有界,调整控制器增益与非线性项参数可使跟踪误差收敛到原点附近,仿真和实验表明,本文设计的控制器能显著缩短比例阀换向滞后、提高电液位置控制系统的跟踪速度、精度与抗扰能力.     

呼吸机比例阀的控制与仿真

比例阀是呼吸机吸气模块中负责流量控制的重要组件,为了研究比例阀的特性和提高呼吸机吸气模块的流量跟踪效果,推导了比例阀阀芯位移与流量之间的关系,构建了比例阀的被控对象模型并采用S—函数在Simulink中实现了该模型;对模型进行简单的输入控制可以获得比例阀的瞬态特征和稳态特征,对模型输入采用PID控制和模糊PID控制方法均能够提高比例阀的响应速度;在两种控制方法中采用一致参数,分别在Simulink仿真和实验条件下对比两种方法的流量跟踪效果,可以验证相较于固定参数的PID控制方法,模糊PID控制方法更能有效降低流量的超调量从而保持气路中流量的稳定.     

互联非线性系统反馈主导控制设计方法及汽门开度控制应用

分析了电力系统非线性的数学性质,指出电力系统非线性是一种有界非线性.在此基础上,将反馈主导方法(feedback domination method,FDM)引入多机电力系统非线性控制.该方法与反馈线性化方法不同;反馈线性化方法是通过反馈将原非线性系统转化为线性系统,反馈主导方法则是通过反馈将原非线性系统转换为特定形式的非线性系统,该特定形式的非线性系统的动态由反馈引入的非线性部分主导.以多机系统非线性汽门控制问题为例,设计了反馈主导非线性汽门控制器,该控制器仅包含本地量测量,易于实现.数值仿真表明,多机系统反馈主导非线性汽门控制器可显著提高电力系统暂态稳定性.     

A new adaptive backstepping method for nonlinear control of turbine main steam valve

A new approach for nonlinear adaptive control of turbine main steam valve is developed. In comparison with the existing controller based on ＂classical＂ adaptive backstepping, this method does not follow the classical certaintyequivalence principle in the design of adaptive control law. We introduce this approach, for the first time, to power systems and present a novel parameter estimator and dynamic feedback controller for a single machine infinite bus （SMIB） system with steam valve control. This system contains unknown parameters such as reactance of transmission lines. Besides preserving useful nonlinearities and the real-time estimation of uncertain parameters, the proposed approach possesses better performances with respect to the response of the system and the speed of adaptation. The simulation results demonstrate that the proposed approach is better than the design based on ＂classical＂ adaptive backstepping in terms of properties of stability and parameter estimation, and recovers the performance of the ＂full-information＂ controller. Hence, the proposed method provides an alternative for engineers in applications.     

A directional mutation operator for differential evolution algorithms

Differential evolution (DE) is widely studied in the past decade. In its mutation operator, the random variations are derived from the difference of two randomly selected different individuals. Difference vector plays an important role in evolution. It is observed that the best fitness found so far by DE cannot be improved in every generation. In this article, a directional mutation operator is proposed. It attempts to recognize good variation directions and increase the number of generations having fitness improvement. The idea is to construct a pool of difference vectors calculated when fitness is improved at a generation. The difference vector pool will guide the mutation search in the next generation once only. The directional mutation operator can be applied into any DE mutation strategy. The purpose is to speed up the convergence of DE and improve its performance. The proposed method is evaluated experimentally on CEC 2005 test set with dimension 30 and on CEC 2008 test set with dimensions 100 and 1000. It is demonstrated that the proposed method can result in a larger number of generations having fitness improvement than classic DE. It is combined with eleven DE algorithms as examples of how to combine with other algorithms. After its incorporation, the performance of most of these DE algorithms is significantly improved. Moreover, simulation results show that the directional mutation operator is helpful for balancing the exploration and exploitation capacity of the tested DE algorithms. Furthermore, the directional mutation operator modifications can save computational time compared to the original algorithms. The proposed approach is compared with the proximity based mutation operator as both are claimed to be applicable to any DE mutation strategy. The directional mutation operator is shown to be better than the proximity based mutation operator on the five variants in the DE family. Finally, the applications of two real world engineering optimization problems verify the usefulness of the proposed method.     

A differential game of international pollution control

Pollution is an inevitably by-product of production and damages the environment. The trade-off between production as a good and pollution as a bad over time can be analysed in the framework of a control model, which yields a path of emission charges that force the producers to behave in associally optimal way. Pollution that crosses national borders calls for international coordination of emission charges. In order to estimate the benefits of coordination one must use a realistic non-cooperative equilibrium concept. A natural extension of the control model implies unrealistic assumptions on information and commitment, and under-estimates the damage to the environment of not coordinating emission charges. In this note the more realistic subgame-perfect non-cooperative equilibrium is derived, which reinforces the case for international agreement og on pollution control.     

预测反馈控制法及其特性研究

基于与延迟反馈控制法相似的原理，提出了一种新的混沌系统控制方法——预测反馈控制法．该方法基于目标系统的预测状态来构造控制信号，更为简单实用．首先系统阐述了该方法的基本原理和算法过程；然后严格论证了新方法在不同条件下的稳定性；最后借助于实例模拟总结了预测反馈控制法的一些重要特性，这对该方法的深入理解及应用提供了重要的指导作用．     

人工心脏提高主动脉瓣性能和血管搏动性的反馈控制

本文针对一种旋转式血泵的人工心脏在临床上应用于心衰患者时因恒定泵速导致主动脉瓣永久闭合的现象,以及血管搏动性明显降低的缺点,设计了一种新颖的反馈控制方法,用于提高主动脉瓣性能和血管搏动性.该方法设定主动脉与左心室压力差(△P)的高低参考值(△P_H/△P_L),采用增益调度PI控制器,使△P实际值逼近一个参考值后立即向另一个参考值逼近.仿真结果表明,此方法可以有效地提高血管搏动性、保证心输出量,并使得主动脉瓣间歇性开启的同时不引起抽吸和返流现象.本文设计的控制系统可为旋转式血泵的设计和优化提供理论依据和技术支持.     

Adaptive H-infinity control of synchronous generators with steam valve via Hamiltonian function method

Based on Hamiltonian formulation, this paper proposes a design approach to nonlinear feedback excitation control of synchronous generators with steam valve control, disturbances and unknown parameters. It is shown that the dynamics of the synchronous generators can be expressed as a dissipative Hamiltonian system, based on which an adaptive H-infinity controller is then designed for the systems by using the structure properties of dissipative Hamiltonian systems. Simulations show that the controller obtained in this paper is very effective.     

面向本地差分隐私的K-Prototypes聚类方法

为了在聚类分析中保护数据隐私的同时确保数据的可用性,提出一种基于本地化差分隐私（LDP）技术的隐私保护聚类方案——LDPK-Prototypes。首先,用户对混合型数据集进行编码;其次,采用随机响应机制对敏感数据进行扰动,而第三方在收集到用户的扰动数据后以最大限度恢复原始数据集;然后,执行K-Prototypes聚类算法,在聚类过程中,使用相异性度量方法确定初始聚类中心,并利用熵权法重新定义新的距离计算公式。理论分析和实验结果表明,所提方案与基于中心化差分隐私（CDP）技术的ODPC算法相比,在Adult和Heart数据集上的平均准确率分别提高了2.95%和12.41%,有效提高了聚类的可用性。同时,LDPK-Prototypes扩大了数据之间的差异性,有效避免了局部最优,提高了聚类算法的稳定性。     

基于电液比例阀控制的液压万能试验机系统模糊PID控制器研究

电液比例阀控制的液压万能材料试验机由于时变性和非线性等差异,无法建立精确的数学模型。而常规的PID控制往往需要人工在线整定,既棘手又不经济,如果能运用模糊推理基本理论和方法,构成模糊自适应PID控制。将会极大地改善液压万能材料试验机的控制性能和控制精度。     

A 6:1 image‐compression method using directional prediction for LCD overdrive

Abstract— An overdrive technology was developed and is widely used to diminish motion blur in LCDs. To store a previous frame in the overdrive operation in a limited‐sized memory, simple image‐compression techniques are required. By considering the strong correlation of nearby pixels in natural images, a new 6:1 color‐image‐compression method based on directional prediction is proposed. Different from the directional prediction of intra‐coding in H.264/AVC, the predictable direction is determined beforehand to minimize the computation complexity. A simple content‐adaptive quantization and bit‐streaming method, which preserves image details and is free from blocking artifacts, is also proposed. The experimental results show that our proposed method outperforms the vector quantization block truncation coding method with an average 3‐dB peak signal‐to‐noise ratio (PSNR) as well as the subjective quality in terms of blocking artifacts.     

Design and evaluation of orifice arrangement for particle-excitation flow control valve

In this article, we report a new particle-excitation flow control valve. The purpose of this study is the development of a particle-excitation flow control valve that can precisely control pneumatic cylinders. We have reported this flow control valve principle. The valve, driven by a PZT vibrator, has a simple lightweight structure with large flow rate. We report the relationship between the orifice arrangement and flow rate characteristics of the valve. We have designed a new prototype for the purpose of high controllability. We have measured flow-rate characteristics and confirmed the conditions necessary for continuous adjustment of flow quantity. The control valve works successfully to realize a change in flow rate.     

有限时间控制问题综述

有限时间控制系统因具有良好的鲁棒性能和抗扰动性能而受到广泛关注.首先,回顾了有限时间控制方法的起源,并列举了有限时间控制系统的几种常用判据;然后,总结了有限时间控制系统的研究现状;最后,讨论了未来可能的研究方向.     

静荷拉力试验机测控系统的设计

本文介绍了静荷拉力试验机测控系统的设计,主要用以完成对电力电业部门所使用的安全工器具（如：安全带、脚扣等）和起重工器具（如：钢丝绳、千斤顶等）的静荷拉力测试,也可用于其它金具、材料等的力学性能试验.介绍了试验台液压系统的工作原理,研究试验了系统硬件和软件结构的设计.试验表明,该系统结构简单,性能可靠,易于控制,能满足对电力电业部门使用工器具的静荷拉力测试.     

含正反馈振动主动控制系统的混合自适应控制

对于存在结构正反馈的振动主动控制系统,传统的基于有限冲击响应的自适应前馈控制器设计方法难以同时保证控制系统稳定与良好的控制性能.本文在分析正反馈对前馈控制系统影响的基础上,基于无限冲击响应控制器设计模式,提出一种结合前馈自适应控制器和反馈自适应控制器的混合自适应振动主动控制方法.其中前馈自适应控制器采用参考传感器采集到的扰动相关信号作为参考信号,反馈自适应控制器通过构建扰动的估计量作为参考信号,控制器参数更新采用Landau参数递推算法.以一典型的具有固有正反馈性质的机械振动系统为控制对象,给出了该混合自适应控制算法的详细推导过程以及稳定性和收敛性分析过程,得到了算法稳定与收敛的严格正实条件以及相应放松严格正实条件的要求.在此基础上,通过构建实时振动主动控制实验平台,针对多种振动扰动开展对比实验分析.相关实验结果验证了本文提出的混合自适应振动主动控制方法的可行性和有效性.     

变周期PWM电液比例阀控制电路的设计与实现

分析了脉冲宽度调制(PWM)控制电液比例阀的基本原理,采用C8051F340单片机设计控制电路,通过可编程计数器阵列(PCA)模块编程实现了变周期PWM信号的产生,通过达林顿晶体管阵列芯片实现功率放大。实验表明,该电路具有配置灵活、响应快、精度高等优点,满足电液比例阀控制要求。     

A position controlled disc valve in vehicle semi-active suspension systems

The paper deals with an electromagnetic hydraulic disc valve with a position feedback designed for vehicle semi-active suspension systems. The features of this design are of a simple structure, few critical dimensions, low manufacturing cost, and compact valve size. Although the valve is designed for a vehicle suspension system, it can be used as a two-port proportional control valve for other industrial hydraulic control applications. The paper is concerned with the theoretical model of the valve, including its static and dynamic characteristics with the disc position control, together with the experimental results.     

汽轮发电机主汽门开度非线性鲁棒控制

由于外界干扰以及各种故障的影响, 电力系统的结构并不是不变的, 因此其中的一些重要参数, 如输电线路电抗等, 总是包含某种不确定性. 针对含有参数不确定性的汽轮机调速系统, 使用自适应逆推方法及Lyapunov方法设计了非线性鲁棒汽门控制器, 基于该方法的设计, 设计过程系统、简明, 且不必对原系统进行线性化, 通过对单机无穷大系统的仿真表明了该控制器的有效性.