基于DSP的电液比例方向阀频率特性测控系统设计

针对电液比例方向阀频率特性测试问题,提出了一种基于数字信号处理器(DSP)的电液比例方向阀频率特性测控方案。阐述了测试系统整体结构与工作原理。设计了DSP的硬件系统与软件系统,建立了电液比例方向阀频率特性测试实验系统。在建立的实验台上测试了某电液比例方向阀的频率特性。实验结果表明:研制的基于DSP的电液比例方向阀频率特性测控系统工作可靠,自动化程度高,明显提高了频率特性测试效率。     

液压支架试验台远程多缸同步控制系统设计

为解决30 000kN液压支架试验台活动平台及垂直外加载平台远程四缸同步控制技术难题,设计了基于PXI平台和LabVIEW RT的液压支架试验台远程多缸同步控制系统。采用高频电液比例方向阀作为调高油缸液压系统的执行元件,高精度位移传感器作为实时闭环系统的反馈元件,通过在嵌入式实时控制器中运行模糊PID控制算法,实时调整比例方向阀开口度,从而实现调高油缸的同步。实际应用表明,在液压支架试验台活动平台调高过程中,该系统的四缸最大同步误差为0.91 mm,四缸最小同步误差为0.63mm。     

先导式大流量电液比例方向阀建模与仿真研究

先导式大流量电液比例方向阀控制精度高、响应速度快,能精确实现流量的方向控制和比例控制,这对于电液比例系统的高精度控制及其整体性能提高具有重要的意义。针对某型号的先导式大流量电液比例方向阀建立其静、动态特性和先导阀与主阀匹配研究的仿真模型,进行理论计算和仿真研究。仿真结果表明该阀的静、动态特性较好,先导阀与主阀匹配良好,为阀优化设计奠定了基础。     

基于虚拟仪器的电液比例方向阀静动态特性综合CAT系统

首次采用压力传感器构成压差反馈闭环控制,解决了电液比例方向阀稳态流量特性测试时阀压降恒定问题,使其在测试过程中阀压降波动控制在国标规定的5%以内.采用虚拟仪器技术实现了对电液比例方向阀的静动态综合特性测试,主要包括静态特性的稳态流量特性、压力增益特性、负载流量特性、流量压降特性和动态特性的频率特性、阶跃响应特性,并给出了某电液比例方向阀各种特性的实测结果.     

液压混合动力履带车辆联合制动模糊控制

针对液压混合动力履带车辆联合制动系统,为了实现制动过程平稳性,提出了基于制动力分配原则的模糊控制策略.首先在MATLAB中建立了能量再生制动系统和机械制动系统以及车辆动力学仿真模型,然后设计了以制动力分配系数为控制变量的联合制动模糊控制器,给出了模糊控制规则,建立了控制系统仿真模型,并在不同制动强度条件下对车辆制动过程进行仿真.仿真结果表明,联合制动模糊控制系统能够有效回收制动能量,同时与PID控制相比明显改善和提高了履带车辆制动过程稳定性.     

大型导弹起竖过程最优时间轨迹规划研究

关于导弹起竖优化控制问题,对导弹起竖过程的最优时间轨迹规划问题进行研究,提高导弹起竖过程的快速性和平稳性.由于多级液压缸换级碰撞带来的液压冲击引起系统振动,提出采用分级规划的策略.在对每一级进行轨迹规划时,为保证起竖过程的平稳性,在综合考虑装备实际中的液压系统压力、流量及导弹横向过载约束的基础上,根据五次多项式和非对称组合正弦函数的两种最优时间轨迹规划方法,建立了相应的最优时间轨迹规划模型进行求解.对含二级液压缸的大型导弹起竖过程最优时间轨迹规划仿真算例验证了改进的分级规划策略和最优时间轨迹规划方法的有效性.     

机器人化悬臂式掘进机液压行走驱动系统建模

为了解决机器人化悬臂式掘进机行走控制问题,在对该掘进机液压行走驱动系统的工作原理分析的基础上,建立了该系统的数学模型。该数学模型悬臂式掘进机行走驱动系统中电液比例方向阀的电压与阀芯位移关系式和流量方程、液压马达的流量与扭矩方程、比例方向阀的阀芯位移与液压马达角速度关系方程以及方向阀的输入电压与液压马达角速度的传递函数。仿真实验结果表明,所建立数学模型与实际基本吻合,为机器人化悬臂式掘进机性能分析和控制系统设计提供了实用的数学模型。     

机器人液压挖掘机运动系统的建模与控制

首先利用机器人运动学将铲斗的理想运动轨迹和各工作装置的目标转角序列联系起来,然后利用拉格朗日方程建立各工作装置的运动学模型,最后推导出LUDV液压驱动系统的电液模型,从而得到了挖掘机器人运动系统的完整模型．针对系统动力学的高非线性、参数的不确定性、外界干扰及比例方向阀的死区及非线性增益等特点,提出一种建立在自适应鲁棒控制基础上的非连续映射方法来处理运动系统并利用鲁棒反馈来消除近似误差．最后利用动臂控制试验来验证控制方法的正确性．     

基于反推的电液比例系统共振频率控制

针对电液比例系统的非线性以及不确定性因素对破碎频率控制的影响,设计反推的频率控制方法.建立电液比例阀控液压马达的破碎机构的非线性模型,特别是考虑了比例阀的动态频率和阻尼特性,将系统的各不确定性参数对破碎频率的影响等效为液压马达轴上的负载波动;设计基于反推的控制律,构建各步骤的误差信号、虚拟控制信号和目标函数间的关系,在不确定性有界的前提下保证了液压马达输出转速渐近跟踪的稳定性.给出频率控制系统的模型参数,并在基于Matlab6.5的环境下进行了仿真研究以及车载试验,结果表明,对于具有不确定性因素的电液比例频率控制系统,反推控制策略具有较好的控制性能,能够满足共振式破碎机的工程应用要求.     

大功率液压系统能量损耗的仿真研究

该文建立了大功率液压机的阀控电液伺服系统仿真模型,分析了电磁比例方向阀通过节流控制流量而位移或速度控制时产生的能量损耗,从而导致系统的液压油温度的升高,影响液压系统的稳定工作。通过计算机仿真,分析了直接驱动大功率液压机的能量损耗与控制方式之间的矛盾。在同样控制精度下,采用迭代学习PID控制器比PID控制器时的能量损耗低一个数量级。最后,给出了采用迭代学习PID控制器时,液压机滑块位移与系统压力的仿真曲线以及实际应用的采样曲线。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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