基于LMI的无人直升机姿态解耦鲁棒控制器设计

无人直升机是典型的多输入多输出系统,具有静不稳、强耦合、不确定的特点。本文首先基于小扰动理论建立起无人直升机的线性模型;然后运用状态反馈进行极点配置,实现了对被控对象四通道间的动态解耦;最后设计了基于LMI的无人直升机H∞鲁棒姿态控制器,解决了模型参数摄动的问题并进行了仿真验证。结果表明所设计的姿态控制器性能良好、结构相对简单,达到ADS-33E-PRF标准LEVEL1的要求。     

带电作业机器人控制系统

带电作业机器人是针对配电线路带电作业而研制开发的一种安全、可靠的带电作业设备. 介绍了带电作业机器人系统组成, 运动控制系统的软硬件实现, 最后详细介绍了系统的位置伺服和力/位置混合控制, 并且通过MATLAB仿真对两种控制方法进行了位置跟踪比较, 仿真曲线证明带有力反馈的控制效果更佳.     

Evaluation of the effect of a paver’s trolley on productivity, task demands, workload and local discomfort

The objective of this study was to determine the differences in the number of paving stones laid (productivity), task demands, energetic workload, body region discomfort and preference when laying paving stones with or without use of a paver’s trolley (n = 8) in a within-subject controlled study of pavers. The number of paving stones laid and the task demands were measured by means of systematic observations at the workplace. The energetic workload was determined using the percentage of heart rate reserve (%HRR). Body region discomfort was measured using visual analog scales, and the workers’ preference was ascertained via interview. The use of a paver’s trolley had no effect on productivity, %HRR or body region discomfort compared to working without a paver’s trolley. The duration of knee-straining activities did not differ between working with (141 min) and without (146 min) the paver’s trolley. However, six of the eight pavers indicated that, given suitable circumstances, they wanted to use the paver’s trolley.

Relevance to industry

To reduce the chance of work-related low back and knee complaints among pavers, the duration, frequency and intensity of lower back and knee-straining activities should be limited by means of technical measures such as mechanical paving. The paver’s trolley does not appear to reduce knee-straining activities and therefore does not appear useful in reducing the risk of knee complaints and disorders.     

Practices with technology: learning at the boundary between study and work

A study of part‐time student experience of university courses delivered using a range of technologies found that information and communication technology enabled students to move between study and work experience to the benefit of their learning in both contexts. Technology‐based study activities enabled students to participate in learning both as a student and as a member of a practice or work context. Given the increasingly pressured lives of all students in higher education and their aspirations for employment after graduation, this suggests that we would benefit from taking their relationship to work and professional practice into account more directly, in deciding how to integrate technology into their study experience. Teacher conceptions of technology as a tool primarily for information delivery and discussion need to expand to recognize that it can be used to construct learning experiences situated in roles, skills and interactive environments that enhance students' ability to make transitions across the boundaries between contexts of study and work.     

基于任务的访问控制系统

从特点、基本组成、模型系结构以及应用前景这几个方面着手介绍一种新的访问控制模式－基于任务的访问控制（TBAC）,并着重说明了基于任务的访问控制模型与传统的访问控制模型的不同点。     

A Deformation Field for Euler–Bernoulli Beams with Applications to Flexible Multibody Dynamics

The deformation field commonly used for Euler–Bernoulli beamsin structural dynamics is investigated to determine its suitability foruse in flexible multibody dynamics. It is found that the traditionaldeformation field fails to produce an elastic rotation matrix that iscomplete to second-order in the deformation variables. A completesecond-order deformation field is proposed along with the equationsneeded to incorporate the beam model into a graph-theoretic formulationfor flexible multibody dynamics [1]. This beam modeland formulation have been implemented in a symbolic computer programcalled DynaFlex that can use Taylor, Chebyshev, or Legendrepolynomials as the basis functions in a Rayleigh–Ritz discretizationof the beam's deformation variables. To demonstrate the effects of the proposed second-order deformationfield on the response of a flexible multibody system,two examples are presented.     

Electronic Meeting Support for Councils

City councils hold meetings several times a week. There is a need for computer support at certain meetings. This paper examines the potential for group support systems for use in city council meetings and shows in what ways they can be helpful in pre-meeting and post-meeting activities. The study is based on 17 computer-supported city council meetings, carried out in Stuttgart, Kornwestheim and other cities as part of the Cuparla Project between 1996 and 1998. Three of these meetings are described in the paper as brief case studies. Following this, all 17 meeting sequences are evaluated and analysed. Guidelines have been developed from the results of the study for the introduction of group support systems in city council meetings.     

The Organisation in Ethnography –A Discussion of Ethnographic Fieldwork Programs in CSCW

Ethnography is now one of the key approaches usedwithin the CSCW community to specify the role ofcomputer based systems in work practice. Yet whatethnography involves as a program of inquiries is onlydiscussed in a piecemeal way in the literature. Thispaper attempts to make up for that absence bydescribing one fieldwork program (or programme)developed over a number of projects in whichethnography has been allied with computer systems andwork practice design. The discussions will be ofinterest to both expert practitioners of ethnographyand novices.     

Supporting Different Dimensions of Adaptability in Workflow Modeling

This paper discusses the theme of workflow systemadaptability in relation to process modeling. Startingfrom a discussion on the role of formal constructs incooperation, the main claim is that adaptabilityinvolves different dimensions of process modeling.These dimensions concern the possibility to flexiblycombine a rich set of basic categories in order toobtain the most suitable language for modeling thetarget business process and the work practices aroundit; to take into account various levels of visibilityof the contexts of definition and use of a processmodel; and finally to allow for temporary as well aspermanent modifications of the process itself.Ariadne, a notation conceived for the above purpose,is illustrated by means of a working example.Moreover, the paper presents the main designprinciples governing Ariadne's implementation.     

基于PC104的某型测试设备的设计实现

该文介绍了一种基于PC104总线的某型测试设备的硬件设计和软件设计方案,提出了主要问题的解决方案。该系统结构紧凑,可靠性高,已在实际生产中得到应用。