基于四自由度并联机构的数控机床研究

介绍一种基于混合型四自由度并联平台机构开发的五坐标并联机床 .由于其独特的机构设计 ,与基于 Stewart平台的并联机床相比 ,X方向的进给运动与运动平台分离 ,改由工作台单独进给 ,因而其工作空间成倍增大 .采用龙门框架结构和滚珠丝杠支承方案使机床获得更高的刚度 .给出了该机床运动学逆解 ,控制系统采用基于 PC的数控系统进行五轴联动控制

Design and Development of 3-DOF Modular Micro Parallel Kinematic Manipulator

This paper presents the research and development of a 3-legged micro Parallel Kinematic Manipulator (PKM) for positioning in micro-machining and assembly operations. The structural characteristics associated with parallel manipulators are evaluated and the PKMs with translational and rotational movements are identified. Based on these identifications, a hybrid 3-UPU (Universal Joint-Prismatic Joint-Universal Joint) parallel manipulator is designed and fabricated. The principles of the operation and modeling of this micro PKM is largely similar to a normal size Stewart Platform (SP). A modular design methodology is introduced for the construction of this micro PKM. Calibration results of this hybrid 3-UPU PKM are discussed in this paper.

Application of H-infinity Theory to a 6 DOF Flight Simulator Motion Base

The purpose of this study is to apply inverse dynamics control for a six degree of freedom flight simulator motion system. Imperfect compensation of the inverse dynamic control is intentionally introduced in order to simplify the implementation of this approach. The control strategy is applied in the outer loop of the inverse dynamic control to counteract the effects of imperfect compensation. The control strategy is designed using H-infinity theory. Forward and inverse kinematics and full dynamic model of a six degrees of freedom motion base driven by electromechanical actuators are briefly presented. Describing function, acceleration step response and some maneuvers computed from the washout filter were used to evaluate the performance of the controllers.

Application of H∞ theory to a 6 DOF flight simulator motion base

The purpose of this study is to apply inverse dynamics control for a six degree of freedom flight simulator motion system. Imperfect compensation of the inverse dynamic control is intentionally introduced in order to simplify the implementation of this approach. The control strategy is applied in the outer loop of the inverse dynamic control to counteract the effects of imperfect compensation. The control strategy is designed using H∞ theory. Forward and inverse kinematics and full dynamic model of a six degrees of freedom motion base driven by electromechanical actuators are briefly presented. Describing function, acceleration step response and some maneuvers computed from the washout filter were used to evaluate the performance of the controllers.

Co-creative media : theorising digital storytelling as a platform for researching and developing participatory culture

This paper considers the question, ‘what is co-creative media, and why is it a useful idea in social media research’? The term ‘co-creative media’ is now used by Creative Industries researchers at QUT to describe their digital storytelling practices. Digital storytelling is a set of collaborative digital media production techniques that have been used to facilitate social participation in numerous Australian and international contexts. Digital storytelling has been adapted by Creative Industries researchers at QUT as a platform for researching the potential of vernacular creativity in a variety of contexts, including social inclusion of marginalized and disadvantaged groups; inclusion in public histories of narratives that might be overlooked; and articulation of voices that otherwise remain silent in the formulation of social and economic development strategies. The adaption of digital storytelling to different contexts has been shaped by the reflexive, recursive, and pragmatic requirements of action research. Amongst other things, this activity draws attention to the agency of researchers in facilitating these kinds of participatory media processes and outcomes. This discussion serves to problematise concepts of participatory media by introducing the term ‘co-creative media’ and differentiating these from other social media production practices.

The open kimono: How Intel balances trust and power to maintain platform leadership

A small group of companies including Intel, Microsoft, and Cisco have used "platform leadership" with great effect as a means for driving innovation and accelerating market growth within their respective industries. Prior research in this area emphasizes that trust plays a critical role in the success of this strategy. However, many of the categorizations of trust discussed in the literature tend to ignore or undervalue the fact that trust and power are often functionally equivalent, and that the coercion of weaker partners is sometimes misdiagnosed as collaboration. In this paper, I use case study data focusing on Intel's shift from ceramic/wire-bonded packaging to organic/C4 packaging to characterize the relationships between Intel and its suppliers, and to determine if these links are based on power in addition to trust. The case study shows that Intel's platform leadership strategy is built on a balance of both trust and a relatively benevolent form of power that is exemplified by the company's "open kimono" principle, through which Intel insists that suppliers share detailed financial data and highly proprietary technical information to achieve mutually advantageous objectives. By explaining more completely the nature of these inter-firm linkages, this paper usefully extends our understanding of how platform leadership is maintained by Intel, and contributes to the literature by showing how trust and power can be used simultaneously within an inter-firm relationship in a way that benefits all of the stakeholders.

Maintaining centralised application systems : a cross-country, cross-sector, cross-platform comparison

Past studies of software maintenance issues have largely concentrated on the average North American firm. While they have made a substantial contribution to good information system management practice, it is believed that further segmentation of sample data and cross-country comparisons will help to identify patterns of behaviour more akin to many less average organizations in North America and elsewhere. This paper compares the Singapore maintenance scene with the reported North American experience. Comparisons are also made between: Government organizations, Singapore corporations and multinational corporations (MNCs); mainframe and minicomputer installations; and fourth-generation language (4GL) and non-4GL computer installations. Study findings, while in many cases were similar to earlier US studies, do show the importance of Singapore's young application portfolio, the widespread usage of 4GLs and the severe maintenance personnel problems.

Adopting building information modeling (BIM) as collaboration platform in the design industry

This paper discusses the preliminary findings of an ongoing research project aimed at developing a technological, operational and strategic analysis of adopting BIM in AEC/FM (Architecture-Engineering-Construction/Facility Management) industry as a collaboration tool. Outcomes of the project will provide specifications and guidelines as well as establish industry standards for implementing BIM in practice. This research primarily focuses on BIM model servers as a collaboration platform, and hence the guidelines are aimed at enhancing collaboration capabilities. This paper reports on the findings from: (1) a critical review of latest BIM literature and commercial applications, and (2) workshops with focus groups on changing work-practice, role of technology, current perception and expectations of BIM. Layout for case studies being undertaken is presented. These findings provide a base to develop comprehensive software specifications and national guidelines for BIM with particular emphasis on BIM model servers as collaboration platforms.

Design and evaluation of an image analysis platform for low-power, low-bandwidth camera networks

We describe the design and evaluation of a platform for networks of cameras in low-bandwidth, low-power sensor networks. In our work to date we have investigated two different DSP hardware/software platforms for undertaking the tasks of compression and object detection and tracking. We compare the relative merits of each of the hardware and software platforms in terms of both performance and energy consumption. Finally we discuss what we believe are the ongoing research questions for image processing in WSNs.