Cable-driven parallel manipulator (CDPM) is a good solution to achieving large workspace. However, unavoidable vibrations of long cables can dramatically degrade the positioning performance in large workspace applications. Most work so far on cable-driven parallel manipulators (CDPMs) simply neglected the dynamics of the cables themselves. In this paper dynamic modeling of large CDPMs is addressed using a variable domain finite element method (FEM). A cable element with variable length is derived using the absolute nodal coordinate formulation to facilitate motion analysis of CDPMs. The effects of cable length variation and the resulting mass variation are also considered. Based on this element dynamics model of CDPMs can be readily obtained using the standard assembling operation in the FEM. Numerical results showed that the effect of the derivatives of cable length variation and that of the mass variation are trivial.
This paper addresses modeling and control of a cable-supporting manipulator serving as the feed supporting structure of a large radio telescope. The manipulator consists of six long cables so that their curves must be considered. The end-effector is prone to vibration due to the long-span cables even if cable lengths can change perfectly just as they are expected. To deal with this problem, a feedback controller in the workspace is devised, in which the effects of both the cable length error and the pose error of the end-effector are taken into account. A controller is first devised for the resultant cable wrench exerted on the end-effector. Then the incremental relationship between the cable end force and the cable length together with the displacements of the end-effector is deduced. Combining this relationship, we convert the controller into a nonlinear one with cable length increment as the control output, which can be readily utilized in the manipulator. Numerical examples and experiments carried out on a field model of dimension 50 m validate the positioning precision of the manipulator and we can conclude the feasibility of the proposed feed supporting system.
Abstract-The goal of this paper is to shorten the gap of industrial virtual simulation experiment environment for innovative talents of smart manufacturing between university and advanced technology companies and enterprises.This paper proposes the systematic method to establish a joint laboratory with advanced technology companies and enterprises through various forms of cooperation to get the free advanced software and data resources. The mode has been testified and applied successfully in building process and lessons of electronic equipment virtual simulation center. By this method has been used to the teaching reform project in Shaanxi Province, we have reached a cooperation with Siemens Industry software company and the user of Siemens. The innovation of this paper is to summary and practice the cooperation mode from the whole process point of view with technology companies and enterprises. The best industry-university-research model can be refereed and used in establishing industrial virtual simulation laboratory.
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