STRUCTURAL SYNTHESIS OF A CLASS OF RECONFIGURABLE PARALLEL MANIPULATORS BASED ON OVER-CONSTRAINED MECHANISMS

Guanyu Huang, Dan Zhang, Sheng Guo, and Haibo Qu

Keywords

Over-constrained mechanism, reconfigurable parallel mechanism; screw theory; single-loop mechanism; multi-loop mechanism∗ Zhejiang Lab, 1818 Wenyi West Road, Hangzhou, P. R. China;e-mail: huanggy@zhejianglab.com∗∗ Department of Mechanical Engineering, Lassonde School ofEngineering, York University, 4700 Keele Street, Toronto, ONM3J 1P3, Canada; email: dzhang99@yorku.ca∗∗∗ Department of Mechanical Engineering, Beijing JiaotongUniversity, Beijing 100044, P.R. China; e-mail: {shguo,

Abstract

This paper presents a novel way to design a family of reconfigurable parallel mechanisms based on over-constrained mechanisms. In this paper, some single-loop over-constrained mechanisms with lower degrees of freedom (DOFs) are analysed and their classical structures are obtained. (In this paper, the letter C or F and the associated number indicate the type and number of independent constraint couples or forces in the mechanism.) Then, some special single- loop mechanisms are selected to conduct further study, including F1 (one independent force), C1 (one independent couple) and F1C2 (one independent force and two independent couples) over- constrained mechanisms, and the characteristics of these mechanisms are calculated by using screw theory. Some theorems are proposed to design the multi-loop over-constrained mechanisms. According to these theorems, the F1, C1, F1C2 and mixed multi-loop over- constrained mechanisms are designed. Thus, a family of multi- loop over-constrained mechanisms is evolved, and the 3, 4 and 6 limbs of multi-loop over-constrained mechanisms are listed in the tables. Parallel mechanisms are combined with the multi-loop over-constrained mechanisms to generate the reconfigurable parallel mechanisms. Finally, some 3-link, 4-link and 6-link reconfigurable parallel mechanisms are presented to verify the new method.

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