Abstract
Architectural singularity belongs to the Type Ⅱ singularity,in which a parallel manipulator(PM)gains one or more degrees of freedom and becomes uncontrollable.PMs remaining permanently in a singularity are beneficial for linear-to-rotary motion conversion.Griffis-Duffy(GD)platform is a mobile structure admitting a Bricard motion.In this paper,we present a coordinate-free approach to the design of generalized GD platforms,which consists in determining the shape and attachment of both the moving platform and the fixed base.The generalized GD platform is treated as a combination of six coaxial single-loop mechanisms under the same constraints.Owing to the inversion,hid-den in the geometric structure of these single-loop mechanisms,the mapping from a line to a circle establishes the geometric transformation between the fixed base and the moving platform based on the center of inver-sion,and describes the shape and attachment of the generalized GD platform.Moreover,the center of inversion not only identifies the location of rotation axis,but also affects the shape of the platform mechanism.A graphical construction of generalized GD platforms using inversion,proposed in the paper,provides geometrically feasible solu-tions of the manipulator design for the requirement of the location of rotation axis.
基金项目
National Natural Science Foundation of China(U1813221)
National Natural Science Foundation of China(52075015)
Personnel Startup Project of Zhejiang A&F University Scientific Research Development Foundation of China(2024LFR015)
NETL
NSTL
万方数据