关键词: 球面机构, 精度, 容错, 过约束, 冗余驱动

Abstract:

The side effects of error sources on the motion precision of a spherical parallel mechanisms were treated as a kind of mechanical system faults,a new concept named precision fault tolerance and its basic idea were presented herein.Degree of precision fault tolerance(DOPFT) was defined as an index for describing the precision fault tolerance ability of the spherical parallel mechanisms. Based on screw theory and over-constrained analysis, m-RRR(m≥4) spherical parallel mechanisms were designed, which had the same kinematic performance with spherical 3-RRR parallel mechanism.Their precision fault tolerance performances were compared via computation of DOPFTs,simulation researches were also conducted. Simulation results show that the fault tolerance strategy based on DOPFT can enhance the motion precision of spherical parallel mechanism and eliminate side effect of error sources on the motion precision of spherical parallel mechanisms effectively.

Key words: spherical parallel mechanism, precision, fault tolerance, over-constrained, redundancy actuation