Efficient kinematics of a spherical 4R wrist by means of an equivalent 3R wrist

摘要

This paper describes how the forward and inverse position velocity and acceleration kinematics of a spherical 4R wrist-with coupled second and third joint axes-can be transformed efficiently into the kinematics of a well-known equivalent spherical 3R wrist. The transformation relies on one variable parameterα (which is very easy to calculate) and on a fixed design parameterβ. Industrial implementations exist for some specific values ofβ.