Primary Workspace of Simple Six-Link Robots

Abstract

This paper presents an analytical study on the primary workspace of some simple six-link robots. The approach is to divide the structure of a six-link robot into two subsystems, the regional structure and the wrist. Taking advantage of the kinematic simplicity of three-link subsystems, we at the same time are able to solve the problem of reassemblage of the subsystems by using the concept of vector fields at the connection. Two types of wrist, the Euler Angle wrist and the Roll-Pitch-Yaw wrist are considered. (For Roll-Pitch-Yaw wrist, only Cartesian and articulated regional structures are included). Criteria for these robots to access points from specific directions are firstly developed. The theorems regarding accessing points from all directions are then derived. Finally clean statements on the boundaries of primary workspace are made.