A Nondegenerate Kinematic Solution of a Seven-Jointed Robot Manipulator

Abstract

Kinematically simple manipulators with six joints have unavoidable degenerate configurations that correspond to certain positions or orientations of the end-effector within the workspace. In these degenerate configurations, the end-effec tor of the manipulator is not capable of a motion with six independent degrees of freedom. Such a manipulator reduces the flexibility of a manufacturing system because manufac turing processes need to be planned so that positions or ori entations of the end-effector that correspond to degenerate configurations of the manipulator are not required. In this paper a nondegenerate kinematic solution is devel oped for a kinematically simple seven-jointed robot manipu lator. The solution guarantees that the manipulator is capa ble of positioning and orienting its end-effector within the workspace without ever finding itself in a degenerate configu ration. The nondegenerate kinematic solution is in closed form and is developed from well-known methods and results in three-dimensional kinematics. It is believed that this seven-jointed robot manipulator will be most useful in flexible manufacturing systems.