Optimal design of robot accuracy compensators

Abstract

The design of a kinematic accuracy compensator for a robot manipulator by using linear optimal control theory is discussed. The method is based on the assumption that either the actual kinematic parameters of the robot have been previously identified or that the pose errors of the manipulator can be measured online. A general mathematical framework is used, so that any linearized error model derived from the corresponding kinematic model can be used to construct an effective robot accuracy compensator. The additive corrections of joint commands are found by a linear quadratic regulator algorithm without explicitly solving the inverse kinematic problem for the actual robot. The weighting matrix and coefficients in the cost function can be chosen systematically to achieve specific objectives. It the poses of the manipulator can be measured online, a parameter identification phase of the robot calibration process can be eliminated, thus avoiding the need to identify all the error sources. A simplified algorithm is presented that accelerates significantly the process speed, making it suitable for real-time applications. >