A Perturbation Approach to Robot Calibration

Abstract

The forward and reverse solutions of a manipulator with six joints are expanded up to second order in the 24 joint param eters. Assuming that the 24 errors of the 24 joint parameters are independent of the setting of the six controllable joint parameters, if suffices to triangulate the six coordinates (three translational, three rotational) of the end-effector and sub tract the ideal position computed from the forward solution of the ideal error-free robot. This provides 24 equations for 24 unknowns. Calibration compensation consists of correcting the six controllable joint parameters by six controllable ad justments so that the effect of the 24 errors is compensated for.