Evaluation of a rigid body model for a SCARA-type robot with harmonic drive transmissions

Abstract

The dynamic parameters of a rigid body model for a two-degree-of-freedom SCARA-type robot are estimated through experiments to evaluate the validity of the model. The input torque and the torque calculated using the estimated parameters are compared in order to evaluate the validity of the model. The difference between the two torques is examined, and the contributions of the terms in the model are calculated to observe which term has the greatest effect on the difference. The model can describe the robot dynamics within about 10% for velocities higher than 1 rad/s for the shoulder joint and for the complete velocity range for the elbow joint. Since Coulomb dynamic friction is dominant in the low- velocity region, it seems that the friction in the model is not sufficient to describe the dynamics there.