Characterization Of The Friction Parameters OfHarmonic Drive Actuators

Abstract

The control of rigid and flexible robots is performed using models for predicting the behaviour of their structure. It needs to characterize mechanical parameters. We first present the friction phenomenon in the actuators. The usual Coulomb's model of friction combined with viscosity is no more adapted to robot reducers. We have to identify the friction parameters to reduce the control perturbations. We distinguish the static and the quasi-static friction. We verify that the dry friction torque depends on the applied load and on the angular position. In a second time, we describe the stiffness study. The stiffness of each actuator involves an inaccuracy. It is important to know and correct the angular deflection shift. After a theoretical approach, we will present the experimental results and propose a general model.