Velocity controller with friction compensation

Abstract

The problem of velocity control concerning a manipulator arm is considered. It is assumed that the joint friction is described by a model that contains the Dahl effect. A joint velocity controller and a friction observer are expressed in terms of the normalised quasi-velocities (NQV). The controller with the observer is shown to be exponentially convergent. Some properties arising from the use of NQV are presented. The control strategy, including the friction observer, was tested in simulation on a 3 d.o.f. 3D, Direct Drive Arm robot.