ADAPTIVE FRICTION COMPENSATION IN ROBOT MANIPULATORS - LOW VELOCITIES

This article analyzes the problem of modeling and compensation of friction at velocities close to zero. A new model, linear in parameters, which captures the downward bends at low velocity is used to adaptively compensate for friction. The need for this type of model is mainly motivated by instability phenomena that can be caused by overcompensation when simple models (such as Coulomb friction models) are used as a basis for the friction compensation. This model, in combination with an adaptive computed torque method, was tested experimentally in a robot manipulator.