Adaptive friction compensation for hand grasping and compliant control

Attaining a good positioning control is an important step to be achieved for a robotic hand to safely grasp an object. The safety of the grasped object can be enhanced by providing a compliant control strategy. This paper presents a model reference adaptive compliance controller where a mass spring damper system can be introduced. The performance of model-based adaptive controller with the effect of friction and stiction is investigated. A few mathematical models of friction are considered i.e. static friction (stiction), coulomb friction (dry friction), viscous friction, drag friction and square root friction. It is observed that a good positioning and compliant control are feasible in the presence of friction and stiction in simulation. It is evident that the level of compliant control can be achieved during the object grasped.