Robust control algorithm for safe grasping based on force sensing

Grasping and handling delicate objects with robotic systems need a sophisticated control capable of grasping the object with minimum possible normal force. To devise and implement such a control, one needs to employ a complete dynamic model which accounts for multi phase Columb friction. It is a common practice among researchers to simplify the real multi phase friction with a single one such as slipping mode. Besides, most researchers employed relative velocity and relative acceleration, which are difficult to measure, to detect slipping condition. Investigating the effect of such simplification on the behaviour of the system, this paper presents a new controller which is only based on measurement of the contact and friction forces, instead of measuring relative velocity and acceleration between object and gripper. As the proposed controller is a function of friction coefficient, an algorithm for estimation of that is also presented which guarantees robustness of the controller against variation of mass of the object and friction coefficient.