Robust active compliance control for practical grasping of a cylindrical object via a multifingered robot hand

Abstract

It is essential to devise a safe compliant control scheme for grasping robots when active multifingered robot hands are interacting with a human or a fragile object. Hence, in this study, a novel active and robust compliant control technique is proposed by employing Integral Sliding Mode Control (ISMC). The ISMC allows us to use a model reference approach for which a virtual mass-spring damper can be introduced to enable compliant control. In addition, it is vital to have practical grasping to ensure a particular grasped object is reachable. For this, a cylindrical coordinate system is exploited due to its simplicity and geometric suitability, for the shape of objects to be grasped. This cylindrical coordinate system is centered at the grasped object. The performance of the ISMC is validated for the constrained underactuated BERUL (Bristol Elumotion Robot fingers) fingers. The results show that the approach is feasible for compliant interaction with objects of different softness in cylindrical space. Moreover, the compliance results show that the ISMC is robust towards nonlinearities and uncertainties in the robot fingers in particular friction and stiction.