Intelligent compliance control for robot manipulators using adaptive stiffness characteristics

A compliance control strategy for robot manipulators is proposed by employing a self-adjusting stiffness function. To be specific, each entry of the diagonal stiffness matrix corresponding to task coordinate in Cartesian space is adaptively adjusted during contact along the corresponding axis based on the contact force with its environment. It can also be used for both unconstrained and constrained motions without any switching mechanism which often causes undesirable instability and/or vibrational motion of the end-effector. The experimental results show the effectiveness of the proposed method by employing a two-link direct drive manipulator interacting with an unknown environment