Abstract
The present paper proposes a multi-point compliance control for manipulators whose end-points are constrained by task objects. Compliance of the contact point is affected by the mechanical compliance of the objects as well as the joint compliance of the manipulator. Therefore, to derive the joint compliance which realizes the desired contact point compliance, the manipulator and the task object need to be represented as the parallel link structure. The method presented here can regulate not only the contact point compliance but also the compliance of several points on the manipulator's links utilizing kinematic redundancy.
First of all, the manipulator and the object are divided into a couple of virtual arms whose end-points are connected each other at the contact point or the points on the manipulator's links. Consequently, the kinematic structure of the manipulator becomes the parallel link structure and the relationship between the stiffness of the connected points and the joint stiffness of the manipulator is formalized. Then the optimal joint stiffness is derived, which realizes the desired connected point stiffness as nearly as possible. Finally, it is shown that the multi-point compliance control can regulate the compliance of the connected points for obstacle avoidance while controlling the contact point compliance.
