Impedance-Based Collision Reaction Strategy via Internal Stress Loading in Cooperative Manipulation

Abstract

Cooperative manipulation systems inherently cause internal stress on the common object. Many works have proposed methods to eliminate this internal stress. However, in this paper, we show that this property can be cautiously leveraged to compensate for external disturbance on the cooperative system, particularly disturbances that occur due to collision along the links of one of the cooperating robots. We present an impedance-based scheme to control the level of compensation, thereby regulating the internal stress on the object due to the applied compensation wrenches. Previously, we introduced a method to compensate for collision with one arm of the system, but that approach sometimes caused untenable stress on the object. With the impedance-based compensation strategy presented in this paper, a suitable trade-off between maintaining the desired pose of the grasped object and limiting the permissible internal stress on the object, is achieved. We demonstrate our approach by using two kuka arms to cooperatively grasp and lift a rod in simulation.