Robust Holding Control of Two Cooperating Robot Manipulators

In this paper we deal with the adaptive load sharing for two cooperating manipulators to hold a common object robustly. The task vectors to describe the task are first summarized, and a hybrid control scheme for the simultaneous control of the holding forces and the carrying positions is presented. Within this framework, the robust holding problem is analyzed with paying attention to the contact conditions between the manipulators and the object. The contact conditions are formulated as a set of linear inequalities with respect to the load sharing coefficients. Based on the analysis, a heuristic but very simple algorithm for the on-line adaptation of the load sharing coefficients for the robust holding is presented. The algorithm is corroborated experimentally.