Adaptive force control of robot manipulation with consideration of characteristics of objects. 2nd report. Control of one degree-of-freedom manipulator by the adaptive hybrid force control.

Abstract

In this paper, a force control method for manipulators is presented with consideration given to object dynamics based on the adaptive control. This method for the manipulator system is an extension of the previously proposed method for gripper systems, with additional consideration given to the mass effect at the tip of the manipulator. Since present industrial robotic manipulators commonly employ the input/output position servo control system, one of the purposes of this study is to use the proposed control system to simultaneously control the position of the manipulator, the forces on the manipulator and the forces against given objects. However, it is not easy to control the manipulator, without knowledge of the objects, because the dynamics of the object inevitably comes into the overall feedback control system. Then, it is necessary to adjust the control gains, depending on handling of the objects. For this purpose, a method of the adaptive force control based on the position, and force hybrid control is presented, with consideration given to the static and dynamic characteristics of objects. Some simulations and experiments are carried out for a one-degree-of-freedom manipulator system to adjust pushing and/or holding forces to various objects, whether they be soft or hard, and they showed wider applicability and more flexible manipulation of the conventional servo controlled manipulators.