In this paper, a force control method for manipulators is presented with consideration of object dynamics based on the adaptive control. This method for the manipulator system is an extension of the previously proposed method for gripper systems by the authors. Since present industrial robotic manipulators commonly employ the input/ output position servo control system, it is of great interest to control both force and position of the manipulator with this control system. However, it is not easy to control the manipulator without the knowledge of object dynamics. Then, it is necessary to adjust control gains, depending on handling objects. For this purpose, a method of the adaptive force control is presented here with consideration of object dynamics. Some simulations are carried out for a manipulator system to adjust pushing forces to various objects, and show the wider applicability and the flexible manipulation of manipulators.

Conventional robots in force control, which use the input-output position control system employing high reduction gears for drive control mechanisms, have dynamics of objects in the closed control loop. And so it is necessary to adjust control gains, depending on objects. For this purpose, a method of adaptive force control is presented with consideration of static and dynamic characteristics of objects. Some experiments are carried out for a gripper system to adjust the grasping and/or holding force to various objects whether they are soft and hard, and show the wider applicability and the flexible manipulation of the conventional gripper.