Force restrained control to extend flexibility of trajectory planning

Force restraint in contact-rich tasks with robots is vital in order to avoid breaking objects. Impedance/admittance controls are effective for achieving the restraint; however, they require adjustment of the kinematic impedance, which may induce instability. We proposed a force restrain method while PD controller is used for avoiding unstable robot behavior. This method alters position command in case the robot may give extreme force which leads to damaging objects. This method expands the trajectory planning and motion generation area practically because it can be executed under the condition that the controller autonomously restrains excessive force. To examine the effectiveness of the proposed method, we experimented with contact and detach motion in 1- and 2- DoF translational directions.