Position/Force Sensorless Grasping Control Making Use of Mechanical Spring

This paper introduces a grasping control technique by a simple robot hand. The machine under the experiments is not a robot hand correctly. However alternatively we treat a linear machine driven by a DC servo motor as a simple robot hand. A feature of the hand is tensioned by mechanical springs. We have introduced a position sensor-less control method. It uses an observer to realize observability by using mechanical springs. It has an estimation error if the hand has collision with objects. However we have discoverd that the error caused to realize a kind of compliance control on the hand. So, we present a new force control technique making use of this estimation error. In this paper, we show that the control system realize a compliance control mathematically and the typical application result of grasping control using a boiled egg.