562015-03-24 , 法政大学大学院理工学・工学研究科
In this paper, the estimation of the grasping torque of robotic forceps without the use of a force/torque sensor is discussed. To estimate the grasping torque when the robotic forceps driven by a rotary motor with a reduction gear grasps an object, a novel robust reaction torque observer is proposed. The robust reaction torque observer is developed according to the following steps. First, cancellation of the estimation error torque, which causes an overshoot during the torque estimation, is performed. Second, identification of the load torque caused by the reduction gear is conducted in offline experiments and its cancellation is performed. Third, identification of the load torque caused by the component parts of the robotic forceps is conducted in offline experiments and its cancellation is performed. Thus, the grasping torque added to the grasping component of the robotic forceps (the gripper) is derived by subtracting the estimation error torque and the load torques from the estimated torque. Finally, the mass of the load added to the gripper is calculated from the estimated grasping torque. From results of evaluation experiments, the mass of a 50 g load was able to be estimated to an accuracy of 6 g.