Grasping force control in master-slave system with partial slip sensor ani virtual slip stimulation

For the stable grasping of the object with the robot hand, autonomous grasping force control based on partial slip sensation is known to be effective. To realize dynamic dexterous manipulation, however, slippage between robot finger and the object must be allowed. This paper proposes a novel master-slave system that realizes control of grasping force for conducting stable grasping without slippage and manipulation with slippage according to the operator's intention. In the proposed system, the slave robot automatically controls grasping force based on partial slip information, while the master device applies virtual slip to the operator. Operational intention will be estimated based on the change of grasping force of the operator responding to the virtual slip stimulus. Autonomous grasping force control and operational input are coordinated by suppressing autonomous control according to the estimated intention. The developed partial slip sensor contains strain gages in several ridges placed on the curvature contact surface of the elastic body. By measuring strain velocity of each ridge, the vibration that occurs due to the partial slip can be detected. The virtual slip is displayed by applying dynamic friction force with master device. The formation of virtual slip stimulus is based on the results of psychophysical experiments. Through the grasp manipulation experiments with the developed master-slave system, the validity of the proposed system was confirmed.