Fundamental characteristics of a soft finger-joint mechanism for human-care robot

In this paper, a new soft finger-joint mechanism that has multi-directional passive compliance and the ability of the estimation of the external torque is proposed. In this joint, silicone gum cushions are positioned between an output link and two motor-driven disks and transmit rotational motion of the motor to the output link. In addition, the elastic deformation of the cushion contributes to both the generation of passive compliant motion for external torque and the estimation of the external torque. Based on the proposed mechanism, we developed the metacarpal-phalangeal joint (MP joint) of the finger of a robot for human-care services. Furthermore, it is confirmed in several experiments that the proposed mechanism exhibits the expected characteristics