ON A NEW TORQUE SENSOR FOR TENDON DRIVE FINGERS

This paper proposes a new type of torque sensor for a finger actuation with N actuators and tendons per TV external degrees of freedom. The finger joint torque around a drive pulley is proportional to the tension difference on both ends of the pulley. Using a coupling mechanism between tendons, this tension difference can be measured directly without sensing individual tendon tensions. Based on this idea, we propose a tension differential-type torque (TDT) sensor. With a single body of small size and fewer signal lines, the TDT sensor has several advantages in comparison with the conventional approach, which obtains the torque by attaching two tension sensors at both ends of the drive pulley and feeding sensor signals to a differential circuit. This paper first describes the basic principle of the TDT sensor together with the design orientation. Then, the dynamic characteristic as well as the static characteristic are examined with the introduction of equivalent rotational stiffness, which is useful for discussing system stability. The specially designed TDT sensors were also implemented in a two-fingered robot hand, and the effectiveness of the sensor was confirmed. © 1990 IEEE