Development of a torque sensing robot arm for interactive communication

Joint torque sensing is important for interactive robots, since the robot interacts with humans and the environment by not only the end effector but also the whole body. We have proposed a practical torque sensing technique which utilizes the flexible part of an harmonic drive gear. The sensing technique provides joint torque sensing without reducing the stiffness of the robot or changing the mechanical structure of the joints. Thus, the torque sensing technique is applicable to joint torque sensing for interactive robots. We developed a 7 DOF anthropomorphic robot arm with harmonic drive gearing built-in joint torque sensors. By using the torque sensing technique we realized an anthropomorphic robot arm with dimensions almost the same as those of the human arm. In this paper, we describe the design and prototyping of the robot arm and the evaluation of the effectiveness of the joint torque sensing technique.