Design of a Novel Elastic Torque Sensor for Hand Injuries Rehabilitation Based on Bowden Cable

Rehabilitation of the hands is critical to the recovery of functions in daily life for individuals with hand injuries. It is documented that robots with force control can help patients effectively in limb rehabilitation. However, considering the limited space of the hands, traditional torque sensors, strain beams, for example, cannot meet the need of the compact structure. Therefore, this paper presents a novel elastic torque sensor with a compact structure to realize the real-time measurement of joint torque for hand rehabilitation. We demonstrate the principle of the torque sensor by analyzing the relationship between the angle and the torque of the joint. Integrated in the exoskeleton, the torque sensor is designed with a compact structure based on the Bowden cable. Finally, we carried out experiments to show the good linearity and torque tracking performance of the sensor. Results also show that the deviation between the actual and desired values caused by the backlash characteristics of the Bowden cable. Moreover, the deviation changes in different conditions and is dependent on velocity and orientation. Therefore, an effective compensation method is proposed to reduce the deviation in the experiment.