Compact and lightweight optical torque sensor for robots with increased range

This paper describes the development of a compact and lightweight optical torque sensor for robots with increased range. The torque generated can only be measured by placing a torque sensor on each joint, which makes the joint bulky and heavy adding extra load to be carried by robots. In this paper, we propose a compact and lightweight design for the torque sensor. This sensor can measure torque of robot's links by detecting torsion. The optical technique is used to detect angular displacement in the joints. As optical technique is immune to electromagnetic interference, light weight, and it also required simple electronics. The torque can be calculated by using torque and twist angle relation. The proposed design is simulated by FEM software (ANSYS), and it shows successful measurements of the torque with a load capacity of 100 Nm, which is sufficient for the torque generated in robot's joints. The designed optical torque sensor is manufactured by electrical discharge machining (EDM). The optical torque sensor is calibrated and several experiments are conducted to ensure its feasibility with the robot.

► Measuring torque is essential for all robots.
► The size and weight of torque sensor is reduced for easy installation to the joint.
► The design sensor can with stand the axial and shear forces of the links.
► The results show good response time with repeatability and accuracy.
► The performance of the sensor is found adequate with the commercial torque sensor.