Analysis and Design Optimization of a Compact and Lightweight Joint Torque Sensor for Space Manipulators

This paper describes the development of a compact and lightweight joint torque sensor for space manipulators. Space manipulators with torque sensors can not only apply force control approach to more precise and more dexterous space missions, but also monitor the occurrence of unpredicted events as accidental impacts with objects they have to manipulate. At present, most of the compact torque sensors, designed without consideration of space environment, cannot be directly used in space applications. In this paper, we propose a compact and lightweight design for the joint torque sensor based on strain gauge, for the reason of good physical, chemical, and mechanical stabilities under high temperature environment. In addition, to reduce the interferences by axial forces generated by assembling condition and joint motors, the structural optimization for the sensing element is carried out. The proposed design is simulated by FEM software ANSYS, and it shows successful measurements of the torque with a load capacity of 10 Nm, which is sufficient for the torque generated in robot joints. The effect of axial loading is also analyzed by ANSYS. The designed sensor is manufactured by duralumin alloy. The calibration for the sensor is carried out, and several experiments are conducted to ensure its feasibility with the space manipulator.

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