Measuring Absolute Rotation and Torque in Series Elastic Actuators With a Single Sensor

In this paper, a new sensor is developed and tested to measure the absolute rotational displacement and torque of a shaft simultaneously without any physical contact. A variable surface combined with axial freedom of the shaft is adopted to provide elasticity and toque limiting ability as well as torque/rotation sensing. A kinematic model of the proposed mechanism is constructed and formulated for numerical analysis in order to demonstrate proof of concept. The results are in good agreement with the reference measurements.