An Optical Joint Angle Measurement Sensor based on an Optoelectronic Sensor for Robot Manipulators

This paper presents the design of a joint angle measurement sensor using optoelectronic reflective sensors for use with robotic applications. It offers a minimised solution to shape sensing that can easily be integrated into robotic joints. A mathematical model used to characterize sensor behaviour is presented, and validated experimentally. A single unit of a robotic jointed finger is designed, and the sensing principle is tested with rotational motion. Results are presented and compared to simulated values. While the mathematical model can accurately estimate output signal with varying displacements, limitations of angle range means an updated sensor model is required, with addition of real electrical properties such as saturation of signal and resistance of electrical components. Regression fitting method is therefore done and a third order function was able to accurately estimate the output signal over a simulated sweep of joint angle values.