Design of a two axis optoelectronic joint measurement sensor using orientation constraining mechanism for flexible robotic application

With the advancement of flexible robotic implementation into a range of industries, it is important to develop robust joint angle measurement and shape sensing systems, for stable and accurate position control and actuation. This work introduces the novel design of an optoelectronic based two-axis joint angle sensor, for shape sensing integration into flexible or continuum manipulators. A simple two-unit tendon actuated joint structure is developed to demonstrate angle sensing in two orientations, using two optoelectronic sensors integrated into a spherical-joint inspired structure, with an innovative internal locking mechanism to eliminate unwanted torsional motion, for increased accuracy of sensing in pitch and roll orientations. Non-linear regression is used for calibration of the joint angle sensor. Calibration validation results show that the sensor is able to estimate roll and pitch with good accuracy, with RMSE values of 0.46° and 4.23° respectively.