Rotation angle sensor based on magnetostrictive materials and fiber Bragg gratings

We present a sensor concept for measuring rotation angle based on magnetostrictive materials and fiber Bragg grating strain sensors. The fiber optic strain sensors are used to measure strain in developed in the magnetostrictive rods due to the rotating permanent magnets. The measured strain is related to the angle of rotation. Numerical modeling was performed to investigate the response of magnetostrictive rods due to different angular orientation of magnets. A prototype based on a pendulum was designed to measure the angle with respect to the direction of gravity. Experimental evaluation of its performance revealed a large amount of hysteresis present in the strain data. Finally, we provide some suggestions for further improvement of the design to improve performance and reduce the amount of hysteresis.