Design and development of a variable reluctance based thin planar angle sensor

In this article, a new, thin noncontact angle sensor based on a variable reluctance technique is presented. The proposed sensor has a disc-shaped eccentric rotor and a stator with two printed circuit boards with circular coils. These parts are easy to manufacture using established less expensive processes. The rotor and stator are positioned such that the inductances of the coils change as the angle changes. The inductance values are processed using a simple algorithm to obtain the sensing angle. For the stator, a dual coil structure is employed, which ensures negligible sensitivity to the axial movement of the rotor. The sensor is designed with the help of finite element analysis. A prototype of the sensor is built and tested. Static and dynamic performance tests are performed on the prototype. The resolution and worst-case linearity error of the prototype are found to be 0.06° and 0.7%, respectively. The features and performance factors of the sensor are apt for industrial and automotive applications.