Low cost planar coil structure for inductive sensors to measure absolute angular position

Abstract

There are many applications that need to sense angular displacement/position, such as automotive electronic steering system, throttle and brake pedal position, motors, robotic arm, etc. Contactless sensors are becoming increasingly popular in these kinds of applications due to their robustness, reliability and longevity. The paper proposes a new contactless variable reluctance (VR) resolver that can be built on a PCB as coil traces. The coil layout consists of an excitation coil and two sense coils laid on a single plane of a PCB. A circular metallic disk with a sector aperture alters the induced voltage in the sense coils. The induced voltage in the sense coils is a sine and cosine function of the angular position of disk. The absolute angular position can be measured with high resolution based on sense coil voltages. The design is validated using an ASIC to process the sensor signals and compute the angular position. The linearity of the coil design has been validated through experimental results.