A Small-Size Inductive Absolute Angular Displacement Sensor

Traditional absolute angular displacement sensors usually cannot meet the requirements of high measurement accuracy, low environmental sensitivity, and operation in small space at the same time. This article proposes an inductive absolute angular displacement sensor, which is able to achieve high accuracy with small-sized sensing structure. The sensor employs a resonant rotor coil to enhance the strength of the induction signal, even if there are a few induction coils on the stator. The dual-channel method of absolute angular displacement measurement is used to achieve high measurement accuracy, and the environmental sensitivity is reduced by the inductive sensing method. A sensor model was established and simulated to verify the feasibility of the sensor, and then, a printed circuit board (PCB)-based prototype was fabricated. The prototype with an outer diameter of 38 mm and inner diameter of 13 mm ensures its applicability in space-limited working conditions. The experimental results show that the original error of the sensor prototype in the full scale is from -63” to 65”.