Parasitic time-grating angular displacement sensor for precision position measurement of turntable bearing

This paper proposes a parasitic time-grating angular displacement sensor for detecting the position of the turntable bearing. The sensor is mainly composed of probe, rotor, and supporting signal circuit. The probe consists of two separated measuring units on the left and right, and each measuring unit is composed of four sensing units with iron cores, excitation windings, and induction windings arranged according to specific rules. The rotor is made of sinusoidal isometric grooves based on the bearing end cover of the original turntable bearing. The signal processing circuit is used to filter, amplify, and compare the induction signal; meantime, it can generate the excitation signal. The high-frequency clock pulse signal is used as the measurement benchmark to realize the analysis of the position information of the induction signal. The structure and working principles of the sensor are presented in detail. Through the finite element method simulation, the feasibility of sensor scheme is verified, and the theoretical resolution of the prototype sensor is estimated to be about 1.33e-5. A sensor prototype is designed for testing, and the experimental results show that its accuracy can reach -0.003611 degrees to 0.002583 degrees in the range of [0 degrees, 360 degrees] after compensating the error point-by-point through the look-up table method.