Multilayer absolute angular displacement sensor based on the re-modulation method

Abstract

To meet the industrial needs of miniaturization and maintain favorable precision and resolution, a circular time-grating angular displacement sensor is proposed by using multi-layer structure and re-modulation scheme. The sensor is a three-layer structure. Its inner and outer rings complete the re-modulation of the signal through the multi-layer structure by using the axial space. The inner ring is used as the rough measurement part to realize the absolute positioning and the outer ring through re-modulation is used as the fine measurement part to improve the resolution of the sensor. A prototype sensor with an outer diameter of Φ = 100 mm and an inner diameter of Φ = 50 mm is manufactured by PCB technology. Preliminary experiments show that when the inner and outer rings are excited at the same time, the inner and outer rings are affected by the crosstalk generated by each other. Therefore, a time division method is further proposed to avoid the influence of signal crosstalk to improve the measurement accuracy. The final experimental results show that the sensor can achieve absolute positioning and the resolution of the fine measurement part is doubled, and the original measurement accuracy reaches ±4. 1″.