Measurement Method of Vehicle Shaft Revolution Speed Based on Capacitive Grating Sensor

摘要

Due to the narrow interior space of vehicle, the compact structure limited the method of revolution speed measurement based on photoelectric and magnetoelectric, so a new measurement method based on capacitive grating sensor is presented here. The sensor will output alternating capacitance signal by fixed the mobilizable grating on the shaft and fixed the stator grating on the bracket. The capacitance signal will turn into the corresponding sine wave signal to the speed through differential pulse width modulation circuit, subtraction circuit and low-pass filter circuit, and will output a square wave of the same frequency with the sine wave through phase-locked loop circuit. Then the speed measurement will be realized by counting the signal pulse. Experiments show that this method has the characteristics of non-contact measuring and high sensitivity.