Fast Fourier Transformation Processing Method for Wheel Speed Signal

摘要

At high speed, there are two problems for safety and effective control of vehicles. One is that Signal -to-noise of wheel speed sensors are reduced, and the other is the data calculated by wheel speed signal is emanative. In this paper, wheel speed sensor signal was transformed into a frequency domain by using Fast Fourier Transformation (FFT) or Inverse Fast Fourier Transform (IFFT), waveform features of true signal and noise were studied in a frequency domain. Based on a narrow frequency domain and high energy o f true signal, and wide-band signal and low energy of noise spectrum, a new method to process wheel speed signal was presented by using FFT and IFFT algorithms. Namely, transforming wheel speed signal into frequency do main using FFT firstly, "filtering" the wide-band noises in a frequency domain using polynomial fitting method secondly, and transforming waveforms of the noise spectrum into real signal inversely thirdly. The effects of three filtering methods which are electronic current filter, Karman filter and FFT/IFFT filter were compared to each other by road test of automotive vehicle. The test indicates that it can get rid of noises efficiently ； improve signal-to-noise ratio clearly by using the processing method of FFT/IFFT filter.