Application of Wavelet Transform in Vehicle Wheel Speed Signal Denoising

Wheel speed is a critical parameter in vehicle roadway test. However, because of the internal defects of the wheel speed sensor structure and some electromagnetic inference, this signal is inevitably influenced by kinds of awful noises during the measurement process. These wide band stochastic noises badly influence the analysis of vehicle performance. It is difficult to eliminate these noises with traditional way based on Fourier transform. Wavelet transform is an analytical method of time-frequency, which is especially suitable for the analysis of non-stable signals. This method contains a characteristic of multi-resolution analysis as well as the ability of identifying partial characteristics of signals in time-frequency domain. According to different characteristics of signals and noises at every scale spaces after wavelet transform, the method of soft-threshold is applied to eliminate the noises in this paper. The result suggests this method is effective in wheel speed signal denoising.