Identification of Noise Source in Electric Power Steering System Using Wavelet Transform
Electric power steering systems (EPS) greatly improve fuel performance over conventional hydraulic power steering systems, and therefore being increasingly adopted. However, it is very important to evaluate the mechanical noise and to identify the correct noise source in steering systems, because an EPS has vibration sources such as at the motor gear reducer, manual gears and intermediate joints. In order to identify the noise source, a technique based on time-frequency analysis using the wavelet transform (WT) has been focused on which uses a mother wavelet (MW) that is derived mathematically. The measured signal is adopted as the MW. In this study, applying this method to time-varying signals, a new concept of the Wavelet Instantaneous Correlation Value (WICV) is discussed and is used to identify the noise source.