Characteristics and Control of Suspension System of Vehicle Subjected to Non-stationary Random Excitations Based on Varying Resonant Frequency Bands

It is difficult to improve the time and frequency resolution at the same time using traditional time-frequency analysis methods, such as Short Time Fourier Transform (STFT) and Wavelet Transform (WT), when processing non-stationary random signals of suspension systems. Meanwhile, it is also hard to obtain the accurate time-frequency characteristics of the systems. This paper proposes a new type of non-uniform modulation function by employing non-stationary Pseudo Excitation Method (PEM) to improve the precision of analyzing vertical vibration responses of suspension systems which are subjected to non-stationary random excitations. A general model of non-stationary pseudo excitation is then generated by using this new method. A quarter vehicle model is subsequently established and the response power spectrum with a high-precision time-frequency resolution of the vertical acceleration is obtained. Simulation examples are given to illustrate the vibration characteristics of the suspension systems of vehicle under two conditions, constant speed and varying speeds. It is found that when the vehicle travels at varying speeds, the higher the speed is, the wider the resonant frequency band of the suspension will be. Finally, the \({H}_{\infty }\) control method of the active suspension system is used for suspension control in finite frequency domain according to the varying resonant frequency bands. Results show that control in the varying resonant frequency bands can improve the damping performance of suspension systems.