Time Domain Vibration Control Simulation And Spectral Analysis Of Human-Vehicle-Road System

The research and application about active,semi-active vibration control in vehicle suspension are considered as a great progress for man-vehicle-road system. Traditional vehicle design, changing vehicle characteristic itself, has been developed into other useful methods to suppress road responses, such as the active or semi-active control systems. The research and application of pseudo-excitation method which applies algebra in solving the problem of random vibration solve the problem of low efficiency in traditional random vibration computation. It is more convenient and easily accepted by the engineers. In this thesis,mathematic model of man-vehicle-road system is established. Based on the magnetorheological fluid shock absorber,a semi-active suspension is designed. The road induced random response of a man-car-road model is explored;which all lead to a good answer and some useful conclusions are found by vibration analysis with the use of pseudo-excitation method on this system.Firstly, based on the model of traditional input of frequency domain method, stationary single excitation and multi-excitation random input by pseudo-excitation method are established. In time domain analysis model, regular stationary time domain input model and shift unstationary input model are established, which pave the way for the following further analysis.Secondly, man-vehicle-road model is established. Based on the magnetorheo logical fluid shock absorber, a fuzzy-controlled semi-active suspension which is used to control the vertical acceleration and the vertical speed of car body and a optimal-controlled semi-active suspension which is used to control the vertical acceleration of human body, the vertical acceleration of car body, the suspension working space, the tyre dynamic displacement are designed. Afterwards, some Matlab programs for the system with control system against road are composed and the numerical simulation for the system in different working conditions is carried out. The results show that the performances of semi-active suspension excel that of traditional passive suspension in the ride comfort. We also conclude that the force between vehicle and road is deressed. It is useful to improve the vibration behavior of road.Lastly, the vertical model of vehicle dynamics is deduced by pseudo-excitation method. The correlation between time and spatial frequencies is derived. The transient PSD of vehicle in nonstationary random vibration is obtained. The road induced random response of a man-car model is explored. As a result, it is high efficient to solve the vibration problem of vehicle, especially to solve nonstationary random vibration of vehicle by pseudo-excitation method and it is also easy to calculate by that method. It has a certain reference to researchers.In this paper, two innovative thinking in man-vehicle-road system with semi-active control against road are as follows:(1) For different vibration models, fuzzy-controlled semi-active suspension and optimal-controlled semi-active suspension are designed. The controllers can effectively eliminate road response of such a system in different working conditions, and the correspongding results can be used as reference for similar control problems of other man-vehicle-road system.(2) Vibration of the man-vehicle-road system in uneven speed is analysed with pseudo-excitation method. The correlation of PSD and speed,space frequency is got. And the correlation of acceleration mean square and speed is obtained. Those results are meaning for practical engineering.