Determination of the stochastic kinematic excitation of the car by the real profile of the road surface

Abstract

In the research of model vehicle suspensions for the sake of the simple mathematical notation, in the equations it is assumed that the kinematic excitation is harmonic. This type of excitation is not present in the real exploitation condition of vehicles. In the effect the simulation testing of the suspension is only the estimate - it is not the equivalent of the real road conditions. The crosswise irregularities of the road surface (the profile) are random. The vehicle moving on such a road is excited with a stochastic excitation. The complete description of such process is very difficult. With its description it is assumed that their character is stationary in wide sense and ergodic. The correctness of such assumptions is confirmed by the research conducted by many research centres. Such an assumption requires tests on long distance which requires long measurement time. It may be assumed that mathematical condition of time approaching the infinity [...] is met. Most often the stationarity of the vibration signal in wider sense and its ergodicity is assessed with use of static signals by means of mean value and autocorrelation function. AIso the square mean, probability density and the power spectral density are calculated. The calculated values are used for description of stochastic excitation that are the effect of the irregularities of road surface.