According to hydro pneumatic suspension mechanical characteristics of multiphase medium, fractional calculus theory is introduced; fractional Bagley-Torvik equation is established on the basis of the motion differential equation. Low pass filter of Oustaloup algorithm is designed to obtain the numerical solution of nonlinear fractional differential equation. The selection of optimal order is transformed to the univariate optimization problem; the mean of difference square is established to evaluate the target. The fractional theory, experiment, integer order simulation data are compared by building the proportional test bench and simulation model. This paper alters the excitation frequency and amplitude to observe changes in optimal order times and error trend. Experimental results show that the suspension in the excitation of frequency 1Hz and amplitude 5mm, when fractional times get 0.912, it better reflects the motion characteristics. Optimal fractional-order decreases with the increase of the excitation amplitude and frequency and finally stabilizes. In the high-frequency vibration it tends to be 0.9 fractional times and in the high-amplitude vibration it tends to be 0.86. In multiple excitations of different frequency and amplitude, fractional error is all less than integer-order result; it demonstrates the effectiveness of fractional calculus in the hydro-pneumatic suspension.
Sun Huilai Jin Chun Zhang Wenming Li Hao Tian Haiyong .
Modeling and Experimental Analysis of Hydro-pneumatic Suspension Based on Fractional Calculus[J]. Journal of Vibration and Shock, 2014, 33(17): 167-172
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