A Study Of Parameters Matching Of A Heavy-tractor Air Suspension

As a typical nonlinear system,air suspension which cooperates with heightcontrol valve has an ideal nonlinear elastic characteristic.It has the advantages oflow natural frequency,adjustable stiffness and height,good ride comfort under theconditions from no-load to full-load.This paper is based on a prototype of heavy traction vehicle with airsuspension.Firstly,the constant pressure characteristic curve and dynamiccharacteristic curve of air suspension are fitted,according to the data provided byFirestone Company.Shock absorber speed characteristic curve is obtained throughbench test.Secondly,rigid-flexible coupling model of air suspension and leaf springand the virtual prototype model of the vehicle are constructed.Based on harmonysuperposition method,the random road model is built.Then,ride comfort simulationanalysis is conducted under conditions of vehicle random road surface spectrumand pulse road surface spectrum.Lastly using RSM(response surfacemethod),weighted acceleration root mean square values of the driver and the saddleare fitted. With the same method,a model of RSM approximate quadraticpolynomial between air suspension stiffness and shock absorber damping isestablished.Then,using NSGA-II in Isignt,the above objective functions areoptimized and analyzed. The optimal solutions of the air suspension stiffness andshock absorber damping are obtained.By conversion,the solutions are fitted into airsuspension dynamic characteristic curve and shock absorber velocity characteristiccurve.At the end of this paper,the optimized and matched curves of air suspensiondynamic characteristic and absorber velocity characteristic are substituted into thevehicle dynamic model in ADAMS/Car for ride comfort simulation analysis.Bycomparison with the unprocessed model,the optimized scheme can improve the ridecomfort of tractor significantly.So the feasibility of this optimized scheme isverified.