Abstract: In order to investigate the influence of suspension systems on road-friendliness of heavy vehicles,　an optimal controller for improving road-friendliness and a simulation model for comparing road-friendliness of heavy vehicles with active suspension systems based on optimal control strategy and with passive suspension systems are designed. Through simulation, the dynamic tire forces generated by heavy vehicles with an active suspension system and a passive suspension system are obtained, respectively. Road damage criterion including dynamic load coefficient, dynamic load stress factor and the 95th percentile fourth-power force are used for the comparison of road-friendliness with two different suspension systems. The results show that road-friendliness of heavy vehicles with an optimal control strategy is improved by 1.5, 1.6 times on A-grade highways and 1.5, 2.5 times on B-grade highways when using dynamic load coefficient and dynamic load stress factor criterion. Two suspension system shows similar road-friendliness on A-grade highways when using the 95th percentile fourth-power force criteria, but active suspension systems can substantially increase road friendliness on B-grade highways by 2.5 times. It is concluded that active suspension system based on optimal control strategy with appropriate parameters can improve road-friendliness of heavy vehicles.

Key words: Active suspension systems, Control strategy, Road damage criteria, Road-friendliness, Demand evolution, Function evolution, Function innovation, Process model