Research On All-terrain Active Hydraulic Interconnected Suspension System For Off-road Vehicle

Off-road vehicles are encountering increasingly complex and various terrain and driving conditions,among which the main circumstances are undulating roads,climbing and getting off the slope,side-slope driving,and high-speed driving on the highway.Therefore,based on HIS(Hydraulic Interconnected Suspension),this paper proposes an all-terrain suspension system for the off-road vehicle,which can autonomously adjust the height of the vehicle,increase the approach angle and departure angle of the vehicle,and reduce the absolute roll angle of the sprung mass.With the implementation of this all-terrain suspension system,vehicle will gain high trafficability,safety,and stability.The main points of the paper are as follows:(1)An active HIS hydraulic system that can realize different working modes is proposed.Firstly,it is matched with the 7-DOF vehicle model,and then,a co-simulation model of active HIS and vehicle is established.(2)Different control methods for vehicle height adjustment are deeply studied,through simulation under multiple conditions,a comparative analysis of the fuzzy controller and fuzzy sliding mode controller is conducted.In order to overcome the chattering problem of sliding mode control,a modified fuzzy sliding mode control method is proposed,and its excellent control performance is then verified.(3)The analysis of vehicle rollover forces is conducted,and an active anti-roll control strategy is presented.Through simulation analysis,it is verified that the proposed strategy can improve the safety and stability of vehicle for cornering and side slope driving conditions.Meanwhile,aiming at the problem that the system deviates from the initial state after the active anti-roll control is completed,a comprehensive rollover adjustment strategy for restoring the system state is designed.(4)A comprehensive control strategy for the all-terrain suspension system of off-road vehicle is designed.With the strategy,the suspension can intelligently switch different vehicle height modes,adjust the height of the front or rear axle of the vehicle,and adjust the vehicle rollover gesture according to the environment recognition and manual instructions.Through a simulation under comprehensive working conditions,the effectiveness of the suspension system is verified.In summary,by the research methods of combining theoretical analysis and simulation experiments,this paper establishes the implemental foundation and control strategy of the all-terrain suspension system for off-road vehicle,and makes HIS exhibit more functions,showing relatively high academic value and engineering application feasibility.