Research On AWS System Dynamics Of Multi-axle Vehicle

All wheels steering technology of multi-axial vehicles,one of technologies to be perfected nowadays,aims to enhance maneuverability of heavy-duty vehicles.It can provide smaller steering radius as well as various steering modes and improve vehicles adaptability to complex road conditions by reasonable control on steering angle of each axle.The target of this thesis is an 8×8 heavy-duty vehicle.Based on analysis of four axes vehicle steering principle and Adams,this article did research on Tire force characteristics under different steering modes.What's more,a new steering system was designed and the influence of centroid position on vehicle steering characteristics is investigated.First,the Ackerman theorem and four wheel steering technology aimed to enhance the high speed stability and low-speed maneuverability was introduced.The all wheel steering principle of four axes vehicle is analyzed and the corresponding 2DOF dynamic model of vehicle was deduced.On this basis,the equivalent wheelbase and stability coefficient of four axle vehicle are deduced,and the transient response of the first two axle steering of the four axle vehicle is analyzed.The effects of mass center position,tire stiffness and steering mode on steering characteristics are analyzed.Then,the virtual prototype model of four axle all wheels steering vehicle is established according to vehicle quality and structure information.Tire force characteristics of vehicles in different driving modes was analyzed under different steering system structure limits.Based on multi body dynamics analysis results,a design scheme on basis of an electronically controlled hydraulic all wheels steering system driven by wire was proposed to improve the maneuverability.And the steering rod system was optimized.What is more,the control strategy of the scheme under different steering modes is analyzed.Validated the rules of tire force in different steering mode by using the prototype of vehicle.