Analysis, Modeling, Simulation And Optimization Of Steering System Of Double-Front-Axle Vehicles

Multi-steering vehicles have been playing an increasingly significant role in society,with their ever-increasing market demand.However,relevant research about multi-steering vehicles is insufficient,facial and incomplete.In view of this, this context dedicated to a more comprehensive study of double-front-axle steering (DFAS) vehicle's steering system.This paper covers the foundation of DFAS steering theory,steering systems structure and its optimization,dynamics analysis of steering systems,DFAS vehicle's linear 2-DOF(two degrees of freedom) vehicle model and its steady-state response.This article first stated the current research of multi-axle steering both at home and abroad,and summed up the previous research work and achievements; also pointed out the underlying difficulties and problems.The author explained the DFAS vehicle steering mechanism and its steering theory,and focusing on the ideal kinematic characteristics of a DFAS vehicle in the course of making a turn, from which the relationship between each steering angle was deduced.Then the author established a whole mathematical model of a DFAS system and its optimization.In order to facilitate the analysis and modeling,the DFAS system was divided into three parts:steering linkage,pendant arm-knuckle arm-straight rod,double pendulum-bar.With a strategy of from partial to overall, establishment of a complete mathematical model of steering system was achieved. An in-depth analysis of the DFAS vehicle's steering procedure was carried out. The author proposed a creative model with the object of minimum 'dislocation distance'.Combined with restraints the original objective function was further improved.And a simple but effective proposal was derived,which is more feasible during application.In the following,the theory of linear 2-DOF vehicle model was applied during the kinematic analysis of DFAS vehicle.This part was built mainly based on the principle of Newtonian mechanics,with the combination of parameters geo-metric and dynamic relationship.Two kinematic differential equations are developed with regard to forces balance along Y-axis and torque balance about z-axis.Those equations were further discussed with their application for multi-axle steering vehicles.At last,based on study of kinematic differential equations DFAS vehicle's yaw angular velocity(YAV) was derived with an explicit expression.The vehicle's Yaw Angular Velocity Gain(YAVG) was chosen as a main factor for the evaluation of DFAS vehicle's Steady-state Characteristics.The expression for DFAS vehicle's yaw angle gain is,in a way,pretty complex.For a qualitative analysis,some necessary simplification and assumptions was made,along with a comparison of YAVG between DFAS vehicle and uniaxial steering vehicle.