Dynamics Modeling And Analysis On Lateral Stability Of Articulated Wheel Loaders

Due to the frequently changes of body structure,load and centroid position of articulated wheel loaders,as well as it often works on unstructured ground,it has poor lateral stability and is prone to rollover.Researches show that the active control is the most effective way to avoid accidents.To realize active control,the mechanism of the rollover instability needs to be researched by dynamics analysis of articulated wheel loaders.Based on this,this paper built a 6 degrees of freedom(DOF)dynamics model of articulated wheel loader,the reliability of the model was verified via comparing the experiments carried on by a physical prototype model and a virtual prototype model.Meanwhile,the lateral instability mechanism of articulated wheel loader was analyzed based on the dynamics model.The detailed works of this paper are as follows:(1)Built a 6 degrees of freedom lateral dynamics model of the articulate wheel loader;This paper discusses the structural characteristics of articulated wheel loader body,and analyzes the changing law of the body posture in the 1st and 2st stages of instability of articulated wheel loader.Moreover,a novel dynamics rollover model with 6 DOF was proposed,which was used for modeling the instability process of an articulated wheel loader based on Newton-Euler method and build the tire model by magic formula.(2)Verified the accuracy of dynamics model by comparison the experiments carried on by a physical prototype model and a virtual prototype model;A 1:5 scaled-down physical prototype wheel loader and a virtual wheel loader were built in Adams.multi body simulation software are constructed as experimental platforms,the scaled prototype model has key structures of articulated wheel loaders(articulated steering,rear axle and working devices)and can achieve multiple conditions of experiments.Experiments are conducted under four typical working conditions(obstacle passing;obstacle passing while turning;turning on ramp;obstacle passing on ramp)to verify the reliability of the proposed dynamics rollover model.The dynamics model accuracy is investigated via a rotation motion under a constant steering angle under the critical state of rollover.(3)Analyze influence of different motion parameters on the lateral stability of articulated wheel loader.Taking“steady state margin angle(SSMA)”as the lateral stability index of articulated wheel loader,the prototype model as research object,the 6 DOF dynamics model is used to analyze the influence of different slope,steering angle and forward speed on dynamics lateral stability of wheel loader.With the changes of steering angle and forward speed,the stable working area of wheel loader based on SSMA is obtained,which provides a theoretical basis for lateral instability warning and active control.This paper provides a theoretical basis for the construction of active control system.Furthermore,the 6 degrees of freedom dynamic model can also be used as a computational model in early warning and active control models.