Study On Steering System Of Wheeled Off-Road Vehicle With Two Degrees Of Freedom Articulated Body

This thesis is writing based on school-enterprise cooperation project which is thedevelopment of wheeled off-road engineering-oriented vehicle for complexunstructured terrain, considering the a variety of off-road terrain with complexstructure appeared, the off-road vehicles not only has good Obstacle driving stability,but also have higher off-road capability. The steering system is as one of thesubsystems of the off-road vehicle which will directly affect the vehicle’s off-road,security and mobility. This design of wheeled off-road vehicle with2degrees offreedom articulated body adopts active full hydraulic articulated steering system,which has a flexible steering, steering torque, small turning radius, good mobility andso on.The thesis describes the development of the articulated wheeled off-road vehiclesat home and abroad, and the research status of hydraulic articulated steering system,at last stating the content and methods of this study as follows.(1) It is based on the steering geometry to describe the process of articulatedsteering, and established the steering cylinder piston displacement kinematic relationwith front and rear body and whole vehicle, as well as steering dynamic model.Considering the particularity of the vehicle structure, it is necessary for vehicle to dothe correlation analysis on obstacle state, and d through the simulation analysis to findout the main factors that affect the exercise of offset in the direction. In addition,anglicizing the tire related theory to lay the foundation for the back of the steeringload model.(2) According to the actual structure and working principle of the two maincomponents of single valve and steering gear of hydraulic steering system, there HCDsimulation model is established. Combined with the actual working condition, thedynamic simulation mode of steering system is analyzed and we obtained the changesof the displacement, pressure and flow of steering cylinder. Additional, we found thatthe two steering cylinder is not fully synchronous movement, which to do with theofcylinder position arrangement. To verify the correctness of the simulation model,we have carried on the vehicle steering system test, the results show that thesimulation model could reflect the actual working condition. (3) The steering mechanism model is established through using the multi-bodydynamics simulation software LMS Virtual.Lab Motion, which takes into account theinteraction of the steering mechanism and the tires with the ground effects in theprocess of steering, then conducts the co-simulation of mechanical system andhydraulic system With AMESim simulation mode. By analysising the results ofco-simulation and experimental comparatively, it is found that the co-simulationresults compared with the simulation results of a single system, which better reflectthe actual work. In addition, the thesis has carried on the simulation analysis of thetire force; and it is found that the tire lateral force is a major factor which affects thesteering cylinder pressure in the steering movement.