| Due to the higher centroid and the bigger unsprung mass of the unmanned vehicle driven by in-wheel motor,when the vehicle is turning at low speed,the turning radius ratio is large and the mobility is poor;when the vehicle is turning at high speed,the handling stability is poor and the direction control is easily lost.It is necessary to study the handling stability of all-wheel steering military unmanned vehicles.In view of the problem,from the perspective of engineering application,the design and performance simulation of the 6×6 all-wheel steering military unmanned vehicle chassis are studied.The research work is as follows:(1)Firstly,the current development of military unmanned vehicles is reviewed,and the research status of handling stability and multi-axle steering technology of military unmanned vehicle at home and abroad are mainly analyzed.On this basis,according to the performance requirements of the project,the overall design of the chassis for the military unmanned vehicle is put forward.The paper mainly studies the overall layout of the vehicle chassis and the realization of the omnidirectional all-drive scheme,including battery and motor type selection and all-wheel steering system design.The power performance matching design is carried out.According to the results of power performance matching,the matching results are simulated and verified based on ADVISOR software.(2)An independent steering suspension system based on worm-gear drive is designed to realize the all-wheel steering of the vehicle.Based on the built model of a military unmanned vehicle,a nonlinear two degree of freedom mathematical model of three axis military unmanned vehicle is derived.Based on this model,the optimal control strategy of all-wheel steering is put forward.By using Matlab/Simulink software,the vehicle of 6×6 all-wheel steering and three degree of freedom simulation model is established.Under the condition of the same parameter setting,the simulation results of the all-wheel steering vehicle model and the front axle steering vehicle model are compared and analyzed.The result shows that all-wheel steering three-axle military unmanned vehicles have high maneuverability at low speed and good handling stability at high speed.(3)Based on the analysis of the influence of the all-wheel steering technology on the vehicle handling stability,a multi-body dynamics simulation model of the unmanned vehicle is established by using ADAMS/Car software.According to the parameters and hard-point positions of the 3D virtual prototype model,various templates and subsystems of the vehicle are established respectively,which mainly include system templates such as all-wheel steering,suspension,powertrain and body.Then,the corresponding subsystems are established through these system templates and using the communicators to establish the matching relationship between each other.Finally,it is assembled into a simulation model for the handling stability of a military unmanned vehicle.(4)The handling stability simulation test of the military unmanned vehicle’s multi-body dynamic model is carried out,including corner step,corner pulse,and the snake simulation tests.The results of the tests are analyzed,and the handling stability of the military unmanned vehicle is evaluated according to the test evaluation methods.Through a large number of simulation tests,finding out the factors that influence the handling stability of the vehicle and making quantitative analysis,and choosing the best design parameters to optimize the 3D model of the virtual prototype.In the end,the real vehicle test is carried out through trial prototype car to verify the reliability of the simulation test results.It provides a theoretical reference and engineering application value for the study and improvement of the military unmanned vehicles’ handling stability. |
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