Research On Envelope Of High-speed Unmanned Vehicle And Path Tracking

In civil area,the autonomous vehicles applies technology support for the control of dynamic stability,distance keeping and so on.In military area,the unmanned ground vehicles have the advantages of concealment,replacing soldiers to do some dangerous and so on,which make it popular among many countries.Path tracing is an important part of the autonomous vehicle system,which impacts the dusk conducting directly.Among the studies of the control strategy of path tracking,seldom researchers pay attention to the dynamic performance.And the utilizing of vehicle dynamic during designing the path tracking controller is finite,limiting the speeding up of autonomous vehicles.Focusing on the problem talked about above,the path tracking control strategy will be designed with the point of vehicle dynamic in this paper.The object is pushing the vehicle to the limit during path tracking,and finish the given path with the shortest time.Focusing on the vehicle dynamic,the vehicle dynamic model should established firstly.Considering the objective of this paper and the driving conditions of the test bed,a 7 degree of freedoms dynamic model is established,which describes the tire model with Magic Formula on base of test data.Some characteristics during stable steering is analyzed on base of the dynamic model.And the result can be used to validate the dynamic model.On base of the dynamic model,the “β-ω” portrait is obtained by the method of envelop.The stability limit is described by equilibrium locations.Also,on base of the dynamic model,the G-G diagram is obtained by the method of envelop,which describes the speed limit of the vehicle.The test is held to validate the G-G diagram and validate the method of envelop.The path tracing control method is designed on base of the speed limit and the stability limit,which can be reached by longitudinal control and lateral control respectively.Also the accuracy of path tracking is guaranteed by lateral control.Focusing on the control strategy,a simulation and a test are held to validate the control strategy.The result of simulation and test shows a good performance.