Horizontal And Vertical Motion Control Of Electric Intelligent Vehicle

With the increasingly serious problems of traffic safety and travel efficiency,many countries in the world are actively developing smart vehicle technology.As one of the core technologies in this field,vehicle motion control has been paid much attention.At present,most of the horizontal and vertical control strategies are difficult to improve the ride comfort of the vehicle without guaranteeing high accuracy tracking of the expected speed.Secondly,they also have problems that the change of speed and curvature of the road has a greater impact on the accuracy of the path tracking.To solve the above problems,this paper presents a longitudinal control strategy based on driving intent and a lateral control strategy with adaptive preview distance,and designs a coordination strategy based on the coupling relationship between the longitudinal and horizontal directions.The main contents of this paper include:1)Establish the lateral and longitudinal dynamic model of the vehicle and the lateral driver preview model under reasonable assumptions.Then,the driving intent of the driver when tracking the speed is studied in depth,and a longitudinal speed following control strategy considering the driving intent is designed based on fuzzy control and PID control.Secondly,under the framework of preview following theory,a transverse path tracking strategy with adaptive preview distance is designed by using sliding mode control method.Finally,through the joint simulation of MATLAB/Simulink,Carsim and AMEsim,it is shown that the longitudinal control strategy designed in this paper can improve the ride comfort of the vehicle while guaranteeing high-precision tracking of the expected speed.The horizontal control strategy designed in this paper can track roads with different curvatures with high accuracy while ensuring safety.2)Based on decomposed coordinated control,a structure framework of comprehensive control in both horizontal and vertical directions is constructed.The corresponding coordination strategies are designed for vertical and horizontal control respectively.Considering the influence of vehicle lateral movement on the longitudinal control,a coordinated strategy for expected safe speed is designed.Considering the influence of vehicle longitudinal motion on lateral control,an adaptive calculation method of the target distance based on vehicle speed and road curvature is designed,and the front wheel angle control is modified by considering vehicle turning characteristics in lateral motion.Finally,the simulation verifies that the horizontal and vertical control coordination strategy designed in this chapter can plan the optimal safe speed according to the curvature of the road,and can track roads with different curvatures with higher accuracy under the condition of time-varying speed.3)Finally,this paper builds a hardware-in-the-loop test platform based on NI real-time machine according to the requirements,then controls the whole test process through Veristand,and processes the experimental data.The experimental results show that the comprehensive control strategy designed in this paper can plan the optimal safe speed according to the curvature of the road,and can improve the ride comfort of the vehicle while guaranteeing the accuracy of speed tracking.At the same time,it is verified that the strategy can track roads with different curvatures accurately and ensure the safety and stability of the control under the condition of time-varying vehicle speeds.