Research On Coordinated Control Of Longitudinal And Lateral Movements Of Intelligent Vehicles

Intelligent vehicle is a high-tech fusion system integrating computer science,vision sensing,multi-information fusion,communication,automatic control and other technologies.With its advantages in solving traffic safety and improving road traffic efficiency,vehicle intelligence has become the frontier of vehicle research in the future.Trajectory tracking is one of the key technologies to realize the intelligentization of automobiles,which is directly constrained by the maneuverability of the vehicle's actuator and is closely related to the stability of the body.The existing trajectory tracking strategies have deficiencies in the longitudinal and lateral coordinated control and vehicle stability analysis.The research objective of this paper is to combine the lateral path tracking control of the intelligent vehicle with the longitudinal speed tracking,and design the integrated tracking control system to make the vehicle can pass the specific curve as quickly as possible on the basis of stable trajectory following.First,the vehicle dynamics model is established in MATLAB/Simulink in this paper,which provides the model basis for the design of the trajectory tracking controller,mainly including the Lateral,longitudinal and wheel rotation dynamics models of vehicles with seven degrees of freedom and tire model.Second,Based on Model Predictive Control(MPC)theory,the integrated tracking control system of intelligent vehicle was developed,including the tracking controller of lateral path and the tracking controller of longitudinal speed.First,the basic theory of Model Predictive Control is introduced,and the key issues in the design of trajectory tracking control system are deeply analyzed;A lateral path tracking controller based on LTV-MPC is designed.By optimizing the objective function and dynamic constraint conditions,the vehicle's adaptability to the real environment is improved while ensuring that the vehicle can track the desired trajectory stably at high speeds.The expected speed decision model based on preview theory and the longitudinal speed tracking controller based on MPC are designed to solve the problem of maximum speed decision and speed tracking in longitudinal motion control.In the end,an integrated tracking control system is designed to realize the research objective of fast cornering on the basis of stable trajectory tracking by means of the coordinated control of longitudinal and lateral motion.The effectiveness of the three types of tracking controllers designed has been verified by Car Sim-Simulink co-simulation based on different algorithms.Then,this paper establishes a hardware-in-the-loop(HIL)test platform based on NI PXI,including Lab VIEW real-time control model and embedded code generation model.The realtime control model includes vehicle model and CAN communication receiving and sending model.The algorithm code of the lateral path tracking controller is generated by the neural network algorithm,and it is downloaded to the real ECU.The experimental results of different maneuvers verify the real-time and effectiveness of the designed trajectory tracking control algorithm in the actual ECU,and the robustness of the algorithm to vehicle speed changes.Finally,this paper developed a four-wheel drive electric experimental vehicle platform,including the hardware design and software development.considering the limitation of experimental conditions,the trajectory tracking algorithm model designed in this paper is simplified,and it is verified by real vehicle based on the experimental vehicle platform.The experimental results further verified the trajectory tracking control proposed in this paper.