Research On Intelligent Vehicle Path Tracking With Dual Delay Subsystem Based On Multi-Model Intelligent Hierarchical Control Theory

As one of the important components of intelligent transportation system,intelligent vehicles can effectively reduce traffic accidents,improve driving experience and reduce driving fatigue.Now it has become a frontier topic and research hotspot in the field of automotive engineering.Among them,vehicle path tracking control is one of the key issues in the field of intelligent automobile research,and it is also the key to realize autonomous driving of vehicles,which has attracted extensive attention from scholars at home and abroad.Intelligent vehicle path tracking control mainly includes longitudinal motion control and lateral motion control.The existing path tracking control research mostly ignores the longitudinal and lateral dynamic coupling characteristics of the vehicle,and only controls the control strategy for a single motion direction,which can not meet the low adhesion road surface and Driving requirements for extreme conditions such as high-speed cornering of vehicles.In addition,there is a time lag in the actual control process of the intelligent vehicle execution subsystem,and its time-delay interference has a significant impact on the performance and stability of the intelligent vehicle motion control.How to realize the vertical and horizontal coordinated control of intelligent vehicles and clarify the influence mechanism of subsystem delay on the tracking of intelligent vehicles is the difficulty and focus of intelligent vehicle path tracking.It has extremely high research value and practical significance.In view of the above problems,this paper combines the National Natural Science Foundation of China’s joint fund project "Intelligent Vehicle Multi-State System Dynamic Behavior Modeling and Collaborative Control Research"(Project No.U1564201),and integrates relevant theoretical foundations at home and abroad to study the inclusion of time-delay The system’s intelligent vehicle vertical and horizontal integrated motion coordination mechanism,and the characteristics of intelligent vehicle complex large system and multi-model intelligent hierarchy theory in solving the problem of distributed complex problems,the intelligent vehicle vertical and horizontal multi-model intelligence including time-delay subsystem is designed.The transfer control strategy is used to study the influence mechanism of subsystem time delay on the intelligent vehicle path tracking system.The main contents are as follows:Firstly,based on the modular modeling idea,based on the basic structure and test data of a test vehicle,the influence of the suspension structure on the dynamic performance of the vehicle is neglected,and the seven-degree-of-freedom vehicle dynamics model is constructed.Based on this,an automatic Subsystem nonlinear dynamics model of steering system and anti-lock braking system structure.The simulations of different working conditions were carried out under typical steering conditions and typical path tracking conditions,and the accuracy of the built dynamic model was verified.Secondly,the intelligent vehicle path tracking control algorithm is designed.Based on the vehicle motion model,the vehicle coordinate transformation model and the vehicle pose model,the virtual path between the real-time position coordinates of the vehicle and the position coordinates of the preview point is constructed,and the desired yaw rate of the corresponding vehicle is derived,and the inverse sliding mode control algorithm is used.The desired yaw rate of the vehicle is tracked and controlled.Again,the stability study of the vehicle subsystem is studied.Based on the atomic system dynamics model,the subsystem time-delay dynamics model is constructed.The stability of the time-delay subsystem is analyzed by the generalized Sturm discriminant theory.The system delay time interval is obtained and the time-delay interference factor is determined.On this basis,the influence of vehicle subsystem controller time delay on vehicle subsystem control precision and control stability under different control parameters,different working conditions and different disturbance factors is analyzed.Then,the intelligent horizontal and horizontal coupling multi-model intelligent hierarchical control architecture of intelligent vehicles is constructed,and the control objectives of the control system organization level and coordination level are clarified.The intelligent vehicle path tracking algorithm based on the desired yaw rate is adopted,and the target control force required for the vehicle vertical and horizontal integrated motion control is obtained.The closed loop controller of the active control subsystem is designed to track the control target.On this basis,the influence mechanism of subsystem time lag on the tracking stability of intelligent vehicles is studied.Finally,the MIL test was carried out,and the designed control algorithm and control model were introduced into the MIL test cabinet and the host computer.MIL tests were carried out under different working conditions,including pure intelligent vehicle path tracking test and intelligent vehicle path tracking including subsystems test.The simulation results and bench test results show that the intelligent vehicle path tracking control system based on multi-model intelligent hierarchical control theory can effectively coordinate the control performance of the subsystem,realize the vertical and horizontal coupling control of intelligent vehicles,and avoid the traditional integrated controller.The “dimension disaster” problem that is easy to generate during design.In addition,when the time delay of the subsystem controller is within the critical time lag,the system time delay has low influence on the control precision and control robustness of the subsystem,and the influence on the control precision and control robustness of the path tracking control system is relatively obvious.And as the subsystem time delay approaches the corresponding critical time delay,the control precision and control robustness of the path tracking control system fluctuate to some extent;when the controller time lag exceeds the critical time lag,the subsystem and the path tracking control system are both it is unstable.The above results are consistent with theoretical studies.