Study On The Architecture And Control Strategy For Vehicle Platoon Cooperative Driving System

With the rapid growth of the national economy and the process of urban modernization accelerating,the traffic jams,accidents,environmental pollution and energy crisis problem is getting worse.With control,communications,sensor detection and intelligent computing technology become more mature and smart carriageways collaborative technology gradual improvement,the platoon collaborative driving technology is becoming a new hotspot.The intelligent vehicles composed one or more platoons which have same speed and small vehicle spacing.Under the role of traffic control and interact with people and vehicles,the platoon can achieve some collaborative driving process including autonomous cruise,following,combination,leaving etc,which proposes an efficient,safe,environmental and comfortable people-vehicle-road collaborative driving system.Transportation system is a complex giant system,and the efficient,stable,secure system architecture can better promote the study of subdivision technology.According to the theory of decentralized control hybrid dynamic systems,on the basis of previous studies,this article proposed the hierarchical management of distributed control system architecture that consists of traffic control layer,roadside,communication layer,vehicle management layer and people.In this paper,the system architecture of the vehicle management layer and communication layer was accordingly simplified,and established a CarSim / SIMULINK platoon collaborative driving co-simulation platform,the CarSim software offers only four different vehicle dynamics parameters model,designed unmanned vehicle longitudinal controller and trajectory tracking controller in the SIMULINK software,and expand simulation research based on co-simulation platform under several conditions to test the correctness of the control strategy.To ensure the accuracy of vehicle tracking,using optimal control algorithm design trajectory tracking controller base on the predicted model.The yaw rate response of CarSim model is target,the 2DOF vehicle model as a predictive model,using genetic algorithm to identify the key parameters which consists of yaw moment of inertia and front/rear tire slip stiffness with step steering conditions.Based on the theory of �Preview-Following�,adopted multi-point preview optimal control algorithm to design unmanned vehicle trajectory tracking controller based on lateral displacement deviation,combined with a circular trajectory,double lane track and a comprehensive road trajectory to control the trajectory tracking accuracy and stability of the simulation testing under different speeds conditions.After analyzing the different spacing models from stability of platoon collaborative driving and traffic flow,let the asymptotic stability of platoon collaborative driving as target,designed a PID longitudinal controller based on the speed deviation for leading vehicle.Because of the following vehicle stability was influenced by the velocity changing and spacing fluctuation,but the conventional control methods are difficult to achieve,so designed a fuzzy PID longitudinal controller based on the speed deviation and spacing deviation for following vehicle.Combined with the collaborative driving conditions of constant speed cruising,varied velocity following and merge leaving to verification the controller's accuracy and robustness of the simulation,finally,analysis the simulation results in details.In this paper,the system architecture for the platoon collaborative driving technology for rapid demonstration and application based on existed highway infrastructure and intelligent vehicle highway collaboration technology for reference,established a more sophisticated simulation platform of platoon collaborative driving,the simulation results show:(1)The 2DOF vehicle model after the identification of genetic algorithm,its transient response and trajectory are consistent with CarSim vehicle model under step steering conditions.It can be used to predict complex unmanned vehicle driving state,so laying the foundation of predictive model for the trajectory tracking controller designing.However,empirical model has a certain bias in same condition.(2)The trajectory tracking controller was designed by using optimal control algorithm and predictive model,it has a high tracking accuracy at different target trajectory and speed,so meeting the needs of the actual traveling.In addition,for an initial heading angle deviation,deviation and displacement system disturbance,the controller has better adaptability and robustness.(3)In the simulation study of platoon collaborative driving,the proposed control strategy can better control the target velocity and vehicle spacing,in the dynamic response speed caused by the change,the platoon showed some asymptotic stability in several conditions.