Research On Cooperative Straight Driving Control Strategy Of Intelligent Connected Vehicles At Unsignalized Intersection

Intelligent connected vehicles are the main component of the intelligent transportation system,and research on intelligent connected vehicle technology is helpful to solve the problem of traffic congestion.Among them,the platoon driving control technology of intelligent connected vehicles is the focus of current research.There have been many studies on the lane change control between parallel platoons in the same direction,but there is a lack of research on the longitudinal coordinated control between straight platoons in the crossing directions.The research of this article is based on the Car-vehicle Coupling Mechanism and Collaborative Safety Method(No.2018YFB1600502)of the Ministry of Science and Technology,combined with the longitudinal control of the vehicle platoon and the intersection conflict resolution strategy.At the same time,using the vehicle platoon in two crossing directions as the research object,a distributed collaborative control architecture is proposed.Then,we begin to study the coordinated control strategy of platoon at unsignalized intersections.Firstly,the unsignalized intersection road is selected as the target scene,the conflict scene of the platoon coordination and straight travel is divided,and the overall framework of the coordination platoon and straight travel is proposed,based on the characteristics of the intelligent connected vehicle system.According to the position of the conflict,the road intersection traffic scenes are divided into four types,which are classified as conflict and non-conflict situations.In order to enable the platoon to drive cooperatively in four driving scenarios,we propose an overall framework with the communication decision-making layer and the control layer as the design basis.Then,four kinds of communication topologies for information flow are designed in the communication decision-making layer.Different topological structures determine whether the information of the decision-making vehicle can be received by the following vehicles,and a conflict resolution strategy is also formulated as the coordination between the intersection platoons.In each straight forward switching mode,the decision-making vehicle uses the objective optimization function to plan the optimal control amount of the vehicle,and adjusts the speed and distance between the vehicles in each platoon,so that the two platoons can safely pass through the conflict area at the intersection.Secondly,in the platoon cooperative control layer,a hierarchical control method is adopted,and the upper controller and the lower controller are designed respectively.The upper controller outputs the desired acceleration to control the longitudinal movement of the vehicle.The design of the lower-level controller aims at following the desired acceleration output by the upper-level controller,and uses PI control to synchronously convert the acceleration into throttle opening and brake pressure,which output to the dynamic model.In addition,an Extended Kalman Filter state estimator is designed to preprocess the information that input to the upper controller,and also to realize the prediction and optimization of the state at the next moment.Finally,a joint simulation experiment of Pre Scan based on Matlab/Simulink was carried out.By building specific scenarios and control algorithm modules,it is easy to use different working conditions to complete the simulation verification of the platoon cooperative straight driving control strategy.The simulation results show that the designed control strategy can ensure that the two platoons are coordinated to go straight through the unsignalized intersection without collision.