Research On Decentralized Cooperative Adaptive Cruise Control Method Based On Wireless Communication

The adaptive cruise control(ACC)system can effectively alleviate road traffic congestion,improve driving safety and ride comfort.But there are still some shortcomings in the ACC system,such as the inability to deal with more complex urban traffic scenarios and to predict timely the sudden change of speed of vehicles ahead.These shortcomings lead to less safety and an unsatisfactory experience.With the V2X(Vehicle to Everything)technology,the ACC system can be upgraded to a cooperative adaptive cruise control system(CACC).It can have the information shared between vehicles and then rely on the acquired information to adjust the vehicle's motion.Compared with the traditional ACC system,it can make a ride more comfortable and enhance the safety of driving.Based on the optimal control theory,a longitudinal optimal tracking controller for cooperative adaptive cruise control system is designed and a decentralized cooperative adaptive cruise control method is proposed to improve vehicle control and road traffic efficiency.Firstly,the theoretical basis of optimal control is discussed from three aspects as follows: the optimal control theory,optimal tracking control problem and optimal controller design.Then,with the optimal control theory,the distributed longitudinal optimal tracking control problem in the discrete-time cooperative adaptive cruise control system is discussed.When studying the longitudinal control problem of the vehicle,this thesis considers establishing a longitudinal dynamic model containing three state information of vehicle position,velocity and acceleration for vehicles in the CACC system.According to the longitudinal vehicle model,three tracking targets about estimated distance,speed and acceleration of vehicles are constructed.Longitudinal control problem is transformed into optimal tracking control problem based on quadratic performance index,and three contradictory tracking objectives are balanced.According to the optimal control theory,the longitudinal optimal tracking controller is designed to keep the vehicle under control.Finally,a decentralized cooperative adaptive cruise control method based on wireless communication is proposed to suggest the best route for each vehicle,so that the vehicle can pass an intersection without any interruption and minimize the intersection delay.In order to realize vehicle platoon reorganization,a trajectory planning method is proposed to find the optimal trajectory for vehicles,and a method for space arrangement is proposed to quantify the road space and allocate the space to as many vehicles as possible.In order to achieve better vehicle control,a mixed control strategy is adopted.The simulation results show how the proposed decentralized cooperativeadaptive cruise control method based on wireless communication near the intersection effectively improve the throughput of the road intersection,reduce fuel consumption correspondingly,and improve safety and comfort during driving.