Distributed Control Method Of Vehicle Platoon Based On Single Vehicle Cooperation And Multi-vehicle Coordination

The vehicle platoon is a multi-agent system composed of homogeneous or heterogeneous vehicles.Because the vehicles in the platoon can coordinate with each other,it has the advantages of improving the capacity of expressway system,reducing traffic accidents and reducing fuel consumption,etc.Currently,it has been widely used in various transportation tasks.However,single vehicle has the structural characteristics of strong coupling and high non-linearity,and an efficient coordination between multiple vehicles is required.Therefore,this paper proposes a platoon distributed control method based on single vehicle cooperation and multi-vehicle coordination to achieve the stability and safety of the vehicle platoon system,as follows:Firstly,to ensure the effective control of the system,a three-degree-of-freedom vehicle dynamic model and a kinematic model are established based on the necessary assumptions.Besides,the dynamic model is established considering the coupling effect of lateral and longitudinal direction.The lateral kinematic model is based on the preview mechanism,and the longitudinal kinematic model is based on the constant time headway(CTH)longitudinal inter-vehicle distance.Secondly,in order to achieve the multi-objective of the following vehicle's lateral stability and fast tracking of the reference road centerline,while maintaining a safety distance.A lateral and longitudinal cooperative control strategy of the vehicle based on model predictive control(MPC)and sliding mode control(SMC)is proposed in this paper.On the basis of mastering the principles of MPC and SMC,the design process of MPC-based lateral controller and SMC-based longitudinal controller are expounded in detail,and the Lyapunov stability of SMC controller is proved.Thirdly,on the basis of the cooperative controller,for the problem of multi-vehicle coordination,a distributed coordinated control strategy based on the composite safety distance of the platoon is proposed.By introducing the improved driver-preview(IDP)safety distance model into CTH safety distance model,a composite safety distance model is constructed.The switching process of the safety distance model is given and and a safer distance is selected.At the same time,the implementation steps of distributed coordinated control strategy are elaborated in detail,and the method of increasing inter-vehicle distance after switching the safe distance model is given.Finally,aiming at the emergency braking condition of the front vehicle,combined with the cooperative control method,the platoon lane-changing strategy is proposed.Furthermore,the method of quintic polynomial is adopted to generate the trajectory of lane-changing,and the reasonable velocity constraint and passenger comfort constraint are added to transform this problem into an optimization problem with the constraint condition.The optimal lane-changing trajectory is obtained by solving the objective function.At the same time,the minimum initial longitudinal safety distance between the lane-changing vehicle and the front vehicle is calculated to avoid the collision between them during the lane-changing process.In the MATLAB/Simulink simulation environment,the model and controller of the platoon system are established,and the numerical simulation of various working conditions proves the feasibility and effectiveness of the above-mentioned theory and method of platoon distributed control.The research results of this paper are devoted to improving the safety of platoon driving under expressway,and providing the basic theory and method reference for the realization of single vehicle cooperation and multi-vehicle coordination control of the vehicle platoon.