Stability Analysis And Synthesis Of Autonomous Vehicle Platoon With Communication Delays

Autonomous vehicle platoon drives efficiently with expected vehicle spacing through wireless communication between vehicles,which can effectively alleviate traffic congestion,reduce the risk of traffic accidents and reduce fuel consumption and exhaust emissions.However,there is time delay in wireless communication among vehicles,which weakens the stability of autonomous vehicle platoon.The existing methods for the stability analysis of autonomous vehicle platoons under the time delay and the accurate time-delay boundary solution are time-consuming and computationally large.In addition,the research literatures on vehicle platoon control under time delay focus on the analysis and containment of the negative effects of time delay on the system,but how to exert the positive effects of time delay on the control performance of the platoon is rarely involved.Therefore,this paper carries out the system stability research and synthetical analysis for autonomous vehicle platoon under the influence of communication delay,including the rapid solution of accurate delay stability boundary under the influence of single delay and multiple delays and the design of proportionalretarded controller and the right-most pole assignment.The specific research work and contributions are as follows:(1)For the homogeneous vehicle platoon system under the influence of single time delay,the sufficient and necessary conditions for internal stability and the platoon stability conditions are proposed,considering the delay only in the acceleration information channel and the delay in the position,speed and acceleration channels respectively.Firstly,the closed-loop control system of the vehicle platoon under the influence of single time delay is constructed for the above two situations.On this basis,the system characteristic equation is analyzed by direct method,and the complete and exact delay stable boundary is given.Then,by analyzing the error transfer function,the platoon stability condition of the platoon is given.Finally,the correctness of the proposed stability analysis method is verified by simulation.(2)For the homogeneous and heterogeneous vehicle platoons under the influence of multiple time delays,the closed-loop control systems of vehicle platoons are constructed respectively,and the complete and exact time-delay stable boundaries of the systems are given.Firstly,the closed-loop control system of vehicle platoon is decomposed into several subsystems.On this basis,the traditional cluster treatment of characteristic roots method is improved based on Bistritz table,and the steps of the frequency domain scanning are optimized.The computational cost of time delay boundary solution is greatly reduced,and the sufficient and necessary conditions for system stability are quickly solved.Finally,the correctness of the proposed stability analysis method is verified by simulation.(3)For the homogeneous vehicle platoon system,A proportional-retarded controller is constructed to play the positive role of time delay on vehicle platoon control performance,and a right-most pole assignment method oriented to the controller is proposed.Firstly,the characteristic equation of the system is analyzed by Cauchy-Riemann equation,and the rightmost pole of the system is assigned to improve the response speed of the system.Then,it is proved that the right-most pole cannot be arbitrarily assigned,and available assignment range of the right-most pole assignment is deduced.Thus,the right-most pole assignment strategy which can maximize the response speed of the vehicle platoon is constructed,and the design guidelines of controller gains is given.Finally,the advantages of the proportional-retarded controller in speeding up the response speed of the vehicle platoon and suppressing highfrequency disturbances are verified by simulation.