Intersection Slots Coupling Operational Control Method Of Intelligent Vehicle Infrastructure Cooperative Systems

The quantities of motor vehicles are growing.Urban traffic becomes more and more congested.One important reason that leads to the congestion is the uneffciency of the intersection,the heavy traffic is unable to be coordinate by the existing signal control mode.Basically,the performance of one intersection control method is determined by how optimized the spatial resources assignment mechanism is.Traditional intersection control mode,i.e.,the signal control mode,mainly concentrates on guaranteeing the safety of the vehicels,but pays the price of efficiency.I-VICS(Intelligent Vehicle Infrastructure Cooperation Systems)is able to perceive the status of the elements in the road network and control the movements of the CAV(Connected and Autonomous Vehicle)by information interacting.This advantage of I-VICS brings the possibility of realizing on-board,customized,intelligent signal control method.The mechanism of intersection spatial resources assignment can be optimized,and the contradiction between the traffic requirement and traffic form can be resolved.The dissertation concentrates on realizing slots based intersection.The static characters of intersection,characters of signal control methods,different types of vehicles and the operation mechanism of I-VICS are considered to realize the slots based intersection control method.Capacity of the intersection under the condition of saturated slots assigning is analyzed in the dissertation.Vehicle safety criteria of positioning error,communication delay and driver reacting time are dynamically modeled.Based on the capacity and safety analyses,parallel slots based intersection control method is proposed to guide the vehicles for slotting.And then the slots intersection control method is expand to the situation of mixed traffic with CAVs and human pilot vehicles(HPVs).Vehicle movements coupling and intersection control modes coupling mechanisms are deliberately designed within CAV and HPV to realize the slot based intersection under mixed traffic.A simulation environment is developed to simulate and verify the methods proposed in this dissertation.Based on the research works in this dissertation,innovation points are:(1)A novel approach for evaluating the capacity of slots based intersection control method is proposed in this paper.LOOSE(Location Optimization On Sequence Evaluation)algorithm which is implemented in the infrastructure is proposed calculate the target status of the vehicle for it to avoid collision in the intersection.The results of LOOSE would be optimized by COMPACT(Cooperative Optimization Method for Previous Allocation Comparatively Transforming)algorithm with the objective of minimum queue length.And ADAPT(Acceleration Dynamically Adjusting based on Predicted Trajectory)method is proposed to guide the vehicle to reach the target status.By implementing LOOSE and COMPACT algorithms,the situation of saturated slots assignment can be achieved,and the maximum capacity of slots based intersectin control method can be obtained.(2)Positioning error,communication delay in CAV,driver reacting time in HPV dynimically modeling methods are proposed in the dissertation.Dangerous vehicle following scenario is applied to evaluate the influence of Gaussian distribution based vehicle positioning error and communication delay to vehicle safety.And then segmented non-linear braking model is proposed to estimate the driver reacting time.The positioning error and commuinication delay are modeled to help analyze the value of vehicle safe time in the subsequent section 3,and the drvier reacting time is modeled to help establish the signal control process for HPV in section 5.(3)A parallel slots based CAVs real-time coordinating method at intersection is proposed.PCHIP(Cubic Hermite Interpolating Polynomial)based vehicle trajectory predicting method is proposed to allocate the conflicts in the intersection.FCT(First Conflicting Time)and alterable vehicle safe headway are introduced to realize the parallel slots,and to calculate the status the vehicle should reach when it enters the intersection.ADAPT method is applied to guide the vehicle to reach the target status.A double loop FCT mechanism is introduced to guarantee vehicle safety and the performance of the system in heavy traffic.And a minimum vehicle delay criterion is applied by optimizing the target lane of the vehicle to improve the efficiency of the system.Simulation results have showed the superiority of parallel slots method than traditional intersection control strategies.(4)CAV/HPV coorperatively control method based on the parallel slots theory is proposed in this section.Analyses of coupling the signal control slots and parallel slots are made to discuss the process of coordinating the mixed traffic with CAV and HPV.Slots selecting mechanism for HPV is designed based on vehicle movement prediction and slots delay.Driver reacting time based signal control method is applied to determine the start time and the end time of the green time for HPV.The CAV/HPV coorperatively control method is able to solve the problem of performance degrading of intersection parallel slots control in mixed traffic.A four-layer CAVs kinematic simulation framework,which is composed with road network layer,vehicle operating layer,uncertainties modelling layer and demonstrating layer,is proposed in this dissertation.Properties of the intersections are defined to describe the road network.A target position based vehicle position updating method is designed to simulate such vehicle behaviors as lane changing and turning.Vehicle kinematic models are implemented to maintain the status of the vehicles when they are moving towards the target position.Priorities for individual vehicle control are authorized for different layers.Operation mechanisms of CAV/HPV uncertainties,which are defined as position error,communication delay and driver reacting time,are implemented in the simulation to enhance the reality of the simulation.Paralle slots intersection control strategy in multiple intersections is realized and verified in the simulation platform to show the superiority of the proposed method in the dissertation.And the simulation also shows supports of the platform to CAVs kinematic simulation and verification.