Research On String Stability Of Heterogeneous Autonomous Leader-Following Vehicle Platoons

The cars are known as ‘the machine to change the world'.On one hand,the invention of the cars largely brings great convenience to human beings and improves convenience,comfort and freedom of the human travel.On the other hand,the number of cars have been a sharp increase with the advance of science and technology and rapid development of economy,which makes a series of bad consequences such as the traffic jams,the economic and social function decline,environmental pollution and so on.The vehicles are influenced by some external disturbances such as vehicle acceleration disturbance,uncertainties of wind speed and parameters and so on in most time.At the same time,vehicle actuator saturation even dead zone is inevitable in almost all applications due to the physical limit of the vehicles actuators and the consideration for the passenger safety in actual traffic.Once the actuator saturation even dead zone is without control,the consequences will be serious,which will lead to a decline even instability of vehicle performance.Therefore,how to slow down the effect of actuator saturation and dead zone is particularly important for heterogeneous autonomous vehicle platoons.This paper regards heterogeneous autonomous platoons as the research object and designs corresponding platoon models and controllers according to the external different conditions of the platoon in order to realize the stability of the heterogeneous autonomous platoons.The main works are as follows:Firstly,the paper analyses the sliding mode control and the basic principle of adaptive control based on Lyapunov Theory and designs the specific strategies of the spaces between platoons to increase traffic flow and road density.Secondly,the paper establishes specific platoon models and designs controlled fixed spaces strategy between the platoon and a new adaptive controller to ensure each vehicle's stability and the stability of the platoon in a limited time in view of the heterogeneous autonomous platoons subject to external disturbances such as vehicle acceleration disturbance,wind speed,parameter uncertainty and middle uncertainty caused by the network during high mobility,high noise environment.The conclusions are verified by numerical simulations and experiments.Thirdly,the paper fully considers the heterogeneous autonomous platoons subject to actuator saturation and external bounded unknown acceleration interference(external disturbance supremum and certainly boundary is not known),and sets up corresponding second order control model.It designs suitable fixed spaces strategy between the platoon and adaptive distributed controller combined with the adaptive sliding mode control technology to compensent the consolidation effect of external interferences.By establishingthe Lyapunov functions,the finite stability of the vehicle and the platoon stability of are proved and the effectiveness of the method is proved.Forthly,the paper fully considers the actuator saturation dead zone,and external bounded unknown acceleration interference of heterogeneous autonomous platoon based on the network.It establishes platoon longitudinal control models,designs the second order distributed sliding mode controller of the follower platoon and adapts fixed spaces strategy between the platoon to improve the traffic density and traffic flow.Based on the theory of Lyapunov stability,the queue stability of the platoon is proved and verified by numerical simulations and experiments.In conclusion,the paper studies the effect of outside interference,actuator saturation and actuator dead zone for heterogeneous autonomous platoon and designs suitable corresponding controller to ensure finite stability of the vehicle and the platoon stability.