Research On Adaptive Fault-Tolerant Control For Intelligent Connected Platoon System Under Fault Conditions

Along with the automobile industry in intelligent,electric,network and sharing of the transformation drive,the technology innovation and system construction of intelligent connected vehicle(ICV)industry have become a national development strategy.As the key technology field of ICV,intelligent connected vehicle platoon system(ICVPS)deeply integrates advanced control,communication computing and unmanned vehicles.It has significant advantages in improving traffic efficiency,driving safety and reducing energy consumption.However,the external disturbances and fault in the physical layer seriously affect the closed loop platoon system(CLPS)’s control performance and string stability(SS).The communication fault induced by malicious cyber attacks always threatens the driving safety of ICVPS.To solve the above issues,this dissertation carries out the research on adaptive fault-tolerant control(FTC)to improve the system security and control stability of ICVPS.The research contents of this dissertation are as follows:1.The distributed adaptive FTC method is studied for the ICVPS with actuator fault and actuation input saturation.Firstly,for reducing the conservatism of the traditional spacing policy,the quadratic spacing strategy based on the fault factor is introduced to ensure the strictly SS,in which fault and disturbances decrease layer by layer along the length of ICVPS.Then,based on the adaptive updated laws,the distributed adaptive finite time FTC scheme is designed to compensate the influences of fault,saturation and the disturbances.The fault tolerance ability and stability performance are guaranteed.Finally,the sufficient conditions that ensure the strictly SS are given and proved.Also,based on the Lyapunov stability theory,the CLPS is proved to be globally finite time stability.2.With improved exponential spacing(ES)policy,a distributed adaptive finite time FTC method for the ICVPS is studied.First,different from the traditional spacing policy,by introducing the fault factor and the leader’s velocity information,the improved ES policy is presented to promote the traffic flow capacity and guarantee the SS.Furthermore,under the estimated information of the designed nonlinear observer,a distributed adaptive finite time FTC scheme with the unknown parameters adaptive updated laws is developed to suppress the influence of actuator fault,input saturation and disturbances.Then,the globally finite time stability of the CLPS,the SS and the traffic flow stability are guaranteed through theoretical analysis.3.Considering ICVPS with the multiple communication faults induced by malicious cyber attacks,a distributed adaptive fast finite time FTC scheme in prescribed performance(PP)are investigated.Firstly,the nonlinear state estimator is introduced to ensure the boundability of state signals under communication faults and disturbances.Moreover,incorporating with the improved ES policy in Chapter 3 and asymmetric constraint domain,the string stability,collision avoidance and mobile communication maintenance at high speed can be ensured.Based on the hyperbolic arc-tangent asymmetric barrier Lyapunov function,a distributed adaptive fast finite time FTC strategy in PP is designed to improve the convergence speed and transient/steady state performance of the system with fault.Moreover,the adaptive compensated laws are constructed to achieve communication faults suppression.Thus,the CLPS satisfies the SS and the fast finite time stability performance under PP.4.For the ICVPS with the communication fault induced by malicious attacks and disturbances,the event-triggered based distributed adaptive fixed time FTC method is considered.Firstly,unlike the traditional disturbances observer,a sliding mode based fixed time disturbances observer is constructed to quickly estimate the unknown external disturbances under arbitrary initial conditions.Secondly,under the ES policy and the predecessor-leader following information flow topology,the event triggered based distributed adaptive fixed-time FTC scheme with the fuzzy adaptive laws is designed to reduce the consumption of control energy,improve the robustness of the system and ensure the fast response under the fault.The theoretical analysis proves that the CLPS is ensured to be practical fixed time stability and the SS.Finally,the effectiveness of the proposed scheme is verified by comparative experimental analysis and SUMO-MATLAB joint simulation platform.5.The event-triggered based distributed adaptive fixed-time FTC method in PP is presented for the ICVPS with unknown input dead zone,disturbances and communication fault induced by attacks.Firstly,the predefined fixed-time decaying function and the asymmetric constraint function are introduced for overcoming the shortcomings of existing PP control methods.Then,based on the ES policy and predecessor following information flow topology,the distributed adaptive fixed-time FTC scheme in PP with the fixed-time adaptive laws is designed to realize the fast compensation of unknown dead zone and faults and guarantee the high precision steady-state performance.A bounded exponential decay function is introduced to design the event triggered mechanism,which can avoid the “Zeno” phenomenon of false event triggering and reduce the control energy consumption.Theoretical analysis proves the practical fixed time stability and SS of the CLPS under prescribed constraints performance.