Platoon Control Of Unmanned Ground Vehicles And Diagnosis And Defense Of Network Attack

With the continuous growth of road freight transportation and household car ownership,the pressure on road traffic is also increasing,and problems such as serious road congestion,frequent traffic accidents and environmental pollution need to be solved urgently.As one of the important applications of the combination of Intelligent Transportation System and Internet of Vehicle technology,the platoon control technology of unmanned ground vehicles is a hot research topic at present,which can effectively alleviate problems such as traffic congestion and environmental pollution,and reduce traffic accidents.The unmanned ground vehicle platoon was taken as the research object of the thesis,in order to improve the safety of the unmanned ground vehicle platoon,aiming at the safety problems that the platoon was prone to collision accidents when driving on the road with low adhesion coefficient,improved constant time gap algorithm was designed by the thesis.For the platoon’s communication network was attacked,the attack detection and recovery mechanism using the Set-membership-Kalman filter algorithm was proposed,then the attack diagnosis method using support vector machine and the defense control method of tampering information attack using switching between control algorithms were proposed.First,for the safety problem that the unmanned ground vehicle platoon was easy to cause collision accidents due to the small driving distance when driving on the road with low adhesion coefficient,a calculation method of the minimum safe distance considering the road adhesion coefficient and the acceleration information of the preceding vehicle cannot be continuously received by the own vehicle was proposed.The constant time gap(CTG)algorithm of the desired car distance algorithm was improved.Then,the platoon control system was designed with a layered structure,and the value condition of the controller gain in the upper control is obtained by analyzing the stability of the platoon.Finally,a 4-vehicle platoon is simulated and verified,and the results show that,the string stability of the vehicle platoon can be guaranteed and collision between two cars can be avoided by the improved constant time gap algorithm when the road adhesion coefficient was low.When the own vehicle cannot obtain the acceleration information of the preceding vehicle and the preceding vehicle brakes urgently,the platoon using the improved constant time interval algorithm is in the driving process.The maximum vehicle distance deviation rate of the platoon used the improved constant time interval algorithm was 19%,which is lower than the maximum vehicle distance deviation rate of 22.27%when applying the traditional method,and the vehicle distance error eventually converges to zero with time.The maximum value of the acceleration of the vehicle in the driving process of the platoon used the improved constant time interval algorithm was0.75m/s~2,which is lower than the maximum value of the acceleration0.91m/s~2 in the traditional method.It shows that the stable driving of the platoon can be ensured by the improved constant time interval algorithm and have better ride comfort.Second,for the network attack problem in the platoon control system,the common network attacks are classified according to the purpose and means of the attack,and the impact of tampering imformation attack,replay attack and denial of service attack on the platoon control system were analyzed,the general attack model was summarized.Then,for short-time tampering attacks and denial-of-service attacks,under the assumption of mixed noise,an attack detection and recovery mechanism based on Set-membership-Kalman filtering algorithm was designed.Finally,it was verified by simulation that the proposed attack diagnosis and recovery method can accurately detect the attack on the system,at the same time,it can effectively alleviate the adverse impact of the attack on the system and the security of the system was guaranteed.Finally,in order to solve the problem of long-term tampering attack on the platoon control system,based on the attack diagnosis and recovery mechanism proposed in Chapter 4,the defense control method of switching between control algorithms was proposed.The designed controller switching mechanism can switch the vehicle controller from PID controller to MPC controller according to the attack detection and diagnosis results,and the stability of the system was proved by Lyapunov stability theory.Finally,the effectiveness of the proposed method is verified by software simulation.The results show that when the system was tampered with for a long time,the maximum vehicle distance error of the platoon using the switching controller method was 0.16m,and there was no deviation in the process of tracking the speed of the front vehicle.Using only the recovery mechanism based on state replacement,the maximum vehicle distance error of the team during driving was 0.21m,and there was a deviation of 0.2m/s in the process of tracking the speed of the front vehicle.It shows that the platoon using the defense control method proposed has better following performance than the platoon using only the recovery mechanism of state replacement.The negative impact caused by attack was reduced by the method.