Research On Automatic Anticollision System Of Automobiles

Today traffic accidents have become a social problem all over the world and manyresearchers are paying remarkable attention to the advanced safety technologies forimproving the situation. As one of the important technologies, the vehicle collisionavoidance system based on ITS(Intelligent Transportation System) has beeninvestigated in many countries. However,till now some key problem in this fieldhaven’t been well resolved. So that the more theoretical and technical study on vehiclecollision avoidance rate and promoting ITS application in China. In this dissertation,study on vehicle forward collision avoidance system has been conducted based onvehicle system dynamics and control theory. The study covers with the systemdynamics modeling and control algorithm, the estimation of safety distance, theacquisition and process of vehicle and environmental information and the developmentof the vehicle test system. Finally, we simulated the system using the MATLABsoftware.Firstly,the specific parameter values of the automatic anticollision controllingsystem is identified. The outline of the vehicle forward collision avoidance system isdesigned in this dissertation. Based on it, the key technologies involved in the systemand their relationship are determined. As the basis to realize and evaluate the systemfunction, the dynamics modeling of the collision avoidance system is studied.According to the dynamic characteristics of the test vehicle system and the actuatorstructure, a longitudinal dynamics model which can bu used to simulate the dynamiccharacteristics of the collision avoidance system under some complicated workingconditions has been developed. Furthermore the veracity and simplicity have beencompromised in the model. Base on the analysis of the pilot entire braking process, anew safety distance model which is established on the intention assumption of drivers’distance keeping maneuver in actual traffic situation is proposed. The safety distancemodel can be described as ds=1.4vc+2.5. The vehicle speed vcis obtained from the carmounted sensor.Based on the researchu mentioned above, the control system of the collisionavoidance system is developed.The robust controller of vehicle collision avoidancesystem consists of a lower-layer controller, which is designed based on MMC(ModelMatching Controller)method and an upper-layer controller,which is desingned based onLQ(Linear-Quadric) optimal contro theory and PID fuzzy contro theory. Theupper-layer is dynamic tracked since the actual distance between the car and in front ofgoal a safe distance from the shop safe distance from the model; the lower-layer isaccurately achieved the desired acceleration. The robust controller of vehicle collisionavoidance system are implemented and the external disturbance has smaller effect onthe control volume.Finally, we have designed a real vehicle hardware and software platform. Throughcomputer simulation and vehicle experimental test, the system function and itscorresponding research achievements are investigated. From the simulation figure ofspeed and time and the simulation figure of distance and time, the automatic collisionavoidance system has a good effect on vehicle speed and safe distance control. From thesimulation diagram of the vehicle speed to follow of the cruise control system we cansee, the overshoot of the system is20%,and the settling time is40second, so the control effect of adaptive fuzzy PID control method meets the needs of control requirements.And from the simulation diagram of the vehicle speed to maintain we also can see, Thefluctuation range of the vehicle speed is much smaller than the control error of0.02under the circumstance of the system outside interference power, as the result,thesystem can achieve the desired control effect.The results show that the automatic collision avoidance system has realised itsfundamental system function, and has valuable effects on many aspects such asimproving the active safety of vehicle, reducing the road accident rate, cutting down theloss caused by collision accident, guaranteeing safety driving and so on.