Research On Collision Avoidance And Pre-Warning Control And Simulation Test Method Of Vehicle AEB System

With the rapid development of the automotive industry,the number of vehicles in our country has increased rapidly,which has also led to more serious road traffic accidents and brought huge hidden dangers to the life and property safety of the people and society.Vehicle active safety technology with the goal of reducing road traffic accidents and reducing the severity of accidents has become a research hotspot in the vehicle field.The AEB system as an important direction for development of vehicle active safety technology can improve road traffic safety,reduce the incidence of traffic accident,and protect the safety of drivers,passengers and pedestrians to a great extent.Research on the AEB control strategy and simulation test method is of great significance.Based on vehicle dynamics and control theory,a AEB control strategy that takes into account safety and comfort and meets the driver’s characteristics is designed,and uses the Prescan/Carsim/ Simulink co-simulation platform to verify the effectiveness of the control strategy.The main research work of this paper is follows:(1)The function and principle of vehicle AEB system are deeply analyzed,combined with the typical traffic scenes and working conditions of vehicle driving on the actual road,and designs the vehicle AEB collision avoidance and pre-warning control system based on the consideration of driving safety and system dynamics control,the overall scheme of the AEB collision avoidance and pre-warning control system is planed,and the key technologies needed to be solved to implement the overall scheme were analyzed.(2)With the powerful modeling function of Carsim,the vehicle dynamics is parametric modeling.In order to realize the control of vehicle acceleration,the vehicle inverse longitudinal dynamics model is established,which mainly includes throttle and brake pressure control switching logic model,the throttle control model and the brake pressure control model,thereby completing the modeling of vehicle dynamics.(3)According to the driving environment of the vehicle in real road traffic,the lateral and longitudinal danger state judgment models are established respectively.The lateral relative positional relationship between the host vehicle and the front target is used to realize the judgment of the lateral danger state of the host vehicle.Based on the safe time algorithm,two evaluation indicators of TTC(Time To Collision)and TTA(Time To Avoidance)are established,and judge whether the host vehicle is in a longitudinal danger state by comparing the values of TTC and TTA.As the time threshold for AEB system activation,TTA can adjust the timing of pre-warning and emergency braking in real time according to the relative motion state and road conditions of the main vehicle and front target.In addition,a pedestrian danger state judgement model based on V2 V communication technology is proposed for the blind spot dangerous scenario where pedestrians pass through the front of a stationary obstacle vehicle and collide with the host vehicle.Two danger state judgment evaluation indicators of TTE(Time To Enter)and TTL(Time To Leave)are established,and by comparing the values of TTC,TTE and TTL,it can be judged whether the host vehicle is in a lateral danger state.Finally,on the basis of considering the diver’s reaction time under different pre-warning signals,the vehicle AEB collision avoidance and pre-warning control strategy is designed.(4)According to the hierarchical control,the upper-layer and lower-layer controllers of the AEB collision avoidance and pre-warning control system are designed respectively.The upper-layer controller is designed based on fuzzy control,which can output the expected deceleration in accordance with the current driving conditions and the relative motion state between the host vehicle and the front target,so that the fuzzy controller can well simulate the collision avoidance operation characteristics of real drivers.The lower-layer controller is designed based on PID control,which enables the actual deceleration of the vehicle to accurately follow the expected deceleration output by the upper-layer controller.(5)The seven virtual test scenarios of vehicle-vehicle/two-wheeled vehicle and vehicle-pedestrian were established by Prescan.Co-simulation platform based on Prescan/Carsim/Simulink was built to simulate and analyze the pre-warning and collision avoidance effects of the AEB system in the above seven virtual test scenarios.The simulation results show the system can achieve collision avoidance,it can adjust the timing of the system to take over the control of the vehicle according to the state of the vehicle and the deceleration during braking in real time.In addition,the pedestrian danger state judgement model based on V2 V technology can judge the pedestrian state before radar detects the pedestrian in the blind area,so as to guide the implementation of the AEB collision avoidance and pre-warning function in advance.The effectiveness of the collision avoidance and pre-warning control strategy of the AEB system is verified.