| The rapid development of the automobile industry has both advantages and disadvantages.On the one hand,it greatly affects people’s daily travel,but on the other hand,it also derives many problems including traffic safety.In order to reduce personal injuries and property losses caused by traffic accidents,researchers have been committed to the research of automobile safety.In recent years,besides the passive safety of vehicles,more and more attention is focused on the development and research of active safety technologies that can realize early warning and avoid collisions,and active collision avoidance systems are an important part of the field of automotive active safety.The in-depth study of the active collision avoidance system has important practical significance in planning the capacity of the road rationally,and promoting the intelligentization of vehicles.This paper aims to build an active collision avoidance system for vehicles,and has carried out various related work around the active collision avoidance strategy,safety distance model,vehicle dynamics modeling,controller design and other aspects involved in the system.(1)First of all,the general design scheme of the active vehicle collision avoidance system is formulated,the functions of the active collision avoidance system are defined,and it’s basic components and some key technologies involved are clarified.(2)Through the research of the existing collision avoidance models and the analysis of driving conditions,two safety distance models of high speed and low speed with speed as the boundary are proposed.Taking into account both traffic safety and traffic flow,conservative collision avoidance strategies are adopted at high speed conditions,and aggressive collision avoidance strategies are adopted at low speed conditions.Considering that when facing the danger of collision,the driver’s judgment,selection,and decision-making process require a certain amount of time,the reminder time is set to warn drivers of potential driving risks.In order to ride and seat comfortably,it is proposed to adopt the hierarchical braking method during the automatic emergency braking phase of the vehicle,in which a small deceleration speed is used firstly to give the occupants a certain buffer time,and then full braking to avoid collisions.(3)For the dynamic control of the active collision avoidance system involved,the dynamic model and the inverse dynamic model of the vehicle were established in Carsim and Simulink respectively to obtain the throttle opening,brake pressure,and output speed,acceleration and other variables to realize the control of the vehicle.On the basis of the functional requirements of the collision avoidance system,the lower level controller based on fuzzy PID control is designed,and the corresponding upper level controllers are designed,the corresponding upper-level controllers are designed for working conditions such as constant-speed cruise,adaptive cruise for maintaining vehicle spacing,and automatic emergency braking.(4)Finally,a joint simulation is carried out on different working conditions to verify the performance of the proposed safety distance model,control strategy,and vehicle active collision avoidance system.The simulation results show that the controllers designed for different working conditions achieve good control of the system,and the vehicle active collision avoidance system can well meet the requirements of collision avoidance.The proposed safety distance model based on speed boundary can well respond to the corresponding driving conditions and improve the safety of driving to a certain extent;The designed hierarchical braking method can not only avoid collision,but also improve the comfort of the vehicle during automatic emergency braking.In this paper,the research on vehicle active collision avoidance system has basically achieved the expected effect,which provides a partial reference for the subsequent related research. |
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