The Longitudinal Control Strategy Of Collision Avoidance Warning System For Intelligent Vehicle

The increase of car ownership brought great convenience to people's lives,but also led to traffic accidents occur frequently,which not only brought economic losses,even endanger people's health and safety.As people pay more and more attention to the driving safety of vehicles,Advanced Driving Assistant System has been gradually developed and applied extensively.In this paper,the research object is the Forward Collision Avoidance Warning System,as an intelligent assistance driving technology,it provides the driver a safety and comfortable driving experience.When the danger is detected,the early warning signals is sent to the driver to avoid collision,it could assist the driver to drive safely.The system played an important role in reducing traffic accidents and ensuring personal safety.First of all,the background and significance of the research are introduced in this paper.The current research status of safety vehicle distance model and longitudinal control algorithm are discussed and introduced.The research contents of the chapters and technical route are presented.Secondly,the safety vehicle distance model based on the braking process is analyzed and the main factors that affect the model are analyzed.In view of the shortcomings of the traditional model,an early warning/dangerous safety vehicle models considering driver's style,environment factors are proposed.The driver's delay reaction time is got based on the fuzzy control theory.Under car following conditions,the traditional expectation safety distance based on time headway is improved,the variable time headway is got by using the fuzzy control.It could adapt to the distance and speed change.And the expectation safety distance is multiplied by a driver style option factor to meet the requirements of different drivers.Then,the vehicle dynamics model and inverse dynamics model are established,as the control the research object.Based on the relative distance error and relative speed error,the upper controller based on sliding mode control is designed to obtain the expected acceleration,and the tracking acceleration based on the PID controller.And in view of the chattering problem of sliding mode control,a variable gain coefficient control method is proposed.The fixed gain parameter is improved to the mathematical logic formula associated with the negative exponent in the expected acceleration formula.This method can effectively suppress the chattering problem of the desired acceleration.Finally,the joint simulation model of forward collision warning system was established based on the mature simulation software,Carsim and Simulink,to validate the effectiveness of the control algorithm.The experimental simulation conditions are designed in view of the typical traffic test scenarios.It includes cruising speed of the vehicle,approaching stationary / uniform / decelerating conditions,the following conditions.The simulation results show that the forward collision warning system can remain the expectation safety distance.And the braking deceleration can be made in the dangerous working condition,to ensure the safety of the vehicle without collision with the front car.