Research On Decision Planning And Control Of Autonomous Lane Change Of Intelligent Vehicle On Ice Snow Road

Intelligent vehicle itself has the ability of active environmental perception,and it is also the core component of intelligent transportation system.Through information exchange,the close combination of human vehicle environment can be realized,which can improve the driving safety.Vehicle lane changing behavior is the most common traffic behavior when the vehicle is driving,and it is also one of the most prone to traffic accidents.There are many reasons for traffic accidents in the process of lane change.Among them,one of the most important reasons is that the driver's wrong judgment of space leads to the wrong decision of lane change.This situation can eliminate human factors through automatic driving,so as to avoid accidents.Therefore,it is the key point of the study of lane change to eliminate the hidden danger of human generated lane change in the process of vehicle lane change.In this paper,the ice and snow road as the driving conditions,the intelligent vehicle automatic lane change research.The adhesion ability of vehicles under the ice and snow road is greatly reduced,which adds a lot of security risks to the vehicle lane changing.Therefore,the safety of vehicle lane changing under the ice and snow road conditions is the research focus.Based on the traditional method,according to the complexity of road conditions,this paper puts forward some solutions to improve the safety and stability of vehicles when changing lanes.The specific research content includes the following aspects:(1)Establishing the model of hub driven electric vehicleIn this paper,the former wheel motor driven vehicle is the target vehicle.Firstly,the model of the research object is established to study the lane change decision,trajectory planning and tracking control of the vehicle.The traditional internal combustion engine vehicle model in Car Sim is modified,and then the tire model is established according to the magic formula to form the whole vehicle dynamics model.Finally,the hub motor model is established,which is connected with the whole vehicle dynamics model,and the whole vehicle model driven by the front wheel motor is obtained.(2)Lane-changing decision and trajectory planningFirstly,the behavior of lane change is analyzed,and the complex traffic environment is simplified into a two lane simple lane change scene.Then,the minimum safe distance and the expected speed of driving are deduced.Considering the safety of vehicle lane change on ice and snow road,the decision of lane change is preliminarily studied.In the aspect of track planning,due to the low adhesion coefficient of ice and snow road,vehicles are prone to sideslip and other dangerous phenomena,so the adhesion characteristics of tires are analyzed,considering the influence of longitudinal force of tires on track safety,the lateral acceleration threshold to ensure the safety of lane changing is derived.Based on the 5-degree polynomial trajectory equation,the optimization objective function of lane change time and longitudinal displacement is established,and the optimal trajectory is obtained according to the optimized parameters to improve the safety.Considering the dynamic environment in the process of lane change,the trajectory of the obstacle vehicle is estimated,and the trajectory space of the obstacle vehicle is obtained.Then the local trajectory of the vehicle is obtained through the two degree of freedom steady-state model.Then the unqualified trajectory is removed in the trajectory space,and the optimal trajectory of the free lane change is taken as the target trajectory to get the closest lane change trajectory.(3)Tracking control of lane changeThe tracking control of lane changing track is highly dependent on the environment.When the environment changes,the control effect of the controller will decline.The control of the vehicle is also different from other systems.There are more dynamic constraints and actuator constraints,and the tracking control under the ice and snow road needs to consider more strict safety.In this paper,the controller is divided into two layers.The upper controller adopts the method of model predictive control,which can deal with multiple constrained targets.The tracking control under the condition of low adhesion of ice and snow road has better tracking ability.Because the object studied is a wheel drive vehicle,the lower controller uses the fuzzy PID control method to assist the vehicle Assistant control,through the principle of differential torque control,distributes the driving torque,and improves the safety and stability of vehicle lane changing.(4)Simulation experiment verificationThe traffic environment model is built by using prescan,and the dynamic model,lane change decision module,track planning module and track tracking module established by Car Sim and MATLAB / Simulink are combined with the virtual simulation verification platform to verify the effectiveness and reliability of the independent lane change on ice and snow road studied in this paper.