Research On Autonomous Lane Changecontrol Method Of Intelligent Vehicle

Lane change is a driving behavior that is easy to cause traffic accidents and road congestion during vehicle driving.According to relevant the data,the lane change not only caused 4-10% of traffic accidents,but also caused 10% of road congestion and other traffic problems.Therefore,it is important to study the autonomous lane changing technology that can balance the lane changing efficiency and the lane changing safety reduce traffic accidents and road congestion caused by lane change.On the basis of summarizing the research work of autonomous lane change at home and abroad,this paper takes intelligent vehicles as the research object,analyzes the scenes of vehicle lane change,and extracts two kinds of working conditions,such as straight lane change and curved lane change,and The road condition is simplified,and then the method of establishing the minimum safety distance model is proposed according to the lane change scenario.Based on this,the lane change decision mechanism is established,and the lane change trajectory planning model is established for the straight lane and curve lane.Finally,the effective prediction of the lane change trajectory is realized by using the model predictive control.It has formed a full-featured development of intelligent vehicle autonomous lane change,from lane change decision to lane change trajectory planning and lane change trajectory tracking.The specific research contents are as followed:Firstly,through the combing of the lane changing scene,two typical working conditions of straight lane change and curved lane change are extracted,and the environmental model of these two working conditions is simplified.The lane change intention generation module introduces the speed expectation and the spacing expectation as the index generated by the lane change intention;the lane change decision module establishes the minimum safe distance model of the straight lane and the curved lane,and the lane change is feasible with the minimum safety distance as the constraint,then making autonomous lane change decision.In addition,the simulation of the minimum safe distance model of straight lane and curved lane is carried out.The simulation results show that the minimum safe distance of the straight lane is not applicable to the curved lane.Otherwise,there will be a situation where the lane can be changed,but the misjudgment is that the lane cannot be changed.Secondly,the lane change trajectory model of straight lane and curved lane is established according to the fifth-order polynomial function,and the validity of the lane change trajectory model is verified by simulation.Then the trajectory planning controller is designed based on the lane change trajectory model,and the optimal lane change trajectory is selected by the optimal solution idea to balance the lane change safety and lane change efficiency.Thirdly,based on the simplified vehicle dynamics model and model predictive control theory,this paper establishes a linear model predictive controller based on the vehicle three degree of freedom dynamics model to achieve effective tracking of the lane change trajectory.In this process,the three degree of freedom dynamics model of the whole vehicle is first established,and the simplified model is combined with the small angle hypothesis.The prediction model of the previous wheel angle increment as the control quantity is derived,and the nonlinear model prediction trajectory tracking controller is established.However,due to the nonlinearity of the prediction model and the complexity of the constraints,it is difficult to solve the optimization objective function efficiently,which affects the real-time performance of the controller.In order to solve the accuracy and real-time performance of intelligent vehicle trajectory tracking,this paper discretely linearizes the nonlinear prediction model and constructs a linear model prediction trajectory tracking controller based on two degree of freedom dynamics model.Finally,the trajectory tracking experiment is carried out by using the joint simulation platform of CarSim and MATALB/Simulink.The simulation results show that the controller has wide adaptability and well robustness to the attachment conditions and speed,which can ensure the accuracy and stability of trajectory tracking and meet the actual situation.The lane change requirements and the correct selection of controller parameters can also improve the accuracy,real-time and stability of the trajectory tracking.Finally,in order to verify the performance of the complete autonomous lane change method,this paper verify the effectiveness of the autonomous lane change control method based on CarSim,PreScan and MATLAB/Simulink joint simulation platform software for off-line simulation,and provide a certain reference value for autonomous lane change.