Research Of Trajectory Control System In Unmanned Vehicle

With the rising number of vehicles,social problems is getting more and more serious,due to the driver’s improper operation in our country,such as fatigue driving,causing thousands of traffic accidents.In order to make people’s travel more intelligent,lifestyle,on the premise of meet the increasing demand for people and avoid bad consequences caused by man-made factors on the travel,unmanned vehicles can improve road traffic safety and alleviate urban traffic congestion,which has become the inevitable trend of vehicle development in the future.Perception,planning and control are the three most important components of unmanned vehicles.This paper mainly focuses on trajectory planning and trajectory tracking control,and the main work is as follows:Firstly,this paper puts forward the risk parameters based on fuzzy logic node-search trajectory planning algorithm.Using the sampling node structure map location information,generates directed graph of the network structure,using the cost parameters,the risk coefficient and the parameters design cost function,combined with vehicle traffic information such as time,speed,and travel environment,using the fuzzy logic design risk parameters.The risk parameters of lane keeping,left-parallel and right-parallel are identified,and the local optimal directed path composed of two adjacent nodes is obtained.In this paper,a simulation program is designed in the simulation environment to verify the reliability and effectiveness of the risk parameters in the three-lane environment.Secondly,according to the longitude of adjacent nodes and course angle,based on the two adjacent nodes of local optimum directed path,using Clothoid curve,in order to make the car travels in actual with continuous variable curvature and avoid the risks of a sharp turn,this paper studies and analyzes the expected trajectory generation,puts forward the actual driving environment of the curvature parameter setting method and designs trajectories that are physically feasible.Thirdly,the vehicle lateral and longitudinal motion analysis has very strong coupling relationship,the complex working conditions exist,external disturbance and motor changeable characteristics.In order to offset the impact of unpredictable factors on the system effectively,on the longitudinal control,this paper designs an electric car speed planning method based on fuzzy controller,make more accord with human driving experience during the process of vehicle.The vehicle can effectively maintain the appropriate vehicle distance,improve the safety of driving.In the aspect of lateral control,the differential trajectory tracking control system based on steering compensation is proposed in this paper.By using steering compensation,the errors of horizontal and vertical coordinates and course angle produced in the trajectory tracking process are reduced and the stability and accuracy of trajectory tracking are improved.In this paper,the simulation program is designed in simulation environment,and the typical path including straight line and curve is taken as the expected trajectory.The simulation results imply that in the trajectory tracking with physical feasibility,the differential trajectory tracking control system based on steering compensation designed in this paper can make the horizontal and vertical coordinates in the tracking process tend to be stable.The error is at a good level.Under the action of the steering compensation module,the fluctuation range of course Angle deviation caused by motor disturbance,rise time or inaccurate system parameters will be gradually reduced.The system has good stability and accuracy in trajectory tracking.