Research On Path Following Control Based On Modern Trackless Train

With the continuous increase of urban population,the pressure on public transportation is increasing day by day,and traditional public transportation methods have restricted the improvement of transportation efficiency.Modern trackless train is a new type of urban transportation means,which is a supplement to the existing transportation mode.It not only has the advantages of flexible road vehicle operation and low capital construction cost,but also has the characteristics of large traffic volume and flexible marshalling of urban rail trains.It is the future development trend of urban transportation.The various car bodies of modern trackless trains are connected by hydraulic articulated mechanisms,and the multi-axis steering function can improve the operational flexibility of the vehicle under complex working conditions.However,compared with a single passenger car and a single articulated passenger car,the structure of multiple formations and a long body will make the steering control more complicated.When driving on a curve,the trajectory of the rear vehicle is likely to deviate from the driver’s manipulation intention,and in severe cases,it may lead to the danger of folding and flicking of the car.Therefore,it is necessary to study the path tracking control of modern trackless trains with multiple articulations.Firstly,the overall structure and main design parameters of modern trackless trains of new vehicles are introduced,and three-dimensional structural schematic diagrams including steering bridges and articulated mechanisms are given,and the steering mode and drive configuration of the vehicle are obtained.According to the above structure,the kinematics model of modern trackless train with multi-articulated structure and the driver model based on the optimal preview are established.Based on the virtual prototype technology,a three-dimensional model of the car body is established in the three-dimensional modeling software,and then imported into the ADAMS software to establish a dynamic model of the whole vehicle.Finally,the kinematics model built in Simulink is simulated and compared with the vehicle dynamics model built by ADAMS to verify the correctness of the model.Secondly,in order to solve the problem that the movement of the rear axle lags behind the front axle,the target pose of the rear axle is constructed based on the registered look-up table,and the error function of each axle of the vehicle is established,and the influence factors of position error and heading angle error are analyzed.In view of the situation that each axis of a multi-articulated vehicle is in a different state of motion when driving through a curved path,a transition process control is designed,so that each section of the vehicle can smoothly transition to the curve.In order to solve the problem of poor tracking performance of multi-articulated vehicles,a model predictive control algorithm is used to design a path tracking controller.Through Simulink and ADAMS co-simulation,the path tracking error and heading angle error of the vehicle under sudden curvature changes,different vehicle speeds,double shifting,serpentine and other working conditions are tested,and the path tracking performance and stability are verified.Finally,the preliminary design plan of the modern trackless train principle prototype platform was completed,including its overall structure and Ackerman steering structure.The design of the core control board and drive system is analyzed,and the algorithm program is designed.Based on the prototype vehicle experimental platform,a preliminary verification is carried out on curve driving and steady-state circular motion conditions.