Control Strategy Development And Verification Of Lane Keeping Assistant Driving System For Semi-trailer

Commercial semi-trailers have become the main carriers of the highway transportation due to the large volume,high quality and suitable for long-distance transportation.The driver's driving fatigue is a very important cause of traffic safety hazards in long-distance highway transportation.Therefore,the development of active safety system for commercial vehicles is very significant.Advanced driving assistant systems can make comprehensive decision and analysis according to the changes of the external environment and provide driving guidance to drivers,and some systems can realize the basic active control command without the participation of the drivers,which is playing a very vital role in improving the active safety of vehicles.Based on the Electro-Hydraulic Coupling Steering System and Electro-pneumatic Braking System,this paper developed the Lane Departure Warning and Lane Keeping control strategies which are suitable for commercial semi-trailers and also this paper built a steering-braking test platform for commercial semi-trailers to test and verify the control algorithm.The specific research contents of this paper are as follows:The analysis of driver's intention judgment was discussed in this paper.Based on the driver's input interface to the vehicle(steering wheel,brake pedal and accelerator pedal)and combined with laws and regulations,a model of driver intention judgment according to the driver's driving operating status identification was proposed.Based on the commercial semi-trailer driving simulator collected 18 groups driving behavior threshold parameters to calibrate the opening thresholds of steering wheel torque and brake/accelerator pedal.This paper analyzed the different lane departure modes of commercial semi-trailer under highway working conditions of straight line and curve line,and the advantages and disadvantages of each warning algorithm was also analyzed.Based on the vehicle's deviation speed,a fusion early-warning algorithm based on FOD and TLC was implemented to achieve more developed for accurate and high-quality warning algorithms.Then,this paper explored the influence of different driving styles on the early warning algorithm from two aspects of drivers' psychological factors and physiological factors through simulation analysis.In order to realize the active control of the vehicle after the warning signal,this paper innovatively established a driver model suitable for the commercial semi-trailer based on the simplified three-axis 3-dof vehicle model of commercial semi-trailer and the preview following theory.Furthermore,in order to achieve more precise control of the vehicle position according to the lateral displacement deviation of the tractor's center of mass and the center of the road as input,a fuzzy PID compensation control based on lateral displacement deviation was completed to optimize the original driver model,and the model verification was completed on the established electro-hydraulic coupling steering system.In order to obtain ideal vehicle trajectory,a more accurate six-axis 3-dof semi-trailer model was established.The ideal articulated angle and ideal semi-trailer yaw were obtained by analyzing and calculating the relationship between the center of mass of the tractor-trailer and the center of the road,angular velocity and the difference between it and the actual yaw angular velocity in the TruckSim vehicle model as the input control amount,a single neuron adaptive PID control algorithm was established to calculate the yaw moment value assigned to the tractor and trailer.Through the inverse model of EBS braking system established by the moment distribution method,the upper yaw moment value was converted to the pressure of each brake wheel brake chamber,thereby achieving closed-loop control of commercial semitrailer lane keeping control calculations.This paper built a steering-braking hardware-in-the-loop simulation platform for commercial vehicle semi-trailer on the basis of original commercial vehicle's electro-hydraulic coupling steering test bench and commercial vehicle's electro-pneumatic braking test bench.The driving simulator embeds the electro-hydraulic coupling steering system and electro-pneumatic braking system into the TruckSim dynamic model instead of the original mathematical simulation model.With MATLAB/Simulink software,the departure warning algorithm and the lane keeping control algorithm were implemented.The LabView-RT and TruckSim-RT combined with PXI-1042 Q chassis realized the hardware-in-the-loop of commercial semi-trailer vehicle model,used dSpace and Micro-AutoBox software to complete the compilation and download of the control strategy.By controlling the vehicle's steering wheel angle and braking pressure of each braking chamber,the hardware-in-the-loop verification of the lane departure warning algorithm and lane keeping control strategy for semi-trailer were completed.