Development And Verification Of Control Strategy Based On Commercial Vehicle Electro-hydraulic Coupling Steering System

With the continuous development of the national economy,the demand of my country’s road transportation industry is also steadily increasing.As the main equipment for cargo transportation,commercial vehicles have the characteristics of long body and high center of mass.They lag behind passenger vehicles in terms of handling stability and driving comfort.How to improve the driving comfort and safety of commercial vehicles is an important research topic at present.The steering system is a system directly operated by the driver.Improving the steering feel and active steering performance of the steering system is of great significance for reducing the driver’s driving burden and improving the driving comfort and safety of commercial vehicles.The Electro-hydraulic coupling steering system is a power steering system for commercial vehicles.It is equipped with a booster motor and a controller on the hydraulic power steering system.By controlling the torque output by the booster motor,the steering feel can be improved and active steering can be realized.This paper is financially supported by Jilin Province Science and Technology Development Plan Projects "Research on decision-making and control of automatic lane change of electric vehicle with X-by-Wire chassis"(No.: 20230101121JC),aiming at reducing the operating burden of the steering system and improving the feel and active steering performance of the steering system,based on the electro-hydraulic coupling steering system,the power assist control strategy,centering control strategy,damping control strategy and lateral trajectory tracking suitable for semi-trailer tractors are developed.The control strategy is verified by means of software simulation and hardware-in-the-loop simulation.The specific research contents of this paper are as follows:(1)Aiming at the contradiction between steering portability and steering stability in the steering system of commercial vehicles,a power assist control strategy was developed and verified by software simulation.Aiming at light steering at low speeds and stable steering at high speeds for commercial vehicles,a curved power assist characteristic curve is firstly designed,and then a power assist control strategy is designed based on adaptive fuzzy PID.The software simulation under different working conditions verifies the effectiveness of the boost control strategy.(2)Aiming at the problems of insufficient correction at low speed and correction overshoot at high-speed in the steering system of commercial vehicles,a centering and damping control strategy was developed and verified by software simulation.In order to improve the steering wheel alignment accuracy of the steering system at different vehicle speeds,a mode judgment controller with input signals such as vehicle speed,steering wheel angle,and steering wheel torque was designed first,and then a alignment and damping control strategy was designed based on the adaptive PID control method,and finally verified the effectiveness of the centering and damping control strategy through the working conditions of letting go and returning to the center at different vehicle speeds.(3)For the semi-trailer tractor in commercial vehicles,the lateral trajectory tracking control strategy is designed and verified by software simulation.In order to improve the lateral trajectory tracking accuracy and driving stability of the semitrailer tractor,lateral trajectory tracking controllers are designed for the tractor and semi-trailer respectively,and the lateral trajectory tracking controller of the tractor is developed based on Model Predictive Control(MPC)Algorithm,the semi-trailer lateral trajectory tracking controller is developed based on the Linear Quadratic Regulator(LQR)control algorithm.Under the same working conditions,two control methods of tractor independent control and tractor and semi-trailer joint control are used for comparative testing.Improvement of lateral trajectory tracking performance and driving stability of semi-trailer tractor.(4)A hardware-in-the-loop simulation test bench for the Electro-hydraulic coupling steering system is built,and the designed control strategy is further verified on the test bench.In order to verify the effectiveness of the designed control strategy on the steering system hardware,this paper designs and builds an electro-hydraulic coupling steering system hardware-in-the-loop test bench based on the original commercial vehicle steering system test bench of the research group.The test bench is based on NI PXI The system and the Micro Auto Box controller are used as the hardware basis.The co-simulation of Truck Sim software and Lab VIEW software is used to conduct hardware-in-the-loop tests to verify the designed control strategy.The test results verify the effectiveness of the designed control strategy on the steering system hardware.