| The Hydraulic Power Steering system(HPS),which is generally assembled in traditional commercial vehicles has some defects,such as fixed power steering characteristics,lack of driving assistance function,poor portability at low speed and poor stability at high speed.Due to the power limitation of conventional on-board power supply system,Electric Power Steering system(EPS)with driving assistance function is not suitable for heavy commercial vehicles.Under the background of electric and intelligent development of commercial vehicle steering system,a new type of Electro-Hydraulic Coupling Steering system(EHCS),which combines electric power and hydraulic power,has become a new carrier for commercial vehicle.EHCS adds power assisted motor and ECU on the basis of HPS through torque coupling device,overcomes steering resistance torque through hydraulic system,and realizes active torque and angle control of steering system by using electronic control technology,which has the characteristics of high energy density and high degree of intelligence.Based on the steering system,the active steering control strategy is established,and the co-simulation platform is built by using Trucksim/Matlab/Simulink to preliminarily verify the effectiveness of the control strategy.Finally,Hi L hardware in the loop simulation test is used to further verify the active control strategy(1)According to the system composition of EHCS,the Simulink model including mechanical subsystem,electric power subsystem and hydraulic power subsystem.The whole vehicle model is established by Trucksim,and the Simulink and Trucksim co-simulation model is built,which lays a foundation for the follow-up study of steering control performance and vehicle handling stability of commercial vehicles.(2)In order to realize the active returnability control of commercial vehicle steering and to solve the problem.It is difficult to obtain part of the vehicle state and the tire-road coefficient which affects the stability of the vehicle steering is difficult to measure directly,the UKF observer is built to estimate the vehicle and road state information needed by the controller;according to the UKF filtering algorithm,the UKF observer model is built based on Matlab and integrated with Trucksim.The effectiveness and superiority of UKF filtering algorithm are verified by cosimulation of vehicle model.(3)The judgment mechanism of righting control is introduced.The algorithm of joint sliding mode controller is designed based on the yaw rate and sideslip angle,and the process of joint sliding mode algorithm is deduced in detail.Based on Trucksim/Matlab/Simulink,the model is established Simulink EHCS co-simulation model,co-simulation results show that the commercial vehicle equipped with EHCS using the joint sliding mode control algorithm can effectively track the expected value of sideslip angle and yaw rate,greatly improve the vehicle handling stability and high-speed driving safety,and verify the effectiveness and superiority of the joint sliding mode control algorithm for the commercial vehicle return control.(4)Based on D2 P platform,NI real-time simulation machine and upper computer,the hardware in the loop simulation test platform(Hi L)for active righting control of commercial vehicle is built.Veristand is used to compile the code of controlled vehicle model and EHCS model and write it to NI real-time simulation machine.The joint sliding mode control algorithm is developed by using D2 P platform.Finally,the hardware in the loop simulation test is completed,and the test results are compared with the Truksim/Matlab/ Simulink co-simulation results to verify the stability and effectiveness of the designed joint sliding mode controller. |
PDF Full Text Request