Research On Control Algorithm Of Electric Assistant Steering System For Commercial Vehicles

With the steady development of national economy and automobile industry,the sales of automobile are also increasing year by year.However,compared with passenger cars equipped with electric power steering(EPS),commercial vehicles,which are the main force of passenger and cargo transportation,have higher driving comfort and vehicle driving safety requirements.The steering system has a direct impact on the handling and safety of vehicles.In order to solve the problem of occupational diseases of commercial vehicle drivers,the new type of power steering system,namely the commercial vehicle electric-assisted power steering system,is gradually emerging.The electric-assisted power steering system is designed for commercial vehicles after the electronically controlled hydraulic power steering system(EHPS).It can not only give people a good sense of driving and control,improve vehicle safety,but also help saving energy and protecting the environment.The development of this new technology will be the future trend in the development of commercial vehicle steering system.Therefore,it is of great significance to develop the electric auxiliary steering system of commercial vehicles and study the active control strategy of the steering system to improve the driving comfort of commercial vehicles.In order to make the simulation results of the development of commercial vehicle electric auxiliary steering system is more practical significance,this article first to the steering system,a mathematical model is established based on the empirical formula and tire six component for steering resistance moment are analyzed in detail,using AMEsim software,TruckSim software and Matlab/Simulink software to build the Angle of input and input torque electric auxiliary steering joint simulation model,and by using the simulation results and test data are compared,the results prove that this model is basic accurate,can be used as active control strategy of electric auxiliary steering system developed to provide guidance.Firstly,in order to make the simulation results are more practical for the development of commercial vehicle electric auxiliary steering system,the mathematical model of the steering system is established.And the steering resistance moment is analyzed in detail based on the empirical formula and the six-component force of the tire.Besides,the corner input type and torque input type electric auxiliary steering joint simulation model are built by using AMEsim,TruckSim and Matlab/Simulink.The simulation results are compared with test results,which proves that this model is enough accurate to be used as guidance of the active control strategy of the electric auxiliary steering system.Secondly,based on the driver's ideal hand torque model,the power assist characteristic curve of commercial vehicle electric steering system is designed by using the linear power assist characteristic curve design method.And the influence of steering wheel angle,lateral acceleration and speed on the driver's hand torque is considered.At the same time,considering the steering handiness and maneuverability,the basic power control algorithm based on PID control,the active return-forward control algorithm based on the double closed-loop PID control of steering wheel Angle and speed,and the road bump control algorithm based on the road bump moment estimation equation are designed.The effectiveness of the active control strategy is verified by the joint simulation.Finally,the commercial vehicle electric auxiliary steering system hardware in loop test bench is built.The structure and working principle of test bench are introduced in detail.Then,the electric power system,hydraulic power system and resistance simulation system are tested.The test results indicate that the designed test bench meets the requirements of the hardware in loop test.At the same time,the active control strategy is verified by the test bench and the results show that the designed control strategy achieves the desired effect.