Development Of Electric Power Steering System For Electric Tractor

The development of intelligent agricultural equipment is the key cornerstone of intelligent agricultural development.Electric tractors are the main carrier of intelligent agricultural equipment.In order to better develop intelligent automation technology in the agricultural field,intelligent electric tractors have become social research.As one of the hot spots,the steering system is one of the more important systems for vehicles.This paper analyzes the existing traditional hydraulic steering systems of tractors that are not adapted to the power source and space layout of electric tractors.The electric power steering system commonly used in passenger cars is selected as the auxiliary steering system for electric tractors,and a matching electric tractor is developed.The electric power steering system under the working conditions;the controller of the electric power steering system is designed through the STM32F407VGT6 chip and the peripheral chip circuit;on the premise of ensuring the road feel and safety of the driver,the power assistance characteristics of the passenger car do not meet the tractor The design of operating conditions is in accordance with the assist characteristic curve of electric tractors.Based on the above,a Fuzzy PID comprehensive control strategy based on steering conditions is proposed,and the control strategy is simulated and experimentally verified.The main research contents and work of this article are:(1)Determine the electric tractor steering system plan.The adaptive comparison between the electric power steering system and the traditional hydraulic steering,and the experience of the EPS system of the passenger car is used to analyze and compare the advantages and disadvantages of different power steering solutions.The columntype electric power steering structure is selected as the electric tractor power steering System design,select key components for the designed power steering system,perform non-standard design and process assembly,and theoretically model the EPS system.(2)Controller software and hardware design and sensor analysis.Based on the analysis of the software and hardware requirements of the EPS system,the design of hardware circuits such as the core control module in the EPS controller and the data acquisition module of HELLA TAS,including external electrical connections;the signals transmitted by HELLA torque angle sensors were carried out Analysis;Based on the ISO 11783 standard protocol,the CAN bus message transmission protocol of the EPS system and the connection part of the electric tractor is designed;the AD acquisition program,CAN communication program,and serial communication program of the EPS system are designed.(3)Research on the power-assistance characteristics and control strategies of the steering system.Based on the complicated and variable working conditions of the tractor,the steering conditions of the tractor are analyzed,and three operating modes of the electric power assistance system are designed on this basis,and specific assisting characteristic curves are designed for each operating mode.The analysis of the tractor’s electric power steering system proposes a Fuzzy PID integrated control method based on steering conditions.The Fuzzy control rules are used to adjust the three parameters of the PID algorithm in real time online to improve the effect of electric tractor power steering control under different conditions.(4)Test test.The simulation model of the electric power steering controller was built.The Matlab/Simulink simulation experiments on the torque control algorithms of PID and Fuzzy PID showed that the torque control algorithm of Fuzzy PID had fast response and small fluctuations;a test platform for power steering system bench was established The Fuzzy PID and PID steering experiments based on recognition control were carried out respectively.The test results show that in the steering test,when the vehicle speed is 0.6 km/h,the steering wheel torque range using the Fuzzy PID comprehensive control strategy is reduced by 0.5 N·m,and the steering wheel torque fluctuation is significantly reduced.