Design And Test Of Efficient Steering System Of Unmanned Tractor Based On Dual Steering System

As a large agricultural country,agriculture plays an important role in China’s national economic production.As the most important agricultural machinery in the field,the automatic driving technology of tractor has been widely studied at home and abroad.As the core of automatic driving,the performance of automatic steering execution system determines the quality of tractor operation in the field.In order to improve the intelligent level of tractor automatic steering in the field and improve the operation efficiency of headland turning,a tractor field efficient steering system based on double steering system is designed,which can realize the efficient steering of tractor in the field.The main research work is as follows:(1)In view of the problems of complex installation mechanism,low control torque and high production cost in the traditional tractor automatic steering system,an automatic steering control mode based on the installation of DC motor on the steering column is designed,which mainly includes DC brush motor,motor reducer,steering column,torque sensor and steering wheel.The whole mechanism is directly connected with the full hydraulic steering gear through mechanical structure to ensure the steering accuracy;By detecting the steering column torque in real time through the torque sensor,the manual /automatic driving mode can be switched automatically to ensure the safety of control.The automatic steering system is installed on the tractor and tested.The field test shows that the average deviation of wheel response angle is 0.1 °,the maximum deviation is 0.15 °,the fastest response of ± 20 ° step signal can reach 1.2 seconds,and the overshoot is less than1%,which can meet the steering operation of tractor in field automatic navigation driving.(2)Turning around at the end of the field is one of the factors affecting the efficiency of tractor automatic driving in the field.In this paper,an auxiliary wheel system is designed,which can complete the efficient line change of the ground by installing a 360 ° steering auxiliary wheel at the front end of the tractor,mainly including the structural design of the auxiliary wheel system,the design of the hydraulic drive system and the design of the electro-hydraulic servo controller,which can realize the automatic steering,lifting and driving functions of the auxiliary wheel system.A simulated field experiment is designed to verify the feasibility of the auxiliary wheel steering mode.By comparing with the current common headland steering mode,it shows the efficiency of the auxiliary wheel steering mode.The data shows that the auxiliary wheel ground steering method in time efficiency,driving distance and ground space occupation compared to the traditional steering method increased by 50%,80% and 50%,respectively,is expected to produce a large improvement in the field of tractor driverless.(3)The cooperative control operation is carried out based on the dual steering system,the cooperative control action strategy is formulated according to the field position,and the tractor global path automatic steering simulation experiment is carried out to verify the feasibility of the cooperative control strategy.Secondly,the field real vehicle test of the cooperative control of the dual steering system is carried out.The tracking performance of the dual steering system is judged through the lateral error of the path,the angle tracking data of the dual steering system and the lifting tracking effect of the auxiliary wheel.The test results show that the dual steering system of the tractor has a good effect,the steering accuracy meets the requirements and meets the actual needs of the tractor’s efficient steering operation in the field.