Path Tracking Control Method Of High-gap Plant Protection Machine Considering Anti Rollover

As a traditional agricultural country,agriculture plays an extremely important role in our country.Since entering the 21st century,with the improvement of science and technology and living standards,China has begun to comprehensively promote the development of precision agriculture.In order to improve the accuracy of agricultural machinery and reduce labor costs,it is very important to carry out research on automatic driving system of agricultural machinery.Path tracking control technology in this system is a powerful guarantee to achieve high precision operation of agricultural machinery.In this paper,a path tracking control method considering anti rollover is studied and designed for high gap plant protection machine,which can accurately track the planned target path without rollover.The main research work is as follows:(1)On the basis of consulting a large number of literature on automatic driving of agricultural machinery,the path tracking control method of high gap plant protection machine is studied based on vehicle kinematics model.Aiming at the problem that the preview distance of pure pursuit algorithm,which is often used in agricultural machinery,cannot change adaptively according to the path curvature or speed,resulting in the poor tracking effect caused by too large or too small preview distance.This paper proposes a path tracking control method based on the optimal preview point.Through this method,the plant protection machine can select the optimal preview point in real time according to the predicted attitude of the vehicle,which can track the target path more accurately and stably.The simulation is carried out based on the pycharm environment.(2)According to the structural characteristics of high center of mass of high gap plant protection machine,which is prone to rollover,an anti rollover control strategy is designed.A three degree of freedom Rollover Model of high clearance plant protection machine was established.The dynamic lateral vertical load transfer rate(LTR_d)was used as the rollover index,and the anti rollover control strategy was designed.When the LTR_d of the high gap plant protection machine exceeds the rollover threshold during driving,the anti rollover control will be started,and the rollover of plant protection machine will be prevented by the strategy of active steering and speed control.Then the simulation is carried out based on MATLAB/Simulink.(3)The experiment platform was built on 3WP-500L high gap plant protection machine,and the path tracking experiment was carried out in corn field.The experimental results show that the high gap plant protection machine based on the algorithm proposed in this paper has no trigger roll control during the tracking process,and the tracking accuracy of the line and curve is good,which meets the requirements of the precision operation.At the same time,compared with pure pursuit algorithm,the tracking effect is significantly improved.