Path Tracking Model Predictive Control For 4WID High Gap Sprayer Considering Driving Wheel Slip

Food security is an important foundation for national security.Promoting the development of agricultural science and realizing agricultural modernization is the key to ensuring food security.However,the traditional agricultural machinery which is driven by oil will cause serious pollution to the environment.Traditional agricultural machinery which adopts traditional mechanical transmission has low transmission efficiency and single control form,resulting in large turning radius and difficult attitude control.Traditional agricultural machinery and equipment only rely on farmers to operate the path tracking control accuracy cannot be guaranteed under long hours of work and complex working conditions.Due to operator fatigue driving,it is easy to deviate from the predetermined track,wheel pressure seedlings and other situations,which cause a certain potential safety hazard for traditional agricultural machinery.Therefore,all kinds of intelligent agricultural machinery equipment that use clean energy,have a more reasonable vehicle structure,can operate unmanned and adapt to complex working conditions are gradually becoming the trend of future agricultural machinery development.In this paper,a new type of high-gap four-wheel independent drive sprayer with front-rear double steering bridge was taken as the research object.The influence of driving wheel slip on the stability and tracking accuracy of the path tracking control was considered and a layered control method was adopted to construct a layered path tracking control scheme considering the influence of tire slip.The main contents are as follows:(1)Studying the development of unmanned automatic agricultural machinery driving technology.Based on the problems existing in the unmanned transformation of traditional agricultural machinery equipment,a new type of unmanned gap sprayer was proposed.The structure of the sprayer was analyzed from the angle of kinematics and dynamics and compared with traditional agricultural machinery equipment.The advantages of the new sprayer in steering and handling stability were summarized.The common tire parameters and road parameters were analyzed in order to explore the influence of tire skidding on the tracking control precision of atomizer on the road surface with different flatness and adhesion coefficient.The chassis model of the sprayer was built in Adams/ View.The tire parameters and road parameters of the sprayer were set,which laid a foundation for the subsequent simulation of the sprayer under complex working conditions.(2)The relative control algorithms of path tracking control of unmanned agricultural machinery were studied and the advantages and disadvantages of common tracking control algorithms were analyzed.In order to meet the requirements for the control accuracy of the sprayer’s path tracking under complex working conditions,the layered path tracking control considering the influence of tire slip was constructed based on the kinematics model of the sprayer.The upper controller used the model predictive control algorithm based on the kinematic model of sprayer.According to the desired path and current position information,the actual output steering angle and vehicle speed were solved to achieve path tracking.In the lower controller,the tire slip controller is constructed by fuzzy control and integral separated PID control,so as to realize the effective control of path tracking,vehicle speed and tire slip,which can effectively improve the control stability and path tracking accuracy of the spray machine under complex working conditions.(3)The co-simulation platform was constructed by MATLAB and ADAMS View simulation software to verify the control algorithm.The influence of model predictive controller parameters on the path tracking control accuracy was analyzed.The Road Builder in Adams/Car was used to set up the road file to simulate the complex field road and the distance of the spray machine deviating from the desired path and the change of the slip rate of the driving wheel in the process of straight and turning were analyzed to verify the effectiveness of the control algorithm.(4)Build the spray machine path tracking control experimental platform.The real-time position information of sprayer was measured by high precision differential GPS positioning system.The information interaction and drive control between ADX(A&D5436)controller and experimental platform were realized through CAN bus communication.By analyzing the tracking control effects of sprayer under different path conditions,the tracking performance of the layered path tracking control system considering the slip of driving wheel was verified.This paper verifies the tracking performance of the layered path tracking control system with consideration of driving wheel slip.Experiments shown that the tracking control algorithm studied in this paper had high tracking accuracy and can adapt to complex working conditions and meet the needs of precision agriculture.