Research On Key Technology Of Automatic Navigation Of Green Onion Harvester

China is a major exporter of agriculture and vegetables,and the scale of the green onion industry ranks first in the world.Green onions have become an important economic product to promote the development of China’s rural economy,and the green onion industry has become an important pillar for the revitalization of some rural areas.The standardization,mechanization and intelligent harvesting level of green onions have become the key to its industrial development,and seriously restrict the further improvement of the economic benefits of green onion planting,among which automatic navigation technology is the key technology representing the intelligent harvesting level of green onion harvesters.Based on the design of the green onion harvester,this paper combines visual technology to study the key technologies of automatic navigation such as path planning,motor speed control,and path tracking.The main research contents include:(1)Overall design of green onion harvester.Taking the structure and planting mode of green onions as the starting point and combining the design requirements of green onion harvester,a twisted auger combination excavation mechanism is adopted to carry out the overall structure design of green onion harvester and the design of the whole machine drive scheme.Based on the kinetics and kinematics theory of the harvester,combined with the technical parameters of the green onion harvester,the design and selection of each element of the entire drive system were completed.(2)Research on field harvesting operation path planning of green onion harvester.The global path planning of the green onion harvester was divided into the navigation line and the turning path of the green onion ridge,and the original image was preprocessed by G-R algorithm,maximum between-class variance method and image morphological operation to successfully separate the green onion ridge with good connectivity from the soil background.Furthermore,the navigation key points were extracted based on the edge features of green onions,and the navigation line extraction was quickly and accurately completed by applying the least squares method,and the optimal turning path based on semicircle was studied and determined based on the operation requirements of the green onion harvester.(3)Research on motor speed control of green onion harvester.According to the working principle of each link of the pump control motor system,the mathematical modeling of the motor speed control system is carried out,the transfer function of the system open and closed loop control is determined,and the working principle of the PID controller and the traditional parameter setting method are analyzed.Aiming at the shortcomings of the traditional parameter setting method of PID,the fruit fly optimization algorithm and PID control are combined to find the optimal parameters of PID control,and the motor speed tracking test of various types of signals under load disturbance and without load disturbance is completed,and the results show that the motor speed controller designed in this paper has good control effect and meets the design requirements,and then can realize the accurate control of turning radius.(4)Research on path tracking control of green onion harvester.According to the high-precision requirements of the green onion harvester in autonomous navigation operations,a pure tracking algorithm for dynamic forward viewing distance is proposed.According to different speeds,different basic values of forward viewing distance are set,and then a two-dimensional fuzzy controller is designed with distance deviation and direction deviation as input,which realizes the dynamic adjustment of forward viewing distance.The simulation results show that the control method designed in this paper has small distance error and fast convergence speed,and the simulation effect is good,which can meet the automation requirements of green onion harvester.