Researches On Design And Control Of The Weeding Robot

The substance of the Precision Agriculture is to take measures to eliminate diversity, optimize resource configuration, make prescription for the crop, and gain the most benefit from the invest and the environment. The agricultural robotics, combining with the mapping in crop field, the Variable Rate Technology, and decision-making support system, will play a principal part in the modern agriculture.This research is mainly on the key techniques for the weeding robot based on the direct herbicide application and aims to make the weeding activity basically finished by the robot. The main objects of this project are: 1) high-efficiency, automation and reduction of human labor; 2) precise and selective herbicide application avoiding hurting crops; 3) significant decrease in the quantity of herbicide application compared with traditional spraying herbicide method, protecting the environment.Three different aspects were concerned based on the machine vision:①developing a motion control technique for the robotic arm, actualizing the automatic weed control.②developing a fuzzy control algorithm for the weeding robot navigation according to the crop line directrix, actualizing the autonomous navigation.③developing a variable rate control technology for the direct herbicide application, preliminarily actualizing the automatic herbicide supply control of the robot.Applying the AutoCAD modeling and optimization design, we manufactured a four-joint robotic arm corresponding to the robot body and established the working space. Kinematics analysis and synthesis for the robotic arm were completed. And we got the Jacobean matrix and developed motion control program by VC++. The robotic arm was controlled by the SSC-32 servo board (Lynx motion Co.), thus the weed plant accurate localization was achieved.Considering diverse and open farmland surroundings, we developed a fuzzy navigation control algorithm by VC++. From enormous experiments, we gained respective distribution rule of offset (λ)and heading angle(θr) in the corresponding universe of discourse, the relationship betweenθr,λand the robot's current pose, and the correlation between robot's longitudinal heading rate and speed difference for pose adjustment. Membership function satisfying parameter character was acquired from the robot control rules so that the fuzzy control navigation was realized. The test showed the fuzzy control effectively compensated the defect of navigation analysis algorithm and highly improved reliability.We designed a variable rate system for weeding robot's end-effector for direct herbicide application method. A circuit board for development was made and programmed. The control of cutter rotating speed and solenoid valve for herbicide application supply time was achieved.