DESIGN OF AGRICULTURAL TRACKED ROBOT BASED ON THE SLIDER-CRANK MECHANISM PRINCIPLE FOR NAVIGATION

摘要

For raising automation level of orchard precision management, decreasing the management cost, and promoting the application of robot products, an orchard tracked mobile robot was designed in this paper. As a mobile platform, this robot will be used in orchard management, such as variable spraying and fruit picking. Aiming at some of the current problems on handle and path tracking in complex orchard environment, a rubber pipeline whose diameter is 4 centimeters was laid down in the orchard as the path of the robot, and a method based on the principle of slider-crank mechanism for navigation was used in this paper. The orchard robot was composed of robot body and robot guiding mechanism: robot body including basic mechanism, battery, PC control system and DC servo driven system; robot guiding mechanism including guiding wheel, two potentiometric sensors and a shaft that connects guiding wheel with robot body. Every side of robot track was driven by a DC servo motor to control the robot moving and steering. Robot body, rubber pipeline and robot guiding mechanism would constitute a slider-crank mechanism after the robot guiding wheel contacted with the rubber pipeline.In the slider-crank mechanism, the robot body is the crank, the shaft is the linkage and the guide wheel is the slide. Two potentiometric sensors were used to detect the position and attitude of the robot, the speed of the tracks was controlled through the Fuzzy-PID controller to control the lateral deviation between robot centroid and rubber pipeline. The experiments showed that the maximum tracking error was less than 0.02m when the robot moved straight at the speed of 0.15m/s, and the maximum tracking error was less than 0.05m when the turning radius was 2m. Rubber pipeline can change the path on demand, reduce management cost and improve flexibility of the use of the robot. Orchard precision management, such as pesticide spraying and fruit picking will be realized after putting up spraying system and manipulator on the mobile robot platform.