Rice Autonomous Harvesting: Operation Framework

This paper reports on an operation framework for autonomous rice harvesting. We developed an integrated algorithm for robotic operation and cooperation with farmworkers to automate each subsection of the harvesting and unloading process and of the processes that bridge them (homing and restarting). The algorithm was installed into a head‐feeding combine robot. The robot followed a target path based on its absolute position and orientation, planning a counterclockwise spiral path in a rectangular paddy field, and returned to a position close to a farm road when its grain tank was filled to a specified level. The grain unloading operation was automated using a machine vision system. As the restarting process (return to harvesting) was also automated, the combine robot was able to harvest a rectangular field autonomously by cyclically repeating the harvesting, homing, unloading, and restarting operations. Under field conditions, the robot was able to follow the target path within tolerable lateral and azimuth errors while harvesting rice successfully, and to unload the harvested grain into a wagon without spillage. The root mean square error of the lateral and azimuth errors during harvesting were 0.04 m and 2.6°, respectively. In the homing operation, the robot returned to a given line within ± 0.1 m and aligned its heading to the direction of the line within ± 4°. The robot recognized the arbitrarily parked wagon and positioned its auger spout at the target point with a respective horizontal and vertical accuracy of ± 0.2 m and ± 0.3 m. Harvesting time accounted for 50%–60% of the entire robotic operation. Homing scheduling and dispatch control for the wagon were found to be of importance for developing a more efficient robotic operation.