Path planning of multiple mobile robots considering agricultural work and its application to automatic carriers

Abstract

In automatic harvesting of vegetables such as cabbages which are loaded in containers, autonomous driving of carriers is needed to carry containers. In order to operate multiple harvesters in a wide field such as in Hokkaido, it is necessary to run multiple carriers at the same time. The carrier needs to switch from forward to reverse for connection with the harvester. Moreover, the crop area decreases and the drivable area changes as the harvest progresses. In this paper, we propose a path planning method for multiple carriers that considers these features and shortens the total waiting time of harvesters after they finish harvesting in order to maximize farm work. In this method, the optimal paths are decided by Conflict Tree expansion. A path planning method of single agent considering the switching to reverse from forward is also proposed. In the actual driving, speed control is performed to avoid collision considering time lag from expectations of path planning. Finally, we show experimental results and explain the effectiveness of the proposed method. Sliding mode control is used for autonomous driving of the harvester and carrier. We confirmed that our method allows vehicles to travel simultaneously without collision or being stuck.

Keywords

• path planning
• autonomous driving
• harvester
• carrier
• multi-agent path finding
• sliding mode control
• agricultural vehicle
• automatic harvesting