農業移動ロボットの研究(シミュレーションの世界)  [in Japanese] Research of Farm Mobile Robots  [in Japanese]

This paper introduces research on agricultural robots, especially the wheel-type mobile robots for agriculture. The history of agricultural mechanization in Japan began with mechanization for rice production in paddy field. Nowadays, soil tillage is done by a tractor rotary-tiller combination and puddling is done by a tractor puddling rotor combination. Transplanting operation is performed by a self-propelled rice transplanter and harvesting is performed by a head-feeding combine. Research on agricultural robots being done at present are classified into two categories and targets: agricultural automation and environmental protection in agriculture. Five robot related research are summarized as follows: 1) Yukumoto et al. development of tillage robot. This involved an autonomous tractor ran in the field and tillage performed automatically. 2) Rise et al. performed sensor fusion related research for navigation of farm mobile robot. This was done using RTK-global positioning system (GPS) and fiber optical gyro (FOG). 3) Mizushima et al. developed low price navigation system. Rectlinear autonomous traveling was accomplished by the inner sensor method using GDS and FOG. 4). Nishiike et al. developed the paddy-field management robot. Rectlinear autonomous traveling was fesible in the paddy field filled by water. Our research targeted autonomous mobile robot for sloped terrain. Firstly, we formulated the input-output relationship between steering angle and state vectors (x-y positions and heading angle of tractor) on the sloped terrain using neural networks (NN). Secondly, applying the NN vehicle model and genetic algorithm (GA), we calculated the optimal steering strategy for running along the contour line on the sloped terrain. Finally, we succeeded in autopilot run along the contour line on the slope terrain using a proto-type tractor (25 PS). A uniform approach about robotization of a agricultural machine is not yet reached among researchers. My personal opinions about a field robot are summarized as follows: 1) For the running system of agricultural vehicles, Ackerman steering system or crawler system would be adequate since these two systems are superior to off-road locomotion. 2) During early agricultural mechanization stage in Japan, special-purpose oriented machines such as a rice tranplanter or a combine were used commonly, however in robotization for future agriculture, a single platform as running system should be utilized and various farm works should be done by exchanging robotic manipulators.