A low-cost guidance system was developed for a global positioning system (GPS)-guided
automated rice transplanter. In 2005, the already available GPS-guided automated rice
transplanter was modified to carry long mat-type hydroponic rice seedlings and attached an
herbicide-dripping machine. The use of long mat-type hydroponic rice seedlings allows ricetransplanting
operations to be carried out on a 0.3 ha standard-size Japanese field without the
need to supply additional seedlings. Fully automated rice transplantation was achieved with the
modified transplanter. To reduce the costs of the transplanter, the expensive fiber-optic posture
sensor was replaced by a low-cost posture sensor, developed at Hokkaido University, for
measuring the heading angle and inclination. The processing program of this posture sensor was
modified to adapt it to rice-transplanting operation. Instead of establishing a reference station, a
real-time, kinematic GPS was used. The modified rice transplanter, when tested in planting a
farmer’s paddy field took about one hour between entering and leaving the field. The trial was
almost successful, with a few minor problems.