This study was conducted to ascertain whether a physics engine is applicable, or not, to predict the critical height of a frame, or tip-over protective structure (TOPS), for an agricultural carrier on a slope. Sideways overturning behaviors of both three-wheeled and four-wheeled agricultural model carriers were investigated using a physics engine: Bullet. Results demonstrated that the predicted critical height of TOPS was similar to that of experimentally obtained results for both the three-wheeled and four-wheeled model carriers. With its capability of calculating friction, restitution and its interaction with the vehicle, the physics engine can simulate sideways overturning behaviors of agricultural carriers more realistically than the use of OECD code originally developed for agricultural tractors.

A combine harvester concave was developed to reduce staining during soybean harvest. Preliminary tests showed that one of the causes of soybean staining is that high-moisture stems become entangled in the concave, remain in the thresher, and come into contact with the soybean grains. Newly designed concaves with freely revolving rollers were placed around threshing cylinder, and their performance was studied. The roller concave with a roller of diameter 21 mm arranged at a gap of 18 mm or 24 mm showed less staining compared to standard concaves. Its grain distribution under the concave, threshing losses, and torque for driving the threshing cylinder were equal to that of standard concaves.

We developed a highly efficient trimming machine for spinach and evaluated it experimentally. Once harvested plants were manually placed on its feeding unit, the machine cut roots by the rotary cutter and trimmed lower leaves by the urethane brush with high accuracy. The average length of the root remained to the plant was 6.9 mm and the standard deviation was 1.4 mm. The average trimming capacity was 94.3 %, which is higher than that for the conventional machine rate at 74.9 %. Conventional machines need four workers to operate, and the work efficiency was 508 plants/h·person. This machine needs only two workers, and the work efficiency was 926 plants/h·person, exhibiting an improved work efficiency compared to conventional machines.

With conventional rice transplanters, float depth was adjusted manually by the operator based on their own experience. However, in order to move to an automatic height control system which can respond to the diversification of environmental conditions arising from regional and agricultural management policies, a new function has been developed by which the degree of float subsidence is detected by a rake sensor, allowing a constant depth to be maintained.

As a result of quantitative performance evaluation conducted during bench testing, the gain obtained using the Taguchi Method was confirmed as improved SN ratio of 9.7 dB and float subsidence of 4.5 dB.