Elucidating rice transplanter’s behavior is important for the safety. In this study, a model of a rice transplanter with four degrees of freedom and installed with a fixed front axle was considered. Vibrations from the planting mechanism were also considered. The parameters of the model were identified based on experiments. The rice transplanter’s behavior on accident site was simulated, and the influences of the speed and mass center position on an anteroposterior fall were considered. The results showed that when the running speed is 0.09 m/s or lower, the influence of speed on the anteroposterior fall is small and the optimum location of mass center position is at a distance of 46 %-48 % of the wheelbase from the rear axle.

We examined a method of analyzing an electrocardiogram (ECG)-photoplethysmogram (PPG) simultaneous measurement signal with the aim of developing a diagnosis method of the mind and body condition for visualization of the fatigue state of farm workers. The time delay between ECG and PPG signals was determined with a cross-correlation function. The time delay was found to differ significantly among subjects. In addition, we investigated the possibility of using a Poincaré section as a new method of detecting the nonlinear feature of the PPG. The method of generating the Poincaré section of the PPG using the ECG as a trigger was demonstrated to reduce the scattering of plots when compared with the method of using the average period of the PPG, and the proposed method is considered to be effective in grasping the structure of dynamics.