# Simulation of the Rollover Angle of a Self-Propelled Radish Harvester for Different Load Conditions
## 4 Discussion  
This study focused on evaluating the rollover of a self-propelled radish harvester prototype to confirm if it satisfied the standard overturning angle and deriving a plan to improve the rollover angle. The simulation results of the rollover angles were validated by an indoor test for three levels of weight (50, 100, and 150 kg) installed at three positions (front, center, and rear) of the radish harvester and analyzed statistically. The statistical analysis showed the linear relationship between the simulation and experimental rollover angles with R\({}^{2}\) to be 0.911 and 0.9589, respectively. This indicates that both simulation and experimental results are a similar trend. It was also shown that the rollover angle of the radish harvester was less than 30\({}^{\circ}\) at a deflection angle of 180\({}^{\circ}\). To address this issue, we conducted a further simulation, which included additional load at three locations to improve the rollover angle. We confirmed that the tilt angle of 31.71\({}^{\circ}\) can be obtained by attaching an additional load of 50 kg to the front of the radish harvester. However, it was observed that to satisfy the standard rollover angles, the minimum 150 kg weight should be attached in the center and rear positions of the radish harvester. Therefore, in the case of the center or rear of the radish harvester, we suggest that the users of the harvester during operations attach at least 150 kg of weight to satisfy the standard rollover angles and ensure safety. In comparison with the literature, these rollover angles were similar to those of 30-30.5\({}^{\circ}\) for a tractor-attached radish harvester [31], 37.89\({}^{\circ}\) for a hot pepper harvester [11], and 47.2\({}^{\circ}\) for multipurpose agricultural machines [30]. [PERSON] et al. [31] studied a tractor-mounted radish harvester and reported a similar finding. They stated that right longitudinal overturning occurred at least 30.5\({}^{\circ}\) of the tilt angle, and left longitudinal over  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Installation** & **Additional** & \multicolumn{8}{c}{**Deflection Angle (\({}^{\circ}\))**} \\ \cline{3-10}
**Positions** & **Weight (kg)** & **0 (360)** & **45** & **90** & **135** & **180** & **225** & **270** & **315** \\ \hline Front & & 46.2 & 60.69 & 41.79 & 41.02 & 31.71 & 41.02 & 42.7 & 56 \\ Center & 50 & 48.3 & 61.04 & 41.86 & 41.02 & 29.19 & 41.02 & 42.7 & 5 turning occurred at a tilt angle of 30\({}^{\circ}\). According to agricultural machine test standards [34], the tilt angle of the agricultural machinery was acceptable at less than or equal to 30\({}^{\circ}\). According to the ISO 16251-2 [20], the range of the overturning angle is 15-45\({}^{\circ}\), which is the allowable standard. However, [PERSON] et al. [31] reported that the range of the tractor-mounted radish harvester overturning angle was 30-52\({}^{\circ}\) but they did not consider the load. In this study, the minimum longitudinal overturning angle was 29.19-33.25\({}^{\circ}\) for all load conditions that satisfied the recommended standard. Therefore, the stability analysis of the self-propelled radish harvester indicated that the harvester could comfortably operate on a field with a slope of 30\({}^{\circ}\). On the other hand, [PERSON] et al. [35] analyzed the lateral overturning of the forwarder according to driving speed and whether or not wood was loaded using a multibody dynamics analysis program. They reported that, as the forwarder's CoG increased due to the loaded woods, the stability of the lateral roll was reduced. They also reported that forwarders loaded with wood had to reduce their driving speed by at least 20% compared to those without wood. The higher the obstacle and the smaller the approach angle, the higher the risk of lateral overturning. According to the above studies [35], the lateral overturning angle can be significantly different depending on the agricultural machine's speed and load weight.