## 3 Results
### Simulation Results
#### 3.1.2 Results and Analysis of the Loading Box Fully Loaded with Bee Frames  
When the loading box is fully loaded with bee frames, variations of the roll and pitch values of the vehicle under each road condition on 8\({}^{\circ}\) upslope and downslope are shown in Figure 19. In the roll direction, the maximum range of angle change was (\(-\)0.15-0.25\({}^{\circ}\)). As the vehicle was driven on the 8\({}^{\circ}\) upslope, the left and right wheel settings had extremely small errors, and as a result, the vehicle in the process of going up and down the slope in the driving direction of a slight steering. The change in the yaw direction caused a gap in the pressure carried by the left and right wheels, which led to a marginal change (\(-\)0.1-0.3\({}^{\circ}\)) in the roll direction. However, the angle change was not significant, meaning that the vehicle was stable in the roll direction when traveling uphill. In the pitch direction, the vehicle started in the horizontal position, drove uphill, drove downhill, and finally returned to the horizontal position. The head-up phenomenon occurred to different degrees in the pitch direction under the three different road conditions, with dry sand representing the most severe head-up circumstances during transportation with an angle change of 15.19\({}^{\circ}\), followed by clayey soil and upland sandy loam, which, too, generated considerable head-ups, respectively, with the maximum angles of 11.77\({}^{\circ}\) and 12.75\({}^{\circ}\). However, according to the calculation of the maximum uphill limit inclination angle of the transporter, the limit uphill angle of the transporter when fully loaded with bee frames is 40.7\({}^{\circ}\); thus, the condition of safe transportation is satisfied. Figure 18: Velocity variation of bee frame in each direction under upland sandy loam conditions during s-curve driving. Variations in the roll and pitch values of the vehicle under each pavement condition with full loading of bee frames during s-curve driving are shown in Figure 20. In plane driving, because both sides of the track are subjected to different ground pressures, the transport vehicle will oscillate to a certain degree when driving through the two curve sections. The figure can be seen that the roll angle change at the three road conditions in the range of (\(-1\)-\(1\)deg), so the vehicle in the s-turn roll direction stability need not be concerned. The change in the pitch direction shows that, similar to the upslope and downslope driving conditions, the largest pitch change angle of 2.23 deg occurs under the dry sand condition. The next largest change was recorded in upland sandy loam, with a maximum value of 1.38 deg. The smallest variation was recorded in clayey soil, with a maximum value of 0.84 deg. According to the figure, the pitch angle reaches the maximum value of 2.24 deg when the vehicle first starts on the three types of road surfaces, while the pitch angle of the vehicle gradually returns to normal after the vehicle enters the uniform straight-line driving section. The rate of change of the pitch angle during turning is higher than that when the vehicle moves along a straight line, which is consistent with reality. The maximum pitch angle of the vehicle during driving on the horizontal ground is 2.24 deg, which is considerably smaller than the maximum uphill limit angle of 40.7 deg. It means that the vehicle can be driven stably and normally on a horizontal road. A box plot of the variations in the roll and pitch values of the vehicle under each road condition when the loading box is fully loaded with bee frames is shown in Figure 21. It can be seen that the trend of roll direction change is significantly correlated to road conditions, terrain conditions, and other factors, and the range of angle change is within (\(-0.8\)-\(0.8\)deg).