## 3 Results  
### Simulation Results  
#### 3.1.1 Results and Analysis of the Transportation of a Single Bee Frame  
Herein, the results of multiple tests involving three geologies and two different advance methods are compared to illustrate vehicle movement in different geologies. The X-direction represents the left-right change direction, also called the roll direction. The Y-direction is perpendicular to the ground, while the Z-direction represents the front-to-back change direction, also called the pitch direction. First, displacement variation of the bee frame centroid in the XYZ directions under the condition of 8\({}^{\circ}\) upslope and downslope is shown in Figure 16. The figure shows that under the three soil conditions, the bee frame is the most stable along the Z-direction in clayey Soil, followed by dry sand, and upland sandy loam. The variations in the X- and  
Figure 15: Position of center of gravity: (**a**) loading box fully loaded with bee frames and (**b**) loading box fully loaded with beehives. Y-directions are between \(\pm\)0.1 mm, and there are no significant differences. Throughout operation under the conditions of 8\({}^{\circ}\) upslope and downslope, the centroid of the bee frame had the most extensive range of variation in the Z-direction (\(-\)1.573-0.490 mm), followed by the X-direction (\(-\)0.060-0.066 mm), and the Y-direction (\(-\)0.0059-0.0700 mm). The trend of the Z-direction changed in the negative direction first and then in the positive direction. When the tracked vehicle first traveled uphill and then downhill, under the action of inertia, the bee frame first moved toward the negative Z-axis direction and then converged to 0. The variation range (\(-\)1.573-0.490 mm) was less than the size between the space of the bee frame placement and the length of the bee frame in the loading box (\(-\)2.5-2.5 mm). In the simulation, variation of the bee frame centroid displacement in the X-direction with a variation of less than 0.1 mm in the Y-direction was insufficient to affect the stability of the bee frame during transportation. Figure 16: Variation of relative displacement in (**a**) the X-direction of the bee frame (8\({}^{\circ}\)), (**b**) Y-direction of the bee frame (8\({}^{\circ}\)), (**c**) Z-direction of the bee frame (8\({}^{\circ}\)), and (**d**) range of XYZ direction for the bee frame (8\({}^{\circ}\)). In the box diagram of the 8\({}^{\circ}\) upslope and downslope, the values of X and Y directions are around 0, which means that vibrations in the left and right and up and down directions were small during the movement of the bee frame, and safety was not a concern. The variation in the Z-axis direction was mainly negative because the vehicle moved backward relative to the direction of the bee frame movement on the upslope and downslope due to gravity, and it moved forward along the direction of movement on the downslope. However, the deviation range between the maximum and the minimum values was 3 mm at most, which did not exceed the free motion range of the bee frame in the loading box. Therefore, the experimental results are consistent with common sense, and the bee frame can be transported stably on the 8\({}^{\circ}\) upslope and downslope. The displacement variation of the bee frame centroid under s-turn conditions is presented in Figure 17. In the s-turn transportation process, the free fall process lasts for 0-2 s. Therefore, in the figure, 0-3 s represents a straight line in the forward direction. It is presented that for 0-3 s, almost no change occurs in the bee frame along with the XYZ directions. During 5-15 s in the counterclockwise turning stage, the vibration of the bee frame centroid in the X- and Y-direction increases gradually. The ranges of variation in the X-direction are (\(-\)0.73-0.59 mm) in clayey soil, (\(-\)2.49-0.88 mm) in dry sand, and (\(-\)9.45-10.29 mm) in upland sandy loam. The ranges of variation in the Y-direction are 0-0.28 mm in clayey soil, 0-0.125 mm in dry sand, and 0-2 mm upland sandy loam, followed by convergence at 0.