# Research on Global Navigation Operations for Rotary Burying of Stubbles Based on Machine Vision
## 4 Conclusions  
In this paper, aiming to examine the phenomenon that only the driver's subjective feeling can lead to retillage and missed tillage, the research group selected the Hough matrix and RANSAC to obtain the optimal navigation starting path, the bow-shaped turning mode, and the maximum interbank nesting path planning mode suitable to complete the unmanned straw rotary burying and returning operation. The main conclusions are as follows:  
(1) Regarding the starting route, which is one of the key points in the path planning of nesting paths, this paper proposes an algorithm for extracting the starting route of the field boundary by combining the Hough matrix and RANSAC algorithm. The algorithm uses the H component to segment the image and extracts the boundary of residual straw as the target path. Then, after denoising and smoothing the image via morphological operation, the midpoint of the target path is determined by line scanning. Finally, the Hough matrix is used to extract feature points and remove redundant points, and the RANSAC algorithm is used to reduce the influence of noise points caused by different straw shapes and improve the accuracy of initial route extraction. Experiments show that this method takes less than 0.51 s to identify the initial route in different scenes, and the average recognition accuracy is over 90%, which meets the requirements of extracting the initial route of returning straw to the field by rotary burying.  
Figure 23: Measurement of tillage depth after rotary burying operation.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**System** & **Parameters** & **Value** \\ \hline \multirow{3}{*}{Auxiliary navigation systems} & Maximum deviations/m & 0.133 \\  & Average absolute deviation/m & 0.047 \\  & Standard deviation/m & 0.052 \\ \hline \multirow{3}{*}{Depth of tillage control system} & Average plowing depth/cm & 13.3 \\  & Tillage depth stability factor/\% & 88.35 \\ \cline{1-1}  & Burying rate/\% & 91.41 \\ \hline \hline \end{tabular}
\end{table}
Table 8: Lateral deviation results of tracking in field.  
(2) For the polygonal field, this paper chooses the bow-turning mode. Because the rotary burying operation distance is fixed, in order to reduce the turning paths, this paper makes a hypothetical analysis of the number of turning paths starting from different positions of convex polygonal fields. The results show that the starting operation along one side of the boundary of the fields is the initial route with the least turning paths for the rotary burying and returning operation unit.  
(3) Regarding the field rotary burying operation of the straw rotary burying machine set, this paper adopts the maximum number of cross-line operation paths to design the nesting path, which ensures the smooth running of the nesting rotary burying operation on the premise of avoiding the reversing of the machine set as much as possible. Finally, the road test of the nesting path was carried out. The test shows that the nesting path designed by the research group conforms to the characteristics of a large turning radius with no reversing when the straw rotary burying machine is working, and the path design is suitable for the auxiliary navigation operation of the straw rotary burying machine.