# Path Planning Strategy for Implementing a Machine Control System in Grader Operations
## 3 Path Generation Algorithm for Graders
### Heuristics of Grader Operators and Site Managers
\begin{table}
\begin{tabular}{c c c} \hline
**Question** & & **Answer** \\ \hline Way of working & - & Patterning \\  & - & Material handling \\ \hline Maximum forward distance & - & None \\ \hline Work line work sequence & - & Depends on type of task \\  & - & Used for both work from the outer line \\  & & and work from the middle \\ \hline Criteria for selecting a work line & - & Length of work area \\   change method & - & Width of non-working section \\  & - & Operator’s convenience \\ \hline Blade repeated rate by line & - & Typically, 50\% \\  & - & May vary depending on workload \\  & - & Sometimes almost no overlap \\ \hline Maximum length of one forward movement & - & Depends on type of task \\  & - & There is no limit to the advance distance \\  & & when there is not much material. \\  & - & If there is a lot of material, it is limited to \\  & & around 5 m. \\ \hline Outer line work method & - & Work with some fill and blades \\  & & protruding beyond the line, leaving room \\  & & for road width. \\ \hline Work pattern & - & Figure 3. \\ \hline \end{tabular}
\end{table} 
Table 1: Heuristic survey of motor grade operators for grading. \begin{table}
\begin{tabular}{c c c} \hline
**Question** & & **Answer** \\ \hline
3-point turning method & - & Long work area (Over 200 m) \\  & - & Need for non-work area \\ \hline Turning after backward method & - & Short work area (Under 200 m) \\  & - & Need for non-work area \\ \hline Turning while backward method & - & Short work area (Under 200 m) \\  & - & No need for non-work area \\  & - & Mainly used method \\ \hline \end{tabular}
\end{table} 
Table 2: Heuristic survey of grader work line change method. The commonly used methods for changing work lines include the 3-point turning method, turning after the backward method, and turning while reversing. Although there are simple turning methods, they are excluded from this study because of the large turning radius of the grader, which requires a wider non-working area. The 3-point turning method involves completing work in the work area and then changing the direction using three points: moving forward, reversing, and moving forward again [see Figure 6a]. This method is typically used for work areas longer than 200 m and requires a non-working zone outside the work area to accommodate the grader's turning radius. Figure 4: Concept of repeated area and effective width. Figure 5: Motor grader work patterns. The turning after the backward method involves changing the work lines after reversing. As shown in Figure 5(b), this method entails reversing along the worked line, moving backward further into the nonworking area, and then advancing to the starting point of the next line. It is used for relatively short distances of less than 200 m and requires a non-working area. The turning while backward method involves changing the work line while reversing, as depicted in Figure 5(c). This method involves reversing from the end of one line to the starting point of the next line. It is used for distances of less than 200 m and does not require a non-working area because the line is changed while reversing. This method is predominantly used when the working area is short.