## 4 Recognition and Operation of Facade Protrusions
### Matching of Process Parameters  
The concept of process parameter matching: the robot takes the object dimensions and depth information obtained in the previous steps to filter the process parameters under the operation to be performed, and then obtains the required process parameters. Due to the dynamic operation of the wall-climbing robot and the need to dynamically adjust the process parameters for different operations, the process parameters are derived from the dimensions, the depth information obtained in the previous step and the matching of the process parameter database. The process parameters are matched in the following steps: firstly, the corresponding process parameters \(B\) and \(C\) are obtained according to the current operation. Then, all process parameters under the facade protrusion are obtained based on the previously obtained dimensions \(\{B11\,b11,\,b21,\_,bi1\_,\ldots,\,bm1\}\). Finally, the process parameters under the current facade protrusion distance are selected \(\{B21\,b12,\,b22,\,\ldots\,\,bj2\,\ldots\,\,bm2\}\) in order to complete the dynamic operation. The process parameter-matching pseudocode is as follows (Algorithm 2):  
```
1:dimension of the facade-protrusion \(s\), measuring distance \(m\), process parameter database \(B\)
2:Process parameters \(P\)
3:\(L\)\(\leftarrow\)0//Storage of filtered process parameters
4:If (select the rust removal function) then
5:for each \(bi1\) do//Filter data according to dimension
6:if\(bi1=s\)then
7:\(L\)\(\leftarrow\)\(\{bi2,bi3\,\ldots



The process parameters for rust removal operation such as liquid pressure, distance from the gun, gun movement speed and spraying widths are shown in Table 2.

The process parameters for painting operations, such as liquid pressure, distance from the gun, gun movement speed and painting widths, are shown in Table 3.

The range of swing angles for the gun needs to be determined for each type of operation. The swing angles include the pitch swing angle and the horizontal swing angle. The pitch swing angle range requires that the height of the facade protrusion can be covered, and the horizontal swing angle range is designed to cover the facade protrusion width with an additional 10% of the operation range. Depending on the dimensions of the facade protrusion and the distance between the facade protrusion and the gun, the database of swing angles is created. Using a facade protrusion with a diameter of 20 cm and a height of 20 cm as an example, the swing angle is calculated for different distances. The parameters of swing angles are shown in Table 4.

## 5 Operation Effect Inspection and Feedback Adjustment

The main purpose of the operation effect inspection is to determine whether the operation meets the requirements by detecting the missed painting distance and the effect of rust removal (e.g., incomplete rust removal due to low liquid pressure). When the operation does not meet the requirements, the process parameters are adjusted, and the robot starts operation and inspection again until the operation meets the requirements. The flow chart of the facade operation and inspection and process parameters adjustment is shown in Figure 5. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Distance from the Gun (mm)** & **Pitch Swing Angle (°)** & **Horizontal Swing Angle (°)** \\ \hline
500 & 12.05 & 19.85 \\
600 & 10.13 & 16.59 \\
700 & 8.81 & 14.25 \\
800 & 7.67 & 12.48 \\
900 & 6.88 & 11.10 \\
1000 & 5.13 & 10.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Database of gun swing angles at different distances. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Liquid Pressure (MPa)** & **Distance from the Gun (cm)** & **Gun Movement Speed (cm/s)** & **Spraying Widths (mm)** \\ \hline
1 & 500 & 2 & 30 \\
1.2 & 600 & 2 & 30 \\
1.4 & 700 & 2 & 30 \\
1.6 & 800 & 2 & 30 \\
1.8 & 900 & 2 & 30 \\
2.0 & 1000 & 2 & 30 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Database of process parameters for rust removal.