# Path Planning for Laser Cladding Robot on Artificial Joint Surface Based on Topology Reconstruction
## 5 Experimental Validation
### Simulation Experiment  
The robot model is NACHI MZ04 from Japan and the simulation module named \"FD on Desk\" matches with the robot. As shown in Figure 14, after adding the entry and exit points, the text file was imported into the simulation module and compiled into the executable file of the robot program. First of all, the simulation environment was set up according to the actual working conditions. Then, the compiled robot program file was inputted into the simulation model to run in automatic operation mode.  
Some different positions and poses of the robot during the simulation process are shown in Figure 15. After the automatic operation started, the TCP of the robot moved from the original position to the entry point and then experienced each interpolation point one by one along the path. Finally, it went through the exit point and returned to the original position. The results showed that the TCP of the robot moved exactly along the planned interpolation path. Furthermore, in the whole simulation process, the robot achieved a complete and continuous movement without mechanical collision occurring or exceeding the range of motion. The relative position relationship between the laser beam and the surface of the acetabular cup was shown through different angles. During the laser cladding process, the laser beam was always vertical and perpendicular to the processed surface.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**STL File Size**} & \multicolumn{3}{c}{**Original Data**} & \multicolumn{3}{c}{**Data after Topological Reconstruction**} \\ \cline{2-7}  & **Facet** & **Edge** & **Vertex** & **Facet** & **Edge** & **Vertex** \\ \hline
402 KB & 3656 & 10,968 & 10,968 & 3656 & 5527 & 1872 \\ \hline \begin{tabular}{c} **Number of Direct** \\ **interpolation points** \\ \end{tabular} & \begin{tabular}{c} **Number of simplified** \\ **interpolation points** \\ \end{tabular} & \
\begin{tabular}{c} **Compression ratio of** \\ **interpolation points** \\ \end{tabular} &
\begin{tabular}{c} **Elapsed time** \\ **interpolation points** \\ \end{tabular} \\ \hline
850 & 74 & 8.7\% & \textless{}30 sec \\ \hline \hline \end{tabular}
\end{table}
Table 4: Results of automatic path generation.  
Figure 14: (a) Text file of robot program. (b) The compiled robot program.  
Figure 16 shows the changes of the robot pose angles during the simulation process. From those pictures, we can see the roll angle \(\alpha\) changes from \(-180^{\circ}\) to \(180^{\circ}\), which indicates the robot [PERSON] rotates around the X axis of the world coordinate system for circular motion, and the pitch angle \(\beta\) and the yaw angle \(\gamma\) changes from \(-90^{\circ}\) to \(90^{\circ}\), which indicates the robot TCP rotates around the Y and Z axis of world coordinate system in a half circular motion, respectively. The data results are consistent with the desired results of robot motion. The five cycles of smooth robot pose angles indicates that the robot [PERSON] completes the whole motion correctly along the full path consisting of five parallel transversal lines. There are no singularities and drastic change of the robot pose in the motion process.  
In a word, the simulation results preliminarily confirmed the correctness of the path automatically generated from the path planning module as well as the path planning method proposed in this paper.