# Improvement of the Sensor Capability of the NAO Robot by the Integration of a Laser Rangefinder
## 3 Results
### Measurement Results
#### 3.2.2 Test #2 Measurement Results  
Scenario #1  
Figure 12 shows the measurement setup and the results of test #2 (scenario #1). The robot was placed at an initial distance of 200 cm (Point A in Figure 12) from one of the corners of a box sized 60 \(\times\) 50 \(\times\) 60 cm. The room is the same as test #1 (as shown in Figure 9), but the robot travels horizontally towards the left wall. In particular, the robot advanced towards this obstacle, while the rangefinder device continuously took measurements and stored them in the proper memory area. Moreover, the robot stopped at three specific distances from the box, (B) 150 cm, (C) 100 cm, and (D) 60 cm, to read the actual distances. The corresponding polar diagrams are shown in Figure 12c, while Figure 12b shows the relative images acquired by the robot's camera.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Test**} & \multicolumn{2}{c}{**Sonar**} & \multicolumn{2}{c}{**Laser**} \\  & **Mean Value** & **Variance** & **Mean Value** & **Variance** \\ \hline \#1a (50 cm) & 51.98 cm (6.6\({}^{\circ}\)) & 0.02 cm (0.3\({}^{\circ}\)) & 49.9 cm (6.5\({}^{\circ}\)) & 0.9 cm (0.1\({}^{\circ}\)) \\ \#1b (100 cm) & 102.41 cm (2.2\({}^{\circ}\)) & 0.02 cm (0.3\({}^{\circ}\)) & 102.5 cm (2.6\({}^{\circ}\)) & 1.1 cm (0.1\({}^{\circ}\)) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Sonar and laser rangefinder distance measures.  
Figure 11: Test #1: Histograms for 100 laser rangefinder measurements of the distance between robot and wall. (**a**) 50 cm (test #1a) and (**b**) 100 cm (test #1b).  
Scenario #2  
Figure 13 depicts the results of test #2 (scenario #2). In particular, it shows the pictures taken by a camera behind the NAO (Figure 13a) and those taken by the robot's camera (Figure 13b). Figure 13c shows the polar diagram from the data acquired by the rangefinder device. The NAO robot was placed at an initial distance of about 150 cm from an open  
Figure 12: Test #2—scenario #1: (**a**) measurement setup, (**b**) pictures taken by the robot’s camera; (**c**) polar diagram from the data acquired by the rangefinder device at the distances of (A) 200 cm, (B) 150 cm, (C) 100 cm, and (D) 60 cm. The robot is located in the center (at coordinates 0,0) and oriented toward 0\({}^{\circ}\).  
door from which the Pepper robot entered the room. The robot NAO remains steady for the entire test duration, while the Pepper robot is moving. Figure 13c shows the actual detected positions of the Pepper robot (circled in red).  
Figure 13: Test #2—scenario #2: (**a**) pictures taken by a camera located behind the NAO, (**b**) pictures taken by the robot’s camera; (**c**) polar diagram from the data acquired by the rangefinder device. The robot is located in the center of the diagram (coordinates 0,0) and oriented toward 0\({}^{\circ}\). Circled in red is the position of the Pepper robot.  
Scenario #3  
Figure 14 shows the results of test #2 (scenario #3). It shows the pictures that a camera took behind the NAO (Figure 14a) and those taken by the robot's camera (Figure 14b). Figure 14c depicts the polar diagram from the data acquired by the rangefinder device. In this case, the robot was placed in a corridor with stationary obstacles. The NAO robot moves forward in steps of 50 \(\upmu\)m, while the Pepper robot advances toward it to stop beside it. Figure 14c shows the actual detected positions of the Pepper robot (circled in red).  
Figure 14: Test #2—scenario #3: (**a**) pictures taken by a camera located behind the NAO, (**b**) pictures taken by the robot’s camera; (**c**) polar diagram from the data acquired by the rangefinder device. The robot is located in the center of the diagram (coordinates 0,0) and oriented toward 0\({}^{\circ}\). Circled in red is the position of the Pepper robot.