### Experimental Results
#### 4.2.2 Experimental Results for the Obstacle Detection Component Evaluation  
Once the performance of the VLC component was confirmed, the next phase was focused on the obstacle detection component. Before moving forward to the evaluation in a complex situation, the first tests aimed to determine if the system is able to safely localize potential dangerous objects that could obstruct the path of a blind user. As mentioned in previous sections, these tests aimed to determine the system's efficacy in preventing the user to bump into other persons, to hit objects located in the path, and, most importantly, \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{\begin{tabular}{c} **Modulation/Coding Technique** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Data Rate** \\ **[kb/s]** \\ \end{tabular} } & \multicolumn{2}{c}{**VLC Transmitter-VLC Receiver**} & \multirow{2}{*}{\
\begin{tabular}{c} **Compatible with Light** \\ **[m]** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **BER at a 95\%** \\ **Confidence Level** \\ \end{tabular} } \\ \cline{3-3} \cline{5-6}  & & & & & **Immediate Angle** \\ \hline Manchester & 250 & 0-340 & 0-53\({}^{*}\) & Not in the current setup & \textless{}10\({}^{-7}\)\({}^{*}\) \\ \hline VPPM & 100 & 0-340 & 0-53\({}^{*}\) & 10-90\% & \textless{}10\({}^{-7}\)\({}^{*}\) \\ \cline{2-6}  & 10 & 0-340 & 0-53\({}^{*}\) & 1-9\%\({}^{*}\)91-99\% & \textless{}10\({}^{-6}\)\({}^{**}\) \\ \hline \hline \end{tabular}  
* Based on 30 million received bits; ** Based on 3 million received bits.  
\end{table} 
Table 2: Summary of the prototype VLC experimental results. Figure 5: Illustration of signal processing at the VLC receiver level: Channel 1 (yellow) represents the output of the optical receiver; Channel 2 (cyan) represents the signal after filtering and amplification; Channel 4 (green) shows the digital signal that is used by the microcontroller to extract the binary data. The figure also depicts the use of the VPPM modulation in a 30% duty cycle example, the light dimming principles, and provides a comparison with the traditional Manchester coding. to localize objects that cannot be located by a blind stick, referring here to objects that are located at the chest and/or head level. The situations envisioned are illustrated in Figure 6, whereas the summary of the experimental results is provided in Table 3.  
The experimental findings also demonstrate the prototype's efficacy in assisting visually impaired individuals with key aspects of navigation and spatial awareness. Specifically, the prototype aids users in maintaining a straight trajectory, detecting the presence of individuals or obstacles in their path, signaling the proximity of a door/wall, and enhancing their overall environmental perception. Thus, as illustrated in Figure 7, users exhibit a notably straighter trajectory when utilizing the prototype. This improved directional control, coupled with the increased confidence imparted by the system, results in a significant reduction in travel times. Consequently, users are less apprehensive about encountering obstacles, leading to a noteworthy reduction in the average travel time--from 53.6 s to 39.3 s. It is worth noting that further enhancements are anticipated as users become more accustomed to the system's operation and as the prototype is further calibrated on users' specific requirements, promising even greater improvements in their navigation experience. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Test Objective** & **Number of Trials** & **Successful Detections** \\ \hline Human in the pathway detection & 100 & 100 \\ Chest and head obstacle detection 1 & 100 & 100 \\ Dispenser in the pathway detection 2 & 100 & 100 \\ \hline \hline \end{tabular} \({}^{\dagger}\) Testing setup is illustrated in Figure 6a. 2 Testing setup is illustrated in Figure 6b.  
\end{table} 
Table 3: Summary of the obstacle detection tests.