Real-Time Human Cognition of Nearby Vibrations Using Augmented Reality 143 0 2 4 6 8 10 12 Trial number 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Time in (s) Delay on Local Network vs Mobile Hotspot Local Network Mobile Hotspot Fig. 5 Delay on local network vs. mobile hotspot 8. The three colored lines are plotted on the graph in the user’s view. 9. View Stop and Client Stop are selected to close the graph and shut down the client’s connection to the server. 10. The visual feedback from the graph is recorded in the HoloLens as a video to validate the results and analyze the delay. 11. The time-delay data and Arduino data are plotted in MATLAB. The time delay in the program was investigated using video analysis. By counting the frames between the initial sensor acceleration and the recorded response, the time delay can be approximated. With the known value of the video framerate in FPS, the time delay of the application can be calculated using the following formula. (Frame1 −Frame0) ∗ 1 VideoFPS = TimeDelay (1) 3 Test Results and Analyses The test was run with a total of three trials with four excitations for each WiFi connection. Between each trial the sever-client connection was shut down and the AR application was restarted. Therefore, the graph displayed a total of 12 positive peaks which could be analyzed to determine the time delay. Frame0 was designated as the time of initial acceleration upwards by the sensor. Thus, Frame1 designates the response plotted on the graph in the user’s view. The difference in frames was recorded and the time delay was calculated with Eq. (1). The results were plotted in MATLAB for comparison in Fig. 5 and the individual values are reported in Table 1. The results of the experiment validate the AR application for use in the field. As proven clearly in the graph, the time delay on the local network was inconsistent and slow. The time delay in the graph response on the mobile WiFi network is consistently under 0.5 s, proving the reliability of the application for work in the field. The average time delay in the graph on the mobile network is much closer to real time at 0.263 s versus 0.6875 s on the local network. Additionally, the delay on the local network peaks at one full second while the delay peaks at less than 0.5 s on the mobile network.
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