Fig. 2. Comparison of block diagrams between the previous by Cho et al. (2016) (a) and the enhanced version presented in this study (b) of physical modeling systems. The main features of new system are as follows: All processes are performed at 5 Hz refresh rates rather than 3 Hz. A camera is equipped to record the situation of experimental conditions. Two detection lines are used to determine the direction of the moving target object. The number of input channel of data acquisition unit increases. In the data processing and control unit, two background mode and test mode are available to retest the stored data.
Fig. 1. Conceptual installation of the underwater object detection method (Cho et al., 2016). Two detection lines are located on the seabed and each detection line consists of two current electrodes and a number of potential electrodes. C1-C4 represent current electrodes.
Fig. 3. Photograph of the enhanced version of physical modeling system. The system consists of data processing and control unit, camera, power supply, target object, two detection lines, and data acquisition unit.
Fig. 4. The screen configuration of the enhanced physical modeling system. Panel A: video image is displayed to understand the experimental conditions. Panel B: control and monitoring panel is placed. Panel C and D: 2D and 3D graphs of detection line 2 and 1, respectively. In 2D graph, real-time data are displayed and in 3D graph, stacked real-time data are displayed.
Fig. 5. Flowchart of the video monitoring process.
Fig. 6. Flowchart of the data processing routine.
Fig. 7. Flowchart of the mode 3 (background data generation algorithm).
Fig. 8. Plan and sectional views of the water tank experiment. Eachdetection line consists of two current electrodes at both ends and24 potential electrodes with 1-cm spacing. The stimulation currentlevel is set to 6mA and electric field data for 23 consecutive pairsof adjacent potential electrodes are acquired for each detection line.The target object is moving along the pathway between potentialelectrodes 6 and 7.
Fig. 9. Results of the water tank experiments using mode 1 (without background data) at the detection line 1 (a) and the detection line 2(b). In the 3D graphs, the x-axis represents the channel number, the y-axis represents the time in seconds, and the z-axis represents thedistortion level of electric field.
Fig. 10. Results of the water tank experiments using mode 2 (background data update algorithm) at the detection line 1 (a) and the detection line 2 (b).
Fig. 11. Results of the water tank experiments using mode 3 (background data generation algorithm applied) at the detection line 1 (a) and the detection line 2 (b).
Fig. 12. Console displays at the moment when the target object is passing the right side of water tank (a), the right above the detection line 1 (b), between detection line 1 and 2 (c), the right above the detection line 2 (d), respectively. Note that drastic changes of electric field distortion are observed according to the position of the target object.
Table 1. Summary of the previous system by Cho et al. (2016) and the enhanced system.
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