# A Novel Intelligent IoT System for Improving the Safety and Planning of Air Cargo Operations
## 3 System Integration and Testing
### System's Limits Testing
Abrupt power source loss  
To test the system's behavior in the case where one or more cells of a battery pack are removed from it or malfunction, one cell of the battery pack that provided power to the RMC unit was removed 15 times from the battery pack. Meanwhile, the ULD status reports in the HMI application were monitored to witness the percentage drop in the corresponding battery pack. Only one battery cell was removed during this test, to be as consistent as possible regarding the time required for the cell removal. In the case of more than one battery cell being removed, time inconsistencies could occur between the removal of cells, as the battery cells would be removed from the pack by one of the authors. Moreover, even by removing just one battery cell, the test was valid and adequately served its purpose. Since two battery packs provided power to the RMC unit during the tests, the power management unit immediately switched to the second battery pack upon removal of the cell, and, therefore, no power or communication loss occurred. The reporting time interval for the ULD was set to one (1) second, which is its minimum value, and the time between the cell removal and the battery percentage update in the HMI application was measured. Figure 13 presents the results of the test in the form of a chart. From this chart, it is obvious that the average time between a voltage drop in the system due to any reason and the time it is reported to the flight crew is two (2) seconds. The error of the measurement is set to one second since this is the minimum report time interval. Connection loss between ULD and HMI in normal operation  
In this test, the distance between the ULD and the HMI beyond which the connection between the two modules was lost, was measured. For this test, the ULD was set in normal reporting mode and the time interval between consecutive reports was set to one (1) second, which is its minimum value. The HMI was moved away from the ULD, beyond the limits of the test area, while monitoring the reports from the ULD in the HMI, up to the point where the HMI stopped receiving reports. The test was executed 15 times and the distance from the ULD at which the connection with it was lost was recorded. The test results are presented in Figure 14. In this chart, the average distance from the ULD beyond which the connection between the ULD and the HMI was lost was 160 m. Since the distance was measured using a tape measure and since the space between the ULD and the tester was littered with objects often preventing a straight measurement, an error of five (5) meters was applied to each measurement in the chart. Connection re-establishment between ULD and HMI in normal operation  
This test took place after the connection between the HMI and the ULD was lost. It involved moving towards the ULD having the HMI in hand, up to the point at which the connection between the two was re-established, i.e., up to the point at which the RMC  
Figure 13: The time between the removal of a battery cell and its reporting in the HMI application for 15 tests. unit connected to the Wi-Fi network of the HMI. The time interval between the connection establishment and the first report that was received by the HMI was measured for 15 different repetitions of the test and the results are presented in Figure 15. This figure indicates that an average value of four (4) seconds is sufficient time for the return of the system to its normal operation after a connection re-establishment.