# A Novel Intelligent IoT System for Improving the Safety and Planning of Air Cargo Operations
## 3 System Integration and Testing  
### Laboratory Testing  
After the initial development phase, the system underwent several laboratory tests. In what follows, a summary of the results of laboratory evaluation tests performed on the hardware components and software services is presented. Figure 8 shows the RMC hardware fully connected for testing. During these tests, the system was supplied by an external power supply, which provided 24 V/0.75 A constantly. The components selected, including the sensors and the electronic boards, were the same as those that were eventually installed in the container during the system's field testing. Regarding the hardware of the system, the main functionality tests that were performed during the laboratory testing included continuity and functionality testing of each electronic board. Each test described in the following was performed at least five (5) times, according to standard laboratory testing practice. The system was also tested while powered by batteries. When tested, the battery switching and monitoring units were configured to sufficiently supply the system. The continuity and functionality tests of the power supply and the mainboard showed that there were no unwanted short circuits on the PCBs or crosstalk between neighboring signal tracks. The power supply board and the power management unit were able to provide adequate power to the mainboard and the sensors. The power management unit's redundancy functionalities were also tested by connecting and disconnecting several power cells during the system's operation. The tests showed that the power management unit seamlessly transitioned between the two battery packs, without interrupting the system's functionality. The minimum voltage level for the operation of the system was also tested  
Figure 8: The RMC system set up for laboratory testing. Figure 7: Three-dimensional model and dimensions (**left**); assembly process photos of box 1 (**middle** and **right**). during this test phase, by powering the system via a bench power supply in which the output voltage was gradually lowered. The system worked properly with a minimum power supply voltage of 10 V.  
Every sensor that was going to be installed on the ULD was also tested to be read successfully by the RMC mainboard, using an oscilloscope, tracing its signal along the analog tracks of the mainboard, and making sure that it ended up properly in the corresponding microcontroller input. To test the contact sensors, each switch was pushed and its output change was measured on the mainboard. The position/magnetic sensors were tested by placing either a magnet or a ferromagnetic object near them. The smoke detector that communicates with the microcontroller via CAN bus was also tested, by placing two oscilloscope probes on the CAN bus signal lines and monitoring the CAN high and CAN low signals during the system's normal operation. The two signals arrived simultaneously in the microcontroller's input, without any phase shift or loss of power. The various functionalities of the embedded software of the system were tested using a serial monitor. The first group of functionality tests were to do with the RMC's initialization and communication with both its sensors and the HMI. The device successfully initialized all of its functionalities and established its communication with the HMI during every test performed. Several tests regarding the embedded software's ability to re-establish the RMC's communication with the HMI once the connection between them had been temporarily lost were also performed by detaching the antenna of the RMC board and re-attaching it after a while. The communication between the devices was successfully re-established every time. The second group of tests involved acquiring data from every sensor of the ULD. During this testing phase, every sensor was excited and the effect of this excitation was monitored via the reports that the embedded software sent to the RMC's serial output. Figure 9 shows one of these reports.