**2. Intelligent rescue system**

In this section, we introduce the hardware components of an AIRS and its working principles. The hardware of AIRS contains the sensing module and a double-trigger inflator. The 11-DOF sensing module combines the 9-DOF inertial sensor, barometric pressure sensor, and temperature sensor to collect the motion data and the depth of the underwater vehicle. The inflator is used with gas cylinders as the double trigger mechanism, which can be triggered not only by electricity but also by water damage when the waterproof cabin is severely broken. Furthermore, we used the commercial software LabVIEW™ to analyze the relation between buoyancy force and inflator device in water, to confirm the inflator specifications (**Figure 1**).

**Figure 1.** The structure of the intelligent rescue system.
