## 3 Structured System Design  
### New ROV Structure Design  
The new ROV is mainly composed of a buoyancy body and an electromagnetic adsorption chassis. The buoyancy body is mainly composed of an electronic cabin, an installation frame, and buoyancy material. The electronic cabin mainly plays a protective role for its internal electronic equipment. In this paper, the electronic cabin adopts a cylindrical design; the transparent part of the top is acrylic material, and the rest is made of aluminum alloy material. There are two circles  
Figure 1: Overall system composition. of o-shaped grooves at the bottom of the sealing flange and one o-shaped groove at the top. Installation with a sealing ring can achieve better pressure resistance. The interior is equipped with a three-layer circuit board, multiple sensors, and a single degree of freedom pan-tilt camera that can adjust the pitch angle. The installation framework is the bearing module of the ROV. As shown in Figure 2, the installation frame is made of aluminum alloy, and modules, such as the propeller, the buoyancy material, the electronic cabin, and the electromagnetic adsorption chassis, are fixed onto the aluminum alloy frame. This installation method will make the structure of the ROV more compact and stable. It also gives the whole ROV characteristics of modularization, and the other modules on the ROV can be redesigned according to the relevant requirements. If the size of the original installation hole is retained, the newly designed module can still be installed onto this framework. This design gives the ROV's structure potential for further optimization. The propeller mainly plays a role in providing power to the ROV. The newly designed ROV is equipped with six propellers. The propeller adopts a more flexible arrangement. The thrust has sufficient force in three degrees of freedom in the longitudinal, transverse, and vertical directions so that the ROV can complete movement in these three directions. The thrust component can produce torque on each axis so that it has enough torque on the other three degrees of freedom to complete rolling, pitching, and yawing motions. The thruster used in the ROV designed in this paper has the advantages of small size, light weight, good sealing, large thrust, low power consumption, and high efficiency. The main performance parameters of the propeller are shown in Table 1.  
The ROV uses a buoyancy material with a density of 0.25 g/cm\({}^{3}\). While meeting the basic buoyancy requirements of the ROV underwater, the shape of the buoyancy material \begin{table}
\begin{tabular}{c c} \hline
**Parameter Name** & **Parameter Values** \\ \hline Thrust & 35 N \\ Maximum pressure resistance depth & 150 m \\ Rated voltage & 24 VDC \\ Maximum mooring thrust (rated voltage) & 3.5 Kgf (forward), 2.6 Kgf (reverse) \\ Maximum power (rated voltage) & 190 W \\ \hline \end{tabular}
\end{table} 
Table 1: Underwater thruster performance parameters. Figure 2: ROV installation framework. is designed to be streamlined as much as possible to reduce the resistance of the ROV during operation. As shown in Figure 3, the buoyancy material is composed of four parts, which are fixed on the mounting bracket during installation. The large hole in the middle of the front end of the buoyancy material is used to install the aluminum alloy frame and the electronic cabin. The two symmetrical holes above are used to install the waterproof lighting. The top hole is installed with a monocular camera for underwater visual auxiliary observation. In the past, most magnetic adsorption chassis adopted the track structure, and the permanent magnet was installed on the track to give the ROV the function of climbing the wall. However, this scheme has obvious disadvantages. First, the track may be loosened during long-term operation, affecting its overall adsorption capacity. Secondly, the permanent magnet is installed on the track, and its magnetic force cannot be changed in the operation of the ROV.