## 3 Structured System Design
### Portable Ground Control Box Structure's Design  
In order to realize control of the new ROV, a portable ground control box integrating control and monitoring is designed. It mainly controls the ROV's motion through the rocker, knob, and button on the control panel, and it obtains the ROV's operation information in real time through the visual window of the host computer software. The design of the control box can be divided into three parts, which are the design of the control panel, the design of the hardware installation in the lower box, and the installation design of the upper box's cover display. The control panel integrates all rockers, knobs, buttons, etc. that can directly control the ROV. As shown in Figure 6, nine metal waterproof buttons are installed on it for the selection of ROV control modes, such as forward and backward, automatic depth determination, and automatic bow determination mode switching. Six simulation knobs are used to adjust the target depth and angle when the ROV is fixed in depth and heading. Six green LED lights mainly play a role in indicating the rocker switch. Six 2-gear, 2-leg button switches are mainly used to control the opening and closing of the ROV's lights. Of the two power switches, one is used to control the on-off mode of the overall power supply, and the other is used to control the on-off mode of the ROV's power supply. In the power supply circuit of the ROV, the maximum fuse current of the fuse is 10 A, which effectively ensures the safety of the ROV's power supply circuit. The USB 3.0 interface and the network port can be directly connected to the embedded computer without opening the control panel for data transmission and software updates. Three LED digital tube display screens are used for current and voltage display. The embedded metal keyboard is used as the input of the computer in the control box. Three analog rockers are used to control the underwater motion of the ROV. Two digital joysticks are used for control of the ROV's chassis motor. Two handles are installed on both sides of the control panel, which facilitates the installation and disassembly of the control panel. The parts on the ROV's control panel are designed with redundancy. When the ROV's function is expanded, the connection between the control hardware on the panel and the ROV's expansion function can be established by updating the host computer software to realize control of the ROV's expansion function. The lower box is mainly used as the installation space for hardware equipment, such as the control panel, the embedded computer, the switching power supply, the power carrier module, the DC contactor, and the lithium battery. Firstly, the fixed frame is  
Figure 6: Diagram of the control panel’s structure. 1—LED button switch; 2—analog knob; 3—LED indicator; 4—analog rocker; 5—carrying handle; 6—embedded metal keyboard; 7—twist switch; 8—digital rocker; 9—digital tube display; 10—USB expansion port; 11—fuse; 12—power master switch; 13—ROV power switch; 14—network port; 15—7:inch display adjustment button; 16—7:inch display; 17—display fixing cover. designed and installed inside of the box, and the guide rail is installed on the frame so that other equipment can be fixed on the frame through the guide rail buckle. The embedded computer has the basic functions of all computers, but it has a smaller body and a lighter weight than a desktop computer or a laptop, so it is more conducive to assembly in the control box. Two rail-type switching power supplies are used for converting the introduced alternating current into the voltage or current required in the control box. One end of the power carrier module is connected to the embedded computer through the network port, and the other end is connected to the ROV's electronic cabin through the cable to realize real-time, high-speed communication between the upper computer and the lower computer.