Hull Cleaning ROV

Hull Cleaning ROV

1. Structural Introduction

The ship cleaning ROV (as shown in Figure 1) consists of three modules: cleaning module, fuselage module and control module. The cleaning module can be replaced according to different requirements in the later stage. When working against the wall, the cleaning ROV prototype uses the 4 thrusters on the back of the fuselage to provide power to make it close to the ship wall, and uses the 4 thrusters on the side (Whale 1214) to provide power to control its movement direction. The cleaning module is located in the middle of the ROV's abdomen. The area after the ROV walks is the section that has been cleaned by the cleaning device. A camera and two lighting lamps are installed at the front and back of the ROV to collect image information.

The cleaning module includes a cleaning brush head (including a cleaning brush and a sealed torque motor) and a suspension mechanism. This machine uses a torque motor to provide power, and the torque motor is sealed to ensure that auxiliary devices such as hydraulic pumps are not required when the power is sufficient. The suspension mechanism can automatically adjust the cleaning plane of the cleaning brush, so that the ROV can also be close to the ship wall when encountering a curved ship wall, and can achieve good cleaning results. The cleaning module has good interchangeability and can be replaced according to different working conditions and customer needs.

The control module includes a control circuit, a motor driver and sensors (including an electronic compass, a posture sensor, a water entry sensor and a pressure sensor). The control module is connected to other components through a watertight cable and a watertight plug to control the movement of the ROV. The electronic compass displays the angle of the ROV's movement in real time, the posture sensor monitors the ROV's posture in real time, and the pressure sensor displays the water depth of the ROV's location in real time. The three are essential sensors for path planning, which can improve the stability of the ROV's movement and the degree of intelligence of the control. The water entry sensor monitors whether there is water leakage in the control module in real time, which improves the safety of the ROV. The driver controls the operation of the propeller to complete various actions of the ROV.

The fuselage module includes a frame, a lighting device, a camera and a propeller. The lighting device is installed at the front and rear of the frame to provide visual conditions in the water. The camera is installed at the front and rear of the frame. The camera is equipped with a pan-tilt head that can be used for steering, which can control the direction of the two degrees of freedom up, down, left and right, and conduct a comprehensive observation of the cleaning area. The ROV contains a total of eight high-thrust thrusters, all of which are oil-sealed thrusters with good reliability and high transmission efficiency. They are used to control the ROV's diving, floating, forward and backward, turning and rolling.

2. Control Introduction

The control system architecture of the cleaning ROV consists of 4 main control nodes (Figure 1), using a distributed control system based on the CAN bus. The CAN bus is a multi-master serial communication bus with the advantages of good real-time performance, strong self-checking and error correction mechanism, and strong scalability.

Figure 1 Composition of the control system architecture

The overall control system consists of 4 nodes, and the functions are as follows:

1) Main control node: embedded with embedded real-time operating system uC/OS-II, mainly responsible for the realization of various functions of ROV, including thruster start-up and speed adjustment, cleaning disk start-up and speed adjustment, light opening and closing, and water leakage detection, distance detection, depth detection, and posture detection of each water leakage sensor.

2) Control box node: used to control the operation of the entire cleaning device and the computer's online programming, camera display, and operation status display.

3) Camera1, 2 nodes: used to control the camera opening and pan/tilt rotation, including sensor leakage detection.

3. Introduction to the workflow

The flowchart in Figure 2 shows the entire operation process of the cleaning ROV when working underwater. One cycle is a period, which starts when the control box starts to power on. The ROV's underwater working picture is displayed on the control box display panel through the camera to assist the operator in controlling the underwater ROV.

Figure 2 Flowchart

4. Introduction of Control Box

The control box (Figure 3) is mainly used to control the underwater ROV. The two switches on the control box panel are used to power on the ROV and the host switch. The air switch is used to protect the circuit. It contains a radiator. The power socket and signal line socket on the left are covered with a cover. The operation of the control box is realized by a specially developed control handle. The display screen can display the ROV's posture, heading and real-time images collected by the camera, and can take photos and record videos with one click. The panel contains indicator lights for displaying the working status of the ROV, the working status of the host and the working status of the power supply, and real-time detection of the control box and the operated equipment. There are three USB serial ports and one HDMI video port on the control box panel, which are used to read files, insert wireless devices, and expand the display screen.

Figure 3 Actual picture of the control box

5. Introduction to the propeller

Whale 1214 is a miniaturized DC brushless deep-sea propeller. With high-performance DC motors, high-efficiency propellers and ducts, the stability and hydrodynamic performance of this propeller are excellent, and it can be widely used in small ROVs or AUVs.

Whale 1214 uses an oil seal connection method, and has built-in compensators and drivers, which improves the mechanical transmission efficiency, avoids the problem of magnetic vortex consumption generated in magnetic coupling, and greatly improves the overall efficiency.

6.General Parameters

Pcture of real product