In recent years, with the rapid development of computer technology, the application of artificial intelligence in the field of ship and ocean engineering has become a hot topic nowadays. Highly intelligent equipment such as unmanned ships, intelligent underwater robots, and unmanned aircrafts are gradually being used in various fields of ocean engineering. Many domestic and foreign shipping companies, marine industry owners, classification societies and competent authorities of many countries are exploring brand-new ship operation and inspection models. In order to adapt to the development trend of smart ships, China Classification Society (CCS) has established a smart inspection project team dedicated to the development of modern high-tech inspection technologies. After preliminary investigation and exploration, we found that using drones to perform inspections in the shipping and offshore fields has the following three advantages: One is to reduce operating costs. Take a 330-meter-long 300,000-ton super large oil tanker as an example. To complete a whole ship structural inspection, for the shipowner, at least one million in scaffolding costs and about 2 weeks of scaffolding must be paid Construction time. If the drone is used to perform this work, not only can the inspection of the ship's structure be completed within a few days, but it can also save the shipowner a lot of financial costs. The second is to improve inspection efficiency and ensure inspection quality. Also take a 300,000-ton super large oil tanker as an example. The ship is 30 meters deep and has 17 cargo oil tanks and 10 ballast tanks. Just a brief walk through these cabins will result in a climbing height of about 800. M, it is almost equivalent to climbing the Oriental Pearl Tower twice, let alone a detailed close inspection of each area of ​​each cabin. The actual inspection work may only account for 30 to 40% of the total workload, and a lot of energy is spent on manual labor. However, if we use drones to perform inspections, we can greatly reduce the labor intensity of the inspectors, focus more attention on the inspection work, and improve the quality of the inspection, while the entire inspection process can be completed by the drone. Recording it locally can allow people who are not on site to intuitively understand the actual situation on site and achieve remote technical guidance. The third is to ensure the safety of personnel and reduce the risk of accidents. UAVs can be used to conduct detailed inspections of key structures that are difficult to access in a convenient way, thereby reducing the risk of high-altitude operations and ensuring personnel safety. It can be seen that the application of drone technology to field inspection is very valuable. In October 2016, CCS first tried to use drones to conduct close-up inspections of ships on site. It is found that ordinary drones are difficult to adapt to the complex environment on board, and can hardly achieve stable flight, let alone image data collection. The main reason is that the existing UAVs are suitable for flying in an open environment. They use GPS signals, electronic compasses and visual sensors to locate and control their flight attitude. However, once you enter a closed space such as a ship’s cargo hold, the GPS signal will be lost, and the electronic compass will be interfered by peripheral equipment and steel structures. The dark environment and a single coating color also prevent the visual sensor from working properly. At the same time, since the drone is always in a state of high-frequency vibration during the flight, it is difficult to take a clear photo or video in a relatively dimly lit environment. Therefore, in response to the problems encountered in the first flight test, CCS developed a brand-new UAV navigation system and control system, and optimized the overall design of the power supply system and lighting system. After many on-site test flights at shipyards and docks, the drone prototype developed by CCS can basically achieve stable flight and image data collection in complex environments. It is worth mentioning here that being able to take a clear picture of the hull structure or a video on the ship with a drone is a landmark for CCS. This means that CCS drones can already undertake routine visual inspections. By viewing the collected image information, they can judge whether there are defects in the hull structure, whether the coating in the cabin is in good condition, and it can be conveniently observed at close range. Some structures or areas that are usually inaccessible. We can also use image analysis and comparison techniques to directly obtain the proportion of coating damage and the specific size of structural damage. In November 2017, based on previous research and development work and flight test experience, CCS compiled the "UAV Inspection Application Guidelines", which formulated technical standards for drones, technical standards for data acquisition systems, and on-site inspection and application of drones. The requirements and precautions of the company provide guidance. CCS comprehensively considers the current statutory requirements of the competent authority, classification society regulations, and the acceptance of the safe operation and management system of ships and offshore facilities. It takes the existing drone technology and data collection and analysis system technology as a reference, and combines it with the on-site inspection process. According to the actual situation of the UAV, the guidelines are compiled from three aspects: the effectiveness, operability and safety of the UAV inspection. The guidelines are mainly composed of four aspects: UAV technical standards, data information collection, and ship and offshore field inspection applications, from the safety performance of UAVs, the qualification requirements of inspectors, data information collection and storage, on-site inspection conditions, and pre-inspection More detailed guidance and suggestions were given in various aspects such as preparation and safety matters. While CCS is developing drone inspection technology, it is also exploring the integration of other new inspection technologies with drone technology to establish a systematic intelligent inspection platform. In June 2017, CCS tried to use VR virtual reality technology on a ship for the first time. This technology can provide ship owners with a more intuitive ship management platform. At the same time, the project team also completed the prototype design of the binocular vision navigation and positioning system, which can recognize the structural features of the ship in a low-light environment and realize autonomous navigation and positioning functions. In addition, CCS is also trying to combine these two technologies with UAV technology, and finally it can realize remote autonomous flight of UAVs and display the collected real ship information through the VR virtual technology platform. Next, the CCS project team will use the existing drone inspection technology as the basic platform to develop a multi-functional data collection module, and build an artificial neural network model based on the needs of the whole ship inspection, which can be used for autonomous inspection during the entire operation of the ship. The intelligent decision-making system with independent judgment will finally integrate the intelligent inspection platform into the centralized platform of CCS intelligent ships, thus realizing the intelligent operation of ships.
EPON (Ethernet Passive Optical Network), as the name suggests, is a PON technology based on Ethernet. It adopts point-to-multipoint structure, passive optical fiber transmission, and provides multiple services on Ethernet. EPON technology is standardized by the IEEE802.3 EFM working group. In June 2004, the IEEE802.3EFM working group released the EPON standard-IEEE802.3ah (incorporated into the IEEE802.3-2005 standard in 2005). In this standard, the Ethernet and PON technologies are combined, the PON technology is used in the physical layer, the Ethernet protocol is used in the data link layer, and the PON topology is used to realize Ethernet access. Therefore, it combines the advantages of PON technology and Ethernet technology: low cost, high bandwidth, strong scalability, compatibility with existing Ethernet, and convenient management.
ONU (Optical Network Unit) optical network unit, ONU is divided into active optical network unit and passive optical network unit. Generally, devices equipped with network monitoring including optical receivers, upstream optical transmitters, and multiple bridge amplifiers are called optical nodes. The PON uses a single optical fiber to connect to the OLT, and then the OLT connects to the ONU. ONU provides services such as data, IPTV (i.e. interactive network television), and voice (using IAD, i.e. Integrated Access Device), truly realizing "triple-play" applications.
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