Beginning in the 1990s, underwater robots that can navigate autonomously without needing to be connected to a ship by a cable began to emerge for purposes of assisting in oceanographic research and oil and gas exploration on the ocean floor. Outfitted with sensors for underwater navigation and GPS for surface deployment, in addition to motors and radio communications equipment, they can be programmed to go to a predetermined location and come back. These robots, known as autonomous underwater vehicles (AUVs), are made by companies in several countries, including the United States, Norway, Japan and France. Brazil has only recently engaged in research and development in this field, and therefore has yet to produce an underwater robot that can be commercially manufactured. But there are at least three prototypes currently in the testing stage.
The most recent such prototype is intended for oil and gas exploration, the area offering the most technological opportunities and operational applications for AUV robots in Brazil. BG Brasil, a subsidiary of the Shell Group, has developed an AUV called FlatFish in partnership with the National Industrial Training Service – Center for Integrated Manufacturing and Technology (Senai-CIMATEC) in Salvador, Bahia, with support from the Brazilian Corporation for Industrial Research and Innovation (Embrapii) and the National Agency of Petroleum, Natural Gas and Biofuels (ANP). The robot will be used for high-resolution three-dimensional (3D) visual inspection of underwater oil and gas exploration structures, such as piping, oil pipelines, ship hulls and platforms.
“It’s the first prototype of this kind produced in Brazil,” notes Rosane Zagatti, the company’s manager of underwater technology. “The autonomous underwater vehicle will contribute to deepwater exploration, reducing operating costs by 30% to 50%, improving safety and reducing environmental impact.” She explains that underwater inspections in the oil and gas industry today are performed by remotely operated vehicles (ROVs), which require a support vessel. The ROV is launched into the ocean using cables from the ship, from which it is operated remotely by two people, a pilot and a copilot. Depending on where the inspection takes place, the costs of an ROV can run as high as $200,000 per day. “FlatFish needs no support vessel, which greatly reduces costs,” Zagatti says. According to Marcos Reis, project coordinator for CIMATEC, the vehicle poses major technological challenges, but the advantages to be had from developing it are numerous. “The robot reduces the risks to the integrity of ships, platforms, piping and other underwater structures because it increases inspection frequency and yields better results in terms of quality control,” she says. “It also reduces safety risks to personnel, and eliminates the need for divers to perform hazardous tasks in support operations.”
The role of FlatFish is to transmit real-time information in the form of images and data. To perform these tasks, the robot is equipped with sensors, propellers, onboard computers and computational intelligence, with identification and decision-making systems if needed. “It was developed to provide very stable navigation and the ability to come very close to the equipment being inspected, or even to touch it,” Zagatti explains. “Our vehicle is capable of residing on the ocean floor, in a kind of garage. Once it has been programmed, it can leave the garage to perform its mission autonomously, collecting and sending the inspection data to an operator.” The equipment is propelled by motors powered by lithium batteries that can be recharged on the ocean floor in the underwater garage. FlatFish’s autonomy is 35 to 60 kilometers (km) a 60 km, depending on the mission and maritime currents. Every six months the AUV needs to be brought to dry land for maintenance.
The prototype was tested and can operate at a depth of 300 meters. According to Reis, the CIMATEC team is working to make FlatFish operational at a depth of up to 3,000 meters within four or five years, which would make it useful for pre-salt exploration. To date, R$30 million has been invested in the project, an expenditure shared equally by BG Brasil, Embrapii and Senai, the latter contributing professional staff time, equipment and infrastructure. The project also receives technical support from the German Research Center for Artificial Intelligence (DFKI). BG Brasil has yet to sign partnership agreements for future production of underwater robots.
Another present-day aspect of the use of underwater robots is ocean exploration. Naval engineer Ettore Apollonius de Barros, a professor at the Polytechnic School of the University of Sao Paulo (Poli-USP), began developing an AUV called Pirajuba (yellow fish, in the Tupi language) in 2005, with FAPESP funding. The goal was to study the hydrodynamics of a torpedo-shaped autonomous underwater vehicle, which he did over a nine-year period at the Unmanned Vehicles Laboratory. Development of Pirajuba continued with research headed by biologist Rubens Lopes, a professor and head of the Plankton Systems Laboratory (Laps) at USP’s Oceanographic Institute (IO-USP). He studies the distribution of plankton (microorganisms consumed by several fish species and other marine animals) along parts of the Brazilian coastline. “In February 2014, we initiated a project to modify our Pirajuba AUV and giving it a practical application,” Barros says. “The objective now is to obtain data on plankton.”
The traditional way to collect data in this kind of study is to launch a probe with special sensors from a ship, at several points in the area to be researched. “With an AUV, all you need to do is program the route and release the machine into the water,” says Barros. The unmanned mini submarine has seven onboard microprocessors that cross-communicate, as well as navigation sensors and special sensors for research on microorganisms, such as indicators of conductivity, water temperature and depth. “The vehicle also includes optical sensors that emit ultraviolet light to measure particles suspended in the water and the presence of chlorophyll and cyanobacteria.” Lithium batteries provide autonomy of approximately 10 hours. Since 2014, the vehicle has been evaluated in the ocean around Anchieta Island near Ubatuba on the coast north of Sao Paulo State. In 2015, the vehicle collected data for characterization of plankton in the region. Barros notes that his laboratory is open to cooperation with companies for technology transfer and possible equipment production.
Clinging to the hull
At the Federal University of the ABC (UFABC), Juan Pablo Julca Avila, a mechanical engineer and professor who teaches the Aerospace Engineering course, has received FAPESP support to develop a different underwater robot, a hybrid remotely operated vehicle (HROV). “It is semiautonomous and has two operating modes, free-flight and crawl”, Avila explains. “When launched into the sea, the vehicle goes into autonomous mode, using propellers to steer towards and approach the submerged structure to be inspected. The HROV docks automatically and then goes into crawl mode, moving on tracks as it is remotely steered by an operator.”
The vehicle consists of a frame made of polypropylene plates with six screw propellers for free-flight movement in five directions: forward, down, pitch, roll and yaw, and two motorized rubber tracks that enable it to move around on an underwater surface. A set of sensors measures the vehicle’s movements on pre-established trajectories. “The prototype has now gone through several hydrodynamic and control tests in a test tank,” Avila says. “We’re in the second stage of development, in which the navigation and crawl control system is being implemented. After that, we’ll test it in the ocean.”
The vehicle’s movements are controlled by motors powered by electricity supplied through a ship-based umbilical cable that also provides control and communication. The HROV will be used as an experimental platform for conducting research on dynamics and control for this class of vehicles in marine environments and for analyzing the thickness of underwater structures. As it approaches a ship, for example, the robot positions itself so its base is in contact with the hull. At that point, the motorized tracks are activated for movement. Contact is maintained by mechanical force generated by the propellers. When they rotate in one direction, the robot “clings” to the hull; when they rotate in the other direction, it lets go. According to Avila, this class of equipment with tracked-based docking is now being sold abroad by one company. As with the other projects, Avila does not yet have any prospects for production of his robot. “We are open to interested parties, be they students or researchers qualified to work on developing the equipment,” he notes. “We’re currently looking for partnerships with robotics companies so we can complete the development of the acoustic positioning and thickness calibration systems.”
Underwater robots come in many forms, as demonstrated by the three Brazilian projects. The most advanced and striking of these is an American project that conducted its first dive in April 2016 in the Mediterranean. OceanOne, developed by a research group at Stanford University in the United States, is a humanoid robotic diver. It has the approximate size and appearance of a human and is equipped with artificial intelligence supplied by software that identifies patterns and makes associations. The head contains cameras with stereoscopic vision in place of eyes, two articulated arms, and hands with fingers replete with sensors that give tactile responses. Instead of legs, it has a “tail” that houses batteries, computers and eight multidirectional propellers. The robot is operated remotely using a joystick.
OceanOne is a virtual diver—a kind of avatar. When it grasps an object, for example, the operator can feel its weight and force. The idea to develop it arose when researchers at King Abdullah University of Science & Technology (Kaust) in Saudi Arabia needed to study and monitor coral reefs in the Red Sea. The robot’s first official dive was a visit to the wreck of the La Luna, a galleon from the fleet of French King Louis XIV that sank in 1664, 32 kilometers off the coast in 100 meters of water. OceanOne showed images of the submerged ship and brought a vase up to the surface.
1. Thin layer detection by an autonomous underwater vehicle in a coastal ecosystem: the ECOAUV Project (nº 2013/16669-7); Grant Mechanism Regular Research Grant; Principal Investigator Ettore Apolonio de Barros (USP); Investment R$198,851.41 and US$50,583.98.
2. Development of low-cost autonomous underwater vehicles. Part A: Maneuverability and propulsion system (nº 2005/55847-1); Grant Mechanism Regular Research Grant; Principal Investigator Ettore Apolonio de Barros (Poli-USP); Investment R$71,726.87.
3. Development of a robotic underwater vehicle for ship-hull inspection (nº 2011/51955-5); Grant Mechanism Regular Research Grant; Principal Investigator Juan Pablo Julca Avila (UFABC); Investment R$288,274.93.