Robot buoy to track oil spills
Yesterday, Japan Today reported about a prototype of robotic buoy developed at Osaka University to fight sea pollution in the event of an environmental disaster caused by an oil spill. The current prototype, dubbed SOTAB (short for 'Spilled Oil Tracking Autonomous Buoy') is a 110-kilogram GPS-equipped robot. The cylindrical buoy has a length of 2.7 meters and a diameter of 27 centimeters. The lead researcher admits that these robots will not be really ready before at least three years. But he would like to have these buoys installed on all oil tankers to be automatically dropped in the sea in case of an accident. But read more...
You can see on the left a photo of the SOTAB 1 robotic buoy. There are several pictures of this prototype 'floating' on the Web. This one comes from this page at TreeHugger.
This robot buoy has been designed by Naomi Kato, professor of submersible robotic engineering at the Department of Naval Architecture at Osaka University, Japan, with the members of his lab. The 'Katolab' "is conducting education and research on underwater robotics, biomechanics on aquatic animals and its application to engineering, computational hydrodynamics of viscous flow fields." You'll find more details about this robotic buoy by looking at this specific research project, Development of Spilled Oil Autonomously Chasing Buoy System.
According to Japan Today, here is how Kato justifies the usage of such buoys. "'The development of an oil field in Russia's Sakhalin and Chinese economic expansion will likely lead to increased tanker traffic in Japanese coastal waters.' The buoy is intended to be deposited along the edge of an oil slick in the sea at the time of an accident. A sensor to analyze the stickiness of liquids detects heavy oil, which is more glutinous than sea water."
Now, let's look at how this robot works. "Once the buoy senses it is out of an area of heavy oil, it automatically submerges to a depth of about 10 meters and four extremely sensitive cameras explore the surrounding area. The cameras look out for the black shadow cast by oil and the buoy resurfaces in the oil slick, steering using four fins. It repeats this process to keep track of the oil. It is able to keep searching for oil at night by turning on its lights. The float utilizes the global positioning system to ascertain its position, which it transmits by radio together with data on the speed of the current, water temperature, wind direction and wind velocity."
Here are additional details about SOTAB 1 provided by Pink Tentacle, a site focused on technology advances in Japan, in a February 2008 post, Robot buoy hunts down spilled oil. "It has imaging sensors that can spot floating globs of oil from a distance, as well as viscosity sensors that detect the presence of oil, and it includes a wind monitor, depth meter and water thermometer. When multiple robots are dropped into the water at regular intervals around an oil spill, they can provide a wealth of valuable data to cleanup crews and allow them to monitor a wide area."
But how exactly SOTAB is working? "Once in the water, SOTAB 1 begins searching for oil by reducing its buoyancy and diving underwater, where it trains its imaging sensors back up at the surface. When the robot sees something that looks like oil, it readjusts its buoyancy and floats back to the surface, using 4 fins to steer toward the oil slick. It then takes water samples and determines how much oil is present. As SOTAB 1 follows the oil around, it sends back real-time data about its location and the surrounding meteorological and oceanographic conditions."
Kato hopes this robot buoy will become commercially available in 2 to 3 years. "'We want to get the weight under 30 kilograms and extend the battery life to about 3 to 4 weeks,' says Kato, who began working on the robot in 2006. 'We would one day like to see these robots become standard equipment on oil tankers.'"
Here is a last quote from the Japan Today article about the future. Kato "said the ideal system would be to oblige tankers to have buoys on board and to automatically drop them into the sea when accidents occur. 'A large-sized tanker would be able to respond quickly to the accident should it have dozens of buoys,' he said. Kato is considering using solar batteries and tidal power xgeneration since the cells the prototype currently uses last only several hours, far from the goal of three weeks he is aiming for. He said the size of batteries should be made smaller to save power, improve motion performance and cut down on cost."
For more information about Kato's research, here are three abstracts of technical papers worth reading.
- Median and Paired Fin Controllers for Biomimetic Marine Vehicles, published by Applied Mechanics Reviews (Volume 58, Issue 4, Pages 238-252, July 2005)
- Study on motion of buoy robot chasing spilled oil, included in the Kaiyo Kogaku Shinpojiumu (CD-ROM, 2006)
- Load characteristics of mechanical pectoral fin, published by the Experiments in Fluids Springer journal (Volume 44, Number 5, Pages 759-771, May 2008)
Sources: Japan Today, Japan, August 2, 2008; and various websites
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