Autonomous Underwater Vehicle
A wireless robotic sea-vehicle that can map the seafloor.
By Vantika Dixit, February 2010
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Researchers at Central Mechanical Engineering Research Institute (CMERI) - the apex R&D institute for mechanical engineering under the Council of Scientific and Industrial Research (CSIR) – have developed India’s first indigenous autonomous underwater vehicle (AUV). The robotic vehicle is expected to complete the final sea trial by August 2010. The mega system can fulfill tasks such as seafloor mapping, coastal surveillance, mine countermeasure, and oceanographic measurements during adverse weather conditions.
Sponsored by the Ministry of Earth Sciences (MES), the AUV has been built to operate 150 feet under the sea (see Specifications) to map the seafloor and collect sensor-based data. With no physical cable connection to the surface control station and possessing on-board intelligence and energy supply, the vehicle, designated as AUV-150, has much to boast about.
Autonomous underwater technology and underwater robotics are being vigorously pursued in many technologically advanced countries such as the U.S., Australia, Germany, Russia, Korea, and Japan. According to Gautam Biswas, director, CMERI, “The AUV technology will be an essential technology of the future as our dependence on ocean resources increases. The need for autonomous underwater vehicles is already being felt for activities such as inspection, location of objects, survey on the ocean floor, and surveillance.”
“AUV-150 will be tested in sea for seafloor mapping and monitoring of environmental parameters such as current, temperature, depth, and salinity. Once the technology is proven through extensive trial, the same vehicle with required customization may be used for other future applications such as coastal monitoring, military reconnaissance, mine counter measuring, cable and pipeline surveys, littoral zone sensing, and more,” says Biswas.
FEATURES
AUV-150 is a cylindrical-shaped carrier with streamlined fairing to reduce hydrodynamic drag. It is embedded with advanced power, propulsion, navigation, and control systems. The propulsion system comprises thrusters for generating motion in different directions to control surge, sway, heave, pitch, and yaw, while preventing the vehicle from rolling. Two arrays of cross-fins have also been fixed at the two ends to provide additional stability to the AUV. A lithium polymer battery powers the vehicle and a pressure hull contains its electronics and energy system.
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The vehicle is programmed to carry out an underwater mission without assistance from an operator on the surface. For autonomous free movement under water, with no wires attached to the station on the surface, the vehicle determines its own geographical position with the help of navigational sensors. Its forward looking sonar system and navigational algorithm help the vehicle in avoiding collision with obstacles.
The autonomous vehicle is equipped with a number of navigational (inertial navigation system, depth sensor, altimeter, doppler velocity log, forward looking sonar, global positioning system through ultra- short baseline system, which is a method of underwater acoustic positioning and payload sensors (side scan sonar, camera, and CTD or conductivity-temperature-depth recorder). For smooth communication and distant intervention, the vehicle is equipped with hybrid communication system: it radio frequency on surface and acoustic under water.
The final prototype of the 4.8 meter-long AUV-150, with all its on-board subsystems, weighs approximately 490 kg. The vehicle also has positive buoyancy of approximately 30 newton to facilitate its retrieval in case of a power failure. However, the payload and configuration of the AUV will always be dictated by the mission requirements such as the one provided by the Ministry of Earth Sciences (MoES).
In 2009, a mock steel unit was tested at shallow basin towards validation of various algorithms. Based on the test data, the final prototype of AUV has been developed. In September 2009, the prototype was tested for a week at the Idukki lake in Kerala. Both pre-launch and post-launch checks were committed. During all trials, the mission was carried out with the help of a pre-compiled mission file which was stored in the memory of the on-board computational unit. The final prototype is now ready for sea trial even as work continues to fine tune various algorithms related to navigation, guidance, and control.
PURPOSE
Developed under the supervision of Sankar Nath Shome, group head - robotics and automation and Dean of School of Mechatronics, CMERI, AUV-150 is second only to Maya, a small autonomous underwater vehicle developed by the National Institute of Oceanography (NIO), Goa (another CSIR lab) in September 2009 to sense physical, biological, and chemical properties of the ocean and collect relevant scientific data.
“The working prototype of AUV-150 was developed by the Mechadronics group of CMERI in collaboration with IIT, Kharagpur. The performance parameters of the lab-scale model, developed by IIT Kharagpur, acted as a precursor of the prototype developed by CMERI. The final prototype is capable of exploring the seafloor for unlimited treasure which can be used for mankind, for example, minerals (metals, oil, natural gas, and chemicals), medicines, and food,” says Shome.
The vehicle is also expected to be used for search and rescue operations as well as for military reconnaissance. It is capable of conducting various kinds of surveys such as the bridge scour which is a process of removing sediments of sand and rocks around bridge piers; channel conditioning and clearance survey, which is a hydrographic survey involving determination of size, location, and sedimentation for a channel and requirements for dredging towards flood control measurements; and cable and pipeline surveys for monitoring and repair operations.
Long-term monitoring of seafloor for prediction of weather, habitat mapping, archaeological survey and monitoring of boundary limitations and route survey are other tasks that AUV-150 is expected to perform once the sea trial is over.
Following AUV-150’s successful completion, CMERI and the Naval Science and Technology Laboratory are now planning to launch a mega AUV project under the umbrella of CSIR and DRDO. India, therefore, may see a lot more technology developments in the year ahead.
Vantika Dixit is Senior Assistant Editor of Technology Review India.
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