Monday, 4 August 2008
Automated Underwater Vehicle: Maya to unravel secrets of Seas
August 4, 2008
By Syed Akbar
India's latest autonomous underwater vehicle, Maya, is all set to unravel the secrets hidden beneath the Deep and in the murky depths of rivers, lakes and natural tanks. Developed by the Goa-based National Institute of Oceanography, Maya, has been successfully tested for oceanographic studies, marine biology, water quality studies in fresh water reservoirs and dams and environmental monitoring of coastal waters and estuaries.
The country's first indigenously built autonomous underwater vehicle is now all set for large-scale commercial production. Scientists at NIO have utilised Maya for various studies and after successful results, they decided to transfer the technology to entrepreneurs.
Maya is a simple-looking yet sophisticated robot that's capable of passing on the secrets hidden in the unfathomable depths of oceans and seas. World-wide there are only 58 AUVs and NIO's successful testing of Maya has pushed India in the select league of nations with advanced technology in ocean sciences and technology.
According to senior scientist Desa Elgar, Maya is essentially made up of three parts. The first part is the free flooding nose cone of the vehicle, which houses the scientific sensors. This nose cone is swappable and is application specific. The second part is the sealed aluminium hull called the Core Pressure Unit, which contains the batteries, electronics, vehicle sensors, actuators, communication
systems and the electronics. The third part is called the tail cone and is
used to house the propulsion device.
Maya is rated for 200 mts depth operations and is capable of diving to different programmed depths and maintaining control of motion at those depths. It can follow mission paths that are pre-programmed.
Safety features enable the vehicle to return to the surface in case of hardware failure. The missions for the vehicle are loaded through a radio frequency link.
The AUV was used in different environmental settings including the Idukki reservoir in Kerala and a coastal station in the Arabian sea.
"Our experience in this project has confirmed the potential of small AUVs to work in confined spaces and in the open ocean, and as we have experienced, to discover unexpected processes in the ocean," said Elgar Desa. The vehicle was developed by R Madhan, P Maurya, G Navelkar, A Mascarenhas, S Prabhudesai, S Afzulpurkar and S
Bandodkar, besides Desa.
What are AUVs?
Autonomous Underwater Vehicles are essentially propelled robot platforms with on-board computers, power packs and vehicle payloads that enable automatic control, navigation and guidance of the vehicle.
They are used to acquire data from onboard sensors to sense physical, biological and
chemical properties in the ocean, in lakes, in estuaries, rivers, and dams. AUVs are novel to the extent that they can be programmed to dive and to maintain control at any given depth layer in a water body, to navigate by changing course at a chosen depth, to follow seabed terrain, and when a mission is accomplished to return ‘home’.
"A number of oceanographic problems need data acquisition without disturbing the environment. Shipboard profiling and towed instruments packages and samplers in such cases disturb the layer and can introduce errors in measurements. There are situations and places where divers are at risk and in these cases AUVs and Remotely Operated Vehicles equipped withappropriate sensors, power packs, and propulsion capability are able to address these problems to a large extent," the NIO team said.
In the case of Maya, NIO scientists have fitted Maya with sensors for oxygen, chlorophyll, conductivity, turbidity, temperature and depth.
The vehicle was programmed to dive to different depths in a staircase pattern up to 21 mts, and in the second mission at 1 mt depth up to 4 kilometres of continuous operation. It successfully collected data in the missions.
A single underwater motor is used to propel Maya. Two stern planes and a single rudder control diving and heading manoeuvre respectively.
The nose section on Maya is removable and different sensors can be fitted onto it for specific mission at sea.
Maya is designed to receive commands from shore and also send data over high-speed radio link. Underwater navigation uses the Doppler Velocity Log and a dead reckoning algorithm that estimates position below surface. Surface navigation is based on global positioning system.
"Maya has many applications in oceanography. It can collect standard oceanographic data in confined areas, carry out shallow water bathymetry using acoustic methods, detect blooms with the help of optical radiometers, and also work as a test platform for new sensor technologies," the NIO scientists said.
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