Autonomous instrumentation for oceanography : Maya
This propelled robot platform (AUV) is mounted with on-board computer, power packs and vehicle payloads which enable automatic control, navigation and guidance of the vehicle and acquire data from onboard sensors to sense physical, biological and chemical properties in the ocean, lakes, estuaries, rivers and dams. 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’.Without disturbing the environment data has to be acquired for example shipboard profiling and towed instrument packages and samplers can cause disturbances and can introduce errors in measurements, even there are situations and places where divers are at risk and in these cases AUVs and ROVs equipped with appropriate sensors, power packs and propulsion capability are able to address these problems to a large extent.
The Maya AUV  follows a classical submarine design consisting of a low drag, slender ellipsoid removable nose cone on which scientific sensors can be mounted, a main hull bored from a single bar of aluminum alloy which has been pressure tested to depths of 200 metres, and a tapered Myring profile rear cone with a single DC motor at the extreme end for propulsion. It has two stern planes and two rudders to control diving and heading manoeuvres respectively. The nose section can accommodate different sensors for specific missions at sea. The AUV can receive commands from the shore over a high-speed UHF radio link or download data over the same link. Underwater navigation uses a Doppler velocity log (DVL) to measure speed and a navigation filter that estimates its position below sea surface. Surface navigation is based on GPS.
Mission specific removable nose cones
Design considerations have made it necessary to fabricate a series of removable nose cones which have mission specific sensors. For example, physical properties of the ocean are best studied with a conductivity, temperature, depth (CTD) sensor customised to fit within the available volume offered by the nose. All nose cones are free flooding and can be fitted on to the front pressure endplate of the main hull. Other missions incorporating biogeochemistry require a combination of dissolved oxygen (DO), chlorophyll and turbidity sensors fitted on an identical nose cone.