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Technology - the MARES AUV

MARES (Modular Autonomous Robot for Environment Sampling) is a 1.5m long Autonomous Underwater Vehicle that can be configured to carry a wide variety of sensors, collecting data while following predefined trajectories. One of the inovations on MARES is the thruster configuration with no control surfaces, resulting in the ability to hover in the water column, to navigate close to the bottom, or to perform close-up inspections.

Mechanical Structure

MARES' mechanical structure follows a highly modular approach, with a central hull and several aditional sections.

Since all sections are mechanical extensions, they can be easily interchanged and it is very simple to insert new sections.

Propulsion and direction are controlled by two independent horizontal thrusters. Another set of thrusters, in the vertical direction, control vertical velocity and pitch angle.

The thruster arrangement permits operations in very confined areas, with virtually independent horizontal and vertical motion at velocities starting at 0 m/s.

Electrical Components

The electronic circuits are located in the centrall hull. Energy is provided by Li-Ion batteries, with a total energy of 600 Wh. Depending on vehicle velocity, these batteries can last up to 10 hours, corresponding to about 40km.

The main computer is a PC-104 stack, with a power supply, the CPU, a communications board and a solid-state disk.

The navigation system is based on a LBL acoustic network. The vehicle software continuously fuses ranges to the acoustic beacons, together with compass heading and thruster RPM to compute the estimated position.

Payload Sensors

MARES has limited room to accomodate payload, but it is simple to include additional sections and the main hull has several spare connectors to provide energy and communications.

Larger payload sensors may also be attached to the outside of the hull.

Mission Programming and Supervision

Before AUV launch, 2 acoustic beacons (typically 2 NIBs) are deployed in the operation area.

MARES missions are programmed using a GUI software, where all mission segments are detailed (waypoints, velocity, depth, ...)

During the mission, the acoustic beacons transmit vehicle location data to a support vessel, so that the AUV trajectory can be followed in real time.

At the end, the vehicle starts transmitting her own position by radio, when at the surface.

(>> animation of NIB deployment and MARES mission, 5MB, courtesy B'lizzard Ltd.)

 

Selected Publications

Aníbal Matos, Nuno Cruz, "MARES - Navigation, Control and On-board Software", in Underwater Vehicles, A. Inzartsev (ed.), ISBN 978-953-7619-49-7, In-Tech, Austria, 2009.

Bruno Ferreira, Miguel Pinto, Aníbal C. Matos, Nuno A. Cruz, "Control of the MARES Autonomous Underwater Vehicle", Proceedings of the MTS-IEEE Conference Oceans'2009, Biloxi, MS, October 2009.

Bruno Ferreira, Miguel Pinto, Aníbal C. Matos, Nuno A. Cruz, "Modeling and Motion Analysis of the MARES Autonomous Underwater Vehicle", Proceedings of the MTS-IEEE Conference Oceans'2009, Biloxi, MS, October 2009.

Nuno Cruz, Aníbal Matos, "The MARES AUV, a Modular Autonomous Robot for Environment Sampling", Proceedings of the MTS-IEEE Conference Oceans'2008, Quebec, Canada, September 2008.

Nuno Santos, Aníbal Matos, Nuno Cruz, "Navigation of an Autonomous Underwater Vehicle in a Mobile Network", Proceedings of the MTS-IEEE Conference Oceans'2008, Quebec, Canada, September 2008.

Patrícia Ramos, Sandra Carvalho, "Foz do Arelho Outfall Plume Predictive Study", Proceedings of the MTS-IEEE Conference Oceans'2008, Quebec, Canada, September 2008.

Aníbal Matos, Nuno Cruz, "Coordinated Operation of Autonomous Underwater and Surface Vehicles", Proceedings of the MTS-IEEE Conference Oceans'2007, Vancouver, Canada, October 2007.

Aníbal Matos, Nuno Cruz, "Simultaneous Acoustic Navigation of Multiple AUVs", Proceedings of the Conference MCMC - Maneuvering and Control of Marine Crafts 2006, Lisbon, September 2006.

Aníbal Matos, Nuno Cruz, "AUV navigation and guidance in a moving acoustic network", Proceedings of the IEEE Oceans'2005 Europe, Brest, France, June 2005.

Aníbal Matos, Nuno Cruz, “Algorithms for External Tracking of an AUV”, Proceedings of the Conference IAV’04, Lisbon, July 2004.

Aníbal Matos, Nuno Cruz, F. Lobo Pereira, “Post Mission Trajectory Smoothing for the Isurus AUV”, Proceedings of the Conference Oceans 2003 MTS/IEEE, San Diego, CA, USA, Sept. 2003.

(>> extended list of publications)

Vehicle Status

Jul'09 - Onboard controllers redesigned, improving performance both in the horizontal plane (horizontal velocity and orientation) and in the horizontal plane (vertical velocity and pitch angle).

Aug'08 - ECO-Triplet installed, measuring Chlorophyll-a, CDOM and 660nm red backscatter.

Nov'07 - First sea trial. The MARES AUV was demonstrated at sea off the Portuguese coast, collecting CTD data to map the plume emanating from a sewage outfall near Foz do Arelho.  (>> 2 min. video, 7MB, courtesy B'lizzard Ltd.) (>> more information)

Oct'07 - First autonomous mission. The MARES AUV was demonstrated in fresh water, in the Douro river. She navigated using LBL and collected CTD data in a 300x50m area. (>> more information)

Jul'07 - All major subsystems independently validated: energy management, onboard computer, navigation system and mission programming.

Sep'06 - First pool dive. Depth controllers were tuned to allow independent depth and pitch control. (>> short video, 1MB)

Aug'06 - First water test. The AUV was fully assembled and tested for buoyancy and trimming in a water tank.

May'06 - First mechanical parts machined in a local machine shop.

 

Overview of MARES AUV

MARES equipped with CTD, S. Martinho Porto,
November 2007

MARES at surface in Crestuma, Douro river,
October 2007

 

 

 
 
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