AUV System Spec Sheet

TriMARES configuration

Platform: TriMARES
Manufacturer: University of Porto Ocean Systems Group

Summary

TriMARES AUV

TriMARES is a 3-body autonomous underwater vehicle, based on the MARES design. The vehicle was designed to provided extra payload capability, including high quality video and sonar. The physical arrangement ensures motion smoothness for improved quality in payload and positioning data. Navigation sensors include an IMU, a pressure sensor and an acoustic positioning systems. This vehicle was developed under a contract with a Brazilian power plant company.

Main features:

• modular construction, with reconfigurable sections
• spare ports to accomodate payload sensors
• robust, with fully shrouded moving parts
• operates in confined areas – can ascend/descend in the vertical
• 5-dof (surge, sway, heave, yaw, pitch)
• autonomous operation, with simple mission definition
• optional fibre-optic umbilical for video transmission (ROV operation)
• rechargeable Li-Ion batteries

TriMARES is a 3-body autonomous underwater vehicle, designed to provided extra payload capability, including high quality video and sonar. The physical arrangement ensures motion smoothness for improved quality in payload and positioning data.  TriMARES motion is provided by seven independent thrusters, 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 of underwater structures.

Mechanical Structure and Propulsion
The TriMARES’ mechanical arrangement follows a modular approach, with three main bodies linked by a light mechanical structure. Each body is assembled with interchangealble cilindrical sections, most of them machined in acetal copolymer.

Horizontal propulsion and direction are controlled by four independent thrusters located at the stern. Another set of thrusters, in the vertical direction, control vertical velocity and pitch angle. A single lateral thruster provides sway motion. The thruster arrangement permits operations in very confined areas, with virtually independent horizontal, vertical, and lateral motion at velocities starting at 0 m/s.

Electrical Components
Energy is provided by rechargeable Li-Ion batteries located in the lower pod, with a total energy of 800 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 located in the upper port body, 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, inertial data and thruster RPM to compute the estimated position.

Payload Sensors
TriMARES has spare cilindrical sections to accomodate payload sensores, such as video and sonars, and it is simple to include further modules if required. All end caps have spare connectors to provide energy and communications.
Larger payload sensors may also be attached to the mechanical structure.

Vehicle Operation
Before vehicle launch, two acoustic beacons are deployed in the operation area.
TriMARES missions may be programmed as an AUV using a GUI software, where all mission segments are detailed (waypoints, velocity, depth, …). Alternatively, the operator may chose to connect the fiberoptic umbilical to steer the vehicle as an ROV, providing also a highspeed link for realtime data transmission.