successful final grex sea trials, november...

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Successful final GREX sea trials, November 2009

The final sea trials where organised by the Instituto Superior Técnico (IST) from Lisbon in Portugal. Together with Atlas Elektronik, Ifremer, the Technical University of Ilmenau, the University of the Azores and the company SeeByte they form the technical core of the GREX consortium. The work of the techni-cal team is developed in cooperation with marketing, communi-cation and exploitation activities coordinated by MC Marketing Consulting and Innova.

3 November 2009Newsletter

The GREX project reached the final important milestone in early November 2009 when a series of successful sea trials

took place at the Atlantic coast around the Portuguese city of

Sesimbra.The main objective of the

trials was to verify the concepts developed for the

simultaneous operation of two AUVs and two catamarans,

which relied on inter-vehicle communication to perform

totally autonomous a series of coordination tasks as coopera-

tive path following, go to for-mation manoeuvres and coo-

perative line of sight target fol-lowing.

These achievements represent an important final project goal

for the GREX consortium.

All four autonomous robots in the bay of Sesimbra

3 November 2009GREX-Newsletter

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The final trials featured inter-vehicle communication and coordination of a fleet of two AUVs and two catamarans as the main focus. In order to gather useful data and experience in realistic condition all 4 vehicles were equipped with the modem chosen by the GREX consortium.

The potential for interference between vehicle noise and VEMCO acoustic fish tracking tools was also tested during real multi-vehicle missions. All vehicles were tested as carrying plat-forms for self-contained VEMCO re-ceivers VR2 and VR2W. VEMCO V16 coded depth sensors transmitters were used to simulate both fixed and mobile (onboard) targets.

The autonomous surface vehicles DELFIMx (right) and DELFIM (left) from IST

The AUVs SeeBee from ATLAS (left)

and AUVortex from Ifremer (right)

VEMCO receiver

During the final tests different autonomous tasks which represent the basic ingre-dients of larger and more complex swarm missions have been successfully tested in Sesimbra. As a first step, a “Coordinated Path Following” of all four autonomous vehicles has been achieved. Each vehicle runs its own tack while “talking” to each other and adjusting their speed in order to coordinate the group and to reach the planned formation. Eventually the fleet of all four robots follows the path and keeps the desired formation pattern.


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As a second step the “Go to Formation” manoeuvre has been tested. The proce-dure is the same as for the “Coordinated Path Following” with a time-varying for-mation pattern. The vehicles were scattered after the deployment and calculated their path towards a starting point without any conflicts.

The final sea trials step focused on one of the early envisioned GREX sce-narios: a formation of vehicles recei-ving the location of a target through an acoustic channel and tracking it while keeping the desired formation. The new CLOST2 (Coordinated Line of Sight Target Tracking) algorithm proved to work in the real world with two tracking autonomous surface ve-hicles and a manned vessel (equipped with an acoustic modem) playing the role of the target.

In summary it has been verified that all vehicles were successfully able to keep a spatial formation in a self-organized manner. The main idea behind this is to cre-ate a wider sensor coverage aiming at high efficient search or mapping missions.

Arc mission with all four vehicles

CLOST2 algorithm test at sea results,

the target (red square) moved sequentially

to waypoints 2, 3 and 4

Triangle mission with DELFIMx, DELFIMand Vortex


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As a main project result it has been achieved that a preliminary GREX-box is now available which can turn already existing vehicles into cooperative robots to fulfil swarm applications. This pack-age consists mainly of a bunch of soft-ware modules which communicate to other GREX-systems, care for naviga-tion updates, and control the coopera-tive movement of the group.

The most visible part of the software is the mission-planning tool which has been developed to plan a complete cooperative mission – including all vehicles – on a single graphical user interface (GUI). This is achieved using a modified version of SeeTrack, which is a commercial product of the Scottish company SeeByte.

The GREX software in general consists of the following four modules:

Interface module as gateway between GREX and the world of single vehicles

Team navigation module to optimise the relative orientation of the team members

Communication module for data exchange with other vehicles

Team handler module which is responsible for the execution of the multi-system mission control.

Graphical User Interface (GUI) from SeeByte

Multi System Mission Control

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GREX Multi System Mission Control

Replanning Commands

(Own Vehicle)

Replanning Commands

(Other Vehicles)

Data from other vehicles

Payload Data

Navigation Data


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Main Results

The GREX project has been launched in June 2006 within the 6th framework pro-gramme of the European Union. The major goal of this 3 and a half year project was the creation of a first operational framework and middleware to coordinate a flock of heterogeneous unmanned autonomous marine vehicles. In order to get a widely general solution the requirements are routed along mission scenarios which incorporate all basic elements of civil and military applications.

The status achieved by the end of 2009 will allow using the GREX system as a stepping stone for real multi-vehicle applications. Emphasis of the future develop-ment needs to be placed on payload data exchange in order to maximize the effect of spatially distributed measurements as well as to increase the reliability of the acoustic communication.

Besides the tested scientific scenarios future applications for swarm robots could be pipeline tracking and inspection, magnetic field mapping of seabed areas as well as archaeological and also military applications.

The GREX Team in Sesimbra


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General Project Information

Introduction

Today, due to the limitations of state-of-the-art embedded systems, underwater researchvehicles are limited in both their autonomy and capabilities. It would be a leap ahead, if a researcher could use a multiple vehicle approach, whereby each vehicle plays the role of a sophisticated node (with sensor, processing, and com-munication capabilities) in a possibly large network – this means combining the properties of different systems in a team. “Grex” - the Latin word for a herd or flock – intimates the focus of the project: to create a conceptual framework and middleware to coordinate a flock of heterogeneous robotic vehicles in order to achieve a well defined practical goal in an optimized manner.

Objectives

The main goal of the project is to achieve a first level of distributed “intelligence” through dependable embedded systems that are interconnected and cooperate towards the coordinated execution of tasks. Thus the project will witness the development of theoretical methods and practical tools for multiple vehicle coo-peration, bridging the gap between concept and practice. The technology deve-loped must be on one hand sufficiently generic in order to interface pre-existing heterogeneous systems. On the other hand it must be sufficiently robust to cover problems caused by faulty communications.

GREX System Overview


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The GREX project has been started on 1st June 2006 and will be funded by the EU IST (Information Society Technologies) programme (IST-No. 035223) under the 6th Framework Programme.

Further information on the GREX project is available under www.grex-project.eu.

GREXc/o ATLAS ELEKTRONIK GmbHMr. Jörg KalwaSebaldsbrücker Heerstraße 235D-28309 Bremen/GermanyEmail: [email protected]

Consortium Atlas Elektronik GmbH, Germany

IMAR-DOP/University of the Azores, Portugal

Ifremer, France

Technical University of Lisbon - IST/ISR, Portugal

TU Ilmenau, Germany

SeeByte Ltd., Great Britain

Innova S.p.A, Italy

MC Marketing Consulting, Germany

successful final grex sea trials, november...

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