Scope and Motivation

Unmanned Surface Vehicles (USVs) have become popular over the last decades motivated by civilian and military applications where security and safety of humans can not be guaranteed. Due to the absence of human pilots on board, USVs can perform several tasks with reduced cost, lower danger, and even higher performance. The most dominant examples are observation/data collection and environment sampling. Several tens of USV models have been designed for these purposes, however most of the existing solutions are large (more than 1.5 meters long) as well as heavy (a few hundred kilograms or more). Yet, based on INESC TEC’s experience in the field, weight and dimensions are relevant characteristics to take into account for logistic reasons. Naturally, small vehicles have the advantage of less demanding requirements, regarding transportation, deployment and recovery. Nevertheless, their capability to carry additional payload should not be neglected.

On the other hand, the huge ocean economy potential is envisioned to increase the activity at the ocean, worldwide, in the coming years, including resource exploitation on the sea floor, environmental monitoring, scientific exploration, and surveillance of maritime borders, apart from the traditional activities such as maritime transportation and fisheries. To perform many tasks in this context, USVs are considered a solution to enrich and extend water-based scenarios for Internet of Things (IoT) platforms and Machine-to-Machine (M2M) applications that will support coordinated network operations and novel above water communication technologies.

Communications at sea are currently limited to use of HF/VHF radios and satellite. HF communications have been mostly used to enable buoy-to-shore data transmission from oceanographic buoys, but they are proprietary and narrowband. VHF analogic radios are typically used for ship-to-ship and ship-to-shore communications, but they are narrowband too and limited to voice applications. In order to access the Internet at a few kilometers from shore, satellite communications are commonly used, but they require proprietary and unaffordable equipment, and are still limited in bandwidth. On the other hand, cellular networks and wireless communications at 2.4/5GHz enable broadband communications, but can only be used near-shore.


FLEXUS aims at extending RAWFIE experimental infrastructure by providing ten maneuverable, small-sized and one-man-portable USVs, designed for outdoor operations and capable to easily accommodate additional payload. FLEXUS aims not only at providing the USVs, but also at endowing them with:

  • a rich set of motion and communication capabilities, being a significant distinction from other small size solutions;
  • over-the-air (OTA) programming, to enable loading of waypoints missions and also control features during a mission;
  • real-time video/photo and data dissemination to the Internet;
  • long-range and multi-hop wireless communications in order to connect the USVs between them, and to run experiments up to several kilometres from shore or from a mission-support ship.

The following specific objectives are considered.

  • To provide innovative USVs, highly reconfigurable either in their motion, communication capabilities and payload, and easy to deploy, operate and maintain by a single person.

  • To specify and implement the FLEXUS communications solution, which will include multi-hop and wireless mesh techniques for extended range, heterogeneous access networks, and emerging long range wireless technologies.
  • To provide to the FLEXUS USVs the ability to run and monitor experiments defined in the scope of RAWFIE project.

  • To engage end-users for testing new networking solutions, services, USVs behaviors and payloads as well as applications over the FLEXUS and RAWFIE testbed (e.g., Navy).