Lorenzo Brignone

The European R&D-Project MORPH: Marine robotic systems of self-organizing, logically linked physical nodes

Abstract The MORPH project (FP 7, 2012-2016) advances the novel concept of an underwater robotic system composed of a number of spatially separated mobile robot-modules, carrying complementary resources. Instead of being physically coupled, the modules are connected via communication links that rely on the flow of information among them, i. e. inter-module interactions are enabled by underwater communication networks at distant and close ranges and supported by visual perception at very close range. Without rigid links, the MSV can reconfigure itself and adapt in response to the shape of the terrain, including walls with negative slope. The MORPH concept requires qualitatively new behaviors such as adaptive sensor placement for perception and navigation, as well as environmental modeling in complex environments. On site view planning will lead to a solution well beyond the operational state of the art for underwater cliff surveys and other similar missions. A final demonstration on a vertical cliff, unfeasible automatically with todays technology, will validate the efficacy of the methods developed at the end of the project.

GREX sea trials: first experiences in multiple underwater vehicle coordination based on acoustic communication

As unmanned marine vehicles rapidly establish themselves as powerful and reliable tools in an ever increasing number of tasks, the focus of research has shifted towards simultaneous operation of coordinated fleets of vehicles. The GREX project joins this development effort with a comprehensive and ambitious development plan. This paper gives account of the first sea trials experience involving a fleet of two AUVs performing a simple coordination task relying on inter-vehicle acoustic communication.

Multiple AUV control in an operational context: a leader - follower approach

As Autonomous Underwater Vehicles universally establish themselves as invaluable tools to provide unprecedented results in a variety of scientific, industrial and naval scenarios, the focus of development is gradually shifting towards considering the operation of multiple cooperating vehicles. There is widespread consensus on that despite the added complexity of having to operate several vehicles, the multiple AUV approach enables the definition of new interesting scenarios which offer a potential improvement in the quality of the collected data and a reduction in operational costs.

ART-R: a novel reinforcement learning algorithm using an ART module for state representation

The work introduces a neural network (NN) algorithm capable of merging the fast and stable learning behaviour offered by the adaptive resonance theory (ART) and the advantageous properties of a reinforcement learning agent. The result is ART-R a neural algorithm particularly suited to learning state-action mappings in control applications. A real time example addressing a typical problem found in autonomous robotic assembly is discussed to highlight the achievement of unsupervised and fast learning of an optimal behaviour.

Communication infrastructure for fleets of autonomous marine vehicles: concepts and first results

Abstract Cooperative robotics have been one of the hot topics of research for different scientific and technological fields throughout the last decade. Extending the concepts explored in land and aerial robotics to the underwater application scenarios have proven to be particularly difficult due to the limitations of the available communication channels, lack of standardization, etc. The GREX project aims at providing the means to use different autonomous marine vehicles, from different manufacturers in cooperative missions. This paper describes the ongoing work related to the development of the communication system that supports all data exchange required for team operation and gives account of the first sea trials experience involving a fleet of two AUVs performing a simple coordination task relying on inter-vehicle acoustic communication.

CORAL: The new deepwater AUV program by IFREMER

The French National Oceanographic Institute IFREMER has announced the launch of a new autonomous underwater vehicle program to provide the scientific community with an innovative tool for deepwater exploration. The new system targets the needs of a wide user base (oceanographers, marine geologists, geophysicists, biologists, sedimentologists, …) and will thus offer the ability to integrate and actively interact with a wide range of payload sensors.

A new underwater optical modem based on highly sensitive Silicon Photomultipliers

Silicon Photomultipliers (SiPMs) have recently been recognized as an interesting alternative to photomultiplier tubes (PMTs) thanks to their high sensitivity and time resolution. They can closely approach quantum-limited sensitivity in the detection of weak optical signals. Ifremer (French Research Institute for Exploitation of the Sea) and Institut Fresnel research lab have been investigating appropriate alternative solutions for PMTs in the context of underwater optical communications, and have for the first time used these new photodetector components for signal detection. A novel prototype of an optical modem based on SiPM receivers was realized with support from Osean SAS Co., a French instrumentation company. A number of lab experiments and sea trials in turbid waters and clear open sea were conducted using this modem to evaluate the practical interest of SiPMs. This paper studies the feasibility of using SiPMs for underwater optical communications. It outlines the description of the transmitter and the receiver of the modem prototype, the different techniques used to take advantage of this new technology and solutions to possible practical challenges. It also presents the methodology of the conducted sea trials and the performance evaluations in terms of range and data rate.