A new pair of optical wireless modems has been realized, which exploit visible light communication to transmit Ethernet signals through water. The modem prototypes were finally tested in sea waters at La Spezia harbor; they successfully transmitted 10 Mbit/s 10Base-T signals over up to 10 m, notwithstanding the high turbidity and the strong sunlight. Final tests included the integration with SUNRISE testbed and the use with a moving robot, remotely operated. Commercial components were used to realize the modems; thus, we expect that the key design concepts can be used as a starting point for practical deployment of this technology.

We experimentally demonstrate at NATO site in Spezia a bi-directional underwater optical wireless transmission compliant with 10Base-T Ethernet. Zero packet-loss-was achieved up to 10 m distance in a real harbor, with shallow murky waters and daylight.

This paper presents our recent advancements in the development of the underwater optical wireless modems, designed within the OptoCOMM project. The target performance of the optical modem is to achieve the data rate of 10 Mbit/s at a distance of at least 10 m in presence of sunlight. The transmitter is based on blue Light Emitting Diode (LED) technology. The modem will be developed in three versions to be integrated in Littoral Ocean Observatory Network (LOON) test-bed, and add a novel technology to the infrastructure of the FP7-SUNRISE project. We tested the first version of the modems in a typical shallow harbour water (1 m depth), in the same location of the LOON to validate the adopted technology. The seawater of the test-bed is characterized by a medium-high turbidity (about 1 FTU), which heavily affects the optical communication in terms of attenuation. All tests were run in sunny summer days with very high sunlight illumination level (∼ 100 klux). Despite the challenging conditions, we achieved successful transmission at 10 Mbit/s over 7.5 m distance.

In this paper we present the initial implementation of an integrated optical and acoustic system that can enable large data transfer between mobile and static nodes in Underwater Wireless Sensor Networks (UWSNs). The proposed system is based on the OptoCOMM optical modem and on the SUNSET Software Defined Communication Stack (S-SDCS) framework. The OptoCOMM modem allows to overcome the limits of maximum data rate and bandwidth imposed by the use of acoustic communication by providing a data rate of 10Mbps. SUNSET SDCS instead has been used to provide networking and fragmentation capabilities to efficiently offload large data in UWSNs. The performance of the proposed approach has been evaluated through in lab experiments where large files with arbitrary sizes have been optically transferred. The results achieved show that our system is able to transfer up to 1.5 GBytes of data in short time.

OptoCOMM aims at demonstrating the potential, at physical level, of a communication facility for the SUNRISE platform constituted by an Optical Underwater Wireless Communication (OUWC) module with target performance of 10 Mb/s transmission rate at 10 meters range in shallow medium/high turbidity harbour waters. The module, which is based on blue Light Emitting Diode (LED) units and common photodiodes, is an evolution of the proof-of-principle prototype already proven in laboratory (pool). It will constitute an additional node integrated in the Littoral Ocean Observatory Network (LOON) test-bed of the SUNRISE infrastructures, providing a high speed and short-range communication node, which will complete the capability of acoustic modems already present in the test-bed. Three modules (nodes) will be developed and experimentally demonstrated: one for direct integration with the LOON infrastructures, one, battery powered, to be potentially installed on buoys, Remotely Operated Vehicles (ROVs), etc., and one to be installed on the eFolaga Autonomous Underwater Vehicle (AUV) of the proponents. The paper describes in detail the development of the modems as well as the first lab experiments, where the core technology has been successfully tested.

The paper provides a comparison between different control allocation techniques in over-actuated Autonomous Underwater Vehicles. The pseudoinverse, Linear Programming (LP), Quadratic Programming (QP), Mixed Integer Linear Programming (MILP) and Mixed Integer Quadratic Programming (MIQP) are evaluated in simulation on the V-Fides vehicle model. The MILP and MIQP techniques allow to include in their implementations a more detailed characterization of the non-linear static behaviour of the actuators. This customizability can be also exploited to improve the practical stability of the system. The metrics used for comparison include the maximum attainable forces and torques, the integral of the error allocation and the required thrusters effort. Our simulation results show that, in particular with respect to thrusters effort, MILP and MIQP are the preferred allocation methods. The computational complexity associated to both methods is not such to compromise their implementation in operating vehicles; in particular, the MILP version is currently implemented in the V-Fides vehicle.

The objective of this paper is to address the problem of Fault Detection and Isolation (FDI) on thrusters of an over-actuated Autonomous Underwater Vehicle (AUV) under on/off abrupt faults. The goal is pursued through Non-Linear Principal Component Analysis (NLPCA), which is the non-linear extension of the popular Principal Component Analysis (PCA). While the Fault Detection (FD) system directly exploits the model-free nature of NLPCA (data-driven approach), the Fault Isolation (FI) is achieved by properly train off-line Artificial Neural Network (ANN). The consistency and robustness of the proposed method is verified in realistic simulation.

The proposed work is in the framework of the V-Fides project, in which is a general purpose, 3000m depth rated underwater vehicle with highly maneuverability capabilities was developed. The project was co-funded by Tuscany Region (Italy) and developed by a team lead by WASS S.p.A. (Whitehead Sistemi Subacquei, Livorno) with the participation of several partners including two research institutions of the University of Pisa and Small-Medium Enterprises in the Pisa-Livorno area. The vehicle is equipped with a sensors payload for autonomous navigation. This contribution describes an integrated calibration/navigation filter capable of estimating the relative (rotational) calibration parameters between the IMU and the DVL, and producing the standard velocity and attitude navigation output together with accelerometers biases. The results were demonstrated with real data sets collected during extensive experimental campaigns. Finally the observability analysis is proposed in order to define the motion requirements for the asymptotic convergence of the parameter estimates.

This paper describes a nonlinear complementary filter capable of estimating the course motion variables namely the position, velocity, heading and accelerometers bias of an agile, over-actuated AUV during underwater operations, using the inertial sensors (IMU), the DVL, the depth sensor and the compass. The proposed work is within the framework of the V-Fides project, co-funded by Tuscany Region (Italy) and developed by a team lead by WASS S.p.A. (Whitehead Sistemi Subacquei, Livorno). The aim of the project was to develop and evaluate an high-depth, over-actuated, long endurance Autonomous Underwater Vehicle (AUV). The paper proposes the mathematical development of the observer, together with some experimental results, able to demonstrate the capabilities of the estimation scheme, compared with the estimations obtained via a standard Kalman Filter.

The proposed work aims to describe the “V-FIDES” project, focused on developing a new generation of agile, over-actuated, long endurance Autonomous Underwater Vehicles, for deep underwater exploration, operation and environmental monitoring. The project, co-funded by Tuscany Region (Italy), has been developed by a team lead by WASS S.p.A. (Whitehead Sistemi Subacquei, Livorno), with the participation of several partners including Kayser Italia S.r.l., Scuola Superiore Sant'Anna, University of Pisa and other SMEs in the Tuscany area. This paper gives an overview of the developed general architecture of the vehicle and obtained results during the project.

The adoption of fault detection and isolation (FDI) techniques is fundamental to ensure high levels of safety and productivity, especially in critical and expensive applications like Autonomous Underwater Vehicles (AUV). This paper describes a comparison between different techniques available in the literature, applied to over-actuated AUVs under single fault condition (SFC) and considering only abrupt faults. The main contribution of this work is twofold: first, we show how such techniques can be adapted to the case of over actuated AUVs in order to isolate and identify a faulty situation of one thruster. Moreover, we give a means for robust fault reaction by using an optimal control allocation problem, which is tightly coupled with the FDI algorithm. The proposed work is in the framework of the V - Fides project and the algorithms are demonstrated in simulation, employing the dynamical model of that vehicle.

The proposed work is in the framework of the V-Fides project, aiming at developing a new generation of agile, over-actuated, long endurance Autonomous Underwater Vehicles, for deep underwater exploration, operation and monitoring. The project is co-funded by Tuscany Region (Italy) and is developed by a team lead by WASS S.p.A. (Whitehead Sistemi Subacquei, Livorno) with the participation of several partners including two research institutions of the University of Pisa and Small-Medium Enterprises in the Pisa-Livorno area. The vehicle is a general purpose, 3000m depth rated underwater vehicle with highly maneuverability capabilities, which can operate both as AUV and ROV. The vehicle is equipped with seven thrusters, with asymmetric input-output characteristic, and with a sensors payload for autonomous navigation, composed by: a tactical grade Inertial Measurement Unit (IMU), a Doppler Velocity Logger (DVL), a depth sensor, a magnetic compass and an acoustic modem for underwater communication and localization. This contribution gives an overview of the developed general architecture of the Navigation and Control module of the vehicle, from the algorithmic and system implementation stand-points.

Since the introduction of the first prototypes of robotic end-effectors showing manipulation capabilities, much research focused on the design and control of robot hand and grippers. While many studies focus on enhancing the sensing capabilities and motion agility, a less explored topic is the engineering of the surfaces that enable the hand to contact the object. In this paper we present the prototype of the Velvet Fingers smart gripper, a novel concept of end-effector combining the simple mechanics and control of under-actuated devices together with high manipulation possibilities, usually offered only by dexterous robotic hands. This enhancement is obtained thanks to active surfaces, i.e. engineered contact surfaces able to emulate different levels of friction and to apply tangential thrusts to the contacted object. Through the paper particular attention is dedicated to the mechanical implementation, sense drive and control electronics of the device; some analysis on the control algorithms are reported. Finally, the capabilities of the prototype are showed through preliminary grasps and manipulation experiments.