G. Bruzzone

ROBY goes to Antarctica

The IX Italian Expedition 1993-94 of PNRA (Programma Nazionale di Ricerche in Antartide) included the first experimental campaign in Antarctica in the field of underwater robotics. It can be described as a pilot mission to better define the role of this technology in the future of Antarctic exploration. The work plan was as follows: to test and develop the CPR-IAN test-bed prototype called ROBY; to verify requirements and constraints of the SARA (Sottomarino Autonomo Robotizzato Antartica), an advanced Antarctic AUV currently being designed by a consortium including CNR, ENEA, Tecnomare and others; and to help scientists collect oceanographic data. The results were satisfactory both from the technical and scientific points of view. Roby worked well in all renditions and no electrical or mechanical problems arose from either the low temperatures or rough treatment involved in such harsh working conditions. Eighteen dives were performed at a maximum depth of 150 metres for a total underwater working time of 20 hours. Most of the marine environments of Terra Nova Bay were explored and documented in the form of video and data; the work met with a favourable response from marine biologists and oceanographers, who will use the collected data for their studies.<<ETX>>

Design and Exploitation of an Autonomous Surface Vessel for the Study of Sea-Air Interactions

The design, development, sea trials and exploitation of the SESAMO (SEa Surface Autonomous MOdular unit) platform, an autonomous surface vessel for the study and characterization of the air-sea interface, are presented. The SESAMO prototype robot, developed by the robotics group of CNR-ISSIA, Genova branch, in strict cooperation with the scientific end-users in the framework of a project of the Italian National Program of Research in Antarctica (PNRA), was able to sample the sea surface microlayer and immediate sub-surface. After satisfactory basic at field trials of the navigation, guidance and control (NGC) and sampling systems, the robotised catamaran was exploited by the scientific end-users for water sample collection in the area of Terra Nova Bay, Ross Sea, Antarctica, in the framework of the PNRA project Chemical contamination.

A real-time mosaicking algorithm using binary features for ROVs

This article presents a real-time mosaicking algorithm based on a SLAM framework. The mosaic of the seafloor can be useful in real time for a ROV operator that is piloting the ROV. Two important aspects arise in this kind of work: data association and computational time. In order to solve the first one, a combination of SURF features and template correlation methods is used. To minimize the computational time, a very recent approach in the domain of feature description is used: BRIEF binary features. Finally, to be able to update the whole mosaicking in a fast and easy way, local mosaics are used instead of a global one. The algorithm was tested using data collected in a typical experiment and the results show the improvement with respect to previous versions of a similar algorithm.

Comparison between feature-based and phase correlation methods for ROV vision-based speed estimation

Abstract The performance of different visual approaches for estimating the motion of an underwater Remotely Operated Vehicle (ROV) is discussed. The paper compares three different techniques: feature correlation, Speeded Up Robust Features (SURF), both based on feature extraction and matching, and phase correlation, which instead does not rely on image features. The three algorithms accuracy and performance are compared using a batch of data collected in typical operating conditions with the Romeo ROV. In estimating vehicle speed, phase correlation outperformed SURF in terms of robustness and precision, giving similar results to those obtained with feature correlation. In terms of computational time, phase correlation outperformed both feature-based methods.

Romeo goes to Antarctica [unmanned underwater vehicle]

Deals with the first operational campaign of Romeo, the latest unmanned underwater vehicle developed at CNR-IAN. Romeo has been designed as an operational testbed to perform research on intelligent vehicles in the real subsea environment. Its main application field is the development of advanced methodologies for marine science. A brief description of the mechanical design and of the control, computing and software architecture of Romeo is given and its exploitation in Antarctica is reported. During the XIII Italian Expedition to Terra Nova Bay (29 October 1997-26 February 1998) it has been used for (a) collecting data about under-ice biological processes, (b) testing under-ice performances of a set of acoustic devices for autonomous navigation and guidance, and (c) collecting benthic data in the Marine Antarctic Specially Protected Area established near the Italian TNB Station.

ROV actuator fault diagnosis through servo-amplifiers' monitoring: an operational experience

A system for ROV actuator fault detection, diagnosis and accommodation through servo-amplifier monitoring and dedicated steady-state maneuvers has been designed on the basis of real data recorded during operating missions of Romeo, the ROV prototype developed by CNR-IAN. In particular, an actuator fault during sea operations of Romeo enabled the validation with real data of the developed system.

Enhancing autonomous capabilities and human-robot interaction for Unmanned Surface Vehicles

In the context of autonomous exploration and observation of water areas by means of Unmanned Surface Vehicles (USVs), this work describes the improvements developed with respect to the advanced mission control system and the integration with multiple and modular sensing devices, in particular underwater cameras and sonar systems. The experimental proof of the concept validity is obtained testing the overall framework on the CNR-ISSIA Charlie USV. Moreover, to enhance the interaction capabilities between human operator and autonomous platform, different driving and commanding devices, including multi-purpose reconfigurable console and smartphone applications, have been developed and integrated with the already existing architecture. Data gathered from the experimental campaign carried out in Murter (Croatia), within the “Breaking The Surface 2011” training field, are reported.

A simulation environment for unmanned underwater vehicles development

Logistics problems and high costs necessary to carry out experiments with robots in hazardous environments such as the open sea led to the development of simulation environments (SE) where the physical robot and the operating environment can be substituted by real-time simulators in a way that is completely transparent to the robots control and sensing modules. SEs are extremely useful tools which allow to rapidly designing, developing, testing and evaluating in lab the working of an underwater vehicle and to minimise the risks to lose expensive equipment during in field testing. In this paper the SE developed by the National Research Council, Institute for Ship Automation of Genoa (CNR-IAN) will be presented.

A comparison between different feature-based methods for ROV vision-based speed estimation

Abstract A comparison study between different state-of-the-art visual approaches for estimating the motion of an underwater Remotely Operated Vehicle (ROV) is performed. The paper compares five different techniques: the template correlation, Speeded Up Robust Features (SURF), Scale Invariant Feature Transform (SIFT), Features from Accelerated Segment Test (FAST) and Center Surround Extrema (CenSurE), all based on feature extraction and matching. All these are implemented on the same free open source library which allows a fair comparison that can establish the best technique (depending on the criteria used). Taking into account previous work where SURF and template correlation techniques were evaluated using a batch of data collected in typical operating conditions with the Romeo ROV, the other techniques are compared using the same data set. In estimating vehicle speed, SURF and SIFT presented noise levels higher but close to template correlation, though SURF and SIFT have more outliers. In terms of computational time, template correlation outperforms all other alternatives by large in some cases.

Execution control of the NGC tasks for ROVs

The problem of designing an interface between the continuous-state and the discrete-state domains of intelligent control architectures is addressed, focusing on the case of a hierarchical navigation, guidance and control (NGC) architecture for unmanned underwater vehicles. The proposed interface represents the underlying continuous-state execution level as a discrete event system using a Petri net formalism. The correct behavior of the execution level is ensured, checking that no forbidden state is reached and that the proper task activation and deactivation order is respected. Methodologies for the off-line generation of the Petri net representation of the execution level and automatic system reconfiguration are presented.