Marco Natalini

Typhoon at CommsNet13: Experimental experience on AUV navigation and localization

The CommsNet 2013 experiment took place in September 2013 in the La Spezia Gulf, North Tyrrhenian Sea. Organized and scientifically led by the NATO S&T Org. Ctr. for Maritime Research and Experimentation (CMRE, formerly NURC), with the participation of several research institutions, the experiment included among its objectives the evaluation of on-board acoustic Ultra-Short Base Line (USBL) systems for navigation and localization of Autonomous Underwater Vehicles (AUVs). The ISME groups of the Universities of Florence and Pisa jointly participated to the experiment with one Typhoon class vehicle. This is a 300 m depth rated AUV with acoustic communication capabilities originally developed by the two groups for archaeological search. The CommsNet 2013 Typhoon, equipped with an acoustic modem/USBL head, navigated within the fixed nodes acoustic network deployed by CMRE. This allows the comparison between inertial navigation, acoustic self-localization and ground truth represented by GPS signals (when the vehicle was at the surface). The preliminary results of the experiment show that the acoustic USBL self-localization is effective, and it has the potential to improve the overall vehicle navigation capabilities.

Thesaurus: AUV teams for archaeological search. Field results on acoustic communication and localization with the Typhoon

The Thesaurus project, funded by the Tuscany Region, had among its goals the development of technologies and methodologies for archaeological search with Autonomous Underwater Vehicles working as a team in exploration missions. This has led to the design and realization of a new AUV class, the Typhoon, on the basis of the archaeological requirements, and of an appropriate acoustic simultaneous communication and localization scheme. The paper describes the project background, the technical characteristics of the Typhoon AUVs, and the field results in acoustic localization as obtained in the CommsNet13 cruise, led by the NATO CMRE (Centre for Maritime Research and Experimentation), to which the Thesaurus project teams of the University of Pisa and Florence took part. In particular, the fields result reports the performance of acoustic localization through on-board USBL communicating with fixed modems placed in initially unknown locations.

Fusing acoustic ranges and inertial measurements in AUV navigation: The Typhoon AUV at CommsNet13 sea trial

The paper presents some experimental results of autonomous underwater navigation, based on the fusion of acoustic and inertial measurements. The work is in the framework of the Thesaurus project, funded by the Tuscany Region, aiming at developing techniques for systematic exploration of marine areas of archaeological interest through a team of Autonomous Underwater Vehicles (AUVs). The test was carried out with one Typhoon vehicle, a 300m depth rated AUV with acoustic communication capabilities, during the CommsNet13 experiment, organized and scientifically coordinated by the NATO S&T Org. Ctr. for Maritime Research and Experimentation (CMRE, formerly NURC), with the participation of several research institutions. The fusion algorithm is formally casted into an optimal stochastic filtering problem, where the rough estimation of the vehicle position, velocity and attitude, are refined by using the depth measurement, the relative measurements available on the acoustic channel and the vehicle surge speed.

Development of Nemo remotely operated underwater vehicle for the inspection of the Costa Concordia wreck

Remotely operated underwater vehicles are mobile robots increasingly used in underwater applications; these devices are widely used and suitable for different scenarios, for example, for patrolling and monitoring and also for underwater interventions. In the last 30 years, the remotely operated underwater vehicles have become more and more advanced; at the same rate with the progressive technological development of these vehicles, the market of the specialized component industry is fast-increasing. Generally speaking, a remotely operated underwater vehicle allows to investigate areas inaccessible or too dangerous for human beings. The use of remotely operated underwater vehicles during a mission, with the related implication of support ships and specialized pilots, or the involvement of professional divers, is usually associated with high costs. The reduction of these costs is an important topic in the underwater robotic field and the easy piloting of these mobile robots is a crucial aspect in their development. This article describes Nemo remotely operated underwater vehicle, a remotely operated underwater vehicle prototype specifically designed for the exploration of the Costa Concordia wreck, Isola del Giglio, Italy. Nemo remotely operated underwater vehicle can be considered a mini-remotely operated underwater vehicle, that is, a remotely operated underwater vehicle with weight less than 25 kg and easily deployable from a small boat. This article describes the main characteristics of the vehicle: the onboard control logic and on the development of a user-friendly graphical user interface for underwater navigation able to take advantage of its high maneuverability. It is worth to note that the developed graphical user interface enables to operate the vehicle even to inexperienced pilots. Preliminary experimental data collected during navigation are provided.

An anti-capsize strategy for industrial vehicles: Preliminary testing on a scaled AGV

The stability of industrial vehicles, such as forklifts and lifters, is very important from a safety point of view: these vehicles are subjected to variable loading conditions and their design is often optimized to privilege handling in narrow spaces, instead of stability. To study in deep the problem of vehicle capsize prevention, the authors developed a scaled AGV (Automated Guided Vehicle). It is a three wheeled differential drive mobile robot, with front motorized wheels, driven by speed-controlled drivers. The position of the wheels and the loads can be easily modified to simulate different vehicle configurations and operating scenarios. The vehicle is controlled with a Texas Instrument C2000 controller, programmable through Matlab-Simulink Embedded Coder™. In addition, the forces exchanged among the wheels and the ground are monitored using low cost load cells, with miniaturized amplification stages. MEMS three-axial accelerometers and gyros are installed in order to detect inertial loads and to estimate the vehicle pose and, through a proper filtering, the ground slope. The implemented strategy is able to identify the loading conditions of the vehicle by means of a dedicated algorithm: this algorithm evaluates the position of the center of mass from static measurements that are further refined when the vehicle is in motion with an adaptive filtering based on the fusion of both static and dynamic measurements. Once the vehicle is in motion, the controller, to prevent the vehicle capsize, is able to limit its forward speed without changing the geometry of the assigned trajectory. In this work, the results of preliminary testing activities are shown, demonstrating the validity and the effectiveness of the proposed approach.

Fast prototyping of a scaled AGV for the testing of stability control for industrial vehicles

Mechatronics is a multidisciplinary and application oriented science. Fast prototyping of a complete, scaled mechatronic system is very useful both for research and teaching activities. This work describes the development of a scaled AGV, using fast prototyping techniques, both for the design of the mechanical components and the development of the vehicle control system. The scaled AGV is used as a scaled demonstrator to verify the feasibility of an anti-capsize controller. Capsize is a typical problem that have to be avoided on industrial vehicles, forklifts and moving lifter where heavy and partially unknown loads have to be moved using vehicles with a design that privilege manoeuvrability and small costs against stability. The AGV is a three wheeled differential drive mobile robot, with front motorized wheels, driven by speed-controlled drivers. The vehicle is controlled through a Texas Instrument C2000 controller, programmable by using Matlab-Simulink Embedded Coder™. Forces exchanged between the wheels and the ground are monitored using low cost load cells. MEMS three-axial accelerometers and gyros are used to detect inertial loads and to estimate the vehicle pose and, through a proper filtering, the ground slope. The implemented strategy is able to identify the loading conditions of the vehicle by means of a dedicated algorithm. Once the vehicle is in motion, the controller, to prevent the vehicle capsize, is able to limit its forward speed without changing the geometry of the assigned trajectory. In this work, the results of preliminary testing activities are shown, in order to demonstrate the validity and the effectiveness of the proposed approach.