A. Turetta - Academia.edu (original) (raw)

Papers by A. Turetta

ABSTRACT In the present work modular reconfigurable complex kinematic chains, characterized by th... more ABSTRACT In the present work modular reconfigurable complex kinematic chains, characterized by the presence of an embedded distributed control system will be considered. More specifically, every single joint of the structure is assumed to be equipped with a simple local processing unit for properly driving its motion. As a consequence, each joint and the associated link may be considered as a defective "1-dof only" separately controlled atomic manipulator, which is required to act in team with all the other joints, in order to accomplish a global common task specified in the operational space. In this context the paper proposes a computationally distributed kinematic inversion technique that, via the on-line application of a dynamic programming technique (based on a moderate data exchange among the processing units), allows the establishment of a global self-organizing behavior; thus allowing to execute the task by solely exploiting the control capabilities of each local processing unit, while not requiring any centralized knowledge about the overall structure geometry and kinematics.

ABSTRACT The paper deals with the problem of underwater localization for Autonomous Underwater Ve... more ABSTRACT The paper deals with the problem of underwater localization for Autonomous Underwater Vehicles (AUVs) by using a set of acoustic transponders located in known fixed positions. More specifically, the work proposes an effective technique for enabling an AUV to on-line estimate its 3D position, by only employing the measurements of the Time-of-Flights (ToFs) of the signals exchanged with the transponders, without any a-priori information on the Speed of Sound (SoS) of the considered water area. The value of SoS is indeed considered as an additional unknown parameter within the estimation procedure. For any set of received ToFs, a cost function (dependent on the AUV coordinates and the SoS value) is defined and minimized via a standard gradient-descent technique. The optimization process exhibits very good properties in terms of speed of convergence, thanks to the simple structure of the considered cost function. The algorithm has been first tested in a simulated environment and then experimentally validated on an eFOLAGA AUV interrogating four Hydroid transponders.

OCEANS'10 IEEE SYDNEY, 2010

OCEANS'10 IEEE SYDNEY, 2010

Abstract—The paper deals with the problem of distributed acoustic localization of teams of Autono... more Abstract—The paper deals with the problem of distributed acoustic localization of teams of Autonomous Underwater Vehi-cles (AUVs) and proposes a novel algorithm, Real-Time Ray-Tracing (RT2), for evaluating the distance between any pair of AUVs in the team. The technique, ...

Distributed Autonomous Robotic Systems 8, 2009

Distributed Control and Coordination of Cooperative Mobile Manipulator Systems Enrico Simetti, Al... more Distributed Control and Coordination of Cooperative Mobile Manipulator Systems Enrico Simetti, Alessio Turetta, and Giuseppe Casalino Abstract. The paper deals with the problem of suitably coordinating the movement of two mobile manipulators in order to accomplish a ...

ABSTRACT This contribution addresses the problem of area coverage by a team of autonomous underwa... more ABSTRACT This contribution addresses the problem of area coverage by a team of autonomous underwater vehicle. The case addressed is the one in which the area map is not known in advance but adaptively estimated on-line by the vehicles themselves as they move along the area. The approach proposed is distributed, i.e., the vehicles in the team exchange information among themselves and autonomously take individual decisions on where to move next on the basis of the available information. Communication constraints among the vehicles, in terms of communication range and bandwidth, are explicitly taken into account by the algorithm, and can be dependent by the spatial position in the covered area. The paper proposes a series of algorithms for adaptive sampling with communication constraints in which the communication constraints are expressed in terms of connectivity of the graph of the vehicles. Depending on the structure of the graph (ordered serial graph, ordered tree graph, etc.) the algorithms take the structure of a distributed dynamic programming approach or of minimum spanning tree graph searching.

In this paper a towed semi-autonomous system for automatic tracking of underwater pipeline is pre... more In this paper a towed semi-autonomous system for automatic tracking of underwater pipeline is presented together with some experimental tests of the pipeline sensing apparatus. This paper focuses, in particular, on the development of a new guidance system based on the differential magnetometers which is the output measurements in the feedback loop.

International Conference on Robotics and Automation, 2005

The present work deals with manipulator arms characterized by the presence of an embedded distrib... more The present work deals with manipulator arms characterized by the presence of an embedded distributed control system. More specifically, every single joint is assumed to be equipped with a simple local processing unit for properly driving its motion. As a consequence, each joint and the associated link may be considered as a defective "1-dof only" separately controlled atomic manipulator, which

Abstract The current technological developments in au-tonomous underwater vehicles (AUVs) and und... more Abstract The current technological developments in au-tonomous underwater vehicles (AUVs) and underwater communication have nowadays allowed to push the original idea of autonomous ocean sampling network even further, with the possibility of using each ...

ABSTRACT This paper presents simulations and a sensitivity analysis of a Real-Time Ray-Tracing (R... more ABSTRACT This paper presents simulations and a sensitivity analysis of a Real-Time Ray-Tracing (RT2) technique for acoustic-based range evaluation. The RT2 is an algorithm that evaluates the range of an acoustic receiver from the emitter, while taking into account the anisotropy of the underwater medium, exploiting the knowledge of the depth information of both the emitter and the receiver, and the depth-dependent sound speed profile. This technique allows the vehicle itself to know its position, unlike COTS systems that are usually conceived for “tracking” the underwater devices. Moreover, the required hardware is only an acoustic modem, which is already necessary for communication, thus the algorithm can be easily implemented even on low-cost vehicles. The sensitivity analysis here presented shows that, even when the sound speed profile is not known exactly, the algorithm achieves a good precision when compared to straight ray propagation assumption, especially in the presence of the so called “acoustic channels”. Despite the presence of few outliers, and few limited zones when the algorithm performs worse than a straight ray assumption, in average the simulations shows an increase of one order of magnitude of precision.

... A. Caiti, G. Casalino, A. Turetta, R. Viviani Page 2. 2 ... A. Caiti, G. Casalino, A. Turetta... more ... A. Caiti, G. Casalino, A. Turetta, R. Viviani Page 2. 2 ... A. Caiti, G. Casalino, A. Turetta, R. Viviani Abstract—An algorithm for adaptive on-line planning of environmental exploration missions with a team of Autonomous Underwater Vehicles (AUVs) is proposed. ...

Ocean Engineering, 2009

... Multi-vehicle or multi-robot cooperation/coordination, not necessarily referred to underwater... more ... Multi-vehicle or multi-robot cooperation/coordination, not necessarily referred to underwater applications, is ... of the distributed dynamic programming, the simulative application of the algorithm shows that ... capabilities, that may be exploited in several inspection and patrolling tasks ...

ABSTRACT The need for actual autonomy in underwater robotic systems is rapidly increasing. Many c... more ABSTRACT The need for actual autonomy in underwater robotic systems is rapidly increasing. Many challenging issues derive from such a trend, one in all the requirement of coordinately controlling the motion of an underwater floating I-AUV endowing a robotic arm, to accomplish complex manipulation tasks. This work is aimed to present a strategy based on the prioritization of tasks of equality and inequality type, once combined with Dynamic Programming techniques, for coordinately controlling the motion of such I-AUV. A general algorithmic framework is developed and simulative results supporting its resulting effectiveness are presented.

ABSTRACT In the present work modular reconfigurable complex kinematic chains, characterized by th... more ABSTRACT In the present work modular reconfigurable complex kinematic chains, characterized by the presence of an embedded distributed control system will be considered. More specifically, every single joint of the structure is assumed to be equipped with a simple local processing unit for properly driving its motion. As a consequence, each joint and the associated link may be considered as a defective "1-dof only" separately controlled atomic manipulator, which is required to act in team with all the other joints, in order to accomplish a global common task specified in the operational space. In this context the paper proposes a computationally distributed kinematic inversion technique that, via the on-line application of a dynamic programming technique (based on a moderate data exchange among the processing units), allows the establishment of a global self-organizing behavior; thus allowing to execute the task by solely exploiting the control capabilities of each local processing unit, while not requiring any centralized knowledge about the overall structure geometry and kinematics.

ABSTRACT The paper deals with the problem of underwater localization for Autonomous Underwater Ve... more ABSTRACT The paper deals with the problem of underwater localization for Autonomous Underwater Vehicles (AUVs) by using a set of acoustic transponders located in known fixed positions. More specifically, the work proposes an effective technique for enabling an AUV to on-line estimate its 3D position, by only employing the measurements of the Time-of-Flights (ToFs) of the signals exchanged with the transponders, without any a-priori information on the Speed of Sound (SoS) of the considered water area. The value of SoS is indeed considered as an additional unknown parameter within the estimation procedure. For any set of received ToFs, a cost function (dependent on the AUV coordinates and the SoS value) is defined and minimized via a standard gradient-descent technique. The optimization process exhibits very good properties in terms of speed of convergence, thanks to the simple structure of the considered cost function. The algorithm has been first tested in a simulated environment and then experimentally validated on an eFOLAGA AUV interrogating four Hydroid transponders.

OCEANS'10 IEEE SYDNEY, 2010

OCEANS'10 IEEE SYDNEY, 2010

Abstract—The paper deals with the problem of distributed acoustic localization of teams of Autono... more Abstract—The paper deals with the problem of distributed acoustic localization of teams of Autonomous Underwater Vehi-cles (AUVs) and proposes a novel algorithm, Real-Time Ray-Tracing (RT2), for evaluating the distance between any pair of AUVs in the team. The technique, ...

Distributed Autonomous Robotic Systems 8, 2009

Distributed Control and Coordination of Cooperative Mobile Manipulator Systems Enrico Simetti, Al... more Distributed Control and Coordination of Cooperative Mobile Manipulator Systems Enrico Simetti, Alessio Turetta, and Giuseppe Casalino Abstract. The paper deals with the problem of suitably coordinating the movement of two mobile manipulators in order to accomplish a ...

ABSTRACT This contribution addresses the problem of area coverage by a team of autonomous underwa... more ABSTRACT This contribution addresses the problem of area coverage by a team of autonomous underwater vehicle. The case addressed is the one in which the area map is not known in advance but adaptively estimated on-line by the vehicles themselves as they move along the area. The approach proposed is distributed, i.e., the vehicles in the team exchange information among themselves and autonomously take individual decisions on where to move next on the basis of the available information. Communication constraints among the vehicles, in terms of communication range and bandwidth, are explicitly taken into account by the algorithm, and can be dependent by the spatial position in the covered area. The paper proposes a series of algorithms for adaptive sampling with communication constraints in which the communication constraints are expressed in terms of connectivity of the graph of the vehicles. Depending on the structure of the graph (ordered serial graph, ordered tree graph, etc.) the algorithms take the structure of a distributed dynamic programming approach or of minimum spanning tree graph searching.

In this paper a towed semi-autonomous system for automatic tracking of underwater pipeline is pre... more In this paper a towed semi-autonomous system for automatic tracking of underwater pipeline is presented together with some experimental tests of the pipeline sensing apparatus. This paper focuses, in particular, on the development of a new guidance system based on the differential magnetometers which is the output measurements in the feedback loop.

International Conference on Robotics and Automation, 2005

The present work deals with manipulator arms characterized by the presence of an embedded distrib... more The present work deals with manipulator arms characterized by the presence of an embedded distributed control system. More specifically, every single joint is assumed to be equipped with a simple local processing unit for properly driving its motion. As a consequence, each joint and the associated link may be considered as a defective "1-dof only" separately controlled atomic manipulator, which

Abstract The current technological developments in au-tonomous underwater vehicles (AUVs) and und... more Abstract The current technological developments in au-tonomous underwater vehicles (AUVs) and underwater communication have nowadays allowed to push the original idea of autonomous ocean sampling network even further, with the possibility of using each ...

ABSTRACT This paper presents simulations and a sensitivity analysis of a Real-Time Ray-Tracing (R... more ABSTRACT This paper presents simulations and a sensitivity analysis of a Real-Time Ray-Tracing (RT2) technique for acoustic-based range evaluation. The RT2 is an algorithm that evaluates the range of an acoustic receiver from the emitter, while taking into account the anisotropy of the underwater medium, exploiting the knowledge of the depth information of both the emitter and the receiver, and the depth-dependent sound speed profile. This technique allows the vehicle itself to know its position, unlike COTS systems that are usually conceived for “tracking” the underwater devices. Moreover, the required hardware is only an acoustic modem, which is already necessary for communication, thus the algorithm can be easily implemented even on low-cost vehicles. The sensitivity analysis here presented shows that, even when the sound speed profile is not known exactly, the algorithm achieves a good precision when compared to straight ray propagation assumption, especially in the presence of the so called “acoustic channels”. Despite the presence of few outliers, and few limited zones when the algorithm performs worse than a straight ray assumption, in average the simulations shows an increase of one order of magnitude of precision.

... A. Caiti, G. Casalino, A. Turetta, R. Viviani Page 2. 2 ... A. Caiti, G. Casalino, A. Turetta... more ... A. Caiti, G. Casalino, A. Turetta, R. Viviani Page 2. 2 ... A. Caiti, G. Casalino, A. Turetta, R. Viviani Abstract—An algorithm for adaptive on-line planning of environmental exploration missions with a team of Autonomous Underwater Vehicles (AUVs) is proposed. ...

Ocean Engineering, 2009

... Multi-vehicle or multi-robot cooperation/coordination, not necessarily referred to underwater... more ... Multi-vehicle or multi-robot cooperation/coordination, not necessarily referred to underwater applications, is ... of the distributed dynamic programming, the simulative application of the algorithm shows that ... capabilities, that may be exploited in several inspection and patrolling tasks ...

ABSTRACT The need for actual autonomy in underwater robotic systems is rapidly increasing. Many c... more ABSTRACT The need for actual autonomy in underwater robotic systems is rapidly increasing. Many challenging issues derive from such a trend, one in all the requirement of coordinately controlling the motion of an underwater floating I-AUV endowing a robotic arm, to accomplish complex manipulation tasks. This work is aimed to present a strategy based on the prioritization of tasks of equality and inequality type, once combined with Dynamic Programming techniques, for coordinately controlling the motion of such I-AUV. A general algorithmic framework is developed and simulative results supporting its resulting effectiveness are presented.