1,523 research outputs found
Autonomous Underwater Intervention
No full textPurpose of Review
There is a growing interest and literature on autonomous underwater intervention systems. The purpose of this paper is to provide a review of the recent literature on control systems for autonomous or semi-autonomous underwater manipulation activities, classifying the results based on the type of task executed and the testing environment (simulation, pool, or sea).
Recent Findings
Amongst underwater intervention tasks, the grasping of objects lying on the seafloor is one of the most studied topics. Several results are given both in pool and sea environments. The perception of such objects might still need further improvements before the system can be considered robust enough. Manipulation of valves while docked has been demonstrated in sea environments. Results on floating valve manipulation or floating inspection through force regulation are still limited to pool environments. Finally, cooperative transportation by multiple agents is still limited to numerical simulation results only.
Summary
A review of the state of the art of underwater manipulation is presented. First an introduction is given, recalling the fundamental milestones reached in the past on this topic. Then, recent findings on control systems for (semi-)autonomous intervention are presented, subdivided in grasping, valve manipulation and force regulation tasks and cooperative manipulation. Some unconventional systems are also presented
A Novel Practical Technique to Integrate Inequality Control Objectives and Task Transitions in Priority Based Control
No full textThe task priority based control is a formalism which allows to create complex control laws with nice invariance properties, i.e. lower priority tasks do not affect the execution of higher priority ones. However, the classical task priority framework (Siciliano and Slotine) lacked the ability of enabling and disabling tasks without causing discontinuities. Furthermore, tasks corresponding to inequality control objectives could not be efficiently represented within that framework. In this paper we present a novel technique to integrate both the activation and deactivation of tasks and the inequality control objectives in the priority based control. The technique, called iCAT (inequality control objectives, activations and transitions) task priority framework, exploits novel regularization methods to activate and deactivate any row of a given task in a prioritized hierarchy without incurring in practical discontinuities, while maintaining as much as possible the invariance properties of the other active tasks. Finally, as opposed to other techniques, the proposed approach has a linear cost in the number of tasks. Simulations, experimental results and a time analysis are presented to support the proposed technique
Manipulation and Transportation With Cooperative Underwater Vehicle Manipulator Systems
No full textAutonomous underwater manipulation has been a topic of interest since the early 1990s. In the past few years, several milestone projects such as SAUVIM and TRIDENT have demonstrated autonomy capabilities for a single underwater vehicle manipulator system (UVMS) in performing simple manipulation tasks, e.g., the recovery of an object from the seafloor. The Italian funded MARIS project aims to extend some of these results to multiple UVMSs performing a cooperative transportation task of a long object such as a pipe. This paper presents the results achieved in developing a unifying architecture for the control of both individually and cooperatively operating UVMSs which explicitly makes use of a limited amount of information exchange between the agents, which is needed due to the severe bandwidth limitations of the underwater acoustic communications. A complete execution of the reference transportation mission is presented to support the proposed distributed algorithm. Furthermore, hydrodynamic simulations of the cooperative transportation phase are presented and an analysis of the achievable performances as different communication schemes are employed is given
A three-layered architecture for real time path planning and obstacle avoidance for surveillance USVs operating in harbour fields
No full textUnderwater vehicle manipulator systems: Control methodologies for inspection and maintenance tasks
No full textThis paper presents the control framework under development within the DexROV Horizon 2020 project, for the execution of maintenance and inspection tasks by a semi-autonomous ROV. The work exploits a task priority based kinematic inversion developed by the authors, extending it to encompass also a force regulation task. A way to manage transitions between the different DexROV missions is also given. The paper presents some simulation results to support the proposed control architecture
Underwater communication requirements in coordinated autonomous manipulation: The MARIS project
No full textThis paper addresses the communication requirements needed within the MARIS project, which involves several Italian institutions. The goal of the MARIS project is to develop technologies for autonomous underwater interventions, in particular to enable two floating manipulators in executing joint grasping and transportation activities. In this context, communication issues are mainly related to the information exchange needed by the cooperation algorithms during all the phases of the mission, in particular in the coordinated transportation. Simulation results show the expected performances of the cooperative algorithm as the communication rate changes. Based on these results, a strategy to meet the requirements imposed by the cooperation and to achieve the mission objective with the available devices is presented
RT^2: A Real-Time Ray-Tracing method for acoustic distance evaluations among cooperating AUVs
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