A Dynamic Manipulation Strategy for an Intervention: Autonomous Underwater Vehicle

Ridolfi A Conti R,Costanzi R Fanelli F

doi:10.4172/2168-9695.1000132

Abstract

This paper presents the modelling and the control architecture of an Autonomous Underwater Vehicle for Intervention (I-AUV). Autonomous underwater manipulation with free-floating base is still an open topic of research, far from reaching an industrial product. Dynamic manipulation tasks, where relevant vehicle velocities are required during manipulation, over an additional challenge. In this paper, the accurate modelling of an I-AUV is described, not neglecting the interaction with the fluid. A grasp planning strategy is proposed and integrated in the control of the whole system. The performances of the I-AUV have been analysed by means of simulations of a dynamic manipulation task.

Highlights

The development of the Autonomous Underwater Vehicles (AUVs) has a great importance in modern society, because of their fundamental role in the military field, in underwater explorations and in the industrial field (e.g. Oil and Gas applications)
To which is added the presence of a long communication and power supply cable, restricting the possible movements of the vehicle and of its arm, have recently brought some researchers to consider what appears as the AUV natural evolution, i.e. the autonomous underwater vehicles equipped with manipulator arms, the I-AUVs [4,5]
As soon as the cylinder enters the field of view of a camera mounted on the palm of the gripper, the reference trajectory is changed so as to align the camera focal axis with the line connecting the palm of the gripper to the position of the center of mass of the object; this way, the cylinder is kept inside the field of view of the camera all the time; c

Summary

Introduction

The development of the Autonomous Underwater Vehicles (AUVs) has a great importance in modern society, because of their fundamental role in the military field, in underwater explorations (e.g. archaeological field) and in the industrial field (e.g. Oil and Gas applications). Before analysing in detail the terms that compose the aforementioned virtual force, it is important to notice that, generally speaking, during the execution of the algorithm the candidates do not lie on the same plane; referring to Figure 21, for the computation of fvi their projections (indicated by the apex p) on the plane Π which minimize the distance from all the contact points are considered. During the execution the contact points are kept at a fixed distance from the surface of the object, as a safety measure aimed at avoiding undesirable contacts when the output of the algorithm is used as the reference value for the positional controller of the gripper’s fingers This distance is reduced to zero at the last iteration, once the final contact points have been chosen. It is advised to use, together with the proposed ones, an algorithm that computes the optimal contact force for each finger on the basis of the object properties and the required task

Simulation Results

Results

Conclusions and Further Developments