An Advanced Electromechanical elemanipulation System to Increase the Effectiveness of Undersea Intervention
Authors: Terribile A. , Schiavon R. , Lanza R. 
Published: October 2008

This paper provides a description of an innovative underwater telemanipulation system with electromechanical joints and force reflection control. Such a system is the prototype of a new product for remote operations in hostile environment, primarily for undersea applications. It is the upgrading to operational level of a previous laboratory prototype. It is a manually controlled telemanipulation system with capability to interact with objects in the environment to execute Inspection Maintenance Repair (IMR) tasks. It is also compatible with interfacing to a supervisory control system for telerobotic applications.

Introduction

Remote intervention in hostile environments is expected to be an evolving market in the near future. In the offshore industry, Inspection Maintenance and Repair (IMR) of production platforms is already performed by Remotely Operated Vehicles (ROV) equipped with hydraulic manipulators arms. There is also a growing trend towards the robotization of subsea production facilities: wellhead trees and manifold, now being installed at ever increasing operating depths. One of the factors hampering the diffusion of robotics in the subsea industry is represented by the poor performances of the hydraulic arms currently available on the market. Hydraulic actuation allows to achieve a high payload capability to weight ratio: in the order of two for existing commercial arms. On the other hand, hydraulic manipulators are affected by several drawbacks. Intended for master/slave operations, they feature poor positioning accuracy and are not suited for implementation of fine control of the interaction force with theenvironment during contact tasks.

Commercial ROVs are hydraulically powered and the power supply for the manipulation system is available at no cost. Deep water ROVs now being investigated for future applications will probably be electrically powered to minimize weight and size. An electrical manipulator would be appealing in this perspective.

An underwater telemanipulation system could also find a potential market niche in the nuclear industry, for applications in shallow water, inside pools. Dismantling and decommissioning of power plants and disposal of wastematerial represent the main applications.

Such considerations have motivated the development of a new manipulation system. The distinctive feature of thissystem stems from the combination of the following main attributes: underwater, electromechanical, substantial payload toweight ratio, with force control and in general suited for robotics. As far as it is known, there are no other telemanipulation systems like this in the world. A first development phase, supported by national funding sources, has been completed with the achievement of a laboratory prototype. A follow-on project has led to the upgrading to an operational level of the existing prototype.

After providing a description of the main design features of the operational prototype, this paper presents the results of thefirst laboratory tests executed in air. In water tests, inside a pool, are also planned. A summary of the system dimensions, specifications and operating modes is finally provided. Final conclusions outline the foreseen future work.