Use Of Manipulators In Underwater Work

ABSTRACT Submarine Development Group ONE has conducted numerous manipulator centered work tasks in ocean depths to 20,000 feet utilizing five different manned submersibles. Subjective conclusions based upon this experience acknowledge the importance of the manipulator in underwater work, but point toward the even greater importance of visibility and maneuvering and the need for integrating these elements to form effective work systems. INTRODUCTION In spite of the encumbrances he commonly bears, a trained and properly equipped diver is still the most effective work system in use today. What he lacks in brute strength is more than compensated for by his unique combination of dexterity, body maneuverability, and vision. However when conditions such as depth or support limitations preclude the use of divers, it is usually necessary to substitute a manned or unmanned submersible, thereby removing man at least one step from the work. At present, this is a giant step. Tasks that would be straightforward for a man ashore typically-become difficult for a diver underwater. But tasks that are straightforward for a diver can be virtually impossible for a submersible. This latter discrepancy can be directly attributed to the relatively undeveloped state of underwater teleoperator work systems that are in operation today. Progress is being made, however, as more is learned of the critical elements of work systems. One of the chief critical elements, or prime operatives, is the manipulator. More will be said about the importance of considering this element in relationship to other factors later. Normally, undersea manipulators are either electrically or hydraulically powered and range in size and complexity from small 2–3 function devices up to seven or even eight-function arms weighing several hundred pounds. Typically, these manipulators are either rate-controlled (fixed-rate functions individually switched on or off) or employ some kind of continuous position and force feedback (masterslave) for improved man-machine familiarity. It is not the purpose of this paper to explore the relative merits of various types of manipulator systems, but to present the results of experience gained with manipulators by Submarine Development Group ONE over the past eight years in a wide variety of work tasks. This experience and the conclusions to be drawn from it should be helpful toward the conception and design of future submersible work systems. Currently, there are five work submersibles, all manned, under cognizance of Commander Submarine Development Group ONE, San Diego, California. These are the bathyscaph TRIESTE II, the sister submersibles SEA CLIFF and TURTLE, and the submarine rescue vehicles MYSTIC and AVALON. Among them a myriad of jobs have been performed from Wake Island to the Azores to depths of 20,000 feet. Most of this work has been oriented toward recovery of objects or maintenance and repair of facilities.