Design of an Articulated, 1-Atm Undersea Suit

Abstract

HE development of a wide spectrum of devices and systems capable of functioning effectively at great depths is now being considered. Included is the 1-atm, articulated, pressure-resistant suit which will allow a diver to remain at normal atmospheric pressure while working under high hydrostatic pressure. The suit, moreover, can be effectively insulated and equipped with a self-contained life support system. Based on the experience gained in the development of pressure-protective suit systems for use in both space and space atmospheres, the Space Sciences Laboratories of Litton Industries established that the basic requirements for a protective suit system involved: 1) safety, 2) mobility, and 3) comfort. From an engineering point of view, mobility is the most difficult requirement and is primarily considered here. The human body contains bones, jointed by articulations that allow rotations and deflections, which are shaftlike and hingelike respectively. Complex motions allowed by ball-andsocket joints (shoulder, hip) can be resolved into simple motions of both types. The technical success of a rigid, articulated suit requires joints that can move like the body articulations with minimum friction and volume variation. The number, position, and orientation of the articulations must correspond quite closely to corresponding human anatomical articulations. The degrees of freedom found necessary for adequate mobility require 13 different mechanical articulations. Nine are hingelike, two are rotational, and the remaining two can be mechanized in different ways since the complex anatomical motions are resolved into rotations about reference axes that lie at inaccessible points inside the body (shoulder, hip). In Litton suit designs, both for space and underwater, hinge-like or flexural motions are permitted by constantvolume convolute joint systems and the rotational motions by rotary seals. The proper combination of the two allows adjusting the joint systems to conform to the human anatomy and to place the geometrical axis of the structure in coincidence with the anatomical axis of the articulation. Technical problems in adaptation of these joint concepts from space suit to the diving suit are severe, primarily because the specific pressure difference is 3.7 to 5 psi in the former case and 270 psi in the latter.