TABLE 10.8 SUBMERSIBLE MANIPULATOR CHARACTERISTICS (Cont.) 



pressure-resistant suit, and the diver's arm 

 provides the movement. Wilson {ibid.) provides 

 a brief but informative treatment of man- 

 ipulator power (actuation) in regards to the 

 advantages and disadvantages of electro- 

 mechanical versus electro-hydraulic actuators 

 and Rockwell's table (Table 10.9) compares 

 both approaches. 



Design and Capabilities 



The design and capabilities of manipula- 

 tors followed no particular course to an ulti- 

 mate destination. Increased capabilities, 

 such as more degrees of freedom or greater 

 lifting and grasping power, were provided 

 only if they were required to perform a par- 

 ticular task. The manipulators on the Navy's 

 SEA CLIFF and TURTLE are indeed versa- 

 tile, but for many submersibles they are 

 unnecessary. For example, DS-4000's ma- 

 nipulator and claw may appear somewhat 

 inadequate compared to the aforementioned, 

 but for over 400 dives this arm provided all 

 that was necessary for the scientific re- 

 search of its users. So the question of such 



things as how many degrees of freedom, type 

 of claw and lifting capacity is really an- 

 swered by balancing the trade-offs. If the 

 dexterity of the human arm and hand is the 

 goal, then expense, complexity, weight and 

 extensive maintenance are some of the sacri- 

 fices — as well as a long wait, for this goal is a 

 long way off. In the interim, Figures 10.39 

 and 10.40 present representative contempo- 

 rary examples of manipulators; the charac- 

 teristics of each can be found in Table 10.8. A 

 brief discussion serves to introduce the capa- 

 bilities of each and describe the field at large 

 as well. 



SEA OTTEWs manipulator (Fig. 10.39a) is 

 really what Wilson termed a special machine. 

 It can only move up or down and relies on 

 the submersible to train it left or right or 

 move it forward. The hydraulic cylinder be- 

 tween it and the skid pushes it up or down by 

 virtue of a hand pump in the pressure hull. 

 The device was fabricated for attaching a lift 

 hook to a sunken tug boat. The lift hook was 

 held in the terminal end by a dowel. When it 

 was in place, the dowel was removed by 



525 



