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Fig. 10.41 An early model of ALVIN's portable manipulator controls (WHOI) 



arm provides too much backscatter and a 

 dark arm cannot be seen. 

 — Both manipulator operator and vehicle 

 operator should have the same view if 

 submersible movements and manipula- 

 tor operations are to interact. 

 — Common machine shop practices, e.g., 

 self-alignment, self-tool feed, torque-lim- 

 iting clutches and step drills for pilot 

 holes, could be applied profitably to ma- 

 nipulator tool design. 

 There are indeed many improvements 

 which submersible manipulators must pro- 

 vide if they are to realize anywhere near the 

 capability of the diver. But the onus is not on 

 submersible operators alone. The designer of 

 underwater hardware to be worked on is one 

 of the major obstacles standing in the way of 

 submersible performance. Look closely at 

 Figure 10.43, where the diver is making a 



midwater electrical connection in seconds 

 that would take a submersible minutes and 

 perhaps hours to complete. In addition to the 

 connector, there are bolts and nuts that also 

 might need disconnecting, a relatively easy 

 task for the diver. Why are they easy tasks? 

 Quite simply because they were designed to 

 be performed by the human arm and hand 

 with assistance from human hand-held tools. 

 Herein lies the crux of the problem: If the 

 ends of the nuts or the connector had been 

 designed for grasping by a hook, parallel 

 jaws or Dorrance-type claw, the task of the 

 submersible would be eased immensely. No 

 doubt, equaling the human "manipulator" is 

 a difficult, if not impossible, task, but the 

 human can only go so deep in the ocean. 

 Hardware knows no depth limit, and if the 

 hardware designers anticipate replacement 

 of parts or installation of devices subsequent 



532 



