PROBLEM 



Inspection of underwater objects such as underwater pipelines and struc- 

 tures can be made more cost-effective if the technology for using unmanned, 

 free-swimming (untethered) submersibles is developed. One major critical area 

 in the development of such vehicle systems is that of a manipulator capability 

 for implacement of sensors, positioning of imaging subsystems, and retrieval 

 of small objects in the water. A small, lightweight, energy-efficient manipu- 

 lator, which could be operated on an unmanned, free- swimming submersible, was 

 required to act as a testbed for advanced supervisory-control techniques. 



RESULTS 



A small, lightweight, electrically driven manipulator capable of handling 

 an 8-pound load in water was designed, developed, and tested in the labora- 

 tory. The unit was found to be quite satisfactory as a testbed for advanced 

 supervisory-controlled teleoperator techniques. The oil -filled, pressure- 

 compensated motor assembly design, incorporating potentiometer feedback and 

 harmonic drive gearing, represents one of the most compact underwater designs 

 of its kind in existence. The sleek exterior design, together with the 

 smooth, quiet operation of the entire manipulator configuration, are note- 

 worthy features. 



RECOMMENDATIONS 



Advanced techniques in manipulator control should be tested and evaluated 

 with this manipulator mounted on the NOSC/US Geological Survey EAVE WEST free- 

 swimming submersible testbed. 



