Hobbies And Interests
Physical Size
A 28-inch articulated manipulator isn't likely to be as strong as an 800-pound, 6-foot manipulator, but sometimes size matters more than strength. For example, a heavily articulated manipulator used in bomb disposal typically must access small spaces to remove explosives. Its undersea counterpart, fighting a runaway oil well, needs to be large enough to manipulate valves and move damaged piping.
Intended Use
Multiple levels of complexity occur when operating manipulators with more mass. A robot arm useful for bomb disposal on land is likely to be electrically controlled and powered. A robot underwater -- a remotely operated vehicle, or ROV -- will use electronic sensors. The controls used by the pilots are somewhat similar to those of a video game, but electronic controls on the surface direct hydraulic valves on the ROV to operate its manipulators.
Environment
The environment also may limit an articulated robot arm's use. The hull of USS Arizona -- one of the U.S. Navy ships sunk in the Japanese attack on Pearl Harbor on December 7, 1941 -- is a final resting place for 1,177 American sailors and Marines. The remotely operated vehicle sent into the interior of the ship in 2004 had to be small, with electric motors and an electrically controlled manipulator. To avoid damaging or exposing the grave site to potential hydraulic leaks from a larger unit, a small, electrically powered ROV performed interior inspections of the vessel.
The Platform
Inertia limits robotic arms, too. An articulated robot arm bolted to the floor of a factory can move anything within its capacity to lift or manipulate. The same robot arm, when attached to a foundation that weighs less than the object to be manipulated, will fail because the fragile foundation lacks sufficient mass.