Page 110 - Concise Encyclopedia of Robotics

End Effector
changes are made. The machine is tested again, and the problems noted.
Another drawing-board round follows. This process is repeated until the
machine works the way the engineer (or the customer) wants.
END EFFECTOR
An end effector is a device or tool connected to the end of a robot arm. The
nature of the end effects depends on the intended task.
If a robot is designed to set the table for supper, “hands,” more often
called robot grippers, can be attached to the ends of the robot arms. In an
assembly-line robot designed to insert screws into cabinets, a rotating-
shaft device and screwdriver head can be attached at the end of the arm.
Such a rotating shaft might also be fitted with a bit for drilling holes, or
an emery disk for sanding wood.
A given type of robot arm can usually accommodate only certain kinds
of end effectors. One cannot take a table-setting robot, simply replace
one of its grippers with a screwdriver, and then expect it to tighten the
screws on the hinges of kitchen cabinets. Such a task change requires a
change in the programming of the robot controller, so it operates in
“handyrobot mode” rather than in “waitrobot mode.” One must also
change the hardware in the robot arm to operate a rotating end effector
rather than a gripper.
See also ROBOT ARM and ROBOT GRIPPER.
ENTITIZATION
Entitization, also called objectization, is an expression of the ease with which
a robot can differentiate among objects in its work environment. It is an
indication of the effectiveness of object recognition, and can be defined in
qualitative or quantitative terms.
Qualitative expressions of entitization are adjectives (such as “good,”
“fair,” or “poor”). Quantitative entitization is determined on the basis of
the proportion of correct identifications in a large number of tests in a
practical scenario. For example, if a robot correctly identifies an object
997 out of 1000 times, its entitization is 99.7 percent accurate.
See also OBJECT RECOGNITION.
ENVELOPE
See WORK ENVELOPE.
EPIPOLAR NAVIGATION
Epipolar navigation is a means by which a machine can locate objects in
three-dimensional (3-D) space. It can also navigate, and figure out its
own position and path. Epipolar navigation works by evaluating the way

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