Page 117 - Concise Encyclopedia of Robotics

Eye-In-Hand System
Expert systems can be used in computers to help people do research,
make decisions, and generate forecasts.A good example is a program that
assists a physician in making a diagnosis.The computer asks questions,and
arrives at a conclusion based on the answers given by the patient and doctor.
One of the biggest advantages of expert systems is the fact that repro-
gramming is easy. As the environment changes, the robot can be taught
new rules, and supplied with new facts.
EXTENSIBILITY
Extensibility, also called expandability, refers to the ease with which a robotic
system can be modified to perform a greater number, or a greater variety,
of tasks than those allowed for in its original design.
The extensibility of a robotic system depends on various factors, includ-
ing the nature of the hardware, the controller memory, the controller
data storage space, and the controller processing speed. Extensibility is
enhanced by the use of modular construction and standardized parts.
EXTRAPOLATION
When data are available within a certain range, an estimate of values out-
side that range can be made by a technique called extrapolation. This can be
educated guessing, but it can also be done using a computer. The more
sophisticated the computer software,the more accurately it can extrapolate.
An example of extrapolation is the forecast path of a hurricane as it
approaches a coastline. Knowing its path up to the present moment, a
range of possible future paths is developed by the computer. Factors that
can be programmed into the computer to help it make an accurate extrap-
olation include:
• Paths of hurricanes in past years that approached in a similar way
• Steering currents in the upper atmosphere
• Weather conditions in the general path of the storm
The farther out (into the future) an extrapolation is made,the less accurate
the results. While a weather computer might do a good job of predicting
a hurricane path 24 h in advance, no machine yet devised can tell exactly
where the storm will be in a week. Compare INTERPOLATION.
EYE-IN-HAND SYSTEM
For a robot gripper to find its way, a camera can be placed in the gripper
mechanism. The camera must be equipped for work at close range, from
about 1 m down to a few millimeters. The positioning error must be as
small as possible, preferably less than 0.5 mm. To be sure that the camera

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