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INTRODUCTION
Sensor is a device that detects or senses the value or changes
of value of the variable being measured. The term sensor some
times is used instead of the term detector, primary element or
Transducer.
The fusion of information from sensors with different physical
characteristics, such as light, sound, etc enhances the
understanding of our surroundings and provide the basis for
planning,decision making, and control of autonomous and intelligent
machines.
A sensor is a device that responds to some external stimuli
and then provides some useful output. With the concept of input and
output, one can begin to understand how sensors play a critical role
in both closed and open loops.
One problem is that sensors have not been specified. In other
words they tend to respond variety of stimuli applied on it without
being able to differentiate one from another. Neverthless, sensors
and sensor technology are necessary ingredients in any control type
application. Without the feedback from the environment that sensors
provide, the system has no data or reference points, and thus no
way of understanding what is right or wrong g with its various
elements.
Sensors are so important in automated manufacturing
particularly in robotics. Automated manufacturing is essentially the
procedure of remo0ving human element as possible from the
manufacturing process. Sensors in the condition measurement
category sense various types of inputs, condition, or properties to
help monitor and predict the performance of a machine or system.