Page 159 - Concise Encyclopedia of Robotics

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Temperature, Degrees Celsius
Hysteresis loop

All servomechanisms employ feedback of some kind.There must always
be some hysteresis built into the feedback response. This hysteresis is
often a natural result of the environment; for example, it takes some time
for the temperature in a house to warm up and cool down by 3°C as
depicted in the illustration. However, in a tiny temperature-regulated
chamber intended to ensure the stable operation of the controller in a robot
working in an extreme environment such as outer space, the hysteresis
must be incorporated into the electronic design of the feedback circuit or
thermostat. Otherwise, overreactions can be so severe that the system
constantly cycles between states.
See also SERVOMECHANISM.

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