Controls - The Building Blocks to Automation

Written by Thomas Yoon

As man learns to make machines that no longer rely on animal or human power, he finds that he has to develop some means to manage and control them. Powerful machines let loosed by themselves will create havoc and destruction.

Control systems have been developed for machines or processes so as to reducerepparttar chances of failure and to providerepparttar 133417 required results.

Basically, there are open loop control systems and close loop control systems.

Open loop systems are those whererepparttar 133418 controller action is not related torepparttar 133419 final result. This means that there is no feedback torepparttar 133420 controller to adjustrepparttar 133421 control action. A simple example is when you fill up a tank using a garden hose. As long asrepparttar 133422 tap is opened,repparttar 133423 water will flow. The height ofrepparttar 133424 water inrepparttar 133425 tank will not makerepparttar 133426 tap close.

However, when you seerepparttar 133427 tank becoming full and decide to closerepparttar 133428 tap, you are addingrepparttar 133429 element of feedback torepparttar 133430 loop. It then becomes a closed loop. But it is a human controlled closed loop.

Closed loop systems use feedback fromrepparttar 133431 final result to adjustrepparttar 133432 control action accordingly.

But how would you like to stand in one position, watchrepparttar 133433 process going on and operate valves, or switches according to repparttar 133434 conditions you want? This is very tiring, isn't it?

Moreover, human beings are prone to fatigue, boredom, and misjudgment. Manual control works very well only ifrepparttar 133435 speed ofrepparttar 133436 response is very slow, andrepparttar 133437 result is not very critical or important. Human controlled systems can become very unreliable.

Transducers - The Remarkable Changers

Written by Thomas Yoon

Complex control systems all make use of signals that can be easily measured and altered remotely. Automatically operated machines or actuators need to be powered either by electrical motors, pneumatic or hydraulic cylinders.

The most common signals sent out from a transducer are electrical current or voltage and pneumatic pressure. These signals are easily translated by controllers. Visual measuring devices like liquid bulb thermometers are not able to be used in automatic control systems because there are no electrical or pneumatic signals.

However, when some other component is added to it to enable it to give a corresponding signal, thenrepparttar measuring unit becomes a transducer.

A transducer is a device to convert a signal (representing a physical quantity) of one form into a corresponding signal of another form, retainingrepparttar 133416 amplitude variations of energy being converted.

Just as an example, a microphone is a sound transducer (acoustic to electrical) and a loudspeaker is an electrical transducer (electrical to acoustic). A transducer may be an integral part ofrepparttar 133417 measuring unit, for example pressure to displacement in a Bourdon pressure gauge. It may also be a separate unit converter especially suitable to changerepparttar 133418 signal to a better form for remote transmission, e.g. displacement to electrical in a differential transformer.

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