Open Loop System

Open loop systems are the ones in which the variable to control the system is not the output produced by it. In these systems, the output is calculated using the input variables which are based on the open loop transfer function of the system. They are easy to use and have simple functioning.

A control system is a group of interconnected electronic devices where each system has its own input and output relation for controlling the output of another connected system. There are two types of control systems.

  1. Open loop system
  2. Closed loop system
Open Loop System block diagram
Open Loop System block diagram

Open loop system is also known as non-feedback system because here output has no effect or influence on the input signal’s action. So, in this system the output is not measured at all. That’s why open loop system follow the input command no matter what the output result is you can set your point on the basis of input; as output has no effect.

It is referred to as open loop feedback system because here the output is not being used as the control variable; this type of systems does not depend on their output.

The output is not fed-back to the system and the system contains no feedback loop that’s why they are also referred to as non-feedback system.

Components of an open loop system

  • Controller which can be a timer
  • Processor
  • Input unit
  • Output unit
  • Heating elements

Examples of open loop system

There are end numbers of applications of open loop systems in our day to day life. We all have used the devices and appliances which work on this simple and amazing system function. The best thing about using this system is the cost effectiveness.  

Some of the examples of open loop system which we all have heard of are mentioned below:

  • Clothes drier
  • Electric bulb
  • Automatic washing machine
  • Bread toaster (time based)
  • Electric hand drier
  • Door lock systems
  • Servo motors
  • Remote control of TV
  • Inkjet printers
  • Word processor
  • Controlling the volume of the audio systems
  • Water faucet
  • Mobile phones

Working of a Clothes Drier Machine

Electrical Cloth Dryer - Open Loop System
Electrical Cloth Dryer – Open Loop System

The concept of open loop system is used in automatic clothes drier machine because it does not depend on the output that is it will stop according to the set time, no matter what the condition of the cloth is.

For an automatic washing direr to work and dry the clothes. We prefix the timing which is needed by our clothes to dry off. Suppose 20 minutes is the time duration we have set, and then the machine will automatically stop as soon as it completes 20 minutes. It will not keep rotating if the clothes are not dry because it works on the concept of open loop system where the output has no effect on the input.

The clothes drier machine has basically three main units that are

  1. Timer
  2. Heating elements
  3. Clothes

As, it works on the non-feedback system it doesn’t care about the feedback of the clothes. It will stop working as per its pre-set time, not considering the condition of the clothes (that whether they are still wet or dried up).

Benefits of using an open loop system

  • They are not expensive rather they are cheaper than other control systems.
  • They are convenient to use.
  • There functioning is simple.
  • And, they are relatively easy to maintain as their maintenance charges aren’t much.

Also see Automatic Emergency Light

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