What are the types of Control Systems?


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What are the types of Control Systems?

A control system can be functioned electrically, mechanically, pressure by fluid (gas or liquid), or it can be combination of these ways. Control systems are used to arrange and manage components in a way that the required condition or output is obtained. A control system is a system, which controls other systems.

There are two types of control systems depending upon the configuration of systems:

  1. Open loop control systems

  2. Closed loop control systems

Open loop control systems

Open loop control system are systems with no feedback which means those systems in which the output has no effect on the control action.

An open-loop control system takes input under the consideration and doesn’t react on the feedback to obtain the output. This is why it is also called a non-feedback control system.
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• Input: the excitation applied to the system from an external sources to attain an output is called input signal.

• Control system: It is an arrangement or a combination of various physical components also called the sub systems connected in such a manner so as to attain an output.

• Control action: it is quantity that is responsible for activating the system

• Output: the actual system attain from the system is called output signal.

Practical Examples of Open Loop Control System

  1. Electric Hand Drier - Hot air (output) comes out as long as you keep your hand under the machine, irrespective of how much your hand is dried.

  2. Automatic Washing Machine - This machine runs according to the pre-set time irrespective of washing is completed or not.

  3. Bread Toaster - This machine runs as per adjusted time irrespective of toasting is completed or not.

  4. Automatic Tea/Coffee Maker - These machines also function for pre adjusted time only.

  5. Timer Based Clothes Drier - This machine dries wet clothes for pre-adjusted time, it does not matter how much the clothes are dried.

  6. Light Switch - Lamps glow whenever light switch is on irrespective of light is required or not.

  7. Volume on Stereo System - Volume is adjusted manually irrespective of output volume level.

Closed loop control systems

A closed loop system is also referred as a feedback control system. A system in which the control action is dependent on the output is called a closed loop system. In closed loop system the output is constantly monitored and adjusted to the required value by the system.

The output signal is fed back and compared with the reference input. Depending upon the difference between the output signal and reference input, corrective actions are taken by the controller to adjust the output. For example air conditioning unit.

Practical Examples of Closed Loop Control System

  1. Automatic Electric Iron - Heating elements are controlled by output temperature of the iron.

  2. Servo Voltage Stabilizer - Voltage controller operates depending upon output voltage of the system.

  3. Water Level Controller - Input water is controlled by water level of the reservoir.

  4. Missile Launched and Auto Tracked by Radar - The direction of missile is controlled by comparing the target and position of the missile.

  5. An Air Conditioner - An air conditioner functions depending upon the temperature of the room.

  6. Cooling System in Car - It operates depending upon the temperature which it controls.