Introduction to open and closed loop

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When the output quantity of the system is controlled by varying the input quantity, then the system is known as a control system or controlled system. Control systems play a significant role in bringing advancement to modern technology. As a result, almost all of our day-to-day lives are affected by the control system. An air conditioner, robotics, industrial processes, an automatic iron or geezer, etc. are examples of the control system.

Robotic Arm

The Control system is a vital and integral part of numerous applications around us. In control systems, we attempt to model complex physical systems using a series of mathematical tools.  One such commonly used technique is the block diagram representation of a system. In this method, the physical components of the corresponding systems are modeled with the aid of representative blocks connected orderly. Apart from this, various mathematical tools such as the Laplace Transform is used to analyze the response, stability, and other parameters of the systems.


Control systems are used to improve manufacture, efficiency, and protection in many areas, including:

  • Environmental control
  • Water treatment plants
  • Sewage treatment plants
  • Agriculture
  • Nuclear power plants
  • Metal and mines
  • Pharmaceutical manufacturing
  • Food and food processing
  • Chemical plants

Types of Control System

Based on the feedback of the output, the control system is divided into two types:

  • Open-loop control system
  • Closed-loop control system

Open Loop Control System

An open-loop control system is one in which the control action is independent of the output.

Closed-Loop Control System

A closed-loop control system is one in which the control action is somehow dependent on the output.

In upcoming lessons, we will see how we can use MATLAB & Simulink to build a control system model and analyze its response. In addition to the standard response, we will also use custom input signals and then analyze the system for these signals.

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