Javatpoint Logo
Javatpoint Logo

Control Systems Introduction

A Control System is a system in which the output is controlled by varying the input. The first control system device was James Watt's Flyball governor, which was invented in 1767. The aim of inventing Flyball governor was to keep the speed of the engine constant by regulating the supply of the steam to the engine.

In a control system, the behavior of the system is described by the differential equations. The differential equations can be either ordinary differential equations or the difference equations.


control systems Introduction

There are two types of control system:

  1. Open loop control system.
  2. Closed loop control system.

Open loop control system

An open-loop control system is a system in which the control action is independent of the desired output signal. In this system, the output signal is not compared with the input signal which means there is no feedback signal in this system. The open-loop control system is also known as a non-feedback control system or control system without feedback.


control systems Introduction

Examples

  1. Automatic washing machine- In this system, the operating time is set manually. After the completion of the set time, the machine stops whether the desired cleanness is obtained or not because there is no feedback signal which the machine can sense.
  2. Immersion rod- In this system, the rod heats up the water but how much hot water is required that cannot be sensed by the rod.

Advantages of an open-loop control system

  1. Open loop systems are simple.
  2. These are economical.
  3. Less maintenance is required and is not difficult.

Disadvantages of open loop control system

  1. Open loop systems are inaccurate.
  2. These systems are not reliable.
  3. These are slow.
  4. Optimization is not possible.

Closed loop control system

A closed loop control system is a system in which control action is dependent on the desired output. In this system, the output signal is compared with the reference input signal, and an error signal is produced then this error signal is fed to the controller to reduce the error to obtain the desired output.


control systems Introduction

Examples

  1. Automatic electric iron.
  2. Servo voltage stabilizer.
  3. An air conditioner.

Advantages of closed-loop systems

  1. These systems are more reliable.
  2. Closed-loop systems are faster.
  3. Many variables can be handled simultaneously.
  4. Optimization is possible.

Disadvantages of closed-loop systems

  1. Closed-loop systems are expensive.
  2. Maintenance is difficult.
  3. Installation is difficult for these systems.

Difference between an open-loop system and closed-loop system

S.No Open Loop system Closed Loop system
1 These are easier to build. These are difficult to build.
2 These systems are not reliable. These systems are reliable.
3 These systems are slow. These systems are faster.
4 These systems are generally more stable. These systems are less stable.
5 Optimization is not possible. Optimization is possible.
6 Examples - Hand dryer, washing machine. Servo voltage stabilizer, air conditioner.




Please Share

facebook twitter google plus pinterest

Learn Latest Tutorials