14 Difference Between Open Loop And Closed Loop System (With Comparison Chart)

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A control system is a system of devices or set of devices that manages, commands, directs or regulates the behavior of other devices or systems to achieve desired results. There are two main types of control system. They include:

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

What Is Open Loop Control System?

An open loop system is a type of continuous control system in which the output has no influence or effect on the control action of the input signal. In other words, in an open-loop control system, the output is neither measured nor ‘’fed back’’ to the input for further consideration or comparison. Therefore, an open loop system is expected to follow its input command or set point regardless of the final result. These systems do not contain any feedback loop and thus are also referred to as non-feedback system.

An open-loop system has no knowledge of the output condition therefore cannot self-correct any errors it could make when the preset value drifts, even if this results in large deviations from the preset value. Also, open-loop systems are poorly equipped to handle disturbances or changes in the conditions which may reduce its ability to compete the desired task.

Examples of open loop system include:

  • Traffic lights controller
  • Water sprinkler
  • Stepper motors
  • Automatic washing machine

Characteristics Of Open Loop System

  1. An open loop control system acts completely on the basis of input and the output has no effect on the control action.
  2. The open loop system can also be referred to as the non-feedback system control system.
  3. An open loop system works on fixed operation conditions and there are no disturbances.
  4. Examples of open loop system include traffic lights controller, water sprinkler, Stepper motors and automatic washing machine.
  5. The accuracy of the closed loop system is comparatively less to that of closed-loop system.
  6. The output control system has a non-linear response.
  7. Open loop system is easy to design as there is no feedback.
  8. Error detector is not present in open loop system.
  9. Open loop control systems are mostly stable.
  10. An open loop system is an easy principle to implement as it requires less number of components to be constructed.
  11. Open loop systems require good calibration and lesser power rating.
  12. The open loop system gives a fast response.
  13. Open loop system is reliable.
  14. The open loop system is not optimized.

What Is Closed Loop Control System?

A closed-loop control system also referred to as feedback control system is a type of control system in which the controlling action shows dependency on the generated output of the system. In other words, in these systems, the output of the system controls the input applied to the system. The term closed-loop control always implies the use of a feedback control action in order to reduce any errors within the system and its ‘’feedback’’ that’s the main difference between an open and closed-loop system.

Closed-loop systems are designed to automatically achieve and maintain the desired output condition by comparing it with the actual condition. It does this by generating an error signal which is the difference between the output and the reference input. In other words, a closed-loop system is a fully automatic control system in which its control action being dependent on the output in some way. The main advantage of a closed-loop system is its ability to reduce a system’s sensitivity to external disturbances.

Examples Of Closed Loop System

  • Missile launching system
  • Voltage stabilizer
  • Temperature controller
  • Toaster
  • Computer mouse
  • Television remote

Characteristics Of Closed Loop System

  1. A closed loop control system considers the current output and alters it to the desired condition. The control action in these systems is based on the output.
  2. The closed loop system is also referred to as feedback system control system.
  3. A closed loop control system doesn’t encounter and react on external disturbances or internal variations.
  4. Missile launching system, voltage stabilizer, temperature controller, toaster, Computer mouse and television remote are examples of closed loop system.
  5. Closed loop system is more accurate when compared to open loop system.
  6. The input control system has linear responses.
  7. Closed loop system is complex to design as there is feedback.
  8. Error detector is present in closed loop system.
  9. Closed loop systems are mostly less stable.
  10. A closed loop system requires a large number of components to implement and thus it is a complex principle to implement.
  11. Closed loop systems comparatively requires less calibration and higher power rating.
  12. Closed loop system gives the slow response.
  13. Closed loop system is less reliable.
  14. The closed loop system is optimized.

Also Read: Difference Between Sequential And Combinational Logical Circuit

Difference Between Open Loop And Closed Loop System In Tabular Form

BASIS OF COMPARISON OPEN LOOP SYSTEM CLOSED LOOP SYSTEM
Description An open loop control system acts completely on the basis of input and the output has no effect on the control action.   A closed loop control system considers the current output and alters it to the desired condition. The control action in these systems is based on the output.  
Synonym The open loop system can also be referred to as the non-feedback system control system.   The closed loop system is also referred to as feedback system control system.  
Disturbances An open loop system works on fixed operation conditions and there are no disturbances.   A closed loop control system doesn’t encounter and react on external disturbances or internal variations.  
Examples Examples of open loop system include traffic lights controller, water sprinkler, Stepper motors and automatic washing machine.   Missile launching system, voltage stabilizer, temperature controller, toaster, Computer mouse and television remote are examples of closed loop system.  
Accuracy The accuracy of the closed loop system is comparatively less to that of closed-loop system.   Closed loop system is more accurate when compared to open loop system.  
Input/Output Control The output control system has a non-linear response.   The input control system has linear responses.  
Design Open loop system is easy to design as there is no feedback.   Closed loop system is complex to design as there is feedback.  
Error Detector Error detector is not present in open loop system.   Error detector is present in closed loop system.  
Stability Open loop control systems are mostly stable.   Closed loop systems are mostly less stable.  
Number Of Components An open loop system is an easy principle to implement as it requires less number of components to be constructed.   A closed loop system requires a large number of components to implement and thus it is a complex principle to implement.  
Calibration Open loop systems require good calibration and lesser power rating.   Closed loop systems comparatively requires less calibration and higher power rating.  
Response The open loop system gives a fast response.   Closed loop system gives the slow response.  
Reliable Open loop system is reliable.   Closed loop system is less reliable.  
Optimization The open loop system is not optimized.   The closed loop system is optimized.