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Open Loop Control System Vs Closed Loop Control System | Difference between Open Loop Control System and Closed Loop Control System

This page compares Open Loop Control System vs Closed Loop Control System and mentions difference between Open Loop Control System and Closed Loop Control System.

What is control System ?
A control system is a combination of elements arranged in a planned manner where in each element causes an effect to produce a desired output.

The control system is categorized into following types.
➨Open Loop Control System
➨Closed Loop Control System: Further divided into positive feedback and negative feedback

Open Loop Control System

Open Loop Control System

• It is conditional control system, formulated under basic condition that, the system is not subjected to any type of the disturbances.
• Control characteristics of such systems are independent of output of the system.
• The output is neither measured nor feedback for comparison with the input.

Closed Loop Control System

Closed Loop Control System

• Control characteristics of the system depends upon the output of the system.
• It is also termed as feedback control system.
• The control action is actuated by an error signal 'e' which is difference between input signal and output signal.
• The purpose of the feedback is to reduce the error between the reference input and system output.

The effect of negative feedback are as follows.
• Effect of parameter variation reduces.
• The gain of system reduces by a factor (1+GH).
• The bandwidth of system increases.
• Effect of internal disturbance reduces.


Open Loop Control System Closed Loop Control System
As long as calibration is good, open loop system will be accurate. Due to feedback, the closed loop system is more accurate.
Organization is simple and easy to construct. Complicated and difficult.
Generally stable in operation. Stability depends on system components.
If non-linearity is present, system operation degrades. The performance is better compare to open loop system if non-linearity is present.



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