Difference between Open Loop Control System and Closed Loop Control System
In this article we will discuss about the difference between open loop control system and closed loop system. We will learn about the basic control system . Advantage of control system and also about application of control system .
Basic Control System
Control system is a combination of elements arranged in a planned manner here in each element causes an effect to produce a desired output. The basic objective of control system is to control the outputs in some prescribed manner by the input through the element of control system.
Control system can be of two types
- Open loop control systems
- Closed loop control systems
Open loop control system
Systems in which output quantity has no effect on the input quantity are open-loop control system or non feedback system. Open loop systems are the systems in which input to the system at any instant independent of output at that instant.
Advantage of open loop control system
- Open loop system is simple.
- Open loop control system is economical
- Less maintenance is required and not difficult.
- Proper calibration is not a problem
- Disadvantages of Closed loop control system
- Open loop system are inaccurate.
- These are not reliable
- These are slow
- Optimization is not possible.
Closed Loop Control System
Closed loop control systems are also known as feedback control system. In closed loop control system the control action is dependent on the desired output, if any system is having one or more feedback paths froming a closed loop system . In closed loop systems the output is compared with the reference input and error signal is producd. The error signal is fed to the controller to reduce the error and desired output is obtained.
Advantage of Closed loop control system
These system are more reliable
- Closed loop systems are faster.
- A number of variables can be handled simultaneously
- Optimization is possible
- Disadvantages of Closed loop control system
- Closed loop system is expensive
- Maintenance is difficult
- Complicated installation.
Difference between Open Loop Control System and Closed Loop Control System.
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Open Loop Control System |
Closed Loop Control System |
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The accuracy of an open-loop system depends on the calibration of the input. Any departure from predetermined affects the output. |
As the error between the reference input and the output is continuously measured through feed back. The closed loop work more accurately. |
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The open-loop system is simple to construct and cheap. |
The closed-loop system is complicated to construct and costly. |
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The open-loop systems are generally stable. |
The closed-loop systems can become unstable under certain condition. |
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The operation of open loop system is affected due to the presence of non-linearities in its elements. |
In terms of the permormance the closed-loop system adjusts to the effects of non linearities present in its elements. These are basic difference between open loop control system and closed loop control system. |
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It is satisfactory for slow process. |
It is not satisfactory for slow process. |
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Optimization is not possible. |
Optimization is possible. |
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It is used only when inputs to the system are known ahead of time. |
It can be used when inputs are not known ahead of time. |
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Output has no effect on control action. |
Outpt has an effect on control action through feedback system. |
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There is no provision of removing errors in case of different output from what is desired thus this type of systems have less accuracy. |
They are more accurate systems as they are provided feedback path by which recalibration can be done in order to get desired output. |
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They are more sensitive to noise disturbances and changes in the environment. |
They are less sensitive to noise, disturbances and changes in environment . It is basic difference between open loop control system and closed loop control system. |
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It is convenient when output is difficult to measure. |
It is inconvenient when output is difficult to measure. |
Hence these are some basic difference between open loop control system and closed loop control system. If you will find any incorrect in above article . you must comment below in comment box.