29-08-2013, 04:55 PM
Open & Closed Loop Control System
[attachment=57587]
Closed-loop control
shows a closed-loop action (closed control loop);
can counteract against disturbances (negative feedback);
can become unstable, i.e. the controlled variable does not fade away, but grows (theoretically) to an infinite value.
Open-loop control
shows an open-loop action (controlled chain);
can only counteract against disturbances, for which it has been designed; other disturbances cannot be removed;
cannot become unstable - as long as the controlled object is stable.
Summarising these properties we can define:
Systems in which the output quantity has no effect upon the process input quantity are called open-loop control systems.
Systems in which the output has an effect upon the process input quantity in such a manner as to maintain the desired output value are called closed-loop control systems.
Open & Closed Loop Control System - Advantages & Disadvantages
Open & Closed Loop System - Advantages & Disadvantages [Control System].
In control systems engineering, a system is actually a group of objects or elements capable of performing individual tasks. They are connected in a specific sequence to perform a specific function.
A system is of 2 types:
1. Open loop system which is also called as Manual control system.
2. Closed loop system which is also named as automatic control system.
In this post, we will be discussing various advantages and disadvantages of the 2 types of control systems.
Open Loop System:
Advantages:
1. Simplicity and stability: they are simpler in their layout and hence are economical and stable too due to their simplicity.
2. Construction: Since these are having a simple layout so are easier to construct.
Disadvantages:
1. Accuracy and Reliability: since these systems do not have a feedback mechanism, so they are very inaccurate in terms of result output and hence they are unreliable too.
2. Due to the absence of a feedback mechanism, they are unable to remove the disturbances occurring from external sources.
Closed Loop System:
Advantages:
1. Accuracy: They are more accurate than open loop system due to their complex construction. They are equally accurate and are not disturbed in the presence of non-linearities.
2. Noise reduction ability: Since they are composed of a feedback mechanism, so they clear out the errors between input and output signals, and hence remain unaffected to the external noise sources.
Disadvantages:
1. Construction: They are relatively more complex in construction and hence it adds up to the cost making it costlier than open loop system.
2. Since it consists of feedback loop, it may create oscillatory response of the system and it also reduces the overall gain of the system.
3. Stability: It is less stable than open loop system but this disadvantage can be striked off since we can make the sensitivity of the system very small so as to make the system as stable as possible.
[attachment=57587]
Closed-loop control
shows a closed-loop action (closed control loop);
can counteract against disturbances (negative feedback);
can become unstable, i.e. the controlled variable does not fade away, but grows (theoretically) to an infinite value.
Open-loop control
shows an open-loop action (controlled chain);
can only counteract against disturbances, for which it has been designed; other disturbances cannot be removed;
cannot become unstable - as long as the controlled object is stable.
Summarising these properties we can define:
Systems in which the output quantity has no effect upon the process input quantity are called open-loop control systems.
Systems in which the output has an effect upon the process input quantity in such a manner as to maintain the desired output value are called closed-loop control systems.
Open & Closed Loop Control System - Advantages & Disadvantages
Open & Closed Loop System - Advantages & Disadvantages [Control System].
In control systems engineering, a system is actually a group of objects or elements capable of performing individual tasks. They are connected in a specific sequence to perform a specific function.
A system is of 2 types:
1. Open loop system which is also called as Manual control system.
2. Closed loop system which is also named as automatic control system.
In this post, we will be discussing various advantages and disadvantages of the 2 types of control systems.
Open Loop System:
Advantages:
1. Simplicity and stability: they are simpler in their layout and hence are economical and stable too due to their simplicity.
2. Construction: Since these are having a simple layout so are easier to construct.
Disadvantages:
1. Accuracy and Reliability: since these systems do not have a feedback mechanism, so they are very inaccurate in terms of result output and hence they are unreliable too.
2. Due to the absence of a feedback mechanism, they are unable to remove the disturbances occurring from external sources.
Closed Loop System:
Advantages:
1. Accuracy: They are more accurate than open loop system due to their complex construction. They are equally accurate and are not disturbed in the presence of non-linearities.
2. Noise reduction ability: Since they are composed of a feedback mechanism, so they clear out the errors between input and output signals, and hence remain unaffected to the external noise sources.
Disadvantages:
1. Construction: They are relatively more complex in construction and hence it adds up to the cost making it costlier than open loop system.
2. Since it consists of feedback loop, it may create oscillatory response of the system and it also reduces the overall gain of the system.
3. Stability: It is less stable than open loop system but this disadvantage can be striked off since we can make the sensitivity of the system very small so as to make the system as stable as possible.