Closed Loop Systems

Summary

In this lecture on control systems, the focus shifts from open loop systems to closed loop systems, which overcome the reliability issues of their predecessors by incorporating feedback. The closed loop system continuously measures and adjusts the output to maintain the desired level, as exemplified by air conditioners and geezers that regulate temperature. The lecture highlights the higher accuracy and reliability of closed loop systems, contrasting them with the simplicity and lower cost of open loop systems. The importance of the feedback mechanism is emphasized, setting the stage for further exploration of control system dynamics and the role of Laplace transform in upcoming sessions.

Takeaways

• 🔁 Open loop systems have a major disadvantage as they cannot handle disturbances and do not know when to stop the process, such as an immersion water heater that heats water until manually switched off.
• 🔄 Closed loop systems overcome the limitations of open loop systems by continuously measuring the output and using a feedback signal to maintain the desired output, improving system accuracy and reliability.
• 📊 The block diagram of an open loop system consists of a controller section and a process section, but lacks the feedback mechanism present in closed loop systems.
• 🌡️ An air conditioner serves as an example of a closed loop system, continuously monitoring and adjusting to maintain the desired room temperature.
• 🚿 A geezer, a type of water heater, is another example of a closed loop system that maintains a set temperature by monitoring and adjusting the heating process.
• 🔍 The presence of feedback in closed loop systems allows for error detection and correction, compensating for disturbances and enhancing system performance.
• 📉 Open loop systems are generally less accurate and less reliable compared to closed loop systems due to their inability to handle disturbances.
• 🛠️ Open loop systems are simpler and less expensive to design because they do not incorporate a feedback mechanism, making them more cost-effective.
• 🔧 Closed loop systems are more complex and expensive to design due to the additional feedback factor and the resulting complexity in circuitry.
• 🔄 The key differentiating factor between open and closed loop systems is the presence of feedback, which is absent in open loop and essential in closed loop systems.
• 📚 The lecture concludes with a预告of reviewing the Laplace transform in the next session, highlighting its importance in the study of control systems.

Q & A

What is the primary disadvantage of open loop systems discussed in the lecture?

The primary disadvantage of open loop systems is that they are not able to handle disturbances effectively and do not know when to stop, leading to a lack of reliability.

How does a closed loop system overcome the limitations of an open loop system?

A closed loop system overcomes the limitations of an open loop system by continuously measuring the output and feeding it back to the input to determine the error with respect to the desired output, allowing for adjustments to maintain the desired output.

What is the role of the error detection unit in a closed loop system?

The error detection unit in a closed loop system measures the output continuously and compares it with the desired output to determine the error, which is then used to adjust the input accordingly.

Can you provide an example of a closed loop system mentioned in the lecture?

An air conditioner is an example of a closed loop system, as it continuously monitors the temperature inside the room and adjusts the operation of the compressor to maintain the desired temperature.

How does a geezer, as a closed loop system, maintain the desired temperature of water?

A geezer maintains the desired temperature by continuously monitoring the water temperature and turning off and on the heating element to maintain the set temperature, adjusting as needed when the temperature decreases.

What is the main difference between open loop and closed loop systems in terms of reliability?

Closed loop systems are more reliable than open loop systems because they can handle disturbances and maintain accuracy, while open loop systems cannot effectively manage disturbances and are less accurate.

Why are open loop systems considered to be less complex in design compared to closed loop systems?

Open loop systems are less complex in design because they do not involve a feedback mechanism, resulting in simpler circuitry without the need for additional components to process feedback signals.

How does the presence of feedback in closed loop systems affect the system's cost?

The presence of feedback in closed loop systems makes them more expensive compared to open loop systems, due to the additional components and complex circuitry required for processing feedback signals.

What is the significance of the Laplace transform in the study of control systems as mentioned in the lecture?

The Laplace transform plays an important role in control systems as it is used for analyzing and designing systems in the frequency domain, which is crucial for understanding system dynamics and stability.

What will be the focus of the next lecture following the one in the script?

The next lecture will focus on a review of the Laplace transform, as it is an essential tool for further study and analysis of control systems.

Why is the feedback mechanism considered the distinguishing factor between open and closed loop systems?

The feedback mechanism is the distinguishing factor because it is absent in open loop systems and present in closed loop systems, enabling the latter to adjust and maintain the desired output in response to disturbances.

Outlines

00:00

🔁 Introduction to Closed-Loop Systems

This paragraph introduces the concept of closed-loop systems as a solution to the limitations of open-loop systems. It explains that open-loop systems lack the ability to handle disturbances and maintain desired outputs, as they do not measure output continuously. The paragraph uses the example of an immersion water heater to illustrate this point. It then contrasts this with closed-loop systems, which measure output continuously and use a feedback signal to adjust the input, ensuring the desired output is maintained. Examples of closed-loop systems include air conditioners and geysers, which monitor and adjust to maintain a set temperature. The paragraph concludes by highlighting the key advantage of closed-loop systems over open-loop systems in terms of reliability and accuracy.

Keywords

💡Control Systems

Control systems are an essential part of engineering that manage the behavior of a system to achieve desired outcomes. In the video, the theme revolves around the comparison and discussion of open and closed loop systems within the context of control systems, emphasizing the importance of feedback in closed-loop systems for maintaining accuracy and reliability.

💡Closed Loop Systems

Closed loop systems, also known as feedback systems, are a type of control system where the output is measured and fed back to the input to compare with the desired set point. The video explains how closed loop systems overcome the limitations of open loop systems by continuously monitoring and adjusting the system to maintain the desired output, using examples like air conditioners and geezers.

💡Open Loop Systems

Open loop systems are control systems without feedback, meaning they do not measure or adjust the output based on the system's performance. The script describes the disadvantages of open loop systems, such as their inability to handle disturbances or maintain a desired output, using the example of an immersion water heater that does not stop heating until manually switched off.

💡Feedback

Feedback in control systems refers to the process of taking the output signal and using it as an input to adjust the system's behavior. The video script highlights feedback as the key distinguishing factor between open and closed loop systems, emphasizing its role in improving system accuracy and reliability.

💡Error Detection Unit

The error detection unit is a component of closed loop systems that compares the feedback signal with the desired output to determine the error. The script explains that this unit is crucial for closed loop systems to make adjustments based on the difference between the actual and desired outputs.

💡Controller

In the context of control systems, a controller is a device or system that manages the operation of other devices or systems. The video script mentions the controller's role in closed loop systems to adjust the input based on the error signal from the error detection unit to achieve the desired response.

💡Process Section

The process section in control systems is the part that processes the input to generate the output. The script describes how in open loop systems, the process section operates without feedback, while in closed loop systems, it works in conjunction with feedback to maintain the desired output.

💡Desired Output

The desired output is the target or set point that a control system aims to achieve. The video script uses the term to illustrate the goal of both open and closed loop systems, with closed loop systems being better at maintaining the desired output through continuous feedback and adjustment.

💡Disturbance

Disturbance refers to any unwanted change or interference that affects the performance of a control system. The script points out that open loop systems are not able to handle disturbances effectively, while closed loop systems use feedback to compensate for such disturbances and maintain accuracy.

💡Geezer

A geezer, in the context of the script, is a type of water heater that can be set to a desired temperature and uses a closed loop system to maintain that temperature. It serves as an example in the video to illustrate the practical application of closed loop systems in everyday appliances.

💡Laplace Transform

The Laplace transform is a mathematical method used to analyze and simplify the analysis of linear time-invariant systems. The script mentions that the Laplace transform will play an important role in future discussions of control systems, indicating its relevance in the study of system dynamics and control strategies.

Highlights

Introduction to closed-loop systems as a solution to the disadvantages of open-loop systems.

Explanation of open-loop systems' inability to handle disturbances and their unreliability.

Description of the block diagram of an open-loop system, including the controller and process sections.

The immersion water heater example illustrating the lack of self-regulation in open-loop systems.

Introduction of feedback signals in closed-loop systems for continuous output measurement and error detection.

The role of the error detection unit in closed-loop systems to determine the error with respect to the desired output.

How controllers in closed-loop systems adjust input based on the desired response to achieve the desired output.

The air conditioner example demonstrating the continuous monitoring and regulation in closed-loop systems.

The geezer example showing how closed-loop systems maintain desired temperature by turning off and on.

Comparison of open-loop and closed-loop systems in terms of accuracy, reliability, and design complexity.

The cost difference between open-loop and closed-loop systems, with closed-loop systems being more expensive.

The distinguishing factor between open-loop and closed-loop systems: the presence of feedback.

Upcoming discussion on types of feedback in control systems.

Importance of the Laplace transform in control systems and its role in upcoming lectures.

Conclusion of the lecture with a summary of the key points discussed about closed-loop systems.

Applause and music signaling the end of the lecture.

Transcripts

hello everyone and welcome back to the

next lecture of control systems in this

lecture we will discuss the closed loop

systems in the previous lecture we

discussed about the open loop systems

and we also had discussion on some of

the disadvantages of using the open loop

systems and we all know that the open

loop systems are not reliable because

they are not able to handle the

disturbance so now in this lecture we

will try to overcome that disadvantage

and let's see how we can do it so let's

get started this is the block diagram of

an open loop system that we have already

discussed in the previous lecture and we

know that the open loop systems are

internally divided into two different

sections one is the controller section

which controls the amount of input that

is required for the desired output and

the process section processes the input

in order to generate the output but the

major disadvantage in case of the open

loop systems is that it does not know

when to stop or it is not able to handle

the disturbance we took one example of

an immersion water heater in the

previous lecture and we know that if we

put the heating rod inside the water and

we turn the switch on then the immersion

water heater starts heating the water

but it does not know when to stop

heating or we can say that that open

loop system does not know your desired

output and that's why it goes on heating

the water until you turn the switch off

so in order to maintain the desired

output we need to measure the output

continuously and we do it by using a

feedback signal in the closed loop

systems we can say the output the output

is measured continuously and is fed back

to the input where the error with

respect to the desired output is

determined we call this unit as the

error detection unit and then after that

the signal goes to the controller the

controller then controls the amount of

input according to the desired response

and then the controlled input goes to

the process section and hence we get the

desired output and this time the desired

output is maintained and in this way the

presence of feedback compensates for

the disturbance and it improves the

accuracy of the system an air

conditioner is a very good example of a

closed-loop system it continuously

monitors the temperature inside the room

and accordingly it turns off and starts

over the compressor which is present

outside the room and in this way it

maintains the desired temperature we can

have one more example of a geezer a

geezer is a water heater but here we can

set the desired temperature it

continuously monitors the temperature of

the water present inside and it turns

off and starts over again in order to

maintain the desired temperature

whenever the desired temperature is

achieved the Geezer will turn off and

after some time when the temperature

decreases it starts over again in order

to maintain the temperature so now we

are done with the introductory portion

of closed-loop systems and now we will

have a comparison of open loop systems

and the closed loop systems moving on to

the comparison between the open loop

systems and the closed loop systems we

can say that the accuracy of open loop

systems is low because they can't handle

disturbance whereas the accuracy of

closed loop systems is high because they

are able to handle disturbance

the open-loop systems are not that

reliable because they are not accurate

on the other hand the closed-loop

systems are more reliable because they

are more accurate the open-loop systems

are easy to design because there is no

feedback factor involved and the

circuitry is simple whereas the

closed-loop systems are complex in

design because an additional feedback

factor is involved and the circuitry is

complex due to all the three reasons the

open-loop systems are less expensive as

compared to the closed-loop systems but

the closed-loop systems are expensive

and now what is the distinguishing

factor between the two yes it is the

feedback which is the distinguishing

factor between the open-loop systems and

the closed-loop systems and is absent in

the open-loop and is present in the

closed-loop systems we will discuss the

types of feedback in the upcoming

sections of this course we will also

have the transfer function of a control

system but before that in the very next

lecture we will take a review of Laplace

transform because from now onwards the

Laplace transform will play an important

role in control systems as of now we are

done with this lecture I'll end this

lecture here see you in the next one

[Applause]

[Music]