Open Loop Systems

Summary

In this lecture, the focus is on open-loop systems in control systems. An open-loop system is one where the control action is independent of the system's output, lacking a feedback mechanism. Examples include an immersion water heater and a toaster, which operate without monitoring the output. The lecture highlights the simplicity and cost-effectiveness of open-loop systems but also points out their inability to handle disturbances effectively. The session concludes with a teaser for the next lecture, which will cover closed-loop systems.

Takeaways

• 🔁 **Open Loop Systems**: Discussed in the lecture, these are systems where the control action is independent of the system's output.
• 🎯 **System Configurations**: Two types exist - open loop and closed loop, each with its own system behavior and characteristics.
• 🏗️ **Block Diagram**: The control system is divided into a controller section and a process section, with the controller managing the input for the process to generate the output.
• 🔑 **Reference Input**: The input to the system is now referred to as the reference input, which is controlled by the system's controller.
• ❌ **Lack of Feedback**: Open-loop systems do not have a feedback mechanism to adjust the input based on the output, making them less accurate and reliant on user experience.
• 🌡️ **Example - Immersion Water Heater**: Used as an example to illustrate an open-loop system, it heats water without a feedback mechanism to control the temperature.
• 🍞 **Example - Toaster**: Another example of an open-loop system, it heats bread without knowing when to stop, potentially burning the toast.
• 🛠️ **Simplicity and Economy**: Open-loop systems are praised for their simplicity in construction, economic design, and ease of use when output measurement is challenging.
• 🚫 **Vulnerability to Disturbances**: A significant disadvantage of open-loop systems is their inability to handle external disturbances effectively, affecting reliability.
• 🔄 **Transition to Closed-Loop**: To overcome the shortcomings of open-loop systems, a feedback loop is introduced, leading to the discussion of closed-loop systems in the next lecture.

Q & A

What are the two types of system configurations discussed in the lecture?

The two types of system configurations discussed are open loop and closed loop.

What is an open-loop system?

An open-loop system is one where the control action is independent of the system's output, meaning there is no feedback mechanism to adjust the input based on the output.

What is the role of the controller section in an open-loop system?

In an open-loop system, the controller section is responsible for controlling the amount of input required to process the input, but it does not consider the system's output.

Can you provide an example of an open-loop system from the lecture?

Yes, two examples given are an immersion water heater and a toaster. Both operate without feedback on the output, such as the temperature of the water or the bread.

What is the main advantage of open-loop systems as mentioned in the lecture?

The main advantages of open-loop systems are their simplicity in construction and design, economic nature due to fewer elements, and convenience when the output is difficult to measure.

What is the primary disadvantage of open-loop systems?

The primary disadvantage of open-loop systems is their inability to handle disturbances effectively, making them less reliable.

How does the presence of feedback in a system differ between open-loop and closed-loop systems?

In open-loop systems, there is no feedback from the output to adjust the input, whereas in closed-loop systems, feedback is used to regulate the input based on the output.

What is the term used for the input to the system in the context of the lecture?

In the context of the lecture, the input to the system is referred to as the 'reference input.'

How does the accuracy of an open-loop system depend on the user?

The accuracy of an open-loop system depends on the user's experience because the system does not have a mechanism to automatically adjust for desired output.

What is the next topic that will be discussed in the following lecture?

The next topic to be discussed is closed-loop systems, which will address the disadvantages of open-loop systems by introducing feedback mechanisms.

Outlines

00:00

🔧 Introduction to Open Loop Systems

This paragraph introduces the topic of open loop systems in control systems engineering. It contrasts open loop systems with closed loop systems, highlighting that in open loop systems, the control action is independent of the system's output. The lecture explains that an open loop system does not incorporate a feedback mechanism to adjust the input based on the output. Examples such as an immersion water heater and a toaster are used to illustrate the concept, where these devices operate without monitoring the output, leading to potential issues like overheating. The paragraph also touches on the simplicity and cost-effectiveness of open loop systems, but notes their inability to handle disturbances effectively.

Keywords

💡Control Systems

Control systems are engineered devices or processes that regulate the behavior of other devices or processes. In the context of the video, control systems are discussed in terms of their ability to process inputs and generate outputs, with a focus on how they are configured either as open-loop or closed-loop systems. The video emphasizes the importance of control systems in managing and directing the behavior of various processes, such as heating water or toasting bread.

💡Open Loop Systems

An open-loop system is one where the control action is independent of the system's output. This means that the system does not have a feedback mechanism to adjust its operation based on the output it produces. The video uses the example of an immersion water heater and a toaster to illustrate open-loop systems, where the devices continue their operation without any input from the output, potentially leading to over-heating or burnt toast.

💡Closed Loop Systems

Closed-loop systems, which will be discussed in a subsequent lecture as hinted in the video, are those where the output is fed back into the system to influence the control action. This feedback mechanism allows for adjustments to be made based on the output, making the system more responsive and accurate. The video suggests that closed-loop systems are an improvement over open-loop systems in terms of handling disturbances and maintaining reliability.

💡Block Diagram

A block diagram is a graphical representation of a system where the system's components are represented by blocks and their relationships by arrows. In the video, the block diagram of a control system is used to explain how inputs are processed through a controller and a process section to generate outputs. It helps visualize the separation between the controller, which manages the input, and the process, which produces the output.

💡Controller Section

The controller section of a control system is responsible for managing the amount of input required to process a task. As explained in the video, the controller decides how much input is necessary for the process section to generate the desired output. It is a crucial part of the system's operation, especially in open-loop systems where it operates without feedback from the output.

💡Process Section

The process section in a control system is where the actual processing of the input occurs to generate the output. The video describes how the controlled input from the controller section moves to the process section, which then processes it to produce the output. This is a key component in the operation of any control system, whether open-loop or closed-loop.

💡Reference Input

Reference input, as mentioned in the video, is the input provided to the control system. It is the starting point for the system's operation, and the controller uses this reference input to determine the necessary control actions. The video emphasizes that in open-loop systems, the reference input is independent of the output, which contrasts with closed-loop systems where the output can influence the reference input.

💡Feedback Signal

A feedback signal is a portion of the output that is sent back into the system to influence its operation. The video explains that open-loop systems lack a feedback signal, which means they cannot adjust their operation based on the output. This lack of feedback is a key characteristic of open-loop systems and is highlighted as a limitation that closed-loop systems overcome.

💡Disturbance

In the context of control systems, a disturbance refers to any unwanted change or influence that affects the system's operation. The video points out that open-loop systems are poorly equipped to handle disturbances because they do not have a feedback mechanism to make adjustments. This makes them less reliable compared to closed-loop systems that can compensate for disturbances.

💡Reliability

Reliability in control systems refers to the ability of a system to perform consistently and accurately over time. The video discusses how open-loop systems lack reliability because they cannot adjust to disturbances or changes in the environment. This is a key disadvantage of open-loop systems, and the video suggests that closed-loop systems offer improved reliability through their feedback mechanisms.

💡Economic

The term 'economic' in the video refers to the cost-effectiveness of open-loop systems. It is mentioned as an advantage because these systems are simpler in construction and design, requiring fewer elements and less complex circuitry. This simplicity makes them less expensive to implement, which is beneficial in scenarios where the output is difficult to measure or where a simple control system is sufficient.

Highlights

Introduction to open loop systems in control systems lecture.

Definition of open loop systems and their contrast with closed loop systems.

Explanation of control system block diagram with controller and process sections.

Description of the role of the controller in managing input for the process section.

Concept of reference input and its processing to generate output in an open loop system.

Open loop systems' characteristic of independent control action from system output.

Example of an immersion water heater as a classic open loop system.

Example of a toaster illustrating the lack of feedback in open loop systems.

Advantage of open loop systems being simple in construction and design.

Economic benefits of open loop systems due to fewer elements and simple circuitry.

Suitability of open loop systems when output measurement is challenging.

Disadvantage of open loop systems in handling disturbances and reliability.

Transition from open loop to closed loop systems by introducing feedback.

Anticipation of the next lecture focusing on closed loop systems.

Conclusion and appreciation expressed for the audience's attention.

Transcripts

hello everyone and welcome back to the

next lecture of control systems in this

lecture we will discuss the open loop

systems in the previous lecture we

discussed the system response

characteristics and in that lecture at

the end we had discussion on the system

configurations we have two types of

system configurations one is the open

loop configuration and the other is the

closed loop configuration and on the

basis of system configuration we have

two types of systems one is the open

loop system and the other is the closed

loop system so now in this lecture we

will discuss the open loop systems so

let's get started

we have discussed the block diagram of

control system and we all know that any

control system will take an input it

will process the input and it will

generate the output but internally the

control system is divided into two

different sections one is the controller

section that controls the amount of

input that is required to process the

input and the other is the process

section that actually processes the

input in order to generate the output on

the left hand side we have the input to

the system and from now onwards we will

call this as a reference input and on

this side we have the output so now we

can say that any control system will

take an input and inside the control

system the controller will control the

amount of input that is required for the

process and the controlled input will

move on to the process section and it

will be processed in the process section

in order to generate the output in this

way we are done with the block diagram

of open loop system now let's move on to

some of the important points of open

loop system

an open-loop control system is a system

in which the control action is totally

independent of the output of the system

this point simply says that the input to

the system is totally independent of the

output it means that we don't have a

feedback signal that tells us how to

vary the input learn to increase or

decrease the input signal in order to

get the desired output in that case the

accuracy of the system depends on the

experience of the user to understand

this one classical example is immersion

water heater that immersion rod that we

put inside the water to heat it yes that

one

it goes on heating the water but it

doesn't have a feedback mechanism to

tell you how hot the water is and when

to stop heating the water that's why it

is a perfect example of an open-loop

system one more classic example is of a

toaster the toaster goes on increasing

the temperature of the bread but it

doesn't know when to stop heating and

that's why sometimes we get to know that

the toast has burned so now we are done

with the introduction of open-loop

system now let's move on to the

advantages of using open-loop system the

first advantage of any open-loop system

is it is simple in construction and

design because it does not have a

complex mechanism also it is economic

because it does not have many elements

present in it and the circuitry is

simple also it is convenient to use when

the output is difficult to measure so we

have some advantages of using open-loop

systems but on the other hand we also

have some disadvantages and the major

disadvantage of using any open-loop

system is it is poorly equipped to

handle disturbance and as it can't

handle disturbance it is not reliable so

in order to remove the disadvantages of

open-loop system we will add one

feedback factor from the output side to

the input side and in this way we will

move on to the closed-loop systems we

will discuss the closed-loop systems in

the next lecture as of now we are done

with this lecture thank you for watching

this lecture I will end this lecture

here see in the next one

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[Applause]

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