Name: feedback in open and closed control systems
Uploaded: 2024-09-26T13:17:14.000Z
Duration: 1 min 17 s
Channel: JoVE

Control systems are primarily classified as open-loop and closed-loop or feedback control systems.
The elements of an open-loop system are the controller and the controlled process. An input signal is applied to the controller, which controls the process so that the controlled variable performs according to prescribed standards.
Open-loop systems operate independently of the output. A practical example is a washing machine that operates on a time basis without measuring the clothes&#39; cleanliness.
They are advantageous when the output is difficult to quantify or precise measurement is not economically feasible.
Closed-loop systems include one or more feedback links from the output to the input for more accurate control.
In a closed-loop idle-speed control system, any difference between the desired idling speed and the actual speed is sensed and corrected by adjusting the throttle angle. So, due to the use of feedback, the system quickly recovers after a disturbance to the preset value.
However, they are more complex to build and are generally higher in cost and power due to the use of more components.

open and closed-loop control systems

Control systems are foundational elements in automation and engineering. They are broadly categorized into open-loop and closed-loop systems. These classifications hinge on the presence or absence of feedback mechanisms, significantly influencing the system&#39;s performance, complexity, and application.
An open-loop control system operates without feedback from the output. It consists of two primary elements: the controller and the controlled process. The controller receives an input signal and manipulates the process to achieve the desired outcome. Importantly, open-loop systems function independently of the output, meaning there is no automatic correction based on the performance of the system. A common example of an open-loop system is a washing machine that runs on a predefined time cycle. It does not adjust its operation based on the cleanliness of the clothes, highlighting the absence of feedback. Open-loop systems are advantageous in scenarios where precise measurement of the output is either impractical or economically unfeasible. They are typically simpler and less costly to design and maintain due to their straightforward architecture.
In contrast, closed-loop or feedback control systems incorporate one or more feedback loops that continuously monitor the output and adjust the input accordingly to maintain the desired performance. This configuration significantly enhances accuracy and responsiveness. For instance, in a closed-loop idle-speed control system used in automotive engines, the system constantly monitors the idling speed and compares it to the desired speed. If a discrepancy is detected, the system adjusts the throttle angle to correct the speed. This feedback mechanism allows the system to quickly recover from disturbances and maintain the preset value, ensuring consistent performance.
Despite their superior accuracy and ability to handle disturbances, closed-loop systems are inherently more complex. They require additional components for monitoring and feedback, which increases the design complexity, cost, and power consumption. The choice between open-loop and closed-loop systems depends on the specific requirements of the application, including the need for precision, the feasibility of output measurement, and economic considerations.

Open and closed-loop control systems

Control systems are primarily classified as open-loop and closed-loop or feedback control systems.
The elements of an open-loop system are the controller ...

Education

JoVE Core

Electrical Engineering

Unit 1

Introduction to Control Systems

KEY TERMS AND CONCEPTS

feedback in open and closed control systems

Control systems are key parts of automation and engineering. They are usually grouped into open-loop and closed-loop systems. The difference depends on whether the output is fed back to the controller.

An open-loop control system works without feedback from the output. It has two main parts: the controller and the controlled process. The controller receives an input signal and drives the process to reach the desired result. Because it does not check the output, the system does not correct itself automatically.

A washing machine that runs for a preset time is a common open-loop example. It keeps running on the set cycle and does not measure how clean the clothes are. Open-loop systems are useful when measuring the output is difficult or too expensive. They are also simpler and cheaper to design and maintain.

A closed-loop control system, also called a feedback control system, uses one or more feedback loops. These loops monitor the output and adjust the input to keep the system near the desired value. This feedback improves accuracy and responsiveness.

An automotive idle-speed control system is a clear example of a closed-loop system. It monitors engine idle speed and compares it with the target speed. If the speed changes, the system adjusts the throttle angle to correct it. This helps the system recover quickly from disturbances and keep a steady preset value.

Closed-loop systems are more complex than open-loop systems. They need extra parts for monitoring and feedback, which can increase design complexity, cost, and power use. The best choice depends on the application’s needs, including precision, whether the output can be measured, and cost.

Feedback in Open and Closed Control Systems

feedback-in-open-and-closed-control-systems

control systems

Feedback in Everyday Control Systems

Control systems use feedback to keep a variable close to a desired value. They appear in both natural and engineered settings. Examples include blood sugar regulation, heart rate changes during stress, elevators, automated vehicles, aerospace systems, and automated manufacturing. A control system is a network of subsystems and processes that turns an input into a desired output. Several parts work together in that network. The controlled variable is the quantity the system tries to regulate.

control systems: applications

Control Systems in Cars and Furnaces

Control systems are used in cars, electric furnaces, and space shuttles to manage devices and processes. They help equipment work safely, correctly, and efficiently. Electrical engineering plays a central role in making these systems work in daily life. In modern vehicles, control systems help manage performance and safety. The steering wheel and accelerator are key inputs in the car control system. The steering direction and pedal pressure are processed to control the vehicle’s speed and...

Control systems are key parts of automation and engineering. They are usually grouped into open-loop and closed-loop systems. The difference depends on whether the output is fed back to the controller. An open-loop control system works without feedback from the output. It has two main parts: the controller and the controlled process. The controller receives an input signal and drives the process to reach the desired result. Because it does not check the output, the system does not correct...

effects of feedback

Feedback in Control Systems: Gain and Stability

Feedback in control systems changes gain, stability, and noise response. It does more than reduce error. A basic feedback system uses input, output, error, and feedback signals to shape how the system behaves. One major effect is on gain. Gain is the amount a system amplifies an input. Without feedback, the gain is changed by the factor 1 + GH, where G is the open-loop gain and H is the feedback factor. This means feedback can increase or reduce gain, depending on the frequency range. <br...

feedback control systems

Types of Feedback Control Systems

Feedback control systems can be grouped by how they behave, how their parameters change, and what kind of signals they use. These categories help engineers choose the right control method for a given system. They also make design and analysis easier. Linear feedback systems are theoretical models that simplify control design. In these systems, output is directly proportional to input within a certain range. An amplifier is a good example, but only while the input stays within its allowed range.

key terms and concepts

Learn how open-loop and closed-loop control systems work, why feedback matters, and how examples like washing machines and engine idle control differ.

Feedback in Open and Closed Control Systems | JoVE K12

JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

Feedback in Open and Closed Control Systems

Description

Transcript

Tags