Control Systems Introduction & Types

Control Systems Introduction

• A control system is a collection of interconnected components designed to provide a desired output response given a specific input
• Control systems consist of subsystems and processes that work together to achieve a desired outcome
• Systems may be open or closed loop depending on their use of feedback
• Open loop systems lack feedback, making them less adaptable to changes
• Closed loop systems utilize feedback to adjust output and ensure desired performance, reacting to external influencing factors

Types of Control Systems

• Open loop: No feedback mechanism. Output doesn't affect input, making output dependent on a direct input and inflexible to changes.
• Closed loop (feedback): Output is measured and compared to desired output; the difference (error) is used to make adjustments to the input
• Feedback mechanisms are essential for accurate control and adaptation.

Main Control System Components

• Input: The starting point of the system. Input signals trigger the actions of the process.
• Process: The part where the input is converted into output. It contains the control logic
• Output: The end result of the control system workings.

Open Loop Systems

• Feedback is absent, and output doesn't affect the input
• Less adaptable to changes and less precise
• Simple design and often less costly
• Examples: Microwave, on/off lights (combinations circuits)

Closed Loop Systems

• Feedback is present, making the system adaptable to changes
• Output is measured and compared to desired output to regulate system
• More complex design but more precise and robust adjustments
• Examples: Thermostats, car drivers (reacts to the environment), split ACs

Positive Feedback

• System output is added to the input, amplifying the effect
• Can lead to instability, making it difficult to control

Negative Feedback

• System output is subtracted from the input, reducing the effect
• Stabilizes the output, making it easier to control
• Usually preferred in most control systems.

Multi-Loop Systems

• Multiple feedback loops exist (one-variable-multiple-loop). The loops interact for more complex outputs.

Multi-Variable Systems

• Many interconnected variables are controlled simultaneously.
• Multiple input and output. More intricate configurations and adjustments

Control System Design Processes

• Engineering design aims to create systems with desired specifications
• Design process proceeds through steps, including defining goals, identifying variables, defining system configuration, selecting controller parameters, evaluating, and optimizing.
• Iterative approach is frequently used to fine-tune the control system.

Engineering Design

• Complex process combining creativity and analysis to achieve a specific goal
• Involves creating a system, focusing on design activity. Planning, shape, material composition (all in accordance with the design goals)
• Creative use of knowledge to achieve functions, shapes, and material elements
• Designers need to determine needs from different groups. This includes detailed specifications
• Designers evaluate and decide on a particular design that satisfies specifications.

Terms and Concepts

• Automation: No human intervention, automated controls are implemented
• Closed Loop feedback: System that utilizes feedback to regulate actions. Output measures the current output relative to the desired output, this is how a feedback loop is created
• Design: The act of creation, making certain that all elements and factors are taken into account
• Design Gap: A difference between the abstract design and the final product

Laplace Transform

• Mathematical technique that converts a function from time domain into complex frequency domain to solve differential equations
• Linear systems are transformed into the frequency domain using a Laplace transform
• Equations are simplified and solved by transformations