Control systemsLesson 1 of 3 in the course PID control

PID Control: Actions, Tuning, Stability, and Practical Implementation

5 flashcards · 5 quiz questions · 5 match pairs · 3 fill-in sentences · English

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Summary

This lesson introduces feedback control and explains how a PID controller compares a desired condition with a measured one to make automatic corrections.

A control system aims to make a measured process condition match a desired target. The desired target is the setpoint (SP), while the measured condition is the process variable (PV). The difference is the error, commonly defined as e(t)=SP−PV(t)e(t)=SP-PV(t).

All flashcards

Why can proportional-only control leave a steady-state offset?
A nonzero error may be needed to sustain the output required by the process.
What is integral windup?
Continued accumulation of integral error when the actuator has reached a feasible limit.
What is cascade control?
A control arrangement in which an outer controller's output sets the target for an inner controller.
What does direct action mean when error is defined as e=SP−PVe=SP-PV?
A positive error produces a positive correction in controller output.
What does a digital PID controller do at each sampling interval?
It samples the process, calculates the control output, and sends that output to an actuator.

Quiz questions

  1. In a PID controller, which feature of the error does proportional action respond to?Answer: The error's current value.
  2. What is a key role of integral action in PID control?Answer: Reducing persistent error that can remain with proportional-only control.
  3. What is a potential drawback of derivative action in a PID controller?Answer: It can amplify high-frequency measurement noise.
  4. In the common Ziegler–Nichols procedure, what is the ultimate gain KuK_u?Answer: The proportional gain at which the loop reaches sustained oscillation.
  5. How does feed-forward control differ from feedback control?Answer: It uses known setpoint or disturbance information to calculate part of the control action directly.

Based on the Wikipedia article PID controller, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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