Proportional-Integral-Derivative
          Controller
       Presented by: Sancho McCann
Simple Control Loop


Control       Plant    Feedback
Examples

     Control             Plant            Feedback

     Throttle         Auto-engine       Wheel speed

    Air...
Speed control: lookup table
    10 kph      3% Throttle

    20 kph      6% Throttle

    40 kph      20% Throttle

    80...
What to do?




         Goal (set-point): 21 kph

How much should you change your throttle?
What to do?




            Set-point: 80 kph

How much should you change your throttle?
Proportional Controller
• Far from set point? Change throttle more
• Close to set point? Change throttle less


 quot;cont...
Example
Proportional-Derivative Control
    • Approaching set point quickly? Ease off
      throttle.


       pTerm = (setPoint q...
Example
Problem with Derivative Term



      Enhances noise
Integral Term
• Helps state average around the set point

• Accumulate historic error
• Allow this integral to inform the ...
Examples
Extremes
• What if
  –   P term is too low?
  –   P term is too high?
  –   D term is too low?
  –   D term is too high?
 ...
Tuning (one manual method)
• Start with low pGain (< 1)
• Set dGain ~ 100x pGain
• Increase dGain until oscillation
  – Ha...
Can be complex: Autopilot


Heading       Roll        Aileron
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Proportional-Derivative-Integral (PID) Control

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A simple, widely used control method. This presentation will provide an introduction to PID controllers, including demonstrations, and practise tuning a controller for a simple system.

From the Un-Distinguished Lecture Series (http://ws.cs.ubc.ca/~udls/). The talk was given Mar. 30, 2007.

Published in: Technology, Business

Proportional-Derivative-Integral (PID) Control

  1. 1. Proportional-Integral-Derivative Controller Presented by: Sancho McCann
  2. 2. Simple Control Loop Control Plant Feedback
  3. 3. Examples Control Plant Feedback Throttle Auto-engine Wheel speed Air temp Room temp Thermostat temp Steering direction Car Distance from path Voltage Electric motor Fan speed Fan speed CPU temp CPU temp sensor
  4. 4. Speed control: lookup table 10 kph 3% Throttle 20 kph 6% Throttle 40 kph 20% Throttle 80 kph 50% Throttle 140 kph 100% Throttle
  5. 5. What to do? Goal (set-point): 21 kph How much should you change your throttle?
  6. 6. What to do? Set-point: 80 kph How much should you change your throttle?
  7. 7. Proportional Controller • Far from set point? Change throttle more • Close to set point? Change throttle less quot;control = (setpoint # currentState) • pGain
  8. 8. Example
  9. 9. Proportional-Derivative Control • Approaching set point quickly? Ease off throttle. pTerm = (setPoint quot; currState) • pGain dTerm = (prevState quot; currState) • dGain #control = pTerm + dTerm !
  10. 10. Example
  11. 11. Problem with Derivative Term Enhances noise
  12. 12. Integral Term • Helps state average around the set point • Accumulate historic error • Allow this integral to inform the control decision
  13. 13. Examples
  14. 14. Extremes • What if – P term is too low? – P term is too high? – D term is too low? – D term is too high? – I term is too low? – I term is too high?
  15. 15. Tuning (one manual method) • Start with low pGain (< 1) • Set dGain ~ 100x pGain • Increase dGain until oscillation – Halve until no oscillation reduced • Increase pGain until oscillation – Halve that value • Set iGain very low and increase until a small overshoot is noticeable
  16. 16. Can be complex: Autopilot Heading Roll Aileron

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