How To Improve PID

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Presentation given during NIWeek 2008 about basics on PID and tips on how to improve it

Presentation given during NIWeek 2008 about basics on PID and tips on how to improve it

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  • 1. 1
  • 2. How to Improve your PID Controller Javier Gutierrez LabVIEW Product Marketing 2
  • 3. Benefits of Advanced Control and Tuning Model-based Manual • A poorly tuned control control < 1% control valve costs additional $880/year* • A bad pH loop incurred chemical waste of $50,000/month* • A bad kiln temp loop cost $30,000/month* PID needs PID is fine manual tuning *Sources: Cybosoft and ExperTune 3
  • 4. Agenda • What is PID? • How to improve performance  Hardware considerations  Upgrade PID Algorithm  Advanced Controllers • Conclusion 4
  • 5. Agenda • What is PID? • How to improve performance  Hardware considerations  Upgrade PID Algorithm  Advanced Controllers • Conclusion 5
  • 6. What is PID • Set Point (SP) – Desired control point • Output (OP) – Controller output • Process Variable (PV) – Plant/process output • Error = SP - PV error OP SP PV 6
  • 7. PID Parameters • Proportional  Drive to setpoint  Error → 0, OP → 0  “Steady-state error” • Integral  Eliminate steady state error  OP proportional to ∫ error • Derivative  Increase response rate  OP proportional to rate of change of error 7
  • 8. System to control 8
  • 9. PID Implementation Demo 9
  • 10. PID Control – Pros and Cons • Advantages  Proven  Easy to implement • Disadvantages  Not easy to tune  Not suitable for all systems • Backlash, friction, and so on 10
  • 11. Agenda • What is PID? • How to improve performance  Hardware considerations  Upgrade PID Algorithm  Advanced Controllers • Conclusion 11
  • 12. How to program PID Function Blocks Windows/Real Time FPGA Control and Simulation 12
  • 13. Benefits of Higher Loop Rates 13
  • 14. PID Loop rates 1 MHz 100 kHz 25 kHz 600 Hz 14
  • 15. Die Casting Machine The movement of the aluminium injection plunger controlled in a steady closed loop at a speed varying from 0 up to 10 m/sec. 15 Copyright 2007 © EUROelectronics srl – ITALY -
  • 16. Agenda • What is PID? • How to improve performance  Hardware considerations  Improve PID Algorithm  Advanced Controllers • Conclusion 16
  • 17. Upgrade your PID Disturbances Feed-forward Non Linear Gain Scheduling Time Variant Adaptive PID 17
  • 18. Feed-Forward • Commonly used to compensate for a measurable external disturbance before it affects a controlled variable. • e.g. product feed rate changes 18
  • 19. Gain Scheduling • Used to change gain on real-time depending on OV. • Bumpless transfers 19
  • 20. Adaptive PID • Mixed of On-Line system identification and common PID control. • Can handle time-variant systems 20
  • 21. Agenda • What is PID? • How to improve performance  Hardware considerations  Upgrade PID Algorithm  Advanced Controllers • Conclusion 21
  • 22. Advanced Controllers National Instruments • Optimal Controllers (LQR, LQG) • Model Predictive Control (MPC) • Kalman Filters • Fuzzy Logic Third Party Partners • Neural Networks • Genetic Algorithms • Model Free Adaptive 22
  • 23. How to create an advanced Controller Control Design • Datalogging • Deployment • System • Design • Test Identification • Simulation • Model Validation Plant Modeling Implementation 23
  • 24. Temp Chamber - Experiment 24
  • 25. Plant Modeling - Validation 25
  • 26. MPC Control Design 26
  • 27. MPC Control Prototype 27
  • 28. Advanced Controllers • Pros/Cons 28
  • 29. Agenda • What is PID? • How to improve performance  Hardware considerations  Upgrade PID Algorithm  Advanced Controllers • Conclusion 29
  • 30. Conclusions • PID • Consider  Upgrading hardware  Enhance PID Algorithm  Upgrading Control Algorithm 30