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Ziegler-Nichols Loop Tuning

The Ziegler-Nichols loop tuning protocol1) is a simple method to establishing the loop parameter values for a PI or PID control loop. This protocol is designed to optimize the loop for disturbance rejection.

Click here for the SLICE-QT Manual.
Click here for the SLICE-QT Quick Start Guide.
Click here for the SLICE-QT API.
Click here for the SLICE-QT web page.
Click here for the Github page for SLICE-QTC GUI
Click here for the Github page for SLICE-QTC firmware revisions

Instructions

There is the possibility for the loop to go unstable at too high gain. Use caution as gain is increased.
  1. From the Home Screen, touch the Channel icon for the loop to be tuned
  2. Touch Settings > PID Params
  3. Choose a Set Point temperature
  4. Set Proportional Gain (KP) to 0
  5. Turn off Integral and Differential portions of the loop (TI & TD, respectively)
  6. While monitoring the error in temperature on rolling graph on the SLICE-QT display or an external oscilloscope, slowly increase KP until the error begins to oscillate
  7. Use the and icons, to scale displayed response appropriately
  8. Use the icon to pause the graph
    1. Note: the pause icon only pauses the graph, not the servo control
  9. Note KP where oscillation begins; this is KP, cr, the critical proportional gain.
  10. Use the Cursors enabled by touching the icon to measure the period of oscillation, Tcr
    1. You can use the two rotary knobs or touch & drag the cursors on the touch screen
  11. Use the following table to set the values of KP, TI, and TD
Type of Control Loop KP TI TD
PI 0.45•KP, cr 0.83•Tcr 0
PID 0.6•KP, cr 0.5•Tcr 0.125•Tcr
Tab. 1: Ziegler-Nichols loop values
slice/z-n.txt · Last modified: 2019/07/29 14:11 by Michael Radunsky