Tuning Multiple Rigidly Connected Axes

Knowledge Base: Troubleshooting
1

Here is a general procedure for tuning multiple rigidly connected cylinders:

  1. Put the axes in the same halt group
    In the Axis Tools, on the All tab, in the Halts section, set the Halt Group Number parameter to the same number ( not zero) for all the connected axes, then download the Axis Tools. This ensures that when any axis halts, all the other axes will also halt.

    • In the same section, review the Closed Loop Halt Decel and Open Loop Halt Decel values to make sure they will work safely for your application.

  2. Set up shortcut buttons
    Set up two Shortcut buttons to send identical commands to the axes. The first button will move them all to one position, the other will move them all to another position. Initially, make these positions somewhat close to each other.

  3. Set up a plot
    Set up a plot to contain the positions of all the axes. You may want to include the velocities and Control Output as well.

  4. Disable the Following Error
    Set the Following Error Auto Stop to Status Only.

  5. Tune the axes
    You will need to tune the axis manually, using the Shortcut buttons to sending identical moves to the axes simultaneously.

    1. Set the Proportional gain to a small value. Make sure to set it to the same for all axes.
    2. Move the axes and look at the plot.
    3. Increase the Proportional gains, move the axes again, and look at the plot.
    4. Once you have reasonable control, you may be able to lengthen the move distance.
    5. Once you have reasonable control, you may be able to use the Tuning Wizard to complete the tuning.
      1. In the Tuning Tools, click Tuning Wizard, choose Use an Existing Plot, and click next.
      2. Choose Two Plots and click Next.
      3. Choose the plots of your motion and click Next.
      4. Complete the wizard, and use the Gain calculator to choose some gains. Make sure to copy the gains to each axis.
      5. Move the axes, using the Gain Calculator to get new gains, as needed. Make sure to copy the gains to each axis.
        Make sure to set the Following Error Auto Stop to a value that is safe for your machine operation.
2

If it is possible to break something if the axes try to move in different directions or to different positions then it may be best to leave the Following Error Auto Stops set to Direct Output.

In addition, you can create a program that monitors the positions of the two axes and shuts down the axes if the positions diverge by more than a given amount. This program would need to be left running in the background during the whole tuning process.