Tuning torque controller

Torque controller tuning means finding the correct gain values for a torque controller inside the servo drive to achieve a proper response from a torque setpoint change.

In Granity, there is no dedicated PI gains as the software supports entering motor coil inductance and resistance where the optimum PI gains are calculated from. In order to change torque tuning, one needs to change motor resistance [MR] and inductance [ML] parameters until the torque response looks satisfactory.

Preparations

Correct torque tuning settings on the Testing tab.

Steps to do to begin torque tuning:

• Ensure that motor is parameterized correctly and working
• Fix the motor shaft so that it cannot rotate under full peak torque of the motor
• Make following parameter changes to Granity and click apply afterwards:
  • Set drive in torque control mode [CM]
  • Set torque bandwidth limit [TBW] to maximum
  • Choose Serial only setpoint input [CM]
  • Make other necessary adjustments to have drive powered and enabled
• Set-up the test stimulus and capture settings from Testing tab:
  • Set target setpoint 1 [TSP1] to 5000-15000
  • Set delay 1 [TSD1] to 0.05 seconds
  • Set target setpoint 2 [TSP2] to 0
  • Set delay1 [STD2] to 0.5 s
  • Choose sample rate [TSR] of 10000 Hz or more
  • Choose Capture setpoint change ind positive direction from the dropdown
  • Tick Continuously repeating capture
  • Tick Torque setpoint and Torque achieved from signals
  • Tick Start capture to begin continous capture.
  • Tick Enable test stimulus [TSE] to begin a pulsed torque generation

Steps to do after tuning finished:

• Stop test stimulus by unticking [TSE]
• Stop scope catpure by unticking Continuously repeating capture
• Undo all temporary changes made to settings (such as [TBW] and [CM])

Adjusting MR and ML to for optimum torque control

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