Servo motor torque mode test

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Main idea[edit | edit source]

The servo motor torque mode test is a method to verify that basic parameters and wiring are correct. The target is to rotate/move the motor in torque mode in a continuous manner.

Assumptions[edit | edit source]

  • All wiring are triple checked and torque tuning is done properly.
    • Refer to the product user guidebook for detailed wiring instructions.
    • Pay special attention to encoder operating voltage (VCC) and GND wiring. Wiring VCC and GND erroneously may damage the encoder.
  • The motor is free to move/rotate, and no harm nor damages can happen from a long continuous movement.
  • You have read and understood servo tuning basics.

Steps[edit | edit source]

  1. Set the drive in Torque mode from Granity/Goals tab.
  2. Go to Granity/Testing tab.
  3. Make sure that the setpoint is zero and the drive is enabled and ready.
  4. Set the Target setpoint 1TSP1 Target setpoint 1 to 500.
  5. Increase the target setpoint slowly by clicking the "Increment by TSP1" button and checking whether the motor moves of not.
    • When setpoint reaches 16384 or greater, the maximum current is being delivered to motor. So further increase of setpoint will not have any effect.
    • If drive stops into overvelocity fault, it typically means that system works properly. However, you may increase Velocity tracking error thresholdFVT enough to complete the test without overvelocity fault.
  6. If the motor moves in a continuous manner, all parameters and wiring are correct.
    • If the motor halts, click the "Set zero setpoint" button and follow the troubleshooting instructions below.

Troubleshooting[edit | edit source]

In most cases, the motor halts after a short movement if the feedback resolution is incorrect, or if it's direction is reversed.

  • Check wiring, especially logic and motor voltages, Enable, and STO.
  • Check [FBI] Invert feedback direction checkbox in Granity/Machine tab, and repeat the steps above.
    • This inverts the encoder direction without the need for rewiring.
  • Check the motor pole count and encoder resolution from their datasheets.
  • Move the motor by known angle/distance, and check the position feedback reading from Granity/Testing tab.
    • The Position feedback value in Granity/Testing tab is always in CPR (counts per revolution). From this, the correct PPR can be calculated for one revolution (PPR = CPR/4).

Further reading[edit | edit source]

After the torque mode is configured and the motor can be controlled in torque mode properly, velocity and/or position modes can be tuned. Please refer to their respective instruction pages for further details.

Other motor types[edit | edit source]

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