5-28 Operation MN1941WEN
5.7 Local servo axis - tuning for current control
5.7.1 Selecting servo loop gains
All servo loop parameters default to zero, meaning that the demand output will be zero at
power up. Most drive amplifiers can be set to current (torque) control mode or velocity control
mode; check that the drive amplifier will operate in the correct mode. The procedure for
setting system gains differs slightly for each. To tune an axis for velocity control, go straight
to section 5.8. It is recommended that the system is initially tested and tuned with the motor
shaft disconnected from other machinery. Confirm that the encoder feedback signals from
the motor or drive amplifier have been connected, and that a positive demand causes a
positive feedback signal.
Note: The method explained in this section should allow you to gain good control of the
motor, but will not necessarily provide the optimum response without further fine-
tuning. Unavoidably, this requires a good understanding of the effect of the gain
terms.
1. In the Toolbox, click the Fine-tuning icon.
The Fine-tuning window is displayed at the
right of the screen. The main area of the
Mint WorkBench window displays the
Capture window. When tuning tests are
performed, this will display a graph
representing the response.
2. In the Fine-tuning window, click in the Axis
selection box at the top and select Axis 0
(assuming axis 0 has already been
configured as a servo axis - see section
5.4.3).
Click in the KDERIV box and enter a
starting value of 1.
Click Apply and then turn the motor shaft
by hand. Repeat this process, slowly
increasing the value of KDERIV until you
begin to feel some resistance in the motor
shaft. The exact value of KDERIV is not
critical at this stage.
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