Baldor MN1928 Servo axis - tuning for current control, Selecting servo loop gains, 6-16Operation

6.6 Servo axis - tuning for current control

6.6.1 Selecting servo loop gains

All servo loop parameters default to zero, meaning that the demand output will be zero at power up. Most servo amplifiers can be set to current (torque) control mode or velocity control mode; check that the servo 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 6.8. 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 servo 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 WorkBench v5 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 4. By default, axis 4 is a servo axis (although it can be reconfigured as a stepper - see section A.1).

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.

6-16 Operation MN1928