ElmoMC SimplIQ Digital Servo Drives-Bell Getting Started - Manual (Page 66)

The SimplIQ for Steppers Getting Started & Tuning and Commissioning Guide
MAN-BELGS (Ver. 1.1)
66
A.7 Testing the Response of a Controller
Manual tuning is an iterative process in which you select parameters for the
controller, and then test them.
A.7.1 Current Limits
Beware that the peak current limit and the continuous current limit of the drive
may differ. If you use excessive current levels in the experiment, the drive may
switch automatically to the continuous limit, and exhibit saturation behavior.
A.7.2 Recording the Experiment Results
The Conductor's Wizard records the results of the tuning experiment. The
recorder is automatically triggered when the motion command (speed or target
position) changes.
The recorder records the reference and the actual speed and position waveforms,
and also the motor's current demand. The current demand is very useful for:
Detecting saturation. If the current demand is saturated then the system
reached physical limitations, and you cannot distinguish the small signal
response from the experiment result.
Current command waveforms easily reveal phenomena like friction (current
increases for a while before the motor starts to move), cogging (periodic-in-
position torque disturbance), dynamic unbalance (periodic-in-position torque
disturbance, proportional to the squared speed), play (the ratio between current
and acceleration jumps wildly), resonant limit cycle (constant frequency
sinusoidal disturbance) and much more.
Large high frequency current demands reveal the need for high frequency
filtering in a more vivid way than position or speed error.
Check that the currents are near the expected values for the accelerations used.
This gives you extra assurance that the system is properly assembled and well
calculated.
You can set the recorder time as long as you want, but for large recording times
you will lose resolution, as the number of the recorded data points is limited.
Notes:
The recorder can export the experiment results to Matlab8 for further analysis.
When decreasing the recorder resolution, you become more susceptible to
aliasing. In other words, high frequency disturbances may be totally mis-
presented, and they may look as phenomena of a much lower frequency.
8
Popular, excellent technical calculations software by MathWorks.