ElmoMC SimplIQ Digital Servo Drives-Bell Getting Started - Manual (Page 55)

The SimplIQ for Steppers Getting Started & Tuning and Commissioning Guide
MAN-BELGS (Ver. 1.1)
55
Free: For non-restricted displacement around the initial position. The starting
step controller will keep the motor with constant speed, so that the frictions will
minimally affect identification. This mode gives the best linear identification.
Bounded: For restricted displacement around the initial position with given
position limits around the initial position. This mode gives most of the Free
mode advantages when you cannot allow free rotation of the motor.
You can identify in each of the "Stay in place", "Free" or "Bounded" modes.
The comparison will inform you how frictions affect your system; and the later
control design may consider all the cases.
The following figure shows your selection. The window opens by clicking
Identify in the Motion tab of the Conductor.
Figure 52: Selecting the identification method
Check Identify Aux. Sensor if you intend to use sensor #2 for position control.
4.2.4 Selecting the Identification Frequencies
The Conductor applies sine signals to the plant. Each sine signal must be
maintained long enough for the transients to disappear, then the Conductor can
extract the frequency response for that single frequency.
Putting so much energy in a single frequency gives the best results which are also
the most noise immune. However, the identification is slow.
The Conductor must select the identification frequency with care, so that:
It will find all the critical plant data, without missing important points.
It can complete the identification in a reasonable time.
The Conductor applies an iterative search which first spans a broad set of
frequencies.
Where the frequency response looks locally smooth, it accepts it.
Where it finds large amplitude or phase gradients, it applies denser frequencies.