ElmoMC SimplIQ Digital Servo Drives-Bell Getting Started - Manual (Page 60)

The SimplIQ for Steppers Getting Started & Tuning and Commissioning Guide
MAN-BELGS (Ver. 1.1)
60
Appendix A: Manual Tuning of Speed
and Position Control
A.1 Scope
This Appendix explains how to manually tune controllers of the following types:
1. A PI speed controller.
2. Cascaded position controller: The inner loop is a PI speed controller and the outer
loop is a position simple gain controller.
3. A PI speed controller with a single notch filter, a low-pass filter or both.
4. Cascaded position: The inner loop is a PI speed controller with a single notch filter,
a low-pass filter or both; and the outer loop is a simple gain.
The notch filter and/or low-pass filter are termed in this document as "High
order filters".
High order filters are expected to improve closed loop performance
if the sensors are noisy with systems that exhibit resonance, and when it is
essential to decrease high frequency motor currents. The High order filter can
improve the controller performance dramatically when used correctly. Incorrect
usage of the High order filter can lead to a poor or even unstable controller.
Use the manual tuning as a starting point for automatic tuning: Automatic tuning
brings better results than human tuning in most cases.
Notes:
This appendix concentrates on manual tuning tips and theory, and it does not
provide an accurate description of controller parameterization. For that, refer to
the KP[N], KI[N] commands etc in the SimplIQ for Steppers Command
Reference Manual. All the relevant commands have links to the full control
structure description.
This appendix does not describe the tuning interfaces – see the sections on
motion tuning for that.
We strongly recommend familiarizing yourself with the controller structure and
parameterization before attempting to tune it.
A.2 Safety
Servo systems must be treated with care. In the tuning process, they must be
treated with extreme care. Although we have made our best efforts to generate
safe tuning conditions:
In the tuning process, the motion controller may become unstable, leading to an
abrupt, unexpected response.
In the tuning process, the motion controller may become very weak, letting
disturbances and external loads drive the shaft.
Read this appendix carefully before launching an experiment, and evaluate the
experiment parameters carefully before launching it. The Conductor suggests
some experiment parameters, but it may mislead you, being unaware of your
specific limitations.