ElmoMC SimplIQ Digital Servo Drives-Bell Command Reference - Manual (Page 289)

Chapter 8:The Position and Speed
Controller
This chapter, which provides details about the speed and position control algorithms,
is written for the advanced user who wants to tune the
SimplIQ servo drive manually,
rather than using the Digital Feedback Technologies tuning systems. Familiarity with
basic digital control theory is mandatory.
The type of controller used depends on the SimplIQ drive unit mode
Unit Mode Control Algorithm
0 Voltage mode
1 Open loop.
2 Speed control.
3 Micro-stepper.
4 Position, dual-feedback source. One sensor is used for commutation
and speed control while the other sensor serves for load position
control.
5 Position, single-feedback source.
Table 8-1: Unit Mode Values and Definitions
At the basic level of the speed controller, the control algorithm is the traditional PI
(proportional - integral). At the basic level of the position controller, the control
algorithm is an internal PI speed loop and an external position loop using a simple
gain for the controller, a structure known as a cascaded loop.
As control requirements become more stringent, the algorithms may extend to
include:
A high-order filter that operates in series with the PI controller, with the
following blocks:
Notch filters for notching resonance.
Low-pass filters for attenuating high-frequency resonance and
decreasing sensor noise.
A lead-lag element, which may increase bandwidth by adding phase
near the crossover frequency.
A continuous scheduling algorithm that modifies the PI algorithm as a
function of the closed loop operating point.
An advanced user may tune the various filter blocks, which is more complex than
tuning the PI and simple gain. The gain scheduling can be programmed by the
support software automatically or manually, using the Advanced Manual Tuning
options.
SimplIQ for Steppers Application Note The Position and Speed Controller
MAN-STECR (Ver. 1.1)
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