Mach-DSP User’s Manual
Document Number: MACH-DSP-9021
Page 76
www.ScannerMAX.com
9.0 Tuning Instructions
As described in section 7.7 of this manual, the Mach-DSP servo actually allows instant
access to up to four separate scanner tunings, accessible from a menu in the Mach-
DSP Servo Control Application.
When a complete system is purchased (scanners, mirrors, mount, servo driver, and
cables) the Mach-DSP should arrive already tuned at the Pangolin factory. Often times,
there will be several tunings already stored in memory, with the first, second, or third
tuning activated on power-up.
In the first part of this chapter will cover PD and PID tuning. The second part covers
PDF tuning. In any event it should be understood that, this manual is only meant to
familiarize the reader with the some of the overall concepts of scanner tuning. Certain
topics are not covered at all, such as how to properly tune the Low Frequency Damping
Filter and High Frequency Damping Filter, Notch Filters or any nonlinear correction
tables. To obtain a complete understanding of scanner tuning, you should contact
Pangolin and arrange a full training session. You may also consult the book “LASER
SCANNERS: Technologies and Applications found at
www.LaserScanningBook.com
.
If you are unfamiliar with the process of tuning galvanometers, it is recommended that
you only access tunings created and stored by Pangolin in memory.
DO NOT ATTEMPT TO CHANGE THE ADJUSTMENTS ON THE MACH-DSP UNLESS
YOU ARE THOROUGHLY FAMILIAR WITH SERVO TUNING CONCEPTS AS WELL
AS THE TUNING INSTRUCTIONS FOUND IN THIS CHAPTER OF THE MANUAL.
9.1
Equipment needed
The following equipment is required to properly tune the Mach-DSP servo driver:
Power Supply (see “Mach-DSP Specifications” for current and voltage ratings)
Mach-DSP Servo Control Application for the Windows-based PC
Test Signal Generator (external or built into Mach-DSP program)
Oscilloscope (external or built into Mach-DSP program)
Projection surface – preferably with optical scale or ruler
Visible Laser
Scanner Mount
9.2
Initial “PD” Tuning
The term “Initial PD tuning” refers to a tune that uses Proportional and Derivative servo
terms, and which may or may not achieve a desired level of performance, but is
adequate to set the most important servo parameters including
position scale, position
offset, input gain, input
offset
and possibly
notch filter
. After this initial tuning is
accomplished, further tuning can be done to fully achieve the desired performance
objective.