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Proceedings Paper

Optimizing the feedback control of Galvo scanners for laser manufacturing systems
Author(s): Theodore Mirtchev; Robert Weeks; Sergey Minko
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Paper Abstract

This paper summarizes the factors that limit the performance of moving-magnet galvo scanners driven by closed-loop digital servo amplifiers: torsional resonances, drifts, nonlinearities, feedback noise and friction. Then it describes a detailed Simulink® simulator that takes into account these factors and can be used to automatically tune the controller for best results with given galvo type and trajectory patterns. It allows for rapid testing of different control schemes, for instance combined position/velocity PID loops and displays the corresponding output in terms of torque, angular position and feedback sensor signal. The tool is configurable and can either use a dynamical state-space model of galvo's open-loop response, or can import the experimentally measured frequency domain transfer function. Next a drive signal digital pre-filtering technique is discussed. By performing a real-time Fourier analysis of the raw command signal it can be pre-warped to minimize all harmonics around the torsional resonances while boosting other non-resonant high frequencies. The optimized waveform results in much smaller overshoot and better settling time. Similar performance gain cannot be extracted from the servo controller alone.

Paper Details

Date Published: 22 September 2010
PDF: 7 pages
Proc. SPIE 7750, Photonics North 2010, 77500T (22 September 2010); doi: 10.1117/12.873068
Show Author Affiliations
Theodore Mirtchev, Algonquin College (Canada)
Robert Weeks, Algonquin College (Canada)
Sergey Minko, Algonquin College (Canada)

Published in SPIE Proceedings Vol. 7750:
Photonics North 2010
Henry P. Schriemer; Rafael N. Kleiman, Editor(s)

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