High speed laser scanning microscopy by iterative learning control of a galvanometer scanner. (May 2016)

• Record Type: Journal Article
• Authors: Yoo, Han Woong; Ito, Shingo; Schitter, Georg
• Is Part Of: Control engineering practice. Volume 50(2016)
• Page Start: 12
• Page End: 21
• Publication Date: 2016-05
• Subjects: Iterative learning control -- Galvanometer scanner -- Non-minimum phase zeros -- Scanning laser microscopy -- Precision motion control; Automatic control -- Periodicals; 629.89
• DOI: 10.1016/j.conengprac.2016.02.007
• Languages: English
• ISSNs: 0967-0661

Abstract

Abstract: Iterative learning control (ILC) for a galvanometer scanner is proposed to achieve high speed, linear, and accurate bidirectional scanning for scanning laser microscopy. A galvanometer scanner, as a low stiffness actuator, is first stabilized with a feedback control compensating for disturbances and nonlinearities at low frequencies, and ILC is applied for the control of the fast scanning motion. For stable inversion of the non-minimum phase zeros, a time delay approximation and a zero phase approximation are used for design of ILC, and their attainable bandwidths are analyzed. Experimental results verify the benefits of ILC of its wide control bandwidth, enabling a faster, more linear, and more accurate scanning without a phase lag and a gain mismatch. At the scan rate of 4112 lines per second, the root mean square (RMS) error of the ILC can be reduced by a factor of 73 in comparison with the feedback controlled galvanometer scanner of the commercial system.