0
Research Papers

Electromechanical Modeling and Adaptive Feedforward Control of a Self-Sensing Scanning Fiber Endoscope

[+] Author and Article Information
Ivan L. Yeoh, Per G. Reinhall, Martin C. Berg, Howard J. Chizeck, Eric J. Seibel

Department of Mechanical Engineering,
University of Washington,
Seattle, WA 98195

Contributed by the Dynamic Systems Division of ASME for publication in the JOURNAL OF DYNAMIC SYSTEMS, MEASUREMENT, AND CONTROL. Manuscript received August 1, 2015; final manuscript received May 13, 2016; published online June 28, 2016. Assoc. Editor: Kevin Fite.

J. Dyn. Sys., Meas., Control 138(10), 101006 (Jun 28, 2016) (15 pages) Paper No: DS-15-1360; doi: 10.1115/1.4033708 History: Received August 01, 2015; Revised May 13, 2016

Precise image capture using a mechanical scanning endoscope is framed as a resonant structural-deflection control problem in a novel application. A bipolar piezoelectric self-sensing circuit is introduced to retrofit the piezoelectric tube as a miniature sensor. A data-driven electromechanical modeling approach is presented using system identification and system inversion methods that together represent the first online-adaptive control strategy for the scanning fiber endoscope (SFE). Trajectory tracking experiments show marked improvements in scan accuracy over previous control methods and significantly, the ability of the new method to adapt to changing operating environments.

Copyright © 2016 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 2

Low-footprint self-sensing by implementing a sensing circuit at the proximal end of the device

Grahic Jump Location
Fig. 3

Our bipolar piezoelectric self-sensing circuit design

Grahic Jump Location
Fig. 4

(a) Axes convention for a piezoelectric material with respect to poling direction and (b) electrode configuration on the piezoelectric tube within the SFE

Grahic Jump Location
Fig. 5

(a) Electrode configuration with respect to the bending axes and (b) the piezoelectric tube bending along the y-axis direction, with radius of curvature ρ

Grahic Jump Location
Fig. 6

Tip deflection as related to bending radius for small bending approximation

Grahic Jump Location
Fig. 7

Experimental input-to-fiber deflection amplitude (y-axis) versus frequency excitation (x-axis), with the first two resonant modes clearly identifiable

Grahic Jump Location
Fig. 8

Lumped model of the mechanical scanner

Grahic Jump Location
Fig. 9

Full electromechanical model of the scanner for one eigendirection. The low-pass output circuit is to model the characteristics of the differential amplifier output stage.

Grahic Jump Location
Fig. 10

(a) Time-profile comparison between experimental data and model prediction and (b) plot of normalized error between experimental data and model prediction

Grahic Jump Location
Fig. 11

(a) First mode dynamics identified and extracted from piezoelectric self-sensing signal and (b) measurement—first mode residue. The remaining signal is largely input feedthrough due to capacitive bridge imbalance.

Grahic Jump Location
Fig. 12

(a) Experimental setup and (b) clamping of scanner in a v-groove by tightening a screw

Grahic Jump Location
Fig. 13

(a) Example of desired pixel locations on a spiral. (b) Example of the error between a desired location O and an achieved location X for a given pixel.

Grahic Jump Location
Fig. 14

(a) Twenty scan parameters manually configured for the de facto open-loop control. (b) Result of correctly calibrated open-loop control, showing straight braking lines and settling point.

Grahic Jump Location
Fig. 15

Unclamped: (a) 2D scan result with open-loop control, (b) 2D scan result with adaptive feedforward control, (c) normalized squared radial error compared between open-loop and adaptive feedforward result, and (d) phase/tangential squared error compared between open-loop and adaptive feedforward result

Grahic Jump Location
Fig. 16

Clamped: (a) 2D scan result with open-loop control, (b) 2D scan result with adaptive feedforward control (c) normalized squared radial error compared between open-loop and adaptive feedforward result, and (d) phase/tangential squared error compared between open-loop and adaptive feedforward result

Grahic Jump Location
Fig. 17

Radial and phase/tangential MSE over three unclamped tests and five clamped tests, achieved by open-loop versus adaptive feedforward method

Grahic Jump Location
Fig. 18

(a) Target image to be laser-projected, (b) open-loop scan unclamped, (c) open-loop scan after clamped, (d) adaptive feedforward scan unclamped, and (e) adaptive feedforward scan clamped

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In