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Proceedings Paper

A fast high-precision six-degree-of-freedom relative position sensor
Author(s): Gary B. Hughes; Van P. Macasaet; Janelle Griswold; Claudia A. Sison; Philip Lubin; Peter Meinhold; Jonathan Suen; Travis Brashears; Qicheng Zhang; Jonathan Madajian
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Paper Abstract

Lasers are commonly used in high-precision measurement and profiling systems. Some laser measurement systems are based on interferometry principles, and others are based on active triangulation, depending on requirements of the application. This paper describes an active triangulation laser measurement system for a specific application wherein the relative position of two fixed, rigid mechanical components is to be measured dynamically with high precision in six degrees of freedom (DOF). Potential applications include optical systems with feedback to control for mechanical vibration, such as target acquisition devices with multiple focal planes. The method uses an array of several laser emitters mounted on one component. The lasers are directed at a reflective surface on the second component. The reflective surface consists of a piecewise-planar pattern such as a pyramid, or more generally a curved reflective surface such as a hyperbolic paraboloid. The reflected spots are sensed at 2-dimensional photodiode arrays on the emitter component. Changes in the relative position of the emitter component and reflective surface will shift the location of the reflected spots within photodiode arrays. Relative motion in any degree of freedom produces independent shifts in the reflected spot locations, allowing full six-DOF relative position determination between the two component positions. Response time of the sensor is limited by the read-out rate of the photodiode arrays. Algorithms are given for position determination with limits on uncertainty and sensitivity, based on laser and spot-sensor characteristics, and assuming regular surfaces. Additional uncertainty analysis is achievable for surface irregularities based on calibration data.

Paper Details

Date Published: 15 March 2016
PDF: 9 pages
Proc. SPIE 9754, Photonic Instrumentation Engineering III, 975403 (15 March 2016); doi: 10.1117/12.2211372
Show Author Affiliations
Gary B. Hughes, California Polytechnic State Univ., San Luis Obispo (United States)
Van P. Macasaet, California Polytechnic State Univ., San Luis Obispo (United States)
Janelle Griswold, Univ. of California, Santa Barbara (United States)
Claudia A. Sison, California Polytechnic State Univ., San Luis Obispo (United States)
Philip Lubin, Univ. of California, Santa Barbara (United States)
Peter Meinhold, Univ. of California, Santa Barbara (United States)
Jonathan Suen, Univ. of California, Santa Barbara (United States)
Travis Brashears, Univ. of California, Santa Barbara (United States)
Qicheng Zhang, Univ. of California, Santa Barbara (United States)
Jonathan Madajian, Univ. of California, Santa Barbara (United States)


Published in SPIE Proceedings Vol. 9754:
Photonic Instrumentation Engineering III
Yakov G. Soskind; Craig Olson, Editor(s)

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