Measurement of Deformations by MEMS Arrays, Verified at Sub-millimetre Level Using Robotic Total Stations

Authors

  • Tomas Beran Measurand Inc., 2111 Hanwell Road, Fredericton, New Brunswick, E3C 1M7 Canada
  • Lee Danisch Measurand Inc., 2111 Hanwell Road, Fredericton, New Brunswick, E3C 1M7 Canada
  • Adam Chrzanowski Canadian Centre for Geodetic Engineering, University of New Brunswick, PO Box 4400, Fredericton, New Brunswick, E3B 5A3 Canada
  • Maciej Bazanowski Canadian Centre for Geodetic Engineering, University of New Brunswick, PO Box 4400, Fredericton, New Brunswick, E3B 5A3 Canada

DOI:

https://doi.org/10.14311/gi.12.6

Keywords:

deformation monitoring, geodetic systems, geotechnical instrumentation

Abstract

Measurement of sub-millimetre-level deformations of structures in the presence of ambient temperature changes can be challenging. This paper describes the measurement of a structure moving due to temperature changes, using two ShapeAccelArray (SAA) instruments, and verified by a geodetic monitoring system. SAA is a geotechnical instrument often used for monitoring of displacements in soil. SAA uses micro-electromechanical system (MEMS) sensors to measure tilt in the gravity field. The geodetic monitoring system, which uses ALERT software, senses the displacements of targets relative to control points, using a robotic total station (RTS). The test setup consists of a central four-metre free-standing steel tube with other steel tubes welded to most of its length. The central tube is anchored in a concrete foundation. This composite “pole” is equipped with two SAAs as well as three geodetic prisms mounted on the top, in the middle, and in the foundation. The geodetic system uses multiple control targets mounted in concrete foundations of nearby buildings, and at the base of the pole. Long-term observations using two SAAs indicate that the pole is subject to deformations due to cyclical ambient temperature variations causing the pole to move by a few millimetres each day. In a multiple-day experiment, it was possible to track this movement using SAA as well as the RTS system. This paper presents data comparing the measurements of the two instruments and provides a good example of the detection of two-dimensional movements of seemingly rigid objects due to temperature changes.

References

CHRZANOWSKI, A. and A. SZOSTAK-CHRZANOWSKI (2010). “Automation of

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DANISCH, L., T. ABDOUN, and M. LOWERY-SIMPSON, (2007). Shape-Acceleration Measurement Device and Method, US Patent 7,296,363.

DANISCH, L., CHRZANOWSKI, A., BOND, J., and BAZANOWSKI, M. (2008).

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deformations,” presented at 13th FIG International Symposium on Deformation

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DANISCH, L., T. PATTERSON, and J. FLETCHER (2011). “MEMS-Array Monitoring of a Dam”, in Proceedings of Canadian Dam Association Annual Conference. Fredericton, NB. October 15-20, 2011.

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Published

2014-06-03

Issue

Vol. 12 (2014)

Section

Articles

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