Sources of variability in the set-up of an Indoor GPS

Carlo Ferri, Luca Mastrogiacomo, Julian Faraway

Research output: Contribution to journalArticlepeer-review

9 Citations (SciVal)
198 Downloads (Pure)


An increasing demand for an extended flexibility to model types and production volumes in the manufacture of large-size assemblies has generated a growing interest in the reduction of jigs and fixtures deployment during assembly operations. A key factor enabling and sustaining this reduction is the constantly expanding availability of instruments for dimensional measurement of large-size products. However, the increasing complexity of these measurement systems and their set-up procedures may hinder the final users in their effort to assess whether the performance of these instruments is adequate for pre-specified inspection tasks. In this paper, mixed-effects and fixed-effects linear statistical models are proposed as a tool to assess quantitatively the effect of set-up procedures on the uncertainty of measurement results. This approach is demonstrated on a Metris Indoor GPS system (iGPS). The main conclusion is that more than 99% of the variability in the considered measurements is accounted for by the number of points used in the bundle adjustment procedure during the set-up phase. Also, different regions of the workspace have significantly different error standard deviations and a significant effect on the transient duration of measurement. This is expected to affect adversely the precision and unbiasedness of measurements taken with Indoor GPS when tracking moving objects.
Original languageEnglish
Pages (from-to)487-499
Number of pages13
JournalInternational Journal of Computer Integrated Manufacturing
Issue number6
Publication statusPublished - 6 Jun 2010


Dive into the research topics of 'Sources of variability in the set-up of an Indoor GPS'. Together they form a unique fingerprint.

Cite this