Rene Mayrhofer, Helmut Hlavacs,
"Optimal Derotation of Shared Acceleration Time Series by Determining Relative Spatial Alignment"
: Proc. iiWAS 2014: 16th International Conference on Information Integration and Web-based Applications \& Services, in iiWAS 2014, ACM Press, New York, NY, USA, Seite(n) 71--78, 2014, ISBN: 978-1-4503-3001-5
Optimal Derotation of Shared Acceleration Time Series by Determining Relative Spatial Alignment
Sprache des Titels:
Proc. iiWAS 2014: 16th International Conference on Information Integration and Web-based Applications \& Services
Detecting if two or multiple devices are moved together is
an interesting problem for different applications. However,
these devices may be aligned arbitrarily with regards to each
other, and the three dimensions sampled by their respective
local accelerometers can therefore not be directly compared.
The typical approach is to ignore all angular components
and only compare overall acceleration magnitudes -- with
the obvious disadvantage of discarding potentially useful information. In this paper, we contribute a method to ana-
lytically determine relative spatial alignment of two devices
based on their acceleration time series. Our method uses
quaternions to compute the optimal rotation with regards to
minimizing the mean squared error. The implication is that
the reference system of one device can be (locally and independently) aligned with the other, and thus that all three
dimensions can consequently be compared for more accurate classification. Based on real-world experimental data
from smart phones and smart watches shaken together, we
demonstrate the effectiveness of our method with a magnitude squared coherence metric, for which we show an im-
proved EER of 0.16 (when using derotation) over an EER
of 0.18 (when not using derotation).