  Synchronisation of wireless inertial measurement units in human movement
analysis is often achieved using event-based synchronisation techniques.
However, these techniques lack precise event generation and accuracy. An
inaccurate synchronisation could lead to large errors in motion estimation and
reconstruction and therefore wrong analysis outputs. We propose a novel
event-based synchronisation technique based on a magnetic field, which allows
sub-sample accuracy. A setup featuring Shimmer3 inertial measurement units is
designed to test the approach. The proposed technique shows to be able to
synchronise with a maximum offset of below 2.6~ms with sensors measuring at
100~Hz. Also, the results indicate a reliable event generation and detection.
The investigated parameters suggest a required synchronisation time of eight
seconds. Further research should investigate the temperature changes that the
sensors are exposed to during human motion analysis and their influence on the
internal time measurement of the sensors. In addition, the approach should be
tested using inertial measurement units from different manufacturers to
investigate an identified constant offset in the accuracy measurements.
