Low-Power Synchronization for Multi-IMU WSNs

Wireless time synchronization is one of the most important services in a wireless sensor network (WSN). Inertial measurement units (IMUs) are often used in these WSNs in healthcare-related treatments. We present a low-power, wirelessly synchronized multi-IMU platform. The proposed approach synchronously captures packets from different IMUs and transmits the data over Bluetooth low energy (BLE) to a central data capturing unit (DCU). The contribution of this letter is, rather than focussing on the highest possible accuracy, to provide a low-power accurate enough solution for use in a multi-IMU WSN. We examine key factors affecting synchronization accuracy and elaborate on the implementation challenges. An accuracy of sub
$1~\mathrm {\mu }\text{s}$
can be achieved with the approach using 74.8
$\text{J}\mathrm {\mathbf {h^{-1}}}$
of energy, while a power-optimized implementation is presented with an accuracy of
$200~\mathrm {\mu }\text{s}$
and an energy consumption of only 198 mJ
$\mathrm {\mathbf {h^{-1}}}$
. This approach suits the required accuracy and low-power requirements for a multi-IMU system.