KEH-Gait: Towards a Mobile Healthcare User Authentication System by Kinetic Energy Harvesting

Accelerometer-based gait recognition for mobile healthcare systems has became an attractive research topic in the past years. However, a major bottleneck of such system is it requires continuous sampling of accelerometer, which reduces battery life of wearable sensors. In this paper, we present KEHGait, which advocates use of output voltage signal from kinetic energy harvester (KEH) as the source for gait recognition. KEHGait is motivated by the prospect of significant power saving by not having to sample the accelerometer at all. Indeed, our measurements show that, compared to conventional accelerometerbased gait detection, KEH-Gait can reduce energy consumption by 78.15%. The feasibility of KEH-Gait is based on the fact that human gait has distinctive movement patterns for different individuals, which is expected to leave distinctive patterns for KEH as well. We evaluate the performance of KEH-Gait using two different types of KEH hardware on a data set of 20 subjects. Our experiments demonstrate that, although KEH-Gait yields slightly lower accuracy than accelerometer-based gait detection when single step is used, the accuracy problem can be overcome by the proposed Multi-Step Sparse Representation Classification (MSSRC). We discuss the advantages and limitations of our approach in detail and give practical insights to the use of KEH in a real-world environment.