Validation of the e-AR Sensor for Gait Event Detection Using the Parotec Foot Insole with Application to Post-Operative Recovery Monitoring

The use of e-AR (ear-worn activity recognition) sensorfor gait pattern estimation has shown promise for a range of health and wellbeing applications. To establish its more detailed quantitative accuracy, an in-shoe pressure measurement system (Parotec) has been used to validate the estimated gait events from the e-AR sensor. Ten healthy adults equipped with Parotec and e-AR systems walked in acorridor of about 15m. The sampling frequency of both systems was set at 100Hz and a manual synchronisation has been performed for subsequent error measurements. The gait events from the e-AR sensor are estimated by using a recently developed method based on singular spectrum analysis and longest common subsequence algorithms [1]. Thecorresponding gait events from the Parotec system are estimated using the ground reaction forces. The upper and lower limits of absolute errors using 95% confidence intervals for heel contact and toe off events obtained as 35.38±3.22ms and 73.05±7.24ms respectively. We furtherprovide a preliminary patient study to demonstrate how the estimated gait events and the gait analysis platform can be used for assessing patients recovering after orthopaedic surgery inside the clinic.