Combined Regression and Classification Models for Accurate Estimation of Walking Speed Using a Wrist-worn IMU

Walking speed is an important quantity not only in fitness applications but also for lifestyle and health monitoring purposes. With the recent advances in MEMS technology, miniature body-worn sensors have been used for ambulatory walking speed estimation using regression models. However, studies show that these models are more prone to errors in slow walking regime compared to normal and fast walking regimes. To address this issue, our study proposes a combined classification and regression walking speed estimation model. An experimental evaluation was performed on 10 healthy subjects during treadmill walking trials using a smartwatch. The experimental results show that including the classification model can improve the accuracy of walking speed estimation in the slow speed regime by about 22%. The results show that the proposed combined model has error of less than around 13% for various walking speed regimes.