Ground Reaction Force Estimation via Time-aware Knowledge Distillation.

Human gait analysis with wearable sensors has been widely used in various applications, such as daily life healthcare, rehabilitation, physical therapy, and clinical diagnostics and monitoring. In particular, ground reaction force (GRF) provides critical information about how the body interacts with the ground during locomotion. Although instrumented treadmills have been widely used as the gold standard for measuring GRF during walking, their lack of portability and high cost make them impractical for many applications. As an alternative, low-cost, portable, wearable insole sensors have been utilized to measure GRF; however, these sensors are susceptible to noise and disturbance and are less accurate than treadmill measurements. Deep learning has shown potential in addressing these issues, but such methods are computationally expensive and often require extensive computing resources, limiting their feasibility for real-time and portable systems. To address these challenges, we propose a Time-aware Knowledge Distillation framework for GRF estimation from insole sensor data. This framework leverages similarity and temporal features within a mini-batch during the knowledge distillation process, effectively capturing the complementary relationships between features and the sequential properties of the target and input data. The performance of the lightweight models distilled through this framework was evaluated by comparing GRF estimations from insole sensor data against measurements from an instrumented treadmill. Various teacher-student model architectures and learning strategies were evaluated across multiple performance metrics using data collected at different walking speeds. Empirical results demonstrated that Time-aware Knowledge Distillation outperforms current baselines in GRF estimation from wearable sensor data. Moreover, our method significantly reduces the number of training parameters needed for GRF estimation, offering a data- and resource-efficient solution for human gait analysis while achieving excellent accuracy and model reliability.