ClearFoot: real-world continuous foot clearance measurement with integrated shoe morphometry

Minimum foot clearance (MFC) is a critical parameter for evaluating trip-related fall risk and actuating assistive gait devices. However, existing continuous monitoring systems are largely confined to laboratory settings or rely on bulky, footwear-dependent hardware. We present ClearFoot, a lightweight (<24 g), low-cost, and shoe-agnostic wearable sensing system for real-time, continuous foot clearance measurement. The system uses Time-of-Flight (ToF) distance sensors and 9-axis Inertial Measurement Units (IMUs) assembled as a sensing unit and attached modularly to the lateral side of the shoe, near the toes and heel. These sensors enable vertical distance measurement from the sensing units. Minimum foot clearance is determined by substrating a footwear geometric normalization value from this vertical distance. Validation through treadmill walking trials against goldstandard optical motion capture demonstrates the system’s spatial accuracy with an 5-6 mm RMSE for slower walking speeds of target populations. ClearFoot provides a robust, modular approach to out of lab gait instrumentation, offering strong translational potential for continuous clinical fall risk assessment and real-time control of assistive devices.