REFIT: Recognize, Fix, and Test Wearable Sensor Placement Shifts without Labels

Bangxun Tang (UC Irvine)

Summary

A gradient-free, label-free input calibration that sits in front of a frozen IMU activity classifier. It models a watch moved to the other wrist (a reflection) or a strap sensor put back turned (one of 24 axis-aligned rotations) as orthogonal axis transforms. The gyroscope picks up an extra det(A) sign because it measures an axial vector.