Table 3.

Approaches to sensor-orientation invariance, managed by the participants.

Orientation Management	Team No.
By the magnitude of raw accelerometer or gyroscope signals	T6 (for all algorithms)
By using a pair of motion vectors for accelerometer, and
rotation angle around the 3D rotation axis for gyroscope [55]	T7 (for Alg. 2,4,5,6)
By PCA-based rotation matrix	T8 (for all algorithms)
By random rotations of inputs during training	T3 (for all algorithms)