Smoothness and continuity of movement. For continuous exercises, as they are typical for gym-based training, it is important
to maintain smooth motion. In order to remain relatively independent of the particular exercise and to avoid the excessive
use of prior knowledge, a novel local assessment approach has been developed (next section).
Global motion quality. Each exercise requires the user to perform particular motion sequences. The assessment on how well
these motions were performed is crucial for the assessment of the quality of the performed task.
Usage of board’s degrees of freedom. If a task requires the user to fully displace the board along at least one degree of freedom,
the fraction to which he uses this opportunity while avoiding extreme postures (e.g., touching the ground) provides a
valuable measure for exercise performance.
The goal of the automated assessment is to estimate measures for the aforementioned aspects and to combine them
into a single performance criterion or metric. Aiming at transferability of the method the amount of parameters and prior
knowledge used us limited as much as possible.
Before the actual analysis the recorded orientation-values (azimuth, pitch, roll) are normalized to a common value-range
with zero-mean. Deviation from mean translates into [−180°, +180°] and is mapped to [−1, +1]. For both pitch and roll the
calibrated 0-positions are taken as idle positi