Figure 5.

Scheme of signal processing and information analysis to obtain manual dexterity metrics on each sensor. Currently, four metrics have been achieved from IGlove’s raw signals: Duration of exercises (Duration), the number of movements during each exercise (Movements), spatial displacement (Disp), and angular displacement ($Dis{p}_{\theta }$). The absolute value of the Hilbert transform of a gyroscope signal is filtered to obtain a smoothened signal that is higher than 0 when the hand moves. A comparator decides when the level and duration of a perturbation in the signal were enough to mark it as an exercise. The metric Duration of an exercise is the difference between the end and the beginning of a significant perturbation. Variable Movements is calculated from the magnitude of angular speed $S_{\omega }$ (computed from all gyroscopes using Equation (1)). It was observed that peaks on $S_{\omega }$ indicate when a movement was performed. To estimate the number of moves, $S_{\omega }$ is smoothened, but this time, a peak detector identifies the spikes in the signal that were large enough and have been caused by a valid hand movement. The area under $S_{\omega }$ was calculated using numerical integration to estimate $Dis{p}_{\theta }$. Spatial kinematic parameters were estimated from accelerometers signal $S_a$ (calculated using Equation (3)), Runge–Kutta method was used to obtain an approximate time series for the magnitude of velocity $V_a$. Finally, spatial displacement is calculated as the area under the curve of $\left|V_a\left(t\right)\right|$. When performing numerical integration, Duration and Movements parameters were used to establish integration limits and estimate initial conditions.