Table 8 Features extracted from the time-series signals (see Table 6).

MeanFreq

Mean frequency of actions

mean(f)

Speed

CovarFreq

Coefficient of variation of the frequency of actions

\({\textstyle{{{{{\mathrm{std}}}}({{{\mathrm{f}}}})} \over {{{{\mathrm{mean}}}}({{{\mathrm{f}}}})}}}\)

Speed

MeanVel

The average of the velocities between peaks and troughs

mean(V)

Speed

CovarVel

Coefficient of variation of the velocities between peaks and troughs

\({\textstyle{{{{{\mathrm{std}}}}({{{\mathrm{V}}}})} \over {{{{\mathrm{mean}}}}({{{\mathrm{V}}}})}}}\)

Speed

MeanAmp

Mean of amplitude of actions

mean(a)

Amplitude

CovarAmp

Coefficient of variation of the amplitude of actions

\({\textstyle{{{{{\mathrm{std}}}}({{{\mathrm{a}}}})} \over {{{{\mathrm{mean}}}}({{{\mathrm{a}}}})}}}\)

Amplitude

PeriodRange

The range of period of actions

range(d)

Hesitations

PrcInv

Average of the rate of inversions between peaks and troughs

mean(I)

Hesitations

Roughness

The median of the absolute jerk divided by absolute acceleration

\({{{\mathrm{median}}}}\left( {{\textstyle{{s^{\prime\prime \prime}} \over {s^{\prime\prime}}}}} \right)\)

Hesitations

DiffAmp

Percentage change between MeanAmp of first third of peaks (denoted A^T1) and the last third of peaks (denoted A^T3)

\({\textstyle{{{{{\mathrm{A}}}}^{T3} - {{{\mathrm{A}}}}^{T1}} \over {{{{\mathrm{A}}}}^{T1}}}}\)

Decrementing signal

DiffVel

Percentage change between MeanVel of the first third of peaks (denoted W^T1) and the last third of peaks (denoted W^T3)

\({\textstyle{{{{{\mathrm{W}}}}^{T3} - {{{\mathrm{W}}}}^{T1}} \over {{{{\mathrm{W}}}}^{T1}}}}\)

Decrementing signal