Table 9 Extracted gait features with formulation and definition.

Primary gait features

Stride time

\(\:ST=\:{R}_{HS(n+1)}-{R}_{HS\left(n\right)}\)

Duration between two consecutive events of the reference foot

Stance time

\(\:{R}_{stn}={R}_{To\left(n\right)}-{R}_{HS\left(n\right)}\)

Duration when reference foot is in contact with the ground

Swing time

\(\:{R}_{sw}={R}_{HS\left(n\right)}-{R}_{TO\left(n\right)}\)

Duration when reference foot is off the ground

Double support time

\(\:DS\:={L}_{TO\left(n\right)}-{R}_{HS\left(n\right)}\:\text{o}\text{r}\:DS\:={L}_{HS(n+1)}-{R}_{TO\left(n\right)}\)

Duration when body-weight is supported by both feet

Gait speed

\(\:SV=\:\frac{Total\:distance\:covered}{ST}\)

Distance covered in direction of propagation per unit time

Secondary gait features

SI_Stance time

\(\:{SI}_{stn}=2*\:\frac{\left|{L}_{stn}-{R}_{stn}\right|}{{L}_{stn}+{R}_{stn}}\)

Symmetry index calculated from both legs during stance time

SI_Swing time

\(\:{SI}_{sw}=2*\:\frac{\left|{L}_{sw}-{R}_{sw}\right|}{{L}_{sw}+{R}_{sw}}\)

Symmetry index calculated from both legs during swing time

CoV_Stride time

\(\:\%CoV\_str=\:\frac{{\sigma\:}_{str}}{{\mu\:}_{str}}\times\:100\)

Computation of stride-to-stride fluctuations during complete gait cycle

CoV_Stance time

\(\:\%CoV\_stn=\:\frac{{\sigma\:}_{stn}}{{\mu\:}_{stn}}\times\:100\)

Computing stride fluctuations during stance phase of gait cycle

CoV_Swing time

\(\:\%CoV\_sw=\:\frac{{\sigma\:}_{sw}}{{\mu\:}_{sw}}\times\:100\)

Computing stride fluctuations during swing phase of gait cycle

CoV_DS time

\(\:\%CoV\_DS=\:\frac{{\sigma\:}_{DS}}{{\mu\:}_{DS}}\times\:100\)

Computing fluctuations when body-weight is fully supported by both feet

nm_Stance time

\(\:nm\_sw=\:\frac{{R}_{sw}}{ST}\times\:100\)

Computation of swing-time with respect to stride time or gait cycle time

nm_Swing time

\(\:nm\_stn=\:\frac{{R}_{stn}}{ST}\times\:100\)

Computation of stance-time with respect to stride-time or gait cycle time

nm_DS time

\(\:nm\_DS=\:\frac{DS}{ST}\times\:100\)

Computation of double support time with respect to stride-time or gait cycle time

Swing to stance ratio (RSS)

\(\:RSS=\:\frac{{R}_{sw}}{{R}_{stn}}\)

Computing ratio of swing-time to that of stance-time