# A Novel Wearable Foot and Ankle Monitoring System for the Assessment of Gait Biomechanics
###### Abstract
This results in the foot turning slightly outward then changing from a flexible foot to a more rigid foot, so it can propel the foot and push off from the ground. During this phase, the foot inverts slightly, and the arches become higher, thus enabling the foot to properly roll over the hallux [12]. As such, deviation from the physiological COP progression line accounts for some form of gait pathology. For illustration purpose, a physiological progression of the COP is presented in qualitative comparison to a pathological progression of the COP in Figure 4.  
The COP progression line can be assessed very well with the pressure sensor distributions in Figure 2b,c. Nevertheless, a finer resolution in the acquisition of plantar pressures, which spans across the whole footprint, is achieved with sensor distributions presented as follows. [PERSON] et al. deploys one sensor onto the toe, five sensors onto the metatarsal arch, one sensor onto the lateral arch and two sensors onto the heel [13], as illustrated in Figure 5a. As for another example, [PERSON] et al. deploy only three sensors onto the metatarsal arch, three sensors onto the heel and an additional sensor onto the medial arch as an indicator of flat foot [14], as illustrated in Figure 5b. On the other hand, the solutions proposed by [PERSON] et al. in [15] and illustrated in Figure 5c, as well as the solution proposed by [PERSON] et al. in [16] and illustrated in Figure 5d, deploy an additional sensor onto the lesser toes. Additionally, the solution of [PERSON] et al. keeps the FSR on the medial arch for flat foot indication. Figure 4: Center of pressure progression line for (**a**) physiological gait, (**b**) abnormal gait. During walking, the foot is the first part of the lower extremity to contact the ground and has to face multiple force loads, ranging from external forces, e.g., gravitational attraction exerted by the Earth and to ground reaction forces (GRF), to internal forces, e.g., the body weight and the oscillations of body center of mass, as illustrated with the red line in Figure 3a. The muscles involved in ankle movement are the pretibial muscles for dorsiflexion and calf muscles. The muscular activity for the lower kinetic chain throughout different phases of the gait cycle during the stance phase is listed in Table 1, followed by the muscular activity throughout the swing phase listed in Table 2. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Gait Phase** & **Heel Strike** & **Foot Flat** & **Midstance** & **Heel Off** & **Toe Off** \\ \hline
**Duration–** **\% of** **Total** & **0–2\%** & **0–10\%** & **10–30\%** & **30–50\%** & **50–60\%** \\ \hline
**Iliopsoas** & inactive & inactive & inactive & concentric & concentric \\ **Gluteus** & eccentric & inactive & inactive & inactive & inactive \\ **Gluteus** & eccentric & eccentric & eccentric & eccentric & inactive \\ **Medius** & eccentric & eccentric & inactive & inactive & inactive \\ **Hamstrips** & eccentric & eccentric & inactive & inactive & eccentric \\ **Quadriceps** & eccentric & eccentric & inactive & inactive & inactive \\ **Pretibial** & eccentric & eccentric & inactive & inactive & inactive \\ **Camles** & inactive & inactive & eccentric & concentric & concentric \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Muscular activity throughout the stance phases of the gait cycle [10]. Figure 5: Solutions of pressure sensor deployment on the footprint for dynamic assessment: (**a**) assessment of the footprint medial line with sensors deployed onto the hallux, metatarsal arch, lateral arch and heel respectively [13], (**b**) additional sensor deployed on the medial arch for flatfoot identification [14], (**c**) additional sensor deployed on the lesser toes and medial arch for flatfoot identification [15], (**d**) additional sensor deployed on the lesser toes [16]. In the present work, we have decided upon the assessment of the tibialis anterior--from the pretibial muscle group, and the gastrocnemius--from the calf muscle group.