# A Novel Wearable Foot and Ankle Monitoring System for the Assessment of Gait Biomechanics
## 3 Results
Figure 18: The COP progression line during a stance phase with light red indicating applied pressure, following the successive activation of FSR\({}_{5}\)— heel area, FSR\({}_{4}\) to FSR\({}_{1}\)—midfoot, and FSR\({}_{0}\)—hallux. activity are indeed interdependent during the physiological gait cycle as prescribed in Table 1.  
Assessment of the interdependency between plantar pressure and muscular activity requires a more thorough analysis performed via cross-correlation, as described in mboxsectsect:sec2 dot3-applsci-1038217. The actual muscular activation pattern, determined for both tibialis anterior and gastrocnemius on the basis of the EMG features, is illustrated in Figure 20.  
The values of the EMG feature magnitudes, as read from Figure 20, discriminate walking form resting as prescribed by Table 4 (a 100\(\times\) multiplier was considered for MAV and RMS). This enables the evaluation of the FSR and EMG cross-correlation in the context of walking, aiming towards the decision upon physiological gait. Figure 19: The FSR recordings during a stance phase, plotted alongside the tibialis anterior and gastrocnemius EMG respectively. Figure 20: Muscular activation pattern determined based on the EMG extracted feature for (a) tibialis anterior and (b) gastrocnemius. The FSR was correlated with the EMG muscular activity as prescribed by Equation (6). The cross-correlation results of the FSR and EMG signals are plotted in Figure 21 for the tibialis anterior and the gastrocnemius respectively. As illustrated, the tibialis anterior cross-correlation maximum is in the origin with FSRs, indicating that the tibialis anterior is activated for heel strike during physiological gait. Similarly, the gastrocnemius cross-correlation maximum is in the origin with FSR\({}_{0}\), indicating that gastrocnemius is activated for toe-off during physiological gait. On the other hand, cross-correlation maxima outside the origin indicates that muscular activity occurred before/after FSR activation., e.g., pressure is read on FSR\({}_{0}\) only after activity on the tibialis anterior-motivating the shift of the R\({}_{\text{FSR0,TA}}\) maximum from the origin, whereas FSR5 reads pressure before gastrocnemius activity--motivating the shift of the R\({}_{\text{FSR5,GC}}\) from the origin. Figure 21: Cross-correlation of the FSRs to the (**a**) tibialis anterior and the (**b**) gastrocnemius. The cross-correlation results plotted in Figure 21 enable the formulation of the gait map listed in Figure 17.0 Indeed, the cross-correlations plotted in Figure 21 illustrate the interdependency of the investigated plantar pressure point with muscular activity during gait. On the cross-correlation plots, we have identified the lags corresponding to the middle of each gait cycle. Then, we have compared the cross-correlation function magnitude to a threshold level equal to 0.75 of the cross-correlation maxima, having the 0.75 fraction determined empirically. Cross-correlation magnitudes larger than the threshold account correlation of the plantar pressure with the muscle in the respective gait cycle, i.e., logical '1' in the gait map, whereas cross-correlation magnitudes below the threshold level account for lack o correlation, i.e., logical '0' in the gait map. The gait map formulation process, according to the explanation beforehand, is depicted in Figure 17.1