*2.3. Data Analysis*

The force data from the first to fifth sensors in the static and dynamic trial were calculated, respectively. In terms of static standing, the average of the force of static standing for five seconds was divided by the body weight. During analysis, this study calculated several indices. First, the average normalized force of each sensor for five seconds. Second, this study viewed the third sensor as the center column of the arch, which divided the arch into the medial arch and lateral arch and the third sensor also contributed both the medial side and lateral, the medial arch (the sum of the average force of the fifth sensor, the fourth sensor, and the third sensor was divided by two), and the lateral arch (the sum of the average force of the first sensor, the second sensor, and the third was divided by two). Third, the first three sensors (the sum of the first, the third, and the fifth) and the five sensors were calculated.

In terms of the dynamic trial, three successful gait trials were collected, and the maximum value of each gait of each sensor, the maximum of the sum of the medial arch in Equation (1), the average force of the lateral arch in Equation (2), the maximum of the sum of the first three sensors, and the maximum force of five sensors were calculated.

$$\text{Max}\left(\text{Sensor } \dots \text{Sensor } 4 + \frac{\text{Sensor } 3}{2}\right) \tag{1}$$

$$\text{Max}\left(Sensor \, 1 + Sensor \, 2 + \frac{Sensor \, 3}{2}\right) \tag{2}$$

All the force data calculated in this paper were normalized by their own body weight (kgf/kg) to minimize the effect of the individual difference.
