## 2 Materials and Methods
### Methodology of Experimental Research  
Experimental research was performed using the original workbench and acquiring real operating data from sensors when a person walks with shoe insoles equipped with sensors in different situations. These situations were used for data-flow management and network functionality assessment. \begin{table}
\begin{tabular}{c c c} \hline
**Property** & **Proposed Method** & **Alternative Method** \\ \hline The extent of the & Slave boards are synchronized to each & Slave boards are synchronized to each \\ system synchronization & other and to the master board & other but not to the master board \\ The frequency of the & A synchronization message is sent at every & The synchronization message is sent only \\ synchronization message & data acquisition cycle & at the start of a data-logging session \\ The activity of slave boards & Slave boards stay idle unless a message is & Slave boards are constantly collecting and \\  & received ordering to collect and send data & sending data to the master \\ The activity of the master board & Initiating data acquisition, processing the & Processing the incoming data (including \\  & incoming data, exporting data & data pairing by timestamp), exporting data \\ Timestamp generation & By the master board & Each slave board separately \\ Conditions of data being & Data arrives on the same data & Data timestamps match \\ considered synchronized & acquisition cycle & Data timestamps match \\ \hline \end{tabular}
\end{table} 
Table 2: A comparison of the proposed and the alternative methods of synchronization. Figure 4: Alternative local network operation in the data-acquisition process diagram. A series of measurements were performed to evaluate the real system latency from the command to collect data to data arrival in the master microprocessor memory. An oscilloscope was used as a key measurement tool in a study aiming to define the characteristics of data-transmission delay in a system that includes sensors and two ESP32 microcontrollers. The oscilloscope was connected to the power supply and configured with time-scale and trigger-level settings to capture signals. The first probe of the oscilloscope was connected to the pin of the first slave ESP32, which receives data from the sensor. The second probe was connected to the pin that transmits data from the master ESP32 to the cloud storage. After adjusting the equipment, the software was run on the master ESP32, which read the data from the sensor and transferred it to the cloud storage. The oscilloscope successfully captured the signals, allowing you to observe the dynamics of the signals visually. Using the oscilloscope measuring function, the time between the signal change on the first channel (from the sensor to the first ESP32) and the signal change on the second channel (from the main ESP32 to cloud storage) was defined. The sensors must be individually calibrated for each patient before use. Calibration is carried out by a preprogrammed button when the patient stands still in one position. An additional restart function and clearing the calibration on the programmed buttons were also implemented. Calibration of the sensors takes into account the peculiarities of the human body's weight distribution and the position of the patient's feet concerning the sensor's sensitive area. The calibration procedure defines a baseline for evaluating the human body's mass distribution and allows for minimizing additive and multiplicative measurement errors. Internal data preprocessing applying compensation coefficients obtained from calibration is a straightforward mathematical procedure, and, compared to data-transfer tasks, it takes a negligible amount of time. In the practical experiment carried out, a setup with insoles for both the left and right feet, each embedded with three pressure sensors for three main foot pressure points (conditional division into three main areas, the heel and the left and right parts of the ball of the foot), a gyroscope and an accelerometer, was implemented.