## 3 Results
### Testing the Prosthesis's Movement  
The behavior of the self-adjusting transtibial prosthesis during movement was evaluated using a Digital Image Correlation (DIC) system. The DIC method is a non-contact, non-destructive measurement technique that involves calculating 2D or 3D coordinates from a series of images obtained through recording with two cameras, which allow for the determination of 3D coordinates [36]. In order to facilitate the calculation of 3D displacement values of the self-adjusting transtibial prosthesis by means of this method, the 3D coordinates of the points of interest were determined by subtracting the 3D coordinates of each recorded stage over time from those of the reference stage. The determination of the displacement during the alignment process of the mannequin limbs, subsequent to simulating the growth of the non-prosthetic limb, was determined using the ARAMIS 3D DIC System, Teledyne Dalsa 12M (Carl Zeiss, Jena, Germany). The system ran the PONTOS software version 6.3.1-1 (PONTOS Software GmbH, Jena, Germany). The main technical characteristics of the DIC system are highlighted in Table 6.  
The PONTOS Live system operates on the principle of triangulation and is capable of point-by-point analysis of components made from various materials, with dimensions ranging from a few millimeters to several meters [36; 37]. Using the stereo cameras mounted in front of the prosthetic mannequin, the 3D coordinates of the reference points, represented by markers (standardized dimensions), were obtained. These markers were strategically positioned on the self-adjusting transtibial prosthesis and on the lower limbs of the mannequin. The DIC system was strategically positioned in front of the stand, consisting of the mannequin fitted with the self-adjusting transtibial prosthesis. This ensured that the angle and distance between the cameras were optimal for capturing all the necessary details during the analysis. The measurement equipment configuration was designed to maximize the accuracy of capturing the movements performed by the prosthesis, and consequently, by the lower limbs. Figure 9: Overview of the experimental setup for automatic LLD detection and compensation (1—anatomical mannequin positioned seated; 2—valid right lower limb; 3—amputated lower limb with prosthetic EPM; 4—base plate; 5—Master component; 6—Slave component; 7—12 V power supply). (**a**) Front view. After the proper positioning of the DIC system, as shown in Figure 10a, the equipment was calibrated to ensure the accuracy and reliability of the measurements that were to be performed. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameters** & **Technical Specifications** \\ \hline Camera sensor & CMOS \\ \hline Camera resolution & 4096 \(\times\) 3000 pixels \\ \hline \multirow{6}{*}{Frame rate} & 130 fps @ full resolution \\  & 240 fps @ 1/2 image height \\  & 450 fps @ 1/4 image height \\  & 43 fps @ 2496 \(\times\) 2096 pixels (5 M Mode) \\  & 25 fps @ full resolution \\ \hline Illumination & Tracking Spots (markers) \\ \hline \multirow{6}{*}{Measuring area (mm)} & Frame 150: 30 \(\mid\)55 \(\mid\)90 \(\mid\)140 \\  & Frame 300: 140\(\mid\)200 \(\mid\)300 \(\mid\)550 \\  & Frame 600: 650 \(\mid\)1200  
The calibration process synchronized the stereo cameras, rectified optical errors to prevent the introduction of artifacts into the captured images, and facilitated the repeatability of the measurements. Calibration was performed according to the contrast, luminosity, and temperature requirements recommended by the manufacturer of the DIC system. Ultimately, the PONTOS software was able to provide the mean values of the 3D coordinates (X, Y, and Z) for each marker placed on the transtibial prosthesis and the mannequin's limbs. These coordinates were automatically calculated based on the data captured by the DIC system, using advanced three-dimensional reconstruction algorithms.