## 3 Results
### Experimental Evaluation of the Finger Module Prototype  
Given that the project is currently in the preliminary design phase, the decision to perform a mechanical test on the compliant dorsal structure and on the assembled finger module was motivated by the need to evaluate the most appropriate manufacturing configuration for the compliant dorsal structure and bending behavior of the phantom on which the exoskeleton finger module will be worn. The primary objective of this test was to quantify the displacement and the force required to achieve full flexion when using the finger module prototype. The module was designed for a finger length of 77.5 mm (corresponding to the index finger of a 12-year-old children). According to this measure and considering the results of the mechanical characterization, a prototype of the index finger module was developed, including the following components: guidance rings with diameters of 17.5 mm for the proximal phalanx and 12 mm for the middle phalanx (both with a thickness of 3 mm) and compliant dorsal links consisting of 3 cells each, for both the proximal and distal pairs of anchor points. The prototype was functionally tested to derive information on the cable stroke and force necessary to reach a complete finger flexion. Figure 7 represents the relationship between the applied force and the cable displacement during finger flexion. The graph displays the mean force curve (dashed red line, Figure 7) along with the corresponding standard deviation (shaded blue area). A progressive increase in force is observed as the cable displacement increases, indicating that the system requires a greater force to achieve full flexion. The trend is not perfectly linear but exhibits oscillations along the curve, which can be attributed to vari  
Figure 7: Mean force curve graph of the complete flexion of the exoskeleton, highlighting the standard deviation. The graph displays the average force from the conducted experiments as a dashed red line, with the light blue shaded area representing the standard deviation across tests. ations in contact points, friction phenomena in the utilized phantom, and, in particular, the progressive engagement of joints, as illustrated in Figure 7. The recruitment of each joint is indicated by a change in the concavity of the curve. Moreover, the compliant dorsal structures introduce additional resistance upon activation, influencing the recorded force profile. The total displacement required for complete flexion was determined to be 45 mm. The standard deviation remains relatively low in the initial displacement, suggesting good repeatability in this phase. However, as displacement increases, data dispersion grows, indicating a slightly higher variability in the system response. This difference may be attributed to friction variations between trials, which affect the traction forces required during finger flexion. A second test was carried out with the same experimental setting to test static behavior of the prototype. The cable stroke to reach a complete finger flexion was divided into five intervals (9 mm each) performing five trials for each phase. A total of 25 force-displacement points were obtained, from which a box-plot was generated to highlight the variability in the force required for system engagement at different level of cable stroke, as shown in Figure 8.  
The box-plot shows a progressive increase in force as displacement increases, confirming that the system requires greater effort as flexion progresses. In the first two stages (9 mm and 18 mm displacement), the force exhibits limited variability, with relatively close medians and narrow whiskers. However, from 27 mm onward, data dispersion increases significantly, indicating greater variability in the system response. At 36 mm and 45 mm displacement, the largest force fluctuations are observed, with a wider distribution and the presence of outliers.