# Development of a Lightweight Prosthetic Hand for Patients with Amputated Fingers
## 4 Results
### Experiment  
The experiment for performance verification of the prosthetic hand involved passive and active hand motions. Passive motions included palm movement and adduction/abduction motions. First,  
\begin{table}
\begin{tabular}{c c} \hline \hline \multicolumn{1}{c}{**Weight**} & 152.32 g (Except thumb) \\ \hline
**Overall size [length, width, thickness]** & [174 mm, 77 mm, 11 mm] \\ \hline \multirow{4}{*}{
\begin{tabular}{c} Finger sizes [length, width, thickness] \\ \end{tabular} } & Index finger & [83.7 mm, 14.8 mm, 11 mm] \\ \cline{2-3}  & Middle finger & [88.7 mm, 14.8 mm, 11 mm] \\ \cline{2-3}  & Ring finger & [83.7 mm, 14.8 mm, 11 mm] \\ \cline{2-3}  & Little finger & [73.7 mm, 14.8 mm, 11 mm] \\ \hline \multicolumn{1}{c}{**Degrees of freedom**} & 18 \\ \hline
**Active motions (The number of actuators)** & 4 \\ \hline \hline
**Passive motions** & 14 \({}^{\star}\) \\ \hline \multicolumn{1}{c}{**Joint coupling method**} & Tendon \\ \hline \multicolumn{1}{c}{**Adaptive grasping**} & Yes \\ \hline \multirow{2}{*}{\
\begin{tabular}{c} Grip Forces \\ \end{tabular} } & Maximum force: 6.460 N (at \(\eta=0\)) and 7.487 N (at \(\eta=90\)) \\ \cline{2-3}  & (for \(0\leq\theta\leq 65\) and \(\alpha=\beta=25\) in a finger module) \\ \hline \multirow{4}{*}{
\begin{tabular}{c} Ranges of Motion \\ \end{tabular} } & DIP joint & 0–90 \\ \cline{2-3}  & TCP joint & 0–90 \\ \cline{2-3}  & Adduction/Abduction & 0–15 \\ \cline{2-3}  & Adaptive grasping in PIP and MCP joints & 0–25 \\ \cline{2-3}  & Palm & 0–30 \\ \hline \multicolumn{1}{c}{**Finger/Grasp speed**} & Up to 185.8\({}^{\circ}\)/s at each phalanx \\ \hline \hline \end{tabular}  
* The number of passive motions realized using linear springs: 8, torsional springs: 4, and leaf springs: 2. DIP: the distal interphalangeal, PIP: the proximal interphalangeal, and MCP: the metacarpophalangeal.  
\end{table}
Table 2: Specifications of the developed prosthetic hand.  
passive motions were executed. Figure 9a,b show the palm movement and adduction/abduction motions, respectively. The initial configuration of the mounting part was set to 15\({}^{\circ}\) by leaf springs at each joint, as shown in Figures 2b and 9a. Furthermore, in the adduction/abduction motions, the index finger was rotated counterclockwise, while the other fingers (middle, ring, and little fingers) were rotated clockwise in the range from 0\({}^{\circ}\) to 15\({}^{\circ}\) (Figure 9b).  
Second, the practical applicability of the developed prosthetic hand was verified using diverse objects encountered in daily life. Objective motions, such as natural motion and self-adaptive grasping, were tested (Figure 10). In natural motion, the prototype was moved, as shown in Figure 10a. Because of the absence of external forces, each phalanx moved from 0\({}^{\circ}\) to 90\({}^{\circ}\). In addition, because the initial configuration of the palm was set to 15\({}^{\circ}\) at the two joints, slight interference was observed between the middle and ring fingers in the final configuration of natural motion (the red circle in Figure 10a). Self-adaptive grasping was tested with diverse objects (Figure 10b). In particular, the four fingers of the developed hand could maintain the grasping configuration while lifting the 1.36 kg dumb-bell. In all experiments, the developed prosthetic hand robustly grasped various objects.  
All motions including passive and self-adaptive grasping motions can be checked in supplementary video, and it is guided in Supplementary Materials.  
Figure 10: _Cont_.  
Figure 9: Passive motions in (**a**) palm movements and (**b**) adduction/abduction motions.