## 3 Results and Discussions
Passive mechanisms refer to the ones that have no accurate control of the patient's movements; they provide only a limited number of rehabilitation exercises and cannot be controlled in real-time. The proposed design has the advantage over several other models due to the increase in the ROM of each articulation on the index finger. It has a better ROM than most rehabilitation gloves shown in Table 3; only the work performed in [14] has equal ROM at PIP articulation. This increase in the ROM is, in part, thanks to the use of a mechanism that used virtual centers, which can be observed in Figure 1(Om, Od) and Figure 2(Op). Further, the 3D design produced by the parametric model contributes to the maximum ROM angles for each patient. The use of virtual centers made it possible to avoid a more cumbersome design. The use of virtual centers would allow for a more versatile rehabilitation glove in the future, as the only way there could be a DOF for each finger at the coronal plane is by using these virtual centers because the MCP articulations are contained within the palm's muscles. Therefore, it is impossible to use an independent hinge on each MCP articulation. The type of mechanism used to transmit motion in this work, mechanical linkages with cams, also has advantages over other mechanisms used in different investigations. This work's mechanism can possibly transmit motion during the contraction and extension motions of the finger using the same mechanical elements; in contrast, a cable-driven mechanism, such as in [14], cannot do this. Compared to soft robotic gloves such as [34] or cable-driven mechanisms [14], which cannot assure a stable position of the fingers, the design proposed here is rigid, thus having more capability in keeping finger location consistent. Some gloves use rigid bar mechanisms [33], but these designs, unlike those proposed here, are often bulky and have to use hinges located at the physical finger's articulations. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**ROM (Degrees)**} \\ \hline \multirow{2}{*}{**Work**} & **Single/Double Action** & \multirow{2}{*}{**MCP**} & \multirow{2}{*}{**PIP**} & **DIP** & **Transmission Mechanism** & \multirow{2}{*}{**DOF**} \\ \hline
[20] & Double & 55 & 65 & N/A & Linkage & 1 \\ \hline
[33] & Single & 50.7 & 90 & 61.6 & Linkage & 0 ** \\ \hline
[14] & Single *** & 49 & 90 & 50 & Cable & 1 \\ \hline
[34] & Single & \multicolumn{3}{c}{250 *} & Compliant & 1 \\ \hline
\begin{tabular}{c} Present \\ work \\ \end{tabular} & Double & 90 & 90 & 85 & Linkage & 2 \\ \hline \hline \end{tabular}  
* The 250 degrees of ROM are distributed within the three joints. ** It has 0 DOF because the system is completely passive. *** It has an extension but only passive.  
\end{table} 
Table 3: Comparison between different works and the one presented in this document. Concerning the number of DOFs used in this work, two were chosen because this allows for replicating most of the finger's natural movements on the sagittal plane. In comparison to systems that have only one DOF for each finger, such as [14; 20; 33; 34], there is much more variety in exercises that this mechanism can replicate. While using one DOF for each finger allows only a single curve to be followed, using two DOFs allows for an entire family of curves that live on two dimensions, opening the possibilities of rehabilitation exercises the patient could perform. These work areas are personalized through the parametrization model, and thus each patient has their own work area, contrary to most rehabilitation gloves in existence, which have just one curve (in the case of just one DOF) or the work areas are fixed. The work areas for each subject can be seen in Figure 7. These work areas represent the universe of points that the tip of the patient's finger can take; each patient has a whole family of curves that live within this space, and all these curves represent a broad range possibility of rehabilitation exercises.