# Enhancing the Perceived Quality of a Vehicle Sliding Door Inner Handle Concept Design
## 4 Discussion  
Ensuring that the inner handle is well-designed and strategically positioned can significantly enhance the overall usability and accessibility of sliding doors, leading to increased user satisfaction and efficient door operation. The outcomes of our study reveal that a single handle, rotatable to both sides, is the output of the PQ approach (Figure 7). The team designed crank movements to provide technical requirements aligned with the handle movement. The system uses a crank lever to rotate the handle movement with minimum effort.  
\begin{table}
\begin{tabular}{c l l} \hline \hline
**No** & \
\begin{tabular}{l} **Releasing the Door from the Lock** \\ **When It Is Fully Closed/Open** \\ \end{tabular} &
\begin{tabular}{l} **Slide The Door and Lock to Close/Open the Door** \\ \end{tabular} \\ \hline
7 & Pull passenger car type handle & Handle \\
8 & Pull passenger car type handle & Handle and opening closing system together \\
9 & Pull passenger car type handle & Keep opening/closing system \\ \hline \hline \end{tabular} The team created a Taguchi orthogonal array design of nine combinations using Minitab 17 and shared it in Table 7.  
\end{table}
Table 6: _Cont._  
Figure 7: Basic design of unique sliding door inner handle to open and close.  
The team created a virtual prototype of the proposed handle (Figure 8). The same handle design is validated virtually in lower and upper positions, as they are crucial technical requirements due to the QFD table. The virtual validation is prepared using 3D CAD models, integrating Siemens Jack virtual human modeling, establishing a team to evaluate virtually, defining criteria for validation, and reporting the results. CAD models are prepared, and Siemens Jack virtual human modeling is performed (Figure 9). This step helps assess how real users of different body types, postures, and movement capabilities interact with the product. Then, a jury of 10 individuals is invited to validate virtually according to the QFD table CRs list, and the customer's posture is added to the validation criteria, and all are shared in Table 8. The jury consists of automotive experts working on part design.  
The jury discussed that the movement of the arm when opening and closing the door from a completely open position is uncomfortable; the handle position can only be reached by twisting the customer's body backward and awkwardly bending the arm (Figure 4). The maneuver becomes even more uncomfortable if three people sit on the rear seats, reducing the space to turn back and grab the handle. Furthermore, during the opening phase, it may be necessary to rotate the customer's body further to avoid touching the door parts, such as seals with the elbow. The jury agreed to fix the door handle in the lower area of the sliding door to help with arm movement. The visibility of the handle is controversial: the handle is visible, but the hand and arm positions are not comfortable enough to open the door in the upper position of the handle. A standard solution in vehicles is to locate the sliding door handle on the upper side of the door. The jury evaluates the handle reachability and postures better during the opening in the upper position. However, the overall score for the opening is higher concerning the lower position (Table 8). For closing the door, the rest of the eight scores of the usability criteria are higher than the lower position. The jury agreed that the lower position was preferable. Having a unique part for opening and closing the door and assembling it to the lower position of the door are the final decisions.  
The design and positioning of sliding door inner handles is a crucial aspect of user experience and functionality, as they are the primary means of interacting with and operating these doors. This study suggests that a well-designed and strategically positioned sliding door handle can contribute to a heightened sense of perceived quality, thereby enhancing the user experience.