## 3 Experiments and Results
### Guideline for Fabricating Pressure Sensors for Individual Applications
#### 3.2.2 Experimental Participant Information
2.4 Experiments according to the Application Process of the Lower Limb Movement Intention Detection System: Performing Six Locomotion Movements  
An experiment was conducted using the process presented in Table 5 in order to confirm the possibility of detecting the movement intention of the proposed pressure sensor system. This experiment was conducted in the following order. A standing position is presented in (1). It is intended to confirm the conversion time to start flat locomotion in the initial standing state in (2). Stairs are to be first recognized in the stair locomotion movements in (3) and (4), and then power is applied; pressure changes are confirmed by defining knee joint bending movements similar to stair climbing and weight application, with a posture similar to stair descending. The transition from a standing state to a sitting position is carried out, as shown in (5). The transition from a sitting position to a standing state is presented in (6). Figure 14 shows the results of pressure changes according to the proposed six locomotion movements. When the movement is switched from a standing state to a flat locomotion state, the load is removed, and the pressure drops below \(-50\%\) from the upper part of the rectus femoris. At the lower part of the rectus femoris, the weight of the prosthetic leg is concentrated. Then, it is possible to verify that the pressure change increases by more than \(50\%\) at the upper part due to the pressing of the inclined lower limb. During stair climbing, the result of performing the predefined knee joint bending movement appears. The upper part of the biceps femoris removes the pressing force acting on the outer wall of the socket, causing the pressure to drop to \(-100\%\). At the lower part of the biceps femoris, the pressing force increases, and the pressure rises to \(+50\%\). The lower part of the biceps femoris shows a decreasing pressure change in common but is divided into a decreasing result after rising and an immediate decreasing result. This difference is determined to be due to the individual user's habit of performing the knee-bending posture. In this case, it is not designated as a threshold value because it is difficult to identify a clear pressure change. During the stair descending movement, the result of performing the predefined intentional weight application movement appears. The weight application movement increases the pressing force, showing an elevated form in all four positions. \begin{table}
\begin{tabular}{l} \hline \hline (1) Standing \\ \hline (2) Level locomotion in a standing posture \\ \hline (3) Performing knee joint flexion in a standing posture (predefined posture for moving upstairs) \\ \hline (4) Load application in a standing posture (predefined posture for moving downstairs) \\ \hline (5) Sitting in a standing posture \\ \hline (6) Standing in a sitting posture \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Experimental process. It can be seen that the pressure rises to more than 50% in the upper part of the rectus femoris and 100% in the lower part of the rectus femoris and the biceps femoris, entering a saturated state. In the sitting movement, the lower limb is inclined in the front and lower directions, accompanied by knee joint bending. It can be seen that the pressure decreases to \(-100\%\) at the upper part of the rectus femoris, with an increase to +50% at the lower part of the rectus femoris caused by a large pressing force and an increase to +50% at the lower part of the biceps femoris due to a small pressing force. In the conversion movement from the sitting posture to the standing posture, the pressure change based on the sitting posture should be checked. Due to the low load on the lower part of the seated position, the sensors  
Figure 14: Experiment results according to 6 motions. in the upper position of the rectus femoris and the upper and lower positions of the biceps femoris represent a low-pressure condition of \(-50\%\).