## 3 Model Development and Validation
### Data Analysis  
Using IBM SPSS Statistics 20 software, the collected backrest and seat pressure data were subjected to a Kolmogorov-Smirnov normal distribution test with several related samples, such as subjective rating data. After the test, both backrest and seat pressure \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Variables** & \
\begin{tabular}{c} **Regression** \\ **Coefficient** \\ \end{tabular} & **Variables** &
\begin{tabular}{c} **Regression** \\ **Coefficient** \\ \end{tabular} \\ \hline Gender & \(-\)0.107988 & Hip object pressure & 0 \\ Height & 0.087529 & Hip peak object pressure & 0 \\ Weight & 0.0647327 & Hip peak contact pressure & 0 \\ Back object pressure & 0 & Hip peak strength & 0 \\ Back peak object pressure & \(-\)0.0054094 & Hip contact area & 0.0211677 \\ Back peak contact pressure & \(-\)0.0058324 & Hip contact pressure & 0 \\ Back peak strength & 0 & Hip strength & 0.8117908 \\ Back contact area & 0.0042048 & & \\ Back contact pressure & 0.3892448 & & \\ Back strength & 0 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: LASSO regression coefficients. Figure 5: Standard cushion and backrest pressure two-dimensional diagram. data were found to not obey the normal distribution situation. Therefore, this paper selected a non-parametric test to analyze the data, using the Friedman test for the mean and standard deviation of the three backrest tilt angles under the two pitches. The pressure distribution and two posterior comparisons for a seat and pedal pitch of 63 cm are shown in Tables 3 and 4. The body pressure distribution reflects the contact effect between the human body and the seat, which can better characterize the body pressure distribution characteristics. As shown in Table 3, when the distance between the seat and the footrest is 63 cm, the peak back object pressure is the highest when the backrest angle is \(110^{\circ}\), at 32.81 \(\pm\) 1.67 kPa; the peak back object pressure is not much different from that at \(110^{\circ}\) when the backrest is \(120^{\circ}\), at 32.03 \(\pm\) 2.16 kPa; the peak object pressure is the lowest when the backrest angle is \(100^{\circ}\), at 30.71 \(\pm\) 2.15 kPa. Back peak object pressure is the highest point or peak in the pressure distribution of the human back; the human body in different sitting, standing, or lying postures is subjected to different pressures. Measurement and analysis of the back peak object pressure can help to understand the impact of different backrest angles on the back force, especially the pressure distribution on the spine and muscles. Usually, reducing the peak object pressure on the back helps to improve the comfort of the human sitting posture. As shown in Table 4, a post hoc two-by-two comparison of the three backrest inclination angles at 63 cm spacing showed significant differences in peak back object pressure and peak hip object pressure for each of the two different angles at the 95% confidence interval. As shown in Table 3, the peak contact pressure on the back at the seat and footrest distance of 63 cm and backrest tilt angle of \(120^{\circ}\) is the largest, 34.55 \(\pm\) 2.05 kPa; the peak contact pressure at \(100^{\circ}\) is the smallest, 31.13 \(\pm\) 2.13 kPa; at \(110^{\circ}\), peak contact pressure is in the middle, 33.98 \(\pm\) 2.14 kPa. Peak contact pressure is the pressure on the seat cushion and backrest. The average of the four values adjacent to the maximum value is given by this indicator, which reduces the pressure cushion surface wrinkles caused by the abnormally excessive pressure on the results. In general, the peak contact pressure shows a correlation with the subjective evaluation of overall comfort, and the larger the peak contact area, the