# A Kinematic Model of the Shoulder Complex Obtained from a Wearable Detection System
## 4 Discussion
### Comparison of Collected Data with Result of Klopcar Kinematic Model
#### 4.1.2 Comparison of Collected Data in the Sagittal and Coronal Planes
The displacement variable quantity \(z(\phi)\) along the \(z\)-axis does not move with angle \(\phi\) values from \(0^{\circ}\) to \(30^{\circ}\), which matches \(z^{\prime\!li}\). When the elevation is from \(30^{\circ}\) to \(120^{\circ}\), the data increment is larger than \(z^{\prime\!li}\). Considering the experimental data obtained by our detection system, the motion of \(z^{\prime\!li}\) is somewhat delayed from \(30^{\circ}\) to \(120^{\circ}\). However, the displacements \(z(\phi)\) and \(z^{\prime\!li}\) are almost the same at an elevation of \(120^{\circ}\). In Figure 12a, the displacement variable quantity \(x^{\prime\!li}\) changes slightly with the angle \(\phi\), from \(0^{\circ}\) to \(40^{\circ}\). Then, as the angle increases from \(40^{\circ}\) to \(120^{\circ}\), the gradient decreases. The GH joint center displacement variable quantity \(x(\phi)\) along the \(x\)-axis moves slightly with the angle \(\phi\) from \(0^{\circ}\) to \(40^{\circ}\). The gradient and angle present a negative correlation from \(40^{\circ}\) to \(120^{\circ}\). The magnitude of \(x^{\prime\!li}\) is greater than that of \(x(\phi)\). Because the magnitude of \(x^{\prime\!li}\) is less than that of \(x(\phi)\), the movement law of \(x^{\prime\!li}\) is reasonable. In Figure 12b, the displacement variable quantity \(y^{\prime\!li}\) changes slightly in the initial stage, and the gradient of the curve decreases in the middle phase, the change in which is large. Then, the gradient of the curve rises slightly in the end. The GH center displacement variable quantity \(y(\phi)\) along the y-axis stays in the same position as the angle \(\phi\) changes from \(0^{\circ}\) to \(70^{\circ}\). The gradient of the curve decreases from \(70^{\circ}\) to \(110^{\circ}\), the change in which is very evident. From \(110^{\circ}\) to \(120^{\circ}\), the gradient of the curve does not have considerable change. Although the two curves differ in amplitude, the result is acceptable. In Figure 12c, the displacement variable quantity \(z^{\prime\!li}\) changes steadily with the angle \(\phi\), from \(0^{\circ}\) to \(20^{\circ}\). However, the change is very small. The increases in displacement variable quantity \(z^{\prime\!li}\) are first large and then small as the angle \(\phi\) changes from \(20^{\circ}\) to \(120^{\circ}\). The displacement variable quantity \(z(\phi)\) along the \(z\)-axis does not move with angle \(\phi\) values from \(0^{\circ}\) to \(30^{\circ}\), which basically matches \(z^{\prime\!li}\). When the elevation is from \(30^{\circ}\) to \(120^{\circ}\), the data increment is also larger than \(z^{\prime\!li}\). Although the motion of \(z^{\prime\!li}\) is somewhat delayed from \(30^{\circ}\) to \(120^{\circ}\), the trend is basically the same. Based on the above analysis of Figures 11 and 12, although the collected data in the sagittal and coronal planes were different from the comparative analysis of the Klopcar kinematic model, the trends are almost the same. The Klopcar kinematic model was the result of the synthesis of four planes, and this study is considered only at a single elevation plane and takes into account different experimental processing methods. This result is sufficient for daily exercise and the design of rehabilitation training equipment.