Design of the Solar tracker using high order sliding mode

In order to observe high-resolution images of the Sun, it is desperate for more precise tracking of the moving trajectory of the Sun. The high order sliding mode controller, which is invariable to the disturbances of the system, is proposed to realize high-precision control for the designed Solar tracker. By analyzing in detail the structure of the tracking system, we establish an accurate mathematical model for control calculation. Because of the high order sliding mode needs all system states be observable, an exact differentiator is suggested for the unmeasured states in the tracking system, which makes it possible to construct a high order sliding mode controller to eliminate the chattering phenomenon in traditional sliding mode. Finally we make a simplified prototype to testify the performance of the proposed approach. The experimental results show that the proposed approach can obtain high-precision tracking performance, which can satisfy the high-resolution observation of the Sun.