Design of sliding mode control law in space parking

This paper discussed the application of sliding mode control in space parking and aimed to the movement control in the orbital plane. We established the relative motion equations which can be transformed into state equations, then designed the sliding mode surface and adopted constant speed update law to ensure the arriving conditions of the sliding mode. Based above, we deduced the sliding mode control law of the space near relative motion. Through coupling analysis, we found that the motions in two directions in the orbit plane are decoupled when using the control law in this paper, and the problem was simplified to make it easier to be solved. But the precise sliding mode control is difficult to be achieved because the thrust restriction of the actual engine and it working modes and that maybe cause severe tremble during control process. In this case, we proposed an approximate sliding mode control law to eliminate tremble, then analyzed the robustness of the control system. And at last we verified the validity and availability of the control method in this paper.