Mars Ascent Vehicle Tracking Guidance Law Design Added by Sliding Mode Control in the Coasting Phase

This paper studies the design of the guidance law for the nominal trajectory tracking of the Mars ascent vehicle. First of all, the nominal trajectory of the flight process is optimized according to the needs of the mission. Secondly, for the ascending phase, the speed loss caused by the atmosphere in the coasting phase is considered, and the altitude and speed at the apoapsis are corrected. The vehicle is guided by the closed-loop control of the angle of attack and the angle of sideslip. In addition, for the problem of large trajectory tracking error caused by guidance only in the ascending phase, the sliding mode guidance law of the coasting phase is designed. Finally, through numerical simulation, it is verified that the designed guidance law can improve the tracking accuracy and greatly reduce the fuel consumption required for the rounding into orbit.