High-Reliability and High-Precision Braking and Capture Control Technology of Tianwen-1 Probe

Abstract

The Tianwen-1 probe, used in China’s first Mars exploration mission, features multiple flight phases, numerous spatial pointing constraints, and complex working modes. During the braking and capture process, it faces challenges such as uplink or downlink command delay, unique capture window, post-control “occultation”, short-time significant change in speed increment, and interference caused by low-frequency and low-damping solid–liquid flexible coupling oscillations. Therefore, high reliability, high autonomy, and high precision are required for the braking and capture process. As the executor of braking and capture control, the GNC (guidance, navigation, and control) subsystem of the orbiter employs an online orbit control strategy reconstruction method based on arc loss compensation to realize high reliability, the main engine anomaly recognition and a seamless switching scheme to realize high autonomy, and the attitude–orbit coupling control algorithm with thrust direction compensation to realize high-precision speed increment control. According to the on-orbit flight validation of the Tianwen-1 probe, the GNC subsystem of the orbiter has completed the braking and capture control task reliably and autonomously with millimeter-per-second-level accuracy, effectively ensuring the successful execution of subsequent landing and patrol tasks. This paper analyzes the online orbit control strategy reconstruction method, anomaly recognition and seamless switching method, and thrust vector control method of the braking and capture process and offers valuable insights for future interplanetary exploration flight control.