Aerospace Instrument-Making Annotation << Back Active Fail-Safe Attitude Control of Spacecraft Kupriyanov A.O., Zhu Long, Wang Zeyu, Liu Yixin, Neusypin K.A. In this paper, an active fault-tolerant algorithm for spacecraft (SC) attitude control is developed. The proposed algorithm is capable of detecting the occurrence of actuator malfunction in the presence of external disturbances. At the same time, a connection is established between the malfunction and the system states by means of an auxiliary variable, which allows indirectly assessing the overall malfunction. After completing the identifi cation of the malfunction with a certain degree of accuracy, the system switches from the PD controller to the fault-tolerant controller using a backstepping-based method to adapt to the actuator malfunction. The stability of the closed system using this algorithm is analyzed using the Lyapunov function. The efficiency of the algorithm is shown by the results. Keywords: Fault-tolerant control; spacecraft attitude control; fault detection; fault assessment. DOI: 10.25791/aviakosmos.8.2025.1496 Pp. 03-12.