Abstract:  Failure and external disturbance during the process of Mars entry inevitably degrade the performance of Mars entry guidance and control algorithms.The backstepping method was used to design the attitude fault-tolerant control algorithm for Mars entry, which is not sensitive to changes in the moment of inertia information. First, the derivative of the virtual control law was regarded as an interference quantity, and the adaptive technology was used to compensate it, which avoids the defect of differential explosion in the traditional backstepping method. Meanwhile, the saturation function was explicitly introduced in the control design process to ensure that the control law could still keep the attitude of probe stable in the presence of input saturation. Finally, the "Mars Science Laboratory" probe was used as a model for numerical simulation verification. The results show that the controller can achieve the accurate attitude tracking under input saturation,uncertainty of inertia and the actuator failure conditions.

Key words: Mars entry, attitude tracking, fault-tolerant control, input saturation, inertiafree