## 1 Introduction  
In recent years, the advanced spacecraft control technology has been able to achieve more and more functions, and the control technology in many harsh environments has also been developing rapidly. They meet many new needs including satellites and hypersonic vehicles: anti-interference, anti-interception, super maneuver, etc. [1; 2; 3; 4]. Fault-tolerant control (FTC) can also ensure spacecraft stability when the faults occur [5; 6]. However, space exploration is increasingly diversified, and the engineering requirements for control technology are far from being met, such as multi-channel multi-type concurrent fault compensation, variable structure dexterity avoidance, etc. The purpose of this paper was to design an improved adaptive FTC scheme so that the spacecraft with saturation and multiple faults can realize flexible variable structure stability control and meet the design requirements of a new-generation spacecraft. New progress has been made in spacecraft control technology that satisfies tracking stability in complex environments and missions [7; 8]. In [9], disturbances in the hypersonic re-entry vehicles were revisited, a disturbance effect indicator was defined to demonstrate the pros and cons of the disturbances' influence on the system, and based on the disturbance estimation, a disturbance estimation-triggered control scheme for the attitude tracking was established. In [10], the proposed control law was able to guarantee the prescribed transient and steady-state behavior for both attitude and angular velocity errors in the presence of bounded external disturbances. In [11], a novel fixed-time convergent nonsmooth backstepping control scheme was proposed for flexible hypersonic vehicles via augmented sliding mode observers to overcome the uncertainty and measurement noise. In [12], to track the desired velocity and the desired altitude, a data-driven supplementary control approach with adaptive learning capability was proposed for the rigid aircraft controller based on action-dependent heuristic dynamic programming. However, the above schemes seldom considered actuator failure and saturation, so their algorithm reliability is difficult to guarantee. This paper designed an anti-saturation FTC scheme on this basis to solve the above problem. Anti-saturation control technology can normally control the system to complete the task when the actuator is limited, so it is widely used in spacecraft with a strict upper limit of payload [13; 14]. In [15], a low-complexity adaptive tracking control strategy for a class of pure feedback nonlinear spacecraft systems was developed in the presence of completely unknown non-affine nonlinearities, full state constraints, and input saturation constraints. In [16], to improve the agent's solution quality during a search, an agent soft search constraint was designed, setting the soft search constraint filters from the obviously inferior solutions, thereby improving the solution quality of the spacecraft. In [17], a combination of feedback linearization and disturbance observer-based control was adopted for the design of a state-feedback controller that regulated the velocity and altitude of spacecraft subject to constrained inputs. However, the above methods did not consider the fault and flexible active variable structure mode, and the reliability and environmental adaptability are insufficient. On this basis, this paper studied variable structure adaptive FTC to realize the dexterous maneuvering FTC of anti-interception. Spacecraft FTC is a relatively popular branch of space control technology, and due to borrowing the mature information technology of high-speed trains, it is a field with rapid progress and more achievements in recent years [18; 19; 20; 21]. In [22], a passive FTC scheme was proposed for the full re-entry trajectory tracking of spacecraft in the presence of modeling uncertainties, external disturbances, and actuator faults. In [23], a finite-time FTC scheme with command filtering was applied to the general nonlinear uncertain systems.