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This brief presents a finite‐time output feedback control scheme for the velocity‐free attitude stabilization of rigid spacecraft under inertia uncertainties and disturbances. Note that either the finite‐time velocity observer or the finite‐time extended state observer contains the control torques, which makes the transient performance of the observer‐based output feedback control difficult to be regulated. Alternatively, the filter‐based output feedback control can overcome such problem naturally since the finite‐time velocity filter does not involve the control torques in its structure. Different from the existing finite‐time velocity filters, a finite‐time extended state filter is introduced in this work to estimate the pseudo angular velocity and total uncertain item simultaneously. Then, the developed controller is synthesized based on the recovered information, which does not require the angular velocity for feedback and has the excellent uncertainty and disturbance compensation capability. The global finite‐time stability of the resultant closed‐loop system is evaluated through the Lyapunov direct methodology and homogeneous system theory. Lastly, comparative simulations are carried out to examine the efficiency and superiority of the presented control scheme. [ABSTRACT FROM AUTHOR]

In this paper, we present an adaptive control strategy for the output-constrained attitude tracking of rigid spacecraft under unknown inertia and disturbances. The designed controller is recursively constructed under the framework of the backstepping method, which involves an auxiliary stabilizing law and a practical control law. In the auxiliary stabilizing law design, the log-type barrier Lyapunov function (BLF) is embedded to tackle the time-varying output constraints. In addition, in the practical control law design, the element-wise parametric adaptive laws are adopted to identify the unknown inertia and disturbances by introducing a linear mapping operator. The stability evaluation indicates that the overall closed-loop system is semi-globally uniformly ultimately bounded (SGUUB) and all error variables can eventually regulate to the minor fields about zero. Meanwhile, the spacecraft attitude tracking errors can be preserved in the preassigned output constraints. Lastly, the efficiency and strong robustness of the presented control strategy are demonstrated through competitive simulations. [ABSTRACT FROM AUTHOR]

In this paper, a neural adaptive fault-tolerant control scheme is proposed for the integrated attitude and position control of spacecraft proximity operations in the presence of unknown parameters, disturbances, and actuator faults. The proposed controller is made up of a relative attitude control law and a relative position control law. Both the relative attitude control law and relative position control law are designed by adopting the neural networks (NNs) to approximate the upper bound of the lumped unknowns. Benefiting from the indirect neural approximation, the proposed controller does not need any model information for feedback. In addition, only two adaptive parameters are required for the indirect neural approximation, and the online calculation burden of the proposed controller is therefore significantly reduced. Lyapunov analysis shows that the overall closed-loop system is ultimately uniformly bounded. The proposed controller can ensure the relative attitude, angular velocity, position, and velocity stabilize into the small neighborhoods around the origin. Lastly, the effectiveness and superior performance of the proposed control scheme are confirmed by a simulated example. [ABSTRACT FROM AUTHOR]