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This paper investigates an attitude tracking control problem of spacecraft subject to actuator saturation and inertial uncertainties. Aiming at alleviating the negative effects of actuator saturation and parameter uncertainties, an adaptive prescribed performance attitude control scheme is proposed via exploring the reinforcement learning policy. By constructing a critic network and an action network, the approximations of the optimal objective function and the optimal control gains of the spacecraft attitude tracking error system are realized. A group of numerical examples is organized to validate the effectiveness and robustness of the proposed attitude control scheme with respect to actuator saturation and inertia uncertainties.

The trajectory tracking control of the quadrotor unmanned aerial vehicle (QUAV) is investigated. The aim of this paper is to develop a novel trajectory tracking control method considering model uncertainties and external disturbances with finite-time stability and prescribed performance of the attitude. Firstly, the trajectory tracking control system of the QUAV is decoupled into two subsystems, i.e., position and attitude subsystems, wherein, backstepping technique is used to design the position tracking controller. Then, to guarantee the tracking performance of the attitude subsystem, a finite-time convergent performance function is developed, and a prescribed performance attitude controller is devised via using integral barrier Lyapunov function thereafter. In the design process of the above two controllers, ESO is used to estimate and compensate multiple uncertainties and disturbances simultaneously. Moreover, the fractional state feedback and discontinuous phenomenon of the control law are directly avoided to achieve the finite-time convergence rate. Finally, an illustrative example is organized to verify the effectiveness of the proposed approach.

This paper investigates a low-complexity prescribed performance control approach for combined spacecraft with an unknown captured object in the presence of external disturbance. First, a prescribed performance function with appropriate parameters is selected for the filtered state variables involving the attitude and angular velocity. Then, a low-complexity robust prescribed performance controller is developed without any priori knowledge of the inertial information of combined spacecraft. This dramatically decreases the complexity of controller design for combined spacecraft with large uncertainty owing to the fact that the tedious identification of inertial property is avoided. Finally, an illustrative example is employed to validate the effectiveness of proposed control approach in terms of stabilizing the combined spacecraft.