Event-Triggered Fixed-Time Control for Satellite Attitude with External Disturbances

This paper proposes an event-triggered fixed-time control strategy to stabilize the satellite attitude under external disturbances. The approach integrates a fractional-order proportional-derivative (PD) controller to achieve faster convergence and enhanced robustness compared to sliding-mode controllers. A fixed-threshold event-triggered mechanism is introduced to reduce communication overhead while maintaining system stability. The controller ensures fixed-time convergence of the angular velocity and attitude quaternion of the satellite to a small region around the equilibrium point, even in the presence of disturbances and uncertainties of the model. The design leverages a Lyapunov-based stability analysis to guarantee global asymptotic stability and fixed-time convergence. Numerical simulations validate the effectiveness of the proposed controller. The event-triggered mechanism significantly reduces the frequency of signal update, optimizing the use of communication resources. The proposed controller retains the simplicity of PD control while incorporating the advantages of fixed-time control, making it suitable for practical engineering applications. The simulation results confirm that the controller outperforms traditional PD and fixed-time controllers in terms of convergence speed, robustness, and resource efficiency. This approach provides a practical solution for satellite attitude control systems requiring rapid response and minimal communication overhead.