Robust fault-tolerant tracking control design for spacecraft under control input saturation.

Area of Science:

• Aerospace Engineering
• Control Systems Theory
• Robotics

Background:

• Spacecraft attitude control is critical for mission success.
• Traditional fault-tolerant control methods often require explicit fault detection and isolation.
• Actuator failures, input saturation, and external disturbances pose significant challenges to spacecraft control.

Purpose of the Study:

• To propose a continuous, globally stable tracking control algorithm for spacecraft.
• To address challenges including unknown actuator failure, control input saturation, inertial matrix uncertainty, and external disturbances.
• To develop a fault-tolerant controller that does not require prior knowledge of actuator faults.

Main Methods:

• Variable structure control (VSC) design.
• Dynamic adjustment of a single controller parameter.
• Lyapunov stability analysis.
• Utilizing singularity-free quaternion representation of spacecraft dynamics.

Main Results:

• The proposed controller demonstrates fast and accurate response to bounded disturbances.
• It exhibits robustness against partial loss of actuator effectiveness.
• The controller explicitly accounts for control input saturation and inertial matrix uncertainty.
• Numerical simulations confirm successful high attitude performance under various adverse conditions.

Conclusions:

• The developed VSC-based algorithm provides robust and stable spacecraft attitude tracking.
• It effectively handles actuator failures and control saturation without explicit fault diagnosis.
• The controller ensures asymptotic convergence of attitude and angular velocity errors, enhancing mission reliability.