Observer-Based Disturbance Estimation for a Spacecraft Inertial Pointing Using Magnetic Torquers

Abstract

This paper proposes static attitude and rate feedback controllers with an observer-based disturbance estimation technique for the attitude control of spacecraft inertial pointing, using only magnetic torquers. Disturbances widely exist in real-world control systems and bring adverse effects to the performance of control systems. Since the disturbances cannot be measured directly, a modified nonlinear disturbance observer was applied to estimate the system uncertainty including unknown moments of inertia and external disturbances, and then to introduce feedforward compensation to cancel it. The numerical simulation results demonstrate that the proposed new control approach allows faster convergence of the closed-loop system to the desired equilibrium and better control efficiency under the lumped uncertainty.