Regulation of Magnetically Actuated Satellites using Model Predictive Control with Disturbance Modelling

The problem of magnetic attitude regulation of low Earth orbiting satellites is addressed using model predictive control. This paper considers extending the current literature within this area by combining a standard predictive controller with a suitable disturbance model. For low Earth orbiting satellites the disturbances due to the external environment are very significant and consideration of these torques within the control law is imperative to obtain the best possible controller performance. In order to obtain an estimate of the external disturbance, a state estimator of varying complexity is used. This estimator initially assumes that the disturbances acting on the satellite remain constant with time, but this assumption is then improved to assume harmonic variation of the disturbance. Simulations show that inclusion of a feed-forward element to the control offers notable performance benefits. Interestingly, increasing the complexity of the disturbance model seems to offer little improvement in performance and a simple constant disturbance model provides a suitable solution to the problem while maintaining simplicity of the state estimator.