Robust performance design to satellite attitude control

A satellite has an astronomical survey mission requiring accurate pointing of a scientific sensor package. This package must be maintained in the quietest possible environment, which entails isolating it from the vibrations and electrical noise of the main service body. The pointing requirement arises when it is necessary to point the unit in another direction, it can be met by dynamics with a transient settling time of 20 seconds and an overshoot of no more then 15%. We model the satellite as two masses connected by a spring with torque constant k and a viscous-damper with damping constant b. Physical analysis leads us to assume that the parameters k and b vary as a result of large temperature fluctuation. The attitude pointing requirement must be satisfied for any parameter values in a prespecified range. We will synthesize the robust controller to achieve the specified performance requirement in the presence of parameter uncertainties.