ESA GNC Conference Papers Repository
Improvement of Satellite Availabilty Through Reduction of Flexible Mode Excitation During Slews
Between two pointing, a slew is performed to change satellite orientation, putting the mission on hold and thus impacting satellite availability. The mission unavailability during the slew can be split in two phases. The first phase is the slew itself to go from a pointing A to a pointing B. The second phase corresponds to the duration of the damping of all disturbances once the final pointing is achieved. This includes control law convergence and the damping of all disturbances including flexible modes. Usually, emphasis is given to the reduction of the slew duration itself, either by increasing torque capacity or by performing the slew at maximum rate. The tranquilization time is then managed by reducing control loop response time or increasing satellite stiffness to decrease disturbances linked to flexible modes. This article aims at taking into account the global time of the manoeuvre to increase overall availability. Methods for slew shaping are reviewed and tested allowing the reduction of the disturbances at the end of the slew while minimizing the increase of the slew duration.