  This paper presents a model based experimental investigation to demonstrate
the usefulness of an active damping strategy to manage fluid sloshing motion in
spacecraft tanks. The active damping strategy is designed to reduce the
degrading impact on maneuvering and pointing performance via a force feedback
strategy. Many problems have been encountered until now, such as instability of
the closed loop system, excessive consumption in the attitude propellant or
problems for engine re-ignition in upper stages. Mostly, they have been
addressed in a passive way via the design of baffles and membranes, which on
their own have mass and constructive impacts. Active management of propellant
motion in launchers and satellites has the potential to increase performance on
various levels. This paper demonstrates active slosh management using force
feedback for the compensation of the slosh resonances. Force sensors between
tank and the carrying structure provide information of the fluid motion via the
reaction force. The control system is designed to generate an appropriate
acceleration profile that leads to desired attenuation profiles in amplitude,
frequency and time. Two robust control design methods, one based on $\mu$
design and the other on parametric structured design based on non-smooth
optimization of the worst-case $H_{\infty}$ norm, are applied. The controller
is first tested with a computational fluid dynamics simulation in the loop.
Finally a water tank mounted on a Hexapod with up to $1100$ liter is used to
evaluate the control performance. The paper illustrates that is possible to
actively influence sloshing via closed loop.

Systems and Control