What is it about?

Most satellites are equipped with a minimum of three attitude actuatros for fully controlling attitude and angular rate. More than three actuators make the system redundant, heavier, more expensive, but resilinet to failure. The paper provides a control law that allows aiming a body-fixed direction (e.g. a nozzle for orbit maneuvers or an antenna or the boresight of a sensor) towards a prescribed direction using only two reaction wheels, that is, when the spacecraft is underactuated.

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Why is it important?

Satellite operational life can be extended if a minimal activity can be carried on also after (possibly multiple) failures of on board hardware. Arbitrary pointing precision can be achieved, if the residula angular momentum is kept to zero.

Perspectives

We have been working on kinematic planning of attitude maneuver for a while, that is, the determination of sequences of rotations that can achieve a prescribed attitude. This is the first dynamic implementation of one of this kinematic planning techniques. It is only the first one. More will follow for more complex tasks. We are working on that...

Prof Giulio Avanzini
Universita del Salento

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This page is a summary of: Single-Axis Pointing of an Underactuated Spacecraft Equipped with Two Reaction Wheels, Journal of Guidance Control and Dynamics, June 2017, American Institute of Aeronautics and Astronautics (AIAA),
DOI: 10.2514/1.g002182.
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