Robust Attitude Guidance and Control for Flexible Spacecraft

In assessing several candidates for future M4 class missions, it was shown that significant science downtime is needed when spinning space craft use long wire booms to collect scientific data for Earth Observation missions.

These long wires wobble and are unstable so when the spacecraft is turned, or its orbit is changes, they are excited and wobble. Without a way to damp that motion the mission is put on hold, often over several days, while they stabilize. A lot of data taking time is lost waiting for them to dampen enough to take high quality science data again.

An activity with TDE and Airbus UK, has investigated using robust control methods to actively dampen these booms and improve performance. It created hi-fidelity simulation models that captured the relevant dynamics and typical elements on such spacecraft, before designing & verifying a robust control framework.

This defined certain performance objectives such as how quickly the mission could dampen wobbling and how much residual wobbling would be acceptable. The success was demonstrated in a laboratory at DLR in Germany using a smaller module with 1m wires. It showed that using robust guidance and control could dampen motion very quickly by reducing the loss of data taking time from days to under 2 hours.

The activity found that some wire oscillatory modes remain uncontrollable due to the restriction of using thrusters only on the main spacecraft body, but these modes are naturally lightly damped and not expected to be significantly excited.

While no current missions are planned that could utilize this, if spinning missions arise in the future with astrophysics goals this will become a highly relevant technology development.

T205-032EC closed in 2021 and was presented in the Technology Sharing Days.