Robust Control Techniques for Large Satellites with Demanding Pointing Performances

Status date
Activity Code

The project aims at improving the overall pointing performance and robustness with respect to uncertainties of large telecom platforms with highly flexible appendages and demanding pointing payloads.

Two performance class have been identified:

  • Lower than 0.03 deg for multi-spot mission The mandatory solution is to use a second stage of control directly on the RF signal,
  • Lower than 0.1 deg for missions with very large flexible appendage.

The selected solution is to estimate and pre-compensate the disturbance torque mainly due to propellant motion.

click for larger image


The main challenge was to find solutions both efficient and realistic at short to mid-term for telecom missions.


Strong improvement of pointing accuracies, thus improving payloads efficiencies and general competitiveness. With Antennas Tracking Systems: pointing is improved from 0.05 deg to 0.027 deg, including during manoeuvres. Without dedicated antennas pointing system: pointing is improved from 0.126 deg to 0.075 deg.


According to the 2 performance class identified, the project is divided in 2 cases:

  • Antenna Tracking System to control RF signal orientation at a very high sample frequency µ-synthesis tuning method is implemented to find a stable and robust controller that reaches the required performance,
  • Estimation and pre-compensation of the disturbance torque from one station keeping manoeuvre to the next is implemented to reduce the main contributor to control error.

The project is split into 4 tasks:

  • Brainstorming to identify ways of improvements,
  • Selection of the most promising ones,
  • Development of selected solutions,
  • Validation and performance assessment of the selected solutions.
Current status

The project is finished.