Low-order robust attitude control of an earth observation satellite

The attitude control of an observation satellite, which exhibits highly unc ertain lightly damped modes, is designed by loop-shaping H-infinity design. Minimum-order controllers solving an LMI formulation of the problem are so ught, using a cone complementarity linearisation algorithm. For different c ontrol laws, it is explained why the procedure leads to very low-order cont rollers. To analyse the stability robustness of the control law, different structured singular-value upper bounds and fitting characterisations of set s of uncertainties allow the computational cost of a mixed mu-analysis proc edure to be minimised. Finally, the performance of the control laws is stud ied on a nonlinear simulator. (C) 1999 Elsevier Science Ltd. All rights res erved.