Multirate eigenstructure assignment with application to an aircraft lateral SAS/Autopilot

A result for multirate state feedback with fast and slow feedback loops is extended to output feedback. This multirate feedback structure is combined with eigenstructure assignment to design a lateral stability augmentation system operating at 50 Hz and a bank angle autopilot operating at 10 Hz for the linearized dynamics of the L-1011 aircraft. Gain suppression is used to reduce the number of gains from twelve to seven. A hybrid simulation with the continuous aircraft dynamics and digital multirate controller demonstrates the excellent intersampling behavior both with the autopilot on and with the autopilot off.