Antenna Robust Controller Design Using Feedforward Action for Accurate Pointing Onboard a Spacecraft1

A controller for a spacecraft mounted flexible antenna is designed. The antenna/plant has a high order and disturbances from the host spacecraft are transmitted to the antenna and need to be attenuated, while a high degree of pointing accuracy must be achieved. The design concept explored herein entails feedforward control to slew the antenna. Feedback control is then exclusively used to compensate for plant uncertainty and disturbance rejection. A tight feedback control loop is designed to meet performance specifications while minimizing the control gains. It is shown that the integration of feedforward control action and feedback compensation produces better responses than feedback control alone.