H-Infinity Control for Attitude Manoeuvres of a Spinning Asymmetric Vehicle

Abstract

The design and simulation of an H-infinity controller for the purposes of attitude guidance for a spinning asymmetric vehicle is detailed. The controller takes pitch and yaw rate commands from an attitude guidance law and issues flap deflection commands. The modelled vehicle has a rectangular body cross-section and spins at 1.5 Hz with independent pitch and yaw flap sets. The simulation is performed in a six degree-offreedom program. The vehicle is shown to perform an attitude manoeuvre pitching up 6o and yawing to the right 4o with a settling time of less than 0.25 seconds. A previous implementation of the guidance law used two SISO autopilots, which resulted in a settling time of approximately 0.5 seconds. The H-infinity controller demonstrates a significant improvement in settling time performance and is a potential candidate for implementation in a flight experiment, despite an H-infinity norm of 100.1 at a frequency of 0.