Robust autopilot design of uncertain bank-to-turn missiles using state-space disturbance observers

Robust autopilot design for bank-to-turn (BTT) missiles under disturbances and uncertainties is investigated in this paper using the disturbance observer concept. It is well known that the BTT missile dynamics undergo a substantial changes during its flight. In this disturbance observer based control setting, the influences caused by parameter variations are merged into disturbance terms and regarded as parts of the lumped disturbances. Disturbance observers are employed to estimate the lumped disturbances and then a disturbance observer based robust control method is proposed in this paper to compensate the the influences of parameter variations and the disturbances from the output channels. Similar to the baseline LQR design, the disturbance observer based robust control is analysed and designed using linear techniques. Very promising performance has been achieved for the BTT missile as shown in simulation. It is demonstrated that disturbance observer based control approach provides a simple, intuitive and practical solution for many challenging control problems where systems are subject to significant external disturbances, and uncertainties such as BTT missiles.