LESO-Enhanced Reduced-Order H-Infinity Control of a Rigid Aerial Refueling Boom

Rigid aerial-refueling booms experience atmospheric disturbances, aerodynamic-model mismatch, and residual within-channel effects. This study develops an LESO-enhanced reduced-order H∞ control framework for the attitude regulation of a rigid boom with H-type control surfaces. A trim-centered small-perturbation model provides a unified channel-wise representation of pitch and roll while preserving their individual state-space matrices. A weighted generalized plant balances tracking, disturbance rejection, and control activity; a tenth-order synthesis is reduced by stable-component balanced truncation to yield an implemented fourth-order controller. A model-assisted linear extended state observer estimates the residual total disturbance and compensates it at the plant input without modifying the robust-feedback loop. The model-assisted gain selection places the error polynomial at (s+ωo)3 while retaining the nominal dynamics. A four-block pitch-loop structured-singular-value test and time-domain tests of mismatch, measurement noise, and actuator constraints are reported with explicit scope limitations. Under common commands and colored-gust inputs, LESO augmentation improves disturbance-affected tracking while maintaining comparable command activity when actuator authority is available. The resulting framework combines transparent robust-feedback design, online disturbance compensation, and reproducible within-channel verification for rigid flying-boom control.