An improved reel take-up system for suppressing the aerial refueling hose whipping phenomenon (HWP) is proposed and analyzed. The conventional spring-loaded take-up system is improved by adding a rewinding acceleration changing rate limiter (RACRL), relying on a permanent magnet synchronous motor (PMSM). The effectiveness of this new reel take-up system is confirmed by the numerical simulation at various closure speeds. The results show that the new PMSM-RACRL reel take-up system successfully accomplishes the active control of tension oscillation and the suppressing of HWP with a straightforward strategy. The amplitude of tension oscillation is reduced to one-tenth of that without active control. It is also discovered that the reel take-up speed lagging behind the drogue closure speed is mainly caused by the oscillation of hose tension, and a maximum acceleration of the reel take-up system lower than the maximum closure acceleration of the drogue will inevitably cause the slack and whipping of the hose.
Large-slenderness-ratio (LSR) aircraft exhibit more severe lateral–directional coupling compared with other aircraft, which poses a significant challenge to their flight safety, especially during high-speed maneuvers. Reliable attitude decoupling control is, therefore, essential for LSR aircraft. In this study, a novel control framework that combines incremental nonlinear dynamic inversion (INDI) and extended state observer (ESO) is proposed for supersonic roll maneuver control of LSR aircraft. The ESO is used to estimate the angular acceleration on the basis of an onboard mathematical model. The acceleration estimator based on ESO achieves superior noise reduction compared with the complementary filter (CF) and reduces the onboard model requirement without significantly sacrificing estimation accuracy. Monte Carlo (MC) simulations and frequency–domain analysis demonstrate the effectiveness and robustness of the proposed controller. The sensitivity of parameter uncertainties is also investigated, revealing that the natural frequency of the actuator is the most critical parameter affecting robustness. Finally, flight tests validate the effectiveness of the proposed control structure.
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