Civil aircraft weight and center-of-gravity real-time estimation via the six-degree-of-freedom model with variable center of mass

Abstract

This article addresses the issue of civil aircraft weight and center-of-gravity position real-time estimation using the six-degree-of-freedom model with variable center of mass, and derives the explicit expressions for aircraft weight and longitudinal center-of-gravity. Firstly, the nonlinear six-degree-of-freedom aircraft model with center-of-gravity variations is established, where the moment correction is considered. Subsequently, an aircraft weight estimation method via force analysis and an aircraft longitudinal center-of-gravity position estimation method via moment transformation are developed, and the acceleration correction is derived. Furthermore, a fuel system architecture is introduced, and the active center-of-gravity controller is designed. To assess the effectiveness of the proposed method, a series of numerical simulations are operated, integrating sensitivity analysis with quantitative calculation. The results demonstrate that the algorithm achieves consistent and reliable performance even under parameter perturbations, with the longitudinal center-of-gravity position estimation error remaining within ±2 % of the mean aerodynamic chord (MAC).