Pitot tube measure-aided air velocity and attitude estimation in GNSS denied environment

This paper addresses the problem of estimating air velocity and gravity direction for small autonomous fixed-wing drones in GNSS¹-denied environments. The proposed solution uses a minimal sensor suite, relying on Pitot tube measurements and Inertial Measurement Unit (IMU) signals, including only gyrometers and accelerometers. The approach combines the Riccati observer and Equivariant Filter designs, using an over-parametrization technique to design an observer on $\mathrm{SO}\left(3\right)\times R^3$ and subsequently re-project to $S^2\times R^3$ to estimate the gravity direction. The system’s observability is analyzed, and local exponential stability of the origin of the observer error is demonstrated as long as the aircraft attitude is persistently exciting. The observer was evaluated using simulated and real flight data to showcase the estimator’s performance.