Zivanovic, MiroslavVilella San Martín, IñigoIriarte Goñi, XabierPlaza Puértolas, AitorGainza González, GorkaCarlosena García, Alfonso2025-02-242025-02-20Zivanovic, M., Vilella, I., Iriarte, X., Plaza, A., Gainza, G., Carlosena, A. (2025). Main shaft instantaneous azimuth estimation for wind turbines. Mechanical Systems and Signal Processing, 228, 1-21. https://doi.org/10.1016/j.ymssp.2025.112478.0888-327010.1016/j.ymssp.2025.112478https://academica-e.unavarra.es/handle/2454/53545We present a novel approach to estimating the instantaneous main shaft angular position in the context of wind turbine structural health monitoring. We show that only two IMU channels - gyroscope axial and accelerometer tangential - contain enough information to build an acceleration state-space model that properly captures the rotational dynamics of a wind turbine. The kernel of the model is an in-phase and quadrature time-varying sinusoid whose argument is driven by the integral of the gyroscope output. This approach clearly stands in contrast to most state-of-the-art methods, where the gyroscope output is explicitly modeled. The model equation describes the states dynamics, which simultaneously assesses the instantaneous amplitude and initial phase of the angular displacement through a first-order autoregressive process. Such a state-space model features only two states per time instant; furthermore, it is linear-in-states and therefore straightforwardly estimated by the linear Kalman filter. It is shown that the instantaneous azimuth estimates obtained from the state-space model, linearly combined with the gyroscope output, effectively cancel out the long-term drift in the estimate. The benchmark results suggest that the proposed method outperforms a state-of-the-art method, in terms of robustness against noise and adaptability to changing operating regimes in a wind turbine.application/pdfeng© 2025 Elsevier Ltd. This manuscript version is made available under the CC-BY-NC-ND 4.0Wind turbineAzimuthInertial measurement unitKalman filterInstantaneous phaseinfo:eu-repo/semantics/article2025-02-24info:eu-repo/semantics/embargoedAccess