A Cost-Effective IMU-Based Wave Buoy: Customizable Design, Performance Variability, and Field Trial

Yu. Yu. Yurovsky✉, O. B. Kudinov

Marine Hydrophysical Institute of RAS, Sevastopol, Russian Federation

✉ e-mail: y.yurovsky@mhi-ras.ru

Abstract

Purpose. The objective of the study is to present a small batch of wave-measuring buoys developed at Marine Hydrophysical Institute (MHI) using affordable inertial sensors and to evaluate potential errors in wave height measurements associated with random variations in sensor parameters.

Methods and Results. Based on one of the most common sensors, the MPU9250, several identical wave buoys were constructed: 10 in a small housing with a 300 mAh battery for short-term (up to 24 hours) manual measurements and 3 in a larger housing with a 12000 mAh battery for longer deployments (up to a month). Laboratory tests provided upper estimates of linear distortions and measurement biases for the accelerometer, gyroscope, and magnetometer. A field experiment was conducted at the MHI’s Black Sea Hydrophysical Subsatellite Polygon, where three prototype buoys were used to take measurements at two locations: near the shore (30 m from shore, 4 m depth) using both small and large buoys, and near the Stationary Oceanographic Platform (500 m from shore, 30 m depth) using a large buoy, alongside a reference resistive wave gauge. Measurements were taken over two days during easterly winds, with peak speeds reaching 16 m/s. The maximum recorded significant wave height was 1.2 m. Laboratory error estimates for the constructed sensors fall within the ranges specified by the manufacturer. The most critical error for wave height measurements – accelerometer calibration – was no more than 2% for the component normal to the sensor housing and no more than 0.5% for orthogonal components (one of which was used as the vertical axis in the buoys). Field measurements near the platform showed agreement with reference wave gauge data for significant wave heights with a root-mean-square error of 2.4 cm. Wave elevation spectra obtained near the shore by two buoys matched within 95% confidence intervals (a similar agreement was observed between the buoy and wave gauge measurements near the platform). However, wave heights near the shore and near the platform differed by a factor of 2–3 during the experiment, which cannot be attributed to sensor parameter variations and instead reflects the inhomogeneity of the surface wave field.

Conclusions. The developed wave buoys, based on low-cost inertial motion units, can be effectively used in swarm deployments, and factory variations in their internal parameters do not hinder the reliable measurement of typical wind waves. Thus, the proposed approach is useful for studying wave transformation mechanisms at coastal boundaries and for adapting wave models to specific water areas.

Keywords

wave buoy, inertial motion unit, significant wave height, wind waves, measurement errors, field validation, coastal Black Sea

Acknowledgements

Buoy prototyping and calibration were sponsored by the Russian Scientific Foundation grant 24-27-00153 “Measuring waves with small buoys: methods, validation, prospects of miniaturization”. Wind wave field analysis was sponsored by the MHI State Order FNNN2024-0001.

About the authors

Yury Yu. Yurovsky, Leading Researcher, Head of the Applied Sea Physics Laboratory, Marine Hydrophysical Institute of RAS (2 Kapitanskaya Str., Sevastopol, 299011, Russian Federation), CSc. (Phys.-Math), Scopus Author ID: 24377122700, ORCID ID: 0000-0002-9995-3965, ResearcherID: F-8907-2014, SPIN-code: 8482-5777, y.yurovsky@mhi-ras.ru

Oleg B. Kudinov, Researcher, Marine Hydrophysical Institute of RAS (2 Kapitanskaya Str., Sevastopol, 299011, Russian Federation), CSc. (Tech.), SPIN-code: 2248-7034, obk91@mail.ru

For citation

Yurovsky, Yu.Yu. and Kudinov, O.B., 2026. A Cost-Effective IMU-Based Wave Buoy: Customizable Design, Performance Variability, and Field Trial. Physical Oceanography, 33(1), pp. 201-214.

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