A mixed-scale hardware-in-the-loop testing framework for wave energy converter-autonomous underwater vehicle systems

Hardware-in-the-Loop (HIL) offers a promising pathway for evaluating wave energy converter–autonomous underwater vehicle (WEC–AUV) systems in the laboratory, where a mix of laboratory-scale waves and full-scale AUVs present significant challenges for conventional testing approaches. This study aims to develop and validate an HIL testing framework that reproduces wave forces and dock motions for WEC-AUV systems by integrating wave tank experiments with numerical simulations. Core methodologies, including wave distortion, wave prediction, excitation force estimation, and dock motion control, were developed and experimentally validated in the Large Wave Flume at O.H. Hinsdale Wave Research Laboratory. The approach replicated ocean wave forcing by matching water acceleration or velocity amplitudes under inertia- and drag-force-dominated conditions. Wave prediction enabled real-time estimation of excitation force and resulting dock motion. Across the tested regular and irregular waves, the coefficient of determination R 2 ranged from 0.850 to 0.990 for wave prediction and from 0.956 to 0.995 for excitation force estimation. Dock motion control strategies were implemented in the HIL framework to provide improved AUV docking conditions. Overall, this work provided a practical and experimentally validated pathway for advancing wave energy–powered AUV docking systems.