Motion sickness predictions for floating wind turbine motion data

The rising demand for clean energy is expected to drive the expansion of offshore wind farms, particularly in deep-sea locations where floating foundations will be necessary. These future wind turbines will be taller and larger than those currently in use. While larger turbines do not necessarily experience more motion, their increased size alters the frequency and magnitude of movements. These dynamic effects, combined with exposure
to waves and wind, could impact stability in the nacelle. As a result, motion sickness in maintenance engineers working on these floating wind turbines may become a significant concern. As no empirical data on either nacelle motion or motion sickness for this type of wind turbine are available, prediction models may provide insight into the likelihood of motion sickness given a certain sea state and wind condition combined with different types of floating bases. However, the prediction model in the only available international standard on motion sickness, ISO 2631-1[4], is expected to have only limited applicability for this situation. This model was developed specifically to predict seasickness and therefore only takes vertical accelerations into account. Moreover, it only predicts motion sickness incidence (the percentage of the population expected to end up vomiting due to motion exposure) as an outcome variable and therefore cannot predict lower degrees of motion sickness, which still may have debilitating effects on performance. Recently, TNO has developed an extended version of the ISO 2631-1 model, which is based on linear accelerations along all three cardinal axes (longitudinal, lateral and vertical) and predicts various degrees of motion sickness [2]. Moreover, it allows for predictions for groups of people with different motion sickness susceptibility as measured with the Motion Sickness Susceptibility Questionnaire (MSSQ [3]). ORE Catapult has asked TNO to apply TNO’s motion sickness prediction model to simulated nacelle acceleration data for two different types of floating bases (semisubmersible and TLP), each with five different sea states. The goal is to compare motion sickness predictions for the two base types and assess the potential influence of sea state for both bases. In addition, the predictions will be compared to those from the ISO 2631-1 model. This report describes the process and the results.