Probabilistic modelling of the drifting trajectory of an object under the effect of wind and current for maritime search and rescue

The problem of trajectory prediction for unpowered drifting objects under the effect of current and wind is studied in this paper. A probabilistic model is proposed to predict the object's velocity and position at every moment in a sequential way. The objective is to make an optimal estimation of the current and wind velocities near the object using observations of the spatial correlated velocity fields. According to the leeway dynamics model, the object's velocity is the weighted average of current and wind speeds. Extensive simulations are performed and the influence of parameters, such as the uncertainties on current and wind velocities, the frequencies and resolutions of the fields, on the performance of the algorithm are also analyzed. Simulation results indicate that the proposed algorithm works well and the object's true position lies within the 99.7% confidence area. Increasing the reliability and resolution of wind or current field's data would enhance the precision in predicting the object's position. The effect of wind and current depends to a large degree on the drifting object's volume above and below the water.