Online wave estimation using vessel motion measurements

Abstract

In this paper, a computationally efficient online sea state estimation algorithm is proposed for estimation of the onsite sea state. The algorithm finds the wave spectrum estimate from motion measurements in heave, roll and pitch by iteratively solving a set of linear equations. The main vessel parameters and motion transfer functions are required as input. Apart from this the method is signal-based, with no assumptions on the wave spectrum shape, and as a result it is computationally efficient. The algorithm is implemented in a dynamic positioning (DP) control system, and tested through simulations in different sea states, with heading changes. Discrete stability analysis is performed to find iteration gains in the algorithm.