REAL TIME ESTIMATION OF WAVES AND DRIFT FORCES
J. M. M. Knoop, R. Eatock Taylor · 1990
It is demonstrated how information about the undisturbed wave at all frequencies of interest can be retrieved by constrained deconvolution of the outputs of several sensors with different known linear response characteristics, placed on or around a floating structure. A model of the sea state which retrains information about the amplitude, phase and direction can then be used to calculate the resulting nonlinear drift forces by means of known quadratic transfer functions. With certain limitations, the wave and drift force calculation can be implemented in real time using frequency domain techniques. The resulting force time history could be used as feed forward information by the controller of a dynamic positioning system, to improve performance and efficiency. This could be further enhanced by applying linear prediction techniques (an auto-regressive model) to the force time history.