Position control of floating structures via slow-drift force ensemble simulations

Abstract

The solution of Riccati equation in conventional linear quadratic optimal control usually neglects effects of forcing function. This will lead to sub-optimization of quadratic cost function as in the case of floating vessels subjected to environment disturbances which are random in nature. The significance of accounting for the forcing function is demonstrated here for the case of dynamic position of moored floating vessels subjected to simulated slow-drift wave forces. For this purpose, the control algorithm developed by [5] is adopted. An ensemble of slow-drift wave forces are simulated in moderate sea and extreme sea state to represent critical environment disturbances acting on floating vessels to arrive at the corresponding set of optimal control parameters. In addition, comparison is made for the control between linear and nonlinear model in moderate sea and extreme sea.