抄録
Offshore platform or cable layer ship are often required to keep their position with high accuracy under influence of external forces. In order to keep their position at deep sea, dynamic positioning system (DPS) is often used. Though the linear quadratic (LQ) optimal regulator theory is often applied to design control system of DPS, it is very difficult to select suitable weighting matrices in the performance index that is necessary to obtain optimal control input. Therefore, from a viewpoint of practical use, recently the inverse linear quadratic (ILQ) optimal servo theory that makes design process more easier has been proposed. In this paper, we applied the ILQ optimal servo theory to design the control system of DPS for ships and carried out numerical simulations of ship motion to examine the performance of the control system designed by using the ILQ optimal servo theory. From the numerical simulations, it is found that the time constant T_i should be selected to be small value considering performance of the thruster and the gain adjustment parameter σ_i would be selected as same as value of σ__-. It is also found that design process using the ILQ optimal servo theory would be more easier than using conventional LQ optimal regulator theory.
