抄録
Thrust allocation is one of the most important problems for the motion control of a ship with rotatable azimuth thrusters. The conventional method optimizes only the fuel consumption, which makes the control performance poor because azimuth thrusters cannot realize the allocation commands instantly. Recently, several studies have been made on the allocation method in consideration of both fuel consumption and limitation of thrusters' angular velocities. However, each solution scheme needs an iterative optimization in the online calculation and it makes the implementation difficult. On the other hand, Ohtsubo et al. have proposed the allocation method under the constraints on azimuth thrusters' angles, which needs no online optimizing calculation while the energetic efficiency is poor compared with some conventional methods. Koterayama et al. have improved the allocation method via linear approximation and verified the performance through model experiments. However the approximation method cannot always satisfy angle constraints and achieve the optimality. In the paper, we present the thrust allocation method under the constraints on azimuth thrusters' angles using piecewise linear interpolation and verify that the algorithm satisfies angle constraints strictly and achieves the optimality through numerical simulations.
