Thrust Allocation of Ship Dynamic Positioning System Under Extreme Sea Environment

The thrust allocation of Dynamic Positioning system allocates the control force to thrusters by calculating thrust and angle of each thruster. The whole thrust optimization allocation goal is to minimize energy consumption of the propulsion system, taking account of the amplitude and rate saturation of thrusters, the rate of change of the angle of azimuth thrusters, prohibited area of thrust of thrusters and so on. Under extreme sea environment such as gust, the output value of control force is beyond the ability of thrusters. It is proposed to reduce all the generalized forces with the same percent. The reducing percent is obtained based on Multiobjective optimization method. Then augmented Lagrange method is adopted to solve general thrust optimization allocation. This approach reserves the desired generalized force direction. Simulation results show that the proposed thrust allocation scheme is applicable and reliable without specified requirements on storage of memory and the control performance is satisfied with the proposed thrust allocation scheme. There is more extensive application prospect.