In this paper, a new algorithm which integrates the powerful firefly algorithm(FA) and the ant colony optimization(ACO) has been used in tracking control of ship steering for optimization of fractional-order proportional-integral-derivative(FOPID) controller gains. Particle swarm optimization(PSO) algorithm is also used to optimize FOPID controllers, and their performances are compared. It is found that FA optimized FOPID controller gives better performance than others. Sensitivity analysis has been carried out to see the robustness of optimum FOPID gains obtained at nominal conditions to wide changes in system parameters, and the optimum FOPID gains need not be reset for wide changes in system parameters.
为了解海洋石油支持船(Offshore Support Vessel-OSV)抛锚作业过程中,系泊缆和工作缆的缆型、张力变化以及抛锚作业对锚作船的影响,提出了一种OSV抛锚作业的建模方法。采用MMG(Ship Manoeuvring Mathematical Model Group)建模思想,建立了六自由度拖船运动数学模型,通过水下缆索任一微元段的受力平衡条件导出各微元段的动力学微分方程,建立了拖缆模型。在此基础上考虑耦合边界条件,建立了船-缆-锚-缆系统的运动数学模型,并采用龙格库塔方法对船舶运动积分求解,采用差分法对拖缆运动进行求解。仿真结果表明该模型可为制定抛锚控制策略提供参考依据,并对OSV模拟器开发提供理论基础。
