推进器功率推力关系对动力定位能力的影响

Influence of the power-thrust relation of the thrusters on dynamic position capability

动力定位推力分配一般以能量损耗最小为目标进行优化求解。本文旨在讨论推进器功率推力关系对动力定位能力的影响。针对三个不同的推进器功率推力关系,建立性能指标数学模型。基于不同指标函数形式,采用遗传算法、模拟退火算法以及二次规划方法进行优化求解。算例分析结果表明,不同的推进器功率推力关系形式对动力定位能力的影响甚微。同时,遗传算法、模拟退火算法收敛速度慢,计算效率远低于二次规划算法。因此,在处理推力分配优化实际问题时可认为推进器功率正比于推力的平方,推荐采用二次规划算法求解。此外,计算结果还表明动力定位系统在功率受限制时会降低系统的定位能力。

Thrust allocation is a core issue of dynamic positioning and is generally optimized by minimization of energy consumption. The purpose of this paper is to investigate the influence of power-thrust relation on dynamic positioning capability. In view of different power-thrust relations of the thrusters, cost functions are set up. According to these functions, genetic algorithm(GA), simulated annealing algorithm(SAA) and quadratic programming(QP) method can be utilized to optimize the thrust allocation. An illustrative example is provided to demonstrate correctness of the capability polar plot program. And the results show that different power-thrust relations of the thrusters have little influence on DP capability. Meanwhile, the convergence speed of GA and SAA is slow, and the computation efficiency is much lower than that of QP method. Therefore, when thrust allocation is optimized in engineering projects, thruster power can be treated as proportional to the square of thrust, and QP method is recommended to improve the computation efficiency. Furthermore,the results also show that the power limitation will lower the positioning capability of DP system.