ROV水动力性能及推力控制分配研究与仿真

Research and simulation of ROV hydrodynamic performance and thrust control distribution

良好的推力控制分配策略是缆控水下机器人(remotely operated vehicle, ROV)机动性和作业安全性的保障,也是ROV运动控制技术得以实现的必要条件.但现有的推力控制分配策略存在推力输出饱和或计算时间过长等问题,导致ROV机动性欠佳.针对现存问题,提出了一种混合优化目标推力控制分配策略.首先,建立ROV驱动系统数学模型,设计了一种混合优化目标推力控制分配函数;再使用Fluent软件分析不同工况下导管螺旋桨的水动力性能,得到推进器的推力模型,从而确定混合优化目标推力控制分配函数的约束条件;最后采用光滑牛顿法求解混合优化目标推力控制分配函数,并与传统伪逆推力分配策略进行仿真对比.仿真结果表明,混合优化目标推力控制分配策略能满足各推进器对推力的约束要求,并能有效地利用约束范围内的推力集合,且通过光滑牛顿法求解的总体误差小于0.0007 N m,单步迭代次数在10步以内,单步计算时间小于2 ms,其具有精度高、实时性好、无推力输出饱和等优点.

A good thrust control distribution strategy is needed to guarantee ROV mobility and operational safety and implement ROV motion control technology. However, the existing thrust control distribution strategy has problems including saturation of thrust output and excessive calculation time, leading to poor ROV mobility. To address these problems, a hybrid optimization target thrust control allocation strategy is proposed. First, the ROV drive system is mathematically modelled and a hybrid optimization target thrust control distribution function is designed. ANSYS Fluent software is used to analyze the propeller’s hydrodynamic performance under different working conditions and model its thrust to determine the constraints of the hybrid function. Finally, the smooth Newton method is used to solve the function, and compare it with the traditional pseudo-reverse thrust distribution strategy. Simulation results show that the new strategy is able to meet the thrust requirements of each thruster and effectively utilize the thrust set in the constraint range. The overall error solved by the smooth Newton method is less than 0.0007 N m, with less than 10 iteration steps, and a singlestep calculation time of less than 2 ms. It has the advantages of high precision, good real-time performance, and no thrust output saturation.