复杂环境下运动水下机械手涡激振动及水动力性能研究

The underwater vehicle-manipulator system is an important tool for exploring and developing marine resources. However, when the underwater manipulator performs precise positioning operation, it is seriously affected by the vortex-induced vibration. The manipulator vibration and hydrodynamic load become the constraints to establish the underwater manipulator precise positioning control system. The underwater manipulator in complex environment is mainly adopted in this research. The basic scientific research on vortex-induced vibration and hydrodynamic performance of underwater manipulator is carried out. Firstly, the influence mechanism of structural parameters, fluid parameters, motion parameters and relative motion on the vortex-induced vibration response and hydrodynamic performance is explored, and the mechanism of the influence of vortex-induced vibration on hydrodynamic performance is expounded. Secondly, the vortex-induced vibration response law of underwater manipulator is revealed, and the vortex-induced vibration response displacement relationship of underwater manipulators in complex environment is established. Finally, the variation law of fluid load distribution of motive underwater manipulators is explained, and the mapping relationship between hydrodynamic torque and centroid position is established. This project focuses on the basic theoretical research of the precise positioning control technology of underwater manipulators. The research results can promote the development of underwater manipulator transmission and control theory, and provide theory for designing high precision, fast response and intelligent underwater manipulator precise positioning control system. The basis has important theoretical significance and application value.

水下机器人-机械手系统是探索和开发海洋资源的重要工具，然而，水下机械手执行精准定位操作时受涡激振动作用影响严重，机械手振动及水动力载荷成为制约建立水下机械手精准定位控制系统的瓶颈。本项目以复杂环境下运动水下机械手为研究对象，通过实验研究及数值计算，开展水下机械手涡激振动及水动力性能基础科学研究。首先，探索结构参数、流体参数、运动参数及相对运动等因素对涡激振动响应及水动力性能的影响机制，阐明涡激振动对水动力性能的影响机理；其次，揭示水下机械手涡激振动响应规律，建立复杂环境下水下机械手涡激振动响应位移关系式；最后，阐释运动水下机械手流体载荷分布变化规律，建立水动力力矩与质心位置间映射关系。本项目着眼于水下机械手精准定位控制技术的基础理论研究，研究成果可助推水下机械手传动及控制理论发展，为设计高精度、快响应和智能化的水下机械手精准定位控制系统提供理论依据，具有重要的理论意义和应用价值。

水下机器人-机械手系统广泛应用于海洋探索和开发，然而受流体横掠作用产生的涡激振动影响，致使其精准定位和拾取等操作困难。本项目针对水下机械手的涡激振动响应及水动力性能问题，采用数值计算及实验测试等手段，对比了固定和运动水下机械手在单向流场和复杂流场的涡激振动响应及水动力性能，发现水下机械臂截面形状和来流方向是影响振动响应和水动力性能的主要因素，随着机械臂椭圆截面主轴的增大，升阻力系数迅速减小。随着来流方向角度的增大，升阻力系数明显增大。在复杂流场下，随着水流脉动频率和幅值的增大，位于前端的机械臂涡脱数量明显增加，后端机械臂为椭圆形时涡脱规律性降低，能量耗散加快，后端机械臂为圆形时涡脱呈现一定的规律性。在单向层流流场中，水下机械手横流向涡激振动频率以13.67Hz低频振动为主，顺流向振动频率表现为多峰值。在湍流流场中，横流向涡激振动频率下降至9.7Hz，顺流向振动主频不明显。在复杂剪切流场中，横流向的振动位移呈单模态，振动主频集中在15Hz至20Hz，顺流向的振动主频在12Hz至18Hz之间，在较高流速工况下呈多模态。通过对水下机械手涡激振动响应的分析，建立了包含水流流速和运动夹角的振动响应关系式。分析了流体流动、结构参数及姿态变换对水下机械手水动力性能的影响规律，发现水流速度对升阻力系数、力矩系数、表面压力系数及斯特劳哈尔数有着明显的影响，当水流速度到达一定程度后影响不再明显。对比了半圆形前缘与直角前缘机械手水动力系数，半圆形前缘使得阻力系数、升力系数和力矩系数分别最大下降了44%、25%和50.5%。通过计算不同姿态下水下机械手的水力矩系数，得到了水下机械手质心位置与水力矩系数间的关系。本项目揭示了复杂流场下水下机械手的涡激振动特性及水动力性能，研究成果对建立精准的水下机械手水动力模型提供了理论基础，对推进我国高精度、快响应的智能水下机械手发展和进步具有一定的理论意义。