多自由度两鳍推进自主仿生机器鱼基础理论研究

It has been shown that the existing two pectoral fin propulsion biomimetic-robotic fishes mostly achieve theirs basic swimming mode by flapping motion, feathering motion, and theirs compound motion. But theirs performance indexes such as swimming speed and maneuverability are far away the expected one. One of important reasons may be that the pectoral fin with one or two degrees of freedom (DOF) cannot simulate the motion of the fish. For this purpose, this project is devoted to develop an autonomous biomimetic-robotic fish which propelled by two pectoral fins with multiple DOF, flexible body with multiple links and caudal fin, which can be used to detect the water environment of Northwest of china. The main contents are as follows. (1) The propulsion mechanism of pectoral fin are first designed such that the lead-lag motion, flapping motion, feathering motion, and theirs compound motion can be achieved simultaneously. Then the flexible body with multiple links and the caudal fin are designed, too. Finally, the control systems of the proposed robotic fish are designed. (2) The kinematics models are established for the propulsion mechanism of pectoral fin and flexible body/caudal fin, respectively. Then, the hydrodynamics models are proposed for pectoral fin by using the micro-element analysis method and for flexible body/caudal fin by the fluid theory of fishes driven by BCF, respectively. Finally, the shape and flexibility of pectoral fin and caudal fin are optimized. (3) For the cases of driven by pectoral fin, flexible body/caudal fin, or the combination of them, each swimming mode is determined according to the desired resultant force and resultant moment. Combined with the results of experiments, each swimming mode is further partitioned into different gears.

调研表明，现有两鳍推进机器鱼大都通过两侧胸鳍摇翼运动、上下拍翼运动、或两者复合运动实现其游动模态，但在游速、机动性等方面远未达到预期目标。其中胸鳍自由度数较少，无法更好地模拟真实鱼类胸鳍运动方式是重要原因之一。为此，本项目拟研制一款兼具多自由度胸鳍、多关节柔性身体及尾鳍，可用于西北地区水环境监测的自主仿生机器鱼，内容包括: (1) 设计能实现摇翼运动、上下拍翼运动、前后拍翼运动以及三者复合运动的胸鳍推进机构、以及相应多关节柔性身体及尾鳍；并完成控制系统设计。(2) 针对胸鳍、柔性身体/尾鳍推进机构，分别建立运动学模型，进而采用微元分析方法建立胸鳍推进水动力学模型，利用BCF推进理论建立身体/尾鳍推进水动力学模型；完成胸鳍/尾鳍形态优化。(3) 分别针对胸鳍、柔性身体/尾鳍单独及协同推进情形，根据各游动模态所需合力和合力矩条件，确定其所对应的运动学参数集，并结合实验结果，完成各模态档位划分。

高推进效率、高机动性的水下仿生机器人是完成众多水下作业的重要装备，是机器人研究的重要分支。本项目以两鳍推进仿生机器鱼为研究对象，针对多自由度推进机构设计、复合推进方式、以及自主控制方法等内容展开研究，项目执行期内发表论文23篇，其中SCI/EI收录期刊论文8篇：会议EI收录论文5篇，申请/授权发明专利8件，授权实用新型专利9件，甘肃省优秀硕士学位论文1篇。取得的主要结果如下： (1). 设计了多种具有上下拍翼、前后拍翼和摇翼等3个自由度的仿生机器鱼刚性胸鳍，以此为基础完成了多款仿生机器鱼设计，并完成了样机试制。所设计机器鱼以两个多自由度刚性胸鳍、柔性身体以及尾鳍为推进机构，具有丰富的推进模式；(2). 以所研制放生机器鱼为研究对象，深入分析了前后拍翼、上下拍翼、摇翼、柔性身体及尾鳍协同推进机理。CFD水动力学分析结果表明，复合推进模式结合了中央鳍/对鳍和身体/尾鳍推进模式的特点，具有较好的游动稳定性、小的转弯半径和高机动性；(3). 以理论分析与实验相结合的方式，研究了所研制仿生机器鱼直游、转弯、以及定深控制方法。在转弯性能研究中，以多自由度胸鳍推进仿生箱鲀机器鱼为对象，研究其在单侧胸鳍推进、两侧胸鳍协同推进、以及单侧胸鳍与尾鳍协同推进等多种情形下的转弯特性．给出了单侧胸鳍推进、单侧胸鳍／尾鳍协同推进时机器鱼实现给定半径转弯以及原地转弯的条件；在定深控制中，根据深度误差的大小将定深控制过程分解为趋近阶段与巡游阶段，给出了一种基于中枢模式发生器（central pattern generator，CPG）与模糊控制相结合的闭环运动控制方法，提高了机器鱼趋向期望深度的速度并减小了在期望深度巡游时的稳态误差；(4). 针对多仿生机器鱼编队控制问题，提出了一种基于二阶一致性算法的多仿生机器鱼分布式编队控制方案。以上结果对两鳍多自由度仿生机器鱼的协同推进机理和控制方法的研究具有一定的参考价值，为后续研究奠定了比较坚实的基础。