【作者】 杨超；

【导师】 徐新生；

【作者基本信息】 大连理工大学 ， 工程力学， 2009， 硕士

【摘要】 随着科学的进步,在各领域中,机器人的运用和研制越来越受到重视,特别是能在液体中游动的新型管道微型机器鱼。该机器鱼可在微小的空间内不受环境影响的灵活工作。比如在有毒物质或被污染管道内作业等。因此对此进一步研究有重要意义。本文采用合金薄板模拟鱼尾骨架,贴在该薄板的超磁致伸缩材料模拟鱼体肌肉,并以外磁场模拟神经控制鱼体摆动。经过鱼类快速起动的仿生学分析和研究建立了该问题的一个力学模型。通过对模型的分析和简化建立了机器鱼游动的动力学方程,给出了动力学方程所需满足的初始条件和边界条件。在讨论上述问题中,首先考虑简单模型,即线性模型。采用分离变量法把问题归结为空间坐标和时间的两个函数问题。其中一个问题转化为特征值和特征向量问题,而另一个问题归结为关于时间的二阶常微分方程问题。利用特征向量(振型)的正交归一关系,将所得到的解进行叠加,从而获得问题的解析解表达式。第二步讨论与几何大变形和非线性阻尼相关的非线性模型。利用上述本征解和非线性动力方程以及小参数展开方法,得到了一种递推公式,形成一种求解非线性问题的数值方法。通过数值分析,揭示了仿生机器鱼的游动机理。分析和研究了材料和几何参数以及环境因素等对机器鱼起动的影响。结果表明,仿生机器鱼平均驱动力并不是随着外界频率的增加而单调增加,而是存在一个最佳频率,在此外界频率下平均驱动力最大,因而可设计出该鱼最佳起动模式。数值结果还发现仿生机器鱼在起动过程中最佳模式是从低阶模态到高阶模态的快速过渡。这个规律可实现机器鱼快速从静止到高速游动的过渡。研究结果还表明通过调节外磁场频率和强度可控制超磁机器鱼的起动速度。仿生机器鱼起动的快慢与材料常数、几何参数、液体环境以及外磁场频率和强度有关。仿生鱼起动过程中的轨迹并不是直线且与鱼体有一夹角。该夹角与外磁场强度密切相关。研究结果验证了鱼类各种起动模式的合理性,同时也为仿生机器鱼快速起动的设计提供了依据。更多还原

【Abstract】 The application and manufacture of robots are noticed specially in many fields with the development of science. The bionic robot-fish is an important one of the robots since it can swim in the small tube and is not affected by the circumstance, for example, toxic or polluted liquid. Therefore, it is important to research bionic robot-fishes.In this paper, the alloy sheet is simulated as the framework of the fishtail, the giant magnetostrictive material (GMM), which is stuck on the sheet, as the muscle of the fish and the external magnetic field as the nerve to control the swing of the fishtail. By analyzing fast-start of fishes bionically, a mechanics model and new analytical method are presented. By discussing and predigesting the model, dynamic equations, boundary conditions and initial conditions are obtained for swimming of robot-fish. Firstly, consider a simple model, or linear model. Using the method of separation of variables, the problem is divided into two sorts of equations, which are expressed by two functions of spatial coordinate and time respectively. One of them is transformed to the problem of eigenvalues and eigenvectors, and the other is reduced to the problem of the ordinary differential equation of the second order about time. By aiding the adjoint symplectic orthonormal relations between eigenvectors (or vibration modes) and the superposition principle, the expression of analytic solution is obtained. Secondly, the nonlinear model is discussed, in which the large deformation and nonlinear damp are considered. By adopting eigensolutions, nonlinear dynamic equations and the method of small parameter expansions, the recursive formulas are obtained, so that a numerical method for nonlinear problem is derived. By numerical computation and analysis, the fast-start mechanism of the bionic robot-fish is revealed. Besides, effects of material constants, geometrical parameters and circumstance factors for bionic fish starting are researched. The results show that the average propulsion of the robot-fish is not monotone increased with the frequency of the external magnetic fields. But there is an optimal frequency of the fields, in other words, the average propulsion is the strongest at the frequency of system. Thus, the mode of the optimal starting is devised. In numerical results, it is discovered that the optimal mode for the starting is the fast-transition which is from the lower order mode to the higher order mode so that the robot-fish can swim quick from the static state. The results show still that the start velocity of the bionic fish can be controlled by adjusting the frequency and intensity of the external magnetic fields. It should be point that the contrail of the fish is not a beeline and there is an angle between the initial state and the transient state of fish body. The angle depends on the intensity of the external magnetic fields. Numerical results agree with start-modes of fishes. The method and results provide theoretical foundation and applied basis for designing bionic robot-fish.更多还原