【作者】 孙发明；

【导师】 徐新生；

【作者基本信息】 大连理工大学 ， 流体力学， 2009， 博士

【摘要】 在工业、国防、石油化工和医学等领域中,由于环境和其它因素的限制,迫切需要各种能在液体介质中平稳灵活移动的新型微小型机器人。特别是无线驱动并具有很高的机动性和灵活性的机器人更受人青睐。比如在医学中利用微小型机器人做精密手术,能避免对患者手术开刀和缝补伤口,将使患者的伤害达到最小。再比如,在工业上,微小型机器人常常被用来维护工业管道以及探伤等。随着智能材料的研制和应用,微小型机器人得到了较快的发展。超磁致伸缩材料是一种特殊的智能材料,通过外磁场可以达到无线控制的目的。因此研究和设计特殊的仿生超磁机器鱼,成为一个较好的选择。然而这类机器鱼驱动的关键技术和机理有待于进一步研究。本文采用合金薄板模拟鱼尾骨架,贴在该薄板上的超磁致伸缩材料模拟鱼体肌肉,用外磁场来模拟鱼的神经控制系统,建立了一种利用外磁场驱动仿生机器鱼的力学模型。通过研究机器鱼的游动机理,设计了一种驱动机器鱼游动的超磁动力驱动器。超磁仿生机器鱼的设计避免了携带动力系统,易于实现机器鱼的小型化和微型化,并在管道作业等有着重要的意义。论文分析了外磁场频率、鱼尾材料参数和几何参数等因素对鱼尾摆动所产生的平均驱动力的影响。发现了外磁场频率接近鱼尾系统的固有频率时,鱼尾摆动所产生的驱动力达到一个较大的峰值。这样通过调节外部磁场频率可实现了控制超磁机器鱼游动。通过对鱼尾的不同摆动模式进行了数值模拟,得到了鱼尾的各种摆动模态、鱼体游动轨迹以及鱼尾摆动流场尾迹。模拟自然界鱼类特征,揭示了自然界金枪鱼类,梭鱼类和蝴蝶鱼类等的游动机理。计算和分析结果表明,在外磁场作用下,机器鱼鱼尾被激励和摆动,其摆动模态可以通过调节外磁场强度和频率来控制。在一般情况下当外磁场以系统的二阶固有频率工作时其工作效率最佳。在此情况下鱼尾摆动产生了推力型反卡门涡街形态的尾迹涡流。针对不同的液体媒介或不同的鱼尾材料和几何形状,最优的鱼尾摆动所对应的最佳外磁场频率是不同的。应该指出鱼尾长度对机器鱼的游动也有较大的影响。各阶摆动模态都存在一个最佳鱼尾长度,这样通过改变鱼尾的长度,也可以调整机器鱼游动的姿态,以适应具体环境。借助于此研究和发现,以及优化鱼尾长度和外磁场频率等参数,提出了机器鱼的一种新的设计思想,设计出前后两鱼尾的新型水下双尾机器鱼。该仿生机器鱼在外磁场一特定的频率下向前游动,而在另一特定的频率下向后游动。这样实现了通过调整外部磁场频率控制机器鱼前后游动。在此基础上考虑非线性阻尼和几何大变形情况,研究和讨论了问题的稳态解和非稳态解。结合金枪鱼和梭子鱼的形态特征,以三种形状的鱼尾为例,它们分别对应矩形参照鱼尾、金枪鱼月牙形鱼尾和梭子鱼形态特征鱼尾。分别以问题的稳态解和非稳态解研究了机器鱼巡游和加速游动以及沿鱼尾长度的驱动力分布。揭示了鱼尾形状对机器鱼性能的影响,同时也解释了鱼类游动的物理现象。研究结果对仿生机器鱼性能方面的设计有特殊的应用价值。更多还原

【Abstract】 Many new type micro robots that can swim smoothly in liquids medium have urgently been demanded in industrial,national defensive,petrochemical and medical fields due to constraints of the environment or other special conditions.Especially the wireless driven robot with high flexibility has being more popular with people.For instance,by using micro robots,a delicate surgical operation can avoid dismantling and reassembling,which minimizes the patient’s hurt.On the other hand,micro robots are often proposed to maintain factory pipelines or fault detection.The study on micro robot has enormously been developed with the coming forth and application of giant magnetostrictive materials,which can be controlled in wireless utilizing external magnetic field as a special intelligent material.Therefore,studying and designing advanced magnetic bionic robot fish has become a significative research choice. However,the key technologies and mechanism of this type of machine-driven fish should be further explored.In this paper,the mechanics model of a bionic robot fish,which is composed of muscle, tail and neural control system and simulated respectively by giant magnetostrictive material (GMM),elastic sheet and external magnetic field,is built.With the aid of its swimming mechanism,a GMM actuator(GMMA) is devised.The new type bionic robot fish controlled by GMMA,abandons traditional power system,paves a way for achieving micromation and has an extremely significance for working in pipelines.The effects of external magnetic field frequency,material parameters and geometrical parameters of fishtail on the average propulsion produced by swing tail are analyzed.It is found that the average driving force can reach a peak value when the forced external magnetic field has a same frequency as the tail system.Thus the robot fish swimming can be controlled by adjusting the frequency of the external magnetic field.The fishtail wakes for several system frequency modals are obtained through numerical simulation.The characteristics of tuna,pike and butterflyfish are simulated and the kinematic mechanism of swimming,acceleration and turning are discussed in detail.The numerical and analytical results show that the magnetostrictive effect of GMM can drive the fishtail’s swing,and the tail vibration modes can be controlled by frequency and magnetic density of the altemant external magnetic field.Generally,the best efficiency is obtained in second order vibration mode of the fishtail,and the reverse Karman Vortex Street wake is observed with corresponding frequency.The best frequency of external magnetic field corresponding to fish tail swing is changed with different liquid medium,fish tail material or geometrical shape.It should be pointed out that the influence of the tail length on robot swimming is also marked and each order vibration mode has a best tail length.Therefore,in order to adapt fish to specific environment,the swimming posture can be adjusted by changing the tail length.According to the above findings,the optimized fish length and external magnetic field frequency,a new type bionic robot fish with two tails is devised,which can move forward and backward by changing the magnetic field.Considering nonlinear damping and geometric large deformation,steady and nonsteady solutions of the main tail’s vibrational problem is discussed.Three kinds of fish tails are supposed,which are corresponding to square,tuna’s and pike’s tail respectively.It is found that the steady and nonsteady solutions are in accord with the dynamic characteristics of tuna and pike.Thus the influence of tail shape on robot fish performance is revealed,and the physical phenomenon of fish swimming is explained in this paper.Obviously,these study results have special using value for performance design of bionic robot fish.更多还原