基于输流软管驱动的仿水母动力学设计、仿真与实验

Dynamic design,simulation,and experiment on a bioinspired jellyfish driven by soft pipes conveying fluid

本文创新性地提出了一种基于输流软管变形驱动的新型仿水母机器人设计.当弯曲初始构型的软管输送流体时会产生较大的变形,在流速为零时软管便会恢复到初始构型,通过利用软管周期性的变形-恢复原理达到驱动目的.首先,基于绝对节点坐标法建立了输流软管的非线性动力学理论模型,通过动力学分析确定了在较小流速下产生较大变形的软管构型设计.然后,按照该弯曲初始构型制作了仿水母软体触手,并在水中开展了不同流速下的变形-恢复实验研究,与理论模型预测结果进行了对比.此外,发展了结构变形与流体动力学耦合的仿真方法,探究了仿水母机器人的内部流速和触手个数对作用在触手上的流体力的影响规律.研究表明,内流速越大,触手变形也越大,触手摆动频率降低,但最大流体力逐渐增大;在内流速相同的情况下,触手个数对单个触手变形产生的最大流体力没有影响.最后,通过3D打印制作了头部和三通接头,与软体触手共同组成仿水母机器人,在水下进一步开展了推进实验研究.实验表明,随着电压(内部流速)的增大,软体触手变形越大,推进速度也越大;相比于喷水推进模式,通过利用软体触手变形可提高28%的推进速度.本研究为水下仿生机器人驱动方式提供了一种新的设计策略.

A new bioinspired jellyfish robot propelled by the deformation of soft pipes conveying fluid is proposed in the present study.The initially curved soft pipe conveying fluid can result in large deformations.At zero internal flow velocity,the soft pipe returns to its initial configuration.Actuation can be achieved utilizing the periodic deformation and recovery of the soft pipe.Based on the absolute nodal coordinate formulation(ANCF)method,a nonlinear dynamic theoretical model of the soft pipe was established.The optimal initial configuration of the soft pipe was determined through dynamic analysis.Subsequently,soft appendages were fabricated according to the initial curved-pipe configuration.Deformation and recovery experiments were performed underwater at different internal flow velocities,and the results were compared with those obtained using the theoretical model.In addition,a coupling simulation method was developed for structural deformation and fluid dynamics.The influence of the internal flow velocity and number of appendages on the fluid force acting on the appendages was investigated.Results show that the larger the internal flow velocity,the greater the appendage deformation and the smaller the appendage swing frequency,but the maximum fluid force increased gradually.For the same internal flow velocity,the number of appendages does not affect the maximum fluid force of a single appendage.Finally,head and tee connectors were fabricated using 3D printing,which,together with the soft appendages,formed a waterproof jellyfish robot.Further experimental research on appendage swing and propulsion was performed underwater.Experimental results showed that with increasing voltage(internal velocity),appendage deformation and propulsion speed increased.Importantly,the propulsion speed could be enhanced by 28% for the robot with soft appendages compared to that without appendages in the pure jet mode.This research provides a new strategy for designing the actuation mode for an underwater robot.