Department of Mechanical Engineering, Northwestern University, Evanston, IL, USA.
Bioinspir Biomim. 2011 Jun;6(2):026004. doi: 10.1088/1748-3182/6/2/026004. Epub 2011 Apr 7.
South American electric knifefish are a leading model system within neurobiology. Recent efforts have focused on understanding their biomechanics and relating this to their neural processing strategies. Knifefish swim by means of an undulatory fin that runs most of the length of their body, affixed to the belly. Propelling themselves with this fin enables them to keep their body relatively straight while swimming, enabling straightforward robotic implementation with a rigid hull. In this study, we examined the basic properties of undulatory swimming through use of a robot that was similar in some key respects to the knifefish. As we varied critical fin kinematic variables such as frequency, amplitude, and wavelength of sinusoidal traveling waves, we measured the force generated by the robot when it swam against a stationary sensor, and its velocity while swimming freely within a flow tunnel system. Our results show that there is an optimal operational region in the fin's kinematic parameter space. The optimal actuation parameters found for the robotic knifefish are similar to previously observed parameters for the black ghost knifefish, Apteronotus albifrons. Finally, we used our experimental results to show how the force generated by the robotic fin can be decomposed into thrust and drag terms. Our findings are useful for future bio-inspired underwater vehicles as well as for understanding the mechanics of knifefish swimming.
南美电鳗是神经生物学中的主要模式生物系统。最近的研究重点是了解它们的生物力学，并将其与神经处理策略联系起来。电鳗通过身体大部分长度的波动鳍游泳，鳍固定在腹部。用这种鳍推动自己，使它们在游泳时身体相对保持笔直，从而可以使用刚性船体进行简单的机器人实现。在这项研究中，我们使用类似于电鳗的机器人研究了波动游泳的基本特性。当我们改变关键的鳍运动学变量，如正弦行波的频率、振幅和波长时，我们测量了机器人在对抗固定传感器游泳时产生的力，以及它在流动隧道系统中自由游泳时的速度。我们的结果表明，鳍的运动学参数空间中有一个最佳的操作区域。为机器人电鳗找到的最佳驱动参数与先前观察到的黑鬼电鳗（Apteronotus albifrons）的参数相似。最后，我们使用实验结果展示了如何将机器人鳍产生的力分解为推力和阻力项。我们的发现对于未来的仿生水下机器人以及理解电鳗游泳的力学都很有用。
