This video presents a biomimetic propulsion mechanism, inspired by the flexible undulating fins encountered in certain electric eel species (knifefishes, in particular).
The prototype is comprised of eight actively-controlled fin rays (driven by R/C servos), which are interconnected by a flexible silicone membrane. Propulsion is obtained by the propagation of a traveling wave along the fin, obtained through appropriately coordinated motions of the rays.
The results from a series of detailed parametric investigations (sample runs are shown in this video) reveal several important findings regarding the effect of the undulatory wave kinematics on the propulsion speed and efficiency.
Based on these findings, two alternative strategies for propulsion control of the robotic fin have been developed. In the first one, the speed is varied through changes in the undulation amplitude (Amplitude Modulation Velocity Control scheme), while the second one involves simultaneous adjustment of the undulation frequency and number of waves (Frequency/Phase Modulation Velocity Control scheme), in a manner which enables attaining a specified desired swimming speed with optimum efficiency.
The video presents experiments demonstrating closed-loop position control of the prototype, based on these two strategies.
Additional details can be found in the following publication:
M. Sfakiotakis, J. Fasoulas, M.M. Kavoussanos, and M. Arapis, “Experimental investigation and propulsion control for a bio-inspired robotic undulatory fin,” Robotica, vol. 33, no. 5, pp. 1062–1084, 2015.
Post time: Jun-20-2017