Asymmetrical Oscillating Morphology Hydrodynamic Performance of a Novel Bionic Pectoral Fin

Abstract

This research proposes a novel bionic pectoral fin and experimentally studied the effects of the oscillation parameters on the hydrodynamic performance of a bionic experimental prototype. Inspired by manta rays, the bionic pectoral fin was simplified and modeled based on the natural pectoral fin skeleton structure and oscillation morphology of this underwater creature. A dual-degree-of-freedom bionic pectoral fin was designed. The active spatial motion was realized by the space six-link mechanism driven by two motors, and the passive deformation was achieved by carbon fiber. The motion analysis of the bionic pectoral fin proves that the pectoral fin can realize an “8”-shaped spatial trajectory. An experimental prototype was developed accordingly. The experimental prototype could flap between 0.1 Hz and 0.6 Hz and produce a maximum thrust of 20 N. The hydrodynamic performance under different oscillation parameters was studied experimentally in a water pool. The experimental results indicate that the hydrodynamic performance of the pectoral fin oscillation is closely related to the motion equation parameters including the amplitude, frequency, phase difference, and initial bias. In addition to considering the impact of parameters on thrust and lift, the influences of asymmetrical oscillation on the position of the equivalent point were also studied. The results show that the pectoral fin proposed in this research exhibited the expected spatial deformation and outstanding hydrodynamic performance. The obtained results shed light on the updated design and control of a bionic robot fish.

A Novel Integrated Gliding and Flapping Propulsion Biomimetic Manta-Ray Robot

“…The mechanism schematic is described in Figure 5a, and the three-dimensional model of the pectoral fin is shown in Figure 2d. The flexible pectoral fin comprises driving steering gears 1 and 2, a secondary link mechanism, flexible carbon fiber fin rays, and an elastic skin [36]. When the pectoral fin flaps, the motors drive the steering gear to make the driving rod swing back and forth along the spanwise direction.…”

Similarity Evaluation Rule and Motion Posture Optimization for a Manta Ray Robot

“…The pectoral fins on both sides of the manta ray robot are completely symmetrical; therefore, the analysis of the motion performance of the pectoral fins is only performed on one side of the pectoral fins. If the flexible deformation of the fins is ignored, the displacement of the endpoint of the fins along the Z-axis direction i h is related to the rudder output angle i θ as follows: sin( ) However, under the condition that the current and the flexibility of the fins themselves exist, the fins exhibit not only active deformation controlled by the rudder output but also passive flexibility along the spreading direction [25]. The actual flap of the fins underwater is smaller than that under active control.…”

“…However, under the condition that the current and the flexibility of the fins themselves exist, the fins exhibit not only active deformation controlled by the rudder output but also passive flexibility along the spreading direction [25]. The actual flap of the fins underwater is smaller than that under active control.…”

Effects of Bionic Bone Flexibility on the Hydrodynamics of Pectoral Fins

“…The two-dimensional flexible flapping pectoral fin can be considered to be a flexible thin wing, and the flapping wings' curve after the flexible deformation is used instead of the mid-arc line so as to carry out the analysis. The two-dimensional pectoral fin used in this paper is designed as two equilateral triangles considering that the real manta ray shape is approximated as a diamond shape [35].…”