Article
Development of a Bionic Dolphin Flexible Tail Experimental
Device Driven by a Steering Gear
Bo Zhang
1,
*, Qingxiang Li
1,
*, Tao Wang
2
and Zhuo Wang
1
Citation: Zhang, B.; Li, Q.; Wang, T.;
Wang, Z. Development of a Bionic
Dolphin Flexible Tail Experimental
Device Driven by a Steering Gear.
Actuators 2021, 10, 167. https://
doi.org/10.3390/act10070167
Academic Editor: Dario Richiedei
Received: 12 May 2021
Accepted: 12 July 2021
Published: 19 July 2021
Publisher’s Note: MDPI stays neutral
with regard to jurisdictional claims in
published maps and institutional affil-
iations.
Copyright: © 2021 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
1
College of Mechanical and Electrical Engineering, Harbin Engineering University, Harbin 150001, China;
wangzhuo_heu@hrbeu.edu.cn
2
School of Mechanical Engineering, Hebei University of Technology, Tianjin 300130, China;
1996075@hebut.edu.cn
* Correspondence: zhang-bo_heu@hrbeu.edu.cn (B.Z.); liqingxiang@hrbeu.edu.cn (Q.L.);
Tel.: +86-17864233610 (Q.L.)
Abstract:
In order to study the mechanism of the tail swing of the bionic dolphin, a flexible tail
experimental device based on a steering engine was developed. This study was focused on the
common three joint steering gear and its use in a bionic dolphin tail swing mechanism, and it was
found that the bionic dolphin driven by the steering gear had the problem of excessive stiffness. In
order to solve this problem, we designed a bionic dolphin tail swing mechanism. The tail swing
mechanism was designed rationally through the combination of a steering gear drive and two flexible
spines. Analysis of kinematic and dynamic modeling was further completed. Through simulation
using, the research on the bionic dolphin tail swing mechanism was verified. Experiments showed
that the swing curve formed by the steering gear-driven bionic dolphin tail swing mechanism with
two flexible spines fit the real fish body wave curve better than the original bionic dolphin tail
swing mechanism.
Keywords: bionic dolphin; flexible spine; swing mechanism; fish body wave curve
1. Introduction
With the continuous progress and development of science and technology, human
demand for natural resources is rising sharply. Land resources are gradually being depleted,
and there are abundant resources in the ocean, but most of the marine resources have
not been developed due to technological limitations [
1
–
4
]. In order to develop abundant
marine resources, many countries have developed various underwater vehicles [5].
The natural conditions of the seabed are relatively harsh, so there are higher perfor-
mance requirements for the development of underwater vehicles. In order for underwater
vehicles to move in the narrow and long area of the seabed, they must have high flexi-
bility and fast swimming speed [
6
,
7
]. Therefore, the development of high-performance
underwater vehicles has become a goal pursued by all countries.
In nature, fish have undergone screening and elimination by natural laws and evolved
a reasonable and ingenious body structure, which can greatly reduce the resistance of the
fluid. The swimming ability of fish is almost perfect, so they are a good research object.
Therefore, bionic robot fish technology has developed very rapidly, and the energy uti-
lization rate and propulsion performance have gradually been improved. This technology
was initially used to detect seabed conditions and oil pipelines in the process of offshore
oil exploitation. It was later used for underwater exploration, water quality sampling
and ocean current detection, and has even been used for the completion of military tasks,
such as surveillance and reconnaissance, mine sweeping and communication, underwater
intelligence collection, etc. Biomimetic robotic fish have potential advantages in terms of
concealment and mobility compared with propeller-based technologies, which grant them
Actuators 2021, 10, 167. https://doi.org/10.3390/act10070167 https://www.mdpi.com/journal/actuators
