MDPI - Publisher of Open Access Journals

21 pages, 1218 KiB

Open AccessEditor’s ChoiceArticle

Biomimetic Soft Underwater Robot Inspired by the Red Muscle and Tendon Structure of Fish

by Daisuke Aragaki, Toi Nishimura, Ryuki Sato and Aiguo Ming

Biomimetics 2023, 8(2), 133; https://doi.org/10.3390/biomimetics8020133 - 24 Mar 2023

Cited by 8 | Viewed by 4065

Underwater robots are becoming increasingly important in various fields. Fish robots are attracting attention as an alternative to the screw-type robots currently in use. We developed a compact robot with a high swimming performance by mimicking the anatomical structure of fish. In this paper, we focus on the red muscles, tendons, and vertebrae used for steady swimming of fish. A robot was fabricated by replacing the red muscle structure with shape memory alloy wires and rigid body links. In our previous work, undulation motions with various phase differences and backward quadratically increasing inter-vertebral bending angles were confirmed in the air, while the swimming performance in insulating fluid was poor. To improve the swimming performance, an improved robot was designed that mimics the muscle contractions of mackerel using a pulley mechanism, with the robot named UEC Mackerel. In swimming experiments using the improved robot, a maximum swimming speed of 25.8 mm/s (0.11 BL/s) was recorded, which is comparable to that of other soft-swimming robots. In addition, the cost of transport (COT), representing the energy consumption required for robot movement, was calculated, and a minimum COT of 0.08 was recorded, which is comparable to that of an actual fish. Full article

(This article belongs to the Special Issue Latest Trends in Bio-Inspired Underwater Robotics)

► Show Figures

Figure 1

17 pages, 6784 KiB

Open AccessArticle

Optimum Curvature Characteristics of Body/Caudal Fin Locomotion

by Yanwen Liu and Hongzhou Jiang

J. Mar. Sci. Eng. 2021, 9(5), 537; https://doi.org/10.3390/jmse9050537 - 17 May 2021

Cited by 6 | Viewed by 4262

Abstract

Fish propelled by body and/or caudal fin (BCF) locomotion can achieve high-efficiency and high-speed swimming performance, by changing their body motion to interact with external fluids. This flexural body motion can be prescribed through its curvature profile. This work indicates that when the fish swims with high efficiency, the curvature amplitude reaches a maximum at the caudal peduncle. In the case of high-speed swimming, the curvature amplitude shows three maxima on the entire body length. It is also demonstrated that, when the Reynolds number is in the range of 10⁴–10⁶, the swimming speed, stride length, and Cost of Transport (COT) are all positively correlated with the tail-beat frequency. A sensitivity analysis of curvature amplitude explains which locations change the most when the fish switches from the high-efficiency swimming mode to the high-speed swimming mode. The comparison among three kinds of BCF fish shows that the optimal swimming performance of thunniform fish is almost the same as that of carangiform fish, while it is better not to neglect the reaction force acting on an anguilliform fish. This study provides a reference for curvature control of bionic fish in a future time. Full article

(This article belongs to the Section Ocean Engineering)

► Show Figures

Figure 1

24 pages, 9753 KiB

Open AccessArticle

Mechatronic Design and Manufacturing of the Intelligent Robotic Fish for Bio-Inspired Swimming Modes

by Mustafa Ay, Deniz Korkmaz, Gonca Ozmen Koca, Cafer Bal, Zuhtu Hakan Akpolat and Mustafa Can Bingol

Electronics 2018, 7(7), 118; https://doi.org/10.3390/electronics7070118 - 18 Jul 2018

Cited by 29 | Viewed by 8939

Abstract

This paper presents mechatronic design and manufacturing of a biomimetic Carangiform-type autonomous robotic fish prototype (i-RoF) with two-link propulsive tail mechanism. For the design procedure, a multi-link biomimetic approach, which uses the physical characteristics of a real carp fish as its size and structure, is adapted. Appropriate body rate is determined according to swimming modes and tail oscillations of the carp. The prototype is composed of three main parts: an anterior rigid body, two-link propulsive tail mechanism, and flexible caudal fin. Prototype parts are produced with 3D-printing technology. In order to mimic fish-like robust swimming gaits, a biomimetic locomotion control structure based on Central Pattern Generator (CPG) is proposed. The designed unidirectional chained CPG network is inspired by the neural spinal cord of Lamprey, and it generates stable rhythmic oscillatory patterns. Also, a Center of Gravity (CoG) control mechanism is designed and located in the anterior rigid body to ensure three-dimensional swimming ability. With the help of this design, the characteristics of the robotic fish are performed with forward, turning, up-down and autonomous swimming motions in the experimental pool. Maximum forward speed of the robotic fish can reach 0.8516 BLs^-1 and excellent three-dimensional swimming performance is obtained. Full article

► Show Figures

Figure 1

Search Results (3)

Further Information

Guidelines

MDPI Initiatives

Follow MDPI

Saved Queries

Search Filter Reset All

Years

Feature Papers

Subjects

Journals

Article Types

Countries / Regions

Search Results (3)

Further Information

Guidelines

MDPI Initiatives

Follow MDPI