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A three-joint design method for robotic fish based on improved fish body wave equation

A design method, the technology of robotic fish, applied in the direction of non-rotating propulsion elements, etc., can solve the problems of stress concentration at the joint drive rod connection, limit the swing freedom of the robot fish, and the drive rod is prone to breakage, so as to avoid breakage and achieve good results. The effect of meeting the fish movement curve and good propulsion performance

Active Publication Date: 2019-03-26
HOHAI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] The joint structure of the existing robot fish, such as the application number is 201510557116X, and the invention name is a patent for the swing mechanism of a bionic intelligent robot fish. The fish body includes three main drive joints, such as Figure 5 As shown in 5a and 5b, each main driving joint includes a steering gear (4) and a driving rod (3). After many experiments by the applicant, it is concluded that this structure with only three main driving joints limits the The swing degree of freedom of the fish makes it easy to get out of joint when swimming, and the middle part of the drive rod is prone to breakage. According to the research and analysis, it is concluded that the drive rod should not only bear the force in the swing direction (that is, the horizontal direction), but also To bear its own gravity (that is, the vertical direction), the resultant force borne by the drive rod is relatively large, and it is easy to cause stress concentration at the connection of the joint drive rod, because it is easy to cause fracture

Method used

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  • A three-joint design method for robotic fish based on improved fish body wave equation
  • A three-joint design method for robotic fish based on improved fish body wave equation
  • A three-joint design method for robotic fish based on improved fish body wave equation

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Embodiment 1

[0037] A three-joint design method for a robotic fish based on the improved fish body wave equation. The robotic fish includes three main drive joints, namely the first main drive joint, the second main drive joint, and the third main drive joint. The design method includes :

[0038] Step 1, take the original kinematics model f of the bionic robotic fish B Based on (x, t), the improved fish body wave equation is derived under the condition of considering the shaking of the fish head.

[0039] Through research on fish, biologists have concluded that fish will produce a traveling wave in the process of steady-state cruise. This kind of wave propagates from the fluctuation starting point of the fish trunk to the tail, and the amplitude gradually increases, which is called fish body wave. According to the slender body theory proposed by Lighthill, the fish body wave is a traveling wave system whose amplitude gradually increases. is approximated by a polynomial and sinusoidal c...

Embodiment 2

[0102] Such as Figure 7 , 8 As shown, the difference between this embodiment and Embodiment 1 is that there is a connecting rod 9 inside the support ring near the back of the fish, and the upper and lower end surfaces of the connecting rod are provided with slots for engaging the second connecting part of the vertebral hinge. 10. Inside the support ring connected to the steering gear of the active drive joint, there is a slot 11 for clamping the steering gear near the belly of the fish.

[0103] In order to increase the buoyancy of the robot fish, foam is arranged between the inside of the support ring, the spine hinge and the steering gear.

Embodiment 3

[0105] Such as Figure 9 As shown, the difference between this embodiment and Embodiment 1 is that the steering gear is arranged in the steering gear housing 1, which is made of waterproof material to protect the steering gear from being immersed in water, and the steering gear housing is provided with an arc track 12.

[0106] The external force on the drive rod mainly comes from the reaction force of the water when the steering gear drives the main drive joint to swing. The applicant used ANSYS Workbench to conduct a static analysis of the drive rod, and concluded that the maximum pressure point and maximum deformation are in the middle part of the drive rod, so a support rod 13 is vertically connected downwards in the middle part of the drive rod, and the support rod A rolling ball is connected to the bottom end of the steering wheel, the steering gear drives the driving rod to rotate, and the driving rod drives the support rod and the rolling ball to roll back and forth in...

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Abstract

The invention discloses a three-joint design method for a robot fish based on an improved fish body wave equation and provides a theoretical basis for the study of the robot fish. The improved fish body wave equation is derived under the consideration of swaying of a fish head. The three-joint design method is designed and calculated based on the improved fish body wave equation, so that the swimming of the robot fish designed according to the three-joint design method is more in accordance with motion laws of real fishes. By controlling a governing equation of driving joints, the bionic robot fish is capable of quickly steering and obtaining a greater turning moment, thereby realizing good propulsion performance. A three-joint structure is provided with the driving joints and driven joints and vertebra hinges of the driven joints are designed according to vertebrae of the real fishes, thereby increasing the freedom of motion of the robot fish, allowing the swimming of the robot fish to be better in accordance with the motion curve of the real fishes and more similar to the real fishes, and avoiding the disjunction during the swimming of the robot fish.

Description

technical field [0001] The invention relates to the technical field of robotic fish, in particular to a three-joint design method for robotic fish based on an improved fish body wave equation. Background technique [0002] The joint structure of the existing robot fish, such as the application number is 201510557116X, and the invention name is a patent for the swing mechanism of a bionic intelligent robot fish. The fish body includes three main drive joints, such as Figure 5 As shown in 5a and 5b, each main driving joint includes a steering gear (4) and a driving rod (3). After many experiments by the applicant, it is concluded that this structure with only three main driving joints limits the The swing degree of freedom of the fish makes it easy to get out of joint when swimming, and it is easy to break in the middle part of the drive rod. To bear its own gravity (that is, the vertical direction), the resultant force borne by the driving rod is relatively large, and it is ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B63H1/36
CPCB63H1/36
Inventor 娄保东丛宇
Owner HOHAI UNIV