A double-joint flexible robotic fish based on hydraulic drive

Abstract

The present application belongs to the field of underwater bionic robots, and particularly relates to a double-joint flexible robot fish based on hydraulic drive. In the present application, the fish tail of the robot fish adopts a flexible joint, the flexible joint comprising a flexible matrix and a driving unit located inside the flexible matrix, the driving unit being arranged on the left and right sides of the central axial surface of the flexible joint and arranged along the axial direction of the fish body; when driving medium is pumped into the driving unit, the driving unit is axially contracted, and when the driving medium is sucked out of the driving unit, the driving unit is radially expanded; the driving medium is pumped into the driving unit on one side of the central axial surface of the flexible joint through a driving assembly, while the driving medium is sucked out of the driving unit on the other side of the central axial surface of the flexible joint, so that the whole flexible joint is deflected to the side where the driving medium is pumped in; by alternately pumping in from one side and sucking out from the other side of the driving medium, the fish tail is driven to swing.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of underwater bionic robots, and particularly relates to a double-joint flexible robotic fish based on hydraulic driving. BACKGROUND

[0002] For millions of years, natural selection has endowed fish with a nearly perfect body structure that enables them to quickly maneuver in underwater environments. Bionic robotic fish can achieve stronger maneuverability, lower noise and higher efficiency compared with traditional underwater robots with propeller propulsion by simulating the swimming mode of fish. In recent years, researchers have designed various mechanical structures to simulate the swimming characteristics of fish, which can be mainly divided into two types: discrete rigid structures and continuous flexible structures. The former mainly consists of rigid joints driven by motors and has made great progress in the past few decades due to its ease of design and control. However, rigid discrete structure robots have the disadvantages of high failure rate and high noise, and may harm marine life.

[0003] Thanks to the rapid development of material science and intelligent manufacturing, underwater robots with continuous flexible structures are becoming a research hotspot. Compared with traditional rigid robotic fish, flexible robotic fish has strong anti-collision ability, more compliant body, lower noise and is more environmentally friendly. In recent years, researchers have successfully applied pressure driving (pneumatic, hydraulic and chemical reaction driving) to flexible bionic robotic fish. However, soft underwater robots driven by pressure also have disadvantages, such as difficulty in manufacturing and integrating lightweight and small control valves and pressure pumps, single number of joints, low driving frequency, difficulty in deformation sensing of drivers, etc.

[0004] The technical solution most similar to the present application is a patent with the patent number CN110316342A and the patent name of a liquid-driven flexible bionic fish and its working method. The disclosed technical solution of this patent uses a booster pump, a pressure regulating valve and an electromagnetic reversing valve to provide pressure for the driving unit inside the fish tail. The fish tail is purely flexible, the driving unit has no fixation at both ends, the fish tail is hollow inside and has no flexible sensor as feedback, the pectoral fin cannot move, and the hydraulic circuit inside the fish body is external circulation, which has obvious disadvantages. SUMMARY

[0005] The purpose of the present application is to provide a double-joint flexible robotic fish based on hydraulic driving, which can effectively solve the problems of low energy density, low frequency response and slow speed of existing hydraulic flexible robotic fish.

[0006] The purpose of the present application is achieved by the following technical solution:

[0007] A double-joint flexible robotic fish driven by hydraulic pressure, comprising a fish head and a fish tail; the fish tail comprises a flexible joint; the flexible joint comprises a flexible matrix and a driving unit inside the flexible matrix; the driving unit is arranged on the left and right sides of the central axial surface of the flexible joint respectively and arranged along the axial direction of the fish body; the fish head is internally provided with a driving assembly; when driving medium is pumped into the driving unit, the driving unit is axially contracted, and when the driving medium is pumped out of the driving unit, the driving unit is radially expanded; the driving medium is pumped into the driving unit on one side of the central axial surface of the flexible joint through the driving assembly, and the driving medium is pumped out of the driving unit on the other side of the central axial surface of the flexible joint at the same time, so that the flexible joint is deflected to the side where the driving medium is pumped in; the driving medium is alternately pumped in from one side and pumped out from the other side, so as to drive the fish tail to swing.

[0008] Further, the fish tail comprises a large connector, a middle connector, a small connector and a tail fin, the large connector is connected with the fish head, the large connector is connected with the middle connector through the flexible joint I, and the middle connector is connected with the small connector through the flexible joint II.

[0009] Further, the front side of the large connector is provided with four groups of hydraulic cylinder oil inlet interfaces, the rear side is provided with a large connector left side driving unit oil inlet, a large connector right side driving unit oil inlet and two groups of large connector oil inlets, all the large connector left side driving unit oil inlets are connected to one group of hydraulic cylinder oil inlet interfaces through the pipeline inside the large connector, all the large connector right side driving unit oil inlets are connected to another group of hydraulic cylinder oil inlet interfaces through the pipeline inside the large connector, and the other two groups of hydraulic cylinder oil inlet interfaces are connected with the two groups of large connector oil inlets through the pipeline inside the large connector;

[0010] The front side of the middle connector is provided with a middle connector driving unit joint and two groups of middle connector oil inlets, the rear side of the middle connector is provided with a middle connector left side driving unit oil inlet and a middle connector right side driving unit oil inlet, one group of middle connector oil inlets is connected with the middle connector left side driving unit oil inlet through the pipeline inside the middle connector, and the other group of connector oil inlets is connected with the middle connector right side driving unit oil inlet through the pipeline inside the middle connector;

[0011] The front side of the small connector is provided with a small connector driving unit joint, and the rear side of the small connector is connected with the tail fin.

[0012] Further, the flexible matrix of the flexible joint I is provided with a central axial surface left side joint I driving unit group, a central axial surface right side joint I driving unit group and two groups of oil inlets; the flexible matrix of the flexible joint II is provided with a central axial surface left side joint II driving unit group and a central axial surface right side joint II driving unit group;

[0013] The front end of the driving unit in the middle axial surface left joint I driving unit group is connected with the large connecting body left side driving unit oil inlet, and the rear end is connected with the middle connecting body driving unit joint; the front end of the driving unit in the middle axial surface right joint I driving unit group is connected with the large connecting body right side driving unit oil inlet, and the rear end is connected with the middle connecting body driving unit joint; the front end of the oil inlet pipe is connected with the large connecting body oil inlet, and the rear end is connected with the middle connecting body oil inlet;

[0014] The front end of the driving unit in the middle axial surface left joint I driving unit group is connected with the large connecting body left side driving unit oil inlet, and the rear end is connected with the middle connecting body driving unit joint; the front end of the driving unit in the middle axial surface right joint I driving unit group is connected with the large connecting body right side driving unit oil inlet, and the rear end is connected with the middle connecting body driving unit joint.

[0015] Further, a flexible sensor is arranged on the middle axis of the flexible matrix of the flexible joint I and the flexible matrix of the flexible joint II, for detecting the swing angle of the flexible joint I and the flexible joint II.

[0016] Further, the number of the large connecting body left side driving unit oil inlets matches the number of the driving units in the middle axial surface left joint I driving unit group, the number of the large connecting body right side driving unit oil inlets matches the number of the driving units in the middle axial surface right joint I driving unit group, the number of the middle connecting body driving unit joints matches the number of the driving units in the flexible joint I, the number of the middle connecting body left side driving unit oil inlets matches the number of the driving units in the middle axial surface left joint II driving unit group, the number of the middle connecting body right side driving unit oil inlets matches the number of the driving units in the middle axial surface right joint II driving unit group, and the number of the small connecting body driving unit joints matches the number of the driving units in the flexible joint II.

[0017] Further, the driving assembly comprises a four-cylinder plunger pump, which has four groups of oil inlets, and the four groups of hydraulic cylinder oil inlet interfaces on the front side of the large connecting body are connected with the four groups of oil inlets of the four-cylinder plunger pump.

[0018] Further, the four-cylinder plunger pump comprises a hydraulic cylinder body, which has a four-cylinder structure and comprises two pairs of upper and lower cylinder bodies, each of which is provided with a piston; the upper and lower sides of the hydraulic cylinder body are provided with rudder fixed plates, each of which is fixed with a pair of plunger pump rudders, and the output shaft of each plunger pump rudder is connected with the piston in a group of cylinder bodies in the hydraulic cylinder body through a crank slider mechanism, and the rotary motion of the plunger pump rudder output shaft is converted into the reciprocating motion of the piston in the cylinder body through the crank slider mechanism.

[0019] Further, the top surface of the fish head is provided with a dorsal fin, and the left and right sides of the fish head are provided with pectoral fins; the driving assembly comprises a pectoral fin assembly; the pectoral fin assembly comprises a pectoral fin support, and pectoral fin steering engines are connected to the left and right sides of the pectoral fin support; the output shafts of the pectoral fin steering engines are connected to the pectoral fin group through connecting shaft groups; during the operation of the robotic fish, the robotic fish can realize floating and diving by adjusting the angles of the pectoral fins on the left and right sides of the fish head.

[0020] Further, the top surface of the fish head is provided with an antenna, the inside of the fish head is provided with a fish head support frame, a partition layer with a grid is arranged on the fish head support frame, a large PCB board and a small PCB board are arranged above the partition layer, and a battery pack is arranged below the partition layer; the large PCB board is provided with a voltage stabilizing module and a current sensor module, and the small PCB board is provided with a control single-chip microcomputer and a signal transmitter.

[0021] The present application has the following advantages:

[0022] The fish tail of the bionic robotic fish provided by the present application adopts a flexible joint, the flexible joint comprises a flexible matrix and a driving unit arranged in the flexible matrix, the driving unit is arranged on the left and right sides of the central axial surface of the flexible joint and arranged in the axial direction of the fish body, when the driving medium is pumped into the driving unit, the driving unit is axially contracted, and when the driving medium is pumped out of the driving unit, the driving unit is radially expanded; the driving medium is pumped into the driving unit on one side of the central axial surface of the flexible joint through the driving assembly, and the driving medium is pumped out of the driving unit on the other side of the central axial surface of the flexible joint at the same time, so that the flexible joint is deflected to the side where the driving medium is pumped in; the driving medium is alternately pumped in from one side and pumped out from the other side, so that the fish tail is driven to swing. The present application adopts a four-cylinder plunger pump to provide pressure, and the pressure regulating valve and the electromagnetic reversing valve are omitted; the fish tail is a rigid-flexible coupling structure, the two ends of the driving unit are fixed to the connecting body, and the fish tail is further provided with an oil delivery pipe and a flexible sensor in the inside; the pectoral fin can rotate; the hydraulic circuit is an internal circulation, which not only reduces the cost, but also realizes more flexible underwater swinging. The present application can effectively break through the limitations of the existing hydraulic flexible robotic fish, such as low energy density, low frequency response and slow speed, and has a wide application prospect in the fields of underwater exploration and underwater rescue. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of a double-joint flexible robotic fish based on hydraulic driving.

[0024] Figure 2 It is an exploded view of the fish head part.

[0025] Figure 3 It is an exploded view of the driving assembly.

[0026] Figure 4 It is a working principle diagram of the four-cylinder plunger pump.

[0027] Figure 5 Exploded view of the fish tail portion.

[0028] Figure 6 Isometric view of the large connector, middle connector and small connector.

[0029] Figure 7 Schematic diagram of the deformation of the fish tail.

[0030] Wherein the above drawings include the following reference signs:

[0031] 1, fish head; 2, fish tail;

[0032] 1-1, upper cover; 1-2, switch group; 1-3, antenna; 1-4, charging interface; 1-5, control single-chip microcomputer; 1-6, signal transmitter; 1-7, small PCB board; 1-8, voltage stabilizing module; 1-9, large PCB board; 1-10, current sensor module; 1-11, fish head support frame; 1-12, battery assembly; 1-13, battery package counterweight group; 1-14, lower cover; 1-15, drive assembly; 1-15-1, pectoral fin assembly; 1-15-1-1, pectoral fin; 1-15-1-2, connecting shaft assembly; 1-15-1-3, pectoral fin steering engine assembly; 1-15-1-4, pectoral fin support; 1-15-2, four-cylinder plunger pump; 1-15-2-1, plunger pump steering engine; 1-15-2-2, steering engine fixing plate; 1-15-2-3, steering arm; 1-15-2-4, thin pin; 1-15-2-5, connecting rod; 1-15-2-6, thick pin; 1-15-2-7, piston; 1-15-2-8, hydraulic cylinder body; 1-15-2-9, vertically arranged counterweight group; 1-15-2-10, horizontally arranged counterweight group;

[0033] 2-1, large connector; 2-1-1, hydraulic cylinder oil inlet interface; 2-1-2, large connector sensor slot; 2-1-3, large connector oil inlet; 2-1-4, large connector drive unit oil inlet; 2-2, joint I flexible matrix; 2-3, right joint I drive unit group of middle axial surface; 2-4, joint I flexible sensor; 2-5, oil supply pipe; 2-6, left joint I drive unit group of middle axial surface; 2-7, middle connector; 2-7-1, middle connector drive unit joint; 2-7-2, middle connector sensor slot; 2-7-3, middle connector oil inlet; 2-7-4, middle connector drive unit oil inlet; 2-8, joint II flexible matrix; 2-9, right joint II drive unit group of middle axial surface; 2-10, joint II flexible sensor; 2-11, left joint II drive unit group of middle axial surface; 2-12, small connector; 2-12-1, small connector drive joint; 2-12-2, small connector slot; 2-13, tail fin; 2-A, flexible joint I; 2-B, flexible joint II. DETAILED DESCRIPTION

[0034] The present application is further described below with reference to the accompanying drawings.

[0035] The present application provides a double-joint flexible robotic fish based on hydraulic drive, which comprises a fish head and a fish tail, the fish tail comprises three connecting bodies of large, medium and small and a tail fin, there is a flexible joint between two adjacent connecting bodies, each flexible joint has a pair of driving unit groups arranged along the fish body axis, there is a flexible sensor on the neutral layer of the joint to feed back the angle of the driver in real time, and the whole joint is wrapped by a flexible matrix. A four-cylinder plunger pump alternately pumps driving medium into or out of the pair of driving unit groups, the driving unit groups are contracted under pressure, thereby driving the joint to bend, and further causing the fish tail to swing. The present application can effectively break through the limitations of low energy density, low frequency response and slow speed of existing hydraulic flexible robotic fish, and has broad application prospects in the fields of underwater exploration and underwater rescue.

[0036] As shown in Figure 1 , a double-joint flexible robotic fish based on hydraulic drive mainly comprises a fish head 1 and a fish tail 2. The exploded view of the fish head 1 is shown in Figure 2 , and the upper cover 1-1 and the lower cover 1-14 are respectively installed at the upper and lower openings of the fish head support frame 1-11. Four mounting holes are left on the top of the upper cover 1-1, the switch group 1-2 is installed in the two front mounting holes, and the antenna 1-3 and the charging interface 1-4 are respectively installed in the two rear mounting holes.

[0037] The fish head support frame 1-11 has a partition with a grid in the middle, a large PCB board 1-9 and a small PCB board 1-7 are installed above the partition, a voltage stabilizing module 1-8 and a current sensor module 1-10 are welded on the large PCB board 1-9, and a control single-chip microcomputer 1-5 and a signal transmitter 1-6 are welded on the small PCB board 1-7. The battery pack 1-12 and the battery wrapping counterweight group 1-13 are installed below the partition of the fish head support frame 1-11, the end of the battery wrapping counterweight group 1-13 is connected with the partition of the fish head support frame 1-11, and the inside wraps the battery pack 1-12. The driving assembly 1-15 is connected to the rear side of the partition of the fish head support frame 1-11.

[0038] The exploded view of the driving assembly 1-15 is shown in Figure 3 , and the driving assembly 1-15 comprises a pectoral fin assembly 1-15-1 and a four-cylinder plunger pump 1-15-2.

[0039] The pectoral fin assembly 1-15-1 mainly comprises a pectoral fin support 1-15-1-4, and the pectoral fin support is connected with a pectoral fin steering engine assembly 1-15-1-3 on both sides, the output shaft of the pectoral fin steering engine assembly drives the pectoral fin 1-15-1-1 through a connecting shaft group 1-15-1-2. During the operation of the robotic fish, adjusting the angle of the driving pectoral fin 1-15-1-1 can make the robotic fish realize the functions of floating and diving.

[0040] The four-cylinder piston pump 1-15-2 mainly comprises a hydraulic cylinder body 1-15-2-8, which is a four-cylinder structure, and two pairs of upper and lower cylinder bodies, and a piston 1-15-2-7 is installed in each cylinder body. The hydraulic cylinder body 1-15-2-8 is connected with a rudder fixing plate 1-15-2-2 above and below, respectively, each rudder fixing plate 1-15-2-2 fixes a pair of piston pump rudders 1-15-2-1, and the lower rudder fixing plate 1-15-2-2 is connected with a vertically arranged weight group 1-15-2-9 and a horizontally arranged weight group 1-15-2-10. The output shaft of each piston pump rudder 1-15-2-1 is connected with a rudder arm 1-15-2-3, the rudder arm 1-15-2-3 is hinged with a connecting rod 1-15-2-5 through a thin pin 1-15-2-4, and the connecting rod 1-15-2-5 is hinged with the piston 1-15-2-7 through a thick pin 1-15-2-6, so that the rudder and the rudder arm 1-15-2-3, the connecting rod 1-15-2-5 and the piston 1-15-2-7 are hinged together to form a “crank-slider” motion, and the output shaft of the piston pump rudder 1-15-2-1 rotates to drive the piston to reciprocate in the cylinder body.

[0041] The four-cylinder piston pump 1-15-2 is divided into two groups of piston pumps, and the working principle of the four-cylinder piston pump 1-15-2 is introduced by taking one group of piston pumps as an example. As shown in the sectional view A-A of the upper piston pump group, Figure 4 in state A-A-1, the output shaft of the upper rudder rotates counterclockwise to drive the piston 1-15-2-6 to slide outwards, and the driving medium is sucked from the oil inlet 1-15-2-8-1, at the same time, the output shaft of the lower rudder rotates counterclockwise to drive the piston 1-15-2-6 to slide inwards, and the driving medium is pumped out from the oil inlet 1-15-2-8-1. Then the state is changed to A-A-2, the output shaft of the upper rudder rotates clockwise to drive the piston 1-15-2-6 to slide inwards, and the driving medium is pumped out from the oil inlet 1-15-2-8-1, at the same time, the output shaft of the lower rudder rotates clockwise to drive the piston 1-15-2-6 to slide outwards, and the driving medium is sucked from the oil inlet 1-15-2-8-1. In the working process of the bionic robotic fish, the two states are constantly changed.

[0042] As shown in the top view of the fish tail 2, Figure 5 the symmetry plane of the fish tail 2 is defined as the central axis plane, and the fish tail 2 comprises a flexible joint I (2-A) and a joint II (2-B). The fish tail 2 mainly comprises a large connecting body 2-1, a middle connecting body 2-7 and a small connecting body 2-12, and the axonometric view thereof is as shown in Figure 6As shown, the large connector 2-1 is connected with the fish head support frame 1-11, and the four hydraulic cylinder oil outlet interfaces 2-1-1 on the front side are connected with the four oil outlet ports 1-15-2-8-1 of the hydraulic cylinder body 1-15-2-8. Among them, the hydraulic cylinder oil outlet interface 2-1-1 on the upper left of the central axis surface is in communication with the five large connector drive unit oil outlet ports 2-1-4 on the left side of the central axis surface, and the hydraulic cylinder oil outlet interface 2-1-1 on the upper right of the central axis surface is in communication with the five large connector drive unit oil outlet ports 2-1-4 on the right side of the central axis surface. The five large connector drive unit oil outlet ports 2-1-4 on the left side of the central axis surface are connected with the joint I drive unit group 2-6 on the left side of the central axis surface, and the five large connector drive unit oil outlet ports 2-1-4 on the right side of the central axis surface are connected with the joint I drive unit group 2-3 on the right side of the central axis surface. The oil outlet interface 2-1-1 on the lower left of the central axis surface is in communication with the upper large connector oil outlet port 2-1-3, and the oil outlet interface 2-1-1 on the lower right of the central axis surface is in communication with the lower large connector oil outlet port 2-1-3. The two large connector oil outlet ports 2-1-3 are connected with the two oil supply pipes 2-5, the joint I flexible sensor 2-4 is located in the neutral layer, and the front end is embedded in the large connector sensor slot 2-1-2.

[0043] The five middle connector drive unit joints 2-7-1 on the left side of the central axis surface are connected with the joint I drive unit group 2-6 on the left side of the central axis surface, and the five middle connector drive unit joints 2-7-1 on the right side of the central axis surface are connected with the joint I drive unit group 2-3 on the right side of the central axis surface. The two oil supply pipes 2-5 are connected with the two middle connector oil outlet ports 2-7-3, wherein the upper middle connector oil outlet port 2-7-3 is in communication with the middle connector drive unit oil outlet port 2-7-4 on the left side of the central axis surface, and the lower middle connector oil outlet port 2-7-3 is in communication with the middle connector drive unit oil outlet port 2-7-4 on the right side of the central axis surface. The three middle connector drive unit oil outlet ports 2-7-4 on the left side of the central axis surface are connected with the joint II drive unit group 2-11 on the left side of the central axis surface, and the three middle connector drive unit oil outlet ports 2-7-4 on the right side of the central axis surface are connected with the joint II drive unit group 2-9 on the right side of the central axis surface. The rear end of the joint I flexible sensor 2-4 is embedded in the middle connector sensor slot 2-7-2, and the front end of the joint II flexible sensor 2-10 is embedded in the middle connector sensor slot 2-7-2. The left joint I drive unit group 2-6, the right joint I drive unit group 2-3, the oil supply pipe 2-5 and the joint I flexible sensor 2-4 are all wrapped and fixed by the joint I flexible matrix 2-2.

[0044] The small connector driver joint 2-12-1 on the left side of the three median planes is connected to the joint II driver unit group 2-11 on the left side of the median plane, the small connector driver joint 2-12-1 on the right side of the three median planes is connected to the joint II driver unit group 2-9 on the right side of the median plane, the rear end of the joint II flexible driver 2-10 is embedded into the small connector slot 2-12-2, and the rear side of the small connector is connected to the tail fin 2-13. The left side joint II driver unit group 2-11, the right side joint II driver unit group 2-9 and the joint II flexible sensor 2-10 are all wrapped and fixed by the joint II flexible matrix 2-8.

[0045] The working principle of the fish tail 2 is shown in Figure 7 The joint I driver unit group 2-6 on the left side of the median plane, the joint I driver unit group 2-3 on the right side of the median plane, the joint II driver unit group 2-11 on the left side of the median plane and the joint II driver unit group 2-9 on the right side of the median plane all adopt the McKibben type driver unit. Such driver unit is cylindrical and will shrink axially and expand radially under the action of pressure. When the driving medium is pumped into the joint I driver unit group 2-6 on the left side of the median plane by the four-cylinder plunger pump 1-15-2, the joint I driver unit group 2-6 on the left side of the median plane shrinks, and at the same time, the driving medium in the joint I driver unit group 2-3 on the right side of the median plane is sucked out by the four-cylinder plunger pump 1-15-2 to restore its original state, so the flexible joint I (2-A) deflects to the left side of the median plane.

[0046] Similarly, when the driving medium is pumped into the joint II driver unit group 2-11 on the left side of the median plane by the four-cylinder plunger pump 1-15-2 through the oil pipe 2-5, the joint II driver unit group 2-11 on the left side of the median plane shrinks, and at the same time, the driving medium in the joint II driver unit group 2-9 on the right side of the median plane is sucked out by the four-cylinder plunger pump 1-15-2 through the oil pipe 2-5 to restore its original state, so the flexible joint II (2-B) deflects to the left side of the median plane.

[0047] When the driving medium moves in the opposite direction, the fish tail 2 changes its state, and at this time, each joint deflects in the opposite direction. It should be noted that the movements of the flexible joint I (2-A) and the flexible joint II (2-B) are independent. In the process of bionic fish swimming, the driving medium is continuously pumped in and sucked out from the symmetrical driver groups, so as to drive the fish tail 2 to swing continuously. By adjusting the rotation angle, the reversing frequency and the rotation phase difference of the plunger pump steering gear group 1-15-2-1, the swing amplitude, the swing frequency of the flexible joint I (2-A) and the flexible joint II (2-B) and the phase difference between the flexible joint I (2-A) and the flexible joint II (2-B) can be adjusted.

[0048] The application adopts four-cylinder plunger pump to provide pressure, saves pressure regulating valve and electromagnetic reversing valve, the fish tail is rigid-flexible coupling structure, the driving unit is fixed at both ends of the connecting body, the fish tail is internally provided with oil delivery pipe and flexible sensor, the pectoral fin can rotate, the hydraulic circuit is internal circulation, which can not only reduce cost, but also realize more flexible underwater swing.

[0049] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A hydraulically driven, dual-joint flexible robotic fish, characterized in that: The device includes a fish head (1) and a fish tail (2); the fish tail (2) includes a flexible joint; the flexible joint includes a flexible matrix and a drive unit located inside the flexible matrix; the drive units are respectively arranged on the left and right sides of the central axis of the flexible joint and are arranged along the axial direction of the fish body; the fish head (1) is provided with a drive assembly (1-15); when the drive medium is pumped into the drive unit, the drive unit contracts axially, and when the drive medium is sucked out from the drive unit, the drive unit expands radially; the drive medium is pumped into the drive unit on one side of the central axis of the flexible joint through the drive assembly (1-15), and the drive medium is sucked out from the drive unit on the other side of the central axis of the flexible joint, so that the entire flexible joint deflects towards the side into which the drive medium is pumped; the fish tail (2) is driven to swing by the drive medium being pumped in from one side and sucked out from the other side alternately; The fish tail (2) includes a large connector (2-1), a medium connector (2-7), a small connector (2-12), and a caudal fin (2-13). The large connector (2-1) is connected to the fish head (1). The large connector (2-1) and the medium connector (2-7) are connected by a flexible joint I (2-A). The medium connector (2-7) and the small connector (2-12) are connected by a flexible joint II (2-B). The large connector (2-1) has four sets of hydraulic cylinder oil inlet ports (2-1-1) on the front side and four sets of large connector oil inlet ports (2-1-4) and two sets of large connector oil inlet ports (2-1-3) on the rear side. All the large connector left drive unit oil inlets are connected to one set of hydraulic cylinder oil inlet ports (2-1-1) through the pipeline inside the large connector (2-1). All the large connector right drive unit oil inlets (2-1-4) are connected to another set of hydraulic cylinder oil inlet ports (2-1-1) through the pipeline inside the large connector (2-1). The other two sets of hydraulic cylinder oil inlet ports (2-1-1) are connected to the two sets of large connector oil inlet ports (2-1-3) through the pipeline inside the large connector (2-1). The middle connector (2-7) is provided with a middle connector drive unit connector (2-7-1) and two sets of middle connector oil inlets (2-7-3) on the front side. The middle connector (2-7) is provided with a middle connector left drive unit oil inlet and a middle connector right drive unit oil inlet (2-7-4) on the rear side. One set of middle connector oil inlets (2-7-3) is connected to the middle connector left drive unit oil inlet through the pipeline inside the middle connector (2-7), and the other set of connector oil inlets (2-7-3) is connected to the middle connector right drive unit oil inlet (2-7-4) through the pipeline inside the middle connector (2-7). The small connector (2-12) is provided with a small connector drive unit connector (2-12-1) on the front side, and the small connector (2-12) is connected to the tail fin (2-13) on the rear side.

2. The hydraulically driven dual-joint flexible robotic fish according to claim 1, characterized in that: The flexible matrix (2-2) of the flexible joint I (2-A) is provided with a drive unit group (2-6) for the left side of the central axis joint I, a drive unit group (2-3) for the right side of the central axis joint I, and two sets of oil pipes (2-5); the flexible matrix (2-8) of the flexible joint II (2-B) is provided with a drive unit group (2-11) for the left side of the central axis joint II and a drive unit group (2-9) for the right side of the central axis joint II. In the left-side joint I drive unit group (2-6) of the central axis surface, the front end of the drive unit is connected to the oil inlet of the left-side drive unit of the large connector, and the rear end is connected to the drive unit connector (2-7-1) of the middle connector; in the right-side joint I drive unit group (2-3) of the central axis surface, the front end of the drive unit is connected to the oil inlet (2-1-4) of the right-side drive unit of the large connector, and the rear end is connected to the drive unit connector (2-7-1) of the middle connector; the front end of the oil pipe (2-5) is connected to the oil inlet (2-1-3) of the large connector, and the rear end is connected to the oil inlet (2-7-3) of the middle connector; In the left joint II drive unit group (2-11) of the central axis surface, the front end of the drive unit is connected to the oil inlet of the left drive unit of the central connector, and the rear end is connected to the drive unit connector (2-12-1) of the small connector; in the right joint II drive unit group (2-9) of the central axis surface, the front end of the drive unit is connected to the oil inlet (2-7-4) of the right drive unit of the central connector, and the rear end is connected to the drive unit connector (2-12-1) of the small connector.

3. The hydraulically driven, dual-joint flexible robotic fish according to claim 2, characterized in that: Flexible sensors are provided on the central axis of the flexible matrix (2-2) of flexible joint I (2-A) and the flexible matrix (2-8) of flexible joint II (2-B) to detect the swing angle of flexible joint I (2-A) and flexible joint II (2-B).

4. The hydraulically driven dual-joint flexible robotic fish according to claim 2, characterized in that: The number of oil inlets in the left drive unit of the large connector matches the number of drive units in the drive unit group (2-6) of the left joint I of the central axis surface; the number of oil inlets (2-1-4) in the right drive unit of the large connector matches the number of drive units in the drive unit group (2-3) of the right joint I of the central axis surface; the number of connectors (2-7-1) in the drive unit of the middle connector matches the number of drive units in the flexible joint I (2-A); the number of oil inlets in the left drive unit of the middle connector matches the number of drive units in the drive unit group (2-11) of the left joint II of the central axis surface; the number of oil inlets (2-7-4) in the right drive unit of the middle connector matches the number of drive units in the drive unit group (2-9) of the right joint II of the central axis surface; and the number of connectors (2-12-1) in the drive unit of the small connector matches the number of drive units in the flexible joint II (2-B).

5. The hydraulically driven dual-joint flexible robotic fish according to claim 1, characterized in that: The drive assembly (1-15) includes a four-cylinder plunger pump (1-15-2), which has four sets of oil inlets (1-15-2-8-1). The four sets of hydraulic cylinder oil inlet interfaces (2-1-1) on the front side of the large connecting body (2-1) are connected to the four sets of oil inlets (1-15-2-8-1) of the four-cylinder plunger pump (1-15-2).

6. The hydraulically driven dual-joint flexible robotic fish according to claim 5, characterized in that: The four-cylinder plunger pump (1-15-2) includes a hydraulic cylinder body (1-15-2-8); the hydraulic cylinder body (1-15-2-8) is a four-cylinder structure, including two pairs of cylinders, each of which is equipped with a piston (1-15-2-7); the hydraulic cylinder body (1-15-2-8) has servo mounting plates (1-15-2-2) on its upper and lower sides, and each servo mounting plate (1-15-2-2) is fixed with a pair of plunger pump servos (1-15-2-1). The output shaft of each plunger pump servo (1-15-2-1) is connected to the piston (1-15-2-7) in one of the cylinders of the hydraulic cylinder body (1-15-2-8) through a crank-slider mechanism. The rotational motion of the output shaft of the plunger pump servo (1-15-2-1) is converted into the reciprocating motion of the piston (1-15-2-7) inside the cylinder body through the crank-slider mechanism.

7. The hydraulically driven dual-joint flexible robotic fish according to claim 1, characterized in that: The top surface of the fish head (1) is provided with a dorsal fin, and the left and right sides of the fish head (1) are provided with pectoral fins (1-15-1-1); the drive assembly (1-15) includes a pectoral fin assembly (1-15-1); the pectoral fin assembly (1-15-1) includes a pectoral fin support (1-15-1-4), and the pectoral fin support (1-15-1-4) is connected to a pectoral fin servo assembly (1-15-1-3) on both sides. The output shaft of the pectoral fin servo assembly (1-15-1-3) is connected to the pectoral fin assembly (1-15-1-1) through a connecting shaft assembly (1-15-1-2). During the operation of the robotic fish, the angle of the pectoral fins (1-15-1-1) on the left and right sides of the fish head (1) is adjusted to make the robotic fish float up and dive down.

8. A hydraulically driven, dual-joint flexible robotic fish according to claim 1, characterized in that: An antenna (1-3) is installed on the top surface of the fish head (1). A fish head support frame (1-11) is provided inside the fish head (1). A mesh partition is provided on the fish head support frame (1-11). A large PCB board (1-9) and a small PCB board (1-7) are installed above the partition. A battery pack (1-12) is installed below the partition. A voltage regulator module (1-8) and a current sensor module (1-10) are provided on the large PCB board (1-9). A control microcontroller (1-5) and a signal transmitter (1-6) are provided on the small PCB board (1-7).

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