WO2022100557A1

WO2022100557A1 - Underwater turtle-like robot and control method thereof

Info

Publication number: WO2022100557A1
Application number: PCT/CN2021/129418
Authority: WO
Inventors: 张建; 狄陈阳; 李永胜; 李泓运; 连雪海; 赵坦; 唐文献; 李凯
Original assignee: 江苏科技大学
Priority date: 2020-11-16
Filing date: 2021-11-09
Publication date: 2022-05-19
Also published as: CN114506428B; CN114506428A

Abstract

An underwater turtle-like robot and a control method thereof. The underwater turtle-like robot comprises a bionic turtle upper shell (65), a bionic turtle lower shell (23), a turtle limb, a sealing structure, a drive device provided inside a turtle shell and used for driving the turtle limb to move, a secure withdrawal cabin, a protective device, and a sensor. The bionic turtle upper shell (65) consists of an ellipsoidal shell part and a spherical shell part, and carries out an equal-strength thickening design. The underwater turtle-like robot reduces the use of the shell materials, and maintains good compression resistance and anti-impact capabilities.

Description

An underwater turtle imitating robot and its control method

technical field

The invention relates to the field of bionic robot design and control, in particular to an underwater detection bionic turtle robot and a control method thereof.

Background technique

An underwater robot is a mechatronic intelligent device that can move underwater, has a perception system, and uses manipulators or other tools to replace or assist people to complete underwater tasks through remote control or autonomous operation. Underwater robot is one of the indispensable tools for human beings to understand the ocean and develop the ocean. It is also a necessary high-tech means to build a strong ocean country and achieve sustainable development.

Compared with traditional underwater robots, underwater bionic robots have the advantages of low resistance, high efficiency, high maneuverability and high environmental adaptability. It can complete various tasks in a small and complex environment, and can be used in military, detection and other fields.

The existing underwater bionic turtle robots have the following shortcomings:

1. The thickness of the shell of the turtle body is the same thickness, which leads to excess safety margin, waste of unnecessary raw materials, and high cost.

2. There is no effective protective device outside the shell of the bionic turtle robot, which cannot effectively protect the turtle body and related important components. If the turtle body collides with an external object, geometric defects will occur, reducing the pressure resistance of the turtle body;

3. Lack of safe and reliable recovery device, unable to deal with some emergencies such as controller or drive module failure, resulting in robot loss, waste, etc.;

4. The shape and structure are simple, and the streamline shape of the actual turtle shell is greatly different, the water resistance is large, and the power consumption is high;

5. The O-ring seal cannot effectively solve the problem of dynamic sealing in practical application. The mechanical seal has the defects of complex structure and difficult assembly, which is not suitable for the robot structure that needs to be disassembled frequently;

6. Commonly used underwater turtle-like robots are driven by mechanical drive and dielectric elastomer drive. Under mechanical drive, if the limbs can move with two degrees of freedom, the structure will be complicated, and there will be inevitable problems of easy wear and large volume. The dielectric elastomer drive requires a high drive voltage, and generally only one degree of freedom motion can be achieved, so it is difficult to simulate the actual motion of the turtle.

In view of the above problems, the present invention designs the upper shell of the underwater turtle imitation robot with equal strength and thickening, which solves the problem of unnecessary waste of materials; the design of detachable protective fence solves the problem of shell pressure resistance after the turtle body accidentally hits The problem of insufficient performance; by setting up a safe retraction cabin, the problem that the robot cannot be retracted in emergencies is solved; the shell shape that satisfies the elliptical sphere and the spherical equation, and the shape of the forelimb and limb section of the turtle that satisfies the involute equation are designed to solve the problem. It solves the problems of large resistance and high energy consumption when the bionic tortoise moves; dynamic sealing through elastic membrane solves the difficult and complex problems of previous underwater robots; the use of forelimbs and steering gear combined with polypyrrole (PPy) drive provides A new drive mode. ,

CSIC (Qingdao) Marine Equipment Research Institute Co., Ltd. has applied for an invention patent titled "An omnidirectional anti-collision device for a shipborne marine underwater detection device". The patent application number is: CN202010441804.0. It includes an upper protective cover and a lower protective cover, the ends of which are close to each other are provided with fixed waist rings, the upper protective cover is also provided with iron chains, and a second sleeve is arranged at the center of the top surface of the blocking cover, which is insufficient. The disadvantage is that the structure is complex and heavy. If it is installed on an underwater robot, it will generate large water resistance, the protection range cannot be adjusted, and the flexibility is poor. Our invention fully takes into account the following points: 1. Underwater environmental conditions, the guardrail can be installed and removed and the protection range of the guardrail can be adjusted; 2. Flexibility, the whole is divided into two quarter circles, each circle The rings can be adjusted independently; 3. The size of the water resistance, the section of the guardrail is designed to be oval and streamline-like.

SUMMARY OF THE INVENTION

In view of the above technical problems, the present invention proposes an underwater bionic turtle robot and a control method thereof, which have the effects of buffering impact, reducing energy consumption for underwater motion, and facilitating recovery.

In order to realize above-mentioned technical purpose, the present invention adopts following technical scheme:

An underwater bionic turtle robot, comprising a bionic turtle upper shell, a bionic turtle lower shell, turtle limbs, a sealing structure, and a driving device arranged inside the turtle shell for driving the action of the turtle limbs;

The upper shell of the bionic turtle and the lower shell of the bionic turtle are separated by silicone rubber for static sealing and connected with screws;

The four limbs of the turtle are divided into forelimbs and hindlimbs, and the transmission shaft of the hindlimb protrudes from the shaft section of the tortoise shell and between the lower shell of the bionic tortoise, and between the shaft section of the forelimb bevel gear shaft protruding from the tortoise shell and the lower shell of the bionic tortoise. There are silicone rubber elastic membranes for waterproofing;

A pressure sensor is installed on the top of the underwater turtle-like robot, and its real-time depth is judged by the magnitude of the pressure; a temperature and humidity sensor is installed inside the underwater turtle-like robot to detect the internal sealing of the turtle body. If water enters, it will immediately alarm; A gyroscope is set on the turtle shell to adjust the posture of the turtle body; a camera is installed on the head of the underwater turtle imitation robot for observation, and the upper shell of the bionic turtle is composed of an ellipsoidal shell part and a spherical shell part,

The shell thickness of the ellipsoid shell portion is obtained by the following formula:

In the formula, p is the external pressure on the shell, σ _s is the yield stress of the material, a is the radius of the major axis of the ellipsoid, ρ is the ellipticity, t is the thickness of the shell, and x and y are the Cartesian coordinate system;

The shell thickness of the spherical shell portion is obtained by the following formula:

where R is the radius of the spherical shell.

It also includes a guardrail mechanism, which is detachably connected to the turtle shell. The guardrail mechanism includes two groups, which are symmetrically arranged on the left and right sides of the turtle shell. Each group of guardrail mechanisms includes:

The guardrail has a quarter ring structure, one end of the inner side of the guardrail is connected to the turtle shell through a buffer mechanism, and the other end of the inner side of the guardrail is connected to the turtle shell through an adjustment mechanism;

The buffer mechanism includes a cylindrical shock absorbing cavity, a connecting rod and a spring, wherein the spring is arranged in the cylindrical shock absorbing cavity, and one end of the cylindrical shock absorbing cavity is provided with a rod hole;

The inner side of the guardrail is provided with a chute, one end of the connecting rod is provided with a first chute contact matched with the chute, and the other end of the connecting rod extends into the cylindrical shock absorbing cavity through the rod hole;

The middle part of the connecting rod is provided with a shaft shoulder, and the shaft shoulder divides the part of the connecting rod located in the cavity of the shock absorber into a first connecting rod segment and a second connecting rod segment, the first connecting rod segment and the The second connecting rod segments are respectively sleeved with one of the springs;

The outer side of the bottom of the cylindrical shock-absorbing cavity is rotatably connected with the turtle shell through a hinge;

The adjustment mechanism includes an adjustment box, the adjustment box is arranged on the tortoise shell, a first threaded rod and a first transmission shaft are arranged in parallel in the first adjustment box, and the first threaded rod and the first transmission shaft pass through. Transmission connection of gear transmission group;

The outer end of the first transmission shaft extends out of the adjustment box and is connected with an adjustment handle. Under the adjustment of the adjustment handle, the first threaded rod can move back and forth in the horizontal direction to adjust the protection range of the guardrail;

The outer end of the first threaded rod is slidably connected to the guardrail through the second sliding groove contact, and a restriction block is provided on the inner end of the first threaded rod.

The cross-section of the guardrail is oval and streamline-like.

The forelimb is driven by a steering gear combined with a software drive to achieve dual-degree-of-freedom motion: one is the steering gear drive: the forelimb is driven by the forelimb steering gear to drive the forelimb to rotate through the forelimb bevel gear set; the second is the polypyrrole strip drive: the two sides of the forelimb Symmetrically covered with a plurality of polypyrrole strips, which are connected to the lower electrode plate of the clip, followed by wires and connected to the software drive control module through the center hole of the bevel gear shaft of the front limb, and the polypyrrole strips are controlled by the software control module. Drive the forelimbs to swing up and down;

The driving device of the rear limb includes a rear limb steering gear, a steering gear disc, a bearing seat, a connecting shaft, a small elastic belt and a rear limb transmission shaft, wherein the rear limb steering gear, the steering gear disc and the steering gear sleeve are connected by screws. , the connecting shaft and the steering gear sleeve are connected by screws; the small elastic belt transmits the power to the rear limb transmission shaft, and drives the rear limb to make a rotating motion.

Balance wings are provided on both sides of the lower shell of the bionic turtle to assist in maintaining balance.

Also includes a safety retraction pod, connected to the turtle shell by a tow line, including:

A cabin, the cabin is provided with a partition, the partition divides the cabin into an upper cabin and a lower cabin, the upper cabin is provided with a hatch cover that can be opened or closed, and the upper cabin is provided with a compression Airbag, the bottom of the compressed airbag is connected with the hook ear fixed in the inner cavity of the upper cabin through the lead wire;

The lower cabin is a sealed cabin, and the lower cabin is provided with a hatch cover opening mechanism. The hatch cover opening mechanism includes: a second transmission shaft and a second threaded rod arranged in parallel, and the second transmission shaft and the second threaded rod pass through gear drive connection

The servo motor is drivingly connected with the second transmission shaft, and the part of the second threaded rod in the hatch opening mechanism penetrates the baffle and protrudes into the upper cabin. Driven by the servo motor, the second threaded rod can move in the up and down direction inside the cabin to open the hatch cover of the cabin;

The lower cabin is also provided with a transverse plate and a pressure bottom plate, the transverse plate and the pressure bottom plate are connected by bolts, and the pressure plate and the transverse plate are both provided with card slots for fixing the second transmission shaft and the gear transmission. Group;

The cabin is also provided with a signal receiving device for receiving external signals;

a controller, the input end of which is connected to the signal receiving device, and the output end of which is connected to the servo motor;

a power supply, which supplies power to the servo motor, the signal receiving device and the controller;

There are three seals in the cabin, the first is between the upper cabin and the lower cabin, which is a static seal and is sealed with a silicone gasket;

The second place is between the bulkhead and the upper cabin pillar in the upper cabin, which is a static seal and is sealed with a silicone gasket;

The third place is between the second threaded rod and the upper cabin strut in the upper cabin. It is a dynamic seal. It is sealed by a transparent elastic film. on the upper hull strut.

From the perspective of bionics, the tortoise's limbs are formed by two involutes that intersect at the tips of the limbs. When represented by Cartesian coordinates, their equations are:

In the formula, u _i =θ _i +α _i , θ _i is the expansion angle, α _i is the pressure angle, ri _i is the radius of the base circle,

C ₁ is the value range of the angle u1, the range is 240°～270°, C ₂ is the value range of the angle u2, the range is 210°～265°;

Its section is also composed of two involutes, taking the central section as an example, as follows:

In the formula, u′ _i = θ′ _i +α′ _i , θ′ _i is the expansion angle, α′ _i is the pressure angle, r′ _i is the radius of the base circle, C′ ₁ is the value range of the angle u′ ₁ , The range is 210°～226°, C' ₂ is the value range of the angle u' ₂ , and the range is 210°～221°;

Its thickness increases first and then gradually decreases from the front end to the rear end;

The hindlimbs are thin around the edges, with a gradual increase in cross-sectional thickness from the edge to the center.

The shell of the turtle-like robot is streamlined.

A working method based on the underwater bionic turtle robot, comprising the following steps:

Step 1: Check, deploy and dive

First, check the underwater turtle-like robot. The main contents are whether the limbs move normally, whether the seal is intact, whether the sensor is working normally, and whether the power is sufficient. Select the appropriate water area and put the underwater turtle-like robot into the water;

The dive is completed by the cooperation of the forelimb and the hindlimb. The details are as follows: after the hindlimb servo is instructed, the left servo of the hindlimb rotates 90° clockwise, while the right servo of the hindlimb rotates 90° counterclockwise, so that both hindlimbs are equally Keep vertical and upward, and swing back and forth for a total of 60° at this center position, drive the connecting shaft through the steering gear sleeve, and drive the rear limb drive shaft to rotate by the small elastic belt. At the same time, after the forelimb steering gear is commanded, the left forelimb servo rotates 30° clockwise, and the right forelimb servo rotates 30° counterclockwise, and the motion is transmitted to the forelimb bevel gear set. The forelimbs are lifted, so that the front ends of the forelimbs on both sides rise. At this time, the steering gear of the forelimbs stops rotating, and then the software control module applies a reverse voltage to the polypyrrole strips, so that the hind limbs flap backwards and upwards, so that the reaction force of the water pushes the turtle body move forward and downward;

Then disconnect the power supply and the polypyrrole strip, and then the forelimb rudder will get a reverse rotation motion command, and rotate counterclockwise twice the first rotation angle, that is, 60°, so that the rear end of the forelimb will rise, and the forelimb rudder will stop. , the software control module applies a reverse voltage to the polypyrrole strip to make it flap forward and upward, so that the reaction force of the water pushes the turtle body to move backward and downward, and then it is repeatedly turned on in this order to complete the diving movement;

Step 2: Go Forward

The propulsion is accomplished by the mutual cooperation of the forelimb and the hindlimb. The details are as follows: after the servo of the hindlimb is commanded, it rotates back and forth for a total of 60°, the connecting shaft is driven by the steering gear sleeve, and the drive shaft of the hindlimb is driven by the small elastic belt to rotate, and the hindlimb is erected. Swing back and forth for a total of 60°, obtain forward thrust, and keep the movement during the whole process. At this time, the forelimbs are all driven by the polypyrrole strips, and the polypyrrole strips are applied with a positive voltage and bend downward, that is, flap down, with appropriate intervals Time, and then apply a negative voltage to make the polypyrrole strips bend upwards, that is, flap upwards. This cycle completes the propulsion movement. During this process, the swing frequency of the forelimb and the hindlimb should be kept the same, so as to maintain balance;

Step 3: Turn

There are two solutions, both are differential steering and after the movement is completed, the steering gear needs to return to its original position,

Option 1: Realized by the hind limbs, the forelimbs swing up and down a total of 60° to maintain balance, one of the two hind limb servos remains stationary, the other hind limb servo drives the connecting shaft through the steering gear sleeve, and then the small elastic belt drives the hind limbs The drive shaft rotates to realize the vertical reciprocating swing of the hind limbs for a total of 60°, obtain forward thrust, and keep the movement during the whole process;

Option 2: Realized by the forelimb, the hind limb swings up and down to maintain a balance and provide a certain thrust, one of the two forelimbs remains motionless, and the other moves as follows: after the forelimb servo is commanded, the left forelimb servo rotates 90° clockwise, The steering gear on the right side of the forelimb is rotated 90° counterclockwise, so that the forelimbs on both sides are vertical. At this time, the steering gear of the forelimb stops rotating immediately, and then applies a reverse voltage to the polypyrrole strip and flaps it to the rear side, so that the reaction force of the water is caused by the water. Push the turtle body to turn;

Step 4: Float

The uplift is mainly accomplished by the hind limbs. The forelimbs swing up and down a total of 60° to maintain balance. The movement of the hind limbs is as follows: After the hind limb servo is commanded, the left servo of the hind limb rotates 90° counterclockwise, while the right servo of the hind limb rotates clockwise. Rotate 90 degrees, keep both hind limbs vertically downward, and rotate back and forth for a total of 60° with this as the center position, drive the connecting shaft through the steering gear sleeve, and drive the hind limb drive shaft to rotate by the small elastic belt, and complete the horizontal reciprocation of the hind limbs downward. Swing a total of 60°, get upward thrust, and maintain motion throughout the process;

Step 5: Take Back

It is realized by the movement of the hind limb, the steering gear of the hind limb drives the connecting shaft through the steering gear sleeve, and then the drive shaft of the hind limb is driven to rotate by the small elastic belt, so as to realize the vertical reciprocating swing of the hind limb for a total of 60°, obtain the forward thrust, row to the shore, and complete the recovery. Also, throughout the process, .

In the event of an emergency failure, the safe retraction is carried out by controlling the safe retraction cabin, specifically:

The operator sends an ascending command to the safe retraction cabin, so that the servo motor in the cabin rotates, the hatch cover is opened through the hatch cover opening mechanism, the compressed air bag is released, and the imitation turtle robot is driven to float up.

Beneficial effects:

1. The present invention adopts the equal-strength thickening design of the upper shell of the underwater turtle imitation robot to prevent serious excess of safety margins, reduce the use of shell materials, reduce costs, and maintain good compression and impact resistance at the same time. ability.

2. There is a detachable protective fence. When the imitation turtle robot equipped with the protective fence hits an object, the impact is greatly buffered under the action of the buffer device, which effectively protects the turtle body and important parts of the underwater bionic turtle; At the same time, according to the underwater environment, you can choose to install and remove the guardrail or adjust the protection range of the guardrail, which has high flexibility.

3. By setting up a safe recovery cabin to solve the situation that the robot cannot be recovered in an emergency, it has the advantages of cost saving, easy analysis of the cause of the accident and protection of the underwater environment.

4. The upper shell of the underwater turtle-like robot largely imitates the shape of the turtle, which satisfies the elliptical spherical and spherical equations. The shell of the turtle-like robot is streamlined. The water resistance is greatly reduced, and the motion energy consumption of the underwater turtle imitation robot is reduced.

5. The dynamic seal adopts silicone rubber elastic film, which can elastically deform with the small reciprocating rotation of the shaft, which has the advantages of low cost, simple structure and reliable sealing.

6. The forelimb of the present invention is driven by a steering gear combined with polypyrrole (PPy), which simplifies the mechanical structure, reduces wear, and effectively simulates the actual movement of the turtle. The main driving force is provided by the rear limb steering gear, which can quickly realize the three functions of ascending, descending and propulsion, reducing the ascending and descending time and improving work efficiency.

Description of drawings

1 is a three-dimensional model diagram of an underwater turtle imitation robot of the present invention;

2 is a schematic diagram of the internal structure of the underwater turtle imitation robot of the present invention;

3 is a schematic diagram of the hindlimb structure of the underwater turtle imitation robot of the present invention;

4 is a schematic diagram of the forelimb structure of the underwater turtle imitation robot of the present invention;

5 is a schematic structural diagram of an underwater turtle imitation robot guardrail device of the present invention;

6 is a schematic diagram of the buffer mechanism of the underwater turtle imitation robot of the present invention;

7 is a schematic diagram of an underwater turtle imitation robot guardrail adjustment mechanism of the present invention;

8 is a schematic diagram of the connection between the contact of the chute and the chute of the underwater turtle imitation robot of the present invention;

9 is a schematic structural diagram of the safe retraction cabin of the underwater turtle imitation robot of the present invention;

10 is a schematic diagram of the upper shell of the underwater turtle imitation robot of the present invention;

11 is a schematic cross-sectional view of the forelimb of the underwater turtle imitation robot of the present invention;

Fig. 12 is the control flow chart of the underwater turtle imitation robot of the present invention;

Fig. 13 is the signal transmission processing block diagram of the main controller of the underwater turtle imitation robot of the present invention;

Fig. 14 is the control schematic diagram of the safe recovery cabin of the underwater imitation turtle robot of the present invention;

Fig. 15 is a control flow chart of the safe retraction cabin of the underwater turtle imitation robot of the present invention.

In Figure 1 to Figure 15: 1- hind limb, 2- connecting screw, 3- rear limb steering gear, 4- steering gear fixing block, 5- steering gear plate, 6- set screw, 7- bearing seat, 8- connecting shaft , 9- small elastic belt, 10- hind limb drive shaft, 11- end cover, 12- adjusting washer, 13- fixing screw, 14- clip, 15- front limb bevel gear shaft, 16- bevel gear shaft, 17- rudder Machine sleeve, 18-Forelimb steering gear, 19-Bionic turtle tail, 20-Balance wing, 21-Forelimb, 22-Polypyrrole strip, 23-Bionic turtle lower shell, 24-Bionic turtle head, 25-Guard rail, 26 -Battery and controller area, 27-limiting block, 28-turntable, 29-adjustment mechanism, 30-slot cover, 31-bolt, 32-buffer mechanism, 33-rotating block, 34-rotating sleeve, 35-chute Contact, 36-connecting rod, 37-shock body cover, 38-shock body, 39-spring, 40-fixing washer, 41-handle, 42-first drive shaft, 43-small end cap, 44- 1st gear, 45-pressing plate, 46-second gear, 47-bearing, 48-big end cap, 49-first threaded rod, 50-servo motor, 51-motor sleeve, 52-second drive shaft, 53 - Fourth gear, 54- Pressing bottom plate, 55- Partition plate, 56- Rubber gasket, 57- Upper cabin, 58- Second threaded rod, 59- Hatch cover, 60- Upper cabin strut, 61- Small spring , 62 - hook ear, 63 - lower hull, 64 - ring ear, 65 - upper shell of bionic turtle.

Detailed ways

Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in Figure 1-10, the structure of the underwater bionic turtle robot consists of a turtle shell, limbs, driving devices, safety retraction cabins, guardrail devices and sensors.

As shown in FIG. 2 and FIG. 5 , the turtle shell is composed of a bionic turtle upper shell 65 , a bionic turtle lower shell 23 , a bionic turtle head 24 and a balance wing 20 . The silicone rubber is used for static sealing and connected with screws, and the balance wings 20 are used to assist in maintaining balance, making it difficult for the turtle body to tilt.

As shown in Figure 3 and Figure 4, the limb structure is divided into forelimb structure and hind limb structure. The forelimb structure includes forelimb 21, clip 14, polypyrrole strip 22, electrode pad, and lead wire, wherein the forelimb 21 is clamped by clip 14, and more The polypyrrole strips 22 are symmetrically attached to both sides of the forelimb 21 and are connected to the lower electrode plate of the clip, followed by wires and connected to the software drive control module through the central hole of the forelimb bevel gear shaft 15; the hindlimb structure includes hindlimb 1, hindlimb drive shaft 10, wherein the hind limb 1 is connected with the hind limb transmission shaft 10 through the connecting screw 2.

As shown in Figures 3 and 4, the driving device is divided into a forelimb driving device and a hind limb driving device. The fore limb driving device includes a fore limb steering gear 18 , a steering gear disc 5 , a steering gear sleeve 17 , a bearing seat 7 , a bevel gear shaft 16 , and a fore limb bevel gear shaft 15 . The fore limb steering gear 18, the steering gear disc 5 and the steering gear sleeve 17 are connected by screws, the rear end of the bevel gear shaft 16 is connected with the steering gear sleeve 17, and the power is transmitted to the forelimb bevel gear shaft 15 through the bevel gear meshing Forelimbs 21.

The forelimb is driven by a steering gear combined with a software drive to achieve double-degree-of-freedom motion: one is the steering gear drive: the forelimb steering gear 18 provides power through the bevel gear shaft 16, and then the forelimb bevel gear shaft 15 drives the foreleg 21 to rotate; Pyrrole strip (PPy) drive: The polypyrrole strip (PPy) 22 is controlled by the software control module to drive the limbs to swing up and down. The rear limb driving device includes a rear limb steering gear 3, a steering gear disc 5, a bearing seat 7, a connecting shaft 8, a small elastic belt 9, and a rear limb transmission shaft 10. Among them, the rear limb steering gear 3, the steering gear disc 5, and the steering gear sleeve 17 are connected by screws, and the set screw connects the connecting shaft 8 and the steering gear sleeve 17, and the small elastic belt 9 transmits the power to the rear limb transmission shaft 10 to drive Hind limb 1 makes a rotational movement.

The hind limbs mainly rotate in three directions, lateral upward swing, lateral downward swing, and vertical swing. In addition, the steering gear fixing block 4 fixes the steering gear and the turtle body.

As shown in FIG. 5 , the guardrail device is composed of guardrail 25 , limiting block 27 , turntable 28 , adjusting mechanism 29 , slot cover 30 , bolt 31 , buffer mechanism 32 , rotating block 33 , and rotating sleeve 34 . Since the rotating block 33 , the rotating sleeve 34 and the turntable 28 form a rotating pair, the buffer mechanism and the lower buffer mechanism in FIG. 5 can both rotate freely.

As shown in FIG. 6 , the buffer mechanism 32 is composed of a chute contact 35 , a connecting rod 36 , a spring 39 and a fixing washer 40 , wherein the shock absorber 38 and the shock absorber cover 37 are connected by threads, and the chute contact 35 is connected to the The connecting rod 36 is connected by a wedge block, and springs 39 are installed on both sides of the shaft shoulder of the connecting rod 36 , which are fixed in the shock absorbing body 38 through the fixing gasket 40 . When the guardrail 25 is hit, the impact force is transmitted to the connecting rod 36 through the chute contact 35, so that the connecting rod 36 is compressed or pulled. Pressure; if it is under tension, the right spring is stretched, and the left spring is compressed, which buffers the pulling force. In both cases, it effectively plays the role of buffering and shock absorption.

As shown in FIG. 7 , the adjustment mechanism 29 consists of a pressure plate 45 , a handle 41 , a first transmission shaft 42 , a first gear 44 , a second gear 46 , a first threaded rod 49 , a small end cap 43 , a large end cap 48 and a bearing 47 The first transmission shaft 42 is fixed in the adjustment box by the bearing 47 and the end caps, the handle 41 and the first transmission shaft 42 are connected by a wedge block, and the second gear 46 and the first threaded rod 49 are connected by a thread. Twisting the handle 41 makes the first transmission shaft 42 rotate, which drives the gear 44 to rotate, and drives the second gear 46 to rotate through meshing. , and the restriction block 27 restricts the degree of freedom of its rotational direction, so the first threaded rod 49 can only move in the axial direction, and is connected with the chute on the guard rail through the chute contact 35 to drive the guard rail 25 to move, so that the Rotate the handle 41 to adjust the protection range of the guardrail 25 .

Protection examples and functions of the guardrail device: Example: If subjected to the impact force in the direction A as shown in Figure 5, after the buffer mechanism rotates counterclockwise, under pressure, the right spring is compressed, the left spring is extended, and the lower buffer mechanism is affected. Pulling force, the right spring is stretched, and the left spring is compressed, which effectively acts as a shock absorber; if it is subjected to the B-direction impact force, after the upper and lower side buffer mechanisms rotate counterclockwise, both are under tension, the right spring is stretched, and the left side is stretched. The side spring is compressed; if it is subjected to the C-direction impact force, after the buffer mechanism rotates clockwise, under tension, the right spring is stretched, the left spring is compressed, the lower buffer mechanism is under pressure, the right spring is compressed, and the left spring is stretched . It can be seen that, no matter which direction the guardrail is subjected to the impact force, the guardrail device can effectively play the role of buffering and shock absorption. The function of the guardrail device:

1. When the guardrail hits the object, under the action of the buffer device, the impact is greatly slowed down, and the turtle body and important parts of the underwater bionic turtle are effectively protected.

2. According to the underwater environment, you can choose to install and remove the guardrail or adjust the protection range of the guardrail. Specifically, the protection range of the guardrail 25 is controlled by adjusting the valve 41, a small protection radius is selected in the narrow water area, and a large protection radius is selected in the open water area, which has extremely high flexibility.

3. Divide the whole guardrail into two quarter rings, each ring can be adjusted independently, which is convenient to adapt to the complex environment. If it is made as a whole, its flexibility will be reduced.

4. The cross-section of the guardrail is oval and streamlined, which can reduce the water resistance of the underwater turtle-like robot when it moves and reduce the energy consumption of the movement.

As shown in FIG. 9 , the safe retraction compartment includes a servo motor 50, a motor sleeve 51, a second transmission shaft 52, a fourth gear 53, a pressing bottom plate 54, a partition plate 55, a rubber gasket 56, an upper cabin body 57, a second Threaded rod 58, hatch cover 59, small spring 61, hook lug 62, lower cabin 63, ring lug 64; The motion is transmitted to the fourth gear 53, and then the thread of the inner diameter of the fourth gear 53 is screwed with the thread of the second threaded rod 58, and the rotary motion is converted into the linear motion of the second threaded rod 58, and then the second threaded rod 58 Open the hatch cover 59, release the compressed air bag in the upper cabin body 57, the compressed air bag is connected with the hook ear 62 through the lead wire, and the buoyancy of the compressed air bag drives the safe retraction cabin to float up, because the safe retraction cabin is connected with the bionic turtle shell through the traction wire. , so the imitation turtle robot also floated up. The partition plate 55 is used to separate the upper cabin 57 and the lower cabin 63, and cooperate with other components to complete the sealing to prevent water from entering the lower cabin 63; Both the bottom plate 54 and the horizontal plate are provided with card slots for fixing the second transmission shaft 52 , the third gear and the fourth gear 53 .

There are three seals in the cabin, one is between the upper and lower cabins, which is a static seal, which is sealed with a silicone gasket; the other is between the partition 55 and the upper cabin pillar in the upper cabin 57, which is a static seal and is sealed with silicone Gasket sealing; the third is the dynamic seal between the second threaded rod 58 and the upper cabin body pillar in the upper cabin body 57, which is sealed by a transparent elastic film, and one end of the second threaded rod 58 exposed to the upper cabin body pillar part is completely wrapped , and the other end is glued to the upper cabin strut.

The function of the safety retraction cabin: the lower cabin 63 has an independent signal receiving device, power supply, and controller. The operator can issue a floating command to the safety retraction cabin to make the servo motor in the cabin rotate. A turtle-like robot floats up. It has the characteristics of small size, and has little effect on the water resistance of the turtle body. When the main controller or drive module fails, this device can make the imitation turtle robot float on the water surface, recover and maintain it safely, and avoid abandoning it at the bottom of the water. Save costs, and at the same time facilitate the analysis of the cause of the accident and further improvement.

The shell of the underwater turtle imitation robot largely imitates the shape of the turtle. In the three-dimensional Cartesian coordinate system, the upper shell satisfies the elliptical spherical and spherical equations (as shown in Figure 1). The equation is:

Assuming that the upper shell height of the underwater turtle imitation robot is h, and the front-end spherical radius is r, the analysis shows that the parameter

It is related to the water resistance of the underwater turtle-like robot when it moves in water.

When , the structure is better and the water resistance is small, here we take

At this time, the underwater turtle-like robot has a flat structure and a streamline shape, which greatly reduces the water resistance and reduces the motion energy consumption of the underwater turtle-like robot. and intersect at the limb tips, their parametric equations are:

Its section is also composed of two involutes (as shown in Figure 8). Taking the central section as an example, the details are as follows:

It is similar to the streamlined section of an aircraft wing. Its thickness increases first and then gradually decreases from the front end to the rear end. The shape of the hind limb is composed of an arc and two tangents. The surrounding edges are thinner. From the edge to the center, the thickness of the cross section gradually increases Increase, the above features take full advantage of the water's reaction force, so that the limbs get the maximum thrust. According to the above arguments, the specific geometric parameters are selected as follows:

Table 1 Turtle upper shell model parameters and data

模型参数Model parameters	r ₁(mm) r ₁ (mm)	C ₁(°) C ₁ (°)	r ₂(mm) r ₂ (mm)	C ₂(°) C ₂ (°)
前肢外形数据Forelimb shape data	100100	240°—270°240°—270°	5050	210°—265°210°—265°

Table 2 Forelimb shape model parameters and data

模型参数Model parameters	r′ ₁(mm) r′ ₁ (mm)	C′ ₁(°) C′ ₁ (°)	r′ ₂(mm) r′ ₂ (mm)	C′ ₂(°) C′ ₂ (°)
四肢截面数据Cross-sectional data of limbs	150150	210°—226°210°—226°	200200	210°—221°210°—221°

Table 3 Model parameters and data of limb section

Equal-strength thickening design: Through the equal-strength thickening design of the upper shell of the underwater turtle imitation robot, the safety margin is prevented from being seriously excessive, the use of shell materials is reduced, and the cost is reduced, while maintaining good compressive and Shock resistance.

The upper case is made of

Rotated around the x-axis, it consists of an ellipsoid shell part and a spherical shell part. ①. The equal strength of the ellipsoid shell becomes thicker: In the Cartesian coordinate system, the expressions of the first and second principal curvature radii of the ellipsoid shell are respectively:

where a is the radius of the major axis of the ellipsoid; b is the radius of the minor axis of the ellipsoid.

The equivalent stress of each point is required to be less than the yield stress of the material. According to the relevant references, the equivalent stress formula of the equal-strength ellipsoid shell can be expressed as:

In the formula, p is the external pressure on the shell, σ _s is the yield stress of the material, and t is the thickness of the shell.

The thickness of the equal-strength ellipsoid shell is:

Substitute (5) into (7) to get:

where ρ is the ellipticity,

The specific parameters are selected as follows: select stainless steel material, and its performance parameters: yield stress σ _s = 385Mpa, at 200m water depth:

Table 4 The relevant data of the ellipsoid shell part

②, the strength of the spherical shell part becomes thicker

The first and second curvature radii of the spherical shell are:

R ₁ =R ₂ =R (9)

where R is the radius of the spherical shell.

From (6), we get

Equivalent stress formula of equal-strength spherical shell

Then the thickness of the equal-strength spherical shell is

The specific parameters are selected as follows: select stainless steel material, and its performance parameters: yield stress σ _s = 385Mpa, at a water depth of 200 meters:

模型参数Model parameters	R(mm)R(mm)	D ₂(mm) D ₂ (mm)	P(Mpa)P(Mpa)	σ _s(Mpa) σ _s (Mpa)	t(mm)t(mm)
相关数据related data	110110	78≤x≤160且y≥078≤x≤160 and y≥0	1.961.96	385385	0.280.28

Table 5 Related data of spherical shell part

The realization of the upper and lower swing of the forelimb: after the voltage is applied, the positive polypyrrole layer oxidatively expands, and the negative polypyrrole layer reductively shrinks, resulting in the effect of bending deformation, so the polypyrrole strip (PPy) has the characteristic of bending in the direction of the negative electrode. After the software controller applies a forward voltage to the polypyrrole strip through the electrode sheet, the polypyrrole strip (PPy) will bend in the negative direction to achieve the purpose of bending downward, thereby driving the forelimb 1 to bend downward; after changing the voltage direction, the polypyrrole strip (PPy) will bend downward. The pyrrole strip (PPy) changes the bending direction to achieve the purpose of upward bending, thereby driving the forelimb 1 to bend upward.

Limb movement: in the initial state, the forelimbs and hind limbs are kept horizontal, and the forelimbs have two movements, which are the rotational movement achieved by the steering gear and the up and down swing achieved by the energized bending of polypyrrole strips (PPy); the hind limbs are only rotated by the steering gear. Movement, a total of three directions of rotation: horizontal swing up, horizontal swing down, vertical swing.

The invention divides the seal into static seal and dynamic seal, the static seal adopts rubber gasket to seal, and the dynamic seal adopts silicone rubber elastic membrane. It is fixed at one shaft segment that protrudes from the outside, and the other end is glued to the end cover. The end cover is fixed with the lower shell of the bionic turtle through screws, so that when the hindlimb drive shaft and the forelimb bevel gear shaft move, the elastic film can be driven with the hindlimb. The small reciprocating rotation of the shaft and the forelimb bevel gear shaft causes elastic deformation, and at the same time plays a sealing role. This is similar to the rotation of bones driven by human muscles, and the elastic skin can follow it to make small rotations, which has the advantages of low cost, simple structure and reliable sealing.

Sensor: A pressure sensor is installed on the top of the underwater turtle imitation robot, and its real-time depth is judged by the magnitude of the pressure; a temperature and humidity sensor is added to detect the internal sealing of the turtle body, and an alarm will be issued immediately if water enters; a gyroscope is added to adjust the turtle body posture; a camera is installed on the head of the underwater turtle-like robot for observation.

The invention provides a control method for an underwater turtle imitation robot, comprising the following steps:

Step 1: Check, deploy and dive

First, check the underwater turtle-like robot, the main content is whether the limbs move normally, whether the seal is intact, whether the sensor is working normally, whether the power is sufficient, etc. Choose a suitable water area and gently put the underwater turtle robot into the water.

The dive is completed by the mutual cooperation of the forelimb and the hindlimb. The details are as follows: after the hindlimb servo 3 is commanded, the left servo of the hindlimb rotates 90° clockwise, while the right servo of the hindlimb rotates 90° counterclockwise, so that the hindlimbs on both sides are rotated 90° counterclockwise. They are all kept vertically upward, and oscillate reciprocatingly for a total of 60° with this as the center position. The connecting shaft 8 is driven by the steering gear sleeve 17, and the rear limb drive shaft 10 is driven by the small elastic belt 9 to rotate, and the rear limb 1 is oscillated horizontally upward for a total of 60°, a downward thrust is obtained, and the motion is maintained throughout. At the same time, after the forelimb steering gear 18 is instructed, the left steering gear of the forelimb rotates 30° clockwise, and the right steering gear of the forelimb rotates 30° counterclockwise, and the motion is transmitted to the forelimb bevel gear shaft 15 through the bevel gear shaft 16, so that the The front ends of the forelimbs 21 on both sides rise. At this time, the forelimb steering gear 18 stops rotating, and then the software control module applies a reverse voltage to the polypyrrole strip (PPy) 22 to make the hind limbs flap backward and upward, so that the reaction force of the water pushes the turtle body to move forward and downward. Then disconnect the power supply from the polypyrrole strip (PPy) 22, and then the forelimb steering gear 18 will receive a reverse rotation motion command, and rotate counterclockwise twice the first rotation angle, that is, 60°, so that the rear end of the forelimb 21 rises , the forelimb steering gear 18 is stopped, and the software control module applies a reverse voltage to the polypyrrole strip (PPy) 22 to make it flap forward and upward, so that the reaction force of the water pushes the turtle body to move backward and downward. After that, it is repeatedly connected in this order to complete the dive.

Step 2: Go Forward

The propulsion is accomplished by the mutual cooperation of the forelimb and the hindlimb. The details are as follows: after the hindlimb steering gear 3 is instructed, it rotates back and forth for a total of 60°, the connecting shaft is driven by the steering gear sleeve 17, and the hindlimb drive shaft 10 is driven by the small elastic belt 9 to rotate, After completing the vertical reciprocating swing of hind limb 1 for a total of 60°, the forward thrust is obtained, and the movement is maintained throughout the process. At this time, the forelimbs are all driven by the polypyrrole strip (PPy) 22, and the polypyrrole strip (PPy) 2 is applied with a positive voltage and bends downwards, that is, flaps down, at a suitable time interval, and then applies a negative voltage to make the polypyrrole stripe (PPy) 22. (PPy) 22 bends upwards, ie flaps upwards. This cycle completes the propulsion movement. During this process, the swing frequency of the forelimbs and hindlimbs should be kept the same, so as to maintain balance.

Step 3: Turn

There are two solutions, both are differential steering and after the movement is completed, the steering gear needs to return to its original position.

Option 1: Realized by the hind limbs, the fore limbs 21 swing up and down a total of 60° to maintain balance. Among the two rear limb steering gears, one remains stationary, the other steering gear drives the connecting shaft through the steering gear sleeve, and then the small elastic belt 9 drives the rear limb transmission shaft 10 to rotate, so that the rear limb 1 can swing vertically back and forth for a total of 60°, and obtain Forward thrust, and motion is maintained throughout.

Option 2: It is realized by the front limbs, and the hind limbs swing up and down to maintain balance and provide a certain thrust. Of the two forelimbs, one remains motionless, and the other moves as follows: after the forelimb steering gear is commanded, the left forelimb servo rotates 90° clockwise, and the right forelimb servo rotates 90° counterclockwise to make the forelimb upright. At this time, the forelimb steering gear immediately stopped rotating, and then applied a reverse voltage to the polypyrrole strip (PPy) 22 and flapped it backward, so that the reaction force of the water pushed the turtle body to turn.

Step 4: Float

Lifting is mainly done by the hind limbs, and the forelimbs swing up and down a total of 60° to maintain balance. The movement of the hind limb is as follows: After the rear limb servo 3 is instructed, the left servo of the hind limb rotates 90° counterclockwise, while the right servo of the hind limb rotates 90 clockwise, and the center position is reciprocated for a total of 60°. The cylinder 17 drives the connecting shaft 8, and the small elastic belt 9 drives the hindlimb drive shaft 5 to rotate, and the hindlimb oscillates horizontally downward for a total of 60° to obtain an upward thrust, and the motion is maintained throughout the process.

Step 5: Take Back

It is achieved by the movement of the hind limbs. The rear limb steering gear 3 drives the connecting shaft 8 through the steering gear sleeve 17, and then drives the rear limb transmission shaft 10 to rotate by the small elastic belt 9, so as to realize the vertical reciprocating swing of the rear limb for a total of 60°, obtain forward thrust, row to the shore, and complete the recovery. In addition, in the event of an emergency failure, such as failure of the main controller or drive module, it can be retracted by controlling the safe retraction compartment.

Claims

An underwater bionic turtle robot, comprising a bionic turtle upper shell, a bionic turtle lower shell, turtle limbs, a sealing structure, and a driving device arranged inside the turtle shell for driving the action of the turtle limbs;

The upper shell of the bionic turtle and the lower shell of the bionic turtle are separated by silicone rubber for static sealing and connected with screws;

The four limbs of the turtle are divided into forelimbs and hindlimbs, and the transmission shaft of the hindlimb protrudes from the shaft section of the tortoise shell and between the lower shell of the bionic tortoise, and between the shaft section of the forelimb bevel gear shaft protruding from the tortoise shell and the lower shell of the bionic tortoise. There are silicone rubber elastic membranes for waterproofing;

A pressure sensor is installed on the top of the underwater turtle-like robot, and its real-time depth is judged by the magnitude of the pressure; a temperature and humidity sensor is installed inside the underwater turtle-like robot to detect the internal sealing of the turtle body. If water enters, it will immediately alarm; A gyroscope is arranged on the turtle shell to adjust the attitude of the turtle body; a camera is installed on the head of the underwater turtle imitation robot for observation, and it is characterized in that the upper shell of the bionic turtle is composed of an ellipsoid shell part and a spherical shell part,

The shell thickness of the ellipsoid shell portion is obtained by the following formula:

In the formula, p is the external pressure on the shell, σ s is the yield stress of the material, a is the radius of the major axis of the ellipsoid, ρ is the ellipticity, t is the thickness of the shell, and x and y are the Cartesian coordinate system;

The shell thickness of the spherical shell portion is obtained by the following formula:

where R is the radius of the spherical shell.
The underwater bionic turtle robot according to claim 1, further comprising a guardrail mechanism, which is detachably connected to the turtle shell, and the guardrail mechanism includes two groups, which are symmetrically arranged on the tortoise shell. On the left and right sides of the housing, each set of guardrail mechanisms includes:

The guardrail has a quarter ring structure, one end of the inner side of the guardrail is connected to the turtle shell through a buffer mechanism, and the other end of the inner side of the guardrail is connected to the turtle shell through an adjustment mechanism;

The buffer mechanism includes a cylindrical shock absorbing cavity, a connecting rod and a spring, wherein the spring is arranged in the cylindrical shock absorbing cavity, and one end of the cylindrical shock absorbing cavity is provided with a rod hole;

The inner side of the guardrail is provided with a chute, one end of the connecting rod is provided with a first chute contact matched with the chute, and the other end of the connecting rod extends into the cylindrical shock absorbing cavity through the rod hole;

The middle part of the connecting rod is provided with a shaft shoulder, and the shaft shoulder divides the part of the connecting rod located in the cavity of the shock absorber into a first connecting rod segment and a second connecting rod segment, the first connecting rod segment and the The second connecting rod segments are respectively sleeved with one of the springs;

The outer side of the bottom of the cylindrical shock-absorbing cavity is rotatably connected with the turtle shell through a hinge;

The adjustment mechanism includes an adjustment box, an input shaft, a first gear, a second gear and a first threaded rod, wherein,

The adjustment box is arranged on the turtle shell, a first threaded rod and a first transmission shaft are arranged in parallel in the first adjustment box, and the first threaded rod and the first transmission shaft are connected by transmission through a gear transmission group;

The outer end of the first transmission shaft extends out of the adjustment box and is connected with an adjustment handle;

The outer end of the first threaded rod is slidably connected to the guardrail through the second sliding groove contact, and a restriction block is provided on the inner end of the first threaded rod.
The underwater bionic turtle robot according to claim 2, wherein the cross-section of the guardrail is oval and streamline-like.
The underwater bionic turtle robot according to claim 1, wherein the forelimbs are driven by a steering gear combined with a software drive to realize double-degree-of-freedom motion: one is driven by the steering gear: the forelimb steering gear provides power through the forelimb cone The gear set drives the forelimb to rotate; the second is driven by the polypyrrole strips: the two sides of the forelimb are symmetrically covered with a plurality of polypyrrole strips, which are connected to the electrode plate under the clip, and then connected to the wire through the center of the bevel gear shaft of the forelimb. The hole is connected to the software drive control module, and the software control module controls the polypyrrole strip to drive the forelimb to swing up and down;

The driving device of the rear limb includes a rear limb steering gear, a steering gear disc, a bearing seat, a connecting shaft, a small elastic belt and a rear limb transmission shaft, wherein the rear limb steering gear, the steering gear disc and the steering gear sleeve are connected by screws. , the connecting shaft and the steering gear sleeve are connected by screws; the small elastic belt transmits the power to the rear limb transmission shaft, and drives the rear limb to make a rotating motion.
The underwater bionic turtle robot according to claim 1, wherein balance wings are provided on both sides of the lower shell of the bionic turtle to assist in maintaining balance.
The underwater bionic tortoise robot according to claim 1, further comprising a safe retraction cabin connected to the tortoise shell through a traction wire, comprising:

A cabin, the cabin is provided with a partition, the partition divides the cabin into an upper cabin and a lower cabin, the upper cabin is provided with a hatch cover that can be opened or closed, and the upper cabin is provided with a compression Airbag, the bottom of the compressed airbag is connected with the hook ear fixed in the inner cavity of the upper cabin through the lead wire;

The lower cabin is a sealed cabin, and the lower cabin is provided with a hatch cover opening mechanism. The hatch cover opening mechanism includes: a second transmission shaft and a second threaded rod arranged in parallel, and the second transmission shaft and the second threaded rod pass through The gear transmission mechanism is connected.

The servo motor is drivingly connected with the second transmission shaft, and the part of the second threaded rod in the hatch opening mechanism penetrates the baffle and protrudes into the upper cabin. Driven by the servo motor, the second threaded rod can move in the up and down direction inside the cabin to open the hatch cover of the cabin;

The lower cabin is also provided with a transverse plate and a pressure bottom plate, the transverse plate and the pressure bottom plate are connected by bolts, and the pressure plate and the transverse plate are both provided with card slots for fixing the second transmission shaft and the gear transmission. Group;

The cabin is also provided with a signal receiving device for receiving external signals;

a controller, the input end of which is connected to the signal receiving device, and the output end of which is connected to the servo motor;

a power supply, which supplies power to the servo motor, the signal receiving device and the controller;

There are three seals in the cabin, the first is between the upper cabin and the lower cabin, which is a static seal and is sealed with a silicone gasket;

The second place is between the bulkhead and the upper cabin pillar in the upper cabin, which is a static seal and is sealed with a silicone gasket;

The third place is between the second threaded rod and the upper cabin strut in the upper cabin. It is a dynamic seal. It is sealed by a transparent elastic film. on the upper hull strut.
The underwater bionic turtle robot according to claim 1, wherein,

From the perspective of bionics, the tortoise's limbs are formed by two involutes that intersect at the tips of the limbs. When represented by Cartesian coordinates, their equations are:

In the formula, u i =θ i +α i , θ i is the expansion angle, α i is the pressure angle, ri i is the radius of the base circle,

C 1 is the value range of the angle u1, the range is 240°～270°, C 2 is the value range of the angle u2, the range is 210°～265°;

Its section is also composed of two involutes, taking the central section as an example, as follows:

In the formula, u′ i = θ′ i +α′ i , θ′ i is the expansion angle, α′ i is the pressure angle, ri i ′ is the radius of the base circle, C′ 1 is the value range of the angle u′ 1 , The range is 210°～226°, C' 2 is the value range of the angle u' 2 , and the range is 210°～221°;

Its thickness increases first and then gradually decreases from the front end to the rear end;

The hindlimbs are thin around the edges, with a gradual increase in cross-sectional thickness from the edge to the center.
The underwater bionic turtle robot according to claim 1, wherein the shell of the turtle-like robot is streamlined.
A working method based on the underwater bionic turtle robot according to claim 4, characterized in that,

Step 1: Check, deploy and dive

First, check the underwater turtle-like robot. The main contents are whether the limbs move normally, whether the seal is intact, whether the sensor is working normally, and whether the power is sufficient. Select the appropriate water area and put the underwater turtle-like robot into the water;

The dive is completed by the cooperation of the forelimb and the hindlimb. The details are as follows: after the hindlimb servo is instructed, the left servo of the hindlimb rotates 90° clockwise, while the right servo of the hindlimb rotates 90° counterclockwise, so that both hindlimbs are equally Keep vertical and upward, and swing back and forth for a total of 60° at this center position, drive the connecting shaft through the steering gear sleeve, and drive the rear limb drive shaft to rotate by the small elastic belt. At the same time, after the forelimb steering gear is commanded, the left forelimb servo rotates 30° clockwise, and the right forelimb servo rotates 30° counterclockwise, and the motion is transmitted to the forelimb bevel gear set. The forelimbs are lifted, so that the front ends of the forelimbs on both sides rise. At this time, the forelimb steering gear stops rotating, and then the software control module applies a reverse voltage to the polypyrrole strips, so that the hind limbs flap backwards and upwards, so that the reaction force of the water pushes the turtle body move forward and downward;

Then disconnect the power supply and the polypyrrole strip, and then the forelimb rudder will get a reverse rotation motion command, and rotate counterclockwise twice the first rotation angle, that is, 60°, so that the rear end of the forelimb will rise, and the forelimb rudder will stop. , the software control module applies a reverse voltage to the polypyrrole strip to make it flap forward and upward, so that the reaction force of the water pushes the turtle body to move backward and downward, and then it is repeatedly turned on in this order to complete the diving movement;

Step 2: Go Forward

The propulsion is accomplished by the mutual cooperation of the forelimb and the hindlimb. The details are as follows: after the servo of the hindlimb is commanded, it rotates back and forth for a total of 60°, the connecting shaft is driven by the steering gear sleeve, and the drive shaft of the hindlimb is driven by the small elastic belt to rotate, and the hindlimb is erected. Swing back and forth for a total of 60°, obtain forward thrust, and keep the movement during the whole process. At this time, the forelimbs are all driven by the polypyrrole strips, and the polypyrrole strips are applied with a positive voltage and bend downward, that is, flap down, with appropriate intervals Time, and then apply a negative voltage to make the polypyrrole strips bend upwards, that is, flap upwards. This cycle completes the propulsion movement. During this process, the swing frequency of the forelimb and the hindlimb should be kept the same, so as to maintain balance;

Step 3: Turn

There are two solutions, both are differential steering and after the movement is completed, the steering gear needs to return to its original position,

Option 1: Realized by the hind limbs, the forelimbs swing up and down a total of 60° to maintain balance, one of the two hind limb servos remains stationary, the other hind limb servo drives the connecting shaft through the steering gear sleeve, and then the small elastic belt drives the hind limbs The drive shaft rotates to realize the vertical reciprocating swing of the hind limbs for a total of 60°, obtain forward thrust, and keep the movement during the whole process;

Option 2: Realized by the forelimb, the hind limb swings up and down to maintain a balance and provide a certain thrust, one of the two forelimbs remains motionless, and the other moves as follows: after the forelimb servo is commanded, the left forelimb servo rotates 90° clockwise, The steering gear on the right side of the forelimb is rotated 90° counterclockwise, so that the forelimbs on both sides are vertical. At this time, the steering gear of the forelimb stops rotating immediately, and then applies a reverse voltage to the polypyrrole strip and flaps it to the rear side, so that the reaction force of the water is caused by the water. Push the turtle body to turn;

Step 4: Float

The uplift is mainly accomplished by the hind limbs. The forelimbs swing up and down a total of 60° to maintain balance. The movement of the hind limbs is as follows: After the hind limb servo is commanded, the left servo of the hind limb rotates 90° counterclockwise, while the right servo of the hind limb rotates clockwise. Rotate 90 degrees, keep both hind limbs vertically downward, and rotate back and forth for a total of 60° with this as the center position, drive the connecting shaft through the steering gear sleeve, and drive the hind limb drive shaft to rotate by the small elastic belt, and complete the horizontal reciprocation of the hind limbs downward. Swing a total of 60°, get upward thrust, and maintain motion throughout the process;

Step 5: Take Back

It is realized by the movement of the hind limb, the steering gear of the hind limb drives the connecting shaft through the steering gear sleeve, and then the drive shaft of the hind limb is driven to rotate by the small elastic belt, so as to realize the vertical reciprocating swing of the hind limb for a total of 60°, obtain the forward thrust, row to the shore, and complete the recovery. Also, throughout the process, .
A working method based on the described underwater bionic turtle robot according to claim 6, characterized in that, if an emergency failure occurs, the safe recovery is carried out by controlling the safe recovery cabin, specifically:

The operator sends an ascending command to the safe retraction cabin, so that the servo motor in the cabin rotates, the hatch cover is opened through the hatch cover opening mechanism, the compressed air bag is released, and the imitation turtle robot is driven to float up.