Swimming foot for swimming robot, swimming robot and control method thereof

Abstract

The invention discloses a swimming foot for a swimming robot, which comprises a plurality of rigid sheets, the plurality of rigid sheets are arranged at intervals, every two adjacent rigid sheets are connected by a flexible piece, and the connecting part of the flexible piece corresponding to the interval between the two adjacent rigid sheets is provided with a curved surface structure. The invention further discloses a swimming robot with the swimming foot and a control method of the swimming robot. The swimming robot cannot be damaged even if collision occurs in the stroke, meanwhile, the impact force borne by the swimming robot in the swimming process is smaller, and the swimming robot has higher movement flexibility and environmental adaptability.

Description

Technical Field

[0001] The present invention belongs to the technical field of robots, and more specifically, relates to a swimming foot for a swimming robot, a swimming robot, and a control method thereof. Background Art

[0002] The dragonfly-mimicking swimming robot belongs to a kind of bionic underwater robot. Its system design mainly combines the structure, behavior pattern, gait of the swimming feet (middle feet and hind feet) of dragonflies in nature, as well as the shape of dragonflies.

[0003] In the dragonfly-mimicking swimming robot, the dragonfly-mimicking thruster mainly imitates the structural feature of the variable area (and variable speed) of the swimming feet of dragonflies in nature during the water-paddling process. Specifically, during the stroke of its swimming feet, there is a larger swimming area and a faster swinging speed relative to the swimming direction. During the return stroke, there is a smaller swimming area and a slower swinging speed relative to the swimming direction, thereby generating an effective propulsion force. To achieve this feature, the current main technical solution is: to actively change the area of the robot's swimming feet by controlling the joints of each swimming foot with motors, so as to generate effective propulsion. However, the main disadvantages of this technical solution are: poor environmental adaptability brought by the rigid connection between the swimming foot joints, and large impact during collision, which easily leads to damage. In addition, the design of multiple motors for a single swimming foot brings greater complexity to the control system of the robot. Summary of the Invention

[0004] In order to solve the above technical problems existing in the prior art, the present invention provides a swimming foot for a swimming robot, a swimming robot, and a control method thereof that can achieve high flexibility (small impact).

[0005] According to one aspect of the present invention, there is provided a swimming foot for a swimming robot, which includes a plurality of rigid sheets, the plurality of rigid sheets are arranged at intervals, and two adjacent rigid sheets are connected by a flexible member, and a connecting portion of the flexible member corresponding to the interval between the two adjacent rigid sheets has a curved surface structure.

[0006] In an example of the swimming foot provided in the above aspect, the flexible member further includes a first fixing portion and a second fixing portion, the connecting portion is connected between the first fixing portion and the second fixing portion, the first fixing portion is fixed to one of the two adjacent rigid sheets, and the second fixing portion is fixed to the other of the two adjacent rigid sheets.

[0007] In an example of the swimming foot provided in the above aspect, the connecting portion includes a first connecting rod and a second connecting rod. Both the first connecting rod and the second connecting rod are connected between the first fixing portion and the second fixing portion, and the first connecting rod and the second connecting rod are spaced apart from each other. The curved surface structure is connected between the first connecting rod and the second connecting rod.

[0008] In an example of the swimming foot provided in the above aspect, the curved surface structure is in the shape of a cylindrical surface.

[0009] According to another aspect of the present invention, there is also provided a swimming robot, which includes a robot body and a plurality of swimming feet connected to the robot body. The swimming feet are the above-mentioned swimming feet.

[0010] In an example of the swimming robot provided in the above aspect, the robot body includes a bottom shell, an upper shell, and a plurality of waterproof servo motors. The bottom shell and the upper shell are fixedly combined with each other to form an accommodation space. The plurality of waterproof servo motors are arranged in the accommodation space, and the swimming feet are fixedly connected to the steering wheels of the corresponding waterproof servo motors.

[0011] In an example of the swimming robot provided in the above aspect, when the swimming robot is swimming, the protrusion of the curved surface structure faces the advancing direction of the swimming robot.

[0012] In an example of the swimming robot provided in the above aspect, the number of the waterproof servo motors is four. The four waterproof servo motors are respectively a middle left swimming foot waterproof servo motor, a middle right swimming foot waterproof servo motor, a rear left swimming foot waterproof servo motor, and a rear right swimming foot waterproof servo motor;

[0013] The number of the swimming feet is four. The four swimming feet are respectively a middle left swimming foot, a middle right swimming foot, a rear left swimming foot, and a rear right swimming foot;

[0014] Wherein, the middle left swimming foot is fixedly connected to the steering wheel of the middle left swimming foot waterproof servo motor, the middle right swimming foot is fixedly connected to the steering wheel of the middle right swimming foot waterproof servo motor, the rear left swimming foot is fixedly connected to the steering wheel of the rear left swimming foot waterproof servo motor, and the rear right swimming foot is fixedly connected to the steering wheel of the rear right swimming foot waterproof servo motor.

[0015] According to another aspect of the present invention, there is also provided a control method for the above-mentioned swimming robot, which includes: in the first half cycle of the swimming cycle of the swimming robot, the rear left swimming foot and the rear right swimming foot are in the stroke stage and synchronously paddle backward, and the middle left swimming foot and the middle right swimming foot are in the return stroke stage and synchronously paddle forward; in the second half cycle of the swimming cycle of the swimming robot, the rear left swimming foot and the rear right swimming foot are in the return stroke stage and synchronously paddle forward, and the middle left swimming foot and the middle right swimming foot are in the stroke stage and synchronously paddle backward.

[0016] In an example of the control method for the swimming robot provided in the above-mentioned another aspect, the control method further includes: using the following controller function to control the swimming robot,

[0017]

[0018] where x i is the actual output amplitude of the i-th swimming foot, A i is the maximum output amplitude of the i-th swimming foot, f is the frequency of the swing of the swimming foot, is the phase difference of the swing of the i-th swimming foot, b i is the offset of the swing of the i-th swimming foot.

[0019] Beneficial effects: The swimming robot of the present invention will not be damaged even if it collides during the stroke. At the same time, the impact force received by the swimming robot during swimming is also smaller, making the swimming robot have higher motion compliance and environmental adaptability. Description of the Drawings

[0020] Through the following description in conjunction with the drawings, the above and other aspects, features, and advantages of the embodiments of the present invention will become clearer. In the drawings:

[0021] Figure 1 is a perspective schematic view of a swimming robot according to an embodiment of the present invention;

[0022] Figure 2 is a front view of a swimming foot according to an embodiment of the present invention;

[0023] Figure 3 is Figure 2 a top view of the swimming foot shown;

[0024] Figure 4 is a schematic diagram of the swimming foot generating an asymmetric force according to an embodiment of the present invention;

[0025] Figure 5 is a schematic diagram of gait analysis comparison between a swimming robot according to an embodiment of the present invention and a traditional swimming robot. Detailed Embodiments

[0026] Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention can be implemented in many different forms, and the present invention should not be construed as being limited to the specific embodiments set forth herein. On the contrary, these embodiments are provided to explain the principles of the present invention and its practical applications, so that other technicians in the art can understand various embodiments of the present invention and various modifications suitable for specific intended applications.

[0027] As used herein, the term "comprising" and its variants denote open terms, meaning "including but not limited to". Terms such as "based on", "according to", etc. mean "at least partially based on", "at least partially according to". The term "one embodiment" and "an embodiment" mean "at least one embodiment". The term "another embodiment" means "at least one other embodiment". Terms such as "first", "second", etc. may refer to different or the same objects. Other definitions may be included below, either explicit or implicit. Unless explicitly specified in the context, the definition of a term is consistent throughout the specification.

[0028] Figure 1 is a perspective schematic view of a swimming robot according to an embodiment of the present invention.

[0029] Refer to Figure 1 , a swimming robot according to an embodiment of the present invention includes a bottom shell 1, an upper shell 3, a sealed cabin 2, a middle-foot waterproof servo 4, a switch 5, a rear-foot waterproof servo 6, rear swimming feet 7 and middle swimming feet 8.

[0030] The bottom shell 1 and the upper shell 3 are assembled together to form an accommodation space. The sealed cabin 2, the middle-foot waterproof servo 4 and the rear-foot waterproof servo 6 are all accommodated in this accommodation space. Among them, the sealed cabin 2 houses electronic components such as a control board, a wireless communication module, an IMU, and a lithium battery, and these electronic components are not marked in the figure. The wires inside the sealed cabin 2 pass through the wire passing holes (not marked in the figure) on the end cover (not marked in the figure) at the upper part of the sealed cabin 2, and thus are connected to the middle-foot waterproof servo 4, the rear-foot waterproof servo 6 and the switch 5 fitted in the upper shell 3. All the wire passing holes are sealed with sealant. The sealed cabin 2 and the bottom shell 1 are an integral whole, and its end cover is waterproofed by a sealing ring and screws. Therefore, the bottom shell 1, the upper shell 3, the sealed cabin 2, the middle-foot waterproof servo 4, the switch 5, the rear-foot waterproof servo 6 and the electronic components in the sealed cabin 2, etc. constitute the robot body.

[0031] In this embodiment, there are two middle-foot waterproof servos 4, two hind-foot waterproof servos 6, two hind swimming feet 7, and two middle swimming feet 8. Of course, these are only examples, and the quantity of the present invention is not limited thereto. For the convenience of the following description, the two middle-foot waterproof servos 4 are respectively called the middle left swimming-foot waterproof servo and the middle right swimming-foot waterproof servo, the two hind-foot waterproof servos 6 are respectively called the hind left swimming-foot waterproof servo and the hind right swimming-foot waterproof servo, the two hind swimming feet 7 are respectively called the hind left swimming foot and the hind right swimming foot, and the two middle swimming feet 8 are respectively called the middle left swimming foot and the middle right swimming foot.

[0032] In this embodiment, taking the central axis of the fuselage of the swimming robot as the reference, the middle left swimming-foot waterproof servo and the middle right swimming-foot waterproof servo are symmetrically arranged, the hind left swimming-foot waterproof servo and the hind right swimming-foot waterproof servo are symmetrically arranged, the hind left swimming foot and the hind right swimming foot are symmetrically arranged, and the middle left swimming foot and the middle right swimming foot are symmetrically arranged.

[0033] Furthermore, the middle left swimming foot is fixedly connected to the steering wheel of the middle left swimming-foot waterproof servo, the middle right swimming foot is fixedly connected to the steering wheel of the middle right swimming-foot waterproof servo, the hind left swimming foot is fixedly connected to the steering wheel of the hind left swimming-foot waterproof servo, and the hind right swimming foot is fixedly connected to the steering wheel of the hind right swimming-foot waterproof servo.

[0034] The structure of the swimming foot will be described in detail below. Since the structures of each swimming foot are generally similar, only one swimming foot will be taken as an example for detailed description. Figure 2 It is a front view of the swimming foot according to an embodiment of the present invention. Figure 3 It is Figure 2 the top view of the swimming foot shown.

[0035] Referring to Figure 2 and Figure 3 , this swimming foot is a hind swimming foot, which is a four-section structure. The first section structure is composed of one of the hind-foot waterproof servos 6 and a rigid connecting rod 71. As described above, the hind-foot waterproof servo 6 is accommodated and fixed in the accommodation space. The other three section structures are connected in series to form a four-degree-of-freedom bionic swimming hind foot. Among them, the connection between the first section structure and the second section structure (the rigid sheet 77 closest to the first section structure) is a traditional soft rubber-rigid mechanical limit structure, specifically composed of a rigid connecting rod 71 and another rigid connecting rod 76 through a pin shaft 72, a shaft end retaining ring 73, and a square soft rubber 74 fixed on the two rigid connecting rods. When bending, the soft rubber 74 plays a role. When straightening, the mechanical limit structure 75 of the rigid connecting rod of the second section structure and the rigid connecting rod 71 plays a role to keep the swimming foot open. This design is considered that the first section structure is closer to the robot body to avoid interference between the swimming foot and the robot body.

[0036] Specifically, the other three-section structure includes three rigid sheets 77, which are arranged in a line at intervals, and adjacent two rigid sheets 77 are connected by a flexible member 78. The connecting portion 781 of the flexible member 78 corresponding to the interval between the adjacent two rigid sheets 77 has a curved surface structure 7811. In this embodiment, the rigid sheet 77 closest to the first-section structure and another rigid link 76 may be integrally formed.

[0037] The flexible member 78 includes a first fixing portion 782 and a second fixing portion 783. The connecting portion 781 is connected between the first fixing portion 782 and the second fixing portion 783. The first fixing portion 782 is fixed to one of the adjacent two rigid sheets 77, and the second fixing portion 783 is fixed to the other of the adjacent two rigid sheets 77.

[0038] The connecting portion 781 includes a first connecting rod 7812 and a second connecting rod 7813. The first connecting rod 7812 and the second connecting rod 7813 are connected between the first fixing portion 782 and the second fixing portion 783, and the first connecting rod 7812 and the second connecting rod 7813 are spaced from each other. The curved surface structure 7811 is connected between the first connecting rod 7812 and the second connecting rod 7813. In this embodiment, the curved surface structure 7811 is in the shape of a cylindrical surface, but the present invention is not limited thereto. In addition, when the swimming robot swims, the convex of the curved surface structure 7811 faces the advancing direction of the swimming robot.

[0039] It should be noted that, in this embodiment, the area of the rigid sheet of the rear swimming foot is larger than that of the rigid sheet of the middle swimming foot, and / or the series connection number of the rigid sheets of the rear swimming foot is more than that of the rigid sheets of the middle swimming foot.

[0040] Figure 4 It is a schematic diagram of the asymmetric force generated by the swimming foot according to an embodiment of the present invention.

[0041] Referring to Figure 4 When the swimming foot paddles in the Figure 4 mid-stroke direction, by using the "tape-like structure" of the swimming foot, when it bends in the Figure 4 mid-stroke force direction, it has a greater stiffness. At this time, the swimming foot is not easily bent by the water resistance. Therefore, the swimming robot can obtain a greater thrust during the stroke. On the contrary, when the swimming foot paddles in the return stroke direction, by using the "tape-like structure" of the swimming foot, when it bends in the Figure 4 return stroke force direction, it has a smaller stiffness. At this time, the swimming foot is easily bent by the water resistance. Therefore, the swimming robot can obtain a smaller resistance during the stroke.

[0042] It should be noted that in this embodiment, since the switching between the two states of high stiffness (during the stroke) and low stiffness (during the return stroke) is a switching between two fixed values, the impact force on the swimming legs is relatively small. However, when switching from infinite stiffness (traditional rigid mechanical limit) to a lower stiffness value, the impact force on the swimming legs is greater. Moreover, when in the stroke stage (traditional rigid mechanical limit), if a rigid collision occurs to the swimming legs, the thruster is likely to be damaged. In this process of the thruster of this embodiment, the swimming legs can undergo a certain degree of adaptive bending to avoid damage caused by rigid collisions.

[0043] Figure 5 It is a schematic diagram for gait analysis and comparison of a swimming robot according to an embodiment of the present invention and a traditional swimming robot. In Figure 5 , Figure (a) is a schematic diagram of a swimming robot swimming forward with four legs according to an embodiment of the present invention, Figure (b) is a schematic diagram of a traditional swimming robot swimming forward with two legs, Figure (c) is a schematic diagram of a swimming robot swimming left with four legs according to an embodiment of the present invention, and Figure (b) is a schematic diagram of a traditional swimming robot swimming left with two legs.

[0044] In Figure (a), in the first half cycle (0 - 0.5T), the rear swimming legs of the swimming robot are in the stroke stage and synchronously move backward. At this time, the middle swimming legs are in the return stroke stage and synchronously move forward. However, since the rear swimming legs have a larger area (the area of the rigid sheet is larger) and a longer length (the number of rigid sheets connected in series is more), the resultant force generated is forward, so the swimming robot can be propelled forward. In the second half cycle (0.5T - 1T), the rear swimming legs of the swimming robot are in the return stroke stage and synchronously move forward. At this time, the middle swimming legs are in the stroke stage and synchronously move forward. Although the rear swimming legs generate a smaller resistance in the return stroke stage, the thrust generated by the middle swimming legs in the stroke stage can increase the swimming speed of the swimming robot. Therefore, in the second half cycle, the swimming robot of this embodiment can generate a greater propulsion force compared to the two - leg water - paddling shown in Figure (b).

[0045] In Figure (c), by suppressing the left - hand swimming legs from swinging, the right - hand swimming legs of the swimming robot swing and generate a resultant moment to the left, realizing the turning (left - turn) gait. Compared with the turning gait of the two - leg swimming robot in Figure (d), also in the second half cycle (0.5T - 1T), the middle swimming legs provide a thrust moment to weaken the resistance moment generated by the rear swimming legs in the return stroke stage, thereby improving the maneuverability of the swimming robot.

[0046] In addition, the following controller function is used to control the swimming robot according to an embodiment of the present invention. The controller function is expressed as:

[0047]

[0048] where x i is the actual output amplitude of the i-th swimming leg, A i is the maximum output amplitude of the i-th swimming leg, f is the frequency of the swing of the swimming leg, is the phase difference of the swing of the i-th swimming leg, b i is the offset of the swing of the i-th swimming leg.

[0049] In this embodiment, the four swimming legs adopt the same frequency, and the specific parameters are shown in the following table:

[0050]

[0051] In summary, the swimming robot according to the embodiment of the present invention will not be damaged even if it collides during the stroke. At the same time, the impact force received by the swimming robot during the swimming process is also smaller, so that the swimming robot has higher motion compliance and environmental adaptability.

[0052] The above has described in detail the optional implementation manners of the embodiments of the present invention in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above implementation manners. Within the technical concept scope of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all belong to the protection scope of the embodiments of the present invention.

Claims

1. A swimming foot for a swimming robot, characterized in that: The swimming foot comprises a plurality of rigid plates, the plurality of rigid plates are arranged at intervals, two adjacent rigid plates are connected by a flexible member, and a connection portion of the flexible member corresponding to the interval between two adjacent rigid plates has a curved surface structure.

2. The swimming foot according to claim 1, characterized in that: The flexible member further includes a first fixing portion and a second fixing portion, the connecting portion is connected between the first fixing portion and the second fixing portion, the first fixing portion is fixed to one of the two adjacent rigid sheets, and the second fixing portion is fixed to the other of the two adjacent rigid sheets.

3. The swimming foot according to claim 2, characterized in that: The connecting portion includes a first connecting rod and a second connecting rod, the first connecting rod and the second connecting rod are both connected between the first fixing portion and the second fixing portion, and the first connecting rod and the second connecting rod are spaced apart from each other, and the curved surface structure is connected between the first connecting rod and the second connecting rod.

4. The swimming foot according to any one of claims 1 to 3, characterized in that: The curved surface structure is in a cylindrical shape.

5. A swimming robot, characterized in that: The swimming robot comprises a robot body and a plurality of swimming feet connected to the robot body, and the swimming feet are the swimming feet according to any one of claims 1 to 4.

6. The swimming robot according to claim 5, characterized in that: The robot body includes a bottom shell, an upper shell, and a plurality of waterproof servos. The bottom shell and the upper shell are fixedly combined with each other to form an accommodating space. The plurality of waterproof servos are arranged in the accommodating space. The swimming feet are fixedly connected to the steering discs of the corresponding waterproof servos.

7. The swimming robot according to claim 5 or 6, characterized in that: When the swimming robot swims, the protrusions of the curved surface structure face the moving direction of the swimming robot.

8. The swimming robot according to claim 6, characterized in that: The number of the waterproof steering gears is four, and the four waterproof steering gears are respectively a middle left swimming foot waterproof steering gear, a middle right swimming foot waterproof steering gear, a rear left swimming foot waterproof steering gear and a rear right swimming foot waterproof steering gear; The number of the swimming feet is four, and the four swimming feet are respectively a middle left swimming foot, a middle right swimming foot, a rear left swimming foot and a rear right swimming foot; Among them, the middle left swimming foot is fixedly connected to the steering wheel of the middle left swimming foot waterproof servo, the middle right swimming foot is fixedly connected to the steering wheel of the middle right swimming foot waterproof servo, the rear left swimming foot is fixedly connected to the steering wheel of the rear left swimming foot waterproof servo, and the rear right swimming foot is fixedly connected to the steering wheel of the rear right swimming foot waterproof servo.

9. A method for controlling a swimming robot according to claim 8, characterized in that: The control method comprises: In the first half of the swimming cycle of the swimming robot, the rear left swimming foot and the rear right swimming foot are in the stroke phase and paddling backward synchronously, and the middle left swimming foot and the middle right swimming foot are in the return phase and paddling forward synchronously; In the second half of the swimming cycle of the swimming robot, the rear left swimming foot and the rear right swimming foot are in the return phase and paddling forward synchronously, and the middle left swimming foot and the middle right swimming foot are in the stroke phase and paddling backward synchronously.

10. The control method according to claim 9, characterized in that: The control method further comprises: controlling the swimming robot using the following controller function: Among them, x i is the actual output amplitude of the ith swimming foot, A i is the maximum output amplitude of the ith swimming foot, f is the frequency of the swimming foot swing, is the phase difference of the ith swimming leg swing, b i is the bias of the i-th swimming leg swing.

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