Bionic amphibious robot based on duck web structure

Abstract

A bionic amphibious robot based on a duck web structure comprises a body and at least one pair of bionic feet disposed externally thereof. Each bionic foot comprises a servo frame, a power unit disposed thereon, an upper active rocker arm, a lower active rocker arm, and an actuator link connected to each of the upper and lower active rockers. The upper active rocker arm is connected to one end of the actuator link via a connecting rod, and the lower active rocker arm is connected to the middle of the actuator link, thereby forming a five-bar linkage with two degrees of freedom. The other end of the actuator link is provided with an adaptive flipper arm, and the power unit is connected to the upper active rocker arm, the lower active rocker arm, and the adaptive flipper arm via flexible cables. The present invention utilizes an integrated leg-fin structure to enable the flippers to open and close without the need for an additional motor. This addresses the problem of traditional leg-fin robots being unable to adapt to wetland environments where water and land intersect, further broadening the application scenarios of leg-fin robots.

Description

Technical Field

[0001] The present invention relates to the technical field of bionic robots, in particular to a bionic amphibious robot based on a duck web structure. Background Art

[0002] With the advancement of science and technology, the requirements for amphibious quadruped robots are becoming increasingly stringent, such as the ability to navigate complex terrain and effectively connect different workspaces on land and water. The goal is to more simply and efficiently complete tasks that are difficult for robots with a single motion space to achieve. However, due to structural design limitations, existing amphibious bionic robots are either difficult to adapt to walking on land or achieve amphibious movement in water. Some use sealed motors attached to the ends of the leg-like structures for drive, but sealing for underwater environments increases the complexity of the overall design. The long motor leads are also not suitable for waterproofing for long-term underwater operation. Summary of the Invention

[0003] To address the aforementioned shortcomings of the prior art, the present invention proposes a bionic amphibious robot based on a duck webbed structure. This robot utilizes an integrated leg-fin structure to integrate the water-movement paddling unit of a duck webbed foot with the leg structure of a traditional legged robot. Furthermore, an innovative flexible cable-based adaptive opening and closing mechanism for the webbed foot allows for the webbed foot to open and close without requiring an additional motor. This integrated leg-fin structure balances the robot's aquatic and terrestrial performance. Through gait design, the webbed foot remains closed during terrestrial walking, while adaptively expanding during backward paddling and closing during forward paddling during swimming. These dynamics can be adaptively achieved through the flexible cable structure by simply controlling the two motors in the leg's two-degree-of-freedom linkage mechanism, enabling the robot to quickly switch between aquatic and terrestrial motion. The present invention's structure allows the leg structure to fully control the motors, preventing the motors from being completely submerged in water and requiring long wiring distances, thus facilitating a waterproof design for underwater motion. This design makes full use of the leg-type mechanism's high movement speed and obstacle-crossing performance in unstructured terrestrial environments and the flipper structure's high propulsion performance and energy utilization rate in underwater fluid environments, taking into account both terrestrial and water movement performance and terrestrial and water switching capabilities, solving the problem that traditional legged robots cannot adapt to wetland environments where land and water intersect, and further broadening the application scenarios of legged robots.

[0004] The present invention is achieved through the following technical solutions:

[0005] The present invention relates to a bionic amphibious robot based on a duck web structure, comprising: a body portion and at least one pair of bionic feet respectively arranged on the outside of the body portion, wherein each bionic foot comprises: a servo frame, a power unit arranged thereon, an upper active rocker arm, a lower active rocker arm, and an actuator link respectively connected to the upper active rocker arm and the lower active rocker arm, wherein: the upper active rocker arm is connected to one end of the actuator link via a connecting rod, the lower active rocker arm is connected to the middle part of the actuator link, thereby forming a five-bar linkage with two degrees of freedom, the other end of the actuator link is provided with an adaptive flipper, and the power unit is respectively connected to the upper active rocker arm, the lower active rocker arm, and the adaptive flipper arm via a flexible cable.

[0006] The servo frame, upper active rocker arm, lower active rocker arm, connecting rod and executive connecting rod are all hinged through an articulated-flexible cable reversing integrated structure, which includes: a plug bolt and a hollow stepped shaft, two flange bearings and two thrust bearings arranged thereon, wherein: the inner holes of the hollow stepped shaft, thrust bearing and flange bearing are concentrically fitted on the plug bolt and tightened by the plug bolt, the two ends of the hollow stepped shaft are close to the two thrust bearings, and the other ends of the two thrust bearings are close to the end of the connecting rod of the next stage, and the two reamed holes at the end of the connecting rod of the next stage are respectively fitted with two flange bearings.

[0007] The central portion of the hollow stepped shaft with a larger outer diameter cooperates with an H-groove bearing for winding the flexible cable, and the portions on both sides with smaller outer diameters cooperate with the ends of the previous connecting rod.

[0008] The articulated-cable reversing integrated structure realizes the articulation between the front and rear stage connecting rods, and the H-groove bearing provided therein enables the cable control structure to be wound.

[0009] After being led out from the bionic instep, the cable is wound around the H-groove bearings in the three hinged-cable reversing integrated structures for one turn before being led out again. This cable winding method ensures that the cable length between the first and second joints, as well as the cable length between the second and third joints, remains unchanged. The sum of the distance between the third joint and the fixed point on the cable end fixture, and the distance between the first joint and the bionic instep, is a constant. Furthermore, by controlling the distance between the third joint and the fixed point on the cable end fixture, the opening and closing of the flippers can be controlled, and the size of the flipper opening and closing also becomes a single-valued function of the swing angle of the upper active rocker arm. By designing a motion gait, combined adaptive control of leg movement and flipper opening and closing can be achieved.

[0010] Technical Effects

[0011] The present invention adopts an integrated leg-fin design, integrating a duck-foot-like fin structure into the leg structure of a leg-like robot. A flexible cable-based fin opening and closing control system is designed to address this structural feature. The fin opening and closing are driven by the motion of the prime mover of the two-degree-of-freedom five-bar leg structure. The gait design of the two-degree-of-freedom five-bar linkage mechanism in the foot enables adaptive control of leg movement and fin opening and closing. The present invention couples the leg mechanism motion with the fin opening and closing motion through the integrated leg-fin structure and flexible cable control system. Combined with the kinematic design of the integrated leg-fin structure, the fins can adaptively deploy during backward paddling and close during forward paddling when swimming in water. When walking on land, the fins adaptively fold within the integrated leg-fin structure, minimizing the impact of the fins on the robot's land-based walking performance. This structure simply and conveniently implements both paddling in water and walking on land, and allows for rapid switching between the two motion states, achieving the goal of amphibious locomotion. The leg-fin integrated structure and soft-cable control system also removes the motor immersed in water at the end of the leg in existing technical means, and only uses the rod located above the fuselage to drive the motor, reducing the complexity of the control system and avoiding immersing electrical components such as motors and wires in water, thereby improving the waterproof performance during water sports. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the present invention;

[0013] Figure 2 This is a schematic diagram of the overall structure of the legs and flippers;

[0014] Figure 3 This is a schematic diagram of the structure of the servo frame part of the leg structure;

[0015] Figure 4 Schematic diagram of the front and side views of the adaptive duck-like flipper structure;

[0016] Figure 5 Schematic diagram of the flexible cable structure for adaptive opening and closing of the flippers;

[0017] Figure 6 It is a schematic diagram of the principle of the present invention;

[0018] Figure 7 Schematic diagram of the working cycle of the embodiment;

[0019] Figure 8 is the calculated opening and closing of the flippers in both water and land gaits;

[0020] Figure 9 Schematic diagram of the position joint and wire-controlled commutation structure;

[0021] In the figure: A electronic control box, B frame, C bionic foot, D float, 1 servo frame, 2 upper active rocker, 3 connecting rod, 4 actuator link, 5 lower active rocker, 6 adaptive flipper overall structure, 7 sliding bearing and connector, 8 servo fixing plate, 9 connecting angle piece, 10 first waterproof servo, 11 second waterproof servo, 12 lateral swing servo, 13 flexible cable end fixing piece, 14 flipper skeleton rod group, 15 bionic foot, 16 bionic instep, 17 bionic instep guide, 18 guide rail fixing plate, 19 elastic rope fixing hole, 20 flipper membrane fixing hole, 21 flexible rope, 22 flipper membrane, 23 elastic rope, first to third joints a, b, c, H-slot bearing d, plug bolt e, hollow stepped shaft sleeve f, flange bearing g, thrust bearing h. DETAILED DESCRIPTION

[0022] like Figure 1 and Figure 2 As shown, this embodiment relates to a bionic amphibious robot based on a duck web structure, including: a set-top control box A, a frame B, four symmetrical bionic feet, and a float D, wherein: the set-top control box contains a control board, a signal receiver, a battery and a circuit; the frame is respectively connected to the set-top control box, the bionic feet and the float; the bionic feet provide power for the robot; and the float provides buoyancy for the robot.

[0023] The bionic foot includes: a servo frame 1, waterproof servos 10 and 11, an upper active rocker arm 2 and a lower active rocker arm 5, and an actuator link 4 respectively connected to the upper active rocker arm 2 and the lower active rocker arm 5, wherein: the upper active rocker arm 2 is connected to one end of the actuator link 4 through a connecting rod 3, and the lower active rocker arm 5 is connected to the middle part of the actuator link 4 to form a five-bar linkage with two degrees of freedom. The other end of the actuator link 4 is provided with an adaptive flipper 6, and the power unit is respectively connected to the upper active rocker arm 2, the lower active rocker arm 5 and the adaptive flipper 6 through a flexible cable 21.

[0024] The steering gear frame 1 is connected to the fuselage part through sliding bearings 7 and connecting angle pieces 9.

[0025] Each part of the five-link mechanism is composed of two aluminum plates connected by a connector, with space left in the middle for the flexible cable to be routed.

[0026] The fuselage part includes: a main fixing plate, a float box and an electronic control system sealing box, wherein: the main fixing plate is an aluminum plate made by laser cutting, and is provided with openings on the main fixing plate for connecting the leg and fin structure, the electronic control system sealing box and the float box; the float box is a sealed box structure made of acrylic plate, with an extended edge on the upper edge, and a hole on the extended edge to achieve connection with the main fixing plate; the control circuit of the entire machine is encapsulated in the electronic control system sealing box, and after the wiring is completed, it is sealed and waterproofed with silicone.

[0027] An outer edge is left at the lower side of the sealing box, and a hole is provided on the outer edge to achieve connection with the main fixing plate.

[0028] The power unit includes: a steering gear fixing plate 8, first and second waterproof steering gears 10 and 11 arranged thereon, and a lateral swing steering gear 12, wherein: one end of the steering gear fixing plate 8 is connected to the sliding bearing 7 on the steering gear frame 1, and the other end is connected to the lateral swing steering gear 12. The rotational output of the lateral swing steering gear 12 drives the entire steering gear frame to rotate along the axis of the sliding bearing 7, thereby achieving lateral swinging of the entire leg structure and switching between a land walking form and a stable swimming posture in water; the first waterproof steering gear 10 and the second waterproof steering gear 11 serve as drivers of the five-bar linkage mechanism, and are respectively connected to the upper active rocker 2 and the lower active rocker 5 via flexible cables and a steering wheel, thereby controlling the movement of the bionic foot and driving the adaptive control of the adaptive flipper 6.

[0029] The servo fixing plate 3 is provided with a flexible rope end fixing piece 13, and the end of the flexible rope end fixing piece 13 is provided with a flexible rope fixing hole. The geometric dimensions of the flexible rope end fixing hole are theoretically calculated so that the position of the flexible rope fixing hole at the end can meet the needs of automatic adaptive opening and closing of the fins, specifically:

[0030] ① Planar geometry methods are used to model the two-degree-of-freedom five-bar linkage that is responsible for leg movement, and the relationship between the end position of the foot and the swing angles of the upper and lower active rockers is constructed.

[0031] ② Using the relationship obtained in step ① and the given foot trajectory, use the kinematic inverse method to calculate the corresponding motion laws of the upper active rocker and the lower active rocker.

[0032] ③ Taking the maximum difference in the average open area of the fins during backward paddling and forward paddling in the water as the optimization goal, the position of the fixing hole is optimized and calculated to obtain the position of the fixing hole.

[0033] ④ Under the gait of water swimming and land movement, the change law of the fin opening and closing angle in one cycle is as follows: Figure 8 As shown, it is verified that the leg-fin integrated structure and the soft rope control system can achieve the rule that the fins are basically not opened when walking on land, and the fins are opened when paddling backward and closed when paddling forward when swimming in water.

[0034] One end of the flexible cable 21 is fixed to the hole at the end of the flexible cable end fixing piece 13, and is wound around the H-groove bearings d in the three hinged-flexible cable reversing integrated structures for one circle before being led out. The other end is connected to a slider of the flipper frame opening and closing structure.

[0035] like Figure 4As shown, the adaptive fins 6 include: a sliding bionic sole 15, a bionic instep 16, and a pair of fin skeleton rod groups 14 arranged on the bionic sole 15, wherein: the control ends of the pair of fin skeleton rod groups 14 are respectively connected to the bionic instep 16 and form a single-degree-of-freedom four-bar mechanism, and the bionic instep 16 serves as the active component of the four-bar mechanism and is connected to the power unit through a flexible cable 21.

[0036] like Figure 5 and Figure 6 As shown, the servo frame 1, the upper active rocker arm 2, the lower active rocker arm 5, the connecting rod 3 and the execution connecting rod 4 are all hinged by a hinge-flexible cable reversing integrated structure. Figure 9 As shown, it comprises a plug bolt e, a hollow stepped shaft f mounted thereon, two flanged bearings g, two thrust bearings h, and an H-groove bearing d. The larger outer diameter portion of the hollow stepped shaft mates with the H-groove bearing used for winding the flexible cable, while the smaller outer diameter portions on either side of the hollow stepped shaft mate with the ends of the connecting rod of the preceding stage. The ends of the hollow stepped shaft abut against the two thrust bearings, and the other ends of the two thrust bearings abut against the ends of the connecting rod of the following stage. Two flanged bearings fit into the two reamed holes at the end of the connecting rod of the following stage.

[0037] After being extended from the bionic instep 16, the cable 21 is wound around the H-groove bearings in each of the three hinged-cable reversing structures for a complete loop before being extended further. This cable winding method ensures that the cable length between the first joint a and the second joint b, as well as the cable length between the second joint b and the third joint c, remains constant. Therefore, the sum of the distance between the third joint c and the fixed point on the cable end fixture, and the distance between the first joint a and the bionic instep 16, remains constant.

[0038] The flipper skeleton rod set 14 includes two rods cut from the substrate.

[0039] The sliding setting is realized by the guide rail 17 provided on the execution link 4 , that is, the bionic instep 16 and the bionic sole 15 are both provided on the guide rail 17 .

[0040] The bionic instep 16 is preferably further connected to the end of the actuator link 4 via an elastic rope 23 to achieve elastic reset, so that the flipper structure always remains closed under normal circumstances.

[0041] The four-bar mechanism is provided with a flipper membrane 22, which has three fixing points on each side of its symmetry line, namely the threaded hole left at the upper end of the bionic foot 15, the flipper membrane fixing hole 20, and the inner circular groove at the upper end of the elastic rope fixing hole.

[0042] The fixing method of the inner groove is to use a thin rope to penetrate the fin membrane and then tie it together, and the other two places are to use screws to connect after punching holes on the fin membrane. In this way, the fin membrane of the vulnerable part can be easily replaced.

[0043] The flipper membrane 22 is preferably a film made of materials such as PVC and FEP.

[0044] like Figure 6 As shown, L1 is the distance between the third joint c and the fixed point on the flexible cable end fixing part, L2 is the distance between the first joint a and the bionic instep 16, and θ1 is the angle between the upper active part and the horizontal plane. The side lengths of ab and bc are both fixed, while L1 will increase with the increase of the swing angle θ1, causing the L2 section of the flexible cable to be reduced. This device works in the following way: the bionic instep 16 is moved toward the bionic sole 15 through the flexible cable, causing the fin skeleton to automatically open. When the swing angle θ1 decreases, the bionic instep 16 will automatically rebound, causing the fin skeleton to retract. Thus, the movement of the upper active rocker arm 1 simultaneously realizes the control of the two-degree-of-freedom five-link leg mechanism and the control of the opening and closing of the fins. The position of the flexible cable end is determined through joint calculation with the gait, so that when swimming in the water, the fins automatically open when the legs paddle backward, and automatically close when paddling forward. This realizes the adaptive opening and closing of the fins and avoids structural and waterproofing-related problems caused by the additional arrangement of motors and wiring at the foot end.

[0045] like Figure 7 The figure shows the entire process of the device swimming in water: a schematic diagram of the leg structure and flipper status during a working cycle. From left to right, the flippers automatically open when the legs paddle backward and close when paddling forward during a working cycle. The difference in force between the entire leg and flipper structure and the water during this process creates a net forward thrust in the water. When walking on land, due to the Figure 8 The θ1 in the figure does not change much, and the flipper skeleton basically does not move. That is, when walking on the road, the flipper structure will remain normally closed and will not interfere with walking on the road.

[0046] Compared with the existing technology, the present invention solves the problem of underwater movement from a bionic perspective. Taking into account the feasibility and rationality of the duck web paddling itself in the four-legged application, the movement trajectory of the duck web paddling is studied, and the gait rules in the water are summarized; using soft ropes and elastic ropes for rebound, the geometric length relationship is applied to the opening and closing of the webs, and the automatic opening and closing of the webs when the servo controls the movement of the two rods of the legs is realized, reducing the input power requirement; a variety of bearing combination designs are designed at the joint hinge structure: with plug bolts running through, H-slot bearings are placed between the sleeves, and thrust and flange bearings are used on both sides to ensure the mobility and reliability of the joint.

[0047] The above-mentioned specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principles and purpose of the present invention. The scope of protection of the present invention shall be based on the claims and shall not be limited by the above-mentioned specific implementation. All implementation schemes within its scope shall be subject to the constraints of the present invention.

Claims

1. A bionic amphibious robot based on a duck web structure, characterized in that: include: A fuselage portion and at least one pair of bionic feet respectively disposed on the exterior thereof, each bionic foot comprising: a servo frame, a power unit disposed thereon, an upper active rocker arm, a lower active rocker arm, and an actuator link respectively connected to the upper active rocker arm and the lower active rocker arm, wherein the upper active rocker arm is connected to one end of the actuator link via a connecting rod, and the lower active rocker arm is connected to the middle portion of the actuator link, thereby forming a five-bar linkage with two degrees of freedom; an adaptive flipper is provided at the other end of the actuator link; the power unit is respectively connected to the upper active rocker arm, the lower active rocker arm, and the adaptive flipper arm via flexible cables; the servo frame, the upper active rocker arm, the lower active rocker arm, the connecting rod, and the actuator link are all articulated via an integrated hinge-flexible cable reversing structure; The hinged-cable reversing integrated structure includes: a plug bolt and a hollow stepped shaft, two flange bearings, two thrust bearings and an H-groove bearing arranged thereon, wherein: the part with a larger outer diameter in the center of the hollow stepped shaft cooperates with the H-groove bearing used for winding the flexible cable, and the parts with smaller outer diameters on both sides cooperate with the ends of the previous stage connecting rod. The inner holes of the hollow stepped shaft, thrust bearings and flange bearings are concentrically fitted on the plug bolt and tightened by the plug bolt. The two ends of the hollow stepped shaft are respectively close to the two thrust bearings, and the other ends of the two thrust bearings are close to the end of the connecting rod of the next stage. Two flange bearings are respectively fitted in the two reamed holes at the end of the connecting rod of the next stage.

2. The bionic amphibious robot based on the duck web structure according to claim 1 is characterized in that: The power unit includes: a steering gear fixing plate, first and second waterproof steering gears arranged thereon, and a lateral swing steering gear, wherein: one end of the steering gear fixing plate is connected to a sliding bearing on the steering gear frame, and the other end is connected to the lateral swing steering gear. The rotational output of the lateral swing steering gear drives the entire steering gear frame to rotate along the axis of the sliding bearing, thereby achieving lateral swinging of the overall leg structure and switching between a land walking form and a stable swimming posture in water. The first waterproof steering gear and the second waterproof steering gear serve as drivers of the five-bar linkage mechanism, and are respectively connected to the upper active rocker arm and the lower active rocker arm via flexible cables and a steering wheel, thereby controlling the movement of the bionic foot and driving the adaptive control of the adaptive flipper.

3. The bionic amphibious robot based on the duck web structure according to claim 1 is characterized in that: The adaptive flippers include: a sliding bionic sole, a bionic instep, and a pair of flipper skeleton rod groups arranged on the bionic sole, wherein: the control ends of the pair of flipper skeleton rod groups are respectively connected to the bionic instep to form a single-degree-of-freedom four-bar mechanism, and the bionic instep serves as the active component of the four-bar mechanism and is connected to the power unit through a flexible cable.

4. The bionic amphibious robot based on the duck web structure according to claim 1 is characterized in that: After the flexible cable is led out from the bionic instep, it is wound around the H-groove bearings in the three hinged-flexible cable reversing integrated structures for one circle before being led out again; through this flexible cable winding method, the flexible cable length between the first joint and the second joint and the flexible cable length between the second joint and the third joint are guaranteed to remain unchanged, and the sum of the distance between the third joint and the fixed point on the flexible cable end fixing piece and the distance between the first joint and the bionic instep will be a constant value.

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