A seal-like robot capable of two tail motion modes

Abstract

The application discloses a seal-imitating robot with two tail movement modes and belongs to the technical field of underwater navigation equipment. The robot comprises a front body assembly, a rear drive assembly and a flexible outer skin. The front body assembly comprises a head, a control cabin and a seal-imitating front fin, and the rear drive assembly is connected to the rear part of the front body and is sequentially connected by a seal-imitating lumbar unit, a pelvic unit, a lower limb bone unit and a tail fin unit. The lumbar unit comprises a bionic segment structure for swing through bending and a lumbar driving device; the lower limb bone unit comprises tibias arranged on the two sides of the pelvis and tibia driving devices for driving the tibias on the same side to swing; the tail fin unit is composed of a fin root bone, tail toes and a tail fin driving device, a plurality of tail toes form a fan-shaped support, and the tail fin driving device controls the opening and closing of the fan-shaped support and the swing of the fin root bone. The seal-imitating robot has the advantages of compact design, efficient, compliant and stable movement characteristics and good environmental adaptability, and has excellent maneuverability and continuous operation capacity in various underwater tasks.

Description

Technical Field

[0001] The invention belongs to the technical field of underwater navigation equipment, and in particular relates to a seal-like robot capable of realizing two tail movement modes. Background Art

[0002] Traditional underwater vehicles rely primarily on controlling their buoyancy and the position of their center of gravity to achieve basic functions such as surfacing, diving, and steering. They also use propellers and other propulsion devices to provide forward propulsion, resulting in high propulsion speeds. However, due to their rigid mechanical structures, these vehicles are not well adapted to complex marine environments. For example, while traditional propeller propulsion systems can generate significant propulsion force, they are also accompanied by significant noise, which not only affects the vehicle's stealthiness but may also interfere with the normal activities of marine life, limiting their application in sensitive tasks such as ocean monitoring and ecological protection.

[0003] In recent years, biomimetic underwater robots (AUVs), a cutting-edge area of ​​underwater robotics research, have garnered widespread attention. Research in this field aims to combine traditional mechanical structures with the motion characteristics of marine organisms to design robots that more closely resemble natural organisms, exhibiting characteristics such as pliability, flexibility, and low noise, as well as enhanced stealth and environmental adaptability. By mimicking the locomotion mechanisms of marine organisms, AUVs can more naturally integrate into the marine environment and are particularly well-suited for missions requiring high stealth, such as exploration and patrolling. Among many biomimetic models, seals have attracted considerable attention due to their exceptional maneuverability and propulsion efficiency. As pinniped mammals, seals generate propulsion through the rhythmic oscillation of their tails, resulting in high swimming efficiency and hydrodynamic performance. Furthermore, seals can maintain balance and stability by adjusting the movement of their caudal fins, enabling them to demonstrate agile and stable locomotion in complex waters. This coordinated and agile tail motion provides valuable insights into biomimetic design and is expected to enhance the maneuverability and environmental adaptability of AUVs, enabling them to demonstrate low noise, stealth, and efficiency in noise-sensitive underwater environments.

[0004] Currently, seal-inspired biomimetic designs in the field of underwater robotics are still in their early stages of exploration. Existing research has yet to achieve a high degree of simulation of a seal's propulsion system, exposing multiple technical deficiencies and limitations. First, the bionic seal's joint movements lack significant freedom and coordination, failing to achieve the fine-tuned control of a real seal. A seal's tail joint is highly flexible, achieving smooth and efficient propulsion through fine-tuning the bending and swinging of each joint. However, current bionic designs often employ simplified joint motion patterns, failing to truly simulate a seal's natural movement. Furthermore, bionic seals exhibit limited flexibility when moving underwater. Real seals exhibit extremely high compliance, and their drive structures can dynamically adjust to varying water flow conditions, achieving stable propulsion and precise steering. However, existing bionic designs are often limited by rigid structures or single transmission mechanisms, resulting in stiff movements and a lack of natural, smooth motion curves, making them difficult to adapt to complex underwater environments. Furthermore, bionic seals face significant challenges in the transmission design of their drive structures. Seals rely on flexible muscle tissue for propulsion, while bionic seals generally use traditional mechanical transmission structures such as motors and gears. These rigid components have limitations in mimicking the streamlined movement of living organisms, often resulting in stiff and uncoordinated driving movements. At the same time, mechanical transmission devices also lead to increased noise and excessive energy consumption, reducing the stealth and endurance of bionic robots. Finally, the environmental adaptability of existing bionic designs needs to be improved. The unique propulsion method of seals enables them to swim flexibly in environments with turbulent water or full of obstacles, but the movement mode of existing bionic robots is mostly single forward propulsion, which makes it difficult to adapt to the ever-changing underwater environment, resulting in insufficient maneuverability. Overall, the current bionic seal design has not achieved ideal results in terms of joint movement, flexibility, transmission structure and environmental adaptability. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention provides a seal-like robot that can realize two tail movement modes, which solves the problems of insufficient freedom and coordination of joint movements, poor movement flexibility, rigid transmission structure, high energy consumption and noise, and poor environmental adaptability.

[0006] The application is realized as follows: a seal-imitating robot capable of realizing two tail movement modes, characterized in that: comprising a front body assembly, a rear drive assembly and a flexible outer skin arranged on the outer surface; the front body assembly comprises a head, a control cabin and a seal-imitating front fin mounted on the control cabin, the rear drive assembly is connected to the rear of the front body assembly, and the rear drive assembly comprises, in sequence from front to rear, a seal-imitating lumbar unit, a seal-imitating pelvic unit, a femur-tibia-fibula unit and a seal-imitating tail fin unit; the seal-imitating lumbar unit comprises a bionic segment structure capable of swinging through bending and a lumbar driving device for driving the seal-imitating lumbar unit to swing, the femur-tibia-fibula unit comprises tibias arranged on both sides of the seal-imitating pelvic unit and tibia driving devices for driving the tibias to swing to the same side, and the seal-imitating tail fin unit comprises a fin root bone, tail toes and a tail fin driving device, N tail toes form a fan-shaped support, and the tail fin driving device drives the fan-shaped support to open and close and drives the fin root bone to swing.

[0007] In the above technical solution, preferably, the seal-imitating tail fin unit comprises a clamp plate, a tail fin connecting rod, a driving sliding pin, a tail fin pull rod, a tail fin driving rod, a driving sliding block and a crank connecting rod; the tail toes comprise a middle tail toe and inner and outer tail toes symmetrically arranged on both sides of the middle tail toe, the inner and outer tail toes are mounted on the clamp plate through pivot shafts, and the middle tail toe is fixed to the clamp plate; the inner tail toe is mounted with a sliding pin shaft sliding along the inner tail toe, the middle and outer tail toes are provided with fixed pin shafts, the middle tail toe and the inner tail toe and the inner tail toe and the outer tail toe are connected through the tail fin connecting rod, and two ends of the tail fin connecting rod are connected with the sliding pin shaft and the fixed pin shaft respectively; the driving sliding pin is mounted on the middle tail toe and moves along the length direction of the middle tail toe, the middle tail toe and the inner tail toe are connected through the tail fin pull rod, one end of the tail fin pull rod is connected with the driving sliding pin, and the other end of the tail fin pull rod is connected with the inner tail toe through a pin shaft; the driving sliding block is mounted on the fin root bone in a straight line moving mode, an output shaft of the tail fin driving device is connected with the driving sliding block through the crank connecting rod, the tail fin driving device drives the driving sliding block to move and drives the fin root bone to swing through the driving sliding block, and the driving sliding block and the driving sliding pin are connected through the tail fin driving rod.

[0008] In the above technical solution, preferably, the rear end of the middle tail toe extends to the rear of the clamp plate to form the fin root bone, the rear end of the fin root bone is provided with a tail fin swing shaft, and the tail fin driving device drives the fin root bone to swing with the tail fin swing shaft as the axis; the front part of the middle tail toe is provided with a sliding groove, and the driving sliding pin is fitted through the sliding groove; the fin root bone is provided with a sliding groove, and the driving sliding block is fitted through the sliding groove; and the inner tail toe is provided with a sliding groove, and the sliding pin shaft is mounted through the sliding groove.

[0009] In the technical scheme, preferably, the bionic segment structure comprises segment vertebrae connected in sequence in the axial direction, two adjacent segment vertebrae are connected by a vertebra pin shaft and form a bionic segment structure capable of bending to left and right sides, the segment vertebrae are connected in series in the axial direction by an elastic cylindrical rod, the elastic cylindrical rod applies an elastic force to the bionic segment structure to restore the bionic segment structure to an axial state, and the lumbar driving device is connected to the rear end of the bionic segment structure by a pull wire and drives the bionic segment structure to bend by tension.

[0010] In the technical scheme, preferably, the segment vertebrae comprise a cone, a cone bone and a skin support bone, the cones of two adjacent segment vertebrae are connected by a vertebra pin shaft, the cone bone is fixed to the cone and forms a radial support, and the skin support bone is arranged at the periphery of the cone bone and forms an annular structure for supporting the flexible outer skin.

[0011] In the technical scheme, preferably, the bionic segment structure comprises segment vertebrae connected in sequence in the axial direction, two adjacent segment vertebrae are connected by a vertebra pin shaft and form a bionic segment structure capable of bending to left and right sides, the segment vertebrae are connected in series in the axial direction by an elastic cylindrical rod, the elastic cylindrical rod applies an elastic force to the bionic segment structure to restore the bionic segment structure to an axial state, and the lumbar driving device is connected to the rear end of the bionic segment structure by a pull wire and drives the bionic segment structure to bend by tension.

[0012] In the technical scheme, preferably, the cone bone of the segment vertebrae is provided with a guide pulley, and the pull wire is guided through the guide pulleys of the segment vertebrae and connected to the rear end plate.

[0013] In the technical scheme, preferably, the front end plate is provided with a lumbar driving support, the lumbar driving support is provided with an axially extending tension slide rail, the tension slide rail is provided with a lumbar driving slide block moving along the tension slide rail and an adjusting bolt for fixing the position of the lumbar driving slide block, the lumbar driving device is arranged on the lumbar driving slide block, and the output shaft of the lumbar driving device is connected to the pull wire.

[0014] In the technical scheme, preferably, the femur-tibia-fibula unit comprises a lower limb support fixed to the pelvic unit, the root of the tibia is connected to the lower limb support by a first lower limb connecting rod, the rear part of the tibia is connected to the lower limb support by a second lower limb connecting rod, the output shaft of the tibia driving device is provided with a lower limb driving crank, and the second lower limb connecting rod and the lower limb driving crank are connected by a third lower limb connecting rod.

[0015] In the technical scheme, preferably, the second lower limb connecting rod, the third lower limb connecting rod, the lower limb driving crank and the lower limb support form a parallelogram mechanism.

[0016] The application provides a seal robot capable of realizing two tail movement modes. Through in-depth research on the skeletal structure and joint characteristics of a seal tail, a tail movement unit structure of the seal robot is mapped, so that the seal robot has multiple superior performances. First, the tail movement unit of the seal robot adopts a simple structure and a short transmission chain, which greatly reduces the complexity of the movement structure, thereby reducing the difficulty of control and maintenance, and improving the reliability and adaptability of the overall device. The tail movement of the seal robot can highly imitate the flexible action of the seal tail, so that the seal robot moves more naturally in water, and is close to the streamlined movement mode of marine organisms. The flexibility ensures the smoothness and accuracy of the seal robot when performing steering, stabilizing the body and other operations, and significantly improves the environmental adaptability.

[0017] The tail movement unit of the seal robot adopts four steering gears to realize two tail fin swing modes: one is a propulsion mode of tail fin swing in the same direction, and the other is a stabilizing mode of tail fin swing in opposite directions. The tail fin swing mode in the same direction generates stable propulsion, so that the seal robot maintains stable and efficient movement performance when moving forward; the tail fin swing mode in opposite directions provides excellent stabilizing effect, helping the seal robot to maintain the balance of the body, so that the seal robot has stronger anti-interference ability in a complex water flow environment. The dual-mode design can be switched freely in different underwater environments, meets the demand of the seal robot for speed and stability, and is the key to realizing high flexibility.

[0018] In addition, the application further optimizes the reliability and efficiency of the movement in the design of the seal lumbar unit, especially adopts a segmented skin and a guide pulley structure. This design significantly reduces the friction between the internal structure and the external skin, and the friction between the steel wire cable and the internal structure, thereby avoiding energy loss and mechanism wear caused by friction resistance, and ensuring that the seal robot can maintain efficient operation for a long time at a lower energy consumption. At the same time, a tensioning device is arranged to effectively pre-tighten the steel wire cable, so that the transmission chain always maintains appropriate tension, which not only prolongs the service life of the transmission device, but also improves the accuracy and efficiency of mechanical transmission. In summary, the seal robot has compact design structure, efficient, flexible and stable movement characteristics, and good environmental adaptability, and can provide excellent maneuverability and long-term operation performance in various underwater tasks.

[0019] In addition to the above advantages, the design can further improve the performance and application potential of the seal robot:

[0020] The seal robot adopts flexible tail fin movement and simplified transmission chain design, which avoids the strong noise caused by the high-speed rotation of the traditional propeller in water. This low-noise feature makes the seal robot more concealed in the underwater environment, especially suitable for underwater detection, ecological protection and military reconnaissance tasks, which can significantly reduce the interference to marine organisms and improve the concealment.

[0021] Due to the reduction of complex transmission chains and redundant mechanical components in this design, the energy consumption required by the robot when performing movements is reduced. At the same time, the segmented skin and guide pulley structure further reduces friction, improves overall transmission efficiency, and can reduce power consumption while maintaining high-performance movement, thereby prolonging the endurance time. This is particularly important for long-term underwater cruising tasks, helping to improve the sustained working capacity of the robot.

[0022] The tail movement unit, lumbar unit, etc. of the design have modular characteristics, which are convenient for maintenance and replacement. Modular design not only improves the independence and flexibility of each component of the robot, but also provides convenient operation space for subsequent performance upgrade and function expansion, facilitating corresponding modification or upgrade for different task requirements.

[0023] Since the four servos can be independently controlled, the robot can achieve more precise attitude adjustment and control of movement modes. By finely adjusting the angle and speed of each servo, complex tail fin movement patterns can be achieved, thereby improving the precise control ability of the robot in movements such as turning, accelerating, and decelerating. This feature enables the robot to flexibly respond to complex dynamic environments when performing tasks in water, further improving task efficiency.

[0024] Based on this bionic design, future machine learning algorithms can be combined to adjust and optimize the movement patterns of the tail fins in real time to adapt to different water flows and environments. By collecting and analyzing movement data in various environments, the robot can gradually optimize its own movement patterns, further improving stability, energy efficiency, and operational flexibility, and developing towards intelligentization.

[0025] In summary, this sealion-like robot not only has high simplicity and flexibility in structural design, but also exhibits many advantages in low noise, energy saving, impact resistance, modularity, fine control, and adaptive learning, giving it a wide application prospect in underwater exploration, ecological monitoring, scientific research, and covert operations, etc. application field. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a structural schematic diagram of the present invention;

[0027] Figure 2 is a segmented flexible outer skin schematic diagram of the present invention;

[0028] Figure 3 is an internal structure schematic diagram of the present invention;

[0029] Figure 4 is an internal structure schematic diagram of the sealion-like lumbar unit of the present invention;

[0030] Figure 5is a wire winding diagram of a lumbar vertebra unit of the present application;

[0031] Figure 6 is a schematic diagram of the internal structure of a vertebra unit of the present application;

[0032] Figure 7 is a schematic diagram of the internal structure of a femur-tibia fibula unit of the present application;

[0033] Figure 8 is a schematic diagram of the internal structure of a pelvic unit of the present application;

[0034] Figure 9 is a schematic diagram of the internal structure of a right tail fin of the present application;

[0035] Figure 10 is a top view of a left tail fin of the present application. DETAILED DESCRIPTION

[0036] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0037] In order to solve the problems of insufficient freedom and coordination of joint movement, poor motion compliance, rigid transmission structure, high energy consumption and noise, and poor environmental adaptability, the present application provides a seal robot capable of realizing two tail movement modes. The seal robot has a compact design, high efficiency, soft and stable motion characteristics, and good environmental adaptability, and can provide excellent maneuverability and persistent operation performance in various underwater tasks. In order to further illustrate the structure of the present application, the detailed description is as follows in combination with the drawings:

[0038] Please refer to Figure 1 , Figure 2 and Figure 3 , a seal robot capable of realizing two tail movement modes, comprising a forebody assembly, an aft drive assembly and a flexible outer skin arranged on the outer surface. The forebody assembly is the non-powered front part of the seal underwater vehicle, and the forebody assembly comprises a head 1, a control cabin 2 and a seal forefin 3 mounted on the control cabin. The flexible outer skin is wrapped outside the seal robot, so that the robot obtains a good hydrodynamic shape during movement. The aft drive assembly is connected to the rear part of the forebody assembly, and the aft drive assembly comprises a seal lumbar vertebra unit 4, a seal pelvic unit 5, a femur-tibia fibula unit 6 and a seal tail fin unit 7 connected in sequence from front to back. The seal forefin, the femur-tibia fibula unit and the seal tail fin unit are symmetrically distributed on both sides of the robot. Here and below, "front, rear, left and right" are all referred to the advancing direction of the device.

[0039] Specifically, the head is a rigid, 3D-printed conical structure with a favorable hydrodynamic shape, which reduces water resistance. The end of the head is connected to the front of the control cabin via countersunk bolts. The control cabin, which resembles a cylindrical rotating body, houses a power supply, control panel, and other components to control the swinging motion of the seal-like lumbar unit, femoral-tibia-fibula unit, and seal-like caudal fin unit. The end of the control cabin is connected to the cylindrical lumbar unit drive cabin located at the front of the seal-like lumbar unit. The seal-like front flipper has the same profile as a seal's front flipper and is bolted to the side of the control cabin. It helps the robot maintain balance during movement and enhances its stability.

[0040] like Figure 4 、 Figure 5 and Figure 6 The seal-like lumbar vertebra unit includes a bionic segment structure that realizes swinging by bending and a lumbar drive device that drives the seal-like lumbar vertebra unit to swing. The bionic segment structure includes segment vertebrae that are connected axially in sequence. Two adjacent segment vertebrae are connected by vertebral pins to form a bionic segment structure that can bend to the left and right sides. The segment vertebrae are connected in series with axial elastic cylindrical rods. The elastic cylindrical rods exert elastic force on the bionic segment structure to restore it to the axial state. The lumbar drive device is connected to the rear end of the seal-like lumbar vertebra unit through a pull wire and drives the bionic segment structure to bend by tension. The segment vertebra includes a cone, a cone bone, a skin support bone, a front end plate, a rear end plate and a guide pulley. The cones of adjacent segment vertebrae are connected by vertebral pins. The cone bone is fixed to the cone and forms a radial support. The skin support bone is arranged on the periphery of the cone bone and forms an annular structure that supports the flexible outer skin. The segmental vertebrae are located between the front and rear plates. The cones of the segmental vertebrae are disc-shaped, and elastic cylindrical rods are symmetrically positioned above and below the connected cones, extending through and connecting the cones. The front end of the elastic cylindrical rods connects to the front plate, while the rear end of the rear plate connects to the rear plate. The pull wires pass through the segmental vertebrae and connect to the rear plate. The pull wires are guided through the guide pulleys of the segmental vertebrae and connected to the rear plate. The lumbar vertebrae are divided into segments, and the internal skeleton and skin of each stage are integrated. The segments do not contact each other during movement, reducing friction compared to a single skin covering the entire internal skeleton. The guide pulley design also reduces friction on the wire pull wires during movement, improving efficiency.

[0041] The front end plate is mounted on a lumbar drive bracket, which is fitted with an axially extending tensioning rail. The tensioning rail is mounted on a lumbar drive slide that moves along the rail, along with an adjustment bolt that secures the slide in place. The lumbar drive unit is mounted on the slide, and the output shaft of the lumbar drive unit is connected to a cable. A cable tensioning device within the lumbar unit ensures that the cable remains taut after being secured, preventing backlash in the lumbar unit motor.

[0042] Specifically, the seal-like lumbar unit is the first motion joint of this device. The lumbar unit drive cabin 4-1 is located at the front of this part and is connected to the end of the control cabin by countersunk bolts. The lumbar unit drive cabin has the shape of a cylindrical rotating body, and its exterior is wrapped with a flexible skin. The interior of the lumbar unit drive cabin is used to place the lumbar drive device that controls the swing of the seal-like lumbar unit, as well as the tensioning assembly consisting of the lumbar drive bracket and the tensioning slide rail. The lumbar drive device is the first servo 4-2. The lumbar unit drive cabin is connected to the front end plate by bolts. The lumbar drive bracket 4-3 is connected to the front mounting plate by bolts. The tensioning slide rail 4-4 is installed on the lumbar drive bracket. The lumbar drive slide 4-5 is mounted on the tensioning slide rail and the two form an axial linear motion pair. The first servo is installed on the lumbar drive slide, so that the first servo and its components can move relative to the tensioning slide rail. The seal-like lumbar vertebrae unit is driven by a cable. In this embodiment, the cable is a steel wire 4-6. The cable's end is secured to a reel 4-7 on the output shaft of the first servo. It is wound multiple times and then drawn out at both ends. The wire passes through the front plate 4-8, then sequentially winds around the guide pulleys of the segmental vertebrae of the seal-like lumbar vertebrae unit. After exiting the last guide pulley, it is secured to the cable hole in the rear plate 4-15. An adjustment bolt 4-9 is threadedly connected to the lumbar drive bracket. Once the cable is installed, the adjustment bolt can be used to move the first servo forward relative to the tensioning rail, thereby tautening the cable. The seal-like lumbar vertebrae unit is composed of four connected segmental vertebrae. Each segmental vertebrae comprises a cone 4-10, a cone bone 4-11, a skin support bone 4-12, a guide pulley 4-13, and an elastic cylindrical rod 4-14. The cones are connected by pins to connect the segmental vertebrae. The vertebrae are connected to the skin support bones using bolts. Elastic cylindrical rods are placed on the upper and lower sides of the seal-like lumbar vertebrae unit, with their ends inserted into cylindrical grooves on the front and rear panels, respectively. The two elastic cylindrical rods penetrate each vertebral segment.

[0043] The swinging principle of the entire seal-like lumbar vertebrae unit is that when the first servo drives the wire drum to rotate, the length of the steel wire pull at both ends of the seal-like lumbar vertebrae unit changes, causing the seal-like lumbar vertebrae unit to generate a deflection torque. This torque will drive the elastic cylindrical rod to undergo continuous deformation, and then drive the rotation of each segment of the vertebrae unit to form a bending deflection in the overall axial direction, completing the swinging action in sequence.

[0044] The flexible skin on the outside of the seal-like lumbar vertebrae unit is segmented, with each segment directly connected to the skin support bone. The shapes of adjacent segments of the flexible skin are concentric arcs with different radii. This design ensures that the segmented flexible skins will not contact each other when the vertebral units of the seal-like lumbar vertebrae unit move relative to each other, thereby reducing the friction during the movement of this part of the structure and improving mechanical efficiency.

[0045] like Figure 7The seahorse pelvis unit 5 is composed of an upper arc plate 5-1 and a lower arc plate 5-2 fixed on the rear end plate. The rear end plate is provided with mounting holes for connecting with the femur-tibia-fibula unit. The upper arc plate and the lower arc plate are bolted on the rear end plate. The upper and lower arc plates keep the seahorse pelvis unit in good hydrodynamic shape and accommodate the driving part of the seahorse femur-tibia-fibula unit inside.

[0046] As shown in FIG. 1, the seahorse pelvis unit 5 is connected with the seahorse femur-tibia-fibula unit 6. Figure 8 The seahorse femur-tibia-fibula unit 6 includes tibias 6-1 on both sides of the seahorse pelvis unit and tibia driving devices for driving the tibias to swing to the same side. The seahorse femur-tibia-fibula unit includes a lower limb support. The roots of the tibias are connected with the lower limb support through first lower limb connecting rods. The rear parts of the tibias are connected with the lower limb support through second lower limb connecting rods. The output shafts of the tibia driving devices are installed with lower limb driving cranks. The second lower limb connecting rods are connected with the lower limb driving cranks through third lower limb connecting rods. The second lower limb connecting rods, the third lower limb connecting rods, the lower limb driving cranks and the lower limb support form a parallelogram mechanism.

[0047] Specifically, the seahorse femur-tibia-fibula unit is the second movement unit of the device. Two planar six-bar mechanisms are connected in parallel to form the movement mechanism of the seahorse femur-tibia-fibula unit, and are symmetrically distributed on both sides of the seahorse pelvis unit. Specifically, the tibias on both sides are installed on the lower limb support through the connecting rod mechanism. In this embodiment, the lower limb support is the rear end plate of the seahorse lumbar unit. Taking the right tibia as an example, the first lower limb connecting rod 6-2, the tibia, the second lower limb connecting rod 6-3, the third lower limb connecting rod 6-4, the lower limb driving crank 6-5 and the rear end plate constitute the right planar six-bar mechanism. The two ends of the first lower limb connecting rod, the second lower limb connecting rod and the third lower limb connecting rod are hinged to the corresponding components through a pin shaft to form a planar connecting rod structure. The rear end plate serves as the rack part of the two planar six-bar mechanisms on the left and right sides. By designing the length of each rod, the second lower limb connecting rod, the third lower limb connecting rod, the lower limb driving crank and the lower limb support form a parallelogram mechanism. The included angle of the lower limb driving cranks on the left and right sides is fixed. In this embodiment, the lower limb driving cranks of the connecting rod mechanisms on the left and right sides are the same rocker parts. When the lower limb driving cranks swing, the tibias on both sides move synchronously and can move to opposite limit positions. The tibia rudder support is connected with the rear end plate through bolts. The tibia driving device is a second rudder 6-6. The second rudder is fixed on the tibia rudder support. The output shaft of the second rudder drives the rocker part to swing, thereby driving the tibias on both sides of the seahorse femur-tibia-fibula unit to move. Symmetrical Z-shaped supports 6-7 are also provided on both sides for installing and supporting the second lower limb connecting rods on the left and right sides. The movement components are connected through bolts, nuts and shaft sleeves to form rotary pairs. Except for the tibias, all the movement components are arranged in the shell space formed by the upper arc plate and the lower arc plate of the seahorse pelvis unit. The mechanism maps the femur and tibia-fibula of a real seal. When the mechanism is designed, the movement angles of the components corresponding to the femur and tibia-fibula are also corresponding to the rotation limit angles of the biological anatomical bones, which is conducive to realizing the movement similar to that of a real seal.

[0048] The seahorse tail fin unit is the third moving unit of the robot, which includes a left tail fin and a right tail fin. The two tail fins are symmetrically distributed on the left and right sides of the tail of the robot and form rotating pairs with the left and right shanks of the femur-tibia-fibula unit. Since the two tail fins have the same structure, the right tail fin of the seahorse tail fin unit will be taken as an example to describe its composition and movement principle.

[0049] Taking the right tail fin as an example, as shown in Figure 9 and Figure 10 , the right tail fin includes a fin root bone 7-1, tail toes, and a tail fin driving device. The N tail toes form a fan-shaped support, and the tail fin driving device drives the opening and closing of the fan-shaped support and the swing of the fin root bone. In this embodiment, the seahorse tail fin unit includes a clamp plate 7-2, a tail fin connecting rod 7-3, a driving sliding pin 7-4, a tail fin pull rod 7-5, a tail fin driving rod 7-6, a driving sliding block 7-7, and a crank connecting rod 7-8.

[0050] The tail toes include a middle tail toe 7-9 and an inner side tail toe 7-10 and an outer side tail toe 7-11 symmetrically located on both sides of the middle tail toe. The inner side tail toe and the outer side tail toe are installed on the clamp plate through a pin shaft, and the middle tail toe is fixed to the clamp plate. The inner side tail toe is installed with a sliding pin shaft 7-12 sliding along the inner side tail toe. The middle tail toe and the outer side tail toe are provided with a fixed pin shaft 7-13. The middle tail toe and the inner side tail toe, and the inner side tail toe and the outer side tail toe are connected through the tail fin connecting rod. The two ends of the tail fin connecting rod are connected with the sliding pin shaft and the fixed pin shaft, respectively. The driving sliding pin is installed on the middle tail toe and moves along the length direction of the middle tail toe. The middle tail toe and the inner side tail toe are connected through the tail fin pull rod. One end of the tail fin pull rod is connected with the driving sliding pin, and the other end of the tail fin pull rod is connected with the inner side tail toe through a pin shaft. The driving sliding block is installed on the fin root bone in a straight line moving manner. The output shaft of the tail fin driving device is connected with the driving sliding block through the crank connecting rod. The tail fin driving device drives the movement of the driving sliding block and drives the swing of the fin root bone through the driving sliding block. The driving sliding block and the driving sliding pin are connected through the tail fin driving rod. Further, the rear end of the middle tail toe extends to the rear of the clamp plate to form the fin root bone. The rear end of the fin root bone is provided with a tail fin swing shaft. The tail fin driving device drives the fin root bone to swing around the tail fin swing shaft. The front part of the middle tail toe is provided with a sliding groove, and the driving sliding pin is fitted through the sliding groove. The fin root bone is provided with a sliding groove, and the driving sliding block is fitted through the sliding groove. The inner side tail toe is provided with a sliding groove, and the sliding pin shaft is installed through the sliding groove.

[0051] The right tail fin of the aforementioned structure can achieve periodic oscillation, accompanied by the expansion and contraction of the fin surface. Five tail toes and a cleat form the main structure of the tail fin. The middle tail toe is fixed to the cleat via a countersunk bolt. The two outer and inner tail toes form a revolute pair with the cleat, allowing these four tail toes to oscillate about a pin connected to the cleat. The fin root forms a revolute pair with the tail fin support via bolts, nuts, and sleeves. The front end of the middle tail toe extends and is hinged to the tail fin support via a vertical tail fin swing axis. The tail fin drive is a third servo 7-14, fixed to the tail fin support. The tail fin support can be a structural component of the tibia or an independent support fixed to the tibia. The output shaft of the third servo is connected to a crankshaft, which serves as the servo swing arm. The crankshaft is connected to a drive slider in a revolute pair, which is positioned in a slot at the end of the middle tail toe. The crankshaft, middle tail toe, drive slider, and tail fin support form a swing guide mechanism. The third servo drives the crank connecting rod to rotate, thereby causing the middle tail toe and the entire seal-like right tail fin to swing. The middle and inner tail toes have longitudinal slots, with a drive pin and a sliding pin shaft positioned within them. One end of the tail fin connecting rod forms a revolving pair with the sliding pin shaft, while the other end forms a revolving pair with the outer and middle tail toes, respectively, through fixed pin shafts. The inner ends of the tail fin pull rods on either side of the middle tail toe form revolving pairs with the drive pin, while the outer ends form revolving pairs with the inner tail toe through pin shafts. A long connecting rod, the tail fin drive rod, runs between the drive pin and the drive slider. Its ends are welded to the drive pin and the drive slider, forming a single unit called the slider connecting rod. The swing of the crank connecting rod drives the slider connecting rod to move within the middle tail toe, thereby driving the movement of the drive pin, the sliding pin shaft, and the rotation of each connecting rod, achieving the opening and closing of the tail fin surface. The single tail fin in the tail fin unit features a novel biomimetic mechanism, using a single motor to achieve swing and opening / closing motion in two perpendicular planes, mirroring the movements of a real seal's tail fin. Furthermore, the tail fin can achieve both unidirectional and directional swinging, mirroring the movements of a real seal. The previous patent for the seal robot failed to achieve the opposite swinging motion of the tail fins. The robot can steer by controlling the yaw of the lumbar unit, the femoral-tibia-fibula unit (lower limb unit), and the yaw of one tail fin (while the other tail fin remains stationary and in a minimally closed state).

[0052] The specific operation mode of this embodiment

[0053] The bionic prototype of the present invention is a harp seal. The lumbar vertebrae, lower limb bones and tail fin can be regarded as three motion joints respectively. It has two tail motion modes. The first tail motion mode is to generate thrust through the periodic swing of the lumbar vertebrae, lower limb bones and tail fin. This process is accompanied by the opening and closing movement of the tail fin. This is the most important tail motion mode of the seal. In this tail motion mode, the lower limb bones and tail fin on both sides alternately complete the movements of the power stage and the recovery stage. Since the two lower limb bones and the tail fin move symmetrically in the power stage and the recovery stage, the seal's movements in half a motion cycle are now described in detail.

[0054] The movement of the tibia and tail fin on both sides. At the beginning of the power phase, the lumbar spine and lower limb bones are in the right extreme position, the right tail fin is approximately parallel to the seal's body axis and is in a closed state. At this time, the left lower limb is also in the right extreme position, and the left tail fin is approximately coincident with the seal's body axis and is in an open state. At the next moment, the lumbar spine and right tibia swing to the left, the right tail fin quickly opens and dorsiflexes, forming a certain angle with the right tibia, the left tibia swings to the left, the left tail fin adducts and gradually closes. When the lumbar spine and lower limb bones are in the left extreme position, the right tail fin is approximately coincident with the seal's body axis and is in an open state, and the left tail fin is parallel to the seal's body axis and is in a closed state. At this point, the power phase of the right tibia and right tail fin is completed, and the next moment will enter the recovery phase, while the left tibia and left tail fin will enter the power phase. When the tibia and tail fin on both sides alternately complete the power phase and recovery phase, the seal's movement in one cycle is completed.

[0055] In the second tail movement pattern, the lumbar spine and tibia remain stationary, and the seal's tail fins swing in opposite directions. During the power phase, the tail fins swing outward simultaneously and gradually open; during the recovery phase, the tail fins swing inward simultaneously and gradually close.

[0056] The seal-like robot designed by the present invention can realize two tail motion modes and can highly restore the seal's tail motion mode. In the process of realizing the first tail motion mode, the device is described starting from the initial position in the middle position.

[0057] When the first servo rotates counterclockwise a certain angle, the right portion of the cable is wound onto the reel, while the left portion is unwound. The cables on both sides act on the rear plate, creating a rotational torque that bends and deforms the elastic cylindrical rod extending through the vertebrae to the right. This deformation drives the segmental vertebra to its rightmost position. When the second servo rotates counterclockwise a certain angle, the servo's swing arm drives the moving components of the biplanar hexagonal mechanism of the femoral-tibiofibular unit to the right, causing the lower limb bones to reach their rightmost position. The third servo in the right tail fin of the imitation seal tail fin rotates clockwise by a certain angle, so that the right tail fin of the imitation seal tail fin is approximately parallel to the axis of the seal's body and is in a closed state. The third servo in the left tail fin of the imitation seal tail fin rotates clockwise by a certain angle, so that the left tail fin is approximately coincident with the axis of the seal's body and is in an open state. At this time, the right tibia and the right tail fin of the device are in the initial positions of the power stage, and the left tibia and the left tail fin are in the initial positions of the recovery stage. The four driving servos make each unit of the device reach the extreme position at the same time according to the appropriate frequency.

[0058] In the next phase, the first servo rotates clockwise, winding the left portion of the cable onto the reel and the right portion off the reel. The elastic cylindrical rod extending through the vertebral column bends and deforms to the left, causing the segmental vertebra to swing to its left limit position. The second servo rotates clockwise by a certain angle, and the servo's swing arm swings the moving components of the biplane hexagonal mechanism to the left, bringing the limb bone to its left limit position. The third servo on the right caudal fin rotates counterclockwise by a certain angle, causing the right caudal fin to rapidly open and dorsiflex, forming a certain angle with the right tibia. The third servo on the left caudal fin rotates counterclockwise, causing the left caudal fin to adduct and gradually close. At the end of the power phase, the right caudal fin is approximately aligned with the seal's body axis and in an open position, while the left caudal fin is parallel and closed. This completes the power phase for the right tibia and caudal fin. The seal will then enter the recovery phase, while the left tibia and caudal fin will enter the power phase. When the tibia and tail fin on both sides complete the power phase and the recovery phase alternately, the movement of the device in one cycle is completed.

[0059] During the implementation of the second tail motion mode, only the seal tail fin unit is imitated for movement. When the third servo controlling the right tail fin rotates counterclockwise and the third servo controlling the left tail fin rotates clockwise, the left and right tail fins swing outward and gradually open at the same time. This is the recovery stage of the second tail motion mode. When the third servo controlling the right tail fin rotates clockwise and the third servo controlling the left tail fin rotates counterclockwise, the left and right tail fins swing inward and gradually close at the same time. This is the power stage of the second tail motion mode.

[0060] The above merely preferred embodiments of the present application are not used to limit the present application, any modification, equivalent replacement and improvement etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A seal-like robot capable of achieving two tail motion modes, characterized by: The invention comprises a front body assembly, a rear drive assembly and a flexible outer skin provided on the exterior; the front body assembly comprises a head, a control cabin and a seal-like front fin mounted on the control cabin; the rear drive assembly is connected to the rear of the front body assembly; the rear drive assembly comprises a seal-like lumbar unit, a seal-like pelvic unit, a femur-tibia-fibula unit and a seal-like tail fin unit connected in sequence from front to back; the seal-like lumbar unit comprises a bionic segment structure that achieves swing by bending and a lumbar drive device that drives the seal-like lumbar unit to swing; the femur-tibia-fibula unit comprises tibias provided on both sides of the seal-like pelvic unit and a tibial drive device that drives the two tibias to swing to the same side; the seal-like tail fin unit comprises a fin root bone, a tail toe and a tail fin drive device; N tail toes form a fan-shaped surface support; the tail fin drive device drives the fan-shaped surface support to open and close and the fin root bone to swing; The seal-like tail fin unit includes a splint, a tail fin connecting rod, a driving sliding pin, a tail fin pull rod, a tail fin driving rod, a driving slider, and a crank connecting rod; the tail toe includes a middle tail toe and an inner tail toe and an outer tail toe symmetrically located on both sides of the middle tail toe, the inner tail toe and the outer tail toe are installed on the splint through a rotating shaft, and the middle tail toe is fixed to the splint; the inner tail toe is installed with a sliding pin that slides along the inner tail toe, and the middle tail toe and the outer tail toe are provided with a fixed pin, the middle tail toe and the inner tail toe are connected to the inner tail toe and the inner tail toe and the outer tail toe through the tail fin connecting rod, and the two ends of the tail fin connecting rod are respectively connected to the sliding pin. The tail fin drive device is connected to the driving slide pin through the tail fin drive rod, and the driving slide pin is connected to the inner tail toe through the tail fin drive rod. The driving slide pin is installed on the fin root bone in a linear movement manner, and the output shaft of the tail fin drive device is connected to the driving slide pin through a crank connecting rod. The tail fin drive device drives the driving slide pin to move and drives the fin root bone to swing through the driving slide pin. The driving slide pin is connected to the driving slide pin through the tail fin drive rod.

2. The seal-like robot capable of realizing two tail motion modes according to claim 1, characterized in that: The rear end of the middle tail toe extends toward the rear of the splint to form the fin root bone, and the rear end of the fin root bone is provided with a tail fin swing axis, and the tail fin driving device drives the fin root bone to swing with the tail fin swing axis as the axis; the front part of the middle tail toe is provided with a slide groove and the driving sliding pin is equipped with this slide groove, the fin root bone is provided with a slide groove and the driving slider is equipped with this slide groove; the inner tail toe is provided with a slide groove and the sliding pin shaft is installed through this slide groove.

3. The seal-like robot capable of realizing two tail motion modes according to claim 1, characterized in that: The bionic segment structure includes segment vertebrae connected axially in sequence, and two adjacent segment vertebrae are connected by vertebral pins to form a bionic segment structure that can bend to the left and right sides. The segment vertebrae are connected in series with axial elastic cylindrical rods, and the elastic cylindrical rods apply elastic force to the bionic segment structure to restore it to an axial state. The lumbar drive device is connected to the rear end of the seal-like lumbar unit through a pull wire and drives the bionic segment structure to bend through tension.

4. The seal-like robot capable of realizing two tail motion modes according to claim 3, characterized in that: The segmental vertebra includes a cone, a cone bone and a skin support bone. The cones of adjacent segmental vertebrae are connected by a vertebral pin. The cone bone is fixed to the cone and forms a radial support. The skin support bone is arranged on the periphery of the cone bone and forms an annular structure supporting the flexible outer skin.

5. The seal-like robot capable of realizing two tail motion modes according to claim 4, characterized in that: The seal-like pelvic unit includes a front end plate and a rear end plate. The segmental vertebrae of the seal lumbar unit are arranged between the front end plate and the rear end plate. The cone bones of the segmental vertebrae are disc-shaped. The elastic cylindrical rods are symmetrically arranged on the upper and lower sides of the serially connected cones and pass through and connect the cone bones. The front end of the elastic cylindrical rod is connected to the front end plate, and the rear end of the rear end plate is connected to the rear end plate. The pull wire passes through the vertebrae of the segmental vertebrae and is connected to the rear end plate.

6. The seal-like robot capable of realizing two tail motion modes according to claim 5, characterized in that: The cone of the segmental vertebra is provided with a guide pulley, and the pull wire is guided through the guide pulley of the segmental vertebra in turn and connected to the rear end plate.

7. The seal-like robot capable of realizing two tail movement modes according to claim 6, characterized in that: A lumbar drive bracket is installed at the front of the front end plate, and an axially extending tensioning slide rail is installed on the lumbar drive bracket. A lumbar drive slide that moves along the tensioning slide rail and an adjustment bolt for fixing the position of the lumbar drive slide are installed on the tensioning slide. The lumbar drive device is installed on the lumbar drive slide, and the output shaft of the lumbar drive device is connected to the pull wire.

8. The seal-like robot capable of realizing two tail motion modes according to claim 1, characterized in that: The femoral-tibiofibular unit includes a lower limb support fixed to the pelvic unit, the root of the tibia is connected to the lower limb support through a first lower limb connecting rod, the rear of the tibia is connected to the lower limb support through a second lower limb connecting rod, the output shaft of the tibial drive device is installed with a lower limb drive crank, and the second lower limb connecting rod is connected to the lower limb drive crank through a third lower limb connecting rod.

9. The seal-like robot capable of realizing two tail motion modes according to claim 8, characterized in that: The second lower limb connecting rod, the third lower limb connecting rod, the lower limb driving crank and the lower limb support form a parallelogram mechanism.

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