Manta ray-imitated underwater vehicle with pectoral fins capable of actively and passively deforming

Abstract

The invention discloses a manta ray-imitated underwater vehicle with pectoral fins capable of actively and passively deforming, and belongs to the technical field of bionic robots. Comprising a manta ray-imitated skeleton, a plurality of driving joints mounted on the manta ray-imitated skeleton and a skin covering the outer surface of the manta ray-imitated skeleton, and the driving joints are angle servo drivers; the manta ray imitating skeleton comprises a trunk skeleton and pectoral fin skeletons, and the two pectoral fin skeletons are symmetrically arranged on the two sides of the trunk skeleton and are coupled with the driving joints to form linkage pectoral fins; series-parallel control is carried out on the multiple driving joints through the control module, and deformation movement of the pectoral fin in the spanwise direction and deformation movement of the pectoral fin in the chordwise direction are achieved. And the manta ray imitating skeleton and the driving joint are packaged through the skin to form a bionic appearance. According to the bionic multi-joint pectoral fin, large deformation movement in the spanwise direction and fluctuation transmission in the chordwise direction of the bionic multi-joint pectoral fin are achieved, and the bionic pectoral fin shows complex flexible movement similar to that of a real manta ray pectoral fin in the movement process.

Description

Technical Field

[0001] The invention belongs to the technical field of bionic robots, and in particular relates to a manta ray-like underwater vehicle with active and passive deformation of pectoral fins. Background Art

[0002] Manta rays swim by swinging their pectoral fins. Compared with fish that rely on their tail fins for propulsion, manta rays' flat body structure provides better stability, flexibility, and propulsion efficiency. Their unique swimming mode that combines gliding and flapping provides an important reference for the design of bionic underwater vehicles. Vehicles based on manta rays have many advantages, including high propulsion efficiency, strong maneuverability, strong stability, and low noise and environmental interference. Therefore, bionic vehicles can effectively improve underwater maneuverability and endurance, while overcoming the limitations of traditional submersibles in terms of stealth, flexibility, and endurance.

[0003] Bionic flexible pectoral fins are the key propulsion devices of manta ray-like vehicles. The morphological structure and motion state of flexible pectoral fins play a vital role in improving propulsion efficiency. When the pectoral fins of real manta rays flap, there is a certain phase difference in the span direction of the pectoral fins, and the fin tip has a significant lag compared with the entire pectoral fin. Studies have shown that the lag of the fin tip phase has a certain improvement in the thrust and efficiency of the pectoral fins. At present, most bionic flexible pectoral fins mainly rely on the flapping of the rigid pectoral fin root to move, and cannot accurately control the local deformation of the flexible part of the pectoral fin span, resulting in limited flexibility of the pectoral fins and unable to fully simulate the complex flexible pectoral fin movement in nature. This limitation has prevented the potential advantages of flexible pectoral fins from being fully utilized, resulting in the propulsion performance of bionic pectoral fins being far lower than that of their natural prototypes. In contrast, real flexible bionic pectoral fins can generate thrust through the active deformation of the entire pectoral fin surface and the passive deformation after the water flow. Summary of the invention

[0004] Technical issues to be solved:

[0005] In order to avoid the shortcomings of the prior art, the present invention provides a manta ray-like underwater vehicle with active and passively deformable pectoral fins, the multi-joint pectoral fins of the manta ray-like underwater vehicle can realize the flapping motion of the bionic manta ray pectoral fins, the outer contour shape of the flexible fin rays of the bionic joint structure supports the entire shape of the pectoral fins, and the outputs of the root, middle and fin tip motors are controlled in a hybrid manner through an adaptive closed-loop control system of a central pattern generator to drive the active motion of the swinging fin rays and the passive motion after the fin rays are coupled with the water flow to cooperate with each other, thereby realizing large deformation motion of the bionic multi-joint pectoral fins along the span direction and wave transmission along the chord direction, so that the bionic pectoral fins show complex flexible motion similar to that of the real manta ray pectoral fins during movement.

[0006] The technical solution of the present invention is: a manta ray-like underwater vehicle with active and passively deformable pectoral fins, comprising a manta ray-like frame, a plurality of driving joints mounted thereon, and a skin covering the outer surface thereof, wherein the driving joints are angle servo drivers; the manta ray-like frame comprises a trunk frame and a pectoral fin frame, wherein two groups of pectoral fin frames are symmetrically arranged on both sides of the trunk frame, and are coupled with the plurality of driving joints to form linkage pectoral fins;

[0007] The control module is used to perform hybrid control on multiple driving joints to realize the deformation movement of the pectoral fin along the span direction and the chord direction; the manta ray skeleton and driving joints are encapsulated through the skin to form a bionic appearance.

[0008] A further technical solution of the present invention is: the spatial layout of the multiple driving joints is two symmetrical T-shaped arrays, the driving joints arranged in the two T-shaped transverse arrays are located on both sides of the trunk skeleton, connected to the root of the pectoral fin skeleton, and are used to control the deformation movement of the pectoral fin along the chord direction; the driving joints arranged in the two T-shaped vertical arrays are located in the span direction of the pectoral fin skeleton, and are used to control the deformation movement of the pectoral fin along the span direction.

[0009] A further technical solution of the present invention is: the trunk skeleton is a bionic shell structure symmetrical with respect to the central symmetry plane of the aircraft, the front end of which is the aircraft head, the rear end is the aircraft tail fin, and the upper and lower surfaces thereof serve as skin support surfaces;

[0010] The bionic shell structure is a hollow shell with two through sides, and three driving joints are arranged on both sides of the cavity from the head to the tail, that is, the driving joints along the T-shaped horizontal array, and the output shaft of each driving joint is connected to the corresponding swinging fin through a circular steering wheel; the swinging fin connected to the middle driving joint is sequentially arranged with a middle driving joint and a fin tip driving joint along the span direction, that is, the driving joints along the T-shaped vertical array.

[0011] A further technical solution of the present invention is: the three-section drive joints are respectively a primary drive joint, a secondary drive joint and a tertiary drive joint from the head to the tail; the output shaft of the primary drive joint is connected to the primary root swing fin ray through a circular steering disc, and the end of the primary root swing fin ray is connected to the primary follower fin ray through an elastic component along its length direction; the output shaft of the secondary drive joint is connected to the secondary root swing fin ray through a circular steering disc, and a middle drive joint is installed on the secondary root swing fin ray, and the output shaft of the middle drive joint is connected to the middle swing fin ray through a steering gear arm, and a fin tip drive joint is installed on the middle swing fin ray connection, and the output shaft of the fin tip drive joint is connected to the fin tip swing fin ray through a steering gear arm; the output shaft of the tertiary drive joint is connected to the tertiary root swing fin ray through a circular steering disc, and a conformal skeleton of the rear edge of the pectoral fin is provided at the root of the tertiary root swing fin ray.

[0012] A further technical solution of the present invention is: a conformal skeleton at a corresponding position is arranged at the same spanwise position of the swinging pectoral fins connected to the respective output shafts of the three-section driving joints, and a plurality of groups of conformal skeletons are arranged along the spanwise direction of the pectoral fins, and each group of conformal skeletons constitutes a NACA00 airfoil frame; wherein the middle sections of the conformal skeletons on the middle swinging fin rays and the swinging fin rays at the fin tip are connected to the conformal skeletons at the leading and trailing edges of the pectoral fins through elastic components.

[0013] A further technical solution of the present invention is that the elastic component is two springs arranged in parallel, and two ends of the elastic component are respectively installed on the adjacent ends of two connected parts through ear hanging structures to achieve flexible follow-up of the connected parts.

[0014] A further technical solution of the present invention is: the middle section of the conformal frame at the middle swinging fin ray is connected to the conformal frame connected to the rear edge of the pectoral fin through a spring assembly and a rotational pair mechanism, the middle section of the conformal frame and the adjacent ends of the conformal frame at the rear edge of the pectoral fin are both provided with through holes, and the two ends of the rotational pair mechanism are respectively matched with the two through holes, that is, the rotational connection between the two is achieved through the rotational pair mechanism; the rotational pair mechanism includes a first U-shaped connecting rod and a second U-shaped connecting rod, the two arms of the first U-shaped connecting rod are hollow structures, respectively passing through the through holes on the conformal frame in the middle section of the conformal frame and the rear edge of the pectoral fin, and the two arms of the second U-shaped connecting rod are respectively inserted into the two hollow arms of the first U-shaped connecting rod, that is, a rectangular rotational pair mechanism is formed;

[0015] The spring assembly is located above the rotational pair mechanism and limits the rotational angle of the rotational pair mechanism through the rebound force.

[0016] A further technical solution of the present invention is: the driving joint is a motor or a steering gear.

[0017] A control method for a manta ray-like underwater vehicle with active and passive deformation of pectoral fins, the specific steps are as follows:

[0018] Initialize the amplitude, phase, and frequency parameters of the driven joint;

[0019] The initialized parameters are output to the control module to calculate the amplitude and phase signals;

[0020] Generate the angle signal of the driving joint according to the amplitude and phase signals; the expression is as follows:

[0021] θ i =r i (1+cos(φ i ))

[0022] Among them, θ i represents the output angle of the i-th driving joint, r i represents the amplitude of the i-th driven joint, φ i represents the phase of the i-th driven joint;

[0023] Transmit the angle signal of the driving joint to the driving joint and execute the angle control instruction;

[0024] Detect the error between the output signal and the feedback signal, and adjust the angle control command of the driving joint according to the error until the error requirement is met.

[0025] A further technical solution of the present invention is: the calculation formula of the amplitude and phase signal is as follows:

[0026] The phase equation is expressed as:

[0027]

[0028] Among them, φ i represents the phase of the i-th driven joint, φ i represents the phase of the jth driven joint, v i represents the frequency of driving the joint, w ij represents the coupling weight of the j-th driven joint to the i-th driven joint, Δφ ij represents the expected phase difference between the j-th driven joint and the i-th driven joint;

[0029] The amplitude equation is expressed as:

[0030]

[0031] Among them, r i represents the amplitude of the i-th driven joint, a i represents the coefficient that controls the convergence speed of the amplitude of the i-th driven joint, R i represents the desired amplitude of the i-th driven joint.

[0032] Beneficial Effects

[0033] The beneficial effects of the present invention are as follows: the present invention utilizes the root, middle and fin tip driving joints to drive the active movement of the swinging fins and the passive movement of the fins coupled with water to cooperate with each other, so as to realize the large deformation movement of the bionic multi-joint pectoral fin along the span direction and the wave transmission along the chord direction, and adopts the adaptive closed-loop control system of the central pattern generator to perform hybrid control on the wave of the bionic flapping wing along the span direction and the chord direction, so as to complete the complex flexible deformation movement. The specific advantages are as follows:

[0034] 1. The present invention realizes spanwise bending motion and chordwise fluctuation of the bionic pectoral fin by hybrid control of driving joints of various parts of the bionic pectoral fin to output different phases and amplitudes, so as to make the multi-joint pectoral fin structure fit more accurately the multi-degree-of-freedom flexible flapping motion, thereby realizing a manta ray-like underwater vehicle with active and passive deformation of the pectoral fin.

[0035] 2. The present invention places multiple motors inside the pectoral fins, and each motor can be driven individually. The output phase difference of the multiple motors is controlled in a mixed manner through the adaptive closed-loop control system of the central pattern generator, so as to realize the wave number regulation of the sinusoidal motion in the chord direction of the bionic pectoral fin and the step-by-step lag of the flapping in the span direction of the bionic pectoral fin from the root to the fin tip, thereby improving the propulsion efficiency and maneuverability of the existing MPF bionic pectoral fin. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 1 is a general structural diagram of a manta ray-like underwater vehicle with active and passive deformation of pectoral fins according to an embodiment of the present invention;

[0037] Figure 2 is a partial enlarged view of the multi-jointed pectoral fin structure in an embodiment of the present invention;

[0038] Figure 3 is a partial enlarged view of a first-stage swinging fin ray in an embodiment of the present invention;

[0039] Figure 4 is a partial enlarged view of the multi-jointed pectoral fin structure in an embodiment of the present invention;

[0040] Figure 5 is a partial enlarged view of the middle follower fin ray in an embodiment of the present invention;

[0041] Figure 6 is a diagram of fin ray swinging at the fin tip in an embodiment of the present invention;

[0042] Figure 7 is a diagram of a rotating pair structure in an embodiment of the present invention;

[0043] Figure 8 is a flow chart of a CPG adaptive closed-loop control system according to an embodiment of the present invention;

[0044] Fig. 9 Schematic diagram of CPG hybrid control architecture in an embodiment of the present invention;

[0045] Explanation of the reference numerals: 1. upper trunk frame, 2. lower trunk frame, 3. middle motor, 4. fin tip motor, 5. first-level root motor, 6. second-level root motor, 7. third-level root motor, 8. first-level motor bracket, 9 second-level motor bracket, 10, third-level motor bracket, 11. circular steering disc, 12. first-level root swing fin rays, 13. first-level follower fin rays, 14.30mm spring, 15. servo arm, 16. middle conformal frame, 17. middle swing fin rays, 18. second-level root swing fin rays, 19. middle follower fin rays, 20. rotating sub-mechanism, 21. servo arm, 22. fin tip follower fin rays, 23. fin tip follower fin rays, 24. fin tip swing fin rays, 25.20mm spring, 26. servo arm, 27. third-level root swing fin rays, 28. first U-shaped connecting rod, 29. second U-shaped connecting rod. DETAILED DESCRIPTION

[0046] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0047] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0048] Based on the fact that most of the current bionic flexible pectoral fins mainly rely on the flapping of the rigid pectoral fin roots to move, it is impossible to accurately control the local deformation of the flexible part of the pectoral fin in the span direction, resulting in limited flexibility of the pectoral fins and an inability to fully simulate the complex flexible pectoral fin movement in nature. The present invention provides a manta ray-like underwater vehicle with active and passive deformation of pectoral fins, comprising a manta ray-like skeleton and a plurality of driving joints mounted thereon, and a skin covering the outer surface thereof, wherein the driving joints are angle servo drivers; the manta ray-like skeleton comprises a trunk skeleton and a pectoral fin skeleton, two groups of pectoral fin skeletons are symmetrically arranged on both sides of the trunk skeleton, and are coupled with a plurality of driving joints to form a linkage pectoral fin; a control module is used to perform hybrid control on the plurality of driving joints to realize the deformation movement of the pectoral fin along the span direction and the deformation movement along the chord direction; the manta ray-like skeleton and the driving joints are encapsulated by the skin.

[0049] Specifically, the multiple driving joints are spatially arranged in two symmetrical T-shaped arrays. The driving joints arranged in the two T-shaped transverse arrays are located on both sides of the trunk skeleton and are connected to the root of the pectoral fin skeleton, so as to control the deformation movement of the pectoral fin along the chord direction; the driving joints arranged in the two T-shaped vertical arrays are located in the span direction of the pectoral fin skeleton, so as to control the deformation movement of the pectoral fin along the span direction.

[0050] Specifically, the trunk skeleton is a bionic shell structure symmetrical with the central symmetry plane of the aircraft, with its front end being the aircraft head and the rear end being the aircraft tail fin, and its upper and lower surfaces serving as skin support surfaces; the bionic shell structure is a hollow shell with through-both sides, and three driving joints are arranged on both sides of the cavity from the head to the tail, namely, driving joints along the T-shaped horizontal array, and the output shafts of each driving joint are connected to the corresponding swinging fins through a circular steering wheel; the swinging fins connected to the middle driving joint are sequentially arranged with a middle driving joint and a fin tip driving joint along the span direction, namely, driving joints along the T-shaped vertical array.

[0051] Specifically, the three driving joints are, from the head to the tail, a primary driving joint, a secondary driving joint, and a tertiary driving joint; the output shaft of the primary driving joint is connected to the primary root swing fin ray through a circular steering disc, and the end of the primary root swing fin ray is connected to the primary follower fin ray through an elastic component along its length direction; the output shaft of the secondary driving joint is connected to the secondary root swing fin ray through a circular steering disc, and a middle driving joint is installed on the secondary root swing fin ray, and the output shaft of the middle driving joint is connected to the middle swing fin ray through a steering gear arm, and a fin tip driving joint is installed on the middle swing fin ray connection, and the output shaft of the fin tip driving joint is connected to the fin tip swing fin ray through a steering gear arm; the output shaft of the tertiary driving joint is connected to the tertiary root swing fin ray through a circular steering disc, and a conformal skeleton of the rear edge of the pectoral fin is provided at the root of the tertiary root swing fin ray.

[0052] Specifically, a conformal skeleton at a corresponding position is arranged at the same spanwise position of the swinging pectoral fin connected to each output shaft of the three driving joints, and a plurality of groups of conformal skeletons are arranged in the spanwise direction of the pectoral fin, and each group of conformal skeletons constitutes a NACA00 airfoil frame; wherein, the middle sections of the conformal skeletons on the middle swinging fin ray and the swinging fin ray at the fin tip are connected to the conformal skeletons at the leading edge and the trailing edge of the pectoral fin through elastic components.

[0053] Specifically, the elastic component is two springs arranged in parallel, and the two ends of the elastic component are respectively installed on the adjacent ends of the two connected parts through the ear structures to achieve flexible follow-up of the connected parts.

[0054] Specifically, the middle section of the conformal frame at the middle swinging fin is connected to the conformal frame connected to the rear edge of the pectoral fin through a spring assembly and a rotational sub-mechanism, and the middle section of the conformal frame and the adjacent ends of the conformal frame at the rear edge of the pectoral fin are both provided with through holes, and the two ends of the rotational sub-mechanism are respectively matched with the two through holes in a clearance, that is, the rotational connection between the two is achieved through the rotational sub-mechanism; the rotational sub-mechanism includes a first U-shaped connecting rod and a second U-shaped connecting rod, and the two arms of the first U-shaped connecting rod are hollow structures, which respectively penetrate through the through holes on the conformal frame at the rear edge of the pectoral fin at the middle section of the conformal frame, and the two arms of the second U-shaped connecting rod are respectively inserted into the two hollow arms of the first U-shaped connecting rod, to form a rectangular rotational sub-mechanism; the spring assembly is located above the rotational sub-mechanism, and limits the rotation angle of the rotational sub-mechanism by the rebound force.

[0055] Specifically, the driving joint is a motor or a steering gear.

[0056] The present invention performs hybrid control on the outputs of the root, middle and fin tip motors through an adaptive closed-loop control system of a central pattern generator, drives the active movement of the swinging fin rays and the passive movement of the fin rays coupled with the water flow to cooperate with each other, realizes the large deformation movement of the bionic multi-joint pectoral fin along the span direction and the wave transmission along the chord direction, so that the bionic pectoral fin exhibits complex flexible movement similar to that of the pectoral fin of a real manta ray during movement.

[0057] The above technical solution is further described below in conjunction with the accompanying drawings:

[0058] Reference Figure 1-Figure 7 As shown, the present embodiment is a manta ray-like underwater vehicle with active and passive deformation of pectoral fins, which has a multi-joint pectoral fin mechanism with controllable spanwise bending and chordwise fluctuation, including: a trunk upper skeleton 1, a trunk lower skeleton 2, a middle motor 3, a fin tip motor 4, a first-level root motor 5, a second-level root motor 6, a third-level root motor 7, a first-level motor bracket 8, a second-level motor bracket 9, a third-level motor bracket 10, a circular steering disc 11, a first-level root swinging fin ray 12, a first-level follower fin ray 13, a 30mm spring 14, a steering gear arm 15, a middle conformal skeleton 16, a middle swinging fin ray 17, a second-level root swinging fin ray 18, a middle follower fin ray 19, a rotary sub-mechanism 20, a steering gear arm 21, a fin tip follower fin ray 22, a fin tip follower fin ray 23, a fin tip swinging fin ray 24, a 20mm spring 25, a steering gear arm 26, a third-level root swinging fin ray 27, a connecting rod 28, a connecting rod 29 and a skin. The motor in this embodiment is the driving joint.

[0059] The following is a detailed description of the installation method of each mechanism of the manta ray-like underwater vehicle: The manta ray-like underwater vehicle with active and passive deformation of the pectoral fin includes a trunk frame, a drive motor, a pectoral fin frame and a skin. The structure of the manta ray-like underwater vehicle is symmetrical about the central axis, so this embodiment is described according to the left side structure of the vehicle.

[0060] Reference Figure 1 As shown, the trunk skeleton described in this embodiment includes an upper trunk skeleton 1 and a lower trunk skeleton 2; the upper trunk skeleton 1 serves as the back frame structure of the manta ray-like underwater vehicle, and a circular groove is opened on its back, which can be connected and fixed with a mechanical sensor to test the mechanical properties of the vehicle, and through holes are opened on both sides close to the pectoral fins, and the circuits of each drive motor are connected to the peripheral device through the through holes; the lower trunk skeleton 2 serves as a mounting platform for the root motor, and six motor brackets are attached to its upper surface, and three symmetrical brackets are respectively provided on the left and right sides, which are a first-level motor bracket 8, a second-level motor bracket 9 and a third-level motor bracket 10, and the lower trunk skeleton 2 also serves as the frame structure of the head, trunk body and tail of the manta ray-like underwater vehicle; the upper surface of the upper trunk skeleton 1 and the lower surface of the lower trunk skeleton 2 are covered with a flexible skin to achieve the purpose of shape preservation.

[0061] Reference Figure 2 As shown, the driving motor includes a primary root motor 5, a secondary root motor 6, a tertiary root motor 7, a middle motor 3 and a fin tip motor 4; the primary root motor 5, the secondary root motor 6 and the tertiary root motor 7 are fixed to the lower trunk skeleton 2 through a primary motor bracket 8, a secondary motor bracket 9 and a tertiary motor bracket 10 respectively, and their output shafts are perpendicular to the side of the lower trunk skeleton 2; the output shafts of the primary root motor 5 and the secondary root motor 6 are coaxially fixed thereto through a circular steering disc 11, and the tertiary root motor 7 is coaxially fixed to its output shaft using a steering gear arm 26, and the circular steering disc 11 and the steering gear arm 26 can rotate synchronously with the motor; the output shafts of the middle motor 3 and the fin tip motor 4 are also perpendicular to the side of the lower trunk skeleton 2, and are coaxially fixed with a steering gear arm 15 and a steering gear arm 21;

[0062] Reference Figure 2 , Figure 3 As shown, the pectoral fin skeleton described in this embodiment includes primary swinging fin rays, secondary swinging fin rays, and tertiary swinging fin rays. The swinging fin rays are provided with NACA00 airfoil conformal skeletons along the chord direction of the bionic pectoral fin; the primary swinging fin rays include primary root swinging fin rays 12 and primary follower fin rays 13; the primary swinging fin rays serve as the leading edge support structure of the multi-joint pectoral fin, and the primary root swinging fin rays 12 are coaxially fixed to the circular steering disc 11 on the primary root motor 5 through the root adapter structure, so as to realize the span-wise swinging freedom of the primary swinging fin rays, and the primary root swinging fin rays 12 are attached with conformal skeletons of the leading edge of the pectoral fin for supporting the flexible skin; the primary follower fin rays 13 serve as the leading edge support structure at the fin tip, and similarly, the primary follower fin rays 13 are attached with conformal skeletons of the leading edge of the pectoral fin for supporting the flexible skin of flapping motion. Figure 4 As shown, the upper and lower surfaces of the primary swing fin ray 12 and the primary follower fin ray 13 are provided with a slot structure. In order to eliminate the preload force of the single spring fixation, the hooks on both sides of the two 30mm springs 14 are respectively matched and fixed with the above-mentioned slot structure, so that the primary follower fin ray 13 follows the movement of the primary swing fin ray 12 under the constraint of the 30mm spring 14; the 30mm spring 14 not only serves as a connecting structure between the primary swing fin ray 12 and the primary follower fin ray 13, but also serves as a partial front edge support structure of the pectoral fin;

[0063] The secondary swinging fin ray comprises a secondary root swinging fin ray 18, a secondary middle swinging fin ray and a secondary fin tip swinging fin ray; the secondary root swinging fin ray 18 is attached with a conformal skeleton of the root of the pectoral fin, and the adapter structure at its root is coaxially fixed with the circular steering disc 11 on the secondary root motor 6, and the other side is connected and fixed with the middle motor 3, and the secondary root swinging fin ray 18 serves as a connecting structure between the secondary root motor 6 and the middle motor 3, so as to realize the freedom of the secondary root swinging fin ray 18 to swing in the span direction around the secondary root motor 6; the secondary middle swinging fin ray comprises a middle conformal skeleton 16, a middle swinging fin ray 17 and a middle follower fin ray 19; the middle conformal skeleton 16 serves as a supporting structure in the chordwise direction of the middle part of the pectoral fin, and is fixed to the steering gear arm 15 of the middle motor 3, And it fits with the fin tip motor 4; similarly, the middle swing fin ray is fixed to the servo arm 15 of the middle motor, fits with the fin tip motor 4, and the middle conformal skeleton 16 and the middle swing fin ray 17 of the pectoral fin cooperate with each other to form a slot, half-wrapping and fixing the fin tip motor 4, so as to realize the freedom of the secondary middle swing fin ray to swing around the middle motor 3 in the span direction; the NACA00 airfoil conformal strip of the middle follower fin ray 19 is cut in a left-right staggered manner so that the skin support structure of the conformal strip is "S" shaped, and the cutting is performed in a non-equal step length manner so that the volume of the connection of the middle follower fin ray 19 from front to back gradually decreases, so as to achieve the effect of gradually increasing its flexibility from front to back, which meets the characteristic that the flexibility of the pectoral fin of a real manta ray gradually increases from the leading edge to the trailing edge. Reference Figure 5 As shown, it is fixed to the middle conformal frame 16 by two 30mm springs 14, and a rotational substructure 20 is used between the middle follower fin 19 and the middle conformal frame 16 to constrain the middle follower fin 19 to have only one rotational degree of freedom during the movement of the middle conformal frame 16; Figure 7 As shown, the rotating secondary structure 20 includes a connecting rod 28 and a connecting rod 29. The assembly axis of the connecting rod 28 is a hollow axis, and the assembly axis of the connecting rod 29 is a solid axis. The assembly axes of the two are connected by interference fit. The two side arms after connection are respectively rotatably connected with the middle conformal skeleton 16 and the middle follower fin ray 19. The secondary fin tip swing fin ray includes a fin tip swing fin ray 24, a fin tip follower fin ray 22 and a fin tip follower fin ray 23. The fin tip swing fin ray 24 is fixed to the steering gear arm 21 of the fin tip motor 4, so as to realize the freedom of the secondary fin tip swing fin ray 24 to swing around the fin tip motor 4 in the span direction. Figure 6As shown, the fin tip swing fin ray 24 is attached with a conformal frame at the pectoral fin tip, and the fin tip swing fin ray 24 is connected to the primary follower fin ray 13 through a spring to form a constraint, so as to prevent the flexible skin from being greatly deformed and damaged during the flapping of the fin ray, and the thickness of the frame at the fin tip gradually decreases from the root to the tip; the fin tip follower fin ray 22 and the fin tip follower fin ray 23 of the fin tip follower fin ray are fixedly connected to the fin tip swing fin ray 24 through two upper and lower 20mm springs 25 in the same manner as described above, and the flexibility of the frame gradually increases from the front to the back;

[0064] Reference Figure 3 As shown, the three-stage swing fin ray 27 is coaxially fixed with the servo arm 26 on the three-stage root motor 7, so as to realize the freedom of the three-stage swing fin ray to swing in the span direction around the three-stage root motor 7. The three-stage swing fin ray 27 is attached with a conformal skeleton of the pectoral fin root and the trailing edge of the pectoral fin. In order to meet the similar structure with the relatively soft trailing edge of the real manta ray, the flexibility of the conformal skeleton gradually increases from the front to the rear. The skin is a flexible material with elastic deformable properties, covering the outer surface of the trunk skeleton and the pectoral fin skeleton, and being adhered and fixed to each part of the skeleton.

[0065] Combination Figure 1-3 As shown, the driving control method of the manta ray-like underwater vehicle is described in detail below: the movement of the bionic vehicle is driven by a motor by imitating the swimming posture of the manta ray, and the power supply and control signal lines required by the drive motor are connected to each drive motor through the through holes opened on both sides of the upper frame 1 of the trunk near the pectoral fins. The drive motor acts as a joint structure in the pectoral fin of the manta ray-like underwater vehicle, and moves with the fin ray fixed to it through the motor traction. The structure of the manta ray-like underwater vehicle is symmetrical from the left to the right about the central axis, so this embodiment is described according to the left side structure of the vehicle.

[0066] When a real manta ray swims, its pectoral fins generate waves in both the spanwise and chordwise directions. The spanwise flapping of the pectoral fins generates lateral force, and the chordwise fluctuations of the pectoral fins are used to slap the water backwards to generate thrust, thereby achieving its own turning and forward propulsion. In order to make the bionic vehicle achieve the swimming posture of the manta ray as much as possible, the control of the present invention adopts an adaptive closed-loop control system of the central pattern generator (CPG), and uses a hybrid control method to dynamically regulate the spanwise and chordwise fluctuations of the bionic pectoral fins. The core is to generate periodic outputs through the CPG model, and adjust the state of the servo motor through real-time feedback to achieve a dynamically balanced closed-loop control. The CPG model is mainly composed of a phase equation, an amplitude equation, and an output equation.

[0067] The phase equation is expressed as:

[0068]

[0069] Among them, φ irepresents the phase of the i-th motor, v i Indicates the frequency of the motor, w ij represents the coupling weight of the jth motor to the ith motor, Δφ ij represents the desired phase difference between the j-th motor and the i-th motor.

[0070] The amplitude equation is expressed as:

[0071]

[0072] where r i represents the amplitude of the i-th motor, a i Represents the coefficient that controls the convergence speed of the amplitude of the i-th motor, R i represents the desired amplitude of the i-th motor.

[0073] The output equation is expressed as:

[0074] θ i =r i (1+cos(φ i )),

[0075] where θ i Represents the output angle of the i-th motor.

[0076] Reference Figure 8 As shown in the figure, it is a flow chart of the CPG adaptive closed-loop control system. In order to achieve the flapping of the manta ray-like aircraft in the span direction and the chord direction, a hybrid control architecture is used to adjust the signals of each unit (motor) of the CPG. The specific schematic diagram of the CPG hybrid control architecture is shown in Fig. 9 shown.

[0077] By changing the output angle of the motor output shaft, the fin ray can rotate around the axis, and the height of the fin ray tip is controlled by the output angle of the motor connected to it. Taking the pectoral fin upstroke as an example, the output angles of the first-stage root motor 5, the second-stage root motor 6 and the third-stage root motor 7 are respectively θ1=A1sin(ω1t+Δφ 21 ), θ2=A2 sin(ω2t) and θ3=A3sin(ω3t+Δφ 23 ) changes with time. Among them, θ i is the output angle of a motor, A i is the amplitude of a motor, ω i is the angular velocity of a motor, Δφ ij is the phase difference between motor i and motor j. Based on the output of the secondary root motor 6, the phase of the primary root motor 5 is Δφ ahead of the secondary root motor 6. 21 The output angle of the third-stage root motor 7 lags behind the second-stage root motor 6 by Δφ 23In the actual movement process, the first-level root motor 5 rotates counterclockwise first, and then the second-level root motor 6 and the third-level root motor 7 rotate counterclockwise in sequence, ensuring that the movement of the first-level root motor 5 always leads the second-level root motor 6, and the movement of the second-level root motor 6 always leads the third-level root motor 7. The root motors at each level pull the fins connected to them to move, thereby realizing the chordal fluctuation of the pectoral fins during the flapping process, providing the main thrust for the forward movement of the vehicle.

[0078] The output angles of the middle motor 3 and the fin tip motor 4 are θ4=A4 sin(ω4t+Δφ 24 ) and θ5=A5 sin(ω5t+Δφ 45 ) changes with time, the middle motor 3 takes the output of the secondary root motor 6 as the reference, and its output amplitude is A4=k1A2, and lags behind the secondary root motor 6 by a phase Δφ 24 The output amplitude of the fin tip motor 4 is A5=k2A4 based on the middle motor 3. Similarly, the output phase of the fin tip motor 4 lags behind the phase of the middle motor 3 by Δφ. 45 By adjusting the amplitude coefficients k1 and k2 of the output of the middle motor 3 and the fin tip motor 4, the bending deformation degree of the pectoral fin in the span direction is controlled. 24 and Δφ 45 By regulating and controlling, the flapping motion of the bionic pectoral fin from the root to the fin tip is delayed in sequence, thereby realizing a large spanwise deformation of the multi-joint pectoral fin and improving the movement efficiency of the aircraft.

[0079] The CPG hybrid control method is adopted to make the outputs of the five motors on one side cooperate with each other, realize the wave transmission of the pectoral fin in the chord direction, and the active bending deformation of the pectoral fin when flapping, so that the bionic pectoral fin can show complex flexible movement similar to the pectoral fin of a real manta ray during movement. The errors of the output signals and feedback signals of each motor are detected at all times, and dynamic adjustments are made through closed-loop control to improve the robustness of the bionic vehicle during movement.

[0080] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A manta ray-like underwater vehicle with active and passive deformation of pectoral fins, characterized in that: It includes a manta ray-like skeleton, a plurality of driving joints installed thereon, and a skin covering the outer surface thereof, wherein the driving joints are angle servo drivers; the manta ray-like skeleton includes a trunk skeleton and a pectoral fin skeleton, wherein two groups of pectoral fin skeletons are symmetrically arranged on both sides of the trunk skeleton and coupled with the plurality of driving joints to form linkage pectoral fins; The control module is used to perform hybrid control on multiple driving joints to realize the deformation movement of the pectoral fin along the span direction and the chord direction; the manta ray skeleton and driving joints are encapsulated through the skin to form a bionic appearance.

2. The manta ray-like underwater vehicle with active and passive deformation of pectoral fins according to claim 1, characterized in that: The multiple driving joints are spatially arranged in two symmetrical T-shaped arrays, and the driving joints arranged in the two T-shaped lateral arrays are located on both sides of the trunk skeleton and connected to the root of the pectoral fin skeleton to control the deformation movement of the pectoral fin along the chord direction; The array is arranged in two T-shaped vertical drive joints located in the span direction of the pectoral fin skeleton, and is used to control the deformation movement of the pectoral fin along the span direction.

3. The manta ray-like underwater vehicle with active and passive deformation of pectoral fins according to claim 2, characterized in that: The trunk skeleton is a bionic shell structure symmetrical with respect to the central symmetry plane of the aircraft, with the front end being the aircraft head and the rear end being the aircraft tail fin, and the upper and lower surfaces thereof serving as skin support surfaces; The bionic shell structure is a hollow shell with two through sides, and three driving joints are arranged on both sides of the cavity from the head to the tail, that is, the driving joints along the T-shaped horizontal array, and the output shaft of each driving joint is connected to the corresponding swinging fin through a circular steering wheel; the swinging fin connected to the middle driving joint is sequentially arranged with a middle driving joint and a fin tip driving joint along the span direction, that is, the driving joints along the T-shaped vertical array.

4. The manta ray-like underwater vehicle with active and passive deformation of pectoral fins according to claim 3, characterized in that: The three driving joints are respectively a primary driving joint, a secondary driving joint and a tertiary driving joint from the head to the tail; the output shaft of the primary driving joint is connected to the primary root swinging fin ray through a circular steering disc, and the end of the primary root swinging fin ray is connected to the primary follower fin ray through an elastic component along its length direction; the output shaft of the secondary driving joint is connected to the secondary root swinging fin ray through a circular steering disc, and a middle driving joint is installed on the secondary root swinging fin ray, and the output shaft of the middle driving joint is connected to the middle swinging fin ray through a steering gear arm, and a fin tip driving joint is installed on the connection of the middle swinging fin ray, and the output shaft of the fin tip driving joint is connected to the fin tip swinging fin ray through a steering gear arm; the output shaft of the tertiary driving joint is connected to the tertiary root swinging fin ray through a circular steering disc, and a conformal skeleton of the rear edge of the pectoral fin is provided at the root of the tertiary root swinging fin ray.

5. The manta ray-like underwater vehicle with active and passive deformation of pectoral fins according to claim 4, characterized in that: A conformal skeleton at a corresponding position is arranged at the same spanwise position of the swinging pectoral fin connected to each output shaft of the three-section driving joint, and a plurality of groups of conformal skeletons are arranged along the spanwise direction of the pectoral fin, and each group of conformal skeletons constitutes a NACA00 airfoil frame; wherein, the middle section of the conformal skeleton on the middle swinging fin ray and the fin tip swinging fin ray is connected to the conformal skeletons at the leading edge and the trailing edge of the pectoral fin through an elastic component.

6. The manta ray-like underwater vehicle with active and passive deformation of pectoral fins according to claim 5, characterized in that: The elastic component is two springs arranged in parallel, and the two ends of the elastic component are respectively installed on the adjacent ends of the two connected parts through the ear structures to achieve flexible follow-up of the connected parts.

7. The manta ray-like underwater vehicle with active and passive deformation of pectoral fins according to claim 6, characterized in that: The middle section of the conformal frame at the middle swinging fin ray is connected to the conformal frame connected to the rear edge of the pectoral fin through a spring assembly and a rotational pair mechanism. The middle section of the conformal frame and the adjacent ends of the conformal frame at the rear edge of the pectoral fin are both provided with through holes, and the two ends of the rotational pair mechanism are respectively matched with the two through holes, that is, the rotational connection between the two is achieved through the rotational pair mechanism; the rotational pair mechanism includes a first U-shaped connecting rod and a second U-shaped connecting rod, the two arms of the first U-shaped connecting rod are hollow structures, respectively passing through the through holes on the conformal frame at the rear edge of the pectoral fin in the middle section of the conformal frame, and the two arms of the second U-shaped connecting rod are respectively inserted into the two hollow arms of the first U-shaped connecting rod, that is, a rectangular rotational pair mechanism is formed; The spring assembly is located above the rotational pair mechanism and limits the rotational angle of the rotational pair mechanism through the rebound force.

8. The manta ray-like underwater vehicle with active and passive deformation of pectoral fins according to claim 1, characterized in that: The driving joint is a motor or a steering gear.

9. A method for controlling a manta ray-like underwater vehicle with active and passive deformation of pectoral fins as claimed in any one of claims 1 to 8, characterized in that The specific steps are as follows: Initialize the amplitude, phase, and frequency parameters of the driven joint; The initialized parameters are output to the control module to calculate the amplitude and phase signals; Generate the angle signal of the driving joint according to the amplitude and phase signals; the expression is as follows: i i =r i (1+cos(φ i )) Among them, θ i represents the output angle of the i-th driving joint, r i represents the amplitude of the i-th driven joint, φ i represents the phase of the i-th driven joint; Transmit the angle signal of the driving joint to the driving joint and execute the angle control instruction; Detect the error between the output signal and the feedback signal, and adjust the angle control command of the driving joint according to the error until the error requirement is met.

10. The control method of a manta ray-like underwater vehicle with active and passive deformation of pectoral fins according to claim 9, characterized in that: The calculation formulas of the amplitude and phase signals are as follows: The phase equation is expressed as: Among them, φ i represents the phase of the i-th driven joint, φ i represents the phase of the jth driven joint, v i represents the frequency of driving the joint, w ij represents the coupling weight of the j-th driven joint to the i-th driven joint, Δφ ij represents the expected phase difference between the j-th driven joint and the i-th driven joint; The amplitude equation is expressed as: Among them, r i represents the amplitude of the i-th driven joint, a i Represents the coefficient that controls the convergence speed of the amplitude of the i-th driven joint, R i represents the desired amplitude of the i-th driven joint.

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