A robot frowning device based on deformation guiding constraint structure and a control method thereof

Abstract

The application provides a robot frowning device based on a deformation guiding constraint structure and a control method, which comprises a glabella biomimetic elastomer module, the glabella biomimetic elastomer module is fixed on a human eyebrow arch and a glabella bearing structure of a robot face; at least one group of traction components is arranged on the left and right sides respectively, the action part of the distal end of each group of traction components is connected with the eyebrow target area on the glabella biomimetic elastomer module; a driving module, the power output end of the driving module is connected with the driving part of the proximal end of the traction component; when the driving module drives the traction component, the left and right traction components can generate opposite traction forces synchronously, and drive the two eyebrow target areas to gather to the central glabella direction. The application also discloses a robot frowning expression control method. The application solves the technical problems of the frowning action of the biomimetic robot being stiff, the eyebrow expression being unnatural and the degree of reality being poor, and can improve the reality of human-computer interaction.

Description

Technical Field

[0001] This application relates to the technical field of bionic robots, and particularly to a robot bionic frowning device and control method based on a deformation-guided constraint structure. Background Art

[0002] In the simulation of facial expressions of bionic robots, frowning is a key micro-expression that conveys complex emotions such as confusion, concentration, dissatisfaction, etc. Its physiological process not only involves the bilateral eyebrows converging towards the root of the nose, but more crucially, under the traction of the underlying muscles and the constraint of the upper frontal bone structure, specific non-linear compression and longitudinal "Sichuan" character wrinkles are generated in the soft tissue of the glabellar skin.

[0003] In the prior art, a driving unit is mostly used to directly drive the movement of the "eyebrow substrate" attached to the surface of the simulation skin through a wire. The core idea of such a scheme is to drive a rigid or semi-rigid "proxy component", and rely on the movement of this component to带动 or压迫 the flexible skin thereon to generate a following deformation. Such a scheme has the following inherent defects:

[0004] 1. The deformation is passive and uncontrollable: The generated skin wrinkles depend on the compression of the substrate and the passive rebound of the skin material, and it is impossible to actively guide the direction, depth and shape of the wrinkles, resulting in random and unnatural wrinkles.

[0005] 2. The action mechanism is distorted: Human frowning is a controlled fold generated by the skin under the muscle tension and bone constraint, rather than a hard piece sliding or pressing on the skin. The existing scheme does not conform to the biological principle in terms of the action mechanism.

[0006] 3. The ceiling of the degree of simulation is low: Limited by the "driving component - following deformation" mode, it is difficult to simulate a vivid and natural continuous expression gradient that conforms to anatomical characteristics.

[0007] In summary, there is an urgent need for a robot frowning simulation scheme that can simulate human frowning, achieve natural skin wrinkles, and has a high degree of simulation. Summary of the Invention

[0008] The purpose of this application is to overcome the above-mentioned defects of the prior art and provide a bionic simulation scheme for robot frowning expressions that is innovative in terms of the action mechanism. The core idea of this application is: Abandon the traditional idea of "driving a proxy component", and instead adopt the method of "tracting a flexible body" combined with "intelligent fixed constraint", and through a simple underactuated system, actively guide and lock the flexible body to generate a precise deformation that conforms to biomechanical characteristics.

[0009] To achieve the above objectives, this application provides a robot bionic frowning device based on a deformation-guided constraint structure, comprising: a bionic elastomer module between the eyebrows, wherein the bionic elastomer module between the eyebrows is adapted and fixed to the robot's face on a bearing structure corresponding to the human brow ridge and between the eyebrows.

[0010] It includes at least one set of traction components respectively disposed on the left and right sides along the center line between the eyebrows, and the working part of the distal end of each set of traction components is connected to the eyebrow target area on the eyebrow bionic elastomer module;

[0011] The driving module has its power output end connected to the driving part near the traction component. When the driving module drives the traction component, it controls the left and right traction components to generate opposing traction forces synchronously, causing the target areas of the eyebrows on both sides to converge towards the central brow area. At the same time, the fixed deformation guiding constraint structure generates geometric interference and constraint on the brow bionic elastomer module converging towards the center, forcing it to have a wrinkling effect at the constraint point. This causes the brow area of ​​the brow bionic elastomer module to undergo compression deformation and longitudinal skin wrinkles, actively and predictably forming deformations that conform to longitudinal skin wrinkles, rather than irregular bulges.

[0012] A deformation-guided constraint structure is fixedly mounted on the eyebrow support structure; the slider of the deformation-guided constraint structure is connected to the strain layer of the eyebrow bionic elastomer module; when the eyebrow bionic elastomer module is subjected to traction and undergoes lateral compression, the slider and the slider connection part are restricted from displacement in the direction perpendicular to the skin surface, while the slider slides laterally, thereby guiding the eyebrow bionic elastomer module to generate longitudinal skin folds that conform to biomechanical characteristics.

[0013] Furthermore, the deformation-guided constraint structure consists of at least one transverse slot fixed to the eyebrow-mounted support structure. A slider is provided that mates with the slot, allowing the slider to slide along the transverse axis of the slot. The slider is connected to the strain layer of the biomimetic elastomer module.

[0014] When the traction component drive module converges towards the center, the cooperation between the slider and the lateral slot forms a constraint system:

[0015] 1. Lateral Sliding and Longitudinal Constraint: The slider is confined within the slot and can slide freely laterally (left-right) to accommodate the convergence movement. At the same time, the slot exerts a strong displacement constraint on the slider in the direction perpendicular to the skin surface.

[0016] 2. Strain concentration and directional swelling: Under the above constraints, when the glabella region is transversely compressed, the material connected to the slider cannot release the deformation upward due to the restriction of the longitudinal displacement, resulting in the concentration of compressive strain in the regions between adjacent sliders. When the material in these regions is transversely compressed and relatively free in the direction perpendicular to the skin surface, it is forced to undergo regular buckling and swelling outward from the skin.

[0017] 3. Precise fold formation: This controlled swelling process is transformed into one or more clear and lifelike longitudinal skin folds under the guidance of fixed constraint points. By designing parallel card slots and corresponding slider groups, the unique "Sichuan" character wrinkles on the human glabella can be reproduced.

[0018] Among them, when the driving module is configured to drive the traction component, it can control the traction components on the left and right sides to synchronously generate opposite traction forces, driving the target areas of the two sides of the eyebrows to converge towards the central glabella direction, so as to cause compressive deformation and longitudinal skin folds in the glabella region of the glabella bionic elastomer module.

[0019] Further, the traction component includes a traction rope, and the acting part at the distal end of the traction rope is connected to the target area of the eyebrow.

[0020] Further, the traction rope is one or a combination of high-strength fiber ropes and flexible webbing.

[0021] Further, the traction rope is a steel wire rope.

[0022] Further, the traction component further includes a guiding component, the traction rope is arranged in the channel of the guiding component, and the guiding component is used to constrain the movement path of the traction rope.

[0023] Further, the target area of the eyebrow includes the middle-eyebrow target area and the brow-head target area. The middle-eyebrow target area is outside the brow-head target area. There are two sets of traction components. One set of traction components is connected to the brow-head target area, and the downward pressing action of the brow-head position is realized by pulling the brow-head target area; the other set of traction components is connected to the middle-eyebrow target area, and the inward gathering action of the glabella part is realized by pulling the middle-eyebrow target area; the driving module can independently or coordinately control the two sets of traction components to realize the inward gathering and downward pressing actions of different parts of the eyebrows, and complete the continuous expression simulation from slight displeasure to deep anger.

[0024] Further, a deformation guiding and constraining structure is arranged at the near-glabella and / or glabella part of the glabella bionic elastomer module, and the deformation guiding and constraining structure is fixed on the glabella bearing structure to guide the glabella bionic elastomer module to generate deformation conforming to the longitudinal skin folds when being pulled.

[0025] Furthermore, the biomimetic elastomer module between the eyebrows includes a strain layer and a skin layer from the inside out; the strain layer is an elastic matrix embedded with a biomimetic reinforcing fiber network; the fiber network is radially distributed from the preset center of the eyebrow fold towards the eyebrow head and eyebrow tail.

[0026] Furthermore, the drive module includes a motor, a transmission mechanism, and a controller; the controller is used to control the operation of the motor according to the target expression parameters, and the motor converts the rotational motion into linear traction of the traction component through the transmission mechanism.

[0027] According to another aspect of this application, a robot biomimetic frowning control method based on a deformation-guided constraint structure is provided, applied to a biomimetic frowning device, characterized by comprising the following steps:

[0028] S1: Receive facial expression commands and parse them to obtain the cohesive displacement parameters and downward displacement parameters of the target areas of the left and right eyebrows;

[0029] S2: Based on the pre-established mapping model that includes the nonlinear mechanical characteristics and deformation guidance structure of the eyebrow biomimetic elastomer module, the displacement parameters are converted into the target stroke and traction force parameters of the traction component;

[0030] S3: Control and drive module, drive traction component to perform traction action, and coordinate the timing and force of the traction component action of the eyebrow target area and the eyebrow middle target area according to the expression intensity requirements;

[0031] S4: Under the action of the traction components, one set of traction components causes the eyebrow area of ​​the eyebrow bionic elastomer module to converge and generate compression wrinkles that conform to the preset shape, while another set of traction components pulls to make the target area in the eyebrow stable and press down, together to complete a natural and realistic robot frowning expression.

[0032] S5: After the expression is completed, the control drive module reverses to release the traction force, and the eyebrow bionic elastomer module automatically returns to its initial state based on the elasticity of its material and the restoring force of its internal fiber network.

[0033] In the embodiment of the present application, the controller controls the motor of the driving module to rotate, driving the transmission mechanism to rotate, thereby tightening the traction rope, and can control the traction components on the left and right sides to synchronously generate opposite traction forces, driving the target areas of the eyebrows on both sides to converge towards the center between the eyebrows. The deformation guiding and constraining structure in the middle remains stationary, and the slider can slide horizontally, thereby forming a wrinkled expression. The controller controls the rotation speed of the motor and the tightening length brought by the operation. When a certain period of time after the wrinkled expression is executed, the controller controls the motor to release synchronously. According to the elastic characteristics of the bionic elastic body module between the eyebrows, the eyebrows automatically return to the original state. The traction method is similar to the muscle pulling of a living being, with a higher degree of simulation and a smoother movement. The bionic elastic body module between the eyebrows can automatically recover according to the physical characteristics of the elastic body after the expression is completed, thereby solving the technical problems of the rigid driving of the frowning expression of the bionic robot, such as the生硬动作、表情不自然、拟真度差, and improving the realism of human-computer interaction.

[0034] The beneficial effects of the present application are: high bionic authenticity, smoother movement of the frowning expression, simple structure, capable of realizing the frowning movement, more conforming to the human facial anatomical structure, low cost, convenient installation and production, and high practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Structural schematic diagram of a bionic frowning device of a robot based on a deformation guiding and constraining structure according to an embodiment of the present invention;

[0036] Figure 2 Schematic diagram of the deformation guiding and constraining structure of a bionic frowning device of a robot based on a deformation guiding and constraining structure according to an embodiment of the present invention (one card slot);

[0037] Figure 3 Schematic diagram of the deformation guiding and constraining structure of a bionic frowning device of a robot based on a deformation guiding and constraining structure according to an embodiment of the present invention (two card slots), capable of forming two longitudinal "Chuan" character lines;

[0038] Figure 4 Logic flowchart of a control method for a bionic frowning device of a robot based on a deformation guiding and constraining structure according to an embodiment of the application;

[0039] Explanation of reference numerals: 1 - Bionic elastic body module between the eyebrows; 2 - Deformation guiding and constraining structure; 21 - Slider; 22 - Card slot; 3 - Traction component; 31 - Guide component; 32 - Traction rope; 4 - Target area of the eyebrows; 41 - Middle eyebrow target area; 42 - Brow head target area; 5 - Driving module; 51 - Motor; 52 - Transmission mechanism; 53 - Controller. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. The components of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0041] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0042] In this application, the terms "upper," "front," "rear," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0043] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0044] Furthermore, the terms "installed," "equipped with," and "connected" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0045] It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of protection of the invention. The present application will now be described in detail with reference to the accompanying drawings and embodiments.

[0046] Example 1

[0047] like Figure 1 As shown, this embodiment provides a robot-inspired frowning device based on a deformation-guided constraint structure, including a biomimetic elastomer module 1 between the eyebrows. This module 1 is adapted and fixed to the robot's face, corresponding to the human brow ridge and the supporting structure between the eyebrows; since it mimics a humanoid robot, the term "on the human brow ridge and the supporting structure between the eyebrows" is used. The biomimetic elastomer module 1 is made of an elastic material. The module 1 has an eyebrow target area 4 at the eyebrow position. The eyebrow positions, from the outside to the inside, are the eyebrow tail, the eyebrow middle, and the eyebrow head. In this invention, the eyebrow target area 4 refers to the eyebrow middle target area 41 and the eyebrow head target area 42. The supporting structure between the eyebrows resembles the human skull.

[0048] Traction components 3 are symmetrically arranged on the left and right sides along the center line between the eyebrows. Each traction component 3 includes a traction rope 32, the distal end of which is connected to the target eyebrow area 4. Figure 1 As shown in this embodiment, the traction component 3 consists of two symmetrically arranged traction ropes 32.

[0049] The eyebrow support structure has symmetrically arranged guide holes on both sides for threading the traction rope 32. The guide holes are located in the eyebrow target area 42 and the eyebrow center target area 41, and the traction rope 32 is a high-strength fiber rope.

[0050] The deformation-guided constraint structure 2 is fixedly mounted on the eyebrow support structure. Specifically, the deformation-guided constraint structure 2 consists of at least one transverse slot 22 fixed to the eyebrow support structure and a slider 21 that slides in cooperation with the slot. Multiple sliders are provided, including two or three. Each slider is connected to the strain layer of the eyebrow biomimetic elastomer module. The working mechanism of this structure is to allow the slider and the connected elastomer material to slide laterally (left-right) along the slot, but strictly restricts their displacement perpendicular to the skin surface.

[0051] Drive module 5, the power output end of drive module 5 is connected to the drive part near the traction assembly 3;

[0052] The driving module 5 is configured to drive the traction component 3, controlling the left and right traction components 3 to synchronously generate opposing traction forces, causing the target eyebrow areas 4 on both sides to converge towards the central eyebrow area, thereby causing lateral compression in the eyebrow area of ​​the eyebrow bionic elastomer module 1. During this process, the deformation guiding constraint structure 2 restricts the longitudinal displacement at the slider, forcing the compressive strain to concentrate in the area between the sliders and bulge upwards, forming longitudinal skin wrinkles. For example, the left traction component 3 passes through the thread hole of the left eyebrow target area 41 and connects to the right eyebrow target area 41, while the right traction component 3 passes through the thread hole of the right eyebrow target area 41 and connects to the left eyebrow target area 4, forming a cross and symmetrical arrangement. When this set of traction components 3 works, such as when tightening, it will synchronously generate opposing traction forces, thereby causing the target eyebrow areas 4 on both sides to converge towards the central eyebrow area, causing compression deformation and longitudinal skin wrinkles in the eyebrow area of ​​the eyebrow bionic elastomer module 1, resulting in a more natural expression.

[0053] The eyebrow-shaped bionic elastomer module 1 has a deformation-guiding constraint structure near or between the eyebrows. This structure is fixed to the eyebrow-supporting structure to guide the eyebrow-shaped bionic elastomer module 1 to deform in accordance with longitudinal skin folds when subjected to traction. The deformation-guiding constraint structure can be a horizontally arranged slot, with at least two slots. These slots connect the eyebrow-shaped bionic elastomer module 1 to the eyebrow-supporting structure, and the slots can be straight lines or lines with slight curvature.

[0054] The eyebrow biomimetic elastomer module 1 includes a strain layer and a skin layer from the inside out; the strain layer is an elastic matrix embedded with a biomimetic reinforcing fiber network; the fiber network is radially distributed from the preset eyebrow fold center towards the eyebrow head and eyebrow tail.

[0055] The drive module 5 includes a motor 51, a transmission mechanism 52, and a controller 53. The controller 53 controls the operation of the motor 51 according to the target facial expression parameters. The motor 51 converts rotational motion into traction of the traction component 3 along a predetermined trajectory via the transmission mechanism 52. The transmission mechanism 52 can be a cable reel. The motor 51 can be a servo motor or a miniature motor. The drive module 5 is fixed inside the skull. When performing a wrinkled facial expression, it pulls the target area 41 in the middle of the eyebrow.

[0056] In this embodiment, the motor 51, transmission mechanism 52, and traction rope 32 are all arranged symmetrically on the left and right.

[0057] The operation process of this embodiment is as follows: The controller 53 controls the left motor 51 to rotate, driving the transmission mechanism 52 to rotate, thereby tightening the left traction rope 32 and causing the right eyebrow target area 41 to tighten to the left. At the same time, the right motor 51 rotates, driving the transmission mechanism 52 to rotate, thereby tightening the right traction rope 32 and causing the left eyebrow target area 41 to tighten to the right. The deformation guiding constraint structure remains stationary, thus forming a wrinkled expression. The controller 53 controls the speed of the motor 51 and the tightening length caused by its operation. After the wrinkled expression is executed for a certain period of time, such as 1 second, the controller 53 controls the motor 51 to release synchronously. According to the elastic characteristics of the eyebrow bionic elastomer module 1, the eyebrows automatically return to their original state.

[0058] The key innovation of this embodiment lies in the introduction of a fixed deformation-guided constraint structure. Please refer to [link / reference]. Figure 2 This structure is not simply a mounting point; its core function is as follows:

[0059] 1. When the left and right traction ropes 32 tighten synchronously and drive the skin between the eyebrows to compress laterally, the structure forces the compressive strain to be transferred to the adjacent area that allows longitudinal deformation by restricting the longitudinal displacement of a specific point (slider), thereby precisely guiding the location and number of longitudinal wrinkles to form.

[0060] 2. This system eliminates the need for multiple complex driving points in the brow area to shape each wrinkle individually. It achieves the complex transformation from "in-plane contraction" to "vertical folds" simply through opposing traction on both sides, combined with guidance from a fixed constraint in the middle, demonstrating the design concept of "intelligent constraint-simplified driving."

[0061] 3. Biomechanical simulation: This structure simulates the rigid support and constraint that the human frontal bone exerts on the skin between the eyebrows. When frowning, the skin forms wrinkles in a specific direction precisely because of the constraint of the frontal bone surface. Therefore, this design is closer to real biomechanical principles at the structural level.

[0062] The deformation-guided constraint structure, which is formed by the horizontal slots and sliders fixed on the glabella support structure, is one of the core features for achieving precise guidance of vertical wrinkles.

[0063] The active formation process of longitudinal wrinkles:

[0064] 1. Drive input: The left and right traction components 3 generate opposing traction forces, driving the eyebrow area of ​​the eyebrow bionic elastomer module 1 to undergo lateral compression.

[0065] 2. Constraint Response: The slider fixed within the transverse groove is prohibited from bulging perpendicular to the skin, but can slide laterally along the groove to accommodate compression. This prevents the compressed elastomer material from releasing its deformation upwards at the slider's location.

[0066] 3. Buckling guidance: Compressive strain thus concentrates in the area between two adjacent sliders. The material in these areas undergoes regular upward (longitudinal) buckling bulges under the condition of being transversely compressed and having relatively free longitudinal movement.

[0067] 4. Wrinkle generation: The upward bulge in each "area between sliders" forms a longitudinal skin fold. Therefore, by setting N sliders, N - 1 longitudinal wrinkles can be actively guided to generate (for example, three sliders generate two "Chuan" character wrinkles). The transverse arrangement of the card slots directly presets the direction of the wrinkles, and the spacing and quantity of the sliders precisely control the spacing and quantity of the wrinkles.

[0068] Embodiment 2

[0069] The other parts are the same as those in Embodiment 1. The difference from Embodiment 1 is that there are two sets of the traction components 3. One set of the traction components 3 is connected to the target area 42 of the brow. By pulling the target area 42 of the brow, the downward movement of the brow position is achieved. For example, the left traction rope 32 passes through the left rope guiding hole and is connected to the target area 42 of the brow. Tightening the left traction rope 32 drives the left target area 42 of the brow to descend; the right traction rope 32 is connected to the right target area 42 of the brow. Tightening the right traction rope 32 drives the right target area 42 of the brow to descend; by pulling the target area 42 of the brow, the downward pressure of the eyebrows is achieved; the driving module 5 can independently or coordinately control the two sets of the traction components 3 to achieve the inward aggregation and downward pressure actions of different parts of the eyebrows, and complete the continuous expression simulation from slight displeasure to deep anger.

[0070] Embodiment 3

[0071] The difference from Embodiment 1 or Embodiment 2 is that the traction component 3 further includes a guiding component 31. The traction rope 32 is穿设于 (should be "disposed in") the channel of the guiding component 31, and the guiding component 31 is used to constrain the movement path of the traction rope 32. The guiding component 31 adopts a hollow tube, and the traction rope 32 is disposed in the channel of the hollow tube. The guiding component 31 is fixed inside the skull.

[0072] Embodiment 4

[0073] The difference from Embodiment 1 is that the traction rope 32 is an ultra-fine steel wire rope. The ultra-fine steel wire rope has higher strength and longer service life.

[0074] Embodiment 5

[0075] Multiple parallel transverse card slots can be provided on the glabella bearing structure to form a transverse card slot array. The slider can be designed to be detachable or movable and locked between different card slots.

[0076] Working principle and effect: By changing the installation position and number of sliders, the distribution pattern of constraint points can be dynamically adjusted. For example:

[0077] Sparse mode: Using only a few widely spaced sliders, it produces fewer but deeper vertical wrinkles, simulating deep anger or confusion.

[0078] Dense mode: Using multiple closely spaced sliders guides the generation of numerous and fine vertical wrinkles, simulating slight displeasure or focused thinking.

[0079] This physically adjustable constraint array allows the device to switch between various predetermined wrinkle patterns without the need for any additional drive units, simply through mechanical reconstruction. The system is simple yet expressive.

[0080] Example 6

[0081] According to another aspect of this application, a robot biomimetic frowning control method based on a deformation-guided constraint structure is also provided, applied to a biomimetic frowning device, characterized by comprising the following steps:

[0082] S1: Receive facial expression commands and parse them to obtain the cohesive displacement parameters and downward displacement parameters of the target areas of the left and right eyebrows;

[0083] First, the controller receives the frowning expression command sent by the host computer through a preset communication interface (such as CAN bus, Ethernet or serial port). This expression command is a digital command, which includes an expression type identifier (here, "frowning") and an expression intensity level (for example, divided into 1-5 levels, where level 1 is a slight frown and level 5 is a deep frown).

[0084] The controller internally stores a mapping table between facial expression intensity and displacement parameters. Based on the received facial expression intensity level, it analyzes and obtains the cohesive displacement parameters and downward displacement parameters of the target areas on the left and right eyebrows. Specifically, the cohesive displacement parameter refers to the distance the target areas in the middle of the left and right eyebrows move towards the center of the brow, and the downward displacement parameter refers to the distance the target areas at the inner corners of the eyebrows sink towards the eye socket. For example, when the facial expression intensity is level 3, the analyzed cohesive displacement parameters are 3.2mm for the left eyebrow and 3.2mm for the right eyebrow (symmetrical), and the downward displacement parameters are 2.5mm for the left eyebrow target area and 2.5mm for the right eyebrow target area. When the facial expression intensity is level 5, the cohesive displacement parameter increases to 4mm, and the downward displacement parameter increases to 3.5mm.

[0085] Meanwhile, the controller verifies the validity of the parsed displacement parameters to determine whether the parameters are within the preset safety threshold range (e.g., the maximum threshold for cohesive displacement is 4.8 mm, and the maximum threshold for downward displacement is 3.9 mm). If the parameters exceed the threshold, the command is discarded and an error message is fed back. If the parameters meet the requirements, the process proceeds to the next step.

[0086] S2: Based on the pre-established mapping model that includes the nonlinear mechanical characteristics and deformation guidance structure of the eyebrow biomimetic elastomer module, the displacement parameters are converted into the target stroke and traction force parameters of the traction component;

[0087] Because the biomimetic elastomer module between the eyebrows has nonlinear mechanical properties (i.e., its deformation and the applied traction force are not linearly related, with low stiffness in the small deformation stage and significantly increased stiffness in the large deformation stage), and because the deformation guiding structure constrains the traction direction, the traction component cannot be directly driven by displacement parameters. Therefore, a mapping model needs to be established in advance to achieve parameter conversion. The mapping model is a three-dimensional lookup table of displacement-stroke-traction force fitted based on experimental data.

[0088] In this embodiment, the mapping model is obtained by fitting a large amount of experimental data. Its inputs are the cohesive displacement parameters and downward displacement parameters analyzed in step S1, and the outputs are the target stroke and traction force parameters of the two sets of traction components. The process of establishing the mapping model is as follows: using high-precision displacement sensors and tension sensors, the actual stroke and corresponding traction force data of the traction components under different displacement inputs are collected respectively. Combined with the stress-strain curve of the eyebrow-shaped biomimetic elastomer module, the nonlinear mapping function is obtained by fitting using the least squares method and stored in the controller's storage unit.

[0089] The controller calls the mapping model described above, substituting the cohesive displacement parameters and downward displacement parameters obtained in step S1 into the mapping function to calculate the target stroke and traction force parameters of the two sets of traction components. For example, for a cohesive displacement of 3.0 mm for a level 3 facial expression intensity, the target stroke of the first set of traction components is converted to 3.0 mm, and the traction force parameter is 8.5 N; for a downward displacement of 2.5 mm, the target stroke of the second set of traction components is converted to 2.5 mm, and the traction force parameter is 6.2 N.

[0090] S3: Control and drive module, drive traction component to perform traction action, and coordinate the timing and force of the traction component action of the eyebrow target area and the eyebrow middle target area according to the expression intensity requirements;

[0091] Based on the target stroke and traction force parameters obtained in step S2, the controller generates a corresponding drive control signal and sends it to the drive module. In this embodiment, the drive module uses a servo motor drive unit, with one servo motor corresponding to each traction component. The servo motor is connected to the traction component through a ball screw mechanism to achieve precise control of traction force and stroke.

[0092] To achieve a natural and realistic frowning expression, the timing and force of the two sets of traction components need to be coordinated according to the intensity of the expression. Based on biomimetic research on human frowning movements, the preset timing rules are as follows: For a slight frown (intensity level 1-2), both sets of traction components are activated simultaneously, with the force steadily increasing to the target value; for a moderate to deep frown (intensity level 3-5), the first set of traction components (converging between the eyebrows) is activated first, followed by a 50-80ms delay before the second set of traction components (pressing down in the middle of the eyebrows), with the force increasing in a gradient manner to avoid abrupt movements. For example, for a level 5 frown, the traction force of the first set of traction components increases from 0N to 12.3N in a gradient increment of 0.5N, with each step lasting 20ms; the second set of traction components is activated after an 80ms delay, with the traction force increasing from 0N to 9.8N in a gradient increment of 0.4N, with each step lasting 20ms.

[0093] During the driving process, the encoder built into the servo motor collects the actual stroke data in real time and feeds it back to the controller.

[0094] S4: Under the action of the traction components, one set of traction components causes the eyebrow area of ​​the eyebrow bionic elastomer module to converge and generate compression wrinkles that conform to the preset shape, while another set of traction components pulls to make the target area in the eyebrow stable and press down, together to complete a natural and realistic robot frowning expression.

[0095] Under the control of the drive module, the two sets of traction components perform traction actions according to the coordinated timing and force:

[0096] The first set of traction components (corresponding to the glabella convergence) applies centripetal traction force to the inner endpoints of the left and right glabella biomimetic elastomer modules via traction ropes. Under the action of traction force, the biomimetic elastomer in the glabella region converges towards the center and is subjected to lateral compression. At this time, the deformation-guided constraint structure actively guides the release of compressive strain in the region between the sliders by limiting the longitudinal displacement at the sliders, forming longitudinal wrinkles. The internal radial fiber network helps to make the shape of these wrinkles smoother and more anatomically consistent.

[0097] The second traction component (corresponding to the downward pressure on the brow target area) acts on the biomimetic elastomer of the brow target area through the traction element. Under the guidance of the deformation guiding structure, it drives the brow target area to sink smoothly towards the eye socket. Because the movement of this traction component is coordinated with that of the first traction component, it ensures the stability and naturalness of the frowning expression.

[0098] After the two sets of traction components complete their movements, the shape formed by the bionic elastomer module between the eyebrows is consistent with the preset frowning expression. Visual observation verifies that the similarity between this expression and the real human frowning expression reaches more than 95%, with no obvious mechanical feel.

[0099] S5: After the expression is completed, the control drive module reverses to release the traction force, and the eyebrow bionic elastomer module automatically returns to its initial state based on the elasticity of its material and the restoring force of its internal fiber network.

[0100] When the frowning expression lasts for, for example, 1 second, the controller sends a reset command to the drive module, which controls the servo motor to reverse, causing the two sets of traction components to move in opposite directions and releasing the traction force applied to the bionic elastomer module between the eyebrows.

[0101] Because the biomimetic elastomer module between the eyebrows has elastic recovery characteristics, after the traction force is released, it automatically returns to its initial state (the flat shape when not frowning) by relying on the elastic force of its own material and the rebound tension of the internal fiber network. During the reset process, the controller receives stroke data fed back by the servo motor in real time. When it detects that both sets of traction components have returned to the initial position (stroke of 0mm), the control drive module stops working, completing the complete control process of one frowning expression.

[0102] In several embodiments of this application, the beneficial effects are as follows: high biomimicry realism, smoother frowning facial movements, simple structure, ability to realize frowning movements, better fit to the human facial anatomy, low cost, convenient installation and production, high practicality, improved realism of the robot in the scene, and greatly enhanced interactivity.

[0103] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A biomimetic frowning device for robots based on a deformation-guided constraint structure, characterized in that, include: The eyebrow bionic elastomer module (1) is adapted and fixed on the robot's face corresponding to the human brow arch and eyebrow support structure. The eyebrow bionic elastomer module (1) includes a strain layer and a skin layer from the inside to the outside. The strain layer is an elastic matrix embedded with a bionic reinforcing fiber mesh. The fiber mesh is radially distributed from the preset eyebrow fold center to the eyebrow head and eyebrow tail. The traction component (3) includes at least one set of traction components respectively disposed on the left and right sides along the center line between the eyebrows, and the working part of the distal end of each set of traction components is connected to the eyebrow target area (4) on the eyebrow bionic elastomer module. The drive module (5) is connected to the drive part near the traction component when the drive module (5) drives the traction component (3). The drive module (5) controls the left and right traction components to generate opposing traction forces synchronously, causing the target areas of the eyebrows on both sides to converge towards the central eyebrow area, thereby causing the eyebrow area of ​​the eyebrow bionic elastomer module (1) to undergo compression deformation and longitudinal skin wrinkles. A deformation guiding constraint structure (2) is fixedly installed on the eyebrow support structure. The deformation guiding constraint structure consists of at least one transverse slot fixed on the eyebrow support structure and is provided with a slider that cooperates with the slot, so that the slider can slide along the axis of the slot, and the axis of the slot is transverse. The slider (21) of the deformation guiding constraint structure (2) is connected to the strain layer of the eyebrow bionic elastomer module (1). When the eyebrow bionic elastomer module (1) is subjected to traction and transverse compression, the slider and the slider connection part are restricted from displacement in the direction perpendicular to the skin surface. At the same time, the slider slides transversely, thereby guiding the eyebrow bionic elastomer module to generate longitudinal skin folds that conform to biomechanical characteristics.

2. The bionic frowning device according to claim 1, characterized in that, The traction assembly includes a traction rope (32), the distal end of which is connected to the eyebrow target area (4).

3. The biomimetic frowning device according to claim 2, characterized in that, The traction rope (32) is one or more combinations of high-strength fiber rope or flexible webbing.

4. The biomimetic frowning device according to claim 2, characterized in that, The traction rope (32) is a steel wire rope.

5. The biomimetic frowning device according to claim 2, characterized in that, The traction assembly (3) further includes a guide assembly (31), in which the traction rope is threaded through the channel of the guide assembly, and the guide assembly is used to constrain the movement path of the traction rope.

6. The bionic frowning device according to claim 1, characterized in that, The traction component (3) consists of two sets. The eyebrow target area includes the middle eyebrow target area (41) and the eyebrow head target area (42). One set of traction components is connected to the eyebrow head target area and pulls the eyebrow head target area to achieve the downward movement of the eyebrow head position. The other set of traction components is connected to the middle eyebrow target area and pulls the middle eyebrow target area to achieve the inward movement of the eyebrow area. The driving module can independently or collaboratively control the two sets of traction components to achieve the inward and downward movement of different parts of the eyebrow, and complete the simulation of continuous facial expressions from slight displeasure to deep anger.

7. The bionic frowning device according to claim 1, characterized in that, The drive module (5) includes a motor (51), a transmission mechanism (52), and a controller (53); the controller is used to control the operation of the motor according to the target expression parameters, and the motor converts the rotational motion into linear traction of the traction component through the transmission mechanism.

8. A method for controlling a robot's frowning expression, applied to the bionic frowning device as described in any one of claims 1-7, characterized in that, Includes the following steps: S1: Receive facial expression commands and parse them to obtain the cohesive displacement parameters and downward displacement parameters of the target areas of the left and right eyebrows; S2: Based on the pre-established mapping model that includes the nonlinear mechanical characteristics and deformation guidance structure of the eyebrow biomimetic elastomer module, the displacement parameters are converted into the target stroke and traction force parameters of the traction component; S3: Control and drive module, drive traction component to perform traction action, and coordinate the timing and force of the traction component action of the eyebrow target area and the eyebrow middle target area according to the expression intensity requirements; S4: Under the action of the traction components, one set of traction components causes the eyebrow area of ​​the eyebrow bionic elastomer module to converge and generate compression wrinkles that conform to the preset shape, while another set of traction components pulls to make the target area in the eyebrow stable and press down, together to complete a natural and realistic robot frowning expression. S5: After the expression is completed, the control drive module reverses to release the traction force, and the eyebrow bionic elastomer module automatically returns to its initial state based on the elasticity of its material and the restoring force of its internal fiber network.

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