A tangential force direction identification airbag device based on air pressure response

Abstract

The application discloses a tangential force direction identification air bag device based on air pressure response and belongs to the technical field of flexible sensing and human-computer interaction. The device comprises a closed air-filled cavity composed of a flexible material, the inner wall of the closed air-filled cavity is connected with at least one directional reinforcing rib, all the directional reinforcing ribs extend along a first direction, so that the equivalent stiffness of the closed air-filled cavity in the first direction is greater than the equivalent stiffness of the closed air-filled cavity in a second direction perpendicular to the first direction; the closed air-filled cavity is connected with an air pressure sensor and a signal processing unit; when a tangential force is applied from different directions, the air bag deforms differently due to anisotropy of stiffness, so that the volume change difference in the closed air-filled cavity will lead to the air pressure change difference, and the tangential force direction is calculated accordingly. The application only needs a single air pressure sensor, has the advantages of simple structure, low cost, electromagnetic interference resistance, strong environmental adaptability, programmable direction response and the like, and is suitable for soft robot, intelligent artificial limb and safe human-computer cooperation system.

Description

Technical Field

[0001] This invention relates to the field of flexible sensing and intelligent interaction technology, and in particular to an airbag device for recognizing the tangential force direction based on air pressure response. Background Technology

[0002] In modern intelligent systems, especially in fields such as soft robots, rehabilitation prostheses, collaborative robotic arms, virtual / augmented reality interactive devices, and smart wearable equipment, the ability to perceive the mechanical information of contact interfaces has become a core element for achieving safe, dexterous, and adaptive operation. Among these, the recognition of the direction of tangential force (i.e., the frictional or sliding force acting parallel to the contact surface) is particularly critical—it directly relates to the realization of advanced functions such as grasping stability assessment, sliding warning, texture recognition, gesture interpretation, and human-machine intent understanding.

[0003] Currently, industry and academia widely employ multi-axis force / tactile sensor arrays based on microelectromechanical systems (MEMS) or flexible electronics to acquire tangential force information. These sensors typically integrate piezoresistive, capacitive, piezoelectric, optical, or magnetoelastic sensing units on a substrate, combined with complex microstructures to decouple normal and tangential force components. While these electronic sensing technologies exhibit high measurement accuracy and spatial resolution in laboratory environments, their inherent limitations are becoming increasingly apparent in practical engineering applications. The structure is complex and the manufacturing cost is high. To achieve triaxial force decoupling, each sensing pixel typically needs to integrate at least three independent sensing elements and matching signal conditioning circuits. When building a large-area tactile array, the number of channels required increases dramatically, resulting in extremely complex wiring, difficult packaging, and low yield. In addition, microfabrication processes (such as photolithography, sputtering, and laser etching) are highly dependent on cleanroom environments and precision equipment, which keeps the cost per point high and makes it difficult to meet the demand for low-cost, high-volume production of consumer products.

[0004] Insufficient flexibility, stretchability, and durability. Most electronic sensors rely on rigid or semi-rigid material systems. Even when using flexible substrates such as polyimide (PI) and PDMS, the overall tensile strain they can withstand is usually low. However, when soft robots perform grasping, bending, or torsional movements, the surface often experiences local strain exceeding 20% ​​or even 50%. Under such large deformation conditions, electronic circuits are prone to breakage, delamination, or contact failure, leading to degradation or complete loss of sensing performance. In addition, repeated inflation and deflation, friction and wear, or environmental aging can also accelerate device fatigue and significantly shorten the service life.

[0005] Poor environmental robustness limits applicable scenarios. Electronic sensors are extremely sensitive to their working environment: in environments with strong electromagnetic interference (such as near motors, welding workshops, or MRI equipment), capacitive or inductive sensors are susceptible to noise contamination, resulting in a sharp drop in signal-to-noise ratio; in humid, oily, or liquid environments (such as food processing, surgery, or underwater operations), moisture or grease may seep into the circuitry, causing short circuits, corrosion, or dielectric drift; in high-radiation or extreme-temperature environments (such as nuclear power plants or space exploration), the performance of semiconductor materials is prone to irreversible degradation; in enclosed or vision-free conditions (such as inside pipes or in dark environments), sensors relying on optical principles completely fail; these limitations make it difficult for electronic tangential force sensors to operate reliably in critical fields such as Industry 4.0, medical rehabilitation, and special robots.

[0006] High power consumption and heavy data processing burden. High-density sensor arrays require continuous power to maintain signal acquisition and generate massive raw data streams, posing severe challenges to the computing power, memory bandwidth and energy consumption of embedded processors; this problem is particularly prominent in battery-powered mobile platforms (such as exoskeletons, drone robotic arms, and smart gloves), which severely limits the system's battery life and real-time performance.

[0007] The lack of inherent safety and biocompatibility poses a risk of electric shock to users in scenarios involving close human-computer interaction (such as rehabilitation training and elderly care). Furthermore, some electronic materials (such as heavy metals and organic solvent residues) fail to meet medical-grade biocompatibility standards, limiting their use in direct skin contact or implantable applications.

[0008] The shortcomings of the aforementioned electronic sensing technologies severely restrict their deployment and promotion in real-world scenarios. Summary of the Invention

[0009] To overcome the shortcomings of the prior art, the present invention aims to provide an airbag device for tangential force direction recognition based on air pressure response. By actively designing the geometry of the airbag and / or arranging directional reinforcing ribs inside the cavity, controllable mechanical anisotropy is introduced into the airbag structure, so that significantly different deformation dynamic behaviors are generated when tangential forces are applied in different directions. Thus, the passive calculation of the tangential force direction can be completed using only a single air pressure sensor; tangential force direction recognition can be achieved by detecting the air pressure response inside the cavity without any electronic sensing elements.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A tangential force direction recognition airbag device based on air pressure response includes a closed inflatable cavity 1 made of flexible material. At least one directional reinforcing rib 2 is connected to the inner wall of the closed inflatable cavity 1. All directional reinforcing ribs 2 extend along a first direction, such that the equivalent stiffness of the closed inflatable cavity 1 in the first direction is greater than the equivalent stiffness in a second direction perpendicular to the first direction. The closed inflatable cavity 1 is connected to the signal input of an air pressure sensor 3, and the output of the air pressure sensor 3 is connected to a signal processing unit 4. When a tangential force is applied from different directions, the anisotropy of stiffness causes different deformations in the airbag. Therefore, the difference in volume change within the closed inflatable cavity 1 will lead to a difference in air pressure change, and the tangential force direction is calculated accordingly.

[0011] The enclosed inflatable cavity 1 has an anisotropic second moment shape, which is elliptical, rectangular, L-shaped or T-shaped.

[0012] When the number of the directional reinforcing ribs 2 is one, it penetrates the geometric center of the closed air-filled cavity 1 along the first direction.

[0013] When there are two directional reinforcing ribs 2, they are arranged in parallel in the first direction, and the distance between the two reinforcing ribs is 1 / 3 to 1 / 2 of the length of the enclosed air-filled cavity 1 in the second direction.

[0014] When the number of directional reinforcing ribs 2 is greater than two, they are arranged in parallel in the first direction, and each reinforcing rib is evenly arranged in the second direction of the closed air-filled cavity 1.

[0015] The cross-section of the directional stiffener 2 is rectangular, with a width of 2 mm-6 mm and a thickness of 0.05 mm-0.2 mm.

[0016] The directional reinforcing rib 2 is made of a high-modulus flexible material, and its elastic modulus is 1 to 100 times that of the flexible material constituting the closed inflatable cavity 1.

[0017] The signal processing unit 4 receives the air pressure signal output by the air pressure sensor 3 and calculates the direction of the tangential force based on a preset classification rule.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This application is completely free of electronic sensing elements: abandoning traditional piezoresistive, capacitive, and other electronic arrays, it fundamentally solves problems such as high cost, easy damage, and poor anti-interference; dual anisotropic design freedom: it can achieve basic anisotropy through shape design (such as ellipse), or programmable and enhanced anisotropy through internal reinforcing ribs, or even the two in combination, flexibly adapting to different application scenarios; single-point air pressure signal can decouple direction: only one air pressure sensor is needed, the system is extremely simple, has low power consumption, and is easy to integrate; high environmental robustness: the air pressure signal is not affected by electromagnetic interference, oil, humidity, or light, and is suitable for harsh environments such as industrial, medical, underwater, and space; strong shape compatibility: it supports both symmetrical installation (circular + rib) and asymmetrical high-sensitivity design (ellipse) to meet diverse interface requirements; simple manufacturing process: it can be integrally formed by hot pressing, high-frequency welding, or 3D printing molds, suitable for low-cost mass production. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the air-filled cavity and internal directional reinforcing ribs in an embodiment of the present invention.

[0021] Figure 3 The graph shows the ABAQUS simulation results of an embodiment of the present invention.

[0022] In the diagram: 1. Enclosed inflation chamber; 2. Directional reinforcing rib; 3. Pressure sensor; 4. Signal processing unit. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0024] Reference Figure 1 and Figure 2 A tangential force direction identification airbag device based on air pressure response includes a closed inflatable cavity 1 made of flexible material. Seven directional reinforcing ribs 2 are connected to the inner wall of the closed inflatable cavity 1, all extending along a first direction, such that the equivalent stiffness of the closed inflatable cavity 1 in the first direction is greater than the equivalent stiffness in a second direction perpendicular to the first direction. The closed inflatable cavity 1 is connected to a signal input of a pressure sensor 3, which is used to detect the air pressure change signal inside the closed inflatable cavity 1 under the action of tangential force in real time. The output of the pressure sensor 3 is connected to a signal processing unit 4. When tangential force is applied from different directions, the anisotropy of stiffness causes different deformations in the airbag, resulting in differences in volume change within the closed inflatable cavity 1, which in turn leads to differences in air pressure change. Based on this, the direction of the tangential force can be calculated.

[0025] The enclosed inflatable cavity 1 has an anisotropic second moment and is elliptical in shape.

[0026] The directional reinforcing ribs 2 are arranged in parallel in the first direction, and each reinforcing rib is evenly arranged in the second direction of the closed air-filled cavity 1.

[0027] The cross-section of the directional stiffener 2 is rectangular, with a width of 2 mm-6 mm and a thickness of 0.05 mm-0.2 mm.

[0028] The directional reinforcing rib 2 is made of a high-modulus flexible material, and its elastic modulus is 1 to 100 times that of the flexible material constituting the closed inflatable cavity 1.

[0029] The signal processing unit 4 receives the air pressure signal output by the air pressure sensor 3 and calculates the direction of the tangential force based on a preset classification rule.

[0030] To verify the effectiveness of this invention, simulation analysis was performed using ABAQUS: Material of the enclosed inflatable cavity 1: Yeoh hyperelastic model (C10=0.04298, C20=-0.001366, C30=0.0006777); Directional stiffener 2 material: Yeoh hyperelastic model (C10=0.04298, C20=-0.001366, C30=0.0006777); Gas: Air, laminar flow, incompressible; The analysis process consists of three steps, all of which use dynamic display. The first step is to inflate the closed inflation chamber 1. The second step is to apply a certain normal stress to the closed inflation chamber 1. The third step is to apply a certain shear stress to the surface of the closed inflation chamber 1. The initial air pressure P = 0.015 MPa was obtained in the first analysis step for the sealed inflation chamber 1. In the second analysis step, the closed air-filled cavity 1 is subjected to a downward pressure of F1 = 20 N; In the third analysis step, a tangential force F2 = 12N is applied in five directions with angles of 0°, 22.5°, 45°, 67.5° and 90° to the first direction, respectively.

[0031] Simulation results: Figure 3This is a response curve of the air pressure inside the closed inflation chamber 1 during the third analysis step. The graph shows significant differences in air pressure changes under different tangential force directions. The reason for this is that the equivalent stiffness of the closed inflation chamber 1 is greatest in the 0° angle direction (the first direction). After being subjected to a certain tangential force, the deformation is small, resulting in a small volume change for the gas inside the closed inflation chamber 1, hence a small air pressure change, as shown by the lack of a significant downward trend in the air pressure curve. Similarly, in the 90° angle direction (the second direction), the equivalent stiffness of the closed inflation chamber 1 differs the most from that in the first direction. Therefore, after being subjected to the same magnitude of tangential force, the deformation is the greatest, leading to the largest volume expansion of the gas inside the closed inflation chamber 1. Thus, the air pressure shows a downward trend, and the decrease is more pronounced than in other directions.

[0032] In practical applications, thresholds can be set, or machine learning models (such as support vector machines, SVM) can be used to classify multi-dimensional features to achieve multi-directional or even continuous direction recognition.

Claims

1. A tangential force direction recognition airbag device based on air pressure response, characterized in that: The system includes a closed inflatable cavity (1) made of flexible material. The inner wall of the closed inflatable cavity (1) is connected to at least one directional reinforcing rib (2). All directional reinforcing ribs (2) extend along a first direction, so that the equivalent stiffness of the closed inflatable cavity (1) in the first direction is greater than the equivalent stiffness in the second direction perpendicular to the first direction. The closed inflatable cavity (1) and the air pressure sensor (3) are connected to the signal input. The output of the air pressure sensor (3) and the signal processing unit (4) are connected. When the tangential force is applied from different directions, the deformation of the airbag is different due to the anisotropy of stiffness. Therefore, the difference in volume change in the closed inflatable cavity (1) will lead to the difference in air pressure change. The direction of the tangential force is calculated accordingly.

2. The apparatus according to claim 1, characterized in that: The closed inflatable cavity (1) has an anisotropic second moment shape, which is elliptical, rectangular, L-shaped or T-shaped.

3. The apparatus according to claim 1, characterized in that: When the number of the directional reinforcing ribs (2) is one, they penetrate the geometric center of the closed air-filled cavity (1) along the first direction.

4. The apparatus according to claim 1, characterized in that: When there are two directional reinforcing ribs (2), they are arranged in parallel in the first direction, and the distance between the two reinforcing ribs is 1 / 3 to 1 / 2 of the length of the closed air-filled cavity (1) in the second direction.

5. The apparatus according to claim 1, characterized in that: When the number of the directional reinforcing ribs (2) is greater than two, they are arranged in parallel in the first direction, and each reinforcing rib is evenly arranged in the second direction of the closed air-filled cavity (1).

6. The apparatus according to claim 1, characterized in that: The cross-section of the directional stiffener (2) is rectangular, with a width of 2 mm-6 mm and a thickness of 0.05 mm-0.2 mm.

7. The apparatus according to claim 1, characterized in that: The directional reinforcing rib (2) is made of a high-modulus flexible material, and its elastic modulus is 1 to 100 times that of the flexible material constituting the closed inflatable cavity (1).

8. The apparatus according to claim 1, characterized in that: The signal processing unit (4) receives the air pressure signal output by the air pressure sensor (3) and calculates the direction of the tangential force based on the preset classification rules.

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