Plane touch sensing system based on ultrasonic waves

Abstract

The invention provides a plane touch sensing system based on ultrasonic waves, and the system comprises a flexible electronic substrate which is of a flexible circuit structure, has the bending fitting capability, is used for supporting and connecting a transducer array, and provides a drive signal and a signal transmission path for the transducer array; the transducer array comprises a plurality of ultrasonic transducer units which are uniformly arranged on the flexible electronic substrate according to a matrix array mode, and the transducer array periodically emits ultrasonic waves upwards and receives ultrasonic echo signals reflected back from a medium above; the silica gel layer covers the transducer array and is used for simulating the soft touch feeling of a human hand touching an interface and generating controllable deformation under the action of pressing or external force, so that the propagation path and echo characteristics of the ultrasonic waves in the medium are changed; the flexible electronic substrate, the transducer array and the silica gel layer are sequentially laminated and integrally formed to form an integral sensing unit.

Description

Technical Field

[0001] The present invention relates to the field of tactile sensing technology, and in particular to an ultrasonic-based planar tactile sensing system. Background Art

[0002] Currently, mainstream tactile sensing systems mostly use passive sensing technologies such as voltage, resistance, and capacitance. The Chinese invention patent application number CN119573929A states that its tactile sensing device includes multiple neodymium iron boron magnetic structures and resistance measurement circuits. The processor identifies the size and position of external force based on changes in the resistance sequence, and has a certain tactile recognition capability.

[0003] Although this technology realizes the force recognition function at the structural level, it still has the following defects:

[0004] (1) The structure is too rigid to achieve flexible fit, making it unsuitable for wearable or curved touch scenarios;

[0005] (2) It relies on magnetoresistance changes as a sensing mechanism, which is easily affected by magnetic field interference and has poor signal stability;

[0006] (3) It is difficult to achieve high-density array layout, resulting in limited tactile spatial resolution;

[0007] (4) The response speed is slow, making it difficult to use for high-frequency dynamic tactile change detection.

[0008] Patent application CN104866098A discloses an ultrasonic tactile feedback system based on a capacitive ultrasonic sensor, comprising a capacitive ultrasonic sensor array, a control circuit, a drive circuit, and a computer. The computer controls the ultrasonic emission signal and loads it onto the capacitive ultrasonic sensor array units, causing each sensor unit to generate ultrasonic radiation fields of various amplitudes and phases in space. These interact to form several acoustic focal points that form the shape of a pre-determined virtual object. At this point, when the instrument projects the ultrasonic wave onto the hand, the person can feel it, thereby achieving tactile feedback. However, this patent fails to fully resolve existing technical issues and fails to meet the requirements of the present invention. Summary of the Invention

[0009] In view of the defects in the prior art, an object of the present invention is to provide a planar tactile sensing system based on ultrasound.

[0010] The ultrasonic-based planar tactile sensing system provided by the present invention includes:

[0011] The flexible electronic substrate is a flexible circuit structure with the ability to bend and conform to the environment. It is used to support and connect the transducer array and provide it with driving signals and signal transmission paths.

[0012] a transducer array comprising a plurality of ultrasonic transducer units uniformly arranged on the flexible electronic substrate in a matrix array manner, wherein the transducer array periodically transmits ultrasonic waves upward and receives ultrasonic echo signals reflected from the medium above;

[0013] The silicone layer covers the transducer array and is used to simulate the soft touch of a human hand touching the interface. It produces controllable deformation when pressed or subjected to external force, thereby changing the propagation path and echo characteristics of the ultrasonic wave in the medium.

[0014] The flexible electronic substrate, the transducer array and the silicone layer are stacked in sequence and integrally formed to form an overall sensing unit;

[0015] When the device is working, the transducer array emits an ultrasonic signal that enters the silicone layer and propagates. If there is no touch, the echo path is stable; when the silicone layer is pressed by the outside world, local deformation causes changes in echo time and amplitude. The data acquisition module obtains and transmits it to the signal processing module. After preprocessing and decoupling analysis, corresponding tactile feedback is formed to achieve high-precision two-dimensional tactile recognition.

[0016] Preferably, the circuit layout of the flexible electronic substrate adopts a serpentine routing design, the wire width is 50 μm to 100 μm, and the spacing between adjacent wires meets the following requirements:

[0017]

[0018] Among them, V max is the maximum driving voltage, t rise is the signal rise time, ε r is the dielectric constant of the substrate, and ε0 is the dielectric constant of vacuum.

[0019] Preferably, the transducer array is composed of M×N ultrasonic transducer units arranged in a matrix, wherein the value range of M and N is 10≤M, N≤100, and the resonant frequency of a single transducer unit is 1MHz to 10MHz.

[0020] Preferably, the driving signal of the transducer array is a pulse width modulation waveform, the width of a single pulse is 0.1 μs to 1 μs, the repetition frequency is 1 kHz to 100 kHz, and the emission phase difference between adjacent transducer units satisfies:

[0021]

[0022] Where Δx is the transducer spacing, θ is the beam deflection angle, and λ is the ultrasonic wavelength to achieve directional beamforming.

[0023] Preferably, the silicone layer is composed of three layers of silicone with different hardness, with a total thickness of 2mm to 10mm, wherein the hardness of the top layer is Shore A 10-20, the hardness of the middle layer is Shore A 30-50, and the hardness of the bottom layer is Shore A 60-80;

[0024] The top layer of the silica gel layer is provided with a microstructure array, which is a hemispherical protrusion with a diameter of 50 μm to 200 μm, a height of 20 μm to 100 μm, and a density of 100 to 500 per mm 2 .

[0025] Preferably, it also includes a signal processing module, including a data acquisition, preprocessing, decoupling analysis unit and a tactile imaging unit, for reconstructing the tactile distribution according to the time domain and spatial domain characteristics of the ultrasonic echo;

[0026] The transducer array periodically emits ultrasonic pulses and detects the echo time difference Δt and amplitude attenuation rate α caused by the deformation of the silicone layer, combined with the formula:

[0027]

[0028] Calculate the local deformation d, where v is the propagation speed of ultrasound in silicone, E eff is the elastic modulus after deformation, and E0 is the initial elastic modulus.

[0029] Preferably, the decoupling analysis unit adopts a spatial spectrum estimation technology, specifically including:

[0030] The spatial spectrum function is constructed by the phase difference of the array receiving signal:

[0031]

[0032] Among them, w i is the weight coefficient of the i-th transducer, d i is the array element spacing, k is the wave number;

[0033] Use the MUSIC algorithm to search for peaks in the spatial spectrum with a resolution of:

[0034]

[0035] To reconstruct the three-dimensional deformation field of the silicone layer.

[0036] Preferably, the tactile imaging unit matches the deformation pattern through a preset calibration database and optimizes the stress distribution using a bilinear interpolation algorithm. The interpolation formula is:

[0037]

[0038] Among them, f 11、f 12 、f 21 、f 22 The measured values ​​of four adjacent transducers are finally generated into a two-dimensional tactile distribution image with a resolution of ≥200dpi.

[0039] Preferably, a feature analysis and classification module is also included, which extracts the time-frequency features of the tactile signal through short-time Fourier transform and classifies it using the K-means clustering algorithm. The classification is based on:

[0040] Pressure change rate threshold: It is judged as a quick click, ΔP is the pressure change value, and Δt is the duration of the pressure change;

[0041] Contact duration threshold: t≥500ms is considered a long press;

[0042] When the frequency domain energy is concentrated in the range of 1kHz to 5kHz, it is determined to be a sliding operation.

[0043] Preferably, it also includes a dynamic change recognition module, which monitors the temporal evolution of signal features in real time through a sliding window, and captures the state transition law in combination with a hidden Markov model, so as to distinguish continuous gestures or intention switching.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The present invention provides a planar tactile sensing system based on ultrasound, which integrates an ultrasonic transducer array on a flexible substrate, forms a tactile sensing interface through multiple layers of silicone, and performs planar tactile perception in combination with changes in echo signals, thereby achieving highly sensitive, deformable, and flexible tactile sensing. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0047] Figure 1 This is a schematic diagram of the structure of a planar tactile sensing system based on ultrasound;

[0048] Figure 2 This is a schematic diagram of the structure of a planar tactile sensing system based on ultrasound;

[0049] In the figure, 1-flexible electronic substrate, 2-transducer array module, 3-silicone layer. DETAILED DESCRIPTION

[0050] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0051] Example

[0052] like Figure 2 The present invention provides a planar tactile sensing system based on the ultrasonic echo change recognition principle, comprising: a flexible electronic substrate 1, a transducer array 2, and a three-layer silicone layer 3, which are stacked in sequence and integrally formed to form an overall sensing unit.

[0053] The flexible electronic substrate 1 is a flexible circuit structure with bending and conforming capabilities, and is used to support and connect the transducer array and provide it with driving signals and signal transmission paths.

[0054] The transducer array 2 includes a plurality of ultrasonic transducer units, which are evenly arranged on the flexible electronic substrate 1 in a matrix array manner. The transducer array 2 periodically transmits ultrasonic waves upward and receives ultrasonic echo signals reflected from the medium above.

[0055] The silicone layer 3 covers the transducer array 2 and is used to simulate the soft touch of a human hand touching the interface. It produces controllable deformation when pressed or subjected to external force, thereby changing the propagation path and echo characteristics of the ultrasonic wave in the medium.

[0056] When the device is working, the transducer array 2 emits an ultrasonic signal that enters the silicone layer 3 and propagates. If there is no touch, the echo path is stable; when the silicone layer 3 is pressed by the outside world, local deformation causes changes in characteristics such as echo time and amplitude; these changes are acquired by the data acquisition module and transmitted to the signal processing module. After preprocessing and decoupling analysis, corresponding tactile feedback is formed to achieve high-precision two-dimensional tactile recognition.

[0057] The circuit layout of the flexible electronic substrate adopts a serpentine routing design, the wire width is 50μm to 100μm, and the spacing between adjacent wires meets the following requirements:

[0058]

[0059] Among them, V max is the maximum driving voltage, t rise is the signal rise time, ε r is the dielectric constant of the substrate, and ε0 is the dielectric constant of vacuum.

[0060] The transducer array is composed of M×N ultrasonic transducer units arranged in a matrix, wherein the value range of M and N is 10≤M, N≤100, and the resonant frequency of a single transducer unit is 1MHz to 10MHz.

[0061] The driving signal of the transducer array is a pulse width modulation waveform, with a single pulse width of 0.1μs to 1μs, a repetition frequency of 1kHz to 100kHz, and the emission phase difference between adjacent transducer units meets the following requirements:

[0062]

[0063] Where Δx is the transducer spacing, θ is the beam deflection angle, and λ is the ultrasonic wavelength to achieve directional beamforming.

[0064] The silicone layer is composed of three layers of silicone with different hardness, with a total thickness of 2mm to 10mm, wherein the hardness of the top layer is Shore A 10-20, the hardness of the middle layer is Shore A 30-50, and the hardness of the bottom layer is Shore A 60-80;

[0065] The top layer of the silica gel layer is provided with a microstructure array, which is a hemispherical protrusion with a diameter of 50 μm to 200 μm, a height of 20 μm to 100 μm, and a density of 100 to 500 per mm 2 .

[0066] The signal processing module includes data acquisition, preprocessing, decoupling analysis units and a tactile imaging unit, which is used to reconstruct the tactile distribution based on the time domain and spatial domain characteristics of the ultrasonic echo;

[0067] The transducer array periodically emits ultrasonic pulses and detects the echo time difference Δt and amplitude attenuation rate α caused by the deformation of the silicone layer, combined with the formula:

[0068]

[0069] Calculate the local deformation d, where v is the propagation speed of ultrasound in silicone, E eff is the elastic modulus after deformation, and E0 is the initial elastic modulus.

[0070] The decoupling analysis unit adopts spatial spectrum estimation technology, specifically including:

[0071] The spatial spectrum function is constructed by the phase difference of the array receiving signal:

[0072]

[0073] Among them, w i is the weight coefficient of the i-th transducer, d i is the array element spacing, k is the wave number;

[0074] Use the MUSIC algorithm to search for peaks in the spatial spectrum with a resolution of:

[0075]

[0076] To reconstruct the three-dimensional deformation field of the silicone layer.

[0077] The tactile imaging unit matches the deformation pattern through a preset calibration database and uses a bilinear interpolation algorithm to optimize the stress distribution. The interpolation formula is:

[0078]

[0079] Among them, f 11 、f 12 、f 21 、f 22 The measured values ​​of four adjacent transducers are finally generated into a two-dimensional tactile distribution image with a resolution of ≥200dpi.

[0080] like Figure 1 , for the workflow of software and hardware working together:

[0081] The transducer array module periodically transmits ultrasonic waves to the silicone layer 3 and receives echoes;

[0082] The data acquisition module samples the transducer echo signal and uploads it to the pre-processing module;

[0083] The preprocessing module performs denoising and normalization on the signal, extracts characteristic parameters and transmits them to the signal decoupling module;

[0084] The signal decoupling and tactile imaging module uses a single-beam emission method to control the ultrasonic sensor array, and reconstructs tactile information through directional emission and echo analysis. The reflected echoes received by the array carry time, spatial, and energy characteristic information at the same time. The system uses the phase difference of the array-received signals to construct a spatial spectrum function, and uses spatial spectrum estimation technology to reconstruct the three-dimensional deformation field inside the silicone layer. Then, a mechanical model is established based on the constitutive relationship of the silicone material, and the actual deformation pattern is matched through a preset calibration database. An interpolation algorithm is used to optimize the reconstruction accuracy of the stress distribution, finally obtaining a high-precision two-dimensional tactile distribution image.

[0085] It also includes a feature analysis and classification module to extract time-frequency features from the decoupled tactile signals, including key parameters such as pressure change rate, contact duration, and vibration frequency. Signals with similar features are then classified using a clustering algorithm (such as K-means) to form a library of interaction modes such as light touch, long press, and sliding. The classification is based on:

[0086] Pressure change rate threshold: It is judged as a quick click, ΔP is the pressure change value, and Δt is the duration of the pressure change;

[0087] Contact duration threshold: t≥500ms is considered a long press;

[0088] When the frequency domain energy is concentrated in the range of 1kHz to 5kHz, it is determined to be a sliding operation.

[0089] It also includes a dynamic change recognition module, which monitors the temporal evolution of signal features in real time through a sliding window, and combines the hidden Markov model (HMM) to capture state transition rules, thereby distinguishing continuous gestures (such as zooming and rotating) or intention switching (such as switching from clicking to dragging).

[0090] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0091] Those skilled in the art will appreciate that, in addition to implementing the system, device, and various modules provided by the present invention in purely computer-readable program code, it is entirely possible to implement the same program in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, embedded microcontrollers, and the like by logically programming the method steps. Therefore, the system, device, and various modules provided by the present invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered structures within the hardware component; the modules for implementing various functions can also be considered both software programs for implementing the method and structures within the hardware component.

[0092] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A planar tactile sensing system based on ultrasound, characterized in that: include: The flexible electronic substrate is a flexible circuit structure with the ability to bend and conform to the environment. It is used to support and connect the transducer array and provide it with driving signals and signal transmission paths. a transducer array comprising a plurality of ultrasonic transducer units uniformly arranged on the flexible electronic substrate in a matrix array manner, wherein the transducer array periodically transmits ultrasonic waves upward and receives ultrasonic echo signals reflected from the medium above; The silicone layer covers the transducer array and is used to simulate the touch of a human hand touching the interface. It produces controllable deformation when pressed or subjected to external force, thereby changing the propagation path and echo characteristics of the ultrasonic wave in the medium. The flexible electronic substrate, the transducer array and the silicone layer are stacked in sequence and integrally formed to form an overall sensing unit; When the device is working, the transducer array emits an ultrasonic signal that enters the silicone layer and propagates. If there is no touch, the echo path is stable; when the silicone layer is pressed by the outside world, local deformation causes changes in echo time and amplitude. The data acquisition module obtains and transmits it to the signal processing module. After preprocessing and decoupling analysis, corresponding tactile feedback is formed to achieve two-dimensional tactile recognition.

2. The ultrasonic-based planar tactile sensing system according to claim 1, characterized in that: The circuit layout of the flexible electronic substrate adopts a serpentine routing design, the wire width is 50μm to 100μm, and the spacing between adjacent wires meets the following requirements: Among them, V max is the maximum driving voltage, t rise is the signal rise time, ε r is the dielectric constant of the substrate, and ε0 is the dielectric constant of vacuum.

3. The ultrasonic-based planar tactile sensing system according to claim 1, wherein: The transducer array is composed of M×N ultrasonic transducer units arranged in a matrix, wherein the value range of M and N is 10≤M, N≤100, and the resonant frequency of a single transducer unit is 1MHz to 10MHz.

4. The ultrasonic-based planar tactile sensing system according to claim 1, wherein: The driving signal of the transducer array is a pulse width modulation waveform, with a single pulse width of 0.1μs to 1μs, a repetition frequency of 1kHz to 100kHz, and the emission phase difference between adjacent transducer units meets the following requirements: Where Δx is the transducer spacing, θ is the beam deflection angle, and λ is the ultrasonic wavelength to achieve directional beamforming.

5. The ultrasonic-based planar tactile sensing system according to claim 1, wherein: The silicone layer is composed of three layers of silicone with different hardness, with a total thickness of 2mm to 10mm, wherein the hardness of the top layer is Shore A 10-20, the hardness of the middle layer is Shore A 30-50, and the hardness of the bottom layer is Shore A 60-80; The top layer of the silica gel layer is provided with a microstructure array, which is a hemispherical protrusion with a diameter of 50 μm to 200 μm, a height of 20 μm to 100 μm, and a density of 100 to 500 per mm 2 .

6. The ultrasonic-based planar tactile sensing system according to claim 1, characterized in that: It also includes a signal processing module, including data acquisition, preprocessing, decoupling analysis units and a tactile imaging unit, for reconstructing tactile distribution based on the time domain and spatial domain characteristics of the ultrasonic echo; The transducer array periodically emits ultrasonic pulses and detects the echo time difference Δt and amplitude attenuation rate α caused by the deformation of the silicone layer, combined with the formula: Calculate the local deformation d, where v is the propagation speed of ultrasound in silicone, E eff is the elastic modulus after deformation, and E0 is the initial elastic modulus.

7. The ultrasonic-based planar tactile sensing system according to claim 6, characterized in that: The decoupling analysis unit adopts spatial spectrum estimation technology, specifically including: The spatial spectrum function is constructed by the phase difference of the array receiving signal: Among them, w i is the weight coefficient of the i-th transducer, d i is the array element spacing, k is the wave number; Use the MUSIC algorithm to search for peaks in the spatial spectrum with a resolution of: To reconstruct the three-dimensional deformation field of the silicone layer.

8. The ultrasonic-based planar tactile sensing system according to claim 6, characterized in that: The tactile imaging unit matches the deformation pattern through a preset calibration database and optimizes the stress distribution using a bilinear interpolation algorithm. The interpolation formula is: Among them, f 11 、f 12 、f 21 、f 22 The measured values ​​of four adjacent transducers are finally generated into a two-dimensional tactile distribution image with a resolution of ≥200dpi.

9. The ultrasonic-based planar tactile sensing system according to claim 1, wherein: It also includes a feature analysis and classification module, which extracts the time-frequency features of tactile signals through short-time Fourier transform and uses the K-means clustering algorithm for classification. The classification is based on: Pressure change rate threshold: It is judged as a quick click, ΔP is the pressure change value, and Δt is the duration of the pressure change; Contact duration threshold: t≥500ms is considered a long press; When the frequency domain energy is concentrated in the range of 1kHz to 5kHz, it is determined to be a sliding operation.

10. The ultrasonic-based planar tactile sensing system according to claim 1, characterized in that: It also includes a dynamic change recognition module, which monitors the temporal evolution of signal features in real time through a sliding window, and combines the hidden Markov model to capture the state transition rules, thereby distinguishing continuous gestures or intention switching.

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