A touch sensing device based on pvdf piezoelectric film and its recognition algorithm

Abstract

This invention discloses a tactile sensing device based on a PVDF piezoelectric film, comprising a sensor body, a signal acquisition circuit, and a data processing module. The sensor body includes, from top to bottom, an upper PVDF piezoelectric film, a first electrode array, a flexible dielectric layer, a second electrode array, and a lower PVDF piezoelectric film. The input terminal of the signal acquisition circuit is connected to and acquires the signal collected by the sensor body, and the output terminal of the signal acquisition circuit is connected to and outputs the collected signal to the data processing module. This invention integrates mutual capacitance position sensing and PVDF piezoelectric dynamic sensing into the same flexible stacked structure, enabling simultaneous touch position detection, pressure holding state recognition, dynamic force change characterization, and tactile event recognition. It is suitable for scenarios such as flexible human-computer interaction, wearable devices, electronic skin, and tactile information acquisition.

Description

Technical Field

[0001] This invention relates to the field of flexible tactile sensing and information processing technology, specifically to a tactile sensing device and its recognition algorithm that combines PVDF piezoelectric response with mutual capacitance detection. Background Technology

[0002] Existing flexible tactile sensors are mostly based on a single sensing mechanism such as piezoresistive, capacitive, piezoelectric, or triboelectric. Different sensing mechanisms have their own characteristics in acquiring tactile information. Among them, capacitive schemes are more suitable for position detection and pressure holding state recognition, while piezoelectric schemes are more suitable for characterizing the dynamic response during the establishment of tactile events, force changes, and release processes.

[0003] For tactile tasks that require simultaneous acquisition of touch position, press hold state, and dynamic force change information, a single sensing mechanism is usually insufficient. Furthermore, array-type tactile devices also suffer from problems such as interlayer coupling, signal crosstalk, and high system integration complexity in practical applications. For example, the published document CN120141687A, entitled "An Array-Type Flexible Tactile Sensor, Its Fabrication Method, and Tactile Sensing System," discloses an array-type flexible tactile sensor comprising several arrayed flexible tactile sensor units, which, from top to bottom, include a friction layer, a hydrophilic layer, an electrode layer, and a substrate layer, wherein the lower surface of the friction layer is a hydrophilic surface.

[0004] Therefore, it is necessary to propose a tactile sensing device and its recognition algorithm that is lightweight, easy to flexibly fabricate, and capable of simultaneously realizing position detection, pressure holding state recognition, and dynamic force change characterization. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to realize a tactile sensing device and its recognition algorithm based on PVDF piezoelectric film, so as to solve the problem that existing single-sensing-mechanism tactile sensors cannot simultaneously take into account touch position recognition, continuous pressure holding detection and dynamic force change characterization.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a tactile sensing device based on a PVDF piezoelectric film, comprising a sensor body, a signal acquisition circuit, and a data processing module. The sensor body comprises, from top to bottom, an upper PVDF piezoelectric film, a first electrode array, a flexible dielectric layer, a second electrode array, and a lower PVDF piezoelectric film stacked sequentially. The input terminal of the signal acquisition circuit is connected to and acquires the signal acquired by the sensor body, and the output terminal of the signal acquisition circuit is connected to and outputs the acquired signal to the data processing module.

[0007] The first electrode array and the second electrode array are arranged opposite to each other and separated by the flexible dielectric layer. The first electrode array and the second electrode array together form a matrix mutual capacitance sensing unit.

[0008] The corresponding electrode units of the first electrode array and the second electrode array are arranged in a non-overlapping manner.

[0009] The upper PVDF piezoelectric film serves as a dynamic piezoelectric response output layer. When subjected to changes in force, it outputs a piezoelectric response signal for sampling by the piezoelectric signal acquisition module. This signal is used to characterize the dynamic response information during the pressing, force change, and release processes.

[0010] The lower PVDF piezoelectric film serves as a flexible support layer and interlayer structure carrier, supporting the second electrode array and working together with the flexible dielectric layer to maintain the stability of the overall sensor stack structure.

[0011] The signal acquisition circuit is equipped with a capacitive signal acquisition module and a piezoelectric signal acquisition module;

[0012] The capacitance signal acquisition module is connected to the first electrode array and the second electrode array. It is used to scan and acquire the matrix mutual capacitance sensing unit according to a preset scanning order to obtain capacitance change data of each sensing node, and realize touch position detection and press hold state recognition based on the capacitance change data.

[0013] The piezoelectric signal acquisition module is connected to the upper PVDF piezoelectric film. The piezoelectric signal acquisition module is used to sample the output signal of the upper PVDF piezoelectric film to characterize the dynamic response information during the pressing, force change and release processes.

[0014] The first electrode array and the second electrode array adopt an array-type electrode arrangement structure or a discrete electrode unit structure.

[0015] The data processing module is used to synchronously process the capacitance change data and piezoelectric timing data. Specifically, it determines the touch position based on the mutual capacitance matrix response, identifies the press-hold state based on the duration and amplitude changes of capacitance offset, and realizes dynamic force information characterization based on piezoelectric response characteristics combined with mechanical calibration relationships. The mechanical calibration is to obtain the correspondence between piezoelectric output and force by applying different known loads and establish a press force estimation model. The data processing module is used to output the touch position, press-hold state, and tactile event category according to the processing results.

[0016] A recognition algorithm for a tactile sensing device based on PVDF piezoelectric thin film includes the following steps:

[0017] Step 1: Real-time synchronous acquisition of capacitance change data and piezoelectric timing data

[0018] Step 2: Obtain the touch position and pressing time window by using capacitance change data, and obtain the dynamic force characteristics by using piezoelectric timing data;

[0019] Step 3: Time-align the capacitive and piezoelectric features according to the pressing time window to construct multimodal features;

[0020] Step 4: Use a recognition model to identify the multimodal features and output the tactile event category.

[0021] This invention integrates mutual capacitance position sensing and PVDF piezoelectric dynamic sensing into the same flexible laminated structure, enabling simultaneous touch position detection, press hold state recognition, dynamic force change characterization, and tactile event recognition. It is applicable to scenarios such as flexible human-computer interaction, wearable devices, electronic skin, and tactile information acquisition. Attached Figure Description

[0022] The following is a brief explanation of the content and markings in each of the accompanying drawings in this specification:

[0023] Figure 1 This is a schematic diagram of the interlayer structure of the tactile sensing device based on PVDF piezoelectric thin film of the present invention;

[0024] Figure 2 This is a schematic diagram showing the non-overlapping arrangement of the first electrode array and the second electrode array of the present invention;

[0025] Figure 3 This is a block diagram of the dual-modal signal acquisition and processing of the present invention;

[0026] Figure 4 This is a flowchart of the recognition algorithm of the present invention;

[0027] The markings in the above figures are: 1. Upper PVDF piezoelectric film; 2. First electrode array; 3. Flexible dielectric layer; 4. Second electrode array; 5. Lower PVDF piezoelectric film. Detailed Implementation

[0028] The following description, with reference to the accompanying drawings, details the specific implementation of the present invention, including the shape and structure of each component, the relative positions and connections between the parts, the function and working principle of each part, the manufacturing process, and the operation and use methods, to help those skilled in the art to have a more complete, accurate, and in-depth understanding of the inventive concept and technical solution of the present invention.

[0029] The tactile sensing device based on PVDF piezoelectric film includes a sensor body, a signal acquisition circuit, and a data processing module. The signal acquisition circuit and data processing module are mainly used for data acquisition and data processing. The sensor body will be described in detail below.

[0030] like Figure 1 As shown, the sensor body is a double-layer flexible stacked structure, namely a capacitive-piezoelectric dual-modal tactile sensing device based on a double-layer PVDF flexible stacked structure. It simultaneously realizes mutual capacitance position detection, press-hold state recognition, and dynamic force information extraction based on the piezoelectric response of the upper PVDF in the same flexible stacked device. Tactile event recognition is realized through synchronous acquisition, time alignment, feature extraction, and recognition model. The sensor body comprises, from top to bottom, an upper PVDF piezoelectric film, a first electrode array, a flexible dielectric layer, a second electrode array, and a lower PVDF piezoelectric film. Specifically, a flexible dielectric layer is placed between the two PVDF piezoelectric films, and the first and second electrode arrays are respectively placed on the opposite inner surfaces of the two PVDF layers. The two electrode arrays together form a matrix mutual capacitance sensing unit, used to acquire the touch position and press-hold state. At the same time, the upper PVDF piezoelectric film serves as a dynamic piezoelectric response layer, acquiring dynamic response information during the press establishment, force change, and release processes through a piezoelectric signal acquisition module. The mutual capacitance matrix data and piezoelectric timing data are then synchronously processed, time-aligned, feature-extracted, and recognized for output, thereby achieving tactile event recognition through dual-modal information fusion.

[0031] The first electrode array and the second electrode array are arranged opposite to each other and separated by the flexible dielectric layer. Together they form multiple matrix mutual capacitance sensing units, and the corresponding upper and lower electrode units are arranged in a non-overlapping manner to reduce the additional coupling between adjacent nodes, improve the locality of position detection and channel independence, and the upper PVDF piezoelectric film is used to output a piezoelectric response signal when the force changes.

[0032] The two PVDF layers are not merely redundant; they have distinct functions. The upper PVDF piezoelectric film serves as a dynamic piezoelectric response output layer, outputting a piezoelectric response signal when subjected to changes in force. This signal is then sampled by the piezoelectric signal acquisition module to characterize the dynamic response information during the press-up, force change, and release processes. The lower PVDF piezoelectric film, in this application, is not the primary piezoelectric acquisition layer but mainly serves as a flexible support layer and interlayer structure carrier. It supports the second electrode array and, together with the flexible dielectric layer, maintains the stability of the overall sensor stack structure.

[0033] The first and second electrode arrays are arranged with corresponding upper and lower electrode units in a non-overlapping configuration to reduce additional coupling between adjacent nodes and improve the locality and channel independence of the matrix node response. Preferably, both the first and second electrode arrays adopt an array-type electrode arrangement structure and are centrally led out via leads to connect to an external acquisition circuit. Preferably, the capacitance signal is acquired using a matrix scanning method, and the piezoelectric signal is acquired using a multi-channel sampling method, and time alignment and fusion processing are performed under a unified time reference.

[0034] Both the first and second electrode arrays are disposed on the inner surfaces of the two PVDF layers, with the electrode layers located inside the stacked structure rather than exposed on the outermost layer. This design serves several purposes:

[0035] It helps protect the electrode layer;

[0036] Reduce the impact of external friction, contamination, and direct contact on the stability of the electrode layer;

[0037] It facilitates overall flexible packaging;

[0038] It facilitates the formation of a stable interlayer mutual capacitance structure.

[0039] The first electrode array and the second electrode array are not simply overlapping vertically, but rather arranged in a non-overlapping relative arrangement of corresponding electrode units. This feature directly corresponds to the following technical effects:

[0040] Reduce the additional coupling between adjacent nodes;

[0041] Improve the locality of matrix node responses;

[0042] Improve the channel independence of position detection;

[0043] Reduce crosstalk between adjacent channels;

[0044] This makes the response at the target contact point more concentrated.

[0045] The signal acquisition circuit includes a capacitance signal acquisition module connected to the first electrode array and the second electrode array, and a piezoelectric signal acquisition module connected to the upper PVDF piezoelectric film. The capacitance signal acquisition module is used to scan and acquire the matrix mutual capacitance sensing unit according to a preset scanning sequence to obtain capacitance change data of each sensing node, and realize touch position detection and press hold state recognition based on the capacitance change data. The piezoelectric signal acquisition module is used to sample the output signal of the upper PVDF piezoelectric film to characterize the dynamic response information during the press establishment, force change and release process.

[0046] The capacitance signal acquisition module is connected to the first and second electrode arrays to scan and acquire data from the matrix mutual capacitance sensing unit, obtaining capacitance change data for each sensing node. The capacitance channel primarily performs two tasks: touch position detection and press-and-hold state recognition.

[0047] The piezoelectric signal acquisition module is connected to the upper PVDF piezoelectric film and is used to sample the piezoelectric response signal output by the upper PVDF piezoelectric film. The piezoelectric channel is mainly used to characterize: the press-up process; the force change process; and the dynamic response during the release process.

[0048] In this scheme, the capacitive channel and the piezoelectric channel do not exist independently, but work together around the same tactile event: the capacitive channel first provides the touch position and the pressing time window; the piezoelectric channel then provides the dynamic force characteristics within the time window; finally, the data processing module performs time alignment and feature fusion on the dual-modal data.

[0049] The data processing module is used to synchronously process the capacitance change data and piezoelectric timing data. Specifically, it determines the touch position based on the mutual capacitance matrix response, identifies the press-hold state based on the duration and amplitude changes of capacitance offset, and realizes dynamic force information characterization based on piezoelectric response characteristics combined with mechanical calibration relationships. Mechanical calibration is to obtain the correspondence between piezoelectric output and force by applying different known loads, thereby establishing a press force estimation model. The data processing module is also used to output the touch position, press-hold state, and tactile event category according to the processing results.

[0050] A recognition algorithm based on a tactile sensing device includes the following steps:

[0051] Synchronous control is performed on the capacitance signal acquisition module and the piezoelectric signal acquisition module;

[0052] Collect mutual capacitance matrix data and piezoelectric timing data corresponding to the same tactile event;

[0053] The mutual capacitance matrix data is processed and the touch position and pressing time window are extracted. The piezoelectric timing data is processed and the dynamic force characteristics are extracted.

[0054] Multimodal features are constructed by aligning capacitive and piezoelectric features in time according to the pressing time window;

[0055] The recognition model is used to identify the multimodal features and output the tactile event category.

[0056] The aforementioned recognition algorithm is not an algorithm that exists independently of the device structure, but rather a processing flow based on the dual-modal tactile sensing device described in this application. The algorithm flow can be summarized as follows:

[0057] Synchronous control is performed on the capacitance signal acquisition module and the piezoelectric signal acquisition module to acquire mutual capacitance matrix data and piezoelectric timing data corresponding to the same tactile event;

[0058] The mutual capacitance matrix data is processed and the touch position and press time window are extracted.

[0059] Process the piezoelectric time series data and extract dynamic stress characteristics;

[0060] Multimodal features are constructed by aligning capacitive and piezoelectric features in time according to the pressing time window;

[0061] A recognition model is used to identify multimodal features and output tactile event categories or status labels.

[0062] This invention enables simultaneous touch position detection, press-hold state recognition, and dynamic force information representation within the same flexible stacked device. Compared to a single capacitor solution, it enhances the ability to acquire dynamic force change information; compared to a single piezoelectric solution, it adds position detection and sustained press state recognition capabilities; and compared to a simple stacked multimodal solution, it provides a clearer division of structural functions and a more defined acquisition path. By arranging corresponding upper and lower electrode units in a non-overlapping manner, the locality of position detection and channel independence are improved, reducing additional coupling between adjacent nodes; by sampling piezoelectrically only from the upper PVDF layer, the source of dynamic response is clearly identified, and the acquisition path is simplified; and by synchronously acquiring dual-modal data and aligning the press time window, subsequent recognition becomes more targeted.

[0063] The following is a comparison and description of the tactile sensing device based on PVDF piezoelectric thin film of this invention with traditional sensing devices:

[0064] 1. Compared to traditional single-capacitive tactile sensors, which are generally good at position detection and static or quasi-static contact recognition, they are insufficient in representing dynamic information such as press establishment, force changes, and release processes. Even if capacitance changes can reflect the degree of contact, they often cannot directly reflect the dynamic process of force changes.

[0065] The difference between this solution and the previous one is that this solution is not a simple capacitor array, but rather introduces an upper-layer PVDF piezoelectric dynamic response into the same flexible stacked structure, so that the device can not only complete position detection and hold state recognition, but also obtain response information that is more sensitive to dynamic force processes.

[0066] 2. Compared to traditional single piezoelectric tactile sensors, which are typically sensitive to dynamic events but unsuitable for stably representing continuous pressing states, and also poor at mapping specific two-dimensional array positions, piezoelectric channels alone are usually insufficient to simultaneously determine "where the press is" and "whether the press is maintained."

[0067] The difference between this scheme and the previous one is that this scheme forms a matrix mutual capacitance sensing unit by using the first electrode array and the second electrode array. The capacitor channel is responsible for position detection and state recognition, and the upper PVDF provides dynamic response, thus realizing a clear division of labor and complementarity between the two sensing mechanisms.

[0068] 3. Compared to simple superimposed multimodal structures, some existing multimodal tactile devices simply arrange or superimpose different sensors, resulting in thick structures, strong coupling, large signal crosstalk, and unclear functional division.

[0069] The difference between this solution and the previous one is that this solution is designed as an integrated system around a double-layer PVDF flexible stacked structure. It forms a complete structure-acquisition-processing-identification link by setting the inner electrode, separating the flexible dielectric layer, arranging the corresponding upper and lower electrode units in a non-overlapping manner, and collecting data by the upper PVDF piezoelectric method. It is not a simple sensor splicing.

[0070] 4. Compared to the traditional top-bottom overlapping electrode structure, the larger overlapping area in the traditional top-bottom overlapping electrode structure may lead to stronger local coupling, but it can also easily lead to enhanced edge coupling of adjacent regions, resulting in larger non-target channel response and blurred position boundaries.

[0071] The difference between this scheme and the previous one is that this scheme explicitly adopts a non-overlapping arrangement of corresponding upper and lower electrode units, the purpose of which is to improve locality and channel independence, rather than simply pursuing enhanced node coupling.

[0072] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A tactile sensing device based on PVDF piezoelectric film, characterized by: The sensor body includes a sensor body, a signal acquisition circuit, and a data processing module. The sensor body comprises, from top to bottom, an upper PVDF piezoelectric film, a first electrode array, a flexible dielectric layer, a second electrode array, and a lower PVDF piezoelectric film. The input terminal of the signal acquisition circuit is connected to and acquires the signal acquired by the sensor body, and the output terminal of the signal acquisition circuit is connected to and outputs the acquired signal to the data processing module.

2. The tactile sensing device based on PVDF piezoelectric thin film according to claim 1, characterized in that: The first electrode array and the second electrode array are arranged opposite to each other and separated by the flexible dielectric layer. The first electrode array and the second electrode array together form a matrix mutual capacitance sensing unit.

3. The tactile sensing device based on PVDF piezoelectric thin film according to claim 2, characterized in that: The corresponding electrode units of the first electrode array and the second electrode array are arranged in a non-overlapping manner.

4. The tactile sensing device based on PVDF piezoelectric thin film according to claim 3, characterized in that: The upper PVDF piezoelectric film serves as a dynamic piezoelectric response output layer. When subjected to changes in force, it outputs a piezoelectric response signal for sampling by the piezoelectric signal acquisition module. This signal is used to characterize the dynamic response information during the pressing, force change, and release processes.

5. The tactile sensing device based on PVDF piezoelectric thin film according to claim 4, characterized in that: The lower PVDF piezoelectric film serves as a flexible support layer and interlayer structure carrier, supporting the second electrode array and working together with the flexible dielectric layer to maintain the stability of the overall sensor stack structure.

6. The tactile sensing device based on PVDF piezoelectric thin film according to any one of claims 1-5, characterized in that: The signal acquisition circuit is equipped with a capacitive signal acquisition module and a piezoelectric signal acquisition module; The capacitance signal acquisition module is connected to the first electrode array and the second electrode array. It is used to scan and acquire the matrix mutual capacitance sensing unit according to a preset scanning order to obtain capacitance change data of each sensing node, and realize touch position detection and press hold state recognition based on the capacitance change data. The piezoelectric signal acquisition module is connected to the upper PVDF piezoelectric film. The piezoelectric signal acquisition module is used to sample the output signal of the upper PVDF piezoelectric film to characterize the dynamic response information during the pressing, force change and release processes.

7. The tactile sensing device based on PVDF piezoelectric thin film according to claim 6, characterized in that: The first electrode array and the second electrode array adopt an array-type electrode arrangement structure or a discrete electrode unit structure.

8. The tactile sensing device based on PVDF piezoelectric thin film according to claim 7, characterized in that: The data processing module is used to synchronously process the capacitance change data and piezoelectric timing data. Specifically, it determines the touch position based on the mutual capacitance matrix response, identifies the press-hold state based on the duration and amplitude changes of capacitance offset, and realizes dynamic force information characterization based on piezoelectric response characteristics combined with mechanical calibration relationships. The mechanical calibration is to obtain the correspondence between piezoelectric output and force by applying different known loads and establish a press force estimation model. The data processing module is used to output the touch position, press-hold state, and tactile event category according to the processing results.

9. A recognition algorithm for a tactile sensing device based on a PVDF piezoelectric thin film, characterized in that, Includes the following steps: Step 1: Real-time synchronous acquisition of capacitance change data and piezoelectric timing data Step 2: Obtain the touch position and pressing time window by using capacitance change data, and obtain the dynamic force characteristics by using piezoelectric timing data; Step 3: Time-align the capacitive and piezoelectric features according to the pressing time window to construct multimodal features; Step 4: Use a recognition model to identify the multimodal features and output the tactile event category.

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