A signal acquisition circuit for a flexible sensor array for detecting plantar pressure

Abstract

The utility model relates to signal acquisition technical field especially, it is a kind of signal acquisition circuit of the flexible sensor array of detecting plantar pressure, the circuit includes flexible sensor array, and also includes host chip, multiplexing module, voltage conversion module, voltage division module, reset module, interface module, the multiplexing module is connected between the voltage division module with the flexible sensor array, for the screening conduction of the row / column of the flexible sensor array, the output end of voltage division module, the control end of the multiplexing module, reset module, interface module are connected with the host chip, the voltage conversion module is the flexible sensor array, the host control module, multiplexing module provides power input.

Description

Technical Field

[0001] This utility model relates to the field of signal acquisition technology, and in particular to a signal acquisition circuit for a flexible sensor array for detecting plantar pressure. Background Technology

[0002] Plantar pressure distribution detection has significant application value in fields such as medical rehabilitation, sports analysis, and footwear design. Traditional plantar pressure detection equipment typically uses rigid sensor arrays, which have the following technical drawbacks: limited array size: existing detection systems mostly use fewer than 16×16 channels, making it difficult to fully cover the biomechanical characteristic areas of the foot; low signal acquisition efficiency: point-by-point scanning acquisition methods result in insufficient sampling frequency, failing to meet the needs of dynamic pressure analysis, etc.

[0003] To address the aforementioned issues, existing technologies attempt to improve performance by optimizing the circuit design for signal acquisition. For example, Chinese patent CN204102123U discloses a multi-serial port data transceiver control circuit based on an STM32 microcontroller. However, the inventors of this application still face the following technical bottlenecks: the channel expansion of the high-density sensor array leads to a sharp increase in circuit complexity, and the traditional cascaded multiplexer method is difficult to achieve stable control; the nonlinear resistance characteristics of the flexible sensor result in insufficient signal conversion accuracy, affecting the accuracy of pressure measurement. Summary of the Invention

[0004] In view of the above-mentioned prior art, the present invention provides a signal acquisition circuit for a flexible sensor array for detecting plantar pressure, which mainly solves the technical problems existing in the background art.

[0005] To achieve the above objectives, the technical solution of this utility model embodiment is implemented as follows: a signal acquisition circuit for a flexible sensor array for detecting plantar pressure, the circuit including a flexible sensor array, a main control chip, a multiplexer module, a voltage conversion module, a voltage divider module, a reset module, and an interface module. The multiplexer module is connected between the voltage divider module and the flexible sensor array, and is used to filter and conduct rows / columns of the flexible sensor array. The output terminal of the voltage divider module, the control terminal of the multiplexer module, the reset module, and the interface module are all connected to the main control chip. The voltage conversion module provides power input to the flexible sensor array, the main control chip, and the multiplexer module.

[0006] Optionally, the multiplexing module includes seven multiplexing switch chips U10, U11, U12, U13, U14, U15, and U16. The control terminals of the multiplexing switch chips U10 to U16 are connected to the main control chip. The multiplexing switch chips U10, U11, and U12 are used to conduct the corresponding row signals of the flexible sensor array. The common output terminals of the multiplexing switch chips U13 to U15 are respectively connected to the Y2, Y1, and Y0 pins of U16. The common output terminal of the multiplexing switch chip U16 is connected to the main control chip.

[0007] Optionally, the multiple rows of sensors in the flexible sensor array are sequentially connected to the Y0 to Y7 pins of the multiplexing switch chips U10 to U12.

[0008] The multiple rows of sensors in the flexible sensor array are sequentially connected to the Y0 to Y7 pins of the multiplexer chips U13 to U15.

[0009] Optionally, the voltage conversion module includes chip U2, chip U3, filter capacitors C3-C9, and surface mount resistors R1-R2. The input terminal of chip U2 is connected to a +5V reference voltage, and its output terminal generates a -5V voltage, which is grounded through the parallel filter capacitors C3-C5.

[0010] The input terminal of the chip U3 is connected to a +5V reference voltage, and its output terminal generates a +3.3V voltage, which is regulated by filter capacitors C6-C9.

[0011] Optionally, the voltage divider module includes terminals for connecting reference resistors with different resistance values.

[0012] Optionally, the reset module consists of a reset button, a capacitor C2, and a bidirectional trigger diode. One end of the reset button is connected to the main control chip, and the other end is grounded. The capacitor C2 and the bidirectional trigger diode are both connected in parallel with the reset button.

[0013] Optionally, the interface module uses a USB-C-TYPE connector.

[0014] The beneficial effects of this utility model are as follows: 1) It uses the ESP32 main control chip and peripheral circuits to realize the signal acquisition of the pressure sensor array, and can also send data to the host computer through wireless data transmission. It has the advantages of high integration, complete functions and miniaturized circuit.

[0015] 2) Multiplexing switches are used to filter and process a large number of array signals. When converting the resistance signal of the pressure sensor array into a voltage signal, a selection and then voltage division method is adopted, which effectively improves the acquisition efficiency and saves resource costs.

[0016] 3) In the voltage divider circuit design, the reference resistor position is designed as a terminal that can be connected to different resistors. The reference resistor can be replaced according to the resistance changes of different pressure sensor arrays, and it has good adaptability to sensor arrays with different resistance ranges. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of this utility model.

[0018] Figure 2 This is a circuit diagram of the main control chip ESP32 and some of its peripheral circuits.

[0019] Figure 3 This is the circuit diagram of the interface module in this utility model.

[0020] Figure 4 This is a circuit diagram of the voltage conversion module in this utility model.

[0021] Figure 5 This is the pin circuit diagram for connecting all rows and columns of the pressure sensor array in this utility model.

[0022] Figure 6 This is a circuit diagram of the multi-channel selection module and the voltage divider module in this utility model.

[0023] Figure 7 This is the circuit diagram of the reset module in this utility model. Detailed Implementation

[0024] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this utility model belongs. The terminology used in this specification of this utility model is for the purpose of describing particular embodiments only and is not intended to limit the utility model. In the following description, the expression "some embodiments" refers to a subset of all possible embodiments; however, it should be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments and can be combined with each other without conflict.

[0025] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid confusion with the present invention.

[0026] It should be understood that this invention can be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of this invention to those skilled in the art. Furthermore, the terminology used herein is intended only to describe particular embodiments and is not intended to limit the invention. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “compose” and / or “comprising,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0027] It should also be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "inner," "outer," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0028] To fully understand this utility model, a detailed structure will be presented in the following description to illustrate the technical solution proposed by this utility model. Optional embodiments of this utility model are described in detail below; however, in addition to these detailed descriptions, this utility model may have other embodiments.

[0029] Please refer to the attached document. Figures 1 to 7 This application provides a signal acquisition circuit for a flexible sensor array for detecting plantar pressure. The circuit includes a flexible sensor array, a main control chip, a multiplexer module, a voltage conversion module, a voltage divider module, a reset module, and an interface module. The multiplexer module is connected between the voltage divider module and the flexible sensor array and is used to filter and conduct rows / columns of the flexible sensor array. The output terminal of the voltage divider module, the control terminal of the multiplexer module, the reset module, and the interface module are all connected to the main control chip. The voltage conversion module provides power input to the flexible sensor array, the main control chip, and the multiplexer module.

[0030] Specifically, the main control chip used in this application is an ESP32 chip. Two signal input / output pins of the ESP32 main control chip are electrically connected to the interface module for data communication. Simultaneously, the interface module provides a +5V reference voltage to the ESP32 main control chip. A voltage conversion module converts the +5V reference voltage to 3.3V as the turn-on voltage for the flexible sensor array, and similarly converts the +5V reference voltage to -5V. Both the +5V and -5V voltages serve as the input voltages for the multiplexer module. The ESP32 main control chip output pin controls the multiplexing module to sequentially select and conduct 24×24 signals. The selected single signal is input to the 12-bit ADC acquisition module built into the ESP32 main control chip in the form of a voltage divider circuit. After all signals are sequentially conducted and acquired by the multiplexing module, the sequential signal acquisition of each point of the pressure sensor array can be realized. The complete 576 data points acquired in one sequential acquisition are packaged and sent to the host computer through the built-in communication module. The host computer software parses the received data and intuitively reflects the spatial distribution characteristics of plantar pressure.

[0031] It should be noted that the method by which the host computer parses the received data and intuitively reflects the spatial distribution characteristics of plantar pressure is a conventional technical means in this field, and will not be described in detail in this embodiment.

[0032] The ESP32 microcontroller used in this application is a high-performance and low-power chip launched by Espressif Systems. This microcontroller is equipped with a diverse and powerful array of peripheral interfaces, integrating Wi-Fi and dual-mode Bluetooth, and is compatible with Bluetooth Class and Bluetooth Low Energy functions. It covers functions such as analog-to-digital converter (ADC), digital-to-analog converter (DAC), pulse width modulation (PWM), I2C, I2S audio interfaces, SPI serial peripheral interface, universal asynchronous transceiver (UART), and secure digital input / output (SD IO), fully meeting the needs of various IoT applications.

[0033] Furthermore, the main control chip ESP32 is model ESP32-S3-WROOM-1-N8R2, which has a built-in 12-bit ADC analog-to-digital converter, GPIO pin input / output, and WiFi communication module.

[0034] In addition, the flexible sensor array in this application is a 24×24 channel pressure sensor array, which is rectangularly distributed. The upper surface of the array connects the upper surfaces of each row of sensing units to bring out 24 row signals, and the lower surface of the array connects the lower surfaces of each column of sensing units to bring out 24 column signals. When the row signal on the upper surface and the column signal on the lower surface of a certain unit are both on, the pressure sensing unit will be connected to the voltage divider circuit as a variable resistor for the ESP32 main control chip to collect voltage signals. In the circuit, the 24 row signal lines and 24 column signal lines are connected through two 24-pin connectors.

[0035] In some embodiments, the multiplexing module includes seven multiplexing switch chips U10, U11, U12, U13, U14, U15, and U16. The control terminals of the multiplexing switch chips U10 to U16 are connected to the main control chip. The multiplexing switch chips U10, U11, and U12 are used to conduct corresponding row signals of the flexible sensor array. The common output terminals of the multiplexing switch chips U13 to U15 are respectively connected to the Y2, Y1, and Y0 pins of U16. The common output terminal of the multiplexing switch chip U16 is connected to the main control chip. The multiple rows of sensors in the flexible sensor array are sequentially connected to the Y0 to Y7 pins of the multiplexing switch chips U10 to U12. The multiple columns of sensors in the flexible sensor array are sequentially connected to the Y0 to Y7 pins of the multiplexing switch chips U13 to U15.

[0036] Specifically, the multiplexing module uses seven identical 74HC4051 multiplexing switch chips, namely U10 to U16. The 74HC4051 is an 8-channel analog multiplexer / demultiplexer with three digital selection inputs, namely pins S0 to S2, one active low enable input, namely the E interface pin, eight independent inputs / outputs, namely pins Y0 to Y7, and one common input / output, namely the Z interface pin.

[0037] Three multiplexer chips U10 to U12 control the selection of row signals. IO21, IO12, and IO13 in the ESP32 main control chip are connected to the digital selection inputs S2, S1, and S0 of the three multiplexer chips U10 to U12. The low enable input E# of multiplexer U10 is connected to IO16 in the ESP32 main control chip. Rows 0 to 7 of the sensor array are connected to the eight independent inputs / outputs (Y0 to Y7) of U10. The low enable input E# of multiplexer U11 is connected to IO15 in the ESP32 main control chip. Rows 8 to 15 of the sensor array are connected to the Y0 to Y7 pins of U11.

[0038] The low enable input terminal E# of the multiplexer U12 is connected to IO14 in the ESP32 main control chip, and rows 16 to 23 of the sensor array are connected to pins Y0 to Y7 of U12.

[0039] Connect the 3.3V voltage output from the voltage conversion module to the common input / output terminals of U10 to U12. The ESP32 main control chip outputs high and low level logic on IO21, IO12, IO13 and IO16, IO15, IO14 to open the corresponding channel of the chip, so that a certain row of the sensor is connected to the 3.3V power supply. For example: CS2=1; CS1=0; CS0=1; E0=1; E1=0; E2=1, then open the Y5 channel of U11, that is, connect the 13th row of the sensor array to 3.3V.

[0040] Similarly, for the selection of the control column signals of the four multiplexer chips U13 to U16, IO8, IO9, and IO10 of the ESP32 main control chip are connected to the digital selection inputs S2, S1, and S0 of the three multiplexer chips U13 to U15 respectively; IO5, IO6, and IO7 are connected to the digital selection inputs S2, S1, and S0 of the multiplexer chip U16 respectively. The three output terminals U13Z, U14Z, and U15Z of U13-U15 are connected to the Y2, Y1, and Y0 pins of U16 respectively. The active low enable inputs of U13-U16 are all grounded.

[0041] The column signals of the 24 arrays are sequentially connected from Y0 of U13, Y0 of U14, Y0 of U15, Y1 of U13, Y1 of U14, Y1 of U15, Y2 of U13, Y2 of U14, and Y2 of U15 to pins Y0 to Y7 of U13-U15. The ESP32 main control chip outputs high and low level logic on IO5, IO6, IO7 and IO8, IO9, IO10 to open the corresponding channel of the chip, so that a certain column of the sensor is connected to the circuit. For example: LS2=1; LS1=0; LS0=1; MS2=0; MS1=0; MS0=1, then the Y5 channel of U14 is opened, that is, the 16th column of the sensor array is connected to the circuit.

[0042] In some embodiments, the voltage conversion module includes chip U2, chip U3, filter capacitors C3-C9, and surface mount resistors R1-R2. The input terminal of chip U2 is connected to a +5V reference voltage, and its output terminal generates a -5V voltage, which is grounded through the parallel filter capacitors C3-C5.

[0043] The input terminal of the chip U3 is connected to a +5V reference voltage, and its output terminal generates a +3.3V voltage, which is regulated by filter capacitors C6-C9.

[0044] Specifically, chip U2 is a DC / DC converter LTC1983ES6-5 chip. Its pin 1 is connected to a +5V reference voltage, and its pin 2 outputs a -5V voltage. Filter capacitors C3 and C4 are connected to pins 1 and 2 respectively, and filter capacitor C5 is connected in parallel between pins 3 and 4. Pin 5 is grounded, and pin 6 is connected to a pull-up resistor, so that the pull-up voltage is 3.3V.

[0045] Chip U3 is an LM1117 I MPX-3.3 linear regulator. Pin 1 is grounded, pin 2 outputs 3.3V, and pin 3 is connected to a +5V reference voltage. Filter capacitors C6 and C7 are pulled down and connected to pin 3. Pin 4 is connected to the 3.3V voltage, filter capacitors C8 and C9 are pulled down and connected to pin 4, and resistor R1 and diode are pulled down and connected to pin 4.

[0046] In some alternative implementations, the voltage divider module includes terminals for connecting reference resistors of different resistance values.

[0047] Specifically, a reference resistor is connected to the reference circuit. When the pressure sensor array is connected to the circuit, the corresponding rows and columns are sequentially opened by a multiplexer module for filtering and conduction. At this time, the reference resistor and a conducting unit in the pressure sensor array form a voltage divider circuit. Through the voltage divider principle, the resistance change is mapped to a voltage change. Then, the 12-bit AD acquisition unit in the main control chip converts and stores the voltage change acquired at the current moment.

[0048] In some implementations, the reset module consists of a reset button, a capacitor C2, and a bidirectional trigger diode. One end of the reset button is connected to the main control chip, and the other end is grounded. The capacitor C2 and the bidirectional trigger diode are both connected in parallel with the reset button.

[0049] Furthermore, the interface module uses a USB-C-TYPE connector.

[0050] The above are merely specific embodiments of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. The protection scope of this utility model should be determined by the protection scope of the stated claims.

Claims

1. A signal acquisition circuit for a flexible sensor array for detecting plantar pressure, the circuit comprising a flexible sensor array, characterized in that, It also includes a main control chip, a multiplexer module, a voltage conversion module, a voltage divider module, a reset module, and an interface module. The multiplexer module is connected between the voltage divider module and the flexible sensor array, and is used to filter and conduct the rows / columns of the flexible sensor array. The output terminal of the voltage divider module, the control terminal of the multiplexer module, the reset module, and the interface module are all connected to the main control chip. The voltage conversion module provides power input to the flexible sensor array, the main control chip, and the multiplexer module.

2. The signal acquisition circuit for a flexible sensor array for detecting plantar pressure according to claim 1, characterized in that, The multiplexing module includes seven multiplexing switch chips U10, U11, U12, U13, U14, U15, and U16. The control terminals of the multiplexing switch chips U10 to U16 are connected to the main control chip. The multiplexing switch chips U10, U11, and U12 are used to conduct the corresponding row signals of the flexible sensor array. The common output terminals of the multiplexing switch chips U13 to U15 are respectively connected to the Y2, Y1, and Y0 pins of U16. The common output terminal of the multiplexing switch chip U16 is connected to the main control chip.

3. The signal acquisition circuit for a flexible sensor array for detecting plantar pressure according to claim 2, characterized in that, The multiple rows of sensors in the flexible sensor array are sequentially connected to the Y0 to Y7 pins of the multiplexer chips U10 to U12. The multiple rows of sensors in the flexible sensor array are sequentially connected to the Y0 to Y7 pins of the multiplexer chips U13 to U15.

4. The signal acquisition circuit for a flexible sensor array for detecting plantar pressure according to claim 3, characterized in that, The voltage conversion module includes chip U2, chip U3, filter capacitors C3-C9, and surface mount resistors R1-R2. The input terminal of chip U2 is connected to a +5V reference voltage, and its output terminal generates a -5V voltage, which is grounded through the parallel filter capacitors C3-C5. Its output terminal provides power input to the main control chip and the multiplexing module. The input terminal of the chip U3 is connected to a +5V reference voltage, and its output terminal generates a +3.3V voltage, which is regulated by filter capacitors C6-C9. Its output terminal provides power input to the flexible sensor array.

5. The signal acquisition circuit for a flexible sensor array for detecting plantar pressure according to claim 2, characterized in that, The voltage divider module includes terminals for connecting reference resistors with different resistance values.

6. The signal acquisition circuit for a flexible sensor array for detecting plantar pressure according to claim 1, characterized in that, The reset module consists of a reset button, a filter capacitor C2, and a bidirectional trigger diode. One end of the reset button is connected to the main control chip, and the other end is grounded. The filter capacitor C2 and the bidirectional trigger diode are both connected in parallel with the reset button.

7. The signal acquisition circuit for a flexible sensor array for detecting plantar pressure according to claim 1, characterized in that, The interface module uses a USB-C-TYPE connector.

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