Multi-channel plantar pressure acquisition system

Abstract

The utility model discloses a multi-channel plantar pressure acquisition system, which consists of an FPC (Flexible Printed Circuit) substrate, a flexible sensor array, an FPGA (Field Programmable Gate Array) controller and a flexible flat cable. The FPC substrate is designed to be in an insole shape, and wiring of the flexible sensor is reserved. A rechargeable battery, a Bluetooth sending module, a signal acquisition module, an analog-to-digital conversion module and an FPGA control module are arranged in the FPGA controller. The flexible sensor array can comprehensively convert a plantar pressure signal into a voltage signal, and the flexible sensor array inputs the voltage signal into the FPGA controller through a plurality of leads; multiple paths of voltage signals are synchronously amplified, filtered and converted into digital quantity in the FPGA controller, and the digital quantity is sent to other equipment in a wireless mode. The multi-channel pressure sensor has the advantages that wearing is comfortable, response is sensitive, array arrangement is achieved, and plantar pressure can be rapidly and synchronously collected in a multi-channel mode.

Description

Technical Field

[0001] The utility model relates to the technical field of data acquisition, in particular to a multi-channel plantar pressure acquisition system. Background Art

[0002] The plantar pressure distribution can directly reflect the structure and function of the human foot and the control of the entire body posture. In recent years, it has begun to be widely used in clinical diagnosis, rehabilitation medicine, sports training, shoe design, robot control signals and other fields. It is necessary to pay attention to the research and application of plantar pressure. The plantar pressure acquisition array is based on piezoelectric sensor technology. Through multiple piezoelectric sensors distributed on the bottom of the insole, the pressure signal of the sole of the foot is converted into a measurable electrical signal. The plantar pressure signal processing unit is based on the programmable logic device FPGA. FPGA can not only realize highly parallel data processing and calculation, but also has a higher computing speed. Combined with the advantages of piezoelectric sensors such as fast response time, long life, stable performance and easy processing and installation, FPGA can collect and process plantar pressure data more comprehensively and at high speed.

[0003] Current portable plantar pressure collection systems suffer from low sampling rates, poor sensitivity, a limited number of pressure collection points, short sensor lifespan, and thermal instability. These issues lead to deficiencies in the accuracy, comprehensiveness, and real-time nature of data collection. Therefore, a plantar pressure collection system is proposed. Summary of the Invention

[0004] A plantar pressure acquisition system includes a flexible sensor array arranged on an insole-shaped flexible printed circuit board (FPC). The FPC transmits the electrical signal generated by the foot pressure to an FPGA controller via a flat cable connection. The FPGA controller converts and transmits the analog signal.

[0005] The technical problem to be solved by the present invention is to address the deficiencies in the above-mentioned prior art. The present invention provides a plantar pressure acquisition system, comprising an FPC substrate, a flexible sensor array, a cover layer, and an FPGA main control unit;

[0006] The FPC substrate is in the shape of a shoe insole; the flexible sensor array is arranged on the FPC substrate; the FPGA main control unit is connected to the flexible sensor array through leads; the FPGA main control unit includes a signal adjustment module, an analog-to-digital conversion module, an FPGA control module, a Bluetooth communication module and a DC power supply module; the output end of the DC power supply module is respectively connected to the power supply interfaces of the signal adjustment module, the analog-to-digital conversion module, the FPGA control module and the Bluetooth communication module; the input end of the signal adjustment module is connected to the flexible sensor array through leads, the output end of the signal adjustment module is connected to the input end of the analog-to-digital conversion module, the output end of the analog-to-digital conversion module is connected to the input end of the FPGA control module; the output end of the FPGA control module is connected to the input end of the Bluetooth communication module.

[0007] As a preferred solution of the present invention, the flexible sensor array includes a plurality of piezoelectric film sensors, and the plurality of piezoelectric film sensor arrays are arranged on an FPC substrate.

[0008] As a preferred solution of the present invention, the flexible sensor array is attached to the FPC substrate via conductive silver glue.

[0009] As a preferred solution of the present invention, the signal adjustment module includes a charge amplifier for amplifying the sensor signal, an active low-pass filter for filtering out high-frequency interference, and a 50 Hz notch filter for filtering out the voltage interference signal generated by the human body on the piezoelectric film sensor; the input end of the charge amplifier is connected to the flexible sensor array through a lead, and the output end of the charge amplifier is connected to the active low-pass filter; the output end of the active low-pass filter is connected to the input end of the 50 Hz notch filter, and the output end of the 50 Hz notch filter is connected to the analog-to-digital conversion module.

[0010] As a preferred embodiment of the present invention, the DC power supply module includes a rechargeable lithium battery and a voltage conversion circuit; the output end of the rechargeable lithium battery is connected to the signal adjustment module and the analog-to-digital conversion module via the voltage conversion circuit. More preferably, the rechargeable lithium battery is a 5V rechargeable lithium battery, and the voltage conversion circuit provides a voltage ranging from -5V to +5V to the signal adjustment module and the analog-to-digital conversion module, enabling the signal adjustment module to convert the voltage signal generated by the piezoelectric film sensor into a voltage range of -5V to +5V, and enabling the analog-to-digital conversion module to convert the voltage variation signal within the -5V to +5V voltage range into a corresponding numerical signal.

[0011] Compared with the prior art, the present invention has at least the following beneficial effects:

[0012] The flexible sensor array in this utility model accurately and sensitively converts plantar pressure into analog quantities for quantitative acquisition. The insole-shaped FPC is portable and comfortable, allowing for plantar pressure acquisition in a variety of motion conditions. The flexible sensor array comprises multiple flexible thin-film sensors, enabling pressure acquisition at multiple points, thus addressing the issue of limited pressure collection points. The flexible sensor array exhibits dynamic strain sensitivity, is lightweight, thin, passive, highly sensitive, has a wide measurement range, and is highly durable.

[0013] The FPGA control module uses parallel computing and can control the analog-to-digital conversion module to simultaneously convert analog quantities into digital quantities, improving data processing efficiency. This utility model can be used for plantar pressure collection, achieving long-term wear, accurate measurement, and comprehensive and high-speed collection and transmission of plantar pressure data. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] For ease of explanation, the present invention is described in detail with reference to the following specific implementations and accompanying drawings.

[0015] Figure 1 It is a structural diagram of the present utility model.

[0016] Figure 2 This is a schematic diagram of the data processing system of the present utility model.

[0017] In the figure: 1. FPC substrate; 11. Lead; 2. Flexible sensor array; 21. Piezoelectric film sensor; 3. FPGA main control unit; 31. Signal adjustment module; 32. Analog-to-digital conversion module; 33. FPGA control module; 34. Bluetooth communication module; 35. DC power supply module. DETAILED DESCRIPTION

[0018] The present invention will be further described and illustrated below in conjunction with specific embodiments. The embodiments are merely illustrative of the present disclosure and do not limit its scope. The technical features of the various embodiments of the present invention may be combined accordingly, provided that there is no conflict between them.

[0019] The plantar pressure collection principle of the multi-channel plantar pressure collection system of the present invention is that when the plantar pressure changes, the PDVF film will generate a voltage change, and the voltage signal is sent to the FPGA controller through the signal line. The signal adjustment module first amplifies the analog voltage and performs low-pass filtering on the analog quantity. Then, the analog-to-digital conversion module synchronously converts the multiple analog voltage signals into digital quantities. After the digital quantities are filtered by the software inside the FPGA control module, they are transmitted in real time through the Bluetooth communication module, realizing multi-channel real-time collection of plantar pressure.

[0020] like Figure 1Figure 2 shows a multi-channel plantar pressure acquisition system according to the present invention, comprising an FPC substrate 1, a flexible sensor array 2, and an FPGA main control unit 3. Multiple piezoelectric film sensors 21 are connected to the FPC substrate 1 using conductive silver glue. These multiple piezoelectric film sensors are arranged according to the human body structure and form a flexible sensor array 2 for collecting plantar pressure. In one embodiment of the present invention, there are 16 piezoelectric film sensors, each with a radius of 5 mm.

[0021] The FPC substrate 1 can be bent freely at the sole of the foot and can be closely attached to the piezoelectric film sensor 21. In a specific embodiment of the present invention, the FPC substrate can be bent up to 200,000 times.

[0022] Piezoelectric film sensors 21 are arranged according to the foot structure to form a flexible sensor array 2. They are bonded to the FPC substrate 1 using conductive silver glue and are used to measure plantar pressure at different locations on the sole of the foot. The flexible sensor array 2 has excellent low-frequency response and can operate in a quasi-static state, accurately measuring plantar pressure during human movement. In one embodiment of the present invention, a covering layer is provided over the flexible sensor array 2 to cover the flexible sensor array 2. The covering layer can be made of rubber, natural leather, or non-woven fabric.

[0023] The flexible sensor array 2 is connected to the multi-channel lead 11 to transmit the measured plantar pressure signal to the internal module of the FPGA main control unit 3. The FPGA main control unit 3 includes a signal adjustment module 31, an analog-to-digital conversion module 32, an FPGA control module 33, a Bluetooth communication module 34 and a DC power supply module 35;

[0024] The output of the signal conditioning module 31 is connected to the input of the analog-to-digital conversion module 32, which in turn is connected to the input of the FPGA control module 33. The output of the FPGA control module 33 is connected to the input of the Bluetooth communication module 34. The signal conditioning module 31 is a multi-channel module that includes a charge amplifier, a low-pass filter, and a 50 Hz notch filter. In one embodiment of the present invention, the signal conditioning module 31 can process 16 sensor signals, ensuring consistent and rapid system measurements. The charge amplifier in the signal conditioning module 31 amplifies weak sensor signals. The low-pass filter in the signal conditioning module 31 has a cutoff frequency of 16 Hz, filtering out high-frequency interference to ensure data accuracy. Because 50 Hz alternating current generates an alternating magnetic field, which causes electromagnetic induction between the human body and the piezoelectric sensor, noise or fluctuations are superimposed on the piezoelectric sensor's output signal, affecting measurement accuracy. The 50 Hz notch filter in the signal conditioning module 31 eliminates interference caused by the 50 Hz power frequency.

[0025] The analog-to-digital conversion module 32 synchronously converts sensor signals into digital signals, ensuring that plantar pressure characteristics are not lost. A digital filter within the FPGA control module 33 filters the digital signals to remove interference data. The FPGA control module 33 also backs up plantar pressure data. The sampling frequency of the analog-to-digital conversion module 32 is controlled by the FPGA control module 33 and can be adjusted according to different conditions. The Bluetooth communication module 34 uses a communication protocol to transmit digital signals to other devices in a targeted manner.

[0026] The output end of the DC power supply module 35 is connected to the power supply interfaces of the signal adjustment module 31, the analog-to-digital conversion module 32, the FPGA control module 33, and the Bluetooth communication module 34. The output end of the rechargeable lithium battery is connected to the signal adjustment module 31 and the analog-to-digital conversion module 32 via a voltage conversion circuit. In a specific embodiment of the present invention, the rechargeable lithium battery is a 5V rechargeable lithium battery. The voltage conversion circuit provides a voltage ranging from -5V to +5V to the signal adjustment module and the analog-to-digital conversion module. This enables the signal adjustment module to convert the voltage signal generated by the piezoelectric film sensor into a voltage range of -5V to +5V, and the analog-to-digital conversion module to convert the voltage change signal within the -5V to +5V voltage range into a corresponding digital signal. The analog-to-digital conversion module can simultaneously convert 16 sensor signals into digital signals, and the cutoff frequency of the active low-pass filter is 16 Hz.

[0027] In one specific embodiment of the present invention, the charge amplifier in the signal conditioning module 31 is composed of a rail-to-rail operational amplifier LMC6482, a 1MΩ resistor, and a 1uf capacitor. The low-pass filter, composed of the LMC6482, capacitors, and resistors, forms a Sallen-Key low-pass filter with a cutoff frequency of 16 Hz. The 50 Hz power frequency notch filter is composed of an AD8062 operational amplifier and capacitors and resistors, with the accuracy of the capacitors and resistors required to be within ±0.5%. The analog-to-digital conversion module 32 utilizes the AD7606 integrated 8-channel synchronous sampling data acquisition system, which integrates an input amplifier, overvoltage protection circuit, a second-order analog anti-aliasing filter, an analog multiplexer, a 16-bit 200kSPS SAR ADC 4, and a digital filter. The Bluetooth communication module is model XY-MBO26A. The FPGA main control unit consists of a power supply, a clock circuit crystal oscillator, a reset and debug interface JTAG, and a FLASH configuration chip.

[0028] In order to more clearly express the working process of the above device, this embodiment also provides a pressure collection method of the multi-channel plantar pressure collection system, including the following steps:

[0029] 1) placing the insole-shaped FPC substrate 1 of the multi-channel plantar pressure acquisition system inside a shoe, and connecting the piezoelectric film sensor 21 of the sensor array 2 to the signal adjustment module 31 of the FPGA main control unit 3 via the lead 11;

[0030] 2) In the FPGA main control unit 3, the DC power supply module 35 supplies power to the signal adjustment module 31, the analog-to-digital conversion module 32, the FPGA control module 33, and the Bluetooth communication module 34 to ensure that each module can operate stably;

[0031] 3) When the tester applies pressure to the multi-channel plantar pressure acquisition system, the piezoelectric film sensor 21 provided on the FPC substrate 1 generates a voltage change according to the applied pressure, and transmits the corresponding voltage change signal to the signal adjustment module 31 through the lead 11 for adjustment;

[0032] 4) The charge amplifier in the signal adjustment module 31 amplifies the transmitted voltage change signal, and the low-pass filter in the signal adjustment module 31 filters out high-frequency interference in the amplified voltage change signal; finally, a 50 Hz notch filter is used to eliminate the voltage interference signal induced by the 50 Hz power frequency on the piezoelectric film sensor;

[0033] 5) The voltage change signal adjusted by the signal adjustment module 31 is transmitted to the analog-to-digital conversion module 32.

[0034] The analog-to-digital conversion module 32 and the FPGA control module 33 communicate according to the SPI protocol. The analog-to-digital conversion module 32 converts the voltage change signal into a corresponding numerical signal and transmits the converted numerical signal to the FPGA control module 33.

[0035] 6) The digital filter inside the FPGA control module 33 filters the numerical signal to remove interference data, and backs up the numerical signal after the interference data is filtered out;

[0036] 7) The Bluetooth communication module 34 sends the numerical signal after filtering out the interference data to an external host computer; after receiving the numerical signal, the host computer analyzes it to obtain the plantar pressure result.

[0037] In summary, the utility model provides a multi-channel plantar pressure acquisition system that can sensitively and accurately convert plantar pressure into piezoelectric signals, can realize multi-channel high-speed acquisition and high-speed transmission of plantar pressure data, and is comfortable for users to wear, easy to carry, and easy to use and operate.

[0038] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. Persons skilled in the art will readily appreciate that variations and modifications may be made without departing from the scope of the present invention, all of which fall within the scope of protection of the present invention.

Claims

1. A multi-channel plantar pressure acquisition system, characterized in that: It comprises an FPC substrate (1), a flexible sensor array (2), and an FPGA main control unit (3); The FPC substrate (1) is in the shape of a shoe insole; the flexible sensor array (2) is arranged on the FPC substrate (1); the FPGA main control unit (3) is connected to the flexible sensor array (2) via a lead (11); the FPGA main control unit (3) comprises a signal adjustment module (31), an analog-to-digital conversion module (32), an FPGA control module (33), a Bluetooth communication module (34) and a DC power supply module (35); the output end of the DC power supply module (35) is respectively connected to the power supply interfaces of the signal adjustment module (31), the analog-to-digital conversion module (32), the FPGA control module (33) and the Bluetooth communication module (34); the input end of the signal adjustment module (31) is connected to the flexible sensor array (2) via a lead (11), the output end of the signal adjustment module (31) is connected to the input end of the analog-to-digital conversion module (32), the output end of the analog-to-digital conversion module (32) is connected to the input end of the FPGA control module (33); and the output end of the FPGA control module (33) is connected to the input end of the Bluetooth communication module (34).

2. The multi-channel plantar pressure acquisition system according to claim 1, characterized in that: The flexible sensor array (2) comprises a plurality of piezoelectric film sensors (21), and the plurality of piezoelectric film sensors (21) are arrayed on an FPC substrate (1).

3. The multi-channel plantar pressure acquisition system according to claim 1, characterized in that: The flexible sensor array (2) is adhered to the FPC substrate (1) via conductive silver glue.

4. The multi-channel plantar pressure acquisition system according to claim 1, characterized in that: The signal adjustment module comprises a charge amplifier for amplifying sensor signals, an active low-pass filter for filtering out high-frequency interference, and a 50 Hz notch filter for filtering out voltage interference signals generated by the human body on the piezoelectric film sensor; the input end of the charge amplifier is connected to the flexible sensor array (2) through a lead (11), and the output end of the charge amplifier is connected to the input end of the active low-pass filter; the output end of the active low-pass filter is connected to the input end of the 50 Hz notch filter, and the output end of the 50 Hz notch filter is connected to the analog-to-digital conversion module (32).

5. The multi-channel plantar pressure acquisition system according to claim 1, characterized in that: The DC power supply module (35) comprises a rechargeable lithium battery and a voltage conversion circuit; the output end of the rechargeable lithium battery is connected to the signal adjustment module (31) and the analog-to-digital conversion module (32) respectively through the voltage conversion circuit.

6. The multi-channel plantar pressure acquisition system according to claim 1, characterized in that: The Bluetooth communication module (34) is connected to an external host computer via wireless transmission.

7. The multi-channel plantar pressure acquisition system according to claim 1, characterized in that: It also comprises a covering layer, which is arranged on the FPC substrate (1) and covers the flexible sensor array (2); the material of the covering layer is rubber, natural leather or non-woven fabric.

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