CN110200636B - Plantar pressure sensor and method for detecting pressure, humidity and collecting energy by plantar pressure sensor - Google Patents
Plantar pressure sensor and method for detecting pressure, humidity and collecting energy by plantar pressure sensor Download PDFInfo
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
- A61B5/1036—Measuring load distribution, e.g. podologic studies
- A61B5/1038—Measuring plantar pressure during gait
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
- A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
- A61B5/6802—Sensor mounted on worn items
- A61B5/6804—Garments; Clothes
- A61B5/6807—Footwear
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
- A61B2562/02—Details of sensors specially adapted for in-vivo measurements
- A61B2562/029—Humidity sensors
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
- A61B2562/06—Arrangements of multiple sensors of different types
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
- A61B2562/18—Shielding or protection of sensors from environmental influences, e.g. protection from mechanical damage
Abstract
The invention discloses a plantar pressure sensor, which comprises a signal acquisition part and a circuit part, wherein the signal acquisition part comprises at least one detection unit, the detection unit comprises a humidity sensitive material layer, a piezoelectric film layer and a first electrode layer which are sequentially arranged from top to bottom, and a second electrode and a third electrode which are provided with intervals are arranged between the humidity sensitive material layer and the piezoelectric film layer; the circuit part comprises a front-end circuit, a back-end circuit and a power module, and the second electrode is used as an energy collection group and is connected with the input end of the power module. The invention also discloses a method for detecting pressure, humidity and collecting energy by adopting the plantar pressure sensor. The invention can measure pressure and humidity at the same time, can collect energy to supply power for the circuit part, greatly improves the accuracy of the sensor and makes up the defects of the existing products. The invention is suitable for the technical field of medical equipment.
Description
Technical Field
The invention belongs to the technical field of medical equipment, and particularly relates to a plantar pressure sensor and a method for detecting the pressure and the humidity of a plantar and collecting energy.
Background
Along with the improvement of living standard, human health becomes an important issue of concern. According to the bioholographic theory, the foot is related to the internal organs and each organ of the human body and has corresponding reflection areas, so that the foot has close relationship with the health and longevity of the human body.
The distribution of plantar pressure of the human body can reflect the changes of the functions and the body posture of the lower limbs. The physiological and pathological parameters of the human body under different movement states can be obtained by testing and analyzing the pressure parameters of each point of the sole, which has important significance for researches such as clinical disease diagnosis, postoperative effect evaluation, rehabilitation degree evaluation and the like.
The traditional plantar pressure sensor is greatly affected by environmental humidity. When contacting and leaving the sensor, a capacitance is formed between the foot and the electrode of the sensor, the dielectric constant of the capacitance varies greatly with the humidity of the air, and if compensation correction is not performed, a large error is brought to the measurement.
Disclosure of Invention
The invention aims to provide a plantar pressure sensor which can not only detect the plantar pressure and the plantar humidity, but also collect energy.
It is another object of the present invention to provide a method for detecting pressure, humidity and collecting energy using the above plantar pressure sensor.
The technical scheme adopted by the invention for realizing the purposes is as follows:
a plantar pressure sensor comprises a signal acquisition part and a circuit part, wherein,
first) signal acquisition part
The signal acquisition part comprises at least one detection unit, the detection unit comprises a humidity sensitive material layer, a piezoelectric film layer and a first electrode layer which are sequentially arranged from top to bottom, and a second electrode and a third electrode with intervals are arranged between the humidity sensitive material layer and the piezoelectric film layer;
the third electrode, the piezoelectric film layer and the first electrode together form a pressure detection group; the second electrode and the third electrode form a capacitor through an edge effect, a humidity sensitive material between the second electrode and the third electrode is used as a dielectric layer, and the second electrode, the third electrode and the dielectric layer form a humidity detection group together;
two) circuit portion
The circuit part comprises a front-end circuit and a back-end circuit;
the front-end circuit comprises a controller and a multiplexer, and the signal output end of the controller is respectively connected with the signal input ends of the second electrode and the third electrode through the multiplexer;
the back-end circuit is a first back-end circuit or a second back-end circuit;
A. first back-end circuit
The first back-end circuit comprises a first multiplexer, a first analog-to-digital conversion unit, a first central processing unit, communication equipment and an upper computer which are sequentially connected in series;
the signal output ends of the pressure detection group and the humidity detection group are connected with the signal input end of the first multiplexer;
B. second back-end circuit
The second back-end circuit comprises a second multi-path demodulator, a filtering unit, a second analog-to-digital conversion unit, a second central processing unit, second communication equipment and a second upper computer which are sequentially connected in series;
the filtering unit comprises a low-pass filter and a band-pass filter which are connected in parallel, the second analog-to-digital conversion unit comprises a first analog-to-digital converter and a second analog-to-digital converter which are connected in parallel, the signal output of the low-pass filter is connected with the signal input end of the first analog-to-digital converter, and the signal output end of the band-pass filter is connected with the signal input end of the second analog-to-digital converter; the signal output ends of the pressure detection group and the humidity detection group are connected with the signal input end of the second multiplexer.
The circuit part also comprises a power supply module, the second electrode is used as an energy collection group and is connected with the input end of the power supply module, and the output end of the power supply module is connected with the power supply input end of the front-end circuit and the power supply input end of the components except the first upper computer/the second upper computer of the back-end circuit.
As a limitation: the cross sections of the second electrode and the third electrode are comb structures, and branches of the second electrode and the third electrode are mutually intersected to form comb-shaped intersected capacitors.
A method for detecting pressure, humidity and collecting energy is realized by adopting the plantar pressure sensor, wherein the method is a method I or a method II when a back-end circuit adopts a first back-end circuit, the method is a method I when the back-end circuit adopts a second back-end circuit, the method is a method II,
I. method one
The method one comprises the following steps in sequence:
1. a frequency is set as by the controllerThe multiplexer modulates the received alternating voltage/current signal and outputs the modulated alternating voltage/current signal to the second electrode and the third electrode;
when the humidity of the sensor appearance corresponding to the second electrode and the third electrode changes, the dielectric constant of the humidity sensitive material layer changes, a mutual inductance capacitance is generated between the second electrode and the third electrode, and the humidity detection group outputs an alternating current analog electric signal containing mutual inductance capacitance information to the first multiplexer; when the pressure applied by the detection unit changes, the surface of the piezoelectric film layer generates charges and further forms an alternating current analog current signal;
the detection unit outputs an alternating current analog voltage signal containing the mutual inductance capacitance information and an alternating current analog current signal with the pressure value change to the first analog-to-digital conversion unit;
2. the first analog-to-digital conversion unit converts the received mixed analog electric signal into a digital signal and outputs the digital signal to the first central processing unit;
3. the first central processing unit processes the received digital signal by utilizing a self-stored band-pass filtering algorithm to obtain a digital signal containing mutual inductance capacitance information, and processes the received digital signal by utilizing a self-stored low-pass filtering algorithm to obtain a digital signal containing pressure information;
4. the first central processing calculates and processes the digital signal containing the mutual inductance capacitance information to obtain the time-varying value of the mutual inductance capacitanceAnd output to the first upper computer via the first communication device, the first CPU calculates and processes the digital signal containing the pressure information to obtain a pressure signal +.>And output to the first upper computer through the first communication equipment;
5. the first upper computer receives the mutual inductance capacitance change value along with timeCalculating the piezoelectric constant after correction, and the first upper computer is used for receiving the pressure signal +.>Calculating total charge number of the detection unit>Finally, calculating a pressure correction value;
II, method II
The second method comprises the following steps in sequence:
(one) a frequency is set as by the controllerThe multiplexer modulates the received alternating voltage/current signal and outputs the modulated alternating voltage/current signal to the second electrode and the third electrode;
when the humidity of the outer surface of the sensor corresponding to the second electrode and the third electrode changes, the dielectric constant of the humidity sensitive material layer changes, a mutual inductance capacitance is generated between the second electrode and the third electrode, and the humidity detection group outputs an alternating current analog electric signal containing mutual inductance capacitance information to the second multiplexer; when the pressure applied by the detection unit changes, the surface of the piezoelectric film layer generates charges and further forms an alternating current analog current signal;
the detection unit outputs an alternating current analog voltage signal containing the mutual inductance capacitance information and an alternating current analog current signal with the pressure value changed to the filtering unit;
the filtering unit processes the received mixed analog electric signal through a low-pass filter to obtain an alternating current analog electric signal containing pressure change and outputs the alternating current analog electric signal to the first analog-to-digital converter, and the filtering unit processes the received mixed analog current signal through a band-pass filter to obtain an alternating current analog electric signal containing mutual inductance capacitance information and outputs the alternating current analog electric signal to the second analog-to-digital converter;
the first analog-to-digital converter converts the received alternating current analog electric signal containing pressure change into a digital signal and outputs the digital signal to the second central processing unit, and the second analog-to-digital converter converts the received alternating current analog electric signal containing mutual inductance capacitance information into a digital signal and outputs the digital signal to the second central processing unit;
(IV) the second CPU calculates the digital electric signal received from the first A/D converter to obtain a pressure signalThe digital signal received from the second analog-to-digital converter is calculated by the second central processing unit to obtain the time-varying value +.>And outputting the data to a second upper computer through second communication equipment;
fifth, the second upper computer changes the value along with time according to the received mutual inductance capacitanceCalculating the corrected piezoelectric constant, and the second upper computer is used for controlling the second upper computer according to the received pressure signal +.>Calculating total charge number of the detection unit>Finally, calculating a pressure correction value;
in the whole process of the first and second methods, the following steps are also respectively carried out,
the power module collects the charges generated by the second electrode and supplies power to the front-end circuit and the first back-end circuit/the second back-end circuit, and in the process, the multiplexer controls the collected energy and the capacitance measurement through time sequence in turn.
Compared with the prior art, the technical proposal adopted by the invention has the following technical progress:
(1) The invention can measure the pressure and the humidity at the same time, thereby correcting the change of the capacitance between the foot and the electrode caused by the change of the humidity, greatly improving the accuracy of the sensor and making up the defect of the prior product;
(2) The second electrode and the third electrode form a comb-shaped crossed capacitor for measuring humidity, so that the capacitance value is greatly increased, and the accuracy is improved;
(3) The invention adopts the passive piezoelectric film, collects the electric energy converted by the mechanical energy by utilizing the positive piezoelectric characteristic of the passive piezoelectric film, supplies power for the back-end circuit, and has the advantage of low energy consumption;
(4) The invention has simple and ingenious structure, realizes multiple functions on one detection unit by utilizing time sequence control, the characteristics of the piezoelectric film material and the edge effect between electrodes, and simultaneously realizes energy collection and measurement of pressure and humidity;
(5) The invention also discloses a method for detecting pressure and humidity and collecting energy by using the piezoelectric sensor, and the method has simple steps, is easy to realize, and has development in the plantar pressure detection field;
(6) The invention can be manufactured into an insole type array sensor to detect the force change at multiple points of the sole, thereby detecting the change of the pressure distribution of the whole sole when a tested person walks, and having important significance for researches such as clinical disease diagnosis, postoperative effect evaluation, rehabilitation degree evaluation and the like.
The invention is suitable for the technical field of medical equipment.
Drawings
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate the invention and together with the embodiments of the invention, serve to explain the invention.
In the drawings:
FIG. 1 is a schematic overall structure of embodiment 1 of the present invention;
FIG. 2 is a schematic cross-sectional view of a humidity detection group according to embodiment 1 of the present invention;
FIG. 3 is a schematic block diagram of embodiment 1 of the present invention;
FIG. 4 is a schematic diagram of a back-end circuit employing a second configuration according to embodiment 1 of the present invention;
FIG. 5 is a signal plot of the positive stress measured at the insole region corresponding to a small electrode during a walk according to example 2 of the present invention.
In the figure: 1. the humidity sensitive material layer 2, the second electrode, the third electrode layer 21, the second electrode, the third electrode 3, the piezoelectric film layer 4 and the first electrode layer.
Detailed Description
Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are presented for purposes of illustration and explanation only and are not intended to limit the present invention.
Example 1 plantar pressure insole
The present embodiment relates to a plantar pressure insole, which includes a signal acquisition portion and a circuit portion. As shown in fig. 1 and 2, the signal acquisition part comprises at least one detection unit, the detection unit comprises a humidity sensitive material layer 1, a second electrode, a third electrode layer 2, a piezoelectric film layer 3 and a first electrode layer 4 which are sequentially arranged from top to bottom, the second electrode and the third electrode layer 2 are provided with a plurality of electrode groups distributed according to the shape of the sole with intervals, each electrode group comprises a second electrode 21 and a third electrode 22 with comb-shaped cross sections, and branches of the second electrode 21 and the third electrode 22 are mutually intersected to form a comb-shaped intersected capacitor; the third electrode 22, the piezoelectric thin film layer 3 and the first electrode together constitute a pressure detection group; the second electrode 21 and the third electrode 22 form a capacitor by an edge effect, the humidity sensitive material between the second electrode 21 and the third electrode 22 is used as a dielectric layer, the three together form a humidity detection group, and the second electrode 21 is used as an energy collection group.
As shown in fig. 3, the circuit portion includes a front-end circuit, a back-end circuit, and a power supply module; the front-end circuit comprises a controller and a multiplexer, wherein the signal output end of the controller is respectively connected with the signal input ends of the second electrode and the third electrode through the multiplexer; the back-end circuit comprises a first multi-path demodulator, a first analog-to-digital conversion unit, a first central processing unit, first communication equipment and a first upper computer which are sequentially connected in series; the signal output ends of the pressure detection group and the humidity detection group are connected with the signal input end of the first multiplexer, the output end of the energy collection group is connected with the input end of the power module, and the output end of the power module is connected with the power input end of the front-end circuit and the power input end of the components except the first upper computer of the back-end circuit.
The back-end circuit of this embodiment may also adopt a structure as shown in fig. 4, and includes a second multiplexer, a filtering unit, a second analog-to-digital conversion unit, a second central processing unit, a second communication device and a second upper computer that are sequentially connected in series; the filtering unit comprises a low-pass filter and a band-pass filter which are connected in parallel, the second analog-to-digital conversion unit comprises a first analog-to-digital converter and a second analog-to-digital converter which are connected in parallel, the signal output of the low-pass filter is connected with the signal input end of the first analog-to-digital converter, and the signal output end of the band-pass filter is connected with the signal input end of the second analog-to-digital converter; the signal output ends of the pressure detection group and the humidity detection group are connected with the signal input end of the second multiplexer.
Example 2A method of detecting pressure, humidity and harvesting energy
This embodiment is implemented by using embodiment 1, and when the back-end circuit shown in fig. 3 is used, the method is a method one, which includes the following steps performed in order:
1. a frequency is set as by the controllerThe AC voltage signal of (2) is output to a multiplexer which modulates the received AC voltage/current signal and outputs to a secondAn electrode 21 and a third electrode 22;
when the humidity of the sensor appearance corresponding to the second electrode 21 and the third electrode 22 changes, the dielectric constant of the humidity sensitive material layer 1 changes, a mutual inductance capacitance is generated between the second electrode 21 and the third electrode 22, and the humidity detection group outputs an alternating current analog electric signal containing mutual inductance capacitance information to the first multiplexer; when the pressure applied by the detection unit changes, the surface of the piezoelectric film layer 3 generates charges and further forms an alternating current analog current signal;
the detection unit outputs an alternating current analog voltage signal containing the mutual inductance capacitance information and an alternating current analog current signal with the pressure value change to the first analog-to-digital conversion unit;
2. the first analog-to-digital conversion unit converts the received mixed analog electric signal into a digital signal and outputs the digital signal to the first central processing unit;
3. the first central processing unit processes the received digital signal by utilizing a self-stored band-pass filtering algorithm to obtain a digital signal containing mutual inductance capacitance information, and processes the received digital signal by utilizing a self-stored low-pass filtering algorithm to obtain a digital signal containing pressure information;
4. the first central processing calculates and processes the digital signal containing the mutual inductance capacitance information to obtain the time-varying value of the mutual inductance capacitanceAnd output to the first upper computer via the first communication device, the first CPU calculates and processes the digital signal containing the pressure information to obtain a pressure signal +.>And output to the first upper computer through the first communication equipment;
5. the first upper computer receives the mutual inductance capacitance change value along with timeCalculating the piezoelectric constant after correction, and a first upper computer rootBased on the received pressure signal->Calculating total charge number of the detection unit>And finally, calculating a pressure correction value.
When the back-end circuit shown in fig. 4 is used, the second method is used in this embodiment, and the following steps are performed in sequence:
(one) a frequency is set as by the controllerThe ac voltage signal of (2) is output to the multiplexer, which modulates the received ac voltage/current signal and outputs it to the second electrode 21 and the third electrode 22;
when the humidity of the sensor appearance corresponding to the second electrode 21 and the third electrode 22 changes, the dielectric constant of the humidity sensitive material layer 1 changes, a mutual inductance capacitance is generated between the second electrode 21 and the third electrode 22, and the humidity detection group outputs an alternating current analog electric signal containing mutual inductance capacitance information to the second multiplexer; when the pressure applied by the detection unit changes, the surface of the piezoelectric film layer 3 generates charges and further forms an alternating current analog current signal;
the detection unit outputs an alternating current analog voltage signal containing the mutual inductance capacitance information and an alternating current analog current signal with the pressure value changed to the filtering unit;
the filtering unit processes the received mixed analog electric signal through a low-pass filter to obtain an alternating current analog electric signal containing pressure change and outputs the alternating current analog electric signal to the first analog-to-digital converter, and the filtering unit processes the received mixed analog current signal through a band-pass filter to obtain an alternating current analog electric signal containing mutual inductance capacitance information and outputs the alternating current analog electric signal to the second analog-to-digital converter;
the first analog-to-digital converter converts the received alternating current analog electric signal containing pressure change into a digital signal and outputs the digital signal to the second central processing unit, and the second analog-to-digital converter converts the received alternating current analog electric signal containing mutual inductance capacitance information into a digital signal and outputs the digital signal to the second central processing unit;
(IV) the second CPU calculates the digital electric signal received from the first A/D converter to obtain a pressure signalThe digital signal received from the second analog-to-digital converter is calculated by the second central processing unit to obtain the time-varying value +.>And outputting the data to a second upper computer through second communication equipment;
fifth, the second upper computer changes the value along with time according to the received mutual inductance capacitanceCalculating the corrected piezoelectric constant, and the second upper computer is used for controlling the second upper computer according to the received pressure signal +.>Calculating total charge number of the detection unit>And finally, calculating a pressure correction value.
The power module collects the charge generated by the second electrode 21 and supplies power to the front-end circuit and the first back-end circuit/the second back-end circuit throughout the process of the first and second methods, and the collected energy and capacitance measurement are alternately performed through time sequence control in the process. The time sequence control process is to use a multiplexer to control so that the back-end circuit is switched between energy collection and capacitance detection. Because the humidity changes relatively slowly, the second electrode 21 collects energy most of the time, and the capacitance is detected every 5s or so.
As shown in FIG. 4, a signal diagram of the positive stress measured in the insole region corresponding to a small electrode during a period of walking is shown, the positive rising stage of the signal indicates that the foot is gradually stepping on the insole, the positive stress is increased, and then the electric charge is consumed; the reverse descent phase of the signal indicates that the foot gradually leaves the ground and the normal stress is reduced.
For each humidity detection unit, according to the time-varying value of the mutual inductance capacitanceThe change value of the dielectric constant of the humidity sensitive material layer 1 along with time can be calculated, and then the change data of humidity along with time can be obtained by combining the corresponding relation of the dielectric constant and humidity of the humidity sensitive material. Since the magnitude of the piezoelectric constant is proportional to the dielectric constant of the corresponding material, the piezoelectric constant of the piezoelectric thin film layer 3 after humidity correction can be obtained by combining the obtained humidity change data with time according to the corresponding relation of the dielectric constant-humidity of the piezoelectric material:
according to piezoelectric relationsThe relation between the charge density and the positive stress collected on the plane of the piezoelectric film layer 3 can be obtained>Where σ is the normal stress perpendicular to the plane direction of the film.
The change with time of the plantar pressure after the humidity correction is:
in this embodiment, the power module collects the charges on the second electrode 21 by using the bridge rectifier circuit, and stores the charges by using the capacitor included in the power module, where the stored energy can be calculated by the following formula:
where U represents the voltage of the capacitor.
Claims (3)
1. A plantar pressure sensor comprising a signal acquisition portion and a circuit portion, characterized in that:
first) signal acquisition part
The signal acquisition part comprises at least one detection unit, the detection unit comprises a humidity sensitive material layer, a piezoelectric film layer and a first electrode layer which are sequentially arranged from top to bottom, and a second electrode and a third electrode with intervals are arranged between the humidity sensitive material layer and the piezoelectric film layer;
the third electrode, the piezoelectric film layer and the first electrode together form a pressure detection group; the second electrode and the third electrode form a capacitor through an edge effect, a humidity sensitive material between the second electrode and the third electrode is used as a dielectric layer, and the second electrode, the third electrode and the dielectric layer form a humidity detection group together;
two) circuit portion
The circuit part comprises a front-end circuit and a back-end circuit;
the front-end circuit comprises a controller and a multiplexer, and the signal output end of the controller is respectively connected with the signal input ends of the second electrode and the third electrode through the multiplexer;
the back-end circuit is a first back-end circuit or a second back-end circuit;
A. first back-end circuit
The first back-end circuit comprises a first multiplexer, a first analog-to-digital conversion unit, a first central processing unit, communication equipment and a first upper computer which are sequentially connected in series;
the signal output ends of the pressure detection group and the humidity detection group are connected with the signal input end of the first multiplexer;
B. second back-end circuit
The second back-end circuit comprises a second multi-path demodulator, a filtering unit, a second analog-to-digital conversion unit, a second central processing unit, second communication equipment and a second upper computer which are sequentially connected in series;
the filtering unit comprises a low-pass filter and a band-pass filter which are connected in parallel, the second analog-to-digital conversion unit comprises a first analog-to-digital converter and a second analog-to-digital converter which are connected in parallel, the signal output of the low-pass filter is connected with the signal input end of the first analog-to-digital converter, and the signal output end of the band-pass filter is connected with the signal input end of the second analog-to-digital converter; the signal output ends of the pressure detection group and the humidity detection group are connected with the signal input end of the second multiplexer;
the circuit part also comprises a power supply module, the second electrode is used as an energy collection group and is connected with the input end of the power supply module, and the output end of the power supply module is connected with the power supply input end of the front-end circuit and the power supply input end of the components except the first upper computer/the second upper computer of the back-end circuit;
the power supply module collects charges generated by the second electrode and supplies power to the front-end circuit and the first back-end circuit/the second back-end circuit, and in the process, the multiplexer controls the collected energy and capacitance measurement in turn through time sequence;
the first central processing unit processes the received digital signal by utilizing a self-stored band-pass filtering algorithm to obtain a digital signal containing mutual inductance capacitance information, and processes the received digital signal by utilizing a self-stored low-pass filtering algorithm to obtain a digital signal containing pressure information; the first central processing calculates and processes the digital signal containing the mutual inductance capacitance information to obtain a time-varying value C (t) of the mutual inductance capacitance and outputs the value C (t) to the first upper computer through the first communication equipment, and the first central processing calculates and processes the digital signal containing the pressure information to obtain a pressure signal U F (t) outputting the data to the first upper computer through the first communication equipment; the first upper computer calculates the corrected piezoelectric constant according to the received mutual inductance capacitance value C (t) along with time, and the first upper computer calculates the corrected piezoelectric constant according to the received pressure signal U F (t) calculating the total charge number Q of the detection unit F (t) finally calculating a pressure correction value;
the second CPU calculates and processes the digital electric signal received from the first A/D converter to obtain a pressure signal U F (t) outputting the value C (t) of the mutual inductance capacitance along with time to a second upper computer through second communication equipment, and outputting the value C (t) of the mutual inductance capacitance along with time to the second upper computer through the second communication equipment by a second central processing unit; the second upper computer calculates the corrected piezoelectric constant according to the received mutual inductance capacitance value C (t) along with time, and the second upper computer calculates the corrected piezoelectric constant according to the received pressure signal U F (t) calculating the total charge number Q of the detection unit F (t) finally, calculating the pressure correction value.
2. The plantar pressure sensor of claim 1, wherein: the cross sections of the second electrode and the third electrode are comb structures, and branches of the second electrode and the third electrode are mutually intersected to form comb-shaped intersected capacitors.
3. A method of detecting pressure, humidity and collecting energy, implemented with the plantar pressure sensor of claim 1 or 2, characterized in that the method is method one or method two, when the back-end circuit employs a first back-end circuit, the method is method one, when the back-end circuit employs a second back-end circuit, the method is method two, wherein,
I. method one
The method one comprises the following steps in sequence:
1. a frequency is set as by the controllerf 1 The multiplexer modulates the received alternating voltage/current signal and outputs the modulated alternating voltage/current signal to the second electrode and the third electrode;
when the humidity of the sensor appearance corresponding to the second electrode and the third electrode changes, the dielectric constant of the humidity sensitive material layer changes, a mutual inductance capacitance is generated between the second electrode and the third electrode, and the humidity detection group outputs an alternating current analog electric signal containing mutual inductance capacitance information to the first multiplexer; when the pressure applied by the detection unit changes, the surface of the piezoelectric film layer generates charges and further forms an alternating current analog current signal;
the detection unit outputs an alternating current analog voltage signal containing the mutual inductance capacitance information and an alternating current analog current signal with the pressure value change to the first analog-to-digital conversion unit;
2. the first analog-to-digital conversion unit converts the received mixed analog electric signal into a digital signal and outputs the digital signal to the first central processing unit;
3. the first central processing unit processes the received digital signal by utilizing a self-stored band-pass filtering algorithm to obtain a digital signal containing mutual inductance capacitance information, and processes the received digital signal by utilizing a self-stored low-pass filtering algorithm to obtain a digital signal containing pressure information;
4. the first central processing calculates and processes the digital signal containing the mutual inductance capacitance information to obtain a time-varying value C (t) of the mutual inductance capacitance and outputs the value C (t) to the first upper computer through the first communication equipment, and the first central processing calculates and processes the digital signal containing the pressure information to obtain a pressure signal U F (t) outputting the data to the first upper computer through the first communication equipment;
5. the first upper computer calculates the corrected piezoelectric constant according to the received mutual inductance capacitance value C (t) along with time, and the first upper computer calculates the corrected piezoelectric constant according to the received pressure signal U F (t) calculating the total charge number Q of the detection unit F (t) finally calculating a pressure correction value;
II, method II
The second method comprises the following steps in sequence:
(one) a frequency is set as by the controllerf 1 The multiplexer modulates the received alternating voltage/current signal and outputs the modulated alternating voltage/current signal to the second electrode and the third electrode;
when the humidity of the outer surface of the sensor corresponding to the second electrode and the third electrode changes, the dielectric constant of the humidity sensitive material layer changes, a mutual inductance capacitance is generated between the second electrode and the third electrode, and the humidity detection group outputs an alternating current analog electric signal containing mutual inductance capacitance information to the second multiplexer; when the pressure applied by the detection unit changes, the surface of the piezoelectric film layer generates charges and further forms an alternating current analog current signal;
the detection unit outputs an alternating current analog voltage signal containing the mutual inductance capacitance information and an alternating current analog current signal with the pressure value changed to the filtering unit;
the filtering unit processes the received mixed analog electric signal through a low-pass filter to obtain an alternating current analog electric signal containing pressure change and outputs the alternating current analog electric signal to the first analog-to-digital converter, and the filtering unit processes the received mixed analog current signal through a band-pass filter to obtain an alternating current analog electric signal containing mutual inductance capacitance information and outputs the alternating current analog electric signal to the second analog-to-digital converter;
the first analog-to-digital converter converts the received alternating current analog electric signal containing pressure change into a digital signal and outputs the digital signal to the second central processing unit, and the second analog-to-digital converter converts the received alternating current analog electric signal containing mutual inductance capacitance information into a digital signal and outputs the digital signal to the second central processing unit;
(IV) the second CPU calculates the digital electric signal received from the first A/D converter to obtain a pressure signal U F (t) outputting the value C (t) of the mutual inductance capacitance along with time to a second upper computer through second communication equipment, and outputting the value C (t) of the mutual inductance capacitance along with time to the second upper computer through the second communication equipment by a second central processing unit;
fifth, the second upper computer calculates the corrected piezoelectric constant according to the received mutual inductance capacitance value C (t) along with time, and the second upper computer calculates the corrected piezoelectric constant according to the received pressure signal U F (t) calculating the total charge number Q of the detection unit F (t) finally calculating a pressure correction value;
in the whole process of the first and second methods, the following steps are also respectively carried out,
the power module collects the charges generated by the second electrode and supplies power to the front-end circuit and the first back-end circuit/the second back-end circuit, and in the process, the multiplexer controls the collected energy and the capacitance measurement through time sequence in turn.
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