CN210673316U - Sensor for accurately detecting normal stress and shearing force of sole during walking - Google Patents
Sensor for accurately detecting normal stress and shearing force of sole during walking Download PDFInfo
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- CN210673316U CN210673316U CN201921044732.5U CN201921044732U CN210673316U CN 210673316 U CN210673316 U CN 210673316U CN 201921044732 U CN201921044732 U CN 201921044732U CN 210673316 U CN210673316 U CN 210673316U
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- 239000011241 protective layer Substances 0.000 claims abstract description 8
- 238000012545 processing Methods 0.000 claims description 36
- 238000004891 communication Methods 0.000 claims description 13
- 230000000694 effects Effects 0.000 claims description 6
- 238000005259 measurement Methods 0.000 abstract description 4
- 230000007547 defect Effects 0.000 abstract description 2
- 210000002683 foot Anatomy 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 210000000988 bone and bone Anatomy 0.000 description 2
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- 238000006243 chemical reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 230000005021 gait Effects 0.000 description 1
- 210000001255 hallux Anatomy 0.000 description 1
- 210000003141 lower extremity Anatomy 0.000 description 1
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Abstract
The utility model discloses a sensor for accurately detecting the normal stress and the shearing force of the sole during walking, which comprises a signal acquisition part and a back-end circuit, wherein the signal output end of the signal acquisition part is connected with the signal input end of the back-end circuit; the signal acquisition part comprises a first device protective layer, a detection unit and a second device protective layer which are sequentially arranged from top to bottom; the detection unit comprises a first electrode, a third electrode and a second electrode which are arranged side by side and at intervals, a first piezoelectric film is arranged between the first electrode and the second device protection layer, and a second piezoelectric film is arranged between the second electrode and the second device protection layer. The utility model discloses but the defect of current product has been remedied to simultaneous measurement normal stress and shearing force, provides abundanter, more comprehensive data for sole pressure's measurement, is applicable to medical equipment technical field.
Description
Technical Field
The utility model belongs to the technical field of medical equipment for sole normal stress and shearing force when the accurate detection was walked, specifically speaking are sensors of sole normal stress and shearing force when the accurate detection was walked.
Background
With the improvement of living standard, human health becomes an important concern. According to the biological holographic theory, feet are related to internal organs and organs of human body and have corresponding reflecting regions, so that the feet are closely related to the health and longevity of human body.
The distribution of the human body sole pressure can reflect the function of the lower limbs and the change of the body posture. The pressure parameters of each point of the sole are tested and analyzed, physiological and pathological parameters of the human body in different motion states can be obtained, and the method has important significance for the research of clinical disease diagnosis, postoperative effect evaluation, rehabilitation degree evaluation and the like. Most of the conventional plantar pressure measuring devices can only measure the positive stress and cannot provide data of the shearing force, however, many diseases are proved to be closely related to the latter. For example, chinese utility model patent publication No. CN 208511028U discloses a plantar pressure signal collecting device, which collects the distribution of plantar pressure by using the crossing point of the vertical conductive band and the horizontal conductive band as a signal collecting point. The above technique can only simply collect the distribution of sole pressure and cannot provide data of shear force.
Disclosure of Invention
The utility model aims at providing a sole normal stress and shearing force's sensor when accurate detection is walked can the plantar normal stress of simultaneous measurement and shearing force.
The utility model discloses a realize above-mentioned purpose, the technical scheme who adopts as follows:
a sensor for accurately detecting the normal stress and shearing force of the sole of a foot during walking comprises a signal acquisition part and a back-end circuit, wherein the signal output end of the signal acquisition part is connected with the signal input end of the back-end circuit;
signal acquisition part
The signal acquisition part comprises a first device protective layer, a detection unit and a second device protective layer which are sequentially arranged from top to bottom;
the detection unit comprises a first electrode, a third electrode and a second electrode which are arranged side by side and at intervals, a first piezoelectric film is arranged between the first electrode and the second device protection layer, and a second piezoelectric film is arranged between the second electrode and the second device protection layer;
the first piezoelectric film is mainly based on longitudinal piezoelectric effect and has a piezoelectric constant d33（1）>>d31（1）>>d32（1）；
The second piezoelectric film is mainly based on transverse piezoelectric effect and has a piezoelectric constant d31（2）>>d33（2）>>d32（2）；
The first electrode, the first piezoelectric film and the third electrode form a normal stress collection group together, and the second electrode, the second piezoelectric film and the third electrode form a shearing force collection group together;
the number of the detection units is at least one.
As a limitation: the back end circuit comprises a signal processing circuit, communication equipment and an upper computer which are connected in series;
the signal processing circuit comprises a first signal processing circuit and a second signal processing circuit which are connected in parallel;
the first signal processing circuit comprises a first charge amplifier and a first analog-to-digital converter, the input end of the first charge amplifier is connected with the signal output end of the positive stress acquisition group, and the output end of the first charge amplifier is connected with the first input end of the communication equipment through the first analog-to-digital converter;
the second signal processing circuit comprises a second charge amplifier and a second analog-to-digital converter, the input end of the second charge amplifier is connected with the signal output end of the shearing force acquisition group, and the output end of the second charge amplifier is connected with the second input end of the communication equipment through the second analog-to-digital converter.
As a further limitation: a central processing unit is arranged between the signal processing circuit and the communication equipment;
the output end of the first charge amplifier is connected with the first input end of the central processing unit through the first analog-to-digital converter, the output end of the second charge amplifier is connected with the second input end of the central processing unit through the second analog-to-digital converter, and the signal output end of the central processing unit is connected with the upper computer through the communication equipment.
As a second limitation: the electric axis of the first piezoelectric film points to the advancing direction of the sole, and the direction of the z axis is vertical to the upper direction; the mechanical axis of the second piezoelectric film points to the forward direction of the sole, and the direction of the z axis is vertical and upward.
As a third limitation: the first electrode and the second electrode have the same structure.
As a fourth limitation: when the number of the sensing cells is more than one, the third electrodes of the respective sensing cells are commonly grounded.
The utility model discloses owing to adopted foretell technical scheme, it compares with prior art, and the technical progress who gains lies in:
(1) the utility model can measure the change of the shearing force while measuring the normal stress, makes up the defects of the existing products, provides richer and more comprehensive data for measuring the sole pressure, and has development in the field of sole pressure detection;
(2) the utility model has simple and smart structure, combines two different piezoelectric materials in the same sensor, and realizes the measurement of two types of parameters;
(3) the utility model discloses in arranging measuring electrode and ground electrode in same one deck, when reducing sensor thickness, reduced the inter-electrode and crosstalked to reduce measuring error.
The utility model is suitable for a medical equipment technical field.
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 embodiments of the invention, and together with the description serve to explain the invention and not to limit the invention.
In the drawings:
fig. 1 is a schematic structural diagram of a signal acquisition part according to an embodiment of the present invention;
fig. 2 is a schematic longitudinal sectional view of an embodiment of the present invention;
fig. 3 is a schematic block circuit diagram of an embodiment of the present invention;
FIG. 4 is a schematic diagram showing the change of the positive stress of five monitoring points in a walking cycle with time according to the embodiment of the present invention;
FIG. 5 is a schematic diagram showing the change of the shearing force of a monitoring point in a walking cycle with time according to an embodiment of the present invention;
FIG. 6 is a schematic diagram showing the change of the normal stress of a detection point with time during walking according to the embodiment of the present invention;
fig. 7 is an algorithm flow diagram implemented by the present invention.
In the figure: 1. the device comprises a first device protective layer, 2, a signal acquisition array, 3, a second device protective layer, 4, a detection unit, 21, a first electrode, 22, a first piezoelectric film, 23, a third electrode, 24, a second electrode, 25 and a second piezoelectric film.
Detailed Description
The 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 for purposes of illustration and explanation only and are not intended to limit the invention.
Embodiment is an insole for accurately detecting normal stress and shearing force of sole during walking
The embodiment relates to an insole for accurately detecting the normal stress and the shearing force of a sole during walking, which comprises a signal acquisition part and a back-end circuit, wherein the signal output end of the signal acquisition part is connected with the signal input end of the back-end circuit. As shown in fig. 1, the signal acquisition part comprises a first device protection layer 1, a signal acquisition array 2 and a second device protection layer 3 which are arranged in sequence from top to bottom; the signal acquisition array 2 comprises a plurality of detection units 4 distributed according to the shape of the sole of a foot.
As shown in fig. 2, the detecting unit 4 includes a first electrode 21, a third electrode 23 and a second electrode 24 arranged side by side and at an interval, a first piezoelectric film 22 is arranged between the first electrode 21 and the second device protecting layer 3, a second piezoelectric film 25 is arranged between the second electrode 24 and the second device protecting layer 3, and the third electrodes 23 of all the detecting units 4 are commonly grounded.
In this embodiment, the first piezoelectric film 22 is mainly based on the longitudinal piezoelectric effect, and has a piezoelectric constant d33（1）>>d31（1）>>d32（1）The electric axis of the first piezoelectric film 22 points in the advancing direction of the sole when placed; the second piezoelectric film is mainly based on transverse piezoelectric effect and has piezoelectric constant d31（2）>>d33（2）>>d32（2）The mechanical axis of the second piezoelectric film 25 points in the advancing direction of the sole when placed; the z-axis direction of the first piezoelectric film 22 and the second piezoelectric film 25 is directed vertically upward.
The first electrode 21, the first piezoelectric film 22 and the third electrode 23 together form a positive stress collection group, and the second electrode 24, the second piezoelectric film 25 and the third electrode 23 together form a shear force collection group. The first electrode 21 and the second electrode 24 have the same structure in this embodiment.
As shown in fig. 3, the back-end circuit includes a signal processing circuit, a central processing unit, a communication device and an upper computer connected in series; the signal processing circuit comprises a first signal processing circuit and a second signal processing circuit which are connected in parallel; the first signal processing circuit comprises a first charge amplifier and a first analog-to-digital converter, the input end of the first charge amplifier is connected with the signal output end of the positive stress acquisition group, and the output end of the first charge amplifier is connected with the first input end of the central processing unit through the first analog-to-digital converter; the second signal processing circuit comprises a second charge amplifier and a second analog-to-digital converter, the input end of the second charge amplifier is connected with the signal output end of the shearing force acquisition group, and the output end of the second charge amplifier is connected with the second input end of the central processing unit through the second analog-to-digital converter.
The detection of the normal stress and the shearing force of the sole during walking by adopting the embodiment is carried out according to the following steps in sequence:
firstly, the insole is placed in a shoe, a person to be tested wears the shoe to walk, and when the normal stress on the detection unit 4 changes, the surface of the first piezoelectric film 22 generates electric charges; when the shearing force applied to the detection unit 4 along the direction of the second piezoelectric film 25 changes, the surface of the second piezoelectric film 25 generates charges;
secondly, the step comprises the following steps which are carried out in sequence,
the first charge amplifier collects the charges generated on the surface of the first piezoelectric film 22, amplifies the charges into an analog voltage signal and outputs the analog voltage signal to the first analog-to-digital converter, and the second charge amplifier collects the charges generated on the surface of the second piezoelectric film 25, amplifies the charges into an analog voltage signal and outputs the analog voltage signal to the second analog-to-digital converter;
the first analog-to-digital converter converts the received analog voltage signal into a digital signal and outputs the digital signal to the central processing unit, and the second analog-to-digital converter converts the received analog voltage signal into a digital signal and outputs the digital signal to the central processing unit;
thirdly, the central processing unit endows the received digital signals with serial port transmission order and then sends the digital signals to the upper computer through the communication equipment;
and (IV) the upper computer calculates the normal stress value borne by the sensor according to the digital signal from the first analog-to-digital converter, and calculates the shear force value borne by the sensor according to the digital signal from the second analog-to-digital converter.
As shown in fig. 4, the signal is a signal of the change of the positive stress with time collected by five detecting units 4 in a walking cycle, 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 backward descending phase of the signal indicates that the foot gradually leaves the ground and the normal stress is reduced. In fig. 4, the sampling points of the curves a, b, c, d, e are the heel, the middle of the foot, the third spat bone, the first spat bone and the first toe, respectively.
The shear force versus time signal collected by one detection unit 4 during one gait cycle is substantially as shown in figure 5. The positive-negative pulse of the signal indicates that the shear force is directed forward and the negative-positive pulse of the signal indicates that the shear force is directed backward.
During walking, the signal of the normal stress measured by one detecting unit 4 is roughly as shown in fig. 6, and can be composed of a segmentThe average value of the pulse peak intervals in the stable walking time is used for calculating the walking period T, thereby obtaining the step frequency
：
Period of time
In the formula (1)
For counting.
Data processing: the back end circuit amplifies the collected charge signals, and transmits the amplified charge signals to an upper computer through a central processing unit and communication equipment after analog-to-digital conversion. The upper computer can obtain the data of the change of the electric charge along with the time collected by each detection unit 4 of the sensor according to the received voltage signal and the input-output relation of the back end circuit
。
According to the piezoelectric relation and the piezoelectric constant of the selected piezoelectric film, neglecting properly, the relation between the charge density collected on the piezoelectric film plane and the normal stress and the shearing force can be obtained:
Wherein, σ is the normal stress perpendicular to the plane direction of the piezoelectric film, and τ is the shearing force in the front and back directions of the sole.
Assuming that the radius of the sensor electrode is R, there are:
therefore, in this embodiment, the plantar normal stress
And shear force
The change over time can be solved by:
wherein,
and
is the piezoelectric constant of the ith piezoelectric film.
Fig. 7 is a flowchart of the algorithm.
Claims (6)
1. A sensor for accurately detecting the normal stress and the shearing force of a sole during walking is characterized in that: the signal acquisition circuit comprises a signal acquisition part and a back-end circuit, wherein a signal output end of the signal acquisition part is connected with a signal input end of the back-end circuit;
signal acquisition part
The signal acquisition part comprises a first device protective layer, a detection unit and a second device protective layer which are sequentially arranged from top to bottom;
the detection unit comprises a first electrode, a third electrode and a second electrode which are arranged side by side and at intervals, a first piezoelectric film is arranged between the first electrode and the second device protection layer, and a second piezoelectric film is arranged between the second electrode and the second device protection layer;
the first piezoelectric film is mainly based on longitudinal piezoelectric effect and has a piezoelectric constant d33（1）>>d31（1）>>d32（1）；
The second piezoelectric film is mainly based on transverse piezoelectric effect and has a piezoelectric constant d31（2）>>d33（2）>>d32（2）；
The first electrode, the first piezoelectric film and the third electrode form a normal stress collection group together, and the second electrode, the second piezoelectric film and the third electrode form a shearing force collection group together;
the number of the detection units is at least one.
2. The sensor for accurately detecting the normal stress and the shear force of the sole of a foot according to claim 1, wherein: the back end circuit comprises a signal processing circuit, communication equipment and an upper computer which are connected in series;
the signal processing circuit comprises a first signal processing circuit and a second signal processing circuit which are connected in parallel;
the first signal processing circuit comprises a first charge amplifier and a first analog-to-digital converter, the input end of the first charge amplifier is connected with the signal output end of the positive stress acquisition group, and the output end of the first charge amplifier is connected with the first input end of the communication equipment through the first analog-to-digital converter;
the second signal processing circuit comprises a second charge amplifier and a second analog-to-digital converter, the input end of the second charge amplifier is connected with the signal output end of the shearing force acquisition group, and the output end of the second charge amplifier is connected with the second input end of the communication equipment through the second analog-to-digital converter.
3. The sensor for accurately detecting the normal stress and the shear force of the sole of a foot according to claim 2, wherein: a central processing unit is arranged between the signal processing circuit and the communication equipment;
the output end of the first charge amplifier is connected with the first input end of the central processing unit through the first analog-to-digital converter, the output end of the second charge amplifier is connected with the second input end of the central processing unit through the second analog-to-digital converter, and the signal output end of the central processing unit is connected with the upper computer through the communication equipment.
4. A sensor for accurately detecting the normal and shear stress on the sole of a foot when walking according to any one of claims 1 to 3, wherein: the electric axis of the first piezoelectric film points to the advancing direction of the sole, and the direction of the z axis is vertical to the upper direction; the mechanical axis of the second piezoelectric film points to the forward direction of the sole, and the direction of the z axis is vertical and upward.
5. A sensor for accurately detecting the normal and shear stress on the sole of a foot when walking according to any one of claims 1 to 3, wherein: the first electrode and the second electrode have the same structure.
6. A sensor for accurately detecting the normal and shear stress on the sole of a foot when walking according to any one of claims 1 to 3, wherein: when the number of the sensing cells is more than one, the third electrodes of the respective sensing cells are commonly grounded.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110200633A (en) * | 2019-07-05 | 2019-09-06 | 北京中硕众联智能电子科技有限公司 | The sensor and detection method of vola direct stress and shearing force when accurate detection walking |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110200633A (en) * | 2019-07-05 | 2019-09-06 | 北京中硕众联智能电子科技有限公司 | The sensor and detection method of vola direct stress and shearing force when accurate detection walking |
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