CN118150009A

CN118150009A - Array type circuit pressure detection system and method

Info

Publication number: CN118150009A
Application number: CN202410442381.2A
Authority: CN
Inventors: 刘丰铨; 胡正发
Original assignee: Guangdong University of Technology
Current assignee: Guangdong University of Technology
Priority date: 2024-04-12
Filing date: 2024-04-12
Publication date: 2024-06-07

Abstract

The invention discloses an array type circuit pressure detection system and method, wherein the system comprises an array type flexible film sensing unit module, a first multi-channel analog switch module, a second multi-channel analog switch module, a singlechip, a calibration resistor and an upper computer; the first end of the array type flexible film sensing unit module is connected with the first end of the first multichannel analog switch module, and the second end of the first multichannel analog switch module is connected with one end of the calibration resistor; the other end of the calibration resistor is connected with a 3.3V pin of the singlechip, and a digital-to-analog conversion module of the singlechip is connected between one end of the calibration resistor and a second end of the first multichannel analog switch module; the control end of the first multichannel analog switch module and the control end of the second multichannel analog switch module are electrically connected with the single chip; the technical problem of current array circuit pressure detecting system's design circuit is more complicated, leads to the use cost high is solved.

Description

Array type circuit pressure detection system and method

Technical Field

The invention relates to the technical field of pressure measurement, in particular to an array type circuit pressure detection system and method.

Background

With the continuous development of technology, the demand for sensors is also increasing. However, for the design of the sensor, a single sensor is generally adopted, or a plurality of sensors are integrated together to form a large-area sensor, and both the design modes of the two sensors have the defect that the sensing range of the single sensor is limited, only a specific physical quantity or environmental condition can be sensed, and a plurality of integrated sensors consume more resources, and the complexity of a system and the complexity of a circuit are increased.

The array sensor is a sensor system in which a plurality of sensors are arranged in an array or matrix form, and the data of a plurality of points are measured by utilizing the simultaneous operation of the plurality of sensors, so that richer information is provided, wider and more accurate monitoring and detection are realized, and the effects of signal processing and data analysis are improved. In various fields (microphone array in acoustic field, antenna array in radar field, detector array in medical image, etc.), array type sensor plays an important role, helping people to monitor, detect and identify more accurately and effectively.

In the existing array type circuit pressure detection system, each sensing unit is led out to form a loop by two wires, a standard resistor is needed to be inscribed for data analysis, meanwhile, ADC channels of the microprocessor are not more, a large-area array type scanning circuit is also needed to be externally connected with a digital-to-analog conversion module, the time of one period of data acquisition of all sensing units of the array type sensor is longer, the design circuit is more complex, and the application cost is high.

Disclosure of Invention

The invention provides an array type circuit pressure detection system and method, which are used for solving the technical problem that the application cost is high due to the fact that a design circuit of the existing array type circuit pressure detection system is more complex.

The invention provides an array type circuit pressure detection system, which comprises an array type flexible film sensing unit module, a first multi-channel analog switch module, a second multi-channel analog switch module, a singlechip, a calibration resistor and an upper computer, wherein the first multi-channel analog switch module is connected with the first multi-channel analog switch module;

the first end of the array type flexible film sensing unit module is connected with the first end of the first multichannel analog switch module, and the second end of the first multichannel analog switch module is connected with one end of the calibration resistor;

The other end of the calibration resistor is connected with a 3.3V pin of the singlechip, and a digital-to-analog conversion module of the singlechip is connected between one end of the calibration resistor and a second end of the first multichannel analog switch module;

the control end of the first multichannel analog switch module and the control end of the second multichannel analog switch module are electrically connected with the single chip;

The first end of the second multichannel analog switch module is grounded, and the second end of the array type flexible film sensing unit module is connected with the second end of the second multichannel analog switch module;

The singlechip is in communication connection with the upper computer;

The single chip microcomputer is used for responding to the detection instruction, after the first multichannel analog switch module and the second multichannel analog switch module are controlled to be in a conducting state, acquiring a plurality of sensing unit electric signals of the array type flexible film sensing unit module, and calculating a plurality of sensing unit pressure values according to the sensing unit electric signals and a preset inversion function group;

the upper computer is used for receiving and displaying the pressure value of each sensing unit sent by the singlechip.

Optionally, the array type flexible film sensing unit module comprises a plurality of flexible film sensing units which are connected in an array distribution manner;

The flexible film sensing units at the head end of each row of arrays are respectively connected with the first end of the first multichannel analog switch module;

the flexible film sensing units at the head ends of the arrays are respectively connected with the second ends of the second multichannel analog switch modules.

Optionally, the flexible film sensing unit includes a first electrode layer, a piezoresistive sensing unit, and a second electrode layer sequentially disposed.

Optionally, the flexible film sensing unit has a rectangular horizontal section.

Optionally, the first multi-path analog switch module includes a first multi-path analog switch and a plurality of row electrodes;

The first multichannel analog switch is provided with a plurality of first input ports, a plurality of first output ports and a plurality of first control ends;

each first control end is electrically connected with the single chip;

each first output port is connected with the flexible film sensing unit at the head end of each row of the array through each row electrode;

each first input port is connected with one end of the calibration resistor;

The digital-to-analog conversion module of the singlechip is connected between one end of the calibration resistor and each first input port.

Optionally, the second multi-path analog switch module includes a second multi-path analog switch and a plurality of column electrodes;

The second multichannel analog switch is provided with a plurality of second input ports, a plurality of second output ports and a plurality of second control ends;

Each second control end is electrically connected with the single chip;

each second input port is connected with the flexible film sensing unit at the head end of each array through each array electrode;

Each second output port is grounded.

Optionally, the single-chip microcomputer is specifically configured to:

responding to the detection instruction, and controlling the first multichannel analog switch module and the second multichannel analog switch module to be in a conducting state;

Sequentially acquiring sensing unit electric signals of the flexible film sensing units through the digital-to-analog conversion module and performing digital-to-analog conversion to generate sensing unit digital quantities corresponding to the sensing unit electric signals;

Substituting the digital quantity of each sensing unit into a preset inversion function group respectively, and calculating the pressure value of the sensing unit corresponding to the digital quantity of each sensing unit.

Optionally, the preset inversion function set specifically includes:

Wherein R _s is the resistance value of the conductive flexible film sensing unit; r is the resistance value of the calibration resistor; g is the pressure value of the sensing unit; the ADC is the digital quantity of the sensing unit.

The invention provides an array type circuit pressure detection method, which comprises the following steps:

acquiring a plurality of sensing unit electric signals of the array type flexible film sensing unit module;

performing digital-to-analog conversion on the electric signals of the sensing units to generate sensing unit digital quantities corresponding to the electric signals of the sensing units;

Optionally, the preset inversion function set specifically includes:

From the above technical scheme, the invention has the following advantages:

The first aspect of the present invention provides an array circuit pressure detection system, which includes an array flexible film sensing unit module, a first multi-path analog switch module, a second multi-path analog switch module, a singlechip, a calibration resistor and an upper computer; the first end of the array type flexible film sensing unit module is connected with the first end of the first multichannel analog switch module, and the second end of the first multichannel analog switch module is connected with one end of the calibration resistor; the other end of the calibration resistor is connected with a 3.3V pin of the singlechip, and a digital-to-analog conversion module of the singlechip is connected between one end of the calibration resistor and a second end of the first multichannel analog switch module; the control end of the first multichannel analog switch module and the control end of the second multichannel analog switch module are electrically connected with the single chip; the first end of the second multichannel analog switch module is grounded, and the second end of the array type flexible film sensing unit module is connected with the second end of the second multichannel analog switch module; the singlechip is in communication connection with the upper computer; the single chip microcomputer is used for responding to the detection instruction, after controlling the first multichannel analog switch module and the second multichannel analog switch module to be in a conducting state, acquiring a plurality of sensing unit electric signals of the array type flexible film sensing unit module, and calculating a plurality of sensing unit pressure values according to the sensing unit electric signals and a preset inversion function group; the upper computer is used for receiving and displaying the pressure value of each sensing unit sent by the singlechip; based on the scheme, the other end of the first multichannel analog switch module is only required to be connected with one end of one calibration resistor, compared with a loop formed by leading out two wires from each sensing unit in the existing array type circuit pressure detection system, a design circuit of a standard resistor is needed to be connected in an inscription mode, the use of components can be reduced, the complexity of the design circuit is reduced, and therefore the application cost is reduced.

The second aspect of the present invention provides an array circuit pressure detection method, which includes firstly obtaining a plurality of sensing unit electrical signals of an array flexible film sensing unit module, and then performing digital-to-analog conversion on each sensing unit electrical signal to generate a sensing unit digital quantity corresponding to each sensing unit electrical signal; finally, substituting the digital quantity of each sensing unit into a preset inversion function group respectively, and calculating a sensing unit pressure value corresponding to the digital quantity of each sensing unit; based on the scheme, the process of calculating the pressure value of the sensing unit according to the preset inversion function set and the digital quantity of the sensing unit obtained through digital-to-analog conversion processing can realize rapid acquisition of the pressure value of the sensing unit.

Drawings

In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained from these drawings without inventive faculty for a person skilled in the art.

Fig. 1 is a schematic structural diagram of an array circuit pressure detection system according to a first embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a flexible thin film sensor unit according to a first embodiment of the present invention;

fig. 3 is a schematic diagram of a structure of a row conductor and a column conductor according to a first embodiment of the present invention;

FIG. 4 is a schematic diagram showing the electrical signal change of the piezoresistive sensor unit according to the first embodiment of the present invention according to the change of stress;

FIG. 5 is a diagram illustrating a connection relationship between a piezoresistive sensor unit and a row electrode and a column electrode according to an embodiment of the present invention;

FIG. 6 is a schematic diagram illustrating a processing procedure of a pressure value of a sensing unit according to a first embodiment of the present invention;

FIG. 7 is a diagram showing a comparison between a pressure value of a sensing unit and an actual pressure value according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of a4×4 array circuit pressure detection system according to an embodiment of the present invention;

FIG. 9 is a diagram showing normalized curves of the relationship between maximum and minimum partial pressures and the resistance of a calibration resistor of a piezoresistive sensor unit according to an embodiment of the present invention;

FIG. 10 is a diagram showing normalized curves of the voltage division range and the calibration resistance according to the first embodiment of the present invention;

FIG. 11 is a flowchart of a fast scan procedure of a4×4 array circuit pressure detection system according to an embodiment of the present invention;

Fig. 12 is a flowchart illustrating a method for detecting pressure of an array circuit according to a second embodiment of the present invention.

Wherein the reference numerals have the following meanings:

1. An array type flexible film sensing unit module; 2. a first multi-path analog switch module; 3. a second multi-path analog switch module; 4. a single chip microcomputer; 5. calibrating the resistor; 6. a flexible thin film sensing unit; 7. a row electrode; 8. a column electrode; 9. column conductors; 10. a row conductor; 11. a first electrode layer; 12. a piezoresistive sensing unit; 13. and a second electrode layer.

Detailed Description

The embodiment of the invention provides an array type circuit pressure detection system and method, which are used for solving the technical problem that the application cost is high due to the fact that a design circuit of the existing array type circuit pressure detection system is more complex.

In order to make the objects, features and advantages of the present invention more comprehensible, the technical solutions in the embodiments of the present invention are described in detail below with reference to the accompanying drawings, and it is apparent that the embodiments described below are only some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Term interpretation:

Piezoresistance type: the material changes resistance with pressure.

Inversion: the evaluation is deduced by the existing results and the formula inverse.

Array type: and the device is orderly arranged according to M rows and N columns, and is like a gymnastics square array.

And a sensing unit: an array type sensor is formed by arranging a certain number of sensing units according to an array, wherein the sensing units are the smallest units in the sensor, and each sensing unit is independently connected with a circuit and can be regarded as one sensor.

Calibrating resistance: the resistance for dividing the voltage with the sensing unit is a constant value, and the change of the resistance of the sensing unit is determined by measuring the change of the voltage at both ends of the constant value.

R (correlation coefficient): a coefficient for measuring the degree of correlation between two variables. The closer the absolute value of the correlation coefficient is to 1, the stronger the correlation between the variables is explained. If the correlation coefficient is greater than 0, positive correlation is shown between the two; if the correlation coefficient is less than 0, it indicates that there is a negative correlation between the two.

R square (determining coefficient): the decision coefficient, also called goodness of fit, is usually used to describe how well the data fit to the model, and represents how well the independent variable X interprets the dependent variable Y. The closer the R square value is between 0 and 1, the better the regression fit effect is. For example R-party = 0.5, then the explanatory argument may explain the cause of the 50% change in the dependent variable.

Referring to fig. 1, fig. 1 is a schematic structural diagram of an array circuit pressure detection system according to an embodiment of the invention.

The invention provides an array type circuit pressure detection system which comprises an array type flexible film sensing unit module 1, a first multichannel analog switch module 2, a second multichannel analog switch module 3, a singlechip 4, a calibration resistor 5 and an upper computer, wherein the calibration resistor is connected with the upper computer;

referring to fig. 1, a first end of an array type flexible film sensing unit module 1 is connected with a first end of a first multi-path analog switch module 2, and a second end of the first multi-path analog switch module 2 is connected with one end of a calibration resistor 5;

The array type flexible film sensing unit module 1 is composed of a plurality of flexible film sensing units 6 which are connected in an array distribution mode, each flexible film sensing unit 6 comprises a first electrode layer 11, a piezoresistive sensing unit 12 and a second electrode layer 13 which are sequentially arranged, the first multichannel analog switch module 2 is composed of a first multichannel analog switch and a plurality of row electrodes 7, and the first multichannel analog switch is provided with a plurality of first input ports and a plurality of first output ports.

It should be noted that, the first end of the array flexible film sensing unit module 1 is the flexible film sensing unit 6 at the head end of each row array, each flexible film sensing unit 6 at the head end of each row array is correspondingly connected to one end of a row electrode 7 through the second electrode layer 13, that is, the first end of the array flexible film sensing unit module 1 is connected to the first end of the first multichannel analog switch module 2, the other end of each row electrode 7 is correspondingly connected to one output port of the first multichannel analog switch, each input port of the first multichannel analog switch is all connected to one end of one calibration resistor 5, that is, the second end of the first multichannel analog switch module 2 is connected to one end of the calibration resistor 5, and the first multichannel analog switch is arranged on the connection path between the flexible film sensing unit 6 at the head end of each row array and the calibration resistor 5.

The other end of the calibration resistor 5 is connected with a 3.3V pin of the singlechip 4, and a digital-to-analog conversion module of the singlechip 4 is connected between one end of the calibration resistor 5 and the second end of the first multi-channel analog switch module 2;

the control end of the first multichannel analog switch module 2 and the control end of the second multichannel analog switch module 3 are electrically connected with the singlechip 4;

the first end of the second multichannel analog switch module 3 is grounded, and the second end of the array type flexible film sensing unit module 1 is connected with the second end of the second multichannel analog switch module 3;

The second multi-path analog switch module 3 is composed of a second multi-path analog switch provided with a plurality of second input ports and a plurality of second output ports, and a plurality of column electrodes 8.

It should be noted that, the second end of the array flexible film sensing unit module 1 is the first electrode layer 11 of the flexible film sensing unit 6 at the head end of each column array, each first electrode layer 11 of the flexible film sensing unit 6 at the head end of the column array is correspondingly connected to one end of one column electrode 8, that is, the second end of the array flexible film sensing unit module 1 is connected to the second end of the second multichannel analog switch module 3, the other end of each column electrode 8 is correspondingly connected to one input port of the second multichannel analog switch, and all output ports of the second multichannel analog switch are grounded, that is, the first end of the second multichannel analog switch module 3 is grounded.

The singlechip 4 is in communication connection with the upper computer;

the control end of the first multi-path analog switch module 2 and the control end of the second multi-path analog switch module 3 are both control pins.

Referring to fig. 1, the control pin of the first multichannel analog switch module 2 and the control pin of the second multichannel analog switch module 3 are electrically connected with the I/O port of the single chip microcomputer 4, the other end of the calibration resistor 5 is connected with the 3.3V pin of the single chip microcomputer 4, i.e. the other end of the calibration resistor 5 is connected with the 3.3V voltage supplied by the single chip microcomputer 4 to form a loop with 3.3V-GND, so as to obtain a serial connection relationship between the calibration resistor 5 and the whole array flexible film unit, i.e. the array flexible film sensing unit module 1, wherein the single chip microcomputer 4 is specifically the stm32 single chip microcomputer 4, the stm32 single chip microcomputer 4 is internally provided with an ADC digital-analog conversion module, and a specific pin is connected between the calibration resistor 5 and the array film, i.e. the ADC digital-analog conversion module (ADC digital-analog conversion module) of the single chip microcomputer 4 is connected between one end of the calibration resistor 5 and the second end of the first multichannel analog switch module 2, so as to form ADC measurement (measurement of the electrical signal of the sensing unit).

The singlechip 4 is used for responding to the detection instruction, controlling the first multichannel analog switch module 2 and the second multichannel analog switch module 3 to be in a conducting state, acquiring a plurality of sensing unit electric signals of the array flexible film sensing unit module 1, and calculating a plurality of sensing unit pressure values according to the sensing unit electric signals and a preset inversion function group;

the upper computer is used for receiving and displaying the pressure value of each sensing unit sent by the singlechip 4.

It should be noted that, the level states of the first multi-channel analog switch module 2 and the second multi-channel analog switch module 3 are controlled through the I/O port of the single chip microcomputer 4, so that after the first multi-channel analog switch module 2 and the second multi-channel analog switch module 3 are in a conducting state, the ADC digital-to-analog conversion module of the single chip microcomputer 4 obtains a plurality of sensing unit electric signals of the array flexible film sensing unit module 1 and performs digital-to-analog conversion, so as to obtain sensing unit digital values corresponding to the sensing unit electric signals, and then according to the sensing unit digital values and the preset inversion function groups, a plurality of sensing unit pressure values are calculated and transmitted to the upper computer, and the upper computer displays the sensing unit pressure values.

As a further improvement, the array type flexible film sensing unit module 1 comprises a plurality of flexible film sensing units 6 which are connected in an array distribution manner; the flexible film sensing units 6 at the head ends of the rows of arrays are respectively connected with the first ends of the first multichannel analog switch modules 2; the flexible film sensing units 6 at the head ends of the arrays are respectively connected with the second ends of the second multi-channel analog switch modules 3.

Alternatively, the flexible thin film sensing unit 6 includes a first electrode layer 11, a piezoresistive sensing unit 12, and a second electrode layer 13, which are sequentially disposed.

Alternatively, the flexible film sensor unit 6 has a rectangular horizontal section.

Referring to fig. 2-3, the flexible thin film sensing unit 6 is composed of a second electrode layer 13, a first electrode layer 11 and an intermediate dielectric layer, wherein the second electrode layer 13 and the first electrode layer 11 are the same conductive thin film or electrode, and the intermediate dielectric layer is a corresponding sensing unit which is piezoresistive, has extremely high resistance under the condition of no stress, or is open circuit, but has the resistance which changes along with the change of pressure after being stressed; the array type flexible film sensing unit module 1 is composed of a plurality of flexible film sensing units 6 which are distributed and connected in an array mode, as shown in fig. 3, first electrode layers 11 of the flexible film sensing units 6 are connected in series to form a row wire 10, and second electrode layers 13 of the flexible film sensing units 6 are connected in series to form a column wire 9.

Referring to fig. 4, the resistance value of the sensing unit of the single flexible film sensing unit 6 is measured by using a multimeter, the sensing unit exhibits resistance property after being pressed, and its characteristic is changed with the change of pressure, the pressure is applied to the single-point sensing unit by using a weight, a manometer, etc., and the change of resistance is recorded, which is similar to an inverse proportion function, in other words, a state that its conductance is linear with the change of pressure, and its conductance is increased with the increase of pressure. As shown in fig. 3: the pressure law is that when the sensing unit is subjected to pressure, the resistance is reduced along with the pressure increase, the piezoresistive property is expressed as that the resistance and the pressure are in a power function relation, the inverse resistance and the pressure are in an approximate linear relation, namely, the larger the conductive performance of the sensing unit is inversely proportional to the pressure, the stronger the conductive performance is, and then the pressure value is inversely proportional to the resistance value of the sensing unit, directly proportional to the conductivity of the sensing unit and linearly exists in a certain range according to a plurality of groups of experimental data.

As a further improvement, the first multi-path analog switch module 2 includes a first multi-path analog switch and a plurality of row electrodes 7; the first multichannel analog switch is provided with a plurality of first input ports, a plurality of first output ports and a plurality of first control ends; each first control end is electrically connected with the singlechip 4; each first output port is connected with a flexible film sensing unit 6 at the head end of each row of arrays through each row of electrodes 7; each first input port is connected with one end of the calibration resistor 5; the digital-to-analog conversion module of the singlechip 4 is connected between one end of the calibration resistor 5 and each first input port.

Optionally, the second multi-path analog switch module 3 comprises a second multi-path analog switch and a plurality of column electrodes 8; the second multichannel analog switch is provided with a plurality of second input ports, a plurality of second output ports and a plurality of second control ends; each second control end is electrically connected with the singlechip 4; each second input port is connected with the flexible film sensing unit 6 at the head end of each column array through each column electrode 8; each second output port is grounded.

Referring to fig. 5, for example, a 4×4 array circuit pressure detection system, four flexible film sensing units 6 at the head end of each row array are correspondingly connected to one end of a row electrode 7, and the other end of each row electrode 7 is correspondingly connected to one output port of a first multichannel analog switch, where all input ports of the first multichannel analog switch are connected to one end of a calibration resistor 5; the four flexible film sensing units 6 at the head end of each column array are correspondingly connected with one end of one column electrode 8, and the other end of each column electrode 8 is correspondingly connected with one input port in the second multichannel analog switch, and all output ports in the second multichannel analog switch are grounded.

As a further improvement, the single-chip microcomputer 4 is specifically configured to:

Responding to the detection instruction, and controlling the first multi-path analog switch module 2 and the second multi-path analog switch module 3 to be in a conducting state; sequentially acquiring sensing unit electric signals of each flexible film sensing unit 6 through a digital-to-analog conversion module, and performing digital-to-analog conversion to generate sensing unit digital quantities corresponding to the sensing unit electric signals; substituting the digital quantity of each sensing unit into a preset inversion function group respectively, and calculating the pressure value of the sensing unit corresponding to the digital quantity of each sensing unit.

It should be noted that, the control pin of the single chip microcomputer 4 controls the first multi-path analog switch module 2 to be in a conducting state, so as to gate the flexible film sensing units 6 of the row array in the array type flexible film sensing unit module 1, and controls the second multi-path analog switch module 3 to be in a conducting state, so as to gate the flexible film sensing units 6 of the column array in the array type flexible film sensing unit module 1, one column can be positioned after each gate, so as to sequentially position and collect the pressure values of the sensing units of the partial pressure of the flexible film sensing units 6 of the (1, 1) - > (M, N) points,

Referring to fig. 6, the processing procedure of the pressure value of the sensing unit specifically includes: firstly, acquiring sensing unit electric signals of a flexible film sensing unit 6 through an ADC digital-to-analog conversion module of an STM32 singlechip 4, performing digital-to-analog conversion on the sensing unit electric signals to obtain sensing unit digital quantities, substituting the sensing unit digital quantities into a preset inversion function group, and calculating sensing unit pressure values corresponding to the sensing unit digital quantities; the method comprises the following steps of:

Wherein R _s is the resistance value of the conductive flexible film sensing unit; r is the resistance value of the calibration resistor 5; g is the pressure value of the sensing unit; the ADC is the digital quantity of the sensing unit.

Further, referring to fig. 7, since the STM32 single-chip microcomputer 4 has a very high working frequency, and the reading time interval of the ADC can be set to be microsecond or millisecond, so that the time of a working period is very short, the working tasks in the period can be regarded as the same time, and the real-time performance is very high, and the comparison relation between the pressure value calculated by presetting the inversion function group and the actual stressed value is as shown in fig. 7, and the two are very similar, and the accuracy is good.

For example, referring to fig. 8, the 16 flexible thin film sensing units 6 are arranged in an array distribution and connected in four rows and four columns to form a 4x4 lattice, and four row conductors 10 and four column conductors 9 are formed to be stacked with each other to lead out 8 electrodes, wherein (1, 1) - > (4, 4) is the array number of the 16 flexible thin film sensing units 6; the first multi-channel analog switch module 2 and the second multi-channel analog switch module 3 adopt a CD4066BM four-way analog switch or a CD4066BM four-way two-way analog switch to screen a conducting loop, the CD4066BM four-way analog switch adopts a CMOS technology, has lower power consumption, is suitable for being used in low-power consumption application, has high anti-interference performance, can reliably work in a noise environment, has wide working voltage range, can normally work under the power supply voltage of 3V to 18V, has lower input resistance, and can provide better signal transmission and driving capability; the device also has a high switching speed, making it suitable for high-speed signal switching and data processing applications, and a low leakage current can reduce power consumption and improve system stability. The IC comprises 4 independent double-pole double-throw switches, each switch has two inputs and one output, and can realize multi-channel signal switching and selection; in the 4×4 array circuit pressure detection system, as shown in fig. 8, the flexible film sensor units 6 at the head ends of the rows and the arrays are (1, 1), (2, 1), (3, 1), (4, 1), and the flexible film sensor units 6 at the head ends of the columns and the arrays are (1, 1), (1, 2), (1, 3), (1, 4), respectively.

Further, by means of the four-way analog switches of the two CDs 4066BM, one is responsible for gating the row circuit and one is responsible for gating the column circuit, so that a row-column array lattice is formed, a flexible thin film sensing unit 6 can be positioned one column per gate, for example, a first row and a first column are gated, and the output analog quantity of the ADC is the voltage division value with the flexible thin film sensing unit (1, 1). The sensing unit pressure value of the (1, 1) - > (4, 4) flexible film sensing unit 6 can be positioned in the same way, wherein the sensing unit pressure value is divided by the calibration resistor 5 and the film, and the resistance value of the flexible film sensing unit 6 can be obtained by measuring the voltage values at the two ends of the calibration resistor 5, so that the stress condition of the flexible film sensing unit is deduced.

Further, 8 IO ports of the STM32 singlechip 4 are respectively connected to the control end of the CD4066BM four-way two-way analog switch, and are responsible for controlling the on and off of each channel. In the piezoresistive sensor, the location of the (flexible film sensing unit 6) point and the value thereof are key of the whole sensor, based on the above, the dot matrix of 16 flexible film sensing units 6 is divided into 4 rows and 4 columns, the row and column coordinates thereof are respectively from (1, 1) to (4, 4), the high level of the control pin of the four-way analog switch of the CD4066BM is controlled through the IO port of the STM32 singlechip 4, the high level of the port A of one CD4066BM is given first, namely the first row is conducted, at the moment, the high level is given to the port A, B, C, D of the other CD4066BM sequentially, when one port is high, the other ports are all pulled down, for example, the column is given to the row control port A and the column control port A, namely the conduction (1, 1) point loop, and the measured partial pressure is the partial pressure of the corresponding resistor of the flexible film sensing unit 6 at the point (1, 1).

Further, the calculation principle of the partial pressure formula is as follows: since the resistance value of the sensing unit of each gating of the known array flexible film pressure strain sensor (flexible film sensing unit 6) changes along with the pressure change, the partial pressure of the sensing unit changes along with the pressure change when the sensing unit is connected in series with the calibration resistor 5, and based on the principle, the relation formula of the partial pressure value of the sensing unit read by the ADC digital-analog conversion module and the calibration resistor 5 can be obtained as follows:

Wherein U is the partial pressure value of the gated flexible film sensing unit; r _s is the resistance value of the conductive flexible film sensing unit; r is the resistance value of the calibration resistor.

Further, referring to fig. 9, since the optimal value of the calibration resistor R needs to be determined, after knowing the value range of the resistor of the flexible film sensing unit 6, that is, knowing the resistor value range of the flexible film sensing unit 6, the voltage dividing principle can obtain the required resistance value of the calibration resistor 5, so that the test value range is increased, that is, the voltage dividing range is increased as much as possible, and the ADC digital-analog conversion module of the STM32 monolithic ADC can only measure the voltage of 3.3V as much as possible, so that the voltage dividing range accords with 0-3.3V as much as possible, and the voltage dividing range is the largest at this time, and the measurement accuracy is the largest. The formula for calculating the normalized partial pressure maximum value and the normalized partial pressure minimum value of the calibration resistor is calculated by a partial pressure formula, and specifically comprises the following steps:

Wherein y ₁ is the maximum value of the normalized partial pressure, y ₂ is the minimum value of the normalized partial pressure, R is the resistance value of the calibration resistor, and the resistance value change range of the flexible film sensing unit is about 3k omega-400 k omega through experimental measurement.

Further, referring to fig. 10, when the value of the standard resistor (calibration resistor) of the design circuit is a fixed value, the voltage division range is the maximum voltage division minus the minimum voltage division of the circuit, i.e., y=y ₁-y₂, when the value of the voltage division range is 0.8 precision, a better solution of the calibration resistor 5 can be obtained, and according to the voltage variation range curve, a 35k Ω resistor is selected as the calibration resistor 5, and the voltage division range is the most suitable for experiments; where y is the circuit voltage range difference, y ₁ is the normalized partial pressure maximum, and y ₂ is the normalized partial pressure minimum.

Further, after the connection circuit of the 4×4 array circuit pressure detection system is determined, circuit control, data processing and transmission are performed by using an STM32 singlechip, specifically, the STM32 singlechip controls a GPIO port to enable a scanning circuit to perform rapid scanning, at the moment of each scanning unit, an ADC digital-to-analog conversion module in the STM32 singlechip reads the instant analog quantity of the current conducting circuit and converts the instant analog quantity into digital quantity, data are stored in a memory of the singlechip, and finally serial port communication is enabled by an STM32 control usart module to transmit the data to an upper computer for display.

Based on the above, please refer to fig. 11, a sensor scanning code is designed for a 4×4 array circuit pressure detection system, specifically, first, two variables i and j are defined in a main function, corresponding to rows and columns, to determine a point scanned by the current scanning, gradually scan (4, 4) from coordinates (1, 1) through a for loop, complete a scanning loop, read an ADC value scanned to the point in the middle of the scanning loop, and execute an INV function, where the function functions to convert the read digital quantity into a pressure value to be displayed through calculation, and finally output the inverted data to an upper computer through a serial port communication array;

For the INV function, namely presetting an inversion function group, determining that the scanning read by the ADC at a certain moment is a certain confirmed point through a scanning function, firstly reading the ADC value of the point, calculating a corresponding resistance Rs through a partial pressure formula, and calculating a stress condition G corresponding to the sensitive unit through inversion of the resistance Rs by using the inversion function; specifically, the acquired digital quantity is converted into a voltage value, and as the accuracy of the ADC of the STM32 single-chip microcomputer is 12 bits, that is, the digital quantity is 212=4096 at maximum, and the ADC reference voltage is 3.3V at maximum, the digital quantity corresponding to the analog quantity of 3.3V is 4096, the conversion formula is:

Wherein U is the partial pressure value of the gated flexible film sensing unit; the ADC is the digital quantity of the sensing unit.

Further, in the known array flexible film pressure strain sensor (flexible film sensing unit 6), the resistance change and the stress are in a power function relationship, and the inverse of the resistance and the stress are in a linear relationship, so that the linear relationship is obtained by fitting through experiments:

R_s＝0.01105+8.22253×10^-5H；

Wherein R _s is the reciprocal value of the flexible film sensing unit; h is the pressure applied by the flexible film sensing unit, and the unit is g. At this time, the calculation can obtain that the R (correlation coefficient) of the linear fitting straight line is 0.99190, the R square (determination coefficient) is 0.98386, and both values are close to 1, namely the height of the fitting straight line accords with the law of the stress and the electric signal change of the sensing unit.

Based on the above-mentioned basis, the relation between the pressure applied to the piezoresistive sensor unit 12 and the resistance thereof is:

wherein R _s is the resistance value of the conductive flexible film sensing unit; g is the pressure value of the sensing unit, and the unit is G.

Further, the resistance value of the gated piezoresistive sensor unit 12 can be obtained by converting the value read by the ADC and inverting the partial pressure formula above:

wherein R _s is the resistance value of the conductive flexible film sensing unit; r is the resistance value of the calibration resistor; the ADC is the digital quantity of the sensing unit.

In this embodiment, the working process of the array circuit pressure detection system provided by the application is as follows: the continuous circulation scanning circuit is used for continuously reading the ADC value in the operation period of the scanning circuit, inverting the stressed value through a preset inversion function group and outputting the stressed value to the upper computer for display; the application can realize 4×4 array, and design M×N large array sensor by selecting proper multi-path analog switch or multiple multi-path analog switches or even multiple ADCs. For example, if an 8×8 array piezoresistive sensor (8×8 array circuit pressure detection system) is designed, the four-way analog switch selected in the above example is changed to an appropriate eight-way analog switch or two four-way analog switches are combined together, if the eight-way analog switch is selected, there are eight groups of IO ports, but only 3 control ports are provided, the conducting IO ports are in a 2-system mode, the eight IO ports are numbered 0-7, then the three control ports are respectively a, B and C, the ABC is given a high level, the ABC is given a low level is given a 0, the conduction can be controlled in a 2-system mode, if the pair of IO ports with the label of 0 is to be conducted, the control port ABC is pulled low, namely 000, if the number 7 IO ports are to be controlled, and the ABC is given a high level, namely 111.

Further, in terms of time, if the m×n array rows and columns to be designed are relatively large, considering that only one ADC is used, the scan period is relatively large, and another ADC channel of the same STM32 may be used to read data, so that the scan period time may be reduced, one standard resistor is necessarily required for one ADC scan to perform comparison, and multiple standard resistors are required for multiple ADC scans to perform comparison, where the design circuit complexity of the present application is far less than that of other existing circuit design methods at present under the condition of equal specification.

As comparison of technical effects, reference can be made by combining with the prior art, and the circuit design and program implementation of the prior array type sensor are related to less people in the field, and the program for implementing the array type scanning is not yet opened, so that the rapid scanning design and method of the array type flexible film sensor still have many research spaces and development directions; in the current common array sensor circuit design method, each sensing module is basically connected with one circuit for data reading, so that after the number of arrays is increased, the number of circuit lines is increased. The circuit complexity increases.

Based on the above, the complexity of designing a circuit is high, and basically three cases are divided: (1) The most traditional circuit is designed in such a way that each sensing unit is led out of two wires to form a loop, and a standard resistor is needed to be connected in the loop for data analysis, namely for an MxN array sensor, the circuit at least needs to be led out of 2 MxN wires and connected into 2 MxN resistors; some existing circuit designs need to access each path to an ADC for data acquisition, the occupied pins are more or the occupied resources are large, the ADC channels carried by a general microprocessor are not more, the large-area array scanning circuit possibly needs to be externally connected with an ADC module, so that the circuit is more complex, the more complex the design circuit is, the more complex the PCB is manufactured, the more the purchase amount of components is, the longer the time of one period of data acquisition of all sensing units of the array sensor is, so that the defects of high cost of ownership, large volume and portability are caused

(2) For some optimized circuits, each row and each column is connected with a wire, the formed loop is connected with a standard resistor, and an M multiplied by N array sensor (0 < M < N) is assumed, so that at least M+N wires are required to be led out from the circuit and M standard resistors are required to be connected;

(3) Still other circuits may use microcontrollers and diodes for circuit design, but in this design, each column of each row is connected to one conductor, each sensing unit needs to be connected in series with one diode, and assuming an M x N array sensor (0 < M < N), the circuit needs to have at least m+n conductors, M x N diodes and a microcontroller.

In view of the above, the present application provides an array circuit pressure detection system, which uses a multichannel analog switch (using a multichannel analog switch as a selection chip), uses an array arrangement method to arrange sensing units, and uses an array type lead-out row conductor 10 and a column conductor 9 to access a circuit, i.e. the circuits thereof only need to access each channel of a switch with a proper channel to each row and each column, and all the channels are connected to the same standard resistor, and controls the sensing units through an STM32 singlechip. The application provides an array sensor (0 < M < N), which is provided with M+N wires, 1 standard resistor and a microcontroller, wherein for the existing method, the use of components is reduced, the complexity of the circuit is reduced, and the application can carry out rapid data acquisition on the array sensor by only accessing an ADC digital-analog conversion module, the program flow of rapid data scanning and reading is determinant scanning, the actual value is obtained by inversion function inversion, the derivation process of the preset inversion function group is formed by fitting according to the resistor series voltage division theorem and a large amount of experimental data, the resource occupancy rate is greatly reduced, meanwhile, the application can manufacture smaller products with lower cost compared with other existing schemes because of low circuit complexity and small occupied resource, and the STM32 singlechip has the characteristics of high working frequency, strong stability and multiple peripheral functions, and can control the scanning circuit to microsecond or time period and millisecond.

Furthermore, the STM32 singlechip adopted by the application is provided with a plurality of ADC ports, a plurality of ADCs can be used, and a plurality of IO ports are arranged, so that more multi-channel analog switches can be controlled, the design of the scanning circuit of the existing array piezoresistive sensor is optimized, the complexity of the sensor circuit is greatly reduced, and the specification of the sensor to be produced can be more light and miniaturized; based on the optimized array piezoresistive sensor scanning circuit, a rapid scanning circuit and a data acquisition program are designed, so that the sensor achieves a rapid data acquisition method with real-time performance and accuracy, the problems of large data acquisition processing capacity and more occupied resources of the array sensor are solved, inversion of data can be realized based on a simple inversion formula, meanwhile, the defect of low expansibility of the traditional array sensor is overcome, and the array piezoresistive sensor has strong expansibility and can be compatible with integration of a plurality of formed arrays.

In the embodiment of the invention, the invention provides an array type circuit pressure detection system, which comprises an array type flexible film sensing unit module, a first multi-channel analog switch module, a second multi-channel analog switch module, a singlechip, a calibration resistor and an upper computer; the first end of the array type flexible film sensing unit module is connected with the first end of the first multichannel analog switch module, and the second end of the first multichannel analog switch module is connected with one end of the calibration resistor; the other end of the calibration resistor is connected with a 3.3V pin of the singlechip, and a digital-to-analog conversion module of the singlechip is connected between one end of the calibration resistor and a second end of the first multichannel analog switch module; the control end of the first multichannel analog switch module and the control end of the second multichannel analog switch module are electrically connected with the single chip; the first end of the second multichannel analog switch module is grounded, and the second end of the array type flexible film sensing unit module is connected with the second end of the second multichannel analog switch module; the singlechip is in communication connection with the upper computer; the single chip microcomputer is used for responding to the detection instruction, after controlling the first multichannel analog switch module and the second multichannel analog switch module to be in a conducting state, acquiring a plurality of sensing unit electric signals of the array type flexible film sensing unit module, and calculating a plurality of sensing unit pressure values according to the sensing unit electric signals and a preset inversion function group; the upper computer is used for receiving and displaying the pressure value of each sensing unit sent by the singlechip; according to the scheme, the other end of the first multichannel analog switch module is only required to be connected with one end of one calibration resistor, compared with a loop formed by leading out two wires from each sensing unit in the existing array type circuit pressure detection system, a design circuit of a standard resistor is needed to be connected in an inscription mode, the use of components can be reduced, the complexity of the design circuit is reduced, and therefore the application cost is reduced.

Referring to fig. 12, fig. 12 is a flowchart illustrating a method for detecting pressure of an array circuit according to a second embodiment of the invention.

Step 1201, acquiring a plurality of sensing unit electrical signals of the array flexible film sensing unit module.

In this embodiment, a plurality of sensor unit electrical signals of an array-type flexible thin film sensor unit module are acquired.

Step 1202, digital-to-analog conversion is performed on the electrical signals of each sensing unit, so as to generate a sensing unit digital quantity corresponding to the electrical signals of each sensing unit.

In this embodiment, digital-to-analog conversion is performed on each sensing unit electrical signal, so as to generate a sensing unit digital quantity corresponding to each sensing unit electrical signal.

And 1203, substituting the digital quantity of each sensing unit into a preset inversion function group respectively, and calculating a sensing unit pressure value corresponding to the digital quantity of each sensing unit.

Further, presetting an inversion function group, specifically:

Wherein, the resistance value of the flexible film sensing unit is conducted; the resistance value of the resistor is calibrated; is the pressure value of the sensing unit; is the digital quantity of the sensing unit.

In this embodiment, the digital values of the sensing units are substituted into a preset inversion function set, and the pressure values of the sensing units corresponding to the digital values of the sensing units are calculated.

In the embodiment of the invention, the invention provides an array type circuit pressure detection method, which comprises the steps of firstly obtaining a plurality of sensing unit electric signals of an array type flexible film sensing unit module, and then performing digital-to-analog conversion on the sensing unit electric signals to generate sensing unit digital quantities corresponding to the sensing unit electric signals; finally, substituting the digital quantity of each sensing unit into a preset inversion function group respectively, and calculating a sensing unit pressure value corresponding to the digital quantity of each sensing unit; according to the scheme, the process of calculating the pressure value of the sensing unit according to the preset inversion function group and the digital quantity of the sensing unit obtained through digital-to-analog conversion processing can realize rapid acquisition of the pressure value of the sensing unit.

In the several embodiments provided by the present application, it should be understood that the disclosed systems and methods may be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.

The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

The above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. The array type circuit pressure detection system is characterized by comprising an array type flexible film sensing unit module, a first multichannel analog switch module, a second multichannel analog switch module, a singlechip, a calibration resistor and an upper computer;

The singlechip is in communication connection with the upper computer;

2. The array circuit pressure detection system of claim 1, wherein the array flexible film sensing unit module comprises a plurality of flexible film sensing units connected in an array distribution;

3. The array circuit pressure sensing system of claim 2, wherein the flexible thin film sensing unit comprises a first electrode layer, a piezoresistive sensing unit, and a second electrode layer disposed in sequence.

4. The array circuit pressure sensing system of claim 2, wherein the flexible membrane sensing unit is rectangular in horizontal cross-section.

5. The array circuit pressure detection system of claim 2, wherein the first multi-path analog switch module comprises a first multi-path analog switch and a plurality of row electrodes;

each first control end is electrically connected with the single chip;

each first input port is connected with one end of the calibration resistor;

6. The array circuit pressure sensing system of claim 2, wherein the second multi-path analog switch module comprises a second multi-path analog switch and a plurality of column electrodes;

Each second control end is electrically connected with the single chip;

Each second output port is grounded.

7. The array circuit pressure detection system of claim 2, wherein the single-chip microcomputer is specifically configured to:

8. The array circuit pressure detection system of claim 7, wherein the preset inversion function set is specifically:

9. An array type circuit pressure detection method is characterized by comprising the following steps:

10. The method for detecting the pressure of the array circuit according to claim 9, wherein the preset inversion function set specifically comprises: