阅读说明：本技术 压力分布检测装置及在线消除柔性薄膜压力分布检测系统时间漂移的方法 (Pressure distribution detection device and method for eliminating time drift of flexible film pressure distribution detection system on line ) 是由 叶宏 汪晓阳 陈新振 于 2021-06-24 设计创作，主要内容包括：本发明公开一种压力分布检测装置,包括柔性薄膜压力分布测试系统、称重系统,以及装有压力分布检测软件的上位机；柔性薄膜压力分布测试系统包括用于获取待测物体各单位面积的压力或压强分布数据的柔性薄膜压力感测片以及第一传输模块；称重系统包括用于获取柔性薄膜压力感测片的整体受力G的称重传感以及第二传输模块；压力分布检测软件在被上位机运行时,根据所述压力或压强分布数据计算待测物体各单位面积的压力之和Fs,以及计算与压力之和Fs和整体受力G相关的动态校准系数,并通过所述动态校准系数对各单位面积的压力或压强数据进行修正。本发明能够有效消除柔性薄膜压力传感器的漂移,提高压力分布检测的准确度。(The invention discloses a pressure distribution detection device, which comprises a flexible film pressure distribution testing system, a weighing system and an upper computer provided with pressure distribution detection software; the flexible film pressure distribution test system comprises a flexible film pressure sensing sheet and a first transmission module, wherein the flexible film pressure sensing sheet is used for acquiring pressure or pressure distribution data of each unit area of an object to be tested; the weighing system comprises a weighing sensor and a second transmission module, wherein the weighing sensor is used for acquiring the integral stress G of the flexible film pressure sensing sheet; when the pressure distribution detection software is operated by an upper computer, calculating the pressure sum Fs of each unit area of the object to be detected according to the pressure or pressure distribution data, calculating a dynamic calibration coefficient related to the pressure sum Fs and the whole stress G, and correcting the pressure or pressure data of each unit area through the dynamic calibration coefficient. The invention can effectively eliminate the drift of the flexible film pressure sensor and improve the accuracy of pressure distribution detection.)

1. A pressure distribution detecting apparatus, characterized by comprising: the flexible film pressure distribution testing system comprises a flexible film pressure distribution testing system, a weighing system and an upper computer provided with pressure distribution detection software;

the flexible film pressure distribution testing system comprises a flexible film pressure sensing sheet and a first transmission module, wherein the flexible film pressure sensing sheet is used for acquiring pressure or pressure distribution data of each unit area of an object to be tested, and the first transmission module is used for uploading the pressure or pressure distribution data to an upper computer;

the weighing system comprises a weighing sensor for acquiring the integral stress G of the flexible film pressure sensing sheet and a second transmission module for uploading the integral stress G to an upper computer;

when the pressure distribution detection software is operated by an upper computer, calculating the pressure sum Fs of each unit area of the object to be detected according to the pressure or pressure distribution data, calculating a dynamic calibration coefficient related to the pressure sum Fs and the whole stress G, and correcting the pressure or pressure data of each unit area through the dynamic calibration coefficient.

2. The pressure distribution sensing device according to claim 1, further comprising a pressure transmission system for transmitting the entire force G applied to the flexible film pressure sensing patch to the load cell.

3. The pressure distribution detecting apparatus according to claim 2, wherein the pressure transmission system includes a bearing plate, the object to be measured and the flexible film pressure-sensing sheet are disposed above the bearing plate, and the load cell is disposed below the bearing plate.

4. The apparatus according to claim 1, wherein the load cell has a support surface for supporting the flexible film pressure sensing sheet and the object to be measured.

5. The pressure distribution detecting device according to any one of claims 1 to 4, wherein the load cell is a load cell sensor.

6. The pressure distribution detection device according to any one of claims 1 to 4, wherein the first transmission module is a pressure distribution collector, and is configured to convert an analog signal output by the flexible thin film pressure sensing sheet into digital information and then upload the digital information to an upper computer;

the second transmission module is a pressure transmitter and is used for converting the analog signals output by the weighing sensor into digital information and then transmitting the digital information to an upper computer.

7. A method for eliminating time drift of a flexible film pressure distribution detection system on line, comprising:

acquiring pressure or pressure distribution data of each unit area of an object to be detected, and calculating the sum Fs of the pressures of each unit area of the object to be detected according to the pressure or pressure distribution data;

acquiring the integral stress G of the flexible film pressure sensing sheet;

calculating a dynamic calibration coefficient relating to said sum of pressures Fs and said overall force G;

and correcting the pressure or pressure data of each unit area through the dynamic calibration coefficient.

8. The method of claim 7, wherein the pressure or pressure distribution data of each unit area of the object to be measured is obtained by a flexible film pressure sensing sheet; and acquiring the integral stress G of the flexible film pressure sensing sheet through the weighing sensor.

9. The method of claim 7, further comprising zeroing the load data measured by the load cell to equal the overall force G of the flexible membrane pressure sensing patch in the initial state.

10. The method according to any one of claims 7 to 9, wherein the linearly correcting the pressure or pressure data per unit area in the pressure distribution data by the dynamic calibration coefficient includes:

the pressure or pressure value per unit area is multiplied by a dynamic calibration factor, k, G/Fs, respectively.

11. The method according to any one of claims 7 to 9, wherein the performing a weighted correction on the pressure or pressure data per unit area by the dynamic calibration coefficients specifically comprises:

calculating a K value according to the formula (1) and the formula (2), and calculating a weighting correction coefficient K (x, y) corresponding to each unit area based on the formula (1);

K(x,y)＝K×{A×Lg[P(x,y)]+B} (1)

Fs＝G＝Sum[G(x,y)×K(x,y)] (2)

wherein K represents an overall correction coefficient, K (x, y) represents a correction coefficient of a grid point of a coordinate point (x, y), G (x, y) represents the original stress of the coordinate point (x, y) before the correction of the film pressure sensing piece, P (x, y) represents the original pressure value of the coordinate point (x, y) before the correction of the film pressure sensing piece, A represents the slope of a correction curve, B represents the intercept of the correction curve, and AB is determined by calculating the slope and the intercept of a linear function trend line of an actual pressure curve of the flexible film pressure sensing piece;

the dynamic calibration coefficient is a weighted correction coefficient K (x, y) of each point, and the pressure or pressure value of each unit area is multiplied by the weighted correction coefficient K (x, y) corresponding to each unit area.

Technical Field

The invention belongs to the technical field of pressure distribution detection, and particularly relates to a method for eliminating time drift of a flexible film pressure distribution detection system and a system for realizing accurate pressure distribution detection.

Background

The flexible film type pressure distribution detecting sensor inevitably has a drift problem because of the use of a flexible material therein. When a fixed constant force is applied to the thin film pressure distribution sensor, the detected pressure data will slowly rise with time. At present, the drift problem is not solved well.

For the scene of testing pressure distribution instantaneously or in a short time, the influence of time drift is not too large, but for the application requirement of testing pressure distribution change for a long time, the drift problem is a key factor influencing the accuracy of the flexible film pressure distribution testing system, and the accuracy of the whole system can be improved only by solving the drift problem.

Disclosure of Invention

The problem that this application will be solved is exactly to eliminate flexible film pressure sensor's drift, improves the degree of accuracy that pressure distribution detected.

In order to solve the above problems, the specific technical solution of the present invention includes:

the first scheme is as follows: the invention discloses a pressure distribution detection device, which comprises: the flexible film pressure distribution testing system comprises a flexible film pressure distribution testing system, a weighing system and an upper computer provided with pressure distribution detection software;

the flexible film pressure distribution testing system comprises a flexible film pressure sensing sheet and a first transmission module, wherein the flexible film pressure sensing sheet is used for acquiring pressure or pressure distribution data of each unit area of an object to be tested, and the first transmission module is used for uploading the pressure or pressure distribution data to an upper computer;

the weighing system comprises a weighing sensor for acquiring the integral stress G of the flexible film pressure sensing sheet and a second transmission module for uploading the integral stress G to an upper computer;

when the pressure distribution detection software is operated by an upper computer, calculating the pressure sum Fs of each unit area of the object to be detected according to the pressure or pressure distribution data, calculating a dynamic calibration coefficient related to the pressure sum Fs and the whole stress G, and correcting the pressure or pressure data of each unit area through the dynamic calibration coefficient.

Preferably, the pressure distribution detecting device further comprises a pressure transmission system for transmitting the whole stress G of the flexible film pressure sensing piece to the weighing sensor.

Preferably, the pressure transmission system comprises a bearing plate, the object to be measured and the flexible film pressure sensing sheet are arranged above the bearing plate, and the weighing sensor is arranged below the bearing plate.

Preferably, the weighing sensor is provided with a bearing surface for bearing the flexible film pressure sensing sheet and the object to be measured.

Preferably, the weighing sensor is a load cell sensor.

Preferably, the first transmission module is a pressure distribution collector and is used for converting analog signals output by the flexible film pressure sensing sheet into digital information and then uploading the digital information to an upper computer; the second transmission module is a pressure transmitter and is used for converting the analog signals output by the weighing sensor into digital information and then transmitting the digital information to an upper computer.

Scheme II: the invention also discloses a method for eliminating the time drift of the flexible film pressure distribution detection system on line, which comprises the following steps:

acquiring pressure or pressure distribution data of each unit area of an object to be detected, and calculating the sum Fs of the pressures of each unit area of the object to be detected according to the pressure or pressure distribution data;

acquiring the integral stress G of the flexible film pressure sensing sheet;

calculating a dynamic calibration coefficient relating to said sum of pressures Fs and said overall force G;

and correcting the pressure or pressure data of each unit area through the dynamic calibration coefficient.

Preferably, the pressure or pressure distribution data of each unit area of the object to be detected can be acquired through the flexible film pressure sensing sheet; the whole stress G of the flexible film pressure sensing piece can be obtained through the weighing sensor.

Preferably, the method further comprises the step of enabling the weighing data measured by the weighing sensor to be equal to the whole stress G of the flexible film pressure sensing piece in a zero-resetting mode in the initial state.

Preferably, the linear correction of the pressure or pressure data per unit area in the pressure distribution data by the dynamic calibration coefficient specifically includes:

the pressure or pressure value per unit area is multiplied by a dynamic calibration factor, k, G/Fs, respectively.

Preferably, the dynamic calibration coefficient may be used to perform weighted correction on the pressure or pressure data of each unit area, specifically including:

calculating a K value according to the formula (1) and the formula (2), and calculating a weighting correction coefficient K (x, y) corresponding to each unit area based on the formula (1);

K(x,y)＝K×{A×Lg[P(x,y)]+B} (1)

Fs＝G＝Sum[G(x,y)×K(x,y)] (2)

wherein, K represents the overall correction coefficient, K (x, y) represents the correction coefficient of the grid point of the coordinate point (x, y), G (x, y) represents the original stress of the coordinate point (x, y) before the film pressure sensing sheet is corrected, P (x, y) represents the original pressure value of the coordinate point (x, y) before the film pressure sensing sheet is corrected, A represents the slope of the correction curve, B represents the intercept of the correction curve, and the values of A and B can be determined by calculating the slope and the intercept of the linear function trend line of the actual pressure curve of the flexible film pressure sensing sheet;

the dynamic calibration coefficient is a weighted correction coefficient K (x, y) of each point, and the pressure or pressure value of each unit area is multiplied by the weighted correction coefficient K (x, y) corresponding to each unit area.

According to the invention, the load cell sensor with high precision and no drift influence is introduced, so that the total pressure born by the load cell sensor and the total pressure born by the flexible film pressure sensing sheet are equal, the pressure distribution data output by the flexible film pressure sensing sheet are calibrated in real time based on the accurate pressure data output by the load cell sensor, the time drift influence is eliminated, and the accurate pressure distribution data are output.

Drawings

Fig. 1 is a schematic structural diagram of a pressure distribution detection apparatus.

The attached drawings are marked as follows: the device comprises a flexible film pressure sensing sheet 1, a load cell sensor 2, a load bearing plate 3, a pressure distribution collector 4, a pressure transmitter 5 and an upper computer 6.

Detailed Description

The invention is further explained below with reference to the figures and the specific embodiments.

Embodiment 1 discloses a method for eliminating time drift of a flexible film pressure distribution detection system on line, which mainly comprises the following steps:

and acquiring pressure distribution data of the object to be detected through the flexible film pressure sensing sheet. The flexible film pressure sensing sheet is a flexible film pressure distribution sensor, and can acquire pressure distribution data of an object to be measured in contact with the flexible film pressure sensing sheet, wherein the pressure distribution data can be pressure or pressure value of each unit area of the object to be measured. The object to be measured generally includes various mobile phone glass panels, display liquid crystal glass panels, lithium batteries, new energy batteries, printing screens/steel meshes, and the like. In practical application, the system can be used as long as two pressure contact surfaces are tested, whether the surface-to-surface contact is flat, whether the pressure is applied and the stress is uniform, and whether the plane is flat.

And acquiring the integral stress G of the flexible film pressure sensing sheet through the weighing sensor. The overall stress G of the flexible film pressure sensing sheet may be the actual weight of the object to be measured, or may be the sum of the actual weight of the object to be measured and the force applied to the object to be measured. However, in practical use, the weighing data of the load cell, i.e. the actual force applied to the load cell, may further include the weight of the flexible film pressure sensing sheet itself, the weight of other auxiliary modules, e.g. a bearing plate for bearing the object to be measured, etc. In order to simplify the data structure, the zero-resetting method is usually adopted, so that the weighing data of the weighing sensor is the actual weight of the object to be measured, or the sum of the actual weight of the object to be measured and the force applied to the object to be measured, that is, the overall stress G of the flexible film pressure sensing sheet does not contain the weight of the flexible film pressure sensing sheet and other weights.

And calculating the pressure sum F of each unit area according to the pressure distribution data acquired by the flexible film pressure sensing sheet, and then calculating a dynamic calibration coefficient related to the pressure sum F and the whole stress G.

And finally, correcting the pressure data of each unit area in the pressure distribution data through the dynamic calibration coefficient.

The dynamic calibration coefficient may be calculated using the simplest linear relationship, and may be a value that changes in real time, for example, a ratio k (k ═ G/F) between a sum F of pressures and the total applied force G may be used as the dynamic calibration coefficient, and the dynamic calibration coefficient may be multiplied by pressure data per unit area at the time of calibration.

Based on the characteristics of the flexible film pressure sensing sheet, in order to correct the pressure distribution data more accurately, the dynamic calibration coefficient can also be calculated and obtained by adopting a mode of dynamically correcting the pressure value based on each pressure point. With the dynamically modified calibration method, a different calibration factor will be used for each point on the flexible membrane pressure sensing patch. The calibration coefficients for each point will be calculated using a set of linear corrections based on the original pressure value for that point. K represents an overall correction coefficient, K (x, y) represents a correction coefficient of a grid point of a coordinate point (x, y), G (x, y) represents the original stress of the coordinate point (x, y) before the film pressure sensing piece is corrected, P (x, y) represents the original pressure value of the coordinate point (x, y) before the film pressure sensing piece is corrected, A represents the slope of a correction curve, B represents the intercept of the correction curve, and A and B can be determined according to the slope and the intercept of a linear function of an actual flexible film pressure sensing piece test curve.

K(x,y)＝K×{A×Lg[P(x,y)]+B} (1)

Fs＝G＝Sum[G(x,y)×K(x,y)] (2)

Based on the above formula (1) and formula (2), K value can be calculated, and based on the formula (1), K (x, y) of each point can be obtained. Therefore, the weighted correction of each point on the whole film pressure sensing sheet based on the pressure value can be completed.

For example, assume that a 2mm grid array film sensor of 2 × 2 currently reads pressure values of:

P_(1,1)＝10KPa,P_(1,2)＝100KPa,P_(2,1)＝1000KPa,P_(2,2)＝10000KPa。

in the formula (1), A takes the value of 0.4, B takes the value of 0.2, and the calculation results are that:

K_(1,1)＝K×(0.4×Lg10+0.2)＝0.6K，

K_(1,2)＝K×(0.4×Lg100+0.2)＝1K，

K_(2,1)＝K×(0.4×Lg1000+0.2)＝1.4K，

K_(1,2)＝K×(0.4×Lg10000+0.2)＝1.8K，

the corrected statistical weight F (X, y) of the grid point (X, y) is P (X, y) × S × K (X, y), where S is the area of the grid point, and in this example, 2mm X2mm is 0.04cm²And calculating to obtain: f_(1,1)＝100g/cm2X0.04cm2X0.6K＝2.6Kg

F_(1,2)＝1000g/cm2X0.04cm2X1K＝40Kg

F_(2,1)＝10000g/cm2X0.04cm2X1.4K＝560Kg

F_(2,2)＝100000g/cm2X0.04cm2X1.8K＝7200Kg

Further calculating the integral stress Fs-7802.6 Kg

Suppose that the reading value of the current weighing sensor is G5000G

In accordance with Fs — G, the overall correction factor K may be calculated to be 5000/7802.6 to about 0.64

At this time, the corrected P (x, y) can be recalculated according to the determined K value

P_{Repair (1,1)}＝P_(1,1)×K_(1,1)＝10KPa×0.6×0.64＝3.84KPa

P_{Repair (1,2)}＝P_(1,2)×K_(1,2)＝100KPa×1×0.64＝64KPa

P_{Repair (2,1)}＝P_(2,1)×K_(2,1)＝1000KPa×1.4×0.64＝896KPa

P_{Repair (2,2)}＝P_(2,2)×K_(2,2)＝10000KPa×1.8×0.64＝11520KPa

The whole weighted correction calculation is completed. According to the correction method, the corrected weight statistic value of 4 points is 5000g, but the correction coefficients of 4 grid points are subjected to weighting correction processing due to different pressure values of each point, so that the tested data are more accurate.

The weighing system comprises a weighing sensor, a weighing system and a weighing system, wherein the weighing sensor is used for acquiring the integral stress G of the flexible film pressure sensing sheet, the weighing sensor is used for directly acquiring the integral stress G of the flexible film pressure sensing sheet, and other force transmission mechanisms are not needed.

In other embodiments, the whole stress G of the flexible film pressure sensing sheet can be transmitted to the weighing sensor by the pressure transmission system, which is generally applicable to a weighing system with a small volume of the weighing sensor, especially a small contact surface of the weighing table, which cannot completely lay the flexible film pressure sensing sheet or can not well bear the object to be measured. A simpler mode that pressure transmission system realized adopts a bearing plate promptly, and flexible film pressure sensing piece and the object that awaits measuring are arranged in the bearing plate top, and weighing sensor arranges in the bearing plate below. When the flexible film pressure sensing piece is used, the flexible film pressure sensing piece can be laid on the upper surface of the bearing plate, an object to be measured is placed on the flexible film pressure sensing piece, and then the bearing plate and a bearing object of the bearing plate are placed on the weighing sensor as a whole. Of course, the pressure transmission system may have other implementation manners, and is not limited thereto, as long as the whole stress G of the flexible film pressure sensing piece can be transmitted to the weighing sensor.

Referring to fig. 1, embodiment 2 discloses a pressure distribution detection device, which mainly includes four parts, namely, a flexible film pressure distribution test system, a load cell weighing system, a pressure transmission system, and an upper computer equipped with software including an automatic calibration pressure distribution detection system.

The flexible film pressure distribution testing system mainly comprises a flexible film pressure sensing sheet and a pressure distribution collector which are electrically connected. The system tests pressure distribution data through the flexible film pressure sensing sheet and then transmits the data to an upper computer through the pressure distribution collector. Analog signals sampled by the sensor are generally transmitted between the flexible film pressure sensing sheet and the pressure distribution collector, and digital signals transmitted by a USB can be set between the pressure distribution collector and an upper computer. Specifically, the pressure signal generated by the flexible film pressure sensing sheet due to stress change is converted into an analog electrical signal and output to the pressure distribution collector, and the analog electrical signal is subjected to analog amplification, ADC (analog to digital converter) sampling and finally output to a digital signal through the pressure distribution collector and is subjected to data processing on an upper computer connected with the pressure distribution collector through a USB (universal serial bus) interface.

The load cell weighing system mainly comprises a load cell sensor and a pressure transmitter which are electrically connected. The weighing data acquired by the load cell sensor can be sent to an upper computer through an RS485 or RS232 interface of the pressure transmitter. Finished parts on the market can be directly purchased by the load cell sensor and the pressure transmitter according to requirements, and the requirements of the structure appearance size, the precision and the upper computer communication interface in practical application are generally met. For example, in actual use, there is no specific requirement for the external dimensions of the load cell sensor, and mainly in combination with the actual application scenario, the thickness of the load cell sensor is ensured to be small, and the load cell sensor can be placed in a device in which the load cell sensor is installed; the precision can meet 1%. The communication interface of the pressure transmitter and the upper computer can be RS485 or RS232, and the pressure transmitter and the upper computer are mainly used for receiving the analog electric signals which are output by the load cell sensor and change along with the pressure, and then converting the analog electric signals into digital signals and uploading the digital signals to the upper computer.

The pressure transmission system is a bearing plate in this embodiment, and when the detection area of the flexible pressure sensing sheet is large and the bearing area of the load cell weighing system is small, all the pressure borne by the flexible film pressure sensing sheet can be transmitted to the load cell sensor by the pressure transmission system. As a simplest implementation manner, the bearing plate may be a metal plate such as a steel plate, a stainless steel plate, or an aluminum plate, or may be a non-metal plate that is not easily deformed, for example, a plastic ABS or PC plate. Of course, the bearing plate is only a simplest implementation manner of the pressure transmission system, and in practice, the bearing plate is not limited to this scheme as long as the bearing plate can transmit all the pressure borne by the flexible film pressure sensing sheet to the load cell sensor. When the pressure sensor is used, the flexible film pressure sensing piece is flatly laid on the bearing plate, and all pressure borne by the sensing piece is transmitted to the load cell sensor through the bearing plate. In practical use, the weighing weight of the load cell sensor generally includes the total weight borne by the flexible film pressure sensing sheet, the self weight of the flexible film pressure sensing sheet, the weight of the bearing plate and the like, and considering that the weights of the flexible film pressure sensing sheet and the bearing plate are fixed values, the influence of the weights can be eliminated in a zero-resetting mode, so that the total weight borne by the flexible film pressure sensing sheet is equal to the total weight weighed by the load cell sensor, and the calculation is simplified.

Of course, the pressure transmission system may not be used in other application scenarios, for example, the load cell system itself may have a large and flat weighing platform, or the object to be measured may be small enough that the existing weighing platform is placed sufficiently.

The upper computer is provided with pressure distribution detection system software containing automatic calibration, and the system software receives pressure distribution data uploaded by the flexible film pressure distribution test system, for example, the pressure values P of 4096 points in 64 rows X64 columns are obtained in total. The pressure values of 4096 points are multiplied by the areas S corresponding to the respective points to obtain pressure values F (F — P × S) for each point, and finally, a total Fs (Fs — 4096 × F) of 4096 points is calculated. Meanwhile, the system software also receives weight data G uploaded by the load cell weighing system. Based on the special structural design of the pressure transmission system, the total weight G sensed by the load cell sensor is equal to 4096 points of the pressure sum Fs at the time of initial measurement (no drift generated).

In the testing process, the film pressure distribution test has certain drift change of the output pressure value due to the characteristics of the flexible film material used by the flexible film pressure sensing sheet in the flexible film pressure distribution testing system; but the load cell sensor has no drift problem at all. Therefore, system software can calculate and generate a calibration coefficient k by combining weighing data (namely G) of the load cell sensor and the pressure sum (namely Fs) sensed by the flexible film pressure sensing sheet in real time, and data correction is carried out on pressure distribution data of the flexible film pressure sensing sheet based on the calibration coefficient k, so that drift is eliminated, and accurate pressure distribution data detection is realized.

The calibration coefficient K can be calculated by using the simplest linear relationship, that is, K ═ G/Fs, and after the calibration coefficient K is obtained, the pressure values of 4096 points are respectively multiplied by the calibration coefficient K for correction. The corrected data can reflect the pressure distribution data detected in real time more accurately. Of course, besides the linear calculation method, the calibration coefficient can be further accurately corrected by combining different pressure sections of the flexible film pressure distribution testing system in actual use.

Finally, it should be noted that while the above describes exemplifying embodiments of the invention with reference to the accompanying drawings, the invention is not limited to the embodiments and applications described above, which are intended to be illustrative and instructive only, and not limiting. Those skilled in the art, having the benefit of this disclosure, may effect numerous modifications thereto without departing from the scope of the invention as defined by the appended claims.