CN112857639B - Servo incremental high-precision pressure sensor and using method thereof - Google Patents

Abstract

The invention discloses a servo incremental high-precision pressure sensor and a using method thereof, and belongs to the technical field of pressure sensors. The servo incremental high-precision pressure sensor comprises a loading table, pressure sensors, an air bag, a micro-displacement driver, a micro-displacement sensor and a base, wherein the lower side of the air bag is installed on the upper surface of the base, the upper side of the air bag supports the loading table, the micro-displacement driver and the micro-displacement sensor are circumferentially arranged on the upper surface of the base by taking the air bag as a center, the pressure sensors are in one-to-one correspondence with the micro-displacement driver, each pressure sensor is supported by the corresponding micro-displacement driver, and the upper side of each pressure sensor supports the loading table. The invention improves the overall measurement precision and realizes the high-precision measurement of the load increment.

Description

Servo incremental high-precision pressure sensor and method of using the same

technical field

The invention relates to a servo incremental high-precision pressure sensor and a using method thereof, belonging to the technical field of pressure sensors.

Background technique

Pressure sensors are widely used in all walks of life, and their accuracy is closely related to the range, usually expressed as a coefficient of the full range, and a high-precision sensor can reach about 2/10,000 of the full range. Therefore, when the range increases, the accuracy also deteriorates, and how to achieve high accuracy under large load conditions becomes the bottleneck of the pressure sensor. On the other hand, in many applications such as centroid test benches and satellite simulators, the size of the initial load is often not concerned, but the load change relative to the initial load, that is, the pressure increment.

SUMMARY OF THE INVENTION

The purpose of the present invention is to propose a servo incremental high-precision pressure sensor and a method for using the same, so as to solve the problems existing in the prior art.

A servo incremental high-precision pressure sensor, the servo incremental high-precision pressure sensor includes a loading table, a pressure sensor, an air bag, a micro-displacement driver, a micro-displacement sensor and a base, and the lower side of the air bag is installed on the On the upper surface of the base, the upper side of the air bag supports the loading table, the micro-displacement driver and the micro-displacement sensor are circumferentially arranged on the upper surface of the base with the air bag as the center, the The pressure sensors are in one-to-one correspondence with the micro-displacement drivers, and each pressure sensor is supported by the corresponding micro-displacement driver, and the loading table is supported on the upper side of the pressure sensors.

Further, the loading table and the base are coaxial circular tables.

Further, the airbag is arranged on the axis of the loading platform and the base.

Further, the airbag is an airbag with an adjustable inflation volume.

Further, the micro-displacement driver and the pressure sensor are coaxial.

Further, N micro-displacement drivers and micro-displacement sensors are evenly arranged along the circumferential direction of the airbag, and N≥3.

Further, the micro-displacement driver and the micro-displacement sensor are arranged staggered in the same circle.

Further, the micro-displacement driver and the micro-displacement sensor are arranged in different circles in the same direction.

Further, the base is provided with a universal fixing interface.

A method of using a servo incremental high-precision pressure sensor, based on the above-mentioned servo incremental high-precision pressure sensor, the using method includes the following contents:

First, adjust the pressure of the airbag according to the working point load F ₀ so that the indication of the pressure sensor is in the middle of the range, and record the indication P _i0 of the micro-displacement sensor and the indication F _i0 of the pressure sensor, the subscript i represents the pressure sensor or The number of the micro-displacement sensor, i=1,2,...,N, N represents the total number of pressure sensors or micro-displacement sensors; the subscript 0 represents the initial value, and then a load is applied on the loading table, and the display of the micro-displacement sensor is at this time. number is P _i , if

and/or

Among them, ò and σ represent the preset displacement accuracy parameters and displacement distribution parameters, respectively, μ _ΔP and σ _ΔP represent the mean and variance of the displacement changes of all micro-displacement sensors when the load increases, respectively,

Adjust the micro-displacement driver (4) to reduce μ _ΔP and σ _ΔP until μ _ΔP <ò and σ _ΔP <σ, read the pressure sensor reading F _i at this time, then the load table (1) is relative to the working point The added load for load F ₀ is:

When the relative measurement accuracy of the pressure sensor is r ₀ , the range is G, and the stiffness of the airbag at the working point is k, the relative measurement accuracy of the above-mentioned newly added load is:

Among them, the working point stiffness k represents the displacement change caused by the slight change of the load at the operating point, and the ratio of the load change to the displacement change; a represents the designed relative operating point, that is, the operating point load and the total range of the pressure sensor Ratio,

By designing smaller k and ò such that kò<<NG, and choosing larger a such that a>>1, we get

That is, higher measurement accuracy is achieved.

The present invention has the following advantages: the present invention adopts the airbag as the main support, realizes the unloading of the load at the working point, and uses the position of the working point as the equilibrium position, and monitors the displacement change after the incremental load is applied by the micro-displacement sensor, and This variation is reduced to a certain range through the micro-displacement driver, and the incremental driving force applied to reduce the incremental displacement to a certain range is measured by a small-range high-precision pressure sensor connected in series with the micro-displacement driver. The resultant force gives the incremental load applied to the loading table. Since the air bag is used as the main support to unload the working point load, the pressure sensor only needs to measure the incremental load. When the incremental load is small relative to the working point load, a pressure sensor with a small range can be selected, thereby improving the accuracy of the incremental load. measurement accuracy. The error brought by the main support is determined by the stiffness of the main support, the measurement accuracy of the micro-displacement sensor and the drive resolution of the micro-displacement driver. By choosing a high-precision micro-displacement sensor and a high-resolution micro-displacement driver, the error can be very small. be ignored. Thus, high-precision measurement of incremental loads under large loads is achieved.

Description of drawings

1 is a front view of a servo incremental high-precision pressure sensor of the present invention;

Fig. 2 is the side view of Fig. 1;

3 is a schematic perspective view of a servo incremental high-precision pressure sensor of the present invention;

FIG. 4 is a flow chart of a method for using a servo incremental high-precision pressure sensor according to the present invention.

Among them, 1 is a loading table, 2 is a pressure sensor, 3 is an air bag, 4 is a micro-displacement driver, 5 is a micro-displacement sensor, and 6 is a base.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Referring to Fig. 1-Fig. 3, the present invention designs a servo incremental high-precision pressure sensor in order to solve the demand for high-precision measurement of incremental loads under large loads in applications such as centroid test benches and satellite simulators. The central airbag 3 balances the initial load at the working point, measures the displacement change caused by the incremental load through the high-precision micro-displacement sensor 5, and restores the loading table 1 to the working point position through the high-resolution micro-displacement driver 4. The small-range high-precision pressure sensor 2 connected in series with the micro-displacement driver 4 measures the indication increment that needs to be applied when returning to the working point, and the sum of the indication increments of all the pressure sensors 2 gives the load relative to the working point load Increment. Since the large initial load at the working point is balanced by the air bag 3, the range of the pressure sensor 2 only needs to meet the measurement requirements of the full incremental load. The pressure sensor 2 with a smaller range can be selected. When the incremental load is small relative to the initial load , the pressure sensor 2 with a smaller range can be selected, thereby significantly improving the measurement accuracy.

The servo incremental high-precision pressure sensor of the present invention includes: a loading table 1 , a pressure sensor 2 , an air bag 3 , a micro-displacement driver 4 , a micro-displacement sensor 5 , and a base 6 .

The loading table 1 is supported on the upper side of the pressure sensor 2 and the air bag 3, and is used to apply the load. A standard interface or a special interface can be designed according to the applied load. The center of the loading load should be close to the geometric center of the loading table 1. The geometric size of the loading table 1 To consider the geometric size of the airbag 3 and the distribution and size of the pressure sensor 2, the micro-displacement driver 4, and the micro-displacement sensor 5, usually the projection can envelop the airbag 3, the pressure sensor 2, the micro-displacement driver 4 and the micro-displacement sensor 5 as It can also be designed according to the constraints of the installation space;

The lower side of the pressure sensor 2 is installed on the micro-displacement driver 4, the upper side supports the loading table 1, and N pieces are arranged along the circumferential direction of the airbag 3, N=3, 4, ..., for measuring the load to be measured, N usually takes 3 or 4. It is advisable to have a uniform layout in the circumferential direction. The range of the pressure sensor 2 needs to be determined according to the size of the incremental load to be measured, the loading position and N. The maximum incremental load to be measured is ΔF _max as an example. At the same time, the load When applying, it is applied through a spherical hinge, that is, the load is not allowed to appear eccentric, and the range of the pressure sensor 2 should meet the

The lower side of the airbag 3 is installed on the base 6, and the upper side supports the loading table 1, which is coaxial with the base 6 and the loading table 1, and is used to carry the load of the working point on the loading table 1, and an external inflator can be connected to the airbag 3. Inflate to adjust the stiffness of the airbag 3. The bearing capacity of the airbag 3 needs to be selected according to the size of the loaded load, and the air supply pressure needs to be determined according to the load size of the working point and the required stiffness. Take the working point load F ₀ as an example, The bearing capacity of the air bag 3 should satisfy F _max ≥F ₀ +ΔF _max . Assuming that the displacement resolution of the micro-displacement driver 4 is δP _a , the allowable maximum value of the error caused by the incomplete reset of the air bag 3 is δF _s , then the air bag 3 is in The stiffness of the working point should satisfy

If the micro-displacement actuator 4 adopts a piezoelectric ceramic actuator, its displacement resolution can usually reach nanometer level. Taking δF _s =0.001N as an example, the stiffness of the airbag 3 at the working point only needs to satisfy

Such rigidity requirements can be easily met without special design.

The lower side of the micro-displacement driver 4 is installed on the base 6, the upper side supports the pressure sensor 2, and is coaxial with the pressure sensor 2, and N is arranged along the circumferential direction of the airbag 3, N=3, 4, . . . for driving The loading table 1 restores the working point position, where N is the same as the number N of the pressure sensors 2, and its stroke and driving capacity should be sufficient to restore the deformation of the airbag 3 to the working point position after applying incremental loads. The measurement accuracy of the incremental load is designed. When the working point load is applied, the micro-displacement actuator 4 should be in the middle of the stroke, and when the maximum incremental load is increased and decreased, it is located at the two extreme positions of the stroke. It has a unidirectional relationship with displacement, and can be comprehensively designed from the load and stroke, that is, when the load increment is guaranteed to be the smallest (the negative value is the largest), the load and displacement output of the micro-displacement driver 4 are not zero, and the load is the largest (positive value). Maximum), the bearing capacity of the micro-displacement driver 4 does not exceed its maximum bearing capacity, therefore, the maximum bearing capacity of the micro-displacement driver 4 should meet the

Taking N=4 and ΔF _max =100N as an example, L _max ≥50N. If the micro-displacement driver 4 adopts a piezoelectric ceramic actuator, its driving capacity can usually reach several hundreds of Newtons to several thousand Newtons. Therefore, such driving capacity requirements are extremely easy to achieve.

The micro-displacement sensor 5 is installed on the base 6 on the lower side, and N is arranged along the circumferential direction of the airbag 3, N=3, 4, . In the same way, the layout can be staggered with the micro-displacement driver 4 and the pressure sensor 2 or in the same direction but on different distribution circles. If the deformation increment exceeds its range and causes damage, the displacement resolution δP _s needs to be designed according to the measurement accuracy of the incremental load, which should be smaller than the displacement resolution δP _a of the micro-displacement driver 4, that is, δP _s <δP _a , if a capacitor is used The sensor is used as a micro-displacement sensor 5, and the displacement resolution can usually reach sub-nanometer level;

The airbag 3 is installed on the base 6, the micro-displacement sensor 5 and the micro-displacement driver 4 are arranged along the circumference of the airbag 3, and the bottom can be processed with a general fixed interface or designed a special connection interface as required.

As shown in Figure 4, in use, it is divided into two stages: debugging, calibration and application.

First of all, when installing, it is necessary to ensure that when the indication of the pressure sensor 2 is in the middle of the range, the micro-displacement driver 4 is also basically in the middle of the stroke. Adjust the pressure of the airbag 3 according to the operating point load F ₀ , so that the reading of the pressure sensor 2 is in the middle of the range, and record the reading P _i0 of the micro-displacement sensor 5 and the reading F _i0 of the pressure sensor 2 , and the subscript i represents the pressure sensor 2 Or the number of the micro-displacement sensor 5, i=1,2,...,N, N represents the total number of pressure sensors 2 or micro-displacement sensors 5; the subscript 0 represents the initial value;

Then, apply a load on the loading table 1, at this time the micro-displacement sensor 5 shows the number P _i , if the average value of the displacement increment of the loading table 1

And/or the variance of the displacement increments of the plurality of micro-displacement sensors 5

Among them, ò and σ represent the preset displacement accuracy parameters and displacement distribution parameters, respectively, and _{μΔP and σ ΔP represent} the mean and variance of the displacement changes of all the micro-displacement sensors 5 when the load increases, respectively.

The micro-displacement drive 4 is adjusted to decrease _{μΔP and σΔP until μΔP <ò and σ ΔP < σ .} Reading the number F _i of the pressure sensor 2 at this time, the increased load on the loading table 1 relative to the working point load F ₀ is:

The measurement error of the incremental load includes two parts: the measurement error of the multiple pressure sensors 2 and the error caused by the incomplete reset of the airbag 3 . As a conservative estimate, the errors of the two parts are directly superimposed (when the error propagation formula is used for calculation, the comprehensive error is smaller than the result of direct superposition); while the measurement errors of multiple pressure sensors 2 are calculated using the error propagation principle. When the relative measurement accuracy of the pressure sensor 2 is r ₀ , the range is G, and the stiffness of the airbag 3 at the working point is k, the relative measurement accuracy of the above-mentioned newly added load is

Among them, the working point stiffness k represents the displacement change caused by the slight change of the load at the operating point, and the ratio of the load change to the displacement change; a represents the designed relative operating point, that is, the total amount of the operating point load and the pressure sensor 2 Cheng ratio

By designing a smaller k and ò such that kò<<NG, and a larger a such that a>>1, we can get

That is, higher measurement accuracy is achieved. According to the aforementioned parameters, it is further assumed here that G=L _max =100N, F ₀ =2000N, a=5, r≈0.1r ₀ can be obtained, that is, the accuracy is improved by 10 times.

The invention proposes a servo incremental high-precision sensor for the measurement requirements of high-precision load increments under large initial bearing conditions. The sensor uses the airbag as the main load, and the position of the initial load as the equilibrium position. After the load changes, the micro-displacement sensor 5 is used to monitor and the micro-displacement driver 4 is used to drive, so that the loading table 1 returns to the equilibrium position, and the small range of high precision The pressure sensor 2 is connected in series with the micro-displacement driver 4 and is connected in parallel with the main load of the airbag 3. Therefore, the sum of their indication changes gives the load increment of the loading table. Due to the initial load offset by the main load of the airbag 3, the pressure sensor 2 can choose a sensor with a small range, which improves the overall measurement accuracy and realizes the high-precision measurement of the load increment.

The above implementation examples are only used to help understand the method of the present invention and its core idea. For those skilled in the art, according to the idea of the present invention, several improvements and modifications can also be made in the specific implementation and application scope. These improvements and retouching should also be regarded as the protection scope of the present invention.

Claims (9)

1. A method of using a servo incremental high-precision pressure sensor, based on a servo incremental high-precision pressure sensor comprising a loading table (1), a pressure sensor (2) , airbag (3), micro-displacement driver (4), micro-displacement sensor (5) and base (6), the lower side of the airbag (3) is mounted on the upper surface of the base (6), so The upper side of the airbag (3) supports the loading table (1), and the micro-displacement driver (4) and the micro-displacement sensor (5) are circumferentially arranged on the base (4) with the airbag (3) as the center. 6) on the upper surface of the pressure sensor (2) and the micro-displacement driver (4) in one-to-one correspondence, and each pressure sensor (2) is supported by the corresponding micro-displacement driver (4), so The upper side of the pressure sensor (2) supports the loading table (1), characterized in that, The usage method includes the following: First, adjust the pressure of the airbag (3) according to the working point load F ₀ so that the indication of the pressure sensor (2) is in the middle of the range, and record the indication P _i0 of the micro-displacement sensor (5) and the pressure sensor (2) Indication F _i0 , the subscript i represents the number of the pressure sensor or micro-displacement sensor, i=1,2,...,N, N represents the total number of pressure sensors or micro-displacement sensors; the subscript 0 represents the initial value, Then, apply a load on the loading table (1), at this time the indication of the micro-displacement sensor (5) is P _i , if

and/or

Among them, ∈ and σ represent the preset displacement accuracy parameters and displacement distribution parameters, respectively, μ _ΔP and σ _ΔP represent the mean and variance of the displacement changes of all micro-displacement sensors when the load increases, respectively, Adjust the micro-displacement driver (4) to reduce μ _ΔP and σ _ΔP until μ _ΔP <∈ and σ _ΔP <σ, read the pressure sensor (2) reading F _i at this time, then the relative load on the loading table (1) The added load at the operating point load F ₀ is:

When the relative measurement accuracy of the pressure sensor (2) is r ₀ , the range is G, and the stiffness of the airbag (3) at the working point is k, the relative measurement accuracy of the above-mentioned newly added load is:

Among them, the working point stiffness k represents the displacement change caused by the slight change of the load at the operating point, and the ratio of the load change to the displacement change; a represents the designed relative operating point, that is, the operating point load and the total range of the pressure sensor Ratio,

By designing smaller k and ∈ such that k∈<<NG, and choosing larger a such that a＞＞1, we get

That is, higher measurement accuracy is achieved. 2 . The method for using a servo incremental high-precision pressure sensor according to claim 1 , wherein the loading table ( 1 ) and the base ( 6 ) are coaxial circular tables. 3 . 3. A method of using a servo incremental high-precision pressure sensor according to claim 2, wherein the airbag (3) is arranged on the axis of the loading table (1) and the base (6) heart. 4 . The method of using a servo incremental high-precision pressure sensor according to claim 3 , wherein the air bag ( 3 ) is an air bag whose inflation volume can be adjusted. 5 . 5 . The method for using a servo incremental high-precision pressure sensor according to claim 4 , wherein the micro-displacement driver ( 4 ) and the pressure sensor ( 2 ) are coaxial. 6 . 6. A method of using a servo incremental high-precision pressure sensor according to claim 5, wherein the micro-displacement driver (4) and the micro-displacement sensor (5) are both along the airbag (3) There are N evenly arranged in the circumferential direction, and N≥3. 7 . The method for using a servo incremental high-precision pressure sensor according to claim 6 , wherein the micro-displacement driver ( 4 ) and the micro-displacement sensor ( 5 ) are staggered in the same circle. 8 . 8 . The method of using a servo incremental high-precision pressure sensor according to claim 6 , wherein the micro-displacement driver ( 4 ) and the micro-displacement sensor ( 5 ) are arranged in the same direction and different circles. 9 . 9 . The method of using a servo incremental high-precision pressure sensor according to claim 3 , wherein the base ( 6 ) is provided with a universal fixed interface. 10 .

Images