Inclination angle adjusting platform

Abstract

The utility model provides an inclination angle adjusting platform which is used for calibrating a differential pressure transmitter and comprises a base, an off-axis inclination assembly and a first double-axis inclination angle sensor. The base is provided with a mounting face, and the off-axis inclination assembly comprises two angular displacement tables and a mounting platform. The two angular displacement tables are stacked on the mounting surface, two rotating planes of the two angular displacement tables are perpendicular to each other, the two rotating planes are perpendicular to the mounting surface, and the mounting platform is mounted on the angular displacement table located on the upper portion. The first dual-axis tilt angle sensor is mounted on the mounting platform and is suitable for providing a measurement angle and representing an actual angle between the mounting platform and an ideal plane by the measurement angle. Wherein the two angular displacement tables respond to an actual angle and drive the mounting platform to deflect, so that the mounting platform is always parallel to an ideal plane under the condition that the differential pressure transmitter is calibrated.

Description

Technical Field

[0001] At least one embodiment of the utility model relates to the technical field of differential pressure transmitter calibration, and in particular to an inclination angle adjustment platform for calibrating a differential pressure transmitter. Background Art

[0002] The differential pressure transmitter is a very important component of professional pressure instruments and is the most commonly used transmitter in industrial practice. It is widely used in water conservancy and hydropower, railway transportation, intelligent buildings, production automation, aerospace and other industries. The accuracy of the traceability of the differential pressure transmitter is very important.

[0003] The differential pressure transmitter is a sensor based on gravity. Under normal use, the installation posture of the differential pressure transmitter must be kept horizontal, otherwise it will cause the differential pressure transmitter to be biased and the measurement results will be biased. Before leaving the factory, the differential pressure transmitter needs to be verified and calibrated on a horizontal plane to ensure the accuracy of the differential pressure transmitter measurement.

[0004] The differential pressure transmitter has strict requirements on the underlying surface during the verification and calibration process. The smaller the rated differential pressure value of the differential pressure transmitter, the stricter the requirement. Taking the (0~1)kPa accuracy level of 0.05 micro differential pressure transmitter as an example, a deviation of 0.2° of the underlying surface will cause the differential pressure transmitter verification result to fail. Utility Model Content

[0005] In order to solve at least one of the technical problems in the prior art, an embodiment of the utility model provides an inclination angle adjustment platform, which can provide a bottom surface parallel to an ideal plane for calibration of a differential pressure transmitter.

[0006] One aspect of an embodiment of the utility model provides a tilt angle adjustment platform, characterized in that it is used to calibrate a differential pressure transmitter, and the tilt angle adjustment platform includes a base, an off-axis tilt assembly and a first dual-axis tilt sensor. The base has a mounting surface, and the off-axis tilt assembly includes two angular displacement tables and a mounting platform. The two angular displacement tables are stacked on the mounting surface, and the two rotation planes of the two angular displacement tables are perpendicular, and the two rotation planes are perpendicular to the mounting surface, and the mounting platform is mounted on the angular displacement table located at the upper part. The first dual-axis tilt sensor is mounted on the mounting platform, and is suitable for providing a measurement angle, and characterizing the actual angle between the mounting platform and the ideal plane with the measurement angle. The two angular displacement tables drive the mounting platform to deflect in response to the actual angle, so as to keep the mounting platform always parallel to the ideal plane when calibrating the differential pressure transmitter.

[0007] According to an embodiment of the present invention, the two angular displacement platforms respectively have arc-shaped swing platforms.

[0008] According to an embodiment of the utility model, each of the above-mentioned angular displacement platforms further includes a base, a motor and a worm gear mechanism. The base is mounted on the above-mentioned mounting surface, and an arc-shaped guide rail matching the above-mentioned swing platform is mounted on the above-mentioned base, and the above-mentioned swing platform is mounted on the above-mentioned arc-shaped guide rail. The motor is mounted on one end of the above-mentioned base and is located on the above-mentioned mounting surface. The worm gear mechanism is mounted between the above-mentioned motor and the above-mentioned swing platform, and is suitable for driving the above-mentioned swing platform to swing in the above-mentioned arc-shaped guide rail under the rotation of the rotating shaft of the above-mentioned motor.

[0009] According to an embodiment of the utility model, the midpoints of the two arc-shaped guide rails are located on the intersection line, and the tilt angle adjustment platform further includes a second dual-axis tilt angle sensor. The second dual-axis tilt angle sensor is detachably mounted on the mounting platform and is located on the intersection line, and is suitable for providing a calibration angle to correct the installation error of the tilt angle adjustment platform.

[0010] According to an embodiment of the utility model, the differential pressure transmitter is installed on a mounting platform and is located on the intersection line.

[0011] According to an embodiment of the present invention, the shape of the installation platform includes any one of a polygon, a circle and an ellipse.

[0012] According to an embodiment of the utility model, the above-mentioned installation platform has a top surface and a bottom surface, and the above-mentioned first dual-axis inclination sensor is installed on the above-mentioned bottom surface.

[0013] According to an embodiment of the utility model, the tilt angle adjustment platform further comprises a support member, which is used to support the base and is suitable for providing stable support for the base to stabilize the position of the installation surface.

[0014] According to an embodiment of the utility model, the tilt angle adjustment platform also includes an electronic level, which is suitable for measuring the above-mentioned ideal plane.

[0015] According to an embodiment of the utility model, a plurality of mounting holes arranged in an array are provided on the mounting platform, and the micro differential pressure transmitter and the first dual-axis inclination sensor are respectively mounted on the mounting platform through the mounting holes by external fixing devices.

[0016] According to the tilt angle adjustment platform of the embodiment of the utility model, the measuring angle of the mounting platform is measured by the first dual-axis tilt sensor, and the measuring angle is used to represent the actual angle between the mounting platform and the ideal plane, so that the two angular displacement tables drive the mounting platform to deflect in response to the actual angle. When calibrating the differential pressure transmitter, the mounting platform can be kept parallel to the ideal plane, and a underlying surface parallel to the ideal plane can be provided for the calibration of the differential pressure transmitter. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other purposes, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0018] Figure 1 A side view of the tilt angle adjustment platform according to an embodiment of the utility model is schematically shown;

[0019] Figure 2 Schematically shows another side view of the tilt angle adjustment platform according to an embodiment of the utility model; and

[0020] Figure 3 A top view of a mounting platform according to an embodiment of the utility model is schematically shown;

[0021] Figure 4 The schematic diagram of horizontal direction error angle distribution according to an embodiment of the utility model is schematically shown;

[0022] Figure 5 The graph between the first angle relationship and the second angle relationship under different setting error angles according to the embodiment of the utility model is schematically shown.

[0023] Description of reference numerals:

[0024] 1- Base;

[0025] 2-Off-axis tilt assembly;

[0026] 21- angular displacement stage;

[0027] 211-base;

[0028] 212-swing table;

[0029] 213-motor;

[0030] 22-Installation platform;

[0031] 221-mounting hole;

[0032] 3- first dual-axis inclination sensor;

[0033] 4- Differential pressure transmitter. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention, and the various features described in the embodiments can be combined to form multiple optional solutions. It should also be noted that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, rather than all structures.

[0035] Figure 1 A side view of the tilt angle adjustment platform according to an embodiment of the utility model is schematically shown. Figure 2 Another side view of the tilt angle adjustment platform according to an embodiment of the utility model is schematically shown.

[0036] As one aspect of the present invention, a tilt angle adjustment platform is provided for calibrating a differential pressure transmitter 4, such as Figure 1 and Figure 2 As shown, the tilt angle adjustment platform includes a base 1, an off-axis tilt assembly 2 and a first dual-axis tilt sensor 3. The base 1 has a mounting surface, and the off-axis tilt assembly 2 includes two angular displacement tables 21 and a mounting platform 22. The two angular displacement tables 21 are stacked on the mounting surface, and the two rotation planes of the two angular displacement tables 21 are perpendicular, and the two rotation planes are perpendicular to the mounting surface. The mounting platform 22 is mounted on the angular displacement table 21 located at the upper part. The first dual-axis tilt sensor 3 is mounted on the mounting platform 22, and is suitable for providing a measurement angle, and characterizing the actual angle between the mounting platform 22 and the ideal plane with the measurement angle. Among them, the two angular displacement tables 21 drive the mounting platform 22 to deflect in response to the actual angle, so as to keep the mounting platform 22 always parallel to the ideal plane when the differential pressure transmitter 4 is calibrated.

[0037] According to the tilt angle adjustment platform of the embodiment of the utility model, the measuring angle of the mounting platform is measured by the first dual-axis tilt sensor, and the measuring angle is used to represent the actual angle between the mounting platform and the ideal plane, so that the two angular displacement tables drive the mounting platform to deflect in response to the actual angle. When calibrating the differential pressure transmitter, the mounting platform can be kept parallel to the ideal plane, and a underlying surface parallel to the ideal plane can be provided for the calibration of the differential pressure transmitter.

[0038] According to the embodiment of the utility model, the base 1 can be made of stainless steel, and the mounting platform 22 can be made of aluminum alloy material with light weight and high hardness.

[0039] According to the embodiments of the present utility model, Figure 1 and Figure 2 As shown, the two angular translation stages respectively have an arc-shaped swing table 212 , so that the two angular translation stages can respectively deflect along the arc-shaped trajectory of the swing table 212 .

[0040] According to the embodiments of the present utility model, Figure 1 and Figure 2As shown, each angular displacement platform also includes a base 211, a motor 213 and a worm gear mechanism. The base 211 is mounted on the mounting surface, and an arc guide rail matching with the swing table 212 is mounted on the base 211, and the swing table 211 is mounted on the arc guide rail. The motor 213 is mounted at one end of the base and is located on the mounting surface. The worm gear mechanism is installed between the motor and the swing table, and is suitable for driving the swing table to swing in the arc guide rail under the rotation of the rotating shaft of the motor.

[0041] Specifically, the first base of the first angular displacement table located at the bottom is installed on the mounting surface, and the first base is installed with a first arc-shaped guide rail matched with the first swing table of the first angular displacement table, and the first swing table is installed on the first arc-shaped guide rail. The first motor is installed at one end of the first base and is located on the mounting surface. The first worm gear mechanism is installed between the first motor and the first swing table, and is suitable for driving the first swing table to swing in the first arc-shaped guide rail under the rotation of the rotating shaft of the first motor. The second base of the second angular displacement table located at the upper part is installed at the top of the first swing table, and the second base is installed with a second arc-shaped guide rail matched with the second swing table of the second angular displacement table, and the second swing table is installed on the second arc-shaped guide rail. The second motor is installed at one end of the second base. The second worm gear mechanism is installed between the second motor and the second swing table, and is suitable for driving the second swing table to swing in the second arc-shaped guide rail under the rotation of the rotating shaft of the second motor.

[0042] In an illustrative embodiment, the swing amplitude of each angular displacement stage may be between ±15°. It is understandable that the swing amplitude of each angular displacement stage may be selected according to actual needs, for example, it may also be ±12°.

[0043] According to an embodiment of the present invention, the shape of the mounting platform 22 includes any one of a polygon, a circle and an ellipse.

[0044] In an illustrative embodiment, two angular translation stages use arc guide rails as guiding mechanisms, with a swing angle of ±15°, a motor step angle of 1.8°, transmission ratios of 320:1 and 450:1 respectively, resolutions of 0.0007° and 0.0005° respectively under 8 subdivisions, and repeatability positioning accuracy of less than 0.005°.

[0045] According to the embodiments of the present utility model, Figure 1 and Figure 2 As shown, the mounting platform 22 has a top surface and a bottom surface, and the first dual-axis tilt sensor 3 is mounted on the bottom surface. It can be understood that the first dual-axis tilt sensor 3 can also be mounted on the top surface.

[0046] According to the embodiments of the present utility model, Figure 1 and Figure 2As shown, the differential pressure transmitter 4 is mounted on the mounting platform 22 and is located on the intersection line of the midpoints of the two arc-shaped guide rails, so as to avoid uneven force on the mounting platform 22 when calibrating the differential pressure transmitter, which may cause the mounting platform 22 to deflect.

[0047] According to the embodiments of the present utility model, Figure 1 and Figure 2 As shown, the differential pressure transmitter 4 is mounted on the top surface of the mounting platform 22 .

[0048] According to an embodiment of the utility model, the tilt angle adjustment platform further comprises a support member (not shown in the figure), which is used to support the base and is suitable for providing stable support for the base to stabilize the position of the mounting surface.

[0049] According to an embodiment of the utility model, the tilt angle adjustment platform further comprises an electronic level, which is suitable for measuring an ideal plane.

[0050] Figure 3 A top view of a mounting platform according to an embodiment of the utility model is schematically shown.

[0051] According to the embodiments of the present utility model, Figure 3 As shown, a plurality of mounting holes 221 arranged in an array are provided on the mounting platform 22 , and the differential pressure transmitter 4 and the first dual-axis inclination sensor 3 are respectively mounted on the mounting platform 22 through the mounting holes 221 by external fixing devices.

[0052] According to an embodiment of the present invention, the mounting hole 221 may be a through hole or a threaded hole.

[0053] According to an embodiment of the utility model, the midpoints of the two arc-shaped guide rails are located on the intersection line, and the tilt angle adjustment platform further includes a second dual-axis tilt sensor, which is detachably mounted on the mounting platform 22 and is located on the intersection line (that is, Figure 1 The position where the differential pressure transmitter 4 is installed is suitable for providing a calibration angle to correct the installation error of the tilt angle adjustment platform.

[0054] According to the embodiment of the present utility model, the second dual-axis tilt sensor is mounted on the mounting platform 22 through the mounting hole 221 by an external fixing device.

[0055] According to an embodiment of the present invention, the fixing device may include a bolt, a screw rod, a nut or a combination thereof.

[0056] According to an embodiment of the present utility model, the second dual-axis inclination sensor cooperates with the first dual-axis inclination sensor 3 to correct the installation error of the tilt angle adjustment platform, so that the measurement angle measured by the first dual-axis inclination sensor can represent the actual angle between the installation platform and the ideal plane.

[0057] The tilt angle adjustment platform can control the mounting platform 22 to tilt in any direction through two angular displacement tables 21. The pitch and yaw angles relative to the ideal plane can reach ±12°. The angle accuracy between the mounting platform of the tilt angle adjustment platform and the ideal plane can reach 0.02°, which meets the requirements of the differential pressure transmitter for the underlying surface and has good application in actual verification and calibration processes.

[0058] In the process of implementing the utility model, it was found that due to errors in the processing technology and installation of the parts of the tilt angle adjustment platform, a certain angle deviation was generated in the vertical direction of the tilt angle adjustment platform and superimposed on the measurement angle of the first dual-axis tilt sensor, which affected the angle measurement and control of the angular displacement platform based on the first dual-axis tilt sensor. The tilt angle adjustment platform has four connected installation planes in the vertical direction (i.e., the top surface for installing the differential pressure transmitter, the bottom surface for installing the first dual-axis tilt sensor, the upper end surface of the first angular displacement platform, and the upper end surface of the second angular displacement platform). However, during the production and installation process, it is impossible to ensure that these four surfaces are in a parallel state, and the slight inclination between them will affect the angle state of the top surface for installing the differential pressure transmitter and the bottom surface for installing the first dual-axis tilt sensor.

[0059] Although the angular error caused by this installation error is difficult to quantitatively evaluate, it is a constant system error caused by the installation process or manufacturing process and will not change during the swing of the angular translation stage.

[0060] Figure 4 The diagram schematically shows a horizontal direction error angle distribution diagram according to an embodiment of the utility model.

[0061] In an illustrative embodiment, Figure 1 and Figure 2 As shown in the figure, the angular displacement stage at the bottom is the Y-axis angular displacement stage, and the angular displacement stage above the Y-axis angular displacement stage is the X-axis angular displacement stage. Figure 4 As shown, XOYZ represents the coordinate system of the ideal measurement axes of the two angular displacement stages, and the coordinate system of the ideal measurement axes may not be absolutely vertical. xoy represents the measurement coordinate system of the two measurement axes of the second dual-axis inclination sensor, and there may be small angles α and β between the two measurement axes of the second dual-axis inclination sensor and the ideal measurement axes in the corresponding directions, respectively.

[0062] Taking the x direction as an example, the construction unit is configured to construct a first angle matrix relationship between the ideal measurement axis vector x0 and the set error angle α based on the measurement axis direction of the first inclination sensor being parallel to one of the tilt axes of the two angular displacement stages, and obtain the actual installation measurement axis vector x c .

[0063] Ideal measurement axis vector x0 = [a, 0, 0] T , then the actual installation measurement axis vector x c The error angle α can be set by rotating the tilt axis around the Z axis, and the actual installation measurement axis vector x can be obtained. c :

[0064]

[0065] Among them, α is the setting error angle.

[0066] The first drive angle θ among the tilt axis rotation drive angles orthogonal to the ideal measurement axis x0 in the two angular translation stages x , construct a first drive angle θ x The first ideal measurement axis vector That is, the ideal measurement axis vector x0 and the actual installation measurement axis vector x c Rotate the first driving angle θ around the Y axis x , we can get the first ideal measurement axis vector

[0067]

[0068] Among them, α is the setting error angle, θ x is the first driving angle.

[0069] The tilt axes of the two angular translation stages that are orthogonal to the ideal measurement axis x0 are rotated by a first driving angle θ x After that, construct the first drive angle θ x The actual measured axis vector related to the set error angle α

[0070]

[0071] Among them, α is the setting error angle, θ x is the first driving angle.

[0072] For the first driving angle θ x The first ideal measurement axis vector Solve and get the first drive angle θ x The first angle relation is:

[0073]

[0074] Among them, α is the setting error angle, θ x is the first driving angle.

[0075] For the first driving angle θ xThe actual measured axis vector related to the set error angle α Solve and get the first drive angle θ x The second angle relationship between the setting error angle α is:

[0076]

[0077] Among them, α is the setting error angle, θ x is the first driving angle.

[0078] Figure 5 The graph between the first angle relationship and the second angle relationship under different setting error angles according to the embodiment of the utility model is schematically shown.

[0079] like Figure 5 As shown, the actual installation measurement axis vector x c The first driving angle θ is tilted around the Y axis x The actual measured angle θ x 'In the range of the swing amplitude of the swing table [-15°, 15°], it can be approximated as a linear function within the set error [0°, 90°]. Similarly, the set error angle α has an effect on the measurement axis y c , error angle β to the measuring axis x c and measuring axis y c The influence of is relatively stable, that is, the angle measured by the measuring axis of the first dual-axis inclination sensor is approximately a linear function with the inclination of the two angular displacement stages. That is, the calibration angle and the driving angle of the second dual-axis inclination sensor are approximately linearly related, and the measurement angle of the first dual-axis inclination sensor and the calibration angle of the second dual-axis inclination sensor are approximately linearly related.

[0080] Therefore, there is a first mapping relationship between the driving angle and the calibration angle, and there is a second mapping relationship between the calibration angle and the measurement angle. The first mapping relationship can be represented by a first homography matrix, and the second mapping relationship can be represented by a second homography matrix.

[0081] Furthermore, a driving angle can be generated according to the target angle, and at least one of the two angular displacement tables can be driven to rotate based on the driving angle to deflect the mounting platform to obtain a calibration angle measured by the second dual-axis inclination sensor and a measurement angle measured by the first dual-axis inclination sensor, and a first installation error between the two angular displacement tables and the second dual-axis inclination sensor can be corrected according to the driving angle and the calibration angle, and a second installation error between the first dual-axis inclination sensor and the second dual-axis inclination sensor can be corrected according to the calibration angle and the measurement angle.

[0082] Specifically, the following process may be repeated multiple times (for example, greater than or equal to 4 times): setting a target angle, driving at least one of the angular displacement stages to rotate, and recording the target angle, the driving angle, the calibration angle, and the measurement angle, respectively. Further, a first homography matrix between the driving angle and the calibration angle is obtained based on the target angle and the driving angle measured multiple times, and a second homography matrix between the calibration angle and the measurement angle is obtained based on the calibration angle and the measurement angle measured multiple times.

[0083] According to an embodiment of the utility model, the homography matrix is ​​a 3×3 matrix, which is generally used to describe the transformation relationship between two image planes. In computer vision, it is generally used for tasks such as image correction, image stitching and 3D reconstruction. In the tilt angle adjustment platform provided by the utility model, the first homography matrix is ​​used to describe the transformation relationship between the driving angle and the calibration angle, and the second homography matrix is ​​used to describe the transformation relationship between the calibration angle and the measurement angle. The first homography matrix is ​​used to control the driving angle of the angular displacement table, and the second homography matrix is ​​used to cooperate with the first dual-axis tilt sensor to obtain the actual angle value of the top surface of the mounting platform after the swing.

[0084] According to the embodiments of the utility model, the first installation error can be compensated by the first homography matrix, and the second installation error can be compensated by the second homography matrix. The actual angle of the top surface can be monitored in real time through the measurement values ​​measured by the first dual-axis inclination sensor, thereby reducing the error in the angle measurement of the top surface of the installation platform.

[0085] The analysis of the installation error of the correction system for the installation error of the inclination sensor shows that there is a high linear relationship between the calibration angle and the drive angle measured by the second dual-axis inclination sensor. Therefore, the first homography matrix H1 between the calibration angle of the second dual-axis inclination sensor and the drive angle of the angular displacement stage can be calculated based on the homography method, so as to calculate the drive angle required to actually drive the angular displacement stage to rotate in order to tilt the installation platform to the target angle after the system is calibrated. Similarly, the second homography matrix H2 between the calibration angle and the measured angle can be calculated based on the homography method.

[0086] According to the embodiment of the utility model, since the homography transformation method is based on the plane assumption, the better the planarity of the two surfaces used for estimation, the higher the accuracy of the homography estimation. In other words, if the linearity of the driving angle of the angular displacement stage and the calibration angle measured by the second dual-axis tilt sensor is higher, the accuracy of the angle mapping method based on the homography transformation method is better.

[0087] In an illustrative embodiment, assuming is the first homogeneous coordinate formed by the angle value of the angular displacement stage tilted in two directions, is the second homogeneous coordinate formed by the corresponding angle value i measured by the second dual-axis inclination sensor, then Transform to It can be obtained through the first homography matrix H1, and the mapping relationship is as follows:

[0088]

[0089] Among them, H1 is a 3×3 matrix, and substituting the coordinates into it, we can get:

[0090]

[0091] Among them, h nm Represents the coefficients of the nth row and mth column of the first homography matrix, n=1,2,3; m=1,2,3.

[0092] Furthermore, formula (7) can be transformed into:

[0093]

[0094] Among them, h nm Represents the coefficients of the nth row and mth column of the first homography matrix, n=1,2,3; m=1,2,3.

[0095] The first homography matrix H1 can be used to calibrate the angles (X i ,Y i ), which is converted into the driving angle (x i ,y i ), when i=0°, that is (X i ,Y i )=(0,0), the angular displacement stage is adjusted according to the calculated driving angle (x0,y0), and the function of angle control of the top surface of the mounting platform can be realized.

[0096] Depend on Figure 1 and Figure 2 As shown, the upper second angular displacement stage (for example, an X-axis angular displacement stage) is installed on the lower first angular displacement stage (for example, a Y-axis angular displacement stage). The rotation of the lower first angular displacement stage will cause an off-axis tilt angle error in the second angular displacement stage. This off-axis tilt angle error is a nonlinear error.

[0097] According to an embodiment of the present invention, the nonlinear error can be determined based on the ideal measurement axis angle and the driving angle where the second dual-axis inclination sensor is located.

[0098] Specifically, after the second driving angle in the driving angle is rotated based on the first ideal measurement axis vector related to the first driving angle, a second ideal measurement axis vector related to the first driving angle and the second driving angle is constructed, wherein the first driving angle is an angle for driving one of the two angular displacement tables to rotate, and the second driving angle is an angle for driving the other of the two angular displacement tables to rotate. The first ideal measurement axis vector is obtained by rotating the tilt axis orthogonal to the ideal measurement axis of the second dual-axis inclinometer in the two angular displacement tables by the first driving angle.

[0099] Furthermore, by solving the second ideal measurement axis vector, a third angle relationship related to the first drive angle and the second drive angle is obtained, and the difference between the first drive angle and the third angle relationship is obtained, and the difference is determined as the nonlinear error to achieve the determination of the nonlinear error. In this way, after the angular displacement stage located below rotates, the driving angle of the angular displacement stage located above can be compensated by the nonlinear error, so that the angular displacement stage located above rotates according to the compensated driving angle.

[0100] In an exemplary embodiment, based on the first driving angle θ x The first ideal measurement axis vector The second driving angle θ in the rotation driving angle y After that, construct the first drive angle θ x and the second driving angle θ y The second ideal measurement axis vector Wherein, the first driving angle θ x The second driving angle θ is the angle at which one of the two angular displacement stages is driven to rotate. y is the angle by which the other of the two angular translation stages is driven to rotate.

[0101] The ideal measurement axis vector x0 rotates around the Y axis by the first driving angle θ x Get the first ideal measurement axis vector Then the first ideal measurement axis vector Rotate the second driving angle θ around the X axis y When the second ideal measurement axis vector It can be expressed as:

[0102]

[0103] Among them, α is the setting error angle, θ x is the first driving angle, θ y is the second driving angle.

[0104] For the first driving angle θ x and the second driving angle θ y The second ideal measurement axis vector Solve and get the first drive angle θ x and the second driving angle θ y The relevant third angle relationship is:

[0105]

[0106] Among them, α is the setting error angle, θ x is the first driving angle, θ y is the second driving angle.

[0107] There is a small nonlinear error in the angle of the X-axis measurement. After the Y-axis angular stage (that is, the first angular stage installed at the bottom) moves, the X-axis angular stage (the second angular stage installed at the top) should be compensated.

[0108] Calculate the first driving angle θ x The difference between the third angle relationship and the nonlinear error is taken as error:

[0109]

[0110] Among them, α is the setting error angle, θ x is the first driving angle, θ y is the second driving angle.

[0111] The installation error of the tilt angle adjustment platform is a combination of linear and nonlinear. The nonlinear part can be represented by formula (11). Therefore, the installation error of the system only needs to calibrate the linear part.

[0112] Considering that the workpiece to be measured needs to be placed on the top surface of the installation platform during daily measurement and calibration, the first dual-axis inclination sensor needs to be installed below the installation platform (that is, on the bottom surface) to measure and control the angle of the top surface relative to the ideal plane in real time. However, the top surface and the installation plane of the first dual-axis inclination sensor are not absolutely parallel. Therefore, the second homography matrix H2 of the top surface and the installation plane of the first dual-axis inclination sensor should be calibrated on the two planes to monitor the inclination of the top surface in real time.

[0113] The distribution of calibration points used for homography estimation is rationalized, which can not only reduce the number of points used for homography estimation and the amount of calibration calculation, but also improve the calibration accuracy. Homography estimation is based on the plane assumption, which means that the better the planeness of the points used for homography estimation, the higher the homography estimation accuracy. From formula (11), it can be obtained that the nonlinear error error point is close to θ x =0° and θ y =0°, they are all approximately 0°, and the overall planarity is good, so the angle position point for constructing homography estimation is selected as θx =0° and θ y The best effect is achieved at the angle position of =0°.

[0114] After correcting the installation errors (the first installation error, the second installation error and the nonlinear error), the accuracy of the tilt angle adjustment platform can reach 0.02°. In actual use, the tilt angle adjustment platform can calculate the driving angle that the angular displacement stage actually needs to rotate according to the target angle and the first homography matrix. After the angular displacement stage located below rotates according to the driving angle, the driving angle of the angular displacement stage located above is compensated according to the nonlinear error, so that the angular displacement stage located above rotates according to the compensated driving angle, and then the first dual-axis tilt sensor measures the current measurement angle, and obtains the actual angle of the top surface according to the second homography matrix and the measurement angle, and judges whether the top surface is parallel to the ideal plane according to the actual angle. In the case that the top surface is not parallel to the ideal plane, the updated target angle is generated according to the actual angle, and at least one of the two angular displacement stages is deflected again until the top surface is parallel to the ideal plane.

[0115] In an illustrative embodiment, the y-axis angular displacement table of the two angular displacement tables is fixed, and the x-axis angular displacement table is swung at intervals of 3° within the range of [-12°, 12°], and the calibrated angle values ​​and measured angle values ​​respectively measured by the second dual-axis inclination sensor and the first dual-axis inclination sensor are measured and recorded to determine the installation error.

[0116] The relationship between the two-axis measurement values ​​of the two dual-axis inclination sensors and the inclination value of the x-axis angular displacement stage is as follows:

[0117] The relationship between the x-axis measurement value y1 of the second dual-axis inclination sensor and the driving angle x1 of the angular displacement stage is:

[0118] y1=0.9942x1+0.3969,R 2 =0.9999 (12)

[0119] The relationship between the x-axis measurement value y2 of the first dual-axis inclination sensor and the driving angle x1 of the angular displacement stage is:

[0120] y2=0.9939x1+0.4297,R 2 =0.9999 (13)

[0121] The relationship between the y-axis measurement value y3 of the second dual-axis inclination sensor and the driving angle x1 of the angular displacement stage is:

[0122] y3=0.0152x1+0.1025,R 2 =0.9997 (14)

[0123] The relationship between the y-axis measurement value y4 of the first dual-axis inclination sensor and the driving angle x1 of the angular displacement stage is:

[0124] y4=0.0195x 1+ 0.1524, R 2 =0.9996 (15)

[0125] In formulas (12) to (15), R 2 represents the coefficient of determination.

[0126] It can be seen from formulas (12) to (15) that the linearity of the two measuring axes of the two dual-axis inclination sensors is very high when a certain swing axis tilts, which proves that the constructed inclination angle adjustment platform has a small approximate linear error in the horizontal direction. After obtaining the corresponding angle conversion relationship using the homography estimation method, the angle range of [-12°, 12°] with an interval of 3° is collected to observe the error between the measured angle and the driving angle of the two axes of the two dual-axis inclination sensors. The maximum error before calibration compensation is 0.559° and -0.216°, and the maximum error after calibration compensation is 0.020° and 0.013°. The inclination angle adjustment platform provided by the utility model can reduce the angle error by an order of magnitude, meeting the calibration accuracy requirement of 0.02° in most engineering applications.

[0127] By respectively correcting the first installation error, the second installation error and the nonlinear error, the actual angle between the top surface of the installation platform and the ideal plane can be monitored by the first dual-axis inclination sensor, and the driving angle can be updated by the actual angle, so that the top surface of the installation platform is always parallel to the ideal plane. When the micro differential pressure transmitter is verified and calibrated, the second dual-axis inclination sensor is removed and the differential pressure transmitter is installed on the top surface of the installation platform. Since the top surface of the installation plane is always parallel to the ideal plane, the requirements of the differential pressure transmitter for the underlying surface can be met, and it has a good application in the actual verification and calibration process.

[0128] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A tilt angle adjustment platform, characterized in that: Used for calibrating a differential pressure transmitter (4), the tilt angle adjustment platform comprises: A base (1) having a mounting surface; An off-axis tilt assembly (2) comprising: Two angular displacement tables (21) are stacked on the mounting surface, the two rotation planes of the two angular displacement tables (21) are perpendicular, and the two rotation planes are perpendicular to the mounting surface; and A mounting platform (22) mounted on the angular displacement platform (21) located at the upper portion; A first dual-axis inclination sensor (3), mounted on the mounting platform (22), adapted to provide a measurement angle and to characterize an actual angle between the mounting platform (22) and an ideal plane using the measurement angle; The two angular displacement platforms (21) drive the mounting platform (22) to deflect in response to the actual angle, so as to keep the mounting platform (22) always parallel to the ideal plane when calibrating the differential pressure transmitter (4).

2. The tilt angle adjustment platform according to claim 1, characterized in that: The two angular displacement platforms respectively have an arc-shaped swinging platform (212).

3. The tilt angle adjustment platform according to claim 2, characterized in that: Each of the angular displacement stages further comprises: A base (211) is mounted on the mounting surface, an arc-shaped guide rail matching the swing table (212) is mounted on the base (211), and the swing table (212) is mounted on the arc-shaped guide rail; A motor (213) is mounted on one end of the base and is located on the mounting surface; and The worm gear mechanism is installed between the motor and the swing table, and is suitable for driving the swing table to swing in the arc guide rail under the rotation of the rotating shaft of the motor.

4. The tilt angle adjustment platform according to claim 3, characterized in that: The midpoints of the two arc-shaped guide rails are located on the intersection line, and the tilt angle adjustment platform further includes: A second dual-axis tilt sensor is detachably mounted on the mounting platform (22) and is located on the intersection line, and is suitable for providing a calibration angle to correct the installation error of the tilt angle adjustment platform.

5. The tilt angle adjustment platform according to claim 4, characterized in that: The differential pressure transmitter (4) is mounted on the mounting platform (22) and is located on the intersection line.

6. The tilt angle adjustment platform according to claim 1, characterized in that: The shape of the mounting platform (22) includes any one of a polygon, a circle and an ellipse.

7. The tilt angle adjustment platform according to claim 1, characterized in that: The mounting platform (22) has a top surface and a bottom surface, and the first dual-axis inclination sensor (3) is mounted on the bottom surface.

8. The tilt angle adjustment platform according to claim 1, characterized in that: Also includes: The support member is used to support the base and is suitable for providing stable support for the base to stabilize the position of the mounting surface.

9. The tilt angle adjustment platform according to claim 1, characterized in that: Also includes: The electronic level is suitable for measuring the ideal plane.

10. The tilt angle adjustment platform according to any one of claims 1 to 9, characterized in that: The mounting platform (22) is provided with a plurality of mounting holes (221) arranged in an array, and the differential pressure transmitter (4) and the first dual-axis inclination sensor (3) are respectively mounted on the mounting platform (22) through the mounting holes (221) by means of external fixing devices.

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