CN206132015U - Etalon that multisensor measuring engine coordinate is unified and precision is examined and determine - Google Patents

Abstract

A standard for coordinate unification and accuracy verification of a multi-sensor measuring machine is used for calibration of a compound coordinate measuring machine integrating an image sensor, a contact sensor and a non-contact displacement sensor, including a base and a fixed setting on the base Two or more calibrators with the same structure and different heights. The utility model can realize the unification of two or three coordinates of a contact sensor, an image sensor and a non-contact displacement sensor. As well as the measurement accuracy verification in the global measurement space of the measuring machine, the operation is simple and convenient, and the calibration efficiency is high. The utility model can obtain workpieces whose roundness, cylindricity, coaxiality, verticality and other errors are less than tens of nanometers. The image sensor images the top circle of the cone at one time, and the contact sensor measures the circle two-dimensionally, which reduces the influence of multi-dimensional motion. The standard device composed of two above-mentioned calibrators is suitable for the accuracy verification of the global measurement space or the local measurement space of the high-precision compound measuring machine.

Description

A Standard for Coordinate Unification and Accuracy Verification of Multi-sensor Measuring Machines

technical field

The utility model relates to a coordinate unifying and precision testing standard device. In particular, it relates to a standard device for coordinate unification and accuracy verification of a multi-sensor measuring machine that integrates multiple sensors such as image sensors, contact sensors and non-contact displacement sensors.

Background technique

Coordinate measuring machines are an important means of measuring workpiece dimensions and are widely used in many industries. At present, due to the more precise and specialized workpieces, and the more delicate and complex structures, the traditional contact single sensor is difficult to meet the measurement requirements in many cases. The multi-sensor compound measuring machine can realize the measurement work that was difficult to complete by a single sensor in the past. Integrating multiple sensors such as image sensors, contact sensors and non-contact displacement sensors into the same measuring machine can realize competitive, cooperative and complementary measurements of different characteristics and sizes, and achieve the purpose of optimal measurement. For example: use the image to measure the diameter of the microhole, use the non-contact displacement sensor to measure the free-form surface of the lens, etc.

To realize multi-sensor composite measurement, it is necessary to unify the coordinates of multiple sensors, that is, put multiple coordinate systems into the same coordinate system. Usually, a physical standard with certain geometric features or a combination of certain geometric features is used as a medium for multi-sensor coordinate fusion (registration), such as the longest standard ball used in traditional coordinate machine verification. On a measuring machine that only uses a single contact sensor, using a standard ball as a physical standard has shown good results and is widely accepted by the industry. In theory, the contact sensor takes multiple points on the standard sphere to measure the three-dimensional coordinates of the center of the sphere; the image sensor measures the equatorial circle of the standard sphere to obtain the two-dimensional coordinates of the sphere center; the non-contact distance sensor captures the standard sphere The two-dimensional coordinates of the center of the sphere can also be obtained. However, when the precision requirements are high, such as in submicron-level high-precision composite measurement, how to integrate the different coordinate systems of multiple sensors into the same coordinate system, the above-mentioned traditional methods have shortcomings. Take the non-contact distance sensor to capture the zenith pole as an example. Limited by the resolution of the distance sensor, when the sensor obtains the pole and the value does not change, the corresponding point on the X-Y plane is not the only point, but an area. For another example, when the image sensor collects points on the standard spherical equator circle, it puts forward very high requirements on the lighting quality of the light source. In addition, the processing of the sphere requires a special process, and there are technical difficulties when it needs to be combined with other objects or reprocessed.

How to unify the different coordinate systems of multiple sensors into the same coordinate system with high precision in sub-micron composite measurement to achieve high-precision measurement of the measuring machine; how to solve the problem of the standard ball used in the traditional contact coordinate measuring machine The inapplicability of multi-sensor coordinate unification; how to verify the measurement accuracy of the compound measuring machine, and many other problems need to be solved.

Contents of the invention

The technical problem to be solved by the utility model is to provide a standard device for coordinate unification and accuracy verification of a multi-sensor measuring machine.

The technical solution adopted by the utility model is: a standard device for coordinate unification and accuracy verification of a multi-sensor measuring machine, which is used for calibration of a composite coordinate measuring machine integrating an image sensor, a contact sensor and a non-contact displacement sensor , is characterized in that it includes a base and more than two standardizers with the same structure and different heights fixedly arranged on the base.

The multi-sensor measuring machine coordinate unification and accuracy verification standard device of the utility model can realize the coordinate unification of two or three coordinates of a contact sensor, an image sensor, and a non-contact displacement sensor. As well as the measurement accuracy verification in the global measurement space of the measuring machine, the operation is simple and convenient, and the calibration efficiency is high. The calibrator in the utility model is made of a cylindrical base material, classic turning process, and one-time clamping of ultra-finishing equipment, and the process is mature; and the errors such as roundness, cylindricity, coaxiality, and verticality can be obtained less than dozens nanoscale artifacts. The image sensor images the top circle of the cone at one time, and the contact sensor measures the circle two-dimensionally, which reduces the influence of multi-dimensional motion. The standard device composed of two above-mentioned calibrators is suitable for the accuracy verification of the global measurement space or the local measurement space of the high-precision compound measuring machine.

Description of drawings

Fig. 1 is the structure schematic diagram of the standard device of coordinate unification and accuracy verification of multi-sensor measuring machine of the present invention;

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

Fig. 3 is the structural representation of the standard device in the utility model;

Fig. 4 is the side view of standard device in the utility model;

Figure 5 is a top view of Figure 4;

Fig. 6 is a structural schematic diagram of a compound coordinate measuring machine;

Fig. 7 is the schematic diagram when calibrator calibration in the utility model;

Fig. 8 is a schematic diagram of a model for calibrating the XY direction of a compound coordinate measuring machine;

Fig. 9 is a schematic diagram of a model for calibrating the Z direction of a compound coordinate measuring machine.

in the picture

1: Base 2: Calibrator

21: Cylinder 22: Conical truncated

3: Compound coordinate measuring machine frame 4: Compound coordinate measuring machine X axis

5: Compound coordinate measuring machine Z axis 6: Worktable (Y axis)

7: Standard V: Image sensor

P: contact sensor L: non-contact displacement sensor

detailed description

The standard device for coordinate unification and accuracy verification of the multi-sensor measuring machine of the present invention will be described in detail below in conjunction with the embodiments and accompanying drawings.

As shown in Fig. 1, Fig. 2, Fig. 6 and Fig. 7, the multi-sensor measuring machine coordinate unification and precision verification standard device of the present invention is used to integrate image sensor, contact sensor and non-contact displacement sensor The calibration and accuracy verification of the compound coordinate measuring machine includes a base 1 and more than two calibrators 2 with the same structure and different heights fixedly arranged on the base 1 . As shown in FIG. 2 , the distance l between the central axes of every two scalers 2 is known. Each calibrator 2 can individually complete coordinate unification of multiple sensors.

As shown in Fig. 3, Fig. 4, Fig. 5, described calibrator 2 comprises cylinder 21, and the upper end surface of described cylinder 21 is fixedly provided with conical frustum 22, and described conical frustum 22 is the same as described cylinder 22. axis settings. in:

As shown in FIG. 7 , the diameter lv of the upper surface Zs of the truncated cone 22 is smaller than the measurement field range of the image sensor on the compound coordinate measuring machine. The size of the included angle θ between the generatrix (inclined plane) Zm of the truncated cone 22 and the upper surface Zx of the cylinder 1 is within the angle range that can be measured by the non-contact displacement sensor on the compound coordinate measuring machine, or the upper surface of the truncated cone 22 The vertical distance h _l between the end face and the lower end face is within the measurement range of the non-contact displacement sensor.

The calibrator 2 of the utility model is made by ultra-finishing, and the precision is better than submicron level. The coordinate unification of the image sensor, the contact sensor and the non-contact displacement sensor is completed by using a single calibrator 2 . By moving the XYZ axis of the coordinate machine, the image sensor, contact sensor and non-contact displacement sensor can measure the horizontal and vertical distances of the standard composed of multiple calibrator 2, and complete the accuracy verification of the composite measuring machine in the measurement space.

The calibration method of the standard device using multi-sensor measuring machine coordinates unification and accuracy verification of the utility model adopts any calibration device 2 in the standard device to carry out unified coordinate calibration of the multi-sensors of the composite coordinate measuring machine, and the calibration includes the following step:

1) Use the image sensor V, contact sensor P and non-contact displacement sensor L shown in Figure 4 to measure the calibrator respectively, where

Measurements of the image sensor V include:

(1) Adjust the focus of the image sensor V, and make the upper end surface Zs of the conical frustum 22 of the calibrator as a whole within the field of view of the image sensor V after the focus is clear;

(2) Obtain the circular boundary of the upper end surface Zs of the calibrator conical frustum 22 through the image sensor V;

(3) Obtain the center V ₀ of the upper end face of the frustum of cone 22 through the circular boundary;

(4) Use the center of circle V ₀ obtained in step (3) as the position or coordinates of the image sensor V on the compound coordinate measuring machine.

At this time, the acquisition of the circle center V ₀ is done by the image sensor once, and the compound coordinate measuring machine has no mechanical displacement, so there will be no mechanical motion error.

The measurements of the contact sensor P include:

(1) Use the contact sensor P to measure multiple points on the cross-sectional circumference of the same position Ysc of the cylinder 21;

( ₂ ) Extracting the center P ₀ of the section, which is used as the position or coordinates of the touch sensor P on the compound coordinate measuring machine.

At this time, the Z-axis of the compound coordinate measuring machine is in a locked state, and only the 2-dimensional movement of the X-axis and Y-axis realizes data acquisition. Compared with the 3-dimensional movement usually required to measure the coordinates of the center of the sphere, the mechanical movement error is reduced.

The calibration of the non-contact displacement sensor includes:

(1) Use the non-contact displacement sensor L to scan the conical frustum 22 along the X direction and the Y direction respectively;

(2) Find out the center of symmetry or the axis of symmetry of the truncated cone 22 as the center L ₀ of the upper end face of the truncated cone 22 according to the scan results;

(3) The center L ₀ of the upper end surface of the conical frustum 22 is taken as the position or coordinates of the non-contact displacement sensor L on the compound coordinate measuring machine.

2) Use a contact sensor to measure the top surface of the cylinder to obtain the height Zp;

3) Use a non-contact displacement sensor to measure the upper surface of the truncated cone 22 to obtain the height _Z1 ;

4) Find out the position or coordinate point V ₀ of the image sensor, the position point P ₀ of the contact sensor and the position point L ₀ of the non-contact displacement sensor on the XY plane of the same coordinate system. The difference between the height Zp of the upper end surface and the height Z _l of the upper end surface of the truncated cone 22, thereby obtaining the positional relationship between the image sensor, the contact sensor and the non-contact displacement sensor, and completing the relationship between the image sensor, the contact sensor and the non-contact displacement sensor Coordinate unification or calibration.

It should be the same point under the XY plane of the same coordinate system (its Z axis is parallel to the axis of symmetry of the calibrator), but step 1) adopts the calibrator 2 of the present utility model to obtain the position of the image sensor as shown in Figure 8 Point V ₀ , the difference between the position point P ₀ of the contact sensor and the position point L ₀ of the non-contact displacement sensor, find the position difference between the three position points V ₀ , P ₀ and L ₀ △YVL, △YPV, △YPL, △XVP, △XPL, △XVL, the positional relationship in the xy plane between the image sensor V, the contact sensor P and the non-contact displacement sensor L is obtained from the difference; The difference ΔZ of the coordinates in the Z direction shown in FIG. 9 .

The utility model uses a multi-sensor measuring machine coordinate unification and precision verification standard to detect the accuracy of a compound coordinate measuring machine, which is a method for measuring the accuracy of a compound coordinate measuring machine based on an image sensor, a contact sensor and a non-contact displacement sensor. detection, where:

The measurement accuracy detection based on the image sensor includes the following steps:

1) Align the image sensor V with the upper end surface of the truncated cone 22 of any one of the calibrator 2 in the standard, and adjust the focus. After the focus is clear, the upper end surface of the truncated cone 22 of the calibrator 2 is within the field of view of the image sensor V as a whole;

2) Obtain the circular boundary of the upper end face of the truncated cone 22 of the calibrator 2 through the image sensor V;

3) Obtain the center of circle on the upper end face of the truncated cone 22 of the calibrator 2 through the circular boundary;

4) Repeat step 1) to step 3) to respectively obtain the center of circle of the upper end surface of the truncated cone 22 of other calibrator in the standard;

5) Solve the center-to-centre distance between the upper end faces of the frustum 22 of every two calibrator 2, and the known value between the upper end faces of the frustum 22 of the two calibrator 2 corresponding to the used standard The difference is calculated to obtain a difference value, and the difference value is a measurement error of the compound coordinate measuring machine based on the image sensor.

The measurement accuracy detection based on the contact sensor includes the following steps:

1) Use contact sensors to respectively extract the center coordinates of the cylinders 21 of each calibrator 2 in the standard device in the X and Y directions within the set area;

2) Obtain the center-to-center distance between every two calibration devices 2 according to the obtained center coordinates of each calibration device 2;

3) The known value of the center-to-center distance between each two calibration devices 2 described in step 2) and the corresponding two calibration devices 2 in the used standard device is calculated to obtain a difference, to obtain a difference, Complete the accuracy verification of the X and Y directions of the compound coordinate measuring machine based on the contact sensor in the set area;

4) Use a contact sensor to measure the top surface Z _X of the cylinder 21 of each calibrator 2 in the standard in the set area respectively, to obtain the height measurement value Zp of the cylinder 21 of each calibrator 2;

5) Calculate the difference between the height measurement value Zp of the cylinder 21 of each calibrator 2 obtained in step 4) and the known height value of the top surface of the cylinder 21 of each calibrator 2 in the standard device to obtain the Z-direction measurement error, and complete The accuracy verification of the compound coordinate measuring machine based on the contact sensor in the Z direction of the set area is carried out.

The measurement accuracy detection based on the non-contact displacement sensor includes the following steps:

1) Use the non-contact displacement sensor L to measure the height Z _X of the top surface of the cylinder 21 of each calibrator 2 in the standard, respectively, to obtain the height measurement value Z _l of the cylinder 21 of each calibrator 2;

2) Calculate the difference between the measured height value Z1 obtained in step ₁ ) and the known height value of the cylinder 21 of each calibrator 2 in the standard device, and the difference is measured in the Z direction of the composite coordinate measuring machine based on the non-contact displacement sensor error.

changing the position of the standard in the measurement space of the composite coordinate measuring machine, repeating the steps of measuring accuracy detection based on the image sensor, the detection accuracy of measurement based on the contact sensor and the detection accuracy of measurement based on the non-contact displacement sensor, Complete the measurement accuracy verification of different local spaces of the compound coordinate measuring machine.

The overall Z-direction position change of the etalon is realized by using parallel planes whose accuracy meets the requirements to raise the etalon described above, such as by using a gauge block group.

In this way, the multi-sensor coordinate unification of the composite measuring machine and the measurement accuracy verification in the measuring space of the measuring machine can be realized.

Claims (1)

1. A standard device for unification of coordinates of a multi-sensor measuring machine and accuracy verification is used for the calibration of a multi-sensor measuring machine integrating image sensors, contact sensors and non-contact displacement sensors, and is characterized in that it includes a base ( 1) and more than two calibrators (2) with the same structure and different heights fixed on the base (1), the calibrator (2) includes a cylinder (21), and the upper part of the cylinder (21) A conical frustum (22) is fixedly arranged on the end surface, and the conical frustum (22) is arranged coaxially with the cylinder (21). Field range, the angle between the generatrix of the truncated cone (22) and the top surface of the cylinder (21) is within the angle range measured by the non-contact displacement sensor on the multi-sensor measuring machine, and the upper surface of the truncated cone (22) The vertical distance between the end face and the lower end face is within the measurement range of the non-contact displacement sensor.