1. A control method for a CMM system, comprising the steps of:

step S110: providing a probe and a plurality of laser interferometers arranged around the probe, wherein laser emitted by the plurality of laser interferometers is converged at the probe;

step S120: establishing a relation between the displacement of the probe and the laser interferometer;

step S130: analyzing the surface shape characteristics of the measured object, dotting through the probe to obtain corresponding interferometer displacement so as to obtain characteristic points on the characteristic surface, and performing characteristic fitting through a least square method fitting mode;

step S140: generating a point set on the characteristic surface by adopting a minimum interpolation method, and taking the point set as an automatic dotting sampling point;

step S150: finishing the dotting work on the plane of the measured object according to the sampling points;

step S160: and (4) performing zernike polynomial fitting on the point set obtained by the dotting work in the step to obtain a fitted wave surface, further obtaining PV and RMS values, and completing the analysis of the surface shape.

2. The control method for a CMM system as defined by claim 1, wherein the laser interferometers are three and are mounted in a perpendicular manner.

3. The control method for a CMM system as claimed in claim 1, wherein in the step of establishing the connection between the displacement of the probe and the laser interferometer, the steps of:

and operating a data acquisition module in a Labview upper computer program, reading the data of the laser interferometer by the data acquisition module and feeding the data back to the Labview upper computer, establishing the relation between the displacement of the probe and the laser interferometer by the Labview upper computer according to the data, and electrically connecting the laser interferometer and the probe by the Labview upper computer.

4. The control method for the CMM system as claimed in claim 3, wherein the laser interferometer senses the displacement variation of the probe in 3 degrees of freedom in a Cartesian coordinate system to establish a coordinate variation equation set, and the coordinate transformation matrix in the coordinate variation equation is solved by means of least square fitting to obtain the corresponding relationship between the deformation of the probe when detecting the object to be measured and the laser interferometer.

5. The control method for a CMM system as claimed in claim 1, wherein the step of generating a set of points on the feature plane by using a minimum interpolation method and using the set of points as the sampling points for automatic dotting comprises:

and generating a point set on the characteristic surface by using Matlab software and adopting a minimum interpolation method, and taking the point set as a sampling point for automatic dotting.

6. The control method for a CMM system as claimed in claim 1, wherein the step of performing the dotting operation on the plane of the object to be measured based on the sampling points specifically comprises:

and the Labview upper computer acquires the sampling point, and an automatic dotting module in the Labview upper computer finishes dotting work on the plane to be measured according to the sampling point.

7. The control method for a CMM system as claimed in claim 1, wherein the step of performing zernike polynomial fitting on the strip data to obtain a fitted wave surface, further obtaining PV and RMS values, and completing the analysis of the surface shape comprises:

and a data decoupling module in the Labview upper computer acquires the belt data, decouples the stored belt data points, stores the data points by using a TMS file, and then performs zernike polynomial fitting to obtain a fitted wave surface, further obtain PV and RMS values, and finish the analysis of the surface shape.

Background

The three-coordinate measuring machine is a high-efficiency novel precision measuring instrument developed in recent decades. It is widely used in the industries of mechanical manufacturing, electronics, automotive, aerospace, and the like. It can detect the size, shape and mutual position of parts and components, such as the measurement of space profiles of boxes, guide rails, scrolls and blades, cylinders, cams, gears, shapes, etc. In addition, the device can be used for drawing lines, centering holes, photoetching integrated circuits and the like, and can be used for scanning continuous curved surfaces and preparing processing programs of numerical control machine tools and the like. The flexible measuring instrument has the advantages of strong universality, large measuring range, high precision, high efficiency and good performance, and can be connected with a flexible manufacturing system, so that the flexible measuring instrument becomes a large-scale precision instrument and is called as a measuring center.

At present, the three-coordinate measuring machine has higher requirement on the precision of a motion platform, and the precision of a measured object needs to be improved.

Disclosure of Invention

In view of this, it is necessary to provide a control method and a calibration apparatus for a CMM system, which have low requirement on precision of a motion platform and high precision of a measured object, aiming at the defects in the prior art.

In order to solve the problems, the invention adopts the following technical scheme:

a control method for a CMM system comprising the steps of:

step S110: providing a probe and a plurality of laser interferometers arranged around the probe, wherein laser emitted by the plurality of laser interferometers is converged at the probe;

step S120: establishing a relation between the displacement of the probe and the laser interferometer;

step S130: analyzing the surface shape characteristics of the measured object, dotting through the probe to obtain corresponding interferometer displacement so as to obtain characteristic points on the characteristic surface, and performing characteristic fitting through a least square method fitting mode;

step S140: generating a point set on the characteristic surface by adopting a minimum interpolation method, and taking the point set as an automatic dotting sampling point;

step S150: finishing the dotting work on the plane of the measured object according to the sampling points;

step S160: and (4) performing zernike polynomial fitting on the point set obtained by the dotting work in the step to obtain a fitted wave surface, further obtaining PV and RMS values, and completing the analysis of the surface shape.

In some of these embodiments, the laser interferometers are three and are mounted in a perpendicular fashion to each other.

In some embodiments, the step of establishing the connection between the displacement of the probe and the laser interferometer includes:

and operating a data acquisition module in a Labview upper computer program, reading the data of the laser interferometer by the data acquisition module and feeding the data back to the Labview upper computer, and establishing the relation between the displacement of the probe and the laser interferometer by the upper computer according to the data.

In some embodiments, the laser interferometer senses the displacement variation of the probe in 3 degrees of freedom in a cartesian coordinate system to establish a coordinate variation equation set, and solves a coordinate transformation matrix in the coordinate variation equation by means of least square fitting to obtain a corresponding relationship between the deformation of the probe when detecting the object to be detected and the laser interferometer, so that the deformation of the laser interferometer and the probe can be used to ensure that the probe is in a state of just contacting with the object to be detected, and the accuracy is improved.

In some embodiments, in the step of generating a point set on the feature plane by using a minimum interpolation method, and taking the point set as a sampling point for automatic dotting, the method specifically includes:

and generating a point set on the characteristic surface by using Matlab software and adopting a minimum interpolation method, and taking the point set as a sampling point for automatic dotting.

In some embodiments, the step of completing the dotting operation on the plane of the measured object according to the sampling point specifically includes:

and the Labview upper computer acquires the sampling point, and an automatic dotting module in the Labview upper computer finishes dotting work on the plane to be measured according to the sampling point.

In some embodiments, the step of performing zernike polynomial fitting on the band data to obtain a fitted wave surface, further obtaining PV and RMS values, and completing analysis on the wave surface specifically includes:

and a data decoupling module in the Labview upper computer acquires the belt data, decouples the stored belt data points, stores the data points by using a TMS file, and then performs zernike polynomial fitting to obtain a fitted wave surface, further obtain PV and RMS values, and finish the analysis of the surface shape.

The technical scheme adopted by the application has the following effects:

according to the control method for the CMM system, laser emitted by a plurality of laser interferometers is converged at the probe, the relation between the displacement of the probe and the laser interferometers is established, the surface shape characteristics of a measured object are analyzed, corresponding interferometer displacement is obtained through dotting of a three-coordinate probe, so that characteristic points on a characteristic surface are obtained, characteristic fitting is carried out in a least square fitting mode by adopting a minimum interpolation method to generate a point set on the characteristic surface, the point set is used as a sampling point for automatic dotting, dotting work on the plane of the measured object is completed according to the sampling point, zernike polynomial fitting is carried out on strip data, a fitted wave surface is obtained, PV and RMS values are further obtained, analysis on the surface shape is completed, the control method for the CMM system effectively analyzes and determines the surface shape of the measured object at a nanometer level, the precision requirement of the motion platform is reduced by combining the laser interferometer and the probe, and the precision of the measured object is ensured; and moreover, the optical path of the interferometer is intersected with the probe, so that Abbe errors are well avoided.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments of the present invention or in the description of the prior art will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a flowchart illustrating steps of a control method for a CMM system according to an embodiment of the present invention.

Fig. 2 is a schematic structural diagram of a CMM system according to an embodiment of the present invention.

Figure 3 is a schematic diagram of another CMM system configuration provided by embodiments of the invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "horizontal", "inside", "outside", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments.

Referring to fig. 1, a flowchart of steps of a control method for a CMM system according to embodiment 1 of the present application includes the following steps:

step S110: providing a probe and a plurality of laser interferometers arranged around the probe, wherein laser emitted by the laser interferometers is converged at the probe.

Referring to fig. 2 and fig. 3, a schematic structural diagram of a CMM system provided by the embodiment of the present application includes a frame 110, a probe 120 fixed in the frame, a plurality of laser interferometers 130 disposed around the probe 120, and a measured object 140 located right below the probe 120, where the measured object 140 is disposed on the XY moving platform 150.

Further, the number of the laser interferometers is three, and the laser interferometers are installed in a mutually perpendicular manner.

As can be understood, the Abbe errors can be well avoided because the laser beams emitted by the plurality of laser interferometers are converged at the probe; and at the same time, because the laser interferometer is used as a basic coordinate system of the CMM system, the situation that the interferometers are perpendicular to each other should be met.

Step S120: and establishing a relation between the displacement of the probe and the laser interferometer.

In some embodiments, the step of establishing the connection between the displacement of the probe and the laser interferometer includes:

and operating a data acquisition module in a Labview upper computer program, reading the data of the laser interferometer by the data acquisition module and feeding the data back to the Labview upper computer, establishing the relation between the displacement of the probe and the laser interferometer by the upper computer according to the data, establishing the relation between the displacement of the probe and the laser interferometer by the Labview upper computer according to the data, and electrically connecting the laser interferometer and the probe by the Labview upper computer.

Specifically, the laser interferometer senses the displacement variation of the probe in 3 degrees of freedom in a Cartesian coordinate system to establish a coordinate variation equation set, and solves a coordinate transformation matrix in the coordinate variation equation in a least square fitting mode to further obtain the corresponding relation between the deformation of the probe when detecting the object to be detected and the laser interferometer, so that the deformation of the laser interferometer and the probe can be used for ensuring that the probe is in a state of just contacting with the object to be detected, and the precision is improved.

Step S130: analyzing the surface shape characteristics of the measured object, dotting through the probe to obtain corresponding interferometer displacement so as to obtain characteristic points on the characteristic surface, and performing characteristic fitting through a least square method fitting mode.

Furthermore, the surface shape characteristics of the measured object comprise a circle, a sphere, a plane and the like.

Step S140: and generating a point set on the characteristic surface by adopting a minimum interpolation method, and taking the point set as an automatic dotting sampling point.

In some embodiments, in the step of generating a point set on the feature plane by using a minimum interpolation method, and taking the point set as a sampling point for automatic dotting, the method specifically includes:

and generating a point set on the characteristic surface by using Matlab software and adopting a minimum interpolation method, and taking the point set as a sampling point for automatic dotting.

Step S150: and finishing the dotting work on the plane of the measured object according to the sampling points.

In some embodiments, the step of completing the dotting operation on the plane of the measured object according to the sampling point specifically includes:

and the Labview upper computer acquires the sampling point, and an automatic dotting module in the Labview upper computer finishes dotting work on the plane to be measured according to the sampling point.

Step S160: and (4) performing zernike polynomial fitting on the point set obtained by the dotting work in the step to obtain a fitted wave surface, further obtaining PV and RMS values, and completing the analysis of the surface shape.

Specifically, a data decoupling module in the Labview upper computer acquires the belt data, stored belt data points are decoupled, stored by a TMS file, and subjected to zernike polynomial fitting to obtain a fitted wave surface, so that PV and RMS values are obtained, and surface shape analysis is completed.

According to the control method for the CMM system, laser emitted by a plurality of laser interferometers is converged at the probe, the relation between the displacement of the probe and the laser interferometers is established, the surface shape characteristics of a measured object are analyzed, corresponding interferometer displacement is obtained through dotting of a three-coordinate probe, so that characteristic points on a characteristic surface are obtained, characteristic fitting is carried out in a least square fitting mode by adopting a minimum interpolation method to generate a point set on the characteristic surface, the point set is used as a sampling point for automatic dotting, dotting work on the plane of the measured object is completed according to the sampling point, zernike polynomial fitting is carried out on strip data, a fitted wave surface is obtained, PV and RMS values are further obtained, analysis on the surface shape is completed, the control method for the CMM system effectively analyzes and determines the surface shape of the measured object at a nanometer level, the precision requirement of the motion platform is reduced by combining the laser interferometer and the probe, and the precision of the measured object is ensured; and moreover, the optical path of the interferometer is intersected with the probe, so that Abbe errors are well avoided.

The above are merely examples of the present application and are not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.