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CN-122016285-A - Rotating shaft five-degree-of-freedom error synchronous measurement method and device for multi-surface composite white light interference

CN122016285ACN 122016285 ACN122016285 ACN 122016285ACN-122016285-A

Abstract

The invention discloses a rotating shaft five-degree-of-freedom error synchronous measurement method and device for multi-surface composite white light interference, wherein the device comprises a precise rotating shaft (1), a clamp (2), an adjusting unit and a white light interference device, one end of the precise rotating shaft (1) is fixedly connected with one end of the clamp (2), the other end of the clamp (2) is fixedly connected with one end of the adjusting unit, a reference piece (5) is arranged at the other end of the adjusting unit, the white light interference device is positioned right in front of the reference piece (5), the reference piece (5) is provided with three edges, the measurement method comprises the steps of S1, the rotating shaft five-degree-of-freedom motion synchronous measurement is realized based on multi-surface composite white light interference, and the step of S2 is used for measuring device installation error separation. The invention can synchronously calculate the five-degree-of-freedom error motion of the rotating shaft, and provides high-efficiency and accurate technical support for performance evaluation and error compensation of the precise rotating shaft.

Inventors

  • HUANG PENG
  • GE WEI
  • ZHU ZHIWEI

Assignees

  • 南京理工大学

Dates

Publication Date
20260512
Application Date
20260304

Claims (9)

  1. 1. The rotating shaft five-degree-of-freedom error synchronous measurement device for multi-surface composite white light interference is characterized by comprising a precise rotating shaft (1), a clamp (2), an adjusting unit and a white light interference device; One end of the precise rotating shaft (1) is connected with one end of the clamp (2) in an installation mode, the other end of the clamp (2) is fixedly connected with one end of the adjusting unit, the other end of the adjusting unit is provided with a reference piece (5), the white light interference device is located right in front of the reference piece (5), and the reference piece (5) is provided with three prismatic surfaces.
  2. 2. The rotating shaft five-degree-of-freedom error synchronous measurement device based on multi-surface composite white light interference according to claim 1, wherein the white light interference device comprises a micro interference objective lens (6), a tube lens (7), a white light source (8) and an industrial camera (9), wherein one end of the tube lens (7) is provided with the micro interference objective lens (6), the other end of the tube lens is connected with the industrial camera (9), the industrial camera (9) realizes sampling control and data transmission through a connecting computer, and one side of the tube lens (7) is provided with an opening, and the white light source (8) is arranged.
  3. 3. The rotating shaft five-degree-of-freedom error synchronous measurement device of multi-surface composite white light interference according to claim 2, wherein the adjustment unit comprises a double-shaft leveling frame (3) and a double-shaft displacement fine adjustment table (4), one end of the double-shaft leveling frame (3) is fixedly connected with the clamp (2), the other end of the double-shaft leveling frame is fixedly connected with the double-shaft displacement fine adjustment table (4), the reference piece (5) is pressed in the double-shaft displacement fine adjustment table (4), the double-shaft leveling frame (3) can adjust the inclination angle of two shafts of the reference piece (5) to enable the end face of the reference piece (5) to be parallel to the end face of a main shaft, and the double-shaft displacement fine adjustment table (4) can adjust the two-shaft displacement of the reference piece (5) in the direction perpendicular to the axis of the main shaft.
  4. 4. The rotating shaft five-degree-of-freedom error synchronous measurement device based on multi-surface composite white light interference according to claim 3, wherein the white light source (8) is an LED white light source, and the bottom of the tube mirror (7) is fixed on a two-axis turntable (10) fixed with a workbench.
  5. 5. The synchronous measuring device for five degrees of freedom errors of a rotating shaft based on multi-sided composite white light interferometry according to claim 2, wherein the reference member (5) is a triangular pyramid microstructure having a slope, the pyramid base is a regular triangle with a side length of 632 μm, the pyramid apex is directly above the triangle center of the base, and the height from the base is set to 11 μm.
  6. 6. A measurement method of a rotating shaft five-degree-of-freedom error synchronous measurement device of multi-face composite white light interferometry according to any one of claims 2 to 5, comprising the steps of: Step S1, realizing the synchronous measurement of five-degree-of-freedom motion of a rotating shaft based on multi-surface composite white light interference; and S2, separating installation errors of the measuring device.
  7. 7. The method according to claim 6, wherein the step S1 is specifically: The relative positions of the reference piece (5) and the white light interference device are adjusted before measurement, so that interference fringes are contained on three edges of an image acquired by the industrial camera (9), the precise rotating shaft (1) rotates at a set rotating speed, and the industrial camera (9) acquires images at different moments; Providing a reference element (5) with three facets passing through an imaginary plane parallel to the reference mirror in the interference objective (6) and having equal optical path differences, the imaginary plane being referred to as the peak coherence plane (Peak Coherence Plane, PCP), and the imaginary plane coinciding with the focal plane of the interference objective (6) to enable projection of an image onto the imaginary plane, defining an image coordinate system on the PCP, wherein Shaft and method for producing the same The shaft is located on the PCP and, The axis is along the optical axis of the interference objective lens (6), and the origin is the center of the image; Sampling and calculating white light interference fringes of a single frame image, namely extracting bright fringe areas in the image by threshold segmentation through an image processing method, performing fringe straight line fitting based on segmentation results, calculating straight line expressions of each fringe in the image, calculating intersecting positions and central positions, finally segmenting the multi-face composite white light interference fringe image into a plurality of independent sub-images according to the intersecting positions and the central positions, wherein each sub-image comprises complete information of a single group of interference fringes, and then separately resolving each group of interference fringes to obtain the position expressions of corresponding prism faces of the sub-images in an image coordinate system: (1) Wherein the method comprises the steps of The normal vector of the calculated prism surface under the image coordinate system is represented by g, which is an expression constant term; for each group of interference fringes after segmentation, the direction of the zero-order bright fringes and the normal direction thereof are obtained by threshold segmentation, edge detection and straight line fitting methods in image processing, and a certain point on the zero-order bright fringes is lengthened to two sides of the zero-order bright fringes along the normal to be fixed as a line segment By image processing method, on-line segment Gray level profile is made in the range to obtain a group of actual interference curve sequences, and then line segments are formed Translating a small distance along the zero-order bright stripe direction, and setting a new line segment Then, a gray level profile is made to obtain a group of new actual interference curve sequences, and the actual interference curve sequences are repeated for a plurality of times to obtain a plurality of groups of actual interference curve sequences; Analyzing the actual interference curve sequences of the groups by using a Hilbert transformation method, accurately extracting the zero optical path difference positions, recording the corresponding pixel positions, and finally accurately fitting a straight line L expression of the zero-order bright stripes in an image coordinate system by using a least square fitting method, wherein the straight line L is the intersection line of the required prism surface and the PCP: (2) Due to points on the edge surface of the reference member The corresponding Z values are different, so that interference fringe projection is generated on the prism surface, and the white light interference light intensity curve on the Z axis is calibrated through vertical scanning, so that the expression of the white light interference light intensity curve is as follows: (3) Wherein the method comprises the steps of As a function of the carrier frequency, For the initial phase position, Is the width of the gaussian function, is used to describe the white light fringe pattern envelope function, z is the height value, Is the light intensity of the corresponding height; Converting the pixel scale of an image coordinate system into the length scale of an actual coordinate system, taking a light intensity peak point as an original point, and performing gray profile on the normal line of the precisely solved straight line L to obtain an actual interference curve sequence, wherein the actual distance between each point in the sequence and the peak point Normalized to the abscissa, the actual interference curve sequence composed of N discrete points is obtained ; Then obtaining the actual interference curve sequence by peak detection and curve fitting method Three-level bright stripe width of (2) And three-level bright stripe width of white light interference light intensity curve I (z) Obtaining the measured plane normal slope m of the corresponding prism face: (4) From the faceted position expression of equation 1, the vector direction is normal to line L Is the horizontal unit vector of (2) Wherein The corresponding prism position expression is along the normal vector direction I.e. the slope of the theoretical plane normal, obtained by implicit function derivation: (5) Will be Substitution to obtain: (6) Theoretical plane normal slope of facets From equation 6, m is the measured plane normal slope, and the two are equal to each other, and the coefficient is obtained : (7) Obtaining the coefficients in the edge position expression Determining the position expressions of three edges of the reference piece in an image coordinate system respectively through three groups of white light interference fringes, and normalizing the three edges to be in the following form: (8) Wherein, the Is the first The component of the normal vector of the facets, Fitting constant terms of the ith prism position expression in the formula 2; the position of the cone top under the image coordinate system at any moment is uniquely determined by an equation set consisting of the simultaneous three prism surface position expressions Cone top coordinates obtained by resolving first frame image Determining 3-DOF relative movement of reference member at k-th frame image moment ; The normal vector of three prism surfaces under the image coordinate system at a certain moment is known as Assume that As the normal vector of the three facets of the reference element at the corresponding position of the first frame image, taking the normal vector as a reference, a rotation matrix R exists at the moment, so that the rotation matrix R rotates the normal vector of each facet at the reference position under the image coordinate system to the normal vector of the facet at a certain moment: (9) Equation 9 solves the rotation matrix R by the Kabsch algorithm, and the change of the posture of the reference element can be described by the sum vector of the normal vectors of the three prism surfaces, which is the sum vector of the first frame As a reference, the sum vector of the reference parts after the relative rotation of the k frame image moment in the image coordinate system is obtained through calculation of a rotation matrix R In the process of obtaining And And then, only determining the five-degree-of-freedom relative motion of the rotating shaft in space when the k frame of image is obtained through the reference piece.
  8. 8. The measurement method according to claim 7, wherein the precision spindle (1) is rotated at 8.33rpm in step S1, and the industrial camera (9) captures images at different moments in time at a frame rate of 50 fps.
  9. 9. The measurement method according to claim 7, wherein the step S2 is specifically: Separating the system errors generated by installation, including in-plane motion error separation and out-of-plane motion error separation, contained in the five-degree-of-freedom relative motion results obtained in the step S1; The in-plane motion error measurement and error separation are specifically that the movement track of the cone vertex of the reference piece calculated under the image coordinate system is a circle with the rotation center of the main shaft as the center of a circle by taking the position of the reference piece at the beginning of data recording as a benchmark, and the relative movement is in the kth frame Including installation of an eccentric motion component caused by eccentricity; decomposing motion to image coordinate system Shaft and method for producing the same Axial direction, in the kth frame image, the edge of the rotation axis Error in radial motion of shaft And a rim Error in radial motion of shaft Expressed as: (10) Wherein, the Indicating the equivalent eccentric radius, Represents an initial phase, ω is a rotation angle frequency, Representing the position of the spindle rotation center in the image coordinate system; The out-of-plane motion error measurement and error separation are specifically that vectors measured in the kth frame due to installation errors during rotation of the spindle The motion track in the space is a cone taking the rotation axis of the rotating shaft as the center, and the rotation axis of the rotating shaft and the image coordinate system The axes also have two coordinate systems respectively around the image Shaft and method for producing the same Static deflection angle of shaft And The deflection angle reflects the installation error between the axis of the rotating shaft and the optical axis of the white light interference device; from the sum vector of the kth frame Obtaining the winding Shaft and method for producing the same The inclination of the shaft is: (11) Wherein the method comprises the steps of Sum vector calculated for kth frame image Is used for the control of the axis component of the (c), Is wound around The inclination angle of the shaft, Is wound around Inclination angle of the shaft; Resolving the tilting movement of the reference member to Shaft and method for producing the same An axis around which the rotation axis is wound in the k-th frame gray scale image Error in tilting motion of shaft And winding Error in tilting motion of shaft Expressed as: (12) Wherein, the Represents a fixed offset angle of the reference member axis and the rotation axis of the rotating shaft, ω is a rotation angle frequency, The initial phase is indicated as such, And Representing a static deflection angle between the rotation axis of the rotating shaft and the Z axis of the image coordinate system; The axial error motion is directly obtained as: (13) Wherein the method comprises the steps of For the moment of the kth frame of image, a relative movement along the Z-axis.

Description

Rotating shaft five-degree-of-freedom error synchronous measurement method and device for multi-surface composite white light interference Technical Field The invention belongs to the technical field of optical precision measurement, and particularly relates to a rotating shaft five-degree-of-freedom error synchronous measurement method and device for multi-surface composite white light interference. Background The precision rotating shaft is a critical part of the machine tool, the precision requirement is higher and higher, the precision is gradually developed to be more than the micron level, and the precision is developed towards the nanometer level and the sub-nanometer level. In the rotation process, the precise rotating shaft inevitably generates five-degree-of-freedom motion errors, including in-plane radial motion and out-of-plane axial and tilting motion. These errors can directly affect the microscopic morphology and the molding precision of the final product, and improving the motion precision of the precise rotating shaft is important to ensure the machining precision. Some students focus on measurement of single-direction motion errors, and methods are proposed, such as an optical measurement method based on laser collimation, for measuring spindle radial errors by changing reflected or refracted laser beams, a machine vision method is adopted for identifying radial motions by calculating two-dimensional images of a test target, a circular grating is matched with an autocollimator for detecting spindle radial error detection, and an industrial camera and a self-made standard device are adopted for realizing high-speed spindle dynamic radial error measurement based on track tracking. Although the device is relatively simple, the method is difficult to reflect the coupling relation among the multi-degree-of-freedom errors, and has limitation in practical application. In order to comprehensively evaluate the performance of the rotating shaft, multi-degree-of-freedom synchronous measurement is necessarily required. To cope with this problem, many students try to acquire error information in a plurality of directions at the same time by combining a plurality of sensors. For example, the most common method is that a dual standard ball is combined with five capacitance sensors to measure the synchronous radial and axial error motions of a main shaft, a laser Doppler vibrometer is used for measuring the radial error of a precise main shaft, the radial and oblique error motions are obtained by identifying the position change of a reflected or refracted laser spot, but the axial motion is difficult to directly measure, so that an additional axial sensor is usually adopted, some students use heterodyne interference to measure the axial motion, and although the methods possibly have different devices, the potential mechanism of the method causes the defect that the measurement of multiple degrees of freedom is often finished through mutually independent parts, the device for simultaneously finishing the measurement of the five degrees of freedom motion errors is quite complex, and the requirement on the accuracy of the installation position of the sensor is extremely high because of the high-accuracy clamp. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a rotating shaft five-degree-of-freedom error synchronous measurement method and device for multi-surface composite white light interference, which realize the 5DOF error motion synchronous measurement of a precise rotating shaft. The technical scheme adopted by the invention is as follows: a rotating shaft five-degree-of-freedom error synchronous measurement device of multi-surface composite white light interference comprises a precise rotating shaft, a clamp, an adjusting unit and a white light interference device; one end of the precise rotating shaft is connected with one end of the clamp in an installation mode, the other end of the clamp is fixedly connected with one end of the adjusting unit, a reference piece is installed at the other end of the adjusting unit, the white light interference device is located right in front of the reference piece, and the reference piece is provided with three edges. Further, the white light interference device comprises a micro interference objective, a tube lens, a white light source and an industrial camera, wherein the micro interference objective is arranged at one end of the tube lens, the other end of the tube lens is connected with the industrial camera, the industrial camera realizes sampling control and data transmission through a connecting computer, and the white light source is arranged at an opening at one side of the tube lens. Further, the adjusting unit comprises a double-shaft leveling frame and a double-shaft displacement fine adjustment table, one end of the double-shaft leveling frame is fixedly connected with the clamp, the other end of the double-shaft le