CN-122015921-A - Two-dimensional correction method for photoelectric coding disc of translation and rotation platform

CN122015921ACN 122015921 ACN122015921 ACN 122015921ACN-122015921-A

Abstract

The invention discloses a two-dimensional correction method for a photoelectric coding disc of a translation and rotation platform. The invention relates to the technical field of engineering measurement, and aims to solve the problem that errors generated in the vertical direction of a photoelectric coding disc of a translation and rotation platform cannot be compensated in the prior art. The invention collects the coding array image and the precise measuring facula image on the photoelectric coding disc through the camera. And identifying the coarse-precision absolute position according to the coded array image. And extracting the center of gravity of the light spot based on the light spot image, and calculating the column pixel variation of the moving direction to obtain accurate displacement or angle. And calculating the line pixel variation in the vertical movement direction, and determining the shaft movement and pitching error amount. And compensating and correcting the positioning result by utilizing the error quantity. The invention not only can accurately measure the position displacement or angle in the motion direction, but also can accurately measure the translational or rotational plane normal position jitter and pitching jitter values, thereby compensating the positioning error caused by the jitter values.

Inventors

YUE KAIDUAN
LI SHI
YU BO

Assignees

西安华腾光电有限责任公司

Dates

Publication Date: 20260512
Application Date: 20260113

Claims (8)

1. The two-dimensional correction method of the photoelectric coding disc of the translation and rotation platform is characterized by comprising the following steps of: The method comprises the steps of firstly, obtaining a coding array image and a precise measurement light spot image of a photoelectric coding disc, wherein two cameras are symmetrically fixed on a rotating device or a translation device through a rotating shaft, and the photoelectric coding disc is fixed on a fixed frame; Step two, identifying coarse-precision absolute position scale values of rotation angles or translational displacements according to the coding array image; Extracting the column pixel change quantity of the light spot gravity center in the rotation displacement direction through a gravity center algorithm according to the precision measurement light spot image, subdividing the coarse precision absolute position scale value into measurement precision of one-half of the total number of the camera column pixels, and calculating the rotation angle or translation precision displacement by combining with the radius of the photoelectric coding disc; Extracting the line pixel change quantity of the light spot gravity center in the direction perpendicular to the rotary displacement direction through a gravity center algorithm according to the precision measurement light spot image, and calculating the axis serial movement error quantity and the axis pitching error quantity of the translation rotary platform by combining the camera pixel size, the lens imaging magnification factor and the radius of the photoelectric coding disc; And fifthly, compensating the rotation angle or the translational accurate displacement in the third step by utilizing the shaft serial movement error amount and the shaft pitching error amount.
2. The two-dimensional correction method for the translation and rotation platform photoelectric coding disc according to claim 1 is characterized in that in the first step, the coding array codes by utilizing preset system values of spectrum colors, the photoelectric coding disc is divided into evenly distributed 360 equal parts, three-color LEDs are used as a group of light sources to form a light source group, a color map is set according to requirements, and color combinations of each group of light sources in a circular coding ring are planned according to the preset system values, so that absolute position coarse scale values are formed.
3. The two-dimensional correction method for the photoelectric coding disc of the translation and rotation platform is characterized in that in the first step, the coding array codes by means of the size of light spots, the light spots with different sizes are transmitted light spots or diffuse reflection light spots, the size of the calculated light spots in the collected image of a camera is coded, the light spot size combination is used for being any system, under the decimal condition, two light spots form 0-99, three light spots form 0-999, four light spots form 0-9999 and the like, coding combination in a measurement range is completed, and therefore an absolute position coarse scale value is formed.
4. The method for two-dimensional correction of a translation and rotation platform photoelectric coding disc according to claim 1, wherein in the second step, an independent large-field camera is adopted to separately identify the coding array image.
5. The method for two-dimensional correction of a translation and rotation platform photoelectric coding disc according to claim 1, wherein in the second step, an independent high-speed color recognition detector is adopted to separately recognize the coding array image.
6. The method for two-dimensional correction of a translation rotation platform photoelectric encoding disk according to claim 1, wherein in the third step, the rotation angle is calculated according to the following formula: Wherein, the In order for the angle of rotation to be a function of, For the number of column pixel variations of the center of gravity of the light spot in the rotational displacement direction, Is the radius of the photoelectric coding disc.
7. The method for two-dimensional correction of a translation rotation platform photoelectric encoder according to claim 1, wherein in the fourth step, the shaft-tandem error amount and the shaft-pitch error amount are calculated according to the following formulas: = = = μ/ = μ/ Wherein, the Pitch error amount for translation rotation platform shaft; The amount of translational rotation platform shaft serial motion error; the radius of the photoelectric coding disc is; The pixel quantity of the right camera is the line quantity of change; The pixel number of the left camera is the line variation; is the light spot of the right camera the corresponding size of the single pixel; Is the spot of the left camera the corresponding size of the single pixel; imaging magnification factors for the light spots of the right camera lens; And imaging magnification times of light spots of a left camera lens are shown, and mu is the pixel size.
8. The two-dimensional correction method of a translation rotation platform photoelectric coding disc according to claim 1, wherein in the fifth step, the vertical compensation amount is as follows: Wherein, the For the amount of vertical compensation, To translate the rotational stage shaft by an amount of error, For the radius of the photoelectric encoding disk, Is the amount of translational and rotational platform shaft pitch error.

Description

Two-dimensional correction method for photoelectric coding disc of translation and rotation platform Technical Field The invention relates to the technical field of engineering measurement, in particular to a two-dimensional correction method for a photoelectric coding disc of a translation and rotation platform. Background In the field of precision engineering measurement, the positioning precision of the translation rotating platform directly influences the overall performance of the equipment, and the photoelectric coding disc is used as a core component for realizing high-precision position feedback, and the measurement capability of the photoelectric coding disc is critical to the control effect of the translation rotating platform. Currently, mainstream photoelectric encoding discs, such as incremental encoders and absolute encoders, face a number of bottlenecks affecting accuracy in practical applications. For example, machining accuracy causes offset errors in the vertical direction when the translational rotary platform is in operation, or vibration when the motor is in operation causes radial runout of the photoelectric encoding disk, resulting in offset readings. The improvement of the subdivision accuracy of the moire fringes of the circular grating is limited by the grating linear density and the layout difficulty of multiple photosensitive elements, and if the absolute encoder improves the resolution by increasing the number of bits, the manufacturing complexity and the error risk are greatly improved. The traditional photoelectric coding disc can usually finish one-dimensional high-precision positioning measurement and cannot perform vertical runout and radial runout. Therefore, it is necessary to propose a two-dimensional correction method for the translation and rotation platform photoelectric coding disc to solve the above-mentioned problems. Disclosure of Invention The invention aims to provide a two-dimensional correction method for a translation and rotation platform photoelectric coding disc, which aims to solve the problem that errors generated in the vertical direction of the translation and rotation platform photoelectric coding disc cannot be compensated in the prior art. The invention provides a two-dimensional correction method of a translation and rotation platform photoelectric coding disc, which comprises the following steps: The method comprises the steps of firstly, obtaining a coding array image and a precise measurement light spot image of a photoelectric coding disc, wherein two cameras are symmetrically fixed on a rotating device or a translation device through a rotating shaft, and the photoelectric coding disc is fixed on a fixed frame; Step two, identifying coarse-precision absolute position scale values of rotation angles or translational displacements according to the coding array image; Extracting the column pixel change quantity of the light spot gravity center in the rotation displacement direction through a gravity center algorithm according to the precision measurement light spot image, subdividing the coarse precision absolute position scale value into measurement precision of one-half of the total number of the camera column pixels, and calculating the rotation angle or translation precision displacement by combining with the radius of the photoelectric coding disc; Extracting the line pixel change quantity of the light spot gravity center in the direction perpendicular to the rotary displacement direction through a gravity center algorithm according to the precision measurement light spot image, and calculating the axis serial movement error quantity and the axis pitching error quantity of the translation rotary platform by combining the camera pixel size, the lens imaging magnification factor and the radius of the photoelectric coding disc; And fifthly, compensating the rotation angle or the translational accurate displacement in the third step by utilizing the shaft serial movement error amount and the shaft pitching error amount. In the first step, the coding array codes by utilizing preset system values of spectrum colors, the photoelectric coding disc is divided into 360 equal parts which are uniformly distributed, the three-color LEDs are used as a group of light sources to form a light source group, a color map is set according to requirements, and the color combination of each group of light sources in the circular coding ring is planned according to the preset system values, so that an absolute position coarse scale value is formed. In the first step, the coding array codes by utilizing the size of light spots, codes light spots with different sizes into transmission light spots or diffuse reflection light spots, a camera collects the sizes of calculated light spots in an image to realize coding, the light spots are combined into any system by utilizing the size of the light spots, under the decimal condition, two light spots form 0-99, three light