Shafting angle measurement error real-time self-compensation metering rotary table based on circular grating encoder

Abstract

The utility model discloses a shafting angle measurement error real-time self-compensation metering rotary table based on a circular grating encoder, which relates to the field of equipment precision measurement, and is characterized by comprising a rotary shafting, a data acquisition device, a circular grating encoder, a data processing module and a driver, the data acquisition device, the circular grating encoder and the driver are all mounted on the rotary shaft system; the data processing module is connected with the data acquisition device and is used for analyzing the radial run-out error data acquired by the data acquisition device; and the data processing module is connected with the driver through a cable and is used for controlling the rotation shaft system to rotate. The influence of shafting deflection caused by shaking, inclination and other factors caused by shafting rotation of the rotary table on the angle measurement precision is reduced, real-time measurement and compensation of the angle measurement error of the metering rotary table can be completed, and the angle measurement error compensation efficiency is remarkably improved.

Description

Technical Field

[0001] The utility model relates to the field of precision measurement of equipment, and more specifically, to a real-time self-compensation metrological turntable for shaft system angle measurement errors based on a circular grating encoder. Background Art

[0002] The metrology turntable is a device used for high-precision angular displacement measurement and calibration. It has the advantages of high resolution, high precision, and high response speed. It has been widely used in mechanical manufacturing, aerospace, precision instruments and other fields. And with the development of science and technology, the demand for the angular measurement accuracy of such equipment is getting higher and higher, which puts higher requirements on the measurement accuracy of the metrology turntable. The circular grating encoder is the core component used to achieve angle measurement and feedback in the metrology turntable, but in actual engineering applications, it is limited by factors such as grating manufacturing errors and shaft component processing errors. The angular measurement performance of the circular grating encoder is difficult to achieve ideal results. Therefore, in order to improve the angular measurement accuracy of the metrology turntable, it is usually necessary to compensate for the angular measurement error of the metrology turntable.

[0003] Angular measurement error compensation is usually the last link in the development of a metrological turntable, and its compensation effect will determine the final angular measurement accuracy of the turntable. At present, in the prior art, the commonly used method in the industry to compensate for the angular measurement error of the metrological turntable is to use a polyhedron with an autocollimator and measure it through the full combination method. Although this method can achieve very high calibration accuracy, it also has many problems, such as limited compensation data points, extremely low test efficiency, extremely high environmental requirements, and can only calibrate static positions. In addition, the angular measurement error can also be measured by angle measuring instruments such as laser goniometers. These methods have improved test efficiency, but the measurement accuracy is not as high as the full combination method and the stability is poor. Secondly, as the use time of the metrological turntable increases, its original compensation parameters may gradually become invalid due to the influence of internal and external factors, and it needs to be regularly calibrated and re-compensated, which is very time-consuming and labor-intensive. Therefore, it is of great significance to study a metrological turntable that can realize real-time self-compensation of the angular measurement error of the shaft system in order to improve the test, calibration, and compensation efficiency of the turntable.

[0004] There are two main methods for achieving self-calibration of the angle measurement accuracy of a metrological turntable in the prior art. Among them, the most common method is the self-calibration method using multiple reading heads based on the principle of equal division and averaging. For example, the symmetrical arrangement of N pairs of reading heads can significantly eliminate angle measurement errors of order N and below. However, if the device wants to eliminate high-order errors, it is necessary to continuously increase the number of installed reading heads, which greatly increases the application cost. At the same time, due to the physical size of the shaft system, the number of reading heads cannot be increased indefinitely. The other method is based on the geometric mapping relationship between the shaft system rotation error and the angle measurement error. By measuring the rotation error of the shaft system, the angle measurement error of the angle measurement error can be accurately measured. This method is rarely used at present, and most of the methods currently use one displacement sensor or three displacement sensors (a group of sensors) to collect the runout data of the equatorial plane of the two standard balls of the calibration rod. When one displacement sensor is used, the runout data collected is difficult to separate the roundness error. When three displacement sensors are used to collect the runout data of the equatorial plane of the two standard balls of the calibration rod, although the collected runout data can separate the roundness error, it cannot overcome the influence of the axis deviation caused by the shaking and tilting caused by the axis rotation of the turntable, which reduces the angle measurement accuracy. And there is no precedent for integrating this method into a metrological turntable to realize real-time self-compensation of the angle measurement accuracy of the metrological turntable. Utility Model Content

[0005] The purpose of the utility model is to provide a real-time self-compensating metrological turntable for shaft system angular measurement errors based on a circular grating encoder. On the one hand, the application measures the rotation angle of the circular grating by installing a dual reading head on the stator of the turntable, which can eliminate the angular measurement error caused by the first-order eccentricity error, thereby improving the angular measurement accuracy to a certain extent. On the other hand, the application measures the rotation error of the two annular inspection surfaces of the double annular inspection rod based on two sets of sensor groups corresponding to each other. According to the radial runout data of the two sections when the shaft system swings, the real-time measurement of the corresponding rotation accuracy of the working section of the circular grating can be achieved, and the angular measurement error can be compensated through the geometric mapping relationship between the rotation error and the angular measurement error, thereby reducing the influence of the shaft system deviation caused by the shaking, tilting and other factors caused by the shaft system rotation of the turntable on the angular measurement accuracy, and can complete the real-time measurement and compensation of the angular measurement error of the metrological turntable, significantly improving the efficiency of angular measurement error compensation.

[0006] The present application provides a real-time self-compensation metrological turntable for shaft system angular measurement errors based on a circular grating encoder, comprising a rotary shaft system, a data acquisition device, a circular grating encoder, a data processing module and a driver;

[0007] The data acquisition device, circular grating encoder and drive are all installed on the rotary shaft system;

[0008] The data processing module is connected to the data acquisition device and is used to analyze the radial runout error data collected by the data acquisition device;

[0009] The data processing module is connected to the driver via a cable and is used to control the rotation of the rotary shaft system.

[0010] In one implementation, the rotating shaft system includes a rotor and a stator;

[0011] The rotor comprises a workbench, an encoder mounting plate, a rotating shaft and a motor which are installed in sequence;

[0012] The stator comprises a top cover, a base, a bearing seat and a reading head mounting seat, wherein the bearing seat is mounted on the base, the reading head mounting seat is mounted on the bearing seat, and the top cover is mounted on the data acquisition device;

[0013] Wherein, the reading head mounting seat is mounted on the encoder mounting plate.

[0014] In one implementation, the data acquisition device includes a sensor bracket, two displacement sensor groups and a double-annular inspection rod;

[0015] The sensor bracket is fixedly mounted on the reading head mounting seat, and the two displacement sensor groups are vertically mounted on the sensor bracket;

[0016] The double-annular inspection rod has two annular inspection surfaces, which are used to cooperate with the displacement sensor group to detect radial runout error data during the rotation process of the shaft system.

[0017] In an implementation, the displacement sensor group includes a plurality of displacement sensors, and the number of mounting interfaces of the sensor bracket matches the number of displacement sensors included in the displacement sensor group.

[0018] In one implementation, the plurality of displacement sensors of the displacement sensor group are evenly arranged at 120° in the circumferential direction of the equatorial plane of the test surface of the double-annular test rod.

[0019] In one implementation, the axes of the multiple displacement sensors of each displacement sensor group are located on the same horizontal plane, and the intersection of the axes of the multiple displacement sensors is located on the axis center of the double-annular test rod on the same horizontal plane.

[0020] In one implementation, the number of the displacement sensors is three.

[0021] In one implementation, the displacement sensor is a capacitive displacement sensor.

[0022] In one implementation, the circular grating encoder includes a circular grating disk and two symmetrically arranged reading heads. The circular grating disk is coaxially mounted with the rotor. The two reading heads are fixedly mounted on the reading head mounting seat for detecting and feeding back the angular information of the rotation of the rotating shaft system.

[0023] Compared with the prior art, the utility model has the following beneficial effects:

[0024] On the one hand, the present application measures the rotation angle of the circular grating by installing a dual reading head on the stator of the turntable, which can eliminate the angular measurement error caused by the first-order eccentricity error, thereby improving the angular measurement accuracy to a certain extent. On the other hand, the present application is based on two sets of sensor groups corresponding to the rotation errors of the two annular inspection surfaces of the double-annular inspection rod. According to the radial runout data of the two sections when the shaft system swings, the real-time measurement of the corresponding rotation accuracy of the working section of the circular grating can be achieved, and the angular measurement error can be compensated through the geometric mapping relationship between the rotation error and the angular measurement error, thereby reducing the influence of the shaft system deviation caused by the shaking, tilting and other factors caused by the shaft system rotation of the turntable on the angular measurement accuracy, and can complete the real-time measurement and compensation of the angular measurement error of the metrology turntable, significantly improving the efficiency of angular measurement error compensation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are used to provide a further understanding of the embodiments of the present utility model, constitute a part of this application, and do not constitute a limitation of the embodiments of the present utility model. In the drawings:

[0026] Figure 1 A schematic diagram of the internal structure of a real-time self-compensation metrological turntable for shaft system angular measurement errors based on a circular grating encoder provided in an embodiment of the present application;

[0027] Figure 2 A schematic cross-sectional structure diagram of a real-time self-compensation metrological turntable for shaft system angular measurement errors based on a circular grating encoder provided in an embodiment of the present application;

[0028] Figure 3 A schematic diagram of the arrangement of three displacement sensors of the sensor group provided in an embodiment of the present application at 120 degrees.

[0029] Marks and corresponding parts names in the attached drawings:

[0030] 1. Sensor bracket; 2. Displacement sensor; 3. Workbench; 4. Double ring test rod; 5. Top cover; 6. Circular grating disk; 7. Reading head; 8. Reading head mounting seat; 9. Encoder mounting plate; 10. Rotating shaft; 11. Bearing seat; 12. Data processing module; 13. Base; 14. Motor; 15. Driver. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the utility model more clearly understood, the utility model is further described in detail below in conjunction with embodiments and drawings. The schematic implementation manner of the utility model and its description are only used to explain the utility model and are not intended to limit the utility model.

[0032] It should be noted that the terms "include" or "may include" used in various embodiments of the present application indicate the presence of the function, operation or element applied for, and do not limit the addition of one or more functions, operations or elements. In addition, as used in various embodiments of the present application, the terms "include", "have" and their cognates are only intended to indicate specific features, numbers, steps, operations, elements, components or a combination of the foregoing items, and should not be understood as first excluding the presence of one or more other features, numbers, steps, operations, elements, components or a combination of the foregoing items or the possibility of adding one or more features, numbers, steps, operations, elements, components or a combination of the foregoing items.

[0033] In various embodiments of the present application, the expression "or" or "at least one of B or / and C" includes any combination or all combinations of the words listed at the same time. For example, the expression "B or C" or "at least one of B or / and C" may include B, may include C, or may include both B and C.

[0034] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0035] Please refer to Figure 1 and Figure 2 , Figure 2 A schematic cross-sectional structure diagram of a real-time self-compensation metrological turntable for shaft system angular measurement error based on a circular grating encoder provided in an embodiment of the present application is shown in FIG. Figure 2 As shown: the turntable includes a rotary shaft system, a data acquisition device, a circular grating encoder, a data processing module and a driver 15; the data acquisition device, the circular grating encoder and the driver are all installed on the rotary shaft system; the data processing module is connected to the data acquisition device for analyzing the radial runout error data collected by the data acquisition device; the data processing module is connected to the driver 15 through a cable for controlling the rotation of the rotary shaft system.

[0036] The working principle of the real-time self-compensation metrological turntable for measuring the angular error of the shaft system provided in this embodiment is as follows: in a real-time self-compensation metrological turntable for measuring the angular error of the shaft system based on a circular grating encoder provided in this application embodiment, on the one hand, two reading heads 7 are installed on the reading head mounting seat 8 of the stator component of the rotating shaft system to measure the rotation angle of the circular grating disk 6, and the influence of the first-order eccentricity error on the angular measurement accuracy can be eliminated by the equal division and averaging technology, thereby improving the angular measurement accuracy. On the other hand, based on the two groups of displacement sensor groups corresponding to the rotation errors of the two annular inspection surfaces of the double annular inspection rod 4 respectively, according to the radial runout data of the two sections when the shaft system swings, the real-time measurement of the corresponding rotation accuracy of the circular grating working section can be realized, and the angular measurement error can be compensated by the geometric mapping relationship between the rotation error and the angular measurement error, thereby reducing the influence of the shaft system deflection caused by the shaking, tilting and other factors caused by the shaft system rotation of the turntable on the angular measurement accuracy, and can complete the real-time measurement and compensation of the angular measurement error of the metrological turntable, and significantly improve the efficiency of angular measurement error compensation.

[0037] Specifically, the rotating shaft system includes a rotor and a stator; the rotor includes a workbench 3, an encoder mounting plate 9, a rotating shaft 10 and a motor 14 installed in sequence; the stator includes a top cover 5, a base 13, a bearing seat 11 and a reading head mounting seat 8, the bearing seat 11 is installed on the base 13, the reading head mounting seat 8 is installed on the bearing seat 11, and the top cover 5 is installed on the data acquisition device; wherein, the reading head mounting seat 8 is installed on the encoder mounting plate 9.

[0038] In this embodiment, the rotary shaft system consists of two parts, the rotor and the stator. The rotor part includes a workbench 3, an encoder mounting plate 9, a rotating shaft 10 and a motor 14 which are installed in sequence, and the installation method can be screw connection. The stator part mainly includes a top cover 5, a base 13, a bearing seat 11 and a reading head mounting seat 8, and the installation method can be screw connection. The rotary shaft system in this embodiment is an air-floating shaft system, but it should be noted that the specific implementation principle of the rotary shaft system is not the focus of the present application, and the rotary shaft system can also be implemented by other structural solutions, and will not have a substantial impact on the results mentioned in the present application, so it will not be described in detail.

[0039] In some embodiments, the data acquisition device includes a sensor bracket 1, two displacement sensor groups and a double-annular inspection rod 4; the sensor bracket 1 is fixedly mounted on a reading head mounting base 8, and the two displacement sensor groups are vertically mounted on the sensor bracket 1; the double-annular inspection rod 4 has two annular inspection surfaces, which are used to cooperate with the displacement sensor group to detect radial runout error data during the shaft system rotation process.

[0040] Specifically, the circular grating encoder in this embodiment includes a circular grating disk 6 and two reading heads 7. The circular grating disk 6 is coaxially mounted with the turntable rotor part. The two reading heads 7 are arranged 180° symmetrically along the shaft system and fixedly mounted on the reading head mounting seat 8 for detecting and feeding back the shaft system rotation angle information.

[0041] In some embodiments, the displacement sensor group includes a plurality of displacement sensors 2 , and the number of mounting interfaces of the sensor bracket 1 matches the number of displacement sensors 2 included in the displacement sensor group.

[0042] In some embodiments, the plurality of displacement sensors 2 of the displacement sensor group are evenly arranged at 120° in the circumferential direction of the equatorial plane of the test surface of the double-annular test rod 4 .

[0043] In some embodiments, the axes of the multiple displacement sensors 2 of each displacement sensor group are located on the same horizontal plane, and the intersection of the axes of the multiple displacement sensors 2 is located on the axis of the double-annular test rod 4 on the same horizontal plane. As a specific embodiment, the number of the displacement sensors 2 is three.

[0044] Specifically, the two displacement sensor groups in this embodiment are divided into an upper group and an lower group, and the number of displacement sensors in each displacement sensor group is three, such as Figure 3 As shown, three displacement sensors 2 of the upper and lower layers are evenly arranged at 120° along the circumferential direction on the equatorial plane of each annular test surface. Of course, four or five displacement sensors 2 can also be arranged, that is, four or five displacement sensors 2 are evenly arranged at 90° and 72° along the circumferential direction on the equatorial plane of each annular test surface. It should be noted that since the two groups of sensors are divided into one group each, the displacement sensors 2 of the two sensor groups are on the same vertical axis on the sensor bracket 1.

[0045] In some embodiments, the displacement sensor 2 is a capacitive displacement sensor.

[0046] Specifically, the capacitive displacement sensor is a non-contact precision measuring instrument. It achieves measurement in a non-contact manner, avoiding wear, damage and errors that may be caused by contact, ensuring the stability and accuracy of the measurement. Of course, the displacement sensor can also use other non-contact displacement sensors, such as spectral confocal displacement sensors.

[0047] In some embodiments, the circular grating encoder includes a circular grating disk 6 and two symmetrically arranged reading heads 7. The circular grating disk 6 is coaxially mounted with the rotor. The two reading heads 7 are fixedly mounted on the reading head mounting base 8 for detecting and feeding back the angular information of the rotation of the rotating shaft system.

[0048] Specifically, with regard to the current angle measurement method of the circular grating disk 6 (the circular grating encoder is a photoelectric conversion device used to measure the rotation angle, and its core is composed of a circular grating disk 6 and a reading head 7), in addition to the system error of the circular grating disk 6 itself, several error sources that have a greater impact on the angle measurement accuracy of the circular grating encoder include the installation eccentricity error of the circular grating disk 6, the geometric error of the rotation axis, the grating ring shape error and environmental interference, etc. Among them, the grating ring shape error and environmental interference can be effectively suppressed by improving the assembly process and controlling the use environment, while the errors caused by factors such as the installation eccentricity error and the geometric error of the rotation axis are often difficult to avoid in practical applications, and these errors have a very significant impact on the angle measurement accuracy. Therefore, it is particularly important to measure and calculate these error parameters through effective means and compensate for the measurement errors. In addition, the eccentricity error that affects the grating angle measurement accuracy includes not only the installation eccentricity error but also the electrical eccentricity error. The electrical eccentricity error is the deviation between the axis center of the circular grating disk 6 and the ideal axis line. It is a manufacturing error of the circular grating disk 6 itself. It is difficult to compensate for it by measuring the rotation error of the shaft system. The best method is to eliminate it by symmetrically arranging multiple reading heads 7. However, due to the physical size of the shaft system and the cost of using the reading heads 7, the number of reading heads 6 cannot be increased indefinitely. Therefore, in this embodiment, two reading heads 7 are symmetrically arranged and installed on the reading head mounting seat 8 of the stator of the metering turntable to measure the rotation angle of the circular grating disk 6, which can eliminate the first-order eccentricity error and improve the angle measurement accuracy. Specifically, the data collected by the two reading heads 7 are averaged by equal division to eliminate the influence of the first-order eccentricity error, and the rotation angle measurement value is obtained. The first-order eccentricity error is mainly caused by the physical installation eccentricity of the circular grating disk 6, the electrical installation eccentricity, and the first-order error in the shaft system rotation accuracy. Therefore, the method of equal division and averaging of the double reading heads 7 still retains the error components of the second order and above in the angle measurement error.

[0049] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the utility model in detail. It should be understood that the above description is only the specific implementation method of the utility model and is not used to limit the protection scope of the utility model. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the utility model should be included in the protection scope of the utility model.

Claims

1. A real-time self-compensation metrological turntable for shaft system angular measurement error based on a circular grating encoder, characterized in that: It includes a rotary shaft system, a data acquisition device, a circular grating encoder, a data processing module and a driver; The data acquisition device, circular grating encoder and drive are all installed on the rotary shaft system; The data processing module is connected to the data acquisition device and is used to analyze the radial runout error data collected by the data acquisition device; The data processing module is connected to the driver via a cable and is used to control the rotation of the rotary shaft system.

2. The real-time self-compensation metrological turntable for shaft system angle measurement error based on circular grating encoder according to claim 1 is characterized in that: The rotating shaft system includes a rotor and a stator; The rotor comprises a workbench, an encoder mounting plate, a rotating shaft and a motor which are installed in sequence; The stator comprises a top cover, a base, a bearing seat and a reading head mounting seat, wherein the bearing seat is mounted on the base, the reading head mounting seat is mounted on the bearing seat, and the top cover is mounted on the data acquisition device; Wherein, the reading head mounting seat is mounted on the encoder mounting plate.

3. The real-time self-compensation metrological turntable for shaft system angle measurement error based on circular grating encoder according to claim 2 is characterized in that: The data acquisition device includes a sensor bracket, two displacement sensor groups and a double-annular inspection rod; The sensor bracket is fixedly mounted on the reading head mounting seat, and the two displacement sensor groups are vertically mounted on the sensor bracket; The double-annular inspection rod has two annular inspection surfaces, which are used to cooperate with the displacement sensor group to detect radial runout error data during the rotation process of the shaft system.

4. The real-time self-compensation metrological turntable for shaft system angle measurement error based on circular grating encoder according to claim 3 is characterized in that: The displacement sensor group includes a plurality of displacement sensors, and the number of mounting interfaces of the sensor bracket matches the number of displacement sensors included in the displacement sensor group.

5. The real-time self-compensation metrological turntable for shaft system angle measurement error based on circular grating encoder according to claim 4 is characterized in that: The plurality of displacement sensors of the displacement sensor group are evenly arranged at 120° in the circumferential direction of the equatorial plane of the inspection surface of the double-annular inspection rod.

6. The real-time self-compensation metrological turntable for shaft system angle measurement error based on circular grating encoder according to claim 5 is characterized in that: The axes of the multiple displacement sensors of each displacement sensor group are located on the same horizontal plane, and the intersection of the axes of the multiple displacement sensors is located on the axis center of the double-annular inspection rod on the same horizontal plane.

7. The real-time self-compensation metrological turntable for shaft system angle measurement error based on circular grating encoder according to claim 6 is characterized in that: The number of the displacement sensors is three.

8. The real-time self-compensation metrological turntable for shaft system angle measurement error based on circular grating encoder according to claim 7 is characterized in that: The displacement sensor is a capacitive displacement sensor.

9. The real-time self-compensation metrological turntable for shaft system angle measurement error based on circular grating encoder according to claim 2 is characterized in that: The circular grating encoder includes a circular grating disk and two symmetrically arranged reading heads. The circular grating disk is coaxially mounted with the rotor. The two reading heads are fixedly mounted on the reading head mounting seat for detecting and feeding back the angular information of the rotation of the rotating shaft system.

Images