Split inertial measurement device and method for linear axis error detection of machine tools

Abstract

The present application belongs to the technical field of precision testing of numerical control machine tools, and discloses a split inertia measuring device and method for detecting linear shaft errors of machine tools. The split inertia measuring device mainly comprises a bottom base plate, an orthogonal three-axis zero positioner, a single-axis inertia sensor and an integrated data acquisition module. The single-axis inertia sensor is sequentially assembled to X, Y and Z three-direction reference surfaces, combined with static calibration and standard motion trajectory measurement, a plurality of sets of inertia data are obtained, and coordinate registration and pose solution are realized through data fusion, so that the positioning error, straightness error and angle deviation of the linear shaft of the machine tool are obtained. The split inertia measuring device adopts a split structure and sensor multiplexing design, avoids complex optical alignment and multi-sensor configuration, is compact in structure and convenient to install; combined with wireless data acquisition and magnetic attraction fixing mode, six-dimensional geometric error detection can be efficiently completed on the machine tool site, hardware investment is reduced, and measurement applicability and popularization value are improved.

Description

Technical Field

[0001] This invention belongs to the field of CNC machine tool accuracy testing technology, specifically relating to a split inertial measurement device and method for detecting linear axis errors in machine tools. Background Technology

[0002] Machine tool geometric error measurement is a key technology for ensuring machining accuracy, and its measurement efficiency directly affects the debugging cycle of overall machine accuracy assessment and compensation. However, existing measurement technologies generally face the problem of balancing accuracy, efficiency, and economy. For example, while single-degree-of-freedom laser interferometers are low-cost, they require repeated light adjustments, leading to cumbersome operation and long measurement cycles; while multi-degree-of-freedom laser interferometers can improve measurement efficiency, their high equipment cost limits their widespread application. This technological bottleneck has resulted in machine tool accuracy maintenance being characterized by high investment and low efficiency, failing to meet the demands of modern manufacturing for rapid, economical, and high-precision testing, and hindering the improvement of enterprise production efficiency and the optimization of machine tool maintenance costs. Therefore, there is an urgent need to develop a new type of rapid on-machine measurement device that can achieve efficient and low-cost geometric error detection while ensuring measurement accuracy.

[0003] Currently, domestic research has been conducted on machine tool geometric error measurement devices. In 2015, Zhou Xiangdong et al. from Huazhong University of Science and Technology disclosed a continuous measurement device for the geometric error of a five-axis linkage machine tool rotary axis in patent CN204893581U. This device establishes a mapping relationship for positional deviations by setting three non-collinear calibration balls to achieve continuous sampling and detection. In 2018, Wang Yongqing et al. from Dalian University of Technology disclosed a rapid detection method for the rotational angle error of a CNC machine tool linear axis in patent CN108362493A. This method uses a gyroscope and accelerometer to measure the deflection angle of the linear axis during uniform motion, and then calculates the pitch angle error, yaw angle error, and roll angle error of the linear axis. In 2021, Wu Shi et al. from Harbin University of Science and Technology disclosed an on-machine detection device for the geometric error of a five-axis machine tool rotary axis and an error field prediction method in patent CN113587870A. This method rapidly detects various geometric errors of the rotary axis through online measurement using a contact-triggered probe. In 2025, Qi Xiaojin et al. from the Beijing Institute of Computer Technology and Applications disclosed a modular inertial measurement device in patent CN120609352A, which can realize the modularization of inertial measurement components and facilitate the assembly of the measurement device.

[0004] Analysis of existing machine tool geometric error measurement devices reveals the following: 1. Existing machine tool error measurement devices are complex to install and calibrate, relying heavily on optical equipment and requiring fixed base stations. Measurements are easily affected by obstructions from moving machine tool parts, often necessitating repeated adjustments and reinstallation, making it difficult to meet the demands of rapid on-machine testing. 2. Existing inertial measurement units typically require multiple sensors to achieve full-attitude measurement, increasing manufacturing costs. 3. Existing devices mostly employ wired power supply and data transmission methods, which are insufficient for meeting the on-machine measurement requirements of large gantry milling machines and other large machine-scale applications. Furthermore, the use of clamps for fixing and the limited application of magnetic fixing methods result in insufficient ease of installation and operation. Summary of the Invention

[0005] The purpose of this invention is to address the problems of existing machine tool geometric error measurement devices, such as complex installation, reliance on optical base stations, numerous sensors, cumbersome wiring, and inconvenient installation methods. The invention proposes a split inertial measurement device for detecting linear axis errors in machine tools, which simplifies the structure, facilitates installation, reduces costs, and enables rapid on-machine measurement.

[0006] The technical solution of the present invention:

[0007] A split inertial measurement device for detecting linear axis errors in machine tools includes a bottom base plate, an X-axis vertical base plate, a Y-axis vertical base plate, an X-axis zero-point positioner mother plate, a Y-axis zero-point positioner mother plate, a Z-axis zero-point positioner mother plate, a zero-point positioner male plate, a single-axis inertial sensor, an integrated data acquisition module, and a magnetic base.

[0008] Four magnetic bases are provided below the bottom base plate for fixing the split inertial measurement unit to or removing it from the machine tool worktable. X-axis and Y-axis vertical base plates are vertically mounted on the bottom base plate. The X-axis, Y-axis, and Z-axis zero-point positioner mother plates are fixed to the X-axis, Y-axis, and bottom base plates, respectively. These three plates are orthogonal to each other, providing a three-dimensional positioning reference plane for the single-axis inertial sensor in the X, Y, and Z directions, which are aligned with the machine tool's linear axis. The single-axis inertial sensor is rigidly connected to the zero-point positioner male plate. The X-axis, Y-axis, and Z-axis zero-point positioner mother plates are positioned to the male plate via rivets and secured with bolts.

[0009] The integrated data acquisition module is fixed to the bottom substrate by bolts and includes a data acquisition circuit, a battery power supply unit, and a wireless communication module. It is used to power the single-axis inertial sensor and to acquire and wirelessly transmit its output signal.

[0010] Furthermore, the single-axis inertial sensor includes an accelerometer and a gyroscope. The single-axis inertial sensor acquires dynamic measurement data in the X, Y, and Z directions through three independent clamping and measurement operations.

[0011] A method for detecting linear axis error in a machine tool, based on the aforementioned split-body inertial measurement device, includes the following steps:

[0012] Step 1: Install the split inertial measurement unit;

[0013] The split inertial measurement unit is fixed to a preset position on the surface of the machine tool worktable via a magnetic base under the bottom base plate;

[0014] Step 2, assembly of the single-axis inertial sensor;

[0015] The single-axis inertial sensor is assembled with the X-axis zero-point positioner female disk, Y-axis zero-point positioner female disk, and Z-axis zero-point positioner female disk respectively through the zero-point positioner male disk, and is used for X-axis linear axis, Y-axis linear axis, and Z-axis linear axis measurement respectively.

[0016] Step 3, Static and Dynamic Data Acquisition;

[0017] Each time a single-axis inertial sensor is assembled, static data from the single-axis inertial sensor is collected for zero-bias correction and initial alignment. Then, the measured linear axis of the machine tool is driven to execute a preset reciprocating motion trajectory. During the reciprocating motion, dynamic measurement data from the single-axis inertial sensor is collected.

[0018] Step 4, Static data fusion and alignment;

[0019] The static data of the single-axis inertial sensor in three assembly positions are fused to obtain unified initial alignment parameters.

[0020] Step 5: Dynamic data splicing and calculation;

[0021] The dynamic measurement data of the linear axis being measured on the machine tool are spliced ​​and the coordinates are transformed. The initial alignment parameters obtained in step 4 are used for error correction, and the six-dimensional geometric error information of the linear axis being measured on the machine tool is calculated.

[0022] Furthermore, in step 4, the static time periods are extracted from the static data of the three assembly positions as inputs. Combined with local latitude and longitude information, gravity vector and Earth rotation angular velocity model, the data of the three assembly positions are fused to establish the overall alignment relationship between the equivalent three-axis inertial navigation system composed of single-axis inertial sensors in the X, Y and Z directions and the Earth coordinate system.

[0023] Furthermore, in step 5, the start and end positions of the machine tool linear axis motion are used as the time synchronization reference for the measurement data, and the measurement data of the three assembly positions are unified into the machine tool coordinate system through the coordinate transformation matrix from the measured linear axis coordinate system to the machine tool coordinate system.

[0024] Furthermore, the six-dimensional geometric error information of the machine tool's measured linear axis includes the positioning error along the machine tool's measured linear axis, the two-way straightness error orthogonal to the machine tool's measured linear axis, and the three-way angular deviation in the X, Y, and Z directions.

[0025] The beneficial effects of this invention are:

[0026] (1) By combining a single-axis inertial sensor with an orthogonal triaxial zero-point positioner, multi-directional multiplexing measurement of the single-axis inertial sensor is realized. The six-dimensional geometric error is reconstructed by combining data fusion algorithm, avoiding the use of multiple single-axis inertial sensors, and significantly reducing hardware costs while ensuring measurement accuracy.

[0027] (2) The static calibration fusion method is adopted, which combines latitude and longitude, gravity vector and Earth rotation angular velocity model for initial alignment, effectively eliminating systematic errors and improving the consistency and reliability of measurement results.

[0028] (3) The orthogonal triaxial zero-point positioner combines pull pin positioning and bolt fastening to achieve highly repeatable clamping and positioning. With the bottom magnetic suction structure, it can be quickly installed and disassembled on the machine tool workbench, significantly improving on-site operation efficiency.

[0029] (4) The integrated data acquisition module has a built-in battery and wireless communication unit to achieve wireless power supply and transmission, avoid cable interference, and improve the applicability and stability of the device in the machine tool environment.

[0030] (5) The overall structure is compact and easy to install. It can quickly complete the six-dimensional error detection of the linear axis on the machine tool site, providing an efficient, low-cost and reliable technical solution for machine tool accuracy analysis and error compensation. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure of a split-type inertial measurement unit used for detecting linear axis errors in machine tools.

[0032] Figure 2 This is a schematic diagram of the structure of the single-axis inertial sensor unit of the device of the present invention.

[0033] Figure 3 This is a flowchart illustrating the method for detecting linear axis errors in machine tools using the device of the present invention.

[0034] Figure 4 This is a schematic diagram illustrating the application scenario of the device of the present invention on a machine tool workbench.

[0035] In the figure: 1 Bottom substrate; 2 X-axis vertical substrate; 3 Y-axis vertical substrate; 4 X-axis zero-point positioner mother disk; 5 Y-axis zero-point positioner mother disk; 6 Z-axis zero-point positioner mother disk; 7 Zero-point positioner male disk; 8 Single-axis inertial sensor; 9 Integrated data acquisition module; 10 Magnetic base; 81 Accelerometer; 82 Gyroscope. Detailed Implementation

[0036] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0037] like Figure 1 As shown, the present invention provides a split inertial measurement device for detecting linear axis errors in machine tools, comprising a bottom base plate 1, an X-axis vertical base plate 2, a Y-axis vertical base plate 3, an X-axis zero-point positioner mother plate 4, a Y-axis zero-point positioner mother plate 5, a Z-axis zero-point positioner mother plate 6, a zero-point positioner male plate 7, a single-axis inertial sensor 8, an integrated data acquisition module 9, and a magnetic base 10.

[0038] In this embodiment, the bottom substrate 1 serves as the basic support component for the split inertial measurement unit (IMU). Multiple magnetic bases 10 are evenly distributed below it, used to quickly fix the IMU onto the machine tool worktable surface, facilitating on-machine installation and removal. The X-axis vertical substrate 2 and the Y-axis vertical substrate 3 are respectively vertically mounted on both sides of the bottom substrate 1, supporting the corresponding X-axis zero-point locator mother disk 4 and Y-axis zero-point locator mother disk 5. The Z-axis zero-point locator mother disk 6 is disposed on the bottom substrate 1, forming, together with the X-axis zero-point locator mother disk 4 and the Y-axis zero-point locator mother disk 5, mutually orthogonal X, Y, and Z-axis positioning reference planes.

[0039] In this embodiment, the single-axis inertial sensor 8 is clamped by the zero-point locator male disk 7. The zero-point locator male disk 7 is connected to the X-axis zero-point locator female disk 4, the Y-axis zero-point locator female disk 5, and the Z-axis zero-point locator female disk 6 using pull pins and bolts for positioning, achieving highly repeatable clamping and positioning. The single-axis inertial sensor 8 integrates a combination unit of accelerometer 81 and gyroscope 82, enabling it to collect static and dynamic measurement data under different installation orientations. In this way, a single single-axis inertial sensor 8 can complete equivalent triaxial measurement tasks in three directions, avoiding the cost and assembly complexity associated with using multiple single-axis inertial sensors 8 in parallel.

[0040] In this embodiment, the integrated data acquisition module 9 is fixed to the bottom substrate 1 by bolts. The integrated data acquisition module 9 contains a data acquisition circuit board, a rechargeable battery, and a wireless communication module. The integrated data acquisition module 9 is used to provide power to the single-axis inertial sensor 8, and simultaneously completes data acquisition and wireless transmission, avoiding interference and wiring complexity from external cables, and improving the stability and applicability of the split inertial measurement device in machine tool environments.

[0041] In this embodiment, as Figure 2 As shown, the single-axis inertial sensor 8 is integrated with the zero-point positioner disk 7, and its outer housing is designed for quick clamping on the reference planes of the mother disk in the X, Y, and Z directions. Through three independent clamping and measurement operations, inertial measurement data in different directions can be acquired.

[0042] like Figure 3 As shown, the present invention provides a method for detecting linear axis errors in machine tools. This method is based on the aforementioned split-body inertial measurement device and includes the following steps:

[0043] Step 1, Installation of the split inertial measurement unit: Quickly fix the split inertial measurement unit to the preset position on the machine tool worktable surface through the magnetic base 10 under the bottom base plate 1. The orthogonal X-axis zero-point positioner mother plate 4, Y-axis zero-point positioner mother plate 5, and Z-axis zero-point positioner mother plate 6 are already fixed at the factory with the X-axis vertical base plate 2, Y-axis vertical base plate 3, and bottom base plate 1, and do not need to be installed separately.

[0044] Step 2, Assembly of single-axis inertial sensor 8: Assemble the single-axis inertial sensor 8 sequentially onto the X-axis zero-point positioner mother disk 4, Y-axis zero-point positioner mother disk 5, and Z-axis zero-point positioner mother disk 6 via the zero-point positioner male disk 7, for error measurement of the X-axis, Y-axis, and Z-axis respectively.

[0045] Step 3, Static and Dynamic Data Acquisition: During each assembly, static data from the single-axis inertial sensor 8 is first acquired for zero-bias correction and initial alignment. Subsequently, the machine tool's X, Y, and Z axes are driven to execute preset reciprocating motion trajectories. During these reciprocating motions, dynamic measurement data from the single-axis inertial sensor 8 are acquired. .

[0046] Step 4, Static Data Fusion and Alignment: The static data of the single-axis inertial sensor 8 in the three assembly positions are fused and processed. Combined with local latitude and longitude information, gravity vector and Earth rotation angular velocity model, the overall alignment relationship between the equivalent three-axis inertial navigation system composed of the single-axis inertial sensor 8 in the X, Y and Z directions and the Earth coordinate system is established, thereby obtaining unified initial alignment parameters.

[0047] Step 5: Dynamic Data Assembly and Calculation: The dynamic measurement data obtained from the three assembly steps are then assembled. The data is spliced ​​and transformed, and the dynamic data is corrected using the unified initial alignment parameters obtained in step 4. The theoretical trajectory of the machine tool is compared with the measured trajectory, and the six-dimensional geometric error information of the X-axis, Y-axis and Z-axis is output, including positioning error, two-way straightness error and three-way angle deviation.

[0048] In this embodiment, as Figure 4 As shown, in the application scenario of the split inertial measurement device on the machine tool workbench, it can be quickly fixed by the magnetic base 10. The single-axis inertial sensor 8 achieves multi-directional measurement by reusing the three-axis master disk (X-axis zero-point positioner master disk 4, Y-axis zero-point positioner master disk 5, and Z-axis zero-point positioner master disk 6). The integrated data acquisition module 9 completes data acquisition and wireless transmission, thereby realizing fast and efficient machine tool linear axis error detection in the field environment.

[0049] It should be understood that those skilled in the art can make various modifications and improvements without departing from the spirit and scope of the present invention, and all such modifications and improvements should be considered within the scope of protection of the present invention.

Claims

1. A split-body inertial measurement device for detecting linear axis errors in machine tools, characterized in that, The split inertial measurement device includes a bottom base plate (1), an X-axis vertical base plate (2), a Y-axis vertical base plate (3), an X-axis zero-point locator mother plate (4), a Y-axis zero-point locator mother plate (5), a Z-axis zero-point locator mother plate (6), a zero-point locator male plate (7), a single-axis inertial sensor (8), an integrated data acquisition module (9), and a magnetic base (10). Four magnetic bases (10) are provided below the bottom base plate (1) for fixing the split inertial measurement device to or removing it from the machine tool worktable surface; the X-axis vertical base plate (2) and the Y-axis vertical base plate (3) are respectively vertically arranged on the bottom base plate (1), and the X-axis zero-point positioner mother plate (4), the Y-axis zero-point positioner mother plate (5) and the Z-axis zero-point positioner mother plate (6) are respectively fixed on the X-axis vertical base plate (2), the Y-axis vertical base plate (3) and the bottom base plate (1). The X-axis zero-point positioner mother plate (4), the Y-axis zero-point positioner mother plate (5) and the Z-axis zero-point positioner mother plate (6) are orthogonal to each other and are used to provide a single-axis inertial sensor (8). In the three-dimensional positioning reference planes of X, Y, and Z directions, the X, Y, and Z directions are the same as the linear axis directions of the machine tool; the single-axis inertial sensor (8) is rigidly connected to the zero-point positioner male disk (7), and the X-axis zero-point positioner female disk (4), Y-axis zero-point positioner female disk (5), and Z-axis zero-point positioner female disk (6) are respectively positioned with the zero-point positioner male disk (7) by pull pins and fastened by bolts; the single-axis inertial sensor (8) is assembled with the X-axis zero-point positioner female disk (4), Y-axis zero-point positioner female disk (5), and Z-axis zero-point positioner female disk (6) through the zero-point positioner male disk (7) respectively, and is used for X-axis linear axis, Y-axis linear axis, and Z-axis linear axis measurement respectively; The integrated data acquisition module (9) is fixed to the bottom substrate (1) by bolts. It includes a data acquisition circuit, a battery power supply unit and a wireless communication module, which are used to power the single-axis inertial sensor (8) and to acquire and wirelessly transmit its output signal.

2. The split inertial measurement device for detecting linear axis errors in machine tools according to claim 1, characterized in that, The single-axis inertial sensor (8) includes an accelerometer (81) and a gyroscope (82). The single-axis inertial sensor (8) acquires dynamic measurement data in the X, Y, and Z directions through three independent clamping and measurement operations.

3. A method for detecting linear axis error in a machine tool, characterized in that, The machine tool linear axis error detection method is based on the split inertial measurement device for machine tool linear axis error detection as described in claim 1, and includes the following steps: Step 1: Install the split inertial measurement unit; The split inertial measurement unit is fixed to a preset position on the surface of the machine tool worktable via the magnetic base (10) below the bottom base plate (1); Step 2, Assembly of the single-axis inertial sensor (8); The single-axis inertial sensor (8) is assembled with the X-axis zero-point locator mother disk (4), Y-axis zero-point locator mother disk (5), and Z-axis zero-point locator mother disk (6) respectively through the zero-point locator male disk (7), and is used for X-axis linear axis, Y-axis linear axis and Z-axis linear axis measurement respectively; Step 3, Static and Dynamic Data Acquisition; Each time the single-axis inertial sensor (8) is assembled, the static data of the single-axis inertial sensor (8) is collected for zero bias correction and initial alignment. Then the machine tool is driven to execute the preset reciprocating motion trajectory of the measured linear axis. During the reciprocating motion, the dynamic measurement data of the single-axis inertial sensor (8) is collected. Step 4, Static data fusion and alignment; The static data of the single-axis inertial sensor (8) in the three assembly positions are fused to obtain unified initial alignment parameters; Step 5: Dynamic data splicing and calculation; The dynamic measurement data of the linear axis being measured on the machine tool are spliced ​​and the coordinates are transformed. The initial alignment parameters obtained in step 4 are used for error correction, and the six-dimensional geometric error information of the linear axis being measured on the machine tool is calculated.

4. The machine tool linear axis error detection method according to claim 3, characterized in that, In step 4, the static time periods are extracted from the static data of the three assembly positions as inputs. Combined with local latitude and longitude information, gravity vector and Earth rotation angular velocity model, the data of the three assembly positions are fused to establish the overall alignment relationship between the equivalent three-axis inertial navigation system composed of single-axis inertial sensor (8) in the X, Y and Z directions and the Earth coordinate system.

5. The machine tool linear axis error detection method according to claim 3, characterized in that, In step 5, the start and end positions of the machine tool linear axis motion are used as the time synchronization reference for the measurement data, and the measurement data of the three assembly positions are unified into the machine tool coordinate system through the coordinate transformation matrix from the measured linear axis coordinate system to the machine tool coordinate system.

6. The machine tool linear axis error detection method according to claim 3, characterized in that, The six-dimensional geometric error information of the machine tool's measured linear axis includes the positioning error along the machine tool's measured linear axis, the two-way straightness error orthogonal to the machine tool's measured linear axis, and the three-way angular deviation in the X, Y, and Z directions.

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