Three-coordinate auxiliary alignment device

Abstract

The present invention relates to the field of three-coordinate measurement technology, and discloses a three-coordinate auxiliary alignment device. It includes: a fixing module, a monitoring module, a processing module and a control module; the monitoring module includes a contour acquisition unit placed above the fixing module, and a deformation acquisition unit on the support surface of the fixing module, respectively acquiring the contour data of the workpiece to be measured, and the corresponding deformation data when the support surface contacts different surfaces of the workpiece to be measured; the processing module is respectively connected to the contour acquisition unit and the deformation acquisition unit, and calculates the theoretical geometric center and the dynamic geometric center of the workpiece to be measured to obtain the actual geometric center; the control module is connected to the processing module and the fixing module, and drives the fixing module to perform dynamic adjustment. This application solves the actual geometric center of the workpiece to be measured in real time through the processing module, and combines the control module to drive the dynamic adjustment of the fixing module, so as to keep the geometric center unchanged during the continuous measurement of multiple surfaces of a complex workpiece, thereby improving the accuracy of three-coordinate measurement.

Description

Technical Field

[0001] The present invention relates to the technical field of three-coordinate measurement, in particular to a three-coordinate auxiliary alignment device. Background Art

[0002] In the field of three-coordinate measurement, the precise positioning of the geometric center of the workpiece is the core challenge to ensure measurement consistency. Traditional fixtures and alignment technologies generally have the following technical bottlenecks: when the workpiece needs to switch different contact surfaces for multi-dimensional measurement, the traditional fixture cannot dynamically adjust the clamping position according to the force and deformation of each contact surface. For example, when a certain surface of the workpiece is compressed, the support part sinks locally, resulting in a shift in the geometric center. The existing technology requires manual intervention for repeated calibration, which is inefficient and difficult to ensure the consistency of multiple batches of measurements. In addition, the existing systems mostly rely on the theoretical geometric center of the workpiece for positioning, but during actual clamping, due to uneven force on the contact surface between the fixture and the workpiece or material deformation (such as elastic deformation of the support part), the dynamic geometric center of the workpiece will deviate from the theoretical value. This leads to systematic errors between the theoretical model and the actual clamping state, and low measurement accuracy. Summary of the Invention

[0003] The three-coordinate auxiliary alignment device provided in this application calculates the real-time actual geometric center by fusing the theoretical geometric center calculated based on the contour data of the workpiece to be measured with the dynamic geometric center calculated based on the deformation data through the processing module. The device is combined with the control module to drive the dynamic adjustment of the fixed module to eliminate the center offset caused by clamping deformation and maintain the geometric center unchanged during continuous measurement of multiple surfaces of complex workpieces, thereby improving its measurement accuracy. The specific solution is as follows:

[0004] A three-coordinate auxiliary alignment device, comprising:

[0005] Fixed module, used for dynamic clamping of the workpiece to be tested;

[0006] The monitoring module includes a contour acquisition unit and a deformation acquisition unit; the contour acquisition unit is placed above the support platform of the fixed module to obtain contour data of the workpiece to be measured; the deformation acquisition unit is placed on the support surface of the fixed module to obtain corresponding deformation data when the support surface of the fixed module contacts different surfaces of the workpiece to be measured;

[0007] a processing module, connected to the contour acquisition unit and the deformation acquisition unit, respectively, the processing module calculating the theoretical geometric center of the workpiece to be measured based on the contour data, calculating the dynamic geometric center of the workpiece to be measured when different surfaces of the workpiece to be measured are in contact with the support surface based on the deformation data, and fusing the theoretical geometric center and the dynamic geometric center to determine the actual geometric center of the workpiece to be measured;

[0008] The control module is connected to the processing module and the fixing module, and drives the fixing module to perform dynamic adjustment according to the coordinates of the actual geometric center, so that when different surfaces of the workpiece to be measured contact the fixing module, the geometric center is always the actual geometric center.

[0009] Preferably, the processing module fuses the theoretical geometric center and the dynamic geometric center through the least square method to obtain the actual geometric center. The specific formula is:

[0010] ;

[0011] in, l is the deformation weight factor.

[0012] Preferably, the fixing module includes a carrying platform and at least three clamping mechanisms;

[0013] The clamping mechanism is radially distributed along the circumference of the carrying platform, and based on the theory that three points determine a surface, it can support and clamp different surfaces of the workpiece to be measured. The clamping mechanism includes a telescopic arm;

[0014] One end of the telescopic arm is mounted on the carrying platform and rotates along the carrying platform, a support portion is provided on the top of the other end of the telescopic arm, and clamping members for the workpiece to be measured are respectively provided on both sides of the end of the telescopic arm provided with the support portion, and a controller of the telescopic arm is connected to the control module;

[0015] The clamping member and the supporting part are respectively installed on the telescopic arm, and different supporting points and clamping points of the workpiece to be measured are formed through the extension and contraction of the telescopic arm and the rotation around the carrying platform, thereby ensuring that the coordinates of the workpiece to be measured in the two horizontal directions are the same as the coordinates of the actual geometric center in the two horizontal directions.

[0016] Preferably, the clamping member includes a mounting seat;

[0017] The mounting base is mounted on the top of the support portion, and arms are provided on opposite sides of the mounting base;

[0018] One end of the arm is mounted on both sides of the mounting seat and rotates along the connection respectively, and the other end of the arm is mounted with a clamping claw;

[0019] The controller of the gripper and the controller of the arm are respectively connected to the control module;

[0020] The deformation collection unit is installed on the top of the mounting seat.

[0021] Preferably, the clamping jaw is an open adjustable clamping jaw.

[0022] Preferably, the clamping jaws are pneumatic adaptive clamping jaws to adapt to the surface of the workpiece to be measured.

[0023] Preferably, the arm is a telescopic arm, which is extended or shortened according to the change in the size of the angle between two adjacent telescopic arms to maintain the uniformity of the clamping points.

[0024] Preferably, the support portion is telescopically extended along the vertical direction of the telescopic arm to achieve vertical adjustment of the workpiece to be measured, thereby ensuring that the vertical coordinates of the workpiece to be measured are the same as the vertical coordinates of the actual geometric center.

[0025] Preferably, the carrying platform includes: a seat body;

[0026] An annular cavity is provided in the seat body, and an annular sliding groove is provided on the circumference of the seat body;

[0027] An electromagnetic ring is provided in the annular cavity, and a slip ring is provided on the electromagnetic ring;

[0028] The slip ring is sleeved outside the electromagnetic ring and slides along the length direction of the electromagnetic ring;

[0029] The annular chute is in communication with the annular cavity;

[0030] One end of the telescopic arm passes through the annular slot and is connected to the electromagnetic ring. The telescopic arm is slidably connected to the annular slot. The telescopic arm moves on the electromagnetic ring through the slip ring to achieve rotation around the center of the base body.

[0031] The controller of the electromagnetic ring is connected to the control module.

[0032] Preferably, the seat body comprises an upper seat body and a lower seat body that are buckled together;

[0033] The centers of the opposite sides of the upper and lower seats are respectively provided with matching connecting bosses and connecting grooves, and the opposite circumferential sides of the upper and lower seats are respectively provided with upper annular sliding grooves and lower annular sliding grooves;

[0034] An upper annular cavity and a lower annular cavity with openings facing each other are respectively provided on the circumferential sides of the connecting boss and the connecting groove, and the cross sections of the upper annular cavity and the lower annular cavity are semicircular. The upper annular cavity and the lower annular cavity are respectively located between the upper annular chute and the connecting boss, and between the lower annular chute and the connecting groove, and the upper annular cavity and the lower annular cavity are respectively communicated with the upper annular chute and the lower annular chute;

[0035] The upper annular chute and the lower annular chute form an annular chute;

[0036] The top and the bottom of one end of the telescopic arm facing the seat body are slidably connected to the upper annular sliding groove and the lower annular sliding groove respectively.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] The contour acquisition unit and deformation acquisition unit in the monitoring module acquire the workpiece's contour data and support surface deformation data, respectively. This system comprehensively considers the workpiece's actual clamping state, breaking through the limitations of traditional techniques that rely solely on theoretical geometric center positioning. The processing module calculates the theoretical geometric center based on the contour data and, combined with the deformation data, calculates the dynamic geometric center. By integrating these two, the actual geometric center of the workpiece is determined. This determined actual geometric center closely matches the workpiece's actual state, resolving the problem of geometric center positioning deviation caused by traditional measurements due to neglect of clamping deformation, laying a solid foundation for accurate measurement. The control module dynamically adjusts the fixture module based on the coordinates of the actual geometric center determined by the processing module. During actual measurements, when different surfaces of the workpiece come into contact with the fixture module, varying forces prevent traditional fixtures from responding and adjusting in a timely manner, resulting in geometric center shifts and, consequently, measurement errors. The fixture module of this device, however, adjusts in real time based on the actual geometric center, ensuring a stable geometric center during continuous measurement of multiple surfaces. This feature effectively eliminates center shifts caused by clamping deformation and contact surface switching, significantly improving the precision of three-dimensional coordinate measurement and ensuring the accuracy and reliability of measurement results. This application realizes the automation of the entire process from data acquisition, geometric center calculation to fixed module adjustment. Traditional measurement requires manual intervention and repeated calibration after the geometric center of the workpiece is offset. This process is cumbersome and time-consuming. The technical solution of the present invention eliminates the need for frequent manual operations during the measurement process, greatly reducing the measurement preparation time and errors caused by human factors. Whether it is the multi-faceted measurement of a single complex workpiece or the repeated measurement of multiple batches of workpieces, it can be completed efficiently and stably, significantly improving measurement efficiency, reducing labor costs, and enhancing the stability and consistency of the measurement process.

[0039] By setting the clamping jaws to pneumatic adaptive clamping jaws with adjustable opening, it can adapt to the elastic deformation characteristics of the workpieces to be tested made of different materials, avoiding clamping overload or loosening caused by material differences. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of the principle framework of the three-coordinate auxiliary alignment device in the embodiment of the present application;

[0041] Figure 2 This is a structural diagram of a fixing module in a three-coordinate auxiliary alignment device according to an embodiment of the present application;

[0042] Figure 3Schematic diagram of the cross-sectional structure of the carrying platform in the three-coordinate auxiliary alignment device in the embodiment of the present application;

[0043] Figure 4 Schematic diagram of the structure of the lower seat body of the carrying platform in the three-coordinate auxiliary alignment device in the embodiment of the present application;

[0044] Figure 5 This is a schematic structural diagram of the upper seat in the carrying platform of the three-coordinate auxiliary alignment device in an embodiment of the present application;

[0045] In the figure: 1. Carrying platform; 2. Telescopic arm; 3. Support part; 4. Mounting seat; 5. Arm; 6. Clamping claw; 7. Slip ring; 8. Electromagnetic ring; 9. Deformation acquisition unit; 10. Annular slide; 11. Upper seat; 12. Lower seat; 13. Groove wall of connecting groove; 14. Annular cavity; 15. Connecting boss. DETAILED DESCRIPTION

[0046] The three-coordinate auxiliary alignment device provided in this application is intended to solve the problem of positioning the geometric center of the workpiece in traditional three-coordinate measurement. Through the collaborative work of multiple modules, it can achieve the stability of the geometric center during continuous measurement of multiple surfaces of complex workpieces and improve measurement accuracy.

[0047] The three-coordinate auxiliary alignment device is mainly composed of a fixing module, a monitoring module, a processing module and a control module.

[0048] Fixed module: It is responsible for the dynamic clamping of the workpiece to be tested and consists of a carrying platform 1 and at least three clamping mechanisms.

[0049] The supporting platform 1 comprises a base body, which is composed of an upper base 11 and a lower base 12 that are fastened together. An annular cavity 14 is located within the base body (composed of an upper annular cavity with a semicircular arc-shaped cross-section and a lower annular cavity with opposing openings). An annular groove 10 (formed by an upper annular groove and a lower annular groove) is arranged around the base body. Matching connecting bosses 15 (integrally formed with the lower base 12) and connecting grooves are located in the centers of opposing sides of the upper and lower bases 11 and 12, respectively. The connecting bosses 15 insert into the connecting grooves for initial positioning. Simultaneously, the groove walls 13 of the connecting grooves insert into the recesses on either side of the connecting bosses to further enhance positioning. Bolts are then used to secure the upper and lower bases 11 and 12. The annular cavity 14 houses an electromagnetic ring 8, which is fitted with slip rings 7, matching the number of slip rings 7 on the telescopic arms 2. The slip rings 7 slide along the length of the electromagnetic ring 8.

[0050] The clamping mechanism is radially distributed along the side of the supporting platform 1. Each clamping mechanism includes two telescopic arms 2, a support portion 3 and a clamping member. One end of the telescopic arm 2 is mounted on the supporting platform 1, connected to the slip ring 7 through the annular slide 10, and can rotate around the supporting platform 1. The support portion 3 is provided on the top of the other end, and clamping members are installed on both sides of the support portion 3. The clamping member includes a mounting seat 4, and arms 5 are provided on opposite sides of the top of the mounting seat 4. One end of the arm 5 is rotatably connected to the mounting seat 4, and the other end is equipped with a clamping jaw 6. The clamping jaw 6 is an open and adjustable clamping jaw. The clamping jaw 6 is a pneumatic adaptive clamping jaw that adapts to the elastic deformation characteristics of the workpiece to be measured of different materials (such as metal, composite materials), effectively avoids the problem of clamping overload or loosening, significantly improves the accuracy and stability of three-coordinate measurement, and meets the needs of continuous measurement of multiple surfaces of complex workpieces.

[0051] Monitoring module: This module includes a contour acquisition unit and a deformation acquisition unit 9. The contour acquisition unit is installed above the support platform 1 of the fixed module and is used to collect contour data of the workpiece to be measured. The deformation acquisition unit 9 is installed on the support surface of the fixed module (i.e., the top of the support portion 3) and is responsible for obtaining deformation data when the support surface of the fixed module contacts different surfaces of the workpiece to be measured.

[0052] Processing module: connected to the contour acquisition unit and the deformation acquisition unit 9 respectively. The processing module calculates the theoretical geometric center of the workpiece to be measured using the centroid method based on the contour data collected by the contour acquisition unit; at the same time, based on the deformation data obtained by the deformation acquisition unit 9, it calculates the dynamic geometric center of different surfaces of the workpiece to be measured when they are in contact with the support surface. The processing module fuses the theoretical geometric center and the dynamic geometric center through the least squares method. In the process of geometric center fusion, it is assumed that the theoretical geometric center C 理论 and dynamic geometric center C 动态 The actual geometric center C 实际 In order to optimize the fusion weight of the two, the least squares method is used to construct the objective function to minimize the weighted square sum of the error between the theoretical value and the dynamic value:

[0053] ;

[0054] in, l is the deformation weight factor, which reflects the confidence of the dynamic data. The optimal solution is obtained by taking the derivative of the objective function and setting it to zero:

[0055] ;

[0056] Thus, the actual geometric center is calculated C 实际 .in C 理论It is the theoretical geometric center calculated using the centroid method based on the contour data collected by the contour acquisition unit; C 动态 It is the dynamic geometric center obtained by correcting the theoretical value of deformation data, and the final actual geometric center is the weighted fusion of the two; l According to the elastic deformation degree of the support material, the orthogonal test shows that the error of λ is the smallest in the range of 0.2~0.8. This formula is based on the principle of least squares method. The dynamic geometric center is first calculated through deformation data, and then the theoretical geometric center and the dynamic geometric center are integrated to obtain a geometric center that is more in line with the actual situation. When calculating the dynamic geometric center, first according to the deformation amount of each deformation monitoring point Δdj Determine its weight w j , the formula is w j = aΔd j ( α The elastic coefficient of the material is calibrated experimentally, and the elastic modulus and Poisson's ratio of the support material are calibrated experimentally). Then, the theoretical geometric center is corrected for deformation to obtain the dynamic geometric center:

[0057] ;

[0058] in, For deformation j The normal vector direction is perpendicular to the support surface and points to the workpiece, which is pre-calibrated by the support surface structure; n is the total number of deformation monitoring points;

[0059] is the deformation of the j-th monitoring point (scalar, unit: mm);

[0060] The vector correction value representing the deformation of all monitoring points to the theoretical geometric center is obtained by vector superposition.

[0061] Deformation weight factor l Dynamic adjustment of:

[0062] Fixed value mode: When the workpiece material is known, l It can be pre-calibrated to a fixed value (range: 0.2~0.8) through orthogonal testing, for example, l =0.5, composite material workpiece l =0.7;

[0063] Dynamic adaptive mode: If the device is equipped with a material recognition module (such as a spectral sensor), it can automatically match the material properties of the workpiece according to the real-time recognition. lvalue, in order to take into account the deformation of the workpiece to be measured during the clamping process and realize the accurate calculation of the geometric center.

[0064] The control module connects the processing module and the fixation module. Based on the coordinates of the actual geometric center calculated by the processing module, it drives the fixation module to perform dynamic adjustments. Specifically, this involves energizing the electromagnetic ring 8, causing the slip ring 7 to rotate and extend the telescopic arm 2, adjust the vertical height of the support 3, and control the rotation angle of the arm 5 and the opening and closing of the clamping jaws 6. This ensures that the geometric center of the workpiece under test remains at the actual geometric center when different surfaces contact the fixation module.

[0065] This device integrates contour and deformation data through a processing module, constructing a multi-physics-field coupled geometric center correction algorithm for accurate real-time calculation of the actual geometric center. Based on the actual geometric center coordinates, the control module drives the telescopic arm 2, support unit 3, arm 5, and gripper 6 for coordinated adjustment, achieving closed-loop control of horizontal rotation, vertical lift, and clamping force, dynamically compensating for center offset caused by clamping deformation. The gripper 6 is controlled by a pneumatic proportional valve. Based on real-time deformation data fed back by the deformation acquisition unit, the gripping force is dynamically adjusted (range: 5N to 200N). This prevents excessive workpiece deformation caused by excessive clamping force, further improving geometric center positioning accuracy.

[0066] It should be noted that:

[0067] In the present application, the monitoring module is composed of a contour acquisition unit and a deformation acquisition unit. In order to obtain the three-dimensional point cloud data of the entire workpiece, and combine it with the microscopic strain distribution of the support surface monitored in real time by the deformation acquisition unit. The dynamic capture of contact mechanics parameters is realized; the processing module is connected to the contour acquisition unit and the deformation acquisition unit respectively. The theoretical geometric center of the workpiece to be measured is calculated according to the contour data; then, based on the deformation of each force point when the fixed module contacts different surfaces of the workpiece to be measured, the dynamic geometric center of the workpiece to be measured under different contact conditions is calculated; finally, the theoretical geometric center and the dynamic geometric center are integrated to determine the actual geometric center of the workpiece to be measured, and a reference of the geometric center with the authenticity of the workpiece to be measured is generated. The control module is connected to the processing module and the fixed module respectively. According to the actual geometric center calculated by the processing module, the fixed module is dynamically adjusted (the three-dimensional space coordinates are adjusted) so that when any surface of the workpiece to be measured contacts the fixed module, its geometric center always remains the actual geometric center, thereby providing a stable and unified geometric center for subsequent measurements of the three-dimensional coordinate measuring machine. During the multi-posture clamping process of the workpiece, the support point structure is dynamically adjusted so that the actual geometric center of the workpiece to be measured and the measurement reference coordinate system remain spatially invariant; thus providing a dynamic and stable metrology reference for multi-process measurement.

[0068] Example:

[0069] This embodiment will elaborate on the specific situation of the three-coordinate auxiliary alignment device in actual application, and clearly show the collaborative working process of each component with the help of the accompanying drawings to better understand the working principle and advantages of the device. The horizontal direction in this embodiment corresponds to the X / Y axis, and the vertical direction corresponds to the Z axis. Figure 1 As shown, in this embodiment, the contour acquisition unit and the deformation acquisition unit are respectively connected to the processing module, and the control module is respectively connected to the processing module, the telescopic arm, the support portion, the arm, the clamping jaws, and the electromagnetic ring. In this embodiment, the telescopic arm 2 is an electric push-rod telescopic arm, due to its stable telescopic performance and high precision, which can meet the requirements for precise adjustment of the horizontal position of the workpiece. The clamping jaws 6 are pneumatic adaptive clamps, which can automatically adjust the clamping force according to the shape and size of the workpiece to be measured, ensuring clamping stability and adapting to workpieces of different shapes. The support portion 3 uses a servo-electric lifting column with high-precision vertical lifting control capabilities, which can accurately adjust the height of the workpiece to be measured and ensure its vertical position accuracy. The electromagnetic ring 8 is a segmented electromagnetic coil ring composed of multiple independent coils arranged in a ring. Each coil can be independently energized. By controlling the direction and intensity of the current, a local magnetic field is generated. This interacts with the neodymium iron boron permanent magnet embedded in the slip ring 7, enabling precise movement control of the slip ring 7 and thus precisely adjusting the position of the telescopic arm 2. The contour acquisition unit adopts a laser displacement sensor; the deformation acquisition unit 9 adopts an integrated fiber Bragg grating (FBG) sensor;

[0070] Before measuring, place the workpiece to be measured on the carrying platform 1: Figure 2-5 The supporting platform 1 shown is composed of an upper base body 11 and a lower base body 12 that are fastened together. The centers of the opposite sides of the upper base body 11 and the lower base body 12 are respectively provided with matching connecting bosses 15 and connecting grooves. The connecting boss 15 and the lower base body 12 are integrally formed and inserted into the connecting groove of the upper base body 11 to achieve preliminary positioning. At the same time, the groove wall 13 of the connecting groove is inserted into the depressions on both sides of the connecting boss for further positioning, and then fixed by bolts to ensure that the supporting platform 1 is structurally stable.

[0071] In this embodiment, three clamping mechanisms are arranged radially at 120°. Each clamping mechanism comprises a telescopic arm 2, a support 3, and a clamping jaw 6. The telescopic arm is a motorized actuator. An integrated fiber Bragg grating (FBG) sensor is embedded in the top of the mounting base to monitor support deformation in real time.

[0072] One end of the telescopic arm 2 passes through the annular slot 10 and extends into the annular cavity 14, where it connects to the slip ring 7. A control module controls the electromagnetic ring 8 to generate a magnetic field, driving the slip ring 7 along the annular cavity. This in turn causes the telescopic arm 2 to slide within the annular slot 10 and rotate around the center of the base, driving the telescopic arm 2 to extend and retract, thereby adjusting the horizontal position of the support portion 3 and the clamping jaws 6 mounted at the end of the telescopic arm 2. The support portion 3 is mounted on the top of the end of the telescopic arm 2 facing away from the support platform 1, supporting the workpiece to be measured and allowing for vertical adjustment of the workpiece's height. The clamping jaws 6 are mounted on the end of the arm 5 facing away from the mounting base 4. The arm 5 is located on either side of the mounting base 4. The arm 5 is connected to the mounting base 4 via a drive motor and a rotating shaft. The sides of the arm 5 opposite the mounting base 4 are connected by corresponding arcuate connecting ears. The openings of these arcuate connecting ears are arranged in opposite directions and connected to the arm 5 and the mounting base 4 on the opposite sides. The opposite sides are connected by a rotating shaft. The drive motor is installed on the mounting base 4, and the controller of the drive motor is connected to the control module. The control module controls the rotation of the drive motor, and drives the arm 5 to rotate around the connection so that the contour formed by the arm 5 matches the contour of the workpiece to be measured, and adjusts the clamping position of the clamp 6. Under the action of the control module, the clamp 6 adaptively clamps the workpiece to be measured so that the clamp fits tightly to the surface of the workpiece to be measured, thereby ensuring the stability of the clamping.

[0073] Data collection:

[0074] The laser displacement sensor located above platform 1 begins scanning the workpiece placed on it, generating 3D point cloud profile data. This data accurately records the workpiece's contours and provides a key basis for subsequent calculation of the theoretical geometric center.

[0075] A deformation acquisition unit 9, which integrates a fiber Bragg grating (FBG) sensor, is embedded in the top of the mounting base 4. When a workpiece is placed on the support 3, the support 3 deforms to varying degrees due to factors such as the workpiece's gravity. The deformation acquisition unit 9 monitors this deformation data in real time and transmits it to the processing module.

[0076] The processing module receives the 3D point cloud contour data collected by the laser displacement sensor and the deformation data transmitted by the deformation acquisition unit 9. Based on the 3D point cloud contour data, the theoretical geometric center of the workpiece to be measured is calculated. In the specific calculation, the coordinates of a large number of contour data points are analyzed and processed to determine the center of gravity of the workpiece, thereby obtaining the theoretical geometric center; based on the deformation data, the dynamic geometric center is calculated. The processing module first calculates the deformation amount of each deformation monitoring point according to the deformation amount of each deformation monitoring point. Δd j Determine its weight w j , the formula is: w j = aΔd j ( α is the elastic coefficient of the material calibrated by experiment); then the theoretical geometric center is deformed and the dynamic geometric center is obtained. C 动态 The formula is:

[0077] ;

[0078] in For deformation j The normal vector direction is pre-calibrated by the support surface structure. w j is the weight factor, Δd j is the shape variable,

[0079] The product of the three needs to be determined according to the actual physical meaning, such as vector dot product or scalar weighting;

[0080] Finally, the processing module uses the least squares method to weightedly fuse the theoretical geometric center and the dynamic geometric center to obtain the actual geometric center. C 实际 , the formula is:

[0081] ;

[0082] in l is the deformation weight factor, the value range is 0.2≤ l ≤0.8, can be calibrated by experiment. After each adjustment, re-collect deformation data and iteratively calculate until the difference between the actual geometric center coordinates calculated twice in a row is less than (In this embodiment ), the iteration is terminated.

[0083] The control module uses a PLC controller to receive the actual geometric center coordinates output by the processing module, and controls the electromagnetic ring 8, telescopic arm 2, arm 5, clamping claw 6 and support part 3 to perform dynamic adjustments based on the actual geometric center coordinates. Specifically:

[0084] The control module sends instructions to the controller of electromagnetic ring 8, which consists of 16 independent coils evenly distributed along the annular cavity. Each coil can be independently energized. When a specific coil is energized, the generated magnetic field interacts with the NdFeB permanent magnet embedded in slip ring 7, pushing slip ring 7 to slide along the length of electromagnetic ring 8. One end of telescopic arm 2 passes through an annular groove 10 and connects to slip ring 7, driving telescopic arm 2 to slide within the annular groove 10 and rotate around the center of the base, adjusting the horizontal position of support 3 and clamping jaws 6 to evenly distribute the clamping points and compensate for horizontal center offsets caused by the placement of the workpiece to be measured or deformation of support 3.

[0085] The support part 3 is a servo electric lifting column, and its controller is connected to the control module. The control module drives the support part 3 to extend and retract in the vertical direction according to the actual geometric center coordinates, adjusts the height of the workpiece to be measured, ensures that the vertical coordinates of the workpiece to be measured are consistent with the vertical coordinates of the actual geometric center, and compensates for the center offset in the vertical direction.

[0086] Finally, conduct subsequent measurements.

[0087] After this dynamic adjustment, the geometric center of the workpiece to be measured is locked to the actual geometric center. At this point, the coordinate measuring machine performs high-precision measurements on the workpiece. During the measurement process, if the support portion 3 deforms again due to slight movement of the workpiece or other factors, the deformation acquisition unit 9 will monitor the new deformation data in real time and transmit it to the processing module. The processing module recalculates the actual geometric center, and the control module drives the fixing module to adjust again based on the new actual geometric center coordinates, ensuring that the workpiece geometric center remains stable during the measurement process, thereby improving the precision and accuracy of the three-dimensional coordinate measurement.

Claims

1. Three-coordinate auxiliary alignment device, characterized in that: The device comprises: A fixing module, used for dynamic clamping of the workpiece to be tested, the fixing module comprising a carrying platform and at least three clamping mechanisms; The clamping mechanisms are radially distributed along the circumference of the carrying platform to support and clamp different surfaces of the workpiece to be measured. The clamping mechanisms include a telescopic arm; one end of the telescopic arm is mounted on the carrying platform and rotates along the carrying platform, and the top of the other end of the telescopic arm is provided with a support portion, wherein the top end of the support portion forms a support surface; The monitoring module includes a contour acquisition unit and a deformation acquisition unit; the contour acquisition unit is placed above the support platform of the fixed module to obtain contour data of the workpiece to be measured; the deformation acquisition unit is placed on the support surface of the fixed module to obtain corresponding deformation data when the support surface of the fixed module contacts different surfaces of the workpiece to be measured; a processing module, connected to the contour acquisition unit and the deformation acquisition unit, respectively, the processing module calculating the theoretical geometric center of the workpiece to be measured based on the contour data, calculating the dynamic geometric center of the workpiece to be measured when different surfaces of the workpiece to be measured are in contact with the support surface based on the deformation data, and fusing the theoretical geometric center and the dynamic geometric center to determine the actual geometric center of the workpiece to be measured; a control module connected to the processing module and the fixing module, and driving the fixing module to perform dynamic adjustment according to the coordinates of the actual geometric center, so that when different surfaces of the workpiece to be measured contact the fixing module, the geometric center is always the actual geometric center; The processing module fuses the theoretical geometric center and the dynamic geometric center through the least square method to obtain the actual geometric center. The specific formula is: ； in, C 理论 is the theoretical geometric center, C 动态 is the dynamic geometric center, C 实际 is the actual geometric center, λ is the deformation weight factor.

2. The three-coordinate auxiliary alignment device according to claim 1, characterized in that: The telescopic arm is provided with clamping parts for the workpiece to be measured on both sides of one end of the support part, and the controller of the telescopic arm is connected to the control module; the clamping parts and the support part are respectively installed on the telescopic arm, and through the extension and contraction of the telescopic arm and the rotation around the carrying platform, different support points and clamping points of the workpiece to be measured are formed, so as to ensure that the coordinates of the workpiece to be measured in two directions of the horizontal plane are the same as the coordinates of the actual geometric center in two directions of the horizontal plane.

3. The three-coordinate auxiliary alignment device according to claim 2, characterized in that: The clamping member includes a mounting seat; The mounting base is mounted on the top of the support portion, and arms are provided on opposite sides of the mounting base; One end of the arm is mounted on both sides of the mounting seat and rotates along the connection with the mounting seat respectively, and the other end of the arm is mounted with a clamping claw; The controller of the gripper and the controller of the arm are respectively connected to the control module; The deformation collection unit is installed on the top of the mounting seat.

4. The three-coordinate auxiliary alignment device according to claim 3, characterized in that: The clamping jaws are open and adjustable clamping jaws.

5. The three-coordinate auxiliary alignment device according to claim 3, characterized in that: The grippers are pneumatically self-adapting to the surface of the workpiece to be measured.

6. The three-coordinate auxiliary alignment device according to claim 3, characterized in that: The arm is a telescopic arm, which is extended or shortened according to the change of the angle between two adjacent telescopic arms to maintain the uniformity of the clamping points.

7. The three-coordinate auxiliary alignment device according to claim 2, characterized in that: The support portion is extended and retracted along the vertical direction of the telescopic arm to achieve vertical adjustment of the workpiece to be measured, thereby ensuring that the vertical coordinates of the workpiece to be measured are the same as the vertical coordinates of the actual geometric center.

8. The three-coordinate auxiliary alignment device according to claim 2, characterized in that: The carrying platform includes: a seat body; An annular cavity is provided in the seat body, and an annular sliding groove is provided on the circumference of the seat body; An electromagnetic ring is provided in the annular cavity, and a slip ring is provided on the electromagnetic ring; The slip ring is sleeved outside the electromagnetic ring and slides along the length direction of the electromagnetic ring; The annular chute is in communication with the annular cavity; One end of the telescopic arm passes through the annular slot and is connected to the electromagnetic ring. The telescopic arm is slidably connected to the annular slot. The telescopic arm moves on the electromagnetic ring through the slip ring to achieve rotation around the center of the base body. The controller of the electromagnetic ring is connected to the control module.

9. The three-coordinate auxiliary alignment device according to claim 8, characterized in that: The base body comprises an upper base body and a lower base body that are buckled together; The centers of the opposite sides of the upper and lower seats are respectively provided with matching connecting bosses and connecting grooves, and the opposite circumferential sides of the upper and lower seats are respectively provided with upper annular sliding grooves and lower annular sliding grooves; An upper annular cavity and a lower annular cavity with openings facing each other are respectively provided on the circumferential sides of the connecting boss and the connecting groove, and the cross sections of the upper annular cavity and the lower annular cavity are semicircular. The upper annular cavity and the lower annular cavity are respectively located between the upper annular chute and the connecting boss, and between the lower annular chute and the connecting groove, and the upper annular cavity and the lower annular cavity are respectively communicated with the upper annular chute and the lower annular chute; The upper annular chute and the lower annular chute form an annular chute; The top and the bottom of one end of the telescopic arm facing the seat body are slidably connected to the upper annular sliding groove and the lower annular sliding groove respectively.

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