A helicopter gear sleeve part axis pose adjustment method based on eddy current ranging

Abstract

This invention discloses a method for adjusting the assembly posture of helicopter gear sleeve parts based on eddy current ranging. The method includes: first, establishing a gear sleeve part posture measurement system and a measurement coordinate system; then, correcting the measurement error of the inner arc surface features measured by an eddy current displacement sensor; using the sensor for rotary scanning measurement to extract the surface contour of the part; calculating the tilt angle information of the gear sleeve part's axis in the coarse measurement stage; and then adjusting the relative posture between the sensor and the measured gear sleeve part; in the fine measurement stage, obtaining the coordinates of the center of the cross-sectional contour of the upper and lower inner arc surfaces, calculating the axis posture parameters of the gear sleeve part, and finally adjusting the assembly posture. This invention aims to correct the eddy current measurement error of the inner arc surface features under the conditions of no target, non-contact, and unaffected by grease, thereby improving the measurement accuracy and efficiency of the gear sleeve part's assembly posture. It can also be used for high-precision measurement and adjustment of the part's axis posture during automated assembly of gear sleeve parts.

Description

Technical Field

[0001] This invention relates to a method for adjusting the axial position and orientation of a gear sleeve component, and to the field of gear sleeve component assembly and measurement technology, specifically to a method for adjusting the axial position and orientation of a helicopter gear sleeve component based on eddy current ranging. Background Technology

[0002] The assembly of a helicopter lift system mainly involves the docking and assembly of three major components: the main gearbox, the automatic swashplate, and the main rotor hub. The main rotor hub's inner cavity is connected to the main gearbox shaft via an involute spline meshing, requiring high precision. Currently, the assembly method involves workers using an overhead crane to lift the main rotor hub, repeatedly observing it before pushing it to dock with the main gearbox shaft. This lifting and positioning process makes it difficult to precisely control component movement, easily damaging parts and resulting in low assembly efficiency.

[0003] In recent years, with the rapid development of technologies related to automated aircraft assembly, researchers at home and abroad have developed advanced attitude adjustment and positioning mechanisms to meet the modern production requirements of the aerospace field. However, in the automated docking and assembly process of the lift system, simple clamping or tooling positioning methods cannot guarantee the attitude accuracy requirements during the assembly of the main rotor hub. High-precision measurement methods are often required to obtain the attitude information of the parts to be assembled, which can then guide the attitude adjustment mechanism to make attitude adjustments.

[0004] Current domestic research has, to some extent, met the pose measurement requirements in the automated assembly process of aircraft. For example, the paper "Research Progress on High-Precision Measurement Technology in Large Aircraft Assembly" mentions a high-precision measurement method for a large-space measurement field in aircraft assembly. Its measurement principle involves using advanced digital measurement equipment such as laser trackers and iGPS (indoor GPS) to measure targets mounted on the target parts, obtaining the spatial position information of multiple points in the aircraft design coordinate system, and then calculating the spatial pose information of the aircraft assembly. This method requires installing measurement targets at appropriate positions on the surface of the parts and ensuring unobstructed optical paths between the measurement equipment and the targets. However, due to the lack of external reference points and the presence of obstructions in the main rotor hub, this type of target-based measurement method is not applicable. For example, patent application CN112815850A, entitled "A Method and Apparatus for Measuring the Position and Pose of a Cylinder," discloses a method and apparatus for measuring the position and pose of a cylinder. This method involves arranging three linear laser displacement sensors around the cylinder to be measured and moving their values ​​to obtain relevant parameters of the measurement interface at different heights of the cylinder, thus calculating the cylinder's tilt. While this method avoids the limitation of sensor size for measuring the outer cylindrical surface and prevents product rotation, it requires a larger number of sensors, increasing costs. Furthermore, the laser cannot guarantee measurement accuracy when the measured surface is contaminated or obstructed. For the internal components of lifting system gear sleeves, grease is often applied to the mating surfaces before assembly, causing interference to non-contact optical sensors such as lasers and vision sensors, leading to reading errors and making it difficult to meet measurement accuracy requirements. Moreover, the limited space within the internal arc surfaces and tooth profiles of the components places high demands on sensor size and the measuring device.

[0005] Eddy current displacement sensors offer micron-level measurement accuracy, are unaffected by surface lubricants, and provide non-contact measurement. However, while they typically maintain high accuracy when measuring planar or near-planar metallic conductors, the gear sleeve component in a lift system has a highly curved inner arc surface. Furthermore, the initial tilt of the component causes a misalignment between the eddy current sensor's probe axis and the normal vector of the measured point on the inner arc surface when the sensor is inserted for rotational scanning. These factors all influence the accuracy of eddy current measurements. Therefore, to ensure accurate and reliable measurement of the inner arc surface features inside the main propeller hub, it is crucial to accurately extract the contour information after compensating for sensor measurement errors and quickly calculate the component's assembly posture. Summary of the Invention

[0006] To address the problems existing in the background art, this invention provides a method for adjusting the axial pose of helicopter gear sleeve parts based on eddy current ranging. The technical problem this invention aims to solve is to correct the measurement error caused by the offset of the eddy current displacement sensor probe relative to the inner arc surface feature, accurately extract the inner arc surface feature contour under grease coverage, and calculate the axial pose of the gear sleeve part. This invention method can improve measurement efficiency while ensuring measurement accuracy.

[0007] The technical solution adopted in this invention is:

[0008] The present invention provides a method for adjusting the assembly posture of helicopter gear sleeve parts based on eddy current ranging, comprising:

[0009] Step 1) Build a gear sleeve part pose measurement system including an eddy current displacement sensor and establish a measurement coordinate system.

[0010] Step 2) In the measurement coordinate system, when the eddy current displacement sensor of the gear sleeve part position measurement system is used to measure the inner arc surface feature of the helicopter gear sleeve part, the measurement error is corrected, and then the eddy current correction model is established.

[0011] Step 3) Use the eddy current displacement sensor of the gear sleeve part pose measurement system to perform a rotary scan measurement on the measured point on the gear sleeve part, thereby obtaining the measurement distance and offset of the measured point. Input the measurement distance and offset of the measured point into the eddy current correction model for processing to obtain the true lift-off distance of the measured point. Determine the coordinates of the measured point in the measurement coordinate system based on the rotation radius of the eddy current displacement sensor, the equal interval angle between each measured point on the gear sleeve part, and the true lift-off distance of the measured point.

[0012] Step 4) Use an eddy current displacement sensor to perform a rough measurement on the gear sleeve part. Obtain the axis tilt angle information of the gear sleeve part based on the coordinates of the measured point in the measurement coordinate system, and then obtain the position and pose information of the gear sleeve part in the rough measurement stage.

[0013] Step 5) Based on the position and orientation information of the gear sleeve part in the rough measurement stage and the target assembly position and orientation, use the orientation adjustment device to roughly adjust the relative orientation between the rotation axis of the eddy current displacement sensor and the axis of the gear sleeve part, so that the orientation of the gear sleeve part is adjusted to be close to the target assembly position and orientation.

[0014] Step 6) Use an eddy current displacement sensor to perform a fine measurement on the roughly adjusted gear sleeve part, thereby obtaining the center coordinates of the elliptical cross-sectional profiles of the two inner arc surfaces of the gear sleeve part in the measurement coordinate system.

[0015] Step 7) Calculate the spatial pose of the axis of the gear sleeve part based on the coordinates of the center of the elliptical cross-sectional profile of the two inner arc surfaces of the gear sleeve part, and finally adjust the spatial pose of the axis of the gear sleeve part to the target assembly pose to complete the assembly pose adjustment of the gear sleeve part.

[0016] In step 1), the gear sleeve part pose measurement system further includes a motion control mechanism and a cantilever fixture. The motion control mechanism has at least four degrees of freedom, including three translational degrees of freedom in the spatial rectangular coordinate direction and a rotational degree of freedom about the vertical direction. The end flange of the motion control mechanism is connected to the cantilever fixture, and a locating pin hole is provided on the end flange. The cantilever fixture includes a crossbeam and a longitudinal beam. The end flange of the motion control mechanism is connected to the upper surface of one end of the crossbeam. The radial direction of the end flange is parallel to the length direction of the crossbeam. The lower surface of the crossbeam is provided with a groove along its own length direction. The top end of the longitudinal beam is slidably installed in the groove of the crossbeam, and the longitudinal beam moves along the groove. The cantilever length between the longitudinal beam and the end flange is adjusted by moving the beam. The longitudinal beam is equipped with reinforcing ribs to prevent bending deformation. A through-hole for mounting an eddy current displacement sensor is located at the bottom of the longitudinal beam. The eddy current displacement sensor includes a sensor probe, a sensor connection cable, and a sensor fixing nut. The sensor probe is mounted in the through-hole of the longitudinal beam via the sensor fixing nut. The sensor probe is connected to an external sensor processing device via the sensor connection cable. The orientation of the sensor probe is parallel to the length direction of the beam. The straight-line distance between the center symmetrical point of the locating pin hole on the end flange and the head of the sensor probe serves as the rotation radius r of the eddy current displacement sensor.

[0017] The measurement coordinate system of the gear sleeve part position and posture measurement system takes the center of the base bottom surface of the motion control mechanism as the origin O, the measurement direction along the axis of the eddy current displacement sensor after installation as the X-axis, and the vertically upward direction as the Z-axis, and establishes a right-hand rectangular coordinate system O-XYZ.

[0018] Step 2) is as follows:

[0019] Step 2.1) Move the eddy current displacement sensor into the gear sleeve part using the motion control mechanism. Several measurement points are set at equal intervals on the inner surface of the gear sleeve part. Center the sensor probe of the eddy current displacement sensor. Move the sensor probe step by step along the X and Y axes of the measurement coordinate system in the gear sleeve part using the motion control mechanism to determine the range of the eddy current displacement sensor. Ensure that the eddy current displacement sensor is within the range during movement. At the same time, make the axis of the sensor probe coincide with the normal vector of the currently measured point.

[0020] Step 2.2) Use an eddy current displacement sensor to measure the inner arc surface feature of the gear sleeve part. Change the lift-off distance h and offset δ of the sensor probe relative to the measured point in the plane XOY. The lift-off distance is the actual distance between the sensor probe surface and the measured point. At this time, due to the influence of the curved surface and offset, the measured distance H of the sensor probe is not equal to the actual lift-off distance. Calibrate the N offsets of the same inner arc surface feature under M lift-off distances to obtain the M×N sensor probe measurement distances H(m,n) and sensor lift-off distances h(m,n), where m=1, 2, …, M, n=1, 2, …, N.

[0021] Step 2.3) For each offset, perform a second-order polynomial fitting on all M types of lift-off distance h and measurement distance H under the current offset to obtain the second-order polynomial fitting result of the offset. The second-order polynomial fitting result of the offset is h(m,n)=A ε (n)·H(m,n) 2 +B ε (n)·H(m,n)+C ε (n), the first polynomial parameter A of the nth offset is obtained based on the second-order polynomial fitting result. ε (n), parameter B of the second polynomial ε (n) and the third polynomial parameter C ε (n).

[0022] Step 2.4) For each offset, adjust the first polynomial parameter A of the current offset. ε (n), parameter B of the second polynomial ε (n) and the third polynomial parameter C ε (n) Perform a second-order polynomial fitting to obtain the parameters A of the first polynomial. ε (n), parameter B of the second polynomial ε (n) and the third polynomial parameter C ε The second-order polynomial fitting result of (n), the first polynomial parameter A ε The second-order polynomial fitting result A of (n) ε ′(n), A ε ′(n)=A ε0 ·T(n) 2 +A ε1 ·T(n)+A ε2 The second polynomial parameter B ε The second-order polynomial fitting result B of (n) ε ′(n), B ε ′(n)=B ε0 ·T(n) 2 +B ε1 ·T(n)+B ε2 The third polynomial parameter Cε The second-order polynomial fitting result C of (n) ε ′(n), C ε ′(n)=C ε0 ·T(n) 2 +C ε1 ·T(n)+C ε2 Thus, the first intermediate correction parameter A is obtained. ε0 Second intermediate correction parameter A ε1 Third intermediate correction parameter A ε2 Fourth intermediate correction parameter B ε0 Fifth intermediate correction parameter B ε1 Sixth intermediate correction parameter B ε2 Seventh intermediate correction parameter C ε0 Eighth intermediate correction parameter C ε1 and the ninth intermediate correction parameter C ε2 , where T(n) is the offset distance of the nth offset.

[0023] Step 2.5) When using an eddy current displacement sensor to perform a rotary scanning measurement on the inner arc surface features of the gear sleeve part, the measurement distance H of the sensor probe is obtained. At the same time, based on the offset δ of the sensor probe relative to the measured point in the plane XOY and the nine intermediate correction parameters δ in step 2.4), an eddy current correction model is established. The actual lift-off distance h after eddy current correction can be obtained based on the eddy current correction model.

[0024] In step 2.5), the eddy current correction model is as follows:

[0025] h = A ε ′(n)·H 2 +B ε ′(n)·H+C ε ′(n)

[0026] A ε ′(n)=A ε0 ·δ 2 +A ε1 ·δ+A ε2

[0027] B ε ′(n)=B ε0 ·δ 2 +B ε1 ·δ+B ε2

[0028] C ε ′(n)=C ε0 ·δ 2 +C ε1 ·δ+C ε2

[0029] Where h is the actual lift-off distance of the sensor probe relative to the measured point in the XOY plane.

[0030] Step 3) specifically involves the following steps: In the axial pose measurement of the gear sleeve component, the motion control mechanism drives the sensor probe to perform a rotary scan, simultaneously acquiring the sensor probe's measurement data, including the sensor probe's measurement distance H and the offset δ relative to the measured point in the XOY plane. The sensor probe's measurement data is then input into an eddy current correction model for processing. After processing, the eddy current correction model outputs the sensor probe's true lift-off distance h relative to the measured point in the XOY plane. Based on the sensor probe's true lift-off distance h relative to the measured point in the XOY plane, the sensor probe's rotation radius r, and the equal-interval angle θ between each measured point, the coordinates of the measured point in the measurement coordinate system are determined, as follows:

[0031]

[0032] Where, x i and y i Let X and Y be the coordinates of the i-th measured point in the measurement coordinate system, i = 1, 2, ..., I, where I is the total number of measured points on the cross section of the inner arc surface of the gear sleeve part in the measurement coordinate system, and I = 360 / θ.

[0033] The measured point refers to the three-dimensional coordinates (x, y, z) of a discrete point uniformly distributed on the inner arc surface feature of the gear sleeve part, measured by an eddy current displacement sensor in the coordinate system O-XYZ. i y i , z i ), where i is the index of the discrete point; z i The coordinates are determined by the position of the end flange of the motion control mechanism and the geometric dimensions of the cantilever fixture in the Z-axis direction. The position of the end flange changes as the motion control mechanism moves and can be read directly. The geometric dimensions are fixed lengths and are obtained through measurement.

[0034] Step 4) is as follows:

[0035] Step 4.1) In the rough measurement stage of the gear sleeve part, the sensor probe rotates around the rotation axis of the gear sleeve part once. The rotation section of the gear sleeve part is parallel to the measurement coordinate system XOY. Under normal circumstances, the gear sleeve part is in an inclined state. The rotation section of the gear sleeve part intersects with the inner cylindrical surface of the gear sleeve part to form an elliptical profile.

[0036] Ellipse fitting is performed on a single measured point on the cross-section of the elliptical profile to obtain the coefficients (A) of the elliptical profile. γ B γ C γ Dγ E γ F γ Thus, the ellipse can be determined; besides being represented by an algebraic equation, an ellipse can also be determined by the coordinates of its center (x, y). ci y Ci ), the semi-major axis r of the ellipse a , short half-shaft r b The five geometric parameters, namely the angle β between the major axis and the X-axis, are uniquely determined.

[0037] Specifically, by using the direct least squares method for elliptic algebraic fitting, the coefficients of each term in the algebraic equation of the ellipse can be obtained by minimizing the following objective function J (A). γ B γ C γ D γ E γ F γ ):

[0038]

[0039] Among them, A γ B γ C γ D γ E γ and F γ These are the first, second, third, fourth, and fifth coefficients of the algebraic equation of the ellipse.

[0040] Step 4.2) Based on the radius of curvature R of the inner arc surface of the gear sleeve part and the geometric parameters of the elliptical profile, obtain the angle between the cross section containing the elliptical profile of the gear sleeve part and the circular cross section passing through the center of the elliptical profile. This allows us to obtain the axial tilt angle information of the gear sleeve component. However, we can only obtain the degree of tilt of the gear sleeve component, but we cannot adjust it.

[0041] Step 4.3) Based on the axial tilt angle information of the gear sleeve part and the minor axis direction vector of the elliptical profile... Determine the direction vector of the axis of the gear sleeve component. And the coordinates C of the center of the elliptical profile on the axis. c =(x Ci y Ci , z Ci ), s1, s2, and s3 are the projections of the direction vector of the axial direction of the gear sleeve part onto the X, Y, and Z axes of the measurement coordinate system, respectively. Ci y Ci and z Ci The center C of the elliptical outline is respectively cIn the measurement coordinate system, the X, Y, and Z axes are used. The rotation axis of the eddy current displacement sensor is parallel to the Z-axis of the measurement coordinate system. The unit vector of the rotation axis of the eddy current displacement sensor is... minor axis direction vector of the elliptical profile Based on the geometric parameters of the ellipse, the final positional information of the axis of the gear sleeve part during the roughing stage is determined.

[0042] Step 6) specifically involves moving the sensor probe of an eddy current displacement sensor along the vertical rotation axis, selecting elliptical cross-sectional profiles at the upper and lower points of the gear sleeve part that are parallel to the plane XOY, performing elliptical least-squares fitting on each elliptical cross-sectional profile to obtain the center position of each elliptical cross-sectional profile, and adding the Z coordinate of its corresponding cross-section to the center of each elliptical cross-sectional profile to obtain the spatial coordinates C1 = (x... 11 y 11 , z 11 ) and C2=(x 22 y 22 , z 22 ), where x 11 y 11 and z 11 Let x, Y, and Z be the X, Y, and Z coordinates of the center of the first elliptical cross-section profile in the measurement coordinate system. 22 y 22 and z 22 These are the X, Y, and Z coordinates of the center of the second elliptical cross-section profile in the measurement coordinate system. According to spatial geometry theory, the straight line L formed by connecting the spatial coordinates of the centers of the two elliptical cross-section profiles... C Theoretically, it should coincide with the axis of the gear sleeve component.

[0043] Step 7) specifically refers to the fact that the axis of the gear sleeve part is a straight line in space, and its direction is related to the direction vector. Similarly, based on the coordinates of the centers of the elliptical cross-sectional profiles of the two inner arc surfaces of the gear sleeve component, the spatial equation of the gear sleeve component's axis is determined as follows:

[0044]

[0045] p = s1 / s3

[0046] q = s² / s³

[0047] Where x, y, and z are the X, Y, and Z axis coordinates of a point on the axis of the gear sleeve part in the measurement coordinate system, respectively; p and q are the first and second direction vector parameters, respectively; x0 and y0 are the X and Y axis coordinates of the intersection point C0 of the axis of the gear sleeve part and the XOY plane of the measurement coordinate system, respectively, and z0 = 0; s1, s2, and s3 are the direction vectors of the axis of the gear sleeve part. Projection along the X, Y, and Z axes of the measurement coordinate system.

[0048] For the measurement requirements of the axis of the inner cylindrical surface feature, it is necessary to determine the direction of the axis. The cylinder moving up and down along the axis and rotating around its own axis will not affect the measurement result of the axis. Therefore, the axis equation is simplified by setting the point through which the axis passes on the XOY plane of the measurement coordinate system, i.e., z0 = 0. Let p = s1 / s3 and q = s2 / s3, and a simplified expression of the spatial equation of the axis can be obtained.

[0049] After inputting the coordinates of the centers of the elliptical cross-sectional profiles of the two inner arc surfaces of the gear sleeve into the spatial equation of the gear sleeve, the coordinates of the intersection point C0 of the axis of the gear sleeve and the XOY plane of the measurement coordinate system, as well as the direction vector of the axis of the gear sleeve, are obtained. Specifically as follows:

[0050]

[0051] Where, x 11 y 11 and z 11 These are the X, Y, and Z coordinates of the center C1 of the first elliptical cross-section profile in the measurement coordinate system, respectively. 22 y 22 and z 22 These are the X, Y, and Z coordinates of the center C2 of the second elliptical cross-section profile in the measurement coordinate system.

[0052] The coordinates of the intersection point C0 of the axis of the gear sleeve component and the XOY plane of the measurement coordinate system, and the direction vector of the axis of the gear sleeve component are determined. The positional parameters of the axis of the gear sleeve component are used to determine the spatial positional parameters of the axis of the gear sleeve component.

[0053] The electronic device of the present invention includes: a memory and a processor coupled to each other, wherein the memory stores program data, and the processor invokes the program data to execute the method described above.

[0054] The present invention provides a computer-readable storage medium having program data stored thereon, which, when executed by a processor, implements the method described above.

[0055] The beneficial effects of this invention are:

[0056] 1. This invention uses an eddy current displacement sensor to perform a rotary scan of the inner arc surface features of a gear sleeve component around its rotation axis, acquiring point cloud information of the component's surface. In the coarse measurement stage, an elliptical profile is obtained by intersecting the sensor's rotating cross-section with the measured component. After preliminary calculation and adjustment of the component's tilt angle and coarse measurement axis pose information, the fine measurement stage obtains the elliptical profiles obtained by intersecting two parallel cross-sections with the measured component. The axis pose information is calculated using the center coordinates, avoiding the problems of low accuracy in single measurements and low efficiency in repeated measurements.

[0057] 2. This invention uses an eddy current displacement sensor to assist a motion control mechanism in scanning a part by rotation, and processes the point cloud data acquired during the scan to calculate the part's axial pose. Applying this invention, the spatial pose of metal parts of arbitrary size with inner arc surface features can be measured. Compared to existing measurement methods that require the installation and pasting of targets, the measurement process does not involve contact with the part being measured, thus avoiding damage to the part's surface. Furthermore, for products measured in large quantities, the target installation or pasting process is eliminated, improving measurement efficiency. Compared to measurement methods that rely on laser sensors to extract contours or industrial cameras to capture images, eddy current sensors are unaffected by grease or grease on the measured surface.

[0058] In summary, the method of the present invention aims to correct the eddy current measurement error of the inner arc surface feature under the premise of no target, non-contact and unaffected by grease, improve the measurement accuracy and efficiency of the assembly posture of gear sleeve parts, and can be used for high-precision measurement and adjustment of the axial posture of parts in the automated assembly process of gear sleeve parts. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the gear sleeve part pose measurement system of the present invention;

[0060] Figure 2 This is a schematic diagram of the installation of the end flange and cantilever fixture of the motion control mechanism of the present invention.

[0061] Figure 3 This is a flowchart illustrating the implementation of the axis pose measurement method of the present invention.

[0062] Figure 4 This is a schematic diagram of the inner arc surface feature calibration of the present invention;

[0063] Figure 5 This is a schematic diagram showing the alignment of the sensor axis and the normal vector of the measured point after centering processing according to the present invention.

[0064] Figure 6 This is a schematic diagram of the measurement error of the inner arc surface of the eddy current before correction according to the present invention;

[0065] Figure 7 This is a schematic diagram of the sensor output characteristics after eddy current measurement error correction according to the present invention;

[0066] Figure 8 This is a schematic diagram illustrating the principle of the coarse axis measurement stage of the present invention;

[0067] Figure 9 This is a schematic diagram illustrating the principle of the axis precision measurement stage of the present invention;

[0068] In the diagram: 1. Motion control mechanism, 2. Cantilever fixture, 21. Crossbeam, 22. Longitudinal beam, 3. Eddy current displacement sensor, 4. Gear sleeve component. Detailed Implementation

[0069] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0070] like Figure 1 and Figure 2 As shown, the gear sleeve part pose measurement system constructed by this invention includes a motion control mechanism 1, a cantilever fixture 2, and an eddy current displacement sensor 3. The motion control mechanism 1 has at least four degrees of freedom, including three translational degrees of freedom in the spatial rectangular coordinate direction and a rotational degree of freedom about the vertical direction. The end flange of the motion control mechanism 1 is connected to the cantilever fixture 2, and a positioning pin hole is provided on the end flange. The cantilever fixture 2 includes a crossbeam 21 and a longitudinal beam 22. The end flange of the motion control mechanism 1 is connected to the upper surface of one end of the crossbeam 21. The radial direction of the end flange is parallel to the length direction of the crossbeam 21. The lower surface of the crossbeam 21 is provided with a groove along its own length direction. The top end of the longitudinal beam 22 is slidably installed in the groove of the crossbeam 21. The longitudinal beam 22 moves along the groove. The cantilever length between the longitudinal beam 22 and the end flange is adjusted by moving the longitudinal beam 22. The longitudinal beam 22 is equipped with reinforcing ribs to prevent bending deformation. A through hole for mounting the eddy current displacement sensor 3 is provided at the bottom of the longitudinal beam 22. The eddy current displacement sensor 3 includes a sensor probe 31, a sensor connection cable 32, and a sensor fixing nut 33. The sensor probe 31 is mounted in the through hole of the longitudinal beam 22 via the sensor fixing nut 33. The sensor probe 31 is connected to an external sensor processing device via the sensor connection cable 32. The orientation of the sensor probe 31 is parallel to the length direction of the crossbeam 21. The straight-line distance between the center symmetrical point of the positioning pin hole on the end flange and the head of the sensor probe 31 is used as the rotation radius r of the eddy current displacement sensor 3. The internal dimensions and shape of the gear sleeve part 4 are exactly the same as the internal features of the main propeller hub, with inner arc surface features at the top and bottom, and a toothed spline profile feature in the middle. Preferably, the motion control mechanism 1 uses an industrial robot with six degrees of freedom in space and high motion accuracy.

[0071] The working principle of this invention is as follows:

[0072] The end flange of the motion control mechanism 1 of the present invention is fixedly connected to the cantilever fixture 2, and the movable direction of the longitudinal beam 22 is collinear with the X-axis movement direction of the motion control mechanism 1 through pin hole positioning. The eddy current displacement sensor 3 is installed on the longitudinal beam 22, which ensures that the axis of the eddy current displacement sensor 3 passes through the rotation axis of the end flange of the motion control mechanism 1. In the initial position, the measurement direction of the eddy current displacement sensor 3 is the same as the X-axis direction of the motion control mechanism 1. Since the eddy current displacement sensor 3 measures the area covered by the sensor probe 31, when rotating to measure the inner arc surface feature of the inclined gear sleeve part 4, the sensor probe 31 cannot be guaranteed to be directly facing the measured area. Its axis is offset from the normal vector direction of the measured point, which introduces measurement error. Therefore, calibration is required. The eddy current displacement sensor 3 is controlled to acquire measurement values ​​at different offsets along the offset direction. The eddy current displacement sensor 3 is controlled to move along the lifting direction to acquire measurement values ​​at different lifting distances. The actual distance between the surface of the sensor probe 31 of the eddy current displacement sensor 3 and the surface of the toothed sleeve part 4 being measured is the true value. The output voltage of the eddy current displacement sensor 3 is converted according to the sensor sensitivity coefficient to obtain the measurement value of this distance. Therefore, a relationship curve between the true value and the measured value can be established to correct the measurement error.

[0073] When measuring the axial pose of a gear sleeve part 4 with an unknown orientation, the end effector of the motion control mechanism 1 is controlled to move. The cantilever fixture 2 drives the eddy current displacement sensor 3 deeper into the gear sleeve part 4, aligning it with the upper inner arc surface feature for a rotary scan to obtain the cross-sectional profile. Based on spatial geometry, this profile is ellipse. By fitting the ellipse, the equation of the elliptic curve is obtained, and further transformation yields the elliptic geometric parameters, allowing for a preliminary solution to the axial pose of the gear sleeve part 4. The pose of the gear sleeve part 4 is adjusted so that its axis coincides with the rotation axis of the eddy current displacement sensor 3. At this point, the upper and lower inner arc surface features are precisely measured, and again, an ellipse is fitted to obtain the coordinates of the elliptic center of the two cross-sections, ultimately yielding the axial pose of the gear sleeve part 4.

[0074] Specific embodiments of the present invention are as follows:

[0075] like Figure 3 The diagram shows the implementation flow of the helicopter gear sleeve component axis pose adjustment method based on eddy current ranging proposed in this invention, which includes the following steps:

[0076] Step 1: Establish a measurement coordinate system.

[0077] The measurement coordinate system of the gear sleeve part position and posture measurement system takes the center of the base bottom surface of the motion control mechanism 1 as the origin O, the measurement direction along the axis of the eddy current displacement sensor 3 after installation as the X-axis, and the vertically upward direction as the Z-axis, and establishes a right-hand rectangular coordinate system O-XYZ.

[0078] Step 2: Correction of measurement error for the inner arc surface feature measured by eddy current displacement sensor 3.

[0079] In the measurement coordinate system, when the eddy current displacement sensor 3 of the gear sleeve part position measurement system measures the inner arc surface features of the helicopter gear sleeve part 4, measurement error correction is performed, and then an eddy current correction model is established.

[0080] 1) The motion control mechanism 1 moves the eddy current displacement sensor 3 into the gear sleeve part 4. Several measurement points are arranged at equal intervals on the inner surface of the gear sleeve part 4. The sensor probe 31 of the eddy current displacement sensor 3 is centered. The motion control mechanism 1 moves the sensor probe 31 in the gear sleeve part 4 along the X and Y axes of the measurement coordinate system. First, along the X-axis, the measured value is placed in the middle range of the measurement range. Then, along the Y-axis, after moving 1mm, the measured value corresponding to the current position is read and compared with the measured values ​​of the two positions before and after. When the measured value at the current position is greater than the measured values ​​at the two positions on both sides, the step size is halved, and the sensor probe 31 moves again within the range between the two positions until it moves to the minimum movement resolution of the motion control mechanism 1. The sensor probe 31 is then positioned at the position where the measured value of the sensor probe 31 is maximum, ensuring that the eddy current displacement sensor 3 is within the measurement range during movement. At this time, the axis of the sensor probe 31 coincides with the normal vector of the currently measured point. Figure 5 As shown.

[0081] 2) The inner arc surface feature of the gear sleeve part 4 is measured using an eddy current displacement sensor 3. The motion control mechanism 1 drives the sensor probe 31 to move along the lifting direction and the offset direction, changing the lifting distance h and offset δ of the sensor probe 31 relative to the measured point in the plane XOY. The lifting distance is the true distance between the surface of the sensor probe 31 and the measured point. At this time, due to the influence of the curved surface and the offset, the measured distance H of the sensor probe 31 is not equal to the true lifting distance. The offset of the same inner arc surface feature under M lifting distances is calibrated to obtain M×N kinds of sensor probe 31 measurement distance H(m,n) and sensor lifting distance h(m,n), where m=1,2,...,M, n=1,2,...,N.

[0082] 3) For each offset, perform a second-order polynomial fitting on all M types of lift-off distances h and measurement distances H under the current offset to obtain the second-order polynomial fitting result of the offset. The second-order polynomial fitting result of the offset is h(m,n)=A ε (n)·H(m,n) 2 +B ε (n)·H(m,n)+C ε (n), the first polynomial parameter A of the nth offset is obtained based on the second-order polynomial fitting result. ε(n), parameter B of the second polynomial ε (n) and the third polynomial parameter C ε (n).

[0083] 4) For each offset, the first polynomial parameter A of the current offset is... ε (n), parameter B of the second polynomial ε (n) and the third polynomial parameter C ε (n) Perform a second-order polynomial fitting to obtain the parameters A of the first polynomial. ε (n), parameter B of the second polynomial ε (n) and the third polynomial parameter C ε The second-order polynomial fitting result of (n), the first polynomial parameter A ε The second-order polynomial fitting result A of (n) ε ′(n), A ε ′(n)=A ε0 ·T(n) 2 +A ε1 ·T(n)+A ε2 The second polynomial parameter B ε The second-order polynomial fitting result B of (n) ε ′(n), B ε ′(n)=B ε0 ·T(n) 2 +B ε1 ·T(n)+B ε2 The third polynomial parameter C ε The second-order polynomial fitting result C of (n) ε ′(n), C ε ′(n)=C ε0 ·T(n) 2 +C ε1 ·T(n)+C ε2 Thus, the first intermediate correction parameter A is obtained. ε0 Second intermediate correction parameter A ε1 Third intermediate correction parameter A ε2 Fourth intermediate correction parameter B ε0 Fifth intermediate correction parameter B ε1 Sixth intermediate correction parameter B ε2 Seventh intermediate correction parameter C ε0 Eighth intermediate correction parameter C ε1 and the ninth intermediate correction parameter C ε2 , where T(n) is the offset distance of the nth offset.

[0084] 5) When using the eddy current displacement sensor 3 to perform a rotary scanning measurement on the inner arc surface feature of the gear sleeve part 4, the measurement distance H of the sensor probe 31 is obtained. Simultaneously, based on the offset δ of the sensor probe 31 relative to the measured point in the XOY plane and the nine intermediate correction parameters δ from step 2.4), an eddy current correction model is established. The actual lift-off distance h after eddy current correction can be obtained from the eddy current correction model. The specific eddy current correction model is as follows:

[0085] h = A ε ′(n)·H 2 +B ε ′(n)·H+C ε ′(n)

[0086] A ε ′(n)=A ε0 ·δ 2 +A ε1 ·δ+A ε2

[0087] B ε ′(n)=B ε0 ·δ 2 +B ε1 ·δ+B ε2

[0088] C ε ′(n)=C ε0 ·δ 2 +C ε1 ·δ+C ε2

[0089] Where h is the actual lift-off distance of the sensor probe 31 relative to the measured point in the XOY plane.

[0090] The actual distance h after eddy current correction can then be obtained based on the eddy current correction model. The above method is used to correct an inner circular arc surface with a radius of curvature of 90.5 mm, as follows: Figure 4 As shown, the lift-off distance h is set to a range of 2-7 mm with a step size of 0.5 mm, resulting in 11 different lift-off distances; the offset δ varies from 0-9 mm with a variation interval of 1 mm, resulting in 10 different offsets. The sensor probe 31 has a diameter of 16 mm.

[0091] During the calibration process, the lift-off distance h changes within the range of 2-7 mm, and the offset δ varies within the range of 0-9 mm. Figure 6 As shown, this illustrates the measurement error present when the sensor probe 31 measures the inner arc surface without calibration. This error is influenced by both the curvature of the inner arc and the offset of the sensor probe 31. The maximum measurement error without calibration is -1.44 mm. Figure 7As shown, the output characteristic curve of the lift-measurement distance of the eddy current displacement sensor after correction is shown. The measurement error range of the corrected sensor probe 31 is within ±0.017mm. It can be seen that the eddy current measurement error of the large curvature inner arc surface is significantly reduced after correction, which meets the accuracy requirements for contour extraction of the gear sleeve part 4.

[0092] Step 3: Rotary scanning measurement using eddy current displacement sensor 3.

[0093] In the embodiment of the axial pose measurement of the gear sleeve part 4, the end flange of the motion control mechanism 1 rotates, and the sensor probe 31 is connected to the flange through the cantilever fixture 2. The motion control mechanism 1 can send rotation commands to drive the sensor probe 31 to rotate, and simultaneously send refresh and measurement commands to the sensor probe 31 to acquire the measurement data of the sensor probe 31 in real time. Furthermore, the rotation radius r of the sensor probe 31, the equal interval angle θ between the measured points, and the calibrated actual measurement distance h of the sensor probe 31 can also be input.

[0094] First, the eddy current displacement sensor 3 of the gear sleeve part pose measurement system is used to perform a rotary scan measurement on the measured point on the gear sleeve part 4 to obtain the measurement distance and offset of the measured point. The measurement distance and offset of the measured point are then input into the eddy current correction model for processing to obtain the actual lift-off distance of the measured point. The coordinates of the measured point in the measurement coordinate system are determined based on the rotation radius of the eddy current displacement sensor 3, the equal interval angle between each measured point on the gear sleeve part 4, and the actual lift-off distance of the measured point.

[0095] In the axial pose measurement of the gear sleeve part 4, the motion control mechanism 1 drives the sensor probe 31 to perform a rotary scan, synchronously acquiring the measurement data of the sensor probe 31, including the measurement distance H of the sensor probe 31 and the offset δ of the relative measured point in the XOY plane. The measurement data of the sensor probe 31 is input into the eddy current correction model for processing. After processing, the eddy current correction model outputs the true lift-off distance h of the sensor probe 31 relative to the measured point in the XOY plane. Based on the true lift-off distance h of the sensor probe 31 relative to the measured point in the XOY plane, the rotation radius r of the sensor probe 31, and the equal interval angle θ between each measured point, the coordinates of the measured point in the measurement coordinate system are determined, as follows:

[0096]

[0097] Where, x i and y i Let X and Y be the coordinates of the i-th measured point in the measurement coordinate system, i = 1, 2, ..., I, and I be the total number of measured points on the cross section of the inner arc surface of the gear sleeve part 4 in the measurement coordinate system, I = 360 / θ.

[0098] The measured point refers to the three-dimensional coordinates (x, y, z) of a discrete point uniformly distributed on the inner arc surface feature of the gear sleeve part 4, measured by the eddy current displacement sensor 3 in the coordinate system O-XYZ. i y i , z i ), where i is the index of the discrete point; z i The coordinates are determined by the position of the end flange of the motion control mechanism 1 and the geometric dimensions of the cantilever fixture 2 in the Z-axis direction. The position of the end flange changes as the motion control mechanism 1 moves and can be read directly. The geometric dimensions are fixed lengths and are obtained through measurement.

[0099] Step 4: Roughly measure and obtain the axial tilt angle information of the gear sleeve part 4.

[0100] The gear sleeve component 4 is roughly measured using an eddy current displacement sensor 3. The tilt angle of the axis of the gear sleeve component 4 is obtained based on the coordinates of the measured point in the measurement coordinate system, thereby obtaining the pose information of the gear sleeve component 4 during the rough measurement stage, as detailed below:

[0101] 1) During the rough measurement stage of the gear sleeve part 4, the sensor probe 31 rotates around the rotation axis of the gear sleeve part 4. The rotation section of the gear sleeve part 4 is parallel to the measurement coordinate system XOY. Under normal circumstances, the gear sleeve part 4 is in an inclined state. The rotation section of the gear sleeve part 4 intersects the inner cylindrical surface of the gear sleeve part 4 to form an elliptical profile.

[0102] Ellipse fitting is performed on a single measured point on the cross-section of the elliptical profile to obtain the coefficients (A) of the elliptical profile. γ B γ C γ D γ E γ F γ Thus, the ellipse can be determined; besides being represented by an algebraic equation, an ellipse can also be determined by the coordinates of its center (x, y). Ci y Ci ), the semi-major axis r of the ellipse a , short half-shaft r b The five geometric parameters—the angle β between the major axis and the X-axis—are uniquely determined. The coefficients of the algebraic equation can be converted into the required geometric parameters using the following formula:

[0103]

[0104] Specifically, by using the direct least squares method for elliptic algebraic fitting, the coefficients of each term in the algebraic equation of the ellipse can be obtained by minimizing the following objective function J (A). γ B γ C γ D γ E γ Fγ ):

[0105]

[0106] Among them, A γ B γ C γ D γ E γ and F γ These are the first, second, third, fourth, and fifth coefficients of the algebraic equation of the ellipse.

[0107] 2) such as Figure 8 As shown, a rotary scan is performed on the upper inner arc surface of the gear sleeve part 4. Based on the radius of curvature R of the inner arc surface of the gear sleeve part 4 and the geometric parameters of the elliptical profile, the angle between the cross section containing the elliptical profile of the gear sleeve part 4 and the circular cross section passing through the center of the elliptical profile is obtained. According to the three perpendiculars theorem, we can obtain:

[0108]

[0109] Where R is the radius of curvature of the inner arc surface being measured, which can be obtained by measuring the inner diameter.

[0110] According to the included angle This allows us to obtain the axial tilt angle information of the gear sleeve part 4; at this time, we can only obtain the tilt degree of the gear sleeve part 4, but we cannot adjust it.

[0111] 3) Based on the axial tilt angle information of the gear sleeve part 4 and the minor axis direction vector of the elliptical profile Determine the direction vector of the axis of the gear sleeve part 4. And the coordinates C of the center of the elliptical profile on the axis. c =(x Ci y Ci , z Ci ), s1, s2, and s3 are the projections of the direction vector of the axial direction of the gear sleeve part 4 onto the X, Y, and Z axes of the measurement coordinate system, respectively. Ci y Ci and z Ci The center C of the elliptical outline is respectively c In the measurement coordinate system, the X, Y, and Z axes are used. The rotation axis of the eddy current displacement sensor 3 is parallel to the Z-axis of the measurement coordinate system. The unit vector of the rotation axis of the eddy current displacement sensor 3 is... minor axis direction vector of the elliptical profile Based on the geometric parameters of the ellipse, the positional information of the axis of the gear sleeve part 4 during the roughing stage is finally determined.

[0112] When determining the pose information of the axis of the gear sleeve part 4 during the roughing stage, the direction vector of the axis of the gear sleeve part 4 can be set as follows: The axis of rotation is parallel to the Z-axis of the measurement coordinate system, and the unit vector of the axis of rotation is... Inclination angle of gear sleeve part 4 Expressed in the form of a vector dot product:

[0113]

[0114] The coordinates of the two endpoints A and E on the minor axis of the ellipse are (x, y, y) and (x, y, y) respectively. Ci -r b sinβ, y Ci +r b cosβ, z Ci ) and (x Ci +r b sinβ, y Ci -r b cosβ, z Ci ), where z Ci Equal to the z-axis of the sensor probe 31 at the current rotation time i Coordinates, direction vector of the minor axis Represented as (sinβ, -cosβ, 0), any straight line passing through the center of the circular cross-section of the gear sleeve part 4 is perpendicular to the axis of the gear sleeve part 4. Therefore, by We can obtain:

[0115] The direction vector of the axis can be finally obtained as follows: s1sinβ-s2cosβ=0

[0116]

[0117] At this point, the direction vector of the line is obtained. And a point on the line, i.e., the center of the circle (x Ci ,y Ci ,z Ci The coordinates of the part can be used to determine the pose information of the part's axis obtained during the roughing stage.

[0118] The axial pose of the gear sleeve part 4 under five different orientations was measured using a coarse measurement method. The measurement results are as follows:

[0119] Table 1 shows the measurement results of the elliptical parameters of the upper inner arc surface.

[0120] Group <![CDATA[r a / mm]]> <![CDATA[r b / mm]]> β / ° x / mm y / mm z / mm 1 90.501 90.502 28.490 350.234 -1.919 350 2 90.523 90.494 -62.669 348.807 -0.0400 350 3 90.625 90.495 18.713 348.925 1.477 350 4 90.602 90.503 59.761 348.835 -1.654 350 5 90.541 90.496 29.545 350.128 -1.052 350

[0121] Table 2. Axis pose information of gear sleeve parts obtained from rough measurement.

[0122]

[0123] Step 5: Adjust the relative position of the sensor probe 31 and the gear sleeve part 4 being tested.

[0124] Based on the position and orientation information of the gear sleeve part 4 during the rough measurement stage and the target assembly position and orientation, the relative position and orientation between the rotation axis of the eddy current displacement sensor 3 and the axis of the gear sleeve part 4 are roughly adjusted using an orientation adjustment device, so that the position and orientation of the gear sleeve part 4 are adjusted to be close to the target assembly position and orientation.

[0125] After the coarse measurement stage of the gear sleeve part 4 is completed, the measured pose information can be converted into motion data of the attitude adjustment device. The attitude adjustment device drives the gear sleeve part 4 to make corresponding adjustments, gradually bringing it closer to the assembly pose. Due to the positioning error of the attitude adjustment device, a second measurement is required to verify the pose of the gear sleeve part 4 after attitude adjustment.

[0126] After initial adjustments, the gear sleeve component 4 is close to its assembly position, with a very small angle of inclination on its axis. For example, the angle between the rotation axis of the eddy current displacement sensor 3 and the axis of the gear sleeve component 4 is very small. When measuring the inner arc surface with a radius of curvature of 90.5 mm, it can be found that the difference between the major axis and minor axis of the ellipse trajectory is only 0.007 mm, that is, the difference between the major axis and minor axis of the ellipse profile is only 0.04‰ of the minor axis length. At this time, due to the limitation of the fitting of a single ellipse parameter on the solution of the axis inclination angle of the gear sleeve part 4, the reliability of the coarse measurement method to solve the axis pose of the gear sleeve part 4 is greatly reduced, and it is more susceptible to the influence of the fitting error of the ellipse deflection angle β. Therefore, the coarse measurement method cannot be verified and needs to enter the next fine measurement stage.

[0127] Step 6: Accurately measure and obtain the center of the profile of section 4 of the gear sleeve part.

[0128] like Figure 9 As shown, the eddy current displacement sensor 3 is used to perform fine measurement on the roughly adjusted gear sleeve part 4. The inner arc surfaces at the top and bottom of the gear sleeve part 4 are rotated and measured to obtain the center coordinates of the elliptical cross-sectional profiles of the two inner arc surfaces of the gear sleeve part 4 in the measurement coordinate system, thus completing the fine measurement of the axis pose, as follows:

[0129] Using the eddy current displacement sensor 3, the sensor probe 31 moves along the vertical rotation axis, selecting elliptical cross-sectional profiles at the upper and lower inner arc surfaces of the gear sleeve part 4 that are parallel to the plane XOY. Elliptical least-squares fitting is performed on each elliptical cross-sectional profile to obtain the center position of each profile. The Z-coordinate of the cross-section is added to the center of each elliptical cross-sectional profile to obtain the spatial coordinates C1 = (x... 11 ,y 11 ,z 11 ) and C2=(x 22 ,y 22 ,z22 ), where x 11 y 11 and z 11 Let x, Y, and Z be the X, Y, and Z coordinates of the center of the first elliptical cross-section profile in the measurement coordinate system. 22 y 22 and z 22 These are the X, Y, and Z coordinates of the center of the second elliptical cross-section profile in the measurement coordinate system. According to spatial geometry theory, the straight line L formed by connecting the spatial coordinates of the centers of the two elliptical cross-section profiles... C Theoretically, it should coincide with the axis of the gear sleeve part 4.

[0130] The results of measuring the inner arc surfaces at the top and bottom of the gear sleeve part 4 using the precision measurement method are shown in the table below, which can obtain the spatial coordinates of the centers of the two ellipses.

[0131] Table 3. Results of Ellipse Center Measurement During the Precision Measurement Phase

[0132]

[0133] Step 7: Calculate the axial pose parameters of the gear sleeve part 4.

[0134] The spatial pose of the axis of the gear sleeve part 4 is calculated based on the coordinates of the center of the elliptical cross-sectional profile of the two inner arc surfaces of the gear sleeve part 4. Finally, the spatial pose of the axis of the gear sleeve part 4 is adjusted to the target assembly pose, thus completing the assembly pose adjustment of the gear sleeve part 4.

[0135] The axis of gear sleeve part 4 is a straight line in space, and its direction is related to the direction vector. Similarly, based on the coordinates of the centers of the elliptical cross-sectional profiles of the two inner arc surfaces of the gear sleeve part 4, the spatial equation of the axis of the gear sleeve part 4 is determined as follows:

[0136]

[0137] p = s1 / s3

[0138] q = s² / s³

[0139] Where x, y, and z are the X, Y, and Z axis coordinates of a point on the axis of the gear sleeve part 4 in the measurement coordinate system, respectively; p and q are the first and second direction vector parameters, respectively; x0 and y0 are the X and Y axis coordinates of the intersection point C0 of the axis of the gear sleeve part 4 and the XOY plane of the measurement coordinate system, respectively, and z0 = 0; s1, s2, and s3 are the direction vectors of the axis of the gear sleeve part 4. Projection along the X, Y, and Z axes of the measurement coordinate system;

[0140] For the measurement requirements of the axis of the inner cylindrical surface feature, it is necessary to determine the direction of the axis. The cylinder moving up and down along the axis and rotating around its own axis will not affect the measurement result of the axis. Therefore, the axis equation is simplified by setting the point through which the axis passes on the XOY plane of the measurement coordinate system, i.e., z0 = 0. Let p = s1 / s3 and q = s2 / s3, and a simplified expression of the spatial equation of the axis can be obtained.

[0141] After inputting the coordinates of the center of the elliptical cross-sectional profile of the two inner arc surfaces of the gear sleeve part 4 into the spatial equation of the gear sleeve part 4 for processing, the coordinates of the intersection point C0 of the axis of the gear sleeve part 4 and the XOY plane of the measurement coordinate system, as well as the direction vector of the axis of the gear sleeve part 4, are obtained. Specifically as follows:

[0142]

[0143] Where, x 11 y 11 and z 11 These are the X, Y, and Z coordinates of the center C1 of the first elliptical cross-section profile in the measurement coordinate system, respectively. 22 y 22 and z 22 These are the X, Y, and Z coordinates of the center C2 of the second elliptical cross-section profile in the measurement coordinate system;

[0144] The coordinates of the intersection point C0 of the axis of the gear sleeve part 4 and the XOY plane of the measurement coordinate system, and the direction vector of the axis of the gear sleeve part 4 are determined. The positional parameters of the axis of the gear sleeve part 4 are used to determine the spatial positional parameters of the axis of the gear sleeve part 4.

[0145] The precise axial orientation information of the gear sleeve part 4 is obtained by accurately measuring the coordinates of the ellipse center, as shown in Table 4 below.

[0146] Table 4. Axial position and orientation information of gear sleeve components during the precision measurement phase.

[0147]

[0148] In the method for measuring the axial position and orientation of the gear sleeve part 4 in the above embodiment, the present invention corrects the measurement error of the inner arc surface feature of the eddy current measurement to obtain an ideal detection effect, and the detection error is controlled within 0.017mm.

[0149] The above description and embodiments are merely preferred examples of the present invention and do not constitute any limitation on the present invention. Obviously, those skilled in the art, after understanding the content and design principles of the present invention, may make various modifications and changes in form and detail based on the principles and structure of the present invention. However, these modifications and changes based on the ideas of the present invention are still within the protection scope of the claims of the present invention.

Claims

1. A method for adjusting the assembly posture of helicopter gear sleeve parts based on eddy current ranging, characterized in that, include: Step 1) Build a gear sleeve part pose measurement system including an eddy current displacement sensor (3) and establish a measurement coordinate system; Step 2) In the measurement coordinate system, when the eddy current displacement sensor (3) of the gear sleeve part pose measurement system is used to measure the inner arc surface feature of the helicopter gear sleeve part (4), the measurement error is corrected, and then the eddy current correction model is established. Step 3) Use the eddy current displacement sensor (3) of the gear sleeve part pose measurement system to perform a rotary scan measurement on the measured point on the gear sleeve part (4) to obtain the measurement distance and offset of the measured point. Input the measurement distance and offset of the measured point into the eddy current correction model for processing to obtain the actual lift-off distance of the measured point. Determine the coordinates of the measured point in the measurement coordinate system based on the rotation radius of the eddy current displacement sensor (3), the equal interval angle between each measured point on the gear sleeve part (4) and the actual lift-off distance of the measured point. Step 4) Use an eddy current displacement sensor (3) to perform a rough measurement on the gear sleeve part (4). Obtain the axis tilt angle information of the gear sleeve part (4) based on the coordinates of the measured point in the measurement coordinate system, and then obtain the position and pose information of the gear sleeve part (4) in the rough measurement stage. Step 5) Based on the position and pose information of the gear sleeve part (4) in the rough measurement stage and the target assembly position and pose, use the pose adjustment device to roughly adjust the relative position and pose between the rotation axis of the eddy current displacement sensor (3) and the axis of the gear sleeve part (4) so ​​that the position and pose of the gear sleeve part (4) are adjusted to be close to the target assembly position and pose. Step 6) Use the eddy current displacement sensor (3) to perform fine measurement on the roughly adjusted gear sleeve part (4) to obtain the center coordinates of the elliptical cross-sectional profile of the two inner arc surfaces of the gear sleeve part (4) in the measurement coordinate system. Step 7) Calculate the spatial pose of the axis of the gear sleeve part (4) based on the center coordinates of the elliptical cross-sectional profiles of the two inner arc surfaces of the gear sleeve part (4), and finally adjust the spatial pose of the axis of the gear sleeve part (4) to the target assembly pose to complete the assembly pose adjustment of the gear sleeve part (4).

2. The method for adjusting the assembly posture of helicopter gear sleeve parts based on eddy current ranging according to claim 1, characterized in that: In step 1), the gear sleeve part position measurement system further includes a motion control mechanism (1) and a cantilever fixture (2). The motion control mechanism (1) has at least four degrees of freedom, including three translational degrees of freedom in the spatial rectangular coordinate direction and a rotational degree of freedom about the vertical direction. The end flange of the motion control mechanism (1) is connected to the cantilever fixture (2), and a positioning pin hole is provided on the end flange. The cantilever fixture (2) includes a crossbeam (21) and a longitudinal beam (22). The end flange of the motion control mechanism (1) is connected to the upper surface of one end of the crossbeam (21). The radial direction of the end flange is parallel to the length direction of the crossbeam (21). The lower surface of the crossbeam (21) is provided with a groove along its own length direction. The top end of the longitudinal beam (22) is slidably installed in the groove of the crossbeam (21). The longitudinal beam (22) is provided with reinforcing ribs to prevent bending deformation. The bottom end of the longitudinal beam (22) is provided with a through hole for installing the eddy current displacement sensor (3). The eddy current displacement sensor (3) includes a sensor probe (31), a sensor connecting cable (32) and a sensor fixing nut (33). The sensor probe (31) is installed in the through hole of the longitudinal beam (22) through the sensor fixing nut (33). The sensor probe (31) is connected to an external sensor processing device through the sensor connecting cable (32). The orientation of the sensor probe (31) is parallel to the length direction of the crossbeam (21). The straight distance between the center symmetrical point of the positioning pin hole on the end flange and the head of the sensor probe (31) is used as the rotation radius r of the eddy current displacement sensor (3). The measurement coordinate system of the gear sleeve part position and posture measurement system takes the center of the base bottom surface of the motion control mechanism (1) as the origin O, the measurement direction along the axis of the eddy current displacement sensor (3) after installation as the X-axis, and the vertical upward direction as the Z-axis, and establishes a right-hand rectangular coordinate system O-XYZ.

3. The method for adjusting the assembly posture of helicopter gear sleeve parts based on eddy current ranging according to claim 2, characterized in that: Step 2) is as follows: Step 2.1) Move the eddy current displacement sensor (3) into the gear sleeve part (4) by the motion control mechanism (1). Several measurement points are set at equal intervals on the inner surface of the gear sleeve part (4). The sensor probe (31) of the eddy current displacement sensor (3) is centered. The sensor probe (31) is moved step by step along the X and Y axes of the measurement coordinate system in the gear sleeve part (4) by the motion control mechanism (1). The range of the eddy current displacement sensor (3) is determined so that the eddy current displacement sensor (3) is within the range when it moves. At the same time, the axis of the sensor probe (31) is aligned with the normal vector of the measured point. Step 2.2) Use an eddy current displacement sensor (3) to measure the inner arc surface features of the gear sleeve part (4), change the lift-off distance h and offset δ of the sensor probe (31) relative to the measured point in the plane XOY. The lift-off distance is the real distance between the surface of the sensor probe (31) and the measured point. At this time, the measurement distance H of the sensor probe (31) is not equal to the real lift-off distance. Calibrate the N offsets of the same inner arc surface feature under M lift-off distances to obtain the measurement distance H(m, n) and sensor lift-off distance h(m, n) of the sensor probe (31) for M×N types, where m = 1, 2, ..., M, n = 1, 2, ..., N; Step 2.3) For each offset, perform a second-order polynomial fitting on all M types of lift-off distance h and measurement distance H under the current offset to obtain the second-order polynomial fitting result of the offset. The second-order polynomial fitting result of the offset is h(m,n)=A ε (n)·H(m,n) 2 +B ε (n)·H(m,n)+C ε (n), the first polynomial parameter A of the nth offset is obtained based on the second-order polynomial fitting result. ε (n), parameter B of the second polynomial ε (n) and the third polynomial parameter C ε (n); Step 2.4) For each offset, adjust the first polynomial parameter A of the current offset. ε (n), parameter B of the second polynomial ε (n) and the third polynomial parameter C ε (n) Perform a second-order polynomial fitting to obtain the parameters A of the first polynomial. ε (n), parameter B of the second polynomial ε (n) and the third polynomial parameter C ε The second-order polynomial fitting result of (n), the first polynomial parameter A ε The second-order polynomial fitting result A of (n) ε ′(n), the second polynomial parameter B ε The second-order polynomial fitting result B of (n) ε ′(n), the parameter C of the third polynomial ε The second-order polynomial fitting result C of (n) ε ′(n), thus obtaining the first intermediate correction parameter A. ε0 Second intermediate correction parameter A ε1 Third intermediate correction parameter A ε2 Fourth intermediate correction parameter B ε0 Fifth intermediate correction parameter B ε1 Sixth intermediate correction parameter B ε2 Seventh intermediate correction parameter C ε0 Eighth intermediate correction parameter C ε1 and the ninth intermediate correction parameter C ε2 Where T(n) is the offset distance of the nth offset; Step 2.5) Obtain the measurement distance H of the sensor probe (31), and at the same time, establish the eddy current correction model based on the offset δ of the sensor probe (31) relative to the measured point in the plane XOY and the nine intermediate correction parameters δ in step 2.4).

4. The method for adjusting the assembly posture of helicopter gear sleeve parts based on eddy current ranging according to claim 3, characterized in that: In step 2.5), the eddy current correction model is as follows: h=A ε ′(n)·H 2 +B ε ′(n)·H+C ε ′(n) A ε ′(n)=A ε0 ·d 2 +A ε1 ·d+A ε2 B ε ′(n)=B ε0 ·d 2 +B ε1 ·d+B ε2 C ε ′(n)=C ε0 ·d 2 +C ε1 ·d+C ε2 Where h is the actual lift-off distance of the sensor probe (31) relative to the measured point in the plane XOY.

5. The method for adjusting the assembly posture of helicopter gear sleeve parts based on eddy current ranging according to claim 2, characterized in that: Step 3) specifically involves the following steps: In the axial pose measurement of the gear sleeve part (4), the motion control mechanism (1) drives the sensor probe (31) to perform a rotary scan, and simultaneously acquires the measurement data of the sensor probe (31), including the measurement distance H of the sensor probe (31) and the offset δ of the relative measured point in the plane XOY. The measurement data of the sensor probe (31) is input into the eddy current correction model for processing. After processing, the eddy current correction model outputs the actual lift-off distance h of the sensor probe (31) relative to the measured point in the plane XOY. Based on the actual lift-off distance h of the sensor probe (31) relative to the measured point in the plane XOY, the rotation radius r of the sensor probe (31), and the equal interval angle θ between each measured point, the coordinates of the measured point in the measurement coordinate system are determined, as follows: Where, x i and y i Let X and Y be the coordinates of the i-th measured point in the measurement coordinate system, i = 1, 2, ..., I, and I be the total number of measured points on the cross section of the inner arc surface of the gear sleeve part (4) in the measurement coordinate system, I = 360 / θ.

6. The method for adjusting the assembly posture of helicopter gear sleeve parts based on eddy current ranging according to claim 2, characterized in that: Step 4) is as follows: Step 4.1) In the rough measurement stage of the gear sleeve part (4), the sensor probe (31) rotates around the rotation axis of the gear sleeve part (4) once. The rotation section of the gear sleeve part (4) is parallel to the measurement coordinate system XOY. The gear sleeve part (4) is in an inclined state. The rotation section of the gear sleeve part (4) intersects with the inner cylindrical surface of the gear sleeve part (4) to form an elliptical profile. Step 4.2) Based on the radius of curvature R of the inner arc surface of the gear sleeve part (4) and the geometric parameters of the elliptical profile, obtain the angle between the cross section containing the elliptical profile and the circular cross section passing through the center of the elliptical profile. This allows us to obtain the axial tilt angle information of the gear sleeve part (4); Step 4.3) Based on the axial tilt angle information of the gear sleeve part (4) and the minor axis direction vector of the elliptical profile... Determine the direction vector of the axis of the gear sleeve part (4). And the coordinates C of the center of the elliptical profile on the axis. c =(x Ci y Ci , z Ci ), s1, s2, and s3 are the projections of the direction vector of the axial direction of the gear sleeve part (4) onto the X, Y, and Z axes of the measurement coordinate system, respectively. Ci y Ci and z Ci The center C of the elliptical outline is respectively c In the X, Y and Z axis coordinates of the measurement coordinate system, the rotation axis of the eddy current displacement sensor (3) is parallel to the Z axis of the measurement coordinate system, and finally the position and orientation information of the axis of the gear sleeve part (4) in the roughing stage is determined.

7. The method for adjusting the assembly posture of helicopter gear sleeve parts based on eddy current ranging according to claim 2, characterized in that: Step 6) specifically involves using the sensor probe (31) of the eddy current displacement sensor (3) to move along the vertical rotation axis, selecting elliptical cross-sectional profiles at the upper and lower inner arc surfaces of the gear sleeve part (4) that are parallel to the plane XOY, performing elliptical least-squares fitting on each elliptical cross-sectional profile to obtain the center position of each elliptical cross-sectional profile, and adding the Z coordinate of the cross-section to the center of each elliptical cross-sectional profile to obtain the spatial coordinates C1 = (x... 11 y 11 , z 11 ) and C2=(x 22 y 22 , z 22 ), where x 11 y 11 and z 11 Let x, Y, and Z be the X, Y, and Z coordinates of the center of the first elliptical cross-section profile in the measurement coordinate system. 22 y 22 and z 22 These are the X, Y, and Z coordinates of the center of the second elliptical cross-section profile in the measurement coordinate system.

8. The method for adjusting the assembly posture of helicopter gear sleeve parts based on eddy current ranging according to claim 2, characterized in that: Step 7) specifically involves determining the spatial equation of the axis of the gear sleeve part (4) based on the coordinates of the center of the elliptical cross-sectional profile of the two inner arc surfaces of the gear sleeve part (4): p = s1 / s3 q = s² / s³ Where x, y, and z are the X, Y, and Z axis coordinates of a point on the axis of the gear sleeve part (4) in the measurement coordinate system; p and q are the first and second direction vector parameters, respectively; x0 and y0 are the X and Y axis coordinates of the intersection point C0 of the axis of the gear sleeve part (4) and the XOY plane of the measurement coordinate system, respectively; s1, s2, and s3 are the direction vectors of the axis of the gear sleeve part (4). Projection along the X, Y, and Z axes of the measurement coordinate system; After inputting the coordinates of the center of the elliptical cross-section of the two inner arc surfaces of the gear sleeve part (4) into the spatial equation of the gear sleeve part (4) for processing, the coordinates of the intersection point C0 of the axis of the gear sleeve part (4) and the XOY plane of the measurement coordinate system, as well as the direction vector of the axis of the gear sleeve part (4), are obtained. Specifically as follows: Where, x 11 y 11 and z 11 These are the X, Y, and Z coordinates of the center C1 of the first elliptical cross-section profile in the measurement coordinate system, respectively. 22 y 22 and z 22 These are the X, Y, and Z coordinates of the center C2 of the second elliptical cross-section profile in the measurement coordinate system; The coordinates of the intersection point C0 of the axis of the gear sleeve part (4) and the XOY plane of the measurement coordinate system, and the direction vector of the axis of the gear sleeve part (4) are determined. As the pose parameter of the axis of the gear sleeve part (4), the spatial pose of the axis of the gear sleeve part (4) is determined.

9. An electronic device, characterized in that, include: A memory and a processor are coupled to each other, wherein the memory stores program data, and the processor invokes the program data to perform the method as described in any one of claims 1-8.

10. A computer-readable storage medium storing program data thereon, characterized in that, When the program data is executed by the processor, the method as described in any one of claims 1-8 is implemented.

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