End effector machining pose planning method for hole making of aircraft engine nacelle acoustic lining

Abstract

The present invention discloses a method for machining pose planning of the end effector for hole making of the nacelle acoustic liner of an aeroengine, which relates to the field of aeroengine manufacturing and includes the following steps: through mapping; calculating the axes of the equivalent machining hole coordinate system, when the number of acoustic liner holes in the mapping, calculating the origin of the equivalent machining hole coordinate system, when the number of acoustic liner holes in the mapping, calculating the vector and the origin to obtain the target machining pose of the multi-spindle end effector; The present invention can calculate the pose of the equivalent machining hole coordinate system in the robot base coordinate system, drive the coordinated movement of each joint of the robot to complete the machining of the acoustic liner holes, thereby shortening the manufacturing cycle of the nacelle acoustic liner parts of the aeroengine and providing a theoretical basis and technical support for the formulation of the multi-spindle hole making process specifications of the nacelle acoustic liner robot of the aeroengine.

Description

Technical Field

[0001] The present invention relates to the field of aero-engine manufacturing, and in particular to a method for planning the machining pose of the end effector for making holes in the nacelle acoustic liner of an aero-engine. Background Art

[0002] The noise of an aero-engine is the main source of aircraft noise. The fan noise is the main component of the aero-engine noise. The fan noise control level is an important indicator to measure the advancement of modern aero-engines. In order to reduce the fan noise of an aero-engine, an acoustic liner is laid in the nacelle of the aero-engine. Based on the Helmholtz resonance principle, the acoustic energy is dissipated in the noise radiation propagation path through the acoustic liner holes and honeycomb cavities. Since the number of acoustic liner holes is extremely large, the arrangement is complex, and the position accuracy will affect the acoustic impedance of the acoustic liner. Therefore, making holes in the acoustic liner is an important link in the manufacture of the nacelle acoustic liner.

[0003] The conventional robot single-spindle hole-making system is difficult to meet the high-efficiency hole-making requirements of the nacelle acoustic liner. In order to greatly improve the hole-making efficiency of the acoustic liner holes, a multi-spindle hole-making system for the nacelle acoustic liner of a robot has been developed. The array multi-spindle hole-making of the nacelle acoustic liner is realized through the multi-spindle hole-making end effector. The multi-spindle hole-making end effector can complete the machining of acoustic liner holes equal to the number of spindles at most with one positioning. When making holes in the nacelle acoustic liner, a large number of acoustic liner holes in the hole-making area are mapped into a small number of equivalent machining holes, and the pose of the equivalent machining hole coordinate system in the robot base coordinate system is calculated as the machining pose of the multi-spindle hole-making end effector, and the robot joints are driven to move cooperatively to complete the machining of the acoustic liner holes.

[0004] However, most of the nacelle acoustic liners are large-sized curved surface parts. At the same time, the machining pose of the end effector is determined by the nominal pose parameters of the acoustic liner holes to be machined after one positioning. How to plan the machining pose of the end effector based on the pose parameters of a large number of acoustic liner holes is very crucial for ensuring the hole-making positioning accuracy of the acoustic liner holes.

[0005] In view of this, the inventor of this case has conducted in-depth research on the above problems, and thus this case has been produced. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for planning the machining pose of the end effector for making holes in the nacelle acoustic liner of an aero-engine, so as to ensure the hole-making positioning accuracy of the acoustic liner holes.

[0007] In order to achieve the above purpose, the present invention adopts the following technical solution:

[0008] The method for planning the machining pose of the end effector for making holes in the nacelle acoustic liner of an aero-engine is carried out according to the following steps:

[0009] S1, through mapping , mapping the synchronous machining of multiple acoustic lining holes based on a multi-spindle hole-making end effector to the machining of a single acoustic lining hole based on a single-spindle hole-making end effector, the th acoustic lining hole has ;

[0010] (1);

[0011] Among them:

[0012] ( ) are the pose parameters of the acoustic lining holes synchronously machined by a single positioning of the multi-spindle end effector in the short nacelle acoustic lining product coordinate system ;

[0013] are the position coordinates of the acoustic lining holes;

[0014] is the normal vector of the acoustic lining surface at the

[0015] is the pose matrix of the equivalent equivalent machining hole coordinate system in the product coordinate system ;

[0016] S2. Define that the axis of the acoustic lining hole is collinear with the normal vector of the acoustic lining surface at its position. Based on the normal vector of the acoustic lining hole in the mapping , calculate the axis of the equivalent machining hole coordinate system. The specific steps include:

[0017] S21. Determine the actual acoustic lining hole to be machined corresponding to a certain equivalent machining hole according to the mapping , and mark the position coordinates of this acoustic lining hole as ;

[0018] S22. Extract the normal vector of the acoustic lining surface at the acoustic lining hole through the offline programming software;

[0019] S23. Normalize the mean value of the normal vectors of the actual acoustic lining holes corresponding to the equivalent machining holes as the axis direction of the equivalent machining hole coordinate system;

[0020] (2);

[0021] Among them:

[0022] is the average normal vector of the acoustic lining hole;

[0023] is the of the equivalent machining hole coordinate system Axis unit vector;

[0024] S3, when the mapping the number of acoustic lining holes enters S4;

[0025] Mapping the number of acoustic lining holes enters S5;

[0026] Where:

[0027] is a natural number greater than 0;

[0028] S4, set the axis direction of the equivalent machining hole coordinate system, and at the same time calculate the origin of the equivalent machining hole coordinate system based on the design geometric parameters of the end effector spindle array, the specific steps include:

[0029] S41, based on the calibration result of the robot base coordinate system to obtain the negative unit vector of the axis in the nacelle acoustic lining product coordinate system ;

[0030] S42, and are cross-multiplied to obtain , and is unitized to obtain , which is used as the axis direction of the equivalent machining hole coordinate system;

[0031] (3);

[0032] S43, the unit vectors and are cross-multiplied to obtain the axis direction of the equivalent machining hole coordinate system with respect to the nacelle acoustic lining product coordinate system ;

[0033] (4);

[0034] S44, when , a coordinate system is established on the machining plane, with and as the axis and axis directions respectively, and the coordinates of the equivalent machining hole in this coordinate system are , where Depend on the design geometric parameters of the end effector spindle array;

[0035] S45, solve to obtain the position coordinates of the origin of the equivalent machining hole coordinate system ;

[0036] (5);

[0037] S5, based on the position coordinates of any two acoustic lining holes, determine the axis direction and origin of the equivalent machining hole coordinate system. The specific steps include:

[0038] S51, the axes of the spindles on the multi-spindle hole-making end effector are parallel and the ends are flush. Machining a certain equivalent machining hole can be regarded as each hole-making spindle machining an acoustic lining hole on the same machining plane The equation of the machining plane is set as ;

[0039] According to S2, the normal vector of the machining plane is , let the coefficients in the equation of the machining plane be equal to respectively, and solve based on the least squares algorithm to minimize the sum of the squares of the deviations between the actual position coordinates of the acoustic lining holes and the fitting plane of the coefficients ;

[0040] (6);

[0041] Among them:

[0042] is the objective function, and the optimization model is ;

[0043] is the th position coordinate of the acoustic lining hole;

[0044] S52, calculate the projection of the position coordinates of the acoustic lining holes in the mapping on the machining plane ;

[0045] (7);

[0046] (8);

[0047] Among them:

[0048] is the th position coordinate of the acoustic lining hole Projection;

[0049] is the position coordinate of the nth acoustic lining hole;

[0050] S53. On the machining plane construct a plane rectangular coordinate system to calculate the vector and the origin to determine the equivalent machining hole coordinate system with respect to the nacelle acoustic lining product coordinate system axis direction and origin. The specific process includes:

[0051] S531. According to formula (7), obtain the projections and of the position coordinates of the nth and (n + 1)th acoustic lining holes on the machining plane ; and ;

[0052] S532. Calculate the vector on the machining plane from the projection to the projection , and perform unitization to obtain ;

[0053] S533. Combine with the unit normal vector of the machining plane obtained from formula (2), and cross - multiply to obtain ;

[0054] S534. Based on the unit vectors and , establish a plane rectangular coordinate system ;

[0055] S535. According to formula (9) and formula (10), calculate the vector and the origin ;

[0056] (9);

[0057] (10);

[0058] Where: ;

[0059] S536. Perform unitization on the vector to obtain , which will be used as the axis direction of the equivalent machining hole coordinate system ;

[0060] S537, cross-multiply the unit vector and to obtain the equivalent machining hole coordinate system with respect to the nacelle acoustic lining product coordinate system in the axis direction ;

[0061] (11);

[0062] Take the position coordinate of one of the acoustic lining holes as the origin, establish a plane rectangular coordinate system, and calculate the vector and the origin ;

[0063] S54, based on the equivalent machining hole coordinate system axis unit vector and the in-situ position coordinate , obtain the pose description matrix of the equivalent machining hole in the nacelle acoustic lining product coordinate system , and transform it to the robot base coordinate system , which is the target machining pose of the multi-spindle end effector;

[0064] (12);

[0065] (13);

[0066] Wherein:

[0067] is the calibration result of the robot base coordinate system.

[0068] Preferably, the multi-spindle hole-making end effector includes an end effector frame, a spindle group, a feed group, a solenoid valve group, and a pressure foot group;

[0069] The end effector frame includes a front plate and a rear plate arranged oppositely. The spindle group, the feed group, and the solenoid valve group are all arranged in the inner cavity of the end effector frame. The pressure foot group is arranged on the rear plate and located outside the end effector frame. The feed group is arranged on the rear plate. One end of the spindle group corresponds to the feed group, and the other end passes through the front plate and is correspondingly connected to the pressure foot group. The feed group is used to control the extension or retraction of the corresponding spindle group and the pressure foot group.

[0070] Preferably, it further includes a drilling position error measurement system for measuring the angle between the drilling direction of the equivalent processing hole of the multi-spindle drilling end effector and the surface normal of the equivalent processing hole on the nacelle acoustic lining. The drilling position error measurement system includes a laser displacement sensor group installed on the multi-spindle drilling end effector. The laser displacement sensor group includes four laser displacement sensors respectively used to measure the deviation between the Z-axis of the actual tool coordinate system and the Z-axis of the ideal tool coordinate system. The four laser displacement sensors are respectively installed at the four corners of the front plate, and the Z-axis of the coordinate system is parallel to the drilling direction.

[0071] Preferably, it further includes a drilling direction deviation measurement system for measuring the position coordinates of the prefabricated reference holes on the nacelle acoustic lining and calculating the drilling position error at the position coordinates of each reference hole. The drilling direction deviation measurement system includes a vision unit installed on the multi-spindle drilling end effector. The vision unit includes a light source for providing good shooting illumination conditions, an industrial camera and a telecentric lens for measuring the actual position coordinates of the reference holes. The direction of the light source is parallel to the direction of the spindle group.

[0072] Preferably, the spindle group includes n spindles, the feeding group includes n cylinders, and the pressure feet include n pressure feet. n is an even number greater than 0. Each spindle, cylinder, and pressure foot are arranged in one-to-one correspondence. Each cylinder independently controls the extension and retraction of the corresponding spindle and pressure foot; the solenoid valve group contains n + 1 solenoid valves. Each solenoid valve includes two interfaces, an air inlet and an air outlet. n solenoid valves are used to control the extension and retraction of the cylinders, and the other solenoid valve is used to control the air cooling switch of the spindle.

[0073] Preferably, a spring for pressing the pressure foot against the surface of the acoustic lining perforated panel is arranged between each pressure foot and the front plate. The spring is correspondingly sleeved on the outer periphery of the spindle.

[0074] Preferably, an ultrasonic sensor group is further arranged on the front plate. The ultrasonic sensor group includes four ultrasonic sensors respectively used for anti-collision detection. The four ultrasonic sensors are respectively installed at the four corners of the front plate.

[0075] By adopting the foregoing design scheme, the beneficial effects of the present invention are as follows: The processing pose planning method for the end effector of the nacelle acoustic lining drilling of an aeroengine can calculate the pose of the equivalent processing hole coordinate system in the robot base coordinate system, drive the coordinated movement of each joint of the robot to complete the acoustic lining hole processing, which is very crucial for ensuring the drilling positioning accuracy of the acoustic lining holes of large-size curved surface parts, thereby shortening the manufacturing cycle of the nacelle acoustic lining parts of the aeroengine and providing a theoretical basis and technical support for the formulation of the multi-spindle drilling process specification of the nacelle acoustic lining robot of the aeroengine. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 It is a schematic diagram of the unit vector of the X-axis of the equivalent processing hole coordinate system when processing a single acoustic lining hole in the present invention;

[0077] Figure 2 Schematic diagram for calculating the origin of equivalent machining holes when machining a single acoustic lining hole in the present invention;

[0078] Figure 3 Schematic diagram of the plane coordinate system of the machining plane structure when machining multiple acoustic lining holes in the present invention;

[0079] Figure 4 For calculating the vector and the origin in the present invention; Schematic diagram of the verification relationship;

[0080] Figure 5 Schematic diagram of the spindle distribution of the end effector for multi-spindle hole making in the present invention;

[0081] Figure 6 Schematic diagram of the equivalent machining point positions of the acoustic lining holes in the present invention;

[0082] Figure 7 Axonometric view of the end effector for multi-spindle hole making in the present invention;

[0083] Figure 8 Front view of the end effector for multi-spindle hole making in the present invention;

[0084] Figure 9 Top view of the end effector for multi-spindle hole making in the present invention;

[0085] Figure 10 Side view of the end effector for multi-spindle hole making in the present invention;

[0086] In the figure: multi-spindle hole-making end effector 3, actuator frame 31, first side plate 311, second side plate 312, spindle group 32, feed group 33, solenoid valve group 34, valve island 341, pressure foot group 35, spring 351, ultrasonic sensor group 36, laser displacement sensor group 37, vision unit 38, vacuum tube group 39. Detailed implementation manners

[0087] The following clearly and completely describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0088] Refer to Figures 1 to 10 :

[0089] The end effector machining pose planning method for the acoustic lining of an aeroengine nacelle performs according to the following steps:

[0090] S1, map , map the synchronous machining of multiple acoustic lining holes based on a multi-spindle hole-making end effector to the machining of a single acoustic lining hole based on a single-spindle hole-making end effector. The th acoustic lining hole has ;

[0091] (1);

[0092] Wherein:

[0093] ( ) are the pose parameters of the acoustic lining holes synchronously machined by a single positioning of the multi-spindle end effector in the product coordinate system of the nacelle acoustic lining ;

[0094] are the position coordinates of the acoustic lining holes;

[0095] is the normal vector of the acoustic lining surface at ;

[0096] is the pose matrix of the equivalent machining hole coordinate system in the product coordinate system ;

[0097] S2, define that the axis of the acoustic lining hole is collinear with the normal vector of the acoustic lining surface at its position. Based on the normal vector of the acoustic lining hole in the mapping , calculate the axis of the equivalent machining hole coordinate system. The specific steps include;

[0098] S21, determine the actual acoustic lining hole corresponding to the machining of a certain equivalent machining hole according to the mapping , and mark the position coordinates of this acoustic lining hole as ;

[0099] S22, extract the normal vector of the acoustic lining surface at the acoustic lining hole through offline programming software;

[0100] S23, normalize the mean value of the normal vectors of the actual acoustic lining holes corresponding to the equivalent machining holes as the axis direction of the equivalent machining hole coordinate system;

[0101] (2);

[0102] Wherein:

[0103] is the average normal vector of the acoustic lining holes;

[0104] For the equivalent machining hole coordinate system of axis unit vector;

[0105] S3, when mapping the number of acoustic lining holes in, enter S4;

[0106] Mapping the number of acoustic lining holes in, enter S5;

[0107] Where:

[0108] is a natural number greater than 0;

[0109] S4, set the axis direction of the equivalent machining hole coordinate system, and at the same time, calculate the origin of the equivalent machining hole coordinate system based on the design geometric parameters of the end effector spindle array , the specific steps include:

[0110] S41, based on the calibration result of the robot base coordinate system , obtain the robot base coordinate system of axis negative unit vector description in the nacelle acoustic lining product coordinate system ;

[0111] S42, and cross multiply to get , unitize to get , as the axis direction of the equivalent machining hole coordinate system;

[0112] (3);

[0113] S43, unit vector and cross multiply to get the axis direction of the equivalent machining hole coordinate system with respect to the nacelle acoustic lining product coordinate system ;

[0114] (4);

[0115] S44, when , establish a coordinate system on the machining plane, and respectively use and as axis and In the axial direction, the coordinates of the equivalent machining hole in this coordinate system are , where depends on the design geometric parameters of the spindle array of the end effector;

[0116] S45, solve to obtain the position coordinates of the origin of the equivalent machining hole coordinate system ;

[0117] (5);

[0118] S5, based on the position coordinates of any two acoustic lining holes, determine the axial direction and origin of the equivalent machining hole coordinate system. The specific steps include:

[0119] S51, the axes of the spindles on the multi-spindle hole-making end effector are parallel and the ends are flush. Machining a certain equivalent machining hole can be regarded as each hole-making spindle machining an acoustic lining hole on the same machining plane The equation of the machining plane is set as ;

[0120] According to S2, the normal vector of the machining plane is . Let the coefficients in the equation of the machining plane be equal to respectively. Based on the least squares algorithm, solve for the coefficients that minimize the sum of the squares of the deviations between the actual position coordinates of the acoustic lining holes and the fitting plane ;

[0121] (6);

[0122] Among them:

[0123] is the objective function, and the optimization model is ;

[0124] is the th position coordinate of the acoustic lining hole;

[0125] S52, calculate the projection of the position coordinates of the acoustic lining holes in the mapping on the machining plane ;

[0126] (7);

[0127] (8);

[0128] Among them:

[0129] is the projection of the position coordinates of the th acoustic lining hole;

[0130] is the position coordinates of the th acoustic lining hole;

[0131] S53. Construct a plane rectangular coordinate system on the machining plane to calculate the vector and the origin to determine the axis direction and the origin of the equivalent machining hole coordinate system with respect to the nacelle acoustic lining product coordinate system . The specific process includes:

[0132] S531. According to formula (7), obtain the projections and of the position coordinates of the th and th acoustic lining holes on the machining plane ;

[0133] S532. Calculate the vector on the machining plane from the projection to the projection , and perform unitization to obtain ;

[0134] S533. Combine the unit normal vector of the machining plane obtained from formula (2), and through cross product, obtain ;

[0135] S534. Based on the unit vectors and , establish a plane rectangular coordinate system ;

[0136] S535. According to formula (9) and formula (10), calculate the vector and the origin ;

[0137] (9);

[0138] (10);

[0139] where: ;

[0140] S536. Perform unitization on the vector to obtain , which will be used as the equivalent machining hole coordinate system Axis direction ;

[0141] S537. Cross - multiply the unit vectors and to obtain the axis direction of the equivalent machining hole coordinate system with respect to the nacelle acoustic lining product coordinate system Axis direction ;

[0142] (11);

[0143] Take the position coordinate of one of the acoustic lining holes as the origin, establish a plane rectangular coordinate system, and calculate the vectors and the origin ;

[0144] S54. Based on the axis unit vector of the equivalent machining hole coordinate system and the in - situ position coordinate , obtain the pose description matrix of the equivalent machining hole in the nacelle acoustic lining product coordinate system , and transform it to the robot base coordinate system , which is the target machining pose of the multi - spindle end - effector;

[0145] (12);

[0146] (13);

[0147] Among them:

[0148] is the calibration result of the robot base coordinate system.

[0149] Preferably, the multi - spindle hole - making end - effector 3 is connected to the robotic arm through a flange. The multi - spindle hole - making end - effector 3 includes an actuator frame 31, a spindle group 32, a feed group 33, a solenoid valve group 34, a pressure foot group 35, an ultrasonic sensor group 36, a laser displacement sensor group 37, and a vision unit 38; the actuator frame 31 is the installation basis for each component in the multi - spindle hole - making end - effector 3.

[0150] The actuator frame 31 has a cubic box structure. Define two opposite side plates of the actuator frame 31 as the first side plate 311 and the second side plate 312. The presser foot group 35, the ultrasonic sensor group 36, the laser displacement sensor group 37, and the vision unit 38 are all arranged on the first side plate 311. The feeding group 33 and the solenoid valve group 34 are both arranged on the second side plate 312. The main shaft group 32 is arranged inside the actuator frame 31, and one end passes through the first side plate 311 and is correspondingly connected to the presser foot group 35. The feeding group 33 is used to control the extension or retraction of the corresponding main shaft group 32 and the presser foot group 35.

[0151] Furthermore, the main shaft group 32 is composed of n main shafts in an array form, the feeding group 33 is composed of n cylinders in an array form, and the presser foot group 35 is composed of n presser feet in an array form. n is an even number greater than 0. The number of the main shaft group 32, the feeding group 33, and the presser foot group 35 is the same, and each main shaft, cylinder, and presser foot are arranged in one-to-one correspondence. The cylinders are respectively used to control the extension and retraction of the corresponding main shaft and presser foot. Preferably, a spring 351 for pressing the presser foot against the surface of the acoustic lining perforated panel is arranged between each presser foot and the first side plate 311, and each spring 351 is respectively sleeved on the outer periphery of the main shaft. Driven by each cylinder, the presser foot extends and under the pressure of the spring, presses against the surface of the acoustic lining perforated panel based on the friction between the end face of the presser foot and the surface of the perforated panel. In this embodiment, the acoustic lining part and the end effector 3 of the main shaft hole making are coupled into a whole to improve the stiffness of the hole making system and the stability of hole making, and reduce the vibration during hole making.

[0152] In this embodiment, .

[0153] Furthermore, the multi-main shaft hole making end effector 3 further includes a vacuum tube group 39. The vacuum tube group 39 is composed of n vacuum tubes in an array form. Each vacuum tube is installed on the side of the presser foot. Based on the principle of vacuum chip collection, the chips generated during the hole making of the acoustic lining holes are collected from the presser foot to a dust collector (not shown in the figure).

[0154] Furthermore, the solenoid valve group 34 is composed of n + 1 solenoid valves in an array form. Each solenoid valve includes two interfaces, an air inlet and an air outlet. Among them, n solenoid valves are used to control the extension and retraction of the cylinders in the cylinder array, and the other 1 solenoid valve is used for the control of the main shaft air cooling switch. Preferably, a valve island 341 for installing the solenoid valve group 34 is arranged on the second side plate 312. The valve island 341 can realize the independent control of the solenoid valves in the solenoid valve group 34 based on the same air source.

[0155] The ultrasonic sensor group 36 includes four ultrasonic sensors respectively used for anti-collision detection. The four ultrasonic sensors are evenly installed at the four corners of the first side plate 311.

[0156] The laser displacement sensor group 37 includes four laser displacement sensors respectively used to measure the deviation between the Z-axis of the actual tool coordinate system (the axis parallel to the hole-making direction) and the Z-axis of the ideal tool coordinate system. The four laser displacement sensors are evenly installed at the four corners of the first side plate 311, providing a basis for the attitude correction of the end effector.

[0157] The vision unit 38 includes a light source for providing good shooting illumination conditions, an industrial camera and a telecentric lens for measuring the actual position coordinates of the reference holes. The optical axis direction is parallel to the axis directions of the main shafts on the main shaft group 32. The light source is used to provide good shooting illumination conditions, and the industrial camera and the telecentric lens are used to measure the actual position coordinates of the reference holes. With the help of the hole-making direction deviation measurement system, the object distance and the optical axis direction during the measurement of the industrial camera are controlled. After calculating the deviation between the actual positions of multiple reference holes and their corresponding nominal positions, the hole-making positioning error can be calculated based on a certain interpolation compensation strategy, providing a basis for the position correction of the end effector.

[0158] The method for measuring the positioning error of the multi-spindle hole-making end effector 3 is carried out according to the following steps:

[0159] SA1, use the vision unit integrated on the end effector of the robot multi-spindle hole-making system to capture the image of the reference hole;

[0160] Among them, it is defined that the optical axis of the camera is parallel to the axis of the main shaft array, and the object distance during visual shooting and the perpendicularity of the optical axis to the surface of the acoustic lining are obtained to get the pose of the vision unit in the state of orthoscopic object distance and the optical axis perpendicular to the surface of the acoustic lining;

[0161] (A1);

[0162] Among them:

[0163] is the pose of the vision unit coordinate system relative to the short nacelle acoustic lining product coordinate system ;

[0164] is the pose of the calibrated robot base coordinate system relative to the product coordinate system ;

[0165] is the pose of the robot flange coordinate system relative to the robot base coordinate system obtained based on the robot kinematic model;

[0166] is the calibrated robot tool coordinate system relative to the flange coordinate system Pose;

[0167] is the calibrated hand-eye relationship, i.e., the coordinate system of the vision unit relative to the tool coordinate system Pose;

[0168] represents the positive focal length;

[0169] represents that the optical axis is perpendicular to the surface of the acoustic liner, i.e., the angle is 90°;

[0170] SA2, passing through SA1, obtains the robust, accurate and efficient positioning of the reference hole features in the reference hole image by the reference hole feature positioning algorithm that combines visual saliency and mean shift. The specific steps are as follows:

[0171] SA21, for the obtained original reference hole image perform Gaussian filtering or median filtering to obtain the corresponding smoothed image ; for the smoothed image perform image contrast stretching to obtain the enhanced image , calculate the saliency map of the original reference hole image according to formula (2) ;

[0172] (A2);

[0173] where:

[0174] represents calculating the average pixel value of the image:

[0175] represents obtaining the maximum pixel value of the image;

[0176] represents obtaining the minimum pixel value of the image;

[0177] SA22, through region screening, selects the saliency region with the largest area in the saliency map of the reference hole image to obtain the centroid coordinates of the largest saliency region , calculate the distance map between the coordinate positions of each pixel in the saliency map and the centroid coordinates according to formula (A3) ; ;

[0178] Calculate the weight map according to formula (A4) ;

[0179] According to formula (A5), the weight map and the saliency map Multiply the corresponding elements to clear the fragmented salient regions in the salient map, obtaining an updated salient map ;

[0180] (A3);

[0181] (A4);

[0182] (A5);

[0183] SA23, select a suitable fixed threshold based on the automatic threshold segmentation method or through repetitive tests, and perform threshold segmentation on the updated salient map of SA22 to segment the reference hole feature region from the salient map;

[0184] Use an edge detection operator or a contour extraction algorithm to extract the reference hole contour from the threshold segmentation map of the salient map, approximately evenly divide the set of contour points into three consecutive subsets, randomly select contour points from the three subsets multiple times for circle fitting, and store all the fitted center coordinates in an array;

[0185] From all the candidate centers, randomly select one as the initial centroid, and based on the preset scanning radius centered on it, use the mean shift algorithm to iteratively find the true centroid of the set of centers as the reference hole center coordinate system ;

[0186] SA3, set the image coordinate system at the center of the image, with its axis directions the same as the default axis directions of the image. According to the reference hole center coordinates obtained in SA23 , combined with the calibrated internal parameters of the vision unit and the known image width and height ;

[0187] Define that the XY plane of the vision unit coordinate system and its coordinate axes coincide with the image coordinate plane and its coordinate axes correspondingly, and obtain the physical coordinates of the reference hole in the vision unit coordinate system according to formula (A6) ;

[0188] (A6);

[0189] According to formula (A7) combined with what is obtained in SA1 , obtain the homogeneous transformation matrix expression of the reference hole in the product coordinate system , consisting of the rotation matrix and the translation vector ;

[0190] Translation vector The transpose is the coordinate of the reference hole measured by the vision unit in the product coordinate system. ;

[0191] (A7);

[0192] Combined with the nominal coordinate of the reference hole in the product coordinate system , the hole-making positioning error at the reference hole is obtained ;

[0193] (A8);

[0194] SA4. For all reference holes, repeat steps SA1 to SA3 to measure the hole-making positioning errors at all reference holes through the vision system;

[0195] SA5. Through surface interpolation, obtain the hole-making positioning errors at the positions of the remaining holes in the influence area of the reference hole and compensate for these errors.

[0196] By adopting the foregoing design scheme, the beneficial effects of the present invention are as follows: The end-effector machining pose planning method for hole-making of the acoustic liner of an aero-engine nacelle can calculate the pose of the equivalent machining hole coordinate system in the robot base coordinate system, drive the coordinated movement of each joint of the robot to complete the hole-making of the acoustic liner holes, which is very crucial for ensuring the hole-making positioning accuracy of large-size curved surface parts, thereby shortening the manufacturing cycle of the acoustic liner parts of the aero-engine nacelle and providing a theoretical basis and technical support for the formulation of the multi-spindle hole-making process specification of the aero-engine nacelle robot.

[0197] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for machining pose planning of the end effector for making holes in the acoustic liner of an aeroengine nacelle, characterized in that: Proceed as follows: S1, through mapping , map the synchronous machining of multiple acoustic lining holes by a multi-spindle hole-making end effector to the machining of a single acoustic lining hole by a single-spindle hole-making end effector. The th acoustic lining hole has ; （1）； Wherein: ( ) are the pose parameters of the acoustic lining holes for synchronous machining with one-time positioning of the multi-spindle end effector in the short nacelle acoustic lining product coordinate system ; are the position coordinates of the acoustic lining holes; is the normal vector of the acoustic lining surface at is the pose matrix of the equivalent machining hole coordinate system in the product coordinate system ; S2. Define that the axis of the acoustic lining hole is collinear with the normal vector of the acoustic lining surface at its position, and calculate the axis of the equivalent machining hole coordinate system based on the normal vector of the acoustic lining hole in the mapping. The specific steps are as follows: S21, according to the mapping determine the acoustic lining hole corresponding to the actual machining when machining a certain equivalent machining hole, and mark the position coordinates of this acoustic lining hole as ; S22, extracting the normal vector of the acoustic lining surface at the acoustic lining holes through offline programming software ; S23, normalize the mean value of the normal vectors of the actual acoustic lining holes corresponding to the equivalent machining holes, and use it as the axis direction of the equivalent machining hole coordinate system; （2）； Wherein: is the average normal vector of the acoustic lining holes; For the equivalent machining hole coordinate system of axis unit vector; S3. When mapping the number of acoustic lining holes go to S4; Mapping The number of acoustic lining holes When it is, enter S5; Wherein: n is a natural number greater than 0; S4, set the axis direction of the equivalent machining hole coordinate system , and at the same time, calculate the origin of the equivalent machining hole coordinate system based on the designed geometric parameters of the end effector spindle array , and the specific steps include: S41, based on the calibration result of the robot base coordinate system , obtain the robot base coordinate system 's negative axis unit vector description in the nacelle acoustic lining product coordinate system ; ; S42, Cross multiply with to obtain , normalize to obtain , which serves as the axis direction of the equivalent machining hole coordinate system; （3）； S43, unit vector and are cross - multiplied to obtain the equivalent machining hole coordinate system with respect to the nacelle acoustic lining product coordinate system in the axis direction ; （4）； S44, when , establish a coordinate system on the machining plane, respectively with and as axis and axis directions, the coordinates of the equivalent machining hole in this coordinate system are , where depends on the design geometric parameters of the end effector spindle array; S45, solve to obtain the position coordinates of the origin of the equivalent machining hole coordinate system ; （5）； S5. Based on the position coordinates of any two acoustic lining holes, determine the axis direction and origin of the equivalent machining hole coordinate system. The specific steps include: S51. On the multi-spindle hole-making end effector, the axes of all spindles are parallel and the ends are flush. Machining a certain equivalent machining hole can be regarded as each hole-making spindle machining the acoustic lining hole on the same machining plane. Machining the acoustic lining hole on the machining plane, the machining plane equation is set as ; According to S2, the machining plane has a normal vector of . Let the coefficients in the equation of the machining plane be equal to respectively. Based on the least squares algorithm, solve for the coefficients that minimize the sum of the squares of the deviations between the actual acoustic lining hole position coordinates and the fitting plane ; （6）； Wherein: is the objective function, and the optimization model is ; For the position coordinates of the nth acoustic lining hole; S52, Calculation mapping Position coordinates of the acoustic lining holes Projection on the machining plane ; （7）； （8）； Wherein: is the position coordinate of the th acoustic lining hole; is the position coordinate of the th acoustic lining hole; S53, on the machining plane Construct a plane rectangular coordinate system to calculate the vector and the origin , determine the axis direction and origin of the equivalent machining hole coordinate system with respect to the nacelle acoustic lining product coordinate system . The specific process includes: S531, according to formula (7), the position coordinates of the and th acoustic lining holes on the machining plane projection and ; S532, Calculate the machining plane Projection on Vector pointing to the projection Vector , and perform unitization to obtain ; The machining plane obtained by combining S533 with formula (2) The unit normal vector of , which can be obtained by cross product ; S534, based on unit vectors and , establish a plane rectangular coordinate system ; S535 can calculate the vector according to Formula (9) and Formula (10). and the origin ; （9）； （10）； Wherein: ; S536, for the vector perform unitization processing , and will be used as the equivalent machining hole coordinate system axis direction ; S537, cross multiply the unit vectors and to obtain the equivalent machining hole coordinate system with respect to the nacelle acoustic lining product coordinate system axis direction ; （11）； Take the coordinate of one of the acoustic lining hole positions as the origin, establish a plane rectangular coordinate system, and calculate the vector according to the above process and the origin ; S54, based on equivalent machining hole coordinate system Axis unit vector And the original position coordinates , the equivalent processing hole is obtained in the nacelle sound lining product coordinate system The pose description matrix , transform it into the robot base coordinate system , which is the target machining posture of the multi-spindle end effector; （12）； （13）； Wherein: It is the calibration result of the robot base coordinate system.

2. The method for machining pose planning of the end effector for hole making of the acoustic liner of an aeroengine nacelle according to claim 1, characterized in that: The multi-spindle hole-making end effector includes an actuator frame, a spindle group, a feed group, a solenoid valve group, and a pressure foot group; The actuator frame includes a front plate and a rear plate arranged oppositely. The spindle group, the feed group, and the solenoid valve group are all arranged in the inner cavity of the actuator frame. The pressure foot group is arranged on the rear plate and located outside the actuator frame. The feed group is arranged on the rear plate. One end of the spindle group corresponds to the feed group, and the other end passes through the front plate and is correspondingly connected to the pressure foot group. The feed group is used to control the extension or retraction of the corresponding spindle group and the pressure foot group.

3. The method for machining pose planning of the end effector for hole making of the acoustic liner of an aeroengine nacelle according to claim 2, characterized in that: It further includes a hole-making position error measurement system for measuring the angle between the hole-making direction of the equivalent processed hole of the multi-spindle hole-making end effector and the normal vector of the surface at the equivalent processed hole on the nacelle acoustic lining. The hole-making position error measurement system includes a laser displacement sensor group installed on the multi-spindle hole-making end effector. The laser displacement sensor group includes four laser displacement sensors respectively used to measure the deviation between the Z-axis of the actual tool coordinate system and the Z-axis of the ideal tool coordinate system. The four laser displacement sensors are respectively installed at the four corners of the front plate, and the Z-axis of the coordinate system is parallel to the hole-making direction.

4. The method for machining pose planning of the end effector for making holes in the acoustic liner of an aeroengine nacelle according to claim 2, characterized in that: It further includes a hole-making direction deviation measurement system for measuring the position coordinates of the reference holes prefabricated on the nacelle acoustic lining and calculating the hole-making position error at the position coordinates of each reference hole. The hole-making direction deviation measurement system includes a vision unit installed on the multi-spindle hole-making end effector. The vision unit includes a light source for providing good shooting illumination conditions, an industrial camera for measuring the actual position coordinates of the reference holes, and a telecentric lens. The direction of the light source is parallel to the direction of the spindle group.

5. The end effector machining pose planning method for the hole-making of the acoustic liner of an aeroengine nacelle according to claim 2, characterized in that: The spindle group includes n spindles, the feed group includes n cylinders, the pressure feet include n pressure feet, n is an even number greater than 0, and each spindle, cylinder, and pressure foot are arranged in one-to-one correspondence. Each cylinder independently controls the extension and retraction of the corresponding spindle and pressure foot; the solenoid valve group contains n + 1 solenoid valves. Each solenoid valve includes two interfaces, an air inlet and an air outlet. n solenoid valves are used to control the extension and retraction of the cylinders, and the other solenoid valve is used for the control of the spindle air cooling switch.

6. The end effector machining pose planning method for the hole-making of the acoustic liner of an aeroengine nacelle according to claim 5, characterized in that: A spring for pressing the pressure foot against the surface of the acoustic lining perforated panel is arranged between each pressure foot and the front plate, and the spring is correspondingly sleeved on the outer periphery of the spindle.

7. The end effector machining pose planning method for the perforation of the acoustic liner of an aeroengine nacelle according to claim 6, characterized in that: An ultrasonic sensor group is further arranged on the front plate. The ultrasonic sensor group includes four ultrasonic sensors respectively used for anti-collision detection, and the four ultrasonic sensors are respectively installed at the four corners of the front plate.

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