Equivalent processing hole generation method for nacelle sound insulation hole of an aero-engine

Abstract

The application discloses an equivalent machining hole generation method for nacelle acoustic liner holes of an aero-engine and relates to the field of aero-engine manufacturing.The method comprises the following steps: a surface of a hole area of an acoustic liner is unfolded into a plane, and after the arrangement of a hole machining point of the acoustic liner is completed, the position of a multi-spindle hole machining end effector covering the hole machining point of the acoustic liner is determined to obtain an equivalent machining hole and a corresponding hole machining point set of the acoustic liner; the equivalent machining hole is generated based on a greedy selection strategy, the equivalent machining hole with a larger number of machining holes is generated preferentially, each spindle is fully utilized in a one-time positioning machining process of the multi-spindle hole machining end effector, and all equivalent machining hole sets are output; and the method can be based on acoustic liner machining of a to-be-machined hole area.

Description

Technical Field

[0001] The invention relates to the field of aero-engine manufacturing, in particular to a method for generating equivalent machining holes for acoustic lining holes in a nacelle of an aero-engine. Background Art

[0002] Aircraft engine noise is the primary source of aircraft noise, and fan noise is a major component of aircraft engine noise. The level of fan noise control is a key indicator of the advancement of modern aircraft engines. To reduce aircraft engine fan noise, acoustic liners are installed within the nacelle. Through liner holes and honeycomb cavities, the acoustic energy is dissipated along the noise radiation propagation path based on the principle of Helmholtz resonance. The large number of liner holes, their complex arrangement, and their precise positioning all affect the acoustic impedance of the liner. Therefore, hole preparation is a critical step in nacelle acoustic liner manufacturing.

[0003] Conventional robotic single-spindle drilling systems struggle to meet the demands for efficient drilling of nacelle acoustic liners. To significantly improve drilling efficiency, a robotic multi-spindle drilling system has been developed. This system utilizes a multi-spindle drilling end-effector, which can complete the machining of a maximum number of acoustic liner holes equal to the number of spindles in a single positioning. During drilling of the nacelle acoustic liner, the large number of acoustic liner holes in the drilling area are mapped to a small number of equivalently machined holes, enabling array-based multi-spindle drilling of the nacelle acoustic liner. Before drilling the acoustic liner in the area to be drilled using the multi-spindle drilling end-effector, equivalently machined holes must first be generated based on the drilling points within the area. Inappropriate equivalently machined holes may result in some acoustic liner holes being missed, some holes being repeatedly machined, and the spindles on the multi-spindle drilling end-effector being underutilized.

[0004] In view of this, the inventors of this case conducted in-depth research on the above-mentioned issues, which led to the creation of this case. Summary of the Invention

[0005] The object of the present invention is to provide a method for generating equivalent machining holes for acoustic lining holes in an aero-engine nacelle, so as to provide positioning information for a multi-spindle multi-spindle hole-making end effector of a robot.

[0006] In order to achieve the above object, the present invention adopts such technical solution:

[0007] The equivalent machining hole generation method for the acoustic lining hole of the aircraft engine nacelle is carried out in the following steps:

[0008] S1, unfold the nacelle acoustic lining hole area surface into a plane, and complete it according to a certain row and column spacing Acoustic lining hole processing points Equivalence of the processing points of the acoustic lining holes, and definition of equivalent processing holes in the form of tuples ;

[0009] (1);

[0010] in:

[0011] is the horizontal coordinate numerical position coordinate of the equivalent machined hole on the plane of the hole making area;

[0012] is the vertical coordinate value of the equivalent machined hole on the plane of the hole making area;

[0013] is the number of acoustic lining holes processed after positioning the equivalent processing holes, ;

[0014] , is the set of machining hole points on the plane corresponding to the equivalent machining hole and The number of elements in the collection is no more than ;

[0015] The processing points of the acoustic lining holes to be processed corresponding to the spindles arranged in sequence, if The number of elements in the collection is less than , the processing point corresponding to the spindle that does not participate in processing is empty;

[0016] S2, define the boundary direction of the bottom surface of the multi-spindle drilling end effector to be the same as the row and column direction of the acoustic lining holes in the drilling area;

[0017] The hole-making operation of the multi-spindle hole-making end effector is regarded as a sequential scanning operation of the processing points of the acoustic lining hole, and the position of the multi-spindle hole-making end effector covering the processing points of the acoustic lining hole is determined. Equivalently machined holes And its corresponding acoustic lining hole processing point set Finally, the set of processing points of equivalent processing holes corresponding to acoustic lining holes is obtained ;

[0018] (2);

[0019] in:

[0020] is the position of the equivalent machining hole point set in the set S;

[0021] The corresponding acoustic lining hole point set for all equivalently machined holes is a subset of the set S;

[0022] S3, under the conditions of satisfying formulas (1) and (2), generates equivalent machining holes based on the greedy selection strategy, and prioritizes the number of machining holes. Larger equivalent machining holes , in the multi-spindle hole making end effector one-time positioning processing process to make full use of each spindle, the specific steps are as follows:

[0023] S31, determined according to the number of spindles of the multi-spindle hole making end effector ,make , ;

[0024] S32, select the corresponding hole according to the current equivalent processing sequence , enter S33;

[0025] S33, if There are , enter S34;

[0026] Otherwise, , return to S32;

[0027] S34, if ,make , , enter S35;

[0028] Otherwise, , return to S32;

[0029] S35, if Established, enter S37;

[0030] Otherwise, go to S36;

[0031] S36, judgment Is it established? If established, let and , enter S37;

[0032] Otherwise, , enter S32;

[0033] S37, output all equivalent processing hole sets ;

[0034] in:

[0035] It is a collection of records of processed points.

[0036] Preferably, it is defined that when machining the nacelle acoustic lining holes, all acoustic lining holes in the hole making area are machined, and the same acoustic lining hole will not be machined repeatedly, and the constraint condition of formula (3) is added to formula (2);

[0037] (3).

[0038] Preferably, .

[0039] Preferably, the equivalent machining hole layout is optimized according to the function Given a set of all possible equivalent machining holes with a certain order, generate a set of equivalent machining holes, including mutually exclusive machining points of acoustic lining holes, and the corresponding machining points of acoustic lining holes covering the entire hole-making area, as well as its layout and the number of set elements. The steps are as follows:

[0040] SA1, defines the set of all possible equivalent machining holes , arrange the equivalent processing holes in order As chromosomes of genetic algorithms;

[0041] If the equivalent processing holes are arranged in order contain The chromosome consists of Gene composition, each gene corresponds to an equivalent processing hole layout coordinate ;

[0042] SA2, perform parameter initialization: set the initial population size of the equivalent machining hole arrangement sequence to ,and , the chromosome length of the equivalent processing hole arrangement order in the population is m;

[0043] Set the maximum number of iterations , crossover probability , mutation probability , interval ratio The initial value of etc.

[0044] SA3, all possible equivalent processing holes are selected Coordinates are arranged in order and in reverse order, and these two arrangements are used as two equivalent processing hole arrangement chromosomes. In addition, these two arrangements are randomly shuffled to generate the remaining Equivalent processing hole arrangement order chromosomes constitute the initial population of equivalent processing hole arrangement order;

[0045] SA4, calculate the fitness function ;

[0046] A greedy selection strategy is adopted to obtain the equivalent processing hole set and its layout with the minimum number of equivalent processing holes based on the set of all possible equivalent processing holes in a certain order.

[0047] (A1);

[0048] (A2);

[0049] in:

[0050] is a function value of chromosomes in the order of equivalent processing holes, is the number of preferred equivalent processing holes, and is given by the function The solution is obtained;

[0051] A set of optimal equivalently machined holes;

[0052] The coordinates of each element in for Layout of medium-cost machined holes;

[0053] SA5, updates each chromosome in the equivalent processing hole arrangement order population through the selection of chromosomes with equivalent processing hole arrangement order and crossover and inversion mutation of equivalent processing hole layout coordinate genes;

[0054] SA6, after obtaining the offspring population through SA5, will be based on the interval ratio The retained populations of equivalent processing hole arrangement orders of the parent and child generations are recombined to obtain a new population of equivalent processing hole arrangement orders;

[0055] SA7, the number of algorithm iterations increases by 1, if the number of algorithm iterations reaches the maximum number of iterations , enter SA8;

[0056] Otherwise, return to SA4;

[0057] SA8, outputs the chromosome with the best fitness among the population of chromosomes with the order of equivalently processed holes;

[0058] SA9, simulated annealing algorithm parameter initial value: the specified temperature initial value is , set the current temperature , minimum temperature , cooling rate , chain length ;

[0059] SA10, a new solution for creating equivalent hole arrangement sequences based on the inversion mutation factor in the simulated annealing algorithm;

[0060] SA11, according to The criterion accepts a new solution for the arrangement order of equivalent machining holes. The specific process is: based on the function and the order of equivalent processing holes, the preferred number of equivalent processing holes As the energy of solution;

[0061] SA12, when the temperature When the cooling is completed, the process enters SA14;

[0062] If the current temperature When the temperature is iterated Afterwards, , return to SA10;

[0063] SA13, the minimum energy value in the optimal solution of the equivalent processing hole arrangement sequence obtained by SA12 ;

[0064] SA14, the arrangement order of equivalent processing holes corresponding to the minimum energy value is the global optimal solution of the genetic-simulated annealing optimization process, and the energy minimum value corresponds to Another output of the function The coordinates of each element in is the optimal equivalent machining hole layout.

[0065] Preferably, SA5 uses trigonometric functions to dynamically and nonlinearly adjust the crossover probability and mutation probability according to the fitness function value of each chromosome in the population iteration process of the equivalent processing hole arrangement sequence, so as to accelerate the convergence speed of the algorithm.

[0066] Preferably, in SA11, let ,in , then with a certain probability Accept the new interpretation, as follows:

[0067] ;

[0068] in:

[0069] is the energy of the current optimal solution;

[0070] The energy for the new solution.

[0071] Preferably, the multi-spindle hole-making end effector comprises an actuator frame, a spindle group, a feed group, a solenoid valve group and a presser foot group;

[0072] The actuator frame includes a front plate and a rear plate arranged relatively to each other. The spindle group, feed group and solenoid valve group are all arranged in the inner cavity of the actuator frame. The presser foot group is arranged on the rear plate and is located on the outside of 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 connected to the presser foot group. The feed group is used to control the extension or retraction of the corresponding spindle group and presser foot group.

[0073] Preferably, the system further includes a hole-making position error measurement system for measuring the angle between the hole-making direction of the equivalent hole machined by the multi-spindle hole-making end effector and the normal line of the surface at the equivalent hole machined on the nacelle acoustic liner. The hole-making position error measurement system includes a laser displacement sensor group mounted on the multi-spindle hole-making end effector. The laser displacement sensor group includes four laser displacement sensors for respectively measuring 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 mounted at the four corners of the front plate, and the Z axis of the coordinate system is parallel to the hole-making direction.

[0074] It also includes a hole-making direction deviation measurement system for measuring the position coordinates of prefabricated reference holes on the nacelle sound liner and calculating the hole-making position errors at the position coordinates of each reference hole. The hole-making direction deviation measurement system includes a visual unit installed on the multi-spindle hole-making end effector. The visual unit includes a light source for providing good shooting lighting conditions and 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.

[0075] Preferably, the spindle group includes n spindles, the feed group includes n cylinders, and the presser foot includes n presser feet, where n is an even number greater than 0, and each spindle and cylinder is arranged in a one-to-one correspondence with the presser foot, and each cylinder independently controls the extension and retraction of the corresponding spindle and presser foot;

[0076] The solenoid valve group includes n+1 solenoid valves, each of which includes two interfaces: an air inlet and an air outlet. The n solenoid valves are used to control the extension and retraction of the cylinder, and the other solenoid valve is used to control the spindle air cooling switch.

[0077] Preferably, a spring is provided between each presser foot and the front plate for pressing the presser foot against the surface of the acoustic lining perforated panel, and the spring is correspondingly sleeved on the outer peripheral edge of the main shaft; an ultrasonic sensor group is also provided on the front plate, and 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.

[0078] By adopting the above-mentioned design scheme, the beneficial effects of the present invention are as follows: the equivalent processing hole generation strategy in the acoustic lining hole making of the aircraft engine nacelle of the present invention can generate suitable equivalent processing holes based on the acoustic lining processing point information of the area to be holed, and provide hole making positioning information for the robot multi-spindle hole making system, so as to prevent some acoustic lining holes in the hole making area from being missed, some acoustic lining holes from being repeatedly processed, and the spindles on the multi-spindle hole making end effector from not being fully utilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Figure 1 Schematic diagram of the main axis distribution of the multi-spindle hole making end effector in the present invention;

[0080] Figure 2This is an equivalent schematic diagram of the processing points of the acoustic lining holes in the present invention;

[0081] Figure 3 It is the machining limit position of the multi-spindle hole-making end effector in the hole-making area in the present invention;

[0082] Figure 4 A schematic flow chart of the main steps of equivalent hole layout for multi-spindle hole making according to the present invention;

[0083] Figure 5 This is an isometric view of the multi-spindle hole-making end effector of the present invention;

[0084] Figure 6 It is a front view of the multi-spindle hole-making end effector of the present invention;

[0085] Figure 7 A top view of the multi-spindle hole-making end effector of the present invention;

[0086] Figure 8 It is a side view of the multi-spindle hole-making end effector of the present invention;

[0087] 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, presser foot group 35, spring 351, ultrasonic sensor group 36, laser displacement sensor group 37, vision unit 38, vacuum tube group 39. DETAILED DESCRIPTION

[0088] The following is a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0089] Reference Figures 1-8 :

[0090] The equivalent machining hole generation method for the acoustic lining hole of the aircraft engine nacelle is carried out in the following steps:

[0091] S1, unfold the nacelle acoustic lining hole area surface into a plane, and complete it according to a certain row and column spacing Acoustic lining hole processing points After the arrangement, according to the characteristics of the array arrangement of each spindle on the multi-spindle hole making end effector, the equivalent processing hole is adopted. The processing points of the acoustic lining holes are equivalent; wherein, multiple processing points of the acoustic lining holes can be equivalent to an equivalent processing hole. In this embodiment, 6 spindles are installed in an array as an example ( ),like Figure 2 The dotted part in the nacelle acoustic lining hole area is an equivalent processing hole, which contains 6 acoustic lining holes;

[0092] (1);

[0093] in:

[0094] It is the horizontal coordinate numerical position coordinate of the equivalent machined hole on the hole making area plane, usually the horizontal coordinate projection of the geometric center of the spindle array of the multi-spindle hole making end effector along the hole making direction on the hole making area plane;

[0095] is the ordinate value of the equivalent machined hole on the hole-making area plane, usually the projection of the geometric center of the spindle array of the multi-spindle hole-making end effector along the hole-making direction on the ordinate of the hole-making area plane;

[0096] The number of acoustic lining holes processed by the multi-spindle hole-making end effector based on a certain equivalent processing hole positioning, The maximum number of spindles cannot exceed Preferably, ;

[0097] ,and The number of elements in the collection is no more than ;

[0098] The processing points of the acoustic lining holes to be processed corresponding to the spindles arranged in sequence, if The number of elements in the collection is less than , the processing points corresponding to the spindle that does not participate in processing are empty, such as Figure 3 The multi-spindle hole making end effector is at the machining limit position of the hole making area, and the machining points corresponding to the other spindles not involved in the machining are empty;

[0099] S2, define the boundary direction of the bottom surface of the multi-spindle drilling end effector to be the same as the row and column direction of the acoustic lining holes in the drilling area;

[0100] The hole-making operation of the multi-spindle hole-making end effector is regarded as a sequential scanning operation of the processing points of the acoustic lining hole, and the position of the multi-spindle hole-making end effector covering the processing points of the acoustic lining hole is determined (such as Figure 3 As shown), the positions of all possible covered processing points of the multi-spindle multi-spindle hole-making end effector can be determined, and all possible Equivalently machined holes And its corresponding acoustic lining hole processing point set Finally, the set of processing points of equivalent processing holes corresponding to acoustic lining holes is obtained ;

[0101] (2);

[0102] in:

[0103] is the position of the equivalent machining hole point set in the set S;

[0104] The corresponding acoustic lining hole point set for all equivalently machined holes is a subset of the set S;

[0105] S3, when machining the nacelle acoustic lining holes, it is defined that all acoustic lining holes in the hole making area are machined, and the same acoustic lining hole will not be machined repeatedly; Formula (2) adds the constraint conditions of Formula (3), so that the equivalent machining hole generation problem is transformed into the minimum mutually exclusive set cover problem;

[0106] (3).

[0107] S4, in order to improve the hole making efficiency, under the conditions of satisfying formulas (1) and (2), the equivalent processing holes are generated based on the greedy selection strategy, by giving priority to the number of processing holes. Larger equivalent machining holes , in the multi-spindle hole making end effector one-time positioning processing process to make full use of each spindle, the specific steps are as follows:

[0108] S41, determined according to the number of spindles of the multi-spindle hole making end effector ,make , ;

[0109] S42, select the corresponding hole according to the current equivalent processing sequence , enter S43;

[0110] S43, if There are , enter S44;

[0111] Otherwise, , return to S42;

[0112] S44, if ,make , ;

[0113] Otherwise, , return to S42;

[0114] S45, if Established, enter S47;

[0115] Otherwise, go to S46;

[0116] S46, judgment Is it established? If established, let and , enter S42;

[0117] Otherwise, , enter S42;

[0118] S47, output all equivalent processing hole sets ;

[0119] in:

[0120] A collection of points that have been processed.

[0121] Preferably, the equivalent machining hole layout is optimized according to the function Given a set of all possible equivalent machining holes with a certain order, generate a set of equivalent machining holes, including mutually exclusive machining points of acoustic lining holes, and the corresponding machining points of acoustic lining holes covering the entire hole-making area, as well as its layout and the number of set elements. The steps are as follows:

[0122] SA1, defines the set of all possible equivalent machining holes , arrange the equivalent processing holes in order As chromosomes of genetic algorithms;

[0123] If the equivalent processing holes are arranged in order contain Equivalent processing hole numbers, the chromosome is composed of Gene composition, each gene corresponds to an equivalent processing hole layout coordinate ;

[0124] SA2, perform parameter initialization: set the initial population size of the equivalent machining hole arrangement sequence to ,and , the chromosome length of the equivalent processing hole arrangement order in the population is m;

[0125] Set the maximum number of iterations , crossover probability , mutation probability , interval ratio The initial value of etc.

[0126] SA3, all possible equivalent processing holes are selected Coordinates are arranged in order and in reverse order, and these two arrangements are used as two equivalent processing hole arrangement chromosomes. In addition, these two arrangements are randomly shuffled to generate the remaining Equivalent processing hole arrangement order chromosomes constitute the initial population of equivalent processing hole arrangement order;

[0127] SA4, calculate the fitness function ;

[0128] A greedy selection strategy is adopted to obtain the equivalent processing hole set and its layout with the minimum number of equivalent processing holes based on the set of all possible equivalent processing holes in a certain order.

[0129] (A1);

[0130] (A2);

[0131] in:

[0132] is a function value of chromosomes in the order of equivalent processing holes, is the number of preferred equivalent processing holes, and is given by the function The solution is obtained;

[0133] A set of optimal equivalently machined holes;

[0134] The coordinates of each element in for Layout of medium-cost machined holes;

[0135] SA5, updates each chromosome in the equivalent processing hole arrangement order population through the selection of chromosomes with equivalent processing hole arrangement order and crossover and inversion mutation of equivalent processing hole layout coordinate genes;

[0136] According to the fitness function value of each chromosome in the population iteration process of the equivalent processing hole arrangement sequence, the crossover probability and mutation probability are dynamically and nonlinearly adjusted using trigonometric functions to accelerate the convergence of the algorithm.

[0137] SA6, after obtaining the offspring population through SA5, will be based on the interval ratio The retained populations of equivalent processing hole arrangement orders of the parent and child generations are recombined to obtain a new population of equivalent processing hole arrangement orders;

[0138] SA7, the number of algorithm iterations increases by 1, if the number of algorithm iterations reaches the maximum number of iterations , enter SA8;

[0139] Otherwise, return to SA4;

[0140] SA8, outputs the chromosome with the best fitness among the population of chromosomes with the order of equivalently processed holes;

[0141] SA9, simulated annealing algorithm parameter initial value: the specified temperature initial value is , set the current temperature , minimum temperature , cooling rate , chain length ;

[0142] SA10, a new solution for creating equivalent hole arrangement sequences based on the inversion mutation factor in the simulated annealing algorithm;

[0143] SA11, according to The criterion accepts a new solution for the arrangement order of equivalent machining holes. The specific process is: based on the function and the order of equivalent processing holes, the preferred number of equivalent processing holes As the energy of solution;

[0144] Preferably, let ,in , then with a certain probability Accept the new interpretation, as follows:

[0145] ;

[0146] in:

[0147] is the energy of the current optimal solution;

[0148] Energy for new solutions;

[0149] SA12, when the temperature When the cooling is completed, the process enters SA14;

[0150] If the current temperature When the temperature is iterated After that, , return to SA10;

[0151] SA13, the minimum energy value in the optimal solution of the equivalent processing hole arrangement sequence obtained by SA12 ;

[0152] SA14, the arrangement order of equivalent processing holes corresponding to the minimum energy value is the global optimal solution of the genetic-simulated annealing optimization process, and the energy minimum value corresponds to Another output of the function The coordinates of each element in is the optimal equivalent machining hole layout.

[0153] Preferably, the multi-spindle hole-making end effector 3 is connected to the robot 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 presser 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 base of the various components in the multi-spindle hole-making end effector 3.

[0154] The actuator frame 31 has a cubic frame structure, and one of the two opposite side plates of the actuator frame 31 is defined 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 visual unit 38 are all arranged on the first side plate 311, the feed group 33 and the solenoid valve group 34 are both arranged on the second side plate 312, the spindle group 32 is arranged in the actuator frame 31, and one end passes through the first side plate 311 and is connected to the presser foot group 35. The feed group 33 is used to control the extension or retraction of the corresponding spindle group 32 and the presser foot group 35.

[0155] Furthermore, the spindle group 32 is composed of n spindles in an array, the feed group 33 is composed of n cylinders in an array, and the presser foot group 35 is composed of n presser feet in an array, where n is an even number greater than 0. The number of the spindle group 32, feed group 33, and presser foot group 35 is the same, and each spindle and cylinder is arranged in a one-to-one correspondence with the presser foot. The cylinder is used to control the extension and retraction of the corresponding spindle and presser foot. Preferably, a spring 351 is provided between each presser foot and the first side plate 311 for pressing the presser foot against the surface of the acoustic lining perforated panel. Each spring 351 is respectively sleeved on the outer periphery of the spindle. Driven by each cylinder, the presser foot extends and, under the pressure of the spring, presses the surface of the acoustic lining perforated panel based on the friction between the end face of the presser foot and the perforated panel surface. This embodiment couples the acoustic lining component and the spindle hole-making end effector 3 into an integral whole to improve the rigidity and hole-making stability of the hole-making system and reduce vibration during the hole-making process.

[0156] In this embodiment, .

[0157] Furthermore, the multi-spindle hole-making end effector 3 also includes a vacuum tube group 39, which 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 suction, the chips generated during the acoustic lining hole making process are collected from the presser foot into a dust collector (not shown in the figure).

[0158] Furthermore, the solenoid valve group 34 is composed of n+1 solenoid valves in an array, and each solenoid valve includes two interfaces: an air inlet and an air outlet. A solenoid valve is used to control the extension and retraction of the cylinders in the cylinder array, and another solenoid valve is used to control the spindle air cooling. Preferably, a valve island 341 for mounting the solenoid valve group 34 is provided on the second side plate 312. The valve island 341 can independently control the solenoid valves in the solenoid valve group 34 based on the same air source.

[0159] 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 .

[0160] The laser displacement sensor group 37 includes four laser displacement sensors for measuring 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 to provide a basis for the end effector posture correction.

[0161] Vision unit 38 includes a light source for providing good lighting conditions for shooting, an industrial camera, and a telecentric lens for measuring the actual position coordinates of the reference holes. Its optical axis is parallel to the directions of the spindles on spindle assembly 32. The light source provides good lighting conditions for shooting, while the industrial camera and telecentric lens are used to measure the actual position coordinates of the reference holes. The hole-making direction deviation measurement system is used to control the object distance and optical axis direction during industrial camera measurement. After calculating the deviations between the actual positions of multiple reference holes and their corresponding nominal positions, a specific interpolation compensation strategy can be used to calculate the hole-making positioning error, providing a basis for correcting the end-effector position.

[0162] The positioning error measurement method of the multi-spindle hole-making end effector 3 is carried out in the following steps:

[0163] SB1, uses the vision unit integrated on the end effector of the robotic multi-spindle hole making system to capture the reference hole image;

[0164] The camera optical axis is defined to be parallel to the axis of the main axis array, and the object distance during visual shooting is and the perpendicularity between the optical axis and the acoustic lining surface , get the position of the visual unit when the focal distance is positive and the optical axis is perpendicular to the surface of the acoustic lining;

[0165] (B1);

[0166] in:

[0167] is the visual unit coordinate system Relative nacelle sound liner product coordinate system 's posture;

[0168] is the calibrated robot base coordinate system Relative to the product coordinate system 's posture;

[0169] To obtain the robot flange coordinate system based on the robot kinematic model Relative to the robot base coordinate system 's posture;

[0170] is the calibrated robot tool coordinate system Relative to the flange coordinate system 's posture;

[0171] The hand-eye relationship that has been calibrated is the visual unit coordinate system Relative to the tool coordinate system 's posture;

[0172] Indicates positive focal distance;

[0173] Indicates that the optical axis is perpendicular to the surface of the acoustic liner, that is, the angle is 90°;

[0174] SB2, after SB1, uses a reference hole feature localization algorithm that integrates visual saliency and mean shift to obtain robust, accurate, and efficient localization of the reference hole features in the reference hole image. The specific steps are as follows:

[0175] SB21, the original reference hole image obtained Perform Gaussian filtering or median filtering to obtain the corresponding smooth image ; For smooth images Perform image contrast stretching to obtain enhanced image , calculate the saliency map of the original reference hole image according to formula (2) ;

[0176] (B2);

[0177] in:

[0178] Indicates calculating the average pixel value of an image:

[0179] Indicates obtaining the maximum pixel value of the image;

[0180] Indicates the minimum pixel value of the image to be obtained;

[0181] SB22, select the salient image of the reference hole image through region screening The largest significant area in the middle, get the centroid coordinates of the largest significant area , calculate the coordinates of each pixel position and centroid coordinates of the saliency map according to formula (B3) Distance map ;

[0182] The weight graph is calculated according to formula (B4) ;

[0183] According to formula (B5) weight map With saliency map Multiply the corresponding elements of , clear the fragmented salient areas in the salient map, and get the updated salient map ;

[0184] (B3);

[0185] (B4);

[0186] (B5);

[0187] SB23, based on the automatic threshold segmentation method or by selecting an appropriate fixed threshold through repeatability testing, performs the saliency map updated by SB22. Perform threshold segmentation to segment the reference hole feature area from the saliency map;

[0188] Using edge detection operators or contour extraction algorithms, the fiducial hole contours are extracted from the threshold segmentation map of the saliency map. The contour point set is approximately evenly divided into three consecutive subsets. Contour points are randomly selected from the three subsets for circle fitting multiple times, and the coordinates of all fitted circle centers are stored in an array.

[0189] From all the candidate circle centers, select one as the initial center of mass, take it as the center, and use the mean shift algorithm to iteratively find the true center of mass of the circle center set based on the preset scanning radius as the reference hole center coordinate system. ;

[0190] SB3, set the image coordinate system at the center of the image, and its coordinate axis direction is the same as the default coordinate axis direction of the image. According to the coordinates of the center of the reference hole obtained by SB23 , combined with the calibrated visual unit parameters and the known image width and height ;

[0191] Define the XY plane of the vision unit coordinate system and its coordinate axes to coincide with the image coordinate plane and its coordinate system axes. According to formula (B6), the physical coordinates of the reference hole in the vision unit coordinate system are obtained. ;

[0192] (B6);

[0193] According to formula (B7) combined with SB1, we get , get the homogeneous transformation matrix expression of the reference hole in the product coordinate system , By the rotation matrix and translation vectors composition;

[0194] Translation vector The transpose of is the coordinate of the reference hole measured by the visual unit in the product coordinate system ;

[0195] (B7);

[0196] Combined with the nominal coordinates of the reference hole in the product coordinate system , get the hole positioning error at the reference hole ;

[0197] (B8);

[0198] SB4, repeat steps SB1 to SB3 for all reference holes, and measure the hole positioning errors at all reference holes through the visual system;

[0199] SB5, through surface interpolation, obtains the hole positioning errors of the remaining hole positions within the reference hole influence area and compensates for these errors.

[0200] By adopting the above-mentioned design scheme, the beneficial effects of the present invention are as follows: the equivalent processing hole generation strategy in the acoustic lining hole making of the aircraft engine nacelle of the present invention can generate suitable equivalent processing holes based on the acoustic lining processing point information of the area to be holed, and provide hole making positioning information for the robot multi-spindle hole making system, so as to prevent some acoustic lining holes in the hole making area from being missed, some acoustic lining holes from being repeatedly processed, and the spindles on the multi-spindle hole making end effector from not being fully utilized.

[0201] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for generating equivalent machining holes for acoustic lining holes in aircraft engine nacelles, characterized by: Follow these steps: S1, unfold the nacelle acoustic lining hole area surface into a plane, and complete it according to a certain row and column spacing Acoustic lining hole processing points Equivalence of the processing points of the acoustic lining holes, and definition of equivalent processing holes in the form of tuples ; （1）； in: is the horizontal coordinate numerical position coordinate of the equivalent machined hole on the plane of the hole making area; is the vertical coordinate value of the equivalent machined hole on the plane of the hole making area; is the number of acoustic lining holes processed after positioning the equivalent processing holes, ; , is the set of machining hole points on the plane corresponding to the equivalent machining hole and The number of elements in the collection is no more than ; The processing points of the acoustic lining holes to be processed corresponding to the spindles arranged in sequence, if The number of elements in the collection is less than , the processing point corresponding to the spindle that does not participate in processing is empty; S2, define the boundary direction of the bottom surface of the multi-spindle drilling end effector to be the same as the row and column direction of the acoustic lining holes in the drilling area; The hole-making operation of the multi-spindle hole-making end effector is regarded as a sequential scanning operation of the processing points of the acoustic lining hole, and the position of the multi-spindle hole-making end effector covering the processing points of the acoustic lining hole is determined. Equivalently machined holes And its corresponding acoustic lining hole processing point set Finally, the set of processing points of equivalent processing holes corresponding to acoustic lining holes is obtained ; （2）； in: is the position of the equivalent machining hole point set in the set S; The corresponding acoustic lining hole point set for all equivalently machined holes is a subset of the set S; S3, under the conditions of satisfying formulas (1) and (2), generates equivalent machining holes based on the greedy selection strategy, and prioritizes the number of machining holes. Larger equivalent machining holes , in the multi-spindle hole making end effector one-time positioning processing process to make full use of each spindle, the specific steps are as follows: S31, determined according to the number of spindles of the multi-spindle hole making end effector ,make , ; S32, select the corresponding hole according to the current equivalent processing sequence , enter S33; S33, if There are , enter S34; Otherwise, , return to S32; S34, if ,make , , enter S35; Otherwise, , return to S32; S35, if Established, enter S37; Otherwise, go to S36; S36, judgment Is it established? If established, let and , enter S37; Otherwise, , enter S32; S37, output all equivalent processing hole sets ; in: It is a collection of records of processed points.

2. The method for generating equivalent machining holes for acoustic lining holes of an aircraft engine nacelle according to claim 1, characterized in that: It is defined that when machining the nacelle acoustic lining holes, all acoustic lining holes in the hole making area are machined, and the same acoustic lining hole will not be machined repeatedly. Formula (2) adds the constraint condition of formula (3); （3）。 3. The method for generating equivalent machining holes for acoustic lining holes of an aircraft engine nacelle according to claim 1, characterized in that: 。 4. The method for generating equivalent machining holes for acoustic lining holes of an aircraft engine 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 presser foot group; The actuator frame includes a front plate and a rear plate arranged relatively to each other. The spindle group, feed group and solenoid valve group are all arranged in the inner cavity of the actuator frame. The presser foot group is arranged on the rear plate and is located on the outside of 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 connected to the presser foot group. The feed group is used to control the extension or retraction of the corresponding spindle group and presser foot group.

5. The method for generating equivalent machining holes for acoustic lining holes of an aircraft engine nacelle according to claim 4, characterized in that: Also included is a hole-making position error measurement system for measuring the angle between the hole-making direction of the equivalently machined hole of the multi-spindle hole-making end effector and the surface normal of the equivalently machined hole on the nacelle acoustic liner. The hole-making position error measurement system includes a laser displacement sensor group mounted on the multi-spindle hole-making end effector. The laser displacement sensor group includes four laser displacement sensors for respectively measuring 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 mounted at the four corners of the front plate, and the Z axis of the coordinate system is parallel to the hole-making direction. It also includes a hole-making direction deviation measurement system for measuring the position coordinates of prefabricated reference holes on the nacelle sound liner and calculating the hole-making position errors at the position coordinates of each reference hole. The hole-making direction deviation measurement system includes a visual unit installed on the multi-spindle hole-making end effector. The visual unit includes a light source for providing good shooting lighting conditions and 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.

6. The method for generating equivalent machining holes for acoustic lining holes of an aircraft engine nacelle according to claim 4, characterized in that: The spindle group includes n spindles, the feed group includes n cylinders, and the presser foot includes n presser feet, where n is an even number greater than 0. Each spindle and cylinder is set in a one-to-one correspondence with the presser foot, and each cylinder independently controls the extension and retraction of the corresponding spindle and presser foot. The solenoid valve group includes n+1 solenoid valves, each of which includes two interfaces: an air inlet and an air outlet. The n solenoid valves are used to control the extension and retraction of the cylinder, and the other solenoid valve is used to control the spindle air cooling switch.

7. The method for generating equivalent machining holes for acoustic lining holes of an aircraft engine nacelle according to claim 6, characterized in that: A spring is provided between each presser foot and the front plate to press the presser foot against the surface of the sound lining perforated panel, and the spring is correspondingly sleeved on the outer peripheral edge of the main shaft; an ultrasonic sensor group is also provided on the front plate, and 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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