Automatic drilling and riveting online programming method adapting to skin clamping posture and deformation deviation

Abstract

The present invention relates to the technical field of automatic drilling and riveting of aircraft skins, and in particular to an automatic drilling and riveting online programming method adapted to the clamping posture and deformation deviation of aircraft skins, comprising the following steps: generating theoretical tool positions and normal vector angles of skin reference pins and drill rivets in a digital model, positioning a drill riveting machine on site and measuring the reference pin position with a spatial position sensor and the reference pin normal vector angle with a normal sensor; obtaining theoretical and actual coordinate system transformation parameters by weighted ICP iterative calculation to obtain the optimal tool position of the drill rivet adapted to the actual clamping of the skin; obtaining the vector angle variation of each drill rivet between the actual reference pins, and then obtaining the drill rivet tool position normal vector angle adapted to the actual clamping of the skin; kinematically inversely solving the actual drill rivet tool position and the normal vector angle into the positioning position of each axis of the drill riveting machine, generating a processing program online and performing automatic drilling and riveting. The present invention effectively solves the problem that thin-walled and easily deformed curved aircraft skins cannot be assembled with high precision by automatic drilling and riveting.

Description

Technical Field

[0001] The invention relates to the technical field of automatic drilling and riveting of aircraft skins, and in particular to an automatic drilling and riveting online programming method adapting to aircraft skin clamping posture and deformation deviation. Background Art

[0002] At present, the aviation manufacturing field has higher and higher requirements for aircraft assembly quality. The drilling and riveting position and rivet normal accuracy of the connection between aircraft skin and structural parts directly affect the flight performance of the aircraft. With the rapid development of digital assembly technology, automatic drilling and riveting have been increasingly applied to the field of aircraft skin assembly and processing. However, with the increase in the variety of aircraft products, the increase in complexity and the stringent requirements for delivery quality, many aircraft skin products cannot be assembled by automatic drilling and riveting, especially thin-walled and easily deformed curved surface skins. Due to the influence of its own gravity, clamping support position and clamping force, the actual clamping posture and shape contour of the skin are quite different from the theoretical digital model, making it difficult to use traditional digital model offline programming methods for automatic drilling and riveting.

[0003] Traditional automatic drilling and riveting numerical control programming generally adopts the digital model offline programming method. With the help of CAM software, the drilling and riveting points in the drilling and riveting machine and the skin digital model are extracted, and the skin near the drilling and riveting points is locally projected to generate the normal of the skin of the drilling and riveting point domain. Finally, the theoretical digital model of the skin is assembled on the theoretical digital model of the drilling and riveting machine, and the processing path is planned, the drilling and riveting parameters are set, and the processing program is generated, thereby realizing the digital drilling and riveting assembly of the skin. For skins with large deformation, support tooling is usually added to reduce the skin deformation error, but it is still not completely consistent with the digital model, resulting in low processing accuracy and quality. In addition, the increase in support increases the number of interference parts, resulting in limited skin machinable area. Special conformal tooling must be customized for each type of skin, which not only increases the processing cost, but also brings great difficulties to the placement and use management of more customized tooling. Therefore, it is particularly necessary to explore a method for adaptive online programming based on the actual skin clamping posture and deformation. Summary of the invention

[0004] In order to solve the above-mentioned problems existing in the prior art, the present invention provides a complete and effective automatic drilling and riveting control method that adapts to the skin clamping posture and deformation deviation, which is used for high-precision automatic drilling and riveting assembly of thin-walled and easily deformed curved aircraft skin. The method of the present invention adopts an online control method to adaptively program the clamping posture and deformation of the aircraft skin, which can effectively solve the problem that the clamping posture and deformation of the skin have a large deviation relative to the theoretical digital model, and it is impossible to use digital model offline programming for automatic drilling and riveting. At the same time, it can ensure the high-precision requirements of the aircraft skin on the drilling and riveting position and the rivet normal, and effectively improve the quality of the automatic drilling and riveting assembly of the aircraft skin.

[0005] To achieve the above technical effects, the present invention is implemented through the following technical solutions:

[0006] An automatic drilling and riveting online programming method adapted to skin clamping posture and deformation deviation comprises the following steps:

[0007] Step 1: Generate theoretical tool positions and normal vector angles of skin reference pins and drill rivets in the digital model, locate the drill riveting machine on site, and measure the reference pin position with a spatial position sensor and the reference pin normal vector angle with a normal sensor;

[0008] Step 2: Based on the theoretical and actual reference pin spatial positions, the weighted ICP iterative operation is used to obtain the theoretical and actual coordinate system transformation parameters, and then the theoretical position of the drill rivet is transformed into the actual workpiece coordinate system and scaled to obtain the optimal tool position of the drill rivet that is suitable for the actual clamping of the skin;

[0009] Step 3, calculating the proportional relationship between the theoretical vector angle change of two adjacent reference pins and the vector angle change of each drill rivet therebetween, and according to the proportional relationship and the actual vector angle change of two adjacent reference pins, obtaining the vector angle change of each drill rivet between the actual reference pins, and then obtaining the normal vector angle of the drill rivet tool position adapted to the actual clamping of the skin;

[0010] Step 4: Inversely solve the actual drilling and riveting tool position and the normal vector angle kinematics into the positioning position of each axis of the drilling and riveting machine, generate the processing program online and perform automatic drilling and riveting.

[0011] Furthermore, the specific contents of the skin reference pins, drill rivets and drill riveting machine in step 1 are as follows: the skin reference pins are connecting pins for initial fixation of the skin and structural parts (stringers, legs, etc.), which have high position accuracy and have been assembled before automatic drilling and riveting; the drill rivets are connecting pins that need to be positioned and drilled during the automatic drilling and riveting process, and their rivet positions and normals have high processing accuracy requirements. The drill riveting machine described in this method is a five-axis CNC normal automatic drilling and riveting equipment.

[0012] Furthermore, the specific method for generating the theoretical tool position and normal vector angle of the reference pin and the drill rivet in the digital model in step 1 is that before the on-site online programming processing, the tool position P of the reference pin (>3) in the theoretical workpiece coordinate system ACS needs to be obtained offline in the digital model. A (x,y,z) and the normal vector V A (i, j, k), and the tool position D in the theoretical workpiece coordinate system of drilling rivets A (x,y,z) and the normal vector direction W A (i, j, k), and according to the rotary axis structure of the drilling and riveting machine, the normal vector direction is converted into the angle v corresponding to its space vector A (α,β),w A (α,β).

[0013] Furthermore, the specific method for obtaining the actual position and normal vector angle of the on-site reference pin in step 1 is that the execution end of the on-site drilling and riveting machine is equipped with a spatial position measurement and normal measurement sensor, and has the function of accurately measuring the spatial position of the reference pin and its domain surface normal detection, and the on-site positioning drilling and riveting machine is measured and the position P of the corresponding reference pin in the actual workpiece coordinate system BCS is measured. B (x,y,z) and the normal angle v B (α,β).

[0014] Furthermore, the specific method for determining the optimal fit transformation of the position and scaling based on the theoretical and actual reference pin positions in step 2 is: based on the theoretical position of the reference pin P A (x,y,z) and the actual position P B (x, y, z), use weighted ICP iterative operation to obtain the theoretical and actual coordinate system transformation parameters, including the translation parameter t, that is, the translation matrix [x0, y0, z0] T ; Rotation parameter R, that is, the rotation matrix [V x ,V y ,V z ] T ; Scale factor s,

[0015] The detailed calculation process is as follows: 1. According to the rotation transformation matrix model, the classical least squares method is used to calculate the translation and rotation parameters R0 and t0, and used as the initial value of the ICP iterative operation; 2. The residual of each benchmark pin point is calculated; 3. The weight of each benchmark pin point is calculated using the residual ratio; 4. The weighted centralization value is calculated; 5. The theoretical and actual benchmark pin point data after centralization are calculated; 6. The SVD model is established based on the centralized data; 7. The weighted translation and rotation parameters R1 and t1 are obtained by SVD decomposition; 8. It is used as the basis for calculating the weights in the next iteration, and the above steps 2-7 are repeated until the variances of all benchmark pin points converge to meet the stability requirements, thereby determining the optimal translation and rotation parameters R and t; 9. An adjustment model for the scale scaling parameter s is established, and the optimal scale scaling coefficient s is solved using the classical least squares method.

[0016] Furthermore, the specific method for determining the optimal tool position for drilling rivets in the actual workpiece coordinate system in step 2 is to use the optimal transformation translation matrix [x0, y0, z0] between the theoretical workpiece coordinate system and the actual workpiece coordinate system obtained based on the spatial position of the reference nail as described above. T With the rotation matrix [V x ,V y ,V z ] T , set all the theoretical drilling and rivet tool positions D A(x, y, z) is transformed into the actual workpiece coordinate system through rotation and translation operations. Then, according to the optimal size scaling coefficient s obtained above, the transformed tool positions of all drill rivets are scaled to obtain the optimal tool position D of all drill rivets in the actual workpiece coordinate system. B (x,y,z).

[0017] Furthermore, the specific method for determining the optimal tool position normal vector angle for drilling rivets in the actual workpiece coordinate system in step 3 is to use the theoretical normal angle change v of two adjacent reference nails (n and n+1) A n+1 -v A n The theoretical normal angle change w between each drill rivet (m and n) between two adjacent reference nails A m -v A n The proportional relationship, combined with the actual normal angle change v of the two adjacent reference pins B n+1 -v B n , calculate the actual normal angle change w of each drill rivet between two adjacent reference nails B m -v B n , find the best actual normal angle w of each drill rivet between two adjacent reference nails B m .

[0018] Furthermore, the specific method for calculating the positioning position of each geometric axis of the drilling and riveting machine in step 4 is to calculate the tool position D of all drill rivets in the actual workpiece coordinate system according to the obtained tool position D B (x,y,z) and the normal angle w B m (α, β), combined with the geometric structure of the automatic drilling and riveting machine, the normal vector V of the tool position for drilling rivets is obtained B (i, j, k), solve the tool position end position offset △x, △y, △z after rotating the drilling and riveting machine angle axis according to the tool position normal, and superimpose it into the tool position of drilling rivets to obtain the positioning positions of each geometric axis of the drilling and riveting machine corresponding to all drilled rivets, form a complete online programming plan and generate a processing program for automatic drilling and riveting processing and assembly.

[0019] The advantages of the present invention are:

[0020] 1. Aiming at the posture and deformation deviations caused by the clamping of aircraft skin, the present invention proposes an adaptive online programming method and provides a complete and different solution, which effectively solves the problem that thin-walled and easily deformed curved aircraft skin cannot be assembled by high-precision automatic drilling and riveting.

[0021] 2. The present invention is based on the theoretical tool position of the reference pins and drill rivets in the digital model, uses the actual tool position of the skin reference pins on site, and adopts a coordinate system fitting transformation method based on common points to transform and scale the optimal actual tool position of the drill rivet; based on the theoretical normal vector of the reference pins and drill rivets in the digital model, uses the actual tool position normal vector of the skin reference pin domain surface on site, and adopts a proportional replacement method of the theoretical and actual normal vector changes for the drill rivet between two adjacent reference pins to replace the actual tool position normal vector of the drill rivet; and the drilling and riveting machine axis positioning processing program is obtained through online post-processing of kinematic inverse solution. In this way, the actual skin clamping posture and deformation deviation are adapted, and the high-precision requirements of the skin on the drill rivet position and rivet normal are guaranteed.

[0022] 3. The online programming method that adapts to the clamping posture and deformation deviation of the skin proposed in the present invention is applicable to various types of digital processing equipment in the fixed-point processing of aircraft skins, and is particularly suitable for automatic assembly such as hole making, bushing crimping, and rivet riveting of completed thin-walled, easily deformed curved aircraft skins, and is suitable for wide promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a specific flow chart of the method of the present invention.

[0024] Figure 2 It is a schematic diagram of the theoretical tool position and normal vector of the digital model skinning method of the present invention.

[0025] Figure 3 It is a schematic diagram of the actual reference nail position and normal detection of the on-site skinning method of the present invention.

[0026] Figure 4 It is a schematic diagram of the on-site skin drilling rivet posture transformation and size scaling transformation mapping of the method described in the present invention.

[0027] Figure 5 It is a schematic diagram of the on-site skin drilling and rivet normal vector displacement of the method described in the present invention.

[0028] Reference numerals:

[0029] 1- Theoretical tool position of skin reference pin in digital model, 2- Theoretical tool position of skin drill rivet in digital model, 3- Normal vector of reference pin and drill rivet in digital model, 4- Theoretical workpiece coordinate system ACS of digital model, 5- Actual workpiece coordinate system BCS on site, 6- Actual tool position of skin reference pin on site, 7- Position and normal detection sensor of the end of drill and riveting machine, 8- Actual tool position normal vector of skin reference pin on site, 9- Optimal tool position mapping of skin drill rivet on site, 10- Optimal tool position normal vector replacement of skin drill rivet on site. DETAILED DESCRIPTION

[0030] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0031] It should be pointed out that all directional indications in the embodiments of the present invention (such as both sides, edges, up, down, left, right, front, back, middle, top, bottom, tail, axial, radial...) are only used to explain the relative position relationship, movement state, etc. between the components in a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0032] Example 1

[0033] An automatic drilling and riveting online programming method adapted to skin clamping posture and deformation deviation comprises the following steps:

[0034] Step 1: Generate theoretical tool positions and normal vector angles of skin reference pins and drill rivets in the digital model, locate the drill riveting machine on site, and measure the reference pin position with a spatial position sensor and the reference pin normal vector angle with a normal sensor;

[0035] The skin reference pins are the connecting pins for the initial fixation of the skin and structural parts (stringers, legs, etc.). They have high position accuracy and are assembled before automatic drilling and riveting. The drill rivets are the connecting pins that need to be positioned and drilled during the automatic drilling and riveting process. The rivet position and normal have high processing accuracy requirements. The drilling and riveting machine described in this method is a five-axis CNC normal automatic drilling and riveting equipment.

[0036] Before on-site online programming, the tool position P of the reference pins (>3) in the theoretical workpiece coordinate system ACS needs to be obtained offline in the digital model. A (x,y,z) and the normal vector V A (i, j, k), and the tool position D in the theoretical workpiece coordinate system of drilling rivets A (x,y,z) and the normal vector direction W A (i, j, k), and according to the rotary axis structure of the drilling and riveting machine, the normal vector direction is converted into the angle v corresponding to its space vector A (α,β),w A (α,β).

[0037] The on-site drilling and riveting machine is equipped with a spatial position measurement and normal measurement sensor at the execution end, and has the function of accurately measuring the spatial position of the reference pin and its domain surface normal detection. The drilling and riveting machine is positioned on-site and the position P of the corresponding reference pin in the actual workpiece coordinate system BCS is measured. B (x,y,z) and the angle v between the normal vector B (α,β).

[0038] Step 2: Based on the theoretical and actual reference pin spatial positions, the weighted ICP iterative operation is used to obtain the theoretical and actual coordinate system transformation parameters, and then the theoretical position of the drill rivet is transformed into the actual workpiece coordinate system and scaled to obtain the optimal tool position of the drill rivet that is suitable for the actual clamping of the skin;

[0039] Based on the theoretical position P of the reference pin A (x,y,z) and the actual position P B (x, y, z), use weighted ICP iterative operation to obtain the theoretical and actual coordinate system transformation parameters, including the translation parameter t, that is, the translation matrix [x0, y0, z0] T ; Rotation parameter R, that is, the rotation matrix [V x ,V y ,V z ] T ; Scale factor s,

[0040] The detailed calculation process is as follows: 1. According to the rotation transformation matrix model, the classical least squares method is used to calculate the translation and rotation parameters R0 and t0, and used as the initial value of the ICP iterative operation; 2. The residual of each benchmark pin point is calculated; 3. The weight of each benchmark pin point is calculated using the residual ratio; 4. The weighted centralization value is calculated; 5. The theoretical and actual benchmark pin point data after centralization are calculated; 6. The SVD model is established based on the centralized data; 7. The weighted translation and rotation parameters R1 and t1 are obtained by SVD decomposition; 8. It is used as the basis for calculating the weights in the next iteration, and the above steps 2-7 are repeated until the variances of all benchmark pin points converge to meet the stability requirements, thereby determining the optimal translation and rotation parameters R and t; 9. An adjustment model for the scale scaling parameter s is established, and the optimal scale scaling coefficient s is solved using the classical least squares method.

[0041] According to the optimal transformation translation matrix [x0, y0, z0] between the theoretical workpiece coordinate system and the actual workpiece coordinate system obtained based on the spatial position of the reference pin T With the rotation matrix [V x ,V y ,V z ] T , set all the theoretical drilling and rivet tool positions D A (x, y, z) is transformed into the actual workpiece coordinate system through rotation and translation operations. Then, according to the optimal size scaling coefficient s obtained above, the transformed tool positions of all drill rivets are scaled to obtain the optimal tool position D of all drill rivets in the actual workpiece coordinate system. B (x,y,z).

[0042] Step 3, calculating the proportional relationship between the theoretical vector angle change of two adjacent reference pins and the vector angle change of each drill rivet therebetween, and according to the proportional relationship and the actual vector angle change of two adjacent reference pins, obtaining the vector angle change of each drill rivet between the actual reference pins, and then obtaining the normal vector angle of the drill rivet tool position adapted to the actual clamping of the skin;

[0043] Using the theoretical normal angle change v of two adjacent reference pins (n ​​and n+1) A n+1 -v A n The theoretical normal angle change w between each drill rivet (m and n) between two adjacent reference nails A m -v A n The proportional relationship, combined with the actual normal angle change v of the two adjacent reference pins B n+1 -v B n , calculate the actual normal angle change w of each drill rivet between two adjacent reference nails B m -v B n , find the best actual normal angle w of each drill rivet between two adjacent reference nails B m .

[0044] Step 4: Inversely solve the actual drilling and riveting tool position and the normal vector angle kinematics into the positioning position of each axis of the drilling and riveting machine, generate the processing program online and perform automatic drilling and riveting.

[0045] According to the obtained tool position D of all drill rivets in the actual workpiece coordinate system B (x,y,z) and the normal angle w B m (α, β), combined with the geometric structure of the automatic drilling and riveting machine, the normal vector V of the tool position for drilling rivets is obtained B (i, j, k), solve the tool position end position offset △x, △y, △z after rotating the drilling and riveting machine angle axis according to the tool position normal, and superimpose it into the tool position of drilling rivets to obtain the positioning positions of each geometric axis of the drilling and riveting machine corresponding to all drilled rivets, form a complete online programming plan and generate a processing program for automatic drilling and riveting processing and assembly.

[0046] Example 2

[0047] Reference Figure 1-Figure 2As shown, this embodiment provides an automatic drilling and riveting online programming method that adapts to the skin clamping posture and deformation deviation. This method takes the application scenario where the on-site thin-walled curved surface skin clamping posture and deformation are both deviated from the theoretical numerical model as an embodiment. The position and normal detection sensor 7 has been adjusted and calibrated at the end of the on-site drilling and riveting machine actuator in advance. The specific implementation process of the present invention is as follows Figure 1 As shown, the following steps are included:

[0048] (1) Generate the theoretical tool position and normal vector angle of the skin reference pin and drill rivet in the digital model, locate the drill rivet machine on site, and use the spatial position sensor to measure the reference pin position and the normal sensor to measure the reference pin normal vector angle;

[0049] (2) Based on the theoretical and actual reference pin spatial positions, the weighted ICP iterative operation is used to obtain the theoretical and actual coordinate system transformation parameters, and then the theoretical position of the drill rivet is transformed into the actual workpiece coordinate system and scaled to obtain the drill rivet tool position that is suitable for the actual clamping of the skin;

[0050] (3) Calculate the proportional relationship between the vector angle change of two theoretically adjacent reference pins and the vector angle change of each drill rivet therebetween, and obtain the vector angle change of each drill rivet between the actual reference pins based on the proportional relationship and the actual vector angle change of two actual adjacent reference pins, and then obtain the normal vector angle of the drill rivet tool position suitable for the actual clamping of the skin;

[0051] (4) The actual drilling and riveting tool position and the normal vector angle kinematics are inversely solved into the positioning positions of each axis of the drilling and riveting machine, and the processing program is generated online to perform automatic drilling and riveting.

[0052] In order to better implement the method of the present invention, the step (1) is further introduced in detail. The specific contents of the skin reference pin 1, the drill rivet 2 and the drill riveting machine are as follows: the skin reference pin is a connecting pin for initially fixing the skin and the structural parts (stringers, legs, etc.), which has a high position accuracy and has been assembled before automatic drilling and riveting. The drill rivet is a connecting pin that needs to be positioned and drilled during the automatic drilling and riveting process, and its rivet position and normal have high processing accuracy requirements. The drill riveting machine described in this method is a five-axis CNC normal automatic drilling and riveting equipment.

[0053] For a further detailed description of step (1), refer to Figure 2 The specific method for generating the theoretical tool position and normal vector angle of the reference pin and the drill rivet in the digital model is that before the on-site online programming processing, the tool position P of the reference pin (>3) in the theoretical workpiece coordinate system ACS needs to be obtained offline in the digital model. A (x,y,z) and 3 normal vector directions V A (i, j, k), and the 2-tool position D in the theoretical workpiece coordinate system of drilling rivets A(x, y, z) and 3 normal vector W A (i, j, k), where i, j, k are the components of the normal vector in the three directions of the coordinate system, and the normal vector is converted into the vector direction into the normal angle v according to the rotating axis structure of the drilling and riveting machine. A (α, β), w A (α, β), taking the five-axis CNC automatic drilling and riveting equipment with A / C rotation angle structure as an example, as shown in Equation 1 and Equation 2.

[0054] α=A=cos -1 k Formula (1)

[0055] β=C=tan -1 (j / i) Formula (2)

[0056] For a further detailed description of step (1), refer to Figure 3 The specific method for obtaining the actual position and normal vector angle of the on-site reference pin is that the on-site drilling and riveting machine is equipped with a 7 spatial position measurement sensor (such as a 3D vision sensor) and a normal measurement sensor (such as a plane rhombus four-point distance sensor) at the execution end, and has the function of accurately measuring the spatial position of the reference pin and detecting its domain normal. When measuring the spatial position of the reference pin using the 3D vision sensor as an example, the identification reference image feature and the theoretical spatial position of the reference pin have been calibrated in advance. When measuring the domain normal vector around the reference pin using the plane rhombus four-point distance sensor as an example, the normal measurement reference plane has been calibrated in advance. By positioning the drilling and riveting machine on site and measuring the corresponding reference pin, its 6 position P in the 5 actual workpiece coordinate system BCS is obtained. B (x, y, z) with 8 normal angles v B (α, β).

[0057] The step (2) is further introduced in detail. The specific method for calculating the pose and scaling optimal fitting transformation based on the theoretical and actual reference pin positions is as follows: based on the reference pin theoretical position P A (x, y, z) and the actual position P B (x, y, z), and use weighted ICP iteration to obtain the theoretical and actual coordinate system transformation parameters, including the translation parameter t (i.e., the translation matrix [x0, y0, z0] T ), rotation parameters R (i.e. rotation matrix [V x , V y , V z ] T ), scale scaling factor s, the detailed calculation process is as follows: 1. According to the rotation transformation matrix model (Formula 3, Formula 4), x0, x0, x0 are the positions of the origin of the actual workpiece coordinate system in the theoretical workpiece coordinate system, X X , X Y , X Zis the vector direction of the X axis of the actual workpiece coordinate system in the theoretical workpiece coordinate system, and Y X , Y Y , Y Z is the vector direction of the Y axis of the actual workpiece coordinate system in the theoretical workpiece coordinate system, where Z X , Z Y , Z Z is the vector direction of the Z axis of the actual workpiece coordinate system in the theoretical workpiece coordinate system. The translation and rotation parameters R0 and t0 (Formula 9) are calculated using the classical least squares adjustment model (Formula 5, Formula 6) and its optimal parameter solution algorithm (Formula 8), and are used as the initial values ​​of the ICP iterative operation; 2. Calculate the residual e of each reference nail point i , as shown in formula 10; 3. Use the variance ratio to find the weight w of each benchmark nail point i , as shown in formula 11; 4. Calculate the weighted centralization value M A 、M B , as shown in formula 12; 5. Calculate the theoretical and actual benchmark pin point data P after centralization c A , P c B , as shown in formula 13; 6. Establish the SVD model H according to the centralized data, as shown in formula 14; 7. SVD decomposition obtains the weighted optimal translation and rotation parameters, as shown in formula 15, and the input values ​​R1 and t1 of the second iteration are not performed; 8. Use it as the basis for calculating the weights in the next iteration, and repeat the above 27 steps until the variances of all benchmark pin points converge to meet the stability requirements, thereby determining the optimal translation and rotation parameters R and t; 9. Further establish the adjustment model of the scale scaling parameter s (formula 16), and use the classical least squares method to solve the optimal scale scaling coefficient s, as shown in formulas 17 and 18.

[0058]

[0059]

[0060]

[0061]

[0062] min||e i ||2=min b ||Ab-Y||2 Formula (7)

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072] min||e i ||2=min b ||Ab-Y||2 Formula (17)

[0073]

[0074] For a further detailed description of step (2), refer to Figure 4 The specific method for determining the optimal tool position of the drill rivet in the actual workpiece coordinate system is to obtain the optimal transformation translation matrix t[x, y, z] between the theoretical workpiece coordinate system and the actual workpiece coordinate system based on the spatial positions of the reference pins 1 and 6. T With the rotation matrix R-[V x , V y , V z ] T , set all the digital model theoretical drill rivet 2 tool position position D A (x, y, z) is transformed into the actual workpiece coordinate system through rotation and translation operations. Then, according to the optimal size scaling coefficient s obtained above, all the transformed drill rivet tool positions are scaled by 9 to obtain the optimal tool position D of all drill rivets in the actual workpiece coordinate system. B (x, y, z), as shown in Formula 19.

[0075]

[0076] For a further detailed description of step (3), refer to Figure 5 The specific method for determining the optimal normal angle of the tool position for drilling rivets in the actual workpiece coordinate system is as follows: B m (α, β) where one of the direction angles α is taken as an example, as shown in formula 20, using the theoretical normal angle change v of two adjacent reference pins 8 A n+1 -v A n The change w of the 3 theoretical normal angles α of each drill rivet between two adjacent reference nailsA m -v A n The proportional relationship, combined with the actual normal angle change v of the two adjacent reference pins B n+1 -v B n , perform substitution 10, and obtain the actual normal angle change w of each drill rivet between two adjacent reference nails B m -v B n , where n represents the number of the reference pin, and m represents the number of the drill rivet between adjacent reference pins. Similarly, β is obtained, as shown in formula 21, and then the tool position normal angle w of the drill rivet in the actual workpiece coordinate system is obtained. B m (α, β).

[0077]

[0078]

[0079] The step (4) is further introduced in detail. The specific method for calculating the positioning position of each geometric axis of the drilling and riveting machine is to obtain the tool position D of all drill rivets in the actual workpiece coordinate system. B (x, y, z) and the normal angle w B m (α, β), combined with the geometric structure of the automatic drilling and riveting machine, taking the A / C rotating structure five-axis automatic drilling and riveting machine as an example, the normal vector direction V of the tool position for drilling rivets is obtained B (i, j, k) (Formula 22), according to the length L of the rotary arm of the rotating axis, solve the tool position end position offset Δx, Δy, Δz (Formula 23) after rotating the drilling and riveting machine angle axis in the normal direction of the tool position, and superimpose it into the tool position of the drill rivet to obtain the positioning positions X, Y, Z, A, C of each geometric axis of the drilling and riveting machine corresponding to all drill rivets (Formula 24), form a complete online programming plan and generate a processing program for automatic drilling and riveting processing and assembly.

[0080] i=sin αcosβ, j=sinαsinβ, k=cosα Formula (22)

[0081] ΔX=L*i, ΔY=L*j, ΔZ=L*k Formula (23)

[0082] X=x+AX=L*sinαcosβ

[0083] Y=y+ΔY=L*sinαsinβ

[0084] Z=z+ΔZ=L*cosα

[0085] A=α

[0086] C=B Formula (24)

[0087] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structures or equivalent processes made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. An automatic drilling and riveting online programming method that adapts to the skin clamping posture and deformation deviation, characterized by: The following steps are involved: Step 1: Generate theoretical tool positions and normal vector angles of skin reference pins and drill rivets in the digital model, locate the drill riveting machine on site, and measure the reference pin position with a spatial position sensor and the reference pin normal vector angle with a normal sensor; Step 2: Based on the theoretical and actual reference pin spatial positions, the weighted ICP iterative operation is used to obtain the theoretical and actual coordinate system transformation parameters, and then the theoretical position of the drill rivet is transformed into the actual workpiece coordinate system and scaled to obtain the optimal tool position of the drill rivet that is suitable for the actual clamping of the skin; Step 3, calculating the proportional relationship between the theoretical vector angle change of two adjacent reference pins and the vector angle change of each drill rivet therebetween, and according to the proportional relationship and the actual vector angle change of two adjacent reference pins, obtaining the vector angle change of each drill rivet between the actual reference pins, and then obtaining the normal vector angle of the drill rivet tool position adapted to the actual clamping of the skin; Step 4, inversely solve the actual drilling and riveting tool position and the normal vector angle kinematics into the positioning position of each axis of the drilling and riveting machine, generate the processing program online and perform automatic drilling and riveting; The specific method of obtaining the best fit transformation of the position and scaling based on the theoretical and actual reference pin positions in step 2 is as follows: A (x,y,z) and the actual position P B (x, y, z), use weighted ICP iterative operation to obtain the theoretical and actual coordinate system transformation parameters, including the translation matrix parameter t, that is, the translation matrix [x0, y0, z0] T ; Rotation parameter R, that is, the rotation matrix [V x ,V y ,V z ] T ; Scale scaling factor s; The calculation process is as follows: 1) According to the rotation transformation matrix model, the translation and rotation parameters R0 and t0 are calculated using the classical least squares method and used as the initial values ​​of the ICP iterative operation; 2) Calculate the residual of each benchmark nail point; 3) Use the variance ratio to calculate the weight w of each benchmark nail point i ; 4) Calculate the weighted centralization value; 5) Calculate the theoretical and actual benchmark nail point data after centralization; 6) Establish an SVD model based on the centralized data; 7) Decompose the weighted translation and rotation parameters R1 and t1 by SVD; 8) Use it as the basis for the next iteration to calculate the weight, and repeat the above 2)-7) steps until the variances of all benchmark nail points converge to meet the stability requirements, thereby determining the optimal translation and rotation parameters R and t; 9) Establish an adjustment model for the scale scaling parameter s, and use the classical least squares method to solve the optimal scale scaling coefficient s; The specific method for determining the optimal tool position for drilling rivets in the actual workpiece coordinate system in step 2 is to use the optimal transformation translation matrix t-[x, y, z] between the theoretical workpiece coordinate system and the actual workpiece coordinate system obtained based on the spatial position of the reference nail as described above. T With the rotation matrix R-[V x ,V y ,V z ] T , set all the theoretical drilling and rivet tool positions D A (x, y, z) is transformed into the actual workpiece coordinate system through rotation and translation operations. Then, according to the optimal size scaling coefficient s obtained above, the transformed tool positions of all drill rivets are scaled to obtain the optimal tool position D of all drill rivets in the actual workpiece coordinate system. B (x,y,z); The specific method for determining the optimal normal vector angle of the tool position for drilling rivets in the actual workpiece coordinate system in step 3 is to use the theoretical direction angle change v between two adjacent reference nails n and n+1 A n+1 -v A n The theoretical normal angle change w between the drill rivets m and n between two adjacent reference nails A m -v A n The proportional relationship, combined with the actual normal angle change v of the two adjacent reference pins B n+1 -v B n , find the best actual normal angle w of each drill rivet between two adjacent reference nails B m ; The specific method for calculating the positioning position of each geometric axis of the drilling and riveting machine in step 4 is as follows: B (x,y,z) and the normal angle w B m (α, β), combined with the geometric structure of the automatic drilling and riveting machine, the normal vector V of the tool position for drilling rivets is obtained B (i, j, k), solve the tool position end position offset △x, △y, △z after rotating the drilling and riveting machine angle axis according to the tool position normal, and superimpose it into the tool position of drilling rivets to obtain the positioning positions of each geometric axis of the drilling and riveting machine corresponding to all drilled rivets, form a complete online programming plan and generate a processing program for automatic drilling and riveting processing and assembly.

2. The automatic drilling and riveting online programming method adapted to the skin clamping posture and deformation deviation according to claim 1 is characterized in that: The specific contents of the skin reference pins, drill rivets and drill riveting machine in step 1 are as follows: the skin reference pins are connecting pins for initial fixation of the skin and the structural parts, and have been assembled before automatic drilling and riveting; the drill rivets are connecting pins that need to be positioned and drilled during the automatic drilling and riveting process; and the drill riveting machine is a five-axis CNC normal automatic drilling and riveting equipment.

3. The automatic drilling and riveting online programming method adapted to the skin clamping posture and deformation deviation according to claim 2 is characterized in that: The specific method for generating the theoretical tool position and normal vector angle of the reference pin and the drill rivet in the digital model in step 1 is that before the on-site online programming processing, the tool position P of multiple reference pins in the theoretical workpiece coordinate system ACS needs to be obtained offline in the digital model. A (x,y,z) and the normal vector V A (i, j, k), and the tool position D in the theoretical workpiece coordinate system of drilling rivets A (x,y,z) and the normal vector direction W A (i, j, k), and according to the rotary axis structure of the drilling and riveting machine, the normal vector direction is converted into the angle v corresponding to its space vector A (α,β),w A (α,β).

4. The automatic drilling and riveting online programming method adapted to the skin clamping posture and deformation deviation according to claim 3 is characterized in that: The specific method for obtaining the actual position and normal vector angle of the on-site reference pin in step 1 is that the execution end of the on-site drilling and riveting machine is equipped with a spatial position measurement and normal measurement sensor, and has the function of accurately measuring the spatial position of the reference pin and detecting its domain surface normal, positioning the drilling and riveting machine on-site and measuring the position P of the corresponding reference pin in the actual workpiece coordinate system BCS B (x,y,z) and the normal angle v B (α,β).

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