An assembly method and device for a special-shaped curved surface fitting in a helicopter

Abstract

The present invention relates to the technical field of accessory assembly, and particularly to an assembly method and device for special-shaped curved surface accessories in a helicopter. Before assembling the target accessory, the planned scanning paths for scanning the target accessory and the target skeleton are respectively determined, and based on the scanning results obtained according to the planned scanning paths, a first model corresponding to the target accessory and a second model corresponding to the target skeleton are established. The first model and the second model obtained in this way are more fitted to the physical objects, and can accurately reflect the positions and postures of the target accessory and the target skeleton. Furthermore, in this application, by comparing the first model and the second model, the contact stress distribution map when the target accessory and the target skeleton are assembled is predicted, so that before the worker assembles the target accessory to the target skeleton, the contact stress distribution map can be used to assemble with an assembly robot, thereby avoiding damage to the target accessory caused by excessive contact stress in advance.

Description

Technical Field

[0001] The present invention relates to the technical field of accessory assembly, and particularly to an assembly method and device for special-shaped curved surface accessories in a helicopter. Background Art

[0002] During the assembly process of accessories including special-shaped curved surfaces such as the windshield glass and cabin door of a large helicopter, for example, during the assembly process of the windshield glass, in the traditional assembly, a worker manipulates the robotic arm of an assembly robot to clamp the windshield glass and directly align it and install it onto the helicopter skeleton. During the alignment process, since the contact surface between the windshield glass and the skeleton is a special-shaped complex curved surface, especially the windshield glass is also a highly bright complex curved surface, when determining the position of the windshield glass through the camera held by the robotic arm, the image of the windshield glass captured by the camera is not clear, resulting in an inability to accurately judge the position and posture of the windshield glass, and further leading to the failure of the robotic arm to clamp the windshield glass or damage to the windshield glass.

[0003] In addition, during the process of directly aligning and installing the windshield glass onto the helicopter skeleton, due to some defects on the windshield glass or the helicopter skeleton (such as the shape of the assembly hole positions not corresponding, deformation, abnormal protrusions, etc.), contact stress will be generated during the installation process, resulting in damage to the windshield glass. Even if it is safely installed onto the helicopter skeleton, it may also be damaged due to contact stress during the subsequent use of the helicopter, which is very unsafe.

[0004] Based on this, the present invention proposes an assembly method and device for special-shaped curved surface accessories in a helicopter to solve the above technical problems. Summary of the Invention

[0005] The present invention describes an assembly method and device for special-shaped curved surface accessories in a helicopter, which can reduce damage to accessories during the assembly process.

[0006] According to a first aspect, the present invention provides an assembly method for special-shaped curved surface accessories in a helicopter, including:

[0007] According to the edge features respectively corresponding to the target accessory to be assembled and the target skeleton, respectively determine the planned scanning paths for scanning the target accessory and the target skeleton; wherein, the target accessory includes special-shaped curved surface accessories;

[0008] Scan the target accessory and the target skeleton according to the planned scanning paths, and establish a first model corresponding to the target accessory and a second model corresponding to the target skeleton based on the obtained scanning results;

[0009] Compare the first model and the second model, and predict the contact stress distribution map when the target accessory and the target skeleton are assembled based on the comparison result;

[0010] Use an assembly robot according to the contact stress distribution map to assemble the target fitting to the target framework.

[0011] According to a second aspect, the present invention provides an assembly device for a special-shaped curved surface fitting in a helicopter, including:

[0012] A planning unit configured to respectively determine a planned scanning path for scanning the target fitting and the target framework according to the edge features corresponding to the target fitting to be assembled and the target framework; wherein, the target fitting includes a special-shaped curved surface fitting;

[0013] A modeling unit configured to scan the target fitting and the target framework according to the planned scanning path, and establish a first model corresponding to the target fitting and a second model corresponding to the target framework based on the obtained scanning results;

[0014] A prediction unit configured to compare the first model and the second model, and predict a contact stress distribution map when the target fitting and the target framework are assembled based on the comparison result;

[0015] An assembly unit configured to use an assembly robot according to the contact stress distribution map to assemble the target fitting to the target framework.

[0016] According to the assembly method and device for a special-shaped curved surface fitting in a helicopter provided by the present invention, before assembling the target fitting, the present invention respectively determines a planned scanning path for scanning the target fitting and the target framework, and establishes a first model corresponding to the target fitting and a second model corresponding to the target framework based on the scanning results obtained according to the planned scanning path. The first model and the second model obtained in this way are more fitted to the physical objects, and can accurately reflect the positions and postures of the target fitting and the target framework. Furthermore, in this application, by comparing the first model and the second model, a contact stress distribution map when the target fitting and the target framework are assembled is predicted, so that before the worker assembles the target fitting to the target framework, the assembly robot can be used according to the contact stress distribution map to avoid damage to the target fitting caused by excessive contact stress in advance. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0018] Figure 1Shows a schematic flowchart of an assembly method for a special-shaped curved surface fitting in a helicopter according to an embodiment;

[0019] Figure 2 Shows a schematic flowchart of an assembly method for a special-shaped curved surface fitting in a helicopter according to another embodiment;

[0020] Figure 3 Shows a schematic block diagram of an assembly device for a special-shaped curved surface fitting in a helicopter according to an embodiment. Detailed implementation manners

[0021] The following describes the solution provided by the present invention in conjunction with the accompanying drawings.

[0022] Figure 1 Shows a schematic flowchart of an assembly method for a special-shaped curved surface fitting in a helicopter according to an embodiment. It can be understood that this method can be executed by any device, equipment, platform, or equipment cluster with computing and processing capabilities. As Figure 1 shown, this method includes:

[0023] Step 101: Respectively determine the planned scanning paths for scanning the target fitting and the target skeleton according to the edge features corresponding to the target fitting to be assembled and the target skeleton; wherein, the target fitting includes a special-shaped curved surface fitting;

[0024] In this embodiment, the target fitting refers to fittings including special-shaped curved surfaces such as the windshield glass and cabin door in a large helicopter before assembly. The target skeleton refers to the blank skeleton to which the target fitting needs to be installed, such as a helicopter skeleton. In this embodiment, the target fitting is clamped to the target skeleton by the robotic arm of the assembly robot to achieve the assembly of the target fitting and the target skeleton.

[0025] Step 102: Scan the target fitting and the target skeleton according to the planned scanning paths, and establish a first model corresponding to the target fitting and a second model corresponding to the target skeleton based on the obtained scanning results;

[0026] The planned scanning path refers to the path for scanning the target fitting and the target skeleton by a 3D scanner clamped at the end of the robotic arm of an assembly robot. The target fitting and the target skeleton respectively correspond to at least one planned scanning path. Exemplarily, the planned scanning path corresponding to the target fitting indicates multiple positions on the target fitting that the 3D scanner needs to photograph, as well as the photographing order of the multiple positions.

[0027] In this embodiment, for accessories with a high-brightness, irregular, and complex curved surface such as a windshield, there are the following difficulties in directly photographing an image with a depth camera and modeling it in the related art: Since the high-brightness background will cause local exposure of the photographed image and environmental reflections to appear, resulting in unclear imaging, and due to the irregular contour of the irregular curved surface, the photographed image cannot present the irregular characteristics of the irregular curved surface, and the defects of the edge contour of the irregular curved surface (such as abnormal protrusions) result in unclear defect images due to unclear imaging.

[0028] In this embodiment, by designing a planned scanning path for scanning the target accessory and the target skeleton, multiple scanning images are obtained by step-by-step scanning of the target accessory and the target skeleton, so as to improve the modeling accuracy corresponding to the target accessory and the target skeleton.

[0029] Step 103: Compare the first model and the second model, and predict the contact stress distribution map when the target accessory and the target skeleton are assembled based on the comparison result;

[0030] The above contact stress distribution map is used to characterize the contact stress that the target accessory will bear when the target accessory and the target skeleton are assembled. The generation of the contact stress here is mainly due to the contact stress caused by the mismatch of the shape or position of the assembly hole when connecting the target accessory and the target skeleton through screws and other assembly holes during assembly, the contact stress generated when the edges of the two are fitted due to abnormal protrusions, depressions, etc. on the target accessory or the target skeleton, and the contact stress generated when the edges of the two are fitted due to the deformation of the target accessory or the target skeleton, etc.

[0031] Step 104: Use an assembly robot to assemble the target accessory to the target skeleton according to the contact stress distribution map.

[0032] In specific implementation, a professional assembly worker can decide whether to perform the assembly according to the contact stress distribution map. After obtaining the contact stress distribution map, the professional assembly worker can decide whether to directly assemble or to correct the target accessory or the target skeleton before assembling according to professional knowledge.

[0033] In this embodiment, before assembling the target fitting, the planned scanning paths for scanning the target fitting and the target skeleton are determined respectively. Based on the scanning results obtained according to the planned scanning paths, a first model corresponding to the target fitting and a second model corresponding to the target skeleton are established. The first model and the second model obtained in this way are more fitted to the physical objects, and can accurately reflect the positions and postures of the target fitting and the target skeleton. Furthermore, in this application, by comparing the first model and the second model, the contact stress distribution map when the target fitting and the target skeleton are assembled is predicted, so that before the worker assembles the target fitting to the target skeleton, the assembly robot can be used for assembly according to the contact stress distribution map, and the damage of the target fitting caused by excessive contact stress can be avoided in advance.

[0034] The execution manners of the following Figure 1 shown steps are described.

[0035] For step 101:

[0036] In an embodiment of the present invention, the method for obtaining the edge features in step 101 includes:

[0037] The depth camera installed by the assembly robot is used to obtain the photos corresponding to the target fitting and the target skeleton respectively;

[0038] Based on the photos, a first initial model corresponding to the target fitting and a second initial model corresponding to the target skeleton are established;

[0039] Feature analysis is performed on the first initial model and the second initial model to obtain the edge features corresponding to the target fitting and the target skeleton respectively.

[0040] In this embodiment, after determining the approximate orientations of the target fitting and the target skeleton, the depth camera installed by the assembly robot is first used to take photos of the target fitting and the target skeleton, and at least one photo corresponding to the target fitting and the target skeleton is obtained. A first initial model corresponding to the target fitting is established based on the photo corresponding to the target fitting, and a second initial model corresponding to the target skeleton is established based on the photos corresponding to the target skeleton respectively. Since the first initial model and the second initial model are directly modeled using photos, the models are relatively rough. Therefore, it is necessary to further scan the target fitting and the target skeleton according to the planned scanning path below, and establish a first model corresponding to the target fitting and a second model corresponding to the target skeleton based on the obtained scanning results.

[0041] Establishing a first initial model corresponding to the target fitting and a second initial model corresponding to the target skeleton based on the photos can refer to 3D modeling in the related art, and this application does not limit this.

[0042] Regarding the above feature analysis of the first initial model and the second initial model to obtain the edge features corresponding to the target fitting and the target skeleton respectively, as an embodiment, this step includes:

[0043] Identify and mark each corner at the outer edge of the first initial model and the second initial model;

[0044] Take the features of each marked corner in the first initial model as the edge features corresponding to the target fitting, and take the features of each marked corner in the second initial model as the edge features corresponding to the target skeleton.

[0045] In this embodiment, each corner at the outer edge of the first initial model and the second initial model refers to the protruding corners of the outer contour of the first initial model and the second initial model. For example, if the target fitting is a windshield, then each corner at the outer edge of the first initial model actually corresponds to the four corners of the windshield. Identifying each corner at the outer edge of the first initial model and the second initial model here is mainly to determine the outer edges of the first initial model and the second initial model.

[0046] Regarding step 101, according to the edge features corresponding to the target fitting and the target skeleton to be assembled respectively, determine the planned scanning paths for scanning the target fitting and the target skeleton respectively, which may specifically include the following steps:

[0047] According to the edge features corresponding to the target fitting and the target frame to be assembled respectively, determine the position coordinates of the target fitting and the target skeleton relative to the assembly robot, as well as the contour coordinates of the target fitting and the target skeleton;

[0048] Based on the position coordinates and the contour coordinates, determine the direction change and position change of the 3D scanner when scanning the target fitting and the target skeleton;

[0049] Determine the direction change and position change of the 3D scanner as the planned scanning paths for scanning the target fitting and the target skeleton.

[0050] In this embodiment, the position coordinates of the assembly robot are known, and the position coordinates of the target fitting and the target skeleton relative to the assembly robot can be determined based on the position coordinates of the assembly robot and the distances between the assembly robot and the target fitting and the target skeleton. Among them, the distances between the assembly robot and the target fitting and the target skeleton can be determined by the photos taken when determining the edge features corresponding to the target fitting and the target skeleton to be assembled respectively.

[0051] Furthermore, based on the position coordinates of the assembly robot, the target fitting, and the position coordinates of the target skeleton relative to the assembly robot, the contour coordinates of the target fitting and the target skeleton can be further determined. The contour coordinates here can be the coordinates of each corner corresponding to the edge features determined in the above embodiments.

[0052] As an embodiment, for the target fitting or the target skeleton, based on their corresponding position coordinates and contour coordinates, the direction change and position change of the 3D scanner used for scanning the target fitting or the target skeleton can be determined. The area range that the 3D scanner needs to scan can be determined through the position coordinates. Furthermore, the direction change of the 3D scanner can be determined by the change direction of the coordinate values in the contour coordinates, and the position corresponding to the 3D scanner can be determined according to the positions of the contour coordinates in the change direction.

[0053] In specific implementation, after determining the above planned scanning path, scanning the target fitting and the target skeleton according to the planned scanning path includes:

[0054] For the direction change and position change of the 3D scanner, plan the motion scheme of each joint in the robotic arm that holds the 3D scanner;

[0055] Based on the motion scheme, control the robotic arm to hold the 3D scanner to scan the target fitting and the target skeleton.

[0056] In this embodiment, planning the motion scheme of each joint in the robotic arm that holds the 3D scanner is jointly achieved based on principles such as robot kinematics and the planned scanning path. The principles of robot kinematics and the like can refer to related technologies and will not be elaborated here.

[0057] The above motion scheme is used to control the robotic arm to scan the target fitting and the target skeleton according to the planned scanning path.

[0058] Based on the process of the robotic arm holding the 3D scanner to complete the scanning, for step 102:

[0059] Based on the obtained scanning results, establish the first model corresponding to the target fitting and the second model corresponding to the target skeleton, including:

[0060] Combine the motion trajectory formed after the robotic arm holds the 3D scanner to complete the scanning and the multiple scanning photos obtained by the 3D scanner to establish the first model corresponding to the target fitting and the second model corresponding to the target skeleton.

[0061] It should be noted that the multiple scanned photos obtained by the 3D scanner are not global photos of the target fitting and the target skeleton, but local detail photos of the target fitting and the target skeleton. Therefore, by combining the motion trajectory formed after the manipulator holds the 3D scanner to complete the scanning and the multiple scanned photos obtained by the 3D scanner, the first model and the second model established can accurately reflect the details of the target fitting and the target skeleton.

[0062] Preferably, the established first model and second model can be realized by optimizing the above-mentioned first initial model and second initial model, so as to obtain a first model and a second model that are more conforming to the actual object in combination with the global image presented by the photos.

[0063] Next, Figure 2 A schematic flow chart of an assembly method for a special-shaped curved surface fitting in a helicopter according to another embodiment shown will be described. It can be understood that this method can be executed by any device, equipment, platform, or equipment cluster with computing and processing capabilities. As Figure 2 shown, the method includes:

[0064] Step 201, respectively determine the planned scanning paths for scanning the target fitting and the target skeleton according to the edge features corresponding to the target fitting and the target skeleton to be assembled; wherein, the target fitting includes a special-shaped curved surface;

[0065] Step 202, scan the target fitting and the target skeleton according to the planned scanning paths, and establish a first model corresponding to the target fitting and a second model corresponding to the target skeleton based on the obtained scanning results;

[0066] The related descriptions of the above steps 201 and 202 can refer to the description of Figure 1 and will not be elaborated here.

[0067] Step 203, for the first model and the second model, determine the defect positions where contact stress exists when the first model and the second model are fitted to simulate the assembly of the target fitting and the target skeleton, and the predicted contact stress corresponding to the defect positions;

[0068] As an embodiment, calculating the predicted contact stress corresponding to each defect position can be achieved in the following manner:

[0069] First, according to the known stiffness of the target fitting, a flexible body mechanics model is established that can characterize the relationship between the deformation of the target fitting and the force screw. Then, when the target fitting and the target skeleton are fitted, due to the height difference at the defect position, contact stress will be generated. The role of the generated contact stress is to cause the target fitting to deform to adapt to the height difference. Therefore, for each defect position, through simulation experiments, the deformation degree corresponding to each defect position on the target fitting when the target skeleton fits the defect position in different postures can be estimated. Then, according to the stiffness of the target fitting and the estimated deformation degree of the defect position, the force screw (i.e., the predicted contact stress) when the defect position deforms corresponding to the height difference is determined.

[0070] Step 204, obtain the geometric and dimensional errors of each defect position; wherein, the geometric and dimensional errors include height error and shape error;

[0071] In this embodiment, the height error refers to the height difference generated when the first model and the second model are fitted. Ideally, the height difference should be 0 after the first model and the second model are fitted. However, due to possible deformations, protrusions, depressions, etc. in the first model and the second model, there may be a height difference at some points after the first model and the second model are fitted. The height error is characterized by the three-dimensional coordinates corresponding to the defect position. The shape error mainly refers to the error of inconsistent shape and misalignment of the corresponding part assembly hole positions between the first model and the second model when the first model and the second model are fitted. The shape error is characterized by the two-dimensional coordinates corresponding to the defect position.

[0072] Step 205, establish a mapping equation between the geometric and dimensional error and the contact stress according to the geometric and dimensional errors of each defect position and the corresponding predicted contact stress;

[0073] As an embodiment, assume that the mapping equation between the geometric and dimensional error and the contact stress is: geometric and dimensional error * k = contact stress. The predicted contact stress and geometric and dimensional error corresponding to each defect position have been obtained through the steps of the above embodiment, but the coefficient k is unknown. Therefore, to establish the mapping equation between the geometric and dimensional error and the contact stress, the value of k needs to be calculated. Exemplarily, k can be obtained by fitting the equation for the geometric and dimensional error and the contact stress.

[0074] Step 206, according to the installation direction of the target fitting assembled to the target skeleton, compare and match the edges of the first model and the second model to obtain the corresponding chromatogram when the first model and the second model are fitted; wherein, the chromatogram is used to characterize the geometric and dimensional errors of each point on the edges of the first model and the second model.

[0075] In this embodiment, the edges of the first model and the second model are compared and matched through simulation, and the height error and shape error (mainly the height difference here) existing on the mating contact surface (i.e., the edge) of the first model and the second model are obtained. Since the geometric tolerance on the mating contact surface of the first model and the second model has formed a surface from points, this embodiment uses a chromatogram to characterize the geometric tolerance of each point on the edges of the first model and the second model. Exemplarily, the darker the color of the chromatogram, the greater the geometric tolerance at that place.

[0076] Step 207: Based on the chromatogram and the mapping equation, perform digital simulation on the mating of the first model and the second model to predict the contact stress distribution map when the target fitting and the target skeleton are assembled.

[0077] Here, the digital simulation of the mating of the first model and the second model based on the chromatogram and the mapping equation can refer to relevant digital simulation technologies, and the present application does not limit the simulation technology.

[0078] Step 208: Use an assembly robot to assemble the target fitting to the target skeleton according to the contact stress distribution map.

[0079] In summary, before assembling the target fitting, the present invention respectively determines the planned scanning paths for scanning the target fitting and the target skeleton, and based on the scanning results obtained according to the planned scanning paths, establishes the first model corresponding to the target fitting and the second model corresponding to the target skeleton. In this way, the obtained first model and second model are more fitted to the physical objects and can accurately reflect the positions and postures of the target fitting and the target skeleton. Furthermore, the present application derives the mapping equation between the geometric tolerance and the contact stress by predicting the contact stress at the defect position, and then based on the chromatogram used to characterize the overall geometric tolerance when simulating the mating of the target fitting and the target skeleton, predicts the contact stress distribution map when the target fitting and the target skeleton are assembled. The prediction is more reasonable and accurate, and enables the worker to use an assembly robot for assembly according to the contact stress distribution map before assembling the target fitting to the target skeleton, thus avoiding damage to the target fitting caused by excessive contact stress in advance.

[0080] The following describes Figure 2 the execution manners of the following steps.

[0081] Regarding step 203:

[0082] Determining the defect positions where contact stress exists when the first model and the second model are mated to simulate the assembly of the target fitting and the target skeleton includes:

[0083] Identifying and marking each defect point and assembly hole position in the first model and the second model; wherein, the defect point is the position of abnormal protrusions and / or abnormal depressions carried when the target fitting and the target skeleton leave the factory.

[0084] For each defect position and assembly hole position, calculate the region features, gray-scale features, and gradient features corresponding to the defect position and the assembly hole position respectively, so as to serve as the defect features corresponding to the defect position and the assembly hole position respectively.

[0085] Compare each defect point position and assembly hole position in the first model and the second model, and based on the comparison result and the defect features corresponding to each defect point position and assembly hole position, obtain the form and position error corresponding to each defect point position and assembly hole position.

[0086] Determine the defect positions as the defect point positions and / or assembly hole positions whose form and position errors conform to the preset rules for generating contact stress.

[0087] In this embodiment, before identifying and marking each defect point position and assembly hole position in the first model and the second model, denoising preprocessing can be performed on the first model and the second model (including removing noise from the images within the contact surfaces (i.e., the surfaces that fit when the two are assembled) of the first model and the second model), and region segmentation can be performed on the first model and the second model (region segmentation is performed here considering that the target fitting is too large and is segmented into small images for processing).

[0088] When identifying and marking each defect point position and assembly hole position in the first model and the second model, for each segmented region, the position of the defect point position can be determined respectively according to the fact that the region features, gray-scale features, and gradient features of the pixel points corresponding to the defect point position are different from those of the surrounding pixel points, as well as the height difference from the surrounding adjacent point positions, and the position of the assembly hole position can be determined according to the preset position corresponding to the assembly hole position and the fact that the region features, gray-scale features, and gradient features of the pixel points corresponding to the assembly hole position are different from those of the surrounding pixel points, as well as the height difference from the surrounding adjacent point positions and the shape of the assembly hole position.

[0089] As an embodiment, based on the fact that the first model and the second model have an assembly relationship and the assembly hole positions need to correspond to each other when they are assembled, when comparing each defect point position and assembly hole position in the first model and the second model, the shapes and positions of the assembly hole positions with the same coordinates can be compared to determine the height error and shape error corresponding to the assembly hole positions, and the defect point positions in one model can be compared with the corresponding point positions in the other model to determine the height error and shape error corresponding to the defect point positions.

[0090] Preferably, in this embodiment, the comparison result obtained by comparing each defect point and assembly hole position in the first model and the second model can be used as the first comparison result, the comparison result obtained by comparing each defect point and assembly hole position in the first model with the first standard model can be used as the second comparison result, and the comparison result obtained by comparing each defect point and assembly hole position in the second model with the second standard model can be used as the third comparison result. By synthesizing the first comparison result, the second comparison result, and the third comparison result, the form and position error corresponding to each defect point and assembly hole position can be determined. Herein, the first standard model refers to the standard model corresponding to the target fitting without any defects in the ideal state, and the second standard model refers to the standard model corresponding to the target skeleton without any defects in the ideal state.

[0091] Finally, in this embodiment, the preset rule for generating contact stress can be that when the corresponding height error is greater than the preset height error, and / or the shape error is greater than the preset shape error, contact stress will be generated at the defect point or assembly hole position in the first model or the second model.

[0092] Regarding step 205:

[0093] According to the form and position errors of each defect position and the corresponding predicted contact stress, a mapping equation between the form and position error and the contact stress is established, including:

[0094] For the first model, according to the form and position errors of each defect position and the corresponding predicted contact stress, in combination with the stiffness of the target fitting, the rigid body coordinates of the simulated contact points between the assembly robot and the first model, and the flexible body coordinates of each assembly hole position on the first model relative to the simulated contact points, a mapping equation between the form and position error and the contact stress is established.

[0095] In this embodiment, the contact stress is related to factors such as the stiffness of the target fitting, the rigid body coordinates of the simulated contact points, and the flexible body coordinates of each assembly hole position relative to the simulated contact points. Additionally, in step 203, different poses of the target skeleton have a corresponding relationship with the rigid body coordinates of the simulated contact points. When the pose of the target skeleton is determined, the rigid body coordinates of the simulated contact points are also known. The flexible body coordinates of each assembly hole position relative to the simulated contact points have a corresponding relationship with the rigid body coordinates. When the rigid body coordinates are known, the flexible body coordinates can be calculated based on the rigid body coordinates. Therefore, preferably, in this embodiment, when calculating k, k can be set to include factors such as the rigid body coordinates, the flexible body coordinates, and the stiffness of the target fitting. By synthesizing the predicted contact stress and the rigid body coordinates, etc., corresponding to multiple poses of the target skeleton, the final k can be calculated.

[0096] Among them, the rigid body coordinates of the simulated contact point between the assembly robot and the first model refer to the coordinates of the simulated contact point between the assembly robot and the first model. The flexible body coordinates of each assembly hole position on the first model relative to the contact point mean that when the target fitting is a weak rigid structure, the assembly robot gripping the target fitting may cause slight deformation of the target fitting, so slight coordinate changes will occur in each assembly hole position. The coordinate changes cause the position coordinates of each assembly hole position to change relative to the rigid body coordinates of the simulated contact point. Therefore, the position coordinates of the assembly hole position after the change are the flexible body coordinates.

[0097] So far, the description of Figure 2 the process shown is completed.

[0098] The above describes specific embodiments of the present invention. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in a different order than in the embodiments and still achieve the desired result. Additionally, the processes depicted in the figures do not necessarily require the specific order or sequential order shown to achieve the desired result. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0099] According to an embodiment of another aspect, the present invention provides an assembly device for special-shaped curved surface fittings in a helicopter. Figure 3 The schematic block diagram of an assembly device for special-shaped curved surface fittings in a helicopter according to an embodiment is shown. It can be understood that the device can be implemented by any device, equipment, platform, and equipment cluster with computing and processing capabilities. As Figure 3 shown, the device includes: a planning unit 301, a modeling unit 302, a prediction unit 303, and an assembly unit 304. The main functions of each component unit are as follows:

[0100] The planning unit 301 is used to respectively determine the planned scanning paths for scanning the target fitting and the target skeleton according to the edge features corresponding to the target fitting to be assembled and the target skeleton; among them, the target fitting includes special-shaped curved surface fittings;

[0101] The modeling unit 302 is used to scan the target fitting and the target skeleton according to the planned scanning path, and establish the first model corresponding to the target fitting and the second model corresponding to the target skeleton based on the obtained scanning results;

[0102] The prediction unit 303 is used to compare the first model and the second model, and predict the contact stress distribution map when the target fitting and the target skeleton are assembled based on the comparison result;

[0103] An assembly unit 304 for using an assembly robot to assemble the target fitting to the target skeleton according to the contact stress distribution map.

[0104] As a preferred embodiment, the device further includes an acquisition unit for:

[0105] Obtaining photos corresponding to the target fitting and the target skeleton respectively through a depth camera installed on the assembly robot;

[0106] Based on the photos, establishing a first initial model corresponding to the target fitting and a second initial model corresponding to the target skeleton;

[0107] Performing feature analysis on the first initial model and the second initial model to obtain the edge features corresponding to the target fitting and the target skeleton respectively.

[0108] As a preferred embodiment, the acquisition unit performing feature analysis on the first initial model and the second initial model to obtain the edge features corresponding to the target fitting and the target skeleton respectively includes:

[0109] Identifying and marking each corner at the outer edge of the first initial model and the second initial model;

[0110] Taking the features of each marked corner in the first initial model as the edge features corresponding to the target fitting, and taking the features of each marked corner in the second initial model as the edge features corresponding to the target skeleton.

[0111] As a preferred embodiment, the planning unit 301 determines the position coordinates of the target fitting and the target skeleton relative to the assembly robot, and the contour coordinates of the target fitting and the target skeleton according to the edge features corresponding to the target fitting and the target skeleton to be assembled respectively;

[0112] Based on the position coordinates and the contour coordinates, determining the direction change and position change of the 3D scanner used for scanning the target fitting and the target skeleton;

[0113] Determining the direction change and position change of the 3D scanner as the planned scanning path for scanning the target fitting and the target skeleton.

[0114] As a preferred embodiment, the modeling unit 302 scanning the target fitting and the target skeleton according to the planned scanning path includes:

[0115] For the direction change and position change of the 3D scanner, planning the motion scheme of each joint in the robotic arm clamping the 3D scanner;

[0116] Control the robotic arm to clamp the 3D scanner to scan the target accessory and the target skeleton based on the motion plan;

[0117] The modeling unit 302 establishes a first model corresponding to the target accessory and a second model corresponding to the target skeleton based on the obtained scanning results, including:

[0118] Combining the motion trajectory formed after the robotic arm clamps the 3D scanner to complete the scanning and multiple scanning photos obtained by the 3D scanner, establish a first model corresponding to the target accessory and a second model corresponding to the target skeleton.

[0119] As a preferred embodiment, the device further includes an equation establishment unit for:

[0120] For the first model and the second model, determine the defect positions where contact stress exists when the first model and the second model are fitted to simulate the assembly of the target accessory and the target skeleton, and the predicted contact stress corresponding to the defect positions;

[0121] Obtain the geometric and dimensional errors of each defect position, where the geometric and dimensional errors include height errors and shape errors;

[0122] According to the geometric and dimensional errors of each defect position and the corresponding predicted contact stress, establish a mapping equation between the geometric and dimensional errors and the contact stress.

[0123] As a preferred embodiment, the equation establishment unit determines the defect positions where contact stress exists when the first model and the second model are fitted to simulate the assembly of the target accessory and the target skeleton, including:

[0124] Identify and mark each defect point and assembly hole position in the first model and the second model; the defect points are the positions of abnormal protrusions and / or abnormal depressions carried by the target accessory and the target skeleton when leaving the factory;

[0125] For each defect position and assembly hole position, calculate the region feature, grayscale feature, and gradient feature corresponding to the defect position and the assembly hole position respectively, as the defect features corresponding to the defect position and the assembly hole position respectively;

[0126] Compare each defect point and assembly hole position in the first model and the second model, and based on the comparison result and the defect features corresponding to each defect point and assembly hole position, obtain the geometric and dimensional errors corresponding to each defect point and assembly hole position;

[0127] Determine the defective points and / or assembly hole positions whose geometric and dimensional errors conform to the preset rules for generating contact stress as the defective positions.

[0128] As a preferred implementation manner, the equation establishing unit establishes a mapping equation between the geometric and dimensional errors and the contact stress according to the geometric and dimensional errors of the respective defective positions and the corresponding predicted contact stress, including:

[0129] For the first model, according to the geometric and dimensional errors of the respective defective positions and the corresponding predicted contact stress, in combination with the stiffness of the target fitting, the rigid body coordinates of the simulated contact points between the assembly robot and the first model, and the flexible body coordinates of each assembly hole position on the first model relative to the simulated contact points, establish a mapping equation between the geometric and dimensional errors and the contact stress.

[0130] Compare the first model and the second model, and predict the contact stress distribution diagram when the target fitting and the target skeleton are assembled based on the comparison result, including:

[0131] As a preferred implementation manner, the prediction unit 303 compares the first model and the second model, and predicts the contact stress distribution diagram when the target fitting and the target skeleton are assembled based on the comparison result, including:

[0132] According to the installation direction of the target fitting assembled to the target skeleton, compare and match the edges of the first model and the second model to obtain the corresponding chromatogram when the first model and the second model are fitted, and the chromatogram is used to characterize the geometric and dimensional errors of each point on the edges of the first model and the second model;

[0133] Based on the chromatogram and the mapping equation, perform digital simulation on the fitting of the first model and the second model, and predict the contact stress distribution diagram when the target fitting and the target skeleton are assembled.

[0134] According to an embodiment of another aspect, there is also provided a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed in a computer, the computer is made to execute the method combined with Figure 1 described.

[0135] According to an embodiment of still another aspect, there is also provided an electronic device, including a memory and a processor, where an executable code is stored in the memory, and when the processor executes the executable code, the method combined with Figure 1 is implemented.

[0136] Each embodiment in the present invention is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the device embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and reference can be made to the corresponding parts in the method embodiments for the relevant content.

[0137] Those skilled in the art should be able to realize that in one or more of the above examples, the functions described in the present invention can be implemented by hardware, software, firmware, or any combination thereof. When implemented using software, these functions can be stored in a computer-readable medium or transmitted as one or more instructions or codes on a computer-readable medium.

[0138] The specific embodiments described above further elaborate on the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made on the basis of the technical solution of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for assembling special-shaped curved surface accessories in a helicopter, characterized in that: include: According to the edge features corresponding to the target parts to be assembled and the target skeleton, respectively, the planned scanning paths for scanning the target parts and the target skeleton are determined; wherein the target parts include special-shaped curved surface parts; Scanning the target accessory and the target skeleton according to the planned scanning path, and establishing a first model corresponding to the target accessory and a second model corresponding to the target skeleton based on the obtained scanning results; Comparing the first model with the second model, and predicting a contact stress distribution diagram when the target accessory and the target skeleton are assembled based on the comparison result; Using an assembly robot to assemble the target accessory to the target skeleton according to the contact stress distribution diagram; Before comparing the first model with the second model, the method further includes: For the first model and the second model, the defective position where contact stress exists when the first model and the second model are fitted to simulate the assembly of the target accessory and the target skeleton, and the predicted contact stress corresponding to the defective position are determined; wherein the predicted contact stress corresponding to each defective position is calculated in the following manner: first, based on the known stiffness of the target accessory, a flexible body mechanics model for characterizing the relationship between the deformation and the force twist of the target accessory is established, and then based on the height difference between the defective position when the target accessory and the target skeleton are fitted, the contact stress will be generated, and the role of the generated contact stress is to cause the target accessory to deform to adapt to the height difference. Therefore, for each defective position, the corresponding deformation degree of each defective position on the target accessory when the target skeleton fits the defective position in different postures is estimated through simulation tests, and then, based on the stiffness of the target accessory and the estimated deformation degree of the defective position, the force twist when the defective position produces the corresponding deformation due to the height difference, that is, the predicted contact stress, is determined; Obtaining the shape and position errors of each defect position, wherein the shape and position errors include height errors and shape errors; wherein the height error is represented by the three-dimensional coordinates corresponding to the defect position, and the shape error is represented by the two-dimensional coordinates corresponding to the defect position; According to the shape and position errors of the defect positions and the corresponding predicted contact stresses, a mapping equation between the shape and position errors and the contact stress is established; The step of determining a defective position where contact stress exists when the first model and the second model are fitted to simulate assembly of the target accessory and the target skeleton comprises: Identify and mark each defect point and assembly hole position in the first model and the second model; the defect point is the position of abnormal protrusions and / or abnormal depressions carried by the target accessory and the target skeleton when they leave the factory; For each defect position and assembly hole position, calculating the regional features, grayscale features and gradient features respectively corresponding to the defect position and the assembly hole position as the defect features respectively corresponding to the defect position and the assembly hole position; Comparing each defect point and assembly hole position in the first model and the second model, and obtaining the shape and position errors corresponding to each defect point and assembly hole position based on the comparison result and the defect features corresponding to each defect point and assembly hole position; Defective points and / or assembly holes whose shape and position errors meet the preset rules for generating contact stress are determined as defective positions; wherein the preset rules for generating contact stress are that when the corresponding height error is greater than the preset height error, and / or the shape error is greater than the preset shape error, the defective points or assembly holes in the first model or the second model will generate contact stress.

2. The method according to claim 1, characterized in that The method for obtaining the edge feature includes: Acquire photos corresponding to the target accessory and the target skeleton respectively through a depth camera installed on the assembly robot; Establishing a first initial model corresponding to the target accessory and a second initial model corresponding to the target skeleton based on the photo; Feature analysis is performed on the first initial model and the second initial model to obtain edge features corresponding to the target accessory and the target skeleton, respectively.

3. The method according to claim 2, characterized in that Performing feature analysis on the first initial model and the second initial model to obtain edge features corresponding to the target accessory and the target skeleton, respectively, includes: Identifying and marking each corner of the first initial model and the second initial model that is located at the outer edge of the model; The features of each corner marked in the first initial model are used as edge features corresponding to the target accessory, and the features of each corner marked in the second initial model are used as edge features corresponding to the target skeleton.

4. The method according to claim 1 or 3, characterized in that: According to the edge features corresponding to the target parts to be assembled and the target skeleton, respectively, a planned scanning path for scanning the target parts and the target skeleton is determined, including: Determine the position coordinates of the target accessory and the target skeleton relative to the assembly robot, and the contour coordinates of the target accessory and the target skeleton according to the edge features corresponding to the target accessory and the target skeleton to be assembled; Determining, based on the position coordinates and the contour coordinates, a change in direction and a change in position of a 3D scanner used when scanning the target accessory and the target skeleton; The direction change and position change of the 3D scanner are determined as a planned scanning path for scanning the target accessory and the target skeleton.

5. The method according to claim 4, characterized in that Scanning the target accessory and the target skeleton according to the planned scanning path includes: Planning the motion scheme of each joint in the mechanical arm holding the 3D scanner according to the direction change and position change of the 3D scanner; Based on the motion scheme, control the robotic arm to clamp the 3D scanner to scan the target accessory and the target skeleton; Establishing a first model corresponding to the target accessory and a second model corresponding to the target skeleton based on the obtained scanning results includes: Based on the motion trajectory formed after the mechanical arm clamps the 3D scanner to complete the scanning and the multiple scanned photos obtained by the 3D scanner, a first model corresponding to the target accessory and a second model corresponding to the target skeleton are established.

6. The method according to claim 1, characterized in that According to the shape and position errors of each defect position and the corresponding predicted contact stress, a mapping equation between the shape and position errors and the contact stress is established, including: For the first model, according to the shape and position errors of each defect position and the corresponding predicted contact stress, combined with the stiffness of the target accessory, the rigid body coordinates of the simulated contact point between the assembly robot and the first model, and the flexible body coordinates of each assembly hole position on the first model relative to the simulated contact point, a mapping equation between the shape and position errors and the contact stress is established.

7. The method according to claim 1, characterized in that Comparing the first model with the second model, and predicting a contact stress distribution diagram when the target accessory and the target skeleton are assembled based on the comparison result, including: According to the installation direction of assembling the target accessory to the target skeleton, the edges of the first model and the second model are compared and matched to obtain a chromatogram corresponding to when the first model and the second model are fitted together, wherein the chromatogram is used to characterize the shape and position errors of each point on the edges of the first model and the second model; Based on the chromatogram and the mapping equation, the fit between the first model and the second model is digitally simulated to predict the contact stress distribution diagram when the target accessory and the target skeleton are assembled.

8. An assembly device for special-shaped curved surface accessories in a helicopter, characterized in that: include: A planning unit, used to determine a planned scanning path for scanning the target accessory and the target skeleton respectively according to edge features corresponding to the target accessory to be assembled and the target skeleton respectively; wherein the target accessory includes a special-shaped curved surface; a modeling unit, configured to scan the target accessory and the target skeleton according to the planned scanning path, and establish a first model corresponding to the target accessory and a second model corresponding to the target skeleton based on the obtained scanning results; A prediction unit, configured to compare the first model with the second model, and predict a contact stress distribution diagram when the target accessory and the target skeleton are assembled based on the comparison result; An assembly unit, configured to assemble the target accessory to the target skeleton using an assembly robot according to the contact stress distribution diagram; The device also includes an equation building unit for: For the first model and the second model, the defective position where contact stress exists when the first model and the second model are fitted to simulate the assembly of the target accessory and the target skeleton, and the predicted contact stress corresponding to the defective position are determined; wherein the predicted contact stress corresponding to each defective position is calculated in the following manner: first, based on the known stiffness of the target accessory, a flexible body mechanics model for characterizing the relationship between the deformation and the force twist of the target accessory is established, and then based on the height difference between the defective position when the target accessory and the target skeleton are fitted, the contact stress will be generated, and the role of the generated contact stress is to cause the target accessory to deform to adapt to the height difference. Therefore, for each defective position, the corresponding deformation degree of each defective position on the target accessory when the target skeleton fits the defective position in different postures is estimated through simulation tests, and then, based on the stiffness of the target accessory and the estimated deformation degree of the defective position, the force twist when the defective position produces the corresponding deformation due to the height difference, that is, the predicted contact stress, is determined; Obtaining the shape and position errors of each defect position, wherein the shape and position errors include height errors and shape errors; wherein the height error is represented by the three-dimensional coordinates corresponding to the defect position, and the shape error is represented by the two-dimensional coordinates corresponding to the defect position; According to the shape and position errors of each defect position and the corresponding predicted contact stress, a mapping equation between the shape and position errors and the contact stress is established; The equation building unit determines a defective position where contact stress exists when the first model and the second model are fitted to simulate the assembly of the target accessory and the target skeleton, including: Identify and mark each defect point and assembly hole position in the first model and the second model; The defect points are the abnormal protrusions and / or abnormal depressions that the target accessory and the target frame carry when they leave the factory; For each defect position and assembly hole position, calculating the regional features, grayscale features and gradient features respectively corresponding to the defect position and the assembly hole position as the defect features respectively corresponding to the defect position and the assembly hole position; Comparing each defect point and assembly hole position in the first model and the second model, and obtaining the shape and position errors corresponding to each defect point and assembly hole position based on the comparison result and the defect features corresponding to each defect point and assembly hole position; Defective points and / or assembly holes whose shape and position errors meet the preset rules for generating contact stress are determined as defective positions; wherein the preset rules for generating contact stress are that when the corresponding height error is greater than the preset height error, and / or the shape error is greater than the preset shape error, the defective points or assembly holes in the first model or the second model will generate contact stress.

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