Assembly robot and assembly method for special-shaped curved surface accessory in helicopter

Abstract

The present invention relates to the technical field of accessory assembly, and in particular to an assembly robot and assembly method for a special-shaped curved surface accessory in a helicopter. The assembly robot comprises a mobile chassis, laser sensors, a lifting / lowering mechanism, a controller, a robotic arm, a depth camera, a 3D scanner, a six-dimensional force sensor, and a clamp. The clamp is connected to an external air compressor. The mobile chassis is used for moving the position of the assembly robot. Each laser sensor is used for positioning a working position of the assembly robot. The lifting / lowering mechanism is used for changing the height of the robotic arm. The depth camera is used for capturing photos of a target accessory and a target framework. The 3D scanner is used for scanning the contours of the target accessory and the target framework. The six-dimensional force sensor is used for measuring the contact stress of the tail end of the robotic arm. The clamp is used for clamping the target accessor. The target accessory includes the special-shaped curved surface accessory. The technical solution can reduce damage to accessories during assembly.

Description

Assembly robot and assembly method for special-shaped curved surface accessory in helicopter TECHNICAL FIELD

[0001] The present application relates to the technical field of accessory assembly, in particular to an assembly robot and assembly method for special-shaped curved surface accessory in helicopter. BACKGROUND

[0002] In the assembly process of large helicopter windshield glass and cabin door and other accessories including special-shaped curved surface, such as the assembly process of windshield glass, the traditional assembly is to directly align the windshield glass installed to the helicopter skeleton by the mechanical arm of the assembly robot operated by workers. During the alignment process, since the contact surface of the windshield glass and the skeleton is a special-shaped complex curved surface, especially the windshield glass is a high-brightness complex curved surface, when the camera held by the mechanical arm determines the position of the windshield glass, the image of the windshield glass captured by the camera is not clear, which leads to the failure to accurately determine the position and posture of the windshield glass, and further leads to the failure of the mechanical arm to clamp the windshield glass or damage to the windshield glass.

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

[0004] Therefore, the present application provides an assembly robot and assembly method for special-shaped curved surface accessory in helicopter to solve the above technical problems. SUMMARY

[0005] The present application describes an assembly robot and assembly method for special-shaped curved surface accessory in helicopter, which can reduce the damage of the accessory during the assembly process.

[0006] According to a first aspect, the present application provides an assembly robot for special-shaped curved surface accessory in helicopter, comprising a mobile chassis, laser sensors arranged at two opposite corners of the mobile chassis, a lifting mechanism arranged on the mobile chassis, a controller arranged on the mobile chassis, a mechanical arm arranged on the lifting mechanism, a depth camera and a 3D scanner arranged on the mechanical arm, a six-dimensional force sensor and a clamp arranged at the end of the mechanical arm, the clamp being connected with an external air compressor, the controller being electrically connected with the mobile chassis, the laser sensor, the lifting mechanism, the mechanical arm, the depth camera, the force sensor and the air compressor respectively.

[0007] The mobile chassis is used to move the position of the assembly robot, the laser sensor is used to locate the working position of the assembly robot, the lifting mechanism is used to change the height of the mechanical arm, the depth camera is used to take photos of the target accessory and the target skeleton, the 3D scanner is used to scan the contour of the target accessory and the target skeleton, the six-dimensional force sensor is used to detect the contact stress of the end of the mechanical arm, and the clamp is used to clamp the target accessory.

[0008] According to a second aspect, the present application provides an assembly method of a special-shaped curved accessory in a helicopter, applied to a controller of an assembly robot, the assembly robot being the assembly robot described in the above embodiments, comprising:

[0009] According to the edge features corresponding to the target accessory and the target skeleton to be assembled respectively, a planned scanning path for scanning the target accessory and the target skeleton is determined respectively; wherein the target accessory comprises a special-shaped curved accessory;

[0010] According to the planned scanning path, the target accessory and the target skeleton are scanned, and based on the obtained scanning results, a first model corresponding to the target accessory and a second model corresponding to the target skeleton are established;

[0011] The first model and the second model are compared, and based on the comparison result, a contact stress distribution map when the target accessory and the target skeleton are assembled is predicted;

[0012] According to the contact stress distribution map, the target accessory is assembled to the target skeleton by using the assembly robot.

[0013] According to the assembly robot and the assembly method of the special-shaped curved accessory in the helicopter provided by the present application, by setting the mobile chassis, the position of the assembly robot can be moved; by setting the laser sensor, the working position of the assembly robot can be located; by setting the lifting mechanism, the height of the mechanical arm can be changed; by setting the depth camera, photos of the target accessory and the target skeleton can be taken; by setting the 3D scanner, the contour of the target accessory and the target skeleton can be scanned; by setting the six-dimensional force sensor, the contact stress of the end of the mechanical arm can be detected; by setting the clamp, the target accessory can be clamped; by setting the controller, the contact stress distribution map when the target accessory and the target skeleton are assembled can be predicted, so that the worker can use the assembly robot to assemble before assembling the target accessory to the target skeleton according to the contact stress distribution map, and the damage of the target accessory caused by excessive contact stress can be avoided in advance. BRIEF DESCRIPTION OF DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the accompanying drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained based on these drawings without creative labor.

[0015] Fig. 1 shows a structural schematic diagram of an assembly robot of a special-shaped curved surface accessory in a helicopter according to an embodiment;

[0016] Fig. 2 is an enlarged schematic diagram of a clamp in the assembly robot shown in Fig. 1;

[0017] Fig. 3 shows a flow schematic diagram of an assembly method of a special-shaped curved surface accessory in a helicopter according to an embodiment;

[0018] Fig. 4 shows a flow schematic diagram of an assembly method of a special-shaped curved surface accessory in a helicopter according to another embodiment.

[0019] Reference signs:

[0020] 10 - target accessory;

[0021] 1 - mobile chassis;

[0022] 11 - Mecanum wheel;

[0023] 2 - lifting mechanism;

[0024] 3 - controller;

[0025] 4 - mechanical arm;

[0026] 5 - clamp;

[0027] 51 - adjusting seat;

[0028] 52 - suction cup;

[0029] 53 - arc-shaped hole. DETAILED DESCRIPTION

[0030] The schemes provided by the present application will be described below in combination with the accompanying drawings.

[0031] As shown in Figure 1, the embodiment of the present application provides an assembly robot for irregular curved surface accessories in a helicopter, characterized in that it comprises a mobile chassis 1, laser sensors (not shown in the figure) arranged at two opposite corners of the mobile chassis 1, a lifting mechanism 2 arranged on the mobile chassis 1, a controller 3 arranged on the mobile chassis 1, a mechanical arm 4 arranged on the lifting mechanism 2, a depth camera (not shown in the figure) and a 3D scanner (not shown in the figure) arranged on the mechanical arm 4, a six-dimensional force sensor (not shown in the figure) and a clamp 5 arranged at the end of the mechanical arm 4, the clamp 5 being connected with an external air compressor, and the controller 3 being electrically connected with the mobile chassis 1, the laser sensors, the lifting mechanism 2, the mechanical arm 4, the depth camera, the force sensor and the air compressor respectively.

[0032] The mobile chassis 1 is used to move the position of the assembly robot, the laser sensors are used to locate the working position of the assembly robot, the lifting mechanism 2 is used to change the height of the mechanical arm 4, the depth camera is used to take photos of the target accessory 10 and the target skeleton, the 3D scanner is used to scan the profile of the target accessory 10 and the target skeleton, the six-dimensional force sensor is used to detect the contact stress at the end of the mechanical arm 4, and the clamp 5 is used to clamp the target accessory 10, and the target accessory 10 comprises an irregular curved surface accessory.

[0033] In the embodiment, the position of the assembly robot can be moved by arranging the mobile chassis 1, the working position of the assembly robot can be located by arranging the laser sensors, the height of the mechanical arm 4 can be changed by arranging the lifting mechanism 2, the photos of the target accessory 10 and the target skeleton can be taken by arranging the depth camera, the profile of the target accessory 10 and the target skeleton can be scanned by arranging the 3D scanner, the contact stress at the end of the mechanical arm 4 can be detected by arranging the six-dimensional force sensor, the target accessory 10 can be clamped by arranging the clamp 5, and the contact stress distribution diagram when the target accessory and the target skeleton are assembled can be predicted by arranging the controller 3, so that the worker can use the assembly robot to assemble before assembling the target accessory to the target skeleton according to the contact stress distribution diagram, and the damage of the target accessory caused by excessive contact stress can be avoided in advance.

[0034] The present application can realize flexible movement and accurate positioning in complex and variable industrial environments, and complete the curved surface scanning detection and auxiliary installation of the helicopter windshield and cabin door through the development of a composite mobile robot (i.e. an assembly robot) for helicopter collaborative assembly.

[0035] The composite mobile robot has the following functions:

[0036] 1) It can adapt to complex and variable helicopter assembly environments, and the composite mobile robot system should be able to realize flexible movement in a small space and achieve accurate positioning through multi-sensor information fusion;

[0037] 2) The composite mobile robot should be able to accurately reach the workpiece grabbing, glass assembly and hatch assembly stations, and ensure that no safety problems occur during movement;

[0038] 3) The composite robot can accurately find the position of the connecting point on the aircraft fuselage and achieve high-precision repeated positioning to meet the requirements of precision and quality in the aerospace manufacturing field.

[0039] It can be understood that large components such as windshield glass and cabin doors are inconvenient to move, and need to be assembled and scanned after the composite mobile robot is moved to the station near the helicopter body. Therefore, the coordinate position of the helicopter body in the surrounding environment needs to be determined, and the coordinate position of the composite mobile robot is monitored in real time, so that the composite mobile robot can accurately reach the target position. In the present application, LMS110 laser sensors can be used. The general processing process of laser sensor scanning data extraction information is data processing, clustering, segmentation, fitting and finally positioning.

[0040] In the test environment, there are multiple columns around the composite mobile robot, which are wrapped with reflective plates. Two LMS110 laser sensors are installed on the right front and left rear of the motion platform, respectively, and each completes 270-degree scanning and data acquisition of the surrounding environment. The laser sensor can identify the position of the reflective plate based on the reflected energy, and determine the coordinate position of the system in the environment through the triangle or three-edge method.

[0041] In an embodiment of the present application, the mobile chassis 1 includes Mecanum wheels 11 located at four corners. Mecanum wheels have advantages that other wheeled structures do not have. The present application selects Mecanum wheels to build a full-coverage motion platform, which carries an industrial robot and can realize full-coverage motion and zero-radius rotation in a plane. The moving method is effective and comprehensive, and has great advantages in adapting to the changing aerospace manufacturing environment.

[0042] In order to improve the assembly precision and overturning stability, the robot system needs to be kept stationary during the assembly operation. An auxiliary support component is selected to be installed at the bottom of the motion platform. When the motion platform moves to the assembly station, the auxiliary support acts to lift the entire motion platform and ensure the stability of the robot, and then the composite mobile robot performs assembly operation.

[0043] The six-axis force sensor at the end of the robot adopts a Jianan intelligent six-axis force sensor matched with the robot control. The force sensor is installed between the end of the mechanical arm and the gripper tooling, which can sense the force in the glass / cabin door assembly process in real time, and feedback the sensing information to the robot controller after decoupling, and adjust the glass attitude in time.

[0044] Depth camera machine vision detection is a technology that uses depth cameras (also known as depth cameras or stereo cameras) for machine vision detection. Unlike traditional 2D cameras, depth cameras can capture depth information of objects in a scene, allowing machines to more accurately understand and analyze the three-dimensional structure and position of objects.

[0045] The principle of depth camera machine vision detection mainly includes the following steps:

[0046] 1) Depth perception: Depth cameras use different depth perception technologies (such as structured light, ToF (Time of Flight), binocular stereo vision, etc.) to measure the distance of each point in the object and scene. These technologies obtain depth information by emitting light or laser and measuring its return time or displacement.

[0047] 2) Point cloud data generation: Through depth perception, depth cameras can calculate the three-dimensional coordinates of each point in the scene, forming a three-dimensional point cloud data. Point cloud is a set of points represented in three-dimensional space, each point having XYZ coordinates.

[0048] 3) Object recognition and detection: Based on the obtained 3D point cloud data, machine learning algorithms and computer vision techniques can perform object recognition and detection. These algorithms can identify and detect different objects in the scene based on their shape, size, depth, and other features.

[0049] 4) Position and pose estimation: In addition to recognizing objects, depth cameras can accurately measure the position and pose of objects. By analyzing the point cloud data of an object, information such as the object's position, pose, and rotation angle can be obtained.

[0050] A robotic arm generally consists of a mechanical hand, a motion mechanism, and a control cabinet. The robotic arm is mainly used for grabbing and assembling glass workpieces, and during the driving process of the equipment chassis, the robotic arm needs to adjust the pose to maintain the overall balance of the equipment to prevent the human-machine-assisted equipment from overturning due to uneven counterweight.

[0051] Among them, the end-effector can be used for grabbing and placing actions, and can also be replaced by other end-effectors to realize various forms of work. The end-effectors of the human-machine collaborative equipment mainly include suction cup clamps for sucking glass workpieces, and 3D scanners for fixing glass workpieces to replace hands to complete three-dimensional model scanning and acquisition of glass workpieces and window frames.

[0052] The motion mechanism is the joint and arm of the robotic arm, and the joint part is driven by a motor to realize the movement, rotation and stretching action of the whole robotic arm, and the final purpose is to adjust the pose of the robotic arm to perform a given action.

[0053] The robot end clamp is used for grabbing the installed front windshield glass and cabin door assembly, wherein the windshield glass assembly has a total weight of about 20 kg, the surface shape is irregular, and the bending range is large; the cabin door assembly has a total weight of about 25 kg, and the surface bending range is small. In order to realize reliable grabbing of the two target workpieces of the front windshield glass and the cabin door assembly, a portable adjustable end clamp is designed, the clamp adopts a lightweight support connecting rod design, and there are 8 groups of adjustable height and direction suction disc modules, the height and direction angle of each suction disc can be conveniently adjusted through a bolt clamping mechanism, so that the clamp and the surface curvature of the workpiece are matched during grabbing, and the same clamp is used to realize grabbing of the windshield glass and the cabin door.

[0054] The robot end clamp is composed of a mounting seat, a clamp support, a suction disc connecting rod, a suction disc direction adjusting seat and a vacuum suction disc. The clamp mounting seat is connected with the sixth joint end flange of the robot through bolts; the clamp support is the main structural support component of the suction disc clamp, and needs to have sufficient rigidity and stability, is made of lightweight materials such as aluminum alloy and carbon fiber rod, and is hollow designed to reduce the overall weight of the clamp.

[0055] In an embodiment of the present application, the lifting mechanism 2 comprises a ball screw (not shown in the figure) and a motor (not shown in the figure) connected to each other, and the end of the ball screw is connected with the mechanical arm 4.

[0056] As shown in FIG. 2, in an embodiment of the present application, the clamp 5 comprises an adjusting seat 51 and a suction disc 52 connected to each other, the suction disc 52 is used for sucking the target accessory 10, and the adjusting seat 51 is used for adjusting the angle of the pitch direction of the suction disc 52, so that the suction disc 52 is perpendicular to the surface of the target accessory 10, all suction discs generate maximum suction force, and safe and reliable grabbing and carrying are realized.

[0057] In an embodiment of the present application, the adjusting seat 51 is provided with an arc-shaped hole 53, and the angle of the pitch direction of the suction disc 52 is adjusted through the arc-shaped hole 53.

[0058] FIG. 3 shows a flowchart of an assembly method of a special-shaped curved surface accessory in a helicopter according to an embodiment. It can be understood that the method can be executed by any device, equipment, platform, cluster of equipment with computing and processing capabilities. As shown in FIG. 3, the method comprises:

[0059] Step 301, according to the edge features corresponding to the target accessory and the target skeleton respectively, a planned scanning path for scanning the target accessory and the target skeleton is determined respectively; wherein the target accessory comprises a special-shaped curved surface accessory;

[0060] In this embodiment, the target accessory refers to an accessory with a complex curved surface, such as a windshield and a cabin door of a large helicopter before assembly. The target skeleton refers to a blank skeleton to which the target accessory is to be mounted, such as a helicopter skeleton. In this embodiment, the target accessory is clamped to the target skeleton by the mechanical arm of the assembly robot, and the assembly of the target accessory and the target skeleton is realized.

[0061] Step 302: 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;

[0062] The planned scanning path refers to the path of scanning the target accessory and the target skeleton by a 3D scanner clamped at the end of the mechanical arm of the assembly robot. The target accessory and the target skeleton correspond to at least one planned scanning path respectively. For example, the planned scanning path corresponding to the target accessory indicates the positions on the target accessory that need to be photographed by the 3D scanner and the photographing order of the positions.

[0063] In this embodiment, the accessory with a high-brightness complex curved surface, such as a windshield, has the following difficulties in modeling by directly photographing images by a depth camera in the related art: the high-brightness background causes local exposure and environmental reflection in the photographed images, resulting in unclear imaging; and the irregular profile of the complex curved surface cannot be presented in the photographed images, and the defects (such as abnormal protrusions) of the edge profile of the complex curved surface are also not clear in the images due to unclear imaging.

[0064] In this embodiment, the planned scanning path for scanning the target accessory and the target skeleton is designed, and a plurality of scanning images are obtained by step-by-step scanning of the target accessory and the target skeleton, so as to improve the modeling accuracy of the target accessory and the target skeleton.

[0065] Step 303: Compare the first model and the second model, and predict the contact stress distribution map of the target accessory and the target skeleton during assembly based on the comparison result;

[0066] The contact stress distribution map is used to represent the contact stress that the target accessory will bear during assembly of the target accessory and the target skeleton. The contact stress is mainly caused by the following factors: the contact stress caused by the mismatch of the shape or position of the assembly hole during assembly of the target accessory and the target skeleton by connecting the target accessory and the target skeleton through screws; the contact stress caused by the abnormal protrusions, depressions, etc. on the target accessory or the target skeleton during edge fitting of the target accessory and the target skeleton; and the contact stress caused by the deformation of the target accessory or the target skeleton during edge fitting of the target accessory and the target skeleton.

[0067] Step 304, according to the contact stress distribution map, using the assembly robot, assembling the target accessory to the target skeleton.

[0068] In practice, the professional assembly worker can determine whether to assemble according to the contact stress distribution map. After obtaining the contact stress distribution map, the professional assembly worker can determine whether to directly assemble or to modify the target accessory or the target skeleton before assembling according to professional knowledge.

[0069] In the embodiment, before assembling the target accessory, the planned scanning path for scanning the target accessory and the target skeleton is determined respectively, the first model corresponding to the target accessory and the second model corresponding to the target skeleton are established based on the scanning results obtained according to the planned scanning path, and the first model and the second model obtained are more fitted to the real object, which can accurately reflect the position and posture of the target accessory and the target skeleton. Then, the application compares the first model and the second model to predict the contact stress distribution map when the target accessory and the target skeleton are assembled, so that the worker can use the assembly robot to assemble according to the contact stress distribution map before assembling the target accessory to the target skeleton, and avoid damage to the target accessory caused by excessive contact stress in advance.

[0070] The execution mode of each step shown in FIG. 3 is described below.

[0071] For step 301:

[0072] In an embodiment of the application, the method for obtaining the edge feature in step 301 comprises:

[0073] The depth camera installed by the assembly robot obtains the photos corresponding to the target accessory and the target skeleton respectively;

[0074] Based on the photos, the first initial model corresponding to the target accessory and the second initial model corresponding to the target skeleton are established;

[0075] The feature analysis is performed on the first initial model and the second initial model to obtain the edge features corresponding to the target accessory and the target skeleton respectively.

[0076] In the embodiment, after the approximate positions of the target accessory and the target framework are determined, the target accessory and the target framework are photographed by a depth camera installed by the assembly robot to obtain at least one photo corresponding to the target accessory and the target framework respectively, a first initial model corresponding to the target accessory is established based on the photo corresponding to the target accessory, and a second initial model corresponding to the target framework is established based on the photo corresponding to the target framework. The first initial model and the second initial model are relatively rough because they are directly modeled by using the photos, and thus further scanning of the target accessory and the target framework needs to be performed according to the planned scanning path, and a first model corresponding to the target accessory and a second model corresponding to the target framework are established based on the obtained scanning results.

[0077] The first initial model corresponding to the target accessory and the second initial model corresponding to the target framework are established based on the photos. The 3D modeling in the related art can be referred to, and the present application is not limited in this regard.

[0078] As to the feature analysis of the first initial model and the second initial model to obtain the edge features corresponding to the target accessory and the target framework respectively, as an embodiment, the step includes:

[0079] Each corner at the outer edge of the first initial model and the second initial model is identified and marked;

[0080] The features of each corner marked in the first initial model are taken as the edge features corresponding to the target accessory, and the features of each corner marked in the second initial model are taken as the edge features corresponding to the target framework.

[0081] In the embodiment, each corner at the outer edge of the first initial model and the second initial model refers to the corner protruding from the outer contour of the first initial model and the second initial model. For example, if the target accessory is a windshield, each corner at the outer edge of the first initial model actually corresponds to the four corners of the windshield. The identification of each corner at the outer edge of the first initial model and the second initial model is mainly to determine the outer edge of the first initial model and the second initial model.

[0082] For step 301, the planned scanning path for scanning the target accessory and the target framework is determined according to the edge features corresponding to the target accessory and the target framework respectively. Specifically, the step can include the following steps:

[0083] The position coordinates of the target accessory and the target framework relative to the assembly robot and the contour coordinates of the target accessory and the target framework are determined according to the edge features corresponding to the target accessory and the target framework respectively;

[0084] The direction change and the position change of the 3D scanner used for scanning the target accessory and the target framework are determined based on the position coordinates and the contour coordinates.

[0085] The direction change and the position change of the 3D scanner are determined as a planned scanning path for scanning the target accessory and the target skeleton.

[0086] In this embodiment, the position coordinates of the assembly robot are known, and the position coordinates of the target accessory 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 accessory and the target skeleton. The distances between the assembly robot and the target accessory and the target skeleton can be determined by the photos taken when the edge features corresponding to the target accessory and the target skeleton to be assembled are determined.

[0087] Further, based on the position coordinates of the assembly robot and the position coordinates of the target accessory and the target skeleton relative to the assembly robot, the contour coordinates of the target accessory and the target skeleton can be further determined. The contour coordinates here can be the coordinates of the corners corresponding to the edge features determined in the above embodiments.

[0088] As an embodiment, for the target accessory or the target skeleton, the direction change and the position change of the 3D scanner used for scanning the target accessory or the target skeleton can be determined based on the corresponding position coordinates and contour coordinates. The range of the area to be scanned by the 3D scanner can be determined by the position coordinates, and then the direction change of the 3D scanner can be determined by the direction of change of the coordinate values in the contour coordinates, and the corresponding position of the 3D scanner can be determined according to the position of the contour coordinates in the direction of change.

[0089] In specific implementation, after the planned scanning path is determined, the target accessory and the target skeleton are scanned according to the planned scanning path, including:

[0090] For the direction change and the position change of the 3D scanner, a motion scheme of each joint of the mechanical arm holding the 3D scanner is planned;

[0091] Based on the motion scheme, the mechanical arm holding the 3D scanner is controlled to scan the target accessory and the target skeleton.

[0092] In this embodiment, the motion scheme of each joint of the mechanical arm holding the 3D scanner is planned based on the principles of robot kinematics and the planned scanning path, and the principles of robot kinematics can refer to related technologies, which will not be described here.

[0093] The motion scheme is used to control the mechanical arm to scan the target accessory and the target skeleton according to the planned scanning path.

[0094] Based on the process of scanning by the mechanical arm holding the 3D scanner, for step 302:

[0095] The first model corresponding to the target accessory and the second model corresponding to the target skeleton are established based on the obtained scanning results, and the first model and the second model are established based on the obtained scanning results.

[0096] The first model corresponding to the target accessory and the second model corresponding to the target skeleton are established based on the obtained scanning results, and the first model and the second model are established based on the obtained scanning results.

[0097] It should be noted that the plurality of scanning photos obtained by the 3D scanner are not global photos of the target accessory and the target skeleton, but are local detail photos of the target accessory and the target skeleton. Therefore, the first model and the second model established by combining the motion trajectory formed after the scanning of the 3D scanner and the plurality of scanning photos obtained by the 3D scanner can accurately reflect the details of the target accessory and the target skeleton.

[0098] Preferably, the first model and the second model can be obtained by optimizing the first initial model and the second initial model to obtain a first model and a second model that are more consistent with the real object in combination with the global image presented by the photos.

[0099] The flowchart of the assembly method of the special-shaped curved accessory in the helicopter shown in FIG. 4 according to another embodiment is described below. It can be understood that the method can be executed by any device, equipment, platform, or cluster of equipment having computing and processing capabilities. As shown in FIG. 4, the method comprises:

[0100] Step 401, according to the edge features corresponding to the target accessory and the target skeleton respectively, a planned scanning path for scanning the target accessory and the target skeleton is determined respectively; wherein the target accessory comprises a special-shaped curved surface;

[0101] Step 402, 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;

[0102] The descriptions of steps 401 and 402 above can be referred to the description of FIG. 3, which will not be repeated here.

[0103] Step 403, for the first model and the second model, determining the defect positions where the first model and the second model are in contact stress when simulating the assembly of the target accessory and the target skeleton, and the predicted contact stress corresponding to the defect positions;

[0104] As an embodiment, the predicted contact stress corresponding to each defect position can be calculated by the following method:

[0105] First, according to the rigidity of the known target accessory, a soft body mechanics model is established, which can represent the relationship between the deformation of the target accessory and the force moment, and then based on the target accessory and the target skeleton, due to the height difference at the defect position, contact stress is generated, which causes the target accessory to deform to adapt to the height difference, so for each defect position, the deformation degree of each defect position on the target accessory when the target skeleton is fitted at different postures can be estimated through simulation test, and then according to the rigidity of the target accessory and the estimated deformation degree of the defect position, the force moment (i.e. the predicted contact stress) corresponding to the deformation of the defect position due to the height difference is determined.

[0106] In step 404, the geometric and positional errors of each defect position are obtained; wherein the geometric and positional errors include height errors and shape errors;

[0107] In this embodiment, the height error refers to the height difference generated when the first model and the second model are fitted, and in an ideal case, the height difference after the first model and the second model are fitted should be 0, but due to the possible deformation or protrusions, depressions and other defects of the first model and the second model, there may be height differences at some point positions after the first model and the second model are fitted, and the height error is represented by the three-dimensional coordinates corresponding to the defect position. The shape error mainly refers to the error of the shape inconsistency and position inconsistency that may exist in the corresponding part of the assembly hole of the first model and the second model when the first model and the second model are fitted, and the shape error is represented by the two-dimensional coordinates corresponding to the defect position.

[0108] In step 405, a mapping equation between the geometric and positional errors and the contact stress is established according to the geometric and positional errors of each defect position and the corresponding predicted contact stress;

[0109] As an example, assume that the mapping equation between the geometric and positional errors and the contact stress is: geometric and positional error * k = contact stress, the predicted contact stress and the geometric and positional error corresponding to each defect position are known through the above steps, but the coefficient k is unknown, so the mapping equation between the geometric and positional error and the contact stress needs to calculate the value of k, and for example, the value of k can be obtained by equation fitting of the geometric and positional error and the contact stress.

[0110] In step 406, the edges of the first model and the second model are compared and matched according to the mounting direction of the target accessory assembled to the target skeleton, and the corresponding chromatogram when the first model and the second model are fitted is obtained; wherein the chromatogram is used to represent the geometric and positional errors of each point on the edges of the first model and the second model.

[0111] In this embodiment, the edges of the first model and the second model are matched by simulation, and the height error and shape error (here, mainly the height difference) existing on the contact surface (i.e., the edge) of the first model and the second model are obtained. Since the shape error on the contact surface of the first model and the second model has been formed into a surface by points, the shape error of each point on the edge of the first model and the second model is characterized by a chromatogram in this embodiment. For example, the deeper the color of the chromatogram, the greater the shape error at that position.

[0112] In step 407, the fitting of the first model and the second model is simulated digitally based on the chromatogram and the mapping equation, and a contact stress distribution map when the target accessory and the target skeleton are assembled is predicted.

[0113] Here, the fitting of the first model and the second model based on the chromatogram and the mapping equation can be simulated digitally by referring to related digital simulation techniques, and the simulation techniques are not limited in the present application.

[0114] In step 408, the target accessory is assembled to the target skeleton using an assembly robot according to the contact stress distribution map.

[0115] In summary, before assembling the target accessory, the planned scanning path for scanning the target accessory and the target skeleton is determined respectively, the first model corresponding to the target accessory and the second model corresponding to the target skeleton are established 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 real object, and can accurately reflect the position and posture of the target accessory and the target skeleton. Then, the mapping equation between the shape error and the contact stress is derived by predicting the contact stress at the defect position, and the contact stress distribution map when the target accessory and the target skeleton are assembled is predicted based on the chromatogram used to characterize the overall shape error of the simulated fitting of the target accessory and the target skeleton. The prediction is more reasonable and accurate, and the worker can use the assembly robot to assemble the target accessory to the target skeleton according to the contact stress distribution map before assembling the target accessory to the target skeleton, so as to avoid damage to the target accessory caused by excessive contact stress in advance.

[0116] The execution mode of each step shown in FIG. 4 is described below.

[0117] For step 403:

[0118] The defect position where the 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 includes:

[0119] Each defect point and assembly hole in the first model and the second model is identified and marked. The defect point is the position of the abnormal protrusion and / or abnormal depression carried by the target accessory and the target skeleton when leaving the factory.

[0120] For each defect position and assembly hole position, the area feature, the gray scale feature and the gradient feature corresponding to the defect position and the assembly hole position are calculated respectively as the defect feature corresponding to the defect position and the assembly hole position.

[0121] Each defect point position and assembly hole position in the first model and the second model are compared, and based on the comparison result and the defect feature corresponding to each defect point position and assembly hole position, the form and position error corresponding to each defect point position and assembly hole position is obtained.

[0122] The defect point position and / or assembly hole position whose form and position error meets the preset rule of generating contact stress is determined as the defect position.

[0123] In the embodiment, before each defect point position and assembly hole position in the first model and the second model is identified and marked, the first model and the second model can be preprocessed by denoising (including removing noise from the image in the contact surface (i.e. the surface that adheres when the two are assembled) range of the first model and the second model), and the first model and the second model are regionally segmented (here, regional segmentation is considered because the target accessory is too large, and the image is segmented into small pieces for processing).

[0124] After each defect point position and assembly hole position in the first model and the second model is identified and marked, for each segmented region, the position of the defect point position can be determined according to the area feature, the gray scale feature and the gradient feature of the pixel point corresponding to the defect point position being different from the surrounding pixel points, and the height difference with the surrounding adjacent point position, and the position of the assembly hole position can be determined according to the area feature, the gray scale feature and the gradient feature of the pixel point corresponding to the assembly hole position being different from the surrounding pixel points, and the height difference with the surrounding adjacent point position and the shape of the assembly hole position.

[0125] As an embodiment, based on the first model and the second model having an assembly relationship, the assembly hole positions need to correspond when the two are assembled, therefore, by comparing each defect point position and assembly hole position in the first model and the second model, the shape and position 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 position in one model and the corresponding point position in the other model can be compared to determine the height error and shape error corresponding to the defect point position.

[0126] Preferably, in the embodiment, the comparison result of each defect point and assembly hole in the first model and the second model can be taken as the first comparison result, the comparison result of each defect point and assembly hole in the first model and the first standard model can be taken as the second comparison result, the comparison result of each defect point and assembly hole in the second model and the second standard model can be taken as the third comparison result, and the shape and position error corresponding to each defect point and assembly hole can be determined by comprehensively considering the first comparison result, the second comparison result and the third comparison result. The first standard model refers to a standard model corresponding to the target assembly without any defects, and the second standard model refers to a standard model corresponding to the target skeleton without any defects.

[0127] Finally, in the embodiment, the preset rule for generating the contact stress can be that the defect point or the assembly hole in the first model or the second model will generate the contact stress when the corresponding height error is greater than the preset height error and / or the shape error is greater than the preset shape error.

[0128] For step 405:

[0129] According to the shape and position error of each defect position and the corresponding predicted contact stress, a mapping equation between the shape and position error and the contact stress is established, including:

[0130] For the first model, according to the shape and position error of each defect position and the corresponding predicted contact stress, the mapping equation between the shape and position error and the contact stress is established in combination with the stiffness of the target assembly, 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 on the first model relative to the simulated contact point.

[0131] In the embodiment, the contact stress has a correlation with the stiffness of the target assembly, the rigid body coordinates of the simulated contact point and the flexible body coordinates of each assembly hole relative to the simulated contact point, etc. In addition, in step 403, different postures of the target skeleton have a corresponding relationship with the rigid body coordinates of the simulated contact point. In the case where the posture of the target skeleton is determined, the rigid body coordinates of the simulated contact point are also known. The flexible body coordinates of each assembly hole relative to the simulated contact point have a corresponding relationship with the rigid body coordinates. In the case where the rigid body coordinates are known, the flexible body coordinates can be calculated according to the rigid body coordinates. Therefore, preferably, in the embodiment, when k is calculated, k can be set to include the rigid body coordinates, the flexible body coordinates, the stiffness of the target assembly and other factors, and the corresponding predicted contact stress and rigid body coordinates under multiple postures of the target skeleton are comprehensively considered to calculate the final k.

[0132] The rigid body coordinates of the simulated contact points between the assembly robot and the first model are coordinates of the simulated contact points between the assembly robot and the first model. The flexible body coordinates of each assembly hole on the first model relative to the contact points are that, when the target accessory is a weak rigid structure, the assembly robot may cause slight deformation of the target accessory when picking up the target accessory, so that each assembly hole may change slightly in coordinates. The change in the coordinates of each assembly hole causes the position coordinates of each assembly hole to change relative to the rigid body coordinates of the simulated contact points, so that the position coordinates of each assembly hole after the change are flexible body coordinates.

[0133] Thus far, the description of the flow shown in FIG. 4 is complete.

[0134] The above describes specific embodiments of the present application. Other embodiments are within the scope of the appended claims. In some cases, the acts or steps recited in the claims can be performed in a different order than those described in the embodiments and still achieve desirable results. In addition, the processes depicted in the figures do not necessarily require the particular order shown or sequential order to achieve the desired results. In certain implementations, multitasking and parallel processing can be advantageous.

[0135] Each of the embodiments in the present application is described in a progressive manner, and the same or similar parts between the embodiments can be referred 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 the relevant parts can be referred to the part of the method embodiments.

[0136] Those skilled in the art should be aware that, in one or more examples described above, the functions described in the present application can be implemented in hardware, software, firmware or any combination thereof. When implemented in 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.

[0137] The above specific embodiments further detail the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made on the basis of the technical solutions of the present application should be included in the protection scope of the present application.

Claims

1. An assembly robot for a special-shaped curved surface fitting in a helicopter, characterized by, The assembly robot comprises a mobile chassis, laser sensors arranged at two opposite corners of the mobile chassis, a lifting mechanism arranged on the mobile chassis, a controller arranged on the mobile chassis, a mechanical arm arranged on the lifting mechanism, a depth camera and a 3D scanner arranged on the mechanical arm, a six-dimensional force sensor arranged at the end of the mechanical arm, and a clamp connected to an external air compressor, wherein the controller is electrically connected to the mobile chassis, the laser sensors, the lifting mechanism, the mechanical arm, the depth camera, the force sensor, and the air compressor respectively. The mobile chassis is used to move the position of the assembly robot, the laser sensors are used to locate the working position of the assembly robot, the lifting mechanism is used to change the height of the mechanical arm, the depth camera is used to take photos of the target accessory and the target skeleton, the 3D scanner is used to scan the contours of the target accessory and the target skeleton, the six-dimensional force sensor is used to detect the contact stress at the end of the mechanical arm, and the clamp is used to clamp the target accessory.

2. The assembly robot of claim 1, wherein, The mobile chassis comprises Mecanum wheels arranged at four corners.

3. The assembly robot of claim 1, wherein, The lifting mechanism comprises a ball screw and a motor connected to each other, and the end of the ball screw is connected to the mechanical arm.

4. The assembly robot of claim 1, wherein, The clamp comprises an adjusting seat and a suction cup connected to each other, the suction cup is used to suck the target accessory, and the adjusting seat is used to adjust the angle of the suction cup in the pitch direction to make the suction cup perpendicular to the surface of the target accessory.

5. The assembly robot of claim 4, wherein, The adjusting seat is provided with an arc-shaped hole for adjusting the angle of the suction cup in the pitch direction.

6. A method of assembling a profiled curved component in a helicopter, characterised in that, The controller applied to the assembly robot, wherein the assembly robot is any one of the assembly robots in claims 1-5, comprises: According to the edge features corresponding to the target accessory and the target skeleton to be assembled respectively, a planned scanning path for scanning the target accessory and the target skeleton is determined respectively; wherein the target accessory comprises a special-shaped curved accessory; According to the planned scanning path, the target accessory and the target skeleton are scanned, and based on the obtained scanning results, 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 are compared, and based on the comparison result, a contact stress distribution diagram of the target accessory and the target skeleton during assembly is predicted; According to the contact stress distribution diagram, the target accessory is assembled to the target skeleton using the assembly robot.

7. The method of assembling according to claim 6, wherein, The edge feature acquisition method comprises: A depth camera installed on the assembly robot is used to obtain photos corresponding to the target accessory and the target skeleton respectively; Based on the photos, a first initial model corresponding to the target accessory and a second initial model corresponding to the target skeleton are established; 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.

8. The method of claim 7, wherein, According to the edge features corresponding to the target accessory and the target skeleton to be assembled respectively, a planned scanning path for scanning the target accessory and the target skeleton is determined respectively, including: According to the edge features corresponding to the target accessory and the target skeleton to be assembled respectively, 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 are determined; Based on the position coordinates and the contour coordinates, the direction change and the position change of the 3D scanner used when scanning the target accessory and the target skeleton are determined; The direction change and the position change of the 3D scanner are determined as the planned scanning path for scanning the target accessory and the target skeleton.

9. The method of claim 6, wherein, Before comparing the first model and the second model, the method further includes: For the first model and the second model, 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 are determined, and the predicted contact stress corresponding to the defect positions is determined; Obtain the form and position error of each defect position, the form and position error including height error and shape error; According to the form and position error 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; The determination of 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 includes: Identify and mark each defect point and assembly hole in the first model and the second model; the defect point is the position of the abnormal protrusion and / or abnormal depression carried by the target accessory and the target skeleton when leaving the factory; For each defect position and assembly hole, the area feature, gray feature and gradient feature corresponding to the defect position and assembly hole are calculated as the defect feature corresponding to the defect position and assembly hole; Compare each defect point and assembly hole in the first model and the second model, and based on the comparison result and the defect feature corresponding to each defect point and assembly hole, obtain the form and position error corresponding to each defect point and assembly hole; The defect point and / or assembly hole whose form and position error meets the preset rule of generating contact stress is determined as the defect position.

10. The method of claim 9, wherein, According to the form and position error 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: For the first model, according to the form and position error 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 on the first model relative to the simulated contact point, a mapping equation between the form and position error and the contact stress is established; Comparing the first model and the second model, predicting the contact stress distribution diagram when the target accessory and the target skeleton are assembled based on the comparison result, including: According to an assembling direction of the target accessory to the target framework, the edges of the first model and the second model are compared and matched to obtain a corresponding chromatogram when the first model and the second model are fitted, and the chromatogram is used to represent the shape and position error of each point on the edges of the first model and the second model; Based on the chromatogram and the mapping equation, the fitting of the first model and the second model is digitally simulated to predict the contact stress distribution diagram when the target accessory and the target framework are assembled.

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