An automated skin placement method

Abstract

The present application relates to a kind of skin automated placement method, belong to skin automated assembly technical field, solve the technical problem of low precision in prior art skin placement.The method of the present application includes: teaching to robot to execute the task of assembling skin to framework;Framework is set in target position, and the skin to be assembled is adsorbed by robot end, and the robot is changed according to the teaching and moves the skin to the preset position along the teaching path;The skin and the framework are photographed and identified respectively by visual recognition device;Visual matching calculation is carried out to obtain the actual transformation of robot end;The actual transformation is adjusted according to the actual transformation of the pose of the skin by the robot end, and then the skin is positioned and placed on the framework from the preset position.In the present application, the actual pose of skin and framework is identified respectively to adjust the teaching path, offset the adsorption error, and improve the precision of skin placement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of skin automatic assembly, and in particular to a skin automatic placement method. BACKGROUND

[0002] In the welding unit of complex components, the skin belongs to a special wing component, which poses a great challenge to the automatic welding process. The manufacturing process of the skin includes bending and sheet metal, which leads to poor consistency between the skins and makes it difficult to use traditional mechanical hands to grasp. Currently, the skin is mainly sucked by the suction cup, but the suction cup is a soft connection, and the repeated precision of the suction cup for sucking the skin is about 0.5mm, which leads to the fact that the existing skin placement method cannot meet the high precision requirement of the welding process, especially in the case where the assembly gap needs to be controlled within 0.01mm. SUMMARY

[0003] In view of the above analysis, the embodiments of the present application aim to provide a skin automatic placement method to solve the technical problem of low precision of skin placement in the prior art.

[0004] In one aspect, the embodiments of the present application provide a skin automatic placement method, which comprises:

[0005] Teaching the mechanical hand to perform the task of assembling the skin to the skeleton to obtain the skeleton teaching pose, the teaching path of the mechanical hand, and the teaching transformation of the teaching path of each path point of the skin and the mechanical hand end;

[0006] Setting the skeleton at the target position, adsorbing the skin to be assembled by the mechanical hand end, and moving the skin to the preset position along the teaching path according to the teaching transformation of the mechanical hand end;

[0007] Taking pictures of the skin and the skeleton respectively by a visual recognition device to obtain the actual pose of the skin and the actual pose of the skeleton at the preset position;

[0008] Performing visual matching calculation according to the skeleton teaching pose, the actual pose of the skeleton, and the skin teaching pose, the actual pose of the skin at the preset position, and the teaching transformation of the mechanical hand end to obtain the actual transformation of the mechanical hand end;

[0009] The mechanical hand end adjusts the pose of the skin according to the actual transformation, and then positions and places the skin from the preset position to the skeleton.

[0010] Based on the further improvement of the above method, the visual matching calculation is performed according to the following formula to obtain the actual transformation of the mechanical hand end:

[0011]

[0012] In the formula, T 实际 is the actual transformation of the robot end, T 示教 is the teaching transformation of the robot at the preset position, T2 is the pose relative transformation of the skeleton, P 2实际 is the actual pose of the skeleton, P 2示教 is the teaching pose of the skeleton, T1 is the pose relative transformation of the skin, P 1实际 is the actual pose of the skin at the preset position, P 1示教 is the teaching pose of the skin at the preset position.

[0013] Based on the further improvement of the above method, the preset position is located directly above the target position, and the distance between the preset position and the target position is 20-50 mm.

[0014] Based on the further improvement of the above method, the robot end adjusts the pose of the skin according to the actual transformation, and then positions and places the skin from the preset position to the skeleton, comprising:

[0015] A plurality of guide devices are arranged along the edge of the skeleton at the target position;

[0016] After the robot end adjusts the pose of the skin according to the actual transformation, the skin is positioned and placed from the preset position to the skeleton under the limitation of the guide device.

[0017] Based on the further improvement of the above method, the guide device comprises a base and a guide column, wherein the guide column is elastically connected to the base, and the outer wall of the guide column is used to contact the skin.

[0018] Based on the further improvement of the above method, the robot end adjusts the pose of the skin according to the actual transformation, and then positions and places the skin from the preset position to the skeleton, further comprising:

[0019] When the robot moves the skin to the preset position, the force condition of the robot end is detected;

[0020] According to the force condition, the robot is flexibly controlled until the robot positions and places the skin to the skeleton.

[0021] Based on the further improvement of the above method, the robot is flexibly controlled according to the force condition, comprising:

[0022] The external force on the robot end is converted into a speed adjustment amount and / or a position adjustment amount;

[0023] Adjust the speed of the robot end according to the speed adjustment amount, and / or adjust the moving distance of the robot end according to the position adjustment amount.

[0024] Further improvement based on the above method, the force of the robot is detected by force control sensor, the force control sensor is arranged on the robot.

[0025] Further improvement based on the above method, the end of the robot adsorbs the skin to be assembled, comprising the following steps:

[0026] Obtain the coordinates of the grasping point of the skin to be assembled;

[0027] The robot end adsorbs the skin to be assembled according to the grasping point coordinates, and moves the skin to the preset position.

[0028] Further improvement based on the above method, the coordinates of the grasping point of the skin to be assembled, comprising:

[0029] Assemble the skin template to the skeleton template;

[0030] Identify the coordinates of the fitting points between the skin template and the skeleton template by a visual recognition device;

[0031] Select at least three coordinates of the fitting points as grasping point coordinates.

[0032] Compared with the prior art, the present application can achieve at least one of the following beneficial effects:

[0033] 1、In the present application, after the robot end sucks the skin to be assembled and moves it to the preset position, the actual poses of the skin and the skeleton are identified by a visual recognition device for visual matching, so as to adjust the teaching transformation of the robot end, thereby correcting the pose of the skin, offsetting the adsorption error caused by soft connection such as adsorption connection, obtaining accurate placement pose, and improving the precision of skin placement.

[0034] 2、In the present application, by setting a guide device at the target position, the robot can accurately place the skin on the skeleton, reducing the positioning deviation caused by the adsorption error of the suction cup.

[0035] 3、In the present application, under the guidance of the guide device, the robot end is flexibly controlled according to the force condition, so as to ensure that the robot can operate with appropriate force and speed, avoid damaging the skin, and realize efficient, safe and accurate operation of the robot.

[0036] The technical solutions in the present application can be combined with each other to realize more preferred combination solutions. Other features and advantages of the present application will be described in the following description, and some advantages will become apparent from the description, or will be learned by practice of the present application. The objects and other advantages of the present application can be realized and obtained by the content particularly indicated in the description and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0037] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated in and constitute a part of this application. The drawings illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application.

[0038] Figure 1 A flow chart of a skin automatic placement method according to an embodiment of the present application.

[0039] Figure 2 A schematic diagram of a skin automatic placement process according to an embodiment of the present application.

[0040] Figure 3 A structural schematic diagram of a guide device according to an embodiment of the present application.

[0041] Reference Signs:

[0042] 1, manipulator; 2, guide device; 3, skin; 4, framework;

[0043] 21, base; 22, guide column; 221, straight section; 222, inclined section. DETAILED DESCRIPTION

[0044] The preferred embodiments of the present application will be described in detail below with reference to the drawings, wherein the drawings constitute a part of this application and serve to explain the principles of the embodiments of the present application, but are not intended to limit the scope of the present application.

[0045] One specific embodiment of the present application discloses a skin automatic placement method, as shown in Figure 1 and Figure 2 The method comprises the following steps.

[0046] Step 00, teaching the manipulator 1 to perform the task of assembling the skin 3 to the framework 4, so as to obtain the framework teaching pose, the teaching path of the manipulator 1, and the skin teaching pose of each path point on the teaching path and the teaching transformation of the end of the manipulator 1;

[0047] Step 10, setting the framework 4 at a target position, absorbing the skin 3 to be assembled by the end of the manipulator 1, and moving the skin 3 to the preset position along the teaching path according to the teaching transformation by the end of the manipulator 1;

[0048] Step 20, the skin 3 and the skeleton 4 are respectively identified by the visual recognition device, so as to obtain the actual pose of the skin and the actual pose of the skeleton at the preset position;

[0049] Step 30, according to the skeleton teaching pose, the actual pose of the skeleton, and the teaching transformation of the end of the manipulator 1, the actual transformation of the end of the manipulator 1 is obtained by visual matching calculation.

[0050] Step 40, the end of the manipulator 1 adjusts the pose of the skin 3 according to the actual transformation, and then places the skin 3 from the preset position to the skeleton 4.

[0051] In implementation, the end of the manipulator 1 is provided with an adsorption device, such as a plurality of suction cups, for sucking the skin 3.

[0052] Compared with the prior art, in the embodiment of the application, considering that the adsorption connection is a soft connection, the end of the manipulator 1 will produce adsorption error after adsorbing the skin 3, which will cause the attitude of the skin 3 to deviate, and this deviation cannot be accurately estimated, therefore, after the end of the manipulator 1 sucks the skin 3 to be assembled, the actual poses of the skin 3 and the skeleton 4 are respectively identified by the visual recognition device, which is used for visual matching to adjust the teaching transformation of the end of the manipulator 1, so as to realize the correction of the pose of the skin 3, can offset the adsorption error caused by the soft connection such as adsorption connection, and obtain accurate placement pose, which improves the precision of the placement of the skin 3.

[0053] Step 00, the manipulator 1 is taught to perform the task of assembling the skin 3 to the skeleton 4, so as to obtain the skeleton teaching pose, the teaching path of the manipulator 1, and the skin teaching pose and the teaching transformation of the end of the manipulator 1 at each path point on the teaching path.

[0054] Before performing the actual assembly task, the process of assembling the skin 3 to the skeleton 4 is simulated by teaching, which can ensure that the manipulator 1 accurately learns and replicates the assembly action. By teaching, the teaching path of the manipulator 1, the skin teaching pose and the teaching transformation of the end of the manipulator 1 at each path point on the teaching path, and the skeleton teaching pose can be obtained.

[0055] The skin teaching pose and the skeleton teaching pose refer to the positions and directions of the skin 3 and the skeleton 4 in the robot coordinates determined by the teaching method. Specifically, during teaching, the operator sets the skin teaching pose and the skeleton teaching pose according to the assembly environment and task requirements of the skin 3.

[0056] The teaching path refers to the moving track of the manipulator 1 when performing the assembly task, and the teaching transformation refers to the specific position and direction of the end of the manipulator 1 on the moving track.

[0057] It should be noted that the front and back of the framework 4 are respectively provided with a front skin and a back skin. That is, the skin 3 includes two types of skins, i.e., a front skin and a back skin. The two different skins 3 need to be respectively taught to the robot.

[0058] Step 10: The framework 4 is arranged at a target position, the skin 3 to be assembled is adsorbed by the end of the manipulator 1, and the manipulator 1 moves the skin 3 to the preset position along the teaching path according to the teaching.

[0059] In implementation, the manipulator 1 first moves to a preset initial position, and then moves from the initial position to the storage position of the skin 3, adsorbs a skin 3 to be assembled at the end, moves to the preset position according to the teaching path after adsorbing the skin 3, and then returns to the initial position after visual matching and assembling the skin 3 to the framework 4, so as to prepare for the assembly task of the next skin 3.

[0060] Specifically, the preset position is directly above the target position, and the distance between the preset position and the target position is 20-50 mm.

[0061] In the embodiment of the application, the preset position is close to the framework 4. In other words, in the embodiment of the application, the manipulator 1 first moves the skin 3 to a position close to the framework 4 to adjust the posture of the skin 3, which not only eliminates the adsorption error, but also reduces the cumulative error generated in the movement process, so as to more accurately control the positioning and installation of the skin 3. Specifically, the end of the manipulator 1 adsorbs the skin 3 to be assembled, including the following steps:

[0062] Obtaining the coordinates of the gripping point of the skin 3 to be assembled;

[0063] The end of the manipulator 1 adsorbs the skin 3 to be assembled according to the gripping point coordinates, and moves the skin 3 to the preset position.

[0064] In implementation, the suction cup at the end of the manipulator 1 is adsorbed on the gripping point on the skin 3 to control the posture of the skin 3.

[0065] Specifically, the coordinates of the gripping point of the skin 3 to be assembled include:

[0066] Assembling a skin template to a framework template;

[0067] Identifying the coordinates of the fitting points between the skin template and the framework template by a visual recognition device;

[0068] Selecting at least three coordinates of the fitting points as the gripping point coordinates.

[0069] In this embodiment, the fitting points between the skin 3 and the framework 4 are selected as the grabbing points, which is beneficial to the robot 1 to accurately place the skin 3 on the framework 4, so that the two are fitted.

[0070] It should be noted that, similarly, the skin template includes a front skin template and a reverse skin template, so the above method needs to be used to obtain the grabbing point coordinates of the front skin 3 and the grabbing point coordinates of the reverse skin 3 respectively. In implementation, the corresponding grabbing point coordinates are called according to the category of the skin 3 to be assembled.

[0071] Step 20, the skin 3 and the framework 4 are respectively photographed and recognized by the visual recognition device, so as to obtain the actual pose of the skin at the preset position and the actual pose of the framework.

[0072] Specifically, the visual recognition device is a camera, which is used to capture images and analyze them.

[0073] The visual recognition device analyzes the image of the skin 3 to determine the actual pose of the skin 3, i.e. the position and direction of the skin 3 in space. Similarly, the visual recognition device analyzes the image of the framework 4 to determine the actual pose of the framework 4, i.e. the position and direction of the framework 4 in space.

[0074] The pose of the workpiece refers to the three-dimensional space state of the workpiece in the robot coordinate system, including the position and direction of the workpiece, wherein the position is the coordinates of the center point or the preselected reference point of the workpiece in space, and the direction is the rotation state of the workpiece relative to the robot coordinate, which can be described by Euler angles (pitch angle, yaw angle, roll angle).

[0075] Step 30, according to the actual pose of the skin, the actual pose of the framework and the teaching transformation of the end of the robot 1 at the preset position, the visual matching calculation is carried out to obtain the actual transformation of the skin 3 assembly.

[0076] Specifically, the visual matching calculation is carried out according to the following formula to obtain the actual transformation of the end of the robot 1:

[0077]

[0078]

[0079] In the formula, T 实际 is the actual transformation of the end of the robot 1, T 示教 is the teaching transformation of the end of the robot 1 at the preset position, T2 is the pose relative transformation of the framework 4, P 2实际 is the actual pose of the framework, P 2示教 is the teaching pose of the framework, T1 is the pose relative transformation of the skin 3, P 1实际 is the actual pose of the skin at the preset position, P 1示教Teaching the pose of the skin at the preset position.

[0080] It should be noted that in the assembly task, what is concerned is how to align a specific connecting point of a component to a corresponding connecting point of another component, therefore, in the embodiment of the present application, the pose of the skin 3 refers to the position and direction of the fitting point of the skin 3 on the skeleton 4, and the pose of the skeleton 4 refers to the position and direction of the fitting point of the skin 3 on the skeleton 4.

[0081] Before the robot teaching, the teaching pose of the skin 3 and the teaching pose of the skeleton 4 are respectively set according to the assembly environment and task requirements of the skin 3.

[0082] In step 40, the end of the mechanical hand 1 adjusts the pose of the skin 3 according to the actual transformation, and then positions and places the skin 3 on the skeleton 4, which includes:

[0083] A plurality of guiding devices 2 are arranged along the edge of the skeleton 4 at the target position; after the end of the mechanical hand 1 adjusts the pose of the skin 3 according to the actual transformation, the skin 3 is positioned and placed on the skeleton 4 from the preset position under the limitation of the guiding devices 2.

[0084] In the embodiment of the present application, as shown in Figure 2 By arranging the guiding devices 2 at the target position, the mechanical hand 1 can be assisted to accurately place the skin 3 on the skeleton 4, and the positioning deviation caused by the adsorption error of the suction cup can be reduced.

[0085] As shown in Figure 3 The guiding device 2 includes a base 21 and a guiding column 22, wherein the guiding column 22 is elastically connected to the base 21, and the outer wall of the guiding column 22 is used to contact the skin 3.

[0086] The outer wall of the guiding column 22 is an arc surface, which can ensure that the guiding column 22 and the skin 3 are in line contact instead of surface contact, and the guiding column 22 is elastically connected to the base 21, which can balance the external force on the skin 3, so that the skin 3 can be prevented from being damaged.

[0087] The guiding column 22 includes a straight segment 221 and an inclined segment 222 connected in sequence, and the inclined segment 222 is located above the guiding column 22. The inclined segment 222 located at the upper part facilitates the mechanical hand 1 to place the skin 3 on the skeleton 4, and the straight segment 221 located at the lower part can limit the skin 3.

[0088] In step 40, the end of the mechanical hand 1 adjusts the pose of the skin 3 according to the actual transformation, and then positions and places the skin 3 on the skeleton 4 from the preset position, which further includes:

[0089] When the mechanical arm 1 moves the skin 3 to the preset position, the force condition of the end of the mechanical arm 1 is detected;

[0090] The flexible control is performed on the mechanical arm 1 according to the force condition until the mechanical arm 1 positions and places the skin 3 on the framework 4.

[0091] In the embodiment of the application, the flexible control is performed on the mechanical arm 1 according to the force condition of the end of the mechanical arm 1 while the guiding device 2 guides, so that the robot can be operated with appropriate force and speed, and damage to the skin 3 is avoided, and the mechanical arm 1 realizes efficient, safe and accurate operation.

[0092] Specifically, when the mechanical arm 1 approaches the target position, the guiding device 2 contacts the skin 3 and applies an external force to the skin 3 and conducts the external force to the mechanical arm 1, so that the flexible control is performed on the mechanical arm 1 according to the force condition of the end of the mechanical arm 1, and even under the assembly condition with small tolerance, the skin 3 can be assembled and positioned accurately in a flexible manner when the skin 3 contacts the guiding device 2 with a certain depth.

[0093] Specifically, the force condition of the mechanical arm 1 is detected by a force control sensor, and the force control sensor is arranged on the mechanical arm 1. Further, the force control sensor is a six-dimensional force control sensor.

[0094] Specifically, the flexible control is performed on the mechanical arm 1 according to the force condition, including:

[0095] The external force on the end of the mechanical arm 1 is converted into a speed adjustment amount and / or a position adjustment amount;

[0096] The speed of the end of the mechanical arm 1 is adjusted according to the speed adjustment amount, and / or the moving distance of the end of the mechanical arm 1 is adjusted according to the position adjustment amount.

[0097] The flexible control includes stiffness control, damping control and impedance control. The feedback force signal is converted into a position adjustment amount for stiffness control, the feedback force signal is converted into a speed adjustment amount for damping control, and the feedback force signal is converted into a speed adjustment amount and a position adjustment amount for impedance control. In the embodiment of the application, any one of the flexible controls can be selected according to actual needs.

[0098] Exemplarily, the formula for converting the external force on the end of the mechanical arm 1 into a speed adjustment amount and / or a position adjustment amount is as follows:

[0099] Δv=k d ·F;

[0100] Δx=k p ·F;

[0101] wherein Δv is a velocity adjustment amount, F is an external force at the end of the robot 1; k d is a damping coefficient for determining the strength of the velocity adjustment; Δx is a position adjustment amount, k p is a proportional stiffness coefficient for determining the strength of the position adjustment.

[0102] Those skilled in the art can understand that all or part of the processes of the above-mentioned embodiments can be completed by a computer program instructing relevant hardware, and the program can be stored in a computer readable storage medium. The computer readable storage medium includes a magnetic disk, an optical disk, a read-only memory, a random access memory, etc.

[0103] The above description is merely preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any changes or replacements within the technical scope disclosed by the present application can be easily thought of by those skilled in the art, and should be covered within the protection scope of the present application.

Claims

1. An automated skin placement method, characterized in that, The method includes: The robot arm is taught to perform the task of assembling the skin onto the skeleton, thereby obtaining the skeleton teaching pose, the robot arm teaching path, the skin teaching pose at each path point on the teaching path, and the teaching transformation of the robot arm end effector. The skeleton is set at the target position, the skin to be assembled is adsorbed by the end effector of the robotic arm, and the end effector of the robotic arm moves the skin to the preset position along the teaching path according to the teaching transformation; The skin and the skeleton are photographed and identified by a visual recognition device to obtain the actual pose of the skin and the actual pose of the skeleton at a preset position. Visual matching calculations are performed based on the skeleton teaching pose, the actual pose of the skeleton, the skin teaching pose at the preset position, the actual pose of the skin, and the teaching transformation of the robot end effector to obtain the actual transformation of the robot end effector. The robotic arm end effector adjusts the pose of the skin according to the actual transformation, and then positions the skin from the preset position onto the skeleton; The actual transformation of the robotic arm's end effector is obtained by visual matching calculation based on the following formula: ； ； ； In the formula, This refers to the actual transformation of the robotic arm's end effector. This is a teaching transformation of the robot's end effector at a preset position. For the relative pose transformation of the skeleton This represents the actual pose of the skeleton. The teaching pose is for the skeleton. For the relative pose transformation of the skin, This represents the actual pose of the skin at the preset position. The teaching pose for the skin at the preset position.

2. The method according to claim 1, characterized in that, The preset position is located directly above the target position, and the distance between the preset position and the target position is 20mm to 50mm.

3. The method according to claim 1, characterized in that, The robotic arm end effector adjusts the pose of the skin according to the actual transformation, and then positions the skin from the preset position onto the skeleton, including: Multiple guide devices are provided along the edge of the skeleton at the target location; After the robotic arm end effector adjusts the pose of the skin according to the actual transformation, it positions and places the skin onto the skeleton from the preset position under the guidance of the guiding device.

4. The method according to claim 3, characterized in that, The guiding device includes a base and a guide post, wherein the guide post is elastically connected to the base, and the outer wall of the guide post is used to contact the skin.

5. The method according to claim 3, characterized in that, The robotic arm end effector adjusts the pose of the skin according to the actual transformation, and then positions the skin from the preset position onto the skeleton, further comprising: When the robotic arm moves the skin to the preset position, it begins to detect the force applied to the end of the robotic arm. The robotic arm is flexibly controlled according to the force conditions until it positions and places the skin onto the skeleton.

6. The method according to claim 5, characterized in that, The robotic arm is flexibly controlled based on the force conditions, including: The external force at the end of the robotic arm is converted into a speed adjustment amount and / or a position adjustment amount; The speed of the robotic arm end effector is adjusted according to the speed adjustment amount, and / or the movement distance of the robotic arm end effector is adjusted according to the position adjustment amount.

7. The method according to claim 5, characterized in that, The force applied to the robotic arm is detected by a force control sensor, which is installed on the robotic arm.

8. The method according to claim 1, characterized in that, The process involves using the end effector of a robotic arm to pick up the skin to be assembled, including the following steps: Obtain the coordinates of the gripping points of the skin to be assembled; The robotic arm end effector picks up the skin to be assembled according to the coordinates of the gripping point and moves the skin to the preset position.

9. The method according to claim 8, characterized in that, The process of obtaining the coordinates of the gripping points of the skin to be assembled includes: Assemble the skin template onto the skeleton template; The coordinates of the fitting point between the skin template and the skeleton template are identified using a visual recognition device; Select the coordinates of at least three of the aforementioned contact points as the coordinates of the grab point.

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