A hand-eye calibration method for an automated servo motor assembly system

Abstract

This invention relates to a hand-eye calibration method for an automated servo motor assembly system, belonging to the field of non-standard automated assembly technology. It solves the problem in existing technologies where the end effector of a robotic arm needs to touch the same point at different positions to obtain positional relationships, resulting in uncontrollable calibration errors. This invention discloses a hand-eye calibration method for an automated servo motor assembly system, utilizing a servo motor assembly system; including the following steps: installing a tip device; establishing a first tool coordinate system; establishing a tip coordinate system; establishing a second tool coordinate system; and ending the hand-eye calibration. The calibration method of this invention establishes the transformation relationship between the camera image coordinate system and the first tool coordinate system by controlling the second robotic arm to move nine positions in the same plane. Afterwards, only six images of the feature point need to be taken by the second camera, and the second robotic arm needs to be moved to the midpoint to perform hand-eye calibration of the assembly system, ensuring that the calibration error remains controllable.

Description

Technical Field

[0001] This invention belongs to the field of non-standard automated assembly technology, and in particular relates to a hand-eye calibration method for an automatic servo motor assembly system. Background Technology

[0002] Due to its advantages such as high system integration, good adaptability, and high assembly precision, vision-guided assembly technology has been extensively studied both domestically and internationally, and has been widely applied in the fields of micro-assembly and macro-assembly.

[0003] Visual guidance refers to using industrial cameras to capture images of objects instead of human eyes, processing these images through relevant algorithms to obtain useful information, and ultimately using this information to control the robot's operations. In a visually guided robot system, hand-eye calibration establishes the transformation relationship between the camera coordinate system and the robot's basic coordinate system. Hand-eye calibration determines the transformation relationship between the robot's coordinate system and the camera coordinate system; therefore, the accuracy of this transformation relationship determines whether the robot's end effector can accurately grasp objects.

[0004] Existing hand-eye calibration methods mainly include the multiple position point method and the TCP calibration method. The multiple position point method requires multiple operations and recording the three-dimensional positions of different points, which is time-consuming and labor-intensive. The TCP calibration method requires the end-effector of the robotic arm to touch the same point at different positions to obtain the positional relationship. Its calibration result depends on whether the end-effector of the robotic arm is aligned with the target point. The calibration error is greatly affected by the operator's working state, thus affecting the smooth progress of the operation.

[0005] Therefore, it is necessary to study a hand-eye calibration method for an automated servo assembly system to address the shortcomings of existing technologies and solve the aforementioned problems. Summary of the Invention

[0006] Based on the above analysis, the present invention aims to provide an automatic servo motor assembly system and its hand-eye calibration method, which solves the problem that the existing technology requires the end point of the robotic arm to touch the same point at different positions to obtain the positional relationship, and the calibration result depends on whether the end point of the robotic arm is aligned with the target point, resulting in uncontrollable calibration error.

[0007] The objective of this invention is mainly achieved through the following technical solutions: A hand-eye calibration method for an automatic servo motor assembly system, utilizing an automatic servo motor assembly system; The hand-eye calibration method includes the following steps: Install a pointed device; Establish the first tool coordinate system; Establish a cusp coordinate system; Establish a second tool coordinate system; Complete hand-eye calibration.

[0008] Furthermore, the installation of the tip device includes: installing and fixing the tip device on the screw suction unit, wherein the tip device is coaxially arranged with the screw suction unit.

[0009] Furthermore, establishing the first tool coordinate system includes setting feature points on the calibration plate surface.

[0010] Furthermore, the feature point is a cross-shaped marker.

[0011] Furthermore, the first tool coordinate system is the coordinate system of the second end effector.

[0012] Furthermore, establishing the cusp coordinate system includes: the X'-Y' plane of the cusp coordinate system is parallel to the XY plane of the first tool coordinate system, and the X' axis, Y' axis, and Z' axis are aligned with the X, Y, and Z axes of the first tool coordinate system.

[0013] Furthermore, the absolute distance between the origin of the cusp coordinate system and the origin of the first tool coordinate system in the Z-axis direction is the distance from the cusp of the cusp device to the center of the end face of the screw suction device.

[0014] Furthermore, establishing a cusp coordinate system also includes: the Z' axis of the cusp coordinate system is coaxial with the Z axis of the first tool coordinate system.

[0015] Furthermore, establishing the second tool coordinate system includes: transforming the points in the first tool coordinate system to obtain the second tool coordinate system.

[0016] Furthermore, completing the hand-eye calibration includes: the assembly system guiding the second robotic arm to perform positioning according to the second tool coordinate system.

[0017] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: (1) The calibration method of the present invention can establish the transformation relationship between the camera image coordinate system and the first tool coordinate system by controlling the second robotic arm to move nine positions on the same plane; then, it is only necessary to control the second camera to take pictures of the feature points and control the second robotic arm to move to the middle point to perform hand-eye calibration of the assembly system, so that the calibration error can always be controlled. (2) The secondary positioning mechanism of the present invention can realize the secondary positioning of the servo in the three-dimensional directions of the horizontal, vertical and vertical directions. It can determine the unique three-dimensional position of the servo on the secondary positioning mechanism. The controller only needs to control the gripping mechanism to perform secondary gripping of the servo at this three-dimensional position to ensure the precise clamping of the servo, thereby ensuring that the servo is accurately placed on the assembly position of the aircraft. (3) The translation mechanism of the present invention translates the gripping mechanism longitudinally, thereby expanding the range of motion of the gripping mechanism; (4) When placing the servo motor, the first end effector component of the present invention needs to press the servo motor into the installation position on the aircraft. The pressure plate can prevent the servo motor from disengaging from the first gripper in the direction of the actuator when it is pressed into the installation position on the aircraft, thus ensuring that the servo motor is installed in place. (5) Both the first half-clamp and the second half-clamp of the present invention are provided with anti-disengagement hooks at one end, and the side wall of the servo motor is provided with mounting holes. When the first clamp grips the servo motor, the anti-disengagement hook can be inserted into the mounting holes. If the servo motor is disengaged from the first clamp during the gripping mechanism gripping and moving the servo motor, the anti-disengagement hook can prevent the servo motor from falling and ensure the safety of equipment and personnel. (6) The hook of the present invention can hook the washer and prevent the washer from falling off the screw; (7) The screw adsorber of the present invention is a cylindrical body. A negative pressure can be formed inside the screw adsorber, thereby adsorbing the screw and ensuring that the screw will not fall out of the screw adsorber.

[0018] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the specification or be learned by practicing the invention. The objectives and other advantages of this invention can be realized and obtained from the content specifically pointed out in the text and drawings. Attached Figure Description

[0019] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0020] Figure 1 This is a schematic flowchart of the calibration method of the present invention; Figure 2 This is a schematic diagram of the overall structure of the assembly system of the present invention; Figure 3 This is a schematic diagram of the overall structure of the gripping mechanism; Figure 4 This is a schematic diagram of the overall structure of the first end-effector component; Figure 5 This is a schematic diagram of the servo motor's assembly status; Figure 6 A schematic diagram of the overall structure of the secondary positioning mechanism; Figure 7 This is a schematic diagram of the internal structure of the secondary positioning mechanism; Figure 8 This is a schematic diagram of the overall structure of the centralization component; Figure 9 This is a schematic diagram of the overall structure of the locking mechanism; Figure 10 This is a schematic diagram of the overall structure of the second-end execution component; Figure 11 This is a schematic diagram of the servo motor's assembly status; Figure 12 A schematic diagram of the overall structure of the screw feeding assembly; Figure 13 This is a schematic diagram of the cusp device.

[0021] Figure label: 1-Gantry frame; 2-Gripping mechanism; 3-Secondary positioning mechanism; 4-Locking mechanism; 5-Screw feeding assembly; 6-Translation mechanism; 7-Operating table; 8-Servo motor; 9-Screw; 10-Point device; 11-Longitudinal beam; 12-Crossbeam; 13-Column; 21-First robotic arm; 22-First force control assembly; 23-First camera; 24-Actuator; 25-First half-clamp; 26-Second half-clamp; 27-Friction pad; 28-Pressure plate; 29-Anti-disengagement hook; 31-Support base plate; 32-First positioning block; 33-Second positioning block; 34-Motor; 35- Motor base; 36-Lever; 37-Linking rod; 38-Hinge shaft; 41-Second robotic arm; 42-Second force control assembly; 43-Second camera; 44-Mounting plate; 45-Grip assembly; 46-Screw suction device; 47-Slide rail; 48-Electric screwdriver assembly; 49-Push-pull cylinder; 51-Positioning plate; 52-Screw slot; 53-Handle; 101-Conical section; 102-Cylindrical section; 311-First slot; 312-Second slot; 331-Guide block; 332-Positioning shaft; 451-Second gripper; 452-Hook; 481-Screwdriver bit; 482-Electric screwdriver. Detailed Implementation

[0022] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0023] Example 1 A specific embodiment of the present invention, such as Figure 1 As shown, a hand-eye calibration method (hereinafter referred to as the calibration method) for an automatic servo assembly system is disclosed. This calibration method can perform hand-eye calibration on the assembly system of Embodiment 2. The assembly system accurately places the servo 8 on the assembly position of the aircraft and automatically tightens the screws to complete the assembly.

[0024] The calibration method of the present invention includes the following steps: Step 1: Install the cusp device 10 Install the tip device 10 on the screw suction device 46 and turn on vacuum suction. The axis of the tip device 10 is coaxial with the screw suction device 46 and the screwdriver bit 481.

[0025] Step 2: Establish the first tool coordinate system Feature points are set on the surface of the calibration plate; Preferably, the feature point is a cross mark, which is fixed in position on the surface of the calibration plate.

[0026] A first tool coordinate system is established using the TCP calibration method of the robotic arm. The origin of the first tool coordinate system coincides with the feature point. The first tool coordinate system is the coordinate system of the second end effector.

[0027] Step 3: Establish the cusp coordinate system Establish a cusp coordinate system. The X'-Y' plane of this coordinate system is parallel to the XY plane of the first tool coordinate system. The X', Y', and Z' axes are aligned with the X, Y, and Z axes of the first tool coordinate system. The absolute distance between the origin of the cusp coordinate system and the origin of the first tool coordinate system in the Z-axis direction is the distance from the cusp of the cusp device to the center of the end face of the screw suction device 46.

[0028] The Z' axis of the cusp coordinate system is coaxial with the Z axis of the first tool coordinate system. That is, the cusp coordinate system is translated from the first tool coordinate system along the Z axis direction, and the translation distance is the distance from the cusp of the cusp device to the center of the end face of the screw suction device 46.

[0029] Step 4: Establish conversion relationship A The second robotic arm 41 is controlled to move to nine positions in the first tool coordinate system Z=0 plane and collect the corresponding position information of the second end effector, and the transformation relationship A between the camera image coordinate system and the first tool coordinate system is established.

[0030] The transformation relation A is calculated using the following formula:

[0031] Where (x, y) are the coordinates of the nine points in the first tool coordinate system, (u, v) are the position information of each point, R is the rotation matrix, and M is the translation matrix.

[0032] Preferably, the coordinates of the nine positions are (0,0), (a,0), (-a,0), (0,-a), (a,-a), (-a,-a), (0,a), (a,a), (-a,a), where the value of a ranges from 5mm to 15mm, and the specific value is adjusted according to the size of the feature point and the field of view of the camera.

[0033] Preferably, based on the coordinate relationship between these nine positions in the first tool coordinate system and the camera image coordinate system, the average transformation relationship between the two coordinate systems is obtained, which is the transformation relationship A.

[0034] Step 5: Obtain the coordinates of the intermediate point, including the following sub-steps: Step 51: First acquisition of feature point location information The second robotic arm 41 is controlled to move d units along the Z+ direction in the first tool coordinate system, rotate α angles around the X, Y, and Z axes respectively, and the second camera 43 is controlled to take 3 pictures of the feature point, obtaining the three spatial position coordinates P, Q, and N of the feature point in the first tool coordinate system when the second camera 43 is in 3 different postures.

[0035] Preferably, the moving distance d is 5 to 15 mm and the rotation angle α is 5° to 15°, which can be adjusted according to the field of view requirements.

[0036] Step 52: Second acquisition of feature point location information The second robotic arm 41 is controlled to move d units along the Z-direction in the first tool coordinate system, rotate α angles around the X, Y, and Z axes respectively, and the second camera 43 is controlled to take 3 pictures of the feature point, obtaining the three spatial position coordinates P', Q', and N' of the feature point in the first tool coordinate system when the second camera 43 is in 3 different postures.

[0037] Step 53: Calculate the coordinates of the intermediate point Let p be the midpoint between P and P', q be the midpoint between Q and Q', and n be the midpoint between N and N'. Calculate the coordinates of p, q, and n in the first tool coordinate system.

[0038] Step 6: Record and transform the coordinates of the intermediate point, including the following sub-steps: Step 61: Record the coordinates of the intermediate point The controller controls the second robotic arm 41 to rotate by an angle α around the X, Y, and Z axes in the cusp coordinate system and then move to points p, q, and n. The coordinates of points p, q, and n in the first tool coordinate system are recorded.

[0039] The rotation angle of the second robotic arm 41 in the cusp coordinate system is consistent with the rotation angle of the second robotic arm 41 in the first tool coordinate system in step 5.

[0040] Step 62: Transform the coordinates of the intermediate point Calculate the coordinate transformation relationships B, C, and D between the intermediate points p, q, and n in the first tool coordinate system and the cusp coordinate system, respectively.

[0041] The transformation relation B is: , Where (x', y') refers to the coordinate information of point p in the first tool coordinate system, (u', y') refers to the coordinate information of p' in the second tool coordinate system, R' is the rotation matrix, and M' is the translation matrix; The transformation relation C is: , (x'', y'') represents the coordinate information of point q in the first tool coordinate system, (u'', y'') represents the coordinate information of q' in the second tool coordinate system, R'' is the rotation matrix, and M'' is the translation matrix; The transformation relation D is: , (x''', y''') represents the coordinate information of point n in the first tool coordinate system, (u''', y''') represents the coordinate information of n' in the second tool coordinate system, R''' is the rotation matrix, and M''' is the translation matrix.

[0042] Step 7: Establish the second tool coordinate system The second tool coordinate system is obtained by transforming the points in the first tool coordinate system using transformation relations B, C, and D.

[0043] Step 8: End hand-eye calibration After the hand-eye calibration is completed, the assembly system guides the second robotic arm 41 to perform positioning based on the second tool coordinate system.

[0044] Compared with the prior art, the calibration method of the present invention can establish the transformation relationship between the camera image coordinate system and the first tool coordinate system by controlling the second robotic arm 41 to move to nine positions in the plane; then, it is only necessary to control the second camera 43 to take pictures of the feature points and control the second robotic arm 41 to move to the midpoint to perform hand-eye calibration of the assembly system, so that the calibration error can always be controlled.

[0045] Example 2 A specific embodiment of the present invention, such as Figure 2 As shown, an automatic servo assembly system (hereinafter referred to as the assembly system) using Embodiment 1 is disclosed, including a gantry 1, a gripping mechanism 2, a secondary positioning mechanism 3, a locking mechanism 4, and a screw feeding assembly 5. The gripping mechanism 2, the secondary positioning mechanism 3, the locking mechanism 4, and the screw feeding assembly 5 are all connected to the gantry 1. The gripping mechanism 2, the secondary positioning mechanism 3, and the locking mechanism 4 are all connected to a controller. The controller controls the movement of the gripping mechanism 2, the secondary positioning mechanism 3, and the locking mechanism 4. The gripping mechanism 2 is used to grip and place the servo motor 8. The secondary positioning mechanism 3 is used to perform secondary positioning of the gripping of the servo motor 8 during the gripping and placement process of the gripping mechanism 2. The locking mechanism 4 is used to obtain screws from the screw feeding assembly 5 and lock the servo motor 8 to the aircraft with the screws to complete the assembly.

[0046] Preferably, the gantry 1 includes longitudinal beams 11, transverse beams 12 and columns 13. The longitudinal beams 11 and transverse beams 12 are connected to form a top frame. The top frame is set on the columns 13 and forms a portal structure. The portal structure includes a hollow section, in which an aircraft is placed for assembling the servo motor 8 onto the aircraft.

[0047] Preferably, the length of the longitudinal beam 11 is greater than the length of the transverse beam 12, the longitudinal beam 11 extends in the longitudinal direction, the transverse beam 12 extends in the transverse direction, and the column 13 extends in the vertical direction.

[0048] Preferably, the assembly system of the present invention further includes a translation mechanism 6, which is disposed on the top frame and connected to the controller. The gripping mechanism 2 is connected to the translation mechanism 6, and the controller can control the translation mechanism 6 to longitudinally translate the gripping mechanism 2, thereby expanding the range of motion of the gripping mechanism 2.

[0049] Preferably, the translation mechanism 6 includes a linear unit mounted on the top frame and connected to the controller, and the gripping mechanism 2 is connected to the linear unit. The controller can control the linear unit to longitudinally translate the gripping mechanism 2.

[0050] Preferably, the translation mechanism 6 further includes a truss, which is set on the top frame. The linear unit is connected to the top frame through the truss. The truss is a rigid frame to ensure support for the linear unit and the straightness of the linear unit.

[0051] Preferably, the assembly system of the present invention further includes an operating table 7 on which the servo motor 8 to be assembled is placed for gripping by the gripping mechanism 2. The gripping mechanism 2 is capable of gripping the servo motor 8 placed on the operating table 7 for the first time.

[0052] Preferably, such as Figure 3 and Figure 4 As shown, the gripping mechanism 2 includes a first robotic arm 21, a first force control component 22, a first camera 23, and a first end effector. One end of the first robotic arm 21 is connected to the translation mechanism 6, and the other end of the first robotic arm 21 is sequentially connected to the first force control component 22, the first camera 23, and the first end effector. The first robotic arm 21, the first force control component 22, and the first camera 23 are all connected to a controller. The first robotic arm 21 is used to realize the automatic movement of the first end effector. The first force control component 22 is used to flexibly control the movement of the first robotic arm 21. The first camera 23 is used to provide visual guidance and positioning for the first robotic arm 21. The first end effector is used to grip and place the servo motor 8 for assembly.

[0053] The first robotic arm 21, the first force control component 22, and the first camera 23 are all existing products, and the present invention does not impose any specific limitations.

[0054] Preferably, the first end effector assembly includes an actuator 24, a first half-clamp 25, and a second half-clamp 26. The actuator 24 is mounted on the first robotic arm 21 and connected to the controller. The first half-clamp 25 and the second half-clamp 26 are both connected to the actuator 24 and together form the first gripper. The actuator 24 can control the first half-clamp 25 and the second half-clamp 26 of the first gripper to move closer or further away from each other, thereby realizing the gripping and placement of the servo motor 8 by the first gripper.

[0055] Preferably, the first half-clamp 25 and the second half-clamp 26 are flat to fit against the side wall of the servo motor 8. When gripping the servo motor 8, the first half-clamp 25, the second half-clamp 26 and the side wall of the servo motor 8 are made to fit together to the maximum extent so as to securely grip the servo motor 8.

[0056] Preferably, friction plates 27 are provided on the first half-clamp 25 and the second half-clamp 26. The friction plates 27 are disposed on the inner wall of the first half-clamp 25 and the second half-clamp 26 that are in contact with the servo motor 8. The friction plates 27 are used to provide friction for the first half-clamp 25 and the second half-clamp 26 to ensure that the first jaw firmly clamps the servo motor 8.

[0057] Preferably, the friction plate 27 is a polyurethane rubber plate. The polyurethane rubber plate is elastic, which ensures that the first gripper firmly holds the servo motor 8 while preventing the first half-clamp 25 and the second half-clamp 26 from damaging the side wall of the servo motor 8.

[0058] Preferably, both the first half-clamp 25 and the second half-clamp 26 are provided with pressure plates 28. When the first end effector is placing the servo motor 8, it is necessary to press the servo motor 8 into the installation position on the aircraft. The pressure plates 28 can prevent the servo motor 8 from disengaging from the first clamp in the direction of the actuator 24 when it is pressed into the installation position on the aircraft, thus ensuring that the servo motor 8 is installed in place.

[0059] Preferably, such as Figure 5 As shown, one end of the first half-clamp 25 and the second half-clamp 26 are provided with anti-detachment hooks 29. The side wall of the servo motor 8 is provided with mounting holes. When the first gripper grabs the servo motor 8, the anti-detachment hooks 29 can be inserted into the mounting holes. If the servo motor 8 is disengaged from the first gripper during the gripping mechanism 2 gripping and moving the servo motor 8, the anti-detachment hooks 29 can prevent the servo motor 8 from falling, ensuring the safety of equipment and personnel.

[0060] The controller can perform video recognition of the servo motor 8 to be grasped based on the first camera 23 and control the first robotic arm 21 of the grasping mechanism 2 to align with the servo motor 8. Referring to the motion parameters of the first robotic arm 21 fed back by the first force control component 22, the controller can flexibly control the first end effector to grip the servo motor 8. However, since the servo motor 8 is placed on the operating table 7 manually, the placement direction and position of the servo motor 8 are not uniform. Due to the existence of video recognition errors of the first camera 23, the accuracy of the first end effector in gripping the servo motor 8 is insufficient. The consistency of the relative position between the servo motor 8 and the first end effector cannot be guaranteed each time, and secondary positioning of the servo motor 8 is required.

[0061] Preferably, such as Figure 6 As shown, the secondary positioning mechanism 3 includes a support base plate 31, a first positioning block 32, and a second positioning block 33. The support base plate 31 is mounted on the gantry frame 1. Specifically, the support base plate 31 is fixedly mounted on the column 13. The first positioning block 32 and the second positioning block 33 are both located on one side of the support base plate 31. The first positioning block 32 is fixedly mounted at one end of the support base plate 31, and the second positioning block 33 is located at the other end of the support base plate 31. The servo motor 8 can be placed on the support base plate 31 and remain stationary. The support base plate 31 provides positioning for the servo motor 8 in the lateral direction; the first positioning block 32 can support the servo motor 8 and provide positioning for the servo motor 8 in the vertical direction.

[0062] Preferably, there are two second positioning blocks 33. These second positioning blocks 33 can move towards or away from each other in the longitudinal direction. When the two second positioning blocks 33 move towards each other, one of them can push the servo motor 8 towards the other. Ultimately, both second positioning blocks 33 are connected to the servo motor 8, and the servo motor 8 is in a clamped and fixed state. The second positioning blocks 33 provide positioning for the servo motor 8 in the longitudinal direction. The secondary positioning mechanism 3 can perform secondary positioning of the servo motor 8 in the longitudinal, lateral, and vertical directions, ensuring the positioning and gripping of the servo motor 8 by the gripping mechanism 2.

[0063] Preferably, such as Figure 7 As shown, a first groove 311 is formed on the support base plate 31, and a guide block 331 is provided on the second positioning block 33. The guide block 331 is disposed in the first groove 311 and can slide in the first groove 311, so that the two second positioning blocks 33 can slide towards each other or away from each other on the support base plate 31 along the first groove 311.

[0064] Preferably, the secondary positioning mechanism 3 further includes a motor 34, a motor base 35, and a centering component. The motor base 35 is fixedly connected to the support base plate 31, the motor 34 is fixedly mounted on the motor base 35, the motor 34 is connected to the controller, and the controller controls the rotation of the motor 34. The centering component is connected to the motor shaft of the motor 34 and the second positioning block 33 respectively. When the motor 34 rotates, the two second positioning blocks 33 can slide towards each other or away from each other through the centering component.

[0065] Preferably, such as Figure 8 As shown, the centering assembly includes a lever 36 and connecting rods 37. The lever 36 is connected to the motor shaft, and the motor 34 can drive the lever 36 to rotate. There are two connecting rods 37, each connected to one of the two second positioning blocks 33. Both ends of the lever 36 are provided with hinge shafts 38, and one end of the connecting rod 37 is movably connected to the hinge shaft 38 and can rotate around the hinge shaft 38. Rotating the lever 36 can cause the two connecting rods 37 to move closer or further apart, thereby causing the two second positioning blocks 33 to move closer or further apart.

[0066] Preferably, the second positioning block 33 is provided with a positioning shaft 332, and the connecting rod 37 is movably connected to the positioning shaft 332. The support base plate 31 is also provided with a second groove 312, and the positioning shaft 332 can slide within the second groove 312. The connecting rod 37 can pull the second positioning block 33 to slide on the support base plate 31 via the positioning shaft 332.

[0067] Preferably, the hinge shaft 38 is parallel to the motor shaft, and the distance between the two hinge shafts 38 and the motor shaft is the same. Rotating the lever 36 can drive the two connecting rods 37 to move closer or further away from each other at equal distances, thereby driving the two second positioning blocks 33 to move closer or further away at equal distances.

[0068] Preferably, the support base plate 31 includes a vertical centerline, and two second positioning blocks 33 are symmetrically distributed about the vertical centerline; the motor shaft includes a motor axis that intersects the vertical centerline. Each time a servo motor 8 is placed, the two second positioning blocks 33 can clamp the servo motor 8, the distance from the two second positioning blocks 33 to the vertical centerline can be kept the same, and the position of each servo motor 8 in the longitudinal direction remains consistent.

[0069] Preferably, the support base plate 31 is inclined on the column 13, and the angle between the support base plate 31 and the column 13 is 20°-30°. The servo motor 8 can be stably placed on the support base plate 31 by gravity.

[0070] Preferably, the secondary positioning mechanism 3 is made of stainless steel to ensure sufficient structural strength.

[0071] In this way, after the servo motor 8 is first grasped from the control panel 7, it is placed on the support base plate 31 for secondary positioning. The support base plate 31 remains in a fixed position, providing servo motor 8 with lateral positioning. The first positioning block 32 remains in a fixed position, supporting servo motor 8 and providing servo motor 8 with vertical positioning. The centering component and the second positioning block 33 can adjust the position of servo motor 8 in the longitudinal direction, ensuring consistent positioning of servo motor 8 in the longitudinal direction. The secondary positioning mechanism 3 can achieve secondary positioning of servo motor 8 in the lateral, longitudinal, and vertical three-dimensional directions, and can determine the unique three-dimensional position of servo motor 8 on the secondary positioning mechanism 3. The controller only needs to control the grasping mechanism 2 to perform secondary grasping of servo motor 8 at this three-dimensional position to ensure precise clamping of servo motor 8, thereby ensuring that servo motor 8 is accurately placed in the assembly position of the aircraft.

[0072] Preferably, such as Figure 9 and Figure 10 As shown, the locking mechanism 4 includes a second robotic arm 41, a second force control component 42, a second camera 43, and a second end effector. One end of the second robotic arm 41 is connected to the gantry 1, and the other end of the second robotic arm 41 is sequentially connected to the second force control component 42, the second camera 43, and the second end effector. The second robotic arm 41, the second force control component 42, and the second camera 43 are all connected to a controller. The second robotic arm 41 is used to realize the automatic movement of the second end effector. The second force control component 42 is used to achieve flexible control of the movement of the second robotic arm 41. The second camera 43 is used to provide visual guidance and positioning for the second robotic arm 41. The second end effector is used to grasp and tighten the screw 9 for assembling the servo motor 8.

[0073] The second robotic arm 41, the second force control component 42, and the second camera 43 are all existing products, and the present invention does not impose any specific limitations.

[0074] Preferably, the second end effector includes a mounting plate 44, a gripping assembly 45, a screw suction device 46, a slide rail 47, an electric screwdriver assembly 48, and a pneumatic unit (not shown in the figure). The mounting plate 44 is mounted on the second robotic arm 41. The gripping assembly 45 and the screw suction device 46 are mounted at one end of the mounting plate 44. The slide rail 47 and the pneumatic unit are mounted on the mounting plate 44. The electric screwdriver assembly 48 is mounted on the slide rail 47. The gripping assembly 45, the screw suction device 46, and the electric screwdriver assembly 48 are all connected to the controller.

[0075] Preferably, the gripping assembly 45 includes a second gripper 451 and a hook 452, the hook 452 being disposed at one end of the second gripper 451. The second gripper 451 is a pneumatic gripper, used to grip the screw 9.

[0076] like Figure 12As shown, screw 9 includes a nut, which is cylindrical, and a spring washer 91 and a washer 92 are fitted on screw 9. The hook 452 is hook-shaped. After the second jaw 451 grips screw 9, the hook 452 can hook the washer 92 to prevent the washer 92 from falling off screw 9.

[0077] Preferably, such as Figure 10 and Figure 11 As shown, the screw suction device 46 is a cylindrical body. One end of the cylindrical body is connected to the electric screwdriver assembly 48, and the other end of the cylindrical body can be used to insert the nut of the screw 9. The controller can extract the air in the screw suction device 46 through the pneumatic unit to form a negative pressure, thereby adsorbing the screw 9 and ensuring that the screw 9 will not fall out of the screw suction device 46.

[0078] Preferably, the electric screwdriver assembly 48 includes a screwdriver bit 481 and an electric screwdriver 482. The screwdriver bit 481 is disposed at one end of the electric screwdriver 482, which is mounted on a slide rail 47. The screwdriver bit 481 can be inserted into one end of the cylindrical body of the screw absorber 46 and seal the cylindrical body to create a negative pressure environment inside the cylindrical body. The electric screwdriver 482 can slide along the slide rail 47 and drive the screwdriver bit 481 to push the screw 9 within the cylindrical body, ultimately causing the screw 9 to lock the servo motor 8 to the aircraft.

[0079] Preferably, there are multiple bits 481, each bit 481 having a different end shape and specification, such as slotted, Phillips, or different sizes of internal hexagonal, to accommodate different screws 9.

[0080] Preferably, the second end effector further includes a push-pull cylinder 49, which is mounted on the mounting plate 44 and connected to the electric screwdriver assembly 48. Specifically, the push-pull cylinder 49 is connected to the electric screwdriver 482. The push-pull cylinder 49 is a pneumatic push-pull cylinder, and the controller can charge and depress the push-pull cylinder 49 through a pneumatic unit, thereby controlling the extension or retraction of the push-pull cylinder 49 to push or pull back the electric screwdriver assembly 48.

[0081] Preferably, such as Figure 12 As shown, the screw feeding assembly 5 includes a positioning base plate (not shown) and a positioning disc 51, with the positioning base plate connected to the gantry frame 1. Specifically, the positioning base plate is mounted on the column 13. The positioning disc 51 is movably connected to the positioning base plate.

[0082] Preferably, the positioning base plate is provided with a positioning pin or positioning protrusion (not shown in the figure), and the positioning disk 51 is provided with a positioning hole (not shown in the figure). When the positioning disk 51 is connected to the positioning base plate, the positioning pin or positioning protrusion can be inserted into the positioning hole to fix the position of the positioning disk 51 and prevent the positioning disk 51 from being displaced from the positioning base plate.

[0083] Preferably, the positioning plate 51 includes a screw groove 52 and a screw hole. The screw hole is located in the screw groove 52. After the screw 9 is fitted with a spring washer 91 and a washer 92, it is inserted into the screw hole so that the locking mechanism 4 can clamp it. The hook 452 can be inserted into the screw groove 52 to clamp the screw 9, the spring washer 91, and the washer 92.

[0084] Preferably, the screw 9 also includes a small column section, which is a threaded section for screwing into the servo motor 8 and the aircraft. The depth of the screw hole is less than the length of the small column section minus the thickness of the flat washer and the free-state spring washer. After the screw 9 with spring washer 91 and washer 92 is placed into the screw hole, there is a gap between the nut and the spring washer 91, which can ensure that the screw 9 is placed vertically on the positioning plate 51 and is not affected by the inclination of the spring washer 91 itself, so that the screw suction device 46 can vertically suck the nut.

[0085] Preferably, the positioning disk 51 is provided with handles 53 on both sides for easy gripping.

[0086] Preferably, the controller includes an alarm light (not shown in the figure), which can be illuminated when the assembly system in this embodiment malfunctions.

[0087] Preferably, the linear unit includes a brake that can be opened or closed to allow or fix the movement of the first robotic arm 21.

[0088] Preferably, such as Figure 13 As shown, the assembly system of this embodiment also includes a tip device 10 and a calibration plate (not shown in the figure).

[0089] Preferably, the tip device 10 includes a conical segment 101 and a cylindrical segment 102; the cylindrical segment 102 can be attracted by the negative pressure of the screw suction device 46 and fix the tip device 10 on the screw suction device 46; the conical segment 101 includes a tip, which is the apex of the cone, and the tip can serve as the origin of the tip coordinate system in the hand-eye calibration of the assembly system in this embodiment.

[0090] Preferably, the calibration plate is mounted on the column 13. The calibration plate is a square glass plate with dimensions of 200mm × 200mm. The background color of the calibration plate is black, and the markings on the surface of the calibration plate are white dots or cross-shaped markings. The calibration plate is used to provide feature points for the hand-eye calibration of the assembly system in this embodiment.

[0091] In this embodiment, the secondary positioning mechanism 3 can achieve secondary positioning of the servo motor 8 in the horizontal, vertical and three-dimensional directions. It can determine the unique three-dimensional position of the servo motor 8 on the secondary positioning mechanism 3. The controller only needs to control the gripping mechanism 2 to perform secondary gripping of the servo motor 8 at this three-dimensional position to ensure the precise clamping of the servo motor 8, thereby ensuring that the servo motor 8 is accurately placed on the assembly position of the aircraft.

[0092] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A hand-eye calibration method for an automatic servo motor assembly system, characterized in that, An automated assembly system utilizing servo motors is disclosed, comprising a gantry frame, a gripping mechanism, a locking mechanism, and a screw feeding assembly. The gripping mechanism, locking mechanism, and screw feeding assembly are all connected to the gantry frame. The locking mechanism includes a second robotic arm, a second force control assembly, a second camera, a clamping assembly, and a screw suction device. The clamping assembly includes a second gripper and a hook, with the hook positioned at one end of the second gripper. The second gripper grips the screw, and the hook can hook onto the screw's washer to prevent the washer from detaching from the screw. A negative pressure is created within the screw suction device to attract and hold the screw. The screw feeding assembly includes a positioning base plate and a positioning disc. The positioning base plate is connected to the gantry frame, and the positioning disc is movably connected to the positioning base plate. The positioning base plate is provided with a positioning pin or a positioning protrusion, and the positioning disc is provided with a positioning hole. The positioning pin or positioning protrusion can be inserted into the positioning hole. The positioning disc includes a screw groove and a screw hole. The screw hole is located on the screw groove. After the screw is fitted with a spring washer and a washer, it is inserted into the screw hole. The hook can be inserted into the screw groove to clamp the screw, spring washer, and washer. The depth of the screw hole is less than the length of the small column section of the screw minus the thickness of the flat washer and the free-state spring washer. The hand-eye calibration method includes the following steps: Install a pointed device; Establish a first tool coordinate system; the first tool coordinate system is the coordinate system of the second end effector. Establish a cusp coordinate system; Establish transformation relationship A: Control the second robotic arm to move nine positions in the Z=0 plane of the first tool coordinate system and collect the corresponding position information of the second end effector to establish the transformation relationship A between the camera image coordinate system and the first tool coordinate system; the transformation relationship A is calculated by the following formula: Here, R represents the coordinates of nine points in the first tool coordinate system, M represents the position information captured by each point, R is the rotation matrix, and M is the translation matrix. Based on the coordinate relationship between these nine positions in the first tool coordinate system and the camera image coordinate system, the average transformation relationship between the two coordinate systems is calculated, which is the transformation relationship A. Obtaining the coordinates of the intermediate point involves the following steps: The second robotic arm is controlled to move d units along the Z+ direction in the first tool coordinate system, and rotate α angles around the X, Y, and Z axes respectively. The second camera is controlled to take three photos of the feature point, obtaining the three spatial coordinates P, Q, and N of the feature point in the first tool coordinate system when the second camera is in three different poses. The second robotic arm is also controlled to move d units along the Z- direction in the first tool coordinate system, and rotate α angles around the X, Y, and Z axes respectively. The second camera is controlled to take three photos of the feature point, obtaining the three spatial coordinates P', Q', and N' of the feature point in the first tool coordinate system when the second camera is in three different poses. The midpoint between P and P' is p, the midpoint between Q and Q' is q, and the midpoint between N and N' is n. The coordinates of p, q, and n in the first tool coordinate system are calculated. Record and transform the coordinates of the intermediate point, including the following steps: The controller controls the second robotic arm to rotate by an angle α around the X, Y, and Z axes in the cusp coordinate system and move to points p, q, and n respectively. The coordinates of points p, q, and n in the first tool coordinate system are recorded. The rotation angle of the second robotic arm in the cusp coordinate system is consistent with the rotation angle of the second robotic arm in the first tool coordinate system. The coordinate transformation relationships B, C, and D of the intermediate points p, q, and n in the first tool coordinate system and the cusp coordinate system are calculated respectively. The transformation relation B is: ， Where (x', y') refers to the coordinate information of point p in the first tool coordinate system, (u', y') refers to the coordinate information of p' in the second tool coordinate system, R' is the rotation matrix, and M' is the translation matrix; The transformation relation C is: ， (x'', y'') represents the coordinate information of point q in the first tool coordinate system, (u'', y'') represents the coordinate information of q' in the second tool coordinate system, R'' is the rotation matrix, and M'' is the translation matrix; The transformation relation D is: ， (x''', y''') represents the coordinate information of point n in the first tool coordinate system, (u''', y''') represents the coordinate information of n' in the second tool coordinate system, R''' is the rotation matrix, and M''' is the translation matrix; Establish a second tool coordinate system; based on the points in the first tool coordinate system, the second tool coordinate system is obtained after transformation. Complete hand-eye calibration.

2. The hand-eye calibration method for the automatic servo assembly system according to claim 1, characterized in that, The installation tip device includes: installing and fixing the tip device on the screw suction device, wherein the tip device is coaxially arranged with the screw suction device.

3. The hand-eye calibration method for the automatic servo assembly system according to claim 1, characterized in that, The establishment of the first tool coordinate system includes setting feature points on the surface of the calibration plate.

4. The hand-eye calibration method for the automatic servo assembly system according to claim 3, characterized in that, The feature points are cross-shaped markers.

5. The hand-eye calibration method for the automatic servo assembly system according to claim 1, characterized in that, The establishment of the cusp coordinate system includes: the X'-Y' plane of the cusp coordinate system is parallel to the XY plane of the first tool coordinate system, and the X', Y', and Z' axes are aligned with the X, Y, and Z axes of the first tool coordinate system.

6. The hand-eye calibration method for the automatic servo assembly system according to claim 5, characterized in that, The absolute distance between the origin of the cusp coordinate system and the origin of the first tool coordinate system in the Z-axis direction is the distance from the cusp of the cusp device to the center of the end face of the screw suction device.

7. The hand-eye calibration method for the automatic servo assembly system according to claim 6, characterized in that, The establishment of the cusp coordinate system also includes: the Z' axis of the cusp coordinate system is coaxial with the Z axis of the first tool coordinate system.

8. The hand-eye calibration method for the automatic servo assembly system according to claim 1, characterized in that, The completion of hand-eye calibration includes: the assembly system guiding the second robotic arm to perform positioning according to the second tool coordinate system.

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