Automatic tightening system and method based on dual-robot cooperation

Abstract

An automatic tightening system and method based on dual-robot cooperation. The automatic tightening system based on dual-robot cooperation comprises mounting column and lifting / lowering devices (1), robot systems (3), screw feeding systems (5), an operation terminal (6), and a control cabinet (7).

Description

An automated tightening system and method based on dual-robot collaboration Technical Field

[0001] This invention belongs to the field of assembly and manufacturing technology, and relates to an automatic tightening system and method based on dual-robot collaboration. Background Technology

[0002] Currently, the assembly and tightening process for aerospace products mostly relies on manual assembly using tools such as torque wrenches. This involves manually adjusting the torque value, manually applying the torque, and manually recording the tightening process. This method is labor-intensive, inefficient, and results in inconsistent torque application. There is an urgent need to introduce automated tightening devices to improve production efficiency and ensure consistent assembly quality.

[0003] Currently, the more mature automatic tightening methods mainly use tightening shafts (tightening guns) for torque output, angle control, and data recording, combined with tightening modules to achieve automatic screw feeding (or screw removal). Common automatic tightening devices are mostly suitable for planar tightening scenarios, using a three-axis motion mechanism to achieve planar motion and positioning, and equipped with a tightening shaft and screw feeding mechanism to automatically feed and tighten screws. Alternatively, a single robot equipped with a tightening shaft can be used for tightening operations in small-scale scenarios. However, aerospace products are larger, and assembly tightening involves tightening on many curved surfaces in space. Furthermore, aerospace products need to prevent deformation from affecting subsequent tightening, requiring high spatial accessibility and motion accuracy from the tightening device. A single robot equipped with a tightening mechanism is insufficient to meet the tightening requirements of aerospace products. At the same time, most current automatic tightening devices rely on mechanical positioning or visual hole-finding positioning for position assurance and tightening, lacking corrective measures for misalignment or deviation during the tightening process. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an automatic tightening system and method based on dual-robot collaboration. This automatic tightening system meets the requirements of spatial accessibility, motion positioning and position compensation, and automatic nail removal for tightening aerospace products.

[0005] To achieve the above objectives, the present invention employs the following technical solutions:

[0006] An automated tightening system based on dual-robot collaboration includes an installation column and lifting device, a robot system, a screw feeding system, an operating terminal, and a control cabinet.

[0007] There are two sets of mounting columns and lifting devices, installed in a gantry style and connected by cable trays; the robot system is mounted on the lifting device of the mounting columns and lifting devices, and moves via the lifting device; the end effector of the robot system is equipped with an actuator for performing nail-tightening actions; the screw feeding system is located on one side of the mounting column of the mounting columns and lifting devices for supplying the required screws; the operating terminal is equipped with a control system, which is used to issue tightening tasks, control the robot system, record and store data; the control cabinet is used for the electrical control and power supply of the system.

[0008] As a preferred embodiment, the mounting column and lifting device include a motor, a reducer, a lead screw, a lifting platform, a guide rail slider, a mounting base, a limit block, a cable chain, a limit switch, and the mounting column body.

[0009] The mounting column body is mounted on the mounting base. The motor, reducer, lead screw, and guide rail slider are mounted on the mounting column body and together drive the lifting platform to move vertically. The lifting platform is connected to the lead screw, and the limit block and limit switch are installed at the end of the lifting platform's stroke.

[0010] As a preferred embodiment, the actuator includes a six-dimensional force sensor, a tool holder, a 3D camera, a nail suction tube, grippers, a clamping cylinder, an electric screwdriver, a guide rail slider, a push cylinder, and a tightening gun.

[0011] The six-dimensional force sensor is connected to a robot system and a tool holder at both ends. A 3D camera is connected to one side of the tool holder, and a guide rail slider and a propulsion cylinder are connected to the other side. The tightening gun is connected to the guide rail slider, and an electric screwdriver is installed at the end of the tightening gun for tightening. The electric screwdriver is equipped with a nail suction tube, a gripper, and a clamping cylinder.

[0012] As a preferred embodiment, the robot system is equipped with an end-effector vision system.

[0013] This invention also discloses a method for using an automated tightening system based on dual-robot collaboration, comprising the following steps:

[0014] S1. The control system of the operation terminal issues tasks, and the end vision system of the robot system detects and identifies the spatial position of the threaded hole to be tightened and the position of the screw.

[0015] S2. Based on the detection data, calculate the collaborative operation path and determine the reference hole;

[0016] S3. Install the column and lifting device to coordinate with the robot system's movement, and the robot system will perform the nail removal operation;

[0017] S4. The robot system tightens the screws according to the planned path, and compensates for positional errors through the vision system.

[0018] As a preferred approach, in step S2, the vision system calculates the current pose of the product based on the detection data, and compensates for the offline planned dual-robot motion path by comparing the adjustment amount between the current pose and the offline pose, thereby avoiding interference.

[0019] As a preferred method, in step S3, the 3D camera visually identifies the position, the clamping cylinder controls the jaws to open, the push cylinder pushes the nail suction tube to 1-2mm from the screw head, the nail suction tube picks up the screw, the clamping cylinder controls the jaws to close to prevent the screw from falling, and the push cylinder retracts to complete the nail removal.

[0020] In a preferred manner, in step S4, the lifting platform, in conjunction with the robot system, moves the actuator to above the hole to be tightened. The robot system's joints move to adjust the screw to be perpendicular to the hole's normal direction, and the clamping cylinder controls the grippers to open. The robot system's end effector picks up the clamped screw and moves it close to the tightening position. The push cylinder pushes the electric screwdriver, and the tightening gun rotates to output torque, pushing the screw into the hole. A six-dimensional force sensor monitors the force and torque magnitude during the tightening process in real time and feeds it back to the control system. The robot admittance control algorithm adjusts the screw's direction and angle to perform position compensation, achieving automatic alignment of the screw and hole, and screw tightening.

[0021] This invention addresses the spatial accessibility requirements, motion positioning and position compensation, and automatic screw removal requirements for tightening in aerospace products. First, two collaborative robots carrying actuators perform spatial movement and positioning. Then, a column and lifting device are installed to extend the robots' range of motion. A screw removal mechanism is designed to pick up screws of various sizes, and a vision system performs hole location and position compensation. Finally, a six-dimensional force sensor is introduced to monitor the magnitude of force and torque in all directions during the tightening process, feeding this data back to the control system to adjust the tightening action and achieve smooth screw tightening.

[0022] The present invention has the following advantages:

[0023] (1) A fully automated tightening method was adopted to realize the automation of the entire process of nail removal, tightening control, and data collection and recording, which reduced the labor intensity of operators, improved the transfer efficiency, and avoided the risk of climbing operations during the assembly and tightening of large equipment.

[0024] (2) This invention utilizes two collaborative robots and employs a lifting device to extend the robots' range of motion, ensuring the accessibility of the robot's end-effector tightening mechanism and enabling the tightening of products within a certain spatial size range. Simultaneously, the two collaborative robots can perform symmetrical tightening, reducing the impact of product deformation during the tightening process.

[0025] (3) In the tightening assembly process, the present invention integrates a six-dimensional force sensor, which can monitor the magnitude of force and torque in each direction during the docking process and feed it back to the control system to adjust the tightening action and achieve smooth screw turning. Attached Figure Description

[0026] Figure 1 is a schematic diagram of the structure of the present invention;

[0027] Figure 2 is a schematic diagram of the installation column and lifting device;

[0028] Figure 3 is a schematic diagram of the actuator structure;

[0029] Figure 4 is a schematic diagram of the working state of the present invention. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings.

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0032] Example:

[0033] An automated tightening system based on dual-robot collaboration includes an installation column and lifting device, a robot system, a screw feeding system, an operating terminal, and a control cabinet.

[0034] The mounting column and lifting device 1 are installed in a gantry style, with cable tray 2 for wiring. The robot system 3 is mounted on the lifting platform 11 of the mounting column and lifting device 1, and can move up and down along the mounting column and lifting device 1 to expand the working range. The actuator 4 is installed at the end of the robot system 3 to perform the nail-collecting and tightening action. The screw feeding system 5 is placed on one side of the mounting column and lifting device, consisting of a screw feeding tray and a connecting position, for supplying screws; the actuator 4 can move directly to this position to pick up the screws. The operating terminal 6 is equipped with a control system for issuing tightening tasks, controlling the operation of the automatic tightening system, and providing feedback and recording data. The control cabinet 7 is responsible for the electrical control and power supply of the entire system.

[0035] As shown in Figure 2, the mounting column and lifting device 1 includes a motor 8, a reducer 9, a lead screw 10, a lifting platform 11, a guide rail slider 12, a mounting base 13, a limit block 14, a cable drag chain 15, a limit switch 16, and a mounting column body 17. The motor 8, reducer 9, lead screw 10, and guide rail slider 12 are mounted on the mounting column body 17 and together drive the vertical movement of the lifting platform 11. The limit block 14 and limit switch 16 are installed at the end of the lifting platform 11's stroke, serving as limit protection. The mounting base 13 is used for connection to the ground and for leveling.

[0036] As shown in Figure 3, the actuator 4 includes a six-dimensional force sensor 18, a tool holder 19, a 3D camera 20, a nail-collecting tube 21, a gripper 22, a clamping cylinder 23, an electric screwdriver 24, a guide rail slider 25, a propulsion cylinder 26, and a tightening gun 27. The six-dimensional force sensor 18 is installed at the end of the robot system 3, and the tool holder 19 is installed at the other end of the six-dimensional force sensor 18. The 3D camera 20 is installed on one side of the tool holder 19 for visual recognition and positioning. The guide rail slider 25 and the propulsion cylinder 26 are installed on the other side of the tool holder 19, driving the tightening gun 27, which is mounted on the guide rail slider 25, to move. A custom electric screwdriver 24 is installed at the end of the tightening gun 27 for screw tightening. The nail-collecting tube 21, the gripper 22, and the clamping cylinder 23 form a nail-collecting mechanism, which is fixedly installed on the guide rail slider 25 near the end of the electric screwdriver 24 to collect nails and prevent them from falling.

[0037] The usage instructions for this system are as follows:

[0038] (1) Once the equipment to be tightened is in place, the screw feeder is transported to the docking station by the workshop material AGV (or manually delivered to the docking station).

[0039] (2) The tightening task is manually issued on the control system at 6 control points of the operation terminal.

[0040] (3) The robot system 3 carries an end-of-line 3D camera 19 to identify the spatial position of the threaded hole of the product to be tightened and the position of the screw at the screw feeding system 5.

[0041] (4) Dual robot operation path calculation: Based on the detection situation, the reference hole is determined, and the control system calculates the dual robot operation path according to the operation strategy of symmetrical tightening of cylindrical parts.

[0042] (5) Automatic nail removal operation: The lifting platform 11, which is equipped with the column and lifting device 1, is driven by the motor 8, reducer 9, lead screw 10 and guide rail slider 12 to achieve vertical movement. It works with the robot system 3 to carry the end effector 4 to the screw feeding system 5 to perform nail removal operation. Among them, the 3D camera 19 visually identifies the position, the clamping cylinder 23 controls the gripper 22 to open, the push cylinder 26 pushes the nail suction tube 21 to near the screw head, the nail suction tube 21 picks up the screw, the clamping cylinder 23 controls the gripper 22 to close to prevent the screw from falling, the push cylinder 26 retracts, and the nail removal is completed.

[0043] (6) Tightening operation: The lifting platform 11, together with the robot system 3, moves the end effector tool 4 to above the hole to be tightened. The robot system 3 moves its joints to adjust the screw to be perpendicular to the normal of the hole. The clamping cylinder 23 controls the gripper 22 to open. The robot system 3, carrying the end effector, picks up the screw and moves it to the tightening position. The push cylinder 26 pushes the electric screwdriver 24, and the tightening gun 27 rotates to output torque to push the screw into the hole. At the same time, the end effector six-dimensional force sensor 18 monitors the force and torque of the docking and tightening process in real time and feeds it back to the control system to adjust the direction and angle of the screw and perform position compensation to achieve automatic alignment (axis alignment) of the screw and the hole, thereby achieving smooth screw tightening.

[0044] (7) Repeat steps (5) and (6), with the two sets of robot systems working together to complete the tightening of all the threaded holes according to the path planned in step (4).

[0045] (8) The 3D camera takes pictures of all screw tightening positions to confirm that there are no missing screws or incorrect installations. The control system organizes the data of the tightening process into a data report.

[0046] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. An automatic tightening system based on dual-robot collaboration, characterized in that: This includes the installation of columns and lifting devices, a robot system, a screw feeding system, an operating terminal, and a control cabinet. There are two sets of mounting columns and lifting devices, installed in a gantry style and connected by cable trays; the robot system is mounted on the lifting device of the mounting columns and lifting devices, and moves via the lifting device; the end effector of the robot system is equipped with an actuator; the screw feeding system is located on one side of the mounting column of the mounting columns and lifting devices, and is used to supply the required screws; the operating terminal is equipped with a control system, which is used to issue tightening tasks, control the robot system, record and store data; the control cabinet is used for the electrical control and power supply of the system.

2. The automatic tightening system based on dual-robot cooperation according to claim 1, characterized in that: The mounting column and lifting device include a motor, reducer, lead screw, lifting platform, guide rail slider, mounting base, limit block, cable drag chain, limit switch, and mounting column body. The mounting column body is mounted on the mounting base. The motor, reducer, lead screw, and guide rail slider are mounted on the mounting column body and together drive the lifting platform to move vertically. The lifting platform is connected to the lead screw, and the limit block and limit switch are installed at the end of the lifting platform's stroke.

3. The automatic tightening system based on dual-robot collaboration according to claim 1, characterized in that: The actuator includes a six-dimensional force sensor, a tool holder, a 3D camera, a nail suction tube, grippers, a clamping cylinder, an electric screwdriver, a guide rail slider, a push cylinder, and a tightening gun. The six-dimensional force sensor is connected to a robot system and a tool holder at both ends. The tool holder is connected to a 3D camera, a guide rail slider, and a propulsion cylinder on both sides. The tightening gun is connected to the guide rail slider, and an electric screwdriver is installed at the end of the tightening gun for tightening. The electric screwdriver is equipped with a nail suction tube, a gripper, and a clamping cylinder.

4. The automatic tightening system based on dual-robot collaboration according to claim 1, characterized in that: The robot system is equipped with an end-effector vision system.

5. A method of using the automated tightening system based on dual-robot collaboration as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. The control system of the operating terminal issues tasks, and the end vision system of the robot system detects and identifies the spatial position of the threaded hole and the screw position of the product to be tightened. S2. Based on the detection data, calculate the collaborative operation path and determine the reference hole; S3. Install the column and lifting device to coordinate with the robot system's movement, and the robot system will perform the nail removal operation; S4. The robot system tightens the screws according to the planned work path and compensates for positional errors through the vision system.

6. The method of using the automatic tightening system based on dual-robot cooperation as described in claim 5, characterized in that: In step S2, the vision system calculates the current pose of the product based on the detection data, and compensates for the offline planned dual-robot motion path by comparing the adjustment amount between the current pose and the offline pose.

7. The method of using the automatic tightening system based on dual-robot cooperation as described in claim 5, characterized in that: In step S3, the 3D camera visually identifies the position, the clamping cylinder controls the jaws to open, the push cylinder pushes the nail suction tube to 1-2mm from the screw head, the nail suction tube picks up the screw, the clamping cylinder controls the jaws to close, and the push cylinder retracts, completing the nail removal.

8. The method of using the automatic tightening system based on dual-robot cooperation as described in claim 5, characterized in that: In step S4, the lifting platform, in conjunction with the robot system, moves the actuator to above the hole to be tightened. The robot system's joints move to adjust the screw to be perpendicular to the hole's normal direction, and the clamping cylinder controls the grippers to open. The robot system's end effector picks up the clamped screw and moves it close to the tightening position. The push cylinder pushes the electric screwdriver, and the tightening gun rotates to output torque, pushing the screw into the hole. The six-dimensional force sensor monitors the force and torque magnitude during the tightening process in real time and feeds it back to the control system. The robot admittance control algorithm adjusts the screw's direction and angle to perform position compensation, achieving automatic alignment of the screw and hole, and screw tightening.

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