Automatic tightening system and method based on cooperation of double robots

Abstract

The invention discloses an automatic tightening system based on double-robot cooperation. The automatic tightening system comprises a mounting stand column, a lifting device, a robot system, a screw feeding system, an operation terminal and a control cabinet. The invention further discloses a using method of the automatic tightening system. According to the invention, the screw can be flexibly tightened, the horizontal assembly tightening efficiency of the product is improved, and the consistency of the assembly tightening quality of the product is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of assembly manufacturing, and relates to an automatic tightening system and method based on double robot collaboration. Background Art

[0002] During the current assembly and tightening process of aerospace products, fixed torque wrenches and other tools are mostly used for manual assembly. The assembly and tightening process is completed by manually adjusting the torque value, manually applying the torque to tighten, and manually recording. This assembly and tightening method has high labor intensity, low assembly efficiency, and poor consistency of the torque applied manually. It is urgent to introduce automatic tightening devices to improve production efficiency and ensure the consistency of assembly quality.

[0003] The current more mature automatic tightening method mainly uses a tightening shaft (tightening gun) for torque output, angle control and data recording, and cooperates with a tightening module to realize automatic nail feeding (or nail removal). Commonly used automatic tightening devices are mostly suitable for plane tightening scenarios, using a three-axis motion mechanism to achieve plane motion and positioning, and equipped with a tightening shaft and a nail feeding mechanism to achieve automatic nail feeding and tightening of screws, or a single robot equipped with a tightening shaft to perform tightening operations in a small operating range. However, aerospace products are large in size, and assembly tightening involves tightening of more spatial curved surface positions, and aerospace products need to prevent deformation from affecting subsequent tightening. The spatial accessibility and motion accuracy of the tightening device are required to be high. The method of using only a single robot equipped with a tightening mechanism is difficult to meet the tightening requirements of aerospace products. At the same time, most of the current automatic tightening devices use mechanical positioning or visual hole-finding positioning to ensure position and tighten, and there is a lack of corrective measures for deviation and crooked tightening during the tightening process. Summary of the invention

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

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] An automatic tightening system based on dual robot collaboration, including an installation column and a lifting device, a robot system, a screw feeding system, an operation terminal, and a control cabinet.

[0007] There are two sets of mounting columns and lifting devices, which are installed in a gantry style and connected by a cable bridge; the robot system is arranged on the lifting device of the mounting column and the lifting device, and is moved by the lifting device; an actuator is provided at the end of the robot system for performing the suction and tightening action; the screw feeding system is arranged on one side of the mounting column of the mounting column and the lifting device, for supplying the required screws; the operation terminal is arranged with a management and control system, which is used to issue tightening tasks, control the robot system, and record and store data; the control cabinet is used for electrical control and power supply of the system.

[0008] As a preferred embodiment, the mounting column and the 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 drag chain, a limit switch, and a mounting column body.

[0009] The mounting column body is arranged on the mounting base, and the motor, reducer, lead screw and guide rail slider are installed on the mounting column body to jointly 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 travel of the lifting platform.

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

[0011] The two ends of the six-dimensional force sensor are respectively connected to a robot system and a tool holder, one side of the tool holder is connected to a 3D camera, and the other side is connected to a guide rail slider and a thrust cylinder; 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 matched with a nail suction tube, a clamping claw, and a clamping cylinder.

[0012] As a preferred embodiment, the robot system is provided with a terminal vision system.

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

[0014] S1. The control system of the operation terminal issues tasks, and the terminal 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. Calculate the collaborative operation path and determine the reference hole based on the detection data;

[0016] S3, installing the column and the lifting device to cooperate with the robot system to move, and the robot system performs the nail removal operation;

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

[0018] As a preferred method, in step S2, the visual system calculates the current posture 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 posture and the offline posture to avoid 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 pushing cylinder pushes the nail suction tube to 1-2 mm from the screw head, the nail suction tube sucks the screw, the clamping cylinder controls the jaws to close to prevent the screw from falling, and the pushing cylinder is retracted to complete the nail removal.

[0020] As a preferred method, in step S4, the lifting platform cooperates with the robot system to carry the actuator to move above the hole to be tightened, the robot system joints move, the screw is adjusted to be perpendicular to the hole normal, and the clamping cylinder controls the jaws to open; the robot system carries the end to absorb the clamped screw and bring it close to the tightening position, the thrust cylinder pushes the electric screwdriver, and the tightening gun rotates to output torque to push the screw into the hole; the six-dimensional force sensor monitors the force and torque of the docking tightening process in real time, and feeds back to the management and control system, and adjusts the direction and angle of the screw through the robot admittance control algorithm, performs position compensation, and realizes automatic alignment of the screw and the hole, and screwing of the screw.

[0021] The present invention aims at the spatial accessibility requirements, motion positioning and position compensation, and automatic nail removal requirements of aerospace product tightening. First, two collaborative robots carry actuators for spatial motion and positioning, and then expand the robot's range of motion by installing columns and lifting devices. The nail removal mechanism is designed to achieve the absorption of screws of various specifications, and the visual system is used to perform hole positioning and position compensation. Finally, a six-dimensional force sensor is introduced to monitor the magnitude of force and torque in each direction during the tightening process, and the force and torque are fed back to the control system to adjust the tightening action and achieve smooth tightening of the screws.

[0022] The present invention has the following advantages:

[0023] (1) A fully automated tightening method is adopted to automate the entire process of nail removal, tightening control, and data collection and recording, which reduces the labor intensity of operators, improves transportation efficiency, and avoids the risk of high-altitude operations during the assembly and tightening of large equipment.

[0024] (2) The present invention uses two collaborative robots and a lifting device to expand the robot's range of motion, ensuring the accessibility of the robot's end tightening mechanism and being compatible with the tightening of products within a certain spatial size range. At the same time, the two collaborative robots can perform symmetrical tightening at the same time, which can reduce the deformation of the product object during the tightening process.

[0025] (3) During the tightening and assembly process, the present invention integrates a six-dimensional force sensor, which can monitor the magnitude of forces and torques in various directions during the docking process, and feed them back to the control system to adjust the tightening action and achieve smooth screwing of the screws. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0029] Figure 4 It is a schematic diagram of the working state of the present invention. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0031] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0032] Example:

[0033] An automatic tightening system based on dual robot collaboration, including an installation column and a lifting device, a robot system, a screw feeding system, an operation terminal, and a control cabinet.

[0034] The mounting column and lifting device 1 are installed in a gantry style, with wiring through a cable bridge 2 in the middle. The robot system 3 is installed on the lifting platform 11 of the mounting column and lifting device 1. The robot system 3 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 and is used to perform the suction and tightening action. The screw feeding system 5 is placed on one side of the mounting column and the lifting device. It consists of a screw feeding tray and a docking position, which is used to supply screws. The actuator 4 can move directly here to take nails. The operation terminal 6 is equipped with a management and control system for issuing tightening tasks, controlling the operation of the automatic tightening system, and feeding back recorded data. The control cabinet 7 is responsible for the electrical control and power supply of the entire system.

[0035] Combination Figure 2As shown, 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, the reducer 9, the lead screw 10, and the guide rail slider 12 are mounted on the mounting column body 17, and together drive the lifting platform 11 to move vertically. The limit block 14 and the limit switch 16 are installed at the end of the travel of the lifting platform 11 to play a role of limit protection. The mounting base 13 is used to connect to the ground and level it.

[0036] Combination Figure 3 As shown, the actuator 4 includes a six-dimensional force sensor 18, a tool holder 19, a 3D camera 20, a nail suction tube 21, a clamp 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 to drive the tightening gun 27 installed on the guide rail slider 25 to move. A customized electric screwdriver 24 is installed at the end of the tightening gun 27 for screw tightening. The nail suction tube 21, the clamp 22, and the clamping cylinder 23 constitute a nail suction mechanism, which is fixedly installed on the guide rail slider 25 near the end of the electric screwdriver 24 to suck nails and prevent them from falling.

[0037] The method of using this system is as follows:

[0038] (1) After the tightening equipment products are in place, the screw feed tray is transported to the docking position by the workshop material AGV (or manually delivered to the docking position);

[0039] (2) Manually issue tightening tasks on the control system at the operation terminal 6.

[0040] (3) The robot system 3 carries a terminal 3D camera 19 to identify the spatial position of the threaded hole of the tightening equipment product and the screw position at the screw feeding system 5.

[0041] (4) Calculation of the dual robot operation path: Based on the detection results, the reference hole is determined, and the control system calculates the dual robot operation path based on the operation strategy of symmetrical tightening of cylindrical parts.

[0042] (5) Automatic nail removal operation: The lifting platform 11 of the installation column and the lifting device 1 is driven by the motor 8, the reducer 9, the lead screw 10, and the guide rail slider 12 to achieve vertical movement, and cooperates with the robot system 3 to carry the end effector 4 to move to the screw feeding system 5 to remove the nail. Among them, the 3D camera 19 visually recognizes the position, the clamping cylinder 23 controls the clamping claw 22 to open, the pushing cylinder 26 pushes the nail suction tube 21 to the head of the screw, the nail suction tube 21 sucks the screw, the clamping cylinder 23 controls the clamping claw 22 to close to prevent the screw from falling, and the pushing cylinder 26 is retracted to complete the nail removal.

[0043] (6) Tightening operation: The lifting platform 11 cooperates with the robot system 3 to carry the end-effector tool 4 to move above the hole to be tightened. The robot system 3 moves its joints to adjust the screw to be perpendicular to the hole normal, and the clamping cylinder 23 controls the jaws 22 to open. The robot system 3 carries the end to absorb the clamped screw and bring it close to the tightening position. The thrust 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 six-dimensional force sensor 18 monitors the force and torque of the docking tightening process in real time, and feeds back to the control system to adjust the direction and angle of the screw, perform position compensation, and realize automatic alignment of the screw and the hole (axis alignment), thereby achieving smooth screwing of the screw.

[0044] (7) Repeat steps (5) and (6), and the two robot systems 3 cooperate to complete the tightening work of all the threaded holes to be tightened according to the path planned in step (4).

[0045] (8) The 3D camera 20 takes photos of all the screw locking 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] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. An automatic tightening system based on dual robot collaboration, characterized in that: Including installation of columns and lifting devices, robot system, screw feeding system, operation terminal, control cabinet, There are two sets of mounting columns and lifting devices, which are installed in a gantry style and connected by a cable bridge; the robot system is arranged on the lifting device of the mounting column and the lifting device, and is moved by the lifting device; an actuator is provided at the end of the robot system; the screw feeding system is arranged on one side of the mounting column of the mounting column and the lifting device, and is used to supply the required screws; the operation terminal is arranged with a management and control system, which is used to issue tightening tasks, control the robot system, and record and store data; the control cabinet is used for electrical control and power supply of the system.

2. The automatic tightening system based on dual robot collaboration according to claim 1, characterized in that: 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 drag chain, a limit switch, and a mounting column body. The mounting column body is arranged on the mounting base, and the motor, reducer, lead screw and guide rail slider are installed on the mounting column body to jointly 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 travel of the lifting platform.

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, a clamping claw, a clamping cylinder, an electric screwdriver, a guide rail slider, a propulsion cylinder, and a tightening gun. The two ends of the six-dimensional force sensor are respectively connected to the robot system and the tool bracket, and the two sides of the tool bracket are respectively connected to the 3D camera, the guide rail slider and the propulsion cylinder; 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 matched with a nail suction tube, a clamping claw, 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 provided with a terminal vision system.

5. A method for using the automatic tightening system based on dual robot collaboration as claimed in any one of claims 1 to 4, characterized in that: The steps include: S1. The control system of the operation terminal issues tasks, and the terminal 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. Calculate the collaborative operation path and determine the reference hole based on the detection data; S3, installing the column and the lifting device to cooperate with the robot system to move, and the robot system performs the nail removal operation; S4. The robot system tightens the screws according to the planned operation path and compensates for the position error through the vision system.

6. The method for using the automatic tightening system based on dual robot collaboration as claimed in claim 5, characterized in that: In step S2, the visual system calculates the current posture 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 posture and the offline posture.

7. The method for using the automatic tightening system based on dual robot collaboration as claimed 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 pushing cylinder pushes the nail suction tube to 1-2 mm from the screw head, the nail suction tube sucks the screw, the clamping cylinder controls the jaws to close, and the pushing cylinder is retracted to complete the nail removal.

8. The method for using the automatic tightening system based on dual robot collaboration as claimed in claim 5, characterized in that: In step S4, the lifting platform cooperates with the robot system to carry the actuator to move above the hole to be tightened, the robot system joints move, the screw is adjusted to be perpendicular to the hole normal, and the clamping cylinder controls the jaws to open; the robot system carries the end to absorb the clamped screw and bring it close to the tightening position, the thrust cylinder pushes the electric screwdriver, and the tightening gun rotates to output torque to push the screw into the hole; the six-dimensional force sensor monitors the force and torque of the docking tightening process in real time, and feeds back to the management and control system, and adjusts the direction and angle of the screw through the robot admittance control algorithm, performs position compensation, and realizes automatic alignment of the screw and the hole, and screwing of the screw.

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