Aircraft component assembly system and method based on robot force-position hybrid control

Abstract

The present invention discloses an aircraft component assembly system and method based on robot force-position hybrid control. The aircraft component assembly system based on robot force-position hybrid control comprises a flexible gripper (1), an articulated robot (2), an AGV trolley (3), a product fixture (4), a six-dimensional force sensor (5) and a controller; the aircraft component assembly method based on robot force-position hybrid control comprises the following steps: S1: grabbing a workpiece, S2: transporting a workpiece; S3: docking the workpiece; S4: returning to the workstation. The beneficial effects of the present invention are as follows: the assembly efficiency is increased by 50%. The assembly accuracy is improved; at the same time, damage to the workpiece and the aircraft caused by excessive contact force during the assembly process is avoided; 40% of labor is reduced; the risk of workers being injured during the assembly process is reduced; and the process parameters of the assembly operation are visualized and controllable.

Description

Technical Field

[0001] The present invention relates to robot assembly technology, and in particular to an aircraft component assembly system and method based on robot force-position hybrid control. Background Art

[0002] Traditional industrial robots are all position-controlled. This type of position-controlled robot can perform certain tasks, such as welding, painting, and handling. It has been proven that position-controlled robots can perform tasks where the robot does not come into contact with the external environment or tasks where the robot needs to come into contact with the environment but does not require high contact force control. As a special application field for industrial robots, the assembly of large aircraft parts requires robots to meet the requirements of precision, flexibility, and human-machine collaboration during the assembly process due to the characteristics of the task, and requires real-time monitoring and control of the contact force between the aircraft and the parts. It is far from enough to simply control the position of the robot. The control of contact force and flexibility often determines whether the docking task can be successfully completed. Summary of the invention

[0003] The purpose of the present invention is to propose an aircraft component assembly system and method based on robot force-position hybrid control in order to solve the above problems.

[0004] An aircraft component assembly system based on robot force-position hybrid control comprises a flexible gripper (1), an articulated robot (2), an AGV trolley (3), a product fixture (4), a six-dimensional force sensor (5) and a controller; wherein:

[0005] The flexible gripper (1) is fixed on the product fixture (4) to realize the gripping action of the large aircraft component;

[0006] The base of the articulated robot (2) is fixed on the AGV trolley (3), and data is transmitted through a bus connection controller, and a six-dimensional force sensor (5) is installed at the end flange. At the same time, the product fixture (4) and the flexible gripper (1) are fixed at the end of its mechanical arm, and the instructions issued by the controller realize the grasping and assembly of aircraft parts;

[0007] The AGV trolley (3) is a mobile device of the system, which carries accessories to a specific workstation;

[0008] The data output end of the six-dimensional force sensor (5) is connected to the data input end of the controller to monitor the contact force between the aircraft and the component in real time;

[0009] The controller includes a multi-processing system to support remote control of the robot to grasp the workpiece.

[0010] Preferably, the flexible gripper (1) comprises four gripping portions in different directions.

[0011] Preferably, the articulated robot (2) is a six-axis robot, and the robot load is 150kg-300kg.

[0012] Preferably, the AGV trolley (3) is provided with an operation panel on its surface to set the working route of the AGV trolley and monitor the running status of the trolley.

[0013] Preferably, the articulated robot (2) uses a combination of an admittance algorithm and a force-position hybrid control algorithm to assemble workpieces.

[0014] Preferably, the controller also includes a PCI bus, a large-capacity flash disk, a USB storage interface and a teaching pendant.

[0015] An aircraft component assembly method based on robot force-position hybrid control comprises the following steps:

[0016] S1: The AGV goes to the workstation according to the instructions, and the robot automatically moves to the top of the workpiece;

[0017] S2: Start the force-controlled traction function and adjust the robot's end effector to make the gripper fit the workpiece exactly;

[0018] S3: The robot closes the gripper and lifts the workpiece into a transport posture;

[0019] S4: The AGV vehicle goes to the assembly station next to the aircraft through the ground markings;

[0020] S5: Adjust the robot to the assembly position;

[0021] S6: The worker starts the force-controlled traction function and inserts the shaft into the aircraft assembly hole by dragging the workpiece;

[0022] S7: Start force-controlled automatic insertion;

[0023] S8: Open the gripper, the robot moves back, and the AGV returns to the parking position.

[0024] Furthermore, the step S7 includes four stages: approach stage, chamfering stage, insertion stage, and insertion completion stage.

[0025] Preferably, during the assembly process, the controller monitors the external environmental force of the workpiece and the position of the robot throughout the entire process. If the contact force and / or the position of the robot are abnormal, the workpiece assembly will be stopped and an alarm will be issued.

[0026] The beneficial effects of the present invention are as follows: a six-dimensional force sensor is installed in the end flange of the robot to collect contact force, and the force information obtained is used in the component assembly process to perform algorithm control to achieve compliance, thereby increasing assembly efficiency by 50%.; assembly accuracy is improved; damage to the workpiece and the aircraft caused by excessive contact force during assembly is avoided; 40% of labor is reduced; the risk of workers being injured during assembly is reduced; and process parameters of assembly operations are visualized and controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a system device diagram of the present invention.

[0028] Figure 2 It is a partial device diagram of the present invention.

[0029] Figure 3 It is an assembly flow chart of the present invention.

[0030] Figure 4 It is the system control diagram of the present invention.

[0031] Figure 5 It is the main shaft force analysis diagram of the present invention.

[0032] In the figure: (1) - flexible gripper, (2) - articulated robot, (3) - AGV cart, (4) - product fixture, (5) - six-dimensional force sensor. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings.

[0034] like Figure 1 and Figure 2 As shown, an aircraft component assembly system based on robot force-position hybrid control comprises a flexible gripper (1), an articulated robot (2), an AGV vehicle (3), a product fixture (4), a six-dimensional force sensor (5) and a controller; wherein:

[0035] The flexible gripper (1) is fixed on the product fixture (4) to realize the gripping action of the large aircraft component;

[0036] The base of the articulated robot (2) is fixed on the AGV trolley (3), and data is transmitted through a bus connection controller, and a six-dimensional force sensor (5) is installed at the end flange. At the same time, the product fixture (4) and the flexible gripper (1) are fixed at the end of its mechanical arm, and the instructions issued by the controller realize the grasping and assembly of aircraft parts;

[0037] The AGV trolley (3) is a mobile device of the system, which carries accessories to a specific workstation;

[0038] The data output end of the six-dimensional force sensor (5) is connected to the data input end of the controller to monitor the contact force between the aircraft and the component in real time;

[0039] The controller includes a multi-processing system to support remote control of the robot to grasp the workpiece.

[0040] It should be understood that the flexible gripper (1) comprises four gripping arms in different directions.

[0041] It should be understood that the articulated robot (2) is a six-axis robot and the robot load is 150kg-300kg.

[0042] It should be understood that the surface of the AGV trolley (3) is provided with an operation panel for setting the working route of the AGV trolley and monitoring the running status of the trolley.

[0043] It should be understood that the articulated robot (2) uses a combination of an admittance algorithm and a force-position hybrid control algorithm to assemble workpieces.

[0044] It should be understood that the controller also includes a PCI bus, a large-capacity flash disk, a USB storage interface and a teaching pendant.

[0045] like Figure 3 As shown, a method for assembling aircraft parts based on robot force-position hybrid control includes the following steps:

[0046] S1: The AGV goes to the workstation according to the instructions, and the robot automatically moves to the top of the workpiece;

[0047] S2: Start the force-controlled traction function and adjust the robot's end effector to make the gripper fit the workpiece exactly;

[0048] S3: The robot closes the gripper and lifts the workpiece into a transport posture;

[0049] S4: The AGV vehicle goes to the assembly station next to the aircraft through the ground markings;

[0050] S5: Adjust the robot to the assembly position;

[0051] S6: The worker starts the force-controlled traction function and inserts the shaft into the aircraft assembly hole by dragging the workpiece;

[0052] S7: Start force-controlled automatic insertion;

[0053] S8: Open the gripper, the robot moves back, and the AGV returns to the parking position.

[0054] It should be understood that step S7 includes four stages: approach stage, chamfering stage, insertion stage, and insertion completion.

[0055] It should be understood that during the assembly process, the controller monitors the external environmental force of the workpiece and the robot position throughout the entire process. If the contact force and / or the robot position are abnormal, the workpiece assembly will be stopped and an alarm will be issued.

[0056] It should be understood that step S7 starts the force-controlled automatic insertion function. The robot will apply an assembly force along the direction of the workpiece spindle, and the workpiece will be finally assembled along the spindle direction. During the process of the spindle moving forward, the robot will adjust the position and posture of the workpiece spindle in real time according to the size and direction of the contact force until the spindle is fully inserted into the aircraft assembly hole.

[0057] like Figure 4 Shown is a control diagram of an aircraft component assembly system based on robot force-position hybrid control.

[0058] It is important to understand that first, we need to establish the conversion relationship T between the force and torque applied to the force sensor and the manipulator coordinate system at the end of the robot:

[0059]

[0060] It should be noted that the assembly system can map the force feedback to the robot base coordinate system through a conversion relationship, and the robot controls the robot to make corresponding movements through the force feedback.

[0061] It should be understood that the application of force-position hybrid control in the aircraft assembly process is divided into two steps. First, the spindle is manually pulled into the shaft hole for rough positioning, and then the robot adjusts the position according to the force on the spindle and inserts the spindle into the shaft hole.

[0062] It should be noted that because the force sensor has been zero-calibrated, after gravity compensation, the force sensor will only detect the contact force applied externally. When the force-controlled traction program is started, the system will detect the artificial traction force. The artificially applied external force is unstable, and a stable and smooth force feedback data can be obtained after dynamic filtering. After obtaining the artificial constraint force on the robot terminal actuator degree of freedom, the robot posture is adjusted in this direction, and the position error in the constraint direction should be ignored. At this time, the spatial position vector can be used to optimize the force control of the robot arm, and the redundancy of the end of the robot arm can be used to optimize the robot's motion performance. After solving the Jacobian matrix and the pseudo-inverse matrix, the movement rate of each joint of the robot is obtained, so that the robot can continuously change its posture to maintain a state completely free from external forces. In the macro state, it is the person who pulls the robot to move.

[0063] It should be noted that the robot's displacement and speed will be constrained in real time during the entire equipment process, and the robot will be stopped and an alarm will be sounded after the force feedback exceeds the limit. At the same time, the robot's motion trajectory, motion speed and force feedback data will be displayed in real time on the monitoring screen.

[0064] Figure 5 This is the force analysis diagram of the main shaft during insertion.

[0065] It should be noted that after the initial positioning of the spindle, in addition to the axial force, the spindle will also be subject to forces and moments in other directions. After the robot's active assembly algorithm is started, the robot will adjust its position to eliminate the forces and moments outside the spindle direction. And it will continuously implement pulse force in the spindle direction to guide the spindle to insert into the shaft hole.

Claims

1. An aircraft component assembly system based on robot force-position hybrid control, characterized in that: It includes a flexible gripper (1), an articulated robot (2), an AGV vehicle (3), a product fixture (4), a six-dimensional force sensor (5) and a controller; wherein: The flexible gripper (1) is fixed on the product fixture (4) to realize the gripping action of the large aircraft component; The base of the articulated robot (2) is fixed on the AGV trolley (3), and is connected to the controller via a bus to transmit data. A six-dimensional force sensor (5) is installed at the end flange. At the same time, a product fixture (4) and a flexible gripper (1) are fixed at the end of its mechanical arm. The controller issues instructions to realize the grasping and assembly of aircraft parts. The AGV trolley (3) is a mobile device of the system, which carries accessories to a specific workstation; The data output terminal of the six-dimensional force sensor (5) is connected to the data input terminal of the controller to monitor the contact force between the aircraft and the component in real time; The controller contains a multi-processing system, which remotely controls the robot to grab the workpiece and monitor the workpiece assembly process; It also includes: establishing a conversion relationship T between the force and torque of the force sensor and the manipulator coordinate system at the end of the robot, through which the force feedback can be mapped to the robot base coordinate system, and the robot is controlled to make corresponding movements through the force feedback; The articulated robot (2) uses an admittance algorithm and a force-position hybrid control algorithm to assemble workpieces, and the force-position hybrid control includes: The main shaft is manually pulled into the shaft hole for rough positioning. The robot adjusts the position according to the force on the main shaft and inserts the main shaft into the shaft hole. The force sensor is zero-calibrated, and after gravity compensation, the force sensor only detects the externally applied contact force; When the force-controlled traction program is started, the system detects the artificial traction force and obtains a stable and smooth force feedback data after dynamic filtering; After obtaining the artificial constraint force on the robot terminal actuator's degree of freedom, the robot's posture is adjusted, the force control of the robot arm is optimized using the spatial position vector, and the robot's motion performance is optimized using the redundancy of the robot arm's end. After solving the Jacobian matrix and the pseudo-inverse matrix, the movement rates of each joint of the robot are obtained, so that the robot can continuously change its posture to maintain a state completely free from external forces, pulling the robot to move.

2. The aircraft component assembly system based on robot force-position hybrid control as claimed in claim 1, characterized in that: The flexible gripper (1) comprises four clamping jaws with different directions.

3. The aircraft component assembly system based on robot force-position hybrid control as claimed in claim 1, characterized in that: The articulated robot (2) is a six-axis robot, and the robot load is 150kg-300kg.

4. The aircraft component assembly system based on robot force-position hybrid control as claimed in claim 1, characterized in that: The surface of the AGV trolley (3) is provided with an operation panel for setting the working route of the AGV trolley and monitoring the running status of the trolley.

5. The aircraft component assembly system based on robot force-position hybrid control as claimed in claim 1, characterized in that: The controller also includes a PCI bus, a large-capacity flash disk, a USB storage interface and a teaching pendant.

6. A method for assembling aircraft parts based on robot force-position hybrid control, implemented based on an aircraft parts assembly system based on robot force-position hybrid control as claimed in any one of claims 1 to 5, characterized in that: The steps include: S1: The AGV goes to the workstation according to the instructions, and the robot automatically moves to the top of the workpiece; S2: Start the force-controlled traction function and adjust the robot's end effector to make the gripper fit the workpiece exactly; S3: The robot closes the gripper’s jaws and lifts the workpiece into a transport posture; S4: The AGV vehicle goes to the assembly station next to the aircraft through the ground markings; S5: Adjust the robot to the assembly posture; S6: The worker starts the force-controlled traction function and inserts the shaft into the aircraft assembly hole by dragging the workpiece; S7: Start force-controlled automatic insertion; S8: Open the gripper, the robot moves back, and the AGV returns to the parking position.

7. The method for assembling aircraft parts based on robot force-position hybrid control as claimed in claim 6, characterized in that: The step S7 includes four stages: approach stage, chamfering stage, insertion stage, and insertion completion.

8. The method for assembling aircraft parts based on robot force-position hybrid control as claimed in claim 6, characterized in that: During the assembly process, the controller monitors the external environmental force of the workpiece and the robot posture throughout the entire process. If the contact force and / or the robot posture are abnormal, the workpiece assembly will be stopped and an alarm will be issued.

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