A Robot Compliant Assembly Control Method and System for Aircraft Flap Components

Abstract

The present invention provides a method and system for robot compliant assembly control of an aircraft flap component, relating to the technical field of compliant assembly control. This method establishes a compliant assembly system for the flap component through a force sensor and a mobile industrial robot, innovates a compliant assembly and adjustment method that integrates human-machine collaboration and robot compliant control, identifies the zero drift, temperature drift of the force sensor, and the gravity and center of gravity of the end load, ensuring the accuracy of the perception of external force information of the system; designs a highly flexible compliant control mechanism with various freely combined modes such as single-axis, multi-axis linkage, step-by-step, and continuous adjustment, tests and fits the jitter and non-jitter intervals according to the jitter distribution of the system force control coefficient, and proposes a theoretical assembly model based on the assembly trajectory and assembly force information of the flap sample, realizing the compliant assembly of the aircraft flap based on the desired trajectory. The present invention provides a solution for the compliant assembly of large aircraft flap components, with characteristics such as intelligence, good flexibility, and strong adaptability.

Description

Technical Field

[0001] The present invention relates to the technical field of compliant assembly control, and particularly to a robot compliant assembly control method and system for aircraft flap components. Background Art

[0002] Aircraft flap components are characterized by small batch sizes, large dimensions, and heavy loads. Their assembly quality with the wings and fuselage directly affects the lift or drag during aircraft takeoff and landing. Due to their unique structural and functional characteristics, the assembly process of aircraft flaps presents multi-point or continuous trajectory constraints. At the same time, the high assembly accuracy greatly increases the difficulty of flap assembly. In addition, during the actual aircraft sub-assembly and final assembly processes, the positions of the fuselage and flaps are not fixed during the assembly of different batches of aircraft, resulting in long assembly equipment scheduling and mating times, seriously affecting the progress of aircraft final assembly. Therefore, a highly flexible and efficient robot compliant assembly method and equipment suitable for aircraft flaps are needed.

[0003] At the current stage, during the aircraft final assembly process, the assembly of flaps mostly uses a hoisting method that combines tooling and lifting appliances. This method requires a large number of assembly workers, has low efficiency, and has low multi-person assembly coordination and poor stability. Assembly collisions and other problems are likely to occur. The existing hoisting assembly method cannot achieve assembly speed control. The efficiency of large-scale movement and local movement completely depends on the operator, and the alignment adjustment amount during precise assembly is uncontrollable, requiring a high level of assembly technology and coordination for the operator. In addition, the hoisting assembly method requires an open space at the assembly site and no obstruction above the assembly object, so the applicable scenarios are limited. Summary of the Invention

[0004] Object of the Invention: To propose a robot compliant assembly control method for aircraft flap components, and further propose a robot compliant assembly system for aircraft flap components that can execute this control method to solve the above problems existing in the prior art.

[0005] In a first aspect of the present invention, a robot compliant assembly system for aircraft flap components is proposed. The assembly system includes a product bracket, an assembly object, an AGV automatic guided vehicle, an industrial robot, an end effector, and a six-axis force sensor.

[0006] The product bracket is arranged at a predetermined position within a predetermined working space; an aircraft flap and an aircraft flap sample are placed on the product bracket.

[0007] The assembly object is arranged at a predetermined position within a predetermined working space.

[0008] The AGV automatic guided vehicle moves within the predetermined working space.

[0009] The industrial robot is installed on the AGV automatic guided vehicle; the end fixture of the industrial robot clamps the aircraft flap sample; under the movement of the AGV automatic guided vehicle, the industrial robot can reach the product bracket and the assembly object.

[0010] The six-axis force sensor is installed between the flange of the industrial robot and the end fixture, and can sense the external force information from the end fixture, the aircraft flap, and the aircraft flap sample.

[0011] Based on the aircraft flap component robot compliant assembly system proposed in the first aspect, in the second aspect of the present invention, a method for controlling the robot compliant assembly of the aircraft flap component is proposed, and the steps are as follows:

[0012] Step 1: Move the AGV automatic guided vehicle to the aircraft flap assembly station, and determine that the position of the product bracket equipped with the aircraft flap and the aircraft flap sample meets the assembly space.

[0013] Step 2: Determine the state of the end fixture of the industrial robot, establish the robot base coordinate system {B}, the flange coordinate system {F}, and the force sensor coordinate system {S}, adjust the pose of the industrial robot, collect multiple groups of robot pose information and the corresponding end force sensor information in a stable state, and calculate the gravity, center of gravity of the end fixture, and the zero drift and temperature drift values of the force sensor.

[0014] Step 3: Perform gravity compensation on different poses during the movement of the industrial robot according to the calculated gravity, center of gravity of the end fixture, and the zero drift and temperature drift values of the force sensor.

[0015] Step 4: The operator drags the end fixture to near the product bracket.

[0016] Step 5: The end fixture clamps the aircraft flap sample from the product bracket.

[0017] Step 6: The six-axis force sensor collects the gravity and center of gravity of the currently clamped aircraft flap sample, and determines whether the current clamping environment meets the process requirements. If not, readjust the clamping position until the process requirements are met.

[0018] Step 7: When the distance between the end of the industrial robot and the assembly object is greater than or equal to the safety distance, adjust to the fast force control mode, and control the industrial robot to the pre-assembly space position of the flap at the speed in the fast force control mode.

[0019] Step 8: When the distance between the end of the industrial robot and the assembly object is less than the safety distance, adjust to the slow force control mode.

[0020] Step 9: The operator drags the aircraft flap sample close to the assembly position at the speed in the slow force control mode.

[0021] Step 10: Set the force control trigger upper and lower thresholds of the aircraft flap component robot compliant assembly system [F B , F T ;

[0022] Step 11: Under the condition of the force control trigger upper and lower thresholds [F B , F T , assemble the aircraft flap sample to the predetermined position, complete the assembly of the flap sample, and record the motion trajectory L1 and the force information after gravity compensation of the force sensor;

[0023] Step 12: Under the condition of the force control trigger upper and lower thresholds [F B , F T , move the aircraft flap sample out of the assembly position from the predetermined assembly position, and at the same time record the force information and the robot's motion trajectory L2 during the removal process;

[0024] Step 13: Taking the aircraft flap assembly theoretical trajectory L E as the target, fit and optimize the motion trajectories L1 and L2 during the assembly process to obtain the expected motion trajectory during the robot compliant assembly process at the current spatial position;

[0025] Step 14: The AGV automatic guided vehicle moves to the aircraft flap sample storage rack, releases the end fixture, places the aircraft flap sample back on the product bracket, and at the same time clamps the aircraft flap. Repeat steps 4 to 9 to move the aircraft flap to the pre-assembly position;

[0026] Step 15: The aircraft flap component robot compliant assembly system starts the compliant assembly control based on the expected motion trajectory ;

[0027] Step 16: After assembling in place according to step 15, stop the automatic assembly, release the end fixture, and return to the initial position to complete the aircraft flap assembly.

[0028] In a further embodiment of the second aspect, in step 2, the origin of the robot base coordinate system {B} is located at the center point of the base; the origin of the flange coordinate system {F} is located at the center point of the flange; the origin of the force sensor coordinate system {S} is located at the center of the force sensor;

[0029] Design the force sensor coordinate system {S} to coincide with the flange coordinate system {F} in direction, with only translation in the z direction, and the x, y, and z directions of the end force sensor information coincide with the x S , y S , z S of the force sensor coordinate system {S} respectively.

[0030] In a further embodiment of the second aspect, the relationship between the data collected by the six-axis force sensor and the weight of the suspended load is as follows:

[0031]

[0032] where G x 、G y 、G z 、T Gx 、T Gy and T Gz are the components of the load gravity in the x, y, and z directions and the moments about the three axes in the force sensor coordinate system {S}; F x 、F y 、F z 、T x 、T y and T z are the six-axis force information collected by the force sensor respectively; F x0 、F y0 、F z0 、T x0 、T y0 、T z0 are the zero-drift value and temperature-drift value of the force sensor;

[0033] The relationship between the temperature-drift value of the six-axis force sensor and the ambient temperature C t is successively F x0 (C t ), F y0 (C t ), F z0 (C t ), T x0 (C t ), T y0 (C t ), T z0 (C t ), then the zero-drift value of the six-axis force sensor satisfies:

[0034]

[0035] where 、 、 、 、 、 are the zero-drift values of the force and the moments about the three rotation axes in the x, y, and z directions of the six-axis force sensor respectively;

[0036] The load gravity, moment, and the position of the load center of gravity in the force sensor coordinate system {S} (x g , y g , z g ) satisfy:

[0037] 。

[0038] In a further embodiment of the second aspect, in steps 7 and 8, variable admittance control is adopted to switch and adjust between the fast force control mode and the slow force control mode;

[0039] The parameter change range of the variable admittance control is the experimental calibration result, where the virtual stiffness coefficient is zero, the virtual mass and virtual damping parameters are adjusted, the admittance parameter values in the non-vibration and critical vibration states are recorded, the system state is divided into a vibration interval and a non-vibration interval, and the system force control drag speed adjustment interval is set within the non-vibration interval.

[0040] In a further embodiment of the second aspect, in steps 7 and 8, the operator's intention is recognized at all times:

[0041] When the acceleration output by the admittance model is not 0 and the acceleration direction is the same as the velocity direction, then accelerate;

[0042] When both the output acceleration and velocity are 0, or when the external force is 0, then stop;

[0043] In other cases, when the external force is not 0, the operation intention is to decelerate;

[0044] The expression of this process is as follows:

[0045]

[0046] In the formula, F is the external force received after gravity compensation; and are the velocity and acceleration in the i-axis direction respectively, i is the degrees of freedom of translation and rotation of the three directions x, y, and z at the end of the robot, and the acceleration and deceleration of each axis operate independently.

[0047] In a further embodiment of the second aspect, in step 9, the single force control end adjustment amount is set according to the adjustment distance, and the change range of the single-step adjustment amount of the translation axis is [0.005 mm, 1 mm], and the change range of the single-step adjustment amount of the rotation axis is [0.001°, 0.1°].

[0048] In a further embodiment of the second aspect, in step 10, the force control trigger upper and lower thresholds [F B , F T of the aircraft flap component robot compliant assembly system are set, specifically including:

[0049] A floating structure is provided at the sliding rail connection part of the aircraft flap sample, and the change range of its compression or tensile force is [F S1 , F S2 ;

[0050] Force control trigger lower threshold F B Determined by the minimum compression force of the floating mechanism; the upper threshold F of force control trigger T Determined by the maximum compression or tensile force of the floating mechanism;

[0051] The implementation logic is as follows:

[0052]

[0053] Wherein, is the external force received after gravity compensation of the i-th axis; i is the degrees of freedom of translation and rotation in the three directions of x, y, and z at the end of the robot.

[0054] In a further embodiment of the second aspect, in step 13, the motion trajectories L1 and L2 are motion trajectory information in the robot base coordinate system {B}, and L E is a theoretical trajectory at an uncertain position in space. During the fitting process, the trajectory L E is defined in the robot base coordinate system {B} to obtain the assembly trajectory with the smallest difference from the two trajectories L1 and L2. :

[0055] .

[0056] In the third aspect of the present invention, an electronic device is proposed. The electronic device includes a processor, a memory, a communication interface, and a communication bus. The processor, the memory, and the communication interface complete mutual communication through the communication bus; the memory is used to store a number of executable instructions, and the executable instructions cause the processor to execute the aircraft flap component robot compliant assembly control method as described in the second aspect.

[0057] In the fourth aspect of the present invention, a computer-readable storage medium is proposed. The storage medium stores a number of executable instructions. When the executable instructions run on an electronic device, the electronic device is caused to execute the aircraft flap component robot compliant assembly control method as described in the second aspect.

[0058] Beneficial effects:

[0059] 1) The present invention proposes an aircraft flap component robot compliant assembly system and its operation method. Through the AGV, robot, force sensor, special end fixture, and flap sample, the compliant assembly of the aircraft flap with a continuous motion trajectory is realized. The method has high flexibility and strong adaptability. Through methods such as end quick change, AGV movement, and database establishment, the compliant assembly of aircraft flaps with different specifications, different batches, and different spatial positions can be realized.

[0060] 2) In order to accurately sense the external forces acting on the aircraft flap during the assembly process, the present invention takes into account the influences of the end effector, the aircraft flap, the zero drift and temperature drift of the force sensor, and proposes corresponding identification and compensation methods, enabling the system to sense the external forces during the assembly process in different environments. Combining with the force-controlled compliant assembly method, the robot system can sense the assembly force and correspondingly adjust the robot pose, avoiding excessive force on the aircraft flap during assembly and causing damage to the system and the product.

[0061] 3) The present invention proposes a variable admittance control method including step control and variable-speed force control, which can achieve large-range rapid movement and small-range slow movement of single-axis or multi-axis of the robot compliant assembly system according to human operation intentions. At the same time, step control can be carried out during the local precise pose adjustment process, and the size of the single-step distance is controllable, improving the operation efficiency, operability and adaptability of the system, and meeting the accuracy requirements of different processes in the aircraft flap assembly process.

[0062] 4) The present invention adopts a pre-assembly method for the aircraft flap sample with a floating mechanism, collects the trajectory information and force information of the aircraft flap assembly, and obtains the assembly movement trajectory during the actual assembly process of the aircraft flap by fitting with the theoretical assembly trajectory. Combining with the force-controlled compliant assembly method based on the desired trajectory, the automatic compliant assembly of the aircraft flap component with continuous trajectory constraints is realized, providing a highly flexible solution for the assembly of the aircraft flap component. Description of the Drawings

[0063] Figure 1 It is a composition diagram of the compliant assembly system for the aircraft flap component in the embodiment.

[0064] Figure 2 It is a control flow chart of the robot compliant assembly for the aircraft flap component in the embodiment.

[0065] Figure 3 It is a coordinate system relationship diagram of the robot compliant assembly system in the embodiment.

[0066] Figure 4 It is a diagram of the system force control jitter interval division and variable admittance parameter selection interval in the embodiment.

[0067] The reference numerals in the figures are as follows: AGV automatic guided vehicle 1, robot control cabinet 2, end electrical control cabinet 3, industrial robot 4, product bracket 5, six-axis force sensor 6, aircraft flap 7, end effector 8, assembly object 9, aircraft flap sample 10, obstacle avoidance radar 11. Detailed Embodiments

[0068] In the following description, numerous specific details are given to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without one or more of these details. In other instances, some well-known technical features are not described to avoid obscuring the present invention.

[0069] The following embodiments disclose a robot compliant assembly control method and system for aircraft flap components, which are used for the inner flap assembly during the aircraft wing assembly process, to achieve highly flexible, efficient, highly integrated, and easy-to-operate aircraft flap 7 assembly, and provide technical support for improving aircraft assembly efficiency.

[0070] Figure 1 The structure of the robot compliant assembly system for aircraft flap components is shown. The assembly system includes the following hardware: AGV automatic guided vehicle 1, industrial robot 4, six-axis force sensor 6, end effector 8, obstacle avoidance radar 11, aircraft flap sample 10, and product bracket 5. Among them, the working range of the robot can reach the product bracket 5 and the assembly object 9. The six-axis force sensor 6 is located between the robot flange and the end effector 8, and can sense the external force information of the end effector 8, aircraft flap 7, and aircraft flap sample 10. The robot control cabinet 2 and the end electrical control cabinet 3 are carried on the automatic guided vehicle, which can achieve large-range movement and has a four-foot support anti-overturning function. The six-axis force sensor 6 and the robot rated load meet the weight of the end effector 8. The product bracket 5 can place the aircraft flap 7 and the aircraft flap sample 10 at the same time.

[0071] Figure 2 The control flow of the assembly system is shown, and the specific steps are as follows:

[0072] Step 1: According to the actual requirements of the aircraft assembly site, mobilize the AGV automatic guided vehicle 1 carrying the robot compliant assembly system to the aircraft flap 7 assembly station, move the bracket carrying the aircraft flap 7 to be assembled and the aircraft flap sample 10 to the corresponding assembly working position, ensure that the spatial position relationship among the robot, the bracket, and the assembly object 9 conforms to the working range of the robot, and deploy the four-foot support of the AGV automatic guided vehicle 1 to improve the stability of the entire system.

[0073] Step 2: Determine the state of the robot end effector 8. As Figure 3 shown, establish the robot base coordinate system {B}, flange coordinate system {F}, and force sensor coordinate system {S}, adjust the robot pose, collect multiple groups of robot pose information and the corresponding end force sensor information under stable states, and calculate the gravity, center of gravity of the end effector 8, and the zero drift and temperature drift values of the force sensor.

[0074] Among them, the origin of the robot base coordinate system is located at the center point of the base, the origin of the flange coordinate system is located at the center point of the flange, and the origin of the force sensor coordinate system is located at the center of the force sensor. It is designed that the direction of the force sensor coordinate system coincides with that of the flange coordinate system, with only a translation in the z direction, and the x, y, and z directions of the force information coincide with the x S 、y S 、z S of the force sensor coordinate system respectively.

[0075] Furthermore, the relationship between the data collected by the force sensor and the weight of the suspended load is as follows:

[0076]

[0077] In the formula, G x 、G y 、G z 、T Gx 、T Gy and T Gz are the component forces and torques of the load gravity in the x, y, and z directions of the {S} coordinate system, F x 、F y 、F z 、T x 、T y and T z are the six-dimensional force information collected by the force sensor respectively, and F x0 、F y0 、F z0 、T x0 、T y0 、T z0 are the zero drift value and temperature drift value of the force sensor. The relationship between the temperature drift value of the force sensor and the ambient temperature C t is successively F x0 (C t ), F y0 (C t ), F z0 (C t ), T x0 (C t ), T y0 (C t ), T z0 (C t ). Then, the zero drift value of the sensor satisfies:

[0078]

[0079] Furthermore, the relationship between the load gravity, torque and the position (x g , y g , z g ) of the load center of gravity in the coordinate system {S} satisfies:

[0080]

[0081] Substitute Equation (1) into Equation (3) and simplify to obtain:

[0082]

[0083] where

[0084]

[0085] Collect information on the different poses of the robot and the corresponding force sensor information in more than three groups, record the environmental stability, and substitute it into Equation (4) to obtain the center of gravity of the load (x g , y g , z g ), and (r1, r2, r3). Further substitute them into Equation (5) and Equation (2) to obtain the zero drift and temperature drift values of the sensor.

[0086] Step 3: Perform gravity compensation on different poses during the robot movement according to the identified gravity, center of gravity, and sensor zero drift value, and ensure that the force information collected by the force sensor after compensation meets the requirements of force-controlled compliant assembly. Otherwise, increase the pose coverage range and number of groups for identifying the robot's gravity and center of gravity until the gravity compensation requirements are met.

[0087] Step 4: Turn on the human-robot collaborative force control function of the robot compliant assembly system, and the operator drags the end effector 8 to near the bracket of the aircraft flap 7 and the aircraft flap sample 10.

[0088] During this process, the robot pose and force sensor information are collected in real time. To ensure the effectiveness of the force sensor information and avoid sudden changes in the system state caused by external interference and accidental collisions, set the force sensor sampling frequency to be greater than 1 KHz, and perform moving average filtering on the collected information before gravity compensation calculation to avoid waste of calculation efficiency. Further, combine admittance control to calculate the robot pose adjustment information corresponding to the current state, and periodically make the robot move according to the adjustment information.

[0089] Further, drag the end effector 8 to the clamping position of the aircraft flap sample 10 according to the above operation.

[0090] Step 5: Turn off the human-robot collaborative force control function of the system, turn on the clamping function of the end effector 8, and complete the clamping of the aircraft flap sample 10.

[0091] Step 6: Repeat Step 2 to complete the identification of the end gravity and center of gravity in the clamped state, compare the identification results with the theoretical data, and ensure that the clamping pose and compensation results of the aircraft flap sample 10 meet the process requirements. If not, readjust the clamping position until the gravity compensation requirements are met.

[0092] Step 7: Adjust the spatial position of the robot end to a position suitable for the worker to drag, turn on the system compliance control, manually judge the distance between the robot end and the assembly object 9, adjust to the fast force control dragging speed, and quickly control the robot to the pre-assembly spatial position of the flap.

[0093] Further, the variable admittance control is adopted to adjust the force control dragging speed in Step 7, and the parameter variation range is the experimental calibration result. Among them, the virtual stiffness coefficient is zero, the virtual mass and virtual damping parameters are adjusted, and the admittance parameter values in the non-vibration and critical vibration states are recorded. The system state is divided into a vibration interval and a non-vibration interval. As Figure 4 shown, it is set that the system force control dragging speed adjustment interval is within the non-vibration interval.

[0094] Collect the external force when the robot force control vibrates and the displacement, speed, and acceleration of the robot output by the admittance control model, determine the maximum position, speed, and acceleration at which the robot vibrates, select the sine function adjustment as the external force, calculate the displacement, speed, and acceleration of the robot under different admittance parameters, judge whether the robot vibrates, and determine the admittance coefficient variation interval that satisfies the non-vibration state.

[0095] Step 8: When it is manually judged that the distance between the aircraft flap sample 10 and the assembly object 9 is small, or when the set safety distance is triggered by the lidar, adjust the robot compliant assembly system to the slow force control mode.

[0096] Further, in Step 7 and Step 8, to facilitate the operator to start and stop the system, the operator's intention is recognized at all times, which can be expressed as:

[0097] When the acceleration output by the admittance model is not 0 and the acceleration direction is the same as the speed direction, then accelerate;

[0098] When the output acceleration and speed are both 0, or the external force is 0, then stop;

[0099] In other cases, when the external force is not 0, the operation intention is to decelerate.

[0100] That is:

[0101]

[0102] In the formula, F is the external force received after gravity compensation; and are the speed and acceleration in the i-axis direction respectively. i is the degrees of freedom of the translation and rotation of the three directions x, y, and z at the robot end, and the acceleration and deceleration of each axis operate independently.

[0103] Step 9: Slowly drag the aircraft flap sample 10 close to the assembly position, and focus on adjusting the slide rail of the aircraft flap sample 10 to meet the assembly requirements. It is required that the slide rail coincides with the end face of the assembly track and the center lines are coaxial.

[0104] Furthermore, to meet the pre-assembly requirements for the spatial pose of the aircraft flap sample 10, according to the pose adjustment requirements, the selectable axis force control function is enabled, which can set a certain axis or several axes to enable force control, and the remaining axes remain stationary.

[0105] In addition, the stepping adjustment function of the robot compliant control system is enabled, and the single-step force control end adjustment amount can be set according to the adjustment distance. The single-step adjustment amount change range of the translation axis is [0.005 mm, 1 mm], and the single-step adjustment amount change range of the rotation axis is [0.001°, 0.1°], and it is still possible to achieve independent movement of a certain axis or several axes.

[0106] Step 10: Set the upper and lower thresholds [F B , F T of the system force control trigger, so that when the force at the end of the system is within the upper and lower thresholds, the pose can be adjusted online, and further realize the compliant assembly of dragging the aircraft flap sample 10.

[0107] Among them, a floating structure is provided at the connection part of the slide rail of the aircraft flap sample 10, and the change range of its compression or tensile force is [F S1 , F S2 , which can avoid causing damage to the aircraft flap 7 and the assembly object 9 due to excessive resistance during the assembly process. Further, the lower threshold F B of the force control trigger is determined by the minimum compression force of the floating mechanism. When the floating mechanism receives compression or tensile force, the assembly system can adjust according to the direction of the acting force; the upper threshold F T of the force control trigger is determined by the maximum compression or tensile force of the floating mechanism to avoid damage to the system floating mechanism when it receives excessive acting force. Its implementation logic is as follows:

[0108]

[0109] In the formula, is the external force received by the i-th axis after gravity compensation; i is the degrees of freedom of translation and rotation in the x, y, and z directions at the end of the robot, and force control operations can be performed within the allowable force control range in each direction.

[0110] Step 11: Assemble the aircraft flap sample 10 to the predetermined position in the manner of Step 10, complete the assembly of the flap sample, and record the robot motion trajectory L1 and the force information after gravity compensation of the force sensor during this process.

[0111] Step 12: Using the same force-controlled assembly method as in Step 10, move the aircraft flap sample 10 from the pre-assembly position to the assembly position, and record the force information and the robot's motion trajectory L2 during the removal process.

[0112] Step 13: Taking the theoretical trajectory L of the aircraft flap 7 assembly E as the target, fit and optimize the motion trajectories L1 and L2 during the assembly process to obtain the expected motion trajectory during the robot's compliant assembly at the current spatial position. .

[0113] Among them, L1 and L2 are the motion trajectory information in the robot's base coordinate system {B}, and L E is a theoretical trajectory at an uncertain position in space. During the fitting process, the trajectory L E is defined in the robot's base coordinate system {B} to obtain the assembly trajectory with the smallest difference from the two trajectories L1 and L2. .

[0114]

[0115] Wherein:

[0116]

[0117] In the formula, T is the conversion relationship between the theoretical assembly trajectory L E and the fitted assembly trajectory , which includes the rotation matrix R and the translation matrix M.

[0118] Step 14: Move the robot compliant assembly system to the storage rack of the aircraft flap sample 10, stop the force control and release the fixture to complete the placement of the aircraft flap sample 10. At the same time, move the robot compliant system to clamp the aircraft flap 7 according to the moving position, and repeat Steps 4 to 9 to move the aircraft flap 7 component to the pre-assembly position.

[0119] Step 15: The robot compliant assembly system uses as the expected motion trajectory and starts the compliant assembly control based on the expected motion trajectory.

[0120] Furthermore, no manual participation is required in this process. The robot assembly system automatically performs the assembly, and during the movement according to the predetermined trajectory, the force control is turned on so that the robot can adapt to the assembly force changes caused by the flap clamping error and the trajectory fitting error.

[0121] At the same time, process the force information collected in Steps 10 and 11, extract the force information perpendicular to the predetermined trajectory, average it and set it as the lower threshold of the force control in this direction in Step 15, that is, since the track in this direction is in real-time contact with the assembled part, the force in this direction is allowed.

[0122] Step 16: After the assembly in Step 15 is in place, stop the automatic assembly and turn off the force control. The robot gripper releases and returns to the initial position, completing the assembly of the aircraft flap 7.

[0123] In practical applications, the operation logic of the control method disclosed in the above embodiments can be written as a set of executable instructions. The executable instructions are written into a storage medium and run on an electronic device. More specific examples of the computer-readable storage medium mentioned in this embodiment may include, but are not limited to: electrical connections with one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the above. The computer-readable storage medium may include a data signal propagated in a baseband or as part of a carrier wave, in which the readable program code is carried. Such a propagated data signal may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. The readable signal medium may also be any readable medium other than the readable storage medium, which can send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0124] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as a limitation of the present invention itself. Various changes may be made in its form and details without departing from the spirit and scope of the present invention defined by the appended claims.

Claims

1. A robot compliant assembly control method for an aircraft flap component, characterized in that, It includes the following steps: Step 1: Move the AGV automatic guided vehicle to the aircraft flap assembly station, and determine that the position of the product bracket equipped with the aircraft flap and the aircraft flap sample meets the assembly space; Step 2: Determine the state of the end fixture of the industrial robot, establish the robot base coordinate system {B}, the flange coordinate system {F}, and the force sensor coordinate system {S}, adjust the pose of the industrial robot, collect multiple groups of robot pose information and the corresponding end force sensor information in a stable state, and calculate the gravity, center of gravity of the end fixture, and the zero drift and temperature drift values of the force sensor; Step 3: Perform gravity compensation for different poses during the movement of the industrial robot according to the calculated gravity, center of gravity of the end fixture, and the zero drift and temperature drift values of the force sensor; Step 4: The operator drags the end fixture to near the product bracket; Step 5: The end fixture clamps the aircraft flap sample from the product bracket; Step 6: The six-axis force sensor collects the gravity and center of gravity of the currently clamped aircraft flap sample, and determines whether the current clamping environment meets the process requirements. If not, readjust the clamping position until the process requirements are met; Step 7: When the distance between the end of the industrial robot and the assembly object is greater than or equal to the safety distance, adjust to the fast force control mode, and control the industrial robot to the flap pre-assembly space position at the speed in the fast force control mode; Step 8: When the distance between the end of the industrial robot and the assembly object is less than the safety distance, adjust to the slow force control mode; Step 9: The operator drags the aircraft flap sample close to the assembly position at the speed in the slow force control mode; Step 10, set the force control trigger upper and lower thresholds of the robotic compliant assembly system for aircraft flap components [F B , F T , specifically including: Set the upper and lower thresholds for force control trigger of the robotic compliant assembly system for aircraft flap components [F B , F T , specifically including: A floating structure is provided at the sliding rail connection part of the aircraft flap sample, and the change range of its compression or tensile force is [F S1 , F S2 ; Force control trigger lower threshold F B Determined by the minimum compression force of the floating mechanism; Force control trigger upper threshold F T Determined by the maximum compression or tensile force of the floating mechanism; The implementation logic is as follows: ； In the formula, is the external force received after the gravity compensation of the i-th axis; i is the degrees of freedom of the translation and rotation of the robot end in the three directions of x, y, and z. Step 11. Under the condition that the force control triggers the upper and lower thresholds [F B , F T , assemble the aircraft flap sample to the predetermined position, complete the assembly of the flap sample, and record the motion trajectory L1 and the force information after the gravity compensation of the force sensor; Step 12. Under the condition that the force control triggers the upper and lower thresholds [F B , F T , move the aircraft flap sample from the assembly predetermined position to the assembly position, and at the same time record the force information and the motion trajectory L2 of the robot during the moving process; Step 13: Using the theoretical trajectory L of the aircraft flap assembly E as the target, optimize the fitting of the motion trajectories L1 and L2 during the assembly process to obtain the expected motion trajectory during the compliant assembly of the robot at the current spatial position ; The motion trajectories L1 and L2 are the motion trajectory information in the robot base coordinate system {B}, and L E is a theoretical trajectory at an uncertain position in space. During the fitting process, the trajectory L E is defined in the robot base coordinate system {B} to obtain the assembly trajectory with the smallest difference from the two trajectories L1 and L2 : ； Step 14: The AGV automatic guided vehicle moves to the aircraft flap sample storage rack, releases the end fixture, puts the aircraft flap sample back on the product bracket, and at the same time clamps the aircraft flap. Repeat steps 4 to 9 to move the aircraft flap to the pre-assembly position; Step 15: The robotic compliant assembly system for aircraft flap components starts the compliant assembly control based on the desired motion trajectory , and starts the compliant assembly control based on the desired motion trajectory; Step 16: After assembling in place according to step 15, stop the automatic assembly, release the end fixture, and return to the initial position to complete the aircraft flap assembly.

2. The robot compliant assembly control method for an aircraft flap component according to claim 1, wherein, In step 2, the origin of the robot base coordinate system {B} is located at the center point of the base; the origin of the flange coordinate system {F} is located at the center point of the flange; the origin of the force sensor coordinate system {S} is located at the center of the force sensor; The direction of the designed force sensor coordinate system {S} coincides with that of the flange coordinate system {F}, with only translation in the z direction, and the x, y, and z directions of the end force sensor information coincide with the x S , y S , z S respectively.

3. The robot compliant assembly control method for aircraft flap components according to claim 2, characterized in that The relationship between the data collected by the six-axis force sensor and the weight of the suspended load is: ； where G x , G y , G z , T Gx , T Gy and T Gz are the components of the load gravity in the x, y, and z directions and the torques in the force sensor coordinate system {S}; F x , F y , F z , T x , T y and T z are the six - dimensional force information collected by the force sensor respectively; F x0 、F y0 、F z0 、T x0 、T y0 、T z0 are the zero drift value and temperature drift value of the force sensor; The temperature drift value of the six-axis force sensor and the ambient temperature C t The relationships are successively F x0 (C t ), F y0 (C t ), F z0 (C t ), T x0 (C t ), T y0 (C t ), T z0 (C t ). Then the zero drift value of the six-axis force sensor satisfies: ； In the formula, , , , , , are the zero drift values of the forces in the three directions of x, y, and z of the six-axis force sensor and the torques in the rotational directions around the three axes, respectively; The position (x g , y g , z g ) of the load gravity, moment and load center of gravity in the force sensor coordinate system {S} satisfies: 。 4. The robot compliant assembly control method for an aircraft flap component according to claim 1, wherein In steps 7 and 8, variable admittance control is used to switch and adjust between the fast force control mode and the slow force control mode; The parameter change range of variable admittance control is the experimental calibration result. Among them, the virtual stiffness coefficient is zero, adjust the virtual mass and virtual damping parameters, record the admittance parameter values in the non-vibration and critical vibration states, divide the system state into the vibration interval and the non-vibration interval, and set the system force control drag speed adjustment interval in the non-vibration interval; In steps 7 and 8, continuously identify the operator's intention: When the acceleration output by the admittance model is not 0 and the acceleration direction is the same as the speed direction, then accelerate; When both the output acceleration and the speed are 0, or the external force is 0, then stop; In other cases, when the external force is not 0, the operation intention is to decelerate; The expression of this process is as follows: ； Where F is the external force received after gravity compensation; and are the velocity and acceleration in the i-axis direction respectively, where i represents the degrees of freedom of translation and rotation in the x, y, and z directions at the end of the robot, and the acceleration and deceleration of each axis operate independently.

5. The robot compliant assembly control method for aircraft flap components according to claim 1, wherein In step 9, the single - time force - controlled end adjustment amount is set according to the adjustment distance. The variation range of the single - step adjustment amount of the translation axis is [0.005 mm, 1 mm], and the variation range of the single - step adjustment amount of the rotation axis is [0.001°, 0.1°].

6. A robotic compliant assembly system for an aircraft flap component, characterized in that It is used to execute the robot compliant assembly control method for aircraft flap components as described in any one of claims 1 to 5; The robot compliant assembly system for aircraft flap components includes: A product bracket, which is set at a predetermined position within a predetermined working space; an aircraft flap and an aircraft flap sample are placed on the product bracket; An assembly object, which is set at a predetermined position within a predetermined working space; An AGV (Automated Guided Vehicle) automatic guided vehicle, which moves within a predetermined working space; An industrial robot, which is set on the AGV automatic guided vehicle; the end fixture of the industrial robot clamps the aircraft flap sample; the industrial robot can reach the product bracket and the assembly object under the movement of the AGV automatic guided vehicle; A six - dimensional force sensor, which is installed between the flange of the industrial robot and the end fixture and can sense the external force information from the end fixture, the aircraft flap, and the aircraft flap sample.

7. An electronic device, characterized in that, It includes: A processor, a memory, a communication interface, and a communication bus. The processor, the memory, and the communication interface complete mutual communication through the communication bus; The memory is used to store a number of executable instructions, and the executable instructions cause the processor to execute the robot compliant assembly control method for aircraft flap components as described in any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, A number of executable instructions are stored in the storage medium. When the executable instructions run on an electronic device, the electronic device is caused to execute the robot compliant assembly control method for aircraft flap components as described in any one of claims 1 to 5.

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