Robot, robot control device, robot control method, and program

Abstract

To guide a plurality of feature sections provided in an assembled component to each corresponding target position set to a component to be assembled.SOLUTION: A control device 60 includes: a first reference point correction section 62 which compares states of a plurality of studs in a state where a panel is gripped by a robot arm with states of the studs when teaching data is obtained so as to correct teaching data of a first reference point defined corresponding to each stud and obtain first correction reference points; a target reference point setting section 64 which sets one of the plurality of first correction reference points to a target reference point on the basis of a preset order; and an arm control section 65 which controls the robot arm so as to make the target reference point coincide with a second reference point set corresponding to a through hole of an inner liner. The target reference point setting section 64 sets a first correction reference point in the next order as the target reference point when it is determined that the target reference point coincides with the corresponding second reference point.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present disclosure relates to a robot, a robot control device, a robot control method, and a program.

Background Art

[0002] For example, there has been proposed an assembly method in which an assembly part whose shape is recognized in three dimensions is gripped by a robot, and the assembly part is assembled to a part to be assembled by handling a robot arm.

[0003] For example, Patent Document 1 proposes a method of assembling a screw, which is an assembly part, into a screw hole provided in a part to be assembled. More specifically, Patent Document 1 discloses an assembly device that controls the operation of a working unit so as to correspond a TCP gripping position as a first reference position corresponding to a first reference point of an assembly part defined in three-dimensional model data, and a TCP assembly position as a second reference position corresponding to a second reference point of the assembly part defined in the three-dimensional model data of the part to be assembled.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Patent Document 1 describes a method of assembling a screw, which is an assembly part, into a screw hole provided in a part to be assembled, but this method is merely a simple fitting operation of fitting one screw into one screw hole. Therefore, it was difficult to handle complex assembly tasks, such as when an assembly part has multiple feature parts (e.g., protrusions such as screws and stud bolts), and each of these feature parts is guided to a corresponding target position (e.g., an opening such as a screw hole or through hole) provided in the assembly part.

[0006] This disclosure has been made in view of these circumstances and aims to provide a robot, a robot control device, a robot control method, and a program that can guide multiple feature parts provided on an assembly part to their respective corresponding target positions set on the assembly part. [Means for solving the problem]

[0007] A first aspect of the present disclosure is a robot control device for gripping an assembly part having N (N is an integer of 2 or more) first feature parts with a robot arm and assembling it to an assembly part having N second feature parts corresponding to each of the first feature parts, comprising: a first reference point correction unit that corrects the teaching data of M first reference points defined corresponding to each of the M first feature parts by comparing the state of M (M is an integer of 2 or more and less and less than or equal to N) first feature parts when the assembly part is gripped by the robot arm with the state of M first feature parts when teaching data is obtained, thereby obtaining M first corrected reference points; a target reference point setting unit that sets one of the M first corrected reference points as a target reference point based on a preset order; and an arm control unit that controls the robot arm so that the target reference point matches a second reference point set corresponding to the second feature part of the assembly part, The robot arm is controlled by the arm control unit, If it is determined that the aforementioned target reference point coincides with the corresponding second reference point, The aforementioned target reference point setting unit is This robot control device sets the first correction reference point in the following order as the target reference point.

[0008] A second aspect of this disclosure is a robot equipped with the robot control device described above.

[0009] A third aspect of this disclosure is a robot control method for gripping an assembly part having N (N is an integer of 2 or more) first feature parts with a robot arm and assembling it to an assembly part having N second feature parts corresponding to each of the first feature parts, comprising the steps of: obtaining M first corrected reference points by correcting the teaching data of M first reference points defined corresponding to each of the M first feature parts by comparing the state of M (M is an integer of 2 or more and less and less than or equal to N) first feature parts when the assembly part is gripped by the robot arm with the state of M first feature parts when teaching data is obtained; setting one of the M first corrected reference points as a target reference point based on a preset order; and controlling the robot arm so that the target reference point matches a second reference point set corresponding to the second feature part of the assembly part. By controlling the robot arm, This robot control method involves a computer performing the following steps: when it is determined that the target reference point coincides with the corresponding second reference point, the computer sets the first correction reference point in the following order as the target reference point.

[0010] A fourth aspect of this disclosure is a program for causing a computer to function as the robot control device described above. [Effects of the Invention]

[0011] The robot, robot control device, robot control method, and program described herein have the effect of guiding multiple feature parts provided on an assembly part to their respective corresponding target positions set on the assembly part. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic perspective view showing a combustor according to one embodiment of the present disclosure. [Figure 2] This is a schematic cross-sectional view of the combustor at the cutting line II-II in Figure 1. [Figure 3] This is a schematic perspective view of an outer combustor according to one embodiment of the present disclosure. [Figure 4]Schematic perspective view of an inner combustor according to an embodiment of the present disclosure. [Figure 5] Schematic perspective view of an inner liner before a panel according to an embodiment of the present disclosure is attached. [Figure 6] Schematic perspective view of a panel according to an embodiment of the present disclosure. [Figure 7] Schematic perspective view of a bulkhead. [Figure 8] Diagram showing a schematic configuration of a robot according to an embodiment of the present disclosure. [Figure 9] Functional block diagram showing an example of functions provided by a control device according to an embodiment of the present disclosure. [Figure 10] Diagram showing an example of two-dimensional panel master data according to an embodiment of the present disclosure. [Figure 11] Diagram for explaining a first reference point according to an embodiment of the present disclosure. [Figure 12] Diagram showing an example of two-dimensional liner master data according to an embodiment of the present disclosure. [Figure 13] Diagram for explaining a second reference point according to an embodiment of the present disclosure. [Figure 14] Diagram for explaining the deviation of the gripping position of the end effector when gripping a panel. [Figure 15] Diagram for explaining the deviation of the gripping angle of the end effector when gripping a panel. [Figure 16] Diagram for explaining the deviation of the gripping angle of the end effector when gripping a panel. [Figure 17] Flowchart showing an example of the processing procedure of a robot control method according to an embodiment of the present disclosure. [Figure 18] Flowchart showing an example of the processing procedure of a robot control method according to an embodiment of the present disclosure. [Figure 19] Schematic diagram for explaining the switching timing of the first reference point when assembling a panel to an inner liner. [Figure 20] This is a schematic diagram illustrating the switching timing of the first reference point when assembling the panel to the inner liner. [Figure 21] This is a schematic diagram illustrating the switching timing of the first reference point when assembling the panel to the inner liner. [Figure 22] This is a schematic diagram illustrating the switching timing of the first reference point when assembling the panel to the inner liner. [Figure 23] This is a diagram illustrating the definition of the first reference point in relation to other aspects of this disclosure. [Modes for carrying out the invention]

[0013] Hereinafter, an embodiment of the robot, robot control device, robot control method, and program relating to this disclosure will be described with reference to the drawings. In the following description, an example will be given of applying the robot, robot control device, robot control method, and program relating to this disclosure to a part of the assembly process of the combustor 1, but the invention is not limited to this example. That is, the robot, robot control device, robot control method, and program relating to this disclosure can be broadly applied to assembly work that guides multiple feature parts provided on an assembly part (for example, protrusions such as screws and stud bolts) to corresponding target positions set on the assembly part (for example, openings such as screw holes and through holes).

[0014] [Basic Configuration of Combustors] The basic configuration of combustor 1 will now be explained. Combustor 1 is a device that defines a combustion chamber CC in a turbofan engine, for example, mounted on an aircraft, where compressed air and fuel are mixed and burned to generate high-temperature combustion gases that rotate a turbine.

[0015] Figure 1 is a schematic perspective view showing a combustor 1 according to one embodiment of the present disclosure, and Figure 2 is a schematic cross-sectional view of the combustor 1 along the cutting line II-II in Figure 1. As shown in Figures 1 and 2, the combustor 1 comprises an outer combustor 10, an inner combustor 20, a bulkhead 30 (see Figure 2), and a hood 40. The combustion chamber CC is defined by the outer combustor 10, the inner combustor 20, and the bulkhead 30.

[0016] Figure 3 is a schematic perspective view of the outer combustor 10. As shown in Figure 3, the outer combustor 10 is a cylindrical component as a whole. The outer combustor 10 has an outer liner 11 and a plurality of outer liner panels 12 (hereinafter simply referred to as "panels 12") provided on the inner circumferential surface of the outer liner 11.

[0017] The outer liner 11 is a metal component, for example, a cylindrical shape with axis X0 as its central axis, and is made of sheet metal. The inner circumferential surface of the outer liner 11 facing the combustion chamber CC is divided by a plurality of panels 12 and is covered almost entirely. The panels 12 thermally protect the outer liner 11 from combustion gases.

[0018] As shown in Figures 2 and 3, each panel 12 is an arc-shaped component corresponding to the shape of various parts of the outer circumferential surface of the outer liner 11, and is constructed, for example, by applying a heat-resistant treatment (e.g., ceramic coating) to the surface of a cast plate material. Each panel 12 is provided with a plurality of studs 12a that protrude outward from its outer periphery. Each panel 12 is fixed to the outer liner 11 by inserting a stud 12a through a hole formed in the outer liner 11, and by attaching a washer 12b and a nut 12c to the stud 12a protruding from the hole.

[0019] On the circumferential surface (edge ​​portion) of one end of the outer liner 11, for example, multiple through holes 11a are formed at approximately equal angular intervals along the circumferential direction with axis X0 as the central axis. This edge portion is not covered by the panel 12. The outer wall portion 32 of the bulkhead 30 (see Figure 7) is fitted into this edge portion (for example, by interference fit).

[0020] Figure 4 is a schematic perspective view of the inner combustor 20. As shown in Figure 4, the inner combustor 20 is a cylindrical component as a whole. The inner combustor 20 has, for example, an inner liner 21 and a plurality of inner liner panels 22 (hereinafter simply referred to as "panels 22") provided on the outer circumferential surface of the inner liner 21. As shown in Figures 1 and 2, the inner combustor 20 is positioned inside the outer combustor 10 in the combustor 1 after assembly.

[0021] As shown in Figure 4, the inner liner 21 is a metal component, for example, a cylindrical shape with axis X1 as its central axis, and is made of sheet metal. The outer surface of the inner liner 21 facing the combustion chamber CC is divided by a plurality of panels 22 and is covered almost entirely. The panels 22 thermally protect the inner liner 21 from combustion gases.

[0022] Figure 5 is a schematic perspective view of the inner liner 21 before the panel 22 is attached, and Figure 6 is a schematic perspective view of the panel 22. As shown in Figure 5, multiple through holes 24 are formed on the circumferential surface of the inner liner 21 at approximately equal angular intervals along the circumferential direction with axis X1 as the central axis. Note that some of the through holes 24 are not shown in Figure 5.

[0023] As shown in Figure 6, the panel 22 is an arc-shaped component corresponding to the shape of various parts of the outer circumferential surface of the inner liner 21; in other words, it is a component with curvature, and is constructed, for example, by applying a heat-resistant treatment (e.g., ceramic coating) to the surface of a cast plate. Multiple stud bolts (hereinafter referred to as "studs") 23 protruding inward are provided on the inner circumferential surface of the panel 22. The studs 23 are provided at intervals along the curvature direction of the panel 22. The studs 23 of the panel 22 are inserted through holes 24 (see Figure 5) formed in the inner liner 21. Then, as shown in Figure 2, washers 25 and nuts 26 are attached to the studs 23 protruding from the through holes 24 from the inside of the inner liner 21, thereby fixing the panel 22 to the inner liner 21.

[0024] Furthermore, as shown in Figure 4, the through-holes 27 provided in the edge portion of the inner liner 21 are not covered by the panel 22. The inner wall portion 33 of the bulkhead 30 is fitted into this edge portion (for example, by interference fit). Note that in Figure 4, some of the through-holes 27 and studs 23 are omitted from the illustration.

[0025] Figure 7 is a schematic perspective view of the bulkhead 30. As shown in Figure 1, the bulkhead 30 is an annular component with axis X0 as its central axis, installed to close an annular opening formed between one end of the outer combustor 10 and one end of the inner combustor 20. As shown in Figure 7, the bulkhead 30 has an annular bottom 31, an outer wall portion 32 erected from the outer peripheral edge of the bottom 31, and an inner wall portion 33 erected from the inner peripheral edge of the bottom 31. The outer wall portion 32 is fitted into the outer liner 11. The inner wall portion 33 is fitted into the inner liner 21.

[0026] Multiple through holes 32a are formed in the outer wall portion 32 at approximately equal angular intervals along the circumferential direction with axis X2 as the central axis. The angular interval between the through holes 32a is equal to the angular interval between the through holes 11a (see Figure 3). Therefore, when the bulkhead 30 is fitted into the outer liner 11, the positions of each through hole 32a and each through hole 11a can be made to coincide in the circumferential direction.

[0027] Multiple through holes 33a are formed in the inner wall portion 33 at approximately equal angular intervals along the circumferential direction with axis X2 as the central axis. The angular spacing between the through holes 33a is equal to the angular spacing between the through holes 27 (see Figure 4). Therefore, when the bulkhead 30 is fitted into the inner liner 21, the positions of each through hole 32a and each through hole 27 can be aligned in the circumferential direction.

[0028] As shown in Figure 2, in the assembled combustor 1, the outer wall portion 32 of the bulkhead 30 is in contact with the inner circumferential surface of the outer combustor 10, and the inner wall portion 33 of the bulkhead 30 is in contact with the inner circumferential surface of the inner combustor 20.

[0029] The bulkhead 30 is fixed to the outer combustor 10 and the inner combustor 20 by bolts (not shown) inserted through the outer wall portion 32 and the outer combustor 10 being screwed into nut plates provided on the outer wall portion 32, and by bolts (not shown) inserted through the inner wall portion 33 and the inner combustor 20 being screwed into nut plates provided on the inner wall portion 33. As shown in Figures 1 and 2, the hood 40 is an annular component installed to cover the bulkhead 30.

[0030] The combustor 1, configured as described above, functions as follows: In other words, compressed air and fuel are supplied to the combustion chamber CC and mixed there. This air-fuel mixture is then burned in the combustion chamber CC to generate high-temperature combustion gases that rotate the turbine.

[0031] [Assembly process for panel 22] The robot, robot control device, robot control method, program, and robot according to this embodiment are applied to the step of assembling the panel 22 (see Figure 6) to the inner liner 21 (see Figure 5) in the assembly process of the combustor 1 described above. Specifically, this method is applied to a process in which a panel (assembly part) having multiple studs (first feature part) is grasped by a robot arm and assembled onto an inner liner (assembly part) having multiple through holes 24 (second feature part) corresponding to each stud.

[0032] [Robot Configuration] Figure 8 is a diagram showing a schematic configuration of a robot 50 according to one embodiment of the present disclosure. As shown in Figure 8, the robot 50 comprises a robot arm 52 and an end effector 52a attached to the tip of the robot arm 52. Furthermore, the robot 50 comprises a control device (robot control device) 60 that controls the robot 50.

[0033] Furthermore, for example, the robot arm 52 is equipped with a force sensor 53. For example, the force sensor 53 is located between the tip of the robot arm 52 and the end effector 52a. The force sensor is, for example, a 6-axis force sensor, and detects the force (reaction force) and moment that the panel receives from the inner liner 21 when the studs 23 of the panel 22 come into contact with the inner liner 21. The detected values ​​from the force sensor are output to the control device 60.

[0034] The robot 50 may also be equipped with a vision sensor 54. The vision sensor 54 is used for acquiring shape data of the panel 22, acquiring shape data of the inner liner 21, and detecting the position of the panel 22 during the process of attaching it to the inner liner 21. For example, the vision sensor 54 takes images of the panel 22 to be attached while it is being held by the end effector 52a, and acquires 2D and 3D data of the panel 22. It also takes images of the inner liner 21 to which the panel 22 will be attached while it is fixed, and acquires image data of the inner liner 21. The vision sensor 54 may be a 2D sensor or a 3D sensor. In this embodiment, the vision sensor 54 is equipped with both 2D and 3D sensors.

[0035] The two-dimensional and three-dimensional data acquired by the vision sensor 54 are output to the control device 60. The installation location of the vision sensor 54 is not particularly limited. It can be installed in an appropriate location depending on the application. In addition, multiple vision sensors 54 may be installed. The robot 50 is, for example, a 6-axis driven robot. By controlling the angle of each joint (link), the robot 50 can guide the end effector 52a, which is provided at the tip of the robot arm 52, to a desired position.

[0036] The controller 60 includes, for example, a CPU (Central Processing Unit: processor), main memory, secondary storage (memory), etc. Furthermore, the controller 60 may also include a communication unit for sending and receiving information with other devices.

[0037] Main memory consists of writable memory such as cache memory and RAM (Random Access Memory), and is used as a work area for reading CPU executable programs and writing processing data by executable programs. Secondary storage devices are non-transitory computer-readable storage media. Examples of secondary storage devices include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memory.

[0038] The series of processes required to implement the various functions described later are stored in secondary memory in the form of a program, for example. The CPU reads this program into main memory and performs information processing and calculations to realize the various functions. The program may be pre-installed in secondary memory, provided stored on a computer-readable storage medium, or distributed via wired or wireless communication. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memory.

[0039] Figure 9 is a functional block diagram showing an example of the functions of the control device 60. As shown in Figure 9, the control device 60 includes, for example, a storage unit 61, a first reference point correction unit 62, a second reference point correction unit 63, a target reference point setting unit 64, and an arm control unit 65.

[0040] The memory unit 61 stores pre-created teaching data for the robot 50. For example, the memory unit 61 stores various data as teaching data for guiding and fitting each of the multiple studs (feature parts) 23 provided on the panel 22, which is an assembly part, into the corresponding through holes 24 provided on the inner liner 21, which is an assembly part.

[0041] The teaching data includes various data used when teaching robot 50. For example, the teaching data includes two-dimensional data (hereinafter referred to as "two-dimensional panel master data") and three-dimensional data (hereinafter referred to as "three-dimensional panel master data") of the end effector 52a that grasps panel 22 during teaching. Figure 10 shows an example of 2D panel master data.

[0042] The teaching data includes position data of multiple first reference points defined on panel 22. Figure 11 is a diagram illustrating the first reference points. The configuration of the end effector 52a shown in Figure 11 is an example and is not limited thereto. As shown in Figure 11, in this embodiment, the first reference point is defined at the tip of the stud 23. In this embodiment, as an example, two first reference points TCP1a and TCP1b are defined. For example, the first reference point TCP1a is defined at the tip of the stud 23a provided in one end region in the circumferential direction (longitudinal direction) of the master panel 22r, and the first reference point TCP1b is defined at the tip of the stud 23b provided in the central region of the master panel 22r. The first reference point is, for example, the TCP (Tool Center Position), and is defined, for example, by a position component (XYZ coordinate values ​​in the working coordinate space) and a direction component (XYZ components).

[0043] The teaching data includes two-dimensional data (hereinafter referred to as "two-dimensional liner master data") and three-dimensional data (hereinafter referred to as "three-dimensional liner master data") with the inner liner 21 fixed during teaching. Figure 12 shows an example of 2D liner master data.

[0044] The teaching data includes position data for multiple second reference points TCP2a and TCP2b located on the inner liner 21 side, corresponding to the first reference points TCP1a and TCP1b, respectively. Figure 13 is a diagram illustrating the second reference point. In Figure 13, the configuration of the inner liner 21 is shown in a simplified manner. As shown in Figure 13, in this embodiment, the second reference points TCP2a and TCP2b are provided, for example, on the side of the inner liner 21 opposite to the side into which the panel is fitted. In other words, the second reference points TCP2a and TCP2b are defined on the inner circumferential surface side of the inner liner 21. The second reference point, like the first reference point, is the TCP (Tool Center Position) and is defined, for example, by a position component (XYZ coordinate values ​​in the work coordinate space) and a direction component (XYZ components).

[0045] Furthermore, the teaching data includes control data for aligning the first reference point TCP1a with the second reference point TCP2a, and control data for aligning the first reference point TCP1b with the second reference point TCP2b. The control data is defined, for example, by parameters indicating the rotation angles of each joint of the robot arm 52.

[0046] The first reference point correction unit 62 (see Figure 9) compares the state of studs 23a and 23b (e.g., position and direction) when the panel 22 is gripped by the end effector 52a with the state of studs 23a and 23b (e.g., position and direction) when teaching data is obtained, and corrects the teaching data of the first reference points TCP1a and TCP1b defined corresponding to each of the studs 23a and 23b to obtain the first corrected reference points TCP1a' and TCP1b'.

[0047] For example, panel 22 has individual variations (manufacturing tolerances). Such individual variations include, for example, errors in the curvature of the panel, errors in the placement of the studs 23, and errors in the orientation of the studs 23. Furthermore, the position and orientation of studs 23a and 23b also change due to misalignment of the grip of the end effector 52a during assembly. For example, as shown in Figures 14 to 16, the state of studs 23a and 23b differs from the state of studs 23a and 23b when the teaching data was obtained, depending on the misalignment of the gripping position and gripping angle of the end effector 52a when gripping panel 22.

[0048] The control data included in the teaching data is intended to move the first reference points TCP1a and TCP1b defined in the teaching data to their corresponding second reference points TCP2a and TCP2b, respectively. Therefore, if the individual differences or the gripping misalignment of the end effector 52a are greater than the preset tolerance, it will not be possible to guide each stud 23 of the panel 22 to the corresponding through-hole 24 of the inner liner 21. Therefore, the first reference point correction unit 62 corrects the teaching data of the first reference points TCP1a and TCP1b based on, for example, the state of the studs 23a and 23b of the panel 22 to be assembled.

[0049] For example, the first reference point correction unit 62 acquires 2D and 3D data while the panel 22 to be installed is being held by the end effector 52a. Then, it compares this acquired 2D and 3D data with the panel 2D master data and panel 3D master data stored in the storage unit 61 to calculate the positional and directional deviations of the studs 23a and 23b. Then, using the calculation results, it corrects the first reference points TCP1a and TCP1b to obtain the first corrected reference points TCP1a' and TCP1b'.

[0050] In this case, if the amount of displacement is within the allowable value, there is a high probability that the panel 22 can be fitted into the through hole 24 by force control described later, so the correction of the first reference point may be omitted.

[0051] The second reference point correction unit 63, similar to the first reference point correction unit 62, compares the state of the through holes 24a and 24b when the inner liner 21 is fixed with the state of the through holes 24a and 24b when teaching data is obtained, thereby correcting the teaching data of the second reference points TCP2a and TCP2b defined in correspondence with the through holes 24a and 24b, and obtaining the second corrected reference points TCP2a' and TCP2b'.

[0052] For example, the second reference point correction unit 63 acquires 2D and 3D data with the inner liner 21, which is to be installed, fixed in place. Then, it compares these acquired 2D and 3D data with the liner 2D master data and liner 3D master data stored in the memory unit 61 to calculate the positional deviation of the through holes 24a and 24b. Then, using the calculation results, it corrects the second reference points TCP2a and TCP2b to obtain the second corrected reference points TCP2a' and TCP2b'. If the amount of displacement is within the allowable limit, there is a high probability that the panel 22 can be fitted into the through hole 24 by force control as described later, so the correction of the second reference point may be omitted.

[0053] In this embodiment, the two-dimensional and three-dimensional data described above are acquired using, for example, a vision sensor 54 (see Figure 8), but are not limited to this. That is, any known sensor that can detect the amount of displacement described above can be appropriately used.

[0054] The target reference point setting unit 64 sets one of the multiple first correction reference points TCP1a', TCP1b' as the target reference point based on a predetermined order. The order in which the target reference points are set is from one end region of the panel 22 toward the central region. In this embodiment, the target reference points are set in the order of first correction reference points TCP1a', TCP1b'. When the target reference point setting unit 64 detects that the target reference point matches the corresponding second reference point, it sets the next first correction reference point in the following order as the target reference point.

[0055] The arm control unit 65 controls the robot arm 52 so that the target reference point matches the corresponding second reference point set on the inner liner 21. Specifically, the arm control unit 65 guides the end effector 52a to the desired position and matches the target reference point to the corresponding second correction reference point by controlling the angles of each joint of the robot 50 based on the control data included in the teaching data.

[0056] The arm control unit 65 performs force control when the reaction force generated by the panel 22 (specifically, the stud 23) contacting the inner liner 21 exceeds a preset first threshold when the target reference point is aligned with the second reference point. This reaction force can be obtained from the value detected by the force sensor 53.

[0057] This force control involves, for example, controlling the robot arm 52 to push the panel 22 into the inner liner 21 while swinging it in a preset swing direction. The swing direction may be one direction or a combination of multiple directions. The pushing force at this time is adjusted to a pressing force that does not cause deformation or other problems to the panel 22 or the inner liner 21.

[0058] When force control is performed, the arm control unit 65 determines that the stud 23 with the set target reference point has entered the corresponding through hole 24 when the reaction force falls below a preset second threshold, and that the target reference point coincides with the second reference point.

[0059] The arm control unit 65 performs force control until the reaction force falls below a preset second threshold, or until a preset period of time has elapsed, or until the number of oscillations reaches a preset number. If the reaction force does not fall below the second threshold even after the predetermined period of force control or the number of oscillations has reached a predetermined number, the robot control is stopped and an error notification is issued.

[0060] Next, the robot control method executed by the control device 60 described above will be explained with reference to Figures 17 and 18. Figures 17 and 18 are flowcharts showing an example of the processing procedure of the robot control method according to this embodiment. A series of processes to realize each of the processes described later are stored in secondary memory in the form of a program, for example. The CPU reads this program into main memory and performs information processing and calculations to realize each of the processes.

[0061] First, the end effector 52a grips the panel 22 (SA1), and in this state, 2D and 3D data are acquired (SA2). Next, the acquired 2D and 3D data are compared with the panel 2D master data and panel 3D master data stored as teaching data in the memory unit 61 to calculate the amount of deviation related to the first reference point, in other words, the amount of deviation of the studs 23a and 23b (the amount of deviation related to position and direction) (SA3). Subsequently, based on the calculated amount of deviation, the first reference points TCP1a and TCP1b in the teaching data are corrected to obtain the first corrected reference points TCP1a' and TCP1b' (SA4).

[0062] Next, with the inner liner 21 fixed, 2D and 3D data are acquired (SA5). Subsequently, the acquired 2D and 3D data are compared with the liner 2D master data and liner 3D master data stored as teaching data in the memory unit 61 to calculate the amount of deviation (positional deviation) related to the second reference point (SA6). Subsequently, based on the calculated amount of deviation, the second reference points TCP2a and TCP2b in the teaching data are corrected to obtain the second corrected reference points TCP2a' and TCP2b' (SA7).

[0063] Next, a first correction reference point TCP1a' is set as the target reference point (SA8), and the robot arm 52 is controlled to make the target reference point coincide with the second correction reference point TCP2a' (SA9). Subsequently, it is determined whether the target reference point coincides with the second correction reference point TCP2a' (SA10 in Figure 18), and if they do not coincide (SA10: NO), it is determined whether a reaction force greater than or equal to the first threshold has been detected (SA11). If no reaction force greater than or equal to the first threshold has been detected (SA11: NO), the process returns to step SA10. On the other hand, if a reaction force greater than or equal to the first threshold has been detected (SA11: YES), force control is performed (SA12). As a result, the panel 22 is swung in a predetermined swinging direction and pushed into the inner liner 21 with a predetermined force. Note that the force control may be retried a predetermined number of times until the reaction force is less than or equal to a preset second threshold.

[0064] Next, it is determined whether the reaction force has fallen below a preset second threshold (SA13). If the reaction force is not below the second threshold (SA13:NO), the robot control is stopped and an error notification is issued (SA14).

[0065] On the other hand, if the reaction force falls below the second threshold (SA13:YES), it is determined whether or not there is a first correction reference point that has not been set as a target reference point (SA15). If, as a result, an unset first correction reference point exists (SA15:YES), the target reference point is set according to a predetermined order (SA8 in Figure 17). This switches the target reference point from the first correction reference point TCP1a' to the first correction reference point TCP1b', and the robot arm 52 is controlled to make the first correction reference point TCP1b' coincide with the second correction reference point TCP2b' (SA9), and the subsequent processing is repeated. Then, if the first correction reference point TCP1b' coincides with the second correction reference point TCP2b' (SA10:YES), or if the reaction force falls below the second threshold (SA13:YES), it is determined in step SA15 that there is no first correction reference point that has not been set as a target reference point (SA15:NO), an assembly completion notification is issued (SA16), and the process ends.

[0066] Figures 19 to 22 are schematic diagrams illustrating the switching timing of the first reference point when assembling the panel 22 to the inner liner 21. In Figures 19 to 22, the panel 22 and the inner liner 21 are shown in a simplified form.

[0067] As shown in Figure 19, first, the first correction reference point TCP1a' located at the circumferential end of the panel 22 is set as the target reference point, and the robot arm 52 is controlled to align this first correction reference point TCP1a' with the second correction reference point TCP2a'. Then, as shown in Figure 20, when the first correction reference point TCP1a' aligns with the second correction reference point TCP2a', as shown in Figure 21, the next first correction reference point TCP1b' is set as the target reference point, and the robot arm 52 is controlled to align this first correction reference point TCP1b' with the second correction reference point TCP2b'. Then, as shown in Figure 21, when the first correction reference point TCP1b' aligns with the second correction reference point TCP2b', all the studs 23 are inserted through the through holes 24, and the assembly is completed.

[0068] As described above, the robot, robot control device, robot control method, and program according to this embodiment provide the following effects.

[0069] For example, the control device 60 includes a first reference point correction unit 62 that corrects the teaching data of first reference points TCP1a and TCP1b, which are defined corresponding to studs 23a and 23b, by comparing the state of the studs 23 when the panel 22 is gripped by the robot arm 52 with the state of the studs 23 when teaching data is obtained. This makes it possible to perform assembly work that takes into account manufacturing errors of the panel 22 and gripping misalignment when the robot arm 52 grips the panel 22.

[0070] Furthermore, the control device 60 includes a target reference point setting unit 64 that sequentially determines a target reference point from among a plurality of first correction reference points TCP1a', TCP1b', and an arm control unit 65 that controls the robot arm 52 to align the target reference point with the corresponding second correction reference points TCP2a', TCP2b'. This makes it possible to easily assemble a panel with multiple studs 23 onto an inner liner 21 with multiple through holes 24.

[0071] Although the present invention has been described above using embodiments, the technical scope of this disclosure is not limited to the scope described in the above embodiments. Various modifications or improvements can be made to the above embodiments without departing from the spirit of the invention, and such modified or improved forms are also included in the technical scope of this disclosure. Furthermore, the above embodiments may be combined as appropriate. Furthermore, the robot control method described in the above embodiment is just one example, and unnecessary steps may be deleted, new steps added, or the processing order rearranged, without departing from the spirit of this disclosure.

[0072] The first reference point is just an example, and three or more may be defined. That is, if the number of first reference points is M (where M is an integer) and the number of studs is N (where N is an integer), then the number of first reference points is N ≥ M ≥ 2. For example, first reference points may be defined in both end regions of panel 22. In this case, the target reference point setting unit 64 sets the target reference values ​​in the order of the first reference point provided in one end region, the first reference point provided in the central region, and the first reference point provided in the other end region.

[0073] For example, as shown in Figure 23, in panel 22, a first reference point TCP1c may be set corresponding to a stud 23c provided in the end region opposite to the end region where a stud 23a is provided. In this case, the target reference point setting unit 64 sets the target reference values ​​in the following order: first reference point TCP1a provided in one end region, first reference point TCP1b provided in the central region, and first reference point TCP1c provided in the other end region.

[0074] Furthermore, in the above-described embodiment, a panel 22 provided with a plurality of studs 23 is used as an assembly part, and this panel 22 is grasped and assembled by a robot arm 52. However, the shapes of the assembly part and the parts to be assembled are not limited to this example. Furthermore, in the above-described embodiment, a component with multiple protrusions (screws, stud bolts, etc.) was used as the assembly component. However, instead, a component with an opening may be used as the assembly component, and the assembly work may be performed on the component to be assembled which has multiple protrusions. Furthermore, although the above-described embodiment illustrates the case where the panel 22 has curvature, the panel does not necessarily have curvature and may be a flat plate.

[0075] The robot, robot control device, robot control method, and program according to this embodiment, as described above, can be understood, for example, as follows.

[0076] A robot control device (60) according to a first aspect of this disclosure is a robot control device for gripping an assembly part (22) having N (N is an integer of 2 or more) first feature parts (23) with a robot arm (52) and assembling it to an assembly part (21) having N second feature parts (24) corresponding to each of the first feature parts, and by comparing the state of M (M is an integer of 2 or more and less and less than or equal to N) of the first feature parts (23a, 23b) when the assembly part is gripped by the robot arm with the state of the M of the first feature parts when teaching data is obtained, M first reference points (TCP1a, T) defined corresponding to each of the M of the first feature parts are determined. The system includes a first reference point correction unit (62) that corrects the teaching data of CP1b) to obtain M first correction reference points (TCP1a', TCP1b'), a target reference point setting unit (64) that sets one of the M first correction reference points as a target reference point based on a preset order, and an arm control unit (65) that controls the robot arm to make the target reference point coincide with second reference points (TCP2a, TCP2b) set corresponding to the second feature portion of the assembled part, wherein the target reference point setting unit determines that the target reference point coincides with the corresponding second reference point and sets the first correction reference points in the following order as the target reference points.

[0077] According to this embodiment, the first reference point correction unit compares the state of the M first feature parts when the assembly part is gripped by the robot arm with the state of the M first feature parts when teaching data is obtained, thereby correcting the teaching data of the M first reference points defined corresponding to each of the M first feature parts. This makes it possible to perform assembly work that takes into account manufacturing errors of the assembly part and gripping misalignment when the robot arm grips the assembly part. Furthermore, the robot arm is controlled to sequentially select target reference points from among multiple target correction reference points and align these target reference points with the corresponding second reference points. In this way, by setting one target reference point at a time from among multiple target correction reference points, it becomes possible to efficiently guide an assembly part having multiple first feature parts to the corresponding second feature parts of the assembly part.

[0078] In the robot control device (60) according to a second aspect of the present disclosure, in the first aspect, the first feature portion may be a projection (23) provided on the assembly part.

[0079] According to this embodiment, in an assembly part provided with N protrusions, the state of M protrusions is compared with the state of M protrusions when teaching data is obtained. This corrects the teaching data of M first reference points defined corresponding to each of the M protrusions, and the assembly work is performed based on these corrected teaching data. This makes it possible to perform assembly work that takes into account manufacturing errors of the protrusions provided on the assembly part and gripping misalignment when the robot arm grips the assembly part.

[0080] In the robot control device (60) according to a third aspect of the present disclosure, in the second aspect, the assembly component is a panel having curvature, and the N protrusions may be spaced apart along the direction of curvature.

[0081] According to this embodiment, in a panel having curvature with N protrusions spaced apart, the teaching data of M first reference points defined corresponding to each of the M protrusions is corrected by comparing the state of the M protrusions with the state of the M protrusions when teaching data was obtained. This makes it possible to perform assembly work that takes into account manufacturing errors of the panel (e.g., panel curvature error, protrusion orientation error), etc.

[0082] In the robot control device (60) according to the fourth aspect of this disclosure, in any of the first to third aspects, the order in which the target reference points are set may be set sequentially from one end region of the panel toward the central region.

[0083] According to this embodiment, it is possible to guide the first feature portion provided on the assembly part to the corresponding second feature portion of the part to be assembled, sequentially from one end to the center. This allows for efficient assembly work.

[0084] In the fifth aspect of the present disclosure, the robot control device (60) may, in any of the first to fourth aspects, have the first reference point correction unit acquire three-dimensional data and two-dimensional data of the assembled part being held by the robot arm, and correct the teaching data of M first reference points by comparing them with the three-dimensional data and two-dimensional data obtained when the teaching data was acquired.

[0085] According to this embodiment, the teaching data is corrected using 3D data and 2D data of the assembled parts being held by the robot arm. This makes it possible to efficiently calculate the amount of deviation that reflects both the manufacturing error of the assembled parts and the gripping deviation of the assembled parts by the robot arm.

[0086] In the sixth aspect of the present disclosure, the robot control device (60) may, in the first to fifth aspects, have an arm control unit that, when the target reference point is brought to coincide with the second reference point, performs force control to push the assembly part onto the assembly part while swinging the robot arm in a preset swing direction if the reaction force generated by the assembly part contacting the assembly part exceeds a preset first threshold.

[0087] According to this embodiment, when the assembly part comes into contact with the part to be assembled, and the reaction force from the part to be assembled exceeds a first threshold, force control is performed to push the assembly part into the part to be assembled while swinging the robot arm in a preset swing direction. As a result, even if an error occurs that could not be corrected by the first reference point correction unit and the assembly part comes into contact with the part to be assembled, it is possible to guide the first feature part of the assembly part to the corresponding second feature part of the part to be assembled while searching for a second reference value by swinging the robot arm and pushing it in the direction of the part to be assembled.

[0088] In the robot control device (60) according to the seventh aspect of the present disclosure, in the sixth aspect, the arm control unit may determine that the target reference point coincides with the second reference point when the reaction force becomes less than or equal to a preset second threshold when the force control is performed.

[0089] When force control is being performed, if the reaction force falls below the second threshold, contact between the assembled part and the part being assembled is eliminated, and it can be considered that the first reference point has reached the corresponding second reference point. Therefore, when the reaction force reaches the second threshold, it can be determined that the target reference point coincides with the second reference point, allowing for efficient assembly control.

[0090] In the robot control device (60) according to the eighth aspect of the present disclosure, in the seventh aspect, the arm control unit may repeatedly perform the force control until the reaction force falls below a preset second threshold, and if the reaction force does not fall below the second threshold after performing the force control a predetermined number of times, an error notification may be issued.

[0091] If the reaction force does not fall below the second threshold even after force control is repeated a predetermined number of times, it can be assumed that an error has occurred between the assembled part and the assembled part that cannot be resolved by force control. Therefore, in such cases, issuing an error notification allows for efficient notification of defective products and enables prompt action.

[0092] A robot control device (60) according to the ninth aspect of the present disclosure further comprises a second reference point correction unit (63) that, in any of the first to eighth aspects, corrects the teaching data of M second reference points (TCP2a, TCP2b) defined corresponding to each of the M second reference points by comparing the state of M second feature parts when the assembled part is fixed with the state of M second feature parts when teaching data is obtained, thereby obtaining M second corrected reference points (TCP2a', TCP2b'), and the arm control unit may control the robot arm so as to match the target reference point with the corresponding second corrected reference point.

[0093] According to this embodiment, the second reference point correction unit compares the state of M second feature parts when the assembled part is fixed with the state of M second feature parts when teaching data is obtained, thereby correcting the teaching data of M second reference points defined corresponding to each of the M second feature parts. This makes it possible to perform assembly work that takes into account not only the manufacturing errors of the assembled part, but also the manufacturing errors and installation errors of the assembled part. This makes it possible to perform assembly work even more efficiently.

[0094] A robot according to the first aspect of this disclosure includes a robot control device according to any of the first to ninth aspects.

[0095] A robot control method according to a first aspect of this disclosure is a robot control method for gripping an assembly part having N (N is an integer of 2 or more) first feature parts with a robot arm and assembling it to an assembly part having N second feature parts corresponding to each of the first feature parts, wherein the state of M (M is an integer of 2 or more and less and less than or equal to N) of the first feature parts when the assembly part is gripped by the robot arm is compared with the state of M of the first feature parts when teaching data is obtained, thereby teaching M first reference points defined corresponding to each of the M of the first feature parts. The computer performs the following steps: (SA4) correcting the data to obtain M first correction reference points; (SA8) setting one of the M first correction reference points as a target reference point based on a predetermined order; (SA9~SA15) controlling the robot arm so that the target reference point matches a second reference point set corresponding to the second characteristic part of the assembled part; and (SA8) setting the next order of first correction reference points as the target reference point if it is determined that the target reference point matches the corresponding second reference point.

[0096] The program according to the first aspect of this disclosure is a program for causing a computer to function as a robot control device according to any of the first to ninth aspects. [Explanation of Symbols]

[0097] 1: Combustor 20: Inner combustion chamber 21: Inner liner 22: Inner liner panel (Panel: Assembly part) 22r: Master Panel 23, 23a, 23b: Studs (first feature part) 24, 24a, 24b: Through holes (second characteristic feature) 25: Washer 26: Nut 27: Through hole 50: Robot 52: Robot Arm 52a: End effector 53: Force Sensor 60: Control device (robot control device) 61: Storage part 62: 1st reference point correction section 63:Second reference point correction section 64:Target reference point setting section 65: Arm control unit TCP1a, TCP1b, TCP1c: First reference point TCP1a´,TCP1b´: 1st correction reference point TCP2a, TCP2b: Second reference point TCP2a´,TCP2b´: 2nd correction reference point

Claims

1. A robot control device for grasping an assembly part having N (where N is an integer of 2 or more) first feature parts with a robot arm and assembling it to an assembly part having N second feature parts corresponding to each of the first feature parts, A first reference point correction unit obtains M first corrected reference points by comparing the state of M first feature parts (where M is an integer between 2 and N) when the assembly part is held by the robot arm with the state of M first feature parts when teaching data is obtained, thereby correcting the teaching data of M first reference points defined corresponding to each of the M first feature parts. A target reference point setting unit sets one of the M first correction reference points as the target reference point based on a predetermined order, The arm control unit controls the robot arm so that the target reference point coincides with a second reference point set corresponding to the second characteristic portion of the assembled part. Equipped with, A robot control device in which, when the robot arm is controlled by the arm control unit, it is determined that the target reference point coincides with the corresponding second reference point, the target reference point setting unit sets the first correction reference points in the following order as the target reference point.

2. The robot control device according to claim 1, wherein the first feature portion is a projection provided on the assembly part.

3. The aforementioned assembly component is a panel having curvature, The robot control device according to claim 2, wherein the N protrusions are provided at intervals along the curvature direction.

4. The robot control device according to claim 3, wherein the order in which the target reference points are set is set sequentially from one end region of the panel toward the central region.

5. The robot control device according to claim 1, wherein the first reference point correction unit acquires three-dimensional data and two-dimensional data of the assembled part being held by the robot arm, and corrects the teaching data of M first reference points by comparing them with the three-dimensional data and two-dimensional data obtained when the teaching data was acquired.

6. The robot control device according to claim 1, wherein when the arm control unit aligns the target reference point with the second reference point, and the reaction force generated by the assembly part contacting the part to be assembled exceeds a preset first threshold, the arm control unit performs force control to push the assembly part onto the part to be assembled while swinging the robot arm in a preset swing direction.

7. The robot control device according to claim 6, wherein when the arm control unit performs the force control, it determines that the target reference point coincides with the second reference point when the reaction force falls below a preset second threshold.

8. The robot control device according to claim 7, wherein the arm control unit repeatedly performs the force control until the reaction force falls below a preset second threshold, and if the reaction force does not fall below the second threshold after a predetermined number of force control operations, an error notification is provided.

9. A second reference point correction unit obtains M corrected second reference points by comparing the state of the M second feature parts when the assembled part is fixed with the state of the M second feature parts when teaching data is obtained, thereby correcting the teaching data of M second reference points defined corresponding to each of the M second feature parts, The robot control device according to claim 1, wherein the arm control unit controls the robot arm so as to bring the target reference point to coincide with the corresponding second correction reference point.

10. A robot comprising the robot control device described in claim 1.

11. A robot control method for grasping an assembly part having N (where N is an integer of 2 or more) first feature parts with a robot arm and assembling it to an assembly part having N second feature parts corresponding to each of the first feature parts, The process involves comparing the state of M (where M is an integer between 2 and N) of the first feature portion when the assembly part is grasped by the robot arm with the state of M of the first feature portion when teaching data is obtained, thereby correcting the teaching data of M first reference points defined corresponding to each of the M first feature portion, and obtaining M first corrected reference points. A step of setting one of the M first correction reference points as the target reference point based on a predetermined order, A step of controlling the robot arm so that the target reference point coincides with a second reference point set corresponding to the second characteristic portion of the assembled part, When the robot arm is controlled and it is determined that the target reference point coincides with the corresponding second reference point, the following steps are taken to set the first correction reference point in the following order as the target reference point: A robot control method in which a computer performs the operation.

12. A program for causing a computer to function as a robot control device according to any one of claims 1 to 9.

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