Stability improvement device

Abstract

To enhance the stability of an industrial robot while maintaining a position of a tip portion of an arm.SOLUTION: A stability improvement device comprises: a first coordinate-acquisition unit 31 that acquires first coordinates where a tip portion of an industrial robot is positioned, wherein the tip portion of the industrial robot comprises an arm, at an end of which is provide with the tip portion rotatable in an azimuthal direction about a central axis, and which includes a plurality of joints rotatable about respective rotation axes; a second-coordinate setting unit that acquires second coordinates located away from the first coordinates; a stability determination unit 35 that determines stability of the industrial robot about the second coordinates relative to the first coordinates; and an azimuth candidate information generation unit 36 that generates azimuth candidate information indicating a candidate of a new azimuth of the tip portion when the stability determination unit determines that the stability is unstable. The stability determination unit determines the stability when the azimuth is the candidate on the basis of the azimuth candidate information while maintaining the coordinates of the tip portion at the first coordinates, and a display unit displays the determination result made by the stability determination unit when the azimuth is the candidate.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a stability improvement device.

Background Art

[0002] There are cases where a robot operator actually operates a robot using a teaching operation panel connected to a robot control device to teach the robot a desired working operation (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the robot system described in Patent Document 1, the robot control device calculates a plurality of positions through which the tip of the robot can pass, uses them as sampling points, and determines whether each sampling point is a singular point of the robot or in its vicinity. Then, the robot control device notifies the information display device of the position of each sampling point and the determination result information indicating the result of the determination process for each sampling point.

[0005] However, in the technology disclosed in Patent Document 1, although the user can recognize that the sampling point is a singular point of the robot or in its vicinity, the user does not know how to prevent the tip of the robot from passing through the singular point or its vicinity.

[0006] Therefore, an object of the present invention is to provide a stability improvement device capable of enhancing the stability of an industrial robot while maintaining the position of the tip of the arm.

Means for Solving the Problems

[0007] A stability improvement device according to an aspect of the present invention includes a first coordinate acquisition unit that acquires a first coordinate at which the tip of an industrial robot is located, the tip being provided at an end and having a tip portion rotatable in an azimuth direction with respect to a central axis and including a plurality of joint portions each rotatable around a plurality of rotation axes; a second coordinate acquisition unit that acquires a second coordinate away from the first coordinate; a stability determination unit that determines the stability of the industrial robot with respect to the second coordinate relative to the first coordinate; an azimuth candidate information generation unit that generates azimuth candidate information indicating candidates for a new azimuth of the tip portion when the stability determination unit determines that the stability is unstable; and a display unit. The stability determination unit determines the stability when the azimuth is a candidate based on the azimuth candidate information while maintaining the coordinates of the tip portion at the first coordinate, and the display unit displays the determination result by the stability determination unit when the azimuth is a candidate.

[0008] According to this aspect, when the stability of the industrial robot is unstable, the azimuth of the tip portion can be set to a new azimuth, and the angles of the respective joint portions included in the arm can be changed while maintaining the position of the tip portion of the arm. Thereby, the possibility that the industrial robot becomes stable can be increased without changing the position of the workpiece or the industrial robot. Therefore, the stability of the industrial robot can be increased while maintaining the position of the tip portion of the arm.

[0009] In the above aspect, the second coordinate acquisition unit may set a plurality of second coordinates separated from the first coordinate in different directions, and the stability determination unit may determine the stability with respect to each of the plurality of second coordinates relative to the first coordinate.

[0010] According to this aspect, by determining the stability when moving the tip of the arm from the position of the first coordinate to any of the positions of the plurality of second coordinates, it is possible to more accurately determine whether the first coordinate is located at or near a singular point.

[0011] In the above aspect, the azimuth angle candidate information generation unit generates azimuth angle candidate information indicating a plurality of candidates, and the stability determination unit determines each of a plurality of stabilities when the azimuth angle is one of the plurality of candidates while maintaining the coordinates of the tip as the first coordinates, and the display unit may display the determination result by the stability determination unit when the azimuth angle is one of the plurality of candidates.

[0012] According to this aspect, by preparing a plurality of azimuth angle candidates, it is possible to increase the possibility of proposing to the user the posture of the industrial robot with improved stability.

[0013] In the above aspect, the display unit may display the arm when the azimuth angle is at least one of the plurality of candidates.

[0014] According to this aspect, the user can recognize from the display on the display unit the three-dimensional shape of the arm at the candidate azimuth angle. Thereby, for example, when the tip is a welding torch, the user can recognize which candidate azimuth angle realizes the three-dimensional shape of the arm suitable for the routing of the welding cable provided along the arm.

[0015] In the above aspect, the stability improvement device may further include a reception unit that receives a selected candidate among the plurality of candidates.

[0016] According to this aspect, based on the reception result by the reception unit, the azimuth angle of the candidate selected by the user can be obtained, so that the three-dimensional shape of the arm at the time of the candidate can be realized.

[0017] A stability improvement device according to an aspect of the present invention includes a moving start coordinate acquisition unit that acquires a moving start coordinate at which the tip of an industrial robot is located, the tip being provided at an end and being rotatable in the azimuth direction with respect to a central axis and including an arm having a plurality of joint parts each rotatable around a plurality of rotation axes, a moving end coordinate acquisition unit that acquires a moving end coordinate away from the moving start coordinate, a stability determination unit that determines the stability of the industrial robot when the tip moves from the moving start coordinate to the moving end coordinate, an azimuth candidate information generation unit that generates azimuth candidate information indicating candidates for a new azimuth of the tip when the stability determination unit determines that the stability is unstable, and a display unit (27). The stability determination unit determines the stability when the azimuth is a candidate based on the azimuth candidate information while maintaining the coordinate of the tip at the moving start coordinate or the moving end coordinate, and the display unit displays the determination result by the stability determination unit when the azimuth is a candidate.

[0018] According to this aspect, when the stability when moving the tip of the industrial robot from the moving start coordinate to the moving end coordinate is unstable, the azimuth of the tip at the moving start coordinate or the moving end coordinate is set to a new azimuth, and the angles of the respective joint parts included in the arm can be changed while maintaining the position of the tip of the arm at the moving start coordinate or the moving end coordinate. Thereby, the possibility that the industrial robot becomes stable without changing the position of the workpiece or the industrial robot can be increased. Therefore, the stability of the industrial robot can be improved while maintaining the position of the tip of the arm.

[0019] In the above aspect, the azimuth candidate information generation unit may generate azimuth candidate information indicating a plurality of candidates, the stability determination unit may determine a plurality of stabilities when the azimuth is a plurality of candidates based on the azimuth candidate information while maintaining the coordinate of the tip at the moving start coordinate or the moving end coordinate, and the display unit may display the determination result by the stability determination unit when the azimuth is a plurality of candidates.

[0020] According to this aspect, by preparing a plurality of candidates for the azimuth, the possibility of proposing to the user the posture of the industrial robot with improved stability can be increased.

[0021] In the above aspect, the display unit may display the arm when the azimuth angle is at least one of a plurality of candidates.

[0022] According to this aspect, the user can recognize from the display on the display unit the three-dimensional shape of the arm at the azimuth angle of the candidate. Thereby, for example, when the tip is a welding torch, the user can recognize which candidate azimuth angle realizes a three-dimensional shaped arm suitable for the routing of the welding cable provided along the arm.

[0023] In the above aspect, the stability improvement device may further include a reception unit that receives a selected candidate among a plurality of candidates.

[0024] According to this aspect, based on the reception result by the reception unit, the azimuth angle of the candidate selected by the user can be acquired, so that the three-dimensional shape of the arm at the time of the candidate can be realized.

Advantages of the Invention

[0025] According to the present invention, it is possible to provide a stability improvement device capable of enhancing the stability of an industrial robot while maintaining the position of the tip of the arm.

Brief Description of the Drawings

[0026]

Figure 1

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Figure 8

[0027] Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. Note that the embodiments described below are merely specific examples for carrying out the present invention and do not limit the interpretation of the present invention. In addition, for ease of understanding of the description, the same reference numerals are attached to the same components in each drawing as much as possible, and duplicate descriptions may be omitted.

[0028] <One Embodiment> [Outline of Stability Improvement Device] FIG. 1 is a schematic diagram showing an MR device 201 according to an embodiment of the present invention. As shown in FIG. 1, the MR device 201 (stability improvement device) includes a processor 21, a bus 22, a work memory 23, a storage memory 24, a driver 25, a reception unit 26, a display unit 27, and a photographing unit 28.

[0029] In the MR device 201, the processor 21, the work memory 23, the storage memory 24, and the driver 25 are connected via the bus 22 so that data can be exchanged with each other.

[0030] The work memory 23 is a volatile storage device such as a DRAM (Dynamic Random Access Memory).

[0031] The storage memory 24 is a rewritable non-volatile storage device such as a flash memory, for example, and stores a program (code). The program can be installed from the outside. Further, the program is distributed in a state stored in a storage medium readable by an MR device 201 such as the storage memory 24, an HDD (Hard Disk Drive), an SSD (Solid State Drive), a memory card, or a read-only CD-ROM (Compact Disc Read Only Memory) or DVD-ROM (Digital Versatile Disc-Read Only Memory). Note that the program may be distributed on the Internet connected via a communication interface.

[0032] When executing the program, the processor 21 transfers the program stored in the storage memory 24 and the data necessary for the execution of the program to the work memory 23. The processor 21 reads out the processing instructions and data necessary for the execution of the program from the work memory 23 and executes arithmetic processing according to the content of the processing instructions. At this time, the processor 21 may newly generate the data necessary for the execution of the program and store it in the work memory 23. Note that the processor 21 is not limited to a configuration that acquires the program and data from the storage memory 24, and may be a configuration that acquires them from a server or the like via the Internet.

[0033] The driver 25 outputs various commands and data to the reception unit 26, the display unit 27, and the imaging unit 28 in accordance with an instruction from the processor 21. Further, the driver 25 receives various data output from the reception unit 26, the display unit 27, and the imaging unit 28, and outputs the received data to the processor 21.

[0034] The display unit 27 is, for example, an optically semi-transmissive head-mounted display and is connected to the harness. The user wears the harness on his / her head such that the display is positioned in front of his / her line of sight. The user can view the image displayed on the display unit 27 while viewing the actual welding object 231 through the display unit 27. In the present embodiment, at least a part of a virtual welding robot (hereinafter sometimes referred to as a virtual welding robot) (an example of an "industrial robot") 221 is displayed on the display unit 27.

[0035] The virtual welding robot 221 includes an arm 221a having a plurality of joint parts that can rotate around a plurality of rotation axes. A virtual welding torch 411 (an example of a "tip part") is provided at the end 221b of the arm 221a. The virtual welding torch 411 is rotatable with respect to the end 221b.

[0036] The imaging unit 28 is, for example, a digital camera including a lens and an image sensor (imaging element), and converts the light of the subject received by the lens into an electrical signal (image data). The digital camera is connected to the harness such that an object in the direction of the user's line of sight is photographed. The digital camera is, for example, a three-dimensional camera. Note that the digital camera may be a two-dimensional camera.

[0037] The reception unit 26 is, for example, a pointing device or a joystick. The reception unit 26 detects an operation by the user and outputs data indicating the detection result to the driver 25.

[0038] Note that the reception unit 26 may, for example, track the movement of the user's hand in the image photographed by the imaging unit 28 when the user's hand is positioned within the angle of view of the imaging unit 28, detect the shape and position of the user's hand as an operation by the user, and output data indicating the detection result to the driver 25.

[0039] When the processor 21 receives data from the reception unit 26 through the driver 25, it updates the posture and position of the virtual welding robot 221 displayed on the display unit 27 based on the received data.

[0040] The user can operate the virtual welding robot 221 by operating the reception unit 26 while looking at the virtual welding robot 221 displayed on the display unit 27. Specifically, for example, the user moves the virtual welding torch 411 along the linear welding portion 231a on the welding object 231.

[0041] FIG. 2 is a diagram for explaining the azimuth angle φ. As shown in FIGS. 1 and 2, the virtual welding torch 411 is rotatable in the azimuth direction with respect to the central axis.

[0042] Specifically, for example, the virtual welding torch 411 is rotatable about a rotation axis Ra fixed to the end portion 221b as the central axis. When the origin O of the right-handed three-dimensional orthogonal coordinates by the X-axis, Y-axis, and Z-axis is fixed to the virtual welding torch 411, the Z-axis is oriented in the direction in which the virtual welding torch 411 extends toward the tip. Specifically, the Z-axis is oriented, for example, in the direction in which the nozzle 411a attached to the tip of the virtual welding torch 411 extends. The connection portion between the virtual welding torch 411 and the end portion 221b is away from the Z-axis. The rotation axis Ra and the Z-axis do not coincide.

[0043] By changing the rotation angle of the virtual welding torch 411 with respect to the end portion 221b and the angles of the respective joints of the arm 221a, the nozzle 411a can rotate about the Z-axis as the central axis. The Y-axis is orthogonal to the Z-axis. The X-axis is orthogonal to the Y-axis and the Z-axis. The X-axis and the Y-axis rotate together with the virtual welding torch 411 when the virtual welding torch 411 rotates about the Z-axis as the central axis. The xt-axis starts from the origin O, is perpendicular to the Z-axis, and is oriented in a predetermined direction in space. That is, the xt-axis does not rotate together with the virtual welding torch 411 and does not change its orientation even when the virtual welding torch 411 rotates about the Z-axis as the central axis. The azimuth angle φ is, for example, the angle formed by the xt-axis and the X-axis, and is an angle with the counterclockwise direction being positive when viewed from the + side of the Z-axis to the - side of the Z-axis.

[0044] [Configuration of Azimuth Angle-Dependent Stability Determination Device] FIG. 3 is a functional block diagram showing each function of the azimuth angle-dependent stability determination device 101 according to an embodiment of the present invention. The azimuth angle-dependent stability determination device 101 is configured, for example, by causing the processor 21 in the MR device 201 to execute a stability improvement program, which is an example of a program.

[0045] As shown in FIG. 3, the azimuth angle-dependent stability determination device 101 includes, as functional blocks, a first coordinate acquisition unit 31, a first angle acquisition unit 32, a second coordinate setting unit 33 (second coordinate acquisition unit), a second angle calculation unit 34, a stability determination unit 35, an azimuth angle candidate information generation unit 36, an image generation unit 37, a virtual object management unit 41, and a calibration unit 42.

[0046] The virtual object management unit 41 manages the virtual welding robot 221. Specifically, the virtual object management unit 41 manages various virtual welding robot information regarding the virtual welding robot 221, such as, for example, type, performance, arm information (length of each arm 221a and connection order, etc.), axis information (angles of rotation axes and turning axes, etc.), joint information (opening angles of rotational joints and extension degrees of linear motion joints, etc.), movable range (expansion and contraction range, rotation range, bending range, etc. of arms, axes, torches, joints), and torch information (shape and azimuth angle of the torch, etc.).

[0047] The virtual welding robot information is held, for example, in the work memory 23. Among the contents of the virtual welding robot information, those related to the position and orientation of the virtual welding robot 221 are represented, for example, in the MR device coordinate system. The MR device coordinate system is a coordinate system based on, for example, markers provided in the real three-dimensional space. Hereinafter, the coordinates represented in the MR device coordinate system may be referred to as MR device coordinates. Details of the markers will be described later.

[0048] Among the contents of the virtual welding robot information, the content related to the posture of the virtual welding robot 221 is represented, for example, in a robot coordinate system with the virtual welding robot 221 as a reference. Hereinafter, the coordinates represented in the robot coordinate system may be referred to as robot coordinates.

[0049] Although the configuration for managing the content related to the posture of the virtual welding robot 221 in robot coordinates has been described, it is not limited thereto. For example, a configuration in which all of the position, orientation, and posture of the virtual welding robot 221 are managed by the MR device coordinates may be used.

[0050] Further, the virtual object management unit 41 updates the virtual welding robot information based on the data received from the reception unit 26. Specifically, when the virtual object management unit 41 receives data including the operation content of changing the position or azimuth angle φ of the virtual welding torch 411, for example, based on the data, the virtual welding robot information is updated so that the virtual welding torch 411 is positioned at the changed position with the azimuth angle φ.

[0051] The calibration unit 42 periodically updates the coordinate conversion information for converting between the MR device coordinates and the robot coordinates. The coordinate conversion information is held, for example, in the work memory 23.

[0052] The coordinate transformation in the calibration unit 42 can be realized by existing technologies. For example, markers are arranged around the welding object 231. A two-dimensional code indicating the identifier of the marker is drawn on the marker. The MR device coordinates of the marker are stored in the work memory 23 or the storage memory 24 in association with the identifier of the marker.

[0053] When the calibration unit 42 recognizes that a marker is included in the image captured by the imaging unit 28, it acquires the MR device coordinates of the marker, and generates coordinate transformation information including a transformation formula for converting the MR device coordinates and the robot coordinates based on the acquired coordinates and the virtual welding robot information.

[0054] Based on the virtual welding robot information and the coordinate transformation information, the image generation unit 37 generates an image (hereinafter sometimes referred to as a virtual object image) including at least a part of the virtual welding robot 221. In the virtual object image, the virtual welding robot 221 is drawn at a position and orientation corresponding to the movement when the user moves the viewpoint. Also, in the virtual object image, the virtual welding robot 221 is drawn in a posture corresponding to the change when the angle of each joint of the arm 221a in the virtual welding robot 221 and the azimuth angle φ of the virtual welding torch 411 are changed. The image generation unit 37 outputs virtual object image information including the generated virtual object image to the display unit 27 via the bus 22. The display unit 27 displays at least a part of the virtual welding robot 221 based on the virtual object image information.

[0055] FIG. 4 is a diagram showing an example of a virtual regular hexahedron 421 according to an embodiment of the present invention. As shown in FIGS. 3 and 4, the first coordinate acquisition unit 31 acquires the first coordinates at which the tip, for example, the virtual welding torch 411, provided at the end 221b of the arm 221a in the virtual welding robot 221 is located.

[0056] In this embodiment, for example, when the virtual welding torch 411 exists in the vicinity of the welding location 231a on the welding object 231, the first coordinate acquisition unit 31 acquires the robot coordinates (hereinafter sometimes referred to as torch tip robot coordinates) (an example of the "first coordinate") RC1 at which the tip of the virtual welding torch 411 is located based on the virtual welding robot information held in the work memory 23. The first coordinate acquisition unit 31 outputs the torch tip robot coordinates RC1 to the stability determination unit 35 and the second coordinate setting unit 33.

[0057] The second coordinate setting unit 33 sets a plurality of second coordinates that are separated from the first coordinate in different directions. In this embodiment, the second coordinate setting unit 33 sets, for example, a plurality of second coordinates that are each equidistant from the first coordinate. Specifically, for example, when the second coordinate setting unit 33 receives the torch tip robot coordinates RC1 from the first coordinate acquisition unit 31, it sets eight torch peripheral robot coordinates RC2 (an example of the "second coordinate"). The eight torch peripheral robot coordinates RC2 are, for example, the robot coordinates of the eight vertices in the virtual regular hexahedron 421 centered on the torch tip robot coordinates RC1. The second coordinate setting unit 33 outputs the set eight torch peripheral robot coordinates RC2 to the stability determination unit 35. Note that the second coordinate setting unit 33 may be configured to set the centers of the six surfaces of the virtual regular hexahedron 421 as the second coordinates.

[0058] The stability determination unit 35 determines the stability of the virtual welding robot 221 with respect to each of the plurality of second coordinates relative to the first coordinate.

[0059] Specifically, when the stability determination unit 35 receives the torch tip robot coordinates RC1 from the first coordinate acquisition unit 31, it acquires an angle set (hereinafter sometimes referred to as the first angle set) when the tip of the virtual welding torch 411 is located at the torch tip robot coordinates RC1. Here, the angle set includes, for example, the rotation angles (positions) of a plurality of servo motors that drive a rotation axis, a swivel axis, a rotary joint, a linear motion joint, etc. respectively. Hereinafter, each of these angles may be referred to as an arm-related angle. The arm-related angle may include the rotation angle of the virtual welding torch 411 with respect to the end portion 221b.

[0060] In this embodiment, the stability determination unit 35 outputs the torch tip robot coordinates RC1 to the first angle acquisition unit 32. When the first angle acquisition unit 32 receives the torch tip robot coordinates RC1 from the stability determination unit 35, it acquires the first angle set based on the virtual welding robot information, and outputs the acquired first angle set to the stability determination unit 35.

[0061] Also, when the stability determination unit 35 receives eight torch peripheral robot coordinates RC2 from the second coordinate setting unit 33, it acquires eight angle sets (hereinafter sometimes referred to as the second angle set) when the tip of the virtual welding torch 411 is located at each of the eight torch peripheral robot coordinates RC2.

[0062] In this embodiment, the stability determination unit 35 outputs the eight torch peripheral robot coordinates RC2 to the second angle calculation unit 34. When the second angle calculation unit 34 receives the eight torch peripheral robot coordinates RC2 from the stability determination unit 35, it calculates eight second angle sets corresponding to the eight torch peripheral robot coordinates RC2 respectively by inverse kinematics based on the virtual welding robot information. The second angle calculation unit 34 outputs the calculated eight second angle sets to the stability determination unit 35.

[0063] The stability determination unit 35 selects one of the eight acquired second angle sets, and compares a plurality of arm-related angles (hereinafter sometimes referred to as second arm-related angles) included in the selected second angle set with a plurality of arm-related angles (hereinafter sometimes referred to as first arm-related angles) included in the first set. Based on the comparison result, the stability determination unit 35 determines the stability when the tip of the virtual welding torch 411 moves to the torch peripheral robot coordinates RC2 corresponding to the selected second angle set.

[0064] Specifically, for example, the stability determination unit 35 calculates the magnitude of the difference between each of the plurality of second arm-related angles and the plurality of first arm-related angles. For example, when all of the plurality of differences are equal to or less than a predetermined threshold, since the angular change of each arm-related angle is small, the stability determination unit 35 determines that the movement of the tip of the virtual welding torch 411 is stable.

[0065] On the other hand, when at least one of the plurality of differences is greater than the predetermined threshold, since the change in each arm-related angle is large, the stability determination unit 35 recognizes that the torch tip robot coordinates RC1 are located at or near a singular point, and determines that the posture of the virtual welding robot 221 is unstable.

[0066] The stability determination unit 35 determines the stability for each second angle set, that is, for each torch peripheral robot coordinates RC2. When there are torch peripheral robot coordinates RC2 determined to be unstable, the stability determination unit 35 outputs instability determination information to the azimuth angle candidate information generation unit 36.

[0067] When the stability determination unit 35 determines that the stability is unstable, the azimuth angle candidate information generation unit 36 generates azimuth angle candidate information indicating candidates for a new azimuth angle φ of the virtual welding torch 411.

[0068] In the present embodiment, for example, when the azimuth angle candidate information generation unit 36 receives instability determination information from the stability determination unit 35, the azimuth angle candidate information generation unit 36 generates azimuth angle candidate information indicating a new azimuth angle (φ + α) obtained by adding the angle α to the current azimuth angle φ as a candidate, and outputs the azimuth angle candidate information to the stability determination unit 35.

[0069] FIG. 5 is a diagram showing an example of a determination result image 401 including a virtual welding robot 221 when the tip of a virtual welding torch 411 is located at a torch tip robot coordinate RC1 when the azimuth angle is φ.

[0070] FIG. 6 is a diagram showing an example of a virtual object image 402 including a virtual welding robot 221 when the tip of a virtual welding torch 411 is located at a torch tip robot coordinate RC1 when the azimuth angle is (φ + α).

[0071] As shown in FIGS. 5 and 6, even when the tip of the virtual welding torch 411 is located at the torch tip robot coordinate RC1 = (X1, Y1, Z1), when the azimuth angle is different, a plurality of arm related angles are different. That is, when the azimuth angle is φ, even if the torch tip robot coordinate RC1 is located at or near a singular point and is determined to be unstable, it may be determined to be stable when the azimuth angle is (φ + α).

[0072] As shown in FIG. 3, when the stability determination unit 35 receives azimuth angle candidate information from the azimuth angle candidate information generation unit 36, while maintaining the coordinate of the tip of the virtual welding torch 411 at the torch tip robot coordinate RC1, based on the azimuth angle candidate information, it determines the stability when the azimuth angle is the candidate azimuth angle (φ + α).

[0073] Specifically, when the stability determination unit 35 receives azimuth angle candidate information from the azimuth angle candidate information generation unit 36, it acquires a first angle set and a second angle set when the tip of the virtual welding torch 411 is located at the torch tip robot coordinate RC1 and the azimuth angle is (φ + α).

[0074] In the present embodiment, the stability determination unit 35 outputs the torch tip robot coordinate RC1 and the azimuth angle (φ + α) to the first angle acquisition unit 32. When the first angle acquisition unit 32 receives the torch tip robot coordinate RC1 and the azimuth angle (φ + α) from the stability determination unit 35, based on the virtual welding robot information, while maintaining the coordinate of the tip of the virtual welding torch 411 at the torch tip robot coordinate RC1, it calculates a first angle set when the azimuth angle is (φ + α) and outputs it to the stability determination unit 35.

[0075] Further, the stability determination unit 35 outputs the eight torch peripheral robot coordinates RC2 and the azimuth angle (φ + α) to the second angle calculation unit 34. When receiving the eight torch peripheral robot coordinates RC2 and the azimuth angle (φ + α) from the stability determination unit 35, the second angle calculation unit 34, based on the virtual welding robot information, maintains the coordinates of the tip of the virtual welding torch 411 at each of the eight torch peripheral robot coordinates RC2, and calculates, by inverse kinematics, the eight second angle sets when the azimuth angle is (φ + α), each corresponding to one of the eight torch peripheral robot coordinates RC2. The second angle calculation unit 34 outputs the eight second angle sets to the stability determination unit 35.

[0076] Based on the acquired first angle set and the eight second angle sets, the stability determination unit 35 determines the stability when the azimuth angle of the virtual welding torch 411 is (φ + α).

[0077] The stability determination unit 35 outputs azimuth angle - specific determination result information including the determination result when the azimuth angle is φ and the determination result when the azimuth angle is φ + α to the image generation unit 37.

[0078] As shown in FIGS. 1, 3, and 5, the image generation unit 37 generates image information for displaying the determination results by the stability determination unit 35 when the azimuth angles are φ and (φ + α).

[0079] In this embodiment, when receiving the azimuth angle - specific determination result information from the stability determination unit 37, the image generation unit 37 generates a determination result image 401 (see FIG. 5) including the determination results for each azimuth angle based on the azimuth angle - specific determination result information.

[0080] The image generation unit 37 outputs the image information including the generated determination result image 401 to the display unit 27 via the bus 22. When receiving the image information from the image generation unit 37, the display unit 27 displays the determination result image 401 based on the image information.

[0081] When the user sees the determination result image 401 and recognizes that the tip of the virtual welding torch 411 is located at or near a singular point and is unstable at the azimuth angle φ, the user performs an operation to select another azimuth angle with stable stability for the reception unit 26.

[0082] When the reception unit 26 receives the azimuth angle (hereinafter, may be referred to as the selected azimuth angle) selected by the user among a plurality of azimuth angles (φ + α), the reception unit 26 outputs reception information indicating the received result to the azimuth angle-specific stability determination device 101 via the bus 22.

[0083] When the virtual object management unit 41 in the azimuth angle-specific stability determination device 101 receives the reception information, for example, based on the reception information, the virtual object management unit 41 updates the azimuth angle included in the virtual welding robot information to the selected azimuth angle.

[0084] As shown in FIGS. 1, 3, and 6, the display unit 27 displays the arm 221a when the azimuth angle is at least one of a plurality of candidates.

[0085] In the present embodiment, when the azimuth angle in the virtual welding robot information is updated, the image generation unit 37 generates a virtual object image 402 including the virtual welding robot 221 when the azimuth angle of the virtual welding torch 411 is the selected azimuth angle, the determination button 402a, and the other candidate selection button 402b. The image generation unit 37 outputs image information including the generated virtual object image 402 to the display unit 27 via the bus 22.

[0086] When the display unit 27 receives the image information from the image generation unit 37 via the bus 22, the display unit 27 displays the virtual object image 402 based on the image information.

[0087] The user looks at the posture of the virtual welding robot 221 displayed on the display unit 27 and, for example, checks whether there is any difficulty in the handling of the welding cable. When the user confirms that there is no difficulty in the handling of the welding cable, the user performs a determination operation on the reception unit 26. The determination operation is, for example, an operation of pressing the determination button 402a in the virtual object image 402.

[0088] On the other hand, when the user determines that it is difficult to handle the welding cable, the user performs an operation to select another candidate for the azimuth angle with respect to the reception unit 26. The operation of selecting another candidate for the azimuth angle is, for example, an operation of pressing the other candidate selection button 402b in the virtual object image 402.

[0089] The reception unit 26 outputs operation information indicating the operation result by the user to the azimuth angle-specific stability determination device 101 via the bus 22.

[0090] When the image generation unit 37 in the azimuth angle-specific stability determination device 101 receives the operation information, if the operation information indicates an operation of selecting another candidate for the azimuth angle, the image generation unit 37 outputs image information including the determination result image 401 to the display unit 27. The user can view the determination result image 401 displayed on the display unit 27 and select another candidate for the azimuth angle.

[0091] On the other hand, when the operation information indicates an operation of determining the azimuth angle, the image generation unit 37 continues to generate a virtual object image including the virtual welding robot 221 at the selected azimuth angle.

[0092] [Method for improving stability] Next, the method for improving stability in an embodiment of the present invention will be specifically and in detail described. FIG. 7 is a flowchart showing a method for improving stability executed by the MR device according to an embodiment of the present invention. As shown in FIG. 7, the method for improving stability includes steps S102 to S116, and each step is executed by the processor 21 included in the MR device 201.

[0093] The method for improving stability is executed when a predetermined condition is satisfied. The predetermined condition is, for example, when the user teaches the virtual welding robot 221 and moves the tip of the virtual welding torch 411 to the welding start position. Note that the predetermined condition may be, for example, a timing at each predetermined cycle or when the tip of the virtual welding torch 411 approaches the end of the movable range of the virtual welding robot 221.

[0094] First, assume a situation where the azimuth angle of the virtual welding torch 411 in the virtual welding robot 221 is set to φ. The MR device 201 acquires the first angle set and a plurality of second angle sets. Then, for each second angle set, that is, for each torch-peripheral robot coordinate RC2, the MR device 201 performs a stability determination process to determine the stability when the tip of the virtual welding torch 411 moves to the torch-peripheral robot coordinate RC2 (step S102).

[0095] Next, when the MR device 201 determines that it is stable in the stability determination process (NO in step S104), it performs the stability determination process when the above predetermined conditions are satisfied (step S102).

[0096] On the other hand, when the MR device 201 determines that the torch tip robot coordinate RC1 is located at or near a singular point and is unstable (YES in step S104), for example, it generates azimuth angle candidate information indicating 23 patterns of azimuth angles (φ + α) obtained by adding α in 15° increments from 15° to 345° to the azimuth angle φ (step S106).

[0097] Next, based on the azimuth angle candidate information, the MR device 201 performs the stability determination process each time it increases α by 15° and sets the azimuth angle of the virtual welding torch 411 to (φ + α) (step S108).

[0098] Next, the MR device 201 displays a determination result image 401 (see FIG. 5) including the determination results for each azimuth angle (φ + α) (step S110).

[0099] Next, the MR device 201 waits until it receives the user's selection of the azimuth angle (NO in step S112). When it receives the user's selection of the azimuth angle (YES in step S112), it displays a virtual object image 402 (see FIG. 6) including the virtual welding robot 221 at the azimuth angle selected by the user, that is, the selected azimuth angle (step S114).

[0100] Next, when the user confirms that there is no problem with the handling of the welding cable in the virtual welding robot 221 displayed in the virtual object image 402, the user operates the reception unit 26 to press the determination button 402a in the virtual object image 402. When the MR device 201 receives the pressing of the determination button 402a by the user (YES in step S116), it ends the execution of the stability improvement method.

[0101] On the other hand, when the user confirms that there is a problem with the handling of the welding cable, the user operates the reception unit 26 to press the other candidate selection button 402b in the virtual object image 402. When the MR device 201 receives the pressing of the other candidate selection button 402b by the user (NO in step S116), it waits until it receives the selection of the azimuth angle by the user (NO in step S112).

[0102] Note that in the present embodiment, the stability determination unit 35 has been described as being configured to determine the stability of the virtual welding robot 221 with respect to each of a plurality of second coordinates with respect to the first coordinate, but the present invention is not limited thereto. The stability determination unit 35 may be configured to determine the stability of the virtual welding robot 221 with respect to one second coordinate with respect to the first coordinate.

[0103] Also, in this embodiment, the stability determination unit 35 has been described as determining instability when it recognizes that the torch tip robot coordinates RC1 are located at or near a singular point, but it is not limited to this. The stability determination unit 35 may be configured to determine the stability of the virtual welding robot 221 when the tip of the virtual welding torch 411 moves from the movement start coordinate to the movement end coordinate. Here, the movement start coordinate acquisition unit acquires the movement start coordinate at which the tip of the virtual welding torch 411 of the virtual welding robot 221 is located. The movement end coordinate acquisition unit acquires the movement end coordinate that is away from the movement start coordinate. Specifically, the movement start coordinate and the movement end coordinate are, for example, the coordinates of the welding start position and the coordinates of the welding end position at the welding location 231a of the welding object 231 when welding the virtual welding robot 221. In this configuration, when the tip of the virtual welding torch 411 is moved on a straight line or a curve from the welding start position to the welding end position, when the tip of the virtual welding torch 411 passes through a singular point or its vicinity, the stability determination unit 35 determines that the stability of the virtual welding robot 221 is unstable. When the stability determination unit 35 determines that the stability of the virtual welding robot 221 is unstable, while maintaining the coordinates of the tip of the virtual welding torch 411 at the movement start coordinate or the movement end coordinate, based on the azimuth angle candidate information, it determines the stability when the azimuth angle of the virtual welding torch 411 is a candidate. That is, by changing the azimuth angle of the virtual welding torch 411 at at least one of the movement start coordinate and the movement end coordinate, the stability of the virtual welding robot 221 can be enhanced.

[0104] Also, in this embodiment, the configuration for determining the stability of the virtual welding robot 221 has been described, but it is not limited to this. A configuration for determining the stability of other types of robots may also be used.

[0105] In addition, in this embodiment, a configuration for determining the stability of the virtual welding robot 221 has been described, but the present invention is not limited thereto. A configuration in which an actual welding robot is arranged within the angle of view of the imaging unit 28 and the stability of the actual welding robot is determined may also be adopted. In this case, the first angle acquisition unit 32 acquires a first angle set from, for example, the states of the respective axes. Specifically, the first angle acquisition unit 32 acquires the first angle set from the load of the motor that drives each axis or the measured values by sensors provided on each axis.

[0106] In addition, in this embodiment, as shown in FIG. 2, a configuration in which the azimuth angle φ is defined based on the central axis along the extending direction of the nozzle 411a has been described, but the present invention is not limited thereto. The azimuth angle φ may be defined based on the rotation axis Ra of the virtual welding torch 411 with respect to the end portion 221b.

[0107] FIG. 8 is a diagram for explaining a modified example of the azimuth angle φ. As shown in FIGS. 1 and 8, for example, when the origin O of the right-handed three-dimensional orthogonal coordinates by the X-axis, Y-axis, and Z-axis is fixed to the end portion 221b, the Z-axis is the central axis of rotation of the virtual welding torch 411 with respect to the arm 221a. That is, the Z-axis and the rotation axis Ra coincide. The Y-axis is parallel to, for example, the extending direction of the end portion 221b. The X-axis is orthogonal to the Y-axis and the Z-axis. The position vector r is a vector having the origin O and the tip of the virtual welding torch 411 as the starting point and the ending point, respectively. The tip of the virtual welding torch 411, that is, the ending point of the position vector r, is separated from the Z-axis. The azimuth angle φ is, for example, the angle formed by the projection of the position vector r onto the XY plane and the X-axis, and is an angle with the counterclockwise direction being positive when viewed from the + side of the Z-axis to the - side of the Z-axis. In this case, the arm-related angle may not include the rotation angle of the virtual welding torch 411 with respect to the end portion 221b.

[0108] In addition, in this embodiment, a configuration in which the virtual welding torch 411 is provided at the end portion 221b of the arm 221a has been described, but the present invention is not limited thereto. A configuration in which other tools such as the plasma torch of a plasma cutting machine or the robot hand of a transfer machine are provided at the end portion 221b of the arm 221a as the tip portion may also be adopted.

[0109] The embodiments described above are for facilitating the understanding of the present invention and are not for limiting and interpreting the present invention. Each element included in the embodiments, as well as its arrangement, material, conditions, shape, size, etc. are not limited to those exemplified and can be appropriately changed. Also, it is possible to partially substitute or combine the configurations shown in different embodiments.

Explanation of Reference Numerals

[0110] 21…Processor, 22…Bus, 23…Work Memory, 24…Storage Memory, 25…Driver, 26…Reception Unit, 27…Display Unit, 28…Imaging Unit, 31…First Coordinate Acquisition Unit, 32…First Angle Acquisition Unit, 33…Second Coordinate Setting Unit, 34…Second Angle Calculation Unit, 35…Stability Determination Unit, 36…Azimuth Angle Candidate Information Generation Unit, 37…Image Generation Unit, 41…Virtual Object Management Unit, 42…Calibration Unit, 101…Azimuth Angle-Dependent Stability Determination Device, 201…MR Device, 221…Virtual Welding Robot, 221a…Arm, 221b…End Portion, 231…Welding Object, 231a…Welding Location, 401…Determination Result Image, 402…Virtual Object Image, 402a…Decision Button, 402b…Other Candidate Selection Button, 411…Virtual Welding Torch, 421…Virtual Regular Hexahedron, RC1…Torch Tip Robot Coordinates, RC2…Torch Peripheral Robot Coordinates

Claims

1. A first coordinate acquisition unit that acquires a first coordinate at which a tip portion of an industrial robot provided with an arm including a plurality of joint portions rotatable around a plurality of rotation axes and having a tip portion rotatable in an azimuth direction with respect to a central axis is located; A second coordinate acquisition unit that acquires a second coordinate away from the first coordinate; A stability determination unit that determines the stability of the industrial robot with respect to the second coordinate relative to the first coordinate; An azimuth candidate information generation unit that generates azimuth candidate information indicating a new azimuth candidate for the tip portion when the stability determination unit determines that the stability is unstable; A display unit; and The stability determination unit determines the stability when the azimuth is the candidate based on the azimuth candidate information while maintaining the coordinates of the tip portion at the first coordinate. The display unit displays a determination result by the stability determination unit when the azimuth is the candidate. A stability improvement device.

2. The second coordinate acquisition unit sets a plurality of the second coordinates separated from the first coordinate in different directions. The stability determination unit determines the stability with respect to each of the plurality of the second coordinates relative to the first coordinate. The stability improvement device according to claim 1.

3. The azimuth candidate information generation unit generates the azimuth candidate information indicating a plurality of the candidates. The stability determination unit determines a plurality of the stabilities when the azimuth is the plurality of the candidates based on the azimuth candidate information while maintaining the coordinates of the tip portion at the first coordinate. The display unit displays a determination result by the stability determination unit when the azimuth is the plurality of the candidates. The stability improvement device according to claim 1.

4. The display unit displays the arm when the azimuth is at least one of the plurality of the candidates. The stability improvement device according to claim 3.

5. The stability improvement device further includes A reception unit that receives the selected candidate among the plurality of the candidates. The stability improvement device according to claim 3.

6. A movement start coordinate acquisition unit that acquires a movement start coordinate at which a tip portion of an industrial robot provided with an arm including a plurality of joint portions rotatable around a plurality of rotation axes and having a tip portion rotatable in an azimuth direction with respect to a central axis is located; A movement end coordinate acquisition unit that acquires a movement end coordinate away from the movement start coordinate; A stability determination unit that determines the stability of the industrial robot when the tip moves from the movement start coordinate to the movement end coordinate; An azimuth angle candidate information generation unit that generates azimuth angle candidate information indicating candidates for a new azimuth angle of the tip when the stability determination unit determines that the stability is unstable; A display unit, and The stability determination unit determines the stability when the azimuth angle is the candidate based on the azimuth angle candidate information while maintaining the coordinate of the tip at the movement start coordinate or the movement end coordinate. The display unit displays the determination result by the stability determination unit when the azimuth angle is the candidate. A stability improvement device. **Claim 7** The azimuth angle candidate information generation unit generates the azimuth angle candidate information indicating a plurality of the candidates. The stability determination unit determines a plurality of stabilities when the azimuth angle is the plurality of candidates based on the azimuth angle candidate information while maintaining the coordinate of the tip at the movement start coordinate or the movement end coordinate. The display unit displays the determination result by the stability determination unit when the azimuth angle is the plurality of candidates. The stability improvement device according to claim 6. **Claim 8** The display unit displays the arm when the azimuth angle is at least one of the plurality of candidates. The stability improvement device according to claim 7. **Claim 9** The stability improvement device further includes a reception unit that receives the selected candidate among the plurality of candidates. The stability improvement device according to claim 7.

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