Zero point calibration method for processing tools

Abstract

The present invention provides a zero-point calibration method that can be easily performed on a processing tool mounted on the front end of an arm of a robot having a drive shaft. The present invention provides a zero-point calibration method for a processing tool, which controls a driving unit in a multi-jointed robot having a plurality of driving units driving a single or multiple driving shafts and holds a processing tool that performs a predetermined processing on a processing object at the front end of the arm, and controls the processing position of the processing tool on the processing object, thereby performing zero-point calibration of the processing tool, wherein information of a reference direction of the robot, i.e., reference direction information, is obtained from the movement of the robot, and zero-point calibration of the processing tool is performed based on the obtained reference direction information.

Description

Technical Field

[0001] The present invention relates to a zero point calibration method for a processing tool for performing various processing such as clamping and processing. Background Art

[0002] In industrial robots, at the final stage of the manufacturing process or during adjustment work for shipment to users, when replacing a servo motor as an example of a driving source of the robot, or when repairing a robot system after an interference accident occurs during operation, a correction is performed to achieve consistency between the origin posture of the actual robot and the origin of the program involved in the robot, that is, zero point calibration (mastering) is performed (for example, refer to the following patent document 1). Such a zero point calibration operation is also the same for a processing tool, which is a processing tool mounted on the front end of the robot arm, and controls the processing position of the processing tool on the processing object by driving a single or multiple (rotating) drive shafts possessed by the processing tool itself.

[0003] As an example of such a processing tool, there is an articulated arm composed of two links mounted on the front end of the arm of the robot. In the zero point calibration work, adjustment is performed using a mark attached to the arm and a dedicated jig.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 08-171410 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, in the case where the arm is not marked, in an environment where no special equipment is prepared for maintenance after leaving the factory, the problem of spending a lot of man-hours on the zero-point calibration operation will arise. The same is true when there is no special fixture. In addition, generally speaking, it is necessary to set the reference direction of the robot to be consistent with the reference direction of the processing tool, but in the absence of markings, it will take time to perform zero-point calibration to make the two reference directions consistent. Therefore, a zero-point calibration method that can be easily performed on a processing tool mounted on the front end of an arm of a robot having a drive shaft is desired.

[0009] Means for solving problems

[0010] The present invention discloses a method for zero-point calibration of a processing tool, which controls a processing tool for performing predetermined processing on a processing object to be maintained at the front end of an arm, and has a driving unit in a multi-articulated robot having multiple driving units for driving a single or multiple driving axes, and controls the processing position of the processing tool on the processing object, thereby performing zero-point calibration of the processing tool, wherein information on a reference direction of the robot, i.e., reference direction information, is obtained from the movement of the robot, and zero-point calibration of the processing tool is performed based on the obtained reference direction information.

[0011] Effects of the Invention

[0012] According to the present disclosure, it is possible to provide a zero-point calibration method that can be easily performed on a processing tool mounted on a front end portion of an arm of a robot having a drive shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a diagram showing a system configuration of a robot system to which the first application example of the present invention is applied.

[0014] Figure 2A It is a side view of the robot system of the first application example.

[0015] Figure 2B It is a partially enlarged top view of the robot system of the first application example.

[0016] Figure 3A 1 is a side view showing one step of the zero point calibration operation of the robot system of the first application example ( Figure 2A corresponding figure).

[0017] Figure 3B is with Figure 3A The corresponding partial enlarged top view ( Figure 2B corresponding figure).

[0018] Figure 4A Yes means Figure 3A Side view of the next step.

[0019] Figure 4B is with Figure 4A The corresponding partial enlarged top view.

[0020] Figure 5A Yes means Figure 4A Side view of the next step.

[0021] Figure 5B is with Figure 5A The corresponding partial enlarged top view.

[0022] Fig. 6A Yes means Figure 5A Side view of the next step.

[0023] Figure 6B is with Fig. 6A The corresponding partial enlarged top view.

[0024] Fig. 7A Yes means Fig. 6A Side view of the next step.

[0025] Figure 7B is with Fig. 7A The corresponding partial enlarged top view.

[0026] Figure 8 It is a principle diagram of a rotary wedge scanner according to a second application example of the present invention.

[0027] Fig.9A This is a side view showing one step of the zero point calibration operation of the robot system according to the second application example.

[0028] Fig. 9B is with Fig.9A The corresponding partial enlarged top view.

[0029] Fig. 10A Yes means Fig.9A Side view of the next step.

[0030] Fig. 10B is with Fig. 10A The corresponding partial enlarged top view.

[0031] Fig.11A Yes means Fig. 10A Side view of the next step.

[0032] Fig. 11B is with Fig.11A The corresponding partial enlarged top view.

[0033] Fig.12 This is a schematic diagram of a galvano-scanner according to a third application example of the present invention. DETAILED DESCRIPTION

[0034] [First application example]

[0035] Hereinafter, a first application example in which the zero point calibration method of a processing tool of the present invention is applied to a robot system having a robot and an arm will be described with reference to the accompanying drawings. In addition, the same reference numerals are given to the same or corresponding parts in each of the drawings. Figure 1 It is a diagram showing a system configuration of a robot system to which the first application example of the present invention is applied. Figure 2A It is a side view of the robot system of the first application example. Figure 2B It is a partially enlarged top view of the robot system of the first application example.

[0036] like Figures 1 to 2B As shown, the robot system 1 of the first application example includes a robot 2, an arm 3 as an example of a processing tool, a robot control device 41 for controlling the robot 2, and a tool control device 42 for controlling the arm 3. The robot system 1 moves the robot 2 and the arm 3 to a target position, and performs a predetermined process on a workpiece (not shown) through the arm 3.

[0037] In the first application example, the processing is clamping (clamping, adsorption, etc.) of a workpiece, etc., but it is not limited to this. The processing may also be contact-based removal processing (cutting, welding, etc.), non-contact-based removal processing (laser processing, etc.), and discharge of fluids (sealing materials, coatings, etc.).

[0038] The robot 2 is, for example, a 6-axis vertical multi-joint robot, and has a base (base) 21, a lower robot arm 22, an upper robot arm 23, and a robot arm front end 24 (arm front end). The base 21 is set on a reference plane R1 as the upper surface of the ground. One end side of the lower robot arm 22 is connected to the base 21 in a manner that can rotate around a first axis (vertical axis) J1 and a second axis (horizontal axis) J2. The other end side of the lower robot arm 22 is connected to one end side of the upper robot arm 23 in a manner that can rotate around a third axis (horizontal axis) J3. At the other end side of the upper robot arm 23, the robot arm front end 24 is connected in a manner that can rotate around a fourth axis J4 perpendicular to the third axis J3 and a fifth axis J5 perpendicular to the fourth axis J4. An arm 3 as an example of a processing tool is installed at the robot arm front end 24 in a manner that can rotate around a sixth axis J6 perpendicular to the fifth axis J5.

[0039] In addition, the robot 2 is not limited to a 6-axis vertical articulated robot, and may be another type of articulated robot such as a 4-axis vertical articulated robot. The driving axis may be a single axis.

[0040] The robot 2 has a plurality of servo motors (not shown) built in to drive a plurality of drive axes of the first axis J1 to the sixth axis J6. The servo motors are driven by control signals from the robot control device 41. The position and posture of the robot 2 are changed by the driving of the servo motors, and the position and posture of the arm 3 mounted on the robot 2 are changed.

[0041] The arm 3 is an example of a processing tool. The processing tool controls the processing position of the processing object and performs a predetermined processing on the processing object. The processing object and the processing position are different depending on the content of the processing. In the case where the processing is clamping, the processing object is clamped, and the processing position is the clamped position. In the case where the processing is processing, the processing object is the processed object, and the processing position is the processing position. In the case where the processing is discharge, the processing object is an attached object (for example, a component attached with a sealing material), and the processing position is an attachment position.

[0042] The arm 3 is held at the front end portion 24 of the robot arm. The arm 3 is, for example, a 1-axis articulated arm mechanism, and has a first arm 31, a second arm 32, and a clamp 33. One end of the first arm 31 is connected to the front end portion 24 of the robot arm so as to be rotatable around the sixth axis J6. One end of the second arm 32 is connected to the other end of the first arm 31 so as to be rotatable around the seventh axis J7. A clamp 33 for clamping a workpiece is connected to the other end of the second arm 32. The reference axis of the clamp 33 is referred to as the eighth axis J8 (refer to Figure 2A ). The sixth axis J6, the seventh axis J7 and the eighth axis J8 are arranged in parallel. The clamping method based on the clamper 33 is not limited, for example, clamping, adsorption, and suction.

[0043] The arm 3 has a built-in servo motor (not shown) for driving the drive shaft of the seventh axis J7. The servo motor is driven by a control signal from the tool control device 42. The position and posture of the gripper 33 in the arm 3 are changed by the drive of the servo motor, and the clamping operation is performed.

[0044] The robot control device 41 and the tool control device 42 are each configured as a computing device including a CPU, a ROM, a RAM, and other peripheral circuits. The robot control device 41 and the tool control device 42 send and receive signals to each other (communication). The robot control device 41 stores the operation program (operation program) of the robot 2 and the processing tool, teaching data, etc. In addition, the robot control device 41 can also serve as the tool control device 42.

[0045] use FIG. 2A to FIG. 7B , the zero point calibration operation of the robot system of the first application example is explained. Figure 3A 1 is a side view showing one step of the zero point calibration operation of the robot system of the first application example ( Figure 2A corresponding figure). Figure 3B is with Figure 3A The corresponding partial enlarged top view ( Figure 2B corresponding figure). Figure 4A Yes means Figure 3A Side view of the next step. Figure 4B is with Figure 4A The corresponding partial enlarged top view. Figure 5A Yes means Figure 4A Side view of the next step. Figure 5B is with Figure 5A The corresponding partial enlarged top view. Fig. 6A Yes means Figure 5A Side view of the next step. Figure 6B is with Fig. 6A The corresponding partial enlarged top view. Fig. 7A Yes means Fig. 6A Side view of the next step. Figure 7B is with Fig. 7A The corresponding partial enlarged top view.

[0046] like Figure 2A and Figure 2B As shown, the position and posture of the robot 2 are moved so that the final drive axis of the robot system 1 (robot 2 equipped with an arm 3), that is, the seventh axis J7, is perpendicular to the reference plane R1 of the base 21 of the robot 2. In addition, when the seventh axis J7 is perpendicular to the reference plane R1, the sixth axis J6 and the eighth axis J8 are also perpendicular to the reference plane R1. As an orthogonal coordinate system that serves as a reference for the robot, an Xt-Yt coordinate system (origin: Ot) is set. The reference plane R1 is parallel to the Xt-Yt plane. The angle formed by the Xt axis and the long side direction of the first arm 31 is called θ1. The angle formed by the long side direction of the first arm 31 and the long side direction of the second arm 32 is called θ2.

[0047] like Figure 3A as well as Figure 3B As shown, the clamp 33 of the arm 3 clamps the device side pin Q1. The front end of the device side pin Q1 faces the reference plane R1. In addition, a platform having a second reference plane R2 parallel to the reference plane R1 is placed on the reference plane R1. A target pin Q2 that is paired with the device side pin Q1 is placed on the second reference plane R2. The front end of the target pin Q2 faces the opposite side of the reference plane R1. The position of the front end of the target pin Q2, that is, the projection position onto the reference plane R1 (the second reference plane R2) is referred to as "position P1".

[0048] The position J8 of the gripper 33 of the arm 3 (which is the position of the front end of the device side pin Q1 and the projection position onto the reference plane R1 (second reference plane R2)) is moved to the position P1, so that the front end of the device side pin Q1 is butted against the front end of the target pin Q2. In this state, the angle formed by the Xt axis and the long side direction of the first arm 31 is called θ11, and the angle formed by the long side direction of the first arm 31 and the long side direction of the second arm 32 is called θ21.

[0049] like Figure 4A and Figure 4B As shown, the robot 2 is moved by the amount +X2 in the +Xt direction of the orthogonal coordinate system while maintaining the posture of the arm 3 (while maintaining the angles θ11 and θ12). In this state, the position of the tip of the device-side pin Q1, i.e., the projection position onto the reference plane R1 (second reference plane R2), is stored as "position P2".

[0050] like Figure 5A and Figure 5BAs shown, while maintaining the position and posture of the robot 2, the position J8 of the gripper 33 of the arm 3 is moved by the amount -X2 in the -Xt direction of the orthogonal coordinate system to the position P1 of the front end of the device side pin Q1. Then, the front end (J8) of the device side pin Q1 is docked with the front end (P1) of the target pin Q2 again. At this time, the angle θ12 formed by the Xt axis and the long side direction of the first arm 31 is larger than the angle θ11 (θ12>θ11), and the angle θ22 formed by the long side direction of the first arm 31 and the long side direction of the second arm 32 is smaller than the angle θ21 (θ22<θ21).

[0051] like Fig. 6A as well as Figure 6B As shown in FIG. 1 , the robot 2 is moved by a movement amount +X3 in the +Xt direction of the orthogonal coordinate system while maintaining the posture of the arm 3 (while maintaining the angles θ21 and θ22). In this state, the position of the tip of the device-side pin Q1, i.e., the projection position onto the reference plane R1 (second reference plane R2), is stored as "position P3".

[0052] like Fig. 7A and Figure 7B As shown, while maintaining the position and posture of the robot 2, the position J8 of the gripper 33 of the arm 3 is moved by a movement amount -X3 in the -Xt direction of the orthogonal coordinate system to the position P1 of the front end of the device side pin Q1. Then, the front end (J8) of the device side pin Q1 is docked with the front end (P1) of the target pin Q2 again. At this time, the angle θ13 formed by the Xt axis and the long side direction of the first arm 31 is larger than the angle θ12 (θ13>θ12), and the angle θ23 formed by the long side direction of the first arm 31 and the long side direction of the second arm 32 is smaller than the angle θ22 (θ23<θ22).

[0053] Based on the movement amount of the arm 3 related to the three positions P1, P2, and P3, the angle between the reference direction of the robot 2 and the reference direction of the arm 3 is calculated. Then, the zero point calibration is performed in such a way that the angle is zero, that is, in such a way that the two reference directions are consistent. In short, the information of the reference direction of the robot 2, that is, the reference direction information, is obtained from the movement of the robot 2, and the zero point calibration of the arm 3 as an example of a processing tool is performed based on the obtained reference direction information.

[0054] The zero point calibration of this embodiment can be easily performed on the processing tool, i.e., the arm 3, which is mounted on the front end portion 24 of the robot 2 having a drive shaft. As a result, the man-hours for the action confirmation after the zero point calibration and the correction operation of the zero point calibration are reduced, and the efficiency of the zero point calibration operation can be achieved. In particular, even when the arm 3 is not marked or there is no dedicated fixture, the zero point calibration operation can be easily performed. By eliminating the mark or the dedicated fixture, cost reduction can be achieved.

[0055] [Second application example]

[0056] Next, a second application example in which the zero point calibration method of the processing tool of the present invention is applied to a robot system having a robot and a rotating wedge scanner is described. The zero point calibration method of the processing tool of the present invention can also be applied to a processing tool having a processing head having an optical component capable of transmitting or reflecting laser light and being rotatable around a rotation axis, and a focusing optical system for focusing the laser light.

[0057] In the description of the second application example and thereafter, the same reference numerals are given to the same components as those of the first application example, and the description thereof will be omitted or simplified.

[0058] Figure 8 It is a principle diagram of a rotary wedge scanner according to a second application example of the present invention. Fig.9A This is a side view showing one step of the zero point calibration operation of the robot system according to the second application example. Fig. 9B is with Fig.9A The corresponding partial enlarged top view. Fig. 10A Yes means Fig.9A Side view of the next step. Fig. 10B is with Fig. 10A The corresponding partial enlarged top view. Fig.11A Yes means Fig. 10A Side view of the next step. Fig. 11B is with Fig.11A The corresponding partial enlarged top view.

[0059] A rotary wedge scanner (sometimes also called a "punch scanner") as an example of a processing tool can refract incident laser light and irradiate it at any position by rotating a lens with a tilted surface, for example, by a motor. Figure 8 As shown, in the rotating wedge scanner 6, two prism lenses 61a and 61b (hereinafter, both are sometimes collectively referred to as "prism lenses 61") and a condenser lens 62 are arranged to overlap each other in such a manner that the laser light L is incident in the thickness direction of the lens, and the two prism lenses 61a and 61b rotate around the rotation axis J11. Thus, the irradiation position (processing position) can be controlled on a two-dimensional plane.

[0060] The prism lens 61 is formed in a circular shape when viewed from the rotation axis direction, for example. The thickness of the prism lens 61 changes continuously in the circumferential direction. The prism lens 61 is rotationally driven by a motor (not shown), and the thickness changes continuously along the rotation direction.

[0061] The laser light L incident on the prism lens 61 is refracted according to the refractive index of the prism lens 61 and emitted as refracted light. At this time, the beam position of the laser light L shifted by the refraction is related to the thickness of the prism lens 61. That is, the greater the thickness of the prism lens 61 at the incident position of the laser light L, the greater the shift in the beam position of the laser light L caused by the refraction, that is, the shift amount. By passing the laser light L through the prism lens 61 whose thickness changes continuously and periodically in the rotation direction, the beam position of the laser light L, that is, the irradiation position (processing position) of the laser light L can be changed continuously and periodically.

[0062] However, the rotary wedge scanner does not have a mark for the reference direction on the above-mentioned mechanism that adjusts the phase of the lens by a motor to control the direction in which the incident laser is emitted. Therefore, in the zero-point calibration operation, the guide laser is irradiated in a state perpendicular to the irradiation surface and in focus, and the irradiation position is adjusted while visually confirming the irradiation position. First, the relative angle between the lenses is adjusted to find the origin position, and finally the orthogonal action direction is adjusted. In the adjustment of the orthogonal action direction, the irradiation position of the guide laser is moved from the origin position in the orthogonal coordinate system to an arbitrary direction, and the angle of the moving direction relative to the reference direction is measured and recorded. After the irradiation position of the guide laser is moved to the origin position, the recorded value of the angle is set in the robot control device 41, and the zero-point calibration is completed.

[0063] The following is a specific example. Fig.9A as well as Fig. 9B As shown, the three-dimensional orthogonal coordinate system of XR-YR-ZR (origin: OR) is set as the reference coordinate system of the robot. In addition, the Xt-Yt orthogonal coordinate system (origin Ot) is set as the reference coordinate system of the rotating wedge scanner 6. The reference plane R1 is parallel to the XR-YR plane and the Xt-Yt plane.

[0064] The origin position of the rotary wedge scanner 6 is aligned. Then, the position and posture of the robot 2 connected to the rotary wedge scanner 6 are moved so that the guide laser L is irradiated to the flat reference surface R1. This position is stored as position P1. A mark is added to the irradiation position P1 of the guide laser L.

[0065] like Fig. 10A and Fig. 10B As shown in FIG. 1 , the robot 2 is moved in an arbitrary direction (for example, +XR direction) of the orthogonal coordinate system while maintaining the posture of the rotary wedge-shaped scanner 6 . As a result, the irradiation position is moved to P2 .

[0066] like Fig.11A as well as Fig. 11B As shown, the irradiation position of the guide laser light L emitted from the rotary wedge scanner 6 is moved to the irradiation position P1 while the position and posture of the robot 2 are maintained.

[0067] The angle Δθ formed by the reference direction of the robot 2 and the reference direction of the rotating wedge scanner 6 is calculated based on the movement amount ΔP of the irradiation position of the guide laser L. Then, the zero point calibration is performed in such a manner that the angle Δθ becomes zero, that is, in such a manner that the two reference directions are consistent. In short, the reference direction information as the information of the reference direction of the robot 2 is obtained from the movement of the robot 2, and the zero point calibration of the rotating wedge scanner 6 as an example of a processing tool is performed based on the obtained reference direction information.

[0068] In the second application example, the same effect as in the first application example is achieved. In addition, the zero point calibration operation can be easily performed regardless of whether it is difficult for the operator to identify the reference direction, an environment where no dedicated equipment is prepared for maintenance after the introduction of the device, or an environment where the zero point calibration operation is time-consuming.

[0069] [Third Application Example]

[0070] Next, a third application example in which the zero-point calibration method of a processing tool according to the present invention is applied to a robot system including a robot and a galvano-scanner will be described. Fig.12 This is a schematic diagram of a galvano-scanner according to a third application example of the present invention.

[0071] Regarding the third application example, the structure and principle of the galvano scanner 7 as an example of a processing tool will be described easily. Fig.12 As shown, the galvano scanner 7 is a scanner that receives the laser light L emitted from the laser oscillator 76 and can scan the laser light L on the workpiece W. The galvano scanner 7 includes: two galvano mirrors 71 and 72 that reflect the laser light L emitted from the laser oscillator 76; galvano mirror motors 74 and 75 that respectively drive the galvano mirrors 71 and 72 to rotate; and a focusing lens 73. The focusing lens 73 is sequentially reflected by the galvano mirrors 71 and 72 to transmit the laser light L toward the workpiece W, and focuses the light.

[0072] The galvano mirrors 71 and 72 are configured to be rotatable about two rotation axes J21 and J22 that are orthogonal to each other. The galvano mirror motors 74 and 75 are rotationally driven based on drive data from the tool control device 42 to rotate the galvano mirrors 71 and 72 independently about the rotation axes J21 and J22.

[0073] The laser light L emitted from the laser oscillator 76 is sequentially reflected by the two galvano mirrors 71 and 72, and then emitted from the focusing lens 73 of the galvano scanner 7 to reach the processing position (welding point, processing position) of the workpiece W. At this time, when the two galvano mirrors 71 and 72 are rotated by the galvano mirror motors 74 and 75, respectively, the incident angle of the laser light L incident on these galvano mirrors 71 and 72 changes continuously. As a result, the laser light L is scanned from the galvano scanner 7 along a predetermined path relative to the workpiece W, and a welding track is formed on the workpiece W along the scanning path of the laser light L. The scanning path of the laser light L emitted from the galvano scanner 7 to the workpiece W can be arbitrarily changed in the X and Y directions by appropriately controlling the rotation drive of the galvano mirror motors 74 and 75 to change the rotation angle of each of the galvano mirrors 71 and 72.

[0074] The third application example also has the same effects as those of the second application example.

[0075] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. In addition, the effects described in the embodiments are merely the most preferred effects produced by the present invention, and the effects of the present invention are not limited to the effects described in the embodiments.

[0076] Description of Reference Numerals

[0077] 2Robots,

[0078] 3 arms (handling tools),

[0079] 6 Rotating wedge scanner (processing tool),

[0080] 7Electronic scanner (processing tool),

[0081] 24 Robot arm front end portion (arm front end portion).

Claims

1. A method for zero-point calibration of a processing tool, comprising controlling a processing tool for performing a predetermined processing on a processing object to be processed at the front end of an arm, and the driving unit of a multi-jointed robot having at least one driving unit for driving a single or multiple driving axes, and controlling the driving unit of the processing tool, thereby performing zero-point calibration of the processing tool so that a reference direction of the processing tool is consistent with a reference direction of the robot, characterized in that: Information on the reference direction of the robot, that is, reference direction information, is acquired from the movement of the robot, and zero point calibration of the processing tool is performed based on the acquired reference direction information.

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