Origin calibration method and origin calibration system

Abstract

To provide an origin calibration method and an origin calibration system that can perform calibration with excellent accuracy.SOLUTION: An origin calibration method for a scalar robot includes: a detection step of detecting a reference jig arranged at a reference position and a leading end of the scalar robot simultaneously with an optical sensor; and a calibration step of performing origin calibration for the scalar robot based on a result of the detection step. The optical sensor comprises two sets of sensor units that are arranged opposite to each other across the reference jig and include a light emitting device and a light receiving device. The two sets of sensor units are arranged with their optical axes orthogonal to each other.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present invention relates to an origin calibration method and an origin calibration system. [Background technology]

[0002] Patent Document 1 describes a method for calibrating the origin of an articulated robot by bringing a jig shaft into contact with the articulated robot. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-004179 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the method of calibrating the origin of an articulated robot disclosed in Patent Document 1, there is a risk that the accuracy of the origin calibration will decrease due to machining errors in the jig shaft. [Means for solving the problem]

[0005] The origin calibration method of the present invention is a method for calibrating an origin of a SCARA robot, comprising the steps of: a detection step of simultaneously detecting a reference jig disposed at a reference position and a tip end of the SCARA robot by an optical sensor; and a calibration step of performing origin calibration of the SCARA robot based on the result of the detection step.

[0006] The origin calibration system of the present invention includes a reference jig disposed at a reference position; an optical sensor that simultaneously detects the reference jig and the tip of the SCARA robot; and a processing unit that performs origin calibration of the SCARA robot based on the detection result of the optical sensor. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram of a robotic inspection system according to a preferred embodiment. [Diagram 2] FIG. 2 is a side view showing an example of a robot inspected by the robot inspection system. [Diagram 3] FIG. 3 is an enlarged view of the robot shown in FIG. 2. [Figure 4] FIG. 2 is a side view showing the mounting table and the automated guided vehicle. [Diagram 5] FIG. 13 is a side view showing a state in which the mounting table is raised on the automatic transport vehicle. [Figure 6] FIG. 1 is a top view of a robotic inspection system. [Figure 7] FIG. 2 is a top view showing a state in which the mounting table is connected to the robot inspection system. [Figure 8] FIG. 13 is a diagram showing operations carried out in a third area. [Figure 9] FIG. 13 is a diagram showing operations carried out in a third area. [Figure 10] FIG. 2 is a top view showing the first region. [Figure 11] FIG. [Figure 12] FIG. 2 is a schematic diagram showing the structure of a sensor unit. [Figure 13] 13 is a flowchart showing an origin calibration method for a SCARA robot. [Figure 14] 11 is a perspective view showing a state in which the tip of the robot is positioned within a measurement area of ​​an optical sensor. FIG. [Figure 15] 13 is a flowchart showing an arm length measurement step. [Figure 16] FIG. 4 is a diagram illustrating an example of an image acquired by an optical sensor. [Figure 17] FIG. 4 is a diagram illustrating an example of an image acquired by an optical sensor. [Figure 18] FIG. 4 is a diagram illustrating an example of an image acquired by an optical sensor. [Figure 19] FIG. 4 is a diagram illustrating an example of an image acquired by an optical sensor. [Figure 20]FIG. 11 is a top view showing an origin calibration system according to a second embodiment. [Figure 21] FIG. 11 is a top view showing an origin calibration system according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an origin calibration method and an origin calibration system according to the present invention will be described in detail based on the embodiments shown in the accompanying drawings.

[0009] First Embodiment FIG. 1 is a configuration diagram of a robot inspection system according to a preferred embodiment. FIG. 2 is a side view showing an example of a robot inspected by the robot inspection system. FIG. 3 is an enlarged view of the robot shown in FIG. 2. FIG. 4 is a side view showing a mounting table and an automatic guided vehicle. FIG. 5 is a side view showing a state in which the mounting table is lifted by the automatic guided vehicle. FIG. 6 is a top view of the robot inspection system. FIG. 7 is a top view showing a state in which the mounting table is connected to the robot inspection system. FIG. 8 and FIG. 9 are each a diagram showing an operation performed in the third area. FIG. 10 is a top view showing the first area. FIG. 11 is a perspective view of a reference pin. FIG. 12 is a schematic diagram showing the structure of a sensor unit. FIG. 13 is a flowchart showing an origin calibration method for a SCARA robot. FIG. 14 is a perspective view showing a state in which the tip of the robot is positioned within the measurement area of ​​an optical sensor. FIG. 15 is a flowchart showing an arm length measurement step. FIG. 16 to FIG. 19 are each a diagram showing an example of an image acquired by an optical sensor.

[0010] As shown in Fig. 1, Fig. 6 to Fig. 10, three mutually orthogonal axes are illustrated as the X-axis, the Y-axis, and the Z-axis. In the following, the direction along the X-axis is also referred to as the X-axis direction, the direction along the Y-axis is also referred to as the Y-axis direction, and the direction along the Z-axis is also referred to as the Z-axis direction. The arrow side of each axis is also referred to as the plus side, and the opposite side is also referred to as the minus side. The Z-axis direction is aligned along the vertical direction.

[0011] The robot inspection system 1 shown in Fig. 1 is an apparatus that performs a predetermined inspection on a SCARA robot 3 that has been transported while placed on a mounting table 2. That is, rather than performing inspection for each SCARA robot 3 at the location where each SCARA robot 3 is installed as in the conventional method, all SCARA robots 3 are transported to the robot inspection system 1 for inspection. With such a system, all SCARA robots 3 can be inspected in the same location and in the same environment, making it less likely that the inspection accuracy will vary for each SCARA robot 3. Therefore, stable and highly accurate inspection can be performed on all SCARA robots 3.

[0012] Below, we will explain the robot inspection system 1 in detail, but before that, we will briefly explain the SCARA robot 3 to be inspected, the mounting table 2 on which the SCARA robot 3 is placed, and the automatic guided vehicle 4 (AGV: Automatic Guided Vehicle) that transports the mounting table 2 to the robot inspection system 1.

[0013] [Scara Robot 3] As shown in Figure 2, the SCARA robot 3 has a base 30, a first arm 31 whose base end is connected to the base 30 and rotates around a first rotation axis J1 that is vertical to the base 30, and a second arm 32 whose base end is connected to the tip end of the first arm 31 and rotates around a second rotation axis J2 that is vertical to the first arm 31.

[0014] The SCARA robot 3 also has a work head 33 arranged at the tip of the second arm 32. The work head 33 has a spline nut 331 and a ball screw nut 332 arranged coaxially, and a spline shaft 333 inserted through the spline nut 331 and the ball screw nut 332. The spline shaft 333 is rotatable about a third rotation axis J3, which is the central axis of the second arm 32 and extends along the Z-axis direction, and is also movable up and down along the third rotation axis J3.

[0015] The SCARA robot 3 also has a first joint drive mechanism 361 that connects the base 30 and the first arm 31 and rotates the first arm 31 relative to the base 30 around a first rotation axis J1, a second joint drive mechanism 362 that connects the first arm 31 and the second arm 32 and rotates the second arm 32 relative to the first arm 31 around a second rotation axis J2, a first head drive mechanism 363 that rotates the spline nut 331 to rotate the spline shaft 333 around a third rotation axis J3, and a second head drive mechanism 364 that rotates the ball screw nut 332 to raise and lower the spline shaft 333 in a direction along the third rotation axis J3.

[0016] Each of the drive mechanisms 361, 362, 363, and 364 has a motor as a drive source and a pulse encoder that detects the rotation of the motor. Therefore, the first joint drive mechanism 361 can detect the rotation angle of the first arm 31 about the first rotation axis J1 by counting the pulse signals output by the pulse encoder. The second joint drive mechanism 362 can detect the rotation angle of the second arm 32 about the second rotation axis J2 by ​​counting the pulse signals output by the pulse encoder. The first head drive mechanism 363 can detect the rotation angle of the spline shaft 333 about the third rotation axis J3 by counting the pulse signals output by the pulse encoder. The second head drive mechanism 364 can detect the height of the spline shaft 333 in the Z-axis direction by counting the pulse signals output by the pulse encoder.

[0017] The SCARA robot 3 also has a robot controller 37 that independently controls each of the drive mechanisms 361, 362, 363, and 364 based on position commands from a host computer (not shown). The robot controller 37 is, for example, composed of a computer, and has a processor that processes information, a memory communicatively connected to the processor, and an external interface that connects to an external device. Various programs that can be executed by the processor are stored in the memory, and the processor can read and execute the various programs stored in the memory.

[0018] As shown in FIG. 3, the SCARA robot 3 has a cover 34 disposed on the underside of the second arm 32, which covers the gap between the second arm 32 and the spline shaft 333. A downward triangular marker 341 is formed on the cover 34 and is used in the inspection described below. The marker 341 can be formed by printing, pasting, embossing, or the like. However, the configuration of the marker 341 is not particularly limited as long as it can be used in the inspection described below. Furthermore, if the cover 34 has a unique part in its shape, that part may be used as the marker 341.

[0019] Moreover, the SCARA robot 3 has a stopper 35 disposed midway along the spline shaft 333. When the stopper 35 comes into contact with the cover 34, the spline shaft 333 is restricted from moving further upward. The stopper 35 is a C-shaped member having both ends connected by a screw N1, and is fixed to the spline shaft 333 by tightening the screws. When the stopper 35 is fixed to the spline shaft 333, both ends of the stopper 35 are spaced apart from each other, forming a gap 350 therebetween. This gap 350 functions as a positioning mark used in the inspection described below. However, the configuration of the stopper 35 is not particularly limited as long as it can exert the above-mentioned effects.

[0020] The above describes the SCARA robot 3. However, there is no particular limitation on the configuration of the SCARA robot 3. For example, it may be a robot other than a SCARA robot, specifically a six-axis articulated robot, a dual-arm robot, or the like.

[0021] [Placement table 2] As shown in FIG. 4, the mounting table 2 has a top plate 21 on which the SCARA robot 3 is placed and fixed, a bottom plate 22 located below the top plate 21, and four legs 23 supporting the top plate 21 and the bottom plate 22. The four legs 23 are located at the four corners of the top plate 21 and the bottom plate 22, and support them in a well-balanced manner. In FIG. 4, only the two legs 23 on the front side are shown, but two legs 23 are similarly arranged on the back side. In addition, casters 24 are attached to the lower end of each leg 23, and the mounting table 2 can be freely moved by rotating the casters 24. Such a mounting table 2 may be, for example, a work table for assembling the SCARA robot 3, or may be an installation table for installing the SCARA robot 3 at a predetermined location.

[0022] The above has described the mounting table 2. However, the configuration of the mounting table 2 is not particularly limited as long as it is possible to mount the SCARA robot 3 thereon, and for example, the casters 24 may be omitted.

[0023] [Automated guided vehicle 4] As shown in Fig. 4, the automated guided vehicle 4 has a platform 41 on which the platform 2 is placed, a lifting device 42 for raising and lowering the platform 41, wheels 43, a motor 44 for driving the wheels 43, and a controller 45 for controlling the driving of the motor 44. As shown in Fig. 5, the automated guided vehicle 4 slips under the bottom plate portion 22 of the platform 2 with the platform 41 lowered, and then raises the platform 41 with the lifting device 42, thereby lifting the platform 2 so as to support the bottom plate portion 22 from below. The automated guided vehicle 4 also receives instructions on a travel route from a management device (not shown) and travels according to the received travel route.

[0024] By using such an automatic guided vehicle 4, the SCARA robot 3 can be automatically transported together with the mounting table 2 to the robot inspection system 1. This eliminates the need for an operator to manually push the mounting table 2 to move it to the robot inspection system 1, thereby reducing manpower and enabling the inspection of the SCARA robot 3 to be carried out smoothly.

[0025] The above describes the automated guided vehicle 4. However, the configuration of the automated guided vehicle 4 is not particularly limited as long as it can transport the SCARA robot 3 together with the mounting table 2 to the robot inspection system 1. Also, the automated guided vehicle 4 may be omitted, and the worker may push the mounting table 2 himself to transport it to the robot inspection system 1.

[0026] [Robot Inspection System 1] As shown in FIG. 1, the robot inspection system 1 is placed in an inspection room 10 maintained in a predetermined environment. This allows inspection of multiple SCARA robots 3 under the same conditions, further improving the inspection accuracy. In addition, a vibration damping member 11 is placed between the floor of the inspection room 10 and the robot inspection system 1. This makes it difficult for external vibrations to be transmitted to the robot inspection system 1 through the floor, further improving the inspection accuracy. In this embodiment, a metal plate, particularly an iron plate, is used as the vibration damping member 11. In addition, this iron plate is fixed to the floor by an anchor, and the robot inspection system 1 is fixed to the iron plate by the anchor. However, the installation location of the robot inspection system 1 is not particularly limited. In addition, the vibration damping member 11 may be omitted, and the robot inspection system 1 may be installed directly on the floor.

[0027] As shown in FIG. 6, the robot inspection system 1 also has a connection section 5 to which the mounting table 2 is connected, a positioning mechanism 6 that positions the mounting table 2 relative to the connection section 5, and an inspection section 7 that inspects the SCARA robot 3.

[0028] The connection part 5 has a recess 51 with an entrance 511 through which the mounting table 2 enters, as viewed in a plan view from the Z-axis direction. In this embodiment, the entrance 511 is located on the negative side of the connection part 5 in the Y-axis direction. The inspection part 7 is arranged around the recess 51. By arranging the inspection part 7 around the connection part 5 in this manner, the inspection of the SCARA robot 3 can be efficiently performed. In particular, since the first and second arms 31 and 32 of the SCARA robot 3 move only in the horizontal direction, by arranging the inspection part 7 around the recess 51 in a plan view, the inspection part 7 can be efficiently arranged within the movable range of the SCARA robot, and can be specialized for the inspection of the SCARA robot 3. However, the arrangement of the inspection part 7 is not particularly limited.

[0029] A positioning mechanism 6 is also disposed in the recess 51. The positioning mechanism 6 positions the mounting table 2 transported into the recess 51 with respect to the connection portion 5. This determines the position of the SCARA robot 3 with respect to the robot inspection system 1. Therefore, all SCARA robots 3 can be disposed in the same position, improving the inspection accuracy. The positioning mechanism 6 of this embodiment has a pair of abutting portions 61, 62 protruding into the recess 51. As shown in FIG. 7, the mounting table 2 is positioned with respect to the connection portion 5 by abutting the abutting portions 61, 62. However, the configuration of the positioning mechanism 6 is not particularly limited as long as it can position the mounting table 2 with respect to the connection portion 5. The positioning mechanism 6 may be omitted.

[0030] The inspection unit 7 performs a predetermined inspection of the SCARA robot 3 on the mounting table 2 connected to the connection unit 5. In this specification, "inspection" is meant to include all actions necessary for the setting and maintenance of the SCARA robot 3, such as various checks, various maintenance, various preparations, various measurements, and various calibrations, in addition to inspection.

[0031] Furthermore, the inspection unit 7 performs a plurality of types of inspections on the SCARA robot 3. As shown in Fig. 6, the inspection unit 7 has a first region R1 located on the positive side of the Y axis direction of the recess 51, a second region R2 located on the negative side of the X axis direction of the first region R1, and a third region R3 located on the positive side of the X axis direction of the first region R1.

[0032] Of these regions R1, R2, and R3, the second region R2 is a region where preparations for the inspection in the first region R1 are made. In the second region R2, a task of attaching a weight M to the spline shaft 333 is performed. As shown in Fig. 6, the second region R2 is provided with the weight M, a tool T for fixing the weight M to the spline shaft 333, and a moving mechanism 80 for moving the tool T.

[0033] However, the configuration of the second region R2 is not particularly limited. For example, the number and shape of the weights M, the method of attaching the weights M to the spline shaft 333, etc. are not particularly limited. In addition, the work performed in the second region R2 is also not particularly limited, and can be appropriately set based on various conditions required for the SCARA robot 3, the work performed in the other regions R1 and R3, etc. In addition, the second region R2 may be omitted.

[0034] The third region R3 is a region where origin calibration of the third rotation axis J3 is performed. The origin calibration of the third rotation axis J3 refers to the operation of matching the origin of the third rotation axis J3 stored in the robot controller 37 (hereinafter also referred to as the "ideal origin") with the actual origin (hereinafter also referred to as the "actual origin") when the third rotation axis J3 is positioned at the ideal origin under the control of the robot controller 37. The ideal origin refers to a state in which each motor of the first and second head drive mechanisms 363 and 364 is in a predetermined position (hereinafter referred to as the "0 pulse position"). However, the method of setting the origin of the third rotation axis J3 is not particularly limited.

[0035] As shown in FIG. 6, in such a third region R3, a rotation angle calibration unit 81 that calibrates the rotation angle of the spline shaft 333 and a height calibration unit 82 that calibrates the height of the spline shaft 333 are arranged.

[0036] 8, the rotation angle calibration unit 81 uses an image recognition technique to calibrate the rotation angle of the spline shaft 333. The rotation angle calibration unit 81 has a camera 811 that captures an image of the spline shaft 333 from the horizontal direction, a movement mechanism 813 that moves the camera 811 in the X-axis direction and the Z-axis direction, and a processing unit 812 that uses the image captured by the camera 811 (hereinafter referred to as the "acquired image") to determine the amount of deviation (deviation) between the ideal origin and the actual origin.

[0037] The processing unit 812 stores a large number of comparison images in which the rotation angles of the spline shaft 333 from the ideal origin are different from one another and known. The processing unit 812 then calibrates the rotation angle of the spline shaft 333 by comparing these comparison images with the acquired image captured by the camera 811 using a template matching technique.

[0038] Specifically, first, the motor of the first head driving mechanism 363 is set to the 0 pulse position using the robot controller 37. Next, the camera 811 captures the state in which the marker 341 and the gap 350 between the stopper 35 are in the field of view to obtain an acquired image. Next, the processing unit 812 performs template matching on the acquired image with a number of comparison images, and extracts one comparison image that has the highest similarity to the acquired image from among them. Then, the rotation angle from the ideal origin corresponding to the extracted comparison image is determined as the rotation offset value of the third rotation axis J3. Then, the determined rotation offset value of the third rotation axis J3 is set in the robot controller 37. With the above, the rotation angle calibration work of the third rotation axis J3 is completed. However, the method of calibrating the rotation angle of the third rotation axis J3 is not particularly limited.

[0039] Also, as shown in FIG. 9, the height calibration unit 82 has a pair of contact-type distance sensors 821, 822, a moving mechanism 824 that moves the pair of contact-type distance sensors 821, 822 in the X-axis and Z-axis directions, and a processing unit 823 that calculates the amount of deviation (deviation) between the ideal origin and the actual origin based on the output of the contact-type distance sensors 821, 822.

[0040] The contact type distance sensors 821 and 822 can accurately measure the amount of pressing of the tip. For example, Keyence Corporation's "General-purpose contact type digital sensor / GT series" can be suitably used as such contact type distance sensors 821 and 822. These contact type distance sensors 821 and 822 are arranged apart from each other in the Z-axis direction and both face upward.

[0041] In the height calibration operation, first, the motor of the second head driving mechanism 364 is set to the 0 pulse position using the robot controller 37. Next, the contact type distance sensor 821 is brought into contact with the lower surface of the second arm 32, and the contact type distance sensor 822 is brought into contact with the tip of the spline shaft 333. Next, the processing unit 823 calculates the actual distance (hereinafter also referred to as the "actual distance") between the lower surface of the second arm 32 and the tip of the spline shaft 333 from the separation distance of the contact type distance sensors 821 and 822 and their output values. The processing unit 823 also stores the ideal distance (hereinafter also referred to as the "ideal distance") between the lower surface of the second arm 32 and the tip of the spline shaft 333 when the motor of the second head driving mechanism 364 is in the 0 pulse position, and determines the deviation amount between the actual distance and the ideal distance as the height offset value of the third rotation axis J3. Then, the determined height offset value of the third rotation axis J3 is set in the robot controller 37. With the above, the height calibration operation of the third rotation axis J3 is completed. However, the method of calibrating the height of the third rotation axis J3 is not particularly limited.

[0042] The third area R3 has been described above. However, the configuration of the third area R3 is not particularly limited. For example, either the rotation angle calibration unit 81 or the height calibration unit 82 may be omitted. In addition, the work performed in the third area R3 is not particularly limited, and can be appropriately set based on various conditions required for the SCARA robot 3, the work performed in the other areas R1 and R2, etc. In addition, the third area R3 may be omitted.

[0043] The first area R1 is an area where origin calibration of the SCARA robot 3, specifically, origin calibration of the first and second rotation axes J1 and J2, is performed. In this embodiment, various inspections are performed in the first area R1 in addition to origin calibration of the SCARA robot 3. As shown in Fig. 10, an origin calibration system 99 is disposed in the first area R1.

[0044] The origin calibration system 99 includes a stage 90 movable in the Y-axis direction relative to the connection part 5, a calibration device 94 including a reference pin 91 as a reference jig and an optical sensor 98 arranged on the stage 90, and a processing unit 95 for processing an image captured by the optical sensor 98. By arranging the calibration device 94 on the stage 90, the distance between the connection part 5 and the calibration device 94 becomes variable, so that it is possible to accommodate SCARA robots 3 of various sizes. This increases the versatility of the robot inspection system 1. In addition, by moving the stage 90 to the Y-axis positive side and away from the connection part 5 when connecting the mounting table 2 to the connection part 5, it is possible to avoid a collision between the calibration device 94 and the SCARA robot 3. This makes it possible to suppress breakdowns and damage to the robot inspection system 1 and the SCARA robot 3.

[0045] However, the present invention is not limited to this, and the stage 90 may be fixed and unable to move in the Y-axis direction, or may be configured so that the stage 90 can also move in the X-axis direction.

[0046] The reference pin 91 is disposed at the center of the stage 90. As shown in FIG. 11, the reference pin 91 is a column extending in the Z-axis direction, and is L-shaped bent at a right angle in a plan view from the Z-axis direction. The reference pin 91 has a first outer surface 911 and a second outer surface 912 that are perpendicular to each other. A normal line Q1 of the first outer surface 911 and a normal line Q2 of the second outer surface 912 are inclined at 45° with respect to the X-axis and the Y-axis, respectively. Such a reference pin 91 is a pin that serves as a reference for origin calibration, and its position coordinates in the robot coordinate system are known. The reference pin 91 is formed with sufficiently high dimensional accuracy. However, the shape of the reference pin 91 is not particularly limited as long as it can be used in the inspection described later. The material of the reference pin 91 is not particularly limited, and for example, various metal materials, various resin materials, various glass materials, etc. can be used.

[0047] 10, the optical sensor 98 has two pairs of sensor units 92 and 93. The sensor units 92 and 93 are arranged in a cross shape so that their optical axes O1 and O2 are perpendicular to each other, and a reference pin 91 is located at the intersection of the optical axes O1 and O2. Furthermore, the optical axis O1 of the sensor unit 92 coincides with the normal line Q1, and the optical axis O2 of the sensor unit 93 coincides with the normal line Q2.

[0048] 12, the sensor unit 92 is a dimension measuring instrument, and has a light emitting device 921 and a light receiving device 922 disposed opposite each other via a reference pin 91. The light emitting device 921 and the light receiving device 922 are disposed facing each other along a normal line Q1.

[0049] The light emitting device 921 emits light LL1 toward the light receiving device 922. The light emitting device 921 also includes a light source 921a and a light emitting side telecentric optical system 921b. The light source 921a is a green LED and emits green light LL1. By using a green LED as the light source 921a, it is possible to stably emit light LL1 of a color suitable for measurement and with a sufficient amount of light. The light emitting side telecentric optical system 921b also includes a lens group including a plurality of lenses, and converts the light LL1 emitted from the light source 921a into uniform parallel light and emits it.

[0050] On the other hand, the light receiving device 922 includes an image sensor 922a and a light receiving telecentric optical system 922b that forms an image of the light LL1 on the image sensor 922a. The image sensor 922a is a CMOS sensor. The light receiving telecentric optical system 922b has a lens group including a plurality of lenses, and forms an image of only parallel light on the image sensor 922a. During origin calibration of the SCARA robot 3, the measurement area (field of view) of the image sensor 922a includes the tip of the reference pin 91 and the tip of the spline shaft 333, and captures silhouette images of these, that is, images in which the reference pin 91 and the spline shaft 333 are cast as shadows. That is, since the light emitting devices 921 and 931 are of a transmitted illumination type, it is possible to avoid halation even if the measurement target is metal, and it is possible to clearly observe the contour.

[0051] In this way, the sensor unit 92 is a double telecentric optical system equipped with telecentric optical systems on both the light-emitting side and the light-receiving side. This allows the edge of the object in the measurement area to be sharply imaged, and also ensures a deep depth of field. Therefore, as described later, the edges of both the reference pin 91 and the spline shaft 333 can be clearly imaged. The depth of field is not particularly limited, but is preferably, for example, ±2.0 mm or more. This provides a depth of field sufficient for use in origin calibration of the SCARA robot 3.

[0052] In addition, since the sensor unit 92 is a double telecentric optical system, theoretically the image sensor 922a receives only parallel light, so that the structure is resistant to ambient light, and furthermore, the size of the image formed is unlikely to change even if thermal expansion occurs. Therefore, the influence of temperature change can be minimized, and highly accurate measurements can be performed. In addition, since the sensor unit 92 is a double telecentric optical system, the exposure time can be shortened. This reduces image blurring, and a clear image can be captured. The exposure time is not particularly limited, but is preferably, for example, 100 μsec or less.

[0053] The imaging element 922a has a circular measurement area. The size of the measurement area is not particularly limited, but for example, the diameter is preferably 25 mm or more and 125 mm or less, more preferably 40 mm or more and 125 mm or less, and even more preferably 60 mm or more and 125 mm or less. By using such a shape and size, the measurement area is a size suitable for simultaneously imaging the reference pin 91 and the spline shaft 333. Therefore, it is possible to obtain an image that reliably contains necessary information while eliminating unnecessary information as much as possible, so that the origin calibration of the SCARA robot 3 can be performed accurately and smoothly.

[0054] Furthermore, the repeatability of the sensor unit 92 is not particularly limited, but is preferably ±0.2 μm or less, more preferably ±0.1 μm or less, and even more preferably ±0.05 μm or less. This allows the origin calibration of the SCARA robot 3 to be performed with high accuracy. Also, it is possible to effectively suppress calibration variations for each SCARA robot 3. Note that the repeatability refers to a value of ±2σ (where σ is the standard deviation) when the average number of measured values ​​is 16 for a 14 mm wide groove formed in a calibration glass scale, which is the standard measurement object at the center of the measurement area.

[0055] The sensor unit 93 has the same configuration as the sensor unit 92 described above. That is, the sensor unit 93 has a light emitting device 931 and a light receiving device 932 arranged opposite to each other via a reference pin 91. The light emitting device 931 also has a light source 931a that emits light LL2 and a light emitting side telecentric optical system 931b that converts the light LL2 into parallel light. On the other hand, the light receiving device 932 has an image sensor 932a and a light receiving side telecentric optical system 932b that forms an image of the light LL2 on the image sensor 932a. The configurations of the light emitting device 931 and the light receiving device 932 are the same as those of the light emitting device 921 and the light receiving device 922 of the sensor unit 92 described above, and therefore detailed description thereof will be omitted.

[0056] Although there is no particular limitation on such sensor units 92 and 93, in this embodiment, the "2D High Speed ​​Optical Sensor / TM Series" manufactured by Keyence Corporation, in particular the "TM-6050" can be suitably used. This provides excellent measurement accuracy and enables highly accurate origin calibration of the SCARA robot 3.

[0057] In order to improve the accuracy of the origin calibration of the SCARA robot 3, it is important to precisely orthogonally arrange the sensor units 92 and 93. In this embodiment, the sensor units 92 and 93 are positioned as follows. As described above, the sensor unit 92 captures a silhouette image of the reference pin 91. Here, when the optical axis O1 coincides with the normal line Q1, the width dimension of the reference pin 91 on the image acquired by the light receiving device 922 is smallest, and the more the optical axis O1 is inclined from the normal line Q1, the larger the width dimension of the reference pin 91 on the image. Therefore, the sensor unit 92 is arranged so that the width dimension of the reference pin 91 on the image acquired by the light receiving device 922 is smallest. Similarly, the sensor unit 93 is arranged so that the width dimension of the reference pin 91 on the image acquired by the light receiving device 932 is smallest. As described above, since the normal lines Q1 and Q2 are mutually orthogonal, this method allows the sensor units 92 and 93 to be precisely orthogonally arranged. However, the method for positioning the sensor units 92 and 93 is not particularly limited.

[0058] Next, various inspections performed in the first region R1 will be described in order. Note that, as described above, the various inspections performed in the first region R1 are performed in a state where the weight M is attached to the spline shaft 333.

[0059] In the first region R1, the origin calibration system 99 is used to perform origin calibration of the first and second rotation axes J1 and J2. The origin calibration of the first rotation axis J1 refers to the operation of matching the origin (hereinafter also referred to as the "ideal origin") of the first rotation axis J1 stored in the robot controller 37 with the real origin (hereinafter also referred to as the "real origin") when the first rotation axis J1 is positioned at the ideal origin under the control of the robot controller 37. The ideal origin refers to a state in which the motor of the first joint drive mechanism 361 is in a predetermined position (hereinafter referred to as the "0 pulse position"). Similarly, the origin calibration of the second rotation axis J2 refers to the operation of matching the origin (hereinafter also referred to as the "ideal origin") of the second rotation axis J2 stored in the robot controller 37 with the real origin (hereinafter also referred to as the "real origin") when the second rotation axis J2 is positioned at the ideal origin under the control of the robot controller 37. The ideal origin refers to a state in which the motor of the second joint drive mechanism 362 is in a predetermined position (hereinafter referred to as the "0 pulse position").

[0060] As shown in FIG. 13, origin calibration of the first and second rotating axes J1, J2 includes a detection step S1 in which the reference pin 91 and the tip of the spline shaft 333 (hereinafter also referred to as the "tip of the SCARA robot 3") are simultaneously detected by sensor units 92, 93, and a calibration step S2 in which origin calibration of the first and second rotating axes J1, J2 is performed based on the results of the detection step S1.

[0061] [Detection step S1] In the detection step S1, first, the stage 90 is moved to place the reference pin 91 at a reference position, which is a predetermined coordinate in the robot coordinate system. The reference position in this embodiment is located directly below the central axis of the spline shaft 333 when the motors of the first and second joint drive mechanisms 361 and 362 are both set to the 0 pulse position. However, the reference position is not particularly limited. Next, the motors of the first and second joint drive mechanisms 361 and 362 are set to the 0 pulse position using the robot controller 37. Next, the second head drive mechanism 364 is moved to lower the spline shaft 333, and the tip of the spline shaft 333 is positioned within the measurement area of ​​the sensor units 92 and 93, as shown in FIG. 14. If there is no deviation between the ideal origin and the real origin, in this state, the spline shaft 333 is positioned directly above the reference pin 91.

[0062] Next, this state is imaged by the light receiving device 922 to obtain an image G1 as shown in Fig. 16, and is also imaged by the light receiving device 932 to obtain an image G2 as shown in Fig. 17. As a result, images G1 and G2 are obtained in which the reference pin 91 and the tip of the SCARA robot 3 in the measurement area are simultaneously detected. The timing of imaging by the light receiving devices 922 and 932 is not particularly limited, and may be simultaneous or different. In the examples of Figs. 16 and 17, the third rotation axis J3, which is the central axis of the spline shaft 333, is shifted in the lateral direction of the image with respect to the central axis Jp of the reference pin 91, and a shift occurs between the ideal origin and the actual origin in at least one of the first and second rotation axes J1 and J2.

[0063] In this way, when the third rotation axis J3 is misaligned with the central axis Jp of the reference pin 91 in at least one of the images G1 and G2, the driving of the first and second joint drive mechanisms 361 and 362 and the acquisition of the images G1 and G2 by the light receiving devices 922 and 932 are repeated, and the third rotation axis J3 is aligned with the central axis Jp in each of the images G1 and G2, as shown in Figs. 18 and 19. In particular, as described above, since the optical axes O1 and O2 of the sensor units 92 and 93 are perpendicular to each other, the third rotation axis J3 can be aligned with the central axis Jp with higher accuracy while checking the images G1 and G2. At this time, the spline shaft 333 is not in contact with the reference pin 91.

[0064] [Calibration step S2] Next, the processing unit 95 stores the positions of the motors of the first and second joint drive mechanisms 361 and 362 when the third rotation axis J3 coincides with the central axis Jp as actual positions. Next, the processing unit 95 calculates the deviation (deviation) between the actual position of the motor of the first joint drive mechanism 361 and the 0 pulse position, and determines the calculated deviation as the offset value of the first rotation axis J1. Similarly, the processing unit 95 calculates the deviation (deviation) between the actual position of the motor of the second joint drive mechanism 362 and the 0 pulse position, and determines the calculated deviation as the offset value of the second rotation axis J2. Then, for example, the operator sets the offset values ​​of the first and second rotation axes J1 and J2 determined by the processing unit 95 in the robot controller 37. With the above, the origin calibration of the first and second rotation axes J1 and J2 is completed. The robot controller 37 controls the driving of the first and second joint drive mechanisms 361 and 362 so that the real origin coincides with the ideal origin based on the set offset value. This enables highly accurate control of the SCARA robot 3.

[0065] According to this method, origin calibration of the first and second rotation axes J1, J2 can be performed without the tip of the SCARA robot 3 coming into contact with the reference pin 91. Therefore, there is no displacement or distortion of the SCARA robot 3 due to contact with the reference pin 91, and there is no effect from machining errors of the reference pin 91, so origin calibration of the first and second rotation axes J1, J2 can be performed with high accuracy.

[0066] Furthermore, in the first region R1, the height of the spline shaft 333 is inspected using the origin calibration system 99. For example, when assembling the SCARA robot 3, the mounting position of the second head driving mechanism 364 may shift, and the height of the spline shaft 333 may accordingly shift from the design. Therefore, in this embodiment, the height deviation of the spline shaft 333 is inspected.

[0067] Specifically, first, the motor of the second head driving mechanism 364 is set to a preset measurement position, and the tip of the spline shaft 333 is positioned within the measurement area of ​​the sensor units 92, 93. Next, the processing unit 95 images this state with at least one of the sensor units 92, 93, and calculates the Z-axis position coordinate (hereinafter also referred to as the "actual position coordinate") of the tip of the spline shaft 333 based on the obtained image. The processing unit 95 previously stores the Z-axis position coordinate (hereinafter also referred to as the "ideal position coordinate") of the tip of the spline shaft 333 at the measurement position in an ideal state where there is no deviation in the mounting position of the second head driving mechanism 364, and measures the height deviation of the spline shaft 333 from the actual position coordinate and the ideal position coordinate.

[0068] Furthermore, in the first region R1, an origin calibration system 99 is used to inspect the height deviation of the left and right arm systems. For example, even if the tip of the spline shaft 333 (hereinafter also referred to as the "tip of the SCARA robot 3") is positioned at the same coordinate in the robot coordinate system, there may be a deviation in height of the tip of the SCARA robot 3 between the posture of the right arm system in which the first and second arms 31, 32 are bent on the positive side in the X-axis direction and the posture of the left arm system in which they are bent on the negative side in the X-axis direction. Therefore, in this embodiment, the height deviation of the left and right arm systems is inspected.

[0069] Specifically, first, a target coordinate to which the tip of the SCARA robot 3 is to be moved is determined. The target coordinate is a coordinate within the measurement area of ​​the sensor units 92 and 93. Next, the SCARA robot 3 is moved to move the tip of the SCARA robot 3 to the target coordinate in the left arm system posture, and the state is imaged by at least one of the sensor units 92 and 93 to obtain a left arm system image. Next, the SCARA robot 3 is moved to move the tip of the SCARA robot 3 to the target coordinate in the right arm system posture, and the state is imaged by at least one of the sensor units 92 and 93 to obtain a right arm system image. Next, the processing unit 95 measures the height deviation between the left arm system and the right arm system based on the Z-axis position coordinate of the tip of the SCARA robot 3 calculated from the left arm system image and the Z-axis position coordinate of the tip of the SCARA robot 3 calculated from the right arm system image.

[0070] Furthermore, in the first region R1, the repeatability characteristic of the SCARA robot 3 is inspected using the origin calibration system 99. The repeatability indicates the degree of reproducibility when the same operation is repeatedly performed, and the more excellent the repeatability characteristic, the more accurate the SCARA robot 3. Specifically, first, a first target coordinate and a second target coordinate, both of which are located within the measurement areas of the sensor units 92 and 93, are set, and the SCARA robot 3 is moved so that the tip of the SCARA robot 3 reciprocates between the first target coordinate and the second target coordinate. Then, every time the tip of the SCARA robot 3 reaches the first or second target coordinate, the state is captured by at least one of the sensor units 92 and 93. Then, the amount of deviation from the first or second target coordinate is measured from each of the obtained images, and the repeatability of the SCARA robot 3 is detected using the maximum value, average value, etc. of the amount of deviation.

[0071] Furthermore, in the first region R1, the length L1 of the first arm 31 and the length L2 of the second arm 32 are measured. As shown in FIG. 2, the length L1 is the distance between the first rotation axis J1 and the second rotation axis J2, and the length L2 is the distance between the second rotation axis J2 and the third rotation axis J3. Depending on the assembly accuracy of the SCARA robot 3, the actual lengths L1 and L2 may deviate from the designed lengths L1 and L2. Even in this case, for example, in a PTP (Point to Point) movement in which the tip of the SCARA robot 3 is moved from one coordinate to another coordinate, the trajectory is not important, so problems are unlikely to occur. However, for example, when the tip of the SCARA robot 3 is moved from one coordinate to another coordinate on a determined trajectory, if the lengths L1 and L2 deviate from the design values, the trajectory will meander with respect to the determined trajectory, and the CP (Continuous Path) accuracy will deteriorate. Therefore, in this embodiment, the lengths L1 and L2 of the first and second arms 31 and 32 are measured to suppress deterioration of the CP accuracy.

[0072] As shown in FIG. 15, in the arm length measurement step S3 for measuring the lengths L1 and L2 of the first and second arms 31 and 32, first, the stage 90 is moved to place the reference pin 91 at a predetermined coordinate in the robot coordinate system. Next, the SCARA robot 3 is moved to set the SCARA robot 3 in a first posture in which the tip of the SCARA robot 3 is located within the measurement area of ​​the sensor units 92 and 93. Next, this state is imaged by the sensor units 92 and 93 to obtain a first posture image. Next, the SCARA robot 3 is set in a second posture by moving only the motor of the first joint drive mechanism 361 by a predetermined angle within a range in which the tip of the SCARA robot 3 does not deviate from the measurement area of ​​the sensor units 92 and 93. Next, this state is imaged by the sensor units 92 and 93 to obtain a second posture image. The processing unit 95 obtains the length L1 of the first arm 31 based on the rotation angle of the motor of the first joint drive mechanism 361 and the position coordinates before and after the movement of the tip of the SCARA robot 3 identified from the first and second posture images.

[0073] Next, the SCARA robot 3 is again placed in the first posture. Then, the motor of the second joint drive mechanism 362 is moved by a predetermined angle within a range in which the tip of the SCARA robot 3 does not deviate from the measurement area of ​​the sensor units 92, 93 to place the SCARA robot 3 in the third posture, and this state is imaged by the sensor units 92, 93 to obtain a third posture image. The processing unit 95 calculates the length L2 of the second arm 32 based on the rotation angle of the motor of the second joint drive mechanism 362 and the position coordinates of the tip of the SCARA robot 3 before and after the movement, which are identified from the first and third posture images.

[0074] Then, for example, the operator sets the lengths L1 and L2 measured by the processing unit 95 in the robot controller 37. The robot controller 37 calculates the position of the tip of the SCARA robot 3 based on the set lengths L1 and L2. This enables highly accurate control of the SCARA robot 3.

[0075] The above describes the inspections performed in the first area R1. However, the method of each inspection is not particularly limited. In addition, the inspections performed in the first area R1 are not particularly limited, and as long as the origin calibration of the SCARA robot 3 can be performed, the other inspections are not particularly limited, and at least one of the above-mentioned inspection contents may be omitted, or an inspection different from the above-mentioned inspection contents may be performed.

[0076] Furthermore, the optical sensor 98 included in the origin calibration system 99 is not particularly limited as long as it can simultaneously detect the non-contact reference pin 91 and the tip of the SCARA robot 3. For example, the optical sensor 98 may be a projector, a reflective laser sensor, a line camera, an area camera, or a three-dimensional shape measuring device that performs three-dimensional measurement of an object using phase shift interferometry.

[0077] The robot inspection system 1 has been described above. The method of calibrating the origin of the SCARA robot 3 performed in such a robot inspection system 1 includes a detection step S1 in which an optical sensor 98 simultaneously detects a reference pin 91, which is a reference jig arranged at a reference position, and the tip of the SCARA robot 3, and a calibration step S2 in which origin calibration of the SCARA robot 3 is performed based on the result of the detection step S1. According to this method, origin calibration of the SCARA robot 3 can be performed in a state in which the tip of the SCARA robot 3 is not in contact with the reference pin 91. Therefore, origin calibration of the SCARA robot 3 can be performed with high accuracy without being affected by machining errors of the reference pin 91.

[0078] As described above, the optical sensor 98 includes two sensor units 92, 93 each having a light emitting device 921, 931 and a light receiving device 922, 932 that are arranged opposite each other via a reference pin 91, and the two sensor units 92, 93 are arranged with their optical axes O1, O2 perpendicular to each other. This allows the origin calibration of the SCARA robot 3 to be performed with high accuracy.

[0079] As described above, the light emitting devices 921 and 931 are transilluminators, which can prevent halation from occurring even if the measurement object is made of metal, making it possible to clearly observe the contour.

[0080] As described above, the light emitting devices 921 and 931 have light sources 921a and 931a, and light emitting side telecentric optical systems 921b and 931b that convert the light LL1 and LL2 emitted from the light sources 921a and 931a into parallel light, and the light receiving devices 922 and 932 have image pickup elements 922a and 932a, and light receiving side telecentric optical systems 922b and 932b that form parallel light on the image pickup elements 922a and 932a. In other words, the sensor units 92 and 93 are double telecentric optical systems equipped with telecentric optical systems on both the light emitting side and the light receiving side. This allows the edge of the object in the measurement area to be sharply imaged, and also ensures a deep depth of field. Therefore, the edges of the reference pin 91 and the spline shaft 333 can both be clearly imaged. In addition, theoretically, the image pickup elements 922a and 932a receive only parallel light, so they are resistant to ambient light, and the size of the image formed is unlikely to change even if thermal expansion occurs. Therefore, the influence of temperature changes can be minimized. As a result, the sensor units 92 and 93 configured in this way can exhibit excellent detection characteristics.

[0081] As described above, the measurement range of the optical sensor 98 is 25 mm or more in diameter. This size provides a measurement area of ​​a size suitable for simultaneously detecting the reference pin 91 and the tip of the SCARA robot 3. Therefore, an image can be acquired that reliably contains necessary information while eliminating unnecessary information as much as possible, allowing the origin calibration of the SCARA robot 3 to be performed accurately and smoothly.

[0082] As described above, the repeatability of the optical sensor 98 is ±0.2 μm or less. This allows the origin calibration of the SCARA robot 3 to be performed with high accuracy. Also, the calibration variation for each SCARA robot 3 can be effectively suppressed.

[0083] As described above, the method also includes an arm length measurement step S3 for measuring the arm lengths L1, L2 of the SCARA robot 3 based on the detection results of the detection step S1. This improves the CP (Continuous Path) accuracy of the SCARA robot 3, enabling the SCARA robot 3 to be controlled with higher accuracy.

[0084] As described above, the origin calibration system 99 included in the robot inspection system 1 has the reference pin 91 which is a reference jig placed at a reference position, an optical sensor 98 which simultaneously detects the reference pin 91 and the tip of the SCARA robot 3, and a processing unit 95 which performs origin calibration of the SCARA robot 3 based on the detection result of the optical sensor 98. With this configuration, origin calibration of the SCARA robot 3 can be performed in a state where the tip of the SCARA robot 3 is not in contact with the reference pin 91. Therefore, origin calibration of the SCARA robot 3 can be performed with high accuracy without being affected by processing errors of the reference pin 91.

[0085] <Second embodiment> FIG. 20 is a top view showing the origin calibration system according to the second embodiment.

[0086] The origin calibration system 99 of this embodiment is the same as that of the first embodiment described above, except that the stage 90 is movable in the X-axis direction in addition to the Y-axis direction. In the following description, the present embodiment will be described with a focus on the differences from the previous embodiment, and the description of the same points will be omitted. In the drawings of this embodiment, the same reference numerals are used for the same configurations as the previous embodiment.

[0087] In an origin calibration system 99 shown in Fig. 20, a stage 90 is movable in the X-axis direction and the Y-axis direction. With this configuration, the lengths L1 and L2 of the first and second arms 31 and 32 can be measured with higher accuracy, particularly compared to the first embodiment described above. A method for measuring the lengths L1 and L2 in this embodiment will be specifically described below.

[0088] First, the stage 90 is moved to place the reference pin 91 at the first coordinate in the robot coordinate system. Next, the SCARA robot 3 is moved to a first posture in which the tip of the SCARA robot 3 is positioned within the measurement area of ​​the sensor units 92, 93. Next, this state is imaged by the sensor units 92, 93 to obtain a first posture image.

[0089] Next, the stage 90 is moved in the X-axis and Y-axis directions to place the reference pin 91 at a second coordinate in the robot coordinate system. The second coordinate is located outside the measurement area of ​​the sensor units 92, 93 when the reference pin 91 is at the first coordinate. Next, only the motor of the first joint drive mechanism 361 is driven to set the SCARA robot 3 to a second posture in which the tip of the SCARA robot 3 is located within the measurement area of ​​the sensor units 92, 93. However, at this time, the spline shaft 333 may be temporarily raised and lowered to avoid contact between the tip of the SCARA robot 3 and the origin calibration system 99. Next, this state is imaged by the sensor units 92, 93 to obtain a second posture image.

[0090] Next, the processing unit 95 calculates the length L1 of the first arm 31 based on the rotation angle of the motor of the first joint drive mechanism 361 and the position coordinates before and after the movement of the tip of the SCARA robot 3 identified from the first and second posture images.

[0091] Next, the SCARA robot 3 is moved to assume the first posture again. Next, the stage 90 is moved to place the reference pin 91 at the third coordinate in the robot coordinate system. The third coordinate is located outside the measurement area of ​​the sensor units 92 and 93 when the reference pin 91 is at the first coordinate. Next, only the motor of the second joint drive mechanism 362 is driven to assume the third posture in which the tip of the SCARA robot 3 is located within the measurement area of ​​the sensor units 92 and 93. However, at this time, in order to avoid contact between the tip of the SCARA robot 3 and the origin calibration system 99, the spline shaft 333 may be temporarily raised and lowered. Next, this state is imaged by the sensor units 92 and 93 to obtain a third posture image.

[0092] Next, the processing unit 95 calculates the length L2 of the second arm 32 based on the rotation angle of the motor of the second joint drive mechanism 362 and the position coordinates before and after the movement of the tip of the SCARA robot 3 identified from the first and third posture images.

[0093] According to this method, the difference between the first position and the second position can be made larger than in the first embodiment described above, so that the length L1 of the first arm 31 can be measured with high accuracy. Similarly, the difference between the first position and the third position can be made larger than in the first embodiment described above, so that the length L2 of the second arm 32 can be measured with high accuracy.

[0094] The second embodiment as described above can also achieve the same effects as the first embodiment.

[0095] <Third embodiment> FIG. 21 is a top view showing the origin calibration system according to the third embodiment.

[0096] In the embodiment described above, the origin calibration system 99 is incorporated in the robot inspection system 1, and various inspections such as origin calibration are performed on the SCARA robot 3 transported to the robot inspection system 1. In contrast, in the present embodiment, as shown in Fig. 21, the origin calibration system 99 is not incorporated in the robot inspection system 1, and origin calibration of the SCARA robot 3 is performed in a state where the origin calibration system 99 is transported and placed at the location where the SCARA robot 3 is installed.

[0097] The third embodiment as described above can also achieve the same effects as the first embodiment described above.

[0098] The origin calibration method and origin calibration system of the present invention have been described above based on the illustrated embodiment, but the present invention is not limited to this. The configuration of each part can be replaced with any configuration having a similar function. In addition, any other configuration or any other process may be added to the present invention. [Explanation of symbols]

[0099] 1...robot inspection system, 10...inspection chamber, 11...vibration damping member, 2...mounting table, 21...top plate portion, 22...bottom plate portion, 23...leg portion, 24...caster, 3...scalar robot, 30...base, 31...first arm, 32...second arm, 33...work head, 331...spline nut, 332...ball screw nut, 333...spline shaft, 34...cover, 341...marker, 35...stopper, 350...gap, 361...first joint drive mechanism, 362...second joint drive mechanism, 363...first head head drive mechanism, 364...second head drive mechanism, 37...robot controller, 4...automatic guided vehicle, 41...cargo platform, 42...lifting device, 43...wheel, 44...motor, 45...controller, 5...connection portion, 51...recess, 511...entrance, 6...positioning mechanism, 61...contact portion, 62...contact portion, 7...inspection portion, 80...movement mechanism, 81...rotation angle calibration portion, 811...camera, 812...processing portion, 813...movement mechanism, 82...height calibration portion, 821...contact type distance sensor, 822...contact type distance sensor, 82 3... processing unit, 824... moving mechanism, 90... stage, 91... reference pin, 911... first outer surface, 912... second outer surface, 92... sensor unit, 921... light emitting device, 921a... light source, 921b... light emitting side telecentric optical system, 922... light receiving device, 922a... image sensor, 922b... light receiving side telecentric optical system, 93... sensor unit, 931... light emitting device, 931a... light source, 931b... light emitting side telecentric optical system, 932... light receiving device, 932a... image sensor, 932b... light receiving side telecentric optical system Recentric optical system, 94...calibration device, 95...processing unit, 98...optical sensor, 99...origin calibration system, G1...image, G2...image, J1...first rotation axis, J2...second rotation axis, J3...third rotation axis, Jp...central axis, L1...length, L2...length, LL1...light, LL2...light, M...weight, N1...screw, O1...optical axis, O2...optical axis, Q1...normal, Q2...normal, R1...first region, R2...second region, R3...third region, S1...detection step, S2...calibration step, S3...arm length measurement step, T...tool

Claims

1. An origin calibration method for a SCARA robot, comprising: a detection step of simultaneously detecting a reference jig placed at a reference position and the tip of the SCARA robot by an optical sensor; a calibration step of performing origin calibration of the SCARA robot based on the result of the detection step.

2. the optical sensor includes two sets of sensor units each including a light-emitting device and a light-receiving device that are arranged opposite to each other across the reference jig; 2. The method for calibrating an origin according to claim 1, wherein the two sets of sensor units are arranged so that their optical axes are perpendicular to each other.

3. The origin calibration method according to claim 2 , wherein the light emitting device is a transmitted illumination device.

4. the light emitting device includes a light source and a light-emitting side telecentric optical system that converts light emitted from the light source into parallel light, The origin calibration method according to claim 2 , wherein the light receiving device includes an image sensor and a light receiving side telecentric optical system that forms an image of the parallel light on the image sensor.

5. 2. The method for calibrating an origin according to claim 1, wherein the measurement range of the optical sensor is 25 mm or more in diameter.

6. 2. The method for calibrating an origin according to claim 1, wherein the repeatability 2σ of the optical sensor is ±0.2 μm or less.

7. 2. The method for calibrating an origin according to claim 1, further comprising an arm length measuring step of measuring the length of the arm of said SCARA robot based on the result of said detecting step.

8. a reference jig disposed at a reference position; an optical sensor that simultaneously detects the reference jig and the tip of the SCARA robot; a processing unit that performs origin calibration of the SCARA robot based on the detection result of the optical sensor.

Images