JP2011143497A - Device and method for tray transfer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tray transfer device in which: (1) a wide variety of products in small quantities can be efficiently manufactured by a robot; (2) a supply device can be simplified to reduce an installation space; (3) an inclinedly supplied tray can be detected; and (4) a workpiece can be correctly grasped even if the tray is tilted; and a method used in the same. <P>SOLUTION: The tray transfer device includes: a plurality of trays 10 which can be respectively stacked in a plurality of loading spaces (a), b and c; a tray grasping part 11 provided on the tray; a hand 12 capable of grasping a workpiece 1 mounted on the tray; a camera 14 attached to the hand for imaging the tray from upward; the robot 16 capable of three-dimensionally moving the hand; and a robot controller 20 for image-processing the image recorded by the camera to control the robot. An inclination angle of the tray is measured (S24) based on the image 5 recorded from the above of a destination loading space, a base coordinate of the robot is calibrated (S25) based on the angle, and the workpiece in the tray is transferred. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tray transfer apparatus and method for automatically exchanging trays using an automatic supply apparatus.

  Patent Document 1 has already been disclosed as a system for automatically exchanging trays using an automatic feeder.

FIG. 1 is a conceptual diagram of an assembly system according to Patent Document 1. As shown in FIG.
The purpose of this system is to efficiently perform high-mix low-volume production by robots.

  Therefore, in this system, the robots 51A and 51B are fixed to rectangular bases 52A and 52B, and have mechanical hands 53A and 53B. A plurality of robot tools that can be attached to the tips of the mechanical hands 53A and 53B and grip a part, and a plurality of trays 54 on which an assembly tool including an assembly tool used to assemble the parts is placed are carried into the movable range of the robot. Then, the assembly tool is set at a predetermined position within the movable range. Then, parts are assembled using a set assembly tool.

Japanese Patent No. 3673117, “Assembly apparatus and tray system therefor”

  The system disclosed in Patent Document 1 described above has a problem that a supply device is large and a large installation space is required.

In addition, a dedicated identification unit is provided to detect the presence or absence of the tray in the supply unit and the tray height, but if a simple presence / absence sensor is used, the tray is tilted and supplied in a subsequent process such as a processing device. In the handling of the work on the tray, there has been a problem of inducing an error such as gripping the work while being tilted.
Furthermore, in order to prevent this erroneous detection, when measuring the height with a laser distance meter, etc., the laser distance meter is not only expensive, but also a mechanism for avoiding interference between the robot arm and the laser distance meter. There was a problem.

  The present invention has been developed to solve the above-described problems. That is, the object of the present invention is to (1) be able to efficiently carry out high-mix low-volume production by robots, (2) to simplify the supply device and to reduce the installation space, and (3) to be supplied with the tray inclined (4) To provide a tray transfer apparatus and method that can correctly grip a workpiece on a tray even if the tray is tilted.

According to the present invention, a plurality of trays each capable of being stacked in a plurality of loading spaces,
A tray gripping portion provided on the tray and a hand capable of gripping a workpiece loaded on the tray;
A camera attached to the hand for photographing the tray from above;
A robot capable of moving the hand three-dimensionally;
A robot control device that performs image processing on an image captured by the camera and controls the robot;
Based on the image taken from above each loading space, the position and orientation of the uppermost tray gripping part and the number of stacked trays in each loading space are measured, and the uppermost tray is transferred based on this. ,
A tray that measures the tilt angle of the tray based on an image taken from above the loading space at the transfer destination, calibrates the base coordinates of the robot based on this, and transfers the workpiece on the tray. A transfer device is provided.

According to an embodiment of the present invention, the robot control device performs image processing on the image to measure the position and orientation of the uppermost tray gripping unit and the number of trays stacked in each stacking space. When,
Based on the measurement result of the image processing apparatus, a robot that grips the uppermost tray gripping part by a robot hand and transports it to another loading space, and grips the work on the uppermost tray and transports it to a predetermined position And a controller.

Further, according to the present invention, a plurality of trays that can be stacked in a plurality of loading spaces,
A tray gripping portion provided on the tray and a hand capable of gripping a workpiece loaded on the tray;
A camera attached to the hand for photographing the tray from above;
A robot capable of moving the hand three-dimensionally;
A robot control device that performs image processing on an image captured by the camera and controls the robot;
(A) a first image measurement for measuring the position and posture of the uppermost tray gripping portion and the number of trays stacked in each stacking space, based on images taken from above the respective stacking spaces;
(B) tray transfer control for transferring the uppermost tray to another loading space based on the result of the first image measurement;
(C) second image measurement for measuring a tilt angle of the tray based on an image taken from above the loading space of the transfer destination;
(D) A tray transfer method comprising: a workpiece transfer control for calibrating a base coordinate of a robot based on a result of the second image measurement and transferring a workpiece on the tray to a predetermined position. Is done.

  According to the embodiment of the present invention, in the second image measurement, the height of three or more workpieces is measured by pattern matching on the image, and the tilt angle of the tray is measured from the result.

  In the workpiece transfer control, the workpiece on the tray is gripped based on the base coordinates after calibration, lifted, moved to the destination, and installed at the destination.

  According to the apparatus and method of the present invention, a plurality of trays can be stacked in a plurality of loading spaces (for example, loading space, unloading space, and processing space). By transferring the work on the uppermost tray, the tray supply device can be simplified, the installation space can be reduced, and high-mix low-volume production by a robot can be efficiently performed.

  Also, since the tilt angle of the tray is measured based on the image taken from above the loading space of the transfer destination with the camera attached to the robot hand, the tray is tilted and supplied without using sensors other than the camera. Can be detected.

Furthermore, since the base coordinates of the robot are calibrated based on the measurement result of the tilt angle of the tray and the work on the tray is transferred, the work can be correctly gripped even if the tray is tilted.

1 is a conceptual diagram of an assembly system according to Patent Document 1. FIG. It is a block diagram of the tray transfer apparatus by this invention. It is a schematic diagram of the tray used for this invention. It is a whole flowchart of the tray transfer method by this invention. It is a flowchart of the 1st image measurement by this invention. It is a flowchart of the 2nd image measurement by this invention. It is a flowchart of the workpiece transfer control by this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

  FIG. 2 is a configuration diagram of a tray transfer apparatus according to the present invention, and FIG. 3 is a schematic diagram of a tray used in the present invention.

  In FIG. 2, the tray transfer device of the present invention includes a plurality of trays 10, a hand 12, a camera 14, a robot 16, and a robot control device 20.

In FIG. 3, a tray 10 is a stackable transport tray, has a substantially horizontal flat plate 10a, and a plurality of (for example, 10 to 20) workpieces 1 can be stacked on the upper surface thereof.
In addition, a tray gripping portion 11 is provided on the upper surface (in this example, the center portion) of the flat plate 10 a so that the tray gripping portion 11 can be gripped by the hand 12.

The tray gripping part 11 is a rectangular flat plate in this example, and two vertical holes 11a are provided on the upper surface of the tray gripping part 11 at a predetermined interval. In addition, the tray 10 includes two positioning pins 11b that fit into the vertical holes 11a at positions corresponding to the two vertical holes 11a on the lower surface thereof.
With this configuration, the plurality of trays 10 are sequentially fitted with the positioning pins 11b of the upper tray in the vertical holes 11a of the lower tray, and a plurality of (for example, five stages) trays are placed in the same posture in the same stacking space. It can be stacked.

In FIG. 2, the tray 10 described above can be stacked in a plurality of loading spaces (in this example, a loading space a, a loading space b, and a processing space c).
In this example, a base block 4 (see FIG. 3) for positioning the lowermost tray is provided on the upper surface of the table 3 in each of the loading spaces a, b, and c. The base block 4 has the same shape as the tray gripping part 11 and has a vertical hole 4a having the same dimensions at the same position as the vertical hole 11a.

The workpiece 1 is a disk-shaped member in this example, but the present invention is not limited to this, and may be a member having a certain shape as viewed from above. This shape may be a circle, a rectangle, an ellipse, or other shapes as long as it can be pattern-matched with a shape stored in advance.
In the present invention, it is preferable that the upper surface of the work 1 is provided with two vertical holes 1a spaced apart from each other. This vertical hole 1a is a bolt hole of a flange, for example. The vertical holes 1a are not essential, and may be other holes or shapes as long as the vertical holes 1a are provided in each workpiece and the interval can be accurately detected.

The hand 12 is configured to be capable of gripping a tray gripping portion 11 provided on the tray 10 and a workpiece 1 loaded on the tray.
The hand 12 is a mechanical clamping device having, for example, two opening / closing claws for a tray and a workpiece, and the position of the two opening / closing claws is switched by changing the posture of the hand (rotation, etc.), and the tray gripping part 11 or the workpiece 1 can be gripped at any time.
The hand 12 is not limited to this configuration, and may be a suction pad, an electromagnetic pad, or a mechanical hand having another configuration.

In FIG. 2, a camera 14 is, for example, a CCD camera or a CMOS camera, and is integrally attached to the hand 12 of the arm, and takes a picture of the work 1 from above to output a digital image 5.
Although the number of pixels of the digital image 5 is arbitrary, it has about 4 million pixels (2300 pixels wide × 1700 pixels long), for example. Further, the camera 14 captures the digital image 5 at a constant control cycle (for example, 30 fps: 30 times per second). Hereinafter, a digital image is simply referred to as an image.

The robot 16 moves the hand 12 and the camera 14 three-dimensionally. In this example, the hand 12 is mounted on the tip of the robot arm 16 a of the robot 16 so that the camera 14 can be maintained downward by the robot 16.
In this example, the robot 16 is a vertical articulated robot fixed to the upper surface of the table 3. However, the present invention is not limited to this, and may be another robot (a SCARA robot or an orthogonal robot).

  In FIG. 2, the robot control device 20 according to the present invention includes an image processing device 22 and a robot controller 24, and controls the robot 16 by performing image processing on an image 5 taken by the camera 14.

  The image processing apparatus 22 performs image processing on the image 5 captured by the camera 14 and measures the position and orientation of the uppermost tray gripping unit 11 and the number of stacked trays 10 in each stacking space.

Based on the measurement result of the image processing device 22, the robot controller 24 grips the uppermost tray gripping part 11 with the hand 12 of the robot 16 and conveys it to another loading space, and also works 1 on the uppermost tray. And is conveyed to a predetermined position.
In the above-described example, another loading space for transporting the tray gripping portion 11 is the loading space a, the unloading space b, or the processing space c. Moreover, the predetermined position which conveys the workpiece | work 1 is another apparatus (processing apparatus, assembly | attachment apparatus, etc.) which is not shown in figure installed in the operating range of the robot 16, for example.
In the following example, after the workpiece 1 is transported to the other device, the workpiece 1 is unloaded from the operation range of the robot 16 by another unillustrated unillustrated device and is not returned to the original tray. To do.
However, the present invention is not limited to this configuration, and the robot 16 may be returned to the original tray from another device.

  The robot controller 24 controls the robot 16 to calculate the rotation amount of each joint from the target hand speed of the robot arm 16a, operates the robot arm 16a, and moves the hand 12 and the camera 14 three-dimensionally.

With the above-described configuration, the tray transfer apparatus of the present invention is configured so that the position of the uppermost tray gripping unit 11 is based on the image 5 taken from above each loading space (carry-in space a, carry-out space b, and processing space c). And the posture and the number of stacked trays 10 in each loading space are measured, and based on this, the uppermost tray 10 is transferred.
Furthermore, the tray transfer apparatus of the present invention measures the tilt angle of the tray based on the image 5 taken from above the loading space (for example, the processing space c) of the transfer destination, and calibrates the base coordinates of the robot based on this. The work on the tray is transferred.
That is, the image processing apparatus 22 and the robot controller 24 described above execute first image measurement, tray transfer control, second image measurement, and workpiece transfer control, which will be described later.

  FIG. 4 is an overall flowchart of the tray transfer method according to the present invention. As shown in this figure, the tray transfer method of the present invention comprises steps (steps) S1 to S9. The first image measurement (A), the tray transfer control (B), and the second image measurement (C ) And workpiece transfer control (D).

In the first image measurement (A), the position and posture of the uppermost tray gripping unit and the respective loading spaces are based on images taken from above the loading spaces (the loading space a, the unloading space b, and the processing space c). The number of trays stacked is measured (S1 to S3).
In the tray transfer control (B), the uppermost tray is transferred to another loading space based on the result of the first image measurement (S5, S7).
In the second image measurement (C), the tilt angle of the tray is measured based on the image taken from above the loading space of the transfer destination, and the base coordinates of the robot are calibrated (S6).
In the workpiece transfer control (D), the workpiece on the tray is transferred to a predetermined position based on the result of the second image measurement (S6).

Before the start of operation (before the start of work), a predetermined number (for example, 5 stages) of trays loaded with a plurality of (for example, 20) workpieces (hereinafter referred to as full trays) is prepared, and a 5-stage full tray in which these are stacked is prepared. Install in the carry-in space a.
The unloading space b and the processing space c are empty without a tray, and the base block 4 is exposed on the upper surface of the table 3. Further, the robot 16 returns to the origin in advance and stands by at a position where it does not interfere with another device (not shown) or stacked trays.

At the start of operation (at the start of work), the number of trays 10 in the processing space c, the unloading space b, and the loading space a is measured in S1, S2, and S3. If the number of stages is normal, the number of stages is 5, 0, and 0 in the carry-in space a, the carry-out space b, and the processing space c, respectively, in the above example.
That is, when the system of the present invention is started, the camera 14 takes a picture from above the stacking space (carry-in space a, carry-out space b, and processing space c), and measures and determines the number of trays. At the same time, check the availability of the tray loading / unloading space.

In S4, it is determined whether or not the measured number of stages is normal. If not normal (NO), the operation is stopped (S8), the robot is returned to the origin (S9), and the operation is terminated.
As a result, it is possible to prevent human error in carrying in / out the tray.

When normal in S4 (YES), the full tray is transferred from the carry-in space a to the machining space c (S5), and the workpiece 1 is machined in the machining space c (S6).
The machining operation of the workpiece 1 in S6 is repeatedly performed until the workpiece on the tray in the machining space c is exhausted and becomes empty.
After the tray in the processing space c becomes empty, the empty tray is transported from the processing space c to the unloading space b (S7).

From S5 to S7, the stacked trays 10 that existed in the carry-in space a at the start of operation are transferred from the top to the processing space c and the carry-out space b in order, and are all transferred to the carry-out space b and stacked. Repeated.
In S7, when the last tray becomes empty and is transported to the unloading space b and stacked on another empty tray, the robot returns to the origin (S9) and the operation is completed.
The empty trays stacked in the carry-out space b are carried out of the robot operating range, for example, by an operator.
Note that a carry-out shooter (not shown) may be provided in the carry-out space b so that the empty tray is automatically carried out of the operating range of the robot.

  FIG. 5 is a flowchart of the first image measurement according to the present invention. As shown in this figure, the first image measurement according to the present invention includes the steps (steps) S11 to S14, and the image 5 of the uppermost tray is photographed downward from a predetermined height (S11, S12). Then, the position and orientation of the tray gripping part 11 are measured by pattern matching of the tray gripping part 11 on the image (S13), and the height and the number of stacked trays 10 are calculated from the dimensions of the tray gripping part 11 on the image. (S14).

  In this image measurement, steps S11 to S14 are performed in S1 to S3 described above, and steps S11 to S13 except S14 are performed in S5 and S7 described above.

In S11 to S13, the camera 14 is moved above the target loading space (carry-in space a, carry-out space b, or processing space c) (S11), and has a predetermined height (for example, 350 mm from the upper surface of the base block 4). The image 5 of the uppermost tray 10 is taken downward from the image (S12), and the position and orientation of the tray gripping part 11 or the base block 4 are measured by pattern matching of the tray gripping part 11 or the base block 4 on the image (S13). ).
This position is a relative position of the tray gripping part 11 or the base block 4 as viewed from the camera 14, and corresponds to a position on the horizontal plane (XY coordinates).
The pattern matching (S13) is a rough search, and the position and orientation of the tray gripper 11 or the base block 4 can be determined although the measurement accuracy is low.

After the rough search, precise measurement (S14) is performed.
In the precision measurement (S14), the height and the number of tray stacks are further calculated from the dimensions (for example, circle extraction and position calculation) on the image of the tray gripper 11 or the base block 4.
This height is, for example, the vertical distance between the reference point of the camera 14 and the tray gripping part 11 or the base block 4, and when a plurality of (for example, 1 to 5) trays 10 are stacked, the number of stages Can be calculated from the height of one tray.
That is, the position and orientation of the tray gripping part 11 or the base block 4 are measured (S13), and the number of stages is determined by comparing the tray measurement height (Z coordinate value) with a stage number table having inside the robot.
Further, when there is no tray in the measured loading space, it can be detected from the position on the Z coordinate that there is no tray. Further, the shape of the base block 4 may be made different from that of the tray gripping part 11, and it may be detected that there is no tray only by pattern matching (S13).

  Note that the height calculation accuracy is improved by using, for example, the distance (center distance) between the two vertical holes 11a (or the vertical holes 4a) on the image as the dimensions on the image of the tray holding unit 11 or the base block 4. be able to.

  FIG. 6 is a flowchart of the second image measurement according to the present invention. As shown in this figure, the second image measurement according to the present invention includes steps (steps) S21 to S25, and images the image 5 of the transfer destination tray from a predetermined height downward (S21, S22). ), The height of the workpiece 1 at three or more points is measured by pattern matching on the image (S23), the tilt angle of the tray is measured from the result (S24), and the base coordinates of the robot are calibrated (S25).

In S21 to S23, the camera 14 is moved above the target stacking space (in this example, the processing space c) (S21), and the tray 10 is moved downward from a predetermined height (for example, 350 mm from the upper surface of the base block 4). Image 5 is photographed (S22), and the position and height of three or more workpieces 1 are measured by pattern matching of workpiece 1 on the image (S23).
This pattern matching uses, for example, the center interval (distance on the image) of the two vertical holes 1a as the dimension of the workpiece 1 to increase the accuracy of height calculation. The height calculation position may be any position as long as the relative position with respect to the tray 10 is known.
The pattern matching of the workpiece 1 may be other holes or shapes as long as a known dimension can be accurately detected.

The positions of three or more workpieces 1 are, for example, the same reference positions of the workpieces placed at the four corners of the tray 10.
In this case, since each workpiece 1 is accurately placed on the tray 10, the planes connecting the same reference positions (for example, the centers) of three or more workpieces 1 (the workpieces placed at the four corners) are the same. It is on a plane and is parallel to a reference surface (for example, the upper surface) of the tray 10 with a known distance.

  In S24, the tilt angle of the tray is measured from the result of S23, that is, the positions and heights of three or more workpieces 1 (work placed at the four corners).

In FIG. 2, the base coordinates of the robot are three-dimensional coordinates of three orthogonal axes (XYZ axes), the XY plane is a horizontal plane, and the Z axis is a vertical axis.
When the tray 10 coincides with the horizontal plane, the heights of the workpieces 1 at three or more points coincide, and the inclination angle of the tray is 0 with respect to the X axis and the Y axis.

On the other hand, when the tray 10 is inclined with respect to the horizontal plane, the heights of the workpieces 1 at three or more points do not coincide with each other, and the inclination angle of the tray can be measured from the difference in height.
For example, if the reference position (position and height) of the three workpieces 1 is (Xi, Yi, Zi) (i = 1, 2, 3) in the above three-dimensional coordinates, the X of the plane connecting them , Inclination angles Δθx and Δθy with respect to the Y axis can be obtained.

In S25, the base coordinates of the robot are calibrated from the obtained tilt angles Δθx and Δθy.
This calibration is preferably performed by calibrating the three orthogonal axes (XYZ axes) using the inclination angles Δθx and Δθy with respect to the above-described three-dimensional coordinate system.
The above-described three-dimensional coordinate system may not be set in advance, and a plane connecting the heights of three or more workpieces 1 obtained in S23 may be set as the base coordinates of the robot.

FIG. 7 is a flowchart of workpiece transfer control according to the present invention. As shown in this figure, the workpiece transfer control according to the present invention comprises S31 to S37, performs image measurement (S31, S32), and grips the workpiece on the tray based on the base coordinates after calibration based on the result. (S33), lift (S34), move to the destination (S35), install at the destination (S36), and return to the origin (S37).
In addition, the movement destination in the workpiece transfer control is another apparatus (processing apparatus, assembly apparatus, etc.) not shown.

  The tray transfer control according to the present invention is different in that the uppermost tray is gripped in place of the workpiece in S33 and the destination is a different loading space. It is the same.

In the apparatus and method of the present invention described above, instead of the conventional automatic supply apparatus (Patent Document 1), the tray 10 is automatically replaced by the hand 12 of the robot 16, and at the same time, the number of tray stages and the tray inclination are determined by the camera 14 at the arm end. Measure images.
Therefore, the inclination of the tray can be measured by using the parts (work 1) arranged on the tray and measuring the height of the parts at the four corners of the tray. Since the base coordinates of the robot arm 16a are calibrated at the tray tilt angle, it is possible to prevent the workpiece 1 from being tilted and held.

(1) Therefore, the tray-dedicated automatic supply device (tray transport unit / exchange unit / identification unit in FIG. 1) is unnecessary, and the system is simplified. Also, the installation space of the entire system can be reduced.
(2) When detected by a permanent sensor such as a laser rangefinder, the interference between the arm and the sensor becomes a problem. However, since the image is measured by the camera 14 attached to the arm hand and the tray inclination is determined, such a problem is Does not occur.
(3) Furthermore, the part (work 1) on the tray is used, and no special marker is required.

  According to the above-described apparatus and method of the present invention, a plurality of trays 10 can be stacked in a plurality of loading spaces (for example, the loading space a, the unloading space b, and the processing space c). By transferring the tray 10 and transferring the workpiece 1 on the tray, the tray supply device can be simplified, the installation space can be reduced, and the multi-product and small-volume production by the robot 16 can be performed efficiently.

  Further, since the tilt angle of the tray is measured based on the image taken from above the loading space (processing space c) of the transfer destination by the camera 14 attached to the robot hand 12, sensors other than the camera are used. In other words, it can be detected that the tray has been tilted.

  Furthermore, since the robot base coordinates are calibrated based on the measurement result of the tilt angle of the tray 10 and the workpiece 1 on the tray is transferred, the workpiece 1 on the tray can be correctly gripped even if the tray is tilted.

  In addition, this invention is not limited to embodiment mentioned above, is shown by description of a claim, and also includes all the changes within the meaning and range equivalent to description of a claim.

1 work 1a vertical hole 3 table 4 base block
4a Vertical hole, 5 images,
10 trays, 10a flat plate,
11 Tray gripping part, 11a Vertical hole, 11b Positioning pin,
12 hands, 14 cameras,
16 robot, 16a robot arm,
20 robot control devices, 22 image processing devices,
24 Robot controller

Claims (5)

Multiple trays that can be stacked in multiple loading spaces,
A tray gripping portion provided on the tray and a hand capable of gripping a workpiece loaded on the tray;
A camera attached to the hand for photographing the tray from above;
A robot capable of moving the hand three-dimensionally;
A robot control device that performs image processing on an image captured by the camera and controls the robot;
Based on the image taken from above each loading space, the position and orientation of the uppermost tray gripping part and the number of stacked trays in each loading space are measured, and the uppermost tray is transferred based on this. ,
A tray that measures the tilt angle of the tray based on an image taken from above the loading space at the transfer destination, calibrates the base coordinates of the robot based on this, and transfers the workpiece on the tray. Transfer device. The robot control device performs image processing on the image to measure the position and posture of the uppermost tray gripping unit and the number of trays stacked in each stacking space;
Based on the measurement result of the image processing apparatus, a robot controller that grips the uppermost tray gripping part by a robot hand and transports it to another loading space, and grips the work on the tray and transports it to a predetermined position; The tray transfer device according to claim 1, comprising: Multiple trays that can be stacked in multiple loading spaces,
A tray gripping portion provided on the tray and a hand capable of gripping a workpiece loaded on the tray;
A camera attached to the hand for photographing the tray from above;
A robot capable of moving the hand three-dimensionally;
A robot control device that performs image processing on an image captured by the camera and controls the robot;
(A) a first image measurement for measuring the position and posture of the uppermost tray gripping portion and the number of trays stacked in each stacking space, based on images taken from above the respective stacking spaces;
(B) tray transfer control for transferring the uppermost tray to another loading space based on the result of the first image measurement;
(C) a second image measurement for measuring the tilt angle of the tray and calibrating the base coordinates of the robot based on an image taken from above the loading space of the transfer destination;
(D) A tray transfer method comprising: a workpiece transfer control for transferring a workpiece on the tray to a predetermined position based on a result of the second image measurement.   4. The tray transfer according to claim 3, wherein in the second image measurement, the height of three or more workpieces is measured by pattern matching on the image, and the tilt angle of the tray is measured from the result. Loading method. 4. The tray according to claim 3, wherein, in the workpiece transfer control, the workpiece on the tray is gripped, lifted, moved to the destination, and installed at the destination based on the base coordinates after calibration. Transfer method.