Robotic system, identification and calibration method

Abstract

A robot system, a marker, and a calibration method are provided to effectively suppress the reduction and deviation of calibration accuracy. In the robot system, the control unit sets multiple third robot coordinates based on the pre-calibrated results, such that the marker is located within the field of view of the imaging unit. The multiple third robot coordinates are the positions of the robotic arm in the robot coordinate system. The robotic arm is positioned sequentially at the multiple third robot coordinates, and the imaging unit captures the marker positioned at the first position each time. Based on the obtained third image, the position of the marker in the image coordinate system is obtained as the third image coordinates. Based on the multiple third robot coordinates and the multiple third image coordinates, calibration is performed between the robot coordinate system set in the robot and the image coordinate system set in the imaging unit.

Description

Technical Field

[0001] This invention relates to robot systems, marking, and calibration methods. Background Technology

[0002] Previously, a robot system was known, comprising: a robot performing a predetermined task on a workpiece, a camera for photographing the workpiece, and a control device that controls the robot's drive based on images captured by the camera (hereinafter simply referred to as "camera images"). In such a robot system, before performing the predetermined task, it is necessary to calibrate (establish a correspondence) the image coordinate system of the camera images and the robot coordinate system, which serves as the reference for robot control. Furthermore, as a method for this calibration, for example, Patent Document 1 is known.

[0003] The calibration method described in Patent Document 1 first involves manually and visually machining the reference points on the calibration fixture using a touch-up process to obtain the position of the calibration fixture in the robot coordinate system, and then calculating the coordinate transformation matrix between the robot coordinate system and the calibration fixture coordinate system. Next, a camera mounted on the robot is used to photograph the calibration fixture, and the coordinate transformation matrix between the calibration fixture coordinate system and the camera coordinate system is calculated based on the captured image.

[0004] Patent Document 1: Japanese Patent Application Publication No. 8-210816

[0005] In the calibration method described in Patent Document 1, since the reference points on the calibration fixture are finished by hand using visual inspection, there is a risk of deviation originating from the operator. Therefore, the calibration accuracy is reduced or deviations occur. Summary of the Invention

[0006] The robot system of the present invention comprises: a robot having a robotic arm, wherein the robotic arm has a hand; The mark can be held using the hand and can be self-aligned relative to the hand; The camera unit, fixed at a position opposite to the work surface, photographs the markings on the work surface; and The control unit calibrates the robot coordinate system and the image coordinate system, wherein the robot coordinate system is set at the robot and the image coordinate system is set at the imaging unit. The control unit obtains the position of the robotic arm in the robot coordinate system when the hand places the marker in a first position on the work surface, as the first robot coordinate. The control unit uses the imaging unit to capture an image of the sign positioned at the first location, and obtains the position of the sign in the image coordinate system based on the obtained first image as the first image coordinates. After the control unit holds the marker using the hand, it positions the robotic arm at a second robot coordinate system separated from the first robot coordinate system, places the marker at a second position on the work surface, and captures an image of the marker at the second position using the imaging unit. Based on the obtained second image, the position of the marker in the image coordinate system is obtained as the second image coordinates. The control unit performs a pre-calibration of the robot coordinate system and the image coordinate system based on the first robot coordinates, the second robot coordinates, the first image coordinates, and the second image coordinates. Based on the image coordinate system, the control unit sets multiple third positions, which are located within the field of view of the imaging unit on the working surface. The control unit drives the robot based on the pre-calibrated results, sequentially placing the marker held by the hand into multiple third positions. Each time, the control unit acquires the position of the robotic arm in the robot coordinate system when the marker is placed in the third position as the third robot coordinate. The control unit then captures an image of the marker, and based on the resulting third image, obtains the position of the marker in the image coordinate system as the third image coordinate. The control unit calibrates the robot coordinate system and the image coordinate system based on multiple third robot coordinates and multiple third image coordinates.

[0007] The robot system of the present invention comprises: a robot having a robotic arm, wherein the robotic arm has a hand; The markings are capable of self-alignment relative to the hand; A camera unit, configured on the robotic arm, is used to photograph the markings on the work surface; and The control unit calibrates the robot coordinate system and the image coordinate system, wherein the robot coordinate system is set at the robot and the image coordinate system is set at the imaging unit. The control unit acquires the position of the robotic arm in the robot coordinate system when the hand is used to position the marker at a first position on the work surface, as the first robot coordinate. The control unit uses the imaging unit to capture an image of the sign positioned at the first location, and obtains the position of the sign in the image coordinate system based on the obtained first image as the first image coordinates. The control unit positions the robotic arm at a second robot coordinate system, separate from the first robot coordinate system. The imaging unit captures an image of the marker positioned at the first location. Based on the obtained second image, the position of the marker in the image coordinate system is obtained as the second image coordinates. The control unit performs a pre-calibration of the robot coordinate system and the image coordinate system based on the first robot coordinates, the second robot coordinates, the first image coordinates, and the second image coordinates. Based on the pre-calibration results, the control unit sets multiple third robot coordinates to ensure that the identifier is within the field of view of the imaging unit. These multiple third robot coordinates represent the positions of the robotic arm in the robot coordinate system. The control unit positions the robotic arm sequentially at multiple third robot coordinates, and each time uses the imaging unit to capture an image of the marker positioned at the first location. Based on the obtained third image, the position of the marker in the image coordinate system is obtained as the third image coordinates. The control unit calibrates the robot coordinate system and the image coordinate system based on multiple third robot coordinates and multiple third image coordinates.

[0008] The markings of this invention are used for calibrating the robot coordinate system and the image coordinate system. The robot coordinate system is set on the robot, which has a robotic arm with a hand. The image coordinate system is set on the imaging unit, which captures images of the work surface. The mark has a base and an annular flange. In the state configured on the work surface, The base extends in a direction orthogonal to the working surface and can be held by the hand. The flange protrudes outward from the base when viewed from above on the working surface.

[0009] The calibration method of the present invention calibrates the robot coordinate system and the image coordinate system in a robot system, wherein the robot system comprises: a robot having a robotic arm, the robotic arm having a hand; The mark can be held using the hand and can be self-aligned relative to the hand; and The camera unit is fixed in a position opposite to the work surface to photograph the markings on the work surface. The robot coordinate system is set at the robot, and the image coordinate system is set at the imaging unit. In the calibration method... The position of the robotic arm in the robot coordinate system when the hand positions the marker at a first position on the work surface is obtained as the first robot coordinate. The camera unit captures an image of the marker positioned at the first location. Based on the obtained first image, the position of the marker in the image coordinate system is obtained as the first image coordinates. After holding the marker with the hand, the robotic arm is positioned at a second robot coordinate system, separated from the first robot coordinate system. The marker is then positioned at a second location on the work surface. The imaging unit captures an image of the marker positioned at the second location. Based on the obtained second image, the position of the marker in the image coordinate system is obtained as the second image coordinates. Based on the first robot coordinates, the second robot coordinates, the first image coordinates, and the second image coordinates, a pre-calibration of the robot coordinate system and the image coordinate system is performed. Based on the image coordinate system, multiple third positions are defined, and these multiple third positions are located within the field of view of the shooting unit on the working surface. Based on the pre-calibrated results, the robot is driven to sequentially position the marker, which is held by the hand, at multiple third positions. Each time, the position of the robotic arm in the robot coordinate system when the marker is positioned at the third position is obtained as the third robot coordinate. The robot also captures an image of the marker using the imaging unit, and the position of the marker in the image coordinate system is obtained as the third image coordinate based on the resulting third image. Based on multiple third robot coordinates and multiple third image coordinates, the robot coordinate system and the image coordinate system are calibrated.

[0010] The calibration method of the present invention calibrates the robot coordinate system and the image coordinate system in a robot system. The robot coordinate system includes: a robot with a robotic arm, the robotic arm having a hand; The markings are capable of self-alignment relative to the hand; and The camera unit, mounted on the robotic arm, photographs the markings on the work surface. The robot coordinate system is set at the robot, and the image coordinate system is set at the imaging unit. In the calibration method... The position of the robotic arm in the robot coordinate system when the hand is used to position the marker at a first position on the work surface is obtained as the first robot coordinate. The camera unit captures an image of the marker positioned at the first location. Based on the obtained first image, the position of the marker in the image coordinate system is obtained as the first image coordinates. The robotic arm is positioned at a second robot coordinate system, separate from the first robot coordinate system. The imaging unit captures an image of the marker positioned at the first location. Based on the obtained second image, the position of the marker in the image coordinate system is obtained as the second image coordinates. Based on the first robot coordinates, the second robot coordinates, the first image coordinates, and the second image coordinates, a pre-calibration of the robot coordinate system and the image coordinate system is performed. Based on the pre-calibration results, multiple third robot coordinates are set in a manner that ensures the marker is within the field of view of the imaging unit. These multiple third robot coordinates represent the positions of the robotic arm in the robot coordinate system. The robotic arm is positioned sequentially at multiple third robot coordinates, and each time the imaging unit captures an image of the marker located at the first position. Based on the obtained third image, the position of the marker in the image coordinate system is obtained as the third image coordinate. Based on multiple third robot coordinates and multiple third image coordinates, the robot coordinate system and the image coordinate system are calibrated. Attached Figure Description

[0011] Figure 1 This is an overall structural diagram of the robot system involved in the first embodiment.

[0012] Figure 2 It is a diagram showing the hand used for calibration and the markings.

[0013] Figure 3 This is an example of an image obtained using a fixed camera.

[0014] Figure 4 It is a cross-sectional view of the label.

[0015] Figure 5 This is a top view of the sign.

[0016] Figure 6 It is a cross-sectional view showing the state in which the hand holds the mark.

[0017] Figure 7 This is a flowchart illustrating the calibration process.

[0018] Figure 8 This is a diagram showing the case where the identifier is positioned in the first position.

[0019] Figure 9 This is a diagram showing a first image obtained by taking a picture of a marker positioned in a first location.

[0020] Figure 10 This is a diagram showing an example of the coordinates of the second robot.

[0021] Figure 11 This is a diagram showing a second image obtained by taking a picture of the marker positioned in the first second position.

[0022] Figure 12 This is a diagram showing a second image obtained by taking a picture of the marker positioned at the second second location.

[0023] Figure 13 This is a diagram showing an example of the third position.

[0024] Figure 14 This is a diagram showing a third image obtained by taking a picture of the marker positioned in the first third position.

[0025] Figure 15 This is a cross-sectional view showing the identifier of the robot system according to the second embodiment.

[0026] Figure 16 It is a diagram showing a hand.

[0027] Figure 17 This is a diagram showing the state in which the sign is held by hand.

[0028] Figure 18 This is a cross-sectional view showing the hand and markings involved in the third embodiment.

[0029] Figure 19 It is a cross-sectional view used to illustrate hand movements.

[0030] Figure 20 It is a cross-sectional view used to illustrate hand movements.

[0031] Figure 21 It is a sectional view used to illustrate hand movements.

[0032] Figure 22 It is a cross-sectional view used to illustrate hand movements.

[0033] Figure 23 It is a cross-sectional view used to illustrate hand movements.

[0034] Figure 24 It is a sectional view used to illustrate hand movements.

[0035] Figure 25 This is a diagram illustrating the structure of the robot system according to the fourth embodiment.

[0036] Figure 26 This is a flowchart illustrating the calibration process.

[0037] Figure 27 This is a diagram showing a first image obtained by taking a picture of a marker positioned in a first location.

[0038] Figure 28 This is a diagram showing an example of the coordinates of the second robot.

[0039] Figure 29 This is a diagram showing a second image obtained by taking a picture of a marker positioned at a first location using the first second robot coordinate system.

[0040] Figure 30 This is a diagram showing a second image obtained by taking a picture of a marker positioned at a first location at a second second robot coordinate.

[0041] Figure 31 This is a diagram showing an example of the coordinates of a third robot.

[0042] Figure 32 This is an example of a third image obtained by taking a picture of a marker positioned at a first location at each third robot coordinate.

[0043] Figure 33 This is a diagram showing a third image obtained by taking a picture of a marker positioned at a first location using the first third robot coordinate system.

[0044] Explanation of reference numerals in the attached figures

[0045] 1…Robot system, 10…Working surface, 2…Robot, 21…Base, 22…Mechanical arm, 221…First arm, 222…Second arm, 223…Third arm, 224…Fourth arm, 225…Fifth arm, 226…Sixth arm, 24…Hand, 251…First drive unit, 252…Second drive unit, 253…Third drive unit, 254…Fourth drive unit, 255…Fifth drive unit, 256…Sixth drive unit, 29…Hand, 291…Base, 291a…Recess, 291b…Through hole, 291g…Guide, 292…Suction nozzle, 293…Claw, 293a…Engaging part, 294…Claw, 294a…Engaging part, 295…Pressing part, 295a…Displacement 295b…protrusion, 296…coil spring, 297…locking release part, 297a…hole, 297b…sloping surface, 298…pin, 298a…operating part, 299…coil spring, 4…fixed camera, 5…control device, 6…marker, 61…base, 61g…guide part, 611…recess, 611b…bottom surface, 611g…guide part, 612…recess, 62…flange, 63…sealing part, 8…robot camera, 80…adapter, G…image, G1…first image, G2…second image, G21…second image, G22…second image, G3…third image, G31…third image, O1…first rotating shaft, O2…second rotating shaft, O3…third rotating shaft O4…Fourth rotation axis, O5…Fifth rotation axis, O6…Sixth rotation axis, P1…First position, P2…Second position, P21…Second position, P22…Second position, P3…Third position, P31…Third position, P32…Third position, P33…Third position, P34…Third position, P35…Third position, P36…Third position, P37…Third position, P38…Third position, P39…Third position, Pr1…First robot coordinates, Pr2…Second robot coordinates, Pr21…Second robot coordinates, Pr22…Second robot coordinates, Pr3…Third robot coordinates, Pr31…Third robot coordinates, Pr32…Third robot coordinates, Pr33…Third robot coordinates Coordinates, Pr34… Third robot coordinates, Pr35… Third robot coordinates, Pr36… Third robot coordinates, Pr37… Third robot coordinates, Pr38… Third robot coordinates, Pr39… Third robot coordinates, R… Field of view, S1… Pre-calibration process, S11… First robot coordinate acquisition step, S12… First image coordinate acquisition step, S13… Second image coordinate acquisition step, S14… Pre-calibration step, S2… Calibration process, S21… Third position setting step, S22… Third robot coordinate and third image coordinate acquisition step, S23… Calibration step, S3… Pre-calibration process, S31… First robot coordinate acquisition step, S32… First image coordinate acquisition step,S33…Second image coordinate acquisition step, S34…Pre-calibration step, S4…Calibration process, S41…Third robot coordinate setting step, S42…Third image coordinate acquisition step, S43…Calibration step, TCP…Tool center point, W…Workpiece. Detailed Implementation

[0046] The robot system, marking, and calibration method of the present invention will now be described in detail based on the preferred embodiments shown in the accompanying drawings.

[0047] First Implementation Method

[0048] Figure 1 This is an overall structural diagram of the robot system involved in the first embodiment. Figure 2 It is a diagram showing the hand used for calibration and the markings. Figure 3 This is an example of an image obtained using a fixed camera. Figure 4 It is a cross-sectional view of the label. Figure 5 This is a top view of the sign. Figure 6 It is a cross-sectional view showing the state in which the hand holds the mark. Figure 7 This is a flowchart illustrating the calibration process. Figure 8 This is a diagram showing the case where the identifier is positioned in the first position. Figure 9 This is a diagram showing a first image obtained by taking a picture of a marker positioned in a first location. Figure 10 This is a diagram showing an example of the coordinates of the second robot. Figure 11 This is a diagram showing a second image obtained by taking a picture of the marker positioned in the first second position. Figure 12 This is a diagram showing a second image obtained by taking a picture of the marker positioned at the second second location. Figure 13 This is a diagram showing an example of the third position. Figure 14 This is a diagram showing a third image obtained by taking a picture of the marker positioned in the first third position.

[0049] Figure 1 The robot system 1 shown includes: a robot 2 that performs a predetermined operation on a workpiece W disposed on a work surface 10; a fixed camera 4, serving as a camera unit, fixed in space; and a control device 5, serving as a control unit, that controls the drive of the robot 2. These components are connected in a communicative manner via wired, wireless, or other means. Robot system 1 as shown... Figure 2As shown, it also has a symbol 6, which is used when calibrating (establishing correspondence) the image coordinate system set on the fixed camera 4 and the robot coordinate system set on the robot 2. In such a robot system 1, firstly, the image coordinate system and the robot coordinate system are calibrated using symbol 6, and then the drive of the robot 2 is controlled based on the image captured by the fixed camera 4 to perform a predetermined operation on the workpiece W. Hereinafter, each part constituting the robot system 1 will be described in turn.

[0050] Robot 2

[0051] Robot 2 is a 6-axis robot with 6 rotational axes, such as... Figure 1 As shown, the robot has a base 21 fixed to a floor, ceiling, etc., and a robotic arm 22 connected to the base 21. The robotic arm 22 has: a first arm 221 rotatable about a first rotation axis O1 relative to the base 21; a second arm 222 rotatable about a second rotation axis O2 relative to the first arm 221; a third arm 223 rotatable about a third rotation axis O3 relative to the second arm 222; a fourth arm 224 rotatable about a fourth rotation axis O4 relative to the third arm 223; a fifth arm 225 rotatable about a fifth rotation axis O5 relative to the fourth arm 224; a sixth arm 226 rotatable about a sixth rotation axis O6 relative to the fifth arm 225; and a hand 24 mounted on the sixth arm 226. The hand 24 can be appropriately selected according to the task performed by the robot 2.

[0052] Additionally, a tool center point (hereinafter referred to as "TCP") is set on the robotic arm 22 as a control point. The position and orientation of the TCP serve as the reference for the position and orientation of the hand 24 and the hand 29 described later. In this embodiment, a TCP is provided at the end of the hand 24, but the position of the TCP is not particularly limited.

[0053] In addition, such as Figure 1 As shown, robot 2 includes: a first drive unit 251 for rotating a first arm 221 relative to a base 21; a second drive unit 252 for rotating a second arm 222 relative to the first arm 221; a third drive unit 253 for rotating a third arm 223 relative to the second arm 222; a fourth drive unit 254 for rotating a fourth arm 224 relative to the third arm 223; a fifth drive unit 255 for rotating a fifth arm 225 relative to the fourth arm 224; and a sixth drive unit 256 for rotating a sixth arm 226 relative to the fifth arm 225. The first to sixth drive units 251 to 256 each include, for example, a motor, a speed reducer for reducing the rotation of the motor and transmitting it to the arm, and an encoder for detecting the amount of rotation of the motor (the amount of rotation of the arm). Furthermore, the driving of the first to sixth drive units 251 to 256 is independently controlled by a control unit 5.

[0054] In this robot 2, a robot coordinate system is established for controlling the drive of the robot 2. The robot coordinate system is a three-dimensional orthogonal coordinate system defined by mutually orthogonal X-axis, Y-axis, and Z-axis. In this embodiment, the orthogonal coordinate system is established with the Z-axis along the vertical direction. In addition, for example, the unit of the robot coordinate system is "mm".

[0055] In addition, such as Figure 2 As shown, robot 2 also has a hand 29 for calibrating the image coordinate system and the robot coordinate system. During calibration, hand 29 is mounted on the sixth arm 226. Hand 29 has a base 291 mounted on the sixth arm 226 and a cylindrical suction nozzle 292 protruding from the base 291 along the sixth rotation axis O6, which can adsorb and hold the mark 6.

[0056] The above description pertains to Robot 2, but Robot 2 is not particularly limited. For example, the number of arms in the robotic arm 22 could be 1 to 5 or more. Furthermore, Robot 2 could also be, for example, a SCARA robot (horizontal articulated robot), a dual-arm robot with two robotic arms 22, etc.

[0057] Fixed camera 4

[0058] like Figure 1 As shown, the fixed camera 4 is located above the work surface 10, fixed in a position opposite to the work surface 10. The fixed camera 4 also captures images of the workpiece W on the work surface 10. The fixed camera 4 is a digital camera equipped with a lens and a surface image sensor. Furthermore, as... Figure 3 As shown, an image coordinate system is established in the image G acquired by the fixed camera 4. The image coordinate system is a two-dimensional orthogonal coordinate system defined by the A-axis along the horizontal direction and the B-axis along the vertical direction of image G. Furthermore, for example, the unit of the image coordinate system is a "pixel". Here, in order for the control device 5 to identify the workpiece W on the working surface 10 based on image G and to control the drive of the robot 2 based on the identification result, calibration of the image coordinate system and the robot coordinate system is required. The calibration method will be described later.

[0059] The above describes the fixed camera 4, but the structure and configuration of the fixed camera 4 are not particularly limited.

[0060] Control device 5

[0061] The control device 5 controls the driving of both the robot 2 and the fixed camera 4. Furthermore, the control device 5 calibrates the image coordinate system set on the fixed camera 4 and the robot coordinate system set on the robot 2. This control device 5 is configured, for example, to include a computer, and has a processor for processing information, a memory connected to the processor in a communicative manner, and an external interface. The memory stores various programs that can be executed by the processor, and the processor reads and executes these programs and data stored in the memory. Thus, the computer functions as the control device 5.

[0062] It should be noted that in the structure shown in the figure, the control device 5 is disposed outside the robot 2, but the configuration of the control device 5 is not particularly limited. For example, it may be partially or entirely housed inside the robot 2. In addition, for example, the control device 5 may be configured as a drive control device that controls the drive of the robot 2 and the fixed camera 4, and a calibration device that calibrates the image coordinate system and the robot coordinate system.

[0063] Mark 6

[0064] As mentioned above, label 6 refers to the fixture used during the calibration of the image coordinate system and the robot coordinate system. Figure 4 as well as Figure 5 As shown, when the identifier 6 is disposed on the working surface 10, it has: a cylindrical base 61 extending in a direction orthogonal to the working surface 10; and an annular flange 62 protruding radially from the outer peripheral surface of the base 61. The base 61 and the flange 62 are arranged concentrically. Furthermore, the base 61 has a bottomed recess 611 with an opening on its upper surface. And, as... Figure 6 As shown, the suction nozzle 292 is inserted into the recess 611. Furthermore, the upper end of the recess 611 is frustum-shaped (conical), with its inner diameter gradually increasing towards the upper end. This conical inner circumferential surface functions as a guide portion 611g, which guides the suction nozzle 292 into the recess 611.

[0065] In addition, such as Figure 6 As shown, the outer diameter of the adsorption nozzle 292 is approximately equal to the inner diameter of the recess 611. Therefore, with the adsorption nozzle 292 inserted into the recess 611, the mark 6 does not substantially shift relative to the adsorption nozzle 292. Thus, by inserting the adsorption nozzle 292 into the recess 611, the mark 6 is automatically positioned at a predetermined position relative to the adsorption nozzle 292. In other words, the mark 6 is self-aligned with the adsorption nozzle 292.

[0066] Furthermore, the adsorption nozzle 292 holds the mark 6 by adsorbing the bottom surface 611b of the adsorption recess 611. This allows the mark 6 to be easily held in its positioned state. In particular, in this embodiment, the mark 6 has an annular sealing portion 63 disposed along the outer edge of the bottom surface 611b. The sealing portion 63 is made of, for example, various rubber materials that are elastic and airtight. When the adsorption nozzle 292 adsorbs the bottom surface 611b, the sealing portion 63 is sandwiched between the adsorption nozzle 292 and the bottom surface 611b, improving the seal between the adsorption nozzle 292 and the bottom surface 611b. With this structure, a high adsorption force can be achieved, and the mark 6 can be held more reliably by using the adsorption nozzle 292.

[0067] The flange portion 62 protrudes radially from the outer peripheral surface of the base 61. This flange portion 62 is an image recognition unit used to identify the outline of the mark 6 on the image G of the fixed camera 4. Thus, the flange portion 62 protrudes sufficiently outward from the base 61 on the image G, so that a portion of the flange portion 62 is not obscured or hidden by the base 61. Furthermore, the flange portion 62 is configured to be biased towards the lower end side of the base 61 and is formed to be sufficiently thinner than the base 61. In particular, in this embodiment, the lower end surfaces of the base 61 and the flange portion 62 are coplanar, and the lower surfaces of both the base 61 and the flange portion 62 are in contact with the working surface 10. It should be noted that the thickness of the flange portion 62 is not particularly limited, but is preferably, for example, 1.0 mm or less. By forming the flange portion 62 to be relatively thin and configuring it to be biased towards the lower end side of the base 61, the upper surface of the flange portion 62 can be made close to the working surface 10, enabling more accurate detection of the position of the mark 6 on the image G.

[0068] The aforementioned marking 6 is made of various metal materials such as aluminum, stainless steel (SUS), and steel. By using such materials, the marking 6 achieves a suitable strength and weight, making it difficult for deformation or deviation during calibration to occur. Therefore, calibration can be performed with high accuracy. Furthermore, the working surface 10 is white, while the marking 6 is black, specifically a low-gloss black that effectively suppresses light reflection. By setting the marking 6 to a different color from the working surface 10, the position of the marking 6 on the image can be detected with greater accuracy, enabling high-precision calibration. In particular, as in this embodiment, by setting the working surface 10 to white and the marking 6 to black, the contrast is increased. Moreover, since it is a low-gloss black, light reflection is sufficiently suppressed, effectively suppressing distortion and blurring of the shape (outline) of the marking 6 on the image. Thus, the aforementioned effects become even more significant. It should be noted that the method of setting the surface of the marking 6 to black is not particularly limited and varies depending on the structural material of the marking 6; examples include black chrome plating, black zinc plating, black electroless nickel plating, and black anodizing.

[0069] This structure provides a simple design suitable for calibration, resulting in the mark 6. The mark 6 has been described above, but its structure is not particularly limited. For example, the flange 62 can be omitted. Furthermore, the mark 6 can be made of various ceramic materials, resin materials, or other materials different from metal. Additionally, the top-view shape of the base 61 and flange 62 is not limited to a circle; for example, it can be a quadrilateral, hexagon, etc. Moreover, the base 61 and flange 62 can be formed separately, or each can be a different color.

[0070] The overall structure of robot system 1 has been described above. Next, the calibration method between the image coordinate system and the robot coordinate system performed by control device 5 will be explained. Figure 7 As shown, the calibration method includes a pre-calibration step S1 and a calibration step S2. It should be noted that the settings for various driving conditions, image G distortion correction, and other calibration requirements are assumed to be completed before the pre-calibration step S1. Furthermore, the calibration method is as follows... Figure 2 As shown, this is performed with the hand 29 attached to the sixth arm 226.

[0071] Pre-calibration process S1

[0072] First, the first robot coordinate acquisition step S11 is performed. In the first robot coordinate acquisition step S11, the hand 29 is used to place the marker 6 at the first position P1 on the working surface 10, and the position of the robotic arm 22 in the robot coordinate system when the marker 6 is placed at the first position P1 is obtained as the "first robot coordinate Pr1". It should be noted that the first position P1 is located within the field of view R of the fixed camera 4.

[0073] In this step, firstly, as the first step, the control device 5 drives the robot 2 to use the hand 29 to adhere to and hold the tag 6. Additionally, at this time, the tag 6 self-aligns and is positioned at a predetermined location relative to the hand 29. Next, as... Figure 8As shown, as a second step, the control device 5 drives the robot 2 to deliver the marker 6, held by the hand 29, to a first position P1 on the work surface 10 and positions it there. It should be noted that this step is performed via jogging. Jogging refers to a method where, for example, the operator inputs guidance instructions using an input device such as a teach pendant, and the control device 5 drives the robot 2 based on these instructions. Furthermore, the first position P1 is not preset and can be arbitrarily determined by the operator. Preferably, the first position P1 is the center of the field of view R. This is because, although image G distortion correction is performed, the distortion is less at the center of image G than at the edges, thus improving position detection accuracy. Next, as a third step, the control device 5 detects the position of the robotic arm 22 in the robot coordinate system when the marker 6 is positioned at the first position P1 and uses this position as the first robot coordinate Pr1.

[0074] It should be noted that in this embodiment, the first robot coordinate Pr1 is obtained as the TCP position of the robotic arm 22. The same applies to the second robot coordinate Pr2 and the third robot coordinate Pr3, which will be described later. Which point of the robotic arm 22 is used as the reference for the position is arbitrary.

[0075] After the above processing, step S11 of obtaining the coordinates of the first robot ends.

[0076] Next, the first image coordinate acquisition step S12 is performed. In the first image coordinate acquisition step S12, the fixed camera 4 is used to capture the identifier 6 located at the first position P1. Based on the obtained first image G1, the position of the identifier 6 in the image coordinate system is obtained as the "first image coordinate Pp1".

[0077] In this step, firstly, as the fourth step, the control device 5 moves the drive robot 2, the robotic arm 22, and the hand 29 out of the field of view R of the fixed camera 4. This suppresses the projection of the robot 2 into the image G. Next, as the fifth step, the control device 5 uses the fixed camera 4 to photograph the marker 6 located at the first position P1, obtaining... Figure 9 The first image G1 is shown. Next, as the sixth step, the control device 5 uses a predetermined image processing technique to identify the identifier 6 in the first image G1 and obtain the position of the identifier 6 in the image coordinate system, i.e., the first image coordinates Pp1.

[0078] It should be noted that in this embodiment, the first image coordinate Pp1 is obtained as the center position of the identifier 6. The same applies to the second image coordinate Pp2 and the third image coordinate Pp3, which will be described later. Which point of the identifier 6 is used as the reference for the position is arbitrary.

[0079] After the above processing, step S12 of obtaining the first image coordinates ends.

[0080] Next, the second image coordinate acquisition step S13 is performed. In the second image coordinate acquisition step S13, the robotic arm 22 is positioned at the second robot coordinate Pr2, which is separated from the first robot coordinate Pr1. The identifier 6 is placed at the second position P2 on the working surface 10. The fixed camera 4 is used to capture the identifier 6 placed at the second position P2. Based on the obtained second image G2, the position of the identifier 6 in the image coordinate system is obtained as the "second image coordinate Pp2".

[0081] In this step, firstly, as the seventh step, the control device 5 determines the second robot coordinate Pr2. In this embodiment, as... Figure 10 As shown, the second robot coordinate Pr2 is set with two points. The first second robot coordinate Pr21 is separated from the first robot coordinate Pr1 along the X-axis by +10mm in the robot coordinate system. The second second robot coordinate Pr22 is separated from the second robot coordinate Pr21 along the Y-axis in the robot coordinate system by +10mm. That is, the second robot coordinate Pr22 is separated from the first robot coordinate Pr1 by +10mm along the X-axis and +10mm along the Y-axis in the robot coordinate system. The number and configuration of the second robot coordinates Pr2 are not particularly limited; for example, it is also possible to use only the second robot coordinates Pr22.

[0082] Furthermore, the second position P2 has a second position P21 where the identifier 6 is positioned by the robotic arm 22 located at the second robot coordinate Pr21, and a second position P22 where the identifier 6 is positioned by the robotic arm 22 located at the second robot coordinate Pr22. Moreover, these second positions P21 and P22 are respectively located within the field of view R of the fixed camera 4. In particular, it is preferable that the second positions P21 and P22 are respectively the center of the field of view R of the fixed camera 4. This is because the distortion is less at the center of the image G than at the edges, thus improving the position detection accuracy.

[0083] Next, as the eighth step, the control device 5 drives the robot 2, using the hand 29 to hold the marker 6, and positions the robotic arm 22 at the second robot coordinate Pr21, thereby placing the marker 6 at the second position P21 on the work surface 10. Next, as the ninth step, after the control device 5 moves the robot 2 out of the field of view R of the fixed camera 4, it uses the fixed camera 4 to photograph the marker 6 located at the second position P21, obtaining... Figure 11 The second image G21 is shown. Then, as the tenth step, the control device 5 uses a predetermined image processing technique to identify the identifier 6 in the second image G21 and obtain the position of the identifier 6 in the image coordinate system, i.e., the second image coordinates Pp21.

[0084] Next, as the eleventh step, the robot 2 is driven to hold the marker 6 using its hand 29. By positioning the robotic arm 22 at the second robot coordinate Pr22, the marker 6 is placed at the second position P22 on the work surface 10, thus positioning the marker 6 at this position. Next, as the twelfth step, after the control device 5 moves the robot 2 out of the field of view R of the fixed camera 4, the fixed camera 4 photographs the marker 6 located at the second position P22, obtaining... Figure 12 The second image G22 is shown. Then, as the thirteenth step, the control device 5 uses a predetermined image processing technique to identify the identifier 6 in the second image G22 and obtain the position of the identifier 6 in the image coordinate system, i.e., the second image coordinates Pp22.

[0085] After the above processing, step S13 of obtaining the second image coordinates ends.

[0086] Next, a pre-calibration step S14 is performed. In the pre-calibration step S14, the robot coordinate system and the image coordinate system are pre-calibrated based on the first robot coordinate Pr1, the second robot coordinate Pr21, Pr22, the first image coordinate Pp1, and the second image coordinate Pp21, Pp22 obtained in the above steps S11 to S13.

[0087] Here, the result of steps S11 to S13 performed by the control device 5 is that it obtains three sets of [robot coordinates / image coordinates], namely [first robot coordinate Pr1 / first image coordinate Pp1], [second robot coordinate Pr21 / second image coordinate Pp21] and [second robot coordinate Pr22 / second image coordinate Pp22].

[0088] Therefore, in this step, as the fourteenth step, the control device 5 calculates the coordinate transformation formula for converting the image coordinates to the robot coordinates based on these three sets of [robot coordinates / image coordinates]. Simply put, it calculates which movement of 1 pixel in the A-axis and B-axis directions in the image coordinate system corresponds to a movement of a few millimeters in the robot coordinate system. Thus, the pre-calibration of the image coordinate system and the robot coordinate system is completed. It should be noted that the pre-calibration is a coarse calibration with lower precision than the subsequent calibration step S2, and serves as a preparation for the smooth and reliable execution of calibration step S2.

[0089] Calibration process S2

[0090] In the calibration process S2, firstly, the third position setting step S21 is performed, in which multiple third positions P3 are set on the working surface 10.

[0091] In this step, firstly, as the fifteenth step, the control device 5 is based on the image coordinate system, such as... Figure 13As shown, nine third positions P3 are set on the working surface 10. It should be noted that the nine third positions P3 are located within the field of view R of the fixed camera 4. Furthermore, in this embodiment, the nine third positions P3 are arranged in a 3×3 matrix and are uniformly distributed throughout the entire field of view R. This configuration suppresses the skewness of the marker 6 within the image G, enabling higher precision calibration. Hereinafter, for ease of explanation, the nine third positions P3 will sometimes be described as third positions P31 to P39.

[0092] After the above processing, step S21 of setting the third position is completed. It should be noted that the number of third positions P3 is not particularly limited if there are two or more. Furthermore, the configuration of the third positions P3 is not particularly limited.

[0093] Next, the third robot coordinate and third image coordinate acquisition step S22 is performed. In the third robot coordinate and third image coordinate acquisition step S22, the identifier 6 is sequentially configured in 9 third positions P3, and the position of the robotic arm 22 in the robot coordinate system when the identifier 6 is configured in the third position P3 is obtained as the "third robot coordinate Pr3". The identifier 6 is photographed by the fixed camera 4, and the position of the identifier 6 in the image coordinate system is obtained based on the obtained third image G3 as the "third image coordinate Pp3".

[0094] In this step, firstly, as the sixteenth step, the control device 5 drives the robot 2 based on the result of the pre-calibration process S1 (hereinafter also referred to as the "pre-calibration result") to transport the marker 6 to the third position P31 and place it there. Next, as the seventeenth step, the control device 5 detects the position of the robotic arm 22 in the robot coordinate system when the marker 6 is placed in the third position P31, i.e., the third robot coordinate Pr31. Next, as the eighteenth step, after the robot 26 retracts outside the field of view R of the fixed camera 4, the control device 5 uses the fixed camera 4 to photograph the marker 6 located at the third position P31, obtaining... Figure 14 The third image G31 is shown. Then, as the nineteenth step, the control device 5 uses a predetermined image processing technique to identify the identifier 6 in the third image G31 and obtain the position of the identifier 6 in the image coordinate system, i.e., the third image coordinate Pp31. Through the above processing, the third robot coordinate Pr31 and the third image coordinate Pp31 corresponding to the third position P31 are obtained.

[0095] Next, as the twentieth step, the control device 5 repeats the same operation as steps sixteen to nineteen for the third positions P32 to P39, sequentially acquiring the third robot coordinate Pr32 and the third image coordinate Pp32 corresponding to the third position P32, the third robot coordinate Pr33 and the third image coordinate Pp33 corresponding to the third position P33, the third robot coordinate Pr34 and the third image coordinate Pp34 corresponding to the third position P34, the third robot coordinate Pr35 and the third image coordinate Pp35 corresponding to the third position P35, the third robot coordinate Pr36 and the third image coordinate Pp36 corresponding to the third position P36, the third robot coordinate Pr37 and the third image coordinate Pp37 corresponding to the third position P37, the third robot coordinate Pr38 and the third image coordinate Pp38 corresponding to the third position P38, and the third robot coordinate Pr39 and the third image coordinate Pp39 corresponding to the third position P39.

[0096] After the above processing, step S22, which involves obtaining the third robot coordinates and the third image coordinates, is completed.

[0097] Next, calibration step S23 is performed. In calibration step S23, the robot coordinate system and the image coordinate system are calibrated based on the nine third robot coordinates Pr31 to Pr39 and the nine third image coordinates Pp31 to Pp39.

[0098] Here, the result of step S22 performed by the control device 5 is that it acquires 9 sets of [robot coordinates / image coordinates], namely [third robot coordinate Pr31 / third image coordinate Pp31], [third robot coordinate Pr32 / third image coordinate Pp32], [third robot coordinate Pr33 / third image coordinate Pp33], [third robot coordinate Pr34 / third image coordinate Pp34], [third robot coordinate Pr35 / third image coordinate Pp35], [third robot coordinate Pr36 / third image coordinate Pp36], [third robot coordinate Pr37 / third image coordinate Pp37], [third robot coordinate Pr38 / third image coordinate Pp38], and [third robot coordinate Pr39 / third image coordinate Pp39].

[0099] Therefore, in this step, as the twenty-first step, the control device 5 calculates the coordinate transformation formula for converting the image coordinates to robot coordinates based on these nine sets of [robot coordinates / image coordinates]. Thus, the calibration of the image coordinate system and the robot coordinate system is completed.

[0100] The calibration method for the image coordinate system and the robot coordinate system has been explained above. This calibration method eliminates the need for finishing work required in existing technologies, thus preventing operator-induced deviations. Therefore, it effectively suppresses the reduction in calibration accuracy and deviations. Furthermore, calibration can be performed without the use of force sensors, simplifying the device structure. Additionally, since there is no direct contact between the hand 29 and the work surface 10 as in finishing work, it effectively suppresses impacts and other damage to the work surface 10.

[0101] The above describes robot system 1. As described above, robot system 1 includes: a robot 2 having a robotic arm 22 with a hand 29; a marker 6 held by the hand 29 and self-aligned relative to the hand 29; a fixed camera 4 serving as an imaging unit, fixed at a position opposite to the work surface 10, for imaging the marker 6 on the work surface 10; and a control device 5 serving as a control unit for calibrating the robot coordinate system set in the robot 2 with the image coordinate system set in the fixed camera 4. Furthermore, the control device 5 acquires the position of the robotic arm 22 in the robot coordinate system, i.e., the first robot coordinate Pr1, when the marker 6 is placed at the first position P1 on the work surface 10 using the hand 29. It then uses the fixed camera 4 to capture an image of the marker 6 placed at the first position P1. Based on the obtained first image G1, it acquires the position of the marker 6 in the image coordinate system, i.e., the first image coordinate Pp1. After holding the marker 6 with the hand 29, the robotic arm 22 is positioned at the second robot coordinate Pr2, separated from the first robot coordinate Pr1. The marker 6 is then placed at the second position P2 on the work surface 10. The fixed camera 4 captures an image of the marker 6 placed at the second position P2. Based on the obtained second image G2, it acquires the position of the marker 6 in the image coordinate system, i.e., the second image coordinate Pp2. Based on the first robot coordinate Pr1 and the second robot coordinate Pr2, the control device 5 acquires the position of the robotic arm 22 in the robot coordinate system, i.e., the first robot coordinate Pr1 and the second robot coordinate Pp2. The robot coordinate system and the image coordinate system are pre-calibrated using coordinates Pr2, the first image coordinates Pp1, and the second image coordinates Pp2. Based on the image coordinate system, multiple third positions P3 are set within the field of view R of the fixed camera 4 located on the work surface 10. Based on the pre-calibration results, the robot 2 is driven to sequentially place the marker 6, which is held by the hand 29, into the multiple third positions P3. Each time, the position of the robotic arm 22 in the robot coordinate system when the marker 6 is placed in the third position P3 is acquired, i.e., the third robot coordinate Pr3. The fixed camera 4 is used to photograph the marker 6, and the position of the marker 6 in the image coordinate system, i.e., the third image coordinate Pp3, is obtained based on the obtained third image G3. Based on the multiple third robot coordinates Pr3 and the multiple third image coordinates Pp3, the robot coordinate system and the image coordinate system are calibrated. With this structure, the fine processing work required by existing technologies is not required, and therefore, deviations originating from the operator are not generated. Therefore, the reduction in calibration accuracy and deviations can be effectively suppressed.

[0102] Furthermore, as mentioned above, the mark 6 has a cylindrical base 61. When positioned on the working surface 10, the base 61 extends in a direction orthogonal to the working surface 10 and has a recess 611 for inserting a hand 29. The mark 6 is positioned relative to the hand 29 by inserting the hand 29 into the recess 611. This structure allows for easy positioning of the mark 6 relative to the hand 29.

[0103] Additionally, as mentioned above, the marking 6 has a guide portion 611g that guides the hand 29 toward the recess 611. This structure facilitates the insertion of the hand 29 into the recess 611.

[0104] Additionally, as mentioned earlier, the recess 611 has a bottom, and the hand 29 can adhere to and hold the bottom surface 611b of the recess 611. This structure allows for easy holding of the mark 6.

[0105] Furthermore, as mentioned above, the sign 6 has a sealing portion 63 located between the bottom surface 611b and the hand 29, which airtightly seals the bottom surface 611b and the hand 29. This structure allows for more reliable holding of the sign 6 using the hand 29.

[0106] Furthermore, as mentioned above, the identifier 6 has an annular flange 62 that protrudes radially from the outer peripheral surface of the base 61. With this structure, the outline of the identifier 6 in the image G is formed by the flange 62, enabling accurate detection of the identifier 6's position.

[0107] Additionally, as mentioned earlier, the identifier 6 is used for calibration of the robot coordinate system and the image coordinate system. The robot coordinate system is set on the robot 2, which has a robotic arm 22 with a hand 29. The image coordinate system is set on a fixed camera 4, which serves as the imaging unit, and the fixed camera 4 images the work surface 10. When the identifier 6 is positioned on the work surface 10, it has: a base 61 extending in a direction orthogonal to the work surface 10 and held by the hand 29; and an annular flange 62 protruding outward from the base 61 when viewed from above on the work surface 10. With this structure, the identifier 6 becomes a structure that is easy to hold using the hand 29 and easy to identify through image recognition.

[0108] Furthermore, as mentioned above, the calibration method is a method for calibrating the robot coordinate system and the image coordinate system in robot system 1. Robot system 1 includes: a robot 2 with a robotic arm 22, the robotic arm 22 having a hand 29; a marker 6 that can be held by the hand 29 and can self-align relative to the hand 29; and a fixed camera 4 as a shooting unit, fixed at a position opposite to the work surface 10, for shooting the marker 6 on the work surface 10. The robot coordinate system is set in robot 2, and the image coordinate system is set in fixed camera 4. Such a calibration method includes a pre-calibration step S1 and a calibration step S2. In addition, in the pre-calibration process S1, the position of the robotic arm 22 in the robot coordinate system, i.e., the first robot coordinate Pr1, is obtained when the marker 6 is placed at the first position P1 on the work surface 10 using the hand 29. The marker 6 placed at the first position P1 is photographed using the fixed camera 4. Based on the obtained first image G1, the position of the marker 6 in the image coordinate system, i.e., the first image coordinate Pp1, is obtained. After the marker 6 is held by the hand 29, the robotic arm 22 is positioned at the second robot coordinate Pr2, which is separated from the first robot coordinate Pr1. The marker 6 is placed at the second position P2 on the work surface 10. The marker 6 placed at the second position P2 is photographed using the fixed camera 4. Based on the obtained second image G2, the position of the marker 6 in the image coordinate system, i.e., the second image coordinate Pp2, is obtained. Based on the first robot coordinate Pr1, the second robot coordinate Pr2, the first image coordinate Pp1, and the second image coordinate Pp2, the robot coordinate system and the image coordinate system are pre-calibrated. Furthermore, in calibration step S2, based on the image coordinate system, multiple third positions P3 are set within the field of view R of the fixed camera 4 located on the work surface 10. Based on the pre-calibrated results, the robot 2 is driven to sequentially place the marker 6, which is held by the hand 29, into the multiple third positions P3. Each time, the position of the robotic arm 22 in the robot coordinate system when the marker 6 is placed in the third position P3 is acquired, i.e., the third robot coordinate Pr3. The fixed camera 4 then photographs the marker 6, and the position of the marker 6 in the image coordinate system, i.e., the third image coordinate Pp3, is obtained based on the obtained third image G3. Based on the multiple third robot coordinates Pr3 and the multiple third image coordinates Pp3, calibration of the robot coordinate system and the image coordinate system is performed. This method eliminates the need for the fine-machining operations required in existing technologies, thus avoiding operator-induced deviations. Therefore, it effectively suppresses the reduction in calibration accuracy and deviations.

[0109] Second Implementation Method

[0110] Figure 15 This is a cross-sectional view showing the identifier of the robot system according to the second embodiment. Figure 16 It is a diagram showing a hand. Figure 17 This is a diagram showing the state in which the sign is held by hand.

[0111] The robot system 1 in this embodiment is identical to that in the first embodiment, except for the structure of the identifier 6 and the hand 29. In the following description, this embodiment will be described primarily based on the differences from the first embodiment, and descriptions of identical items will be omitted. Furthermore, in the figures of this embodiment, the same reference numerals are used to label structures identical to those in the aforementioned embodiment.

[0112] like Figure 15 As shown, when the identifier 6 is disposed on the working surface 10, it has: a cylindrical base 61 extending in a direction orthogonal to the working surface 10; and an annular flange 62 protruding radially from the outer peripheral surface of the base 61. The base 61 and the flange 62 are arranged concentrically.

[0113] On the other hand, such as Figure 16 As shown, the hand 29 has a base 291 and a pair of claws 293 and 294, which clamp and hold the base 61 of the mark 6 from both sides. Additionally, as... Figure 17 As shown, the surface of the claw 293 that abuts against the base 61 has an engaging portion 293a composed of a triangular recess, and the surface of the claw 294 that abuts against the base 61 has an engaging portion 294a composed of a triangular recess. In the hand 29 with this structure, if the claws 293 and 294 are used to clamp and hold the base 61 of the mark 6 from both sides, the base 61 engages with the engaging portions 293a and 294a, and the mark 6 is automatically positioned (self-aligned) relative to the hand 29. With this structure, positioning the mark 6 relative to the hand 29 becomes easy. It should be noted that the structure of the engaging portions 293a and 294a is not particularly limited as long as they can engage and be positioned with the base 61.

[0114] As described above, the identifier 6 in this embodiment has a base 61, which extends in a direction orthogonal to the working surface 10 when disposed on the working surface 10. Furthermore, the hand 29 has a pair of claws 293 and 294 that grip the base 61 from both sides and hold the identifier 6. Each claw 293 and 294 has engaging portions 293a and 294a that engage with the base 61. Furthermore, when the identifier 6 is held by the hand 29, the identifier 6 is positioned relative to the hand 29 by the base 61 engaging with the engaging portions 293a and 294a. This structure allows for easy positioning of the identifier 6 relative to the hand 29.

[0115] This second implementation method can achieve the same effect as the first implementation method described above.

[0116] Third Implementation Method

[0117] Figure 18 This is a cross-sectional view showing the hand and markings involved in the third embodiment. Figures 19 to 24 These are cross-sectional views used to illustrate hand movements.

[0118] The robot system 1 in this embodiment is identical to that in the first embodiment, except for the structure of the identifier 6 and the hand 29. In the following description, this embodiment will be described primarily based on the differences from the first embodiment, and descriptions of identical items will be omitted. Furthermore, in the figures of this embodiment, the same reference numerals are used to label structures identical to those in the aforementioned embodiment.

[0119] like Figure 18 As shown, when the mark 6 is positioned on the working surface 10, it has: a cylindrical base 61 extending in a direction orthogonal to the working surface 10; and an annular flange 62 protruding radially from the outer peripheral surface of the base 61. The base 61 and the flange 62 are concentrically positioned. Furthermore, the end portion of the base 61 is frustum-shaped (conical), with its outer diameter gradually decreasing towards the upper end. This conical outer peripheral surface functions as a guide portion 61g, which guides the hand 29 to the mark 6. Additionally, an annular recess 612 is formed on the outer peripheral surface of the base 61. The recess 612 has a triangular cross-sectional shape, with its upper and lower inner peripheral surfaces each composed of inclined surfaces.

[0120] On the other hand, the hand 29 has a base 291, a pressing part 295, a coil spring 296 as a first force-applying part, a locking release part 297, a pair of pins 298, and a coil spring 299 as a second force-applying part.

[0121] The base 291 is fixed to the sixth arm 226. The base 291 has a bottomed recess 291a with an opening at its end face, and a through hole 291b that connects the recess 291a to the outer peripheral surface. The base 61 of the mark 6 is inserted into the recess 291a. The inner diameter of the recess 291a is approximately equal to the outer diameter of the base 61 of the mark 6, thus preventing any substantial movement of the mark 6 within the recess 291a. The end of the recess 291a is frustum-shaped (conical), with its inner diameter gradually increasing towards the end. This conical inner peripheral surface functions as a guide portion 291g, which guides the mark 6 to the hand 29. Even if the mark 6's central axes are misaligned when inserted into the recess 291a, the guide portions 61g and 291g slide against each other, allowing the mark 6 to be smoothly guided into the recess 291a.

[0122] The pressing part 295 has a displacement limiting part 295a inserted into the through hole 291b, and a protrusion 295b located within the recess 291a and protruding from the displacement limiting part 295a toward the end side. The pressing part 295 can move forward toward the end side and backward toward the base end side relative to the base 291. Specifically, the pressing part 295 abuts against the end portion of the through hole 291b via the displacement limiting part 295a, thus limiting further forward movement; and it abuts against the base end portion of the through hole 291b via the displacement limiting part 295a, thus limiting further backward movement. Furthermore, a coil spring 296 in a contracted state is disposed between the protrusion 295b and the base 291, and the pressing part 295 is forced toward the end side relative to the base 291 by the coil spring 296. Therefore, in its natural state, the displacement limiting part 295a abuts against the end portion of the through hole 291b.

[0123] A pair of pins 298 are configured symmetrically with respect to the central axis of the base 291. Furthermore, each of the pins 298 is disposed on the base 291 and is stressed towards the central axis (inner side) by a coil spring 299. Therefore, in its natural state, the ends of the pins 298 protrude into the recess 291a. Additionally, each pin 298 has an operating portion 298a located on the outer side of the base 291.

[0124] The locking release part 297 is cylindrical and covers the outer side of the base 291. Furthermore, the locking release part 297 is slidable relative to the base 291. Additionally, the locking release part 297 has a hole 297a with operating portions 298a for each pin 298. Furthermore, the inner circumferential surface at the lower end of the hole 297a becomes an inclined surface 297b inclined relative to the central axis.

[0125] In the hand 29 with such a structure, when the mark 6 is inserted into the recess 291a, as... Figure 19 As shown, each pin 298 is pushed outward from the recess 291a by the marking 6. Furthermore, if the marking 6 continues to be inserted into the recess 291a, the pressing part 295 is pushed by the marking 6, and with the contraction of the coil spring 296, the pressing part 295 retracts towards the base end relative to the base 291. Then, as... Figure 20 As shown, if the mark 6 is inserted to a position where the recess 612 overlaps with the pin 298, the pin 298 penetrates into the recess 612 and they engage. In this state, the recess 612 engages with the pin 298, and the mark 6 is pressed by the pressing part 295, thus firmly holding the mark 6 relative to the hand 29. Through the above process, the mark 6 is automatically positioned (self-aligned) relative to the hand 29.

[0126] Conversely, when releasing the held mark 6, firstly, the base 291 is moved towards the end side, causing the pin 298 to disengage from the recess 612. If the base 291 is moved further towards the end side, then as... Figure 21 As shown, the inclined surface 297b of the locking release part 297 enters between the operating part 298a of the pin 298 and the base 291, keeping the pin 298 retracted outside the recess 612. That is, the pin 298 is in a locked state. Next, if the hand 29 is moved towards the base end in a manner that pulls it out from the mark 6, the locked state is maintained, as... Figure 22 As shown, pin 298 does not protrude into recess 612; pin 298 passes through recess 612. If hand 29 is moved further towards the base end side, then as... Figure 23 As shown, by applying force to the end side of the locking release part 297 by the pressing part 295, the inclined surface 297b is pulled out from between the operating part 298a and the base 291. Thus, the locking state is released. Furthermore, if the hand 29 is moved further towards the base side, as... Figure 24 As shown, hand 29 is pulled out from mark 6.

[0127] As described above, the identifier 6 in this embodiment has a base 61 with a recess 612 on its outer peripheral surface. When disposed on the working surface 10, the base 61 extends in a direction orthogonal to the working surface 10. Furthermore, the hand 29 has a pin 298 as a protrusion, which is inserted into the recess 612. By inserting the pin 298 into the recess 612, the identifier 6 is held by the hand 29, thereby positioning the identifier 6 relative to the hand 29. With this structure, positioning the identifier 6 relative to the hand 29 can be easily achieved.

[0128] This third implementation method can achieve the same effect as the first implementation method described above.

[0129] Fourth Implementation Method

[0130] Figure 25 This is a diagram illustrating the structure of the robot system according to the fourth embodiment. Figure 26 This is a flowchart illustrating the calibration process. Figure 27 This is a diagram showing a first image obtained by taking a picture of a marker positioned in a first location. Figure 28 This is a diagram showing an example of the coordinates of the second robot. Figure 29 This is a diagram showing a second image obtained by taking a picture of a marker positioned at a first location using the first second robot coordinate system. Figure 30 This is a diagram showing a second image obtained by taking a picture of a marker positioned at a first location at a second second robot coordinate. Figure 31 This is a diagram showing an example of the coordinates of a third robot. Figure 32 This is an example of a third image obtained by taking a picture of a marker positioned at a first location at each third robot coordinate. Figure 33This is a diagram showing a third image obtained by taking a picture of a marker positioned at a first location using the first third robot coordinate system.

[0131] The robot system 1 of this embodiment is the same as that of the first embodiment described above, except for the structure of the imaging unit. In the following description, this embodiment will be described mainly for the differences from the first embodiment described above, and descriptions of the same items will be omitted. In addition, in the figures of this embodiment, the same reference numerals are used to mark the same structures as in the previous embodiment.

[0132] In the robot system 1 of this embodiment, the fixed camera 4 is omitted. Instead, as shown in the figure... Figure 25 As shown, the robot system 1 has a robot camera 8 as its imaging unit, which is mounted to the sixth arm 226 via an adapter 80. In other words, the robot camera 8 is located on the robotic arm 22. Furthermore, a hand 29 is mounted to the adapter 80. When working on the workpiece W, the hand 29 is detached from the adapter 80, and the working hand 24 is mounted back onto the adapter 80. The robot camera 8 captures images of the end face of the hand 29. Additionally, the robot camera 8 is configured to be offset relative to the sixth rotation axis O6, and the optical axis of the robot camera 8 is along the sixth rotation axis O6. This robot camera 8 is a digital camera equipped with a lens and a surface image sensor. Furthermore, an image coordinate system is established within the robot camera 8.

[0133] The above describes the robot camera 8, but its structure and configuration are not particularly limited. For example, the robot camera 8 can also be configured in any part other than the sixth arm 226 of the robotic arm 22, such as the fifth arm 225.

[0134] In the same way, in such a robot system 1, the image coordinate system and the robot coordinate system are first calibrated using the identifier 6. Then, the drive of the robot 2 is controlled based on the image captured by the robot camera 8 to perform the predetermined operation on the workpiece W.

[0135] The overall structure of robot system 1 has been described above. Next, the calibration method between the image coordinate system and the robot coordinate system performed by control device 5 will be explained. Figure 26 As shown, the calibration method includes a pre-calibration step S3 and a calibration step S4.

[0136] Pre-calibration process S3

[0137] First, the first robot coordinate acquisition step S31 is performed. In the first robot coordinate acquisition step S31, the hand 29 is used to place the identifier 6 at the first position P1 of the working surface 10, and the position of the robotic arm 22 in the robot coordinate system when the identifier 6 is placed at the first position P1 is obtained as the "first robot coordinate Pr1".

[0138] In this step, firstly, as the first step, the marker 6 is placed at any position on the work surface 10. The placement of the marker 6 is, for example, performed by an operator. Next, as the second step, the control device 5 drives the robot 2 to insert its hand 29 into the marker 6, positioning the marker 6 relative to the hand 29. The position of the marker 6 in the positioned state is then set as a first position P1. Thus, the marker 6 is positioned at the first position P1 by the hand 29. It should be noted that this step is performed by inching. Furthermore, the marker 6 can also move when the hand 29 is inserted, so high precision cannot be achieved in this step. Next, as the third step, the control device 5 detects the position of the robotic arm 22 in the robot coordinate system when the marker 6 is positioned at the first position P1, i.e., when the hand 29 is inserted into the marker 6, and sets this as a first robot coordinate Pr1.

[0139] After the above processing, step S31 of obtaining the coordinates of the first robot ends.

[0140] Next, in step S32, the robot camera 8 is used to capture the identifier 6 located at the first position P1. The position of the identifier 6 in the image coordinate system is obtained based on the obtained first image G1 as the "first image coordinate Pp1".

[0141] In this step, firstly, as the fourth step, the control device 5 drives the robot 2 so that the marker 6 is within the field of view R of the robot camera 8. At this time, the robot camera 8 is set to a pre-set shooting posture (facing directly downwards). In this embodiment, in particular, the marker 6 is positioned at the center of the field of view R. Next, as the fifth step, the control device 5 uses the robot camera 8 to photograph the marker 6 located at the first position P1, obtaining... Figure 27 The first image G1 is shown. Next, as the sixth step, the control device 5 uses a predetermined image processing technique to identify the identifier 6 in the first image G1 and obtain the position of the identifier 6 in the image coordinate system, i.e., the first image coordinates Pp1.

[0142] After the above processing, step S32 of obtaining the first image coordinates ends.

[0143] It should be noted that all images of the marker 6 captured using the robot camera 8 in this calibration method are taken in this shooting posture, and the height of the robot camera 8 (the separation distance from the working surface 10) is also kept at the same height. Therefore, each image G can be acquired under the same conditions.

[0144] Next, the second image coordinate acquisition step S33 is performed. In the second image coordinate acquisition step S33, the robotic arm 22 is positioned at the second robot coordinate Pr2, which is separated from the first robot coordinate Pr1. The robot camera 8 is used to capture the identifier 6. Based on the obtained second image G2, the position of the identifier 6 in the image coordinate system is obtained as the "second image coordinate Pp2".

[0145] In this step, firstly, as the seventh step, the control device 5 determines the second robot coordinate Pr2. (As follows...) Figure 28 As shown, in this embodiment, the second robot coordinate Pr2 is set with two points. The first second robot coordinate Pr21 is separated from the first robot coordinate Pr1 along the X-axis by +10mm in the robot coordinate system. The second second robot coordinate Pr22 is separated from the second robot coordinate Pr21 along the Y-axis in the robot coordinate system by +10mm. That is, the second robot coordinate Pr22 is separated from the first robot coordinate Pr1 along the X-axis by +10mm and along the Y-axis by +10mm in the robot coordinate system. The number and arrangement of the second robot coordinates Pr2 are not particularly limited; for example, a structure using only the second robot coordinates Pr22 may be used.

[0146] Next, as the eighth step, the control device 5 drives the robot 2, positioning the robotic arm 22 at the second robot coordinate Pr21. Next, as the ninth step, the control device 5 uses the robot camera 8 to capture an image of the marker 6 located at the first position P1, obtaining one of the second images G2. Figure 29 The second image G21 is shown. Then, as the tenth step, the control device 5 uses a predetermined image processing technique to identify the identifier 6 in the second image G21 and obtain the position of the identifier 6 in the image coordinate system, i.e., the second image coordinates Pp21.

[0147] Next, as the eleventh step, drive robot 2 so that robotic arm 22 is positioned at the second robot coordinate Pr22. Next, as the twelfth step, use robot camera 8 to capture an image of marker 6 located at the first position P1, obtaining one of the second images G2. Figure 30 The second image G22 is shown. Then, as the thirteenth step, the control device 5 uses a predetermined image processing technique to identify the identifier 6 in the second image G22 and obtain the position of the identifier 6 in the image coordinate system, i.e., the second image coordinates Pp22.

[0148] After the above processing, step S33 of obtaining the second image coordinates ends.

[0149] Next, a pre-calibration step S34 is performed. In this step, based on the first robot coordinates Pr1, the second robot coordinates Pr21 and Pr22, the first image coordinates Pp1, and the second image coordinates Pp21 and Pp22 obtained in steps S31 to S33, the robot coordinate system and the image coordinate system are pre-calibrated. It should be noted that the pre-calibration method is the same as that described in the first embodiment.

[0150] Calibration process S4

[0151] In the calibration process S4, firstly, the third robot coordinate setting step S41 is performed, in which multiple third robot coordinates Pr3 are set.

[0152] In this step, as the fourteenth step, the control device 5 uses the result of the pre-calibration process S3 (hereinafter also referred to as the "pre-calibration result") to set nine third robot coordinates Pr3 in the robot coordinate system. These nine third robot coordinates Pr3 represent the shooting positions of the robot camera 8 and are set such that the marker 6 is located within the field of view R of the robot camera 8. In this embodiment, as... Figure 31 As shown, the nine third robot coordinates Pr3 are arranged in a 3×3 matrix, and are configured such that the markers 6 are evenly distributed across the entire field of view R of the robot camera 8. For ease of explanation, the nine third robot coordinates Pr3 will sometimes be further divided into third robot coordinates Pr31 to Pr39. Additionally, in... Figure 32 The diagram shows an example of a third image G3 acquired at each of the third robot coordinates Pr31 to Pr39. It should be noted that the number of third robot coordinates Pr3 is not particularly limited if there are two or more. Furthermore, the configuration of the third robot coordinates Pr3 is not particularly limited.

[0153] After the above processing, the third robot coordinate setting step S41 ends.

[0154] Next, the third image coordinate acquisition step S42 is performed. In the third image coordinate acquisition step S42, the robotic arm 22 is moved sequentially to 9 third robot coordinates Pr3, and the robot camera 8 is used to take pictures of the identifier 6 each time. The position of the identifier 6 in the image coordinate system is obtained based on the obtained third image G3 as the "third image coordinate Pp3".

[0155] In this step, firstly, as the fifteenth step, the control device 5 drives the robot 2, positioning the robotic arm 22 at the third robot coordinate Pr31. Next, as the sixteenth step, the robot camera 8 captures an image of the marker 6 located at the first position P1, obtaining... Figure 33 The third image G31 is shown. Then, as the seventeenth step, the control device 5 uses a predetermined image processing technique to identify the identifier 6 in the third image G31 and obtain the position of the identifier 6 in the image coordinate system, i.e., the third image coordinate Pp31. Through the above processing, the third image coordinate Pp31 corresponding to the third robot coordinate Pr31 is obtained.

[0156] Next, as the eighteenth step, the control device 5 repeatedly performs the same operation as steps fifteen to seventeen on the third robot coordinates Pr32 to Pr39, and sequentially acquires the third image coordinates Pp32 corresponding to the third robot coordinate Pr32, Pp33 corresponding to the third robot coordinate Pr33, Pp34 corresponding to the third robot coordinate Pr34, Pp35 corresponding to the third robot coordinate Pr35, Pp36 corresponding to the third robot coordinate Pr36, Pp37 corresponding to the third robot coordinate Pr37, Pp38 corresponding to the third robot coordinate Pr38, and Pp39 corresponding to the third robot coordinate Pr39.

[0157] After the above processing, step S42, which involves obtaining the coordinates of the third image, is completed.

[0158] Next, calibration step S43 is performed. In calibration step S43, the robot coordinate system and the image coordinate system are calibrated based on nine third robot coordinates Pr31 to Pr39 and nine third image coordinates Pp31 to Pp39. It should be noted that the calibration method is the same as that described in the first embodiment.

[0159] The calibration method for the image coordinate system and the robot coordinate system has been explained above. This calibration method eliminates the need for finishing work required in existing technologies, thus preventing operator-induced deviations. Therefore, it effectively suppresses the reduction in calibration accuracy and deviations. Furthermore, calibration can be performed without the use of force sensors, simplifying the device structure. Additionally, since there is no direct contact between the hand 29 and the work surface 10 as in finishing work, it effectively suppresses impacts and other damage to the work surface 10.

[0160] As described above, the robot system 1 of this embodiment includes: a robot 2 having a robotic arm 22, the robotic arm 22 having a hand 29; a mark 6 that is self-aligned relative to the hand 29; a robot camera 8 as a shooting unit, disposed on the robotic arm 22, shooting the mark 6 on the working surface 10; and a control device 5 as a control unit that performs calibration of the robot coordinate system set in the robot 2 and the image coordinate system set in the robot camera 8. Additionally, the control device 5 acquires the position of the robotic arm 22 in the robot coordinate system when the marker 6 is positioned at the first position on the work surface 10 using the hand 29, as the first robot coordinate Pr1. It then uses the robot camera 8 to capture an image of the marker 6 positioned at the first position P1. Based on the obtained first image G1, it acquires the position of the marker 6 in the image coordinate system as the first image coordinate Pp1. Next, it positions the robotic arm 22 at a second robot coordinate Pr2, separated from the first robot coordinate Pr1. It then uses the robot camera 8 to capture an image of the marker 6 positioned at the first position P1. Based on the obtained second image G2, it acquires the position of the marker 6 in the image coordinate system as the second image coordinate Pp2. Finally, it uses the first robot coordinate Pr1, the second robot coordinate Pr2, and the first... Image coordinates Pp1 and second image coordinates Pp2 are used to pre-calibrate the robot coordinate system and the image coordinate system. Based on the pre-calibration results, multiple third robot coordinates Pr3 are set to ensure that the marker 6 is within the field of view of the robot camera 8. These multiple third robot coordinates Pr3 represent the positions of the robotic arm 22 in the robot coordinate system. The robotic arm 22 is positioned sequentially at the multiple third robot coordinates Pr3, and the robot camera 8 captures an image of the marker 6 positioned at the first position P1 each time. The position of the marker 6 in the image coordinate system is obtained based on the obtained third image G3 as the third image coordinates Pp3. Based on the multiple third robot coordinates Pr3 and the multiple third image coordinates Pp3, the robot coordinate system and the image coordinate system are calibrated. With this structure, the fine processing work required by existing technologies is not needed, thus avoiding deviations originating from the operator. Therefore, it is possible to effectively suppress the reduction in calibration accuracy and deviations.

[0161] Furthermore, as mentioned above, the calibration method of this embodiment is a calibration method for calibrating the robot coordinate system and the image coordinate system in the robot system 1. The robot system 1 includes: a robot 2, which has a robotic arm 22, the robotic arm 22 having a hand 29; a mark 6, which is self-aligned relative to the hand 29; and a robot camera 8, which serves as a shooting unit, is disposed on the robotic arm 22 and shoots the mark 6 on the working surface 10. The robot coordinate system is set in the robot 2, and the image coordinate system is set in the robot camera 8. The calibration method includes a pre-calibration step S3 and a calibration step S4. Furthermore, in the pre-calibration process S3, the position of the robotic arm 22 in the robot coordinate system when the marker 6 is positioned at the first position on the work surface 10 using the hand 29 is obtained as the first robot coordinate Pr1. The marker 6 positioned at the first position P1 is photographed using the robot camera 8. Based on the obtained first image G1, the position of the marker 6 in the image coordinate system is obtained as the first image coordinate Pp1. The robotic arm 22 is positioned at the second robot coordinate Pr2, which is separated from the first robot coordinate Pr1. The marker 6 positioned at the first position P1 is photographed using the robot camera 8. Based on the obtained second image G2, the position of the marker 6 in the image coordinate system is obtained as the second image coordinate Pp2. Based on the first robot coordinate Pr1, the second robot coordinate Pr2, the first image coordinate Pp1, and the second image coordinate Pp2, the robot coordinate system and the image coordinate system are pre-calibrated. Furthermore, in calibration step S4, based on the pre-calibration results, multiple third robot coordinates Pr3 are set to ensure that the marker 6 is within the field of view of the robot camera 8. These multiple third robot coordinates Pr3 represent the positions of the robotic arm 22 in the robot coordinate system. The robotic arm 22 is sequentially positioned within these multiple third robot coordinates Pr3, and each time the robot camera 8 captures an image of the marker 6 positioned at the first position P1. Based on the obtained third image G3, the position of the marker 6 in the image coordinate system is obtained as the third image coordinate Pp3. Based on the multiple third robot coordinates Pr3 and the multiple third image coordinates Pp3, calibration is performed between the robot coordinate system and the image coordinate system. This method eliminates the need for the fine-machining operations required in existing technologies, thus preventing operator-induced deviations. Therefore, it effectively suppresses the reduction in calibration accuracy and deviations.

[0162] This fourth implementation method can achieve the same effect as the first implementation method described above.

[0163] The robot system, marking, and calibration method of the present invention have been described above based on the illustrated embodiments. However, the present invention is not limited thereto, and the structure of each part can be replaced with any structure or any process having the same function. In addition, other arbitrary structures or arbitrary processes can be added to the present invention.

Claims

1. A robot system, characterized in that, have: The robot has a robotic arm, which has a hand; The mark can be held using the hand and can be self-aligned relative to the hand; The camera unit, fixed at a position opposite to the work surface, photographs the markings on the work surface; and The control unit calibrates the robot coordinate system and the image coordinate system, wherein the robot coordinate system is set at the robot and the image coordinate system is set at the imaging unit. The control unit obtains the position of the robotic arm in the robot coordinate system when the hand places the marker in a first position on the work surface, as the first robot coordinate. The control unit uses the imaging unit to capture an image of the sign positioned at the first location, and obtains the position of the sign in the image coordinate system based on the obtained first image as the first image coordinates. After the control unit holds the marker using the hand, it positions the robotic arm at a second robot coordinate system separated from the first robot coordinate system, places the marker at a second position on the work surface, and captures an image of the marker at the second position using the imaging unit. Based on the obtained second image, the position of the marker in the image coordinate system is obtained as the second image coordinates. The control unit performs a pre-calibration of the robot coordinate system and the image coordinate system based on the first robot coordinates, the second robot coordinates, the first image coordinates, and the second image coordinates. Based on the image coordinate system, the control unit sets multiple third positions, which are located within the field of view of the imaging unit on the working surface. The control unit drives the robot based on the pre-calibrated results, sequentially placing the marker held by the hand into multiple third positions. Each time, the control unit acquires the position of the robotic arm in the robot coordinate system when the marker is placed in the third position as the third robot coordinate. The control unit then captures an image of the marker, and based on the resulting third image, obtains the position of the marker in the image coordinate system as the third image coordinate. The control unit calibrates the robot coordinate system and the image coordinate system based on multiple third robot coordinates and multiple third image coordinates.

2. A robot system, characterized in that, have: The robot has a robotic arm, which has a hand; The markings are capable of self-alignment relative to the hand; A camera unit, configured on the robotic arm, is used to photograph the markings on the work surface; and The control unit calibrates the robot coordinate system and the image coordinate system, wherein the robot coordinate system is set at the robot and the image coordinate system is set at the imaging unit. The control unit acquires the position of the robotic arm in the robot coordinate system when the hand is used to position the marker at a first position on the work surface, as the first robot coordinate. The control unit uses the imaging unit to capture an image of the sign positioned at the first location, and obtains the position of the sign in the image coordinate system based on the obtained first image as the first image coordinates. The control unit positions the robotic arm at a second robot coordinate system, separate from the first robot coordinate system. The imaging unit captures an image of the marker positioned at the first location. Based on the obtained second image, the position of the marker in the image coordinate system is obtained as the second image coordinates. The control unit performs a pre-calibration of the robot coordinate system and the image coordinate system based on the first robot coordinates, the second robot coordinates, the first image coordinates, and the second image coordinates. Based on the pre-calibration results, the control unit sets multiple third robot coordinates to ensure that the identifier is within the field of view of the imaging unit. These multiple third robot coordinates represent the positions of the robotic arm in the robot coordinate system. The control unit positions the robotic arm sequentially at multiple third robot coordinates, and each time uses the imaging unit to capture an image of the marker positioned at the first location. Based on the obtained third image, the position of the marker in the image coordinate system is obtained as the third image coordinates. The control unit calibrates the robot coordinate system and the image coordinate system based on multiple third robot coordinates and multiple third image coordinates.

3. The robot system according to claim 1, characterized in that, The mark has a cylindrical base, which, when positioned on the work surface, extends in a direction orthogonal to the work surface and has a recess for inserting the hand. The mark is positioned relative to the hand by inserting the hand into the recess.

4. The robot system according to claim 3, characterized in that, The mark has a guide portion that guides the hand toward the recess.

5. The robot system according to claim 3, characterized in that, The recess has a bottom. The hand adheres to and holds the bottom surface of the recess.

6. The robot system according to claim 5, characterized in that, The label has a sealing part located between the bottom surface and the hand, which airtightly seals the bottom surface and the hand.

7. The robot system according to claim 1, characterized in that, The mark has a base, which extends in a direction orthogonal to the working surface when disposed on the working surface. The hand has a pair of claws that grip the base from both sides and hold the mark. Each of the claw portions is provided with an engaging portion, which engages with the base portion. With the mark held in place by the hand, the mark is positioned relative to the hand by engaging with each of the engaging portions via the base.

8. The robot system according to claim 1, characterized in that, The mark has a base with a recess on its outer peripheral surface, and when disposed on the working surface, the base extends in a direction orthogonal to the working surface. The hand has a protrusion that inserts into the recess. By inserting the protrusion into the recess, the mark is held by the hand, thereby positioning the mark relative to the hand.

9. The robot system according to claim 3, characterized in that, The mark has an annular flange that protrudes radially from the outer peripheral surface of the base.

10. An identifier, characterized in that, The markings are used for calibrating the robot coordinate system and the image coordinate system. The robot coordinate system is set on the robot, which has a robotic arm with a hand. The image coordinate system is set on the imaging unit, which captures images of the work surface. The mark has a base and an annular flange. In the state configured on the work surface, The base extends in a direction orthogonal to the working surface and can be held by the hand. The flange protrudes outward from the base when viewed from above on the working surface.

11. A calibration method, characterized in that, The calibration method described herein is used in a robot system to calibrate the robot coordinate system against the image coordinate system. The robot system has the following features: The robot has a robotic arm, which has a hand; The mark can be held using the hand and can be self-aligned relative to the hand; and The camera unit is fixed in a position opposite to the work surface to photograph the markings on the work surface. The robot coordinate system is set at the robot, and the image coordinate system is set at the imaging unit. In the calibration method, The position of the robotic arm in the robot coordinate system when the hand positions the marker at a first position on the work surface is obtained as the first robot coordinate. The camera unit captures an image of the marker positioned at the first location. Based on the obtained first image, the position of the marker in the image coordinate system is obtained as the first image coordinates. After holding the marker with the hand, the robotic arm is positioned at a second robot coordinate system, separated from the first robot coordinate system. The marker is then positioned at a second location on the work surface. The imaging unit captures an image of the marker positioned at the second location. Based on the obtained second image, the position of the marker in the image coordinate system is obtained as the second image coordinates. Based on the first robot coordinates, the second robot coordinates, the first image coordinates, and the second image coordinates, a pre-calibration of the robot coordinate system and the image coordinate system is performed. Based on the image coordinate system, multiple third positions are defined, and these multiple third positions are located within the field of view of the shooting unit on the working surface. Based on the pre-calibrated results, the robot is driven to sequentially position the marker, which is held by the hand, at multiple third positions. Each time, the position of the robotic arm in the robot coordinate system when the marker is positioned at the third position is obtained as the third robot coordinate. The robot also captures an image of the marker using the imaging unit, and the position of the marker in the image coordinate system is obtained as the third image coordinate based on the resulting third image. Based on multiple third robot coordinates and multiple third image coordinates, the robot coordinate system and the image coordinate system are calibrated.

12. A calibration method, characterized in that, The calibration method described herein is used in a robot system to calibrate the robot coordinate system against the image coordinate system. The robot system has the following features: The robot has a robotic arm, which has a hand; The markings are capable of self-alignment relative to the hand; and The camera unit, mounted on the robotic arm, photographs the markings on the work surface. The robot coordinate system is set at the robot, and the image coordinate system is set at the imaging unit. In the calibration method, The position of the robotic arm in the robot coordinate system when the hand is used to position the marker at a first position on the work surface is obtained as the first robot coordinate. The camera unit captures an image of the marker positioned at the first location. Based on the obtained first image, the position of the marker in the image coordinate system is obtained as the first image coordinates. The robotic arm is positioned at a second robot coordinate system, separate from the first robot coordinate system. The imaging unit captures an image of the marker positioned at the first location. Based on the obtained second image, the position of the marker in the image coordinate system is obtained as the second image coordinates. Based on the first robot coordinates, the second robot coordinates, the first image coordinates, and the second image coordinates, a pre-calibration of the robot coordinate system and the image coordinate system is performed. Based on the pre-calibration results, multiple third robot coordinates are set in a manner that ensures the marker is within the field of view of the imaging unit. These multiple third robot coordinates represent the positions of the robotic arm in the robot coordinate system. The robotic arm is positioned sequentially at multiple third robot coordinates, and each time the imaging unit captures an image of the marker located at the first position. Based on the obtained third image, the position of the marker in the image coordinate system is obtained as the third image coordinate. Based on multiple third robot coordinates and multiple third image coordinates, the robot coordinate system and the image coordinate system are calibrated.

Images