JP2011128114A - Method, apparatus for measuring tool dimension and robot having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure the dimensions of a tool mounted on a tool mount portion of a robot. <P>SOLUTION: A method is for measuring a tool reference point T, relative to a tool mount portion 10g of a robot 10, and repeatedly implements such an operation of the robot 10 that the tool mount portion rotates around an predetermined rotational center line passing through any position relative to the tool mount portion 10g, under such a state that a camera 14 photographs the actual tool reference point T. Each time the tool mount portion 10g is rotated, a traveling amount on a camera photographing image of the actual tool reference point T moved by the rotation. Moreover, each time the rotation of the tool mount portion 10g is completed, any position and/or predetermined rotational center line is changed. As a result of these, any position at which the traveling amount on the camera photographic image of the actual tool reference point T moved by the rotation of the tool mount portion 10g becoming substantially zero is identified, and the identified predetermined position is taken as a tool reference point T relative to the tool mount portion 10g. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tool dimension measuring method for measuring the position of a tool reference point with respect to a tool mounting portion, a device therefor, and a robot including the device, which are registered in a robot control device including a tool mounting portion for mounting a tool.

  2. Description of the Related Art Conventionally, a robot that uses a tool such as a welding gun or a spray gun to attach to a tool attachment portion (for example, a tool attachment surface that comes into contact with a reference end surface of the tool) and performs work on a workpiece has been used. When work is performed using such a tool, the dimension value of the tool is registered in the control device of the robot.

  For example, as a tool dimension value, a reference point of the tool with respect to the tool mounting surface, for example, a tip point of a welding gun is registered in the control device of the robot.

  Specifically, for example, the coordinate value of the tip point of the tool in the coordinate system defined in advance on the tool mounting surface is registered in the control device of the robot. Based on this coordinate value, the robot accurately aligns the tip of the tool with respect to the workpiece.

  Of course, in order to accurately align the tip of the tool, it is assumed that the registered tool dimension value is correct (the error from the actual tool dimension value is zero). Otherwise, as shown in FIG. 12, for example, even if the robot moves so that the tip point of the tool recognized based on the registered dimension value of the tool moves in a straight line, the actual tip of the tool The locus of a point may not be a straight line.

  As a countermeasure, several methods for measuring a tool dimension value that can obtain a correct tool dimension value are known.

  For example, the measurement method of the tool dimension value described in Patent Document 1 uses a camera, and measures the dimension value of the tool based on the position of the tool tip point on the captured image of the camera.

  Specifically, first, a plurality of initial postures of the tool mounting surface are prepared (defined) such that the tool tip point is reflected in a captured image of the camera. For each initial posture, a parallel movement amount of the tool mounting surface necessary for the tool tip point shown in the photographed image to move to a predetermined location (for example, the image center) of the photographed image is calculated. Then, for each initial posture, the robot is operated based on the calculated parallel movement amount to translate the tool attachment surface, and the position of the tool attachment surface after the parallel movement is acquired. As a result, a plurality of position and orientation data with different tool attachment surfaces, in which the tool tip point is reflected at a predetermined position of the captured image, can be obtained. Based on the plurality of different position and orientation data, and since the tip point of the tool is not moved with respect to the tool mounting surface, the position of the tip point of the tool with respect to the tool mounting surface is calculated.

  In principle, this method is the same as the three-point touch-up or six-point touch-up method in which the tool tip point is brought into contact with the tip of the fixing pin to calculate the position of the tool tip point with respect to the tool mounting surface. However, the method described in Patent Document 1 is advantageous in that the tool tip point does not receive physical contact.

JP-A-2005-300230

  However, the method described in Patent Document 1 calculates a control amount of the robot (a parallel movement amount of the tool mounting surface) such that the tool tip point moves to a predetermined position of the captured image on the captured image of the camera. The viewing direction of the camera with respect to the robot needs to be specified. Therefore, it is necessary to specify the viewing direction of the camera every time the installation position of the camera changes.

  In order to cope with this, it is conceivable to fix the camera at a fixed position with respect to the robot in a state in which the viewing direction of the camera is fixed. However, in this case, in order to ensure the accuracy of the tool dimension measurement, it must be confirmed before measuring the tool dimension value that the camera's line-of-sight direction is maintained in a fixed state.

  Therefore, the present invention does not specify the line-of-sight direction of the camera with respect to the robot, and is based on the photographed image of the camera and is registered in the robot control device, specifically, the tool dimension value, specifically the tool mounting portion with respect to the tool mounting portion. The problem is to measure the position of the reference point.

In order to solve the above-mentioned problem, the invention according to claim 1 of the present application is
A tool dimension measuring method for measuring a position of a reference point of a tool with respect to a tool mounting portion, which is registered in a robot control device having a tool mounting portion for mounting a tool,
In a state where the camera has photographed an actual tool reference point, a robot operation is repeatedly executed such that the tool attachment portion rotates about an arbitrary rotation center line passing through an arbitrary position with respect to the tool attachment portion. Process,
A second step of measuring the amount of movement of the actual tool reference point moved by the rotation on the captured image of the camera each time the tool mounting portion rotates;
By repeatedly executing the third step of changing the arbitrary position and / or the arbitrary rotation center line every time the rotation of the tool attachment portion is completed,
Specify an arbitrary position where the movement amount on the camera image of the actual tool reference point that moves due to the rotation of the tool mounting part becomes substantially zero,
The specified arbitrary position is set as the position of the tool reference point with respect to the tool mounting portion.

The invention according to claim 2
A tool dimension measuring method for measuring a position of a reference point of a tool with respect to a tool mounting portion, which is registered in a robot control device having a tool mounting portion for mounting a tool,
A first setting for rotating a predetermined angle about a rotation center line extending in a predetermined direction passing through the position with respect to each of at least one position having a predetermined positional relationship with respect to the setting position and a predetermined setting position with respect to the tool mounting portion And the process of
A second step of measuring an amount of movement of the actual tool reference point moved by execution of the first step on the camera-captured image for each of the set position and the at least one position;
A third step in which the position with the smallest amount of movement measured in the second step is set as a new set position;
Changing the predetermined positional relationship so that the direction to the set position is changed and / or the distance to the set direction is gradually reduced;
It is repeatedly performed until the position where the movement amount measured in the second step is substantially zero is specified, and the specified position is set as the position of the tool reference point with respect to the tool mounting portion.

Furthermore, the invention described in claim 3
A tool dimension measuring method for measuring a position of a reference point of a tool with respect to a tool mounting portion, which is registered in a robot control device having a tool mounting portion for mounting a tool,
A first step of rotating the tool mounting portion by a predetermined angle around a first rotation center line passing through the position of the tool reference point registered in the control device;
A second step of measuring a first movement amount on the camera-captured image of the actual tool reference point moved by the execution of the first step;
Centered on a second rotation center line parallel to the first rotation center line passing through a position set in advance in a preset setting direction from the position of the tool reference point registered in the control device As a third step of rotating the tool mounting portion by the predetermined angle;
A fourth step of measuring a second movement amount on the camera-captured image of the actual tool reference point moved by the execution of the third step;
Tool attachment centered on a third rotation center line parallel to the first rotation center line passing through a position away from the set reference distance in the opposite direction of the setting direction from the position of the tool reference point registered in the control device A fifth step of rotating the portion by the predetermined angle;
A sixth step of measuring a third movement amount of the actual tool reference point moved by the execution of the fifth step on the captured image of the camera;
When the second movement amount is the smallest among the first to third movement amounts, the position of the tool reference point registered in the control device is changed to a position away from the set distance in the setting direction,
When the third movement amount is the smallest among the first to third movement amounts, the position of the tool reference point registered in the control device is changed to a position away from the set distance in the direction opposite to the set direction. 7 steps,
And repeatedly executing the eighth step of changing the setting direction and / or gradually decreasing the setting distance,
When the movement amount measured in any one of the second, fourth, and sixth steps becomes substantially zero, the repeated execution of the first to eighth steps is terminated.

In addition, the invention according to claim 4
Predefine an orthogonal coordinate system having first, second and third axes;
Before the first step is performed for the first time,
A first movement vector on the captured image of the camera of the actual tool reference point, generated by translating the tool mounting portion in the first axial direction;
A second movement vector on the photographed image of the camera of the actual tool reference point generated by translating the tool mounting portion in the second axial direction;
An image taken by the camera of the actual tool reference point generated by rotating the tool mounting portion around the rotation center line parallel to the third axis passing through the position of the tool reference point registered in the control device A third movement vector above,
An image taken by the camera of the actual tool reference point generated by rotating the tool mounting portion around the rotation center line parallel to the first axis through the position of the tool reference point registered in the control device A fourth motion vector above,
A fifth movement vector on the captured image of the camera of the actual tool reference point, generated by translating the tool mounting portion in the second axial direction;
A sixth movement vector on the captured image of the camera of the actual tool reference point, generated by translating the tool mounting portion in the third axial direction;
A seventh movement vector on the captured image of the camera of the actual tool reference point, which is generated by translating the tool mounting portion in the first axial direction;
An image taken by the camera of the actual tool reference point generated by rotating the tool mounting portion around the rotation center line parallel to the second axis through the position of the tool reference point registered in the control device An eighth movement vector above,
Based on the ninth movement vector on the captured image of the camera of the actual tool reference point generated by translating the tool mounting portion in the third axial direction,
Find the error between the tool reference point registered in the controller and the actual tool reference point.
Based on the obtained error, the position of the tool reference point registered in the control device is corrected.

In addition, the invention according to claim 5
A tool size measuring device for measuring the position of a reference point of a tool with respect to the tool mounting portion, which is registered in a robot control device having a tool mounting portion for mounting a tool,
A camera that is placed around the robot and captures the actual tool reference point;
Measuring means for measuring the position of the tool reference point with respect to the tool mounting portion via the camera and the control device;
Measuring means
Causing the control device to repeatedly execute the operation of the robot such that the tool attachment portion rotates around an arbitrary rotation center line passing through an arbitrary position with respect to the tool attachment portion;
Measure the amount of movement of the actual tool reference point moved by the rotation on the captured image of the camera each time the tool mounting portion rotates, and
By repeatedly executing the arbitrary position and / or the arbitrary rotation center line every time the rotation of the tool attachment portion is completed,
Specify an arbitrary position where the movement amount on the camera image of the actual tool reference point that moves due to the rotation of the tool mounting part becomes substantially zero,
The specified arbitrary position is registered in the control device as the position of the tool reference point with respect to the tool mounting portion.

In addition, the invention according to claim 6
A robot having a tool mounting portion for attaching a tool and a control device, the position of the reference point of the tool with respect to the tool mounting portion being registered in the control device;
The above-described tool dimension measuring device is provided.

  According to the present invention, when the tool mounting portion is rotated around an arbitrary rotation center line passing through an arbitrary position, the tool reference point does not move on the captured image of the camera (the movement amount is If zero), the position of the tool reference point relative to the tool mount is measured (specified) based on the fact that the arbitrary position matches the actual tool reference point position. In this way, since the amount of movement of the reference point of the tool on the captured image is used, the dimension value of the tool, specifically the position of the reference point of the tool with respect to the tool mounting portion, without specifying the direction of the line of sight of the camera with respect to the robot Can be measured.

1 is a diagram schematically showing a system for measuring a dimension of a tool according to a first embodiment of the present invention. FIG. It is a figure for demonstrating a tool dimension value. It is a figure for demonstrating notionally the tool dimension value measuring method which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating the tool dimension value measuring method which concerns on the 1st Embodiment of this invention. It is another figure for demonstrating the tool dimension value measuring method which concerns on the 1st Embodiment of this invention. It is another figure for demonstrating the tool dimension value measuring method which concerns on the 1st Embodiment of this invention. It is a figure of the flowchart which shows the flow of the tool dimension value measuring method which concerns on the 1st Embodiment of this invention. FIG. 8 is a flowchart showing details of step S150 shown in FIG. It is a figure which shows a position change amount determination table. It is a figure which shows a rotation operation determination table. It is a figure for demonstrating the tool dimension value measuring method based on the 2nd Embodiment of this invention using the linear mapping of a vector. It is a figure for demonstrating the problem which arises when there exists an error between an actual tool front-end | tip point and the tool front-end | tip point registered into the control apparatus of the robot.

(First embodiment)
FIG. 1 schematically shows a system for measuring a dimension value of a tool according to an example of the first embodiment of the present invention.

  The robot 10 shown in FIG. 1 is an arm type robot having, for example, six joints 10a to 10f. Further, the robot 10 includes a tool attachment portion (tool attachment surface) 10g to which a tool 12 such as a welding gun or a spray gun can be attached at the free end.

  Furthermore, the robot 10 includes a control device 10h that controls a plurality of motors (not shown) that drive each of the six joints 10a to 10f. The control device 10h controls the six motors so that the tool mounting surface 10g is arranged at various positions and in various postures. Thereby, the tool 12 attached to the tool attachment surface 10g is arrange | positioned with various attitude | positions in various positions.

  The dimension value of the tool 12 is registered in the control device 10h. As shown in FIG. 2, the dimension value of the tool 12 is a value based on the mechanical interface coordinate system ΣM defined on the tool mounting surface 10g, for example.

  Specifically, for example, in the mechanical interface coordinate system ΣM, as shown in FIG. 2, the center of the tool mounting surface 10g and the origin Om coincide with each other, and the normal direction of the tool mounting surface 10g is the Zm-axis direction. Is defined on the tool mounting surface 10g. As the dimension value of the tool 12, the position Pm (coordinate) of the reference point (tip point) T of the tool 12 in the mechanical interface coordinate system ΣM is registered in the control device 10h. The registration is executed by the user via a teach pendant (not shown) of the robot 10, for example.

  The control device 10h of the robot 10 arranges the tip point T of the tool 12 at various positions in space based on the registered position Pm (coordinates) of the tip point T of the tool 12. Naturally, in order to place the tip point T of the tool 12 at a predetermined position (for example, a predetermined position with respect to the workpiece), it is assumed that the position Pm of the tip point T of the tool 12 registered in the control device 10h is correct. It is.

  A camera 14 and a computer 16 are provided as means for setting the position Pm of the tip point T of the tool 12 registered in the control device 10h of the robot 10 to a correct value.

  The camera 14 is a digital camera, for example, and is arranged at a peripheral position of the robot 10 where the tip point T of the tool 12 can be photographed. The camera 14 is controlled by the computer 16 so as to capture the tip point T of the tool 12 and transmit the captured image as data to the computer 16.

  The computer 16 is configured to be able to specify the position of the tip point T of the tool 12 on the captured image acquired from the camera 14. For example, the tip point T of the tool 12 is identified from the photographed image by image analysis, and the position (coordinate) of the tip point T of the tool 12 in the image coordinate system ΣC defined in the photographed image is specified.

  A light source may be provided at the tip T of the tool 12 so that image analysis can be performed more accurately. Thereby, the tip point T of the tool 12 in the captured image can be identified more accurately. Alternatively, a light source may be attached to a predetermined position of the tool 12 and the light source attachment position may be used as the reference point of the tool 12.

  Further, the computer 16 is configured to measure (calculate) the amount of movement of the tip point T of the tool 12 in the image coordinate system ΣC. Specifically, the tip point T of the tool 12 is photographed before and after the tool mounting surface 10g of the robot 10 rotates, and the position (coordinates) in the image coordinate system ΣC of the tip point T of the tool 12 reflected in each photographed image is specified. To do. Then, based on the position (coordinates) of the tip point T of each identified captured image, the amount of movement in the image coordinate system ΣC of the tip point of the tool 12 moved by the rotation of the tool mounting surface 10g is calculated.

  Further, the computer 16 is configured to output a control signal for controlling the robot 10 to the control device 10 h of the robot 10. Furthermore, the computer 16 is configured to be able to change the registration of the position Pm of the tip point T of the tool 12 registered in the control device 10h.

  Hereafter, a method for measuring (specifying) a correct position Pm in the mechanical interface coordinate system ΣM of the tip point T of the tool 12 as a dimension value of the tool 12 using such a camera 14 and the computer 16 will be described.

  First, a method for obtaining the correct position Pm of the tip T of the tool 12 will be conceptually described. In the following description, the actual position of the tip point T of the tool 12 (in the mechanical interface coordinate system ΣM) with respect to the tool mounting surface 10g is referred to as “Pmr” (hereinafter referred to as “actual position Pmr”). The position of the tip point T of the tool 12 (in the mechanical interface coordinate system ΣM) registered in the control device 10h of the robot 10 with respect to the tool mounting surface 10g is defined as “Pms” (hereinafter referred to as “registered position Pms”). Called).

  FIG. 3 shows a photographed image of the camera 14, and the tip point T of the tool 12 is shown in the photographed image. In the captured image shown in FIG. 3A, the tip point T of the tool 12 in a state where the actual position Pmr and the registered position Pms are shifted by the distance Lma is shown. On the other hand, the captured image shown in FIG. 3B shows the tip point T of the tool 12 in a state where the actual position Pmr and the registered position Pms are shifted by a distance Lmb (<Lma).

  When the tool mounting surface 10g rotates about an arbitrary rotation center line passing through the registration position Pms by an angle θ (when the robot 10 moves in this way), the tip point T of the tool 12 is set at the tip point T of the tool 12. And the image coordinate system ΣC (the tool 12 before the movement is indicated by a two-dot chain line). Note that θ ′ shown in FIG. 3 is an angle on the captured image corresponding to the angle θ.

  As shown in FIGS. 3 (A) and 3 (B), the movement amount ΔSc of the tip point T of the tool 12 in the image coordinate system ΣC naturally has a short distance between the actual position Pmr and the registered position Pms. The smaller it is, the smaller it becomes.

  From this, when the tool attachment surface 10g is rotated about an arbitrary rotation center line passing through the registration position Pms, the tip point T of the tool 12 does not move in the image coordinate system ΣC (movement amount ΔSc). If it is zero), it can be said that the registered position Pms and the actual position Pmr match. The present invention is based on this idea.

  A specific method for obtaining the dimension value of the tool 12, that is, the actual position Pmr (the coordinates of the actual position Pmr) in the mechanical interface coordinate system ΣM based on this idea will be described with reference to FIGS.

  FIG. 4A shows an example of a state where the registered position Pms (coordinates (xms, yms, zms)) is deviated from the actual position Pmr (coordinates are unknown). From this state, the coordinates of the actual position Pmr in the mechanical interface coordinate system ΣM are obtained by repeatedly executing the following four processes in order.

(First process)
First, as a first process, as shown in FIG. 4 (B), the computer 16 moves the position (coordinates (xms + Δxms, yms + Δyms) away from the registered position Pms (coordinates (xms, yms, zms)) in the setting direction. , Zms + Δzms)) is set as the temporary registration position Pms1. The setting direction and the setting distance are stored in advance in a storage device of the computer 16 and stored as coordinate change amounts Δxms, Δyms, Δzms. The “temporary registration position” is a position that may be registered later in the control device 10h of the robot 10 as a new registration position.

  Further, as shown in FIG. 4C, a position (coordinates (xms−Δxms, yms−Δyms, zms−) that is a set distance away from the registered position Pms (coordinates (xms, yms, zms)) in the direction opposite to the set direction. Δzms)) is set as the provisional registration position Pms2. In other words, the temporary registration positions Pms1 and Pms2 face each other with the registration position Pms in between and the same distance from the registration position Pms.

(Second process)
Next, as a second process, the degree of matching (coincidence) with the actual position Pmr is evaluated for each of the registration position Pms and the temporary registration positions Pms1 and Pms2. That is, the one closest to the actual position Pmr is selected from the registered positions Pms and temporary registered positions Pms1, Pms2.

  A method for evaluating the degree of matching with the actual position Pmr for each of the registration position Pms and the provisional registration positions Pms1 and Pms2 will be described.

  First, for each of the registration position Pms and the temporary registration positions Pms1 and Pms2, the tool attachment surface 10g is rotated about the rotation center line passing through the positions (coordinates), and the image of the tip point T of the tool 12 moved thereby. The movement amount in the coordinate system ΣC is measured (calculated).

  Specifically, for each of the registration position Pms and the provisional registration positions Pms1, Pms2, the tool mounting surface 10g is rotated at an angle θ about the rotation center line parallel to the Xm axis of the mechanical interface coordinate system ΣM (first Rotation operation) is executed. Then, the movement amount ΔXc in the Xc axis direction and the movement amount ΔYc in the Yc axis direction in the image coordinate system ΣC of the tip point T of the tool 12 moved by the first rotation operation are measured (calculated).

  Similarly, for each of the registration position Pms and the temporary registration positions Pms1 and Pms2, the tool mounting surface 10g is rotated at an angle (−θ) about a rotation center line parallel to the Xm axis (second rotation operation). ), Rotation operation at an angle θ centered on a rotation center line parallel to the Ym axis (third rotation operation), rotation operation at an angle (−θ) centered on a rotation center line parallel to the Ym axis (fourth rotation operation) Rotation operation), rotation operation at an angle θ about a rotation center line parallel to the Zm axis (fifth rotation operation), and rotation at an angle (−θ) about a rotation center line parallel to the Zm axis. The movement amount ΔXc in the Xc-axis direction and the movement amount in the Yc-axis direction in the image coordinate system ΣC of the tip point T of the tool 12 that is moved by the second to sixth rotation operations by performing the operation (sixth rotation operation). ΔYc is measured (calculated).

  For example, in the case of the third rotation operation, as shown in FIG. 5A, the computer 16 sets a rotation center line Cym0 that passes through the registration position Pms and is parallel to the Ym axis of the mechanical interface coordinate system ΣM. Further, as shown in FIG. 5B, a rotation center line Cym1 that passes through the temporary registration position Pms1 and is parallel to the rotation center line Cym0 is set. Further, as shown in FIG. 5C, a rotation center line Cym2 that passes through the temporary registration position Pms2 and is parallel to the rotation center line Cym1 is set.

  Next, as shown in FIGS. 5A to 5C, the computer 16 determines the robot 10 for each of the registration position Pms and the temporary registration positions Pms1 and Pms2 with a predetermined center of rotation center line. The tool mounting surface 10g is controlled to rotate by the angle θ.

From here, the movement amounts Δxc and Δyc of the tip point T of the tool 12 in the image coordinate system ΣC are the rotation center (registered position Pms, temporary registered positions Pms1, Pms2) and the rotation operation (first to sixth). Therefore, it is expressed as a function of the registration position parameter Pms (i) and the rotation operation parameter R (j) as shown in Equation 1 and Equation 2.

  The registration position parameters Pms (i) shown in Expression 1 and Expression 2 correspond to Pms (0) corresponding to the registration position Pms, Pms (1) corresponding to the temporary registration position Pms1, and Pms (2) corresponding to the temporary registration position Pms2. Yes. The rotation operation parameter R (j) includes R (1) as the first rotation operation, R (2) as the second rotation operation, R (3) as the third rotation operation, and R (4) as the fourth rotation operation. The rotation operation, R (5) corresponds to the fifth rotation operation, and R (6) corresponds to the sixth rotation operation.

Subsequently, the computer 16 obtains a variance value of the movement amount of the tip point T of the tool 12 in the image coordinate system ΣC. Specifically, for each of the registration position Pms and the temporary registration positions Pms1 and Pms2, the variance value Vxc (Pms (i)) of the movement amount Δxc (Pms (i), R (j)) in the Xc axis direction of the image coordinate system ΣC. ) Is obtained (Formula 3). Further, a dispersion value Vyc (Pms (i)) of the movement amount Δyc (Pms (i), R (j)) in the Yc axis direction is obtained (Formula 4).

  In Equations 1 and 2, Δxcm (Pms (i)) is an average of the movement amount Δxc (Pms (i), R (j)). Δycm (Pms (i)) is an average of the movement amount Δyc (Pms (i), R (j)).

When the variance values Vxc (Pms (i)) and Vyc (Pms (i)) are obtained, the computer 16 performs the matching evaluation indicating the degree of matching with the actual position Pmr for each of the registered position Pms and the temporary registered positions Pms1 and Pms2. A value M (Pms (i)) is obtained. The matching evaluation value M (Pms (i)) is defined as the sum of the variance values Vxc (Pms (i)) and Vyc (Pms (i)) as shown in Equation 5.

  This matching evaluation value M (Pms (i)) is the variance value Vxc (Pms (Pms (Pms (i))) of the movement amount Δxc (Pms (i), R (j)) in the image coordinate system ΣC of the tip point T of the tool 12 as described above. i)) and the variance value Vyc (Pms (i)) of the movement amount Δyc (Pms (i), R (j)), the smaller this value, the more the position Pms (i) becomes the actual position Pmr. It is close to.

  Therefore, the computer 16 selects the position Pms (i) having the smallest matching evaluation value M (Pms (i)) as the closest to the actual position Pmr.

(Third process)
Subsequently, as a third process, the computer 16 registers the position Pms (i) selected in the second process in the control device 10h of the robot 10 (Pms registered in the control device 10h is Pms (i). )).

(Fourth process)
Subsequently, as a fourth process, the computer 16 changes the setting direction used in setting the temporary registration positions Pms1, Pms2 in the first process and / or gradually decreases the setting distance, that is, the coordinate change amount Δxms. , Δyms, Δzms are gradually decreased.

  For example, in a state where the coordinate change amounts Δyms and Δzms are maintained at zero, Δxms is gradually decreased from the set value (preset value) every time the third process is completed. Next, when the coordinate change amount Δxms becomes zero, Δyms is gradually decreased from the set value every time the third process is completed while Δxms and Δzms are maintained at zero. Subsequently, when the coordinate change output Δyms becomes zero, Δzms is gradually decreased from the set value to zero every time the third process is completed while maintaining Δxms and Δyms at zero.

  Then, the computer 16 sets the first to fourth processes as one cycle, and repeatedly executes the cycle. This is executed until the movement amount Δxc in the Xc axis direction and the movement amount Δyc in the Yc axis direction in the image coordinate system ΣC of the tip point T of the tool 12 become substantially zero (for example, a predetermined value close to zero, 0.1). To do. As a result, the registration position Pms of the tip point T of the tool 12 registered in the control device 10h of the robot 10 approaches the actual position Pmr (error is corrected) every time the cycle is repeatedly executed, and finally, It almost agrees.

  This will be described with reference to FIG. As shown in FIG. 6A, temporary registration positions Pms1, Pms2 are set across the registration position Pms (first process). Among the registered positions Pms and temporary registered positions Pms1, Pms2, the temporary registered position Pms1 closest to the actual position Pmr (the smallest matching evaluation value M) is selected (second process), and the robot 10 is controlled as a new registered position. Registered in the apparatus 10h (third process). Then, at least one value of the coordinate change amounts Δxms, Δyms, Δzms is gradually decreased (fourth process), and one cycle is completed.

  Subsequently, as shown in FIG. 6B, temporary registration positions Pms1 and Pms2 are set across the registration position Pms (originally the temporary registration position Pms1 shown in FIG. 6A). At this time, the distance (that is, error) of the temporary registration positions Pms1, Pms2 from the registration position Pms is shorter than that in FIG. 6A due to the execution of the fourth process. Further, the directions of the temporary registration positions Pms1, Pms2 from the registration position Pms are also changed compared to the case of FIG. 6A by the execution of the fourth process. Of the registered positions Pms and temporary registered positions Pms1, Pms2, the temporary registered position Pms1 that is closest to the actual position Pmr (the smallest matching evaluation value M) is registered in the control device 10h of the robot 10 as a new registered position. Then, at least one value of the coordinate change amounts Δxms, Δyms, Δzms is gradually decreased, and one cycle is completed.

  When such a cycle is repeated, as shown in a comparison between FIG. 6A and FIG. 6D, the registered position Pms approaches the actual position Pmr every time one cycle ends. (The error between the registered position Pms and the actual position Pmr is reduced). In this way, the registered position Pms approaches the actual position Pmr each time the cycle is repeatedly executed, and finally substantially coincides (the error becomes substantially zero). As a result, the correct position (coordinates) of the tip point T of the tool 12 is registered in the control device 10h of the robot 10.

  When the alignment evaluation value M of the registration position Pms is the minimum, it is preferable to greatly reduce at least one of the coordinate change amounts Δxms, Δyms, and Δzms in the fourth process, rather than gradually decreasing it.

  This is because the registration position Pms is closer to the actual position Pmr than the temporary registration positions Pms1 and Pms2 when the matching evaluation value M of the registration position Pms is minimum. Therefore, in order to quickly match the registered position Pms with the actual position Pmr from this state, it is preferable to greatly reduce at least one of the coordinate change amounts Δxms, Δyms, Δzms.

  From here, the flow of the calculation method of the correct position (coordinates) in the mechanical interface coordinate system ΣM of the tip point T of the tool 12 will be described more specifically. That is, a specific operation flow of the computer 16 will be described. The description will be given with reference to the flowcharts of FIGS.

  First, as shown in FIG. 7, the computer 16 resets the parameter k to zero in step S100.

  Next, in step S110, the computer 16 increments the parameter k (increments by 1).

  Subsequently, in step S <b> 120, the computer 16 acquires the registration position Pms of the tip point T of the tool 12 from the control device 10 h of the robot 10.

  In step S130, the computer 16 acquires the position change amount ΔPms (k) from the position change amount determination table shown in FIG. The position change amount determination table is created in advance as data and stored in the storage device of the computer 16. Specifically, as shown in FIG. 9, coordinate change amounts Δxms, Δyms, Δzms corresponding to the position change amount ΔPms (k) are acquired.

  In step S140, the computer 16 sets the registered position Pms acquired in step S120 as a position Pms (0). Also, a position moved from the registered position Pms by the position change amount ΔPms (k) acquired in step S130 is set as a position Pms (1). Further, a position moved by a position change amount (−ΔPms (k)) from the registered position Pms is set as a position Pms (2).

  In step S150, the computer 16 matches the position evaluation values M (Pms (0)), M (Pms (1)), and M (Pms (2)) at the positions Pms (0), Pms (1), and Pms (2). Is calculated. The calculation flow will be described with reference to the flowchart shown in FIG.

  First, as shown in FIG. 8, in step S300, the computer 16 sets the parameter i to (−1).

  Next, in step S310, the computer 16 increments the parameter i.

  Subsequently, in step S320, the computer 16 changes the registration of the position of the tip point T of the tool 12 registered in the control device 10h of the robot 10 to the position Pms (i).

  In step S330, the computer 16 causes the camera 14 to photograph the tip point T of the tool 12, and based on the photographed image, coordinates (xc (0), yc (0)) of the tip point T of the tool 12 in the image coordinate system ΣC. )) Is specified.

  In step S340, the computer 16 resets the parameter j to zero.

  In step S350, the computer 16 increments the parameter j.

  In step S360, the computer 16 controls the robot 10 to rotate the tool mounting surface 10g with the rotation operation R (j) around the position Pms (i) currently registered in the control device 10h. The rotational motion R (j) is determined based on a rotational motion determination table as shown in FIG. 10 that is created in advance as data and stored in the storage device of the computer 16.

  In step S370, the computer 16 causes the camera 14 to photograph the tip point T of the tool 12 after the rotation operation R (j) executed in step S360, and based on the photographed image, an image of the tip point T of the tool 12 is obtained. The coordinates (xc (j), yc (j)) in the coordinate system ΣC are specified.

  In step S380, the computer 16 determines the coordinates (xc (0), yc (0)) of the tool tip point T identified in step S330, that is, before executing the rotation operation R (j) in step S360, and step S370. That is, the tip of the tool 12 moved by the rotation operation R (j) based on the coordinates (xc (j), yc (j)) of the tip point T of the tool 12 after the rotation operation R (j). The movement amounts Δxc (Pms (i), R (j)) and Δyc (Pms (i), R (j)) of the point T in the image coordinate system ΣC are calculated.

  In step S390, the computer 16 controls the robot 10 to return the tool mounting surface 10g to the state before execution of the rotation operation R (j) (return to before execution of step S360).

  In step S400, the computer 16 determines whether or not the parameter j is six. That is, it is determined whether or not the execution of all six rotation operations R (1) to R (6) centered on the position Pms (i) is completed. If the parameter j is 6, the process proceeds to step S410. Otherwise, the process returns to step S350.

  In step S410, the computer 16 calculates an average value Δxcm (Pms (i)) of the movement amount Δxc (Pms (i), R (j)) of the tip point T of the tool 12 in the image coordinate system ΣC.

  In step S420, the computer 16 calculates the average value Δycm (Pms (i)) of the movement amount Δyc (Pms (i), R (j)) of the tip point T of the tool 12 in the image coordinate system ΣC.

  In step S430, the computer 16 uses the average value Δxcm (Pms (i)) calculated in step S410 to move the movement amount Δxc (Pms (i), R (j) of the tip point T of the tool 12 in the image coordinate system ΣC. )) Variance value Vxc (Pms (i)) is calculated (see Equation 3).

  In step S440, the computer 16 uses the average value Δycm (Pms (i)) calculated in step S420 to move the amount Δyc (Pms (i), R (j) of the tip point T of the tool 12 in the image coordinate system ΣC. )) Variance value Vyc (Pms (i)) is calculated (see Equation 4).

  In step S450, the computer 16 calculates a matching evaluation value M (Pms (i)) from the variance value Vxc (Pms (i)) calculated in step S430 and the variance value Vyc (Pms (i) calculated in step S440. Calculate (see Formula 5).

  In step S460, the computer 16 determines whether or not the parameter i is 2. That is, it is determined whether or not a consistency evaluation value has been calculated for each of the positions Pms (0), Pms (1), and Pms (2). If the parameter i is 2, the calculation of the consistency evaluation value is terminated, and the process proceeds to step S160 shown in FIG. Otherwise, the process returns to step S310 and the calculation of the consistency evaluation value is continued.

  Returning to FIG. 7, in step S160, the computer 16 compares the magnitudes of the matching evaluation values M (Pms (0)), M (Pms (1)), and M (Pms (2)) calculated in step S150. When the matching evaluation value M (Pms (1)) is the minimum, the process proceeds to step S170. Otherwise, the process proceeds to step S180.

  In step S170, the computer 16 changes the registration of the position of the tip point T of the tool 12 registered in the control device 10h of the robot 10 to the position Pms (1). Then, the process proceeds to step S200.

  On the other hand, if it is determined in step S160 that the matching evaluation value M (Pms (1)) is not minimum, in step S180, the computer 16 determines whether or not the matching evaluation value M (Pms (2)) is minimum. Determine. When the matching evaluation value M (Pms (2)) is the minimum, the process proceeds to step S190. Otherwise, the process proceeds to step S200.

  In step S190, the computer 16 changes the registration of the position of the tip point T of the tool 12 registered in the control device 10h of the robot 10 to the position Pms (2). Then, the process proceeds to step S200.

  In step S200, it is confirmed whether or not the parameter k is 48, that is, whether or not all the values of the coordinate change amounts Δxms, Δyms, and Δzms on the table shown in FIG. 9 have been used. When the parameter k is 48, the calculation of the correct position of the tip point T of the tool 12 is terminated. Otherwise, the process returns to step S110.

  According to the present embodiment, when the tool mounting surface 10g is rotated about an arbitrary rotation center line passing through an arbitrary position, the reference point T of the tool 12 must move on the captured image of the camera 14. If the amount of movement is zero, the tool 12 (in the mechanical interface coordinate system ΣM) with respect to the tool mounting surface 10g is based on the fact that the arbitrary position matches the position of the actual tool reference point. The position (coordinates) of the tip point T is measured (specified). Thus, since the movement amount (Δxc, Δyc) of the reference point T of the tool 12 on the captured image is used, the dimension value of the tool 12, specifically, without specifying the line-of-sight direction of the camera 14 with respect to the robot 10. The position (coordinates) of the tip point T of the tool 12 with respect to the tool mounting surface 10g can be measured.

(Second Embodiment)
This embodiment is substantially the same as the first embodiment described above, and is an improved form of the first embodiment. In the case of the first embodiment, the longer the distance between the actual position Pmr of the tip point T of the tool 12 and the registered position Pms (the greater the error), the more the actual position Pmr matches the registered position Pms. It takes time (it takes time to calculate the actual position Pmr). The present embodiment addresses this.

  Basically, the present embodiment is similar to the first embodiment after the registered position Pms of the tip point T of the tool 12 registered in the control device 10h of the robot 10 is set to a value substantially close to the actual position Pmr. In addition, the coordinates of the actual position Pmr are obtained. The rest is the same as in the first embodiment. Therefore, a method for setting the registered position Pms of the tip point T of the tool 12 registered in the control device 10h of the robot 10 to a value substantially close to the actual position Pmr will be described below.

  In order to set the registered position Pms of the tip point T of the tool 12 registered in the control device 10h of the robot 10 to a value substantially close to the actual position Pmr, a vector linear mapping is used.

  A method of using a linear mapping of vectors will be conceptually described.

  First, as shown in FIG. 11, consider a virtual plane Pv that includes a registered position Pms perpendicular to the Zm axis of the mechanical interface coordinate system ΣM. Further, the projection position of the actual position Pmr on the virtual plane Pv is assumed to be Pmr ′ (hereinafter referred to as “projection actual position Pmr ′”).

  An image of the tip point T of the tool 12 with U as the movement vector on the virtual plane Pv of the actual projection position Pmr 'when the tool mounting surface 10g is translated by a distance L in the Xm-axis direction of the mechanical interface coordinate system ΣM. Let the movement vector in the coordinate system ΣC be Uc (corresponding to the “first movement vector” recited in the claims).

  In addition, the movement vector on the virtual plane Pv of the projection actual position Pmr ′ when the tool mounting surface 10g is translated by the distance L in the Ym-axis direction is V, and the image coordinate system ΣC of the tip point T of the tool 12 in the image coordinate system ΣC. The movement vector Vc (corresponding to the “second movement vector” recited in the claims).

  Further, W is a movement vector on the virtual plane Pv of the actual projection position Pmr ′ when the tool mounting surface 10g is rotated by an angle α about the rotation center line parallel to the Zm axis through the registered position Pms. The movement vector of the tip point T of the tool 12 in the image coordinate system ΣC is Wc (corresponding to the “third movement vector” described in the claims).

  Furthermore, a vector R having a registered position Pms as a start point and a projection actual position Pmr 'as an end point is defined.

In the mechanical interface coordinate system ΣM, if the error in the Xm-axis direction between the registered position Pms and the actual position Pmr is xme, and the error in the Ym-axis direction is yme, the virtual plane Pv is orthogonal to the Zm axis. The vector R on the virtual plane Pv can be expressed as shown in Equation 6.

Also, as shown in FIG. 11, since the vector U and the vector V are orthogonal, the vector W can be regarded as the sum of the vector U multiplied by g and the vector V multiplied by h, as shown in Equation 7.

Furthermore, if the angle α is close to zero (α≈0), the magnitude of the vector W can be approximated as sin α times the magnitude of the vector R, as shown in Equation 8.

Furthermore, if the angle α is close to zero (α≈0), the vector R and the vector W can be regarded as being orthogonal. That is, the vector W can be regarded as a vector R rotated 90 degrees. Therefore, considering this and Equation 8, the vector W can be regarded as a vector R multiplied by sin α and rotated by 90 degrees (π), and can be expressed as shown in Equation 9.

From Equation 7 and Equation 9, Equation 10 and Equation 11 hold.

  In Equations 10 and 11, the parameters L and α are known (“L” is the amount of movement when the tool mounting surface 10 g is translated in the Xm-axis direction or Ym-axis direction, and “α” is This is the amount of rotation when rotating around the Zm axis). Accordingly, in order to obtain the errors xme and yme between the registered position Pms and the actual position Pmr, the values of the parameters g and h may be obtained.

  In order to obtain the values of the parameters g and h, a linear mapping of vectors is used.

As shown in FIG. 11, the vectors Uc, Vc, and Wc on the photographed image are linear mappings of the vectors U, V, and W on the virtual plane Pv, and thus the relationships of Expressions 12 to 14 are established. The matrix A is a square matrix.

Since the matrix A is a square matrix, the vector Wc can be represented by vectors Uc and Vc as shown in Equation 15.

Here, the Xc component of the vector Wc is Wxc and the Yc component is Wyc. The Xc component of the vector Uc is Uxc and the Yc component is Uyc. Further, the Xc component of the vector Vc is Vxc, and the Yc component is Vyc. Then, Equation 15 can be expressed as shown in Equation 16.

When Formula 16 is transformed, Formula 17 is obtained.

  From Equation 17, the values of the parameters g and h can be obtained. Then, by substituting the values of the obtained parameters g and h into Expressions 10 and 11, errors xme and yme between the registered position Pms and the actual position Pmr in the mechanical interface coordinate system can be obtained.

  The Xc component Uxc and Yc component Uyc of the vector Uc are the Xc axis in the image coordinate system ΣC of the tip point T of the tool 12 when the tool mounting surface 10g is translated by L in the Xm axis direction of the mechanical interface coordinate system ΣM. Direction and the amount of movement in the Yc-axis direction, and can be calculated based on the captured images captured by the camera 14 before and after the parallel movement.

  Similarly, the Xc component Vxc and the Yc component Vyc of the vector Vc are the Xc axis direction and the Yc axis direction in the image coordinate system ΣC of the tip point T of the tool 12 when the tool mounting surface 10g is translated by L in the Ym axis direction. Therefore, it can be calculated based on the captured images captured by the camera 14 before and after the parallel movement.

  Similarly, the Xc component Wxc and the Yc component Wyc of the vector Wc are the Xc axis direction in the image coordinate system ΣC of the tip point T of the tool 12 when the tool mounting surface 10g is rotated about the Zm axis by an angle α, Since it is the amount of movement in the Yc axis direction, it can be calculated based on the captured images captured by the camera 14 before and after the rotation.

  In summary, the translation vector Uc in the image coordinate system ΣC of the tip point T of the tool 12 is generated by translating the tool mounting surface 10g by the distance L in the Xm-axis direction of the mechanical interface coordinate system ΣM. Further, by moving the tool mounting surface 10g in parallel in the Ym-axis direction by the distance L, a movement vector Vc in the image coordinate system ΣC of the tip point T of the tool 12 is generated. Further, the movement vector Wc in the image coordinate system ΣC of the tip point T of the tool 12 is generated by rotating the tool mounting surface 10g by an angle α around the rotation center line parallel to the Zm axis through the registered position Pms. Let Based on these three movement vectors Uc, Vc and Wc, errors xme and yme between the registered position Pms and the actual position Pmr in the mechanical interface coordinate system ΣM are obtained.

  Similarly, by rotating the tool attachment surface 10g by an angle α around the rotation center line parallel to the Xm axis through the registered position Pms, a movement vector (invoice) in the image coordinate system ΣC of the tip point T of the tool 12 (Corresponding to the “fourth movement vector” described in the above). Further, by translating the tool mounting surface 10g by a distance L in the Ym-axis direction, the movement vector (corresponding to the “fifth movement vector” described in the claims) of the tip point T of the tool 12 in the image coordinate system ΣC. ). Further, by moving the tool mounting surface 10g in the Zm-axis direction by a distance L, the movement vector in the image coordinate system ΣC of the tip point T of the tool 12 (corresponding to the “sixth movement vector” recited in the claims) ). Based on these three movement vectors, errors yme and zme between the registered position Pms and the actual position Pmr in the mechanical interface coordinate system ΣM (the errors in the Zm axis direction between the registered position Pms and the actual position Pmr in the mechanical interface coordinate system ΣM) are obtained. .

  Similarly, by moving the tool mounting surface 10g in parallel in the Xm-axis direction by a distance L, a movement vector in the image coordinate system ΣC of the tip point T of the tool 12 (“seventh movement vector” described in the claims) To respond). Further, by rotating the tool mounting surface 10g by an angle α around the rotation center line parallel to the Ym axis through the registered position Pms, the movement vector (in claim) of the tip point T of the tool 12 in the image coordinate system ΣC. Corresponding to the “eighth movement vector” described in the range. Further, by moving the tool mounting surface 10g in the Zm-axis direction by a distance L, the movement vector in the image coordinate system ΣC of the tip point T of the tool 12 (corresponding to the “ninth movement vector” recited in the claims) ). Based on these three movement vectors, errors xme and zme between the registered position Pms and the actual position Pmr in the mechanical interface coordinate system ΣM are obtained.

の行列式Ｄ（数式１８）の絶対値が大きい方を選択する。これは、この行列式Ｄが大きい方が高精度にパラメータｇ，ｈの値を求めることができるからである。

Based on the nine movement vectors of the tip point T of the tool 12 on the photographed image, as described above, two each for the error xme in the Xm-axis direction, the error yme in the Ym-axis direction, and the error zme in the Zm-axis direction. A value is calculated. In this case, the one closer to the true error value is selected from the two values. Specifically, a square matrix on the right side in Equation 17 used to calculate each value.

The one with the larger absolute value of the determinant D (formula 18) is selected. This is because the values of the parameters g and h can be obtained with higher accuracy when the determinant D is larger.

  When one value is determined for each of the error xme in the Xm-axis direction, the error yme in the Ym-axis direction, and the error zme in the Zm-axis direction by selection based on the determinant D, the control of the robot 10 is performed based on the values. The registered position Pms registered in the device 10h is corrected to a value substantially close to the actual position Pmr.

  If the vector linear mapping is used in this way, errors xme, yme, zme between the registered position Pms and the actual position Pmr in the mechanical interface coordinate system ΣM can be obtained. However, the values of the obtained errors xme, yme, and zme are approximate values rather than accurate error values because the angle α is approximated to zero as described above.

  According to the present embodiment, after the registration position Pms of the tip point T of the tool 12 registered in the control device 10h of the robot 10 is set to a value substantially close to the actual position Pmr, the same as in the first embodiment, The dimension value of the tool 12, specifically, the position (coordinates) of the tip point T of the tool 12 with respect to the tool mounting surface 10g is measured (calculated). Therefore, when the distance between the actual position Pmr of the tip point T of the tool 12 and the registered position Pms is long (when the error is large), the time until the registered position Pms matches the actual position Pmr can be shortened. (The specific time of the actual position Pmr is shortened).

  Although the present invention has been described with reference to the above-described embodiment, the present invention is not limited to this.

  For example, in the case of the above-described embodiment, when the alignment evaluation values M of the registration position Pms and the temporary registration positions Pms1 and Pms2 are calculated in the second process, the registration positions Pms and the temporary registration positions Pms1 and Pms2 Six rotation operations with respect to the tool mounting surface 10g as shown in Table 10 are performed. However, according to the present invention, when calculating the alignment evaluation value M, the number of rotation operations performed on the tool mounting surface 10g is not limited to six.

  In order to calculate the alignment evaluation value M with high reliability, it is preferable to execute a plurality of different rotational operations on the tool mounting surface 10g for each of the registration position Pms and the temporary registration positions Pms1 and Pms2 (thereby A large amount of movement amount data on the captured image of the tip point T of the tool 12 necessary for calculating the alignment evaluation value M can be acquired). However, it takes time to measure (specify) the actual position of the tip point T of the tool 12 with respect to the tool mounting surface 10g.

  When it is desired to shorten the time required for specifying the actual position of the tip point T of the tool 12, three rotation operations may be performed on the tool mounting surface 10g for each of the registration position Pms and the temporary registration positions Pms1 and Pms2. . For example, a rotation operation that rotates an angle θ around a rotation center line parallel to the Xm axis of the mechanical interface coordinate system ΣM, a rotation operation that rotates an angle θ around a rotation center line parallel to the Ym axis, and a rotation parallel to the Zm axis Three rotation operations that rotate the angle θ about the rotation center line may be employed. In this regard, in principle, the alignment evaluation value M can be calculated by performing a rotation operation on the tool mounting surface 10g that rotates the angle θ toward one side about one rotation center line. Is possible.

  In the case of the above-described embodiment, in calculating the alignment evaluation value M in the second process, the rotation center line when rotating the tool attachment surface 10g is the registration position Pms, temporary registration as shown in FIG. This is a rotation center line parallel to the Xm axis, Ym axis, and Zm axis of the mechanical interface coordinate system ΣM that passes through each of the positions Pms1 and Pms2. However, the temporary registration position is not limited to two.

  In the present invention, in calculating the alignment evaluation value M, the rotation center line when rotating the tool mounting surface 10g is, in principle, a preset set position with respect to the tool mounting surface 10g (coordinate is a known position). Thus, for example, the above-mentioned registered position Pms) and an arbitrary rotation center line passing through at least one position having a predetermined positional relationship with respect to the set position.

  That is, in a broad sense, the present invention can be said to be as follows. Each of the preset setting position with respect to the tool mounting surface 10g and at least one position having a predetermined positional relationship with respect to the setting position is rotated by a predetermined angle around a rotation center line extending in a predetermined direction passing through the position ( Step A). Further, for each of the set position and the at least one position, the amount of movement of the actual tool reference point moved by the execution of step A on the camera-captured image is measured (step B). Then, the position where the movement amount measured in the process B is the minimum is set as a new setting position (process C), and the predetermined positional relationship is changed so that the direction to the setting position is changed and / or up to the setting direction. Change so that the distance gradually decreases (step D). Then, these steps A to D are repeatedly executed until the position where the movement amount measured in the step B is substantially zero is specified, and the specified position is set as the position of the tool reference point with respect to the tool mounting portion.

  Furthermore, even if the alignment evaluation value M is not calculated, the actual position of the tip point T of the tool 12 with respect to the tool mounting surface 10g can be measured (specified) by the following method.

  For example, the robot 10 in which the tool attachment surface 10g rotates about an arbitrary rotation center line passing through an arbitrary position with respect to the tool attachment surface 10g in a state where the camera 14 has photographed the reference point T of the actual tool 12. These operations are repeatedly executed (step A ′). Further, every time the tool mounting surface 10g rotates, the amount of movement of the actual reference point T of the tool 12 moved by the rotation on the photographed image is measured (step B '). Further, every time the rotation of the tool mounting surface 10g is completed, an arbitrary position and / or an arbitrary rotation center line is changed (step C '). By these steps A ′ to C ′, an arbitrary position where the movement amount of the actual reference point T of the tool 12 moving by the rotation of the tool mounting surface 10g on the photographed image becomes substantially zero is specified, and the specified arbitrary The position is the position of the reference point T of the tool 12 with respect to the tool mounting surface 10g.

  This is the most basic method for measuring (specifying) the actual position of the tip T of the tool 12 with respect to the tool mounting surface 10g according to the present invention. However, in the case of an arbitrary rotation center line passing through an arbitrary position as described above, if the rotation center line and the position through which the rotation center line passes are determined randomly, the reference point of the tool 12 with respect to the tool mounting surface 10g. It may take an extremely long time to identify the actual position of T.

  As a countermeasure, the above-described embodiment limits the rotation center line to the rotation center lines parallel to the Xm axis, the Ym axis, and the Zm axis of the mechanical interface coordinate system ΣM. Further, the position through which the rotation center line passes is the registration position Pms, the temporary registration position Pms1 that is a set distance away from the registration position Pms in the setting direction, and the temporary position that is a set distance away from the registration position Pms in the opposite direction of the setting direction. The registration position is limited to Pms2. In other words, it can be said that the above-described embodiment defines a method for determining an arbitrary rotation center line passing through an arbitrary position.

10 Robot 10g Tool mounting part (Tool mounting surface)
12 Tool 14 Camera T Tool reference point (tip point)

Claims (6)

A tool dimension measuring method for measuring a position of a reference point of a tool with respect to a tool mounting portion, which is registered in a robot control device having a tool mounting portion for mounting a tool,
In a state where the camera has photographed an actual tool reference point, a robot operation is repeatedly executed such that the tool attachment portion rotates about an arbitrary rotation center line passing through an arbitrary position with respect to the tool attachment portion. Process,
A second step of measuring the amount of movement of the actual tool reference point moved by the rotation on the captured image of the camera each time the tool mounting portion rotates;
By repeatedly executing the third step of changing the arbitrary position and / or the arbitrary rotation center line every time the rotation of the tool attachment portion is completed,
Specify an arbitrary position where the movement amount on the camera image of the actual tool reference point that moves due to the rotation of the tool mounting part becomes substantially zero,
A method for measuring a tool dimension, characterized in that a specified arbitrary position is a position of a tool reference point with respect to a tool mounting portion. A tool dimension measuring method for measuring a position of a reference point of a tool with respect to a tool mounting portion, which is registered in a robot control device having a tool mounting portion for mounting a tool,
A first setting for rotating a predetermined angle about a rotation center line extending in a predetermined direction passing through the position with respect to each of at least one position having a predetermined positional relationship with respect to the setting position and a predetermined setting position with respect to the tool mounting portion And the process of
A second step of measuring an amount of movement of the actual tool reference point moved by execution of the first step on the camera-captured image for each of the set position and the at least one position;
A third step in which the position with the smallest amount of movement measured in the second step is set as a new set position;
Changing the predetermined positional relationship so that the direction to the set position is changed and / or the distance to the set direction is gradually reduced;
It is repeatedly executed until the position where the movement amount measured in the second step is substantially zero is specified, and the specified position is set as the position of the tool reference point with respect to the tool mounting portion. Measurement method. A tool dimension measuring method for measuring a position of a reference point of a tool with respect to a tool mounting portion, which is registered in a robot control device having a tool mounting portion for mounting a tool,
A first step of rotating the tool mounting portion by a predetermined angle around a first rotation center line passing through the position of the tool reference point registered in the control device;
A second step of measuring a first movement amount on the camera-captured image of the actual tool reference point moved by the execution of the first step;
Centered on a second rotation center line parallel to the first rotation center line passing through a position set in advance in a preset setting direction from the position of the tool reference point registered in the control device As a third step of rotating the tool mounting portion by the predetermined angle;
A fourth step of measuring a second movement amount on the camera-captured image of the actual tool reference point moved by the execution of the third step;
Tool attachment centered on a third rotation center line parallel to the first rotation center line passing through a position away from the set reference distance in the opposite direction of the setting direction from the position of the tool reference point registered in the control device A fifth step of rotating the portion by the predetermined angle;
A sixth step of measuring a third movement amount of the actual tool reference point moved by the execution of the fifth step on the captured image of the camera;
When the second movement amount is the smallest among the first to third movement amounts, the position of the tool reference point registered in the control device is changed to a position away from the set distance in the setting direction,
When the third movement amount is the smallest among the first to third movement amounts, the position of the tool reference point registered in the control device is changed to a position away from the set distance in the direction opposite to the set direction. 7 steps,
And repeatedly executing the eighth step of changing the setting direction and / or gradually decreasing the setting distance,
When the movement amount measured in any one of the second, fourth, and sixth steps becomes substantially zero, the repeated execution of the first to eighth steps is terminated. Measurement method. Predefine an orthogonal coordinate system having first, second and third axes;
Before the first step is performed for the first time,
A first movement vector on the captured image of the camera of the actual tool reference point, generated by translating the tool mounting portion in the first axial direction;
A second movement vector on the photographed image of the camera of the actual tool reference point generated by translating the tool mounting portion in the second axial direction;
An image taken by the camera of the actual tool reference point generated by rotating the tool mounting portion around the rotation center line parallel to the third axis passing through the position of the tool reference point registered in the control device A third movement vector above,
An image taken by the camera of the actual tool reference point generated by rotating the tool mounting portion around the rotation center line parallel to the first axis through the position of the tool reference point registered in the control device A fourth motion vector above,
A fifth movement vector on the captured image of the camera of the actual tool reference point, generated by translating the tool mounting portion in the second axial direction;
A sixth movement vector on the captured image of the camera of the actual tool reference point, generated by translating the tool mounting portion in the third axial direction;
A seventh movement vector on the captured image of the camera of the actual tool reference point, which is generated by translating the tool mounting portion in the first axial direction;
An image taken by the camera of the actual tool reference point generated by rotating the tool mounting portion around the rotation center line parallel to the second axis through the position of the tool reference point registered in the control device An eighth movement vector above,
Based on the ninth movement vector on the captured image of the camera of the actual tool reference point generated by translating the tool mounting portion in the third axial direction,
Find the error between the tool reference point registered in the controller and the actual tool reference point.
The tool dimension measuring method according to any one of claims 1 to 3, wherein the position of the tool reference point registered in the control device is corrected based on the obtained error. A tool size measuring device for measuring the position of a reference point of a tool with respect to the tool mounting portion, which is registered in a robot control device having a tool mounting portion for mounting a tool,
A camera that is placed around the robot and captures the actual tool reference point;
Measuring means for measuring the position of the tool reference point with respect to the tool mounting portion via the camera and the control device;
Measuring means
Causing the control device to repeatedly execute the operation of the robot such that the tool attachment portion rotates around an arbitrary rotation center line passing through an arbitrary position with respect to the tool attachment portion;
Measure the amount of movement of the actual tool reference point moved by the rotation on the captured image of the camera each time the tool mounting portion rotates, and
By repeatedly executing the arbitrary position and / or the arbitrary rotation center line every time the rotation of the tool attachment portion is completed,
Specify an arbitrary position where the movement amount on the camera image of the actual tool reference point that moves due to the rotation of the tool mounting part becomes substantially zero,
An apparatus for measuring a tool dimension, wherein an arbitrary specified position is registered in a control device as a position of a tool reference point with respect to a tool mounting portion. A robot having a tool mounting portion for attaching a tool and a control device, the position of the reference point of the tool with respect to the tool mounting portion being registered in the control device;
A robot comprising the tool dimension measuring device according to claim 5.

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