JP2016013608A - Teaching point conversion method of robot, device and robot cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reproduce a teaching point which has been taught to a first robot to a second robot with higher accuracy, in the case of replacing the first robot with the second robot.SOLUTION: Before and after replacement, three or more markers 31 which are not on one straight line other than first and second robots 2 are measured by a camera 4 mounted on a hand tip of the first and second robots 2 respectively. By using a measured value of two pairs of the markers 31 of three points measured by the position measuring device 4 respectively before and after the replacement, an installation error at the replacement time from the first robot 2 to the second robot 2 and a hand tip position specifying parameter for specifying a hand tip position in a base coordinate system 20b of the first robot 2 before the replacement and the second robot 2 after the replacement respectively are estimated. By using the estimated installation error and the hand tip position specifying parameter, the teaching point taught to the first robot 2 is converted to the teaching point for the second robot 2.

Description

  The present invention relates to a method and an apparatus for accurately reproducing a position taught by a robot before replacement with a robot after replacement when replacing the robot.

  If the robot or its parts are replaced due to aging or failure of the robot, the robot after replacement will be affected by the error of the robot installation position (hereinafter referred to as installation error) or individual difference (tolerance) of link parameters. The hand position is displaced by, for example, several millimeters, and it is necessary to correct the teaching point.

  On the other hand, a method is known in which three or more feature points on the floor surface or workpiece are measured by the robot before and after replacement, and coordinate conversion is performed so that the hand position of the robot does not change, thereby reducing installation errors and the like ( For example, see Patent Document 1). In addition, a technique is known in which a camera is always attached to a robot and all teaching points are photographed by the camera.

Japanese Patent No. 3733364

  However, since the conventional method is a method for moving a certain robot, only a simple coordinate transformation for eliminating an installation error is considered. For this reason, when there is a slight difference between two robots, such as when a certain robot is replaced with another robot, the influence of individual differences between the robots cannot be corrected, and the error increases. Therefore, the conventional method is effective in the case of relocation where only one robot is handled, but in the case of replacement where a plurality of robots are handled, individual differences among robots are not taken into account, so the teaching point reproduction accuracy is poor. Become.

  Such a problem is not limited to robot replacement due to aging or failure, but is a problem faced by general robot replacement.

  The present invention has been made to solve such a problem. In the case where the first robot is replaced with the second robot, the teaching point taught to the first robot is accurately obtained by the second robot. The purpose is to reproduce.

  In order to solve the above-described problem, a robot teaching point conversion method according to an aspect of the present invention provides a first robot that replaces the first robot with a second robot (hereinafter simply referred to as replacement). A robot teaching point conversion method for converting the teaching point taught in 1 to a teaching point of a second robot, wherein the position measuring device is attached to the hands of the first and second robots before and after replacement, respectively. Measuring three or more reference space positions that are not on a straight line other than the first or second robot, and measuring the three or more reference space positions measured by the position measuring device before the replacement. Using two sets of measurement values, that is, a set of three or more reference space position measurement values measured by the position measuring instrument after replacement, the first robot to the second robot Replace And estimating the hand position specifying parameter for specifying the hand position in the base coordinate system of each of the first robot before replacement and the second robot after replacement, and the estimated Converting a teaching point taught to the first robot into a teaching point of the second robot using an installation error and a hand position specifying parameter.

  The step of converting the teaching point is a step of calculating a hand position before replacement by solving kinematics using the teaching point of the first robot and the estimated hand position specifying parameter of the first robot. Using the hand position before the replacement and the installation error at the time of replacement, calculating the hand position viewed from the second robot, the hand position viewed from the second robot, and the estimated second And calculating a teaching point viewed from the second robot by solving inverse kinematics using the robot hand position specifying parameter.

  The hand position specifying parameter may be at least one parameter of a robot link parameter, rigidity, and encoder zero point.

  According to another aspect of the present invention, there is provided an apparatus for converting teaching points of a robot in which a teaching point taught to a first robot is replaced with a second teaching point when the first robot is replaced with a second robot (hereinafter simply referred to as replacement). A robot teaching point conversion device for converting to a robot teaching point, which is not on a straight line other than the first robot measured by a position measuring device attached to the hand of the first robot before replacement. Two sets of a set of three or more reference space position measurement values and a set of three or more reference space position measurement values measured by a position measuring device attached to the hand of the second robot after replacement When replacing the first robot with the second robot by using two sets of measurement values of the reference space position stored in the storage unit and the three or more reference space positions stored in the storage unit Installation error and replacement A hand position specifying parameter for specifying the hand position in the base coordinate system of each of the first robot and the second robot after replacement is estimated, and the estimated installation error and hand position specifying parameter are used. And a converter for converting the teaching point taught to the first robot into the teaching point of the second robot.

  The converter calculates a hand position before replacement by solving kinematics using the teaching point of the first robot and the estimated hand position specifying parameter of the first robot, and calculates the hand position before replacement. A hand position as seen from the second robot is calculated using the position and the installation error at the time of replacement, and the hand position as seen from the second robot and the estimated hand position specifying parameter of the second robot; The teaching point viewed from the second robot may be calculated by solving inverse kinematics using, and the teaching point may be converted.

  The hand position specifying parameter may be at least one parameter of a robot link parameter, rigidity, and encoder zero point.

  The position measuring device may be configured to be attachable to or detachable from the hands of the first and second robots. This position detector may be a camera, for example.

  A robot cell according to another aspect of the present invention includes a first robot or a second robot when the first robot is replaced with a second robot (hereinafter simply referred to as replacement), and the first or second robot. A position measuring device attached to the hand of the robot, a jig including markers indicating three or more reference space positions not on a straight line other than the first or second robot, and the first robot before replacement The three points measured by the position measuring instrument attached to the hand of the second robot after replacement with a set of three or more reference space position measurement values measured by the position measuring instrument attached to the hand of the second robot A storage device that stores two sets of measurement values of the measurement value set of the reference space position described above, and two sets of measurement values of the reference space position of the three or more points stored in the storage device, From the first robot An installation error at the time of replacement with the second robot, and a hand position specifying parameter for specifying the hand position in the base coordinate system of each of the first robot before replacement and the second robot after replacement; And a converter for converting the teaching point taught to the first robot into the teaching point of the second robot using the estimated installation error and hand position specifying parameter, the first robot And a teaching point conversion device configured to convert the teaching points taught in (1) to the teaching points of the second robot.

  According to the present invention, when the first robot is replaced with the second robot, the teaching point taught to the first robot can be reproduced with high accuracy by the second robot.

1 is an overall configuration diagram of a robot system for carrying out a robot teaching point conversion method according to a first embodiment of the present invention. It is a top view which shows the structure of the marker board of FIG. It is a block diagram which shows the structure of the robot control apparatus of FIG. It is a block diagram which shows the structure of the teaching point conversion apparatus of FIG. It is the flowchart which showed the flow of the work accompanying substitution of the robot of FIG. It is the flowchart which showed the specific procedure of the operation | work before replacement of FIG. It is a schematic diagram which shows the outline | summary of the measurement of the marker board by a camera. It is the flowchart which showed the specific procedure of the operation | work after replacement of FIG. It is a schematic diagram which shows the relationship between a camera coordinate system and a marker board coordinate system. It is a schematic diagram which shows the relationship of each coordinate system of the base of the robot before and behind, a flange, and a camera. It is a flowchart which shows the procedure of the teaching point conversion process of FIG. It is a schematic diagram which shows the outline | summary of the robot cell which concerns on Embodiment 2 of this invention.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the following, the same or corresponding elements are denoted by the same reference numerals, and redundant description thereof is omitted.

(Embodiment 1)
[Constitution]
FIG. 1 is an overall configuration diagram of a robot system for carrying out the robot teaching point conversion method according to the first embodiment of the present invention. As shown in FIG. 1, the robot system 1 includes a robot 2, a measuring jig 3, a position measuring device 4, a robot control device 5, and a teaching point conversion device 6. (Except the jig 3) is connected to be communicable by wire or wirelessly.

  The robot 2 is a robot that performs work on the workpiece W. In the present embodiment, an industrial robot is assumed. However, the robot 2 is not limited thereto, and may be a home robot, for example. In the present embodiment, the robot 2 includes a base (base) 10 installed on a mounting surface such as a floor surface, and an arm 11 protruding from the base 10. A coordinate system based on the upper surface of the base 10 is referred to as a base coordinate system 20b. The arm 11 is provided with a plurality of joints 11a to 11d that operate in response to a command from the robot control device 5, and a flange-like tool attachment portion 11e (hereinafter also referred to as “flange”) is provided at the tip thereof. . A coordinate system based on the flange 11e is referred to as a flange coordinate system 20f. The joint may rotate or move linearly. Adjacent joints are connected by links.

  The joints 11a to 11d incorporate an encoder (not shown) that is an example of an angle detector capable of detecting the angle of each joint, and the angles of the joints 11a to 11d and the links that constitute the arm 11 are incorporated. The position and orientation of the flange 11e in the base coordinate system 20b can be specified by the dimensions. A tool 12 is attached to the flange 11e. In the example of FIG. 1, the tool 12 is a welding torch having a cylindrical tip, but is not particularly limited. Further, the work W that is the work target of the robot 2 is fixed on the work table 15 via an attachment jig (not shown).

  The position measuring device 4 is attached to the hand of the robot 2. In the present embodiment, the position measuring device 4 is a camera that can be attached to or detached from the tool 12 at the tip of the arm 11 of the robot 2. Two-dimensional coordinate data in a predetermined coordinate system (hereinafter referred to as “camera coordinate system 20c”) imaged by the camera 4 is generated. The position measuring device 4 outputs the generated coordinate data of the measurement points to the teaching point conversion device 6.

  The measuring jig 3 is disposed at a place other than the robot 2 when the robot 2 is replaced (on the floor surface or the work table 15 in FIG. 1). The measurement jig 3 is a marker board in the present embodiment. FIG. 2 is a plan view showing the configuration of the marker board 3. As shown in FIG. 2, the marker board 3 includes a square board 30 and markers 31 indicating three or more reference space positions attached on the board 30. A predetermined coordinate system based on one of the four corners of the marker board 3 is referred to as a marker board coordinate system 20m. In the present embodiment, the three markers 31 are attached at positions not on a straight line from the marker board coordinate system 20m. Three marker boards 3 are arranged and fixed at arbitrary positions around the robot 2 before replacement. Each marker board 3 may be arranged so that it can be returned to the same position by a marker such as a positioning pin without being fixed.

  FIG. 3 is a block diagram showing a configuration of the robot control device 5 of FIG. As shown in FIG. 3, the robot control device 5 includes a calculation unit 51, a storage unit 52, a communication interface 53, an input / output interface 54, and a servo control unit 55 for driving the robot. The function of the teaching point conversion device 6 may be included in the robot control device 5.

  The arithmetic unit 51 performs arithmetic processing for robot control and generates a control command for the robot 2. The servo control unit 55 is configured to control the operation of each axis of the joints 11 a to 11 d of the robot 2 based on the control command generated by the calculation unit 51. The storage unit 52 stores information such as a basic program of the robot control device 5, an operation program (for example, a welding program) of the robot 2, and data for performing processing related to teaching point conversion described later. The communication interface 53 is connected to the teaching point conversion device 6. Via this communication interface 53, the robot control device 5 communicates with the teaching point conversion device 6, and transmits a command related to measurement described later or receives data such as a measurement result. The input / output interface 54 is connected to a teaching operation terminal (for example, a teach pendant, not shown). The robot controller 5 operates the robot 2 through manual operation of the teaching operation terminal, and also creates, corrects, registers, or sets various parameters of the operation program of the robot 2 and plays back the taught operation program. Run.

  FIG. 4 is a block diagram showing the configuration of the teaching point conversion apparatus 6 of FIG. As shown in FIG. 4, a calculation unit 61, a storage unit 62, a camera interface 63, a monitor interface 64, and a communication interface 65 are provided.

  The calculation unit 61 is connected to the storage unit 62. The calculation unit 61 is connected to the camera 4 via the camera interface 63, connected to the display device 13 via the monitor interface 64, and connected to the robot control device 5 via the communication interface 65.

  The calculation unit 61 acquires the angles of the joints 11 a to 11 d corresponding to the posture of the robot 2 from the robot control device 5. In addition, the calculation unit 61 transmits a shooting command signal to the camera 4 according to a shooting command input from an input unit (not shown), and receives a video signal shot by the camera 4. The calculation unit 61 performs image processing on the received video signal, detects the position of a specific point or shape feature in the image, and calculates the three-dimensional position of the marker 31 based on the detected position. Then, the three-dimensional position of the marker 31 is stored in the storage unit 62 in association with the angles of the joints 11a to 11d of the robot 2 at the time of photographing. In addition, the calculation unit 61 performs a parameter estimation process and a teaching point conversion process which will be described later. Furthermore, the calculation unit 61 causes the display device 13 to display an image being captured by the camera 4, a past image, an image subjected to image processing, and the like as necessary.

  In the robot system 1 configured as described above, when the robot 2 is replaced with a new robot due to aging or failure, the teaching point taught to the old first robot 2 is converted to the teaching point of the new second robot 2. Work is required. FIG. 5 is a flowchart showing a work flow associated with the replacement of the robot 2. As shown in FIG. 5, this work is roughly divided into a work performed in advance before the replacement (step 1), an actual replacement work of the robot 2 (step 2), and a work performed after the replacement (step 3). This will be specifically described below.

[Before replacement]
FIG. 6 is a flowchart showing a specific procedure of the pre-replacement work. As shown in FIG. 6, first, the operator attaches the camera 4 to the robot 2 (step 61). Here, the camera 4 is attached to the tool 12 at the tip of the arm 11 of the robot 2.

  Next, the worker places the marker board 3 at an arbitrary position around the robot 2 (step 62). Here, three marker boards 3 are arranged and fixed on any floor surface or work table around the robot 2.

  Next, the operator operates the robot 2 with the above-described teaching operation terminal (not shown), inputs a shooting command from the input unit of the teaching point conversion device 6, and measures the marker 31 with the camera 4 (step). 63). FIG. 7 is a schematic diagram showing an outline of marker board measurement by the camera 4. As shown in FIG. 7, the camera 4 changes the posture of the robot 2 with respect to the marker board 3 and measures, for example, three times. The number of measurements is not limited to three. Here, the measurement includes photographing the marker board 3 with the camera 4 and storing the angles of the joints of the robot 2. As described above, the storage unit 62 stores the three-dimensional position of the marker 31 in the storage unit 62 in association with the angles of the joints 11a to 11d of the robot 2 at the time of shooting. Is done by. The measurement is performed a plurality of times while changing the posture of the robot 2 with respect to each marker board 3, and the measurement is performed with respect to the prepared marker board. The camera 4 may be detached from the robot 2 after the measurement is completed. These operations are performed in advance before the replacement request for the robot 2 is generated at the latest, such as when the robot 2 is installed.

  Thereafter, teaching points are created and the work is executed (steps 64 and 65). When the robot 2 is a welding robot, teaching points for welding work are generated and the welding work is performed. Work is performed until the robot 2 has a replacement request such as aging or failure.

[Robot replacement work]
When a robot becomes old or breaks down, it is replaced with a new robot. Strictly speaking, even with such replacement, there are individual differences in the link parameters or rigidity of the robot. For this reason, even if the teaching point before replacement is given to the robot after replacement, the hand position is shifted.

[Post-replacement work]
FIG. 8 is a flowchart showing a specific procedure for post-replacement work. As shown in FIG. 8, first, the worker attaches the camera 4 to the robot 2 (step 81). Thereafter, as in the pre-replacement operation, the marker measurement performed before the replacement is also performed on the robot 2 after the replacement (step 82). Here, at least one marker board 3 is arranged at the same position as before the replacement. If necessary, the marker board 3 may be disposed at a position where the marker board 3 is not disposed before replacement, or may not be disposed at the position where the marker board 3 is disposed before replacement. At least one marker board 3 is measured. Here, the posture of the robot 2 that measures the marker board 3 may be different before and after the replacement.

Further, the teaching point conversion device 6 (more precisely, the calculation unit 61) calculates the marker position as viewed from the position of each camera 4 using the measurement results measured before and after the replacement. Specifically, the image taken before and after the replacement is subjected to image processing (for example, pattern matching) to determine at which position on the image the marker 31 is present. FIG. 9 is a schematic diagram showing the relationship between the camera coordinate system 20c and the marker board coordinate system 20m. As shown in FIG. 9, the marker position on the image obtained by image processing is u _img , the marker position viewed from the camera coordinate system 20c is x _{c_mk} , the internal parameters of the camera 4 are K, the marker board coordinate system 20m and the camera It is _assumed that the transformation matrix between the coordinate systems 20c is T _{c_bd} , and the marker position viewed from the board coordinate system 20m is x _{bd_mk} . Here, s is the z component of the marker position as viewed from the camera coordinate system 20c. In this case, the following equation (1) is established.
u _img = (1 / s) * K * T _{c_bd} * x _{bd_mk} (1)

Since Equation (1) can be set as many as the number of markers 31 on the marker board 3, an unknown transformation matrix T _{c_bd} can be obtained by a known method. Specifically, an evaluation function is created that adds the sum of squares obtained by subtracting the right side from the left side of Equation (1) by the number of simultaneous equations. Then, a transformation matrix T _{c_bd} that minimizes the evaluation function is obtained by a technique such as the steepest gradient method.

Thereby, the marker position _{xc_mk} viewed from the camera coordinate system 20c can be obtained by the following equation (2).
x _{c_mk} = T _{c_bd} * x _{bd_mk} (2)

  At this time, each marker position is calculated from the camera coordinate system 20c for all the images obtained before and after the replacement. Save the calculation result along with the measurement data. Note that the calculation of each marker position from the camera coordinate system 20c for the image before replacement may be performed before or after replacement.

  Next, the teaching point conversion apparatus 6 estimates the installation error at the time of replacement and the parameters before and after replacement using the marker position from the camera 4 before and after replacement (step 83 in FIG. 8). Here, the parameters are parameters for specifying the hand positions in the respective base coordinate systems 20b of the robots before and after replacement, and in this embodiment, are the link parameters and the rigidity parameters of the robot 2.

FIG. 10 is a schematic diagram showing the relationship between the base, flange, and camera coordinate systems before and after replacement. As shown in FIG. 10, the transformation matrices from the base coordinate system 20b to the flange coordinate system 20f of the robot before and after replacement are _{Tb1_f1} and _{Tb2_f2} . _Let T _{f1_c1} and T _{f2_c2} be transformation matrices from the flange coordinate system 20f of the robot before and after replacement to the camera coordinate system 20c. The vectors from the camera coordinate system 20c to the marker before replacement and after replacement are set to _{xc1_mk} and _{xc2_mk} . The marker position viewed from the base coordinate system 20b of the robot before replacement is assumed to be _{xb1_mk} . A transformation matrix between the base coordinate systems 20b of the robot before and after replacement is assumed to be _{Tb1_b2} .

Here, T _{f1_c1} and T _{f2_c2} are the attachment positions of the camera 4 before and after the replacement. However, the attachment position of the camera 4 may be set in advance, or initially unknown as in the case of the link parameter. You may ask for it. Since camera calibration is well known, detailed description thereof is omitted (see, for example, JP-A-2005-149299).

Also, T _{b1 — f1} and T _{b2 — f2} can be calculated by kinematics if the parameters (link parameters and stiffness parameters) and joint angles are known. Here, the joint angle is known because it is stored at the time of measurement, but the link parameter and the stiffness parameter are unknown _{numbers, and} T _{b1 — b2} which means an installation error at the time of replacement is also an unknown number. Further, when the mounting position of the camera 4 is unknown, the camera mounting positions T _{f1_c1} and T _{f2_c2} are also unknown.

The following equation (3) holds for the robot before replacement.
x _{b1_mk} = T _{b1_f1} * T _{f1_c1} * x _{c1_mk} (3)
On the other hand, the following equation (4) holds for the replaced robot.
x _{b1_mk} = T _{b1_b2} * T _{b2_f2} * T _{f2_c2} * x _{c2_mk} (4)

Since the equations (3) and (4) can be made as many as the measured posture × the number of markers, the installation error T _{b1 — b2} , the link parameter, and the unknown contained in the equations (3) and (4) The stiffness parameter can be obtained by a general known method. Specifically, an evaluation function is created that adds the sum of squares obtained by subtracting the right side from the left side of each of formulas (3) and (4) by the number of simultaneous formulas. Then, an installation error T _{b1 — b2} , a link parameter, and a stiffness parameter that minimize the evaluation function are obtained by a method such as the steepest gradient method. In this way, the installation error at the time of replacement and the parameters before and after the replacement (link parameter and stiffness parameter) are estimated.

  Next, the teaching point conversion device 6 converts the teaching point (joint angle) before replacement into the teaching point (joint angle) of the robot after replacement (step 84 in FIG. 8). By using the installation error at the time of replacement, the link parameter and rigidity of the robot after replacement obtained in step 83, the joint angle used as the teaching point before replacement is exchanged for the robot after replacement. If the teaching point is converted not to the joint angle but to the hand position, it is converted into the joint angle by solving inverse kinematics in advance using nominal link parameters.

FIG. 11 is a flowchart showing the procedure of the teaching point conversion process. As shown in FIG. 11, the teaching point conversion apparatus 6 first calculates the hand position before replacement (step 111). Specifically, by using the teaching point (joint angle) of the robot before replacement, the estimated link parameter and rigidity before replacement, and solving kinematics considering the deflection due to rigidity and link parameters, the teaching before replacement The hand position _{xb1_cmd} before replacement is calculated from the point (joint angle).

Next, the teaching point conversion device 6 calculates the hand position after replacement (step 112). By the following equation in particular with reference to installation errors _{T B1_b2} when substitutions were hand position _{x B1_cmd,} and estimated before substitution (5), and calculates the hand position _{x B2_cmd} viewed from the robot after the replacement.
_{xb2_cmd} = _{Tb1_b2} * _{xb1_cmd} (5)

Finally, the teaching point conversion apparatus 6 calculates the teaching point of the robot after replacement (step 113). Specifically, by using the link parameter after replacement, the rigidity, and the calculated hand position _{xb2_cmd} after replacement, solving the inverse kinematics considering the flexure due to the rigidity and the link parameter, teaching the robot after the replacement A point (joint angle) is calculated. By giving the joint angle to the robot after replacement, a teaching point that does not change the hand position can be generated even for a robot with individual differences in link parameters and stiffness.

  Further, when it is desired to give the teaching point of the robot after the replacement at the hand position, the hand position may be obtained by solving the kinematics using the obtained joint angle using the nominal link parameter.

  Further, when the internal calculation processing of the robot controller 5 calculates with nominal parameters, it is suitable to use the nominal parameters at the beginning and end as in the present embodiment, but the invention is not limited to this. When the internal calculation processing is not performed with the nominal parameters, the processing may be performed with the parameters according to the controller.

  According to the above embodiment, not only the error of the installation position at the time of robot replacement, but also the parameters for specifying the hand positions of the pair of robots to be replaced with each other, and using those information, The teaching point taught to the robot before replacement is converted to the teaching point of the robot after replacement. Thereby, the teaching point after replacement can be reproduced with high accuracy. In addition, the conventional method of always attaching the camera to the robot restricts the movement of the robot in a narrow place such as welding work and restricts the movement of the robot, complicating the contents of the required image processing. According to the invention, such a problem is solved.

  In the present embodiment, the replacement of the robot when the robot has deteriorated or failed has been described. However, the present invention is not limited to this, and a general robot replacement may be used.

  Further, in the present embodiment, the step 84 (FIG. 8) of converting the teaching points is performed by solving kinematics using the teaching points of the robot before replacement and the estimated robot parameters, thereby obtaining the hand before replacement. Step 111 (FIG. 11) for calculating the position, step 112 (FIG. 11) for calculating the hand position as seen from the robot after replacement, using the hand position before replacement and the installation error at the time of replacement, The method further includes a step 113 (FIG. 11) of calculating the teaching point viewed from the replaced robot by solving the inverse kinematics using the hand position viewed from the robot and the estimated parameter of the replaced robot. Thus, the teaching point after replacement can be calculated using the dynamic model of the robot arm.

  In the present embodiment, the parameters for specifying the hand position of the robot are the link parameter and the rigidity parameter of the robot, but are not limited thereto. By using at least one parameter of the robot link parameter, rigidity, and encoder zero point, the hand position in each base coordinate system 20b of the robot before and after replacement can be specified with higher accuracy.

  In the present embodiment, the position measuring device 4 is configured to be attachable to or detachable from the hands of the first and second robots. Since the robot can be removed at the time of the work to be automated, the movement of the robot during the work is not limited, and the freedom of movement can be improved.

(Embodiment 2)
FIG. 12 is a schematic diagram showing an outline of the robot cell according to the second embodiment of the present invention. As shown in FIG. 12, a robot cell 100 including a robot 2, a camera 4 attached to the hand of the robot 2, and a marker board 3 including three or more reference space positions not on a straight line other than the robot 2 is provided. This is just an example. The robot 2, the camera 4, and the marker board 3 are the same as those in the first embodiment.

  Even with such a configuration, the same effect as in the first embodiment can be obtained by the teaching point conversion device 6 as in the first embodiment. Furthermore, in the present embodiment, the marker board 3 is permanently installed in the robot cell 100 and the positional relationship with the robot 2 is measured in advance, thereby reducing the number of unknowns and reducing the number of measurements.

  The present method, apparatus, and robot cell are applicable not only when the configuration of the robot 2 (for example, the joint configuration or link configuration) is the same before and after replacement, but also when the configuration of the robot 2 before and after replacement is different. .

(Other embodiments)
In the first and second embodiments, the position measuring device 4 is a camera. For example, an ultrasonic detector, a three-dimensional digitizer that can specify a position in a three-dimensional space, a two-dimensional digitizer, a GPS, and a magnetic A type position measurement system, a laser displacement meter, or the like may be used.

  In the first and second embodiments, the measurement jig 3 is a marker board. However, the measurement jig 3 is not limited to this as long as it includes three or more reference space positions that are not on a straight line other than the robot 2.

  In the present embodiment, the marker board 3 is fixed, but the marker board 3 may move along a positioner or a travel axis.

  In the first and second embodiments, the teaching point conversion process when the robot 2 body is replaced has been described. However, the present invention is not limited to this. Teach also when link parameters change (for example, the teaching point taught in the summer is converted to the winter season by performing the pre-replacement work in the summer when the temperature is high and the post-replacement work in the winter when the temperature is high) Point conversion processing may be performed.

  In the first and second embodiments, the robot control device 5 is configured to operate the robot 2 through manual operation of the teaching operation terminal. However, the robot control device 5 operates the operation panel of the robot control device 5 to operate the robot. 2 may be operated, or the robot 2 may be configured to operate in response to a command from the teaching point conversion device 6.

  From the foregoing description, many modifications and other embodiments of the present invention are obvious to one skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. Details of at least one of its structure and function can be substantially changed without departing from the spirit of the present invention.

  The present invention is useful not only for robot replacement due to aging or failure, but also for general robot replacement.

1 Robot system 2 Robot body 3 Measuring jig (marker board)
4 Position measuring device (camera)
5 Robot control device 6 Teaching point conversion device 10 Base 11 Arm 12 Tool 13 Display device 15 Work table 20b Base coordinate system 20c Camera coordinate system 20f Flange coordinate system 20m Marker board coordinate system 30 Board 31 Reference space position (marker)
100 Robot cell W Workpiece

Claims (7)

A robot teaching point conversion method for converting a teaching point taught to a first robot to a teaching point of a second robot when replacing the first robot with a second robot (hereinafter simply referred to as replacement). And
Measuring three or more reference space positions that are not on a straight line other than the first or second robot by a position measuring device attached to the hand of the first and second robots before and after replacement, respectively ,
A set of three or more reference space position measurement values measured by the position measuring device before the replacement and a set of three or more reference space position measurement values measured by the position measuring device after the replacement. Using two sets of measured values, the installation error at the time of replacement from the first robot to the second robot and the bases of the first robot before replacement and the second robot after replacement Estimating a hand position specifying parameter for specifying the hand position in the coordinate system;
Converting the teaching point taught to the first robot into the teaching point of the second robot using the estimated installation error and hand position specifying parameter;
A method for converting teaching points of a robot. The step of converting the teaching point includes:
Calculating a hand position before replacement by solving kinematics using the teaching point of the first robot and the estimated hand position specifying parameter of the first robot;
Using the hand position before replacement and the installation error at the time of replacement, calculating the hand position viewed from the second robot;
Calculating a teaching point viewed from the second robot by solving inverse kinematics using the hand position viewed from the second robot and the estimated hand position specifying parameter of the second robot;
A method for converting teaching points of a robot.   The robot teaching point conversion method according to claim 1, wherein the hand position specifying parameter is at least one parameter of a robot link parameter, rigidity, and encoder zero point. A robot teaching point conversion device for converting a teaching point taught to a first robot to a teaching point of a second robot when replacing the first robot with a second robot (hereinafter simply referred to as replacement). ,
A set of three or more reference space position measurement values that are not on a straight line other than the first robot measured by a position measuring device attached to the hand of the first robot before replacement and the second after replacement. A storage device for storing two sets of measurement values, a set of three or more reference space position measurement values measured by a position measurement device attached to the hand of the robot;
Using two sets of measured values of the reference space positions of three or more points stored in the storage device, the installation error at the time of replacement from the first robot to the second robot, and the first before replacement Estimating the hand position specifying parameter for specifying the hand position in the base coordinate system of each of the first robot and the second robot after replacement, and using the estimated installation error and the hand position specifying parameter, A converter for converting the teaching point taught to the first robot into the teaching point of the second robot;
A robot teaching point conversion device. The converter is
By calculating kinematics using the teaching point of the first robot and the estimated first hand position specifying parameter of the first robot, the hand position before replacement is calculated, and the hand position before replacement and the replacement time The hand position as seen from the second robot is calculated using the installation error and the reverse movement is performed using the hand position as seen from the second robot and the estimated hand position specifying parameter of the second robot. The robot teaching point conversion apparatus according to claim 4, wherein the teaching point conversion unit is configured to convert the teaching point by calculating the teaching point viewed from the second robot by solving the learning.   6. The robot teaching point conversion apparatus according to claim 4 or 5, wherein the hand position specifying parameter is at least one parameter of a robot link parameter, rigidity, and encoder zero point. The first robot or the second robot in the case of replacing the first robot with the second robot (hereinafter simply referred to as replacement);
A position measuring instrument attached to the hand of the first or second robot;
A jig including markers indicating three or more reference space positions not on a straight line other than the first or second robot;
A set of three or more reference space position measurement values measured by a position measuring instrument attached to the hand of the first robot before replacement, and a position measurement attached to the hand of the second robot after replacement. A storage device for storing two sets of measurement values of the three or more reference space positions measured by the storage device, and two sets of the three or more reference space positions stored in the storage device And the base coordinate system of each of the first robot before replacement and the second robot after replacement using the measured values of the first robot and the second robot. A hand position specifying parameter for specifying the hand position in the position is estimated, and the teaching point taught to the first robot using the estimated installation error and hand position specifying parameter is used as the teaching point of the second robot. conversion That includes a converter, a, and a configuration is taught points converter to convert the teaching point which is taught in the first robot to the teaching point of the second robot, robot cell.

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