ROBOT TRAINING SYSTEM

Abstract

Robot training system (1), comprising: a first end effector (11) having a gripping structure and used for teaching; a second end effector (12) having the gripping structure and mounted on a robot; a position / attitude fixing tool (13) having a gripped structure in which a position and an attitude with respect to the first end effector (11) and the second end effector (12) are uniquely determined by being gripped by the gripping structure of the first end effector (11) and the second end effector (12); a teaching data transformation unit (6) configured to transform first teaching data (210) representing position / attitude information of the first end effector (11) during a teaching process into second teaching data (510) representing position / attitude information of the second end effector (12); and a robot control unit (51) configured to cause the robot (43) to operate on the basis of the second teaching data (510), wherein the learning data transformation unit (6) transforms the first learning data (210) into the second learning data (510) using a first relative position / attitude indicating a relative position / attitude between the first end effector (11) and the position / attitude fixing tool (13) when the position / attitude fixing tool (13) is gripped, and a second relative position / attitude indicating a relative position / attitude between the second end effector (12) and the position / attitude fixing tool (13) when the position / attitude fixing tool is gripped.

Description

The present invention relates to a robot teaching system that learns a robot to perform a predetermined work.As robot teaching systems that teach robots to perform predetermined works, systems are known in which teaching persons hold teaching devices and robots are caused to reproduce demonstrated works.For example, WO 2021 / 122 580 A1 discloses a robot teaching system in which a teaching person who holds a teaching device performs a predetermined work, a path of the apparatus is detected by a sensor, and then an operation program for a robot is automatically generated based on a sensor value. In the teaching device of WO 2021 / 122 580 A1, various tools (corresponding to "end effectors") corresponding to teaching various kinds of work may be attached.However, in the robot teaching system disclosed in WO 2021 / 122 580 A1, a positional error occurs in the teaching data due to a difference in equipment or structure between an end effector mounted on the teaching device and an end effector mounted on the robot, thereby degrading the reproduction accuracy of the taught work.Furthermore, teaching of a robot is known from post-published DE 10 2022 122 658 A1, in which a human demonstration is detected by sensors. DE 10 2014 208 530 A1 relates to a robot having a changing tool which can also be gripped by a human hand. EP 3 609 656 B1 discloses a tool which can be gripped and used by both a human and a robot. EP 1 987 406 B1 relates to a measuring device by means of which a robot can be controlled. WO 2017 / 03650 A1 teaches a robot teaching system. Finally, DE 10 2015 206 575 A1 relates to a robot hand-held operator device.It is an object of the present invention to provide a robot teaching system capable of reproducing a predetermined taught work with high accuracy even when there is a device or structure difference between an end effector used for teaching and an end effector mounted on a robot.This object is achieved by a robot teaching system according to claim 1.According to an aspect of the present invention, a robot teaching system includes: a first end effector having a gripping structure and used for teaching; a second end effector having the gripping structure and mounted on a robot; a position / posture fixing tool having a gripped structure in which a position and a posture with respect to the first end effector and the second end effector are uniquely determined by being gripped by the gripping structure of the first end effector and the second end effector; a teaching data transformation unit configured to transform first teaching data representing position / posture information of the first end effector during a teaching operation into second teaching data representing position / posture information of the second end effector; and a robot control unit configured to cause the robot to operate based on the second teaching data. The teaching data transformation unit transforms the first teaching data into the second teaching data using a first relative position / posture indicating a relative position / posture between the first end effector and the position / posture fixation tool when the position / posture fixation tool is gripped and a second relative position / posture indicating a relative position / posture between the second end effector and the position / posture fixation tool when the position / posture fixation tool is gripped.According to the present invention, it is possible to provide a robot teaching system capable of reproducing a predetermined taught work with high accuracy even when there is a device or structure difference between an end effector used for teaching and an end effector mounted on a robot.An overview of the attached drawings is provided below: FIG. 1 is a diagram illustrating an operation of a robot teaching system according to a first embodiment. FIG. 2A is a diagram illustrating a detailed configuration of a first end effector and a position / posture fixing tool according to the first embodiment. FIG. 2B is a diagram illustrating a first relative position / relative posture calculation process according to the first embodiment. FIG. 3A is a diagram illustrating a detailed configuration of a second end effector and the position / posture fixing tool according to the first embodiment. FIG. 3B is a diagram illustrating a second relative position / relative posture calculation process according to the first embodiment. FIG. 4 is a diagram illustrating an operation of a learning data transformation unit according to the first embodiment. FIG. 5A is a diagram illustrating a first end effector use learning process according to the first embodiment. FIG. 5B is a diagram illustrating an image of coordinate transformation in a first coordinate transformation unit shown on a work station according to the first embodiment. FIG. 5C is a diagram illustrating an image of a coordinate transformation and a robot operation process in a second coordinate transformation unit shown on a work station according to the first embodiment. FIG. 6 is a diagram illustrating a robot control unit according to the first embodiment. FIG. 7A is a diagram illustrating a configuration and an operation of a learning data transformation unit according to a second embodiment. FIG. 7B is a diagram illustrating an example of another configuration of the learning data transformation unit according to the second embodiment. FIG. 7C is a diagram illustrating an example of another configuration of the learning data transformation unit according to the second embodiment. FIG. 8 is a diagram illustrating a first end effector according to a third embodiment. FIG. 9 is a diagram illustrating a first end effector use learning process according to a fourth embodiment.Hereinafter, embodiments will be described with reference to the drawings.Hereinafter, the description will be made in sufficient detail for practicing the present disclosure to those skilled in the art, but other forms of assembly are possible.FIG. 1 is a diagram showing the operation of a robot teaching system according to a first embodiment. In the robot teaching system 1, a situation in which a robot 53 to which a second end effector 12 is attached is taught is assumed. A teaching person 23 performs the teaching by causing the robot 53 to which the second end effector 12 is mounted to reproduce a position and posture of a first end effector 11 when a predetermined work is demonstrated using the first end effector 11 instead of the robot proper 53 and the second end effector 12. Hereinafter, the "position and posture" will be abbreviated as "position / posture".In such learning, due to a device difference or a structure difference between the first end effector 11 and the second end effector 12 (hereinafter, "the device difference or the structure difference" is referred to as "device difference or the like"), the predetermined work is not likely to be reproducible with high accuracy even when the second end effector 12 completely tracks a position / posture of the first end effector 11.Accordingly, according to the technique of the present invention, the device difference or the like between the first end effector 11 and the second end effector 12 is calibrated using a common position / posture fixing tool 13 that can be gripped by both the first end effector 11 and the second end effector 12.As illustrated in FIG. 1, the robot teaching system 1 largely performs five processes including a first end effector use teaching process 2, a first relative position / relative posture calculation process 3, a second relative position / relative posture calculation process 4, a robot operation process 5, and a teaching data transformation process.The first end effector use learning process 2 is a process of measuring, by a measurement unit 22 (e.g., an infrared camera), position / posture information of the first end effector 11 when the learning person 23 holding the first end effector 11 demonstrates a predetermined work including gripping of a work object 24, and generating first learning data 210 representing the position / posture information of the first end effector 11 during a learning operation by a first end effector use learning unit 21.The first relative position / relative posture calculation process 3 is a process of measuring, by a measurement unit 32 (e.g., an infrared camera) functioning as a first measurement unit, a position / posture of each of the first end effector 11 and the position / posture fixation tool 13 when the position / posture fixation tool 13 is gripped by the first end effector 11, and calculating, by a first relative position / posture calculation unit 31, a first relative position / posture 310 representing a relative position / posture between the first end effector 11 and the position / posture fixation tool 13. the measurement unit 32 can calculate the position / posture of each of the first end effector 11 and the position / posture fixation tool 13 using a design parameter or the like, instead of measuring the position / posture of each of the first end effector 11 and the position / posture fixing tool 13.The second relative position / relative posture calculation process 4 is a process of measuring, by a measurement unit 42 (e.g., an infrared camera) functioning as a second measurement unit, a position / posture of each of the second end effector 12 and the position / posture fixation tool 13 when the position / posture fixation tool 13 is gripped by the second end effector 12, and calculating, by a second relative position / posture calculation unit 41, a second relative position / posture 410 representing a relative position / posture between the second end effector 12 and the position / posture fixation tool 13. the measurement unit 42 can calculate the position / posture of each of the second end effector 12 and the position / posture fixation tool 13 using a design parameter or the like, instead of measuring the position / posture of both the second end effector 12 and the position / posture fixing tool 13.In the robot teaching system 1, the order in which the above processes 2, 3, and 4 are performed does not matter.The learning data transformation process is a process in which the learning data transformation unit 6 transforms the first learning data 210 into second learning data 510 using the first relative position / posture 310 and the second relative position / posture 410.The robot operation process 5 is a process in which a robot control unit 51 controls and operates the robot 53 based on the second teaching data 510. For example, as described below, the robot control unit 51 controls the robot 53 such that the position / posture information of the second end effector 12 included in the second teaching data 510 generated by a teaching data transformation unit 6 coincides with an actual position / posture of the second end effector 12, and causes the robot 53 to reproduce a predetermined work including gripping of the work object 54.FIG. 2A is a diagram illustrating a detailed configuration of the first end effector and the position / posture fixing tool according to the first embodiment.The first end effector 11 includes, as a gripping structure, a base member 113 in which a position / posture is measured, and a pair of gripping members 111 and 112 mounted on the base member 113 and clamping the position / posture fixing tool 13 and the work object. The gripping members 111 and 112 of the first end effector 11 include contact surfaces 1111 (a contact surface of the gripping member 112 is not illustrated) and fastening portions 1112 and 1122, respectively.In the first embodiment, the first end effector 11 is a tool manufactured by modeling the second end effector 12, is not mounted on the robot, and is held and handled by a worker. Accordingly, a grip member 114 held by the worker is mounted on the base member 113 of the first end effector 11. The grip member 114 includes a mechanism (not illustrated) that can be removed from the base member 113 and can have any shape so that the teaching person can easily perform the work. In the first embodiment, no drive source such as an actuator or a battery is included, the gripping members 111 and 112 are screwed to the base member 113, so that a configuration can be assembled and changed, and a gripping state can be realized.A marking 116 is fastened to the base body 113. The mark 116 is measured by the measurement unit 22 or the measurement unit 32 to measure a position / posture of the first end effector 11. In the embodiment, an example will be described in which a marking plate is used on which reflection balls 116 ato 116 dwhich reflect infrared light are mounted as the markings 116.Here, for example, when the work that causes the first end effector 11 to enter a target device is taught in the first end effector use teaching process 2, the markers 116 may not be normally measured by the measurement unit 22 probably due to occlusion (which is a state in which an object is occluded at the rear by an object at the front and is invisible).Accordingly, a mark fixing member 115 is provided between the marks 116 and the base member 113, so that the occlusion is prevented and the marks 116 can be measured satisfactorily by the measurement unit 22. The marker fixing member 115 is configured to prevent occlusion. For example, the mark fixing member 115 has a Z shape or the like.The position / attitude fixing tool 13 includes a grip member 131 and fixing tool marks 133. In the present embodiment, an example in which a marking plate on which reflection balls 133 ato 133 dwhich reflect infrared light are mounted as the markings 133 will be described. The position / posture fixing tool 13 may be a single independent member or a member protruding as a part of the work object.The gripping member 131 has attachable portions 132 (an attachable portion corresponding to the attachment portion 1112 is not illustrated) that are attached in the attachment portion 1112 of the gripping member 111 and the attachment portion 1122 of the gripping member 112.FIG. 2B is a diagram illustrating the first relative position / relative posture calculation process according to the first embodiment. In the first relative position / relative position calculation process 3, the positions / positions of the markers 116 and 133 using a work table coordinate system 37 Σw attached to the work table 35 as a reference are detected by installing the measurement unit 32, which is a measurement camera, at a position where the entire work table 35 can be inspected by a measurement unit column 321 and optically detecting the light reflected from the markers 116 and 133.It is assumed that a measurement unit of the marks 116 and 133 is a motion detection optical system in this embodiment. The positions / postures of the marks 116 and 133 are calculated by irradiating infrared light from the measurement unit 32 which is a measurement camera and using the infrared light reflected by the reflection balls 116 ato 116 dand 133 ato 133 dand an arrangement pattern of the reflection balls.A position / posture of the first end effector 11 is expressed in a first end effector coordinate system 117Σ 1 attached to the mark 116.A position / posture of the position / posture fixation tool 13 is expressed by a fixation tool coordinate system 134Σ 1 attached to the fixation tool mark 133.The measurement unit 32 acquires a homogeneous transformation matrix wT 1 representing a position / posture of the first end effector coordinate system 117Σ 1 in which the work table coordinate system 37Σw is a reference and a homogeneous transformation matrix wTt representing a position / posture of the fixation tool coordinate system 134Σt in which the work table coordinate system 37Σw is a reference, and calculates a homogeneous transformation matrix 1Tt as the first relative position / posture 310 by a formula 1Tt=(wT 1) -1 ·ΣwTt from the two homogeneous transformation matrices. In the embodiment, a corner of the work table 35 is set as the work table coordinate system 37Σw, but any method may be used to adopt the work table coordinate system 37Σw.The first end effector 11 in the first relative position / relative posture calculation process 3 may be carried by the worker 33, or may be individually placed independently thereof.In the embodiment, the first relative position / posture 310 is calculated by the first relative position / posture calculation process 3, but the first relative position / posture 310 may be a numerical value set in advance on the basis of design data.FIG. 3A is a diagram illustrating a detailed configuration of the second end effector and the position / posture fixing tool according to the first embodiment.The second end effector 12 includes, as a grip structure, a base member 123 in which a position / posture is measured, and a pair of grip members 121 and 122 that are mounted on the base member 123 and clamp the position / posture fixing tool 13 and the work object. The gripping members 121 and 122 of the second end effector 12 include contact surfaces 1211 (a contact surface of the gripping member 122 is not illustrated) and fastening portions 1212 and 1222, respectively.The gripping members 121 and 122 may operate in opposite opening and closing directions 120.The second end effector 12 performs a gripping operation by clamping the work object by the gripping members 121 and 122, and the base member 123 is fixed to each robot.The second end effector 12 includes an actuator for electric or fluid pressure operation driven by a signal from the robot or an external controller, and a power transmission mechanism that transmits the force of the actuator to the gripping member 121 and / or 122.The gripping member 131 shown in FIG. 3A is the same as the gripping member 131 shown in FIG. 2A, and in the attachment portion 1212 of the gripping member 121 and the attachment portion 1222 of the gripping member 122, attachment portions 132 are attached (an attachment portion corresponding to the attachment portion 1212 is not illustrated).The attachment portions 1112 and 1122 of the first end effector 11 and the attachment portions 1212 and 1222 of the second end effector 12 need to have the same shape and dimensions in order for the attachable portions 132 of the position / posture fixing tool 13 to be attachable.Meanwhile, other shapes (the lengths and sizes of the gripping members 111 and 112 and the length and size of the base member 113) may be different from the fastening portions.The position / posture fixation tool 13 is inserted by the gripping members 111 and 112 such that the attachable portions 132 are attached to the attachment portions 1112 and 1122 in the first relative position / posture calculation process 3, and thus a position / posture with respect to the first end effector 11 is geographically limited and uniquely determined.The position / posture fixation tool 13 is inserted by the gripping members 121 and 122 such that the attachable portions 132 are attached to the attachment portions 1212 and 1222 in the second relative position / posture calculation process 4, and thus a position / posture with respect to the second end effector 12 is geographically limited and uniquely determined.FIG. 3B is a diagram illustrating the second relative position / relative posture calculation process according to the first embodiment. In the second relative position / relative position calculation process 4, the positions / positions of the markers 126 and 133 in which a work table coordinate system 47 Σw attached to the work table 45 is used as a reference are detected by installing the measurement unit 42, which is a measurement camera, at a position where the entire work table 45 can be inspected by a measurement unit column 421 and optically detecting the light reflected from the markers 126 and 133.A measurement unit of the mark 126 is similar to the marks 116 and 133 described above, and detects a position / posture using reflection balls (not represented by a reference sign) provided on the mark 126.According to the embodiment, a position / position of the second end effector 12 is determined in a second end effector coordinate system 127Σ2fixed to the marking 126.The measurement unit 42 acquires a homogeneous transformation matrix wT 2 representing a position / posture of the second end effector coordinate system 127Σ 2 in which the work table coordinate system 47Σw is a reference and a homogeneous transformation matrix wTt representing a position / posture of the fastening tool coordinate system 134Σt in which the work table coordinate system 47Σw is a reference, and calculates a homogeneous transformation matrix 2Tt as the second relative position / posture 410 by a formula 2Tt=(wT 2) -1 ·ΣwTt from the two homogeneous transformation matrices. In the embodiment, a corner of the work table 45 is set as the work table coordinate system 47Σw, but any method may be used to adopt the work table coordinate system 47Σw.The second end effector 12 may be supported by the robot 43 in the second relative position / relative position calculation process 4 as illustrated in FIG. 3B, or may be set up individually independently of the robot.In the embodiment, the second relative position / posture 410 is calculated by the second relative position / posture calculation process 4, but the second relative position / posture 410 may be a numerical value set in advance on the basis of design data.A position / posture of the second end effector 12 in the second relative position / posture calculation process 4 is measured by the measurement unit 42 as a position / posture of the marker 126 attached to a marker fixing member 125 as described above. Note that the position / posture of the second end effector 12 can be acquired as a solution of kinematic calculation using design parameters and joint angle information of the robot 43 without using the position / posture of the marker 126. In this case, in order to improve learning accuracy, it is necessary to know a position / posture of a coordinate system Σr (not illustrated) fixed to the robot 43 and viewed from the work table coordinate system 47 Σw.In the measurement units 32 and 42, in the calculation of the first relative position / posture 310 and the second relative position / posture 410, only one pair of pieces of position / posture information measured under an arbitrary condition at an arbitrary time point may be used for calculation, or at least two or more pairs of pieces of position / posture information may be measured, the first relative position / posture 310 and the second relative position / posture 410 may be calculated for each pair, and an average of the first relative position / posture 310 and the second relative position / posture 410 may be taken. If the outputs of the measuring units 32 and 42 are noisy, averages can be taken at a plurality of points to obtain a more accurate measurement result.FIG. 4 is a diagram illustrating an operation of a learning data transformation unit according to the first embodiment. FIG. 5A is a diagram illustrating the first end effector use learning process according to the first embodiment. Specifically, FIG. 5A illustrates an aspect in which the teaching person 23 learns a work including a gripping state of the work object 24 using the first end effector 11 in the first end effector use teaching process 2. In FIG. 5A, the work for putting the work object 24 into a work environment structure 26 on the work table 25 is exemplified as an example of the work.In the example of FIG. 5A, the mark 116 attached to the first end effector 11 held by the teaching person 23 is measured by the measurement unit 22 for each given period of time, and the first end effector use teaching unit 21 generates a position / posture of the first end effector coordinate system 117Σ 1 fixed to the mark 116 as the first teaching data 210 and measurement time. The position / posture of the first end effector coordinate system 117Σ 1 fixed to the mark 116 is a position / posture at which a work table coordinate system 27Σw fixed to the work table 25 is a reference, and is expressed with the homogeneous transformation matrix wT 1.As described above, even when a state (occlusion) in which the first end effector 11 and the work object 24 for the measurement unit 22 are occluded by a shadow of the work environment structure 26 is assumed, the measurement unit 22 can measure the markers 116 by configuring the marker fixing member 115 such that the markers 116 are within a measurement range of the measurement unit 22.As illustrated in FIG. 4, the teaching data transformation unit 6 transforms the first teaching data 210 representing the position / posture of the first end effector 11 generated by the first end effector use teaching unit 21 into the second teaching data 510 representing the position / posture of the second end effector 12 using the first relative position / posture 310 calculated by the first relative position / posture calculation unit 31 and the second relative position / posture 410 calculated by the second relative position / posture calculation unit 41, and transmits the transformed second teaching data 510 to the robot control unit 51.The learning data transformation unit 6 includes, for example, a first coordinate transformation unit 61 and a second coordinate transformation unit 62. the first coordinate transformation unit 61 transforms the homogeneous transformation matrix wT 1 at each measurement time point generated as the first learning data 210 into the homogeneous transformation matrix wTt (third learning data 610) representing a position / posture of the fixation tool coordinate system 134Σt using the homogeneous transformation matrix 1Tt representing the first relative position / posture 310 and the formula wTt=wT 1·1Tt.The second coordinate transformation unit 62 transforms the homogeneous transformation matrix wTt transformed as the third teaching data 610 into the homogeneous transformation matrix wT 2 (second teaching data 510) representing a position / posture of the second end effector 12 using the homogeneous transformation matrix 2Tt representing the second relative position / posture 410 and the formula wT 2=wTt·(2Tt)-1.FIG. 5B is a diagram illustrating an image of the coordinate transformation in the first coordinate transformation unit 61 shown on a work station according to the first embodiment. As illustrated in FIG. 5B, the first teaching data 210 is expressed by a trajectory of a plurality of teaching points (e.g., seven points at different times t 1 to t 7) seen from the workplace coordinate system 27Σw.As described above, all the teaching points of the first teaching data 210 are transformed into the homogeneous transformation matrix wTt (the third teaching data 610) representing the position / posture of the fixation tool coordinate system 134Σt seen from the work table coordinate system 27Σw by multiplying the homogeneous transformation matrix wT 1 representing the positions / postures of the teaching points (in FIG. 5B, the teaching points from t 1 to t 7) of the first teaching data 210 seen from the work table coordinate system 27Σw by the homogeneous transformation matrix 1Tt of the first relative position / posture 310 calculated in advance by the first relative position / relative posture calculation unit 31.FIG. 5C is a diagram illustrating an image of the coordinate transformation and a robot operation process in a second coordinate transformation unit illustrated on a work station according to the first embodiment. The work for setting the work object 54 into the work environment structure 56 on a work table 55 as in the first end effector use teaching process 2 is exemplified.As described above, all the teaching points of the third teaching data 610 are transformed into the homogeneous transformation matrix wT 2 (the second teaching data 510) representing the position / posture of the second end effector 12 as viewed from the work table coordinate system 57Σw by multiplying the homogeneous transformation matrix wTt representing positions / postures of the teaching points (in FIG. 5C representing teaching points from t 1 to t 7) of the third teaching data 610 as viewed from the work table coordinate system 57Σw by an inverse matrix of the homogeneous transformation matrix 2Tt of the second relative position / posture 410 calculated in advance by the second relative position / relative posture calculation unit 41.FIG. 6 is a diagram illustrating a robot control unit according to the first embodiment. In the robot operation process 5, the robot control unit 51 causes the robot 53 to operate based on the second teaching data 510. Specifically, the robot control unit 51 causes the robot 53 to reproduce a predetermined work including gripping of the work object 54 performed using the first end effector 11 by controlling the robot 53 such that the position / posture of the second end effector 12 included in the second teaching data 510 coincides with the position / posture of the second end effector 12 mounted on the robot 53.The robot control unit 51 includes, for example, a teaching data correction unit 511, an inverse kinematic calculation unit 512, and a robot operation instruction unit 513.The teaching data correction unit 511 transforms the second teaching data 510, which is position / posture information of the second end effector 12 in which the work table coordinate system 57 Σw is a reference, into position / posture information of the second end effector 12 in which a coordinate system Σr (not illustrated) fixed to the robot 53 is a reference.The inverse kinematic calculation unit 512 calculates an angle of a joint of the robot 53 as an inverse kinematic solution so that the second teaching data 510 is reproduced using the second teaching data 510 transformed by the teaching data correction unit 511 and the design parameters of the robot 53.The robot operation instruction unit 513 transmits an operation instruction 514 to the robot 53 based on a result of the inverse kinematic calculation unit 512. When the solution of the inverse kinematic calculation unit 512 cannot be obtained, an error code is output as a code indicating that execution is not possible.In the robot operation process 5 according to the first embodiment, the measurement unit 52 (the third measurement unit) measures the position / posture of the second end effector 12 at the time when the robot control unit 51 controls the robot 53 based on the second teaching data 510 as the actual operation data 520, and the second teaching data 510 is corrected so that the second teaching data 510 matches the actual operation data 520. For example, the teaching data correction unit 511 compares the position / posture of the second end effector 12 in the second teaching data 510 with the position / posture of the second end effector 12 in the actual operation data 520, recognizes a deviation in the position / posture, and calculates an offset for correcting the detected deviation in the position / posture. The second teaching data 510 is corrected so that the second teaching data 510 coincides with the actual operation data 520 by adding the offset to the position / posture (the transformed second teaching data 510) of the second end effector 12 with the coordinate system Σr (not illustrated) fixed to the robot 53 being a reference.Instead of performing the correction by the measurement unit 52, the second learning data 510 may be corrected by a solution of kinematic calculation in which the design parameters and the joint angle information of the robot 53 are used as a true value. In this case, in order to improve the accuracy of the taught predetermined work, it is necessary to know the position / posture of the coordinate system Σr (not illustrated) fixed to the robot 53 and viewed from the work table coordinate system 57 Σw, and it is necessary that the design parameters and the joint angle information of the robot 53 are very accurate.In the embodiment, the measurement units 22, 32, 42, and 52 are described as different units, but may be the same unit.The robot 53 in the robot operation process 5 may be the same robot as or a different robot from the robot 43 in the second relative position / relative position calculation process 4.When the robot control unit 51 controls the robot 53 in accordance with the first teaching data 210 representing the position / posture of the first end effector coordinate system 117Σ 1, the robot control unit 51 controls the robot 53 such that the second end effector coordinate system 127Σ 2 illustrated in FIG. 3B follows the position / posture of the first end effector coordinate system 117Σ 1 illustrated in FIG. 2B. In this case, for example, when the relative positions / relative postures of the gripping members 111 and 112 to the base member 113 (the first end effector coordinate system 117Σ 1) are different from the relative positions / postures of the gripping members 121 and 122 to the base member 123 (the second end effector coordinate system 127Σ 2), that is, when there is a device difference or the like between the first end effector 11 and the second end effector 12, the gripping members 121 and 122 of the second end effector 12 cannot accurately track the positions / relative postures of the gripping members 111 and 112 of the first end effector 11 even when the second end effector coordinate system 127Σ 2 accurately tracks the position / posture of the first end effector coordinate system 117Σ 1.In the first relative position / relative posture calculation process 3 according to the embodiment, the relative positions / postures of the gripping members 111 and 112 to the position / posture fixation tool 13 are uniquely determined, and therefore, an accurate position / posture (tool center point) of the gripping structure is actually determined by the fixation tool coordinate system 134Σt. Therefore, in the embodiment, a relative position / posture between the first end effector coordinate system 117Σ 1 and the fixation tool coordinate system 134Σt is calculated as the first relative position / posture 310.In the second relative position / relative posture calculation process 4 according to the embodiment, the relative positions / postures of the gripping members 121 and 122 to the position / posture fixation tool 13 are uniquely determined, and therefore, an accurate position / posture (tool center point) of the gripping structure is actually determined from the fixation tool coordinate system 134Σt. Therefore, in the embodiment, a relative position / posture between the second end effector coordinate system 127Σ2and the fixation tool coordinate system 134Σt is calculated as the second relative position / posture 410.By transforming the first teaching data 210 into the second teaching data 510 using the first relative position / posture 310 and the second relative position / posture 410, the taught predetermined work is reproduced with high accuracy even if there is a device difference or the like between the first end effector 11 and the second end effector 12.In the foregoing example, the example has been described in which the positions / postures of the marks 116, 126, and 133 are measured by the above-described optical motion detection system. However, a motion detection system that magnetically detects the motion of a gripped work object by a Hall element or the like may be used instead. Alternatively, a system may be adopted in which the mark is not used, but the movement of a work object or the teaching person 23 is captured with a camera and the image is analyzed.The positions / postures (tool centers) of the gripping members 111 and 112 can be calculated from the first end effector coordinate system 117Σ 1 and the design data. However, since there are dimensional errors or assembly errors in the mark fixing member 115, the base member 113, and the gripping members 111 and 112, it is difficult to calculate the positions / postures (tool centers) of the gripping members 111 and 112 with high accuracy in some cases. In these cases, according to the embodiment, since the positions / postures of the gripping members 111 and 112 are determined from the position / posture of the position / posture fixing tool 13 based on the actual measurement, it is less likely to be affected by the above errors.It is also considered that the second end effector mounted on the robot is detached and used as it is for teaching, but there is a case where the second end effector mounted on the robot cannot be easily handled due to a size, a weight, or the like. In this case, there is no choice other than using the first end effector having a device difference or the like with respect to the second end effector. Thus, according to the present invention, since there is no problem even if a device difference or the like is present between the first end effector and the second end effector, the teaching can be performed regardless of a size or weight of the second end effector. Accordingly, the robot teaching system according to the present invention can be used more generally.A configuration of a robot teaching system 1 according to a second embodiment of the present invention will be described. In the present embodiment, differences from the first embodiment will be mainly described, and configurations, the description of which is omitted, are similar to those of the first embodiment.FIG. 7A is a diagram illustrating a configuration and an operation of a learning data transformation unit according to the second embodiment. The robot teaching system 1 according to the second embodiment includes at least two first end effectors 11 and at least two second end effectors 12. In the present embodiment, in which reference numerals are formed of numerals and letters, the numerals correspond to the reference numerals of the first embodiment, and the letters of the alphabet indicate which end effector is going. For example, a first end effector use learning unit 21 aillustrated in FIG. 7A corresponds to the first end effector use learning unit 21 in the first embodiment, and illustrates that it is the first end effector 11 aaccording to the present embodiment.The first end effectors 11 aand 11 band the second end effectors 12 aand 12 binclude all gripping members in which a fastening portion fastened into the fastening portion 132 of the position / posture fixing tool 13 is provided as in the first embodiment. Here, the dimensions and driving schemes are not limited.FIG. 7A illustrates an example in which the robot 53 to which the second end effector 12 bis mounted is operated on the basis of first teaching data 210 agenerated by the teaching using the first end effector 11 a.The learning data transformation unit 6 further includes a first relative position / relative position storage unit 63, a second relative position / relative position storage unit 64, and a learning data storage unit 65, in addition to the first coordinate transformation unit 61 and the second coordinate transformation unit 62.The first relative position / relative position storage unit 63 stores position / position information of the first end effector 11 agenerated by the first relative position / relative position calculation process 3 in which the first end effector 11 ais used in conjunction with an identifier (first identifier) for identifying information regarding the first end effector 11 aas the first relative position / position 310 a, and stores position / position information of the first end effector 11 bgenerated by the first relative position / relative position calculation process 3 in which the first end effector 11 bis used in conjunction with an identifier (first identifier) for identifying information regarding the first end effector 11 bas the first relative position / position 310 b.The second relative position / relative position storage unit 64 stores position / position information of the second end effector 12 agenerated by the second relative position / relative position calculation process 4 in which the second end effector 12 ais used in conjunction with an identifier (second identifier) for identifying information regarding the second end effector 12 aas the second relative position / position 410 a, and stores position / position information of the second end effector 12 bgenerated by the second relative position / relative position calculation process 4 in which the second end effector 12 bis used in conjunction with an identifier (second identifier) for identifying information regarding the second end effector 12 bas the second relative position / position 410 b.The first end effector use learning unit 21 agenerates first learning data 210 aincluding the position / posture information of the first end effector 11 aduring a learning operation by the first end effector use learning process 2 in which the first end effector 11 ais used and the identifier for identifying the information regarding the first end effector 11 a.When the first teaching data 210 aare input, the first coordinate transformation unit 61 generates third teaching data 610 aby using the identifier included in the first teaching data 210 aand referring to the first relative position / posture 310 acorresponding to the identifier from the first relative position / posture storage unit 63 and stores the third teaching data 610 ain the teaching data storage unit 65.Similarly, a first end effector use learning unit 21 b(not illustrated) generates first learning data 210 bthrough the first end effector use learning process 2 in which the first end effector 11 bis used. When the first teaching data 210 bis input, the first coordinate transformation unit 61 generates third teaching data 610 busing the identifier included in the first teaching data 210 band with reference to the first relative position / posture 310 bcorresponding to the identifier from the first relative position / posture storage unit 63 and stores the third teaching data 610 bin the teaching data storage unit 65.The learning data storage unit 65 stores the third learning data 610 aand the third learning data 610 b.The second coordinate transformation unit 62 receives, from a robot control unit 51 b, robot control condition data 515 bincluding information indicating which second end effector is to be controlled (e.g., an identifier of the second end effector 12 b) and information indicating which teaching data is to be reproduced (e.g., the third teaching data 610 aare reproduced), and generates second teaching data 510 bwith respect to the second relative position / posture 410 bcorresponding to the corresponding identifier from the second relative position / posture search unit 64 and the corresponding third teaching data 610 afrom the teaching data storage unit 65.Here, the learning data storage unit 65 may store the first learning data 210 and / or the second learning data 510 and / or the third learning data 610, and the data is treated as learning data information suitable for transformation or inverse transformation in accordance with the corresponding first relative position / posture 310 and second relative position / posture 410. FIG. 7B shows, for example, another example of the configuration of the learning data transformation unit according to the second embodiment. In this case, the learning data storage unit 65 stores the first learning data 210 aand the first learning data 210 b. The first coordinate transformation unit 61 refers to the corresponding first teaching data 210 afrom the teaching data storage unit 65 based on the robot control condition data 515 b(in the embodiment, the first teaching data 210 ais reproduced).FIG. 7C illustrates another example of the configuration of the learning data transformation unit according to the second embodiment. The learning data storage unit 65 stores the second learning data 510 aand the second learning data 510 b. The robot control unit 51 brefers to the corresponding second teaching data 510 bfrom the teaching data storage unit 65 on the basis of the robot control condition data 515 b(in the present embodiment, the robot 53 to which the second end effector 12 bis mounted is caused to reproduce the second teaching data 510 b).According to the present embodiment, even if arbitrary first teaching data 210 is selected from the plurality of pieces of first teaching data 210 generated using the various first end effectors 11, the taught predetermined work is reproduced with high accuracy, and the robot is caused to reproduce the first teaching data.A third embodiment is a modified example of the first and second embodiments. FIG. 8 is a diagram illustrating the first end effector according to the third embodiment. In the present embodiment, differences from the first and second embodiments will be mainly described, and the configurations, the description of which is omitted, are similar to those of the first and second embodiments.The first end effector 11 according to the third embodiment is a tool manufactured by modeling the second end effector 12, is not mounted on the robot, and is held and handled by a worker.The first end effector 11 includes a first end effector operation unit 118 and a force transmission unit 119 that transmits an operation force supplied to the first end effector operation unit 118 and operates the gripping members 111 and 112 in the opening and closing direction 110.The first end effector operation unit 118, which serves as a pressure switch, for example, includes a battery and an actuator (not illustrated) inside the first end effector 11 and detects a pressure of the first end effector operation unit 118 by an electric signal to drive the power transmission unit 119. The first end effector operation unit 118 is not limited thereto. For example, a rotational force added to a lever may be transmitted with a transmission through the lever to drive the power transmission unit 119 without the battery or the actuator being included within the first end effector 11.In the above configuration, the weight of the first end effector 11 may be less than that of the second end effector 12 actually connected to the robot 53, and a work object gripping operation may be taught at a desired timing by the teaching person 23 in the first end effector use teaching process 2. Therefore, it is possible to provide the robot teaching system capable of performing the teaching more easily.A fourth embodiment is a modified example of the first and second embodiments. FIG. 9 is a diagram illustrating a first end effector use learning process according to the fourth embodiment. In the present embodiment, differences from the first and second embodiments will be mainly described, and the configurations, the description of which is omitted, are similar to those of the first and second embodiments.The first end effector 11 baccording to the fourth embodiment is an end effector connectable to the robot, and may be an end effector the same as one of the second end effectors 12. The first end effector 11 bis mounted on a teaching robot 28 and can operate the gripping members 111 band 112 bby driving the included actuator in accordance with an external signal.The teaching person 23 operates the teaching robot 28 by using the robot operation unit 29 in the first end effector use teaching process 2. at this time, the position / posture of the first end effector 11 bis calculated by the first end effector use teaching unit 21 b, and the first teaching data 210 bis generated.A position / posture of the first end effector 11 bserving as the first teaching data 210 bmay be acquired as a solution of kinematic calculation using joint angle information and a design parameter of the teaching robot 28, or a mark 116 b(not illustrated) attached to the first end effector 11 bmay be measured by the measurement unit 22.In the above configuration, robots whose end effectors have a common gripping structure can share teaching data although the robots are different robots.List of reference characters1 Robot teaching system 11 First end effector 111, 112 Gripping member 1111 Contact surface 1112, 1122 Fixing portion 113 Base member 114 Gripping member 115 Mark fixing member 116 Mark 117Σ1First end effector coordinate system 118 First end effector operation unit 119 Force transmission unit 110 Opening and closing direction 12 Second end effector 121, 122 Gripping member 1211 Contact surface 1212, 1222 Attachment portion 123 Base member 125 Marker fixing member 126 Marker 127Σ2Second end effector coordinate system 120 Opening and closing direction 13 Position / posture fixing tool 131 Gripping member 132 Attachable portion 133 Fixing tool marker 134 Fixing tool coordinate system 2 First end effector use teaching process 21 First end effector use teaching unit 210 First teaching data 22 Measurement unit 23 Teaching person 24 Work object 25 Work table 26 Work environment structure 27Σw Work table coordinate system 28 Teaching robot 29 Robot operation unit 3 First relative position / relative posture calculation process 31 First relative position / relative posture calculation unit 310 First relative position / posture 32 Measurement unit 321 Measurement unit column 33 Worker 35 Work table 37Σw Work table coordinate system 4 Second Relative position / relative posture calculation process 41 Second relative position / relative posture calculation unit 410 Second relative position / posture 42 Measurement unit 421 Measurement unit column 43 Robot 45 Work table 47Σw Work table coordinate system 5 Robot operation process 51 Robot control unit 510 Second teaching data 511 Teaching data correction unit 512 Inverse kinematic calculation unit 513 Robot operation instruction unit 514 Operation instruction 515 Robot control state data 52 Measurement unit 520 Current operation data 53 Robot 54 Work object 55 Work table 56 Work environment structure 57Σw Work table coordinate system 6 Teaching data transformation unit 61 First coordinate transformation unit 610 Third teaching data 62 Second coordinate transformation unit 63 First relative position / relative posture storage unit 64 Second relative position / relative posture storage unit 65 learning data storage unit

Claims

A robot teaching system (1) comprising: a first end effector (11) having a gripping structure and used for teaching; a second end effector (12) having the gripping structure and mounted on a robot; a position / posture fixing tool (13) having a gripped structure in which a position and a posture with respect to the first end effector (11) and the second end effector (12) are uniquely determined by being gripped by the gripping structure of the first end effector (11) and the second end effector (12); a teaching data transformation unit (6) configured to transform first teaching data (210) representing position / posture information of the first end effector (11) during a teaching operation into second teaching data (510) representing position / posture information of the second end effector (12); and a robot control unit (51) configured to cause the robot (43) to operate based on the second teaching data (510), wherein the teaching data transformation unit (6) transforms the first teaching data (210) into the second teaching data (510) using a first relative position / posture indicating a relative position / posture between the first end effector (11) and the position / posture fixing tool (13) when the position / posture fixing tool (13) is gripped and a second relative position / posture indicating a relative position / posture between the second end effector (12) and the position / posture fixing tool (13) when the position / posture fixing tool is gripped.The robot teaching system (1) according to claim 1, further comprising: a first measurement unit (22, 32, 42, 52) configured to measure a position / posture of the first end effector (11) and a position / posture of the position / posture fixing tool (13) gripped by the first end effector (11); a second measurement unit (22, 32, 42, 52) configured to measure a position / posture of the second end effector (12) and a position / posture of the position / posture fixing tool (13) gripped by the second end effector (12), a first relative position / relative posture calculation unit (31) configured to calculate the first relative position / posture (310) based on the position / posture of the first end effector (11) and the position / posture of the position / posture fixing tool gripped by the first end effector; and a second relative position / relative position calculation unit (41) configured to calculate the second relative position / position (410) based on the position / position of the second end effector (12) and the position / position of the position / position fixing tool (13) gripped by the second end effector (12).The robot teaching system (1) according to claim 2, wherein each of the first end effector (11), the second end effector (12), and the position / posture fixing tool (13) has a mark (116, 126), and wherein the first measurement unit (22, 32, 42, 52) and the second measurement unit (22, 32, 42, 52) measure the position / posture of each of the first end effector (11), the second end effector (12), and the position / posture fixing tool (13) by measuring the mark (116, 126).The robot teaching system (1) according to claim 1, further comprising a first storage unit (63) configured to store the first relative position / posture, wherein the first end effector (11) comprises a first identifier that is an identifier of the first end effector, wherein the first storage unit (63) stores the first relative position / posture in association with the first identifier, wherein the first teaching data (210) comprises position / posture information of the first end effector (11) used for teaching and the first identifier of the first end effector (11) used for teaching, and wherein the teaching data transformation unit (6) stores the first teaching data (210) based on the first relative position / posture corresponding to the first identifier, which is contained in the first teaching data (210), is transformed into the second teaching data (510).The robot teaching system according to claim 1, further comprising: a second storage unit (64) configured to store the second relative position / posture, wherein the second end effector (12) comprises a second identifier that is an identifier of the second end effector (12), wherein the second storage unit (64) stores the second relative position / posture in association with the second identifier, and wherein the teaching data transformation unit (6) transforms the first teaching data (210) into the second teaching data (510) based on the second relative position / posture corresponding to the second identifier of the second end effector (12) mounted on the robot (53).The robot teaching system (1) according to claim 1, further comprising: a teaching robot (28); and an operation unit (29) configured to operate the teaching robot (28), wherein the first end effector (11) is mounted on the teaching robot (28).The robot teaching system (1) according to claim 1, wherein the teaching data transformation unit (6) transforms the first teaching data (210) into third teaching data (610) representing a position / posture of the position / posture fixation tool (13) using the first relative position / posture, and transforms the third teaching data (610) into the second teaching data (510) using the second relative position / posture.The robot teaching system (1) according to claim 1, further comprising: a third measurement unit (22, 32, 42, 52) configured to measure a position / posture of the second end effector (12) when the robot control unit (51) controls the robot (53) based on the second teaching data (510) as actual operation data (520), wherein the robot control unit (51) corrects the second teaching data (510) such that the second teaching data (510) coincides with the actual operation data (520).The robot teaching system (1) according to claim 1, wherein each of the first end effector (11) and the second end effector (12) comprises, as the gripping structure, a base member (113) from which a position / posture is measured, and a pair of gripping members (111, 112) mounted on the base member (113) and gripping the position / posture fixing tool (13) and a work object (24), wherein the pair of gripping members (111, 112) have contact surfaces (1211, 1212) with which the position / posture fixing tool (13) and the work object (24) come into contact, and fastening portions (1112, 1122) provided on the contact surfaces (1211, 1212), and wherein the position / posture fixing tool (13) has fixable portions that are capable of being fastened into the fastening portions (1112, 1122) of the pair of gripping elements (111, 112) are fixed as at least parts of the gripped structure.The robot teaching system (1) according to claim 9, wherein the base member (113) of the first end effector (11) includes an operation unit (118) operated by a teaching person and a power transmission unit (119) that transmits the operation force applied to the operation unit (118) and operates the gripping member (111, 112) such that the operation unit (118) is locked to the gripping member (111, 112).

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