Robot system with a robot carried on a movable carriage

Abstract

A robot system comprising a robot (1) that performs a predetermined operation; a carriage (5) that supports the robot (1) and moves under the operation of a worker (9); an optical sensor (41) fixed to a wrist portion (13) of the robot (1); a first marker (46a) and a second marker (46b) provided at a work location where the carriage (5) is placed when the robot (1) performs the operation; a control device (2) having a computational processing device that processes the information obtained by the optical sensor (41) and controls the operation of the robot (1); and a display (31) that displays the result processed by the computational processing device.to move the optical sensor (41) to the position for capturing an image of the second mark (46b), and to capture an image of the second mark (46b) after the optical sensor (41) has captured an image of the first mark (46a) in a state in which the carriage (5) has been moved to the work site, the arithmetic processing device comprises a position acquisition unit (23) that acquires positions of the first mark (46a) and the second mark (46b) based on images captured by the optical sensor (41), and a judgment unit (24) that judges whether or not the robot (1) is located at a position within a predetermined judgment area based on the positions of the first mark (46a) and the second mark (46b) acquired by the position acquisition unit (23), wherein the judgment unit (24), upon judging that the position of the robot (1) deviates from the judgment area,the direction in which the carriage (5) is to be moved and the extent of movement for the robot (1) to reach a target position are calculated, and the display (31) shows the direction in which the carriage (5) is to be moved and the extent of movement.

Description

The present invention relates to a robot system having a robot supported on a movable stand truck.In the related art, robot systems are known that increase the working range of a robot by arranging the robot on a running carriage and moving the running carriage. For example, it is known that a traveling truck to which a robot is fixed travels on rails laid on the ground. Although it is possible to position a running carriage with high accuracy, a special facility such as rails required for running is required. Since the equipment cannot be easily changed after installation, there is a disadvantage that changes of a production process and a production process or the like cannot be easily coped with.On the other hand, there is known an apparatus in which a robot is placed on a carriage moving in arbitrary directions and the robot is moved up to the work area. In this apparatus, since the robot is disposed on a carriage, there is a problem that the positioning accuracy of the robot is not secured in association with the movement of the carriage. In this apparatus, positional deviations of the carriage are measured using a camera or a force sensor. The operation of the robot is corrected according to the amount of deviation from a certain position. By correcting by calculation of a teaching position of the robot, the robot can perform a correct operation even when the rack car deviates from the determined position.JP 5061965 B2 describes a robot production system having: a variably disposed first work table having a transport robot disposed thereon; a camera which is positional deviation detecting means for detecting positional deviation from a prescribed position of the first work table when the first work table is set; and a controller which is positional deviation correcting means for correcting instructed data which is a reference of movement of the transport robot based on a detection result by the camera.JP-H-11-058273 A relates to a visual sensor installed at an arm head end part of a multiaxial robot loaded on a movable slide. The markings are provided on a workbench and an auxiliary marking is provided on the movable carriage. The slip amount of the stop position of the visual sensor is determined in accordance with the slip amount of a stop time position and a learning time position of the assist mark. As a result, a handling position against a workpiece is corrected in accordance with these position slip amount and rotational slip amount.In the patent document JP 4820395 B2 a system is disclosed in which a two-armed robot can correct its working position by its own force when the position of the action which the two-armed robot performs has moved. In this system, automatic regulation of the position of the carriage is disclosed.As for optical sensors, in Japanese Patent Laid-Open No. 2004-138462, a three-dimensional optical sensor is disclosed that accurately measures the three-dimensional position and posture of a workpiece even when the position and posture of the workpiece are changed. In JP 2602812 B2, a system is disclosed in which a first mark, a second mark and a third mark are picked up by three optical sensors mounted on a carriage, and the three-dimensional position and posture of an object is calculated.In a robot system provided with a rack car, in the method that corrects the teaching position of the robot by calculation, it may occur that the robot cannot perform its operation. For example, there are cases where the robot opens a door of a machine tool and performs the operation inside a machining chamber. It is necessary for the robot to insert its arm into the processing chamber through a narrow opening portion and perform the operation. However, when the position of the cradle truck that carries the robot is not appropriate, the robot may collide with the machine tool despite correction of the teaching position of the robot. Therefore, even in a rack car which does not have an accurate positioning mechanism, it is favorable to regulate the position of the rack car with a certain accuracy.When the position of a rack car is determined by a worker, a method is conceivable in which a mark is disposed in the area where the rack car is disposed and the position of the rack car is determined to match the mark. Or a method is also conceivable in which the position of the rack car is determined by setting up a setting device or the like against which the rack car is pushed. However, the appropriate position for the posture of the trolley changes depending on the length of the arm of the robot, the workpiece on which the operation is performed, and the like. Therefore, in a system to be suitable for many kinds of products, it is necessary to prepare many marks or many setting devices. In addition, there is a problem that the worker needs to arrange the rack car after familiarizing with the structure of the robot system.In the apparatus disclosed in the above-mentioned patent JP 4820395 B2, the cradle truck can be placed at a desired position. However, since special devices such as a driving device that moves the rack car and a mechanism that the robot grasps, and the like are required, there is a problem that the structure of the robot system becomes complicated.DE 11 2011 101 730 B4 relates to a calibration system for calibrating an image processing system and a robot in a manner coordinated with one another. This is done by means of a calibration object which the end effector of the robot carries and by means of camera images which the image processing system processes and evaluates. A similar calibration system is known, for example, from U.S. Pat. No. 2016 / 0 039 094 A1.U.S. Pat. No. 6,041,274 A discloses a position recognition unit which is configured to detect a position deviation of a mobile body on which a robot is arranged in a stop position. For this purpose, a sensor on the mobile body recognizes an image on a ground in order to determine its position. A position correction of the mobile body is carried out on the basis of the sensor data, if necessary.Further devices for position determination and position correction of a robot arranged on a movable carriage are known, for example, from JP 2010-162 635 A, JP 2001 252 883 A and JP H11-156 764 A.It is an object of the present invention to provide a robot system with a frame carriage which can move with the aid of optical sensors and markings and can overcome or at least minimize the above-mentioned disadvantages.The robot system of the present invention includes a robot that performs a predetermined operation and a rack car that carries the robot and moves by an operation by a worker. The robot system includes an optical sensor fixed to a wrist portion of the robot or the cradle truck, and a mark disposed at a work site where the cradle truck is placed in performing the operation by the robot. The robot system includes a computation processing device that processes the information obtained by the optical sensor and a display that displays the result processed by the computation processing device. The calculation processing device includes a position acquisition unit that acquires the position of the mark on the basis of the image captured by the optical sensor in a state in which the rack car has been moved to the work location. The calculation processing device includes a judgment unit that judges whether or not the robot is disposed at a position in a predetermined judgment range based on the position of the mark acquired by the position acquisition unit. The judging unit, upon judging that the position of the robot deviates from the judging range, calculates the direction in which the carriage is to be moved and the amount of movement for the robot to reach a target position. The display displays the direction in which the carriage is to be moved and the amount of movement.In the invention described above, the relationship between the position of the robot and the image of the mark for the optical sensor acquired by the optical sensor may be calibrated in advance. The position acquisition unit may calculate the position of the mark by processing the image of the mark whose positional relationship with the work location is set in advance.In the above-described invention, the judgment unit may calculate the distance between the actual position of the mark and the target position of the mark in a plurality of predetermined directions based on the position of the mark acquired by the position acquisition unit. The judging unit may judge whether or not the distance is within the judging range for the respective directions.In the invention described above, the display may update the display image based on the result by the judgment unit so that the worker can regulate the position of the rack car while watching the display.Another robot system of the present invention includes a robot that performs a predetermined operation and a rack car that carries the robot and moves by an operation by a worker. The robot system includes an optical sensor disposed at a work site where the cradle cart is disposed in performing the operation by the robot, and a mark disposed at a wrist portion of the robot or at the cradle cart. The robot system includes a computation processing device that processes the information obtained by the optical sensor and a display that displays the result processed by the computation processing device. The calculation processing device includes a position acquisition unit that acquires the position of a mark on the basis of the image captured by the optical sensor in a state in which the rack car has been moved to the work site. The calculation processing device includes a judgment unit that judges whether or not the robot is disposed at a position in a predetermined judgment range based on the position of the mark acquired by the position acquisition unit. The judging unit, upon judging that the position of the robot deviates from the judging range, calculates the direction in which the carriage is to be moved and the amount of movement for the robot to reach a target position. The display displays the direction in which the carriage is to be moved and the amount of movement. FIG. 1 is an oblique view of a first robot system according to an embodiment. FIG. 2 is an enlarged oblique view of the region of a camera and a marking of the first robot system. FIG. 3 is a block diagram of a robot system according to the embodiment. FIG. 4 is a flow chart of the work for determining the position of the rack car. FIG. 5 is a display image of the display when the work for determining the position of the rack car is not completed. FIG. 6 is a display image of the display when the work for determining the position of the rack car is completed. FIG. 7 is a flowchart of control by a control device according to the embodiment. FIG. 8 is an oblique view of a second robot system according to the embodiment. FIG. 9 is an oblique view of a third robot system according to the embodiment.Referring to FIGS. 1 to 9, robot systems according to embodiments will be explained. The robot systems include a robot, the robot being a device that performs a certain operation. In the robot systems of the present embodiments, the robot is fixed to a rack car moving in arbitrary directions. A worker can change the position of the robot by moving the cradle truck.FIG. 1 is an oblique view of a first robot system according to an embodiment. The robot system 91 of the present embodiment includes a robot 1. the robot 1 of the present embodiment is a multi-articulated robot including a plurality of arms 111 and a plurality of joints 12. To the tip end of the arm 11 is connected a wrist portion 13. The robot 1 can freely change the position and posture of the wrist portion 13. A hand 3 as an end effector is fixed to the wrist portion 13. The hand 3 is formed so as to be able to grasp and release a workpiece. The end effector is not limited to one hand; any device may be used depending on the content of the work. The robot 1 can place a workpiece gripped by the hand 4 at a desired position and posture. In addition, the robot has a weight-bearing capacity and a working area within which it can grasp and transport a workpiece.The robot system 91 of the present embodiment performs operations with respect to a machine tool 6. The machine tool 6 includes a frame body 64. the machine tool 6 includes a door 63 disposed in the frame body 64. The door 63 is formed to open and close. In a machining chamber surrounded by the frame body 64, a main shaft head 62 holding a tool and a table 61 supporting a workpiece are disposed. During the period of machining the workpiece, the relative position of the tool with respect to the workpiece changes by moving at least one of the main shaft head 62 and the table 61.The robot 1 performs a predetermined operation. The robot 1 of the present embodiment arranges workpieces on the table 61 before machining and takes workpieces after machining from the table 61. The robot 1 can perform the operation inside the processing chamber by inserting the arm 11 through the opening portion into the processing chamber.The robot system 1 comprises a frame carriage 5 which carries the robot 1. The rack car 5 of the present embodiment is formed to travel on the ground. The rack car 5 includes a frame body 51 and wheels 52 mounted on the frame body 51. the rack car 5 includes an upper plate 53 disposed on the frame body 51 and a handle 54 fixed to the frame body 51. That is, the worker can move the robot to a desired position. In the example shown in FIG. 1, the front side of the door 63 of the machine tool 6 represents the work location where the robot 1 performs its operation. The worker 9 arranges the rack car 5 on the front side of the machine tool 6.The robot 1 is fixed to the upper plate 53. That is, the robot 1 is fixed to the cradle truck 5. The carriage 5 and the robot 1 move integrally. For the rack car, any structure that can carry the robot and moves by an operation of a worker may be employed. For example, the rack car may be formed to move by a motor, and the worker may move the rack car by operating a control panel.The cradle car 5 includes stoppers 55 for fixing the position. The stoppers 55 of the present embodiment have a function of preventing the rotation of the wheels 52. The wheels can be fixed by the stoppers 55. The worker 9 fixes the position of the rack car 5 by the stoppers 55 after the position of the rack car 5 is set. Thereafter, a desired operation can be performed by the robot 1. Any mechanism can be used as the device for fixing the chassis cart. For example, a locking device can also be arranged on the frame carriage.The robot system 91 includes a control device 2 that controls the robot 1. In the present embodiment, the control device 2 is supported on the carriage 5. The control device 2 moves integrally with the chassis cart 5. the robot system 91 includes a display 31 that displays results calculated by the control device 2 of the robot. The display 31 includes a display panel such as a liquid crystal panel or the like. The display 31 is disposed on the upper plate 53. Also, on the top plate 53, a start button 32 for starting the control for judging the position of the robot 1 is disposed.In FIG. 2, an enlarged oblique view of the region of the robot and the mark in the present embodiment is shown. Referring to FIGS. 1 and 2, the robot system 91 includes a camera 41 fixed to the wrist portion 13 of the robot 1 as an optical sensor. The camera 41 of the first robot system 91 is a two-dimensional camera.The robot system 91 includes markers 46 a, 46 bset at the work site where the rack car 5 is placed at the time of performing the operation by the robot 1. At the work site, a column member 45 is disposed. In the example shown in FIG. 1, two column members 45 spaced apart from each other are arranged. The marks 46 a, 46 bare disposed on the upper surface of the respective pillar members 45. The positional relationship of the markers 46 a, 46 bto the work location is set in advance.The markers 46 a, 46 bmay use any characters or characters whose shape can be recognized by image processing. As for the markers 46 a, 46 b, a graphic is preferable, whereby after processing the image captured by the camera 41, in addition to the position of the marker in the horizontal direction, the rotation angle about a perpendicular axis is also detectable. In the marks 46 a, 46 bin the present embodiment, two lines crossing each other are shown inside a circle.FIG. 3 is a block diagram of the robot system in the present embodiment. The control device 2 includes a computation processing device having a CPU (central processing unit), a RAM (random access memory), and a ROM (read only memory), and the like, which are connected to each other via a bus. As the calculation processing device, a computer may be used. The control device 2 includes a storage unit 21 that stores information related to the operation. As the storage unit 21, for example, a nonvolatile memory whose information is not lost even when the power supply is turned off may be used. The control device 2 includes an operation control unit 22 that controls the operation of the robot 1 and the hand 3. The operation control unit 22 also controls the operation of the camera 41.In the present embodiment, an operation program 27 for operating the robot 1, the hand 3, and the camera 41 is input to the control device 2 in advance. The operation program 27 is stored in the storage unit 21. The operation control unit 22 operates the robot 1, the hand 3, and the camera 41 according to the operation program 27. or a teaching console 26 is connected to the control device 2. The worker can set teaching points for the robot 1 through the teaching console 26. The teaching points are stored in the storage unit 21. The operation control unit 22 may operate the robot 1 to pass the teaching points.The control device 2 processes the information obtained by the optical sensor. The control device 2 includes a position acquisition unit 23 that acquires the positions of the markers 46 a, 46 bbased on the image captured by the camera 41. The position acquisition unit 23 includes an image processing unit 28 that processes the image captured by the camera 41. The worker moves the rack car 5 to the work site. The capturing of the marks 46 a, 46 bby the camera 41 is performed in a state in which the rack cart 5 has been moved to the vicinity of the target position at the work site. The control device 2 includes a judgment unit 24 that judges whether or not the robot 1 has been placed at a position within the predetermined judgment range based on the positions of the markers 46 a, 46 bacquired by the position acquisition unit 23. In addition, the control device 2 includes a display control unit 25 that controls the image represented by the display 31.The judgment unit 24 may judge that the position of the robot 1 has not arrived inside the judgment area. In this case, the judging unit 24 calculates the direction in which the carriage 5 is to be moved and the amount of movement for the robot 1 to reach the target position. The display control unit 25 sends a command for presenting the direction in which the rack car 5 is to be moved and the amount of movement to the display 31. The worker 5 can regulate the position of the trolley according to the information displayed on the display 31.FIG. 4 is a flowchart showing the operation performed by a worker in determining the position of the rack car. In step 101, the worker 9 moves the rack car 5 to the work site on the front side of the machine tool 6.In step 102, the worker 9 instructs the robot system 91 to start the judgment of the position of the robot 1. The worker presses the start button 32, the control device 2 starts the control for judging the position of the robot 1, In the present embodiment, the control for judging the position of the robot 1 is started by pressing the start button 32, but there is no limitation thereto, and the control for judging the position of the robot 1 may also be started by, for example, operating the teaching panel 26.Next, in step 103, the control device 2 judges whether or not the current position of the robot 1 is within the judgment range. Then, the control unit 2 displays the judgment result on the display 31.FIG. 5 shows an example of an image displayed on the display. FIG. 5 is the image when the position of the robot 1 deviates from the judgment range. On the display 13, it is displayed that the regulation of the position of the rack car 5 is not completed. On the display 31, the direction in which the rack car 5 is to be moved is indicated by an arrow. Also, on the display 31, the movement amount up to the target position is displayed.FIG. 6 shows another example of an image displayed on the display. FIG. 6 is an example of the illustration when the robot 1 is disposed at a position within the evaluation range. The display 31 shows that the regulation of the position of the rack car 5 is completed.Referring to FIG. 4, in step 104, the worker 9 acquires, from the display on the display 31, information as to whether or not the position of the robot 1 is within the judgment range. If the position of the robot 1 is not within the judgment range in step 104, the operation proceeds to step 105.In step 105, the worker 9 moves the rack car 5 according to the display shown in FIG. 5 on the display 31. Then, after the movement of the carriage 5, the operation returns to step 102. The worker 9 again presses the start button 32 after the movement of the carriage 5. the control device 2 again performs control for judging the position of the robot.In this way, the worker 9 can regulate the position of the rack car 5 as shown on the display 31. With each making judgment of the position of the robot 1, the control device 2 displays information regarding the position of the robot 1 on the display 31. The display 31 updates its display every time there is a result of the judgment by the control device 2.If the position of the robot 1 is within the judgment range in step 104, the operation proceeds to step 106. On the display 31, it is displayed that the regulation of the position is completed as illustrated in FIG. 6.In step 106, the worker 9 fixes the position of the rack car 5. the worker 9 prevents the wheels 52 from rotating by the stoppers 55. For example, the worker 9 starts the operation of the robot 1 by operating the teaching console 26. the robot 1 can place a workpiece on the table 61 of the machine tool 6 or remove a workpiece placed on the table 61 according to the operation program 27 set in advance.Preferably, after the position of the trolley is fixed by the worker 9, it is detected whether the positional relationship between the robot 1 and the machine tool 6 is correct using an image captured by the camera 41. The control device 2 can calculate deviations of the position of the robot 1 with respect to the machine tool 6 on the basis of the image of the markings 46 a, 46 bacquired by the camera 41. Then, the control device 2 can correct the operation of the robot 1. For example, the control device 2 may calculate a deviation amount of the position of the robot 1 and a deviation amount of revolutions, and correct the position and the posture when driving the robot 1.Next, the control for judging the position of the robot will be explained. FIG. 7 is a flowchart showing the control for judging the position of the robot. Fig. 7 is the control of step 103 in Fig. 4.The operation of the robot 1 and the camera 41 in the control for judging the position of the robot 1 is determined in the operation program 27. For example, the positions and postures of the robot are set when the marks 46 a, 46 bare captured in the operation program 27. By the worker 9 pressing the start button 32, the control device 2 starts control for judging the position of the robot 1.In step 121, the robot 1 moves the camera 41 to the position for capturing the first mark 46 a. Then, in step 122, the camera 41 captures the first mark 46 a. In step 123, the image processing unit 28 of the position acquisition unit 13 acquires the image of the first mark 46 afrom the camera 41.Referring to FIG. 2, the first mark 46 amay be located outside the field of view 71 of the camera 41. That is, the camera 41 may not capture the entire first mark 46 a. The image processing unit 28 judges whether or not the entire first mark 46 ais included in the image. When the first mark 46 adiffers from the field of view 71 of the camera 41, the display control unit 25 may present a warning on the display 31. The worker 9 moves the stage cart 5 so that the first mark 46 ais disposed within the field of view 71. In the present embodiment, the worker can regulate the position of the rack car 5 so that the camera 41 is disposed directly above the first mark 46 a.It is also possible for the display control unit 25 to display the image captured by the camera 41 at specific time intervals. The worker 9 can regulate the position of the trolley 5 by viewing the image of the display 31 so as to capture the entire first mark 46 a.Then, in step 124, the image processing unit 28 calculates the position of the first mark 46 aby performing image processing. In this example, the image processing unit 28 calculates the position of the intersection of the straight lines of the first mark 46 a. As a method for detecting the position of the mark, any method capable of detecting the two-dimensional position of the mark may be employed. For example, for the detection of the marker, the template matching method using normalized correlation may be used. In this manner, the Positionserlangungseinhei8t 23 acquires the position of the first mark 46 a.Next, in step 125, the robot 1 moves the camera 41 to a position where it captures the second mark 46 b. In step 126, the camera 41 captures the second mark 46 b. In step 127, the image processing unit 28 acquires the image of the second mark 46 b.At step 127, the second mark 46 bmay be located outside the field of view 71 of the camera 71. The worker 9 can move the stage cart 5 to a position where the camera 41 can capture the second mark 46 b. In this case, the control device 2 preferably performs control whereby the first mark 46 ais picked up once again and the position of the first mark 46 ais acquired again.Or, it is possible that the control device 2 corrects the position of the robot 1 that receives the second mark 46 bbased on the result of the detection of the first mark 46 a. The control device 2 can calculate the deviation direction and the deviation amount of the position of the robot 1 with respect to the target position, based on the position of the first mark 46 a. It is also possible that the position and the posture of the robot 1 in capturing the second mark 46 aare corrected on the basis of this deviation direction and this deviation amount. By this control, the second mark 46b can be more accurately picked up.In step 128, the image processing unit 28 acquires the position of the second mark 46 bby performing image processing. In this example, it calculates the position of the intersection of the straight lines of the second mark 46b.In step 129, the judging unit combines the position of the first mark 46a and the position of the second mark 46b. For example, the image acquisition unit 123 may calculate the position of a center of a line portion connecting the position of the first mark 46 aand the position of the second mark 46 b.Then, in step 130, the position acquisition unit 13 converts the calculated position of the center point into a position in a robot coordinate system. For the robot 1, a robot coordinate system that is the standard for the operation of the robot and the measurement of the optical sensor is set in advance. The robot coordinate system is a coordinate system having an arbitrary point on the robot 1 as an origin. For example, in the robot coordinate system, the intersection of an axis J 1 as a rotation axis extending in the vertical direction and an axis J 2 extending in a horizontal direction closest to the base surface of the robot may be set as an origin point. It is also possible to set the intersection point of the upper surface of the carriage 5 and the axis J 1 as the origin point in the robot coordinate system (see FIG. 1 ).In this way, the position acquisition unit 23 can acquire the positions of the markers 46 aand 46 bwhen viewed from the robot 1. The positions of the markers 46 a, 46 bwith respect to the machine tool 46 are set in advance. Therefore, it can be said that the position acquisition unit 23 calculates the relative position of the robot 1 with respect to the machine tool 6. The position acquisition unit 23 may also combine the two positions after converting the position of the first mark 46 aand the position of the second mark 46 binto the robot coordinate system.In step 131, the judgment unit 24 judges whether or not the position of the robot 1 is within the judgment range. The judgment area may set the range of an arbitrary distance from the target position of a center point. The judgment unit 24 may calculate the distance between a predetermined target position of the center point and the current position of the center point. When this distance is at most a predetermined threshold, the judgment unit 24 may judge that the position of the robot 1 is within the judgment range.When the position of the robot 1 is within the judgment range in step 131, control proceeds to step 132. In step 132, the display control unit 25 displays the completion of the position regulation on the display 31 as shown in FIG. 6. If the position of the robot 1 deviates from the judgment range in step 131, control proceeds to step 133.In step 133, the judgment unit 24 calculates, based on the target position of the robot 1 and the current position of the robot 1, the direction in which the robot 1 is to be moved and the amount of movement. The judgment unit 24 calculates the direction and the amount of movement from the current position to the target position.The position of the robot 1 corresponds to the position of the stage truck 5. The display control unit 25 displays the direction in which the rack car 5 is to be moved and the amount of movement for the robot 1 to reach the target position, as shown in FIG. 5, on the display 31.In this way, by pressing the start button 32 by the worker, the control device 2 can automatically calculate and display the deviation of the current position of the rack car 5 on the display 31. Then, the worker can regulate the position of the rack car 5 by viewing the display 31.Referring to FIG. 5, the display in the present embodiment shows the direction for the movement of the carriage by an arrow. By applying this representation, the worker can easily grasp the direction in which the movement is to be made. As shown in FIGS. 5 and 6, the display of whether or not the robot 1 is disposed within the judgment area may be displayed by "completed" or "not completed". Or, it is possible that the display shows "OK" or "NG" (not good).The image showing the display is not limited to the direction in which the carriage is to be moved, and the amount of movement, and arbitrary information may be displayed. The display may also display detailed information at the time of detection of the mark. For example, the display may also represent the position of the detected mark and a fit score or the like. Or, the display 31 may display the captured image of the mark.The camera 41 as an optical sensor is calibrated with respect to the robot coordinate system RO. That is, as for the camera 41, the relationship between the position of the robot and the image of the mark captured by the camera 41 is calibrated in advance. The control device 2 may convert the position of the mark detected in the image of the camera 41 to a position of the robot coordinate system. The information regarding the calibration of the camera 41 with respect to the robot coordinate system (the calibration data) may be stored in the storage unit 21. In general, it is sufficient if the calibration of the optical sensor is carried out once, provided that the relative position of the optical sensor and of the robot coordinate system does not change.In addition, in the present embodiment, the position acquisition unit 23 acquires the position of the robot 1 by converting the positions of the markers 46 a, 46 bto the robot coordinate system, but is not limited thereto. The control device 2 can also judge the judgment of the position of the robot 1 based on the position in the image captured by the camera 41. For example, a coordinate system may be set in which the upper left peak point of the image captured by the camera is set as an origin. Then, the position acquisition unit may detect the position of the mark in the image. The judgment unit may judge the position of the robot using the coordinate values of the coordinate system on the image.In the first robot system according to the present embodiment, the judgment of the position of the robot is made by arranging marks at two locations. When an arrow symbol or the like is applied to the mark, the control device may also detect the deviation of the angle in addition to the deviation of the position of the robot with respect to the mark. Therefore, the robot system can make the judgment of the position of the robot based on a mark at a location. The identification accuracy of the optical sensor can also be increased by arranging a plurality of marks and combining the measurement results.Now, a detailed explanation will be given of an example of the control of the position acquisition unit 23 and the judgment unit 24 in the present embodiment. Here, an example in which the judgment is made using a mark will be explained. The position of the mark in the robot coordinate system R 0 is expressed by the symbol P. The position P of the mark corresponds to the position of the robot and the position of the carriage. The target position P 0 of the marker is set in advance. The target position P 0 may be stored in the storage unit 21. When the position P of the marker has arrived at the target position P 0, the robot 1 is also arranged at the target position.The image processing unit 28 of the position acquisition unit 23 may calculate a position P 1 of the mark using the image of the camera 41. The judgment unit 24 may calculate the distance between the actual position P 1 of the marker and the target position P 0.When the distance between the position P 1 of the marker and the target position P 0 exceeds a predetermined threshold, the judgment unit 24 may judge that the position of the robot 1 deviates from the judgment range. When the distance between the position P 1 of the marker and the target position P 0 is within the threshold, the judgment unit 24 may judge that the position of the robot 1 is within the judgment range.As such a distance between the actual position P 1 of the mark and the target position P 0, the aerial line between the position P 1 of the mark and the target position P 0 may be used. Or, for detecting a two-dimensional deviation of the position, a component of a parallel movement and a component of a rotational movement can be set as the directional component. That is, within a certain area, an x-axis and a y-axis crossing each other may be set, and an r-axis may be set about a z-axis perpendicular to the certain area. The coordinate value of the r-axis can be expressed by the rotation angle. Then, the judging unit 24 may calculate the deviations in the directions of the respective components. For example, the deviation of the x-axis direction may also be calculated and a judgment made using the threshold value of the x-axis direction, and the deviation of the y-axis direction may be calculated and a judgment made using the threshold value of the y-axis direction.The judgment unit may calculate the deviation of the position of the robot in a predetermined direction based on the position of the mark acquired by the position acquisition unit. Then, the judging unit may judge whether or not the deviation of the position of the robot is within the judging range. Or, the judging unit may make judgments for plural directions. By performing this control, an accurate judgment can be made according to the operation of the robot 1.As in the modification examples discussed later, in a calculation of a three-dimensional deviation of a position and posture, it is also possible to add a component to the posture of the robot 1 and evaluate the deviation in the x-axis direction, the y-axis direction, the z-axis direction, a w-axis direction (the direction about the x-axis), a p-axis direction (the direction about the y-axis), and the r-axis direction (the direction about the z-axis) by individual components.In the first robot system, it is necessary that the position of the mark is set in advance. Then, the position of the mark with respect to the machine tool is constant. In the first robot system, the mark is disposed on the upper surface of a columnar member upstanding from the floor, but is not limited thereto. The mark may be disposed in an area that can be picked up by the optical sensor. When the optical sensor is fixed to the robot, the mark may be disposed at a position that can be picked up by an operation of the robot.For example, the mark may also be disposed on a device becoming the object for the operation of the robot. In the present embodiment, the mark may also be disposed on the frame body of the machine tool. Or, the shape of a part of the main body of the machine tool may be used as a mark. For example, a portion of the frame body of the machine tool may be used as a mark and captured by the camera. The position of the mark corresponds to the position of the device becoming the object for the operation of the robot. The mark may be disposed at any position as long as the relative positional relationship to the device becoming the object for the operation of the robot does not change.FIG. 8 is an oblique view of a second robot system of the present embodiment. The second robot system 92 includes a plurality of cameras 42, 43. the cameras 42, 43 as optical sensors are fixed to the frame cart 5. The cameras 42, 43 are fixed to the upper plate 53 via holding elements 56. The cameras 42, 43 are arranged to coincide with the positions of the marks 46 a, 46 bwhen the robot 1 is placed at the target position.Thus, cameras can also be fixed to the frame carriage 5. In the second robot system 92, adjustment of the position of the carriage 5 can be made without driving the robot 1. That is, the regulation of the position of the robot 1 can be performed without driving the robot 1. In addition, the first mark 46 aand the second mark 46 bmay be recorded simultaneously. Therefore, the regulation of the position of the carriage 5 can be performed in a short time.When the cameras 42, 43 are fixed to the cradle car 5, the image of the cameras 42, 43 can be calibrated with respect to the cradle car 5. In this case, the detected positions of the marks may not be converted into coordinate values of the robot coordinate system, but may be converted into coordinate values of another coordinate system. For example, the control device may perform conversion into coordinate values of a coordinate system in which a predetermined point on the carriage is set to the origin point.In the second robot system 92, the position acquisition unit 23 may calculate the positions of the markers 46 a, 46 bbased on the images captured by the cameras 42, 43. The judgment unit 24 can judge whether or not the position of the robot 1 is within a predetermined judgment range based on the positions of the markers 46 a, 46 b. Upon judging that the position of the robot 1 deviates from the judgment range, the display 31 may display the direction in which the carriage 5 is to be moved and the amount of movement.In the above-described embodiment, the markers 46 a, 46 bare disposed at the work site where the rack car 5 is disposed, and the camera(s) 41, 42, 43 are disposed on the robot 1 or the rack car 5. However, it is not limited thereto, and it is also possible to arrange the cameras at the work site and establish the markers on the robot or the rack car.FIG. 9 is an oblique view of a third robot system of the present embodiment. In the third robot system 93, the cameras 42, 43 are fixed to the machine tool 6 as optical sensors. That is, the cameras are arranged on the machine tool. The markings 46 a, 46 bare arranged on the frame carriage 5. Plate-shaped elements 47 are fixed to the upper plate 53 of the chassis carriage 5, on which elements the markings 46 a, 46 bare applied. The cameras 42, 43 are fixed in the upper part of the frame body 64 of the machine tool 6. The cameras 42, 43 are arranged to coincide with the positions of the marks 46 a, 46 bwhen the robot 1 has been placed at the target position. The images captured by the cameras 42, 43 may be transmitted to the control device 2 via a wireless device. Or, the images captured by the cameras 42, 43 may be transmitted to the control device 2 via a wired communication device. For example, a worker may connect the communication device connected to the cameras 42, 43 to the control device 2 after the cradle cart 5 is placed in the vicinity of the work machine 6.In the third robot system 93, the regulation of the position of the robot 1 can be performed by the same control as in the second robot system 92. In the third robot system 93, the position of the robot 1 can be regulated by moving the gantry 5 on the basis of the images of the markers 46 a, 46 bacquired by the cameras 42, 43.Thus, the cameras 42, 43 can be installed at the work site where the rack car 5 is placed. The portion where the cameras are configured is not limited to the frame body of the machine tool, and it is also possible to arrange support members standing up from the ground laterally of the machine tool and fix the cameras to the support members, for example.In the example shown in FIG. 9, two marks 46 a, 46 bare disposed on the frame cart 5, but there is no limitation thereto, and a mark may be disposed on the wrist portion 13 of the robot 1. For example, a plate-shaped member to which the one mark has been applied may be fixed to the wrist portion 13. In this robot system, the two cameras can take the mark by changing the position and posture of the robot. The regulation of the position of the robot 1 can be performed by the same control as in the first robot system of the present embodiment.In the robot systems described above, the control device of the robot has a function of processing and judging an image captured by the optical sensor. However, there is no limitation thereto, and the robot system may be provided with an image processing device having the function of processing the image and judging. The image processing apparatus includes a computation processing apparatus provided with a CPU and a RAM, etc. Then, the image processing device may be configured to be capable of communicating with the control device via a radio device. For example, an imaging device provided with a position acquisition unit including an image processing unit, a judgment unit, a display control unit, and an operation control unit that controls the cameras may also be connected to the control device.The camera for the above-described optical sensor is a two-dimensional camera, but any optical sensor capable of detecting the position of the mark and any control method may be employed. Next, modifications of the optical sensor and the controller for judging the position of the robot will be explained.In the first modification, the robot system detects the position of the robot by stereo measurement. At the tip end of the arm of the robot, a two-dimensional camera is disposed as an optical sensor. At the work site at which the rack car is arranged, a third marking is set up in addition to the first marking and the second marking. These marks are disposed at positions away from each other.First, the camera captures the first mark. Then, the camera captures the first mark again after such a movement of the robot that the first mark does not protrude beyond the field of view of the camera. The camera records the same marking from two different viewpoints. By this stereo measurement, coordinate values (x, y, z) of the three-dimensional position of the first mark can be obtained. Then, the same measurement is made with respect to the second mark and the third mark. Using the three-dimensional positions of the first mark, the second mark, and the third mark, a three-dimensional plane passing through three points can be calculated. As a result, a three-dimensional positional relationship of the robot and the machine tool can be obtained. By making a three-dimensional measurement, in addition to judging the planar position, judgment of the inclination of the carriage can also be made.In the second modification, a three-dimensional camera as an optical sensor is disposed at the tip end of the arm of the robot. The robot system detects the position of the machine tool by a three-dimensional measurement. The optical sensor captures the first mark, and the controller detects the two-dimensional position. Then, the optical sensor radiates two mutually intersecting laser lights onto the plane in which the first marking is arranged. The controller determines the inclination of the plane by identifying the laser lights reflected on the image. The control device may acquire coordinate values (x, y, z, w, p, r) of the three-dimensional position and posture of the first mark by combining the result of the two-dimensional measurement and the calculated plane.By detecting the three-dimensional position and posture of the first mark, judgment of the three-dimensional position and posture of the robot can be made. Moreover, by making a measurement of the second mark and the third mark and combining the three-dimensional position and posture of the individual points, it is possible to obtain the coordinate values (x, y, z, w, p, r) of the three-dimensional position with even higher accuracy.In this example, as the three-dimensional camera, a camera capable of emitting laser light was adopted, but any optical sensor capable of acquiring the three-dimensional position and posture of a mark may be adopted.In the third modification, three two-dimensional cameras are arranged on the frame carriage as optical sensors, and the position of the machine tool is determined by three-dimensional measurement. The three cameras are arranged such that their lines of sight are not parallel to each other, but the lines of sight are directed in different directions from each other. A first marking, a second marking and a third marking are arranged at the work location. The size and shape of a triangle formed by the positions of the three marks are set in advance.Using the three cameras arranged on the frame carriage, the first marking, the second marking and the third marking are recorded in each case. The control device calculates three lines of sight from the results of capturing the first mark, the second mark and the third mark. The controller may calculate the three-dimensional positions of the vertices of the triangle by applying the three lines of sight to the previously known triangle. The control device can make the judgment based on these three-dimensional positions.In addition to the above-mentioned modifications, a three-dimensional camera can also be arranged on the frame carriage. In addition, the third modification may be performed by the two-dimensional camera disposed at the tip end of the arm of the robot. The above-described controls for judging the position may be combined as appropriate.As the mark in the present embodiment, a character is used. However, the mark is arbitrary as long as it can be identified by an optical sensor. For example, as the mark, a bar code such as a QR code (registered trademark) or a matrix code may be used. The marking can also contain a barcode in addition to a character. For example, a plurality of machine tools that perform work may be arranged side by side. In this case, the mark for preventing an error in selection of the machine tool by the worker may include a barcode showing the correspondence of the machine tool and the robot. The optical sensor may record the barcode, and the control device may display a number or the like of the machine tool on the display.The optical sensor of the present embodiment receives the mark to detect the position of the machine tool, but is not limited thereto, and the optical sensor may be used for inspecting a workpiece or detecting the position of a workpiece, and the like.The mechanism that drives the robot in the present embodiment is a vertical articulated arm mechanism, but is not limited thereto, and any mechanism may be employed. For example, as a mechanism that drives the robot, a linear motion mechanism or a parallel link mechanism may be employed.In the individual controls described above, the order of the steps can be changed as appropriate within a range that does not change the functions and effects.By the present invention, a robot system can be provided that can easily detect the position of a rack car that carries a robot.In the individual drawings described above, the same or identical elements are provided with the same reference numerals. The above-described embodiments are exemplary and do not limit the invention.

Claims

A robot system comprising a robot (1) that performs a predetermined operation; a cradle truck (5) that carries the robot (1) and moves by an operation by a worker (9); an optical sensor (41) fixed to a wrist portion (13) of the robot (1); a first mark (46a) and a second mark (46b) that are set at a work site where the cradle truck (5) is placed in performing the operation by the robot (1); a control device (2) including a computation processing device that processes the information obtained by the optical sensor (41) and controls the operation of the robot (1); and a display (31) that displays the result processed by the computation processing device, characterized in that, the control device (2) changes a position and a posture of the robot (1) to move the optical sensor (41) to the position for capturing an image of the second mark (46b) and capture an image of the second mark (46b) after the optical sensor (41) captures an image of the first mark (46a) in a state in which the carriage (5) has been moved to the work site, the arithmetic processing device includes a position acquisition unit (23) that acquires positions of the first mark (46a) and the second mark (46b) on the basis of images captured by the optical sensor (41), and a judgment unit (24) that judges positions of the first mark (46a) and the second mark (46b) on the basis of the positions of the first mark (46a) and the second mark (46b) acquired by the position acquisition unit (23), whether or not the robot (1) is disposed at a position in a predetermined judgment area, wherein the judgment unit (24) calculates, upon judgment that the position of the robot (1) deviates from the judgment area, the direction in which the rack car (5) is to be moved and the amount of movement for the robot (1) to reach a target position, and the display (31) displays the direction in which the rack car (5) is to be moved and the amount of movement.The robot system according to claim 1, wherein relationships between the position of the robot (1) and an image of the first mark (46a) acquired by the optical sensor (41) and an image of the second mark (46b) for the optical sensor (41) are calibrated in advance, and the position acquisition unit (23) calculates the positions of the first mark (46a) and the second mark (46b) by processing an image of the first mark (46a) and an image of the second mark (46b) whose positional relationships to the work location are set in advance.The robot system according to claim 1 or 2, wherein the judgment unit (24) calculates the distance between the actual position of the mark and the target position of the mark in a plurality of predetermined directions based on positions of the first mark (46a) and the second mark (46b) acquired by the position acquisition unit (23), and judges whether or not the distance is within the judgment range for the respective directions.The robot system according to any one of claims 1 to 3, wherein the display (31) updates the display image based on the result by the judging unit (24) so that the worker (9) can regulate the position of the rack car (5) while watching the display (31).A robot system comprising a robot (1) that performs a predetermined operation; a cradle truck (5) that carries the robot (1) and moves by an operation by a worker (9); a first optical sensor and a second optical sensor that are arranged at a work site where the cradle truck (5) is arranged in performing the operation by the robot (1); a mark arranged at a wrist portion (13) of the robot (1); a control device (2) including a computation processing device that processes the information obtained by the optical sensors and controls the operation of the robot (1); and a display (31) that displays the result processed by the computation processing device, characterized in that the control device (2) changes a position and a posture of the robot (1), to move the mark to the position for capturing an image of the mark by the second optical sensor and capture an image of the mark by the second optical sensor after the first optical sensor captures an image of the mark in a state in which the cradle truck (5) has been moved to the work site, the arithmetic processing device includes a position acquisition unit (23) that acquires positions of the mark on the basis of the image captured by the first optical sensor and the image captured by the second optical sensor, and a judgment unit (24) that judges whether or not the robot (1) is disposed at a position in a predetermined judgment range on the basis of the positions of the mark acquired by the position acquisition unit (23), wherein the judgment unit (24), upon judgment, judges whether or not the robot (1) is disposed at a position in a predetermined judgment range, wherein the position of the robot (1) deviates from the judging range, calculates the direction in which the carriage (5) is to be moved and the amount of movement for the robot (1) to reach a target position, and the display (31) displays the direction in which the carriage (5) is to be moved and the amount of movement.

Images