Robot arm, robot arm control method and program

Abstract

To provide a robot arm capable of easily specifying a position of the arm at high speed.SOLUTION: Since colors of ridge lines connected to any apex of a camera unit 24 are colored in three difference colors of red, blue, and green, a region corresponding to the ridge lines can be easily extracted from imaging information obtained by shooting a region including the camera unit 24 with imaging means 26. From the length of the region corresponding to the ridge lines or change amount of a position, relative mobility of a position corresponding to the ridge lines is calculated (a step S150), and lens position coordinate is calculated (a step S160). Therefore, a robot arm 20 can be provided, which can reduce the amount of processing when performing extraction processing for extracting information from the imaging information, correction processing for calculating a three-dimensional rotation angle from a planar image and the like, and can easily calculating a position of an arm portion 22 at high speed.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a robot arm, a control method for a robot arm, and a program. [Background technology]

[0002] Conventionally, a robot position correction system has been known that has a relatively simple and inexpensive configuration and performs position detection and, therefore, position correction with sufficient accuracy. For example, Patent Document 1 describes a robot position correction system in which targets, such as concentric circles, are provided on each axis (arm) of the robot body, a CCD camera is provided for capturing images of the target portions of each axis, and a visual recognition device is provided to detect the position of each target from the image data. In this robot position correction system, when a difference occurs between the angle obtained by the encoder and the actual angle due to, for example, the influence of gravity, resulting in an error between the command pose and the realized pose of the robot, the system first detects the positions of three or more targets on one axis of the robot body to derive installation parameters. Then, during robot operation, the system detects the positions of targets on, for example, two or three axes, and calculates the pose using the resulting angle errors for each axis. This allows for sufficiently accurate position detection and position correction of the robot body with a relatively simple and inexpensive configuration. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-117861 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the robot position correction system described in Patent Document 1, targets are set on the surface of the robot body, and depending on the angle of the robot, the camera may not be able to photograph the target, so multiple cameras must be set up. In order to detect the robot's position, it is necessary to correct the planar images taken by the cameras and combine the photographic information obtained from the multiple cameras, which poses the problem of requiring a large amount of information processing to identify the robot's position.

[0005] The present invention has been made in consideration of the above-mentioned problems, and has as its main object to provide a robot arm that can quickly and easily identify its position by reducing the amount of information processing required to identify the position of the robot arm, and also to provide a control method and program for this robot arm. [Means for solving the problem]

[0006] In order to achieve at least one of the above-mentioned objects, the present invention employs the following means.

[0007] The robot arm of the present invention comprises: A movable arm; a hexahedral structure attached to the arm, with all ridges connected to any vertex being a different color; an imaging means for imaging an area including the target structure and the arm and transmitting imaging information; a control means for calculating a position of the arm based on information about the ridgeline included in the photographing information transmitted from the photographing means; characterized in that it comprises It is something.

[0008] In this robot arm, a target structure having a hexahedral shape is attached to a movable arm, and the ridge lines connecting any vertices are all different colors. The imaging means captures an image of an area including the target structure and the arm, transmits imaging information including information about the ridge lines to the control means, and calculates the position of the arm based on the imaging information. Specifically, the position and rotation angle of the target structure are calculated by calculating the length and direction of the ridge lines from the information about the ridge lines included in the imaging information, and the position of the target structure is calculated by calculating the position of the arm. In this way, calculating the position and rotation angle of the ridge lines from the information about the ridge lines included in the imaging information reduces the amount of processing required for extraction processes that extract necessary information from the imaging information and correction processes that calculate three-dimensional rotation angles from planar images, allowing the position of the arm to be calculated quickly and easily. In this case, because the target structure has a hexahedral shape, even when the arm moves three-dimensionally, the possibility of the imaging means being unable to capture the target structure due to obstruction by the arm is reduced. In other words, if the object to be photographed is a flat mark such as a figure, the range in which the photographing means can photograph the mark is limited, so multiple photographing means are required, and the photographic information from the multiple photographing means must be combined and each image must be processed.However, by making the shape three-dimensional, a hexahedron, this processing is not necessary, so the arm position can be calculated quickly and easily.

[0009] In the robot arm of the present invention, the control means is configured to control the arm based on the information about the ridgeline included in the photographing information obtained by photographing the arm positioned at the reference position and the information about the ridgeline included in the photographing information obtained by photographing the arm by the photographing means. Shooting information The position of the arm may be calculated by comparing information about the ridge line included in the imaging information obtained by imaging the arm positioned at a reference position with information about the ridge line included in the imaging information obtained by imaging the arm positioned at a reference position. In this way, the position of the ridge line and the rotation angle of the arm can be calculated quickly and easily using as a reference the information about the ridge line included in the imaging information obtained by imaging the arm positioned at a reference position. Note that the "reference position" here refers to a predetermined position where the three-dimensional coordinates of the arm and the position and rotation angle of the ridge line indicated by the information about the ridge line included in the imaging information obtained by imaging the arm positioned at the reference position are stored in association with each other.

[0010] In the robot arm of the present invention, the photographing means comprises a first photographing means for photographing an area including the subject structure and the arm and transmitting first photographing information, and a second photographing means for photographing an area including the subject structure and the arm and transmitting second photographing information, and the control means determines whether the first photographing information includes information relating to four or more of the ridge lines, and when it determines that four or more of the ridge lines are included, transmits information relating to the ridge lines included in photographing information obtained by photographing the arm positioned at a reference position, the first photographing information and calculating the position of the arm by comparing the information about the edge line included in Less than 4 locations If it is determined that the arm is positioned at a reference position, information about the ridgeline included in the photographing information of the arm positioned at a reference position is the second photographing information The position of the arm may be calculated by comparing information about the ridge lines included in with If the photographing information transmitted from the photographing means does not include information corresponding to the four ridge lines of the subject structure, it is highly likely that the photographing information does not include sufficient information necessary to calculate the position of the subject structure, and in such a case, the position of the arm can be calculated quickly and easily by calculating the position of the subject structure based on photographing information photographed by a second photographing means located at a different position from the first photographing means.

[0011] In the robot arm of the present invention, the object to be photographed may be a line camera. For example, when the robot arm of the present invention is used to inspect a welding condition, the arm is equipped with a line camera that photographs the welded area. Therefore, by making the line camera hexahedral and making the colors of the ridges connecting any vertices different, it is not necessary to provide a new object to be photographed. Furthermore, when inspecting continuous welding conditions, the photographing direction of the photographed information captured by the line camera changes depending on the position of the moving arm. Therefore, applying the present invention is highly effective when calculating the position of the arm when photographed by the line camera and correcting the photographed information according to the arm position.

[0012] The robot arm control method of the present invention includes: A method for controlling a robot arm comprising: a movable arm; a target structure attached to the arm, the target structure being hexahedral in shape, with all ridge lines connecting to any vertex being of different colors; an imaging means for imaging an area including the target structure and the arm and transmitting imaging information; and a control means for calculating a position of the arm based on information about the ridge lines included in the imaging information transmitted from the imaging means, a position calculation step of calculating a position of the arm based on information about the ridgeline included in the photographing information transmitted from the photographing means; characterized in that it comprises It is something.

[0013] In this robot arm control method, a target structure having a hexahedral shape is attached to a movable arm, and the ridge lines connecting any vertices are all different colors. The imaging means captures an area including the target structure and the arm, transmits imaging information including information about the ridge lines to the control means, and calculates the position of the arm based on the imaging information. Specifically, the length and direction of the ridge lines are calculated from the information about the ridge lines included in the imaging information, thereby calculating the position and rotation angle of the target structure, and the position of the arm is calculated by calculating the position of the target structure. In this way, calculating the position and rotation angle of the ridge lines from the information about the ridge lines included in the imaging information reduces the amount of processing required for extraction processes that extract necessary information from the imaging information and correction processes that calculate three-dimensional rotation angles from planar images, allowing the arm position to be calculated quickly and easily. In this case, because the target structure has a hexahedral shape, even when the arm moves three-dimensionally, the possibility of the imaging means being unable to capture the target structure due to obstruction by the arm is reduced. In other words, if the object to be photographed is a flat mark such as a figure, the range in which the photographing means can photograph the mark is limited, so multiple photographing means are required, and the photographic information from the multiple photographing means must be combined and each image must be processed.However, by making the shape three-dimensional, a hexahedron, this processing is not necessary, so the arm position can be calculated quickly and easily.

[0014] The program of the present invention is a program for causing one or more computers to execute each step of the robot arm control method. This program may be recorded on a computer-readable storage medium (e.g., a hard disk, ROM, CD, DVD, flash memory, etc.), or may be transmitted from one computer to another via a transmission medium (a communication network such as the Internet or a wired / wireless LAN), or may be transmitted in any other form. Furthermore, even if the program is executed by a device that executes each step of the control method, the device on which the program is executed may be different from the device on which the processing is performed. In either case, by executing this program on a single computer or by having multiple computers share and execute each step, it is possible to obtain the same effects as the robot arm control method described above. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a block diagram for explaining the electrical connections of the robot arm 20. As shown in FIG. [Figure 2] FIG. 2 is an explanatory diagram for explaining the camera unit 24. As shown in FIG. [Figure 3] FIG. 3 is a flowchart showing an example of a position calculation processing routine. DETAILED DESCRIPTION OF THE INVENTION

[0016] Next, a robot arm 20 will be described in detail as an example of an embodiment of the present invention. The embodiments and drawings described below exemplify some of the embodiments of the present invention and are not intended to limit the scope of the present invention. Appropriate modifications can be made without departing from the spirit of the present invention. Corresponding components in each drawing are denoted by the same or similar reference numerals. Furthermore, by showing an example of a control method for the robot arm 20, an example of a control method for a robot arm of the present invention will also be clarified.

[0017] 1, a robot arm 20, which is an example of an embodiment of the present invention, includes a movable arm 22, a camera unit 24 attached to the tip of the arm 22, a first imaging device 26a provided at a position where the tip of the arm 22 can be photographed, a second imaging device 26b provided at a position where the tip of the arm 22 can be photographed, and a control unit 30 electrically connected thereto. The control unit 30 controls the drive of the arm and performs a position calculation process to calculate the position of the arm from first imaging information or second imaging information captured by the first imaging device 26a or second imaging device 26b. The first imaging device 26a and the second imaging device 26b (hereinafter also referred to as "imaging device 26") photograph an area including the camera unit 24 attached to the tip of the movable arm 22, and the control unit 30 calculates the position of the arm 22 based on the first imaging information and second imaging information (hereinafter also referred to as "imaging information") transmitted from the first imaging device 26a and the second imaging device 26b. The camera unit 24 has a hexahedral shape, and all of the ridges connecting to any vertex are formed in different colors. By adopting such a hexahedral shape, even when the arm section 22 moves to any position, the camera unit 24 can be photographed by the camera section 26 as long as the arm section 22 does not move to a position where the camera section 26, arm section 22, and camera unit 24 are aligned in a straight line. Therefore, even if multiple camera sections 26 are not provided, the camera unit 24 can be included when photographed by the camera section 26. In addition, because the ridge lines connected to any vertex are all formed in different colors, the orientation of the camera unit 24 can be easily identified from the ridge line color, and the position of the camera unit 24 can be quickly and easily calculated. Additionally, because the positional relationship between the camera unit 24 and the tip position of the arm section 22 is fixed, the tip position of the arm section 22 can be quickly and easily calculated.

[0018] The arm 22 is a known robot arm, such as a six-axis robot arm. A camera unit 24 for capturing images in the direction of the tip is provided at the tip of the arm 22, and the arm 22 rotates and moves in any direction based on a control signal from the control unit 30, capturing images in the direction of the tip with the camera unit 24.

[0019] The camera unit 24 corresponds to the photographed structure of the present invention, and is a known camera (e.g., a line camera) having a hexahedron shape with six black faces, detachably attached to the tip of the arm unit 22, and equipped with a lens 24a on the side of the arm unit 22 toward the tip. By making the line camera unit 24 detachable in this way, when attaching the camera unit 24 to the arm unit 22, the photographing direction of the camera unit 24 can be changed by changing the attachment direction. In this camera unit 24, all of the ridges connected to any vertex are colored differently. Specifically, as shown in FIG. 2, the camera unit 24 has a hexahedron shape consisting of vertices A, B, C, D, E, G, and G (vertex G is not shown), and the face consisting of vertices E, F, and G is fixed to the surface of the arm unit 22. Furthermore, ridge lines AE, BF, CG, and DH are each colored blue; ridge lines AB, CD, EF, and GH are each colored red; and ridge lines AD, BC, EH, and FG are each colored green. Thus, all ridge lines connected to any vertex are colored differently. Because the ridge lines are different colors from the six faces of camera unit 24, analyzing the image information captured by camera unit 24 facilitates identifying the areas corresponding to the ridge lines that form the boundaries between adjacent faces, making it easy to extract the areas corresponding to the ridge lines from the image information. Additionally, by prescribing the distances between ridge lines, the effort required for distance calibration can be reduced when calculating the position of arm 22. Furthermore, because each ridge line has a different color, the relationship between the ridge lines can be used to easily calculate the tilt angle of camera unit 24 from the image information. For example, if camera unit 24 is attached at a position where ridge line AE is perpendicular to the surface of arm portion 22, by pre-memorizing that this blue ridge line is perpendicular to arm portion 22, the tilt angle of camera unit 24 can be easily calculated based on the information of the area corresponding to the blue ridge line contained in the shooting information.

[0020] In this case, the dimensions of camera unit 24 may be, for example, 120 mm for side AB, 40 mm for side AD, and 110 mm for side AE. This reduces the possibility of interfering with the operation of arm 24, and also makes it easier to extract the area corresponding to the ridgeline of camera unit 24 from the image capture information.

[0021] The first image capturing means 26a is a known image capturing means, such as a digital camera or digital video camera, provided at a position where it can capture images of the tip of the arm section 22. The first image capturing means 26a is electrically connected to the control unit 30, captures images of the vicinity of the arm section 22 including the camera unit 24, and sequentially transmits first image capturing information to the control unit 30. The control unit 30, upon receiving this first image capturing information, calculates the position of the tip of the arm section 22 based on the first image capturing information. Note that the first image capturing means 26a only needs to be electrically connected to the control unit 30, and may be fixed to a part of the robot including the arm section 22, or may be a unit that can be moved to any location.

[0022] The second imaging means 26b is a known imaging means, such as a digital camera or digital video camera, that is located at a position where it can capture an image of the tip of the arm section 22 but not on the line connecting the first imaging means 26a and the arm section 22. The second imaging means 26b is electrically connected to the control unit 30, captures images of the vicinity of the arm section 22 including the camera unit 24, and sequentially transmits second imaging information to the control unit 30. The control unit 30, upon receiving this second imaging information, calculates the tip position of the arm section 22 based on the second imaging information. At this time, because the second imaging means 26b is located at a position not on the line connecting the first imaging means 26a and the arm section 22, it can be said that the first imaging information captured by the first imaging means 26a and the second imaging information captured by the second imaging means 26b are imaging information of the camera unit 24 and the arm section 22 at different angles. In other words, when the arm section 22 including the camera unit 24 is simultaneously photographed by the first photographing means 26a and the second photographing means 26b, the first photographing means 26a or the second photographing means 26b, the arm section 22, and the camera unit 24 are positioned in a straight line, and there is no possibility that the camera unit 24 will not be included in the photographing information due to the arm section 22, so that either the first photographing information or the second photographing information will always include information on the area corresponding to the camera unit 24. This prevents a situation in which the photographing information of the camera unit 24 is not included in the photographing information and the position of the arm section 22 cannot be calculated. Note that the first photographing means 26a only needs to be electrically connected to the control unit 30, and may be fixed to a part of the robot including the arm section 22, or may be a unit that can be moved to any location.

[0023] 1, the control unit 30 is configured as a microprocessor centered around a CPU 31, and is electrically connected via a bus 35 to a ROM 32 storing various control programs for controlling the arm section 22 and the imaging means 26, a RAM 33 temporarily storing imaging information and the like captured by the imaging means 26, and an interface 34 (hereinafter referred to as "I / F 34") for transmitting and receiving various signals to and from the arm section 22, imaging means 26, etc. The control means 30 calculates the position of the arm section 22 based on the imaging information captured by the imaging means 26.

[0024] Next, the operation performed when calculating the position of the arm portion 22 will be described using as an example a position calculation processing routine executed by the control unit 30. This position calculation processing routine is repeatedly executed at predetermined times (for example, when an execution start command is received, when the drive of the arm portion 22 is recognized, etc.). Note that FIG. 3 is a flowchart showing an example of the position calculation processing routine.

[0025] When this position calculation processing routine is executed by CPU 31, an area corresponding to the ridgeline of camera unit 24 is extracted from the first photographing information output from first photographing means 26a (step S110). Specifically, the area corresponding to the ridgeline of camera unit 24 is extracted using a known image processing technique, such as extracting an area where red, blue, or green appears predominantly or an area that appears linearly, or extracting the area using artificial intelligence that has previously learned photographing information including the area corresponding to the ridgeline. At this time, since the ridgeline of camera unit 24 differs depending on the orientation of the ridgeline and is colored a different color from each face of camera unit 24, it is easier to extract the area corresponding to the ridgeline of camera unit 24 compared to when the color of the ridgeline and the color of each face are the same color.

[0026] Next, CPU 31 determines whether the number of extracted regions corresponding to the ridgelines of camera unit 24 is four or more (step S120), and if it determines that the number of regions is less than four, extracts the regions corresponding to the ridgelines of camera unit 24 from the second photographing information output from second photographing means 26b (step S130). If the number of regions corresponding to the ridgelines of camera unit 24 included in the first photographing information is less than four, it is possible that camera unit 24 was shielded by arm portion 22 when photographing with first photographing means 26a, and was not photographed sufficiently by first photographing means 26a. Therefore, by using second photographing information photographed from a position different from that of first photographing means 26a, the position of arm portion 22 can be calculated based on the photographing information including the regions corresponding to the ridgelines of camera unit 24.

[0027] Next, CPU 31 determines whether the number of areas corresponding to the ridgelines of camera unit 24 included in the second photographing information is 4 or more (step S140), and ends this routine if it determines that the number of areas is less than 4. In such a case, since the number of areas corresponding to the ridgelines of camera unit 24 is less than 4 in both the first photographing information and the second photographing information, there is a high possibility that there is some problem with the photographing environment, and the position of camera unit 24 cannot be calculated.

[0028] On the other hand, if the CPU 31 determines in step S120 that the number of regions corresponding to the ridge lines of the camera unit 24 included in the first photographing information is four or more, or if the CPU 31 determines in step S140 that the number of regions corresponding to the ridge lines of the camera unit 24 included in the second photographing information is four or more, the CPU 31 calculates the relative mobility of the ridge lines based on the first photographing information or the second photographing information (step S150). Specifically, the CPU 31 compares information about the reference positions of the regions corresponding to the ridge lines stored in advance in RAM 33 with information about the positions of the regions corresponding to the ridge lines extracted in step S110 or step S130, and calculates the amount of change from the reference position of the regions corresponding to the ridge lines included in the first photographing information or the second photographing information. In this way, the amount of change relative to the reference position of the regions corresponding to the ridge lines when the first photographing information or the second photographing information was photographed can be calculated as mobility. Here, the "reference position" means the position of the area corresponding to the ridge line when the camera unit 24 is positioned at a predetermined position and photographed by the photographing means 26, and may be stored in advance in RAM 33 or ROM 34 depending on the position of the photographing means 26, or may be photographed as a calibration procedure before use and stored in RAM 33.

[0029] Next, CPU 31 calculates the position coordinates of lens 24a (step S160) and ends this routine. Specifically, the lens position coordinates are calculated by adding the mobility calculated in step S150 to the position coordinates of lens 24a at the reference position. In this way, by making the colors of the ridges of camera unit 24 different from each other, it becomes easier to extract the areas corresponding to the ridges included in the shooting information, and by calculating and using the mobility of this easy-to-extract area, the position of lens 24a of the camera unit can be easily calculated.

[0030] According to the robot arm 20 of the embodiment described above, the colors of the ridge lines connected to any vertex of the camera unit 24 are colored in three different colors, red, blue, and green, making it easy to extract the area corresponding to the ridge line from the image information obtained by capturing an image of the area including the camera unit 24 with the imaging means 26. Furthermore, by calculating the relative mobility of the position corresponding to the ridge line from the amount of change in the length or position of the area corresponding to the ridge line (step S150) and calculating the lens position coordinates (step S160), the amount of processing required for extraction processing to extract information from the image information and correction processing to calculate a three-dimensional rotation angle from a planar image can be reduced, making it possible to quickly and easily calculate the position of the arm section 22.

[0031] Furthermore, in step S150, the relative mobility is calculated by comparing information about the reference position of the area corresponding to the ridge line with information about the position of the area corresponding to the ridge line extracted in step S110 or step S130. This reduces the amount of processing required when performing extraction processing to extract information from imaging information or correction processing to calculate a three-dimensional rotation angle from a planar image, and enables mobility to be calculated quickly and easily.

[0032] Furthermore, if the system has two photographing means, a first photographing means 26a and a second photographing means 26b, and the area corresponding to the ridge line included in the first photographing information is less than four, the area corresponding to the ridge line is used from the second photographing information.If it is difficult to calculate the position of the camera unit 30 from the photographing information photographed by the first photographing means 26a, the position of the arm portion 22 can be calculated quickly and easily by using the photographing information photographed by the second photographing means 26b, regardless of the position of the arm portion 22.

[0033] Furthermore, by calculating the relative movement of the ridgeline of camera unit 24, it is not necessary to provide a new structure to be photographed as a reference for calculating the relative movement when calculating the relative movement. In particular, when robot arm 20 is used for inspecting a welding condition, the photographic information captured by camera unit 24 will have different photographing directions depending on the position of moving arm unit 24. Therefore, when combining the photographic information captured by camera unit 24, which is a line camera, into continuous information, it is necessary to calculate the position of arm unit 24 and correct the photographic information according to the position of arm unit 24. However, the amount of image processing required in this process can be reduced, and the movement can be calculated quickly and easily.

[0034] It goes without saying that the present invention is not limited to the above-described embodiment, and can be embodied in various forms as long as they fall within the technical scope of the present invention.

[0035] For example, in the above-described embodiment, second imaging means 26b is provided at a position other than on the straight line connecting first imaging means 26a and arm unit 22, but first imaging means 26a and second imaging means 26b are preferably located apart. Since the distance between the imaging means 26 increases the difference in the imaging information transmitted from the imaging means 26, even if it is difficult to calculate the position of arm unit 22 from one piece of imaging information, the position of arm unit 22 can be easily calculated by using the other piece of imaging information.

[0036] In the above-described embodiment, the first imaging unit 26a and the second imaging unit 26b are provided as imaging units, but the second imaging unit 26b may be omitted. In this case, steps S130 and S140 in the position calculation processing routine can be omitted, and even in this case, the position can be calculated based on the first imaging information.

[0037] In the above-described embodiment, the imaging means includes first imaging means 26a and second imaging means 26b, but the number of imaging means may be three or more. In this case, by adding steps equivalent to step S130 and step S140 according to the number of imaging means, the same effect as in the above-described embodiment can be obtained.

[0038] In the above-described embodiment, the ridge lines AE, BF, CG, and DH are each colored blue, the ridge lines AB, CD, EF, and GF are each colored red, and the ridge lines AD, BC, EH, and FG are each colored green, so that all of the ridge lines connected to any vertex are colored different colors. However, the colors are not limited to blue, red, and green, and the positions of the blue, red, and green are not limited to these positions; they may be located anywhere, and other colors may be used. Even in this case, the same effects as those of the above-described embodiment can be obtained, but the three colors of blue, red, and green are more preferable because the wavelength ranges of the three colors are significantly different and it is easier to extract regions corresponding to the ridge lines from the imaging information. [Industrial Applicability]

[0039] As shown in the above-described embodiment, the present invention can be used in the field of position detection, particularly as a robot arm capable of detecting a position. [Explanation of symbols]

[0040] 20...Robot arm, 22...Arm portion, 24...Camera unit, 24a...Lens, 26...Photographing means, 26a...First photographing means, 26b...Second photographing means, 30...Control unit, 31...CPU, 32...ROM, 33...RAM, 34...Interface, 35...Bus.

Claims

1. A movable arm; a hexahedral structure attached to the arm, in which ridges connected to any vertices are all colored in different colors so as to be visible; an imaging means for imaging an area including the target structure and the arm and transmitting imaging information; a control means for calculating a position of the arm based on information about the ridgeline included in the photographing information transmitted from the photographing means; characterized in that it comprises Robotic arm.

2. the control means calculates the position of the arm by comparing information about ridge lines included in photographing information obtained by photographing the arm positioned at a reference position with information about ridge lines included in photographing information obtained by photographing the arm by the photographing means. The robot arm of claim 1 .

3. the photographing means comprises a first photographing means for photographing an area including the target structure and the arm and transmitting first photographing information, and a second photographing means for photographing an area including the target structure and the arm and transmitting second photographing information, The control means determines whether the first photographing information includes information about four or more ridge lines, and if it is determined that four or more ridge lines are included, calculates the position of the arm by comparing information about the ridge lines included in photographing information obtained by photographing the arm positioned at a reference position with information about the ridge lines included in the first photographing information, and if it is determined that fewer than four ridge lines are included, calculates the position of the arm by comparing information about the ridge lines included in photographing information obtained by photographing the arm positioned at a reference position with information about the ridge lines included in the second photographing information.

3. The robot arm according to claim 1 or 2.

4. The object to be photographed is a line camera. A robot arm according to any one of claims 1 to 3.

5. A method for controlling a robot arm comprising: a movable arm; a target structure attached to the arm, the target structure being hexahedral in shape, with ridge lines connecting to any vertices all colored in different colors so as to be visible; an imaging means for imaging an area including the target structure and the arm and transmitting imaging information; and a control means for calculating a position of the arm based on information about the ridge lines included in the imaging information transmitted from the imaging means, a position calculation step of calculating a position of the arm based on information about the ridgeline included in the photographing information transmitted from the photographing means; characterized in that it comprises How to control a robot arm.

6. The robot arm control method according to claim 5 is executed by one or more computers. Program for.

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