JP2018005365A - Position detection landmark and moving body position detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position detection landmark that can be easily and accurately detected thanks to image processing, and to provide a moving body position detection method that is hardly affected by an environment, using the position detection landmark.SOLUTION: A plurality of position detection landmarks (a mark 10), which serves as a reference of position detection of a moving body, is a sheet-like landmark, respectively, and is configured to: have a plurality of small areas 11, respectively in a vertical direction and lateral direction, in which a pattern of presence or absence of a retroreflection member in the plurality of small areas is different in a plurality of marks,; and have a notch part 15 that has the retroreflection member cut out only in one part of a contour of respective areas. The presence or absence of the retroreflection member in the small area is denoted as an identification number of the mark, in association with a numerical value in the binary system.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a position detection landmark serving as a reference for position detection of a moving body such as a robot, and a position detection method of the moving body using the position detection landmark.

  In a system that moves a moving body such as a robot or a transport vehicle within a certain area, it is necessary to detect the current position of the moving body. For example, in the past, the applicant created route information for moving a robot by a simple operation of inputting a route using a pointing device on a map image displayed on the display of a management terminal, and wirelessly A system for moving a robot along a route by transmitting an instruction signal to the robot via a communication network has been proposed (see Patent Document 1). Even in this system, it is necessary to detect the coordinates of the current position of the robot that changes as the robot moves.

  In Patent Document 1, a plurality of basic principles of a method of detecting the coordinates of the current position of the robot are listed, and there is a method of using a landmark among them. In this case, a landmark is set in a facility where a robot is moved and used as a reference point. The robot takes an image with the camera in the course of movement, and transmits the imaging data to the management-side control means. The management-side control means performs image processing on the imaging data, and calculates a relative position between the landmark and the robot in the imaging when the landmark is extracted from the imaging. As a result, the absolute coordinates of the current position of the robot can be known based on the absolute coordinates of the landmark which is the default value.

  The basic principle of position detection using a landmark is as described above, but there are various difficulties in actually detecting the position of a moving object using a landmark. For example, a large number of landmarks are installed in a region where the moving body is moved. Therefore, there is a problem of how to provide each landmark with information for identifying each of a large number of landmarks. As the number of landmarks increases, the identification information may become more complicated. However, the identification information must be easily and accurately read by image processing. In addition, a large number of miscellaneous objects existing in the environment are captured in the image captured by the moving body with the camera. Therefore, during image processing, there is a possibility that the landmark cannot be distinguished from other articles, or other articles may be mistaken for landmarks.

JP, 2015-001810, A

  Therefore, in view of the above circumstances, the present invention uses a position detection landmark that can be easily and accurately detected by image processing, and the position detection landmark, in order to use as a reference for position detection of a moving object. An object of the present invention is to provide a method for detecting the position of a moving object that is not easily affected by the environment.

In order to solve the above problems, the landmark for position detection according to the present invention is:
“A plurality of position detection landmarks that serve as a reference for detecting the position of a moving object,
Each of the sheet-like shapes has a plurality of small areas in the vertical direction and the horizontal direction, and the pattern of the presence or absence of the retroreflective material in the plurality of small areas is different in the plurality of position detection landmarks,
Only at one location of each contour has the notched portion in which the retroreflective material is notched ”.

The position detection landmark (hereinafter, also simply referred to as “mark”) having this configuration can be used in the following position detection method for a moving object. That is,
“Projecting light outside the wavelength range of visible light from the moving object, and extracting the image of the position detection landmark from the image acquired by the camera corresponding to the wavelength of the projected light,
Using the notch as a reference, a digit is assigned to the plurality of small areas, and the presence or absence of the retroreflective material in the plurality of small areas is made to correspond to a numerical value in binary, and the identification number of the position detection landmark is detected. And
The relationship between the traveling direction of the moving body and the direction of the position detection landmark is detected using the notch as a reference. "

  In this moving body position detection method (hereinafter sometimes simply referred to as “position detection method”), the presence or absence of a retroreflective material is made to correspond to a binary numerical value. This gives the mark an identification number that can identify a very large number of marks, despite the simple configuration of different patterns for the presence or absence of retroreflective material in a small area arranged vertically and horizontally. can do.

  In addition, in the notch part provided only at one place on the outline of the mark, the two functions of the reference for converting the pattern of the presence or absence of the retroreflective material in the small area into a numerical value by the binary system and the reference of the direction of the mark are provided. This also realizes a position detection landmark having a plurality of types of information with a simple configuration.

  Furthermore, when projecting light from a moving body onto a mark and taking a reflected image of the mark with a camera, light having a wavelength outside the wavelength region of visible light is used. Accordingly, it is possible to reduce the possibility that the mark extraction accuracy is lowered due to the influence of the image processing of the image pickup by various articles existing in the environment, and the mark can be accurately detected. Further, since the mark is detected without using visible light, there is an advantage that no illumination is required for detecting the mark even at night or when the illuminance is low.

  As described above, as an effect of the present invention, the position detection landmark that can be detected simply and accurately by image processing and the position detection landmark are used in order to serve as a reference for position detection of the moving object. It is possible to provide a method for detecting the position of a moving object that is not easily affected by the environment.

(A), (b) Explanatory drawing of a structure common to a plurality of marks, and (c) to (f) illustrating examples of marks having different identification numbers for the position detection landmark according to the embodiment of the present invention. It is. It is a figure which shows installation of the mark to a facility. It is explanatory drawing of the map image and mark registration screen which were displayed on the display of the management terminal. (A) It is explanatory drawing of imaging | photography of the landmark for position detection by a mobile body, (b) It is explanatory drawing of the imaging | photography range. (A)-(d) It is the figure (left figure) which shows an imaging | photography range, and the figure (right figure) which shows imaging about the case where the position of the moving body in a plant | facility is the same, but the advancing direction of a moving body differs. It is explanatory drawing of the procedure which detects the coordinate of a moving body from (a)-(d) imaging. (A), (b) It is a figure which illustrates the landmark for position detection of other embodiment from which the shape of a small area | region and a notch part differs.

  Hereinafter, a position detection landmark 10 (hereinafter sometimes simply referred to as “mark 10”) and a position detection method of a moving body 20 using the mark 10 according to an embodiment of the present invention will be described with reference to FIGS. This will be described with reference to FIG.

  The position detection method of this embodiment uses a plurality of marks 10. Each of the plurality of marks 10 has a sheet shape, has a plurality of small regions 11 in the vertical direction and the horizontal direction, and has a notch 15 in which the retroreflective material becomes discontinuous only at one position of the contour. have. The plurality of marks 10 have the same outer shape and the same shape and number of small regions 11, but the patterns of presence or absence of retroreflective material in the small regions 11 are different.

  Furthermore, in the present embodiment, one mark 10 is formed of a single retroreflective sheet, and the small region 11 that does not have a retroreflective material among the plurality of small regions 11 and the notch portion 15 are recursive. The reflection sheet is formed by cutting.

  More specifically, as shown in FIG. 1A, the mark 10 is formed by cutting one corner out of the four corners of a square into a square, and the remaining part by cutting is a notch. 15. The small regions 11 arranged in the vertical direction and the horizontal direction have the same shape, and are square in this embodiment. Here, there are four rows of small regions 11 per mark 10 in the vertical direction, and there are 15 small regions 11 in total, four from the first row to the third row and three in the fourth row. Illustrated.

The identification numbers for identifying the plurality of marks 10 are obtained by associating the presence / absence of the retroreflective material in the plurality of small regions 11 with numerical values in a binary system. In converting the presence / absence of the retroreflecting material into a binary numerical value, digits are assigned to the plurality of small regions 11 with the notch 15 as a reference. For example, as shown in FIG. 1B, the small area 11 located on the diagonal of the notch 15 is set as the first digit, and digits are assigned so that the number of digits increases in the same direction. When the notch 15 is set to the upper right in the drawing, if the digits are assigned so that the number increases toward the right and above, the mark 10 in FIG. 1 (c) has four digits, five digits, six digits, A retroreflective material is provided in the small region 11 of the 10th and 15th digits. When the retroreflecting material “present” is “1” and the retroreflecting material “absent” is “0”, the pattern in FIG. 1C is converted to a binary number, 2 ³ +2 ⁴ +2 ⁵ +2 ⁹ +2 ¹⁴ = 16952. That is, the identification number of the mark in the pattern of FIG. 1C is “16952”.

  When the number of small regions 11 is 15 as in this embodiment, 32768 patterns can be displayed depending on the presence or absence of a retroreflective material. The number of small areas 11 is not limited to 15, but is set according to the number of required marks, that is, the number of marks to be identified.

  As shown in FIGS. 1D, 1E, and 1F, if there is no notch 15, the notch 15 is formed even if it is a mark 10 in which the pattern of the presence or absence of the retroreflecting material looks the same. By assigning digits to a plurality of small areas 11 as a reference, different identification numbers can be assigned. Here, when digits are assigned as shown in FIG. 1B, when the pattern of the mark 10 in FIGS. 1D, 1E, and 1F is converted into an identification number, “15115” and “12475”, respectively. , And “20701”.

  The notch 15 serves as a reference for the orientation of the mark 10 in addition to being a reference for converting the pattern of the presence or absence of the retroreflecting material into a numerical value (identification number) by a binary system. In the present embodiment, as indicated by an arrow in FIG. 1B, the upward direction when the cutout portion 15 is located at the upper right in the drawing is the direction of the mark 10.

  Next, a position detection method using the mark 10 having the above configuration will be described. In the position detection method, the current position of the moving body 20 moving in the facility 30 is detected by a management terminal (not shown) as it moves. The mobile unit 20 and the management terminal perform wireless communication in both directions via the wireless communication network.

  The management terminal is configured by a general-purpose computer mainly including a main storage device, an auxiliary storage device, a processor, and a communication device that performs wireless communication as a hardware configuration, and an input device including a keyboard and a pointing device; An output device including a display is provided. The main storage device includes at least a management-side wireless communication unit that performs wireless communication with the mobile unit 20 via a wireless communication network, a map display unit that displays a map image 50 on a display, and an imaging 40 transmitted from the mobile unit 20. A program that causes a computer to function as image processing means for image processing, current position detection means for detecting the current position of the moving body 20 based on the result of image processing, and coordinate updating means for updating the coordinates of the current position of the moving body 20 It is remembered.

  The moving body 20 is provided with a projection unit (not shown) for projecting light upward and a camera 21 for photographing the upper part. In the present embodiment, an LED that projects light in the infrared wavelength region (940 nm) is used as the projection unit, and the camera 21 is compatible with light in the wavelength region including infrared rays (750 nm to 950 nm). . In addition, a microcomputer including a main storage device, an auxiliary storage device, a processor, and a communication device that performs wireless communication is stored inside the main body of the moving body 20. Based on at least a mobile-side wireless communication unit that performs wireless communication with the management terminal, an imaging transmission unit that transmits data of the imaging 40 acquired by the camera 21 to the management terminal, and an instruction signal from the management terminal. A program that causes a microcomputer to function as a drive device such as a motor or a drive control unit that manages battery power is stored.

  Prior to the movement of the moving body 20, the mark 10 is attached to the ceiling 31 of the facility 30 to which the moving body 20 is moved. At this time, the direction of the mark 10 need not be taken into consideration. For example, as shown in FIG. 2, a plurality of marks 10 having different identification codes are pasted on the ceiling 31 of the space where the moving body 20 is moved in the facility 30. FIG. 2 is a bird's-eye view of the facility 30 as viewed from directly above, and shows the mark 10 viewed from the back side through the ceiling 31.

  On the other hand, the map image 50 of the facility 30 to which the moving body 20 is moved is created. For example, a printed sketch such as a design drawing of the facility 30 is converted into electronic data by a scanner and used as data of the map image 50. In creating the map image 50, the aspect ratio of the original sketch must be equal to the aspect ratio of the real space. The generated map image 50 data can be stored in the storage device of the management terminal.

  The above map image 50 is read by a program stored in the main storage device of the management terminal and displayed on the display as shown in FIG. The distance in the vertical direction or the horizontal direction of the real space is input in correspondence with the length in the vertical direction or the horizontal direction in the map image 50 displayed on the display. Thereby, the coordinates in the map image 50 displayed on the display are associated with the two-dimensional coordinates in the real space.

  As described above, for the mark 10 installed in the facility 30, a mark coordinate database in which the coordinates (coordinates in the real space) are associated with the identification number is created. In the present embodiment, a mark coordinate database can be created by the management terminal. Specifically, as shown in FIG. 3, after displaying the map image 50 on the display of the management terminal, the landmark registration screen 55 is displayed, and for each mark 10 actually installed, the identification number and the actual number are displayed. Enter coordinates in space. Thereby, the mark coordinate database is created, the coordinates in the real space are converted into the coordinates in the map image 50, and the icon 51 indicating the mark 10 is displayed on the map image 50 of the display.

When the moving body 20 is moved in the facility 30, the moving body 20 performs shooting by the camera 21 at a predetermined timing such as a predetermined time interval. As shown in FIG. 4, when the distance from the camera 21 to the mark 10 is h, and the angle of view of the camera 21 is α degrees in the horizontal direction and β degrees in the vertical direction, the horizontal size Lw and the vertical direction of the shooting range 35 are set. The size Lh of is as follows. A line La in FIG. 4 is the optical axis of the camera 21.
Lw = h × tan (α / 2) × 2
Lh = h × tan (β / 2) × 2

  Data of the imaging 40 acquired by the camera 21 is transmitted to the management terminal, and image processing is performed. If the mark 10 exists in the imaging range 35, the mark image 41 in which the infrared light projected from the moving body 20 is reflected by the retroreflective material of the mark 10 is extracted from the imaging 40. The extraction of the mark image 41 can be performed based on binarization of the imaging 40, for example. By analyzing the pattern of the presence or absence of the retroreflective material in the small area 11 with respect to the extracted mark image 41 with the notch 15 as a reference, the identification number of the photographed mark 10 can be obtained. Thereby, the coordinate in the real space of the mark 10 image | photographed from the mark coordinate database is known. Therefore, the coordinates of the moving body 20 in the real space can be detected from the relative coordinates of the mark image 41 with respect to the camera center P in the imaging 40 and the coordinates of the mark 10 in the real space.

  More specifically, the imaging 40 captured by the camera 21 differs depending not only on the position of the moving body 20 but also on the traveling direction of the moving body 20 at that time, that is, the direction of the camera 21. For example, when the moving body 20 is in the position shown in FIG. 2 in the facility 30, if the moving direction of the moving body 20 is different, the shooting range 35 and the imaging 40 by the camera 21 are shown in FIGS. Will be different. Here, in each of FIGS. 5A to 5D, the left figure is a partially enlarged view of FIG. 2 in which the third chamber of the facility 30 is viewed from directly above, and a triangular symbol indicating the traveling direction of the moving body 20 is provided. It is attached. Each of the right diagrams of FIGS. 5A to 5D shows the imaging 40 photographed by the moving body 20 moving in the direction of the left diagram so that the moving direction of the moving body 20 is a downward direction in the drawing. It is. The traveling direction of the moving body 20 is south in FIG. 5 (a), east in FIG. 5 (b), north in FIG. 5 (c), and northwest in FIG. 5 (d).

As shown in FIG. _6A , the relative coordinates (x _r , y _r ) of the center of the mark image 41 with respect to the camera center P can be obtained from the imaging 40 as described above. At the same time, an angle θ formed by the moving direction of the moving body 20 with respect to the direction of the mark 10 can be known from the imaging 40.

Here, the imaging 40 is an image obtained by looking up from the lower side of the mark 10 attached to the ceiling 31, whereas the coordinates of the mark 10 in the mark coordinate database are the coordinates when the facility 30 is viewed from directly above. is there. Therefore, when the imaging 40 photographed by looking up from below is converted into a state seen from directly above, the relative coordinates of the mark image 41 with respect to the camera center P are (x _r , -y _r ) as shown in FIG. )

Then, in order to make the coordinate axis in the imaging 40 coincide with the coordinate axis in the map image 50 (and eventually the coordinate axis in the real space), as shown in FIG. 6C, relative coordinates (x _r , -Y _r ) is rotated. The relative coordinates (x _t , y _t ) after rotation are as follows.
x _t = x _r · cos θ − (− y _r ) sin θ
y _t = x _r · sin θ + (− y _r ) cos θ

If the size of the image capturing 40 is x pixels in the horizontal direction and y pixels in the vertical direction, the relative coordinates (x _t , y _t ) in the image capturing 40 are converted into coordinates in units of length in real space using the above Lw and Lh. When converted, (x _t (Lw / x), y _t (Lh / y)) is obtained (see FIG. 6D).

Accordingly, when the coordinates in the real space of the mark 10 specified by the identification number determined by the above image processing are (X, Y), the current coordinates (x _p , y _p ) of the moving body 20 in the real space are It is detected as follows.
x _p = X−x _t (Lw / x)
y _p = Y−y _t (Lh / y)
The detected current coordinates (x _p , y _p ) are stored in the storage device of the management terminal. In addition, the current coordinates in the map image 50 are calculated from the current coordinates (x _p , y _p ) in the real space, and the position of an icon (not shown) representing the moving body 20 on the map image 50 is calculated based on the calculation result. Updated.

  As described above, according to the present embodiment, since the presence / absence of the retroreflective material is made to correspond to the numerical value by the binary system, the pattern of the presence / absence of the retroreflective material in the small region 11 arranged vertically and horizontally is represented by a plurality of marks 10. In spite of the simple configuration of differentiating, an identification number that can identify an extremely large number of marks 10 can be given to the marks.

  Further, the notch 15 provided only at one position of the outline of the mark 10 is used as a reference when converting the pattern of the presence or absence of the retroreflective material in the small region 11 into a numerical value by the binary system, and in the direction of the mark 10. By using it as a reference, the mark 10 having a simple configuration has a plurality of types of information.

  Even if some of the small regions 11 arranged vertically and horizontally are colored or color-coded, it is possible to make the pattern correspond to a numerical value (identification number) by a binary system. However, in this case, the mark 10 is shot with the camera 21 corresponding to visible light, and the mark 10 is detected from the imaging 40 such that other articles are misidentified as the mark 10 due to the influence of various articles existing in the environment. There is a risk that the accuracy of extracting the will decrease. On the other hand, in the mark 10 of this embodiment, the pattern of the presence or absence of the retroreflective material in the small region 11 is made to correspond to the numerical value by the binary method, and the image in which the infrared ray is reflected by the mark 10 is photographed. The mark 10 can be accurately detected without being disturbed. Moreover, since it is detection by infrared rays, it has an advantage that illumination is not required for detection of the mark 10 even at night or when the illuminance is low.

  In addition, it is conceivable that a retroreflective material cut to the size of the small region 11 is pasted on the mount to form a mark, whereas in the present embodiment, one mark 10 is formed by one retroreflective sheet. In addition, the retroreflective sheet is cut off in the small area 11 and the notch 15 that do not have the retroreflective material. By setting it as such a structure, since the outline by a retroreflective material can be formed easily, the notch part 15 by which the retroreflective material is notched in the outline can be formed easily.

  The present invention has been described with reference to the preferred embodiments. However, the present invention is not limited to the above-described embodiments, and various improvements can be made without departing from the scope of the present invention as described below. And design changes are possible.

  For example, the case where the light of the wavelength in the infrared region is projected from the moving body 20 and the image of the mark 10 that reflects the light is captured by the camera 21 is exemplified. If it does, the light projected from the moving body 20 is not limited to infrared rays, but may be ultraviolet rays. Moreover, the camera 21 should just contain the wavelength of the light projected on the range of the wavelength of the light made into imaging | photography object, and may contain the wavelength range of visible light in the range of the wavelength of the light made into imaging | photography object. Absent.

Moreover, although the case where the data of the imaging 40 acquired with the camera 21 of the moving body 20 is transmitted to the management terminal and the imaging processing is performed on the management terminal side is illustrated above, the image of the imaging 40 on the moving body 20 side is illustrated. It is good also as processing. For example, the imaging 40 is processed by the microcomputer of the moving body 20, the mark image 41 is extracted to identify the identification number, and the relative coordinates (x _r , y _r ) and the angle θ are detected, and then these The data can be transmitted to the management terminal, and the subsequent processing for obtaining the current coordinates (x _p , y _p ) can be performed by the management terminal. Alternatively, all the processing from the image processing of the imaging 40 until the final determination of the current coordinates (x _p , y _p ) is performed on the mobile unit 20 side, and then the current coordinates (x _p , y _p ) are transmitted to the management terminal. It can be set as the structure to do.

  Furthermore, although the case where the small area 11 in the mark 10 is a quadrangle (square) is illustrated above, the shape of the small area 11 is not particularly limited, and is shown in FIGS. 7A and 7B, respectively. In addition, the small region 11 can be a triangle or a circle. Moreover, although the case where the corner of the retroreflective sheet is cut into a square to form the notch 15 is illustrated above, the corner is triangular or circular as shown in FIGS. 7 (a) and 7 (b). The cutout portion 15 can be formed by cutting it out.

10 mark (landmark for position detection)
11 Small area 15 Notch 20 Moving body 21 Camera 40 Imaging 41 Mark image (image of landmark for position detection)

Claims (2)

A plurality of position detection landmarks serving as a reference for detecting the position of the moving object,
Each of the sheet-like shapes has a plurality of small areas in the vertical direction and the horizontal direction, and the pattern of the presence or absence of the retroreflective material in the plurality of small areas is different in the plurality of position detection landmarks,
A position detection landmark having a cutout portion in which the retroreflective material is cut out only at one position of each contour. A method for detecting a position of a moving object using the landmark for position detection according to claim 1,
Projecting light outside the wavelength range of visible light from the moving body, and extracting the image of the position detection landmark from the image acquired by the camera corresponding to the wavelength of the projected light,
Using the notch as a reference, a digit is assigned to the plurality of small areas, and the presence or absence of the retroreflective material in the plurality of small areas is made to correspond to a numerical value in binary, and the identification number of the position detection landmark is detected. And
A method for detecting a position of a moving body, wherein a relationship between a traveling direction of the moving body and an orientation of a landmark for position detection is detected using the notch as a reference.

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