Movable body control system

Abstract

To obtain a movable body control system that accurately identifies the position of a marker in a picked-up image to cause a movable body to accurately travel along the marker.SOLUTION: In a movable body 1, scanners 12a, 12b optically scan a floor surface to create a floor surface image, and a controller 54 controls a driving device 51 so that the movable body 1 travels along a marker. An image processing unit 54a (a) executes gamma correction on the floor surface image to increase a difference in density between the floor surface and the marker, and (b) identifies the position of the marker in the floor surface image after the gamma correction on the basis of a predetermined threshold. The controller 54 controls the driving device 51 so that the movable body 1 travels along the marker on the basis of the identified position of the marker.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a movement control system.

Background Art

[0002] A certain autonomous driving device captures an image of a driving surface including a driving guide line to obtain an image, and travels along the driving guide line in the obtained image (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As described above, when a linear marker is provided on the floor surface to specify the path of the moving body, the floor density in the captured image differs depending on the state of the floor surface on which the moving body travels. Therefore, the position of the marker in the captured image may not be accurately specified.

[0005] The present invention has been made in view of the above problems, and an object thereof is to obtain a movement control system that accurately specifies the position of a marker in a captured image and accurately causes a moving body to travel along the marker.

Means for Solving the Problems

[0006] The movement control system according to the present invention is a movement control system that controls a moving body to travel along a marker on a floor surface where the marker is set, and includes a driving device that generates a driving force for the traveling of the moving body, a scanner that optically scans the floor surface to generate a floor image, an image processing unit that specifies the position of the marker in the floor image, and a controller that controls the driving device so that the moving body travels along the marker. Then, the image processing unit (a) performs gamma correction on the floor image to expand the density difference between the floor surface and the marker, and (b) specifies the position of the marker in the floor image after the gamma correction based on a predetermined threshold value, and the controller controls the driving device so that the moving body travels along the marker based on the specified position of the marker.

Effect of the Invention

[0007] According to the present invention, a movement control system can be obtained that accurately specifies the position of a marker in a captured image and accurately causes a moving body to travel along the marker.

[0008] The above or other objects, features, and advantages of the present invention will become more apparent from the following detailed description together with the accompanying drawings.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

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Figure 5

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Figure 7

Figure 8

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0011] Embodiment 1.

[0012] FIG. 1 is a perspective view showing an example of a moving body equipped with the movement control system according to the first embodiment. FIG. 2 is a perspective view showing the mechanical configuration of the moving body shown in FIG. 1.

[0013] Here, this movement control system controls the moving body so as to travel along the marker on the floor surface where the marker (such as a linear marker) is set.

[0014] The moving body 1 shown in FIG. 1 is a self-propelled moving body, such as an automatic guided vehicle (AGV) or an autonomous mobile robot (AMR). As shown in FIG. 2, this moving body 1 includes four casters 11 installed at the four corner portions of the bottom surface, scanners 12a and 12b, and a frame body 13 to which the casters 11 and the scanners 12a and 12b are fixed.

[0015] The caster 11 includes a driven wheel that contacts the floor surface and is rotatably fixed to the frame body 13.

[0016] Scanner 12a optically scans the floor surface to generate a first floor surface image. Scanner 12a is disposed at the tip portion of the moving body 1 in the traveling direction. Scanner 12b optically scans the floor surface to generate a second floor surface image. Scanner 12b is disposed at the rear end portion of the moving body 1 in the traveling direction. Each of the scanners 12a and 12b is (a) disposed on the bottom surface side of the moving body 1 facing the floor surface, and (b) repeatedly generates a line image having a predetermined width perpendicular to the traveling direction of the moving body 1 as the first floor surface image or the second floor surface image. Scanners 12a and 12b scan the floor surface at a predetermined high resolution (for example, 600 dpi). Note that one or both of the first floor surface image and the second floor surface image are used as the floor surface image described later.

[0017] The frame body 13 is a body having a frame structure.

[0018] Furthermore, the moving body 1 includes drive wheel units 21a, 21b, 21c, and 21d. Each of the drive wheel units 21a, 21b, 21c, and 21d includes a drive wheel 31 that contacts the floor surface, a support portion 32 that rotatably supports the drive wheel 31, a wheel frame portion 33 to which the support portion 32 is fixed, a rotational support portion 34 that rotatably fixes one end of the wheel frame portion 33 to the frame body 13 (one of the beams 13a and 13b), and a spring member 35 that biases the other end of the wheel frame portion 33 to the frame body 13 (the other of the beams 13a and 13b). Thereby, due to the restoring force of the spring member 35, the drive wheel 31 is pressed against the floor surface with a predetermined pressure.

[0019] Furthermore, each drive wheel unit 21a, 21b, 21c, 21d includes a drive device (not shown) that generates and transmits driving force for traveling to the drive wheel 31. The drive devices are installed independently of the drive wheel units 21a, 21b, 21c, 21d, and individually generate and transmit driving force to the drive wheel 31. Here, the drive device generates driving force with a motor and transmits the driving force to the drive wheel 31 with a gear or the like. The drive wheel 31 includes, for example, a drive shaft connected to the drive device, a rigid wheel fixed to the drive shaft, and an elastic tire fitted outside the wheel.

[0020] FIG. 3 is a diagram showing the configuration of the scanner in the mobile body according to the first embodiment. In the first embodiment, as shown in FIG. 3 for example, each scanner 12a, 12b includes a light emitting unit (not shown) that irradiates light onto the floor surface, an image sensor 41, and a reduction optical system 42 (one or more lenses) that condenses the reflected light obtained by the reflection of the light from the light emitting unit on the floor surface onto the image sensor 41.

[0021] FIG. 4 is a diagram showing another configuration of the scanner in the mobile body according to the first embodiment. The scanners 12a, 12b may include, for example, a contact image sensor as shown in FIG. 4. In that case, the scanners 12a, 12b are scanners of an equal magnification optical system including a line sensor 41a including a plurality of light receiving elements and a lens array 42a.

[0022] FIG. 5 is a perspective view showing the electrical configuration of the mobile body 1 shown in FIG. 1. As shown in FIG. 5, the mobile body 1 includes, in addition to the above-described drive device 51, a power supply device 52, a communication device 53, and a controller 54.

[0023] The power supply device 52 incorporates, for example, a secondary battery and supplies power to the drive device 51, the communication device 53, and the controller 54. Note that the power supply device 52 may be connected to a commercial power supply and include a charging circuit for charging the secondary battery. Also, the secondary battery may be detachable. The communication device 53 performs data communication with an external device (such as the management server 2 described later) via wireless communication according to a predetermined communication protocol.

[0024] The controller 54 includes a computer or an ASIC (Application Specific Integrated Circuit) and performs data processing, control of the drive device 51, control of the communication device 53, etc. using the computer (software processing) or the ASIC (hardware processing).

[0025] In the first embodiment, the controller 54 includes an image processing unit 54a.

[0026] The image processing unit 54a identifies the position of the marker in the floor image described above, and the controller 54 controls the drive device 51 so that the moving body 1 travels along the marker.

[0027] FIG. 6 is a diagram showing an example of the floor surface. For example, as shown in FIG. 6, a linear marker 111 (such as a tape) indicating a path and a marker 111a indicating a stop position are installed on the floor surface 101. Then, the controller 54 detects the edge of the image of the marker 111 in the floor image, derives the deviation from the path in the direction perpendicular to the traveling direction based on the position of the edge in the floor image, and derives the inclination of the traveling direction with respect to the path based on the inclination of the edge, and controls the drive device 51 so as to reduce the deviation and the inclination.

[0028] Note that when the rotational speeds of the drive wheels 31 of the drive wheel units 21a and 21b are made the same as those of the drive wheels 31 of the drive wheel units 21c and 21d, the moving body 1 moves straight. When the rotational speeds of the drive wheels 31 of the drive wheel units 21a and 21b are made different from those of the drive wheels 31 of the drive wheel units 21c and 21d, the moving body 1 turns. Therefore, the controller 54 specifies the deviation of the position of the specified marker from the reference value, and controls the drive devices 51 of the drive wheel units 21a, 21b, 21c, and 21d so as to reduce the specified deviation. Further, when the controller 54 detects the image of the marker 111a in the floor image by pattern matching or the like, it controls the drive device 51 to stop the moving body 1.

[0029] FIG. 7 is a diagram for explaining the image processing in the image processing unit 54a in FIG. 5.

[0030] Furthermore, as shown in FIG. 7 for example, the image processing unit 54a (a) performs gamma correction to expand the density difference between the floor surface and the marker on the floor image, and (b) specifies the position of the marker in the floor image after gamma correction based on a predetermined threshold value. The controller 54 controls the drive device 51 so that the moving body 1 travels along the marker based on the specified position of the marker. Note that the density of the marker is different from that of the floor surface. Here, as shown in FIG. 7 for example, the image processing unit 54a (a) generates a differential image (spatial differential image along the main scanning direction) of the floor image after gamma correction, and (b) compares the differential image with the above-mentioned threshold value to specify the position of the marker in the floor image after gamma correction. That is, the edge of the marker is detected in the differential image, and the position of the marker is specified based on the position of the edge.

[0031] Here, for example, the above-mentioned threshold value is set by a discriminant analysis method. That is, the distributions (histograms) of the floor surface density and the marker density are measured in advance, and the above-mentioned threshold value is set by the discriminant analysis method based on the distributions. Also, the characteristics of the gamma correction are set based on the distributions of the floor surface density and the marker density.

[0032] Next, the operation of the movement control system according to Embodiment 1 will be described.

[0033] In the moving body 1, when the controller 54 detects a user operation on an input device (such as a switch) (not shown) or receives a start command via the communication device 53, it controls the drive device 51 to start the running of the moving body 1.

[0034] Then, the scanner 12a (and the scanner 12b) repeatedly generates a floor image (line image), and the image processing unit 54a performs gamma correction or the like on the floor image as described above, specifies the position of the marker in the gamma-corrected floor image using the threshold value set as described above, and the controller 54 specifies the deviation of the current position of the moving body 1 from the path (marker), and controls the drive device 51 to reduce the deviation and continue the running of the moving body 1.

[0035] Further, when the controller 54 determines based on the floor image that the current position of the moving body 1 is the stop position, it stops the drive device 51 to stop the moving body 1.

[0036] As described above, according to the above Embodiment 1, in the moving body 1, the scanners 12a and 12b optically scan the floor to generate a floor image, and the controller 54 controls the drive device 51 so that the moving body 1 runs along the marker. Then, the image processing unit 54a (a) performs gamma correction on the floor image to expand the density difference between the floor and the marker, (b) specifies the position of the marker in the gamma-corrected floor image based on a predetermined threshold value, and the controller 54 controls the drive device 51 so that the moving body 1 runs along the marker based on the specified position of the marker.

[0037] Thereby, since the position of the marker in the captured image is accurately specified corresponding to the floor density and the marker density, the moving body 1 accurately runs along the marker.

[0038] Embodiment 2

[0039] FIG. 8 is a block diagram showing the configuration of the movement control system according to Embodiment 2. In Embodiment 2, an image processing unit 71 similar to the image processing unit 54a in Embodiment 1 is provided in a management server 2 capable of communicating with the moving body 1. Note that the moving body 1 in Embodiment 2 is not provided with the image processing unit 54a.

[0040] The management server 2 in FIG. 8 includes a communication device 61, an arithmetic processing device 62, and a storage device 63.

[0041] The communication device 61 performs data communication with the moving body 1 via a predetermined communication path 3 (wireless communication path and / or wired communication path). For example, the communication device 61 is a wireless network interface, a data communication interface for a mobile phone network, a short-range wireless communication interface, or the like. Further, even if the communication path 3 includes a wireless station, the communication device 61 is connected to the wireless station via a wired communication path and the moving body 1 is connected to the wireless station via a wireless communication path, the communication device 61 may be capable of performing data communication with the moving body 1.

[0042] The arithmetic processing device 62 is a computer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc., and operates as various processing units by loading a program from the ROM or the storage device 63 into the RAM and executing it with the CPU. Here, the arithmetic processing device 62 operates as the image processing unit 71.

[0043] The storage device 63 is a non-volatile storage device that stores programs and data. Here, threshold data 63a is stored in the storage device 63 in advance.

[0044] The threshold data 63a is data indicating a threshold for marker detection set in advance for each position on the floor surface. Note that the threshold for each position is set according to the density of each position on the floor surface.

[0045] In Embodiment 2, the image processing unit 71: (a) acquires a floor image from the moving body 1 using the communication device 61; (b) performs the above-described gamma correction on the acquired floor image; (c) identifies the position of the marker in the gamma-corrected floor image based on a predetermined threshold; and (d) notifies the moving body 1 of the position using the communication device 61. In the moving body 1, the controller 54 receives the notification of the position of the marker and controls the drive device 51 so that the moving body 1 travels along the marker based on the position of the marker.

[0046] Furthermore, in Embodiment 2, the image processing unit 71: (a) identifies the current position of the moving body 1; (b) refers to the threshold data 63a to identify the threshold corresponding to the current position of the moving body 1; and (c) identifies the position of the marker in the gamma-corrected floor image based on the identified threshold.

[0047] Regarding the current position of the moving body 1, for example, a position marker indicating the position is included in the marker 111, and the image processing unit 71 identifies the current position by identifying the position marker in the floor image.

[0048] Note that since the other configurations and operations of the movement control system according to Embodiment 2 are the same as those of Embodiment 1, the description thereof is omitted.

[0049] Embodiment 3.

[0050] In Embodiment 3, the threshold data 63a and the image processing unit 71 of Embodiment 2 are mounted on the moving body 1 according to Embodiment 1 to identify the above-described threshold corresponding to the current position of the moving body 1.

[0051] Note that since the other configurations and operations of the movement control system according to Embodiment 3 are the same as those of Embodiment 1 or 2, the description thereof is omitted.

[0052] It should be noted that various changes and modifications to the above-described embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the subject matter and without diminishing the intended advantages. That is, it is intended that such changes and modifications be included within the scope of the claims.

Industrial Applicability

[0053] The present invention is applicable to, for example, an AGV.

Explanation of Signs

[0054] 1 Moving body 2 Management server 51 Driving device 54 Controller 54a, 71 Image processing unit

Claims

1. In a movement control system that controls a moving body to travel along a marker on a floor surface where the marker is set, a driving device that generates a driving force for the traveling of the moving body; a scanner that optically scans the floor surface to generate a floor surface image; an image processing unit that specifies the position of the marker in the floor surface image; a controller that controls the driving device so that the moving body travels along the marker, wherein the image processing unit: (a) performs gamma correction for expanding the density difference between the floor surface and the marker on the floor surface image; (b) specifies the position of the marker in the floor surface image after the gamma correction based on a predetermined threshold value; and the controller controls the driving device so that the moving body travels along the marker based on the specified position of the marker. A movement control system characterized by the above.

2. The movement control system according to claim 1, wherein the threshold value is set by a discriminant analysis method.

3. The threshold value is preset for each position of the floor surface, and the image processing unit: (a) specifies the threshold value corresponding to the current position of the moving body; (b) specifies the position of the marker in the floor surface image after the gamma correction based on the specified threshold value. The movement control system according to claim 1, characterized by the above.

4. The image processing unit: (a) generates a differential image of the floor surface image after gamma correction; (b) compares the differential image with the threshold value to specify the position of the marker in the floor surface image after the gamma correction. The movement control system according to any one of claims 1 to 3, characterized by the above.

Images