Traveling vehicle system and method for detecting displacement amount of marker

Abstract

To provide a traveling vehicle system capable of detecting the amount of deviation of a marker without using a special device.SOLUTION: The present invention is a traveling vehicle system (1) that includes a traveling vehicle (2), a plurality of markers (4) provided on a floor surface, a reading sensor capable of reading a plurality of markers (18), and a controller (6). The controller is provided with a position calculating unit (6b) for calculating the current position and angle of a traveling vehicle based on a detection signal obtained by reading a first marker; a traveling control unit (6c) for causing the traveling vehicle to travel to a second marker based on the calculated position and angle; a deviation amount calculation unit (6d) for detecting a deviation amount of the second marker in the horizontal direction by reading the second marker, and, based on this, calculating the deviation amount of an angular position of the first marker; and a deviation amount storage unit (6e) for storing the deviation amount of the angular position of the first marker.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a traveling vehicle system, and more particularly to a traveling vehicle system for automatically driving a traveling vehicle based on markers provided on a floor surface, and a method for detecting a deviation amount of the markers.

Background Art

[0002] Japanese Patent Application Laid-Open No. 1-197809 (Patent Document 1) describes a mark for guiding an unmanned vehicle. The unmanned vehicle described in this Patent Document 1 photographs a mark provided on the ceiling surface of a building with a camera provided on the unmanned vehicle, and recognizes the current position and traveling direction of the unmanned vehicle based on the photographed mark.

[0003] Japanese Patent Application Laid-Open No. 2018-534691 (Patent Document 2) describes automatic fault diagnosis and recovery of a machine. In the invention described in Patent Document 2, markers are provided on the floor surface, and a robot travels in an area using these markers. Further, position indices of the markers are acquired, and by processing the acquired position indices, an offset of the position of the markers and an angular offset with respect to a reference position and an angle are calculated.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, there is a problem that it is difficult to arrange and orient markers provided for running a driverless vehicle or the like with sufficient position accuracy and angular position accuracy. Usually, markers provided on the floor surface or the like for running a driverless vehicle are installed by drawing a marking line on the floor surface or the like and having an operator stick the markers one by one to the floor surface or the like according to this marking line. Thus, since the installation of the markers is generally performed by manual work, there is a problem that the installation position includes unavoidable errors. If there is an error in the installation position of the marker, the travel route of the driverless vehicle traveling based on the detected position and angle of the marker is also affected by this. As a result, the driverless vehicle will travel on a route deviated from the planned travel route, which may lead to a decrease in the running stability of the driverless vehicle and the conveyance efficiency by the driverless vehicle.

[0006] Here, Patent Document 2 describes creating an initial marker offset table for the marker to be installed and adjusting the travel route based on this. That is, in the invention described in Patent Document 2, a reference machine is used to establish the initial marker offset table. This reference machine is equipped with an absolute positioning system that is not incorporated into a general machine (traveling vehicle) and has an accurate dead reckoning (odometry) system.

[0007] However, in the invention described in Patent Document 2, although the initial marker offset table can be established, there is a problem that a special reference machine different from a normal traveling vehicle is required to create this. If each traveling vehicle system is equipped with such an expensive reference machine used only for creating the initial marker offset table, there is a problem that the traveling vehicle system becomes costly. Also, if the reference machine is shared by a plurality of traveling vehicle systems, every time the position of the marker is changed or the marker is replaced, it is necessary to carry in the reference machine from the outside to measure the offset of the marker, and there is a problem that maintenance takes time.

[0008] Accordingly, an object of the present invention is to provide a traveling vehicle system and a method for detecting a deviation amount of a marker that can detect the deviation amount of the marker without using a special device. **Means for Solving the Problems**

[0009] In order to solve the above-described problems, the present invention is a traveling vehicle system for automatically traveling a traveling vehicle based on markers provided on a floor surface, including a traveling vehicle capable of traveling on the floor surface, a plurality of markers provided on the floor surface on which the traveling vehicle travels, a reading sensor provided on the traveling vehicle and capable of reading the plurality of markers, and a controller for controlling the traveling vehicle. The controller includes a position calculation unit that calculates the current position and angle of the traveling vehicle based on a detection signal acquired by the reading sensor by reading a first marker among the plurality of markers, a traveling control unit that causes the traveling vehicle to travel to a second marker provided adjacent to the first marker based on the position and angle of the traveling vehicle calculated by the position calculation unit, a deviation amount calculation unit that detects a deviation amount in the left-right direction of the second marker by reading the second marker with the reading sensor and calculates a deviation amount in the angular position of the first marker based on the deviation amount in the left-right direction, and a deviation amount storage unit that stores the deviation amount in the angular position of the first marker calculated by the deviation amount calculation unit.

[0010] In the present invention configured as described above, the reading sensor provided on the traveling vehicle reads a plurality of markers provided on the floor surface, and the controller controls the traveling of the traveling vehicle. The position calculation unit of the controller calculates the current position and angle of the traveling vehicle based on the detection signal of the first marker acquired by the reading sensor, and the traveling control unit causes the traveling vehicle to travel to the second marker based on the calculated position and angle. The deviation amount calculation unit detects the deviation amount in the left-right direction of the second marker and calculates the deviation amount in the angular position of the first marker based on the deviation amount in the left-right direction, and the calculated deviation amount is stored in the deviation amount storage unit.

[0011] According to the present invention configured as described above, since the amount of deviation in the angular position of the first marker can be calculated based on the amount of deviation in the horizontal direction of the detected second marker, the amount of deviation in the angular position of the marker can be detected without using a special device. Here, in the installation of the marker, generally, an offset due to the parallel movement of the marker and an error in the rotational position of the marker occur. The inventor of the present case has found that the error occurring in the installation of the marker is within an acceptable range with respect to the offset of the marker, while the error regarding the rotational position of the marker tends to increase, and this error in the rotational position has an adverse effect on the accurate running of the traveling vehicle. That is, by detecting the amount of deviation after traveling from one marker to a position where the adjacent marker is arranged, a small angular deviation amount can be detected as a large positional deviation amount. Therefore, based on the amount of deviation in the horizontal direction of the traveling vehicle that has reached the second marker from the first marker, the amount of deviation in the angular position of the marker can be detected with sufficient accuracy without using a special measuring device with high precision.

[0012] In the present invention, preferably, the deviation amount calculation unit also uses the detection signal of a third marker that is different from the second marker and is provided adjacent to the first marker and is acquired by the reading sensor to calculate the amount of deviation in the angular position of the first marker.

[0013] According to the present invention configured as described above, since the amount of deviation in the angular position of the first marker is calculated based on the detection signals of the second marker and the third marker, the amount of deviation in the angular position can be calculated more accurately.

[0014] In the present invention, preferably, the deviation amount calculation unit uses the detection signals of four markers provided adjacent to the first marker and acquired by the reading sensor to calculate the amount of deviation in the angular position of the first marker.

[0015] According to the present invention configured as described above, since the amount of deviation in the angular position of the first marker is calculated based on the detection signals of the four markers adjacent to the first marker, the amount of deviation in the angular position can be calculated even more accurately.

[0016] In the present invention, preferably, the traveling vehicle travels so as to read the first marker a plurality of times, and the deviation amount of the angular position of the first marker calculated by the deviation amount calculation unit is updated every time of reading.

[0017] According to the present invention configured as described above, the traveling vehicle travels so as to read the first marker a plurality of times, and the deviation amount of the angular position of the first marker is updated every time of reading. In this way, by measuring a plurality of times, it becomes possible to measure a finer angular deviation during traveling after applying the correction value, and accidental error generation can be removed.

[0018] In the present invention, preferably, the traveling vehicle continuously travels along three or more markers arranged in a straight line, and sequentially calculates the deviation amount of the angular position of each marker.

[0019] According to the present invention configured as described above, the traveling vehicle continuously travels along three or more markers arranged in a straight line, and the deviation amount of the angular position of each marker is sequentially calculated. Therefore, it is possible to detect the deviation amounts of the angular positions of many markers in a short time.

[0020] Further, the present invention is a method for detecting the deviation amount of a marker for detecting the deviation amount of the angular position of a marker provided on a floor surface in order to automatically drive a traveling vehicle, including a reading step of reading the position and angle of a first marker provided on the floor surface by a reading sensor provided on the traveling vehicle, a traveling step of traveling the traveling vehicle to a second marker provided adjacent to the first marker based on the position and angle of the first marker read by the reading sensor, and a deviation amount calculation step of calculating the deviation amount of the angular position of the first marker based on the position of the second marker read by the reading sensor after the traveling vehicle has traveled to the second marker.

Advantages of the Invention

[0021] According to the traveling vehicle system and the marker deviation amount detection method of the present invention, the deviation amount of the marker can be detected without using a special device.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0023] Next, with reference to the accompanying drawings, a traveling vehicle system and a marker deviation amount detection method according to an embodiment of the present invention will be described. FIG. 1 is a perspective view showing an example in which the traveling vehicle system according to an embodiment of the present invention is applied to the conveyance of goods in a warehouse. FIG. 2 is a perspective view of a traveling vehicle provided in the traveling vehicle system according to an embodiment of the present invention. FIG. 3 is a bottom view of a traveling vehicle provided in the traveling vehicle system according to an embodiment of the present invention.

[0024] As shown in FIG. 1, a traveling vehicle system 1 according to an embodiment of the present invention includes a traveling vehicle 2 capable of traveling on a floor surface, and a plurality of markers 4 provided on the floor surface on which the traveling vehicle 2 travels. Further, the traveling vehicle 2 is provided with a controller 6 for controlling the traveling vehicle, and an imaging device 18 (FIG. 3), which is a reading sensor capable of reading the marker 4. In addition, in the present embodiment, the traveling vehicle system 1 includes a plurality of traveling vehicles 2, and these traveling vehicles 2 are configured to convey the luggage 10 in the warehouse according to a command signal transmitted from the upper controller 8. That is, each traveling vehicle 2 is configured to automatically travel based on the marker 4 provided on the floor surface, and to convey the luggage 10 in the warehouse to a target location according to an instruction from the upper controller 8.

[0025] As shown in FIG. 2, the traveling vehicle 2 includes a main body portion 2a, a controller 6 built in the main body portion 2a, and a lifting device 12 provided on the upper surface of the main body portion 2a. Further, as shown in FIG. 3, on the bottom surface of the main body portion 2a, there are two drive wheels 14, four driven wheels 16 respectively provided on both sides of these drive wheels 14, and an imaging device 18 which is a reading sensor provided at the center of the bottom surface of the main body portion 2a.

[0026] As shown in FIG. 2, the lifting device 12 includes a square plate-shaped mounting table 12a oriented in the horizontal direction, and a square plate-shaped lifting table 12b provided so as to overlap the lower side of the mounting table 12a. Further, the lifting device 12 includes four shafts 12c that support the four corners of the lifting table 12b from below, and a retracting mechanism 12d that moves these shafts 12c forward and backward in the vertical direction. In addition, a rotation mechanism 12e is provided between the mounting table 12a and the lifting table 12b, and by this rotation mechanism 12e, the mounting table 12a is rotated with respect to the lifting table 12b.

[0027] The mounting table 12a is a generally square flat plate-like member, and is configured such that the load 10 can be placed on its upper surface. The lifting table 12b is a generally square flat plate-like member, and at the four corners of its lower surface, shafts 12c are respectively attached so as to extend in the vertical direction. These shafts 12c are supported by the retracting mechanism 12d so as to be retractable in the vertical direction, and by advancing each shaft 12c vertically upward by the retracting mechanism 12d, the lifting table 12b can be lifted. Along with this, the mounting table 12a and the load 10 placed thereon are also lifted. On the other hand, by retracting each shaft 12c downward by the retracting mechanism 12d, the lifting table 12b can be lowered. Thereby, the mounting table 12a and the load 10 placed thereon can be lowered. Also, by operating the rotation mechanism 12e provided between the mounting table 12a and the lifting table 12b, the mounting table 12a can be rotated with respect to the lifting table 12b, and thereby, the load placed on the mounting table 12a can be rotated.

[0028] Next, as shown in FIG. 3, the drive wheels 14 are wheels provided on the bottom surface of the main body portion 2a of the traveling vehicle 2, and are respectively provided one by one at the center in the front-rear direction of both sides of the main body portion 2a. Also, each drive wheel 14 is configured to be independently rotationally driven by a motor (not shown). For this reason, by driving each drive wheel 14 in the same direction at the same rotational speed, the traveling vehicle 2 can be made to travel straight. Also, a rotary encoder (not shown) is connected to each drive wheel 14, and based on this, the traveling vehicle 2 can recognize the traveling distance and the current position. On the other hand, by driving each drive wheel 14 in the reverse direction at the same rotational speed, the traveling vehicle 2 can be rotated (spin turned) about the midpoint C between the drive wheels 14.

[0029] Thus, in the present embodiment, by independently driving the two drive wheels 14, the traveling vehicle 2 can be moved in an arbitrary direction. In contrast, as a modification, by providing a steering mechanism to the drive wheels, or by providing fixed drive wheels and steerable steering wheels, the traveling vehicle can also be configured to be movable in an arbitrary direction.

[0030] The driven wheels 16 are provided in a total of four, one each on the front side and the rear side of each driving wheel 14. These driven wheels 16 are not rotationally driven and can freely rotate about the axle. When each driven wheel 16 contacts the floor surface, the main body 2a of the traveling vehicle 2 is maintained horizontally. Further, each driven wheel 16 can freely rotate about an axis directed in the vertical direction. Thus, when the traveling vehicle 2 changes its direction, etc., it can freely change its orientation accordingly.

[0031] The imaging device 18 is a camera provided on the bottom surface of the main body 2a of the traveling vehicle 2. It is disposed at the center of the bottom surface of the main body 2a and is configured to photograph the floor surface at predetermined time intervals. That is, by traveling the traveling vehicle 2 while photographing the floor surface with the imaging device 18, the marker 4 disposed on the floor surface can be detected. Note that the imaging device 18 has a sufficiently wide viewing angle so that it can photograph the entire marker 4 even when the center of the traveling vehicle 2 passing over the marker 4 is displaced from the center of the marker 4. Further, the image of the marker 4 photographed by the imaging device 18 is subjected to image analysis by a controller 6 mounted on the traveling vehicle 2, and based on this, the current position and angle of the traveling vehicle 2 are calculated. In the present embodiment, the imaging device 18 is used as the reading sensor. However, as a modification, any sensor such as a two-dimensional code reader can also be used as the reading sensor. The calculation of the position and angle of the traveling vehicle 2 by the controller 6 will be described later.

[0032] The traveling vehicle system 1 of this embodiment is configured to transport the goods in the warehouse by causing the traveling vehicle 2 to travel in the warehouse. That is, as shown in FIG. 1, the upper controller 8 transmits a signal for instructing the goods 10 to be transported to the traveling vehicle 2. Based on this command signal, the traveling vehicle 2 travels while sequentially reading the markers 4 installed on the floor surface in the warehouse and stops directly below the target goods 10. Here, each piece of goods 10 in the warehouse is placed on a pallet 10a, and the four corners of this pallet 10a are supported by supports 10b. Therefore, the pallet 10a on which each piece of goods 10 is placed is supported above the floor surface by the four supports 10b. The traveling vehicle 2 enters below the pallet 10a from between the supports 10b that support the goods 10 and stops directly below the target goods 10.

[0033] The traveling vehicle 2 that has stopped directly below the goods 10 activates the lifting device 12 to raise the mounting table 12a. As a result, the pallet 10a is supported by the mounting table 12a from below and lifted from the support 10b. Next, the traveling vehicle 2 travels to the target location in the warehouse while lifting the pallet 10a and transports the goods 10. At the destination, when placing the pallet 10a on the support 10b, the traveling vehicle 2 stops at the center of the four supports 10b that should support the pallet 10a and activates the lifting device 12 to lower the mounting table 12a. As a result, the pallet 10a with the goods 10 can be placed on the support 10b at the destination.

[0034] As described above, in the traveling vehicle system 1 of this embodiment, the traveling vehicle 2 is configured to acquire information on its current position and direction by reading the marker 4 provided on the floor surface and travel to the target point based on this information. However, it is difficult to provide the marker 4 on the floor surface with complete position accuracy and direction accuracy, and due to this, the traveling vehicle 2 may travel on an unintended route. The traveling route of this traveling vehicle 2 will be described below with reference to FIG. 4.

[0035] FIG. 4 is a schematic diagram for explaining a state in which a traveling vehicle 2 provided in a traveling vehicle system according to an embodiment of the present invention travels based on markers. In FIG. 4, in order to distinguish individual markers provided on the floor surface, each marker is indicated with reference numerals “4a”, “4b”, and “4c”.

[0036] First, in the example shown in FIG. 4, a traveling path toward the upper side of the drawing is formed by three markers 4a, 4b, and 4c arranged in a straight line. Here, as shown in FIG. 4, each marker 4 is formed in a substantially square thin sheet shape and is attached to a predetermined position on the floor surface in a predetermined direction. In addition, a unique two-dimensional code (not shown) is printed on each marker, and by reading this with the imaging device 18 of the traveling vehicle 2, the position coordinates of the traveling vehicle 2 in the warehouse can be acquired. That is, in the controller 6 of each traveling vehicle 2, the two-dimensional code included in each marker 4 and the position coordinates where the marker 4 including the two-dimensional code is installed are stored in association with each other, and the position coordinates can be acquired by reading the two-dimensional code. In the present embodiment, a data matrix is used as the two-dimensional code attached to the marker 4. On the other hand, as a modification, any code such as a QR code (registered trademark) can be used as the two-dimensional code attached to the marker 4.

[0037] In addition, each marker 4 includes a line parallel to the direction in which the traveling vehicle 2 travels and a line perpendicular thereto (in the example shown in FIG. 4, the vertical and horizontal sides of the black square), and based on these lines, the traveling vehicle 2 can recognize its own directed direction. That is, in the image of the marker 4 captured by the imaging device 18 of the traveling vehicle 2, if the vertical side of the marker 4 is directed vertically, it means that the traveling vehicle 2 is directed in the direction in which it should travel accurately. Also, when the vertical side of the marker 4 is photographed obliquely, the traveling vehicle 2 is inclined with respect to the direction in which it should travel.

[0038] First, in column (a) of FIG. 4, the traveling vehicle 2 photographs the marker 4a with the imaging device 18, and based on this, travels toward the next marker 4b on the traveling route. That is, in the image photographed by the imaging device 18 when passing the marker 4a, the marker 4a is located at the center of the image, and the vertical sides of the marker 4a are accurately oriented in the vertical direction in the image. Therefore, the traveling vehicle 2 is traveling straight toward the marker 4b which is the next target.

[0039] Next, as shown in column (b) of FIG. 4, when the traveling vehicle 2 reaches the marker 4b, the marker 4b is photographed by the imaging device 18. Here, the marker 4b is slightly tilted due to the pasting error when installing the marker 4b. Thus, when the marker 4b is photographed tilted with respect to the traveling direction of the traveling vehicle 2, the controller 6 of the traveling vehicle 2 determines that the vehicle has traveled tilted with respect to the direction in which the traveling vehicle 2 should travel, and slightly corrects the traveling direction to correct this.

[0040] That is, as shown in column (c) of FIG. 4, the controller 6 corrects the traveling direction so that the traveling direction of the traveling vehicle 2 becomes parallel to the vertical side of the marker 4b. Specifically, the controller 6 controls the drive wheels 14 so that the rotational speed of the right drive wheel 14 of the traveling vehicle 2 becomes higher than the rotational speed of the left drive wheel 14 for a predetermined time, and slightly corrects the traveling direction of the traveling vehicle 2 to the left direction.

[0041] As a result, as shown by the dashed line in column (d) of FIG. 4, the traveling vehicle 2 will travel obliquely deviated from the planned traveling route shown by the solid line. Next, as shown in column (e) of FIG. 4, when the traveling vehicle 2 reaches the marker 4c, the marker 4c is photographed by the imaging device 18. Here, after passing the marker 4b, the marker 4c is photographed shifted to the right with respect to the center of the image due to the correction of the traveling direction. Thereby, the controller 6 recognizes that the traveling route of the traveling vehicle 2 has shifted to the left, and to correct this, as shown in column (f) of FIG. 4, corrects the traveling direction of the traveling vehicle 2 to the right direction.

[0042] As a result of the marker 4b being attached with a slight inclination in this way, the traveling vehicle 2 travels in a zigzag pattern with respect to the straight planned travel route. For this reason, the travel of the traveling vehicle 2 becomes unstable. The traveling vehicle system 1 of the present embodiment is configured to execute the method for detecting the displacement amount of the marker according to the embodiment of the present invention in order to prevent the traveling vehicle 2 from traveling on an unintended travel route based on the installation error of the marker 4, and to detect the displacement amount of the angular position of the marker.

[0043] Next, with reference to FIGS. 5 to 7, a method for detecting the displacement amount of the marker according to the embodiment of the present invention and a traveling vehicle system that executes this will be described. FIG. 5 is a block diagram showing the configuration of a controller 6 that executes the method for detecting the displacement amount of the marker of the present embodiment.

[0044] As shown in FIG. 5, the controller 6 provided in the traveling vehicle 2 of the traveling vehicle system 1 of the present embodiment has a signal input unit 6a for inputting a detection signal from the imaging device 18 and a position calculation unit 6b for calculating the current position and angle of the traveling vehicle 2 based on the detection signal in order to execute the method for detecting the displacement amount of the marker. Further, the controller 6 has a travel control unit 6c for traveling the traveling vehicle 2 to the next marker 4 based on the position and angle of the traveling vehicle 2 calculated by the position calculation unit 6b, and a displacement amount calculation unit 6d for detecting the displacement amount of the next marker 4 in the left-right direction based on the detection signal acquired by the imaging device 18 and calculating the displacement amount of the angular position of the previous marker. Further, the controller 6 has a displacement amount storage unit 6e for storing the displacement amount of the angular position of the marker 4 calculated by the displacement amount calculation unit 6d, and a transmission unit 6f for transmitting the displacement amount of the angular position of the marker 4 to the upper controller 8.

[0045] Specifically, the controller 6 is composed of a microprocessor, a memory, an interface circuit, a transmission / reception circuit, software (not shown above) for operating these components, etc., and functions as each of the above functional units. In this embodiment, the calculation of the deviation amount of the angular position of the marker, etc. is executed by the controller 6 mounted on the traveling vehicle 2. However, the present invention can also be configured such that part or all of the processing in the controller 6 is executed by the upper controller 8. For example, the present invention can also be configured to sequentially transmit the image data captured by the imaging device 18 to the upper controller 8 and execute the calculation of the deviation amount, etc. in the upper controller 8. Alternatively, all functions can be aggregated in one controller, and either the controller 6 or the upper controller 8 can be omitted.

[0046] The signal input unit 6a is configured such that the detection signal of the image captured by the imaging device 18 is input at a predetermined time interval. The detection signal of the image is acquired at a sufficiently short time interval so that the entire marker 4 is captured in at least one image when the traveling vehicle 2 passes over the marker 4.

[0047] The position calculation unit 6b is configured to calculate the current position and angle of the traveling vehicle 2 based on the detection signal acquired by the imaging device 18 when the imaging device 18 captures (reads) one marker (the first marker). That is, the position calculation unit 6b recognizes the unique two-dimensional code (not shown) of each marker 4 from the captured image. The position coordinates of the marker 4 having each two-dimensional code are stored in the controller 6 in advance, and based on this, the controller 6 detects the position where the traveling vehicle 2 is traveling in the warehouse. Further, the controller 6 detects the deviation of the traveling route of the traveling vehicle 2 based on the position where the marker 4 is captured in the image.

[0048] For example, when the marker 4 is captured at the center in the left - right direction within the image, the traveling vehicle 2 can detect that it is traveling accurately on the planned traveling route. Also, when the marker 4 is captured with a deviation to the left side within the image, the traveling vehicle 2 can detect that it is traveling off the planned traveling route to the right side. Further, when the marker 4 is captured tilted within the image, the traveling vehicle 2 can detect that it is traveling at an angle deviated by the tilt angle of the captured marker 4 with respect to the planned traveling route. In this embodiment, when the traveling vehicle 2 is traveling on the planned traveling route, the center in the left - right direction of the traveling vehicle 2 is configured to pass over the marker 4. However, it is also possible to set the traveling route so that a position deviated by a predetermined distance from the center in the left - right direction of the traveling vehicle 2 passes over the marker 4.

[0049] The travel control unit 6c is configured to drive the traveling vehicle 2 to a marker provided adjacent to the marker that has been passed, based on the position and angle of the traveling vehicle 2 calculated by the position calculation unit 6b. That is, when the traveling vehicle 2 passes the first marker 4 and captures the first marker 4, the travel control unit 6c drives the traveling vehicle 2 to the second marker 4 provided adjacent to the first marker 4 according to the planned traveling route. In the example shown in FIG. 4, when the marker 4b is captured by the imaging device 18 as the first marker, based on the position and angle of the traveling vehicle 2 calculated by the position calculation unit 6b from the image, the travel control unit 6c drives the traveling vehicle 2 to the marker 4c, which is the second marker provided adjacent to the marker 4b. That is, based on the calculated position and angle of the traveling vehicle 2, the travel control unit 6c controls a motor (not shown) that drives the left and right drive wheels 14 to drive along the traveling route while referring to the detection signal of a rotary encoder (not shown) connected to the drive wheels 14 to travel.

[0050] The deviation amount calculation unit 6d is configured to detect the lateral deviation amount of the newly arrived second marker by photographing the second marker with the imaging device 18, and calculate the deviation amount of the angular position of the previously photographed first marker based on this lateral deviation amount. That is, in the example shown in FIG. 4, by photographing the marker 4c as the second marker with the imaging device 18, the lateral deviation amount of the marker 4c is detected, and based on this lateral deviation amount, the deviation amount of the angular position of the previously photographed first marker, the marker 4b, is calculated.

[0051] The deviation amount storage unit 6e is configured to store the deviation amount of the angular position of the first marker 4 calculated by the deviation amount calculation unit 6d. That is, in the example shown in FIG. 4, the deviation amount of the angular position of the first marker, the marker 4b, calculated by the deviation amount calculation unit 6d is stored. Thereby, when the traveling vehicle 2 next passes the marker 4b, the deviation amount of the angular position obtained from the image of the photographed marker 4b is corrected based on the deviation amount of the angular position of the marker 4b stored in the deviation amount storage unit 6e, and the deviation of the traveling route based on the deviation of the installation angle of the marker 4b is suppressed. Note that the present invention can also be configured to correct the image of the photographed marker 4b itself based on the deviation amount of the angular position stored in the deviation amount storage unit 6e.

[0052] The transmission unit 6f is configured to transmit the deviation amount of the angular position of the first marker 4 stored in the deviation amount storage unit 6e of the traveling vehicle 2 to the upper controller 8. The upper controller 8 that has received the deviation amount of the angular position of the marker 4 transmits the received deviation amount of the angular position to the controller 6 of each traveling vehicle 2. Each controller 6 of the traveling vehicle 2 that has received the deviation amount of the angular position stores this in the deviation amount storage unit 6e. Thereby, the deviation amount of the angular position of the marker 4 calculated by one traveling vehicle 2 can be shared by all the traveling vehicles 2, and each traveling vehicle 2 can promptly correct the deviation amount of the angular position of the marker 4.

[0053] In the present embodiment, the amount of deviation of the calculated angular position is sent to the upper controller 8, and the amount of deviation is sent from the upper controller 8 to each traveling vehicle 2. However, the present invention can also be configured such that the amount of deviation is directly sent from the controller 6 of the traveling vehicle 2 that calculated the amount of deviation to the controller 6 of another traveling vehicle 2. Alternatively, the present invention can also be configured such that the user copies the amount of deviation of the angular position of the marker 4 calculated by one traveling vehicle 2 to another traveling vehicle 2.

[0054] Next, with reference to FIGS. 6 and 7, the procedure of the marker deviation amount detection method according to the embodiment of the present invention will be described. FIG. 6 is a flowchart showing the execution procedure of the marker deviation amount detection method by the controller 6. FIG. 7 is a diagram for explaining an example of the marker deviation amount detection method according to the present embodiment. In FIG. 7, in order to indicate specific markers in the figure, some markers are labeled with symbols "4d", "4e",... and the other markers are labeled with the symbol "4".

[0055] The flowchart shown in FIG. 6 is a process executed when the traveling vehicle 2 passes over a predetermined marker from a certain marker 4 and travels to the destination, and is executed every time each traveling vehicle 2 of the traveling vehicle system 1 is instructed to travel to the destination.

[0056] First, in step S1 of FIG. 6, it is determined whether the automatic learning mode is set. Here, the automatic learning mode is a mode in which when the traveling vehicle 2 travels from the first marker to the second marker, the deviation amount of the angular position of the first marker is calculated based on the deviation amount in the left-right direction of the second marker and learned (stored). In the automatic learning mode, it is advisable to set the traveling route of the traveling vehicle 2 so that all the markers 4 pass in all directions in which it is possible to travel in the shortest time. Alternatively, when some of the markers 4 are replaced or new markers 4 are installed, the traveling route can also be set so that the traveling vehicle 2 travels only in a partial section including those markers 4. Also, the traveling route can be set so that the traveling vehicle 2 travels the same route multiple times. Furthermore, multiple traveling vehicles 2 can be made to travel simultaneously so that all the markers 4 are passed by the multiple traveling vehicles 2.

[0057] On the other hand, when the automatic learning mode is not set, the process in the flowchart of FIG. 6 proceeds to step S8. In step S8, it is determined whether the traveling vehicle 2 has arrived at the destination. If it has not arrived at the destination, the process returns to step S1, and if it has arrived at the destination, one cycle of the flowchart shown in FIG. 6 is terminated. Therefore, in a state where the automatic learning mode is not set, the process of step S1 → S8 → S1 is repeatedly executed until the destination is reached.

[0058] On the other hand, when the automatic learning mode is set, the process proceeds to step S2. In step S2, it is determined whether a new marker (the second marker) has been detected. That is, the imaging device 18 provided on the traveling vehicle 2 repeatedly photographs the floor surface at a predetermined time interval during traveling, and after departing from the first marker, it is determined whether a new marker (the second marker) has been photographed (detected). If a new marker is detected, the process proceeds to step S3, and if not, the process returns to step S1. Therefore, in a state where the automatic learning mode is set, after departing from the first marker, the process of step S2 → S1 → S2 is repeatedly executed until the second marker is detected.

[0059] In the example shown in FIG. 7, for example, the imaging device 18 of the traveling vehicle 2 reads the marker 4d which is the first marker, and the position calculation unit 6b of the controller 6 calculates the current position and angle of the traveling vehicle 2. Further, the travel control unit 6c causes the traveling vehicle 2 to travel upward in FIG. 7 from the marker 4d according to the set travel route based on the position and angle of the marker 4d. In this case, until the marker 4e which is the second marker is detected, the processing of step S2→S1→S2 is repeatedly executed in the controller 6. Note that the step of reading the marker 4d by the imaging device 18 of the traveling vehicle 2 corresponds to the reading step in the marker displacement amount detection method according to the embodiment of the present invention. Further, the step of causing the traveling vehicle 2 to travel based on the position and angle of the marker 4d until the marker 4e is detected corresponds to the traveling step in the marker displacement amount detection method according to the embodiment of the present invention.

[0060] Next, when a new marker is detected, the process proceeds to step S3. In step S3, based on the image of the second marker that has been photographed, the coordinates of the current position of the traveling vehicle 2 are acquired. That is, the controller 6 of the traveling vehicle 2 identifies the marker 4 based on the two-dimensional code (not shown) included in the image of the second marker that has been photographed, and acquires the position coordinates of the marker 4 stored in association with the marker 4. In the example shown in FIG. 7, for example, when the marker 4e is photographed by the imaging device 18 as the second marker, the position coordinates of the marker 4e are acquired based on the two-dimensional code (not shown) recorded in the marker 4e.

[0061] Furthermore, in step S4, based on the position of the second marker 4 in the image photographed by the imaging device 18, the displacement amount of the second marker 4 in the left-right direction is detected by the displacement amount calculation unit 6d of the controller 6. For example, in the example shown in FIG. 7, if the marker 4e is photographed at the center in the left-right direction of the image as the second marker, it can be determined that the traveling vehicle 2 has reached approximately accurately the position stored as the position coordinates of the marker 4e.

[0062] On the other hand, in the example shown in FIG. 7, the traveling vehicle 2 that has passed through the marker 4d, which is the first marker, is traveling along the traveling path indicated by the dashed line in FIG. 7 because the angular position of the marker 4d is deviated. As a result, the marker 4e is photographed at a position deviated from the center in the left - right direction of the image by the imaging device 18 of the traveling vehicle 2. That is, the central point A of the marker 4e should be photographed at the center in the left - right direction of the image, but due to the deviation of the angular position of the marker 4d, the traveling vehicle 2 travels obliquely, and the point A' of the marker 4e is photographed at the center in the left - right direction of the image.

[0063] Next, in step S5, the deviation amount calculation unit 6d of the controller 6 calculates the deviation amount of the angular position of the marker 4d, which is the first marker, based on the deviation amount in the left - right direction of the position where the marker 4e is photographed. Specifically, based on the distance (A - A') between the point A of the marker 4e that should originally be photographed at the center in the left - right direction of the image and the point A' of the marker 4e that is actually photographed at the center in the left - right direction of the image, and the traveling distance (O - A) from the marker 4d to the marker 4e, the magnitude of the angle ∠AOA' is calculated by the deviation amount calculation unit 6d. That is, the deviation amount of the angular position of the marker 4d is calculated as the angle ∠AOA'. Note that the step of calculating this angle ∠AOA' corresponds to the deviation amount calculation step in the marker deviation amount detection method according to the embodiment of the present invention.

[0064] Here, even when there is no deviation in the angular position of the marker 4d and the marker 4e is installed offset from the accurate position, there may be a deviation in the left - right direction in the position where the marker 4e is photographed. However, in general, the offset error occurring in the installation position of the marker 4 is sufficiently smaller than the error in the rotational position of the marker 4 and can be ignored as confirmed by the inventor of the present case. Also, even when the traveling vehicle 2 that has passed through the marker 4d is not traveling straight accurately, there may be a deviation in the left - right direction in the position where the marker 4e is photographed. However, the deviation due to the traveling of the traveling vehicle 2 is also sufficiently smaller than the error in the rotational position of the marker 4 and can be ignored as confirmed by the inventor of the present case.

[0065] Furthermore, in step S6, it is determined whether or not the lateral displacement amount calculated in step S4 is within a predetermined specified value. If the lateral displacement amount is within the specified value, the process in the flowchart proceeds to step S7, and if it is not within the specified value, the process proceeds to step S8. In this embodiment, the predetermined specified value is set to 50 mm.

[0066] Next, in step S7, the deviation amount (angle ∠AOA') of the angular position of the marker 4d calculated in step S5 is recorded in the deviation amount storage unit 6e of the controller 6. In the past, when the traveling vehicle 2 passed the marker 4d with the automatic learning mode set, the deviation amount of the angular position of the marker 4d has already been stored in the deviation amount storage unit 6e. In this case, the average value of the deviation amount of the angular position calculated in the past and the deviation amount of the angular position calculated this time is calculated, and this value is stored in the deviation amount storage unit 6e as the deviation amount of the angular position. In this way, the traveling vehicle 2 travels so as to read the marker 4d, which is the first marker, a plurality of times, and the deviation amount of the angular position of the marker 4d calculated by the deviation amount calculation unit 6d is updated every time it is read. In this embodiment, at most, the deviation amount of the angular position is calculated by averaging the deviation amounts of the angular positions calculated in the last four times in the past.

[0067] Furthermore, in the example shown in FIG. 7, the amount of deviation of the angular position of marker 4d can be calculated when the traveling vehicle 2 travels from marker 4d to marker 4e. In addition, it can also be calculated when the vehicle travels from marker 4d to marker 4f arranged below marker 4d, or when it travels from marker 4d to markers 4g and 4h on both sides thereof. Thus, even when the deviation amount calculation unit 6d uses the detection signals of the third markers (markers 4f, 4g, 4h), which are different from the second marker 4e provided next to the first marker 4d, it can calculate the amount of deviation of the angular position of marker 4d. That is, the deviation amount calculation unit 6d can calculate the amount of deviation of the angular position of marker 4d by using the detection signals of the four markers 4e, 4f, 4g, and 4h provided next to marker 4d and acquired by the imaging device 18. In this way, by calculating the amount of deviation of the angular position of marker 4d based on a plurality of markers 4, even if there is an offset error in the installation positions of these markers 4, the influence can be reduced.

[0068] On the other hand, in step S6, if it is determined that the lateral deviation amount calculated in step S4 is not within a predetermined specified value, the process proceeds to step S8 without executing step S7. That is, if a lateral deviation amount that is not within the specified value is calculated, there is a high possibility that the calculated deviation amount is an abnormal value. If this value is stored in the deviation amount storage unit 6e, it may have an adverse effect on the setting of the traveling route of the traveling vehicle 2. Therefore, when the lateral deviation amount is not within the predetermined specified value, the process proceeds to step S8 without executing the recording in the deviation amount storage unit 6e in step S7.

[0069] Next, in step S8, it is determined whether the vehicle has arrived at the destination. If it has not arrived, the processes below step S1 are repeated. In the example shown in FIG. 7, when the travel route is set to continue from marker 4d via marker 4e to marker 4i, in the flowchart shown in FIG. 6, the process returns from step S8 to step S1. Note that in the example shown in FIG. 7, when marker 4e is set as the destination of the travel route, when marker 4e is reached, one cycle of the flowchart shown in FIG. 6 ends.

[0070] After returning to step S1, when traveling from marker 4e to marker 4i, marker 4e corresponds to the first marker, and marker 4i corresponds to the second marker (new marker). Therefore, based on the amount of lateral displacement of marker 4i in the image captured when the traveling vehicle 2 reaches marker 4i, the amount of angular displacement of the angular position of marker 4e is calculated. In this way, the traveling vehicle 2 continuously travels along three or more markers 4 arranged in a straight line, and the amount of angular displacement of the angular position of each marker 4 is sequentially calculated.

[0071] Also, in the example shown in FIG. 7, at the position of marker 4e, the traveling vehicle 2 is displaced leftward by a distance (A - A'), and the angle at which the traveling vehicle 2 is directed is also inclined with respect to the vertical side of marker 4e. These positions and angles are calculated by the position calculation unit 6b of the controller 6. Further, the travel control unit 6c of the controller 6 causes the traveling vehicle 2 to travel toward marker 4i so as to correct these displacements. That is, the travel control unit 6c controls the drive wheels 14 of the traveling vehicle 2 so that the traveling vehicle 2 travels along the path indicated by the dashed line in FIG. 7. Further, when the traveling vehicle 2 reaches marker 4i and marker 4i is photographed by the imaging device 18, based on the amount of lateral displacement of marker 4i in the photographed image, the amount of angular displacement of the angular position of marker 4e is calculated.

[0072] In this way, in the state where the automatic learning mode is set, until the traveling vehicle 2 reaches the destination, the deviation amounts of the angular positions of the respective markers 4 that have been passed are sequentially calculated, and these are stored in the deviation amount storage unit 6e of the controller 6. Further, during normal traveling when the automatic learning mode is not set, the angular positions of the respective markers are corrected based on the deviation amounts of the angular positions of the markers stored in the deviation amount storage unit 6e. That is, the angular position of the marker 4 in the image captured by the imaging device 18 is corrected based on the deviation amount of the angular position stored in the deviation amount storage unit 6e, and based on the corrected angular position of the marker 4, the traveling vehicle 2 travels toward the next marker 4. Thereby, even when the angular position of the marker 4 is deviated, the traveling vehicle 2 can travel along an appropriate traveling route toward the adjacent marker 4.

[0073] According to the traveling vehicle system of the embodiment of the present invention, based on the deviation amount in the left-right direction of the detected second marker (for example, marker 4e in FIG. 7) (distance A-A' in FIG. 7), the deviation amount of the angular position of the first marker (for example, marker 4d in FIG. 7) (angle ∠AOA' in FIG. 7) can be calculated. Therefore, the deviation amount of the angular position of the marker 4 can be detected without using a special device.

[0074] Further, according to the traveling vehicle system 1 of the present embodiment, since the deviation amount of the angular position of the first marker (for example, marker 4d in FIG. 7) is calculated based on the detection signals of the second marker (for example, marker 4e in FIG. 7) and the third marker (for example, marker 4f in FIG. 7), the deviation amount of the angular position can be calculated more accurately.

[0075] Furthermore, according to the traveling vehicle system 1 of the present embodiment, since the deviation amount of the angular position of the first marker (for example, marker 4d in FIG. 7) is calculated based on the detection signals of the four markers adjacent to the first marker (for example, markers 4e, 4f, 4g, 4h in FIG. 7), the deviation amount of the angular position can be calculated even more accurately.

[0076] Also, according to the traveling vehicle system 1 of the present embodiment, the traveling vehicle 2 travels to read a first marker (for example, marker 4d in FIG. 7) multiple times, and the deviation amount of the angular position of the first marker is updated each time it is read. In this way, by measuring multiple times, it becomes possible to measure a finer angular deviation during traveling after applying the correction value, and accidental error occurrences can be eliminated.

[0077] Furthermore, according to the traveling vehicle system 1 of the present embodiment, the traveling vehicle 2 continuously travels along three or more markers (for example, markers 4d, 4e, 4i in FIG. 7) arranged in a straight line, and the deviation amount of the angular position of each marker is sequentially calculated. Therefore, it is possible to detect the deviation amounts of the angular positions of many markers in a short time.

[0078] As described above, the embodiments of the present invention have been described, but various changes can be made to the above-described embodiments. In particular, in the above-described embodiments, the traveling vehicle system of the present invention has been applied to a traveling vehicle system for transporting luggage in a warehouse, but the present invention can be applied to a traveling vehicle system that causes a traveling vehicle to travel for any purpose other than transportation.

Explanation of Reference Numerals

[0079] 1 Traveling vehicle system 2 Traveling vehicle 2a Main body part 4 Marker 6 Controller 6a Signal input part 6b Position calculation part 6c Travel control part 6d Deviation amount calculation part 6e Deviation amount storage part 6f Transmission part 8 Upper controller 10 Luggage 10a Pallet 10b Support 12 Lifting device 12a Mounting table 12b Lifting platform 12c Shaft 12d Retracting mechanism 12e Rotating mechanism 14 Driving wheel 16 Driven wheel 18 Imaging device (reading sensor)

Claims

1. A vehicle running system for automatically running a vehicle based on markers provided on a floor surface, comprising: A vehicle capable of running on the floor surface; A plurality of markers provided on the floor surface on which the vehicle runs; A reading sensor provided on the vehicle and capable of reading the plurality of markers; A controller for controlling the vehicle, and having: The controller includes: A position calculation unit that calculates the current position and angle of the vehicle based on a detection signal obtained by the reading sensor by reading a first marker among the plurality of markers; A travel control unit that causes the vehicle to travel to a second marker provided adjacent to the first marker based on the position and angle of the vehicle calculated by the position calculation unit; A deviation amount calculation unit that detects a deviation amount in the left-right direction of the second marker by reading the second marker with the reading sensor, and calculates a deviation amount in the angular position of the first marker based on the deviation amount in the left-right direction; A deviation amount storage unit that stores the deviation amount in the angular position of the first marker calculated by the deviation amount calculation unit; A vehicle running system, characterized by comprising the above.

2. The vehicle running system according to claim 1, wherein the deviation amount calculation unit also uses a detection signal of a third marker that is different from the second marker and is provided adjacent to the first marker and obtained by the reading sensor to calculate the deviation amount in the angular position of the first marker.

3. The vehicle running system according to claim 2, wherein the deviation amount calculation unit uses detection signals of four markers provided adjacent to the first marker and obtained by the reading sensor to calculate the deviation amount in the angular position of the first marker.

4. The vehicle runs to read the first marker multiple times, and the deviation amount in the angular position of the first marker calculated by the deviation amount calculation unit is updated every time of reading. The vehicle running system according to any one of claims 1 to 3.

5. The vehicle continuously runs along three or more of the markers arranged in a straight line, and sequentially calculates the deviation amount in the angular position of each marker. The vehicle running system according to any one of claims 1 to 4.

6. A method for detecting the deviation amount of a marker for detecting the deviation amount in the angular position of a marker provided on a floor surface for automatically running a vehicle, comprising: A reading step of reading the position and angle of a first marker provided on a bed surface by a reading sensor provided on a traveling vehicle; A traveling step of causing the traveling vehicle to travel to a second marker provided adjacent to the first marker based on the position and angle of the first marker read by the reading sensor; A deviation amount calculation step of calculating a deviation amount of the angular position of the first marker based on the position of the second marker read by the reading sensor after the traveling vehicle has traveled to the second marker; A method for detecting a deviation amount of a marker, characterized by comprising the above steps.

Images