Positioning device, moving body, and positioning method

Abstract

To provide a positioning device that can determine whether installation of a marker is appropriate.SOLUTION: A measuring device includes: a receiving section that receives image data from a camera mounted on a moving body; a marker positioning section that calculates a position of the moving body on the basis of a marker image included in the image data; a feature point positioning section that calculates the position of the moving body using a past position of the moving body and feature points in the image data; and a determination section that, when the marker positioning section calculates the position of the moving body according to marker positioning of a third marker, determines an installation state of a first marker and a second marker in accordance with a difference between the position of the moving body calculated according to the marker positioning of the third marker and each of the position of the moving body calculated by the feature point positioning section using a result of marker positioning of the first marker as the past position of the moving body and the position of the moving body calculated by the feature point positioning section using the result of marker positioning of the second marker as the past position of the moving body.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to a positioning device, a moving object, and a positioning method. [Background technology]

[0002] There are moving objects that transport luggage indoors, such as in a logistics warehouse, while measuring their positions. Patent Document 1 discloses a luggage location management device that measures the position of a vehicle using positioning techniques such as a global positioning system (GPS), a wireless local area network (LAN) positioning, and infrared positioning.

[0003] Non-Patent Document 1 discloses a positioning method called Visual-SLAM (Visual Simultaneous Localization and Mapping). In Visual-SLAM, a moving body equipped with a camera moves while capturing images of its surroundings, and the amount of movement of the moving body is calculated based on the amount of movement of feature points in multiple captured images. In this way, in Visual-SLAM, it is possible to estimate the current position of the moving body and generate a map based on the trajectory of the moving body. Note that calculating the position, direction, etc. of a moving body based on multiple captured images is called visual odometry. As a function of this visual odometry, the amount of movement of a moving body may be calculated based on the amount of movement of feature points in multiple captured images.

[0004] Also, a positioning method using a marker is known. For example, a positioning device stores image data of a marker that is attached (attached) to an object such as a pillar or a wall of a building, and map information including the installation position of the marker. The marker information and the installation position are associated with each other.

[0005] The positioning device calculates the relative position of the moving object with respect to the marker based on the marker image captured by the camera. The positioning device refers to map information to acquire the installation position of the marker captured by the camera, and calculates the position of the moving object on the map of the map information based on the acquired installation position and the calculated relative position of the moving object with respect to the marker. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2011-219229 A [Patent Document 2] International Publication No. 2020 / 137315 [Non-patent literature]

[0007] [Non-Patent Document 1] R. Mur-Artal, et al., "ORB-SLAM2: an Open-Source SLAM System for Monocular, Stereo and RGB-D Cameras", IEEE Transactions on Robotics, Volume: 33, Issue: 5, Oct. 2017 Summary of the Invention [Problem to be solved by the invention]

[0008] In a positioning method using a marker, accurate positioning cannot be performed unless the marker is appropriately installed on the object. However, there are cases where the marker is not appropriately installed on the object. For example, when a marker installed on an object falls and is reinstalled on the object, the marker may be installed in a position different from the installation position stored in the map information. Also, the marker may be installed upside down. In this way, if the marker is installed on an object in an incorrect state (inappropriate state), there is a problem that the positioning result of the positioning device may be erroneous.

[0009] Non-limiting embodiments of the present disclosure contribute to providing a positioning device, a moving object, and a positioning method that determine whether a marker is appropriately installed. [Means for solving the problem]

[0010] A positioning device according to an embodiment of the present disclosure includes a receiving unit that receives image data from a camera mounted on a moving body; a marker positioning unit that calculates a position of the moving body based on a marker image included in the image data; a feature point positioning unit that calculates the position of the moving body using past positions of the moving body and feature points of the image data; and a determination unit that, when the marker positioning unit calculates the position of the moving body by marker positioning of a third marker, determines an installation state of the first marker and the second marker based on a difference between the position of the moving body calculated by the feature point positioning unit using a result of marker positioning of a first marker as the past position of the moving body, the position of the moving body calculated by the feature point positioning unit using a result of marker positioning of a second marker as the past position of the moving body, and the position of the moving body calculated by marker positioning of the third marker.

[0011] A moving body according to an embodiment of the present disclosure includes a positioning device having a camera, a receiving unit that receives image data from the camera, a marker positioning unit that calculates a position of the moving body based on a marker image included in the image data, a feature point positioning unit that calculates the position of the moving body using past positions of the moving body and feature points of the image data, and a determination unit that, when the marker positioning unit calculates the position of the moving body by marker positioning of a third marker, determines an installation state of the first marker and the second marker based on a difference between the position of the moving body calculated by the feature point positioning unit using a result of marker positioning of a first marker as the past position of the moving body, the position of the moving body calculated by the feature point positioning unit using a result of marker positioning of a second marker as the past position of the moving body, and the position of the moving body calculated by marker positioning of the third marker.

[0012] In a positioning method according to an embodiment of the present disclosure, a receiving unit receives image data from a camera mounted on a moving body, a marker positioning unit calculates a position of the moving body based on a marker image included in the image data, a feature point positioning unit calculates a position of the moving body using past positions of the moving body and feature points of the image data, and a determination unit determines the installation status of the first marker and the second marker based on a difference between the position of the moving body calculated by the feature point positioning unit using a result of marker positioning of a first marker as the past position of the moving body, the position of the moving body calculated by the feature point positioning unit using a result of marker positioning of a second marker as the past position of the moving body, and the position of the moving body calculated by marker positioning of the third marker, when the marker positioning unit calculates the position of the moving body by marker positioning of a third marker.

[0013] In addition, these comprehensive or specific aspects may be realized by a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized by any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium. Effect of the Invention

[0014] According to an embodiment of the present disclosure, it is possible to determine whether the installation state of the marker is appropriate.

[0015] Further advantages and benefits of an embodiment of the present disclosure will become apparent from the specification and drawings, in which such advantages and / or benefits are provided by some of the embodiments and features described in the specification and drawings, respectively, but not necessarily all of which are provided to obtain one or more identical features. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing a moving body equipped with a positioning device according to an embodiment of the present disclosure. [Diagram 2] Top view of the area in which the moving object moves [Diagram 3]Diagram explaining marker positioning [Figure 4] Diagram explaining feature point positioning [Diagram 5] FIG. 1 is a diagram for explaining an example of the operation of a positioning device; [Figure 6] A block diagram showing the configuration of a positioning device. [Figure 7] 1 is a flowchart showing an example of a positioning process in a first period of a positioning device; [Figure 8] A flowchart showing an example of the process of S3 (marker positioning) in FIG. [Figure 9] A flowchart showing an example of the process of S4 (feature point positioning) in FIG. 7. [Figure 10] 11 is a flowchart showing an example of a positioning process in a second period of the positioning device. [Figure 11] 11 is a flowchart showing an example of a positioning process in a third period of the positioning device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings as appropriate. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially the same configuration may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

[0018] It should be noted that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0019] 1 is a diagram showing a moving object 2 equipped with a positioning device 1 according to an embodiment of the present disclosure. The moving object 2 may be a vehicle such as a forklift or a truck. The moving object 2 is equipped with the positioning device 1 and a camera 3.

[0020] The positioning device 1 receives image data of an image captured by the camera 3. Based on the image data received from the camera 3, the positioning device 1 measures the position of the moving object 2 by positioning based on image recognition of a marker (image of the marker) attached to an object and by positioning based on the amount of movement of a feature point in the image, such as visual odometry. That is, the positioning device 1 measures the position of the moving object 2 using two positioning methods (see, for example, Patent Document 2). Note that the position of the positioning device 1 may be regarded as the position of the moving object 2. That is, the positioning device 1 may measure the position of the positioning device 1 and use it as the position of the moving object 2.

[0021] Hereinafter, positioning based on image recognition of markers may be referred to as marker positioning, and positioning based on the amount of movement of feature points in an image may be referred to as feature point positioning. Positioning based on both marker positioning and feature point positioning may be referred to as a hybrid positioning method.

[0022] The camera 3 is, for example, a stereo camera. The camera 3 may be a compound eye camera as long as it outputs image data that allows the positioning device 1 to calculate the distance to the target object.

[0023] Fig. 2 is a diagram showing an area A2a in which the moving object 2 moves, viewed from above. The square and circle figures shown in the area A2a indicate objects such as luggage stored in a building such as a logistics warehouse, pillars of the building, and walls of the building. Markers A2b to A2e are attached to the objects as shown in Fig. 2. Note that, in Fig. 2, the markers A2b to A2e are drawn on the top surface of the object for ease of understanding, but the markers A2b to A2e may be attached to the side surface of the object so that the camera 3 can easily capture the object.

[0024] Map information (map data) of the area A2a is stored in the positioning device 1. The map information includes marker information such as image data of the markers A2b to A2e, and position information indicating the attachment positions of the markers A2b to A2e. The marker information and the attachment positions are associated with each other.

[0025] The area in which the moving object 2 moves may be indoors or outdoors. The term "attaching" may be rephrased as "installing."

[0026] Marker positioning Fig. 3 is a diagram for explaining marker positioning. Fig. 3 shows an image A3a captured by a camera 3. The image A3a includes a marker A3b.

[0027] The positioning device 1 receives an image A3a captured by a camera 3. The positioning device 1 calculates the relative position of the moving object 2 with respect to the marker A3b based on the appearance of the marker A3b, such as the image angle (tilt), shape, and size of the marker A3b included in the received image A3a. For example, the positioning device 1 calculates the relative position, such as the distance and direction of the moving object 2 with respect to the marker A3b. The positioning device 1 calculates the position (absolute position) of the moving object 2 on the map of the map information based on the calculated relative position and position information of the marker A3b included in the map information.

[0028] Feature point positioning There may be cases where the marker A3b is not present in the location within the area A2a where the moving object 2 moves or in the traveling direction (the shooting direction of the camera 3) of the moving object 2. In this case, the positioning device 1 measures the position of the moving object 2 by feature point positioning.

[0029] Fig. 4 is a diagram for explaining feature point positioning. Fig. 4 shows an image A4a captured by the camera 3. Black squares shown in the image A4a indicate feature points calculated by the positioning device 1. Note that the image A4a does not include markers.

[0030] The positioning device 1 receives an image A4a captured by the camera 3. If the received image A4a does not include a marker image, the positioning device 1 calculates feature points for each frame (or n frames, where n is a positive integer) and calculates the relative movement amount, such as the moving distance and moving direction (rotation angle) of the moving object 2, from the difference (deviation) in the positions of the feature points for each frame.

[0031] For example, the positioning device 1 calculates edges, such as corners of an object, where the shape changes and where the color changes, as feature points from the image A4a. The positioning device 1 calculates the feature points for each frame. The positioning device 1 calculates the relative movement amount of the moving object 2 from the difference in the positions of the feature points for each frame.

[0032] The calculation of the feature points is not limited to the above example. The feature points may be calculated using existing techniques. The feature points may be referred to as feature amounts.

[0033] After calculating the amount of relative movement, the positioning device 1 calculates the position of the moving object 2 within the area A2a based on the calculated amount of relative movement and the positioning result of the marker positioning. For example, the positioning device 1 adds the amount of relative movement to the positioning result of the marker positioning to calculate the position (absolute position) of the moving object 2 on the map of the map information.

[0034] The positioning device 1 performs marker positioning when the marker is again included in the image received from the camera 3. When the marker is no longer included in the image received from the camera 3, the positioning device 1 performs feature point positioning based on the position of the moving object 2 measured by the marker positioning.

[0035] In this way, the positioning device 1 executes marker positioning when the marker is photographed by the camera 3, and executes feature point positioning when the marker is not photographed by the camera 3. As a result, in the hybrid positioning method, even if the positioning result of the feature point positioning contains an error, the error is corrected by the positioning result of the marker positioning.

[0036] Furthermore, compared to the Visual-SLAM positioning method, the hybrid positioning method has the advantage that it does not require data such as point cloud data of the location where positioning is performed (for example, area A2a shown in FIG. 2) and has lighter processing power.

[0037] ·Consider For example, a person may touch a marker placed on an object, causing the marker to fall. If the fallen marker is then reinstalled on the object, it may not be placed in its original position, or may be placed upside down. In this way, if the marker is not placed appropriately on the object, the positioning device may give an erroneous positioning result.

[0038] Therefore, the positioning device 1 judges whether the installation of the marker is appropriate or not. If the positioning device 1 judges that the installation of the marker is inappropriate, the positioning device 1 outputs a positioning result based on the feature point positioning, thereby suppressing errors in the positioning result.

[0039] Example of operation Fig. 5 is a diagram for explaining an example of the operation of the positioning device 1. In Fig. 5, the same components as in Fig. 2 are denoted by the same reference numerals. Hereinafter, the marker A2b shown in Fig. 5 may be referred to as the first marker, the marker A2d as the second marker, and the marker A2e as the third marker.

[0040] 5 indicates the movement trajectory of the moving object 2. The moving object 2 moves from the starting point of the arrow A5aa toward the tip of the arrow.

[0041] Dotted arrows A5a, A5b, and A5c shown in Fig. 5 indicate periods of marker positioning performed by the positioning device 1. Chain-dotted arrows A5d and A5e shown in Fig. 5 indicate periods of feature point positioning performed by the positioning device 1.

[0042] The black circle A5f in Fig. 5 indicates the position of the moving object 2 when the image captured by the camera 3 includes an image of a first marker for which marker positioning is possible. In other words, the positioning device 1 starts marker positioning of the first marker at the position of the black circle A5f. Similarly, the black circle A5g indicates the position of the moving object 2 when the image captured by the camera 3 includes an image of a second marker for which marker positioning is possible. The black circle A5h indicates the position of the moving object 2 when the image captured by the camera 3 includes an image of a third marker for which marker positioning is possible.

[0043] In the following, the period from when the moving object 2 starts marker positioning of the first marker to when it starts marker positioning of the next second marker may be referred to as the first period. The period from when the moving object 2 starts marker positioning of the second marker to when it starts marker positioning of the next third marker may be referred to as the second period. The period after the moving object 2 starts marker positioning of the third marker may be referred to as the third period.

[0044] (1) Operation during the first period 5, an image of the first marker is included in the image captured by the camera 3. When the image of the first marker is included in the image captured by the camera 3, the positioning device 1 starts marker positioning of the moving object 2 based on the image of the first marker.

[0045] The positioning device 1 performs marker positioning while the image of the first marker is included in the image captured by the camera 3. For example, during the period indicated by the dotted arrow A5a, the positioning device 1 performs marker positioning based on the image of the first marker.

[0046] The positioning device 1 starts performing feature point positioning when the image of the first marker is no longer included in the image captured by the camera 3. For example, the positioning device 1 starts feature point positioning as indicated by the dashed-dotted arrow A5d, using the last positioning result of the marker positioning using the first marker (the positioning result of the marker positioning at the time of the tip of the dotted arrow A5a).

[0047] (2) Operation during the second period In the second period, the positioning device 1 executes the following operations 1 and 2.

[0048] ·Operation 1 5, the image of the second marker is included in the image captured by the camera 3. When the image of the second marker is included in the image captured by the camera 3, the positioning device 1 executes the same positioning process as in the first period.

[0049] For example, the positioning device 1 performs marker positioning while the image of the second marker is included in the image captured by the camera 3. For example, the positioning device 1 performs marker positioning based on the image of the second marker during the dotted arrow A5b.

[0050] The positioning device 1 starts performing feature point positioning when the image of the second marker is no longer included in the image captured by the camera 3. For example, the positioning device 1 starts feature point positioning as indicated by the dashed-dotted arrow A5e, using the last positioning result of the marker positioning using the second marker (the positioning result of the marker positioning at the time of the tip of the dotted arrow A5b).

[0051] In the second period, the positioning device 1 executes the above-mentioned operation 1 and also executes the following operation 2.

[0052] ·Operation 2 When an image of the second marker is included in the image captured by the camera 3, the positioning device 1 calculates the distance between the positioning result of the moving object 2 based on the image of the second marker and the positioning result of the feature point positioning that has been performed (continued) in the first period. For example, the positioning device 1 calculates the distance between the positioning result of the marker positioning of the second marker at the time of the starting point of the dotted arrow A5b and the positioning result of the feature point positioning of the dashed-dotted arrow A5d at the time corresponding to the starting point of the dotted arrow A5b (see black circle A5i).

[0053] Here, if either the first marker or the second marker is installed inappropriately, the positioning result of the moving object 2 based on the image of the second marker will diverge from the positioning result of the feature point positioning performed in the first period. Note that it is assumed that the situation in which a marker falls off an object does not occur frequently. Therefore, it is assumed that the possibility that two markers, the first marker and the second marker (multiple markers in the vicinity), are installed inappropriately at the same time is low.

[0054] For example, suppose that the installation of the second marker is inappropriate and the installation of the first marker is appropriate. In this case, the positioning result of the moving object 2 based on the image of the second marker deviates from the actual position of the moving object 2, and the positioning result of the feature point positioning performed in the first period is close to the actual position of the moving object 2. Therefore, the positioning result of the moving object 2 based on the image of the second marker deviates from the positioning result of the feature point positioning performed in the first period.

[0055] For example, suppose that the installation of the second marker is appropriate and the installation of the first marker is inappropriate. In this case, the positioning result of the moving body 2 based on the image of the second marker will be close to the actual position of the moving body 2, and the positioning result of the feature point positioning performed in the first period will deviate from the actual position of the moving body 2. Therefore, the positioning result of the moving body 2 based on the image of the second marker will deviate from the positioning result of the feature point positioning performed in the first period.

[0056] When both the installation of the second markers and the installation of the first markers are appropriate, the positioning result of the moving body 2 based on the image of the second marker and the positioning result of the feature point positioning performed in the first period will be close to the actual position of the moving body 2. Therefore, the positioning result of the moving body 2 based on the image of the second marker and the positioning result of the feature point positioning performed in the first period will be close to each other.

[0057] Therefore, as described above, the positioning device 1 calculates the distance between the marker positioning result at the start point of the dotted arrow A5b and the feature point positioning result at the time point of the dashed-dotted arrow A5d corresponding to the start point of the dotted arrow A5b (see black circle A5i). If the distance between the two positioning results is equal to or greater than a predetermined threshold, the positioning device 1 continues the feature point positioning performed in the first period without correcting the error using the second marker positioning result. For example, as shown by the dashed-dotted arrow A5d, the feature point positioning performed in the first period is continued.

[0058] That is, when the distance between the positioning result of the marker positioning based on the image of the second marker and the positioning result of the feature point positioning in the first period is equal to or greater than a predetermined threshold, the positioning device 1 determines that the installation of either the first marker or the second marker is inappropriate. Then, the positioning device 1 executes two types of positioning: the positioning based on the action 1 and the feature point positioning continued from the first period.

[0059] Note that the positioning device 1 stops the feature point positioning that has been performed in the first period when the distance between the positioning result of the marker positioning based on the image of the second marker and the positioning result of the feature point positioning in the first period is not equal to or greater than a predetermined threshold. For example, when the distance between the positioning result of the marker positioning at the time of the start point of the dotted arrow A5b and the positioning result of the feature point positioning at the time of the dashed-dotted arrow A5d corresponding to the start point of the dotted arrow A5b (see the black circle A5i) is not equal to or greater than a predetermined threshold, the positioning device 1 stops the feature point positioning that has been performed in the first period at the time of the black circle A5i in Fig. 5. This is because, in general, the accuracy of the marker positioning is higher than that of the feature point positioning, and therefore there is no problem in discarding the result of the feature point positioning if it can be assumed that the installation of the marker is appropriate.

[0060] Hereinafter, the positioning result of the feature point positioning continuously performed from the first period (the positioning result at the dashed-dotted arrow A5d) may be referred to as a continuous positioning result. The positioning result by operation 1 (the positioning results at the dotted arrow A5b and the dashed-dotted arrow A5e) may be referred to as a non-continuous positioning result.

[0061] (3) Operation during the third period In the third period, the positioning device 1 executes the following operations 1 and 2.

[0062] ·Operation 1 5, the image of the third marker is included in the image captured by the camera 3. When the image of the third marker is included in the image captured by the camera 3, the positioning device 1 executes the same positioning process as in the first period (or operation 1 in the second period).

[0063] In the third period, the positioning device 1 executes the above-mentioned operation 1 and also executes the following operation 2.

[0064] ·Operation 2 When an image of the third marker is included in the image captured by the camera 3, the positioning device 1 starts marker positioning of the moving object 2 based on the image of the third marker.

[0065] If the positioning device 1 determines that the distance between the positioning result of the marker positioning based on the image of the second marker and the positioning result of the feature point positioning performed in the first period is equal to or greater than a predetermined threshold in the second period, the positioning device 1 compares the positioning result of the marker positioning based on the image of the third marker with the continuous positioning result. In other words, if the positioning device 1 determines that the installation of either the first marker or the second marker is inappropriate in the second period, the positioning device 1 compares the positioning result of the marker positioning based on the image of the third marker with the continuous positioning result. For example, the positioning device 1 compares the positioning result of the marker positioning at the start point of the dotted arrow A5c shown in FIG. 5 with the positioning result of the feature point positioning at the tip of the dashed-dotted arrow A5d shown in FIG. 5.

[0066] Furthermore, if the positioning device 1 determines that the installation of either the first marker or the second marker is inappropriate during the second period, the positioning device 1 compares the positioning result of the marker positioning based on the image of the third marker with the non-continuous positioning result. For example, the positioning device 1 compares the positioning result of the marker positioning at the start point of the dotted arrow A5c shown in Fig. 5 with the positioning result of the feature point positioning at the tip of the dashed-dotted arrow A5e shown in Fig. 5.

[0067] As described above, it is assumed that the possibility of multiple nearby markers being inappropriately installed at the same time is low. Therefore, if the installation of either the first marker or the second marker is inappropriate, the installation of the third marker is assumed to be appropriate.

[0068] Here, if the installation of the first marker is inappropriate, the continuous positioning result will deviate from the positioning result of the marker positioning based on the image of the third marker. For example, if the installation of the first marker is inappropriate, the continuous positioning result reflecting the marker positioning result using the first marker will deviate from the actual position of the moving object 2, and therefore will deviate from the positioning result of the marker positioning based on the image of the appropriately installed third marker.

[0069] On the other hand, if the installation of the second marker is inappropriate, the non-continuous positioning result will deviate from the positioning result of the marker positioning based on the image of the third marker. For example, if the installation of the second marker is inappropriate, the non-continuous positioning result reflecting the marker positioning result using the second marker will deviate from the actual position of the moving object 2, and therefore will deviate from the positioning result of the marker positioning based on the image of the appropriately installed third marker.

[0070] Therefore, the positioning device 1 compares the distance (first distance) between the continuous positioning result and the positioning result of the marker positioning based on the image of the third marker with the distance (second distance) between the non-continuous positioning result and the positioning result of the marker positioning based on the image of the third marker. If the first distance is greater than the second distance, the positioning device 1 determines that the installation of the first marker is inappropriate. If the first distance is not greater than the second distance, the positioning device 1 determines that the installation of the second marker is inappropriate.

[0071] The reason for such a determination is explained below. In principle, it is difficult to completely eliminate errors in continuous positioning and non-continuous positioning. Therefore, both the first distance and the second distance may contain errors, and it is difficult to determine whether the result of continuous positioning or the result of non-continuous positioning is more accurate by evaluating only one of the first distance or the second distance. Therefore, the positioning device 1 presumes that the positioning result closer to the result of marker positioning based on the third marker is the accurate positioning result among the continuous positioning result and the non-continuous positioning result. That is, if the first distance is greater than the second distance, the positioning result of the non-continuous positioning is more accurate, and if the first distance is not greater than the second distance, the positioning result of the continuous positioning is more accurate. Here, if the non-continuous positioning result is more accurate, it can be determined that the installation of the first marker that is the basis of the continuous positioning result is inappropriate. Conversely, if the continuous positioning result is more accurate, it can be determined that the installation of the second marker that is the basis of the non-continuous positioning result is inappropriate.

[0072] When the positioning device 1 determines that the installation of the first marker is inappropriate, it calculates a movement amount (vector) for the continuous positioning result corresponding to the time (timing) when the marker positioning of the second marker is started to match the positioning result of the marker positioning when the marker positioning of the second marker is started. For example, the positioning device 1 calculates a movement amount for the positioning result of the feature point positioning at the time (see black circle A5i) corresponding to the starting point of the dotted arrow A5b of the dashed-dotted arrow A5d in FIG. 5 to match the positioning result of the second marker at the starting point of the dotted arrow A5b. The positioning device 1 moves (for example, moves in parallel) the calculated movement amount and the positioning result of the first period, and outputs it as the positioning result of the first period. That is, the positioning device 1 corrects the positioning result of the first period based on the continuous positioning result corresponding to the time when the marker positioning of the second marker is started among the continuous positioning results and the positioning result of the marker positioning of the second marker. Furthermore, when the positioning device 1 determines that the installation of the first marker is inappropriate, it does not output the continuous positioning result as the positioning result for the second period, but outputs the positioning result of the marker positioning based on the image of the second marker and the positioning result of the feature point positioning using the positioning result of the marker positioning based on the image of the second marker. That is, the positioning device 1 outputs the positioning result of the operation 1 for the second period. This allows the positioning device 1 to output a positioning result in which errors due to inappropriate installation of the first marker are suppressed.

[0073] When the positioning device 1 determines that the installation of the second marker is inappropriate, the positioning device 1 does not output the positioning result of the marker positioning based on the image of the second marker and the positioning result of the feature point positioning using the positioning result of the marker positioning based on the image of the second marker as the positioning result for the second period. In other words, the positioning device 1 does not output the positioning result of the operation 1 for the second period. When the positioning device 1 determines that the installation of the second marker is inappropriate, the positioning device 1 outputs the continuous positioning result as the positioning result for the second period. This allows the positioning device 1 to output a positioning result in which errors due to inappropriate installation of the second marker are suppressed.

[0074] Note that outputting the positioning result may be understood as storing the positioning result in a storage unit. Also, outputting the positioning result may be understood as transmitting the positioning result to a server (not shown in FIG. 1). For example, the positioning device 1 may transmit the positioning result to the server via wireless communication.

[0075] Moreover, outputting the positioning result may be understood as notifying the user of the positioning result in real time via a display, etc. Note that since the positioning device 1 cannot determine whether the installation of the first marker or the second marker is inappropriate until marker positioning using the third marker is performed, the positioning result based on the marker whose suitability for installation has not been determined is a provisional positioning result.

[0076] In the above, the positioning device 1 compares the first distance with the second distance to determine whether the installation of the first marker is inappropriate or the installation of the second marker is inappropriate, but the present invention is not limited to this. For example, the positioning device 1 may determine that the installation of the first marker is inappropriate when the continuous positioning result and the positioning result of the marker positioning based on the image of the third marker deviate by a predetermined threshold or more. The positioning device 1 may determine that the installation of the second marker is inappropriate when the non-continuous positioning result and the positioning result of the marker positioning based on the image of the third marker deviate by a predetermined threshold or more. This determination corresponds to a determination of whether the first distance is greater than a threshold and whether the second distance is greater than a threshold. In this determination, based on the evaluation of either the first distance or the second distance, it is determined whether the installation of each positioning result and the marker that is the basis of the positioning result are appropriate or inappropriate. Therefore, when the accuracy of the continuous positioning and the non-continuous positioning is relatively high, the determination can be made quickly. As described above, there is a possibility that the first distance and the second distance include an error, and it is not possible to determine whether the continuous positioning or the non-continuous positioning is more accurate by evaluating only one of them. However, if the threshold is made small enough, the effect of the error is limited to a range below the threshold, so that a relatively accurate determination result can be obtained even if the determination of whether the continuous positioning or the non-continuous positioning is more accurate is reserved.

[0077] Block configuration 6 is a block diagram showing the configuration of the positioning device 1. As shown in FIG. 6, the positioning device 1 has a control unit 11, a storage unit 12, and a communication unit 13.

[0078] The control unit 11 controls the entire positioning device 1. The control unit 11 may be configured by a processor such as a CPU (central processing unit), for example.

[0079] The control unit 11 includes a marker positioning unit 11a, a feature point positioning unit 11b, a distance unit 11c, a continuation unit 11d, and a determination unit 11e. The control unit 11 may realize the functions of each unit described above according to a program (application) stored in the storage unit 12.

[0080] The marker positioning unit 11 a calculates the position of the moving object 2 based on the marker image included in the image data of the camera 3 .

[0081] When the image data of the camera 3 does not include a marker image, the feature point positioning unit 11b calculates the position of the moving object 2 using the positioning result of the marker positioning calculated by the marker positioning unit 11a and the feature points of the image data.

[0082] Distance unit 11c calculates the distance between the feature point positioning result in the first time period and the marker positioning result in the second time period.

[0083] The continuation unit 11d continues the feature point positioning of the first period during the second period, based on the distance calculated by the distance unit 11c.

[0084] The judgment unit 11e judges the installation status of the first marker and the second marker based on the positioning result of the marker positioning in the third period, the positioning result of the feature point positioning continued by the continuation unit 11d, and the positioning result of the feature point positioning using the positioning result of the marker positioning of the second marker in the second period.

[0085] When the distance calculated by the distance unit 11c is equal to or greater than a predetermined threshold, the continuation unit 11d continues the feature point positioning of the first period into a second period.

[0086] The determination unit 11e calculates a first distance between the positioning result of the marker positioning in the third period and the positioning result of the feature point positioning continued by the continuation unit. The determination unit 11e calculates a second distance between the positioning result of the marker positioning in the third period and the positioning result of the feature point positioning using the positioning result of the marker positioning of the second marker. The determination unit 11e compares the first distance with the second distance to determine the installation states of the first marker and the second marker.

[0087] When the second distance is greater than the first distance, the determination unit 11e determines that the installation state of the second marker is inappropriate. When the second distance is not greater than the first distance, the determination unit 11e determines that the installation state of the first marker is inappropriate.

[0088] When the determination unit 11e determines that the installation state of the second marker is inappropriate, it outputs the positioning result of the feature point positioning continued by the continuation unit 11d as the positioning result for the second period. When the determination unit 11e determines that the installation state of the first marker is inappropriate, it corrects the positioning result for the first period based on the continued positioning result corresponding to the time when the marker positioning of the second marker was started and the positioning result of the marker positioning of the second marker, and outputs the corrected result. In addition, the determination unit 11e outputs the positioning result of the marker positioning of the second marker and the positioning result of the feature point positioning using the positioning result as the positioning result for the second period.

[0089] The storage unit 12 stores an operating system (OS) program and application programs executed by the control unit 11. The storage unit 12 also stores various data necessary for processing by the control unit 11. For example, the storage unit 12 stores map information of the area A2a. The storage unit 12 may be, for example, a solid state drive (SSD), a random access memory (RAM), a flash memory, a read only memory (ROM), and / or a hard disk drive (HDD).

[0090] The communication unit 13 communicates with the camera 3, for example, via wireless or wired LAN.

[0091] Operation flow Fig. 7 is a flowchart showing an example of a positioning process in a first period of the positioning device 1. The positioning device 1 repeatedly executes the process of the flowchart shown in Fig. 7, for example, at a predetermined cycle.

[0092] The positioning device 1 receives image data from the camera 3 (S1).

[0093] The positioning device 1 determines whether or not the image of the image data received in S1 includes a marker (S2).

[0094] When the positioning device 1 determines that the image of the image data received in S1 includes a marker (YES in S2), it executes a positioning process by marker positioning (S3). The process of S3 will be described in detail in the flowchart of FIG.

[0095] On the other hand, if the positioning device 1 determines that the image of the image data received in S1 does not include a marker (NO in S2), it executes a positioning process by feature point positioning (S4). The process of S4 will be described in detail in the flowchart of FIG.

[0096] After performing the positioning process in S3 and S4, the positioning device 1 stores the positioning result in the storage unit 12 (S5). Then, the positioning device 1 ends the process of this flowchart.

[0097] Fig. 8 is a flowchart showing an example of the process of S3 (marker positioning) in Fig. 7. The positioning device 1 acquires marker coordinates of a marker included in an image based on map information including marker installation information (S11). Note that the marker installation information is information that associates image data of a marker affixed to an object with the installation position (coordinates) of the marker.

[0098] The positioning device 1 calculates a vector between the camera 3 and the marker from the shape of the marker included in the image (S12). That is, the positioning device 1 calculates the relative position of the moving object 2 with respect to the marker, such as the distance and direction.

[0099] The positioning device 1 adds the vector between the camera 3 and the marker calculated in S2 to the marker coordinates acquired in S11, and calculates the position of the moving object 2 (absolute position within the map of the map information) (S13). Then, the positioning device 1 ends the processing of this flowchart.

[0100] Fig. 9 is a flowchart showing an example of the process of S4 (feature point positioning) in Fig. 7. The positioning device 1 calculates feature points in an image captured by the camera 3 (S21).

[0101] The positioning device 1 compares the feature points with those of the previous frame to calculate the relative movement amount, such as the movement distance and movement direction, of the moving object 2 (S22).

[0102] The positioning device 1 adds the amount of relative movement calculated in S22 to the position (absolute position) of the previous frame to calculate the position (absolute position) of the moving object 2 (S23).Then, the positioning device 1 ends the process of this flowchart.

[0103] Fig. 10 is a flowchart showing an example of the positioning process in the second period of the positioning device 1. In the process of the flowchart shown in Fig. 7, the positioning device 1 executes the positioning process by feature point positioning (S4) when the marker (first marker) is not included in the image captured by the camera 3 (NO in S2), and then executes the process of the flowchart in Fig. 10 when another marker (second marker) is included in the image captured by the camera 3.

[0104] The positioning device 1 executes a positioning process by marker positioning (a positioning process based on a second marker) (S31).

[0105] The positioning device 1 calculates the distance between the positioning result obtained by the marker positioning in S31 and the positioning result obtained by the feature point positioning in the first period (S32).

[0106] The positioning device 1 determines whether the distance calculated in S32 is equal to or greater than a predetermined threshold (S33).

[0107] If the distance calculated in S32 is not equal to or greater than the predetermined threshold (NO in S33), the positioning device 1 executes the same process as that in the first period (the process in the flowchart shown in FIG. 7) (S34). For example, the positioning device 1 executes the positioning process (marker positioning) indicated by the dotted arrow A5b in FIG. 5 and the positioning process (feature point positioning) indicated by the dashed-dotted arrow A5e in FIG. 5.

[0108] On the other hand, if the distance calculated in S32 is equal to or greater than the predetermined threshold (YES in S33), the positioning device 1 executes a positioning process that continues the feature point positioning in the first period (S35). Then, the positioning device 1 shifts the process to S34.

[0109] That is, when the distance calculated in S32 is equal to or greater than a predetermined threshold (YES in S33), the positioning device 1 executes two positioning processes, that is, a positioning process in S35 and a positioning process in S34. For example, the positioning device 1 executes a positioning process indicated by an arrow A5d of a dashed line in Fig. 5 (the positioning process in S35) and a positioning process indicated by an arrow A5b of a dotted line and an arrow A5e of a dashed line in Fig. 5 (the positioning process in S34).

[0110] Fig. 11 is a flowchart showing an example of the positioning process in the third period of the positioning device 1. The positioning device 1 executes the process of the flowchart shown in Fig. 11 when the following two conditions are satisfied.

[0111] ·Condition 1 In the process of the flowchart shown in FIG. 10, when the marker (second marker) is not included in the image captured by the camera 3 and the positioning process is performed by feature point positioning, a different marker (third marker) is then included in the image captured by the camera 3.

[0112] ·Condition 2 In S33 of the flowchart shown in FIG. 10, if it is determined that the distance calculated in S32 is equal to or greater than a predetermined threshold (YES in S33), and the feature point positioning in the first period has been continued in the second period,

[0113] The positioning device 1 executes a positioning process by marker positioning (a positioning process based on an image of a third marker) (S41).

[0114] The positioning device 1 calculates a distance (first distance) between the positioning result of S41 and the positioning result (continued positioning result) of feature point positioning using the marker recognized in the first period (feature point positioning that has continued from the feature point positioning in the first period) (S42).

[0115] The positioning device 1 calculates the distance (second distance) between the positioning result of S41 and the positioning result (non-continuous positioning result) of the feature point positioning using the marker recognized in the second period (S43). Note that the order of the processes of S42 and S43 may be reversed.

[0116] The positioning device 1 compares the first distance calculated in S42 with the second distance calculated in S43, and determines whether the second distance is greater than the first distance (S44).

[0117] When the positioning device 1 determines that the second distance is greater than the first distance (YES in S44), it determines that the installation of the marker (second marker) recognized in the second period is inappropriate, and stores the continuous positioning result as the positioning result for the second period (S45). For example, the positioning device 1 stores the positioning result at the dashed-dotted arrow A5d, starting from the black circle A5i in FIG. 5, as the positioning result for the second period.

[0118] On the other hand, when the positioning device 1 determines that the second distance is not greater than the first distance (NO in S44), it determines that the installation of the marker (first marker) recognized in the first period is inappropriate, and corrects and stores the positioning result of the first period based on the continuous positioning result corresponding to the time when the marker positioning of the second marker was started and the positioning result of the marker positioning of the second marker (S46). In addition, the positioning device 1 stores the non-continuous positioning result as the positioning result of the second period (S46). For example, the positioning device 1 stores the positioning result at the dotted arrow A5b shown in FIG. 5 and the positioning result at the dashed arrow A5e shown in FIG. 5 as the positioning result of the second period.

[0119] The positioning device 1 also executes a positioning process similar to that in FIG. 7 in parallel with the process of the flowchart in FIG. 11 or before or after the process of the flowchart in FIG.

[0120] <Summary of the embodiment> As described above, the positioning device 1 calculates the distance between the result of feature point positioning in the first period and the result of marker positioning in the second period. The positioning device 1 continues the feature point positioning in the first period in the second period based on the calculated distance. The positioning device 1 determines the installation states of the first marker and the second marker based on the result of marker positioning in the third period, the result of feature point positioning that continues, and the result of feature point positioning using the result of marker positioning of the second marker in the second period. This allows the positioning device 1 to determine whether the installation state of the markers is appropriate. Furthermore, the positioning device 1 can output a positioning result in which errors due to improper installation of the first marker are suppressed. The positioning device 1 can output a positioning result in which errors due to improper installation of the second marker are suppressed.

[0121] <Modification> Variation 1 When the installation state of the second marker is determined to be inappropriate a predetermined number of times, the positioning device 1 may determine that the installation state of the second marker is inappropriate. When the installation state of the second marker is determined to be inappropriate, the positioning device 1 may calculate the position of the second marker based on the positioning result of the feature point positioning continued from the first period, and update the position of the second marker included in the map information.

[0122] Furthermore, the positioning device 1 may refrain from updating the position of the second marker included in the map information until it is determined that the installation state of the second marker is inappropriate. This is because it is difficult to determine whether the installation state of the second marker is truly inappropriate or whether the installation state of the second marker has been erroneously determined to be inappropriate by referring to only one determination result. In addition, since the marker is used as the basis of marker positioning, updating the position carelessly may cause errors in marker positioning by other positioning devices, etc.

[0123] Variation 2 The positioning device 1 may notify other moving bodies of the determination result that the installation of the marker is inappropriate. For example, the positioning device 1 may notify other moving bodies of the marker information and position information of the marker whose installation is determined to be inappropriate. The determination result may be notified to other moving bodies via a server, or may be directly notified between moving bodies.

[0124] Variation 3 In the above, the positioning estimation process using feature point positioning is performed when it is determined that the image of the image data does not include a marker or when the result of the marker positioning is not adopted. However, the positioning estimation process using feature point positioning may be performed regardless of whether or not the marker positioning is performed. For example, the marker positioning and the feature point positioning may be performed in parallel before the result of the marker positioning is obtained.

[0125] Variation 4 In the above, the positioning device 1 has been described as a device capable of performing both marker positioning and feature point positioning. However, the present disclosure can also be applied to a positioning device 1 that does not have a marker positioning function. In this case, the position of the positioning device 1 may be estimated using a means other than a marker. For example, it is possible to estimate the relative position with respect to a wireless communication access point from wireless communication parameters, or to use satellite positioning such as GPS. The position of the positioning device 1 may also be estimated from the result of feature point positioning. As described above, feature point positioning is prone to include errors when there is turning, but if there is movement without turning, the position indicated by the result of feature point positioning is sufficiently reliable.

[0126] Variation 5 In the above, when the positioning device 1 uses the result of feature point positioning, the position of the moving object 2 is calculated by adding the relative movement amount calculated by feature point positioning to the position of one frame before. However, the target to which the relative movement amount is added may be a position of two or more frames before. This is because, if the position of one frame before may include an error or margin of error, the position of one frame before is not necessarily more accurate than the position of two or more frames before. In addition, the target position to which the relative movement amount is added may be obtained by any positioning method, such as marker positioning, feature point positioning, or a positioning method using a known method such as satellite signals or wireless communication. In other words, the target position to which the relative movement amount is added may be a past position of the moving object 2.

[0127] Variation 6 In the above, the determination unit 11e determines whether or not the marker is installed using the result of the feature point positioning continued by the continuation unit 11d. However, the determination unit 11e may be configured to perform this determination without using the result of the feature point positioning continued by the continuation unit 11d. In the above, the positioning result to be obtained by continuing the feature point positioning by the continuation unit 11d is a positioning result in which the result of the marker positioning of the first marker is carried over to a position equivalent to the third marker. In other words, if this result can be obtained, it is not necessarily necessary to continue the feature point positioning. For example, the result of the marker positioning of the first marker and the change in the position of the moving object 2 in the second period may be recorded, and the determination unit 11e may calculate the positioning result influenced by the result of the marker positioning of the first marker based on this information when making the determination. Note that the change in the position of the moving object 2 in the second period may be measured by feature point positioning, or may be measured by another method using an acceleration sensor or the like. However, since both feature point positioning and marker positioning can perform positioning based on an image, the configurations of the positioning device 1 and the moving object 2 can be simplified by using feature point positioning.

[0128] Variation 7 In the above-described embodiment, the first marker, the second marker, and the third marker do not necessarily have to be consecutively recognized markers. Another marker may be recognized between the first marker and the second marker, or between the second marker and the third marker. When four or more markers are recognized during a series of operations of the positioning device 1, which markers are to be treated as the first marker, the second marker, and the third marker may be arbitrarily determined based on a user's instruction, a time period, or the like.

[0129] Variation 8 When the positioning device 1 determines that the installation state of the first marker is inappropriate, the positioning device 1 corrects and outputs the positioning result in the first period, but this is not limited to the above. When the positioning device 1 determines that the installation state of the first marker is inappropriate, the positioning device 1 may not output the positioning result in the first period that is affected by the marker positioning result of the first marker.

[0130] Although the embodiment has been described above with reference to the drawings, the present disclosure is not limited to such examples. It is clear that a person skilled in the art can conceive of various modified or amended examples within the scope of the claims. It is understood that such modified or amended examples also belong to the technical scope of the present disclosure. In addition, the components in the embodiment may be arbitrarily combined within the scope of the present disclosure. Calculation may be rephrased as computation.

[0131] In the above-described embodiments, the notation "... part" used for each component may be replaced with other notations such as "... circuit", "... assembly", "... device", "... unit", or "... module".

[0132] The present disclosure can be realized by software, hardware, or software in cooperation with hardware. Each functional block used in the description of the above embodiment may be realized partially or entirely as an LSI, which is an integrated circuit, and each process described in the above embodiment may be controlled partially or entirely by one LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of one chip that includes some or all of the functional blocks. The LSI may have input and output of data. Depending on the degree of integration, the LSI may be called an IC, a system LSI, a super LSI, or an ultra LSI.

[0133] The method of integration is not limited to LSI, but may be realized by a dedicated circuit, a general-purpose processor, or a dedicated processor. Also, after LSI manufacturing, a programmable FPGA (Field Programmable Gate Array) or a reconfigurable processor that can reconfigure the connections and settings of circuit cells inside the LSI may be used. The present disclosure may be realized as digital processing or analog processing.

[0134] Furthermore, if a new integrated circuit technology that can replace LSI appears due to the progress of semiconductor technology or a derivative technology, it is possible to integrate the functional blocks using that technology. The application of biotechnology is also a possibility. [Industrial Applicability]

[0135] The present disclosure is useful for determining the position of a moving object. [Explanation of symbols]

[0136] 1 Positioning device 2. Mobile 3. Camera A2a area A2b~A2e,A3b markers

Claims

1. A receiving unit that receives image data from a camera mounted on the moving object; a marker positioning unit that calculates a position of the moving object based on a marker image included in the image data; a feature point positioning unit that calculates a position of the moving object using past positions of the moving object and feature points of the image data; a determination unit that determines installation states of the first marker and the second marker in accordance with a difference between a position of the moving body calculated by the feature point positioning unit using a result of the marker positioning of the first marker as the past position of the moving body, a position of the moving body calculated by the feature point positioning unit using a result of the marker positioning of the second marker as the past position of the moving body, and a position of the moving body calculated by the marker positioning of the third marker when the marker positioning unit calculates a position of the moving body by the marker positioning of the third marker; A positioning device having the above configuration.

2. The determination unit further a distance unit that calculates a first distance, which is a distance between a position of the moving body calculated by the marker positioning of the third marker and a position of the moving body calculated using a result of the marker positioning of the first marker as the past position of the moving body, and a second distance, which is a distance between the position of the moving body calculated by the marker positioning of the third marker and a position of the moving body calculated using a result of the marker positioning of the first marker as the past position of the moving body, The determination unit determines an installation state of the first marker and the second marker based on at least one of the first distance and the second distance. The positioning device according to claim 1 .

3. The determination unit is comparing the first distance with the second distance to determine an installation state of the first marker and the second marker; The positioning device according to claim 2.

4. The determination unit is If the second distance is greater than the first distance, it is determined that the installation state of the second marker is inappropriate; If the second distance is not greater than the first distance, it is determined that the installation state of the first marker is inappropriate. The positioning device according to claim 3.

5. The positioning device further comprises: a continuing unit that, when the first distance is equal to or greater than a predetermined threshold, continues the feature point positioning of a first period from when the marker positioning of the first marker starts to when the marker positioning of the second marker starts, into a second period from when the marker positioning of the second marker starts to when the marker positioning of a third marker starts; The positioning device according to claim 2.

6. The determination unit is When it is determined that the installation state of the second marker is inappropriate, the continuation unit outputs a positioning result of the continued feature point positioning as a positioning result for the second period; when it is determined that the installation state of the first marker is inappropriate, outputting, as a positioning result for the second period, a positioning result of the marker positioning of the second marker and a positioning result calculated by the feature point positioning unit using the marker positioning result of the second marker as the past position of the moving object. The positioning device according to claim 5.

7. when the determination unit determines that the installation state of the first marker is inappropriate, the determination unit corrects and outputs the positioning result in the first period based on the positioning result of the feature point positioning continued by the continuation unit, which corresponds to a point in time when the marker positioning of the second marker was started, and the positioning result of the marker positioning of the second marker. The positioning device according to claim 6.

8. the determination unit calculates a movement amount for a positioning result of the feature point positioning corresponding to a time point when the marker positioning of the second marker is started to match a positioning result of the marker positioning of the second marker, and moves and outputs the movement amount and the positioning result for the first period. The positioning device according to claim 7.

9. When the determination unit determines that the installation state of the second marker is inappropriate a predetermined number of times, the determination unit calculates a position of the second marker based on a positioning result of the feature point positioning continued by the continuation unit, and updates the position of the second marker included in map information. The positioning device according to claim 5.

10. A notification unit that notifies another positioning device of the determination result of the determination unit. The positioning device according to claim 1 .

11. A camera and a positioning device having: a receiving unit that receives image data from the camera; a marker positioning unit that calculates a position of the moving body based on a marker image included in the image data; a feature point positioning unit that calculates the position of the moving body using past positions of the moving body and feature points of the image data; and a determination unit that, when the marker positioning unit calculates the position of the moving body by marker positioning of a third marker, determines installation states of the first marker and the second marker in accordance with a difference between the position of the moving body calculated by the feature point positioning unit using a result of marker positioning of a first marker as the past position of the moving body, the position of the moving body calculated by the feature point positioning unit using a result of marker positioning of a second marker as the past position of the moving body, and the position of the moving body calculated by marker positioning of the third marker; A mobile object having the above configuration.

12. A receiving unit receives image data from a camera mounted on the moving object, a marker positioning unit that calculates a position of the moving object based on a marker image included in the image data; a feature point positioning unit that calculates a position of the moving object using a past position of the moving object and the feature points of the image data; a determination unit, when the marker positioning unit calculates the position of the moving body by marker positioning of a third marker, determines installation states of the first marker and the second marker according to a difference between a position of the moving body calculated by the feature point positioning unit using a result of marker positioning of the first marker as the past position of the moving body, a position of the moving body calculated by the feature point positioning unit using a result of marker positioning of the second marker as the past position of the moving body, and a position of the moving body calculated by marker positioning of the third marker. Positioning method.

Images