Automated guided vehicle

Abstract

To provide an automated guided vehicle capable of detecting stairs existing within a travel route, grasping a positional relationship between the stairs and a vehicle body on the basis of a shot image taken by a monocular camera, and stably climbing the stairs through autonomous travel.SOLUTION: There is provided a travel control method of an automated guided vehicle capable of autonomously traveling within a travel route including stairs and moving to a destination, including the steps of: imaging a front direction of the automated guided vehicle with a monocular camera fixed to a vehicle body of the automated guided vehicle and irradiating a road surface within an imaging range of the monocular camera with a laser line extending in a direction orthogonal to the front direction of the automated guided vehicle; detecting the stairs based on a change in the laser line shown in a shot image taken by the monocular camera and generating approach angle information on the automated guided vehicle with respect to the stairs; and controlling an advancing direction of the automated guided vehicle based on the approach angle information.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an automated guided vehicle that can easily and safely move toward a destination along a travel route that includes steps and other irregularities while carrying passengers, luggage, and the like. [Background technology]

[0002] One example of an automated guided vehicle that can move along a travel path that includes steps such as stairs is disclosed in Patent Document 1. In the automated guided vehicle disclosed in this document, a travel unit having three radially arranged travel wheels is provided on the left and right sides of the vehicle body. Each of the three travel wheels rotates by itself to travel on a road surface and can revolve around the rotation axis of the travel unit. By appropriately rotating the travel unit around the rotation axis, it is possible to bring any one of the three travel wheels into contact with the road surface.

[0003] On a flat road surface, two of the three running wheels included in the running unit are brought into contact with the road surface and driven to rotate, allowing the vehicle to travel stably on the road surface. When ascending or descending steps such as stairs, the running unit is driven to rotate, causing the running wheels to revolve around the rotation axis of the running unit, and the running wheels that were not in contact with the road surface are brought into contact with the tread of the next step, allowing the vehicle body to be pulled up or down the step.

[0004] On the other hand, in order for such an automated guided vehicle to travel autonomously, it is necessary to detect steps that exist in the travel route and determine whether or not the step can be traversed. A method for detecting steps on road surfaces is known, as disclosed in Patent Document 2.

[0005] The step detection method disclosed in Patent Document 2 involves providing a camera that captures an image in the direction of travel of the vehicle body, and shining a laser line that extends perpendicular to the direction of travel of the vehicle onto the road surface within the camera's imaging range. From changes in the shape of the laser line in the captured image, concave or convex steps on the road surface, such as gratings or braille blocks, are detected. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2012-85854 A [Patent Document 2] JP 2021-105764 A Summary of the Invention [Problem to be solved by the invention]

[0007] The step detection method disclosed in Patent Document 2 detects various floor steps such as braille blocks, drainage ditches, or gratings by grasping changes in the shape of a laser line in an image captured by a camera, but does not obtain specific information required for an automated guided vehicle to travel autonomously from the captured image. In other words, the distance between the automated guided vehicle and the start position of the step, and whether the body of the automated guided vehicle is facing the step directly, cannot be grasped from the image captured by the camera, and it was necessary to install other equipment such as a laser range finder for distance measurement on the automated guided vehicle. [Means for solving the problem]

[0008] The present invention has been made in consideration of these problems, and its objective is to provide an automated guided vehicle that can detect stairs within its travel route, determine the positional relationship between the stairs and the vehicle body from images captured by a monocular camera, and stably traverse stairs while traveling autonomously.

[0009] In other words, the present invention is a driving control method for an automatic guided vehicle that can autonomously travel within a driving route that includes stairs to a destination, comprising: capturing an image of the front of the automatic guided vehicle with a monocular camera fixed to the body of the automatic guided vehicle; irradiating a road surface within the imaging range of the monocular camera with a laser line extending in a direction perpendicular to the front of the automatic guided vehicle; detecting the stairs based on changes in the laser line in the image captured by the monocular camera; generating approach angle information of the automatic guided vehicle relative to the stairs; and controlling the direction of travel of the automatic guided vehicle based on the approach angle information.

[0010] The present invention also provides an automated guided vehicle capable of autonomously traveling along a travel route that includes stairs to a destination, comprising a plurality of traveling units, at least one on each side of a vehicle body, for raising and lowering the vehicle body up and down the stairs, a traveling control unit for controlling the operation of the plurality of traveling units, a monocular camera for capturing an image in the front direction of the automated guided vehicle, a laser light source for irradiating a road surface within the imaging range of the monocular camera with a laser line extending in a direction perpendicular to the front direction of the automated guided vehicle, and a detection control unit for detecting the stairs based on changes in the laser line in the image captured by the monocular camera and generating information on the approach angle of the automated guided vehicle relative to the stairs, and the traveling control unit controls the operation of the plurality of traveling units based on the approach angle information received from the detection control unit. Effect of the Invention

[0011] According to the present invention, by combining a monocular camera with a laser light source and projecting a laser line onto the road surface within the imaging range of the monocular camera, it becomes possible to detect stairs existing in the travel route of the automated guided vehicle from changes in the laser line in the image captured by the monocular camera. In addition, by utilizing the laser line shown in the captured image, it is possible to generate approach angle information of the automated guided vehicle with respect to the stairs, and by using this approach angle information, it becomes possible to face the automated guided vehicle directly with respect to the stairs and allow it to stably ascend and descend the stairs. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing an example of an embodiment of an electric wheelchair to which an automatic guided vehicle of the present invention is applied. [Diagram 2] 1 is a schematic diagram showing how an electric wheelchair according to an embodiment ascends and descends stairs; [Diagram 3] FIG. 2 is a perspective view showing an example of a running wheel according to the embodiment. [Figure 4] 2 is a schematic diagram showing the relationship between a monocular camera and a laser light source provided in the automatic guided vehicle according to the embodiment. FIG. [Diagram 5] FIG. 2 is a block diagram showing a control system of the automated guided vehicle according to the embodiment. [Figure 6] FIG. 2 is a schematic diagram showing an example of an image captured by a monocular camera. [Figure 7] 11 is a schematic diagram showing an example of a laser line in a captured image when an automated guided vehicle approaches a descending staircase at an angle; FIG. [Figure 8] 11 is a schematic diagram showing an example of a laser line in a captured image when an automatic guided vehicle approaches an ascending staircase at an angle. FIG. [Figure 9] 1 is a schematic diagram showing the relationship between edge lines of a staircase and coordinates in an image captured by a monocular camera. [Figure 10] 1 is a schematic diagram showing a method for measuring a straight-line distance to specific points on the left and right of an image captured by a monocular camera. [Figure 11] 1 is a schematic diagram showing a method for measuring the lateral and vertical distances to specific points on the left and right of an image captured by a monocular camera. [Figure 12] FIG. 11 is a schematic diagram illustrating measurement of the distance between a vehicle body and a staircase. [Figure 13] FIG. 2 is a schematic diagram for explaining measurement of the distance between the car body and a staircase when the car body is tilted at a pitch angle Θ. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an automated guided vehicle according to the present invention will be described in detail with reference to the accompanying drawings.

[0014] 1 is a schematic diagram showing an embodiment in which the automated guided vehicle according to the present invention is applied to an electric wheelchair. This electric wheelchair 1 automatically transports a passenger M to a destination by autonomous driving, and is configured to be able to travel on flat ground with the passenger M seated on the seat, as well as to ascend and descend steps such as stairs.

[0015] This electric wheelchair 1 comprises a body 2, four running units 3 provided on the left, right, front and rear of the body 2, and a seating frame 4 that is tiltably mounted on the body 2 and has a seat surface 40 on which a passenger M sits. The seating frame 4 is rotatably coupled to the body 2 via a support shaft 41, and is connected to the body 2 by an actuator (not shown), so that the connection angle of the seating frame 4 to the body 2 can be freely adjusted by expanding and contracting the actuator. The body 2 is also provided with an angle detection sensor (not shown) that detects the pitch angle of the body 2 with respect to the horizontal.

[0016] Therefore, as shown in sub-diagrams a and b of FIG. 2, when the vehicle body 2 tilts relative to the horizontal while ascending or descending a slope or step, the pitch angle is grasped from the signal of the angle detection sensor, and the actuator is controlled to expand and contract based on the signal, so that the connection angle of the seat frame 4 to the vehicle body 2 can be freely changed. Therefore, even when ascending or descending a slope or step with the passenger M seated on the seat 40, the seat 40 can always be kept horizontal regardless of the inclination of the vehicle body 2, so that the passenger M can be assured of his or her safety. Furthermore, although not shown, it is preferable to provide a mechanism that can adjust the center of gravity of the seat frame 4 forward or backward relative to the vehicle body 2 when the vehicle body 2 tilts relative to the horizontal. By providing such an adjustment mechanism, it is possible to eliminate the risk of the electric wheelchair 1 falling while ascending or descending stairs as much as possible.

[0017] Next, the four propulsion units 3 provided on the vehicle body 2 will be described.

[0018] Each traveling unit 3 has three traveling wheels 31 arranged radially around a drive shaft 30, and the three traveling wheels 31 can revolve around the drive shaft 30. The three traveling wheels 31 are connected to a motor as a traveling drive source via a reduction gear, and are rotated in the same direction at the same speed. In addition, a motor as a lifting drive source is connected to the drive shaft 30 of the traveling unit 3, and by driving the traveling unit 3 to revolve, it is possible to selectively bring one or two of the three traveling wheels 31 into contact with a road surface such as the ground or a road surface. Furthermore, the drive shaft 30 of each traveling unit 3 can be arbitrarily switched between revolving drive, stopping, and free rotation.

[0019] Since the electric wheelchair 1 is required to freely change the running direction, it is necessary to provide a steering mechanism for at least the two running units 3 provided on the front side of the device frame 2 or the two running units 3 provided on the rear side of the running units 3. On the other hand, it is also possible to omit the steering mechanism by configuring all three running wheels 31 provided on the running units 3 as so-called omnidirectional wheels. As the omnidirectional wheel, for example, a Mecanum wheel 10 shown in FIG. 3 can be used. This Mecanum wheel 10 is a wheel in which a plurality of sub-rollers 10b having a rotation axis inclined at 45 degrees to the rotation axis of the running wheel main body 10a are arranged on the outer circumferential surface of the rotating running wheel main body 10a, and when the running wheel main body 10a is rotated, the Mecanum wheel 10 itself tries to move in a direction diagonal at 45 degrees to the rotation direction of the running wheel main body 10a.

[0020] The Mecanum wheels 10 are arranged on each running unit 3 so that the rotation axis of the sub-roller 10b faces the center of the device frame 2. For this reason, for example, by making the rotation direction of the Mecanum wheels 10 different between the running unit 3 located at the front side of the device frame 2 and the running unit 3 located at the rear side, the device frame can be moved in the left and right lateral directions. Also, by making the rotation direction of the Mecanum wheels 10 different between the running unit 3 located at the right side of the device frame 2 and the running unit 3 located at the left side, the device frame can be turned on the spot. In this way, all three running wheels 31 provided on the running unit are made into Mecanum wheels 10, and by controlling only the rotation direction of each running wheel, the device frame can be freely moved forward, backward, left and right, moved diagonally, and turned. Incidentally, since the motion control of the robot cart using the Mecanum wheels 10 is well known, a detailed description thereof will be omitted here.

[0021] The electric wheelchair 1 is equipped with a monocular camera 20 and a laser light source 21 to detect obstacles and stairs present in the travel route. As shown in FIG. 4, the monocular camera 20 is attached to a vehicle body 5 consisting of the device frame 2 and the seat frame 3, and captures an image in front of the vehicle body 5. The laser light source 21 combines a laser light source and an optical lens to linearly irradiate laser light (broken line in the figure) and draw a laser line on the road surface F, and the laser line on the road surface F extends in a direction perpendicular to the front direction of the vehicle body 5 (depth direction on the paper). In order to recognize the laser line from the image captured by the monocular camera 20, the laser light source 21 is irradiated to the road surface F within the imaging range of the monocular camera 20, and is also irradiated at a position at a distance L in front of the vehicle body 5. In other words, both ends of the laser line drawn on the road surface by the laser light source 21 are present within the imaging range of the monocular camera 20.

[0022] 5 is a block diagram showing a control system for driving the electric wheelchair 1. The image captured by the monocular camera 20 is input to a detection control unit 22. The detection control unit 22 is realized by a computer including an MPU, and by analyzing the image captured by the monocular camera 20, it detects the presence of obstacles in the driving route and the presence of steps such as stairs, as well as the start position of the stairs, the riser height of each step in the stairs, and the length of the tread, and the signal generated by the detection control unit 22 is input to the driving control unit 7. In addition, the detection signal of the angle detection sensor 23 provided on the vehicle body 5 is input to the detection control unit 22.

[0023] The traveling control unit 7 is realized by a computer including an MPU, which executes a traveling program stored in advance in memory and sends driving signals to the traveling drive source 8 and the lifting drive source 9. In addition, a revolution amount encoder 32 that detects the amount of rotation of the drive shaft 30 is provided on the drive shaft 30 of the traveling unit 3, and a traveling amount encoder 33 that detects the amount of rotation of the traveling wheel 31 is provided on the rotating shaft of the traveling wheel 31, and the detection signals of these encoders are input to the traveling control unit 7 as an index showing the moving distance of the vehicle body relative to the road surface.

[0024] Information about a travel route is stored in the memory of the travel control unit 7, and the travel control unit 7 generates drive signals for the travel drive source 8 and the lift drive source 9 according to the travel route information while taking into account information from the detection control unit 22 and input signals from the revolution amount encoder 32 and the travel amount encoder 33. This controls the revolution, stop, and free rotation of the travel unit 3, and also controls the rotation drive and stop of the travel wheels 31 included in the travel unit 3, making it possible for the electric wheelchair 1 to travel along a predetermined travel route including stairs.

[0025] FIG. 6 shows an example of an image captured by the monocular camera 20, in which a laser line 210 is drawn on the road surface by the laser light source 21. The laser line 210 is shown as a continuous solid line with a higher brightness than the surroundings on the road surface, but in the figure, it is shown as a dashed line for convenience of drawing. When the laser line 210 irradiated on the road surface is captured by the monocular camera 20, the brightness is higher than the surrounding road surface, so that the laser line 210 can be recognized in the captured image. In addition, there is an advantage that the laser line 210 can be clearly recognized by the monocular camera 20 even in a dimly lit indoor environment.

[0026] The length of the laser line 210 projected onto the road surface F is sufficiently larger than the width of the vehicle body 5, but is long enough to fit within the captured image of the monocular camera 20. Therefore, both ends of the laser line 210 are grasped from the captured image. Since the monocular camera 20 and the laser light source 21 provided on the vehicle body 5 are fixed to the vehicle body 5 facing in a predetermined direction, if the road surface is flat, the position of the laser line 210 is always approximately constant in the captured image of the monocular camera 20.

[0027] 7 and 8 show examples of how the laser line 210 projected onto the road surface F appears, with Fig. 7 showing the vehicle body 5 approaching a descending staircase, and Fig. 8 showing the vehicle body 5 approaching an ascending staircase or a wall. When the vehicle body 5 approaches the descending staircase DS at an angle and the laser line 210 reaches the top of the descending staircase DS, as shown in Fig. 7, the laser line 210 shown on the road surface ends at the edge line where the road surface F and the rise face join, and the end of the laser line 210 is projected onto the tread surface D1 of the first step of the descending staircase. In other words, when the vehicle body approaches the descending staircase at an angle, the end of the laser line 210 in the captured image is separated from the laser line projected onto the road surface F, and is recognized as being in a displaced position. As mentioned above, when laser line 210 is projected onto a flat road surface, laser line 210 should be present at a specific position in the captured image. Therefore, when the end of laser line 210 is broken in the captured image and the end is recognized at a displaced position, this means that road surface F does not exist at a continuous height, and the presence of a downward staircase is inferred.

[0028] On the other hand, when the vehicle body 5 approaches the upward staircase US at an angle and the laser line 210 reaches the first step of the upward staircase, as shown in Fig. 8, the laser line 210 shown on the road surface F is bent at the junction of the road surface F and the rise surface U1 of the first step of the upward staircase, and the end of the laser line 210 is irradiated onto the rise surface U1 and bent upward. In other words, the fact that the end of the laser line 210 is bent upward means that the rise surface U1 of the upward staircase US is present at the bent position, and the existence of the upward staircase US is estimated. Incidentally, when the vehicle body 5 approaches a wall or the like at an angle, the end of the laser line 210 is also raised upward, but the existence of the upward staircase can be confirmed by checking against the driving route information stored in the memory.

[0029] The detection control unit 22 performs preprocessing such as noise removal on the captured image acquired from the monocular camera 20, and then binarizes the captured image using an optimal threshold value according to the color and brightness of the laser line 210. This makes it possible to extract and recognize the laser line 210 from the captured image. As described above, if the road surface F is flat, the display position of the laser line 210 in the captured image is approximately constant, and the laser line 210 should exist at a specific coordinate in the captured image. Therefore, by using a method such as pattern matching and checking whether the end of the laser line 210 exists in a specific coordinate area in the captured image, it becomes possible to determine whether the vehicle body 5 has approached a descending staircase or an ascending staircase.

[0030] In this way, it is possible to detect the presence of stairs by focusing on the end of laser line 210 in the image captured by monocular camera 20 and judging whether the end of laser line 210 has disappeared or bent upward from the image captured by monocular camera 20. As a result, when stairs are included in the travel path of the vehicle body 5, the travel control unit 7 can make the vehicle body 5 travel toward the stairs and approach the stairs.

[0031] Next, a method for detecting the distance between the detected staircase and the vehicle body 5, and the angle between the edge line indicating the start position of the staircase and the traveling direction of the vehicle body 5 by analyzing the image captured by the monocular camera 20 will be described.

[0032] In order for the vehicle body 5 to ascend and descend stairs using the traveling units 3, it is necessary to face the vehicle body 5 directly to the stairs and to grasp the distance between the starting position of the stairs and the vehicle body 5. If the front direction of the vehicle body 5 is not perpendicular to the edge line that is the starting position of the stairs, the positional relationship between the traveling units 3 located on the left and right sides of the vehicle body 5 and the stairs becomes unstable, creating a risk of the vehicle body 5 falling down the stairs.

[0033] It should be noted here that the image captured by the monocular camera 20 is a two-dimensional representation of the scenery in the traveling direction of the vehicle body 5, and even if the angle between the edge line of the stairs and the laser line 210 can be grasped in the captured image, it is not the angle between the actual vehicle body and the edge line of the stairs. For this reason, when the detection control unit 22 detects a descending staircase or an ascending staircase, it is necessary to derive the angle K between the actual vehicle body 5 and the edge line of the stairs based on the information obtained from the two-dimensional captured image. Then, the traveling control unit 7 is notified of this angle K as approach angle information. The traveling control unit 7 refers to the approach angle information received from the detection control unit 22, controls the rotational drive of the running wheels of each traveling unit 3 so that the angle K becomes 0, and makes the vehicle body 5 face the stairs directly.

[0034] As described above, the position of the laser line 210 in the image captured by the monocular camera 20 changes at the start position of the stairs, so that the detection control unit 22 can binarize the captured image with an appropriate threshold value, thereby enabling the detection control unit 22 to extract the edges of each stair step as straight lines, similar to the laser line 210. Furthermore, when the image captured by the monocular camera 20 is binarized, depending on the binarization threshold value, the edges of the stairs or the laser line 210 in the captured image may be expressed as partially interrupted dashed lines, in which case the detection control unit 22 determines that the captured image contains multiple straight lines.

[0035] For this reason, the detection control unit 22 searches for all straight lines included in the captured image, detects the angle each straight line makes with the horizontal direction in the captured image, calculates the actual angle K between the car body 5 and the edge line of the stairs, and labels this for each straight line. Then, the detection control unit 22 adds up the angles of each labeled straight line, and notifies the driving control unit 7 of the sum as the approach angle information.

[0036] A method for deriving the actual angle K between the car body 5 and the edge line of the stairs from the image captured by the monocular camera 20 will be described below.

[0037] First, a straight line showing the edge line of the stairs in the captured image can be expressed by the following equation, where the coordinates of both ends of the straight line are (x1, y1) and (x2, y2). Equation (2) is another expression of equation (1).

[0038]

number

[0039] As shown in Fig. 9, when the straight line represented by this equation (1) crosses the captured image, the position where the straight line crosses the left edge of the captured image is PL, its Y coordinate is yL, and the position where the straight line crosses the right edge is PR, its Y coordinate is yR. On the other hand, as shown in Fig. 10, assuming that the optical axis AX of the monocular camera 20 is horizontal, the vertical angle of view of the monocular camera 20 is S degrees, and the height of the monocular camera 20 from the floor surface is C. For example, if the image size in the Y direction of the captured image is 480 pixels, the angles of view SL and SR of the monocular camera 20 corresponding to the positions of the PL and PR (see Fig. 10) can be expressed as follows:

[0040]

number

[0041] Taking this into consideration, the horizontal distance DL from the monocular camera 20 to the PL and the horizontal distance DR to the PR can be expressed by the following equations.

[0042]

number

[0043] 11 shows in a plan view the positional relationship between position PL at the left edge of a captured image, position PR at the right edge, and monocular camera 20. If the angle of view in the lateral (horizontal) direction of monocular camera 20 is N degrees, the lateral distance HL and vertical distance TL from monocular camera 20 to PL, and the lateral distance HR and vertical distance TR from monocular camera 20 to PR can be expressed as follows.

[0044]

number

[0045] As a result, the angle K that the edge line of the staircase makes with the width direction of the vehicle body can be expressed by the following equation.

[0046]

number

[0047] Through the above procedure, the detection control unit 22 can detect the presence of stairs from the image captured by the monocular camera 20, and can also obtain approach angle information indicating the actual inclination angle of the vehicle body 5 relative to the stairs. Then, the traveling control unit 7 controls the rotational drive of the running wheels 31 so that the angle K indicated in the approach angle information becomes 0 degrees, thereby changing the orientation of the device frame 2. When the vehicle body 5 faces the stairs directly, both the laser line 210 and the edge of the stairs are parallel to the horizontal direction of the captured image, so the sum of the angles that the straight lines in the captured image make with the horizontal direction becomes 0 degrees, and this ends the control of facing the vehicle body 5 directly to the stairs.

[0048] Next, measurement of the distance between the car body 5 and the start position of the stairs will be described.

[0049] As already explained, the electric wheelchair 1 shown in Fig. 1 can ascend and descend stairs by revolving the three radially arranged running wheels 31 around the drive shaft 30. However, in order to do so, it is important to know the distance between the body 5 and the start position of the rise of the stairs. If this distance cannot be known, even if the body 5 can be positioned directly facing the stairs, it is not possible to determine whether to revolve the three running wheels 31 to ascend and descend the stairs, or to rotate and drive the running wheels 31 themselves to reduce the distance to the stairs, and the stairs cannot be ascended and descended appropriately.

[0050] 4 shows an outline of a method for measuring the distance between a vehicle body 5 and an obstacle 10 when the obstacle 10 is located ahead in the traveling direction of the vehicle body 5. That is, when the vehicle body 5 is traveling toward a staircase, the obstacle 10 can be considered as the rise of the staircase.

[0051] The distance from the vehicle body 5 to the laser line 210 projected onto the road surface F is L, the distance from the vehicle body to the obstacle 10 is D, the height from the road surface F to the laser light source 21 is H, and the height (imaging height) on the laser line 210 projected onto the road surface that falls within the imaging range of the monocular camera 21 is T. max The height of the laser line 210 projected onto the front surface of the obstacle 10 from the road surface 7 is T R Let us assume that.

[0052] FIG. 12 shows an example in which the state where the laser line 210 is irradiated on the rise surface of the stairs is captured by the monocular camera 20, and the captured image is further processed and converted into a binary image. However, in FIG. 12, white and black are interchanged for the sake of drawing, and the laser line 210 generated in front of the obstacle 10 is represented in black, and the rest is represented in white. The detection control unit 22 acquires color information of the laser light emitted from the laser light source 21 in advance, and uses it as a threshold range when generating a binary image. The captured image is divided into 4 pixels in the horizontal direction and 8 pixels in the vertical direction of the image frame, and 4×8 pixels are set as one pixel, and each of these pixels is compared with the threshold range of the color information of the laser light. At that time, since the laser line 210 is irradiated in a line along the horizontal direction, one pixel closest to the threshold range is selected from the pixel row extending in the vertical direction in the captured image, and the selected pixel is classified as white and the rest are classified as black, and the entire frame of the captured image is binarized. In addition, since there is a risk of erroneously acquiring color information other than that of the laser line 210, and since there is a risk that the white pixels extracted one for each column in the captured image will not form a horizontal line even though the laser line 210 that is actually seen is a horizontal line, the created binary image is repeatedly compressed and expanded using a kernel transformation.

[0053] As a method for automatically detecting the laser line 210 from the binarized image, the range expressing the laser line 210 is grouped and surrounded by a rectangular detection frame (dashed frame in the figure) as shown in Fig. 12, and two coordinates located diagonally opposite each other in the detection frame, i.e., the upper left coordinate (x01, y01) and the lower right coordinate (x02, y02), are extracted. Note that, although a detection frame with height is shown surrounding the laser line 60 in Fig. 12, if the vehicle body 5 faces the obstacle 10 directly and the laser line 210 extends horizontally without tilting in front of the obstacle 10, the detection frame will be a straight line with no height, and the height components y01 and y02 of the upper left coordinate and the lower right coordinate of the rectangle will be the same value.

[0054] As shown in Fig. 4, the monocular camera 20 and the laser light source 21 are fixed to the vehicle body 5, so that the position of the laser line 210 projected onto the road surface F without being blocked by the obstacle 10 is always constant in the captured image. As described above, the laser line 210 on the road surface is not displayed in the binarized image captured by the monocular camera 21, but the laser line 210 projected onto the road surface F can be recognized from the captured image before the binarization. If the position of the laser line 210 projected onto the road surface F in the captured image is assumed to be the position of the dashed dotted line in Fig. 12, the height from this dashed dotted line to the top of the captured image is the captured height T of the laser line 210 on the road surface. max Therefore, as shown in FIG. 13, the number of pixels from the dashed line in the captured image to the top of the captured image is t m If the number of pixels from the dashed line to the laser line 210 projected on the front surface of the obstacle 10 is t, the height T of the laser line 210 from the road surface 7 on the front surface of the obstacle 10 is R can be expressed as follows using the similarity ratio of triangles:

[0055]

number

[0056] Moreover, the distance D from the vehicle body 5 to the obstacle 10 can be expressed by the following formula.

[0057]

number

[0058] At this time, depending on the settings of the laser light source 21 and the monocular camera 20 for the vehicle body 5, max and t m is known, and the above-mentioned t can be found from the number of pixels corresponding to the y coordinate of the detection frame surrounding the laser line 210 in the binarized image, so by using the above-mentioned two equations, the distance D from the vehicle body to the obstacle 10 can be measured. This measurement of the distance D is performed sequentially.

[0059] When the detection control unit 22 completes the measurement of the distance between the vehicle body 5 and the rise of the staircase located in front of it as described above, it transmits the measurement as step distance information to the traveling control unit 7. When the traveling control unit 7 receives the step distance information, it supplies a drive signal to the traveling drive source 8 or the lifting drive source 9. When the vehicle body 5 and the rise of the staircase are sufficiently close to each other, the traveling control unit 7 supplies a drive signal to the lifting drive source 9 to revolve the traveling unit 3. This causes one of the running wheels 31 to abut against the tread of the next step of the stairs, allowing the vehicle to ascend and descend one step of the stairs.

[0060] On the other hand, if the distance between the vehicle body 5 and the rise of the stairs is greater than a predetermined value, one of the running wheels 31 cannot be brought into contact with the tread of the next step of the stairs even if the traveling unit 3 is revolved, so the traveling control unit 7 supplies a drive signal to the traveling drive source 8, rotates the running wheels 31 and brings the vehicle body 5 closer to the stairs without revolving the traveling unit 3. After this, the detection control unit 22 again measures the distance between the vehicle body 5 and the stairs, and if the distance is less than a predetermined value, the traveling control unit 7 supplies a drive signal to the lifting drive source 9, causing the traveling unit 3 to revolve.

[0061] On the other hand, even if the electric wheelchair 1 is climbing stairs and a laser line 210 is projected onto the next rise surface U2 of the stairs US as shown in Figure 13 and this is imaged by the monocular camera 20, since the monocular camera 20 and the laser light source 21 are fixed to the vehicle body 5, if the vehicle body 5 is inclined in the fore-and-aft direction relative to the horizontal, it is impossible to accurately calculate the distance between the vehicle body 5 and the next rise surface based on the positional relationship as shown in Figure 4.

[0062] For this reason, the detection control unit 22 reads out the pitch angle Θ of the car body from the angle detection sensor 23, and uses this pitch angle Θ to correct the distance between the car body 5 and the rise surface while ascending the stairs. If the pitch angle of the car body 5 while ascending the stairs US is angle Θ with respect to the horizontal, the monocular camera 20 and laser light source 21 fixed to the car body 5 will also be tilted at the pitch angle Θ. For this reason, the coordinate axes in Fig. 13 are tilted by the pitch angle Θ from those in Fig. 4. For reference, the various distances shown in Fig. 4 are shown in Fig. 13 with the same symbols.

[0063] Therefore, the distance D calculated by the above-mentioned method is the distance from the car body to the point M. From this, the horizontal distance Dt from the car body 5 to the riser surface U2 located in front of it can be expressed as follows using the pitch angle Θ.

[0064]

number

[0065] After calculating the distance D, the detection control unit 22 performs a correction calculation using the pitch angle Θ if the pitch angle Θ is not zero, and transmits the result to the traveling control unit 7. This makes it possible to measure the horizontal distance from the car body 5 to the riser surface located in front of it, regardless of whether the car body 5 is tilted at the pitch angle Θ. The traveling control unit 7 then receives the measurement result from the detection control unit 22 and supplies a drive signal to the traveling drive source 8 or the lifting drive source 9.

[0066] As described above, according to the electric wheelchair 1 of this embodiment, a monocular camera 20 is combined with a laser light source 21, a laser line 210 is projected onto the road surface within the imaging range of the monocular camera 20, and the start positions of the descending stairs and ascending stairs can be detected by determining the position of the end of the laser line 210 in the captured image.

[0067] In addition, the edge lines of each step of the stairs can be extracted from the image captured by the monocular camera 20, and the actual angle between the vehicle body 5 and the stairs can be measured from the planar image of the monocular camera 20, making it possible to face the electric wheelchair 1 directly against the stairs.

[0068] Furthermore, even while the vehicle body 5 is climbing stairs, it is possible to measure the horizontal distance between the next rise of the stairs and the vehicle body 5, and it is possible to appropriately drive the traveling unit 3 to safely ascend and descend the stairs.

[0069] In this embodiment, an example in which the automatic guided vehicle of the present invention is applied to an electric wheelchair 1 has been specifically described, but by replacing the seat frame 4 with a loading platform frame, the present invention can also be applied to uses other than wheelchairs, such as transporting luggage. [Explanation of symbols]

[0070] 1...electric wheelchair, 2...device frame, 3...running unit, 4...seating frame, 5...body, 10...mecanum wheel, 20...monocular camera, 21...laser light source, 31...running wheel, 210...laser line

Claims

1. A method for controlling travel of an automated guided vehicle that can autonomously travel along a travel route including stairs to a destination, comprising: capturing an image of a front direction of the automated guided vehicle with a monocular camera fixed to a body of the automated guided vehicle, and irradiating a road surface within an imaging range of the monocular camera with a laser line extending in a direction perpendicular to the front direction of the automated guided vehicle; detecting the staircase based on a change in the laser line in an image captured by the monocular camera, and generating approach angle information of the automated guided vehicle relative to the staircase; a travel control method for an automated guided vehicle, the method comprising: controlling a travel direction of the automated guided vehicle based on the approach angle information;

2. Detecting an edge line that is a starting position of the staircase from the captured image; 2. The method for controlling travel of an automatic guided vehicle according to claim 1, further comprising generating information on an approach angle of the automatic guided vehicle with respect to the stairs from a relationship between a position of an edge line in the captured image and an angle of view of the monocular camera.

3. generating step distance information relating to a horizontal distance between the vehicle body and a staircase located in front of the vehicle body from a relationship between a position of the laser line in an image captured by the monocular camera and pixels constituting the captured image; 2. The method for controlling travel of an automatic guided vehicle according to claim 1, wherein travel of the automatic guided vehicle is controlled based on the step distance information.

4. Detecting a pitch angle of the vehicle body from an angle detection sensor mounted on the vehicle body; 4. The method for controlling travel of an automatic guided vehicle according to claim 3, further comprising the step of correcting the step distance information using the pitch angle.

5. An automated guided vehicle that can autonomously travel along a route including stairs to a destination, A plurality of travel units, at least one of which is provided on each of the left and right sides of a vehicle body, for raising and lowering the vehicle body relative to the stairs; A driving control unit that controls the driving of the plurality of driving units; A monocular camera that captures an image in the front direction of the automated guided vehicle; a laser light source that irradiates a road surface within an imaging range of the monocular camera with a laser line extending in a direction perpendicular to a front direction of the automated guided vehicle; a detection control unit that detects the stairs based on a transformation of the laser line in an image captured by the monocular camera and generates approach angle information of the automated guided vehicle with respect to the stairs; The automated guided vehicle is characterized in that the driving control unit controls the drive of the multiple driving units based on the approach angle information received from the detection control unit.

6. The automated guided vehicle according to claim 5, characterized in that the detection control unit detects an edge line that is the starting position of the stairs from the image captured by the monocular camera, and generates information about the approach angle of the automated guided vehicle relative to the stairs from the relationship between the position of the edge line in the captured image and the angle of view of the monocular camera.

7. the detection control unit generates step distance information relating to a horizontal distance between the vehicle body and a staircase located in front of the vehicle body from a relationship between a position of the laser line in an image captured by the monocular camera and pixels constituting the captured image; 6. The automated guided vehicle according to claim 5, wherein the travel control unit controls travel of the automated guided vehicle based on the step distance information received from the detection control unit.

8. The vehicle body is equipped with an angle detection sensor that detects a pitch angle of the vehicle body, 8. The automated guided vehicle according to claim 7, wherein the detection control unit corrects the step distance information using the detected pitch angle.

9. Each traveling unit is capable of traveling on a road surface by being rotated by a traveling drive source, includes three traveling wheels equiangularly arranged around a rotation axis, and can revolve these traveling wheels around the rotation axis by an elevation drive source; 9. The automated guided vehicle according to claim 8, wherein the travel control unit controls operations of the travel drive source and the revolution drive source based on the step distance information.

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