JP7590241B2 - Road marking device and road marking method - Google Patents

Description

Article 30, Paragraph 2 of the Patent Act: Proceedings and Abstracts of the 2020 Construction and Construction Machinery Symposium and its CD-ROM (Published: December 2, 2020)

The present invention relates to a road marking device and a road marking method for drawing lines on a road surface.

In preparation for paving work, road marking work is carried out to draw lines on the road surface, such as cutting boundaries for the overlay method of repairing asphalt pavement. Road marking work on roads in service requires two workers to stretch both ends of the string, one worker to flick the string to transfer powdered chalk to the road surface, and one safety monitor to check the safety of the surrounding area. For this reason, with the aim of reducing the labor required for road marking work, a technology has been proposed in which a marking tool is used to mark the road surface while a self-propelled cart is driven according to a pre-entered movement program, as described in JP 2001-289638 A (Patent Document 1).

JP 2001-289638 A

When carrying out cutting and overlay construction on expressways and other roads, the standard for alignment and width adjustment is almost always the existing centerline (dashed line), and in many cases no drawings or coordinates are used. At such paving sites, inputting a movement program using drawings and coordinates is time-consuming, and the technology proposed in Patent Document 1 is difficult to use, especially in repair work that is subject to time constraints.

Therefore, the present invention aims to provide a road marking device and a road marking method for road marking work, which involves drawing lines on a road surface, that can reduce the amount of work required for advance preparations such as inputting a movement program, and can reduce the number of workers required to draw the lines while ensuring safety.

The road marking device includes a traveling cart capable of autonomous driving, a camera mounted on the traveling cart to capture images of the area ahead, a marking device mounted on the traveling cart to draw lines on the road surface, a target placed on the road surface in front of the traveling cart, and an electronic control device mounted on the traveling cart. The electronic control device is configured to capture an image including the target with the camera, process the image to recognize the target, and drive the traveling cart toward the target while drawing a line on the road surface with the marking device.

The road marking method also uses the above-mentioned road marking device to draw a line on the road surface from a first point where the traveling cart is placed to a second point where the target is placed.

The present invention reduces the amount of work required for advance preparation in road marking work, which involves drawing lines on a road surface, and can reduce the number of workers required to draw the lines while ensuring safety.

1 is a schematic diagram showing a first embodiment of a road marking device; FIG. 2 is a rear view illustrating an example of the traveling carriage according to the first embodiment. FIG. 4 is a side view showing an example of the traveling carriage of the first embodiment with the arms folded. FIG. 2 is a schematic diagram showing an example of a control system for the traveling carriage. FIG. 2 is a front view showing an example of a target. 13 is a flowchart showing an example of a road marking process. FIG. 2 is an explanatory diagram illustrating an example of a forward image. FIG. 13 is an explanatory diagram of a state in which a light-emitting object is recognized from a forward image. FIG. 11 is an explanatory diagram showing an example of a line drawn between center lines. An explanatory diagram of the road marking work of drawing lines between center lines. FIG. 1 is an explanatory diagram of a method for drawing a center line on a curved road. FIG. 4 is a schematic diagram showing a second embodiment of the road marking device. FIG. 11 is a rear view illustrating an example of the traveling carriage according to the second embodiment. FIG. 11 is a side view illustrating an example of the traveling carriage according to the second embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
1 and 2 show a first embodiment of a road marking device 100 for drawing lines on an asphalt road surface (hereinafter abbreviated as "road surface"), for example, in preparation for a cutting and overlaying method on a highway.

The road surface marking device 100 includes a traveling cart 200 capable of autonomous driving, a camera 300 that captures images in front of the traveling cart 200, a marking device 400 that draws lines on the road surface RS, an electronic control device 500, a controller 600 with a button attached, and a target 700 that is placed on the road surface RS in front of the traveling cart 200.

The traveling cart 200 is composed of a body 210 consisting of a skeleton frame and a dustproof and waterproof casing that encases the skeleton frame, a pair of left and right front wheels 220 (left front wheel 220L and right front wheel 220R) attached to the front of the body 210, one rear wheel 230 consisting of a swivel caster attached to the rear of the body 210, electric motors 240 (left electric motor 240L and right electric motor 240R) that independently rotate the left front wheel 220L and the right front wheel 220R, and a battery (not shown).

On the top surface of the vehicle body 210, at a predetermined location on the center line extending in the front-rear direction, an arm 250 is attached which rotates together with the rotating shaft 210A extending in the vertical direction and can be displaced between an deployed position A located to the right of the vehicle body 210 and a stored position B (position indicated by a dashed line in the figure) located at the rear of the vehicle body 210. The arm 250 is configured to include a rod-shaped first arm member 252 connected to the rotating shaft 210A, a rod-shaped second arm member 254 connected to the first arm member 252, and a holder 256 connected to the second arm member 254 to hold the camera 300 and the marking device 400. The holder 256 is configured to include a base member 256A having a rectangular shape in a plan view, and a running wheel 256B consisting of a swivel caster attached to a predetermined location of the base member 256A.

The base end of the first arm member 252 is connected to the rotation axis 210A of the vehicle body 210 so as to be rotatable relative to the rotation axis 210A around the rotation axis 250A perpendicular to the rotation axis 210A. The base end of the second arm member 254 is connected to the tip of the first arm member 252 so as to be rotatable relative to the rotation axis 250B parallel to the rotation axis 250A. The upper surface of the base member 256A of the holder 256 is connected to the tip of the second arm member 254 so as to be rotatable relative to the rotation axis 250C parallel to the rotation axis 250B. Therefore, the arm 250 can be displaced from the deployment position A shown in FIG. 1 to the storage position B shown in FIG. 3 by rotating the first arm member 252, the second arm member 254, and the holder 256 around the rotation axis 210A of the vehicle body 210 while folding them. By displacing the arm 250 to storage position B, the arm 250 does not get in the way when transporting and storing the road marking device 100, improving convenience.

The camera 300 is, for example, a near-infrared camera capable of capturing images of near-infrared light, which is an example of invisible light, and is attached to a predetermined location, for example, the front, on the upper surface of the base member 256A of the holder 256 so that it can capture images of the front when the arm 250 is displaced to the deployment position A relative to the vehicle body 210. The marking device 400 is, for example, a device that draws lines on the road surface RS by pushing a paint spray with an actuator (not shown), and is attached behind the camera 300 when the arm 250 is displaced to the deployment position A relative to the vehicle body 210. The marking device 400 is not limited to a paint spray, and may be configured to draw lines on the road surface RS with marking chalk.

The electronic control device 500 has a built-in microcomputer that integrates a processor such as a CPU (Central Processing Unit), a non-volatile memory such as a flash ROM (Read Only Memory), a volatile memory such as a RAM (Random Access Memory), an input/output circuit for inputting and outputting analog and digital signals, a timer, etc. The microcomputer of the electronic control device 500 is connected to the camera 300 that captures images in front of the traveling cart 200, the left electric motor 240L that drives the left front wheel 220L, the right electric motor 240R that drives the right front wheel 220R, and the marking device 400 via the input/output circuit, as shown in FIG. 4, so as to be able to input and output any electric signal.

The controller 600 is, for example, a console held by an operator who draws a line on the road surface RS, and remotely controls the traveling cart 200 and the camera 300 and marking device 400 mounted thereon, and is connected to the microcomputer of the electronic control device 500 via a wired cable CB. A button is attached to a predetermined location of the controller 600, for example, a location that is easy for the operator to operate, and the microcomputer of the electronic control device 500 is configured to operate the traveling cart 200, the camera 300, and the marking device 400 only when the operator operates this button. Therefore, the traveling cart 200 travels only when the button of the controller 600 is operated, so that the safety of the work and the surroundings can be ensured. Note that the controller 600 is not limited to a configuration in which it is connected to the electronic control device 500 mounted on the traveling cart 200 via a wired cable CB, and may be connected to the electronic control device 500 via wireless. In this case, the controller 600 may be a mobile terminal such as a tablet terminal or a smartphone.

As shown in FIG. 5, the target 700 is composed of a base member 710 placed on the road surface RS, a standing member 720 having a rectangular cross section standing upward from the upper surface of the base member 710, a light-emitting body 730 attached to one side of the standing member 720 at two positions spaced apart in the vertical direction, and a back plate 740 covering the background on the back side of the light-emitting body 730. The light-emitting body 730 is made of an LED (Light Emitted Diode) that emits near-infrared light, which is an example of invisible light that cannot be seen by humans, so as not to be a hindrance to drivers of vehicles traveling around and to be distinguished from sunlight. Here, the two light-emitting bodies 730 are arranged in a vertically spaced state, making them unique among artificial or natural objects and easy to distinguish from other objects. The back plate 740 is made of a rectangular plate material that extends vertically and horizontally from the ends of the two light emitters 730 attached to the standing member 720 when viewed from the front of the target 700, and the surface facing the light emitters 730 is painted black. Therefore, since the back plate 740 painted black is located on the back side of the light emitters 730, the influence of the surrounding scenery can be reduced.

When drawing a line on the road surface RS, the worker places the traveling cart 200 at the end of the existing center line and places the target 700 at the start of the next center line. At this time, the worker sets up the traveling cart 200 so that the centers of the camera 300 and marking device 400 are located at the center of the center line, and places the target 700 so that the left-right center of the light-emitting body 730 is located at the center of the center line. The worker then operates a button attached to the controller 600 to start the road surface marking work.

Figure 6 shows an example of a road marking process that is executed by the microcomputer of the electronic control unit 500 when an operator operates a button on the controller 600. The microcomputer of the electronic control unit 500 executes the road marking process according to an application program stored in the non-volatile memory.

In step 10 (abbreviated as "S10" in FIG. 6, and the same applies below), the microcomputer of the electronic control device 500 reads an image of the front including the target 700 (forward image) from the camera 300. The forward image read from the camera 300 is temporarily stored in the volatile memory of the microcomputer and is used for subsequent processing (and the same applies below).

In step 11, the microcomputer of the electronic control device 500 performs a predetermined image processing on the forward image temporarily stored in the volatile memory, as described in detail below, to determine whether or not the target 700 emitting near-infrared light has been recognized. If the microcomputer of the electronic control device 500 has recognized the target 700 (Yes), the process proceeds to step 12. On the other hand, if the microcomputer of the electronic control device 500 cannot recognize the target 700 (No), the microcomputer of the electronic control device 500 ends the road marking process. If the target 700 cannot be recognized, it is considered that the installation direction of the traveling cart 200 relative to the target 700 is inappropriate, and the operator may be notified of this by, for example, turning on a warning lamp attached to the controller 600 or activating a buzzer.

Here, the recognition process of the target 700 by the microcomputer of the electronic control device 500 will be described. The microcomputer of the electronic control device 500 first narrows down the candidate light sources for the target 700 by removing pixels with a predetermined light intensity or less from the forward image. The microcomputer of the electronic control device 500 then identifies, from among the candidate light sources, a light source that has light sources in two positions spaced apart in the vertical direction, i.e., a light emitter 730 specific to the target 700, thereby recognizing the target 700.

In step 12, the microcomputer of the electronic control unit 500 determines whether the button attached to the controller 600 is still being operated. If the microcomputer of the electronic control unit 500 determines that the button is still being operated (Yes), it advances the process to step 13. On the other hand, if the microcomputer of the electronic control unit 500 determines that the button is no longer being operated, in other words, if the worker has stopped the road marking work for some reason (No), it advances the process to step 19 to end the road marking work.

In step 13, the microcomputer of the electronic control device 500 outputs a drive signal to the electric motors 240 that rotate the pair of left and right front wheels 220, thereby causing the traveling cart 200 to travel. At this time, the microcomputer of the electronic control device 500 outputs drive signals of the same magnitude to the left electric motor 240L that rotates the left front wheel 220L and the right electric motor 240R that rotates the right front wheel 220R, causing the traveling cart 200 to travel in a straight line.

In step 14, the microcomputer of the electronic control device 500 outputs an activation signal to the marking device 400 to draw a road surface RS line. At this time, the microcomputer of the electronic control device 500 may control the actuator according to the ON time and OFF time set in advance to draw a dashed line on the road surface RS, or may draw a solid line on the road surface RS, as an example of a line.

In step 15, the microcomputer of the electronic control device 500 reads a forward image including the target 700 from the camera 300.

In step 16, the microcomputer of the electronic control device 500 recognizes the target 700 by performing a predetermined image processing on the forward image temporarily stored in the volatile memory, similar to step 11.

In step 17, the microcomputer of the electronic control device 500 controls the drive signal output to the electric motor 240 that rotates the pair of left and right front wheels 220 so that the light-emitting body 730 of the target 700 recognized in the forward image approaches the center in the left-right direction of the forward image. Specifically, if the light-emitting body 730 is located to the right of the center in the left-right direction in the forward image, the microcomputer of the electronic control device 500 outputs a drive signal to the left electric motor 240L that rotates the left front wheel 220L that is larger than the right electric motor 240R that rotates the right front wheel 220R, thereby steering the traveling cart 200 to the right. On the other hand, if the light-emitting body 730 is located to the left of the center in the left-right direction in the forward image, the microcomputer of the electronic control device 500 outputs a drive signal to the right electric motor 240R that rotates the right front wheel 220R that is larger than the left electric motor 240L that rotates the left front wheel 220L, thereby steering the traveling cart 200 to the left. By appropriately steering the traveling carriage 200 in the left-right direction in this manner, the microcomputer of the electronic control device 500 can displace the positions of the camera 300 and the marking device 400, which are positioned offset via the arm 250 relative to the body 210 of the traveling carriage 200, and draw a straight line toward the target 700. At this time, the microcomputer of the electronic control device 500 may change the steering amount of the front wheels 220 according to the distance between the left-right center of the forward image and the target 700, for example, by increasing the steering amount as the distance increases.

In step 18, the microcomputer of the electronic control device 500 refers to the forward image temporarily stored in the volatile memory, and determines whether the light-emitting body 730 of the target 700 shown therein is equal to or larger than a predetermined size, thereby determining whether the traveling vehicle 200 has approached the target 700. If the microcomputer of the electronic control device 500 determines that the traveling vehicle 200 has approached the target 700 (Yes), it advances the process to step 19. On the other hand, if the microcomputer of the electronic control device 500 determines that the traveling vehicle 200 is not approaching the target 700 (No), it returns the process to step 12 to continue the road marking work.

In step 19, the microcomputer of the electronic control device 500 stops the driving signal output to the electric motor 240 that rotates and drives the pair of left and right front wheels 220, thereby stopping the traveling of the traveling cart 200. The microcomputer of the electronic control device 500 also stops the operation signal output to the marking device 400, thereby halting the marking work of drawing lines on the road surface RS. Thereafter, the microcomputer of the electronic control device 500 ends the road surface marking process.

According to this road marking process, the microcomputer of the electronic control device 500 recognizes the light-emitting body 730 of the target 700 from the forward image captured by the camera 300, and controls and steers the electric motor 240 of the traveling carriage 200 so that the light-emitting body 730 approaches the center of the forward image in the left-right direction. Therefore, as shown in FIG. 9, a dashed line is drawn by the marking device 400 from the end of the center line of the road surface RS to the start of the next center line. At this time, when the traveling carriage 200 approaches the target 700, the traveling carriage 200 automatically stops and the road marking work is stopped, so that the worker does not need to keep a close eye on the traveling carriage 200 and can pay attention to the surrounding situation to ensure safety.

In such road marking work, there is no need to input drawings or coordinates as advance preparation, and the labor required for advance preparation can be reduced. In addition, only a worker who places the traveling cart 200 at the end of the center line, a worker who places the target 700 at the start of the center line, and a worker who operates the controller 600 are required, and the number of workers who draw the lines can be reduced compared to the conventional technology. Furthermore, since the labor required for advance preparation and the number of workers can be reduced, work efficiency can be improved, and the construction period can be shortened and costs can be reduced. Note that the worker who places the traveling cart 200 at the end of the center line, the worker who places the target 700 at the start of the center line, and the worker who operates the controller 600 may be the same or different.

In addition, during road marking work, workers do not need to continuously work in a half-crouched position or repeatedly "squat" and "stand", which reduces the physical burden on the worker. And because the burden on the worker is reduced, the worker has more time to pay attention to the situation around them, which also improves safety.

Furthermore, since the camera 300 and the marking device 400 are positioned at a position offset laterally from the traveling carriage 200 via the arm 250, the traveling carriage 200 does not need to run on the center line, and in the case of public construction, it does not get in the way of vehicles running in adjacent lanes. In addition, work near the public lanes is reduced, improving the safety of workers.

Now, with reference to Figure 10, we will explain how to draw a line between two consecutive centerlines using an existing centerline drawn on the road surface RS as a reference.

In the first step, the worker sets up the traveling cart 200 at the starting position where the worker starts drawing a line on the road surface RS, i.e., at the end of one of the center lines CL1. At this time, the worker sets up the traveling cart 200 on the road surface RS so that the camera 300 and marking device 400 mounted on the traveling cart 200 are positioned at the center of the width of the center line CL1.

In the second step, the worker places the target 700 on the road surface RS at the end position where the line is to be drawn, i.e., at the beginning of the other center line CL2. At this time, the worker places the target 700 on the road surface RS so that the light-emitting body 730 of the target 700 is positioned at the center of the width of the center line CL2.

In the third step, the worker operates the button on the controller 600 connected to the traveling cart 200 via the wired cable CB. The traveling cart 200 then starts moving, and a line LN begins to be drawn between the two consecutive center lines CL1 and CL2. At this time, the worker walks along following the traveling cart 200 while operating the button on the controller 600. Here, the workers who perform the first step, second step, and third step may be the same or different.

When the traveling cart 200 travels, the electric motors 240 that rotate and drive the pair of left and right front wheels 220 are individually controlled and steered so that the light-emitting body 730 of the target 700 in the forward image captured by the camera 300 approaches the center in the left-right direction. Therefore, if the traveling cart 200 is traveling at an angle in the left-right direction with respect to an imaginary line connecting the end of one center line CL1 and the start of the other center line CL2, the traveling cart 200 is steered to the opposite side of the angle, and the traveling cart 200 travels along the imaginary line. Then, when the traveling cart 200 approaches the target 700, the traveling cart 200 automatically stops and the road marking work is discontinued.

In the fourth step, when the traveling cart 200 stops, the operator operating the controller 600 stops operating the button. This causes a line LN to be drawn between the two consecutive center lines CL1 and CL2, and then, if necessary, the traveling cart 200 is transported and placed in a position to draw the next line, and the above first to third steps are repeated in sequence.

In short, using the above-mentioned road surface marking device 100, the traveling cart 200 is moved from a first point where the traveling cart 200 is set up to a second point where the target 700 is placed, while the marking device 400 draws a line on the road surface RS.

When the road surface RS on which the line LN is drawn is a curved road with a relatively small curvature as shown in FIG. 11, if the line LN is drawn in a straight line from the end of one of two consecutive center lines CL to the start of the other center line CL, the widthwise deviation of the line LN may exceed the allowable error. To deal with this, the steering angle of the traveling carriage 200 by the electric motor 240 that rotates and drives the pair of left and right front wheels 220 in one control cycle may be limited to an angle according to the curvature radius of the curved road. In this case, the steering angle of the traveling carriage 200 can be set arbitrarily, for example, using a control panel (not shown) attached to a predetermined location of the traveling carriage 200, or can be set arbitrarily using the controller 600. By limiting the steering angle of the traveling carriage 200, it is possible to approximate the virtual line connecting the two consecutive center lines CL with an arc by a polygon, and the widthwise deviation of the line LN drawn on the road surface RS can be kept within the allowable range.

Figures 12 to 14 show a second embodiment of the road marking device 100. In the following explanation, the same components as those in the road marking device 100 of the first embodiment are given the same reference numerals to avoid redundant explanations and to omit or simplify the explanation. If necessary, please refer to the explanation of the road marking device 100 of the first embodiment.

As in the first embodiment, the road marking device 100 includes a self-propelled traveling cart 200, a camera 300 that captures an image in front of the traveling cart 200, a marking device 400 that draws lines on the road surface RS, an electronic control device 500, a controller 600 with a button attached, and a target 700 that is placed on the road surface RS in front of the traveling cart 200.

The camera 300 is attached to a stand 210B attached to the front of the upper surface of the body 210 of the traveling cart 200 at a central position in the left-right direction of the traveling cart 200. At this time, the camera 300 is positioned so that the left-right center line of its imaging range coincides with the center line extending in the front-rear direction of the traveling cart 200.

The marking device 400 is attached to a holder 256 located at the left-right center of the rear of the vehicle body 210. At this time, the marking device 400 is attached so as to be located on the center line extending in the front-rear direction of the traveling carriage 200. Therefore, the camera 300 and the marking device 400 are each located on the center line extending in the front-rear direction of the traveling carriage 200.

In this type of road marking device 100, the camera 300 and marking device 400 are arranged on the center line extending in the fore-and-aft direction of the traveling carriage 200. This makes it easy to set up the traveling carriage 200 at the line drawing start position, thereby shortening the time required for installation. Note that, except for the action and effect of the arm 250, the action and effect of the road marking device 100 of the second embodiment are similar to those of the first embodiment, so a description thereof will be omitted. If necessary, please refer to the action and effect of the road marking device 100 of the first embodiment.

A person skilled in the art will easily understand that new embodiments can be created by omitting parts of the technical ideas of the various embodiments described above, combining parts of them as appropriate, or replacing parts of them with well-known technology.

As one example, the traveling cart 200 is not limited to a pair of left and right front wheels 220 and one rear wheel 230, but may have any number of front wheels 220 and rear wheels 230 as long as the conditions of steering and running are met. In addition, the traveling cart 200 may be configured such that the arm 250 extends to the left so that a line can be drawn between center lines located to the left of the traveling cart 200, or the arm 250 can be configured to be interchangeable between the left and right sides of the traveling cart 200.

At least one of the first arm member 252 and the second arm member 254 of the arm 250 may slide in the axial direction so that the distance (offset amount) between the traveling cart 200 and the camera 300 and the marking device 400 can be changed arbitrarily. The arm 250 is not limited to the above configuration, and may have an L-shape that bends downward when viewed from the front-to-rear direction of the traveling cart 200, or a simple shape that extends in a straight line toward the side of the traveling cart 200.

As long as the target 700 can be distinguished from the surrounding background by image processing, it may be configured, for example, to have three or more light emitters, have a unique shape, or emit invisible light of a unique wavelength.

Reference Signs List 100 Road marking device 200 Traveling vehicle 250 Arm 300 Camera 400 Marking device 500 Electronic control device 600 Controller 700 Target 730 Light emitter 740 Back plate RS Road surface

Claims (10)

An autonomously movable traveling cart;
A camera mounted on the traveling carriage for capturing an image of a front of the traveling carriage;
A marking device mounted on the traveling carriage and drawing a line on a road surface;
A target placed on a road surface in front of the traveling carriage;
an electronic control device mounted on the traveling cart, configured to capture an image including the target with the camera, process the image to recognize the target, and draw a line on a road surface with the marking device while traveling the traveling cart toward the target;
A road marking device comprising: The target emits invisible light.
2. A road marking device according to claim 1. The target has two light emitters that emit the invisible light arranged vertically and spaced apart from each other.
3. A road marking device according to claim 2. A back plate is attached to the target to cover the background behind the light emitter.
4. A road marking device according to claim 3. The back plate has a surface facing the light emitter painted black.
5. A road marking device according to claim 4. The camera and the marking device are disposed at a position offset to the right or left from the center of the left-right direction of the traveling cart via an arm.
A road marking device according to any one of claims 1 to 5. The arm is capable of varying an offset amount of the camera and the marking device.
A road marking device according to claim 6. The electronic control device is configured to limit an amount of steering of the traveling carriage toward the target.
A road marking device according to any one of claims 1 to 7. Further comprising a controller having a button attached thereto;
The electronic control device is configured to draw a line on a road surface by the marking device while causing the traveling cart to travel toward the target only when a button of the controller is operated.
A road marking device according to any one of claims 1 to 8. A road marking device according to any one of claims 1 to 9 is used to draw a line on a road surface from a first point where the traveling carriage is installed to a second point where the target is placed.
Road marking methods.