JP2023154940A - asphalt finisher - Google Patents

Abstract

To provide an asphalt finisher capable of more appropriately performing automatic steering of a tractor.SOLUTION: An asphalt finisher 100 includes a tractor 1, a hopper 2 installed on the front side of the tractor 1 for receiving a pavement material, a conveyor CV for conveying the pavement material in the hopper 2 to the rear side of the tractor 1, a screw SC for spreading on the rear side of the tractor 1 the pavement material conveyed by the conveyor CV, a screed 3 for evenly leveling the pavement material spread by the screw SC on the rear side of the screw SC, an object detecting device 51 for acquiring information related to an object AP placed on the ground of a construction object, and a controller 50 which generates a guide line on the basis of change in the object AP and steers the tractor 1 on the basis of the guide line and a reference line indicating a vehicle length direction of the tractor 1.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD This disclosure relates to asphalt finishers.

Conventionally, a tractor, a hopper installed on the front side of the tractor to receive the paving material, a conveyor that feeds the paving material in the hopper to the rear side of the tractor, and a conveyor that feeds the paving material fed by the conveyor to the rear side of the tractor. An asphalt finisher is known that includes a screw that spreads the material and a screed that spreads the paving material spread by the screw on the rear side of the screw.

Furthermore, an asphalt finisher is known that automatically steers a tractor so that the end face in the width direction of the pavement to be laid extends along a driving reference line drawn on the ground to be constructed (Patent Document 1 and Patent Document 2). reference.).

The asphalt finisher disclosed in Patent Document 1 and Patent Document 2 includes a rod-shaped member attached to a hopper so as to protrude in the vehicle width direction, and a plurality of optical sensors attached to the tip of the rod-shaped member to output light toward the ground. It is equipped with. Each of the plurality of optical sensors is arranged so as to be lined up in the vehicle width direction, and is configured to be able to detect the travel reference line by receiving light reflected from the travel reference line.

With this configuration, the asphalt finisher disclosed in Patent Document 1 and Patent Document 2 can determine whether the tractor is traveling along the travel reference line, approaching the travel reference line, or moving away from the travel reference line. Can be detected. When the asphalt finisher detects that the tractor is approaching the driving reference line, it steers the tractor so that it moves away from the driving reference line, and when it detects that the tractor is moving away from the driving reference line, it steers the tractor away from the driving reference line. Steer the tractor so that it approaches the driving reference line.

Special Publication No. 3-40163 Special Publication No. 4-32883

However, the asphalt finisher disclosed in Patent Document 1 and Patent Document 2 can only steer the tractor after detecting that the tractor approaches or moves away from the travel reference line.

In view of the above, it is desired to provide an asphalt finisher that can more appropriately automatically steer a tractor.

An asphalt finisher according to an embodiment of the present invention includes: a tractor; a hopper installed on the front side of the tractor to receive paving material; a conveyor for feeding the paving material in the hopper to the rear side of the tractor; a screw for spreading the paving material fed by the tractor on the rear side of the tractor; a screed for leveling the paving material spread by the screw on the rear side of the screw; and a predetermined area of the ground to be constructed. an object detection device that acquires information regarding a feature located within the vehicle; and an object detection device that generates a guide line based on a change in the feature, and moves the tractor based on the guide line and a reference line indicating a vehicle length direction of the tractor. A control device for steering.

The above means provides an asphalt finisher that can more appropriately automatically steer a tractor.

FIG. 1 is a side view of an asphalt finisher according to an embodiment of the present invention. 2 is a top view of the asphalt finisher of FIG. 1. FIG. 1 is a diagram illustrating a configuration example of an automatic steering system. It is a schematic perspective view of the formwork for pavement. FIG. 3 is a diagram showing an example of a distance image generated based on the output of the object detection device. FIG. 3 is a diagram showing an example of a distance image generated based on the output of the object detection device. FIG. 7 is a diagram showing another example of a distance image generated based on the output of the object detection device. FIG. 2 is a top view of an automatically steered asphalt finisher. It is a top view of a paving site.

FIG. 1 is a side view of an asphalt finisher 100 according to an embodiment of the present invention. FIG. 2 is a top view of the asphalt finisher 100. In this embodiment, the asphalt finisher 100 is a wheel-type asphalt finisher, and mainly includes a tractor 1, a hopper 2, and a screed 3. In the following, the direction of the hopper 2 as seen from the tractor 1 (+X direction) is referred to as the front, and the direction of the screed 3 as seen from the tractor 1 (−X direction) as the rear.

The tractor 1 is a mechanism for moving the asphalt finisher 100. In this embodiment, the tractor 1 rotates the rear wheels 5 using the rear wheel running hydraulic motor, and rotates the front wheels 6 using the front wheel running hydraulic motor to move the asphalt finisher 100. The hydraulic motor for running the rear wheels and the hydraulic motor for running the front wheels are supplied with hydraulic oil from the hydraulic pump and rotate. However, the front wheel 6 may be a driven wheel.

Asphalt finisher 100 may be a crawler type asphalt finisher. In this case, the combination of rear wheels 5 and front wheels 6 is replaced with a combination of left crawlers and right crawlers.

Hopper 2 is a mechanism for receiving paving material. In this embodiment, the hopper 2 is installed on the front side of the tractor 1 and is configured to be opened and closed in the vehicle width direction (Y-axis direction) by a hopper cylinder. The asphalt finisher 100 normally receives paving material (for example, an asphalt mixture) from the bed of a dump truck when the hopper 2 is fully open. A dump truck is an example of a transportation vehicle that transports paving materials. 1 and 2 show that the hopper 2 is fully open. When the amount of paving material in the hopper 2 decreases, the hopper 2 is closed, and the paving material that was near the inner wall of the hopper 2 is collected in the center of the hopper 2. This is to enable the conveyor CV located in the center of the hopper 2 to feed paving material to the rear side of the tractor 1. The paving material fed to the rear side of the tractor 1 by the conveyor CV is spread in the vehicle width direction on the rear side of the tractor 1 and the front side of the screed 3 by the screw SC. In this embodiment, the screw SC is in a state in which extension screws are connected on the left and right sides. In FIGS. 1 and 2, for clarity, the illustration of the paving material in the hopper 2 is omitted, and the paving material PV spread by the screw SC is shown in a rough dot pattern, and the paving material PV spread by the screed 3 is shown in a rough dot pattern. The newly constructed pavement NP is shown in a fine dot pattern.

The screed 3 is a mechanism for leveling the paving material PV. In this embodiment, the screed 3 includes a front screed 30 and a rear screed 31. The front screed 30 includes a left front screed 30L and a right front screed 30R. The rear screed 31 is a screed that can be expanded and contracted in the vehicle width direction, and includes a left rear screed 31L and a right rear screed 31R. However, the rear screed 31 may be a fixed width screed connected to the left and right sides of the front screed 30. In the case of a fixed width screed, the left rear screed 31L and the right rear screed 31R may be attached to the same position in the front-rear direction. Furthermore, the screed 3 is a floating screed that is pulled by the tractor 1, and is connected to the tractor 1 via a leveling arm 3A. The leveling arm 3A includes a left leveling arm 3AL arranged on the left side of the tractor 1 and a right leveling arm 3AR arranged on the right side of the tractor 1. Note that an end leveling device may be disposed at the end of the rear screed 31.

A moldboard 43 is attached to the front part of the screed 3. The mold board 43 is configured to be able to adjust the amount of paving material PV that stays in front of the screed 3. The paving material PV passes through the gap between the lower end of the moldboard 43 and the roadbed BS and reaches under the screed 3.

A traveling speed sensor S1, a controller 50, an object detection device 51, an on-vehicle display device 52, and a steering device 53 are attached to the tractor 1.

The traveling speed sensor S1 is configured to be able to detect the traveling speed of the asphalt finisher 100. In this embodiment, the traveling speed sensor S1 is a wheel speed sensor, and is configured to be able to detect the rotational angular velocity and rotational angle of the rear wheels 5, as well as the traveling speed and distance of the asphalt finisher 100.

Controller 50 is a control device that controls asphalt finisher 100. In this embodiment, the controller 50 is configured with a microcomputer including a CPU, a volatile storage device, a nonvolatile storage device, and the like. Each function of the controller 50 is realized by the CPU executing a program stored in a nonvolatile storage device. However, each function of the controller 50 may be realized not only by software but also by hardware, or by a combination of hardware and software.

The object detection device 51 is configured to acquire information regarding features within a predetermined range of the ground to be constructed, and to output the acquired information to the controller 50. That is, the object detection device 51 is configured to monitor a predetermined range of the ground to be constructed. The predetermined range on the ground is a range having a longitudinal width and a lateral width larger than the width of the paving formwork, and is, for example, a range of 2 meters square.

The features within the predetermined range include, for example, the roadbed BS and the object AP located outside the roadbed BS. Specifically, the object AP is a feature used to determine the position of the end face in the width direction of the pavement to be laid. In the example shown in FIGS. 1 and 2, the object AP is a paving formwork having a predetermined thickness (height), and the left object APL is on the left side of the asphalt finisher 100, and the left object APL is on the right side of the asphalt finisher 100. right object APR. The object AP may be an L-shaped gutter block, a curb block, a cut step of an existing pavement, or the like. The cut step of the existing pavement means the step between the surface of the cut part and the surface of the uncut part, which is formed when cutting the old pavement and laying the new pavement. do. The object AP may be a feature with almost no thickness, such as a line drawn on the ground, a tape pasted on the ground, or a thread stretched along the ground. The information regarding the feature includes, for example, the height of the feature, the color of the surface of the feature, the reflectance of the surface of the feature, and the like. Note that in FIG. 1, illustration of the left object APL is omitted for clarity.

In this embodiment, the object detection device 51 is a stereo camera configured to monitor a predetermined range. Note that the object detection device 51 may be a monocular camera, LIDAR, millimeter wave radar, laser radar, laser scanner, distance image camera, laser range finder, or ultrasonic sensor configured to monitor a predetermined range. good.

Further, the stereo camera as the object detection device 51 is preferably configured to have an automatic exposure adjustment function. With this configuration, the object detection device 51 can acquire information regarding terrestrial objects within a predetermined range regardless of day or night, that is, without requiring special lighting or the like.

In this embodiment, the object detection device 51 includes a left object detection device 51L installed on the left side of the asphalt finisher 100, and a right object detection device 51R installed on the right side of the asphalt finisher 100.

The left object detection device 51L is configured to be able to monitor the ground on the left side of the asphalt finisher 100. In the present embodiment, the left object detection device 51L is a stereo camera that monitors a left monitoring range ZL (range surrounded by a dashed line in FIG. 2) on the ground on the left side of the asphalt finisher 100.

The right object detection device 51R is configured to be able to monitor the ground on the right side of the asphalt finisher 100. In this embodiment, the right object detection device 51R is a stereo camera that monitors a right monitoring range ZR (range surrounded by a dashed line in FIG. 2) on the ground on the right side of the asphalt finisher 100.

Object detection device 51 may be attached to asphalt finisher 100 via attachment member 60. The attachment member 60 is a member used to attach the object detection device 51 to the asphalt finisher 100. In this embodiment, the attachment member 60 includes a left attachment member 60L and a right attachment member 60R. In the example shown in FIG. 2, the left object detection device 51L is attached to the left front end of the tractor 1 via the left attachment member 60L, and the right object detection device 51R is attached to the right front end of the tractor 1 via the right attachment member 60R. attached to the section. Note that the left object detection device 51L may be attached to other parts of the asphalt finisher 100, such as the left front end of the hopper 2, via the left attachment member 60L. Similarly, the right object detection device 51R may be attached to other parts of the asphalt finisher 100, such as the right front end of the hopper 2, via the right attachment member 60R.

Further, the object detection device 51 may be configured to be able to monitor the expansion and contraction state of the rear screed 31. For example, the object detection device 51 additionally includes a stereo camera configured to monitor the end of the left rear screed 31L and a stereo camera configured to monitor the end of the right rear screed 31R. may be included in In this case, the object detection device 51 may be arranged on the screed 3. For example, the object detection device 51 may be arranged on the rear screed 31. Further, when an end leveling device is arranged at the end of the rear screed 31, the object detection device 51 may be arranged at the end leveling device.

Further, in the example shown in FIG. 2, the object detection device 51 is attached to the attachment member 60 so as to face vertically downward, but it may be attached to the attachment member 60 so as to face in another direction such as diagonally downward. Good too.

Further, in the example shown in FIG. 2, the left attachment member 60L is composed of an extensible member TA that can be expanded and contracted in the width direction, and a rotation member SB that is rotatably connected to the distal end of the extensible member TA. There is. The rotating member SBa indicated by a broken line in FIG. 2 shows the state when the rotating member SB is rotated. The same applies to the right attachment member 60R.

In this way, the attachment member 60 is configured so that the monitoring range of the object detection device 51 can be moved by the telescopic member TA and the rotating member SB. This is to be able to respond to changes in pavement width. Specifically, the controller 50 expands and contracts the expandable member TA so that the object detection device 51 follows the object AP. Thereby, the controller 50 can continuously position the object AP within the monitoring range of the object detection device 51 even if the placement position of the object AP changes left and right in the traveling direction.

The attachment member 60 may include at least one of a sensor that detects the amount of expansion and contraction of the expandable member TA, and a sensor that detects the amount of rotation (rotation angle) of the rotation member SB.

Note that at least one of the telescopic member TA and the rotating member SB may be omitted. For example, the attachment member 60 may be configured to be non-extendable and non-rotatable. That is, the attachment member 60 may be a rod-shaped member that is neither extendable nor rotatable.

Further, the object detection device 51 may be directly attached to the asphalt finisher 100 without using the attachment member 60.

The asphalt finisher 100 is also equipped with a steering angle sensor configured to detect the steering angle of the asphalt finisher 100, a screed expansion/contraction amount sensor configured to detect the amount of expansion/contraction of the rear screed 31, etc. It may be.

The in-vehicle display device 52 is configured to display information regarding the asphalt finisher 100. In this embodiment, the in-vehicle display device 52 is a liquid crystal display installed in front of the driver's seat 1S. However, the in-vehicle display device 52 may include a display device installed on at least one of the left end and right end of the screed 3.

The steering device 53 is configured to be able to steer the asphalt finisher 100. In this embodiment, the steering device 53 is configured to expand and contract a front wheel steering cylinder installed near the front axle. Specifically, the steering device 53 includes a steering electromagnetic control valve that controls the flow rate of hydraulic oil flowing from the hydraulic pump to the front wheel steering cylinder and the flow rate of hydraulic oil discharged from the front wheel steering cylinder. The steering electromagnetic control valve is configured to be able to control the inflow and outflow of hydraulic oil in the front wheel steering cylinders in accordance with the rotation of a steering wheel SH (steering wheel) serving as an operating device. Furthermore, the steering electromagnetic control valve is configured to be able to control the inflow and outflow of hydraulic fluid in the front wheel steering cylinders, in response to a steering command from the controller 50, regardless of the rotation of the steering wheel SH. That is, the controller 50 can automatically steer the asphalt finisher 100 regardless of whether or not the driver operates the steering wheel SH.

When the asphalt finisher 100 is a crawler-type asphalt finisher, the steering device 53 is configured to be able to separately control a pair of left and right crawlers. Note that the crawler-type asphalt finisher has a left operating lever, which is an operating device for operating the left crawler, and a right operating lever, which is an operating device for operating the right crawler, instead of the steering wheel SH.

Specifically, the steering device 53 includes a left electromagnetic control valve that controls the flow rate of hydraulic oil flowing from a hydraulic pump to a left travel hydraulic motor for rotating a left crawler, and a left electromagnetic control valve for controlling a flow rate of hydraulic oil flowing from a hydraulic pump to a left travel hydraulic motor for rotating a right crawler. It includes a right electromagnetic control valve that controls the flow rate of hydraulic oil flowing to the right travel hydraulic motor. The left electromagnetic control valve is configured to be able to control the inflow and outflow of hydraulic fluid in the left travel hydraulic motor according to the operation amount (inclination angle) of the left operation lever. Further, the left electromagnetic control valve is configured to be able to control the inflow and outflow of hydraulic fluid in the left travel hydraulic motor in response to a steering command from the controller 50, regardless of whether or not the driver operates the left operation lever. Ru. Similarly, the right electromagnetic control valve is configured to be able to control the inflow and outflow of hydraulic fluid in the right travel hydraulic motor according to the operation amount (inclination angle) of the right operation lever. Further, the right electromagnetic control valve is configured to be able to control the inflow and outflow of hydraulic fluid in the right travel hydraulic motor in response to a steering command from the controller 50, regardless of whether or not the driver operates the right operation lever. Ru.

Next, with reference to FIG. 3, a configuration example of the automatic steering system DS installed in the asphalt finisher 100 will be described. FIG. 3 is a block diagram showing a configuration example of the automatic steering system DS.

The automatic steering system DS mainly includes a controller 50, a left object detection device 51L, a right object detection device 51R, a traveling speed sensor S1, an on-vehicle display device 52, a steering device 53, and the like.

In the example shown in FIG. 3, the controller 50 includes a guide line generation section 50a, a steering control section 50b, and a screed expansion/contraction control section 50c as functional blocks.

The guide line generation unit 50a is configured to generate a guide line GD based on information regarding the terrestrial feature acquired by the object detection device 51. The guide line GD is an example of a target line and is a virtual line representing a guide surface. The guide surface is a virtual surface that is recognized as a surface on which the end surfaces in the width direction of the pavement to be laid are to be aligned. In the example shown in FIG. 2, the guide line GD is the left guide line GDL representing the left guide surface, which is the surface with which the left end surface of the new pavement NP should be made to match, and the left guide line GDL, which is the surface with which the right end surface of the new pavement NP should be made to match. It includes a right guide line GDR representing a right guide surface.

The guide line generation unit 50a generates a left guide line GDL based on the information regarding the left object APL acquired by the left object detection device 51L, and generates a right guide line GDL based on the information regarding the right object APR acquired by the right object detection device 51R. Generate GDR.

For example, as shown in FIG. 4, the guide line generation unit 50a generates a virtual line representing the edge between the left end surface LE and the upper end surface UE of the right object APR within the right monitoring range ZR as the right guide line GDR. The right guide line GDR is generated as follows. Note that FIG. 4 is a schematic perspective view of the paving formwork as the right object APR seen from the rear of the asphalt finisher 100, and schematically shows the positional relationship between the right object detection device 51R and the right object APR. ing.

For example, the guide line generation unit 50a generates the right guide line GDR using a distance image related to the right monitoring range ZR generated based on the output of a stereo camera serving as the right object detection device 51R. The distance image is a data set in which each pixel value of a two-dimensionally arranged pixel group is represented by the distance from the right object detection device 51R.

The guide line generation unit 50a extracts, from among the pixels constituting the distance image, pixels whose difference with the pixel value on the left is greater than or equal to a predetermined threshold, and derives a straight line from the arrangement of the extracted plurality of pixels. . Any image recognition technique such as Hough transform can be used to derive a straight line.

Note that the guide line generation unit 50a may perform averaging processing to eliminate the influence of portions where the positions of the extracted pixels vary. Specifically, such variations may occur in a portion of the image where two paving forms are in contact with each other, or in an image portion corresponding to an irregular portion of a cutting step.

In this example, the predetermined threshold is a threshold TH regarding the height of the paving formwork. In this case, as shown in FIG. 4, the guide line generation unit 50a generates a virtual line representing the upper left edge of the right object APR, which is a paving formwork, having a height H1 equal to or higher than the threshold TH, as the right guide line GDR. can.

Note that the threshold value TH may be configured to be able to be set in advance according to the height of the paving formwork actually used. Utilization of the threshold value TH set according to the height of the paving formwork actually used allows generation of guide lines based on the edges of the thin layer formwork. Furthermore, when using the threshold value TH set according to the height of the paving formwork actually used, the guide line generation unit 50a may erroneously This can prevent guide lines from being generated.

Note that the above description relates to the process of generating the right guide line GDR from the distance image regarding the right monitoring range ZR, but is similarly applied to the process of generating the left guide line GDL from the distance image regarding the left monitoring range ZL.

Moreover, when the object detection device 51 is a monocular camera, the "distance image" in the above description can be read as "image". In this case, the "pixel value" is expressed not by distance but by color information or the like. The color information may be luminance.

The steering control unit 50b is configured to automatically steer the asphalt finisher 100 regardless of the operation on the operating device. Note that the steering control unit 50b may be configured to be able to control the traveling speed of the asphalt finisher 100 when automatically steering the asphalt finisher 100.

The screed expansion/contraction control section 50c is configured to automatically expand/contract the left and right extensible rear screeds 31, regardless of the operation on the operating device. Note that the screed expansion/contraction control section 50c may be configured to be able to perform automatic control according to the traveling speed of the asphalt finisher 100 when automatically steering the asphalt finisher 100.

In this embodiment, the steering control unit 50b generates a steering command for the steering device 53 based on the guide line GD and the reference line BL generated by the guide line generation unit 50a. The steering command includes, for example, information regarding the steering direction and information regarding the amount of steering. The information regarding the steering direction is, for example, information regarding whether to steer to the right or to the left. The information regarding the steering amount is, for example, information regarding the steering angle, and is typically information regarding the transition or magnitude of the steering angle (target steering angle) from the start of automatic steering until the automatic steering is stopped. . The steering control unit 50b may determine the information regarding the steering angle according to the magnitude of the traveling speed of the asphalt finisher 100 detected by the traveling speed sensor S1. Further, the steering command may include, for example, information regarding steering angular velocity (rate of increase/decrease in steering angle per unit time).

The reference line BL is a virtual straight line used when generating a steering command. In this embodiment, the reference line BL is a line indicating the vehicle length direction (longitudinal direction) of the tractor 1. This means that the reference line BL is set in a direction perpendicular to the axis (axle) of the front wheel 6. In this example, the steering control unit 50b is configured to generate a steering command by comparing the guide line GD and the reference line BL.

Specifically, the steering control unit 50b recognizes the deviation between the guide line GD and the reference line BL, and generates a steering command based on the size of the recognized deviation. More specifically, as shown in FIG. 5, the steering control unit 50b calculates the distance between the reference line BL and the guide line GD in the vehicle width direction as the deviation amount DF. Further, the steering control unit 50b calculates the angle formed between the reference line BL and the guide line GD as the deviation angle θ. Then, the steering control unit 50b generates a steering command that can bring the deviation amount DF and the deviation angle θ close to zero, that is, a steering command that can make the reference line BL and the guide line GD coincide.

Note that FIG. 5 shows an example of the distance image DM generated based on the output of the stereo camera as the right object detection device 51R. FIG. 5 shows that the finer the dot pattern, the closer the distance. Specifically, FIG. 5(A) shows a distance image DMa obtained when there is a misalignment between the vehicle length direction of the asphalt finisher 100 and the extending direction of the paving formwork as the right object APR. Here is an example. FIG. 5B shows an example of a distance image DMb obtained when the vehicle length direction of the asphalt finisher 100 and the extending direction of the paving formwork as the right object APR match.

For example, when a distance image DMa as shown in FIG. 5(A) is obtained, the steering control unit 50b generates an appropriate steering command to obtain a distance image DMa as shown in FIG. 5(B). The tractor 1 is configured to automatically steer as shown in FIG.

Furthermore, when a distance image DMa as shown in FIG. generate.

In addition, in FIG. 5, a vertically extending center line represented by a broken line in the distance image DM corresponds to a reference line BL representing the vehicle length direction of the asphalt finisher 100 (tractor 1). Further, in FIG. 5, the horizontally extending center line represented by a broken line in the distance image DM corresponds to the transverse line TL representing the vehicle width direction of the asphalt finisher 100 (tractor 1). The center point CP of the distance image DM, which is the intersection of the reference line BL and the transverse line TL, corresponds to a point on the ground (surface of the roadbed BS) located directly below the center of the right object detection device 51R. .

In the example shown in FIG. 5(A), the amount of deviation DF between the reference line BL and the right guide line GDR is the difference between the point P1, which is the intersection of the transverse line TL and the right guide line GDR, and the center point CP. It is expressed as a distance and has a value DFa. Further, the deviation angle θ formed between the reference line BL and the right guide line GDR has a value θa. In FIG. 5(B), both the deviation amount DF and the deviation angle θ have a value of zero.

In this example, the deviation amount DF takes a positive value when the point P1 is located outside (on the right side) of the center point CP, and takes a negative value when the point P1 is located inside (on the left side) of the center point CP. Become. Furthermore, the deviation angle θ is a positive value when the guide line GD is inclined outward (to the right) with respect to the reference line BL, as shown in FIG. It becomes a negative value if it is tilted to .

Then, when the deviation amount DF is a positive value, the steering control unit 50b outputs a steering command to the steering device 53 so that the asphalt finisher 100 moves to the right. Similarly, when the deviation amount DF is a negative value, the steering control unit 50b outputs a steering command to the steering device 53 so that the asphalt finisher 100 moves to the left.

Further, in this example, when the deviation angle θ is a positive value, the steering control unit 50b outputs a steering command to the steering device 53 so that the asphalt finisher 100 turns to the right. Similarly, when the deviation angle θ is a negative value, the steering control unit 50b outputs a steering command to the steering device 53 so that the asphalt finisher 100 turns to the left.

Furthermore, in this example, the steering control unit 50b generates a steering command that allows the tractor 1 to turn to the right in order to bring the deviation amount DF and the deviation angle θ closer to zero. In this example, the position of the right end of the right rear screed 31R is adjusted so that the right end surface of the newly installed pavement body NP is included in a vertical plane that includes the reference line BL. Therefore, the steering control unit 50b is configured to automatically steer the tractor 1 so that the amount of deviation DF becomes zero.

Further, the screed expansion/contraction control section 50c adjusts the position of the end of the extensible rear screed 31 according to the position of the object detection device 51. Specifically, the screed expansion/contraction control unit 50c calculates the position of the object detection device 51 with respect to the tractor 1 based on the amount of expansion/contraction of the expansion/contraction member TA on which the object detection device 51 is arranged. Similarly, the screed expansion/contraction control section 50c calculates the position of the screed end with respect to the tractor 1 based on the amount of expansion/contraction of the rear screed 31. The screed expansion/contraction control unit 50c uses the calculated position of the object detection device 51, the position of the screed end, and the length in the front-rear direction between the expansion/contraction member TA and the rear screed 31 to control the object detection device 51. The position of the end of the rear screed 31 is calculated. Then, the screed expansion/contraction control unit 50c calculates the time required for the end of the rear screed 31 to reach the position detected by the object detection device 51 based on the detected traveling speed. Then, the screed expansion/contraction control unit 50c determines the attitude of the asphalt finisher 100 at the time when it reaches the position detected by the object detection device 51 based on the steering angle, calculates the position of the end of the rear screed 31, and calculates the position of the end of the rear screed 31. The screed 31 is controlled to expand and contract. In this way, the screed expansion/contraction control section 50c can cause the end of the rear screed 31 to follow the arrangement position of the object AP even if the arrangement position of the object AP changes from side to side in the traveling direction.

Next, with reference to FIG. 6, another method of generating a steering command will be described. FIG. 6 is a diagram showing another example of the distance image DM generated based on the output of the stereo camera as the right object detection device 51R, and corresponds to FIG. 5. Note that in FIG. 6, illustration of the right object APR is omitted for clarity. Furthermore, although the following description relates to a steering command generated based on the output of the right object detection device 51R, the same applies to the steering command generated based on the output of the left object detection device 51L.

In FIG. 6, the X-axis corresponds to the vehicle length direction of the asphalt finisher 100. The Y-axis corresponds to the vehicle width direction of the asphalt finisher 100. The front axle FX corresponds to an extension of the axle of the front wheel 6. That is, in the example shown in FIG. 6, the right object detection device 51R is arranged to be located on the rear side of the front axis FX in the vehicle length direction (X-axis direction). Specifically, the right object detection device 51R is arranged such that the center point CP of the distance image DM is located behind the front axis FX by a distance Lc. The deviation (deviation amount DF) is the distance between the center point CP and the guide line GD in the vehicle width direction (Y-axis direction).

In the example shown in FIG. 6, the steering control unit 50b generates a steering command (target steering angle δ) for the steering device 53 based on the guide line GD generated by the guide line generation unit 50a. Specifically, the steering control unit 50b calculates the distance Y' between the target position TP and the X-axis based on the distance X' between the target position TP and the front axis FX.

The distance X' is a value set in advance and functions as a control sensitivity parameter. However, distance X' may be dynamically set according to the traveling speed of asphalt finisher 100. In this case, distance X' is typically set to increase as the traveling speed of asphalt finisher 100 increases.

Specifically, the steering control unit 50b calculates the distance Y' based on the following equation (1). More specifically, the steering control unit 50b calculates the distance Y' based on the deviation amount DF, the distance X', the distance Lc, and the deviation angle θ.

Y'=DF+(X'+Lc)×tanθ...(1)
Then, the steering control unit 50b calculates the target steering angle δ based on the following equation (2). The target steering angle δ corresponds to the angle formed by the line segment connecting the position ND and the target position TP with respect to the X-axis. Position ND is the intersection of the X axis and the front axis FX.

Then, the steering control unit 50b executes automatic steering using the calculated target steering angle δ. Note that when the steering control unit 50b is able to generate the target steering angle δR based on the output of the right object detection device 51R and the target steering angle δL based on the output of the left object detection device 51L, Automatic steering may be executed using the average value of the target steering angle δR and the target steering angle δL as the final target steering angle δ. That is, if the steering control unit 50b is able to generate only the target steering angle δR, it may execute automatic steering using the target steering angle δR, and if it is able to generate only the target steering angle δL, Automatic steering may be performed using the target steering angle δL. Alternatively, even if it is possible to generate both the target steering angle δR and the target steering angle δL, the steering control unit 50b executes automatic steering using either the target steering angle δR or the target steering angle δL. It's okay. Further, the steering control unit 50b may stop automatic steering if the target steering angle δR and target steering angle δL cannot be generated for some reason. Further, the steering control unit 50b may restart the automatic steering if generation of at least one of the target steering angle δR and the target steering angle δL is restarted after stopping the automatic steering.

Further, the steering control unit 50b calculates an average deviation amount that is an average value of the deviation amount DF of the left guide line GDL and the deviation amount DF of the right guide line GDR, and calculates the deviation angle θ of the left guide line GDL and the deviation amount DF of the right guide line GDR. After calculating the average deviation angle that is the average value of the deviation angle θ of the guide line GDR, the average guide line may be derived based on the average deviation amount and the average deviation angle. This average guide line corresponds to the virtual center line of the construction width. The steering control unit 50b may then calculate the target steering angle δ based on this average guide line.

Next, with reference to FIGS. 7 and 8, another example of the process in which the guide line generation unit 50a generates the guide line GD will be described. FIG. 7 shows an example of a distance image DM generated based on the output of the stereo camera as the right object detection device 51R. Specifically, FIG. 7(A) shows the distance image DM0 generated at time t0, and FIG. 7(B) shows the distance image DM1 generated at time t1 after a predetermined time has elapsed from time t0. 7(C) shows the distance image DM2 generated at time t2 after a predetermined time has elapsed from time t1, and FIG. 7(D) shows the distance image DM2 generated at time t2 after a predetermined time has elapsed from time t2. A distance image DM3 generated at t3 is shown. In addition, in FIG. 7, illustration of the reference line BL and the transverse line TL, which were illustrated in FIG. 5, is omitted for clarity.

FIG. 8 is a top view of an asphalt finisher that is about to pave a road that curves to the right. Specifically, FIG. 8 shows the center line CL of the asphalt finisher 100 as a dotted line. Further, FIG. 8 shows that at the current time t0, the center line CL of the asphalt finisher 100 and the center of the width of the newly installed pavement body NP coincide.

Further, in FIG. 8, the right monitoring range ZR0 corresponding to the distance image DM0 generated at time t0 and the right monitoring range ZR3 corresponding to the distance image DM3 generated at time t3 are represented by broken lines. Note that in FIG. 8, illustration of the object detection device 51 and the attachment member 60 is omitted for clarity. Furthermore, a right monitoring range ZR1 (not shown) corresponding to the distance image DM1 generated at time t1 and a right monitoring range ZR2 (not shown) corresponding to the distance image DM2 generated at time t2 are , are actually located between the right monitoring range ZR0 and the right monitoring range ZR3, but their illustration is omitted in FIG. 8 for clarity.

Note that in the examples shown in FIGS. 7 and 8, for convenience of explanation, the asphalt finisher 100 continues to move straight until the distance image DM3 is generated, but in reality, the asphalt finisher 100 continues to move straight until the distance image DM3 is generated. It can be automatically steered every time.

At time t0, the guide line generation unit 50a generates a right guide line corresponding to the upper left edge of the paving formwork APR1, which is one of the right objects APR, based on the distance image DM0, as shown in FIG. 7(A). Generate GDR. Then, the steering control unit 50b calculates the value DF0 of the deviation amount DF between the reference line BL and the right guide line GDR, and calculates the deviation angle θ formed between the reference line BL and the right guide line GDR. Calculate the value of zero. Therefore, at time t0, the steering control unit 50b causes the tractor 1 to continue moving straight without generating a steering command that causes the tractor 1 to turn rightward or leftward.

At time t1, as shown in FIG. 7(B), the guide line generation unit 50a creates a right provisional guide corresponding to the upper left edge of the paving formwork APR1, which is one of the right objects APR, based on the distance image DM1. A line PG1 is generated, and a right provisional guide line PG2 corresponding to the upper left edge of the paving formwork APR2, which is another one of the right objects APR, is generated. The paving formwork APR2 is a paving formwork placed adjacent to the paving formwork APR1, and is arranged to be inclined with respect to the paving formwork APR1 in accordance with the road curving to the right. . That is, the right object APR shown in FIGS. 7 and 8 is installed so as to be bent at the contact point between the paving formwork APR1 and the paving formwork APR2.

The right provisional guide line PG1 is an imaginary line corresponding to the upper left edge of the part of the paving formwork APR1 that is within the right monitoring range ZR1 (not shown), and in FIG. It is represented by a chain line. Similarly, the right provisional guide line PG2 is an imaginary line corresponding to the upper left edge of the part of the paving formwork APR2 that is within the right monitoring range ZR1 (not shown), and is ) is represented by a dashed line.

When the right provisional guide line PG1 is generated, the guide line generation unit 50a calculates the midpoint BM1 of the right provisional guide line PG1. Similarly, when the right provisional guide line PG2 is generated, the guide line generation unit 50a calculates the midpoint FM1 of the right provisional guide line PG2.

Then, the guide line generation unit 50a generates a virtual line passing through the midpoint BM1 and the midpoint FM1 as the right guide line GDR1. Then, the steering control unit 50b calculates the value DF1 (>value zero) of the amount of deviation DF between the reference line BL and the right guide line GDR1, and also calculates the value DF1 (>value zero) of the deviation amount DF between the reference line BL and the right guide line GDR1. The value θ1 (>value zero) of the deviation angle θ is calculated. At this point, the steering control unit 50b can generate a steering command for aligning the right guide line GDR1 with the reference line BL based on the deviation amount DF and the deviation angle θ.

At time t2, the guide line generation unit 50a generates a right provisional guide line PG1 corresponding to the upper left edge of the paving formwork APR1 based on the distance image DM2, as shown in FIG. 7(C), and A right provisional guide line PG2 corresponding to the upper left edge of the paving formwork APR2 is generated.

The right provisional guide line PG1 is an imaginary line corresponding to the upper left edge of the part of the paving formwork APR1 that is within the right monitoring range ZR2 (not shown), and in FIG. It is represented by a chain line. Similarly, the right provisional guide line PG2 is an imaginary line corresponding to the upper left edge of the part of the paving formwork APR2 that is within the right monitoring range ZR2 (not shown), and is ) is represented by a dashed line. Note that the right provisional guide line PG1 is shorter than in FIG. 7(B), and the right provisional guide line PG2 is longer than in FIG. 7(B).

When the right provisional guide line PG1 is generated, the guide line generation unit 50a calculates the midpoint BM2 of the right provisional guide line PG1. Similarly, when the right provisional guide line PG2 is generated, the guide line generation unit 50a calculates the midpoint FM2 of the right provisional guide line PG2.

Then, the guide line generation unit 50a generates a virtual line passing through the midpoint BM2 and the midpoint FM2 as the right guide line GDR2. Then, the steering control unit 50b calculates the value DF2 (>value DF1) of the amount of deviation DF between the reference line BL and the right guide line GDR2, and also calculates the value DF2 (>value DF1) of the deviation amount DF between the reference line BL and the right guide line GDR2. The value θ2 (>value θ1) of the deviation angle θ is calculated. At this point, the steering control unit 50b can generate a steering command for aligning the right guide line GDR2 with the reference line BL based on the deviation amount DF and the deviation angle θ.

At time t3, the guide line generation unit 50a generates a right temporary guide line PG1 corresponding to the upper left edge of the paving formwork APR1 based on the distance image DM3, as shown in FIG. 7(D), and A right provisional guide line PG2 corresponding to the upper left edge of the paving formwork APR2 is generated.

The right provisional guide line PG1 is a virtual line corresponding to the upper left edge of the part of the paving formwork APR1 that is within the right monitoring range ZR3 (see Figure 8), and in Figure 7 (D) it is a virtual line that corresponds to the upper left edge of the part of the paving formwork APR1 that is within the right monitoring range ZR3 (see Figure 8). It is represented by a chain line. Similarly, the right provisional guide line PG2 is an imaginary line corresponding to the upper left edge of the part of the paving formwork APR2 that is within the right monitoring range ZR3 (see FIG. 8). ) is represented by a dashed line. Note that the right temporary guide line PG1 is shorter than in FIG. 7(C), and the right temporary guide line PG2 is longer than in FIG. 7(C).

When the right provisional guide line PG1 is generated, the guide line generation unit 50a calculates the midpoint BM3 of the right provisional guide line PG1. Similarly, when the right provisional guide line PG2 is generated, the guide line generation unit 50a calculates the midpoint FM3 of the right provisional guide line PG2.

Then, the guide line generation unit 50a generates a virtual line passing through the midpoint BM3 and the midpoint FM3 as the right guide line GDR3. Then, the steering control unit 50b calculates the value DF3 (>value DF2) of the amount of deviation DF between the reference line BL and the right guide line GDR3, and also calculates the value DF3 (>value DF2) of the deviation amount DF between the reference line BL and the right guide line GDR3. The value θ3 (>value θ2) of the deviation angle θ is calculated. At this point, the steering control unit 50b can generate a steering command for aligning the right guide line GDR3 with the reference line BL based on the deviation amount DF and the deviation angle θ.

In this way, even if the object AP is bent, the guide line generation unit 50a can generate one guide line GD passing through the midpoint of each by generating two temporary guide lines. . Note that the guide line generation unit 50a may generate three or more temporary guide lines, and generate one guide line GD based on the position of the midpoint of each of the three or more temporary guide lines.

Further, in the above example, the guide line GD is generated to be a straight line, but it may be generated as a curved line.

Furthermore, the above description with reference to FIGS. 5 to 8 relates to the processing by the steering control unit 50b when the width of the newly installed pavement NP does not change in accordance with the forward movement of the asphalt finisher 100. That is, the above description relates to processing by the steering control unit 50b when the left guide line GDL and the right guide line GDR extend substantially in parallel. When the width of the newly installed pavement NP changes as the asphalt finisher 100 moves forward, the steering control unit 50b controls the tractor 1 so that the deviation angle θ between the right guide line GDR and the reference line BL approaches zero. This is because automatic steering does not allow the deviation angle θ between the left guide line GDL and the reference line BL to approach zero.

Therefore, when the width of the newly installed pavement NP changes in accordance with the forward movement of the asphalt finisher 100, the steering control unit 50b is configured to automatically steer the tractor 1 while automatically expanding and contracting the rear screed 31. may have been done. For example, as shown in FIG. 9, when the road to be paved has a portion widened to the left (widened portion WD represented by a cross pattern), the steering control unit 50b automatically expands and contracts the rear screed 31. The tractor 1 may be automatically steered while the vehicle is moving.

FIG. 9 is a top view of the paving site. Specifically, in FIG. 9, the center line L1 of the planned paving area having a width W1 that does not include the widened part WD is shown as a dashed-dotted line, and the center line L2 of the planned paving area that has a width W2 that includes the widened part WD is shown as a two-dot chain line. It is shown in Further, FIG. 9 shows, as a thick solid line, the trajectory TR that the center point of the asphalt finisher 100 should follow in order to appropriately pave such a planned paving area. Further, FIG. 9 shows that the widened portion WD includes a first widened portion WD1 to a third widened portion WD3. The first widening section WD1 is a section where the pavement width widens, the second widening section WD2 is a section where the pavement width is maintained, and the third widening section WD3 is a section where the pavement width narrows. . Note that in FIG. 9, illustration of the object detection device 51 and the attachment member 60 is omitted for clarity.

Specifically, FIG. 9 shows the left side feature (left object APL) and right side feature (left object APL) detected by the object detection device 51 when the front end of the rear screed 31 reaches the position indicated by the block arrow AR10. The controller 50 moves the asphalt finisher 100 to the left (+Y side) in the vehicle width direction while extending the left rear screed 31L and the right rear screed 31R according to the position of the right object APR), thereby creating the first widening portion WD1. This indicates that the road will be properly paved. Further, FIG. 9 shows that when the front end of the rear screed 31 reaches the position indicated by the block arrow AR11, the controller 50 stops the extension of the rear screed 31 and then causes the asphalt finisher 100 to move straight. This shows that the second widened portion WD2 is appropriately paved. At this time, the controller 50 may detect the ends of the left rear screed 31L and the right rear screed 31R based on the detection values of the object detection device 51. Further, the asphalt finisher 100 may include an object detection device different from the object detection device 51 in order to detect the ends of the left rear screed 31L and the right rear screed 31R.

Further, FIG. 9 shows that when the front end of the rear screed 31 reaches the position indicated by the block arrow AR12, the controller 50 moves to the left according to the positions of the left feature and the right feature detected by the object detection device 51. It is shown that the third widened portion WD3 is appropriately paved by moving the asphalt finisher 100 to the right (-Y side) in the vehicle width direction while contracting the rear screed 31L and the right rear screed 31R.

Further, FIG. 9 shows that when the front end of the rear screed 31 reaches the position indicated by the block arrow AR13, the controller 50 stops the contraction of the rear screed 31 and then moves the asphalt finisher 100 straight. , indicates that the planned paving area of width W1 not including the widened portion WD will be appropriately paved.

Also in the example shown in FIG. 9, the guide line generation unit 50a generates the right guide line GDR based on the distance image generated based on the output of the right object detection device 51R, and A left guide line GDL is generated based on the distance image generated based on the output.

Thereafter, the controller 50 calculates the total width of the planned paving area based on the information regarding each of the left guide line GDL and right guide line GDR. The steering control unit 50b can determine whether the width of the planned paving area is changing based on the change in the calculated total width. Further, the controller 50 may generate a guide line GD based on the positions of the left feature and the right feature detected by the object detection device 51, and expand or contract the screed 3 based on the generated guide line GD. In this case, the controller 50 may extend or contract the rear screed 31 without performing automatic steering. Alternatively, the controller 50 may expand or contract the rear screed 31 based on the time series data of the deviation (deviation amount DF) and the predicted result of the traveling trajectory of the tractor 1. Further, the controller 50 may detect the positions of the end portions of the left rear screed 31L and the right rear screed 31R based on the detected values of the object detection device 51, and the left rear screed 31L and the right rear screed 31R based on the detected values of the screed expansion/contraction amount sensor. The positions of the ends of the rear screed 31L and the right rear screed 31R may be detected.

The controller 50 may be configured to calculate the total width of the planned paving area based on the output of a sensor that detects the amount of expansion and contraction of the expandable attachment member 60. In this case, the controller 50 may be configured to automatically expand and contract the attachment member 60 so that the center point CP of the distance image DM is located on the guide line GD, for example. Then, the controller 50 may calculate the distance between the tractor 1 and the center point of the object detection device 51 based on the output of a sensor that detects the amount of expansion and contraction of the attachment member 60. The controller 50 then stores information regarding the total width of the tractor 1 that is stored in advance, information regarding the distance between the left end of the tractor 1 and the center point of the left object detection device 51L, and information regarding the distance between the right end of the tractor 1 and the right object detection device 51L. The total width of the planned paving area may be calculated based on the information regarding the distance from the center point of 51R.

Alternatively, in the case where the object detection device 51 is directly attached to the tractor 1, the controller 50 determines whether or not the object is on the pavement based on the distance between the object detection device 51 and the object AP (terrestrial feature) detected by the object detection device 51. The total width of the planned area may be calculated. Specifically, the controller 50 uses information regarding the total width of the tractor 1 stored in advance and information regarding the distance between the left object detection device 51L and the left object APL (left side feature) detected by the left object detection device 51L. The total width of the planned paving area may be calculated based on the information and information regarding the distance between the right object detection device 51R and the right object APR (right feature) detected by the right object detection device 51R.

If it is determined that the width of the planned paving area is changing, the steering control unit 50b automatically steers the tractor 1 so that the asphalt finisher 100 is located in the center of the planned paving area. Specifically, the steering control unit 50b automatically steers the tractor 1 so that the center point of the asphalt finisher 100 follows the trajectory TR (see FIG. 9). The track TR is a line drawn by the midpoint of the width of the area to be paved.

Further, the controller 50 expands and contracts the left rear screed 31L so that the left end of the left rear screed 31L and the left end of the paving planned area coincide, and also causes the right end of the right rear screed 31R to match the right end of the paving planned area. The right rear side screed 31R may be expanded or contracted so that they match. In this case, the controller 50 controls the left rear screed 31L and the right rear screed 31R so that the amount of expansion and contraction (the amount of overhang) of the left rear screed 31L and the amount of expansion and contraction (the amount of overhang) of the right rear screed 31R are equal. It may be expanded or contracted. This is because the density of the newly installed pavement NP becomes uniform over the entire width, making it possible to ensure the flatness of the newly installed pavement NP.

Further, the controller 50 additionally takes into account at least one of the difference between the inner and outer wheels of the asphalt finisher 100 calculated from the steering angle, the distance between the object detection device 51 and the rear screed 31, and the like. It may be configured to control the amount of expansion and contraction of the screed 31. With this configuration, the controller 50 can adjust the width of the newly installed pavement NP with high precision, and can improve the quality of the end portion of the newly installed pavement NP. Moreover, with this configuration, the controller 50 can eliminate the need for adjusting the thickness of the end portion of the newly installed pavement body NP, and can reduce the number of workers involved in the paving work.

As described above, the asphalt finisher 100 according to the embodiment of the present invention includes the tractor 1, the hopper 2 installed on the front side of the tractor 1 to receive paving material, and the paving material PV in the hopper 2 transferred to the rear side of the tractor 1. a screw SC that spreads the paving material PV fed by the conveyor CV on the rear side of the tractor 1, and a screw SC that spreads the paving material PV spread by the screw SC on the rear side of the screw SC. a screed 3, an object detection device 51 that acquires information regarding features within a predetermined range of the ground to be constructed, and an object detection device 51 that generates a guide line GD as a target line based on changes in the feature, and generates a guide line GD as a target line, and A controller 50 as a control device that steers the tractor 1 based on the above-mentioned information is provided.

The controller 50 may generate a guide line GD as a target line based on changes in the terrestrial feature, and may steer the tractor 1 based on the guide line GD and a reference line BL indicating the vehicle length direction of the tractor 1. Note that the vehicle length direction of the tractor 1 is a direction perpendicular to the vehicle width direction of the tractor 1.

The predetermined range is a range having a predetermined front-back width and a predetermined left-right width around the reference point. The reference point is a point that serves as a reference when determining the content of the current steering command, and is, for example, the center point CP of the distance image DM.

The predetermined longitudinal width is set so that information regarding the pavement width in front of the vehicle in the vehicle length direction can be obtained in advance. The larger the longitudinal width (particularly the longitudinal width of the range in front of the reference point), the more the controller 50 can acquire in advance information regarding the pavement width ahead. Further, the predetermined left and right widths are also set so that information regarding the width of the pavement ahead in the vehicle length direction can be obtained in advance. The larger the lateral width (particularly the lateral width of the range in front of the reference point), the more accurately the controller 50 can acquire information regarding the pavement width ahead. This configuration enables more appropriate automatic steering that takes into account changes in the width of the pavement ahead.

The terrestrial features include, for example, a roadbed BS and an object AP located outside the roadbed BS. The object AP is, for example, a paving form, an L-shaped gutter block, a curb block, or an existing pavement. The feature may be a feature with almost no thickness, such as a line drawn on the ground, a tape pasted on the ground, or a thread stretched along the ground. The information regarding the feature is, for example, the property of the feature detected by the object detection device 51 in a non-contact manner, such as the height of the feature, the color of the surface of the feature, or the reflectance of the surface of the feature. . The change in the feature is, for example, a change in the height of the feature, a change in the color of the surface of the feature, a change in the shape of the feature, or a change in the reflectance of the surface of the feature. The shape of the feature is, for example, a continuous band shape.

For example, the controller 50 generates a distance image based on the output of the object detection device 51, and derives the position where the height of the feature changes (for example, the position where the edge of the paving formwork is located) in the distance image. guide line GD can be generated. Then, the controller 50 can automatically steer the tractor 1 so that the guide line GD and the reference line BL in the distance image match, for example.

With this configuration, the controller 50 can automatically steer the tractor 1 more appropriately. Therefore, this configuration can reduce the number of workers involved in paving work, and in turn, reduce the cost of paving work. Moreover, this configuration allows the paving work to be performed appropriately without being affected by the skill level of the worker. That is, this configuration can achieve uniform construction quality, and furthermore can aim to improve construction quality and maintain high construction quality.

For example, the controller 50 determines the distance between the guide line GD and the reference line BL in the vehicle width direction (deviation amount DF), and the angle formed between the guide line GD and the reference line BL (deviation angle θ). Based on at least one of the above, the tractor 1 may be steered so that the guide line GD and the reference line BL match.

With this configuration, the controller 50 can automatically steer the tractor 1 more appropriately. This is because the deviation amount DF represents the deviation between the pavement body and the paving formwork at the present time, and the deviation angle θ represents the deviation between the pavement body and the paving formwork at a future point in time. That is, the controller 50 can not only automatically steer the tractor 1 to eliminate the deviation at the present time, but also automatically steer the tractor 1 to eliminate the deviation at a future point in time.

Furthermore, when paving a straight road, automatically steering the tractor 1 based on the deviation amount DF and the deviation angle θ is more effective than automatically steering the tractor 1 based on the deviation amount DF only. It can improve straightness. Alternatively, even when paving a curved road, automatically steering the tractor 1 based on the deviation amount DF and the deviation angle θ is more effective than automatically steering the tractor 1 based only on the deviation amount DF. The ability of the tractor 1 to follow curves can be improved. This is because the controller 50 can execute automatic steering to prevent the occurrence of deviation before it occurs.

For example, when the feature bends, the controller 50 may be configured to generate the guide line GD based on information regarding the feature before and after the bend. Specifically, as shown in FIG. 8, for example, the controller 50 bends the right object APR as a feature at the contact point between the paving formwork APR1 and the paving formwork APR2, which are its constituent elements. In this case, as shown in FIG. 7, a guide line GD may be generated based on information regarding the paving formwork APR1 before the bend and information regarding the paving form APR2 after the bend. . With this configuration, the controller 50 can generate an appropriate guide line GD even if a feature that can be the basis of the guide line GD is bent or curved. Therefore, the controller 50 can appropriately automatically steer the tractor 1 even if the planned paving area is curved in front.

The above-mentioned change in the feature may be, for example, a change in the height of the feature. In this case, the controller 50 may generate the guide line GD based on the shape of the feature having a height equal to or greater than the threshold value TH. The threshold value TH may be set to be changeable. With this configuration, the controller 50 can prevent the guide line GD from being erroneously generated based on the shape of a feature having a height less than the threshold value TH.

The controller 50 may be configured to calculate the construction width based on a change in a feature on the right side of the tractor 1 and a change in a feature on the left side of the tractor 1. Note that the construction width is, for example, the entire width of the area to be paved. For example, the controller 50 controls the position of the part where the height of the feature on the left side of the tractor 1 changes (the boundary between the roadbed BS and the left object APL) and the height of the feature on the right side of the tractor 1. The construction width may be calculated based on the position of the portion (boundary between the roadbed BS and the right object APR). With this configuration, the controller 50 can accurately grasp the entire width of the planned paving area.

The controller 50 may be configured to steer the tractor 1 so that the center of the tractor 1 is located at the center of the construction width. With this configuration, the controller 50 can, for example, make the amount of expansion and contraction of the left rear screed 31L and the amount of expansion and contraction of the right rear screed 31R substantially the same. Therefore, the controller 50 can improve the running performance (straight-line performance) of the asphalt finisher 100.

The controller 50 may be configured to generate a target line based on changes in the terrestrial feature, and expand/contract the screed 3 based on the target line. With this configuration, the controller 50 can expand and contract the screed 3 more appropriately. Therefore, this configuration can reduce the number of workers involved in paving work, and in turn, reduce the cost of paving work. Moreover, this configuration allows the paving work to be performed appropriately without being affected by the skill level of the worker. That is, this configuration can achieve uniform construction quality, and furthermore can aim to improve construction quality and maintain high construction quality.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the embodiments described above. Various modifications or substitutions may be made to the embodiments described above without departing from the scope of the present invention. Furthermore, the features described with reference to the above-described embodiments may be combined as appropriate unless technically inconsistent.

For example, in the embodiment described above, the steering device 53 is configured to extend and retract the front wheel steering cylinder installed near the front axle, but if a hydraulic steering motor is employed instead of the front wheel steering cylinder, may be configured to rotate a hydraulic steering motor. In this case, the steering device 53 includes a steering electromagnetic control valve that controls the flow rate of hydraulic oil flowing from the hydraulic pump to the hydraulic steering motor. The steering electromagnetic control valve is configured to be able to control the inflow and outflow of hydraulic fluid in the hydraulic steering motor in accordance with the rotation of a steering wheel SH (steering wheel) serving as an operating device. Further, the steering electromagnetic control valve is configured to be able to control the inflow and outflow of hydraulic fluid in the hydraulic steering motor in response to a steering command from the controller 50, regardless of the rotation of the steering wheel SH. Alternatively, the steering device 53 may be configured to control an electric motor that automatically rotates the steering wheel SH. In this case, the steering device can automatically steer the asphalt finisher 100 by automatically rotating the steering wheel SH in response to a steering command from the controller 50.

1...Tractor 1S...Driver's seat 2...Hopper 3...Screed 3A...Leveling arm 3AL...Left leveling arm 3AR...Right leveling arm 5...Rear wheel 6...・Front wheel 30...Front screed 30L...Left front screed 30R...Right front screed 31...Rear screed 31L...Left rear screed 31R...Right rear screed 43...Mold Board 50... Controller 50a... Guide line generation section 50b... Steering control section 50c... Screed expansion/contraction control section 51... Object detection device 51L... Left object detection device 51R... Right object Detection device 52... Vehicle-mounted display device 53... Steering device 60... Attachment member 60L... Left attachment member 60R... Right attachment member 100... Asphalt finisher AP... Object APL... Left object APR... Right object APR1, APR2... Paving formwork BS... Roadbed CL... Center line CV... Conveyor DM, DMa, DMb, DM0 to DM3... Distance image DS. ...Automatic steering system GD...Guide line GDL...Left guide line GDR...Right guide line L1, L2...Center line NP...New pavement PV...Paving material S1... Traveling speed sensor SB, SBa... Rotating member SC... Screw SH... Steering wheel TA... Telescopic member TR... Track WD... Widening section WD1... First widening section WD2. ...Second widening section WD3...Third widening section ZL...Left monitoring range ZR, ZR1, ZR3...Right monitoring range

Claims (12)

tractor and
a hopper installed on the front side of the tractor to receive paving material;
a conveyor that feeds the paving material in the hopper to the rear side of the tractor;
a screw that spreads the paving material fed by the conveyor on the rear side of the tractor;
a screed for leveling the paving material spread by the screw on the rear side of the screw;
an object detection device that acquires information about features within a predetermined range of the ground to be constructed;
a control device that generates a target line based on changes in the terrestrial feature and steers the tractor based on the target line;
Asphalt finisher equipped with The control device generates the target line based on changes in the terrestrial feature, and steers the tractor based on the target line and a reference line indicating a vehicle length direction of the tractor.
The asphalt finisher according to claim 1. The control device is configured to set the distance between the target line and the reference line based on at least one of a distance between the target line and the reference line in the vehicle width direction and an angle formed between the target line and the reference line. steering the tractor so that the reference line coincides with the reference line;
The asphalt finisher according to claim 2. the reference line is set in a direction perpendicular to the axis of the front wheels of the tractor;
The asphalt finisher according to claim 2 or 3. When the feature bends, the control device generates the target line based on information regarding the feature before and after the bend.
The asphalt finisher according to any one of claims 1 to 4. The change in the feature is a change in any one of the height, color information, reflectance, or shape of the feature,
The control device generates the target line based on the shape of the feature having a height greater than or equal to a threshold;
The threshold value is set to be changeable.
The asphalt finisher according to any one of claims 1 to 5. The control device calculates a construction width based on a change in the feature on the right side of the tractor and a change in the feature on the left side of the tractor.
The asphalt finisher according to any one of claims 1 to 6. The control device steers the tractor so that the center of the tractor is located at the center of the construction width.
The asphalt finisher according to claim 7. tractor and
a hopper installed on the front side of the tractor to receive paving material;
a conveyor that feeds the paving material in the hopper to the rear side of the tractor;
a screw that spreads the paving material fed by the conveyor on the rear side of the tractor;
a screed for leveling the paving material spread by the screw on the rear side of the screw;
an object detection device that acquires information about features within a predetermined range of the ground to be constructed;
a control device that expands and contracts the screed based on changes in the feature;
Asphalt finisher equipped with The control device expands and contracts the screed based on a steering angle of the tractor calculated based on a change in the terrestrial feature and a detected traveling speed.
The asphalt finisher according to claim 9. the object detection device is arranged on the screed;
The asphalt finisher according to claim 9. an end leveling device disposed at the end of the screed;
the object detection device is disposed in the edge leveling device;
The asphalt finisher according to claim 9.

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