Asphalt paver

Abstract

An asphalt paver (100) is provided with a tractor (1), a hopper (2) provided on the front side of the tractor (1) and receiving paving material, a conveyor (CV) that conveys the paving material in the hopper (2) to the rear side of the tractor (1), a screw (SC) that spreads the paving material conveyed by the conveyor (CV) on the rear side of the tractor (1), a screed (3) that levels the paving material spread by the screw (SC) on the rear side of the screw (SC), an information acquisition device (51) that acquires information related to a road as a construction object, and a controller (50) that controls the operation of the tractor (1) based on a target track (TPT) or a target position (Pf) or (Qf) determined based on the information related to the road as the construction object acquired by the information acquisition device (51).

Description

Technical Field

[0001] This invention relates to an asphalt rolling machine. Background Technology

[0002] Previously, an asphalt screed was known, comprising: a tractor; a hopper disposed in front of the tractor and receiving paving material; a conveyor that transports the paving material in the hopper to the rear of the tractor; a screw that spreads the paving material transported by the conveyor at the rear of the tractor; and a leveling machine that levels the paving material spread by the screw at the rear of the screw (see Patent Document 1).

[0003] Typically, the operator of an asphalt trolley uses a guide bar (pointer bar) mounted on the tractor to guide the trolley along the elevation difference of the road surface being constructed, ensuring the width-direction end face of the paving material extends along the elevation difference. In other words, the operator moves the trolley while maintaining a state where the width-direction end face of the trolley is approximately parallel to the elevation difference surface. Elevation differences on the road surface can include, for example, the difference between the curb and the subgrade, the difference between the existing paving material and the subgrade, the difference between the paving formwork and the subgrade, or the difference that occurs when old paving material has been cut.

[0004] Previous technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-160636 Summary of the Invention

[0007] The technical problem to be solved by the invention

[0008] However, when the road surface is curved, the driver cannot guide the end face of the paved surface along the height difference in the width direction using only guide bars. This is because the trajectory drawn by the designated point in the center of the screed located behind the tractor does not follow the trajectory drawn by the designated point in the center of the tractor, causing it to bulge outwards from the curve.

[0009] In view of the above, it is desirable to provide an asphalt roller capable of properly laying pavement along the road of the construction object.

[0010] means for solving technical problems

[0011] The asphalt screed according to embodiments of the present invention comprises: a tractor; a hopper disposed at the front of the tractor and receiving paving material; a conveyor that conveys the paving material in the hopper to the rear of the tractor; a screw that spreads the paving material conveyed by the conveyor at the rear of the tractor; a leveling machine that levels the paving material spread by the screw at the rear of the screw; an information acquisition device that acquires road-related information of the construction object; and a control device that controls the operation of the tractor based on a target track or target position determined by the road-related information of the construction object acquired by the information acquisition device.

[0012] Invention Effects

[0013] Based on the above method, an asphalt roller is provided that can appropriately lay pavement along the road of the construction object. Attached Figure Description

[0014] Figure 1 This is a side view of the asphalt roller according to an embodiment of the present invention.

[0015] Figure 2 yes Figure 1 A top view of an asphalt roller.

[0016] Figure 3 This is a diagram illustrating an example of the structure of an automatic steering system.

[0017] Figure 4 This is an overhead view of the construction site.

[0018] Figure 5 This is an overhead view of the construction site.

[0019] Figure 6A This is an overhead view of the construction site.

[0020] Figure 6B This is an overhead view of the construction site. Detailed Implementation

[0021] Figure 1 This is a side view of the asphalt roller 100 according to an embodiment of the present invention. Figure 2 This is a top view of the asphalt roller 100. In this embodiment, the asphalt roller 100 is a wheeled asphalt roller, mainly composed of a tractor 1, a hopper 2, and a leveling machine 3. Hereinafter, the direction of the hopper 2 as viewed from the tractor 1 (+X direction) will be defined as the front, and the direction of the leveling machine 3 as viewed from the tractor 1 (-X direction) will be defined as the rear.

[0022] The traction unit 1 is a mechanism for moving the asphalt roller 100. In this embodiment, the traction unit 1 uses a rear-wheel travel hydraulic motor to rotate the rear wheel 5, and uses a front-wheel travel hydraulic motor to rotate the front wheel 6 to move the asphalt roller 100. The rear-wheel travel hydraulic motor and the front-wheel travel hydraulic motor rotate by receiving a supply of working oil from a hydraulic pump. However, the front wheel 6 can be a driven wheel.

[0023] The asphalt trolley 100 can be a tracked asphalt trolley. In this case, the combination of the rear wheel 5 and the front wheel 6 can be replaced by a combination of the left track and the right track.

[0024] The controller 50 is a control device for controlling the asphalt roller 100. In this embodiment, the controller 50 is composed of a microcomputer including a CPU, volatile memory, and non-volatile memory, and is mounted on the traction machine 1. The CPU executes the program stored in the non-volatile memory, thereby realizing the various functions of the controller 50. However, the various functions of the controller 50 can be implemented not only by software, but also by hardware, or by a combination of hardware and software.

[0025] The hopper 2 is a mechanism for receiving paving materials. In this embodiment, the hopper 2 is located in front of the tractor 1 and is configured to open and close in the vehicle width direction (Y-axis direction) via a hopper cylinder. Typically, the asphalt roller 100 receives paving materials (e.g., asphalt mixture) from the rack of a dump truck when the hopper 2 is fully open. The dump truck is an example of a transport vehicle for transporting paving materials. Figure 1 and Figure 2 This indicates that hopper 2 is in the fully open state. If the paving material in hopper 2 decreases, hopper 2 closes, and the paving material near the inner wall of hopper 2 is concentrated in the center of hopper 2. This is so that the conveyor CV in the center of hopper 2 can transport the paving material to the rear of the tractor 1. The paving material is spread and transported to the rear of the tractor 1 in the vehicle width direction via screw SC at the rear of the tractor 1 and the front of the leveler 3. In this embodiment, screw SC is in a state where extension screws are connected to the left and right sides. Figure 1 and Figure 2 The illustration of the paving material existing in the hopper 2 is omitted. The paving material PV spread by the screw SC is represented by coarse dot patterns, and the newly installed paving body NP is represented by fine dot patterns.

[0026] The leveling machine 3 is a mechanism for leveling paving material PV. In this embodiment, the leveling machine 3 includes a front leveling machine 30 and a rear leveling machine 31. The front leveling machine 30 includes a left front leveling machine 30L and a right front leveling machine 30R. The rear leveling machine 31 is a leveling machine capable of extending and retracting along the vehicle width direction, including a left rear leveling machine 31L and a right rear leveling machine 31R. However, the rear leveling machine 31 can be a fixed-width leveling machine that is connected to the front leveling machine 30 on both sides. Furthermore, the leveling machine 3 is a floating leveling machine towed by a traction machine 1 and is connected to the traction machine 1 via a leveling arm 3A. The leveling arm 3A includes a left leveling arm 3AL disposed on the left side of the traction machine 1 and a right leveling arm 3AR disposed on the right side of the traction machine 1.

[0027] A plow plate 43 is installed at the front of the screed 3. The plow plate 43 is configured to adjust the amount of paving material PV remaining in front of the screed 3. The paving material PV reaches the bottom of the screed 3 through the gap between the lower end of the plow plate 43 and the roadbed BS.

[0028] The tractor 1 is equipped with an information acquisition device 51, an on-board display device 52, and a steering device 53.

[0029] The information acquisition device 51 is configured to acquire road-related information concerning the construction object and output the acquired information to the controller 50. Road-related information includes, for example, the road width, changes in curvature in transition sections (boomerang sections), and curvature in circular arc sections. In this embodiment, the information acquisition device 51 includes a forward monitoring device 51F, a rear monitoring device 51B, a walking speed sensor 51S, a positioning device 51P, and a communication device 51T.

[0030] The forward monitoring device 51F is configured to monitor the front of the asphalt roller 100. In this embodiment, the forward monitoring device 51F is a LIDAR that monitors the monitoring range RF located in front of the tractor 1, and is installed in the center of the tractor 1. The center of the tractor 1 is, for example, the front center of the cover that covers the engine compartment located behind the hopper 2. However, the forward monitoring device 51F can be installed in other parts of the asphalt roller 100, or it can be composed of multiple LIDARs. When composed of multiple LIDARs, the forward monitoring device 51F can simultaneously monitor multiple non-overlapping monitoring ranges. In this case, the multiple LIDARs may include a right front LIDAR installed on the right side of the front of the tractor 1 and a left front LIDAR installed on the left side of the front of the tractor 1. Furthermore, the LIDAR can be mounted on the tractor 1 via a bracket or rod, etc.

[0031] The rear monitoring device 51B is configured to monitor the rear of the asphalt trolley 100. In this embodiment, the rear monitoring device 51B is a LIDAR that monitors the monitoring range RB located behind the leveler 3, and is mounted on the guide rail 1G, which functions as a handrail. However, the rear monitoring device 51B can be mounted on the lower part of the driver's seat 1S, or on other parts of the asphalt trolley 100. Furthermore, the rear monitoring device 51B can be composed of multiple LIDARs. When composed of multiple LIDARs, the rear monitoring device 51B can simultaneously monitor multiple non-overlapping monitoring ranges. In this case, the multiple LIDARs may include a right rear LIDAR mounted on the right side of the rear end of the tractor 1 and a left rear LIDAR mounted on the left side of the rear end of the tractor 1. Furthermore, the LIDARs can be mounted on the tractor 1 via brackets or poles.

[0032] The information acquisition device 51 may include a side monitoring device configured to monitor the side of the asphalt roller 100. In this case, the side monitoring device may include a left side monitoring device and a right side monitoring device. The left side monitoring device may, for example, be a LiDAR monitoring the area to the left of the tractor 1, mounted on the left end of the upper surface of the tractor 1, further forward of the rear wheel 5. The right side monitoring device may, for example, be a LiDAR monitoring the area to the right of the tractor 1, mounted on the right end of the upper surface of the tractor 1, further forward of the rear wheel 5.

[0033] For example, a LiDAR may be configured to determine the distance between itself and multiple points within its monitoring range. However, at least one of the front monitoring device 51F and the rear monitoring device 51B may be a monocular camera, a stereo camera, a millimeter-wave radar, a lidar, a laser scanner, a depth camera, or a laser rangefinder, etc. The same applies to the side monitoring device.

[0034] The monitoring range RF of the forward monitoring device 51F preferably includes the roadbed BS and the above-ground structures AP located outside the roadbed BS. This is to obtain information related to the width of the road to be constructed. The same applies to the monitoring range of the lateral monitoring device. In this embodiment, the monitoring range RF has a width greater than the width of the roadbed BS. The above-ground structures AP are L-shaped side blocks. The above-ground structures AP can be paving frames, curb stones, or existing paving structures, etc.

[0035] The monitoring range RB of the rear monitoring device 51B preferably includes the newly installed pavement NP and the ground features AP located outside the newly installed pavement NP. This is to obtain information related to the width of the newly installed pavement NP. In this embodiment, the monitoring range RB has a width greater than the width of the newly installed pavement NP.

[0036] The travel speed sensor 51S is configured to detect the travel speed of the asphalt roller 100. In this embodiment, the travel speed sensor 51S is a wheel speed sensor and is configured to detect the rotational angular velocity and rotational angle of the rear wheel 5, as well as the travel speed and travel distance of the asphalt roller 100.

[0037] The positioning device 51P is configured to measure the position of the asphalt roller 100. In this embodiment, the positioning device 51P is a GNSS compass, and is configured to measure the position and orientation of the asphalt roller 100. Figure 1 and Figure 2 As shown, the GNSS compass, which serves as the positioning device 51P, includes a left GNSS receiver 51PL mounted on the upper end of a rod PL extending vertically upward from the rear end of the left leveling arm 3AL, and a right GNSS receiver 51PR mounted on the upper end of a rod PL (not visible) extending vertically upward from the rear end of the right leveling arm 3AR.

[0038] However, the positioning device 51P can be a total station. In this case, a reflecting prism that serves as the target of the total station is installed at the front end of the pole PL. The main body of the total station, positioned around the asphalt tumbler 100, is connected to the controller 50 via wireless communication. That is, the main body of the total station sends information related to the position of the derived target to the controller 50.

[0039] The communication device 51T is configured to control communication between the asphalt roller 100 and equipment located outside the asphalt roller 100. In this embodiment, the communication device 51T is located in front of the driver's seat 1S and is configured to control communication via mobile communication networks, short-range wireless communication networks, or satellite communication networks.

[0040] The information acquisition device 51 may include a steering angle sensor configured to detect the steering angle of the asphalt roller 100 and a paving width sensor configured to detect the extension and retraction of the rear screed 31 and calculate the paving width, etc.

[0041] Furthermore, the information acquisition device 51 may include a monitoring device installed at the construction site or a monitoring device mounted on an aircraft flying above the asphalt roller 100. The monitoring device installed at the construction site may be, for example, a LiDAR or monocular camera mounted on the front end of a pole installed along the road surface of the construction object. The monitoring device mounted on the aircraft may be, for example, a LiDAR or monocular camera mounted on a multi-rotor aircraft (drone) or airship.

[0042] The vehicle-mounted display device 52 is configured to display information related to the asphalt tumbler 100. In this embodiment, the vehicle-mounted display device 52 is a liquid crystal display located in front of the driver's seat 1S. However, the vehicle-mounted display device 52 may be located at at least one end of the tumbler 3, either the left or right end.

[0043] The steering device 53 is configured to control the steering of the asphalt trolley 100. In this embodiment, the steering device 53 is configured to extend and retract the front wheel steering cylinder located near the front axle. Specifically, the steering device 53 includes a steering solenoid control valve that controls the flow rate of working oil from the hydraulic pump to the front wheel steering cylinder and the flow rate of working oil discharged from the front wheel steering cylinder. The steering solenoid control valve is configured to control the flow of working oil in the front wheel steering cylinder according to the rotation of the steering wheel SH, which is an operating device. Furthermore, the steering solenoid control valve is configured to control the flow of working oil in the front wheel steering cylinder independently of the rotation of the steering wheel SH, based on control commands from the controller 50. That is, the controller 50 can control the steering of the asphalt trolley 100 regardless of whether the driver operates the steering wheel SH.

[0044] When the asphalt trolley 100 is a tracked asphalt trolley, the steering device 53 is configured to independently control the left and right pairs of tracks. Specifically, the steering device 53 includes a left solenoid control valve that controls the flow of working oil from the hydraulic pump to the left travel hydraulic motor for rotating the left track, and a right solenoid control valve that controls the flow of working oil from the hydraulic pump to the right travel hydraulic motor for rotating the right track. Furthermore, the left solenoid control valve is configured to control the flow of working oil in the left travel hydraulic motor based on the amount of operation (tilt angle) of the operating device for operating the left track, i.e., the left operating lever. Also, the left solenoid control valve is configured to control the flow of working oil in the left travel hydraulic motor independently of whether the driver operates the left operating lever, based on control commands from the controller 50. Similarly, the right solenoid control valve is configured to control the flow of working oil in the right travel hydraulic motor based on the amount of operation (tilt angle) of the operating device for operating the right track, i.e., the right operating lever. Furthermore, the right solenoid control valve is configured to control the flow of working oil in the right travel hydraulic motor regardless of whether the driver operates the right control lever, based on control commands from the controller 50.

[0045] Next, refer to Figure 3 An example of the structure of the automatic steering system DS mounted on the asphalt roller 100 will be described. Figure 3 This is a block diagram illustrating the structure of an automatic steering system (DS).

[0046] The automatic steering system DS mainly consists of a controller 50, a forward monitoring device 51F, a rear monitoring device 51B, a travel speed sensor 51S, a positioning device 51P, a communication device 51T, an on-board display device 52, and a steering device 53.

[0047] exist Figure 3 In the example shown, the controller 50, as a functional module, includes a target calculation unit 50a, a steering control unit 50b, and a display control unit 50c.

[0048] The target calculation unit 50a is configured to calculate the target used by the steering control unit 50b. The target used by the steering control unit 50b is, for example, a target track that needs to be drawn as a predetermined point on the asphalt roller 100. The predetermined point is a point that is pre-associated with a predetermined location on the asphalt roller 100, also referred to as a steering reference point or control reference point. However, the predetermined point can be a point that is dynamically associated with a predetermined location on the asphalt roller 100. Strictly speaking, the target track is a one-dimensional arrangement of multiple target positions. The target position is the location that the predetermined point on the asphalt roller 100 needs to reach. Alternatively, the target used by the steering control unit 50b can be a target position that the predetermined point on the asphalt roller 100 needs to reach after a predetermined time has elapsed. The predetermined time is, for example, a few milliseconds, tens of milliseconds, hundreds of milliseconds, or a few seconds.

[0049] In this embodiment, the target calculation unit 50a calculates the target track that a predetermined point in the center of the tractor 1 must follow, for example, based on road-related information such as construction design data. Typically, the target track is calculated before the asphalt roller 100 begins to move. Therefore, the target track can be calculated by a server or similar device located in a management center outside the asphalt roller 100 and then transmitted to the controller 50 via communication. Furthermore, the predetermined point may be a point located at the center of the front end of the hopper 2, rather than a point located at the center of the tractor 1. In the case of a wheeled asphalt roller, the predetermined point may be a point located at the position of the left front wheel, a point located at the position of the right front wheel, or a point located at the center of the front axle.

[0050] The target calculation unit 50a can calculate the target position, which is the location that a predetermined point in the center of the tractor 1 needs to reach after a predetermined time. At this time, the target position is repeatedly calculated at predetermined control cycles during the movement of the asphalt roller 100. For example, the target calculation unit 50a can calculate the center point in the width direction of the road of the construction object, located at a predetermined distance further forward than the current position of the predetermined point in the center of the tractor 1, based on information obtained from the forward monitoring device 51F. The predetermined distance is, for example, a few centimeters or tens of centimeters. In this case, the target calculation unit 50a can calculate the target position without obtaining construction design data. However, the target calculation unit 50a can calculate the target position based on construction design data and information obtained from the forward monitoring device 51F. For example, the target calculation unit 50a can correct the target position calculated based on the construction design data based on information obtained from the forward monitoring device 51F. Furthermore, the target calculation unit 50a can utilize information obtained from the rear monitoring device 51B.

[0051] The steering control unit 50b is configured to automatically control the steering of the asphalt tumbler 100 without operating the control device.

[0052] In this embodiment, the steering control unit 50b outputs control commands to the steering device 53 in a manner that causes a predetermined point in the center of the tractor 1 to follow the target trajectory calculated by the target calculation unit 50a. Specifically, the steering control unit 50b calculates the current position of the predetermined point in the center of the tractor 1 based on the output of the positioning device 51P. Furthermore, when it is determined that the predetermined point has deviated from the target trajectory to the right, the steering control unit 50b outputs control commands to the steering device 53 in a manner that causes the asphalt roller 100 to move to the left. Similarly, when it is determined that the predetermined point has deviated from the target trajectory to the left, the steering control unit 50b outputs control commands to the steering device 53 in a manner that causes the asphalt roller 100 to move to the right.

[0053] Alternatively, the steering control unit 50b can output control commands to the steering device 53 in a manner that positions a predetermined point in the center of the tractor 1 relative to the target position calculated by the target calculation unit 50a. In this case, the steering control unit 50b can derive the current position of the predetermined point in the center of the tractor 1 based on the output of the positioning device 51P, or it can derive the current position of the predetermined point in the center of the tractor 1 based on the output of at least one of the rear monitoring device 51B and the front monitoring device 51F. In the latter case, the positioning device 51P can be omitted.

[0054] Next, refer to Figure 4 The function of moving the asphalt roller 100 along the target track is explained. Figure 4This is a top view showing the construction site of an asphalt roller 100 passing through the curve (left curve) of road RD, which is the object of construction. Figure 4 In this diagram, asphalt roller 100a represents asphalt roller 100 at the start of construction, i.e., at point 1. Asphalt roller 100b represents asphalt roller 100 at point 2, after a specified time elapsed from point 1. Similarly, asphalt roller 100c represents asphalt roller 100 at point 3, after a specified time elapsed from point 2; asphalt roller 100d represents asphalt roller 100 at point 4, after a specified time elapsed from point 3; and asphalt roller 100e represents asphalt roller 100 at point 5, after a specified time elapsed from point 4. Furthermore, for clarity, Figure 4 The diagram simplifies the asphalt roller 100, showing the tractor 1, the front leveler 30, the left rear leveler 31L, and the right rear leveler 31R. The hopper 2 is omitted from the diagram.

[0055] At the start of construction, i.e., at the first point in time, the target calculation unit 50a of the controller 50 calculates the target track TPT that the designated point P in the central part of the traction machine 1 needs to follow. Figure 4 In the example shown, the designated point P is represented by "○", and the target track TPT is represented by a dashed line. The target calculation unit 50a, referring to the construction design data, derives the centerline CP of the road RD based on the left boundary line LP and right boundary line RP of the road RD. Then, the target calculation unit 50a sets the centerline CP as the target track TPS that the designated point Q in the center of the front leveling machine 30 needs to follow. Figure 4 In the example shown, the designated point Q is represented by "△", and the target track TPS is represented by a dashed line. Then, the target calculation unit 50a calculates the target track TPT that the designated point P needs to follow based on known information such as the distance between the rear wheel 5 and the front wheel 6 of the asphalt roller 100 and the target track TPS.

[0056] exist Figure 4 In the example shown, the left boundary line LP, right boundary line RP, center line CP, target track TPT to be followed by designated point P, and target track TPS to be followed by designated point Q are all derived as a one-dimensional arrangement of multiple position coordinates. These position coordinates are, for example, coordinates in a reference coordinate system.

[0057] A reference coordinate system is, for example, the World Geodetic System. The World Geodetic System is a three-dimensional orthogonal XYZ coordinate system with the origin placed at the Earth's center of gravity, the axis passing through the intersection of the Greenwich Meridian and the equator and the origin as the X-axis, the axis passing through the intersection of the meridian at 90 degrees east longitude and the equator and the origin as the Y-axis, and the axis passing through the North Pole and the origin as the Z-axis.

[0058] Then, the steering control unit 50b of the controller 50 operates the asphalt tumbler 100 in a manner that makes the actual position coordinates of the specified point P consistent with one of the position coordinates constituting the target track TPT. Specifically, the steering control unit 50b derives the current position of the specified point P in the center of the traction machine 1 based on the output of the positioning device 51P. Then, when the position of the specified point P is located to the right of the target track TPT, the steering control unit 50b outputs a control command to the steering solenoid control valve constituting the steering device 53, causing a specified amount of working oil to flow into the cylinder bottom oil chamber of the front wheel steering cylinder. As a result, the asphalt tumbler 100 moves forward and to the left, and the position of the specified point P approaches the target track TPT. Conversely, when the position of the specified point P is located to the left of the target track TPT, the steering control unit 50b outputs a control command to the steering solenoid control valve constituting the steering device 53, causing a specified amount of working oil to flow into the rod side oil chamber of the front wheel steering cylinder. As a result, the asphalt roller 100 moves forward while simultaneously moving to the right, and the position of the designated point P approaches the target track TPT. Furthermore, in this example, the front wheel steering cylinder is configured such that the left steering angle increases as it extends beyond a designated length, and the right steering angle increases as it retracts below a designated length.

[0059] Thus, the controller 50 can position a predetermined point P, which is located at point Pa at the first time point, at point Pb at the second time point, at point Pc at the third time point, at point Pd at the fourth time point, and at point Pe at the fifth time point. Consequently, the controller 50 can position a predetermined point Q, which is located at point Qa at the first time point, at point Qb at the second time point, at point Qc at the third time point, at point Qd at the fourth time point, and at point Qe at the fifth time point.

[0060] exist Figure 4 In the example shown, the left rear screed 31L extends to the left so that its left end face aligns with the left boundary line LP of the road RD, and the right rear screed 31R extends to the right so that its right end face aligns with the right boundary line RP of the road RD. Then, the left end face of the left rear screed 31L moves to follow the left boundary line LP, and the right end face of the right rear screed 31R moves to follow the right boundary line RP. Therefore, by causing the tractor 1 to move forward so that the predetermined point P in the center of the tractor 1 follows the target track TPT, the controller 50 can make the width of the road RD match the width of the newly laid pavement NP.

[0061] The controller 50 can extend or retract the rear screed 31 during the movement of the asphalt tumbler 100. For example, when the left end face of the left rear screed 31L may detach from the left boundary line LP towards the inside of the road RD, the controller 50 can extend the left rear screed 31L to the left. Or, when the right end face of the right rear screed 31R may detach from the right boundary line RP towards the inside of the road RD, the controller 50 can extend the right rear screed 31R to the right.

[0062] Furthermore, in Figure 4 In the example shown, the steering control unit 50b controls the steering of the asphalt roller 100 when the asphalt roller 100 is traveling in the curve of the road RD, but it can also control the steering of the asphalt roller 100 when the asphalt roller 100 is traveling in the straight section of the road RD.

[0063] Next, refer to Figure 5 The function of moving the asphalt roller 100 while determining the target position in real time is explained. Figure 5 This is a top view showing the construction site of an asphalt roller 100 passing through the bend of road RD, which is the object of construction. For clarity, [the image is] shown alongside... Figure 4 Similarly, Figure 5 The diagram simplifies the asphalt roller 100, showing the tractor 1, the front leveler 30, the left rear leveler 31L, and the right rear leveler 31R. The hopper 2 is omitted from the diagram.

[0064] exist Figure 5 In the example shown, the target calculation unit 50a of the controller 50 derives the centerline CP of the road RD of the construction object based on the information obtained by the forward monitoring device 51F. Figure 5 In the example shown, the centerline CP is represented by a dotted line. Specifically, the target calculation unit 50a derives the left boundary line LP and right boundary line RP of the road RD based on the information obtained from the forward monitoring device 51F, and then derives the centerline CP of the road RD based on the left boundary line LP and right boundary line RP. The information obtained by the forward monitoring device 51F includes, for example, the position and orientation of the elevation difference between the curb and the roadbed BS. Furthermore, the target calculation unit 50a derives the current position Pn of a predetermined point P in the center of the tractor 1 and the current position Qn of a predetermined point Q in the center of the front leveler 30. Specifically, the target calculation unit 50a derives the current position Pn of the predetermined point P and the current position Qn of the predetermined point Q based on the output of the positioning device 51P. Figure 5 In the example shown, point P is represented by “○” and point Q is represented by “△”.

[0065] Then, the target calculation unit 50a calculates the target position Pf, which is the location that the specified point P needs to reach after a specified time. Specifically, the target calculation unit 50a calculates the target position Qf, which is the location that the specified point Q needs to reach after a specified time, based on the construction design data and the current position Pn of the specified point P. Based on known information such as the distance between the rear wheel 5 and the front wheel 6 of the asphalt roller 100, and the target position Qf, the target position Pf is calculated. Both the target position Pf and the target position Qf are derived as position coordinates. These position coordinates are, for example, coordinates in a reference coordinate system. Figure 5 In the example shown, the target position Pf is represented by a dotted line “○”, and the target position Qf is represented by a dotted line “△”.

[0066] Then, the steering control unit 50b of the controller 50 operates the asphalt tumbler 100 in a manner that makes the position coordinates of the specified point P consistent with the position coordinates of the target position Pf. For example, the steering control unit 50b derives the center axis AX of the asphalt tumbler 100 based on the output of the positioning device 51P. Then, when the target position Pf is located to the left of the center axis AX, the steering control unit 50b outputs a control command to the steering solenoid control valve constituting the steering device 53, causing a specified amount of working oil to flow into the bottom oil chamber of the front wheel steering cylinder. As a result, the asphalt tumbler 100 moves forward and to the left, and the position of the specified point P approaches the target position Pf. Conversely, when the target position Pf is located to the right of the center axis AX, the steering control unit 50b outputs a control command to the steering solenoid control valve constituting the steering device 53, causing a specified amount of working oil to flow into the rod-side oil chamber of the front wheel steering cylinder. As a result, the asphalt tumbler 100 moves forward and to the right, and the position of the specified point P approaches the target position Pf. In addition, in this example, the front wheel steering cylinder is configured such that the left steering angle increases as it extends beyond a specified length, and the right steering angle increases as it retracts below a specified length.

[0067] Thus, controller 50 can position the specified point P at the target position Pf. Consequently, controller 50 can position the specified point Q at the target position Qf.

[0068] The steering control unit 50b can operate the asphalt roller 100 in a manner that makes the position coordinates of the specified point Q consistent with the position coordinates of the target position Qf. Alternatively, the steering control unit 50b can operate the asphalt roller 100 in a manner that makes the specified point Q approach the centerline CP of the road RD. In this case, the steering control unit 50b determines, according to a predetermined control cycle, whether the specified point Q is located on the centerline CP of the road RD, to the right of the centerline CP, or to the left of the centerline CP. Then, when it is determined to be on the right, the steering control unit 50b moves the asphalt roller 100 to the left, and when it is determined to be on the left, it moves the asphalt roller 100 to the right.

[0069] exist Figure 5 In the example shown, the left rear screed 31L extends to the left so that its left end face aligns with the left boundary line LP of the road RD, and the right rear screed 31R extends to the right so that its right end face aligns with the right boundary line RP of the road RD. Then, the left end face of the left rear screed 31L moves in accordance with the left boundary line LP, and the right end face of the right rear screed 31R moves in accordance with the right boundary line RP. Therefore, by causing the tractor 1 to advance in a manner that causes a predetermined point P in the center of the tractor 1 to follow the target position Pf calculated according to a predetermined control cycle, the controller 50 can make the width of the road RD match the width of the newly laid pavement NP.

[0070] The controller 50 can extend or retract the rear screed 31 during the movement of the asphalt tumbler 100. For example, when the left end face of the left rear screed 31L may detach from the left boundary line LP towards the inside of the road RD, the controller 50 can extend the left rear screed 31L to the left. Or, when the right end face of the right rear screed 31R may detach from the right boundary line RP towards the inside of the road RD, the controller 50 can extend the right rear screed 31R to the right.

[0071] Furthermore, in Figure 5 In the example shown, the steering control unit 50b controls the steering of the asphalt roller 100 when the asphalt roller 100 is traveling in the curve of the road RD, but it can also control the steering of the asphalt roller 100 when the asphalt roller 100 is traveling in the straight section of the road RD.

[0072] Next, refer to Figure 6A and Figure 6B The effect of automatically controlling the asphalt roller 100 through the steering device 53 is explained. Figure 6A and Figure 6B This is a top view showing the construction site of an asphalt roller 100 passing through the bend of road RD, which is the object of construction. Specifically, Figure 6AThis indicates the operation of the asphalt roller 100 when the steering device 53 performs automatic steering. Figure 6B This refers to the operation of the asphalt trolley 100 when manually steered so that a predetermined point P in the center of the tractor 1 follows the centerline CP of the road RD. Figure 6A and Figure 6B In the example shown, the designated point P in the center of the tractor 1 is represented by “○”, and the designated point Q in the center of the front leveler 30 is represented by “△”.

[0073] like Figure 6B As shown, if the machine is manually steered so that a specified point P follows the centerline CP of the road RD, then a specified point Q in the center of the front screed 30 follows the trajectory PS represented by a double-dotted line. That is, when the asphalt roller 100 passes through the bend of the road RD, the distance between the front end of the right side of the tractor 1 and the right boundary line RP of the road RD changes to be approximately equal to the distance between the front end of the left side of the tractor 1 and the left boundary line LP of the road RD. However, the distance between the front end of the right side of the front screed 30 and the right boundary line RP of the road RD changes to be less than the distance between the front end of the left side of the front screed 30 and the left boundary line LP of the road RD. Therefore, the paving material is not laid in the inner region of the bend of the road RD represented by the dotted pattern; instead, it extends beyond the right boundary line RP of the road RD and is laid in the outer region of the bend of the road RD represented by the cross pattern.

[0074] Thus, when the asphalt roller 100 passes through the bend of the road RD, even if the driver of the asphalt roller 100 moves the asphalt roller 100 in such a way that the tractor 1 is located in the center of the width direction of the road RD, the leveler 3 cannot be positioned in the center of the width direction of the road RD.

[0075] In contrast, such as Figure 4 and Figure 6AAs shown, if the asphalt roller 100 is automatically controlled by the steering device 53 to make the specified point P follow the target track TPT, then the specified point Q in the central part of the front leveler 30 follows the center line CP of the road RD, which is indicated by the dashed line. That is, when the asphalt roller 100 passes through the bend of the road RD, the distance between the front end of the right side of the tractor 1 and the right boundary line RP of the road RD changes to be less than the distance between the front end of the left side of the tractor 1 and the left boundary line LP of the road RD, but the distance between the front end of the right side of the front leveler 30 and the right boundary line RP of the road RD changes to be approximately equal to the distance between the front end of the left side of the front leveler 30 and the left boundary line LP of the road RD. Therefore, the paving material is reliably laid in the inner area of ​​the bend of the road RD, and the paving material will not extend beyond the right boundary line RP of the road RD. That is, the asphalt roller 100 can make the width of the road RD and the width of the newly laid pavement NP consistent even in the curved part of the road RD.

[0076] Thus, when the asphalt roller 100 passes through the bend of the road RD, the controller 50 moves the asphalt roller 100 in such a way that the tractor 1 approaches the end of the road RD in the width direction, thereby enabling the leveler 3 to be positioned at the center of the road RD in the width direction.

[0077] As described above, the asphalt roller 100 according to the embodiments of the present invention includes a traction machine 1, a hopper 2 provided at the front of the traction machine 1 and receiving paving material, a conveyor CV that conveys the paving material in the hopper 2 to the rear of the traction machine 1, a screw SC that spreads the paving material conveyed by the conveyor CV at the rear of the traction machine 1, a leveling machine 3 that levels the paving material spread by the screw SC at the rear of the screw SC, an information acquisition device 51 that acquires information related to the road of the construction object, and a controller 50 that controls the operation of the traction machine 1 based on the target track TPT or target position Pf or Qf determined by the information acquisition device 51 related to the road of the construction object.

[0078] According to this structure, the asphalt roller 100 can properly lay the pavement along the road RD of the construction object.

[0079] like Figure 4 or Figure 5As shown, when the road RD of the construction object bends to the left, the controller 50 can be configured to set the target track TPT or target position Pf in the curved section of the road RD of the construction object at a position further out (to the right) than the center (centerline CP) of the road RD of the construction object. Furthermore, the target track TPT is, for example, the target track that a predetermined point P in the center of the traction machine 1 needs to follow, and the target position Pf is the location that the predetermined point P needs to reach after a predetermined time.

[0080] The controller 50 can be configured to set the target track TPT or target position Pf in a manner that aligns the width-direction center of the road RD of the construction object with the width-direction center of the leveling machine 3. For example, as Figure 4 As shown, the target calculation unit 50a of the controller 50 can be configured to set the target track TPT or target position Pf in such a way that the trajectory drawn by the predetermined point Q in the center of the front leveling machine 30 is consistent with the center line CP of the road RD.

[0081] According to this structure, even when the asphalt roller 100 passes through both the straight and curved sections of the road RD, the controller 50 can make the width of the road RD consistent with the width of the newly laid pavement NP.

[0082] The controller 50 can be configured to set the target track TPT or target position Pf in such a way that at least one end of the leveling machine 3 is aligned with the ground surface. For example, as Figure 4 As shown, the target calculation unit 50a of the controller 50 can set the target track TPT or target position Pf such that the left end of the leveling machine 3 is aligned with the left boundary line LP of the road RD and the right end of the leveling machine 3 is aligned with the right boundary line RP of the road RD. Alternatively, the target calculation unit 50a of the controller 50 can set the target track TPT or target position Pf such that the left end of the leveling machine 3 is aligned with the left boundary line LP of the road RD. Alternatively, the target calculation unit 50a of the controller 50 can set the target track TPT or target position Pf such that the right end of the leveling machine 3 is aligned with the right boundary line RP of the road RD.

[0083] Furthermore, the controller 50 can be configured to set the target track TPT or target position Pf based on the distance in the longitudinal direction between a predetermined point P, which serves as a steering reference point, and the leveler 3. For example, the controller 50 can be configured to set the target track TPT or target position Pf based on the distance in the longitudinal direction between the predetermined point P and a predetermined point Q in the center of the front leveler 30.

[0084] Furthermore, the controller 50 can be configured to set a target trajectory TPS or a target position Qf based on the longitudinal distance between a predetermined point P (serving as a steering reference point) and the leveling machine 3. For example, the controller 50 can be configured to set the target trajectory TPS or the target position Qf based on the longitudinal distance between the predetermined point P and a predetermined point Q in the center of the front leveling machine 30. Additionally, the target trajectory TPS is, for example, the target trajectory that the predetermined point Q in the center of the front leveling machine 30 needs to follow, and the target position Qf is the location that the predetermined point Q needs to reach after a predetermined time.

[0085] The controller 50 can be configured such that, in the case of a wheeled asphalt trolley, the action of the tractor 1 is controlled by controlling the steering angle of the front wheel 6, and in the case of a tracked asphalt trolley, the action of the tractor 1 is controlled by individually controlling the rotation speed of the left track and the right track.

[0086] According to this structure, even if the asphalt roller 100 is either a wheeled asphalt roller or a tracked asphalt roller, the controller 50 can automatically control the movement of the asphalt roller 100 to properly lay the pavement along the road RD of the construction object.

[0087] The controller 50 can be configured to control the movement of the traction machine 1 such that the asphalt roller 100 moves along a pre-set target track TPT. Specifically, the controller 50 can be configured to control the movement of the traction machine 1 such that the asphalt roller 100 moves along a target track TPT set before the asphalt roller 100 begins to move. However, the controller 50 can also be configured to control the movement of the traction machine 1 such that the asphalt roller 100 moves along a target track TPT calculated in real time.

[0088] According to this structure, the controller 50 can control the movement of the traction machine 1 simply, reliably and appropriately.

[0089] The information acquisition device 51 can be a camera device or a communication device 51T. Moreover, the camera device can be a LiDAR, a monocular camera, a stereo camera, or a depth camera, etc.

[0090] The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Various modifications or substitutions can be applied to the above embodiments without departing from the scope of the present invention. Furthermore, the features described with reference to the above embodiments can be appropriately combined as long as they are not technically contradictory.

[0091] For example, in the above embodiment, the steering device 53 is configured to extend and retract the front wheel steering cylinder located near the front axle. However, when a hydraulic steering motor is used instead of the front wheel steering cylinder, it can be configured to rotate the hydraulic steering motor. In this case, the steering device 53 includes a steering solenoid control valve that controls the flow rate of working oil from the hydraulic pump to the hydraulic steering motor. The steering solenoid control valve is configured to control the flow of working oil in the hydraulic steering motor according to the rotation of the steering wheel SH, which is an operating device. Furthermore, the steering solenoid control valve is configured to control the flow of working oil in the hydraulic steering motor independently of the rotation of the steering wheel SH, according to a control command from the controller 50. Alternatively, the steering device 53 can be configured to control an electric motor that automatically rotates the steering wheel SH. In this case, the steering device automatically controls the steering wheel SH according to the control command from the controller 50, thereby automatically controlling the operation of the asphalt tumbler 100.

[0092] This application claims priority based on Japanese Patent Application No. 2020-056662, filed on March 26, 2020, the entire contents of which are incorporated herein by reference.

[0093] Symbol Explanation

[0094] 1-Tractor, 1G-Guide rail, 1S-Driver's seat, 2-Hopper, 3-Leveler, 3A-Leveling boom, 3AL-Left leveling boom, 3AR-Right leveling boom, 5-Rear wheel, 6-Front wheel, 30-Front leveler, 31-Rear leveler, 43-Plow, 50-Controller, 50a-Target calculation unit, 50b-Steering control unit, 51-Information acquisition device, 51B-Rear monitoring device, 51F-Front monitoring device, 5 1P - Positioning device, 51PL - Left GNSS receiver, 51PR - Right GNSS receiver, 51S - Travel speed sensor, 51T - Communication device, 52 - Vehicle display device, 53 - Steering device, 100 - Asphalt roller, AP - Ground structure, BS - Roadbed, CV - Conveyor, DS - Automatic steering system, NP - New paving body, PL - Rod, PV - Paving material, SC - Screw, SH - Steering wheel.

Claims

1. An asphalt paver comprising: a tractor; a hopper provided on a front side of the tractor and receiving paving material; a conveyor that conveys the paving material in the hopper to a rear side of the tractor; a screw that spreads the paving material conveyed by the conveyor on the rear side of the tractor; a screed that levels the paving material spread by the screw on a rear side of the screw; an information acquisition device that acquires information related to a road that is a target of construction; and a control device that controls an operation of the tractor based on a target track or a target position determined based on the information related to the road that is the target of construction acquired by the information acquisition device, wherein the control device calculates and sets, as the target track that the steering reference point should follow, a target track based on a distance in a front-rear direction between a steering reference point that corresponds to a center portion of the tractor in advance and the screed, and a center line of a road followed by a prescribed point of the center portion of the screed, in order to align a width direction center of the road that is the target of construction with a width direction center of the screed when a curved portion of the road that is the target of construction is constructed, and the control device causes the steering reference point to follow the target track by changing a steering angle when the curved portion of the road that is the target of construction is constructed.

2. The asphalt paver according to claim 1, wherein the control device sets the target track or the target position at a position that is further outward than a center of the road that is the target of construction in the curved portion of the road that is the target of construction.

3. The asphalt paver according to claim 1, wherein the target track is a set of data in which position coordinates of a plurality of target positions are continuously arranged.

4. The asphalt paver according to claim 1, wherein the control device sets the target track in such a manner that at least one of both end portions of the screed aligns with a terrestrial object that forms a boundary line of the road that is the target of construction.

5. The asphalt paver according to claim 1, wherein the control device controls the operation of the tractor by controlling a steering angle of a front wheel in the case of a wheeled asphalt paver, and controls the operation of the tractor by individually controlling a rotational speed of each of a left track and a right track in the case of a tracked asphalt paver.

6. The asphalt paver according to claim 1, wherein the control device controls the operation of the tractor in such a manner that the asphalt paver moves along the target track set in advance.

7. The asphalt paver according to claim 1, wherein the information acquisition device is a camera device or a communication device. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Images