Road machine and road machine hopper control system

Abstract

To reduce a burden on an operator when operating a hopper.SOLUTION: An asphalt finisher 100 comprises: a tractor 1; a hopper 2 which is installed at the front of the tractor 1 and receives a paving material PV; a conveyor CV which feeds the paving material PV in the hopper 2 to the rear of the tractor 1; a screw SC which spreads the paving material PV fed by the conveyor CV at the rear of the tractor 1; a screed 3 which levels the paving material PV spread by the screw SC at the rear of the screw SC; an object detection device (space recognition device 51) which detects an object around the asphalt finisher 100; and a controller 50 which controls opening and closing of the hopper 2 based on a positional relation between a vehicle detected by the object detection device and the asphalt finisher 100.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to road machinery and a hopper control system for road machinery.

Background Art

[0002] Conventionally, road machinery equipped with a hopper for receiving paving materials transported by a dump truck has been known (see Patent Document 1). This road machinery is configured to receive paving materials from the fully opened hopper into the dump truck bed in a state where the rear wheels of the dump truck are in contact with the push roller at the front end of the road machinery (in a state of vehicle connection or docking). The hopper is configured to be opened and closed according to the operation of an operator.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above-described configuration, if the operator of the road machinery forgets to fully open the hopper, the driver of the dump truck cannot bring the rear wheels of the dump truck into contact with the push roller. This is because there is a risk of bringing the dump truck bed into contact with the hopper wing. Therefore, the operation of the hopper by the operator of the road machinery is an important operation that cannot be forgotten for smooth replenishment of paving materials. And such an operation of the hopper that cannot be forgotten may become a burdensome task for the operator of the road machinery.

[0005] Therefore, it is desired to provide road machinery that can reduce the burden on the operator regarding the operation of the hopper.

Means for Solving the Problems

[0006] The road machinery according to an embodiment of the present disclosure includes a tractor, a hopper installed in front of the tractor for receiving paving material from a vehicle that transports the paving material, a conveyor for feeding the paving material in the hopper to the rear of the tractor, a screw for spreading the paving material fed by the conveyor to the rear of the tractor, a screed for leveling the paving material spread by the screw to the rear of the screw, an object detection device for detecting an object around the road machinery, and a control device for controlling the opening and closing of the hopper based on the positional relationship between the vehicle detected by the object detection device and the road machinery.

Advantages of the Invention

[0007] The above-described road machinery can reduce the burden on the operator regarding the operation of the hopper.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0009] FIG. 1 is a side view of an asphalt finisher 100 and a dump truck 200, which are examples of road machinery according to an embodiment of the present disclosure. The road machinery may be a base paver, a tack paver, a multi-asphalt paver, or the like. The dump truck 200 is an example of a transport vehicle for replenishing (loading) paving material PV into the hopper 2 of the asphalt finisher 100. FIG. 2 is a top view of the asphalt finisher 100 and the dump truck 200, corresponding to FIG. 1. Specifically, FIG. 1 is a side view of the asphalt finisher 100 and the dump truck 200 during construction (during laying of the paving material PV), and FIG. 2 is a top view of the asphalt finisher 100 and the dump truck 200 during construction (during laying of the paving material PV).

[0010] The asphalt finisher 100 mainly includes a tractor 1, a hopper 2, and a screed 3. Hereinafter, for convenience, the direction of the hopper 2 viewed from the tractor 1 (+X direction) is defined as the front, and the direction of the screed 3 viewed from the tractor 1 (-X direction) is defined as the rear. Also, the +Z direction is defined as vertically upward, and the -Z direction is defined as vertically downward.

[0011] The tractor 1 is a mechanism for driving the asphalt finisher 100. In the illustrated example, the tractor 1 rotates the rear wheels 5 using a hydraulic motor for rear-wheel travel and rotates the front wheels 6 using a hydraulic motor for front-wheel travel to move the asphalt finisher 100. The hydraulic motor for rear-wheel travel and the hydraulic motor for front-wheel travel rotate by receiving the supply of hydraulic oil from a hydraulic pump. The rear wheels 5 and the front wheels 6 may be replaced with crawlers.

[0012] The controller 50 is a control device for controlling the asphalt finisher 100. In the illustrated example, the controller 50 is composed of a microcomputer including a CPU, a volatile memory device, a non-volatile memory device, etc., and is mounted on the tractor 1. Various functions of the controller 50 are realized by the CPU executing a program stored in a non-volatile storage medium.

[0013] Hopper 2 is a mechanism for receiving paving material PV. In the illustrated example, the hopper 2 is installed on the frame FR that constitutes the lower front side of the tractor 1 and includes hopper wings 2W. The hopper wings 2W are configured to be openable and closable in the Y-axis direction (width direction, vehicle width direction) by a hopper cylinder 7. Specifically, the hopper wings 2W include a left hopper wing 2WL that can be opened and closed to the left by a left hopper cylinder 7L and a right hopper wing 2WR that can be opened and closed to the right by a right hopper cylinder 7R. The controller 50 can open the hopper wings 2W by contracting the hopper cylinder 7 and close the hopper wings 2W by extending the hopper cylinder 7.

[0014] The asphalt finisher 100 usually receives the paving material PV from the loading platform 201 of the dump truck 200 with the hopper wings 2W fully open (the most open state). In the illustrated example, the paving material PV is an asphalt mixture and is also referred to as an "asphalt composite material". In FIGS. 1 and 2, the hopper wings 2W are in the fully open state. Note that in FIG. 2, the illustration of the paving material PV received in the hopper 2 is omitted so that a part of the conveyor CV can be seen. The paving material PV received in the hopper 2 is fed to the rear of the tractor 1 by a conveyor CV located at the center of the bottom of the hopper 2. When the paving material PV in the hopper 2 decreases, the hopper wings 2W are closed, and the paving material PV near the inner wall of the hopper 2 is collected at the center of the bottom of the hopper 2. This is to enable the conveyor CV to feed the paving material PV to the rear of the tractor 1. If the operator of the asphalt finisher 100 forgets to close the hopper wings 2W, the supply of the paving material PV to the center of the bottom may be insufficient, and ultimately the supply of the paving material PV to the rear of the tractor 1 may be insufficient, causing poor construction. Therefore, the controller 50 may be configured to automatically close the hopper 2 when a predetermined hopper closing condition is satisfied.

[0015] The paving material PV fed to the rear of the tractor 1 is spread in the vehicle width direction behind the tractor 1 and in front of the screed 3 by the screw SC. In the illustrated example, the screw SC is in a state where the left extension screw SCL and the right extension screw SCR are connected. Also, in FIGS. 1 and 2, the paving material PV spread by the screw SC is shown by a coarse dot pattern, and the newly paved body NP leveled by the screed 3 is shown by a fine dot pattern.

[0016] A push roller 2P rotatable about an axis extending in the vehicle width direction is provided at the front end of the frame FR. The push roller 2P is configured to be in contact with the rear wheels (rear rear wheels 204) of the dump truck 200 and rotate together with the rear wheels (rear rear wheels 204) of the dump truck 200. In the illustrated example, the push roller 2P includes a left push roller 2PL that contacts the left rear wheels (left outer rear rear wheels 204EL and left inner rear rear wheels 204IL) of the dump truck 200, and a right push roller 2PR that contacts the right rear wheels (right outer rear rear wheels 204ER and right inner rear rear wheels 204IR) of the dump truck 200.

[0017] When the asphalt finisher 100 is moving forward during the contact (docking) between the push roller 2P and the rear wheels (rear rear wheels 204) of the dump truck 200, the dump truck 200 desirably stops in a neutral state without applying the brakes at a position several centimeters in front of the asphalt finisher 100. Thereafter, the forward-moving asphalt finisher 100 brings the push roller 2P into contact with the rear wheels (rear rear wheels 204) of the stopped dump truck 200 and moves forward together with the dump truck 200 while pushing the dump truck 200 forward. When the asphalt finisher 100 is stopped during docking, the dump truck 200 may reverse at a low speed until the rear wheels (rear rear wheels 204) and the push roller 2P come into contact.

[0018] The screed 3 is a mechanism for leveling the paving material PV. In the illustrated example, the screed 3 includes a front screed 30 and a rear screed 31. The screed 3 is a floating screed towed by the tractor 1 and is connected to the tractor 1 via a leveling arm 3A. The rear screed 31 includes a left rear screed 31L configured to be extendable and retractable to the left, and a right rear screed 31R configured to be extendable and retractable to the right. In FIGS. 1 and 2, the screed 3 is in the most extended (widest) state.

[0019] A side plate 41 is attached to the distal end of the rear screed 31. In the illustrated example, a left side plate 41L is attached to the left end of the left rear screed 31L, and a right side plate 41R is attached to the right end of the right rear screed 31R.

[0020] A tread plate 32 is attached to the rear part of the screed 3. Specifically, the tread plate 32 is attached to the rear part of the screed 3 so that an operator can move back and forth in the vehicle width direction without stepping on the newly paved surface NP behind the screed 3. In the illustrated example, the tread plate 32 includes a central tread plate 32C attached to the rear part of the front screed 30, a left tread plate 32L attached to the rear part of the left rear screed 31L, and a right tread plate 32R attached to the rear part of the right rear screed 31R.

[0021] A mold board 42 is disposed in front of the rear screed 31. In the illustrated example, the mold board 42 is attached to the screed 3 and is configured to be movable up and down to adjust the amount of the paving material PV staying in front of the rear screed 31. The paving material PV reaches under the screed 3 through the gap between the lower end of the mold board 42 and the roadbed RB.

[0022] Specifically, the mold board 42 includes a left mold board 42L disposed in front of the left rear screed 31L, and a right mold board 42R disposed in front of the right rear screed 31R.

[0023] A screw SC is disposed in front of the mold board 42, and a retaining plate 43 is disposed in front of the screw SC. Specifically, the retaining plate 43 includes a left retaining plate 43L disposed in front of the left extension screw SCL and a right retaining plate 43R disposed in front of the right extension screw SCR. Note that the retaining plate 43 may be omitted.

[0024] A space recognition device 51, a display device 55, and a sound output device 56 are attached to the upper part of the tractor 1.

[0025] The space recognition device 51 is configured to recognize the space around the asphalt finisher 100. The space recognition device 51 includes at least one of a monocular camera, a stereo camera, a LIDAR, an ultrasonic sensor, an infrared sensor, a laser radar, and a millimeter wave radar. Note that the space recognition device 51 may include a space recognition device installed on the road and not attached to the asphalt finisher 100, or may be a space recognition device not attached to the asphalt finisher 100. In this case, the space recognition device not attached to the asphalt finisher 100 may be connected to the controller 50 via wireless communication or wired communication. In the illustrated example, the space recognition device 51 is a monocular camera capable of imaging the surroundings of the asphalt finisher 100.

[0026] In the illustrated example, the space recognition device 51 includes a rear camera 51B for imaging the rear of the asphalt finisher 100, a front camera 51F for imaging the front of the asphalt finisher 100, a left camera 51L for imaging the left side of the asphalt finisher 100, and a right camera 51R for imaging the right side of the asphalt finisher 100.

[0027] The display device 55 is a display device attached to the tractor 1 so that a person in front of the asphalt finisher 100 can visually recognize it. In the illustrated example, the display device 55 is a liquid crystal display capable of displaying characters, figures, etc., and is attached to the upper right end of the tractor 1 so that the driver of the right-hand dump truck 200 can directly visually recognize it or through a side mirror or a room mirror. Specifically, the display device 55 is attached so as to protrude to the right from the vehicle width of the tractor 1.

[0028] The sound output device 56 is configured to output sound toward a person in front of the asphalt finisher 100. In the illustrated example, the sound output device 56 is a speaker capable of outputting voice, and is attached to the upper right end of the tractor 1 so that the driver of the right-hand dump truck 200 can easily hear it.

[0029] The dump truck 200 includes a loading platform 201 for loading the paving material PV. In the illustrated example, the dump truck 200 is a 10-wheel dump truck with double tires on the rear wheels, and includes front wheels 202, rear front wheels 203, and rear rear wheels 204. The rear front wheels 203 and the rear rear wheels 204 constitute the rear wheels of the dump truck 200. In the illustrated example, as shown in FIG. 2, the front wheels 202 include a left front wheel 202L and a right front wheel 202R, the rear front wheels 203 include a left outer rear front wheel 203EL, a left inner rear front wheel 203IL, a right outer rear front wheel 203ER, and a right inner rear front wheel 203IR, and the rear rear wheels 204 include a left outer rear rear wheel 204EL, a left inner rear rear wheel 204IL, a right outer rear rear wheel 204ER, and a right inner rear rear wheel 204IR.

[0030] Next, referring to FIG. 3, a hopper control system SYS for assisting the construction by the asphalt finisher 100 will be described. FIG. 3 is a block diagram showing a configuration example of the hopper control system SYS. The hopper control system SYS mainly includes a controller 50, a space recognition device 51, an information acquisition device 53, a display device 55, a sound output device 56, a hopper control device HC, and the like. In the illustrated example, the controller 50, the space recognition device 51, the information acquisition device 53, the display device 55, the sound output device 56, and the hopper control device HC are supplied with power from a power supply device 60.

[0031] The power supply device 60 converts the AC power generated by a generator 62 driven by a diesel engine 61, which is an example of a drive source, into DC power. The power supply device 60 may be supplied with power from a battery (not shown).

[0032] The diesel engine 61 is configured such that its rotation axis is connected to the rotation axis of the main pump 65 so as to be able to drive the main pump 65.

[0033] The main pump 65 is configured to be able to supply hydraulic oil to a hydraulic actuator including a hopper cylinder 7. In the illustrated example, the main pump 65 is a variable displacement type hydraulic pump capable of discharging hydraulic oil for expanding and contracting the hopper cylinder 7.

[0034] The thick dotted line in FIG. 3 represents a power line, the thin solid line represents a signal line, the thick solid line represents a first oil passage HL through which hydraulic oil flows, and the double line represents that each of the diesel engine 61, the generator 62, and the main pump 65 is mechanically connected.

[0035] Note that the diesel engine 61 may be replaced with another internal combustion engine such as a hydrogen engine. Also, the drive source may be replaced with a combination of an all-solid-state battery or a lithium-ion battery and an electric motor, etc.

[0036] The controller 50 includes a hopper control unit 50a as a functional element. The hopper control unit 50a is composed of software, hardware, firmware, or a combination thereof, and controls the display device 55, the sound output device 56, and the hopper control device HC.

[0037] In the illustrated example, the hopper control unit 50a determines whether the opening and closing operation of the hopper wing 2W is necessary based on at least one output of the space recognition device 51 and the information acquisition device 53. Then, when it is determined that the opening and closing operation is necessary, the hopper control unit 50a outputs a command regarding the start of the opening and closing operation to the hopper control device HC. The hopper control device HC is configured to be able to open and close the hopper wing 2W in response to a command from the hopper control unit 50a.

[0038] Specifically, the hopper control device HC is a solenoid valve configured to be able to adjust the pilot pressure of the hopper spool valve HV. The hopper spool valve HV is a control valve provided in the first oil passage HL connecting the main pump 65 and the hopper cylinder 7. The solenoid valve as the hopper control device HC can control the expansion and contraction of the hopper cylinder 7 by opening and closing in response to a command from the controller 50 and adjusting the pilot pressure acting on the pilot port of the hopper spool valve HV. Note that the pilot port of the hopper spool valve HV includes a closed-side pilot port and an open-side pilot port. However, the pilot port of the hopper spool valve HV may be configured to include only the closed-side pilot port. Also, the hopper control device HC may be the hopper spool valve HV as a solenoid valve.

[0039] The information acquisition device 53 is configured to acquire information and output the acquired information to the controller 50. The information acquisition device 53 includes at least one of, for example, a communication device, a positioning device, a traveling speed sensor, a steering angle sensor, a paving thickness sensor, and a paving width sensor. The communication device controls communication with an external device such as a communication device mounted on the dump truck 200. The traveling speed sensor detects the traveling speed of the asphalt finisher 100. The steering angle sensor detects the steering angle of the asphalt finisher 100. The paving thickness sensor detects the height of the roadbed RB and the height of the newly installed paving body NP and calculates the paving thickness. The paving width sensor detects the extension amount of the rear screen 31 and calculates the paving width. Note that the information acquisition device 53 may be an input device such as a touch panel or a switch.

[0040] Next, with reference to FIG. 4, an example of a process in which the hopper control unit 50a controls the hopper control device HC to open and close the hopper 2 (hereinafter referred to as the "hopper opening and closing process") will be described. FIG. 4 is a flowchart of an example of a process in which the hopper control unit 50a controls the hopper control device HC to open the hopper 2 (hereinafter referred to as the "hopper opening process"). The hopper opening process is an example of the hopper opening and closing process. In the example shown in FIG. 4, the hopper control unit 50a repeatedly executes this hopper opening process at a predetermined control cycle during the operation of the asphalt finisher 100. The hopper control unit 50a starts executing the hopper opening process, for example, when the power supply device 60 receives power supply or when the operation of the diesel engine 61 is started. Note that the hopper control unit 50a may be configured to start executing this hopper opening process when a predetermined operation is performed via an input device such as an operation of a switch. Further, the hopper control unit 50a may be configured to stop executing this hopper opening process when a predetermined operation is performed via an input device such as an operation of a switch.

[0041] First, the hopper control unit 50a determines whether the hopper opening condition is satisfied (step ST1). In the illustrated example, the hopper control unit 50a determines that the hopper opening condition is satisfied when at least one of the space recognition device 51 and the information acquisition device 53 acquires information regarding the approach of the dump truck 200 to the asphalt finisher 100. Note that the hopper opening condition may include, as one of the hopper opening conditions, that the hopper 2 is not in the fully open state.

[0042] For example, when the hopper control unit 50a detects that the dump truck 200 has entered the first range ZN1, which is a predetermined range in front of the asphalt finisher 100, based on the image acquired by the front camera 51F as the space recognition device 51, the hopper control unit 50a determines that the hopper opening condition is satisfied on the assumption that it has acquired information regarding the approach of the dump truck 200 to the asphalt finisher 100. That is, the space recognition device 51 may be configured to function as an object detection device.

[0043] Alternatively, when the hopper control unit 50a detects that the distance DS1 between the asphalt finisher 100 and the dump truck 200 has fallen below a predetermined first distance based on the output of the ultrasonic sensor as the space recognition device 51, the hopper control unit 50a may determine that the hopper opening condition is satisfied on the assumption that it has acquired information regarding the approach of the dump truck 200 to the asphalt finisher 100. In this case, the distance DS1 is, for example, the distance between the ultrasonic sensor attached to the front end portion of the frame FR and the rear rear wheel 204 of the dump truck 200. Then, the ultrasonic sensor is arranged such that the position in the traveling direction of the asphalt finisher 100 is the same as the position of the push roller 2P. That is, the distance DS1 is the distance between the push roller 2P and the rear rear wheel 204.

[0044] Alternatively, when the hopper control unit 50a detects that the dump truck 200 has entered the first range ZN1 based on the information received by the communication device as the information acquisition device 53, it may determine that the hopper opening condition is satisfied. The information received by the communication device as the information acquisition device 53 includes, for example, the output of a positioning device such as a GNSS receiver mounted on the dump truck 200. In this case, the hopper control unit 50a can detect that the dump truck 200 has entered the first range ZN1 based on the output of the positioning device as the information acquisition device 53 mounted on the asphalt finisher 100 and the output of the positioning device mounted on the dump truck 200. In this case, the controller 50 may be configured to calculate the distance between the asphalt finisher 100 and the dump truck 200 and determine that the hopper opening condition is satisfied when the distance is less than a predetermined first distance.

[0045] When it is determined that the hopper opening condition is not satisfied (NO in step ST1), the hopper control unit 50a ends the current hopper opening process without opening the hopper 2.

[0046] On the other hand, when it is determined that the hopper opening condition is satisfied (YES in step ST1), the hopper control unit 50a determines whether there is an object within the opening / closing range of the hopper 2 (step ST2). In the illustrated example, the hopper control unit 50a determines whether there is an object within the second range ZN2, which is an example of the opening / closing range of the hopper 2, based on the image acquired by the front camera 51F as the space recognition device 51. The opening / closing range of the hopper 2 is a preset space range that includes, for example, the space between the hopper wing 2W in the fully closed state (the most closed state) and the hopper wing 2W in the fully open state. Specifically, the second range ZN2 includes the second left range ZN2L, which is an example of the opening / closing range of the left hopper wing 2WL, and the second right range ZN2R, which is an example of the opening / closing range of the right hopper wing 2WR.

[0047] When it is determined that there is no object within the opening / closing range of the hopper 2 (NO in step ST2), the hopper control unit 50a activates the hopper control device HC to open the hopper 2 (step ST3). In the illustrated example, the hopper control unit 50a outputs a current command to the solenoid valve as the hopper control device HC. The solenoid valve as the hopper control device HC that has received the current command adjusts the pilot pressure acting on the pilot port on the opening side of the hopper spool valve HV by adjusting the flow area of the oil passage through which the pilot oil flows, and operates the hopper spool valve HV so that the hopper cylinder 7 contracts (so that the working oil flows out from the bottom side oil chamber of the hopper cylinder 7) to fully open the hopper 2. After fully opening the hopper 2, the hopper control unit 50a may output a command to at least one of the display device 55 and the sound output device 56. In this case, the display device 55 that has received the command may display character information such as "Reverse possible" or "Please dock" or an image conveying the same, and prompt the driver of the dump truck 200 to reverse the dump truck 200. Alternatively, the sound output device 56 that has received the command may output an alarm or sound information such as "Reverse possible" or "Please dock" to prompt the driver of the dump truck 200 to reverse the dump truck 200.

[0048] On the other hand, when it is determined that an object exists within the opening / closing range of the hopper 2 (YES in step ST2), the hopper control unit 50a notifies the outside of the current situation (step ST4). In the illustrated example, the hopper control unit 50a determines that the hopper wing 2W cannot be opened because an object exists within the second range ZN2. Then, the hopper control unit 50a determines that if the dump truck 200 continues to reverse, the loading platform 201 of the dump truck 200 may come into contact with the hopper wing 2W that is not in the fully open state, and outputs a command to at least one of the display device 55 and the sound output device 56. The display device 55 that has received the command displays, for example, character information such as "Reverse prohibited" or "Please stop" or an image conveying the same, prompting the driver of the dump truck 200 to stop the dump truck 200. Alternatively, the sound output device 56 that has received the command outputs an alarm or sound information such as "Reverse prohibited" or "Please stop", prompting the driver of the dump truck 200 to stop the dump truck 200. This is to prevent the loading platform 201 of the dump truck 200 from coming into contact with the hopper wing 2W that is not in the fully open state. Note that the hopper control unit 50a may be configured to prompt the driver of the dump truck 200 to move forward the dump truck 200 as necessary.

[0049] As described above, when the hopper control unit 50a determines that an object exists within the opening / closing range of the hopper 2, it ends the current hopper opening process without operating the hopper control device HC, that is, without automatically opening the hopper 2. This is to avoid contact between the hopper 2 and the object.

[0050] Note that the controller 50 may be configured to distinguish the dump truck 200 from objects other than the dump truck 200 by performing various image processes on the images acquired by the front camera 51F. The image process may include, for example, an image recognition process such as deep learning. In this case, when the hopper control unit 50a determines that there is an object other than the dump truck 200 within the first range ZN1, the hopper opening process for this time may be terminated without automatically opening the hopper 2. This configuration has the effect of suppressing the hopper 2 from automatically opening in response to an object other than the dump truck 200.

[0051] Further, the controller 50 may be configured to distinguish a person from an object other than a person by performing various image processes on the images acquired by the space recognition device 51. Also, the operator may wear an armband or a helmet on which a predetermined marker is drawn. This is to make it easier to be recognized by the image recognition process. That is, it is to enable the controller 50 to detect the position of the operator by finding an image of a predetermined marker. In this case, when the hopper control unit 50a determines that there is a person within the first range ZN1 or the second range ZN2, it may execute the same process as when it determines that there is an object other than a person, or it may execute a process different from when it determines that there is an object other than a person. The process different from when it determines that there is an object other than a person is, for example, an emergency stop of the dump truck 200, or an emergency stop of the asphalt finisher 100. This is to surely prevent contact between the dump truck 200 or the asphalt finisher 100 and a person. In this case, the asphalt finisher 100 may be configured to be able to cause the dump truck 200 to make an emergency stop.

[0052] Note that the controller 50 may be configured to detect an object such as a dump truck 200 or a person existing around the asphalt finisher 100 based on the output of another object detection device (space recognition device) such as a stereo camera, a millimeter wave radar, an ultrasonic sensor, a lidar, an infrared sensor, or LIDAR, and may be configured to calculate the distance between the detected object and the asphalt finisher 100.

[0053] Also, step ST2, which is a process of determining whether an object exists within the opening / closing range of the hopper 2, may be omitted, or may be integrated into step ST1, which is a process of determining whether the hopper opening condition is satisfied. In this case, the hopper control unit 50a can open the hopper 2 when it determines that the hopper opening condition is satisfied.

[0054] Further, the controller 50 may be configured to calculate a reliability (a value representing the certainty of the recognition result) of the recognition result that the object approaching the asphalt finisher 100 is the dump truck 200 based on at least one output of the space recognition device 51 and the information acquisition device 53. Then, the controller 50 may be configured to automatically open the hopper 2 when the reliability is equal to or higher than a first threshold value. Further, when the reliability is equal to or higher than a second threshold value and lower than the first threshold value, the controller 50 may be configured to automatically open the hopper 2 and then notify the operator of the asphalt finisher 100 through sound output or image display that the object approaching the asphalt finisher 100 may not be the dump truck 200. This configuration can bring about an effect of suppressing the situation where the hopper 2 is left in the fully open state and the paving material PV in the hopper 2 is unnecessarily cooled although the replenishment of the paving material PV by the dump truck 200 is not performed. Alternatively, when the reliability is lower than the second threshold value, the controller 50 may be configured not to automatically open the hopper 2 and notify the operator that the object approaching the asphalt finisher 100 may not be the dump truck 200 or that an object other than the dump truck 200 is approaching the asphalt finisher 100. This configuration can bring about an effect of suppressing the situation where the hopper 2 is fully opened and the paving material PV in the hopper 2 is unnecessarily cooled although the replenishment of the paving material PV by the dump truck 200 is not performed. Further, in this case, the controller 50 may cause the sound output device 56 to output an alarm to arouse the operator's attention to the object approaching the asphalt finisher 100.

[0055] Further, the controller 50 may be configured to determine whether an object other than the dump truck 200 is a moving object such as a person or an animal or a stationary object. And when the controller 50 determines that an object other than the dump truck 200 is a moving object, it may be configured to issue an alarm toward the moving object. This configuration can make a moving object that is not aware of the presence of the asphalt finisher 100 aware of the presence of the asphalt finisher 100, and has the effect of prompting the moving object to withdraw from a predetermined range in front of the asphalt finisher 100. Also, when the controller 50 determines that an object other than the dump truck 200 is a stationary object, it may be configured to issue an alarm toward the operator of the asphalt finisher 100, and may stop the asphalt finisher 100 urgently as needed. This is to prevent contact between the asphalt finisher 100 and the stationary object. Note that this process can also be used when it is determined that an object other than the dump truck 200 is a moving object.

[0056] Through such a hopper opening process, the controller 50 can automatically open the hopper 2 to the fully open state before the dump truck 200 and the asphalt finisher 100 come into contact, without the operator of the asphalt finisher 100 manually performing the opening operation of the hopper 2. Therefore, the controller 50 can suppress the occurrence of contact between the loading platform 201 of the dump truck 200 and the hopper wing 2W.

[0057] Next, referring to FIGS. 5 to 7, another example of the hopper opening / closing process will be described. FIG. 5 is a flowchart of an example of a process (hereinafter referred to as "hopper closing process") in which the hopper control unit 50a controls the hopper control device HC to close the hopper 2. The hopper closing process is an example of the hopper opening / closing process. In the example shown in FIG. 5, the hopper control unit 50a repeatedly executes this hopper closing process at a predetermined control cycle during the operation of the asphalt finisher 100. The hopper control unit 50a starts executing the hopper closing process, for example, when the hopper 2 is in the fully open state. Note that the hopper control unit 50a may be configured to start executing this hopper closing process when a predetermined operation via an input device such as an operation of a switch is performed. Also, the hopper control unit 50a may be configured to stop executing this hopper closing process when a predetermined operation via an input device such as an operation of a switch is performed.

[0058] FIG. 6 is a side view of the asphalt finisher 100 and the dump truck 200 when the hopper closing process is being executed. FIG. 7 is a top view of the asphalt finisher 100 and the dump truck 200 when the hopper closing process is being executed, corresponding to FIG. 6. In FIGS. 6 and 7, the loading platform 201 of the dump truck 200 is lifted by the hoist cylinder 205, and the paving material PV loaded on the loading platform 201 is replenished into the hopper 2. Note that the state in which the loading platform 201 is lifted by the hoist cylinder 205 is also called the state in which the loading platform 201 is dumped up. The dump truck 200 maintains the state in which the loading platform 201 is dumped up until all the paving materials PV loaded on the loading platform 201 are replenished into the hopper 2. Then, when all the paving materials PV loaded on the loading platform 201 are replenished into the hopper 2, the dump truck 200 starts moving forward and moves away from the asphalt finisher 100.

[0059] The hopper closing process to be described with reference to FIGS. 6 and 7 is different from the above-described hopper opening process that is executed when the hopper 2 is not in the fully open state in that it is executed when the hopper 2 is in the fully open state, for example, when the dump truck 200 is replenishing the paving material PV from the loading platform 201 into the hopper 2 of the asphalt finisher 100.

[0060] Also in this hopper closing process, the hopper control unit 50a first determines whether or not the hopper closing condition is satisfied (step ST11). In the illustrated example, the hopper control unit 50a determines that the hopper closing condition is satisfied when at least one of the space recognition device 51 and the information acquisition device 53 acquires information regarding the departure of the dump truck 200 from the asphalt finisher 100. Specifically, the hopper control unit 50a determines that the information regarding the departure of the dump truck 200 from the asphalt finisher 100 has been acquired and the hopper closing condition is satisfied when it detects that the dump truck 200 has exited from within the third range ZN3, which is a predetermined range in front of the asphalt finisher 100, based on the image acquired by the front camera 51F as the space recognition device 51. Note that the third range ZN3 is typically a range smaller than the first range ZN1 in FIGS. 1 and 2, but it may be the same range as the first range ZN1 or a range larger than the first range ZN1.

[0061] Alternatively, when the hopper control unit 50a detects that the distance DS2 between the asphalt finisher 100 and the dump truck 200 exceeds a predetermined second distance based on the output of the ultrasonic sensor as the space recognition device 51, it may be determined that the hopper closing condition is satisfied on the assumption that information regarding the departure of the dump truck 200 from the asphalt finisher 100 has been obtained. In this case, the distance DS2 is, for example, the distance between the ultrasonic sensor attached to the front end of the frame FR and the rear rear wheel 204 of the dump truck 200. The ultrasonic sensor is arranged such that the position in the traveling direction of the asphalt finisher 100 is the same as the position of the push roller 2P. That is, the distance DS2 is the distance between the push roller 2P and the rear rear wheel 204. Note that the predetermined second distance is typically smaller than the predetermined first distance regarding the distance DS1 in FIGS. 1 and 2, but may be the same as the predetermined first distance or larger than the predetermined first distance.

[0062] Alternatively, the hopper control unit 50a may determine that the hopper closing condition is satisfied when a predetermined hopper closing switch is operated by the operator of the asphalt finisher 100.

[0063] Note that the hopper closing condition may include, as one of the hopper closing conditions, that the hopper 2 is not in the fully closed state.

[0064] When it is determined that the hopper closing condition is satisfied (YES in step ST11), the hopper control unit 50a determines whether or not there is an object within the opening / closing range of the hopper 2 (step ST12). In the illustrated example, the hopper control unit 50a determines whether or not there is an object within the second range ZN2 based on the image acquired by the front camera 51F as the space recognition device 51.

[0065] When it is determined that there is no object within the opening / closing range of the hopper 2 (NO in step ST12), the hopper control unit 50a operates the hopper control device HC to close the hopper 2 (step ST13). In the illustrated example, the hopper control unit 50a outputs a current command to the solenoid valve as the hopper control device HC. The solenoid valve as the hopper control device HC that has received the current command adjusts the pilot pressure acting on the closing-side pilot port of the hopper spool valve HV by adjusting the flow area of the oil passage through which the pilot oil flows, and operates the hopper spool valve HV so that the hopper cylinder 7 extends (so that the operating oil flows into the bottom-side oil chamber of the hopper cylinder 7) to fully close the hopper 2.

[0066] On the other hand, when it is determined that there is an object within the opening / closing range of the hopper 2 (YES in step ST12), the hopper control unit 50a ends the current hopper closing process without operating the hopper control device HC, that is, without automatically closing the hopper 2. This is to surely prevent contact between the hopper wing 2W and the object. Further, the hopper control unit 50a may cause the sound output device 56 to output an alarm. This is to draw attention to the object existing within the opening / closing range of the hopper 2.

[0067] Note that step ST12, which is a process for determining whether an object exists within the opening / closing range of the hopper 2, may be omitted or integrated into step ST11, which is a process for determining whether the hopper closing condition is satisfied. In this case, the hopper control unit 50a can close the hopper 2 when it determines that the hopper closing condition is satisfied. Also, the hopper control unit 50a may determine whether an object exists inside the hopper 2. The object may be, for example, a person working inside the hopper 2 or a paving material PV of a predetermined amount or more inside the hopper 2. In this case, the hopper control unit 50a may determine whether an object exists inside the hopper 2 based on, for example, an image acquired by the front camera 51F as the space recognition device 51. When it is determined that an object exists inside the hopper 2, the hopper control unit 50a may end the current hopper closing process without operating the hopper control device HC, that is, without automatically closing the hopper 2. In other words, the hopper control unit 50a may be configured to operate the hopper control device HC to close the hopper 2 only when it determines that no object exists inside the hopper 2. Also, the process for determining whether an object exists inside the hopper 2 may be integrated into step ST11, which is a process for determining whether the hopper closing condition is satisfied.

[0068] Further, the hopper control unit 50a may be configured to gradually close the hopper 2. This is because when the amount of the paving material PV in the hopper 2 is large, it may be difficult to fully close the hopper 2. That is, even if hydraulic oil is to be made to flow into the bottom side oil chamber of the hopper cylinder 7 to extend the hopper cylinder 7, the pressure in the bottom side oil chamber increases and the hydraulic oil is discharged through the relief valve. In this case, the hopper control unit 50a may be configured to gradually increase the extension amount of the hopper cylinder 7 according to the passage of time from the time when the supply of the paving material PV by the dump truck 200 to the asphalt finisher 100 is completed. Note that the time when the supply of the paving material PV by the dump truck 200 to the asphalt finisher 100 is completed may be, for example, the time when it is determined that the hopper closing condition is satisfied, or may be a time different from the time when it is determined that the hopper closing condition is satisfied (for example, the time when the controller 50 detects that the loading platform 201 of the dump truck 200 has become empty based on the output of the space recognition device 51 or the like). Alternatively, the hopper control unit 50a may be configured to gradually increase the extension amount of the hopper cylinder 7 according to an increase in the travel distance of the asphalt finisher 100 or an increase in the number of rotations of the conveyor CV from the time when it is determined that the hopper closing condition is satisfied. Further, the time interval between each stage and the extension amount of the hopper cylinder 7 at each stage may be determined based on the paving thickness, the paving width, or the like.

[0069] By such hopper closing processing, the controller 50 can start a function of automatically closing the hopper 2 when the dump truck 200 detaches from the asphalt finisher 100 without the operator of the asphalt finisher 100 manually performing the closing operation of the hopper 2. Therefore, the controller 50 can automatically fully close the hopper 2 when the dump truck 200 and the asphalt finisher 100 are separated from each other without the operator of the asphalt finisher 100 manually performing the closing operation of the hopper 2. Therefore, the controller 50 can suppress the unnecessary cooling of the paving material PV in the hopper 2.

[0070] Next, referring to FIG. 8, another configuration example of the hopper control system SYS will be described. FIG. 8 is a schematic diagram showing another configuration example of the hopper control system SYS. The hopper control system SYS is a system that controls the hopper 2 of one or more asphalt finishers 100. In the present embodiment, the hopper control system SYS mainly includes an asphalt finisher 100, a dump truck 200, and a management device 300. Each of the asphalt finisher 100, the dump truck 200, and the management device 300 constituting the hopper control system SYS may be one unit or a plurality of units. Also, the communication with the dump truck 200 may be omitted. In the example shown in FIG. 8, the hopper control system SYS includes one asphalt finisher 100, one dump truck 200, and one management device 300.

[0071] The management device 300 is typically a fixed terminal device, for example, a server computer installed in a management center or the like at a location away from the construction site. The management device 300 may be a portable computer (for example, a notebook PC, a tablet PC, or a mobile terminal device such as a smartphone).

[0072] The management device 300 may be provided with a monitor and an operating device for remote operation. In this case, the operator may operate the asphalt finisher 100 while using the operating device for remote operation. The operating device for remote operation is connected to the controller 50 mounted on the asphalt finisher 100 through a wireless communication network such as a short-range wireless communication network, a mobile phone communication network, or a satellite communication network.

[0073] In the hopper control system SYS shown in FIG. 8, the hopper control unit 50a may be realized by a control device in the management device 300 instead of the controller 50 of the asphalt finisher 100.

[0074] In this case, the controller 50 of the asphalt finisher 100 may transmit at least one of the output of the space recognition device 51, the output of the information acquisition device 53, etc. to the management device 300.

[0075] Further, the space recognition device 51 may include a space recognition device installed on a road, etc., which is not attached to the asphalt finisher 100, and may be a space recognition device not attached to the asphalt finisher 100. In this case, the space recognition device not attached to the asphalt finisher 100 may be connected to the controller 50 via wireless communication or wired communication, and may also be connected to the management device 300.

[0076] As described above, the hopper control system SYS can control the opening and closing of the hopper 2 based on the positional relationship between the asphalt finisher 100 and the dump truck 200 regardless of whether the hopper control unit 50a is implemented in the management device 300 or the controller 50. Therefore, the hopper control system SYS has the effect of reducing the burden on the operator of the asphalt finisher 100 regarding the operation of the hopper 2.

[0077] As described above, the asphalt finisher 100, which is an example of a road machine according to an embodiment of the present disclosure, as shown in FIG. 2, includes a tractor 1, a hopper 2 installed in front of the tractor 1 and receiving paving material PV from a vehicle (dump truck 200) that transports the paving material PV, a conveyor CV that feeds the paving material PV in the hopper 2 to the rear of the tractor 1, a screed SC that spreads the paving material PV fed by the conveyor CV to the rear of the tractor 1, a screed 3 that levels the paving material PV spread by the screed SC to the rear of the screed SC, an object detection device (space recognition device 51) that detects objects around the asphalt finisher 100, and a control device (controller 50) that controls the opening and closing of the hopper 2 based on the positional relationship between the dump truck 200 detected by the object detection device and the asphalt finisher 100.

[0078] This configuration has the effect of reducing the burden on the operator regarding the operation of the hopper 2. For example, this configuration enables the operator to omit the opening operation of the hopper 2 by causing the hopper 2 to automatically open when the dump truck 200 enters a predetermined range in front of the asphalt finisher 100, resulting in the effect of reducing the burden on the operator regarding the opening operation of the hopper 2. Therefore, this configuration can suppress problems such as the driver of the dump truck 200 overlooking the fact that the hopper 2 is closed and causing the loading platform 201 to come into contact with the hopper 2 in situations where it is difficult to obtain a clear view, such as during night construction. Alternatively, this configuration enables the operator to omit the closing operation of the hopper 2 by causing the hopper 2 to automatically close when the dump truck 200 exits a predetermined range in front of the asphalt finisher 100, resulting in the effect of reducing the burden on the operator regarding the closing operation of the hopper 2. Also, this configuration has the effect of suppressing the unnecessary cooling of the paving material PV in the hopper 2 when the hopper 2 is left in the fully open state. Further, this configuration automates the opening and closing operations of the hopper 2, reducing the burden on the operator regarding the opening and closing operations of the hopper 2 and enabling the operator to engage in other operations, thereby resulting in the effect of enhancing the overall accuracy of the construction work. Moreover, this configuration can more reliably and appropriately automate the opening and closing operations of the hopper 2 compared to the case of automating the opening and closing operations of the hopper 2 by grasping the amount of the paving material PV in the hopper 2. This is because it can be difficult to grasp the amount of the black paving material PV based on an image, especially during night work or when the hopper 2 is dirty. In contrast, grasping the positional relationship between the dump truck 200 and the asphalt finisher 100 based on an image or the like can be relatively easily achieved by detecting the illuminated tail lamp of the dump truck 200 during night work.

[0079] Further, as shown in FIGS. 1 and 2, the controller 50 may be configured to open the hopper 2 when the distance DS1 between the dump truck 200 located in front of the asphalt finisher 100 and the asphalt finisher 100 becomes equal to or less than a predetermined distance. Typically, the controller 50 is configured to fully open the hopper 2. Also, the predetermined distance may be a preset fixed value, or may be dynamically set based on at least one of the reverse speed of the dump truck 200, the forward speed of the asphalt finisher 100, and the maximum opening speed of the hopper 2 (the maximum contraction speed of the hopper cylinder 7).

[0080] This configuration brings the effect that the hopper 2 can be surely fully opened at an appropriate timing.

[0081] Further, as shown in FIGS. 6 and 7, the controller 50 may be configured to close the hopper 2 when the dump truck 200 does not exist within a third range ZN3 which is a predetermined range in front of the asphalt finisher 100.

[0082] This configuration brings the effect that the hopper 2 can be closed for as long a period as possible. Also, this configuration can keep the hopper 2 closed for the entire period except for the period during which the paving material PV is replenished into the hopper 2 by the dump truck 200, and brings the effect that unnecessary cooling of the paving material PV in the hopper 2 can be suppressed. Note that this configuration can automatically close the hopper 2 after that, even when the operator manually opens the hopper 2 to visually check the paving material PV in the hopper 2, and brings the effect that the burden on the operator regarding the closing operation of the hopper 2 can be reduced.

[0083] Further, the controller 50 may be configured to start control to automatically close the hopper 2 when the replenishment of the paving material PV by the dump truck 200 to the asphalt finisher 100 is completed.

[0084] This configuration has the effect of enabling the control to automatically close the hopper 2 at an appropriate timing. In this case, when the distance DS2 between the asphalt finisher 100 and the dump truck 200 exceeds a predetermined distance, the controller 50 may determine that the replenishment of the paving material PV by the dump truck 200 to the asphalt finisher 100 is completed and start the control to automatically close the hopper 2.

[0085] Further, the controller 50 may be configured to close the hopper 2 step by step. For example, the controller 50 may be configured to gradually increase the extension amount of the hopper cylinder 7 in response to an increase in the travel distance of the asphalt finisher 100 or an increase in the number of rotations of the conveyor CV from the time when it is determined that the hopper closing condition is satisfied. Also, the extension amount of the hopper cylinder 7 at each stage may be determined based on the paving thickness, paving width, or the like.

[0086] This configuration has the effect of being able to efficiently bring the hopper 2 close to the fully closed state. When the amount of the paving material PV in the hopper 2 is large, even if an attempt is made to flow hydraulic oil into the bottom side oil chamber of the hopper cylinder 7 to extend the hopper cylinder 7 to close the hopper 2, the pressure in the bottom side oil chamber increases and the hydraulic oil is discharged through the relief valve. However, this configuration can close the hopper 2 in a stepwise manner, and while suppressing the discharge of the hydraulic oil through the relief valve, the hopper 2 can be brought into the fully closed state. And this configuration has the effect of being able to suppress the unnecessary cooling of the paving material PV in the hopper 2 by closing the hopper 2 in the fully closed state as early as possible.

[0087] Also, a hopper control system SYS for assisting the construction by the asphalt finisher 100 according to an embodiment of the present disclosure includes an object detection device that detects an object around the asphalt finisher 100, and a control device that controls the opening and closing of the hopper 2 based on the positional relationship between the vehicle (dump truck 200) detected by the object detection device and the asphalt finisher 100. The object detection device may be a device such as a space recognition device 51 mounted on the asphalt finisher 100, or a device that is not mounted on the asphalt finisher 100, such as a device installed on the road. Also, the control device may be a controller 50 mounted on the asphalt finisher 100, or a control device in a management device 300 installed in a management center.

[0088] This configuration, similar to the asphalt finisher 100 according to the embodiment of the present disclosure, brings about the effect of reducing the burden on the operator regarding the operation of the hopper 2.

[0089] The preferred embodiments of the present disclosure have been described above. However, the present invention is not limited to the above-described embodiments, nor is it limited to the embodiments described later. Various modifications, substitutions, etc. can be applied to the above-described or later-described embodiments without departing from the scope of the present invention. Also, each of the features described with reference to the above-described or later-described embodiments may be appropriately combined as long as there is no technical contradiction.

Explanation of Reference Numerals

[0090] 1 ··· Tractor 2 ··· Hopper 2P ··· Push Roller 2PL ··· Left Push Roller 2PR ··· Right Push Roller 2W ··· Hopper Wing 2WL ··· Left Hopper Wing 2WR ··· Right Hopper Wing 3 ··· Screed 3A ··· Levelling Arm 5 ··· Rear Wheel 6 ··· Front Wheel 7 ··· Hopper Cylinder 7L ··· Left Hopper Cylinder 7R ··· Right Hopper Cylinder 30 ··· Front Side Screed 31 ··· Rear Side Screed 31L ··· Left Rear Side Screed 31R ··· Right Rear Side Screed 32 ··· Footboard 32C ··· Central Footboard 32L ··· Left Footboard 32R ··· Right Footboard 41 ··· Side Plate 41L ··· Left Side Plate 41R ··· Right Side Plate 42 ··· Mold Board 42L ··· Left Mold Board 42R ··· Right Mold Board 43 ··· Retaining Plate 43L ··· Left Retaining Plate 43R ··· Right Retaining Plate 50 ··· Controller 50a ··· Hopper Control Unit 51 ··· Space Recognition Device 51B ··· Rear Camera 51F ··· Front Camera 51L ··· Left Camera 51R ··· Right Camera 53 ··· Information Acquisition Device 55 ··· Display Device 56 ··· Sound Output Device 60 ··· Power Supply Device 61 ··· Diesel Engine 62 ··· Generator 65 ··· Main Pump 100 ··· Asphalt Finisher 200 ··· Dump Truck 201 ··· Loading Platform 202 ··· Front Wheel 202L ··· Left Front Wheel 202R ··· Right Front Wheel 203 ··· Rear Front Wheel 203EL ··· Left Outer Rear Front Wheel 203ER ··· Right Outer Rear Front Wheel 203IL ··· Left Inner Rear Front Wheel 203IR ··· Right Inner Rear Front Wheel 204 ··· Rear Rear Wheel 204EL ··· Left Outer Rear Rear Wheel 204ER ··· Right Outer Rear Rear Wheel 204IL ··· Left Inner Rear Rear Wheel 204IR ··· Right Inner Rear Rear Wheel 205 ··· Hoist Cylinder 300 ··· Management Device CV ··· Conveyor FR ··· Frame HC ··· Hopper Control Device HL ··· First Oil Circuit HV ··· Hopper Spool Valve NP ··· New Pavement PV ··· Paving Material RB ··· Roadbed SC ··· Screw SCL ··· Left Extension Screw SCR ··· Right Extension Screw SYS ··· Hopper Control System ZN1 ··· First Range ZN2 ··· Second Range ZN2L ··· Second Left RangeZN2R ··· Second right range, ZN3 ··· Third range

Claims

1. A tractor, a hopper installed in front of the tractor for receiving paving materials from a vehicle that transports the paving materials, a conveyor for feeding the paving materials in the hopper to the rear of the tractor, a screw for spreading the paving materials fed by the conveyor behind the tractor, a screed for leveling the paving materials spread by the screw behind the screw, an object detection device for detecting an object around the road machine, and a control device for controlling the opening and closing of the hopper based on the positional relationship between the vehicle detected by the object detection device and the road machine, a road machine.

2. The control device opens the hopper when the distance between the vehicle located in front of the road machine and the road machine becomes equal to or less than a predetermined distance. The road machine according to Claim 1.

3. The control device closes the hopper when the vehicle does not exist within a predetermined range in front of the road machine. The road machine according to Claim 1.

4. The control device starts control to automatically close the hopper when the replenishment of the paving materials by the vehicle to the road machine is completed. The road machine according to Claim 1.

5. The control device closes the hopper step by step. The road machine according to Claim 4.

6. A hopper control system for a road machine that supports construction by a road machine including a tractor, a hopper installed in front of the tractor for receiving paving materials from a vehicle that transports the paving materials, a conveyor for feeding the paving materials in the hopper to the rear of the tractor, a screw for spreading the paving materials fed by the conveyor behind the tractor, and a screed for leveling the paving materials spread by the screw behind the screw, an object detection device for detecting an object around the road machine, and a control device for controlling the opening and closing of the hopper based on the positional relationship between the vehicle detected by the object detection device and the road machine. A hopper control system for a road machine.

Images