SYSTEM AND METHOD FOR CONTROLLING TRANSPORT VEHICLE

A controller acquires a static path indicative of a target route of a transport vehicle. The static path includes a first endpoint and a second endpoint. The static path is set between a first work machine and a second work machine. The controller determines a first dynamic path that connects the first endpoint and a first target position for work of the first work machine. The controller determines a second dynamic path that connects the second endpoint and a second target position for work of the second work machine. The controller controls the transport vehicle so that the transport vehicle travels according to the static path, the first dynamic path, and the second dynamic path.

BACKGROUND

The present invention relates to a system and a method for controlling a transport vehicle that transports materials between a first work machine and a second work machine.

BACKGROUND INFORMATION

There is work which involves digging materials, such as soil and the like, by a work machine, such as a hydraulic excavator, and loading the materials onto a transport vehicle, such as a dump truck. The transport vehicle is loaded with the materials at a predetermined loading position. The transport vehicle travels to a predetermined dumping position and dumps the materials at the dumping position. The dumped materials are spread and leveled by a work machine, such as a bulldozer. The transport vehicle then returns to the loading position from the dumping position and materials are loaded again by the work machine onto the transport vehicle. Conventionally, as described in International Publication No. 2016/167374, a technique for performing the above transport work by the transport vehicle with automatic control is known. In International Publication No. 2016/167374, a controller, such as a processer, determines a target route of the transport vehicle.

SUMMARY

A hydraulic excavator moves while digging. Also, a bulldozer moves while spreading and leveling the materials. Accordingly, the target route of the transport vehicle changes according to the work conditions of these work machines. Therefore, it is not easy to determine the optimal target route. Also, in order to determine the optimal target route, the load on the controller increases. An object of the present disclosure is to determine the optimal target route of the transport vehicle.

SOLUTION TO PROBLEM

A system according to one aspect of the present disclosure is a system for controlling a transport vehicle that transports materials between a first work machine and a second work machine. The system includes a storage device and a controller. The controller is connected to the storage device. The controller acquires a static path indicative of a target route of the transport vehicle. The static path includes a first endpoint and a second endpoint. The static path is set between the first work machine and the second work machine.

The controller acquires a first target position for work of the first work machine. The controller determines a first dynamic path that connects the first endpoint and the first target position. The controller acquires a second target position for work of the second work machine. The controller determines a second dynamic path that connects the second endpoint and the second target position. The controller controls the transport vehicle so that the transport vehicle travels according to the static path, the first dynamic path, and the second dynamic path.

A method according to another aspect of the present disclosure is a method executed by a controller for controlling a transport vehicle that transports materials between a first work machine and a second work machine. The method includes the following processes. A first process is to acquire a static path indicative of a target route of the transport vehicle. The static path includes a first endpoint and a second endpoint. The static path is set between the first work machine and the second work machine.

A second process is to acquire a first target position for work of the first work machine. A third process is to determine a first dynamic path that connects the first endpoint and the first target position. A fourth process is to acquire a second target position for work of the second work machine. A fifth process is to determine a second dynamic path that connects the second endpoint and the second target position. A sixth process is to control the transport vehicle so that the transport vehicle travels according to the static path, the first dynamic path, and the second dynamic path. The execution order of the processes is not limited to the above-mentioned order and may be changed.

According to the present disclosure, the first dynamic path is determined according to the first target position for the work of the first work machine. The second dynamic path is determined according to the second target position for the work of the second work machine. Accordingly, the optimal travel route of the transport vehicle can be determined.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a control system of a transport vehicle according to an embodiment will be described with reference to the drawings.FIG.1is a plan view illustrating an example of a work site where a transport vehicle1is used. The transport vehicle1, a first work machine2, and a second work machine3are disposed at the work site. In the present embodiment, the first work machine2is a hydraulic excavator. The transport vehicle1is a dump truck. The second work machine3is a bulldozer.

The first work machine2is disposed in a first work area101in the work site. The second work machine3is disposed in a second work area102in the work site. The first work machine2digs in the first work area101and loads the dug materials, such as soil and the like, onto the transport vehicle1. The transport vehicle1moves from the first work area101to the second work area102and dumps the materials in the second work area102. The second work machine3spreads and levels the dumped materials in the second work area102. After dumping the materials, the transport vehicle1returns from the second work area102to the first work area101. The transport vehicle1travels back and forth between the first work area101and the second work area102in the work site. The materials in the first work area101are transported to the second work area102by repeating the above work.

FIG.2is a side view of the transport vehicle1. As illustrated inFIG.2, the transport vehicle1includes a vehicle body10, a traveling body11, and a bed12. The vehicle body10is supported by the traveling body11. The vehicle body10is rotatable around a rotation axis Al with respect to the traveling body11. The vehicle body10includes an operating cabin13. The traveling body11includes crawler belts14. The transport vehicle1travels due to the rotation of the crawler belts14. The traveling body11includes a first traveling body portion15and a second traveling body portion16. The first traveling body portion15and the second traveling body portion16are positioned opposite to each other in a traveling direction of the transport vehicle1. The first traveling body portion15is one end portion in the front-back direction of the traveling body11and the second traveling body portion16is the other end portion in the front-back direction of the traveling body11.

The bed12is supported by the vehicle body10. The bed12is configured to move between a dumping posture and a transporting posture. InFIG.2, the bed12indicated by the solid lines represents a position of the bed12in the transporting posture. The bed12′ indicated by the chain double-dashed lines represents a position of the bed12in the dumping posture. In the transporting posture, the bed12is disposed approximately horizontally. In the dumping posture, the bed12is tilted with respect to the transporting posture.

FIG.3is a side view of the first work machine2. As illustrated inFIG.3, the first work machine2includes a vehicle body21and a work implement22. The vehicle body21includes a rotating body23and a traveling body24. The rotating body23is rotatably attached to the traveling body24. An operating cabin25is disposed on the rotating body23. The traveling body24includes crawler belts26. The first work machine2travels due to the rotation of the crawler belts26.

The work implement22is attached to the front part of the vehicle body21. The work implement22includes a boom27, an arm28, and a bucket29. The boom27is attached to the rotating body23so as to be movable up and down. The arm28is movably attached to the boom27. The bucket29is movably attached to the arm28. Hydraulic cylinders are attached to the boom27, the arm28, and the bucket29. Due to the extension and contraction of the hydraulic cylinders, the work implement22operates.

FIG.4is a side view of the second work machine3. As illustrated inFIG.4, the second work machine3includes a vehicle body30, a traveling body31, and a work implement32. The vehicle body30includes an operating cabin36. The vehicle body30is supported by the traveling body31. The traveling body31includes crawler belts33. The second work machine3travels due to the rotation of the crawler belts33.

The work implement32is attached to the vehicle body30. The work implement32includes a lift frame34and a blade35. The lift frame34is attached to the vehicle body30so as to be movable up and down. The lift frame34supports the blade35. The blade35moves up and down accompanying the up and down movements of the lift frame34. A hydraulic cylinder is attached to the lift frame34. Due to the extension and contraction of the hydraulic cylinder, the work implement32moves up and down.

FIG.5is a block diagram illustrating a configuration of a control system of the transport vehicle1. The transport vehicle1includes an engine41, a hydraulic pump42, a power transmission device43, a lift cylinder44, a rotation motor45, and a control valve46.

The hydraulic pump42is driven by the engine41to discharge hydraulic fluid. Although one hydraulic pump42is illustrated inFIG.5, a plurality of hydraulic pumps may be included. The control valve46is disposed between the lift cylinder44and the hydraulic pump42and between the rotation motor45and the hydraulic pump42. The control valve46controls the flow rate of the hydraulic fluid supplied from the hydraulic pump42to the lift cylinder44. The control valve46may be a pressure proportional control valve. Alternatively, the control valve46may be an electromagnetic proportional control valve.

The power transmission device43transmits driving force of the engine41to the traveling body11. The power transmission device43is, for example, a hydro static transmission (HST).

The lift cylinder44is a hydraulic cylinder. The rotation motor45is a hydraulic motor. The hydraulic fluid discharged from the hydraulic pump42is supplied to the lift cylinder44and the rotation motor45. The lift cylinder44and the rotation motor45are driven by the hydraulic fluid from the hydraulic pump42. The lift cylinder44raises and lowers the bed12. Consequently, the posture of the bed12is switched between the transporting posture and the dumping posture. The rotation motor45rotates the vehicle body10with respect to the traveling body11. The controller48controls the lift cylinder44by means of the control valve46, thereby controlling the operation of the bed12. In addition, the controller48controls the rotation motor45by means of the control valve46, thereby controlling the rotation of the vehicle body10.

The transport vehicle1includes a position sensor47. The position sensor47includes, for example, a global navigation satellite system (GNSS) receiver and an inertial measurement unit (IMU). The position sensor47detects a position of the transport vehicle1and an orientation of the vehicle body10to output position data. The position data includes data indicative of the position of the transport vehicle1and data indicative of the orientation of the vehicle body10.

The transport vehicle1includes a controller48and a storage device49. The controller48includes a processor50, such as a CPU or a GPU. The processor50executes processes for automatic control of the transport vehicle1. The storage device49includes a memory, such as a RAM or a ROM, and an auxiliary storage device, such as a hard disk drive (HDD) or a solid state drive (SSD). The storage device49stores data and programs for the automatic control of the transport vehicle1.

The controller48is communicably connected to the position sensor47and the storage device49by wire or wirelessly. The controller48receives the position data from the position sensor47. The controller48is programmed to control the transport vehicle1based on acquired data. The controller48controls the engine41, the traveling body11, and the power transmission device43, thereby causing the transport vehicle1to travel. The controller48controls the engine41, the hydraulic pump42, and the control valve46, thereby causing the bed12to operate. The controller48controls the engine41, the hydraulic pump42, and the control valve46, thereby rotating the vehicle body10with respect to the traveling body11.

As illustrated inFIG.5, the first work machine2includes a controller51and a position sensor52. The second work machine3includes a controller53and a position sensor54. The controllers51and53and the position sensors52and54have the same configurations as the controller48and the position sensor47of the transport vehicle1, respectively. The position sensor52of the first work machine2outputs data indicative of a position and an orientation of the first work machine2. The position sensor54of the second work machine3outputs data indicative of a position and an orientation of the second work machine3.

The transport vehicle1includes a communication device55. The first work machine2includes a communication device56. The second work machine3includes a communication device57. The communication devices55to57perform data communication with each other via a communication network, such as a wireless LAN or a mobile communication network. The controller48of the transport vehicle1performs data communication with the controller51of the first work machine2via the communication device55. The controller48of the transport vehicle1performs data communication with the controller53of the second work machine3via the communication device55.

The controller48of the transport vehicle1performs data communication with an input device58via the communication device55. The input device58includes a pointing device such as a mouse and a keyboard. Alternatively, the input device58may include a touch screen. The input device58is operable by an operator. The input device58transmits a signal indicative of an operation input by the operator to the controller48. The input device58may be disposed outside of the transport vehicle1. Alternatively, the input device58may be disposed in the transport vehicle1.

Next, processes of automatic control executed by the controller48of the transport vehicle1will be described. As illustrated inFIG.1, the controller48determines a travel path60indicative of a target route of the transport vehicle1. The controller48causes the transport vehicle1to automatically travel according to the travel path60illustrated inFIG.1. The travel path60includes a static path61, a first dynamic path62, and a second dynamic path63.

The static path61is positioned between the first work area101and the second work area102. The static path61is determined regardless of work of the first work machine2and the second work machine3. The first dynamic path62indicates a target route of the transport vehicle1in the first work area101. The first dynamic path62is changed according to work of the first work machine2. The second dynamic path63indicates a target route of the transport vehicle1in the second work area102. The second dynamic path63is changed according to work of the second work machine3.

FIG.6is a flowchart illustrating processes of automatic control executed by the controller48. In step S101, the controller48acquires static path data. The static path data indicates a position of the static path61. As illustrated inFIG.7, the static path data includes coordinates of a first endpoint P1, a second endpoint P2and a plurality of points Pn (n=3, 4, 5, . . . ) between the first endpoint P1and the second endpoint P2. InFIG.7, a reference sign Pn is given to only one of the plurality of points, while other reference signs Pn are omitted.

The first endpoint P1is an endpoint of the static path61at a side of the first work area101. The second endpoint P2is an endpoint of the static path61at a side of the second work area102. When the transport vehicle1moves from the first work area101toward the second work area102(hereinafter referred to as an “approach route”), the first endpoint P1is a starting point of the static path61and the second endpoint P2is an ending point of the static path61. When the transport vehicle1moves from the second work area102toward the first work area101(hereinafter referred to as a “return route”), the second endpoint P2is a starting point of the static path61and the first endpoint P1is an ending point of the static path61.

The static path data is preset and stored in the storage device49. The controller48may acquire the static path data from an external computer via a communication network. Alternatively, the controller48may acquire the static path data via a recording medium. Alternatively, the controller48may generate the static path data by the operator designating the static path61with the input device58.

In step S102, the controller48determines the static path61. As illustrated inFIG.8, the controller48determines a route indicated by the static path data as a first route64. The controller48determines a second route65in which the first route64is offset by a predetermined distance L1in the left-right direction of the transport vehicle1. Further, the controller48determines a third route66in which the first route64is offset by the predetermined distance L1in the direction opposite to the second route65. The controller48calculates the predetermined distance L1by the following formula (1), for example.

FIG.9is a front view of the transport vehicle1and a traveling area of the transport vehicle1. As illustrated inFIG.9, H represents the width of the traveling area of the transport vehicle1and is defined according to the work site. B represents the width of the gauge of the transport vehicle1. D represents the width of the crawler belt. M represents a margin.

The controller48switches between the first route64, the second route65, and the third route66to determine the static path61. For example, the controller48may determine the first route64as the static path61for an approach route and determine the second route65as the static path61for a return route. The controller48may determine the third route66as the static path61for a next approach route and determine the first route64as the static path61for a next return route. Alternatively, the controller48may switch the static path61between the first route64, the second route65, and the third route66for each reciprocating travel. Alternatively, the controller48may switch the static path61to any one of the first route64, the second route65, or the third route66according to the operation of the input device58by the operator.

In step S103, the controller48acquires first target data. The controller48acquires the first target data from the controller51of the first work machine2by communication. As illustrated inFIG.10, the first target data includes the coordinates of a first target position103in the first work area101and a first target orientation104of the transport vehicle1at the first target position103. The first target position103is a target stop position of the transport vehicle1in the first work area101. The first work machine2loads the materials onto the transport vehicle1at the first target position103. The first target data is changed according to work of the first work machine2. The controller51of the first work machine2determines the first target data according to the position and orientation of the first work machine2. For example, the controller51of the first work machine2determines the first target data so that the transport vehicle1faces the front surface or the side surface of the vehicle body21of the first work machine2.

In step S104, the controller48determines the first dynamic path62. As illustrated inFIG.11, the controller48determines, as the first dynamic path62, a route that connects the first endpoint P1and the first target position103. The controller48determines the first dynamic path62according to the first target orientation104of the transport vehicle1.

In step S105, the controller48acquires second target data. The controller48acquires the second target data from the controller53of the second work machine3by communication. The second target data includes the coordinates of a second target position105and a second target orientation106of the transport vehicle1at the second target position105. The second target position105is a target stop position of the transport vehicle1in the second work area102. The second work machine3spreads and levels the materials dumped at the second target position105. The second target data is changed according to work of the second work machine3. As illustrated inFIG.12, the second target data includes the coordinates of a plurality of target points111to115that are preset and second target orientations121to125at the respective target points111to115. The plurality of target points111to115are disposed apart from each other at a predetermined interval in the second work area102. The controller48determines, as the second target position105, a target point designated by the controller53of the second work machine3among the plurality of target points111to115. Alternatively, the controller48may determine, as the second target position105, a target point among the plurality of target points111to115in order.

In step S106, the controller48determines the second dynamic path63. As illustrated inFIG.13, the controller48determines, as the second dynamic path63, a route that connects the second endpoint P2and the second target position105. The controller48determines the second dynamic path63according to the second target orientation106of the transport vehicle1.

In step S107, the controller48controls the transport vehicle1. The controller48controls the transport vehicle1so that the transport vehicle1travels according to the above-mentioned first dynamic path62, the static path61, and the second dynamic path63. After the static path61is determined, the controller48may control the transport vehicle1so that the transport vehicle1starts traveling even before determining the first dynamic path62or the second dynamic path63.FIG.14illustrates the transport vehicle1when moving from the first work area101to the second work area102. As illustrated inFIG.14, after loaded with the materials at the first target position103, the transport vehicle1moves from the first target position103through the first dynamic path62and the static path61to the second endpoint P2. During this time, the transport vehicle1travels on the static path61toward the second work area102with the second traveling body portion16facing front.

The controller48determines whether an entry into the second dynamic path63is allowed at the second endpoint P2. For example, when the second target data is appropriately acquired from the second work machine3, the controller48determines that the entry into the second dynamic path63is allowed. When the second target data is not appropriately acquired from the second work machine3, the controller48determines that the entry into the second dynamic path63is not allowed. When the controller48determines that the entry into the second dynamic path63is not allowed, the controller48causes the transport vehicle1to wait on standby at the second endpoint P2until the second target data is appropriately acquired from the second work machine3.

The controller48may determine whether the entry into the second dynamic path63is allowed at a position other than the second endpoint P2. For example, the controller48may determine whether the entry into the second dynamic path63is allowed at the first target position103. Alternatively, the controller48may determine whether the entry into the second dynamic path63is allowed while the transport vehicle1travels on the first dynamic path62or the static path61.

When the second target data is appropriately acquired from the second work machine3, the controller48causes the transport vehicle1to travel according to the second dynamic path63and stop at the second target position105as illustrated inFIG.15. At this time, the controller48causes the transport vehicle1to arrive at the second target position105with the second traveling body portion16facing front. The controller48rotates the vehicle body10with respect to the traveling body11to switch between the front part and the rear part of the vehicle body10. Then, the controller48switches the bed12to the dumping posture, whereby the materials are dumped from the bed12.

FIG.16illustrates the transport vehicle1when moving from the second work area102to the first work area101. As illustrated inFIG.16, when the transport vehicle1moves away from the second target position105, the transport vehicle1travels with the first traveling body portion15facing front. As illustrated inFIG.16, after dumping the materials at the second target position105, the transport vehicle1moves from the second target position105through the second dynamic path63and the static path61to the first endpoint P1. During this time, the transport vehicle1travels on the static path61toward the first work area101with the first traveling body portion15facing front.

In the example illustrated inFIG.16, the controller48determines the static path61for the return route that is different from the one for the approach route. For example, the controller48determines the second route65as the static path61for the return route. In this case, the controller48determines, as the second dynamic path63, a route that connects the second endpoint P2of the second route65and the second target position105.

The controller48determines whether an entry into the first dynamic path62is allowed at the first endpoint P1. For example, when the first target data is appropriately acquired from the first work machine2, the controller48determines that the entry into the first work area101is allowed. When the first target data is not appropriately acquired from the first work machine2, the controller48determines that the entry into the first work area101is not allowed. When the controller48determines that the entry into the first work area101is not allowed, the controller48causes the transport vehicle1to wait on standby at the first endpoint P1until the first target data is appropriately acquired from the first work machine2.

The controller48may determine whether the entry into the first dynamic path62is allowed at a position other than the first endpoint P1. For example, the controller48may determine whether the entry into the first dynamic path62is allowed at the second target position105. Alternatively, the controller48may determine whether the entry into the first dynamic path62is allowed while the transport vehicle1travels on the second dynamic path63or the static path61.

When the first target data is appropriately acquired from the first work machine2, the controller48determines, as the first dynamic path62, a route that connects the first endpoint P1and the first target position103as illustrated inFIG.17. At this time, when the first target position103is changed, the controller48determines, as the first dynamic path62, a route that connects the changed first target position103and the first endpoint P1. The controller48causes the transport vehicle1to travel according to the first dynamic path62and stop at the first target position103. At this time, the controller48causes the transport vehicle1to arrive at the first target position103with the first traveling body portion15facing front. The controller48rotates the vehicle body10with respect to the traveling body11to switch the front part and the rear part of the vehicle body10. Then, the first work machine2loads the materials onto the bed12of the transport vehicle1. The controller48repeatedly executes the above processes.

In the control system of the transport vehicle1according to the present embodiment described above, the first dynamic path62is determined according to the first target position103for work of the first work machine2. The second dynamic path63is determined according to the second target position105for work of the second work machine3. Accordingly, the optimal travel path60of the transport vehicle1can be determined.

Although an embodiment of the present invention has been described so far, the present invention is not limited to the above embodiment and various modifications can be made without departing from the gist of the invention.

The first work machine2is not limited to the hydraulic excavator and may be another machine, such as a wheel loader. The second work machine3is not limited to the bulldozer and may be another machine, such as a motor grader. The configurations of the first work machine2and/or the second work machine3are not limited to those of the above embodiment and may be changed. For example, the first work machine2and/or the second work machine3may be a vehicle driven by an electric motor. The operating cabin25of the first work machine2and/or the operating cabin36of the second work machine3may be omitted. The configurations of the work implements22and32are not limited to those of the above-mentioned embodiment and may be changed. The first work machine2and/or the second work machine3may be manually operated by an operator, instead of the automatic control.

The transport vehicle1may be a vehicle other than the dump truck. The configuration of the transport vehicle1is not limited to that of the above embodiment and may be changed. For example, the transport vehicle1may be a vehicle driven by an electric motor. The traveling body11and/or the bed12may be driven by an electric motor. The bed12of the transport vehicle1may not be rotatable. The traveling body11of the transport vehicle1may include tires instead of the crawler belts14. The power transmission device43is not limited to the HST and may be another type of power transmission device, such as a transmission having a torque converter or a plurality of transmission gears. The operating cabin13of the transport vehicle1may be omitted.

The controller48is not limited to one unit and may be divided into a plurality of controllers. The processes executed by the controller48may be distributed and executed among the plurality of controllers. In that case, a portion of the plurality of controllers48may be disposed outside of the transport vehicle1.

The controller51of the first work machine2and the controller48of the transport vehicle1may communicate with each other via another controller, instead of directly communicating with each other. The controller53of the second work machine3and the controller48of the transport vehicle1may communicate with each other via another controller, instead of directly communicating with each other.

The processes of the automatic control mode executed by the controller48are not limited to those of the above embodiment and may be changed. For example, the processes for causing the transport vehicle1to wait on standby at the first endpoint P1or the second endpoint P2may be omitted. The control for causing the transport vehicle1to wait on standby at the first endpoint P1or the second endpoint P2may be switched on and off. The controller48may determine whether the entry into the first work area101or the second work area102is allowed corresponding to a signal from the input device58.

The number of the routes of the static path61is not limited to three and may be less than three or greater than three. The processes for determining the first target position103may be changed. The processes for determining the second target position105may be changed. For example, the controller53of the second work machine3may determine the second target position105according to the position and orientation of the second work machine3in the same manner as the processes for determining the first target position103. The number of the plurality of target points for the second target position is not limited to five and may be less than five or greater than five.

According to the present disclosure, the optimal target route can be determined.