System for controlling work machine

Abstract

This system is provided with a travel operation device, a sensor, and a controller. The travel operation device outputs a travel command for causing a work machine to travel. The sensor detects the position of the work machine. The controller controls the travel direction of the work machine. The controller sets a target position. The controller acquires the position of the work machine. The controller sets, as a start position, the position of the work machine when the travel command for causing the work machine to travel is received. The controller determines a route passing through the start position and the target position as a target route. The controller controls the travel direction of the work machine so that the work machine travels according to the target route.

Description

System for controlling a work machine

[0001] The present disclosure relates to a system for controlling a work machine.

[0002] Conventionally, there is known technology for automatically controlling a work machine so that it travels according to a predetermined target path. For example, in a work machine control system disclosed in Patent Document 1, multiple slots (target paths) extending parallel to one another are set. Each of the multiple slots includes a start position and an end position. The control system controls the work machine so that the work machine travels according to each of the multiple slots.

[0003] For example, the work machine excavates with the work implement while traveling from a first start position to a first end position according to a first slot. Next, the work machine moves to a second start position of a second slot, and excavates with the work implement while traveling from the second start position to a second end position according to the second slot. By repeating the above operation, the ground is excavated along each slot.

[0004] Patent Publication No. 2020-166303

[0005] Some work performed by work machines involves collecting materials such as soil and sand in one place. For example, at a site where land leveling work is being performed, soil and sand excavated during the land leveling work is loaded into a dump truck by a hydraulic excavator. In this case, in order to efficiently perform the loading work by the hydraulic excavator, it is desirable to collect the excavated soil and sand from around the hydraulic excavator to a predetermined area near the hydraulic excavator. An object of the present disclosure is to enable a work machine to easily collect materials such as soil and sand from around the predetermined area to the predetermined area.

[0006] A system according to a first aspect of the present disclosure is a system for controlling a work machine and includes a travel operation device, a sensor, and a controller. The travel operation device outputs a travel command to cause the work machine to travel. The sensor detects the position of the work machine. The controller controls the travel direction of the work machine. The controller sets a target position. The controller acquires the position of the work machine. The controller sets the position of the work machine when it receives a travel command to cause the work machine to travel as a start position. The controller determines a route that passes through the start position and the target position as a target route. The controller controls the travel direction of the work machine so that the work machine travels according to the target route.

[0007] In the system according to the first aspect, the work machine is moved to a desired position and then a travel command is output, thereby setting the desired position as the start position of the target route. Therefore, the travel direction of the work machine is automatically controlled so that the work machine travels from the desired start position toward the target position along the target route. This makes it easy to collect materials from any start position around the target position to the target position.

[0008] A system according to a second aspect of the present disclosure is a system for controlling a work machine, and includes a sensor and a controller. The sensor detects the position of the work machine. The controller controls the traveling direction of the work machine. The controller sets a target position. The controller acquires the position of the work machine. The controller determines a plurality of target routes including a first target route and a second target route. The first target route passes through the target position. The second target route passes through the target position and extends in a different direction from the first target route. The controller controls the traveling direction of the work machine to travel according to each of the plurality of target routes.

[0009] In the system according to the second aspect, multiple target routes extending from different directions toward the target position are set. Therefore, the travel direction of the work machine is automatically controlled so that the work machine travels along the target routes from different directions toward the target position. This makes it easy to collect material from around the target position to the target position.

[0010] A system according to a third aspect of the present disclosure is a system for controlling a work machine and includes a travel operation device, a sensor, and a controller. The travel operation device outputs a travel command to cause the work machine to travel. The sensor detects the position of the work machine. The controller controls the travel direction of the work machine. The controller sets a target position. The controller acquires the position of the work machine. When the controller receives a travel command to cause the work machine to travel, it controls the travel direction of the work machine so that the work machine heads toward the target position. The controller maintains the target position setting even when the travel command is released.

[0011] In the system according to the third aspect, the direction of travel of the work machine from the desired position to the target position is automatically controlled by outputting a travel command after moving the work machine to the desired position, thereby making it easy to collect material from any position around the target position to the target position.

[0012] According to the present disclosure, materials such as soil and sand can be easily collected from the periphery of a predetermined area into the predetermined area by a work machine.

[0013] FIG. 1 is a side view showing a work machine according to an embodiment. FIG. 2 is a block diagram showing the configuration of the drive system and control system of the work machine. FIG. 3 is a diagram showing an example of work performed by the work machine. FIG. 4 is a flowchart showing the processing of automatic control of the work machine according to the first embodiment. FIG. 5 is a diagram showing the operation of the work machine under automatic control according to the first embodiment. FIG. 6 is a diagram showing the operation of the work machine under automatic control according to the first embodiment. FIG. 7 is a diagram showing the operation of the work machine under automatic control according to the first embodiment. FIG. 8 is a diagram showing the operation of the work machine under automatic control according to the first embodiment. FIG. 9 is a diagram showing the operation of the work machine under automatic control according to the first embodiment. FIG. 10 is a flowchart showing the processing of automatic control of the work machine according to a second embodiment. FIG. 11 is a diagram showing the operation of the work machine under automatic control according to the second embodiment. FIG. 12 is a diagram showing the operation of the work machine under automatic control according to the second embodiment. FIG. 13 is a diagram showing the operation of the work machine under automatic control according to the second embodiment.

[0014] A work machine according to an embodiment will be described below with reference to the drawings. Figure 1 is a side view showing a work machine 1 according to an embodiment. The work machine 1 according to this embodiment is a bulldozer. The work machine 1 comprises a vehicle body 11 and a work implement 12.

[0015] The vehicle body 11 includes a cab 13, an engine compartment 14, and a traveling device 15. A driver's seat (not shown) is disposed in the cab 13. The engine compartment 14 is disposed in front of the cab 13. The traveling device 15 is provided on the lower part of the vehicle body 11. The traveling device 15 includes a pair of left and right tracks 16. Note that only the left track 16 is shown in FIG. 1. The work machine 1 travels by rotating the tracks 16.

[0016] The work implement 12 is attached to the vehicle body 11. The work implement 12 has a lift frame 17, a blade 18, and a lift actuator 19. The lift frame 17 is supported on the vehicle body 11 so as to be rotatable about a lift axis X1. The blade 18 is disposed in front of the vehicle body 11. The blade 18 is supported by the lift frame 17. The lift actuator 19 is connected to the vehicle body 11 and the lift frame 17. Alternatively, the lift actuator 19 may be connected to the vehicle body 11 and the blade 18. The lift actuator 19 is a hydraulic cylinder. The lift frame 17 moves up and down as the lift actuator 19 extends and retracts. The blade 18 moves up and down in accordance with the up and down movement of the lift frame 17.

[0017] Figure 2 is a block diagram showing the configuration of the drive system 2 and control system 3 of the work machine 1. As shown in Figure 2, the drive system 2 includes a drive source 22, a hydraulic pump 23, and a power transmission device 24. The drive source 22 includes, for example, an internal combustion engine. The drive source 22 may also include an electric motor. The hydraulic pump 23 is driven by the drive source 22 and discharges hydraulic oil. The hydraulic oil discharged from the hydraulic pump 23 is supplied to the lift actuator 19. Although Figure 2 shows one hydraulic pump 23, multiple hydraulic pumps may be provided.

[0018] The power transmission device 24 transmits the driving force of the drive source 22 to the traveling device 15. The power transmission device 24 may be, for example, a hydrostatic transmission (HST). Alternatively, the power transmission device 24 may be, for example, a torque converter or a transmission having a plurality of speed change gears.

[0019] The control system 3 includes a controller 26 and a control valve 27. The controller 26 is programmed to control the work machine 1 based on the acquired data. The controller 26 includes a memory device 28 and a processor 29. The processor 29 includes, for example, a CPU. The memory device 28 includes, for example, a memory and an auxiliary memory device. The memory device 28 may be, for example, a RAM or a ROM. The memory device 28 may be, for example, a semiconductor memory or a hard disk. The memory device 28 stores computer instructions that are executable by the processor 29 and are used to control the work machine 1.

[0020] The control valve 27 is a proportional control valve and is controlled by a command signal from the controller 26. The control valve 27 is disposed between a hydraulic actuator such as the lift actuator 19 and the hydraulic pump 23. The control valve 27 controls the flow rate of hydraulic oil supplied from the hydraulic pump 23 to the lift actuator 19. The control valve 27 may be a pressure proportional control valve. Alternatively, the control valve 27 may be an electromagnetic proportional control valve.

[0021] The control system 3 includes a travel operation device 31A, a steering operation device 31B, and a work implement operation device 31C. The travel operation device 31A can be operated by an operator to manually control the forward and reverse travel of the work machine 1. The travel operation device 31A includes, for example, a travel lever. However, the travel operation device 31A may also include other components such as a switch. The travel operation device 31A can be operated from a neutral position N1 to a forward position A1 and a reverse position B1. The travel operation device 31A outputs travel commands to the controller 26 in accordance with operation by the operator.

[0022] The steering operation device 31B can be operated by an operator to manually steer the work machine 1. The steering operation device 31B includes, for example, a steering lever. However, the steering operation device 31B may include other members such as a steering wheel or a switch. The steering operation device 31B can be operated from a neutral position N2 in a right turning direction A2 and a left turning direction B2. The steering operation device 31B outputs a steering command to the controller 26 in accordance with the operation by the operator.

[0023] The work machine operating device 31C can be operated by an operator to manually operate the work machine 12. The work machine operating device 31C includes, for example, a work machine lever. However, the work machine operating device 31C may also include other components such as a switch. The work machine operating device 31C outputs a work command to the controller 26 in response to an operation by the operator. Note that each of the operating devices 31A-33C may be configured using common components.

[0024] In response to a travel command from the travel operation device 31A, the controller 26 controls the drive source 22 and the power transmission device 24 so as to travel the work machine 1. As a result, the work machine 1 travels forward or backward in response to operation of the travel operation device 31A by the operator.

[0025] The controller 26 controls the drive source 22 and the power transmission device 24 to steer the work machine 1 to the left or right in response to a steering command from the steering operation device 31B. For example, the controller 26 turns the work machine 1 to the left or right by using a speed difference between the left and right tracks 16. As a result, the work machine 1 turns to the left or right in response to operation of the steering operation device 31B by the operator.

[0026] The controller 26 controls the control valve 27 in response to a work command from the work machine operating device 31C to operate the work machine 12. As a result, the work machine 12 moves up and down in response to the operation of the work machine operating device 31C by the operator.

[0027] The control system 3 includes an input device 32. The input device 32 includes, for example, a touch panel. However, the input device 32 may also include other devices such as switches. The operator can use the input device 32 to configure settings for automatic control of the work machine 1. Automatic control of the work machine 1 will be described in detail later.

[0028] The control system 3 includes a position sensor 34, a vehicle body sensor 35, and a work equipment sensor 36. The position sensor 34 is attached to the vehicle body 11. The position sensor 34 includes, for example, a sensor using a Global Navigation Satellite System (GNSS). The position sensor 34 detects the position and orientation of the vehicle body 11. The position sensor 34 outputs a detection signal indicating the position and orientation of the vehicle body 11.

[0029] The vehicle body sensor 35 is attached to the vehicle body 11. The vehicle body sensor 35 detects the attitude of the vehicle body 11. For example, the vehicle body sensor 35 detects the pitch angle and roll angle of the vehicle body 11. The work implement sensor 36 is attached to the work implement 12. The work implement sensor 36 detects the attitude of the work implement 12. For example, the work implement sensor 36 detects the pitch angle of the work implement 12.

[0030] The vehicle body sensor 35 and the work machine sensor 36 are each an IMU (Inertial Measurement Unit). However, the work machine sensor 36 is not limited to an IMU and may be another sensor such as an angle sensor or a cylinder stroke sensor. The vehicle body sensor 35 and the work machine sensor 36 each output a detection signal indicating the detected angle.

[0031] The controller 26 receives detection signals from the position sensor 34, the vehicle body sensor 35, and the work machine sensor 36. The controller 26 calculates the position and orientation of the work machine 1 based on the detection signals. The controller 26 performs automatic control, that is, controls the traveling direction of the work machine, based on the position and orientation of the work machine 1. The automatic control of the work machine will be described below.

[0032] As shown in Figure 3, the work machine 1 performs work to collect material such as soil and sand from the periphery of a predetermined target position Pt1 to the target position Pt1. The target position Pt1 is located, for example, near the excavator 100. The controller 26 assists the operator in operating the work machine 1 during this work by automatically controlling the traveling direction of the work machine 1.

[0033] Figure 4 is a flowchart showing the processing for automatic control of the work machine 1 according to the first embodiment. As shown in Figure 4, in step S101, the controller 26 sets a target position Pt1. As shown in Figure 5, the target position Pt1 is set at the work site where the work machine 1 is located. The target position Pt1 is set by the operator operating the input device 32. For example, a map of the work site is displayed on the input device 32, and the controller 26 sets a position on the map touched by the operator as the target position Pt1.

[0034] In step S102, the controller 26 determines whether a forward travel command has been received. The controller 26 determines that a forward travel command has been received when the travel operation device 31A is operated to the forward position A1. If the controller 26 has received a forward travel command, the process proceeds to step S103.

[0035] In step S103, the controller 26 acquires the position of the reference point Pr1. The reference point Pr1 is a predetermined part included in the work machine 1. As shown in Figure 5, the position of the reference point Pr1 is, for example, the center of the cutting edge of the blade 18. The controller 26 calculates the position of the reference point Pr1 based on detection signals received from the position sensor 34, the vehicle body sensor 35, and the work machine sensor 36.

[0036] In step S104, the controller 26 sets a start position Ps1. The controller 26 sets the position of the reference point Pr1 when the forward travel command is received as the start position Ps1. In step S105, the controller 26 determines a target route R1. As shown in FIG. 6 , the controller 26 determines a route that passes through the start position Ps1 and the target position Pt1 as the target route R1.

[0037] In step S106, the controller 26 executes automatic control of the work machine 1. As shown in Fig. 7 , in response to the forward travel command, the controller 26 moves the work machine 1 forward and controls the travel direction of the work machine 1 so that the work machine 1 travels along the target route R1. In other words, the controller 26 steers the work machine 1 so that the work machine 1 travels along the target route R1 toward the target position Pt1. In particular, the controller 26 turns the work machine 1 so that the reference point Pr1 travels along the target route R1 toward the target position Pt1. As a result, the work machine 1 moves forward while turning toward the target position Pt1 by simply operating the travel operation device 31A, without the operator having to operate the steering operation device 31B.

[0038] In step S107, the controller 26 determines whether the forward travel command has been released. The controller 26 determines that the forward travel command has been released when the travel operation device 31A is operated to the neutral position N1 or the reverse position B1. For example, as shown in FIG. 8 , after the work machine 1 reaches the target position Pt1, the operator switches the travel operation device 31A from the forward position A1 to the reverse position B1. This causes the controller 26 to move the work machine 1 in reverse and determines that the forward travel command has been released. If the forward travel command has been released, the process proceeds to step S108.

[0039] In step S108, the controller 26 stops the automatic control. This allows the operator to manually control the traveling direction of the work machine 1. For example, as shown in Fig. 9, the operator manually operates the traveling operation device 31A and the steering operation device 31B to move the work machine 1 to a position deviating from the target route R1. Note that if the operator operates the steering operation device 31B while automatic control is being executed, the controller 26 also stops the automatic control.

[0040] Thereafter, when the operator again operates the travel operating device 31A to the forward position A1, the controller 26 receives the next forward travel command. As a result, as shown in Fig. 10, the controller 26 resets the position of the reference point Pr1 of the work machine 1 when the next forward travel command was received as the next start position Ps2. However, the controller 26 maintains the setting of the target position Pt1. The controller 26 then determines the route that passes through the next start position Ps2 and the target position Pt1 as the next target route R2.

[0041] 11 , in response to the forward travel command, the controller 26 moves the work machine 1 forward and, by automatic control, controls the travel direction of the work machine 1 so that the work machine 1 travels along the target route R2. By repeating the above operation, the work machine 1 collects material such as soil and sand from around the target position Pt1 to the target position Pt1.

[0042] In the automatic control of the work machine 1 according to the first embodiment described above, the work machine 1 is moved to an arbitrary position and then a forward travel command is output, thereby setting the arbitrary position as the start position of the target route. For example, as shown in FIG. 3 , arbitrary positions around the target position Pt1 are set as start positions Ps1-Ps4. Then, target routes R1-R4 leading from the arbitrary start positions Ps1-Ps4 to the target position Pt1 are determined, and the travel direction of the work machine 1 is automatically controlled so that the work machine 1 travels along each of the target routes R1-R4. This makes it easy to collect materials from any of the start positions Ps1-Ps4 around the target position Pt1 to the target position Pt1.

[0043] Next, automatic control of the work machine 1 according to the second embodiment will be described. Fig. 12 is a flowchart showing the processing of automatic control of the work machine 1 according to the second embodiment. As shown in Fig. 12, in step S201, the controller 26 sets a target position Pt1. In step S202, the controller 26 acquires the position of a reference point Pr1 of the work machine 1. As shown in Fig. 13, the target position Pt1 and the reference point Pr1 are the same as in the first embodiment described above.

[0044] In step S203, the controller 26 determines a plurality of target routes R1-R12. As shown in Fig. 14, the plurality of target routes R1-R12 extend radially from the target position Pt1. The plurality of target routes R1-R12 extend at equal angles from the target position Pt1.

[0045] For example, the controller 26 determines a first target route R1 that passes through a reference point Pr1 and a target position Pt1. The number of target routes R1-R12 is also set, and the controller 26 calculates a target angle between the multiple target routes R1-R12 from the number of the multiple target routes R1-R12. The controller 26 determines other target routes R2-12 so that they are spaced apart from the first target route R1 by the target angle, with the target position Pt1 at the center.

[0046] For example, in the example shown in Fig. 14, the multiple target routes R1-R12 include first to twelfth target routes R1-R12. The first to twelfth target routes R1-R12 each pass through the target position Pt1 and extend in different directions. Note that in the example shown in Fig. 14, the number of the multiple target routes R1-R12 is 12. However, the number of the multiple target routes is not limited to 12, and may be less than 12 or more than 12.

[0047] In step S204, the controller 26 determines whether the target route R1 has been selected. The operator selects one target route from the plurality of target routes R1-R12, for example, by operating the input device 32. Here, it is assumed that the first target route R1 has been selected.

[0048] In step S205, the controller 26 determines whether a forward travel command has been received. If a forward travel command has been received, the controller 26 executes automatic control in step S206. As a result, as shown in Fig. 15 , the controller 26 moves the work machine 1 forward and controls the travel direction of the work machine 1 so that it travels along the first target route R1 selected by the input device 32.

[0049] In step S207, the controller 26 determines whether the forward travel command has been released, as in the first embodiment. If the forward travel command has been released, in step S208, the controller 26 stops the automatic control, as in the first embodiment.

[0050] Next, when the operator selects the next target route, in steps S204 to S206, the controller 26 moves the work machine 1 forward and controls the traveling direction of the work machine 1 so that it travels along the next target route selected by the input device 32. By repeating the above operations, the work machine 1 collects material such as soil and sand from around the target position Pt1 to the target position Pt1.

[0051] In the automatic control of the work machine 1 according to the second embodiment described above, multiple target routes R1-R12 are set, each extending from a different direction toward the target position Pt1. Therefore, the travel direction of the work machine 1 is automatically controlled so that the work machine 1 travels along the target route R1 toward the target position Pt1 from a different direction. This makes it easy to collect material from around the target position Pt1 at the target position Pt1.

[0052] Next, automatic control of the work machine 1 according to the third embodiment will be described. Figure 16 is a flowchart showing the processing of automatic control of the work machine 1 according to the third embodiment. As shown in Figure 16, in step S301, the controller 26 sets a target position Pt1. In step S302, the controller 26 determines whether a forward travel command has been received. In step S303, the controller 26 acquires the position of a reference point Pr1. Steps S301 to S303 are the same as steps S101 to S103 in the first embodiment. As shown in Figure 17, the target position Pt1 and the reference point Pr1 are the same as in the first embodiment described above.

[0053] In step S304, the controller 26 executes automatic control. The controller 26 controls the traveling direction of the work machine 1 so that the work machine 1 heads toward the target position Pt1. In detail, as shown in Fig. 18 , the controller 26 controls the traveling direction of the work machine 1 so that the reference point Pr1 of the work machine 1 heads toward the target position Pt1. Note that in the automatic control according to the third embodiment, the controller 26 does not set a target route R1, but rather controls the traveling direction of the work machine 1 so that the work machine 1 heads toward the target position Pt1.

[0054] In step S305, the controller 26 determines whether the forward travel command has been released. If the forward travel command has been released, the controller 26 stops the automatic control in step S306. Steps S305 and S306 are the same as steps S107 and S108 in the first embodiment.

[0055] For example, after the work machine 1 reaches the target position Pt1, the operator manually operates the travel operation device 31A and the steering operation device 31B to move the work machine 1 to a position different from the position where the previous forward travel command was received. At this time, the controller 26 maintains the setting of the target position Pt1 even if the travel direction of the work machine 1 is changed in accordance with the steering operation device 31B.

[0056] Thereafter, when the operator again operates the travel operating device 31A to the forward position A1, the controller 26 receives the next forward travel command. As a result, the controller 26 controls the travel direction of the work machine 1 so that the work machine 1 again moves toward the target position Pt1 from the position of the work machine 1 when the next forward travel command was received. By repeating the above operation, the work machine 1 collects material such as soil and sand from around the target position Pt1 to the target position Pt1.

[0057] In the automatic control of the work machine 1 according to the third embodiment described above, the work machine 1 is moved to an arbitrary position and then a forward travel command is output, thereby automatically controlling the travel direction of the work machine 1 from the arbitrary position toward the target position Pt1. This makes it easy to gather material from any position around the target position Pt1 to the target position Pt1.

[0058] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention.

[0059] The work machine 1 is not limited to a bulldozer, but may be other vehicles such as a wheel loader or motor grader. The work machine 1 may be operable remotely. In that case, the operation devices 31A-31C and the input device 32 may be located outside the work machine 1. The work machine 1 may have multiple controllers that are separate from each other. The processing by the controller 26 described above may be distributed and executed by multiple controllers.

[0060] The automatic control processing by the controller 26 is not limited to that of the above embodiment and may be modified. The method of setting the target position Pt1 is not limited to that of the above embodiment and may be modified. For example, the controller 26 may acquire the target position Pt1 from the excavator 100. The controller 26 may determine the target position Pt1 from the previous work history. For example, the controller 26 may determine, as the target position Ot1, the position of the work machine 1 when the travel operating device 31A was switched from the forward position A1 to the reverse position B1 during the previous work.

[0061] The reference point Pr1 is not limited to the center of the cutting edge of the blade 18, and may be located at another position. For example, the reference point Pr1 may be provided on the vehicle body 11. The reference point Pr1 may also be the center of rotation of the work machine 1.

[0062] In the second embodiment, the multiple target routes R1-R12 do not have to be arranged at equal intervals. The method for setting the first target route R1 is not limited to that in the second embodiment described above and may be changed. For example, the first target route R1 may be set by an operator operating the input device 32. In the second embodiment, the controller 26 may start automatic control when the target route R1 is selected. Alternatively, the controller 26 may start automatic control when the operator operates the input device 32 after the target route R1 is selected.

[0063] According to the present disclosure, materials such as soil and sand can be easily collected from the periphery of a predetermined area into the predetermined area by a work machine.

[0064] 1: Work machine 26: Controller 31A: Travel operation device 31B: Steering operation device 32: Input device 34: Position sensor

Claims

1. A system for controlling a work machine comprising: a travel operation device that outputs a travel command to cause the work machine to travel; a sensor that detects the position of the work machine; and a controller that controls the travel direction of the work machine, wherein the controller sets a target position; acquires the position of the work machine; sets the position of the work machine when a travel command to cause the work machine to travel is received as a start position; determines a route that passes through the start position and the target position as the target route; and controls the travel direction of the work machine so that the work machine travels according to the target route.

2. The system according to claim 1, wherein the controller maintains the setting of the target position even when the travel command is released.

3. The system described in claim 1, wherein, when a next travel command is received after the previous travel command is released, the controller resets the position of the work machine when the next travel command was received as the next start position, and determines a path passing through the next start position and the target position as the next target path.

4. The system described in claim 3, wherein the driving operation device can be manually operated from a neutral position to a forward position and a reverse position, and the controller sets the position of the work machine at the time the driving command is received by operating the driving operation device to the forward position as a start position of the target route, and determines that the driving command has been released when the driving operation device is operated to the neutral position or the reverse position.

5. A system as described in claim 1, further comprising a steering operation device operable to manually steer the work machine, wherein the controller maintains the setting of the target position even if the work machine moves to a position deviating from the previous target route in response to operation of the steering operation device after the previous travel command is released, and when a next travel command is received, resets the position of the work machine at the time the next travel command was received as the next start position, and determines a route passing through the next start position and the target position as the next target route.

6. A system for controlling a work machine, comprising: a sensor that detects a position of the work machine; and a controller that controls a traveling direction of the work machine, wherein the controller sets a target position, acquires the position of the work machine, determines a plurality of target routes including a first target route that passes through the target position and a second target route that passes through the target position and extends in a different direction from the first target route, and controls the traveling direction of the work machine to travel according to each of the plurality of target routes.

7. The system according to claim 6, wherein the controller determines the plurality of target paths so as to extend radially from the target position.

8. The system according to claim 6, wherein the controller determines the plurality of target paths so as to extend equiangularly around the target position.

9. The system according to claim 6, further comprising an input device operable by an operator, wherein the controller controls the travel direction of the work machine so as to travel according to a target route selected by the input device from among the plurality of target routes.

10. A system for controlling a work machine, comprising: a travel operation device that outputs a travel command to cause the work machine to travel; a sensor that detects the position of the work machine; and a controller that controls the travel direction of the work machine, wherein the controller sets a target position, acquires the position of the work machine, and, when a travel command to cause the work machine to travel is received, controls the travel direction of the work machine so that the work machine heads toward the target position, and maintains the setting of the target position even when the travel command is released.

11. The system according to claim 10, wherein the controller, when receiving a next travel command after the previous travel command is released, controls the travel direction of the work machine so that the work machine again heads toward the target position.

12. The system described in claim 11, wherein the travel operation device can be manually operated from a neutral position to a forward position and a reverse position, and the controller, when the travel command is received by operating the travel operation device to the forward position, controls the travel direction of the work machine so that the work machine heads toward the target position, and when the travel operation device is operated to the neutral position or the reverse position, determines that the travel command has been released.

13. A system as described in claim 10, further comprising a steering operation device operable to manually steer the work machine, wherein the controller maintains the setting of the target position even if the travel direction of the work machine is changed in response to the steering operation device after the previous travel command is released, and when a next travel command is received, controls the travel direction of the work machine so that the work machine again heads toward the target position.

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