Control system for work machine, control method for work machine, and work machine

Abstract

Provided is a control system for a work machine, the system capable of improving the work efficiency of the work machine while preventing the work machine from falling off a cliff or the like. A control system for a work machine according to the present disclosure comprises a processor that acquires terrain information in a traveling direction of a work machine and controls the work machine on the basis of the terrain information. The processor controls the travel of the work machine on the basis of the position of an excavation unit of the work machine and the apex position of the ground surface present within a prescribed distance in the traveling direction of the work machine.

Description

Control system for work machine, control method for work machine, and work machine

[0001] The present disclosure relates to a control system for a work machine, a control method for a work machine, and a work machine.

[0002] For example, a work machine such as a bulldozer may perform work around a cliff. In the control of such a work machine, if the presence of a cliff is overlooked, there is a risk that the work machine may fall off the cliff.

[0003] Conventionally, for example, Patent Document 1 discloses a control system for a work machine that detects cliffs around the work machine using a sensor such as LiDAR (Light Detection And Ranging) mounted on the work machine, and prevents the work machine from falling off the cliff. A control system that detects cliffs using such a sensor can also be used when remotely operating a work machine such as a bulldozer, or when automatically operating a work machine.

[0004] Japanese Patent Application Laid-Open No. 2024-52161

[0005] By the way, the control system described in Patent Document 1 and the like has room for improvement in terms of the working efficiency of the work machine.

[0006] The present disclosure has been made in consideration of the above points, and provides a control system for a work machine, a control method for a work machine, and a work machine that can improve the working efficiency of the work machine while suppressing the fall of the work machine from a cliff or the like.

[0007] One aspect of the control system for a work machine according to the present disclosure includes a processor that acquires terrain information in the traveling direction of the work machine and controls the work machine based on the terrain information, wherein the processor controls traveling of the work machine based on a top position of a ground surface existing within a predetermined distance in the traveling direction of the work machine and a position of an excavation unit of the work machine.

[0008] One aspect of the control method for a work machine according to the present disclosure includes: acquiring terrain information in a traveling direction of the work machine; and controlling traveling of the work machine based on a top position of a ground surface existing within a predetermined distance in the traveling direction of the work machine and a position of an excavation unit of the work machine.

[0009] One embodiment of the work machine of the present disclosure comprises an excavation unit and a processor that acquires terrain information in the direction of travel and controls the work machine based on the terrain information, wherein the processor controls travel based on the position of the top of the ground surface located within a predetermined distance in the direction of travel and the position of the excavation unit.

[0010] According to this disclosure, it is possible to improve the work efficiency of work machinery while suppressing the risk of it falling from cliffs or other obstacles.

[0011] Side view of a bulldozer Top view of a bulldozer Block diagram showing the main components of the bulldozer in the embodiment Diagram showing the communication between the management device and the bulldozer Diagram showing the multiple measurement points measured by the distance measuring sensor Diagram showing the measurement points mapped to the grid of the site coordinate system Diagram for explaining a cliff Diagram for explaining a cliff Diagram showing how the bulldozer stops before a cliff by braking control Diagram showing the case when the height of the apex is higher than the cutting edge of the lower end of the excavation blade Diagram showing the case when the height of the apex is not higher than the cutting edge of the lower end of the excavation blade Flowchart for realizing the travel control of the embodiment

[0012] The embodiments of this disclosure will be described in detail below with reference to the drawings.

[0013] In this embodiment, we will describe an example in which the control system for work machinery of this disclosure is applied to a bulldozer used for work in a mine.

[0014] <1> The schematic configuration of the bulldozer 100 of this embodiment will be explained using schematic diagrams 1 and 2 of the bulldozer. Figure 1 is a side view of the bulldozer 100, and Figure 2 is a top view of the bulldozer 100.

[0015] The bulldozer 100 includes a body 110, a running gear 120, an excavation device 130, and a ripper device 140. The excavation device 130 is located on the front side of the body 110, and the ripper device 140 is located on the rear side of the body 110.

[0016] Furthermore, the bulldozer 100 has distance sensors 151 and 152, a position sensor 153, and attitude sensors 154 and 155. In this embodiment, the distance sensors 151 and 152 are LiDARs, the position sensor 153 is a GNSS (Global Navigation Satellite System), and the attitude sensors 154 and 155 are inertial measurement devices such as IMUs (Inertial Measurement Units).

[0017] Distance measuring sensors 151 and 152 are mounted on top of the bulldozer 100. Distance measuring sensor 151 measures the distance in front of the bulldozer 100, and distance measuring sensor 152 measures the distance behind the bulldozer 100.

[0018] The distance measuring sensors 151 and 152 detect the distance to the surface of an object by reflection from the object around the travel area of ​​the bulldozer 100. As can be seen in the figures, the distance measuring sensors 151 and 152 are capable of detection at predetermined angles α1 and α2 in the vertical direction (Figure 1), and are also capable of detection at predetermined angles β1 and β2 in the horizontal direction (Figure 2).

[0019] The position sensor 153 can detect the position of the bulldozer 100 in the global coordinate system.

[0020] The attitude sensor 154 is attached to the vehicle body and can detect the inclination angle of the vehicle body 110 with respect to the horizontal plane. The attitude sensor 155 is attached to the drilling blade 131 of the drilling device 130 and can detect the displacement of the drilling blade 131 from its reference position.

[0021] Furthermore, the bulldozer 100 may have other sensors, such as radar, for detecting obstacles.

[0022] Figure 3 is a block diagram showing the main components of the bulldozer 100 in the embodiment.

[0023] A control unit 200 is provided on the body 110 of the bulldozer 100. The control unit 200 mainly includes a CPU (Central Processing Unit) 201, RAM (Random Access Memory) 202, ROM (Read Only Memory) 203, etc. The CPU 201 reads a program corresponding to the processing content from the ROM 203, loads it into the RAM 202, and works in cooperation with the loaded program to centrally control the operation of each element of the bulldozer 100.

[0024] Furthermore, the control unit 200 is provided with an auxiliary storage memory 204, and calculation results obtained by the CPU 201 are stored in the auxiliary storage memory 204.

[0025] Furthermore, all or part of the control unit 200 may be formed using hardwired circuits such as ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array).

[0026] The control unit 200 receives measurement data from distance sensors 151 and 152, position sensor 153, and attitude sensors 154 and 155. The control unit 200 controls the traveling device 120, the excavating device 130, and the ripper device 140. The control unit 200 controls the display unit 111 located in the driver's seat of the vehicle body 110. The control unit 200 receives operation signals from the operation unit 112 located in the driver's seat of the vehicle body 110.

[0027] Furthermore, the control unit 200 controls the alarm device 113. The control unit 200 wirelessly transmits predetermined information to the management device 300 via the communication unit 114. The control unit 200 wirelessly receives predetermined information from the management device 300 via the communication unit 114. For example, the control unit 200 wirelessly receives topographic information (generally called a topographic map), including ground height information and cliff location information, from the management device 300.

[0028] Furthermore, the control unit 200 outputs an alarm from the alarm device 113 when the bulldozer 100 approaches a cliff.

[0029] Figure 4 shows the communication between the control device 300 and the bulldozer 100. In mines and other similar environments, the control device 300 installed in the control facility is connected to multiple bulldozers 100-1 to 100-n via a communication network 400. This allows information obtained from multiple bulldozers 100-1 to 100-n to be aggregated in the control device 300. The control device 300 can also transmit topographic information, including ground height information and cliff location information, to the multiple bulldozers 100-1 to 100-n. Furthermore, the control device 300 can remotely control the multiple bulldozers 100-1 to 100-n by transmitting control signals to them.

[0030] In this embodiment, terrain information acquired by each bulldozer 100-1 to 100-n is transmitted to the management device 300. This allows terrain information acquired by one bulldozer 100 to be shared among the other bulldozers 100. Furthermore, the management device 300 can also control the multiple bulldozers 100-1 to 100-n to prevent them from falling off a cliff, based on the terrain information acquired by the multiple bulldozers 100-1 to 100-n, as well as the attitude information of the bulldozers 100-1 to 100-n.

[0031] <2> A brief explanation will be given of general cliff detection using cliff detection distance measuring sensors (LiDAR in this embodiment) 151 and 152.

[0032] Figure 5 shows the arrangement of multiple measurement points (black circles in the figure indicate measurement points) measured by the distance measuring sensor 151. The distance measuring sensor 151 measures the height and direction of the measurement points based on reflected light from the surface of an object such as the ground.

[0033] Figure 6 shows how measurement points are mapped onto a grid in the field coordinate system. By mapping multiple measurement points onto a grid in the field coordinate system, a contour map (a diagram of contour lines) can be created.

[0034] A cliff is determined to be either (i) a point (measurement point) P1 where the ground surface cannot be detected beyond that point, as shown in Figure 7, or (ii) a point (measurement point) P2 where the subsequent downward slope is steeper than a predetermined angle, as shown in Figure 8.

[0035] <3> In general, the automatic driving control of the bulldozer 100 in this embodiment involves braking control to stop the bulldozer 100 before it reaches the cliff when it detects a cliff in the direction of travel, as shown in Figure 9. This prevents the bulldozer from falling off the cliff.

[0036] However, as can be seen from Figure 9, cliff detection sometimes identifies piles of soil, such as loose earth, as cliffs. In this case, even if the bulldozer 100 tries to cut away the soil for leveling purposes, it will be braked before reaching the peak P0, resulting in the inconvenience of not being able to cut away the soil. As a result, the work efficiency of the bulldozer 100 will decrease.

[0037] This disclosure presents a technology that can suppress the decline in work efficiency even under such circumstances.

[0038] Figures 10 and 11 are diagrams used to explain the driving control according to this embodiment.

[0039] The CPU 201 of the bulldozer 100 controls the movement of the bulldozer 100 based on the position of the top P0 of the ground surface that is within a predetermined distance in the direction of travel of the bulldozer 100, and the position of the excavation blade 131 of the bulldozer 100.

[0040] Let me explain in more detail. The CPU 201 calculates the difference h1 between the height of the apex P0 and the height of the cutting edge at the lower end of the drilling blade 131. Then, as shown in Figure 10, if the difference h1 is greater than or equal to a predetermined value, in other words, if the height of the apex P0 is greater than or equal to the cutting edge at the lower end of the drilling blade 131 by a threshold, the CPU 201 suppresses braking control for the bulldozer 100 (specifically, it suppresses stopping control).

[0041] In contrast, as shown in FIG. 11, when the difference h1 is less than a predetermined value, in other words, when the height of the vertex P0 is not higher than the cutting edge of the lower end of the excavation blade 131 by more than a threshold value, the CPU 201 performs braking control on the bulldozer 100 (specifically, stops the bulldozer 100).

[0042] By doing so, it is possible to continue the leveling work of the earth mound in the situation as shown in FIG. 10 without stopping while suppressing falling from a cliff in the situation as shown in FIG. 11. As a result, a decrease in work efficiency can be suppressed while preventing falling from a cliff.

[0043] Next, the travel control of the present embodiment will be described more specifically. The travel control of the present embodiment can be realized by the CPU 201 of the control unit 200 executing processing as shown in, for example, the flowchart of FIG. 12.

[0044] In step S1, the CPU 201 acquires terrain information. This terrain information may be, for example, information of measurement points measured by the distance measuring sensor 151, or may be a terrain map including height information input from the management device 300 via the communication unit 114.

[0045] In the subsequent step S2, the CPU 201 detects a cliff within a predetermined distance based on the terrain information, and calculates the height of the vertex P0 thereof. At this time, as shown in FIGS. 10 and 11, for example, the CPU 201 sets a virtual braking determination frame F1 in the travel direction of the bulldozer 100, and calculates the height of the vertex P0 of the cliff that has entered the braking determination frame F1.

[0046] Incidentally, in the case of the present embodiment, a virtual warning frame F2 may be set in a range farther from the bulldozer 100 than the braking determination frame F1 in the travel direction of the bulldozer 100, and a warning may be output from the warning device 113 when the vertex P0 enters the warning frame.

[0047] In step S3, the CPU 201 calculates the height of the excavation blade 131 (preferably the height of the cutting edge at the lower end of the excavation blade 131). The height of the excavation blade 131 can be calculated using, for example, GNSS data from the position sensor 153 and IMU data from the attitude sensors 154 and 155. Alternatively, the height of the excavation blade 131 can be calculated based on, for example, the stroke length of the cylinder of the excavating device 130.

[0048] In step S4, the CPU 201 determines whether or not the difference between the height of the cliff vertex P0 calculated in step S2 and the height of the cutting edge of the excavation blade 131 calculated in step S3 is greater than or equal to a threshold value.

[0049] When the CPU 201 obtains a negative result in step S4 (step S4: NO), this means that the relationship between the bulldozer 100 and the terrain is as shown in FIG. 11, and the CPU 201 proceeds to step S5 to perform braking control (that is, controls the traveling device to stop the traveling of the bulldozer 100).

[0050] In contrast, when the CPU 201 obtains a positive result in step S4 (step S4: YES), this means that the relationship between the bulldozer 100 and the terrain is as shown in FIG. 10, and the CPU 201 proceeds to step S6 and does not perform braking control (that is, allows the bulldozer 100 to continue traveling without stopping control). After the processing of step S6, the CPU 201 returns to the processing of step S1.

[0051] As described above, the control system for a work machine according to the embodiment acquires terrain information in the traveling direction of a work machine (the bulldozer 100 in the embodiment), and includes a processor (CPU 201) that controls the work machine based on the terrain information. The processor controls traveling of the work machine based on: a vertex P0 position (top position) of the ground surface existing within a predetermined distance in the traveling direction of the work machine, and a position of an excavation part of the work machine (a position of the cutting edge at the lower end of the excavation blade 131 in the embodiment).

[0052] This makes it possible to improve the working efficiency of the work machine while suppressing falling of the work machine from cliffs or the like.

[0053] <4> Other Embodiments The embodiments described above are merely examples of how the present invention can be implemented, and the technical scope of the present invention should not be interpreted as being limited by them. That is, the present invention can be implemented in various forms without departing from its gist or its main features.

[0054] In the above-described embodiment, we described a case where LiDAR was used as the distance measuring sensors 151 and 152 for obtaining terrain information, but this sensor is not limited to LiDAR. For example, a stereo camera or an RGB-D camera can be used as this sensor.

[0055] The above-described embodiment mentions the case where self-position estimation is performed using GNSS, but is not limited to this. Self-position estimation may be achieved using, for example, a positioning system such as GNSS and an IMU. Alternatively, self-position estimation may be achieved by performing SLAM (Simultaneous Localization And Mapping) processing using information obtained from sensors such as LiDAR or stereo cameras.

[0056] In the above-described embodiment, the CPU 201 calculates the difference between the height of the highest point P0 on the ground surface located within a predetermined distance in the direction of travel of the bulldozer 100 and the height of the excavation section of the bulldozer 100, and controls the movement of the bulldozer 100 based on this height difference. However, the embodiment is not limited to this.

[0057] For example, the CPU 201 may set a virtual braking determination frame F1 (Figures 10 and 11) in the direction of travel of the bulldozer 100, and if the apex P0 is within the braking determination frame F1 and the position of the excavation blade 131 is at the excavation position (in other words, the position where it is embedded in the soil), braking control may be suppressed. In other words, even if the apex P0 of a cliff is detected nearby, the travel stop control is suppressed while the excavation blade 131 is excavating (while the excavation blade 131 is holding soil). The same effects as in the above-described embodiment can be obtained by doing this as well.

[0058] In the above-described embodiment, the movement of the bulldozer 100 was controlled based on the difference between the height of the top of the ground surface P0 and the height of the cutting edge of the excavation blade 131. However, control may be performed based on the height of other positions in the excavation section, not just the cutting edge of the excavation blade 131. Furthermore, the position of the top of the ground surface does not need to be exactly the same as the top of the ground surface P0, but includes positions near the top of the ground surface P0 (i.e., the summit position).

[0059] In the above-described embodiment, the process shown in Figure 12 was described in the case where it is performed by the work machine (bulldozer 100), but it is not limited to this. For example, the process shown in Figure 12 may be performed by the control device 300, or it may be performed in a distributed manner between the work machine (bulldozer 100) and the control device 300.

[0060] In the embodiments described above, the present invention was applied to a bulldozer. However, the work machine to which the present invention is applied is not limited to a bulldozer. It may also be applied to other work machines having an excavation section, such as a wheel loader or a motor grader.

[0061] All disclosures in the specification, drawings, and abstract contained in the Japanese application No. 2025-048659, filed on March 24, 2025, are incorporated herein by reference.

[0062] This disclosure can be applied, for example, to the automatic driving control of a bulldozer.

[0063] 10, 100 Bulldozer 110 Body 120 Running gear 113 Warning device 120 Running gear 130 Excavation device 140 Ripper device 151, 152 Distance sensor 153 Position sensor 154, 155 Attitude sensor 200 Control unit 201 CPU 300 Management device 400 Communication network

Claims

1. A control system for a work machine, comprising a processor that acquires terrain information in the direction of travel of the work machine and controls the work machine based on the terrain information, wherein the processor controls the movement of the work machine based on the position of the top of the ground surface located within a predetermined distance in the direction of travel of the work machine and the position of the excavation section of the work machine.

2. The control system for a work machine according to claim 1, wherein the processor performs a calculation process to calculate the difference between the height of the top of the ground surface located within a predetermined distance in the direction of travel of the work machine and the height of the excavation section of the work machine, and a travel control process to control the travel of the work machine based on the height difference.

3. The control system for a work machine according to claim 2, wherein the processor further performs cliff determination based on the terrain information, and in the calculation process calculates the difference between the height of the top of a cliff located in the direction of travel of the work machine and the height of the excavation section of the work machine.

4. The control system for a work machine according to claim 2, wherein in the travel control process, braking control to the work machine is suppressed when the height of the top is higher than or equal to a threshold than the height of the excavation section.

5. The control system for a work machine according to claim 2, wherein the processor sets a virtual braking determination frame in the direction of travel of the work machine, and executes the calculation process and the travel control process when the top is within the braking determination frame.

6. The control system for a work machine according to claim 5, wherein the processor further sets a virtual alarm frame in a range further away from the work machine than the braking determination frame in the direction of travel of the work machine, and performs alarm output control when the top enters the alarm frame.

7. The control system for a work machine according to claim 1, wherein the processor sets a virtual braking determination frame in the direction of travel of the work machine, and suppresses braking control when the top of a cliff is within the braking determination frame and the position of the excavation section is at the excavation position.

8. The control system for a work machine according to claim 1, wherein the work machine is a bulldozer.

9. The control system for a work machine according to claim 2, wherein the work machine is a bulldozer, and the calculation process calculates the difference between the height of the top of a cliff located in the direction of travel of the bulldozer and the height of the cutting edge of the bulldozer's digging blade.

10. A method for controlling a work machine, which involves acquiring terrain information in the direction of travel of the work machine, and controlling the movement of the work machine based on the position of the top of the ground surface located within a predetermined distance in the direction of travel of the work machine and the position of the excavation section of the work machine.

11. A method for controlling a work machine according to claim 10, comprising: a calculation process for calculating the difference between the height of the top of the ground surface located within a predetermined distance in the direction of travel of the work machine and the height of the excavation section of the work machine; and a travel control process for controlling the travel of the work machine based on the height difference.

12. A method for controlling a work machine according to claim 11, further comprising a process for determining a cliff based on the terrain information, wherein the calculation process calculates the difference between the height of the top of a cliff located in the direction of travel of the work machine and the height of the excavation section of the work machine.

13. The method for controlling a work machine according to claim 11, wherein in the travel control process, braking control to the work machine is suppressed when the height of the top is higher than or equal to a threshold than the height of the excavation section.

14. A method for controlling a work machine according to claim 11, wherein a virtual braking determination frame is set in the direction of travel of the work machine, and the calculation process and the travel control process are performed when the top of the machine is within the braking determination frame.

15. The method for controlling a work machine according to claim 14, further comprising setting a virtual alarm frame in a range further from the work machine than the braking determination frame in the direction of travel of the work machine, and outputting an alarm when the top of the alarm frame enters the alarm frame.

16. A control method for a work machine according to claim 11, wherein a virtual braking determination frame is set in the direction of travel of the work machine, and braking control is suppressed when the top portion is within the braking determination frame and the position of the excavation portion is at the excavation position.

17. The method for controlling a work machine according to claim 11, wherein the work machine is a bulldozer.

18. The method for controlling a work machine according to claim 17, wherein the calculation process calculates the difference between the height of the top of a cliff located in the direction of travel of the bulldozer and the height of the cutting edge of the bulldozer's excavation blade.

19. A work machine comprising an excavation section and a processor that acquires terrain information in the direction of travel and controls the work machine based on the terrain information, wherein the processor controls travel based on the position of the top of the ground surface located within a predetermined distance in the direction of travel and the position of the excavation section.

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