WORK STATE ESTIMATION SYSTEM FOR WORK MACHINE, AND WORK STATE ESTIMATION METHOD FOR WORK MACHINE

Description

TECHNICAL FIELD

The present disclosure relates to a state of a work machine and, more particularly, to a technique for estimating a work state.

Background Art

In the related art, various methods are proposed for estimating a work state of a work machine on the basis of results from various sensors provided in relation to the work state (refer to Patent Documents 1 to 4).

CITATION LIST

Patent Literature

• • Patent Document 1: JP 2020-71742 A
  • Patent Document 2: JP 2021-21245 A
  • Patent Document 3: JP 2021-22179 A
  • Patent Document 4: JP 2021-55360 A

SUMMARY OF INVENTION

Technical Problem

On the other hand, the methods described above are complicated and have room for improvement in terms of estimating the work state.

An object of the disclosure is to provide a work state estimation system for a work machine and a work state estimation method for a work machine that are capable of estimating a work state of a work machine by a simple method.

Solution to Problem

A work state estimation system for a work machine based on an aspect of the disclosure includes an inclination angle acquisition unit configured to acquire an inclination angle of a work machine, and a work state estimation unit configured to estimate a work state of the work machine on the basis of a change in the inclination angle. The inclination angle includes at least a pitch angle.

A work state estimation method for a work machine based on an aspect of the disclosure includes acquiring an inclination angle of a work machine, and estimating a work state of the work machine on the basis of a change in the inclination angle. The inclination angle includes at least a pitch angle.

Advantageous Effects of Invention

A work state estimation system for a work machine and a work state estimation method for a work machine according to the disclosure can estimate a work state of a work machine by a simple method.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an external view of a work machine based on an embodiment.

FIG. 2 is a diagram for explaining an inclination angle detection device 70 according to the embodiment.

FIG. 3 is a diagram for explaining a configuration of a controller 60 of a work machine 100 according to the embodiment.

FIG. 4 is a diagram for explaining a flow of work states of the work machine 100 according to the embodiment.

FIG. 5 is a diagram for explaining estimation of the work state of the work machine 100 according to the embodiment.

FIG. 6 is a table for explaining determination of the work state of the work machine 100 according to the embodiment.

FIG. 7 is a diagram for explaining a flow of estimation processing of the work state of the work machine 100 according to the embodiment.

FIG. 8 is a flowchart for explaining the estimation processing of the work state by a work classification unit 62 according to the embodiment.

FIG. 9 is a flowchart for explaining excavation load determination processing by an excavation load determination unit 160 according to the embodiment.

FIG. 10 is a diagram for explaining a specific example of the excavation load determination processing of the excavation load determination unit 160 according to the embodiment.

FIG. 11 is a diagram for explaining revolving determination processing of a revolving determination unit 162 according to the embodiment.

FIG. 12 is a diagram for explaining load revolving determination processing of the revolving determination unit 162 according to the embodiment.

FIG. 13 is a diagram for explaining unloaded revolving determination processing of the revolving determination unit 162 according to the embodiment.

FIG. 14 is a diagram for explaining a specific example of the load revolving determination processing and the unloaded revolving determination processing of the revolving determination unit 162 according to the embodiment.

FIG. 15 is a diagram for explaining dumping determination processing of a dumping determination unit 164 according to the embodiment.

FIG. 16 is a diagram for explaining a specific example of the dumping determination processing of the dumping determination unit 164 according to the embodiment.

FIG. 17 is a flowchart for explaining excavation load determination processing by the excavation load determination unit 160 according to a first modification of the embodiment.

FIG. 18 is a flowchart for explaining revolving determination by the revolving determination unit 162 according to a second modification of the embodiment.

FIG. 19 is a diagram for explaining a specific example of revolving determination processing by the revolving determination unit 162 according to the second modification of the embodiment.

FIG. 20 is a diagram for explaining a bucket angle during dumping according to the embodiment.

FIG. 21 is a flowchart for explaining the dumping determination processing of the dumping determination unit 164 according to a third modification of the embodiment.

FIG. 22 is a diagram for explaining a specific example of the dumping determination processing of the dumping determination unit 164 according to the third modification of the embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments will be described with reference to the drawings. In the following description, the same components are denoted by the same reference signs. The names and functions of these components are the same. Accordingly, detailed descriptions thereof will not be repeated.

Overall Configuration of Work Machine

FIG. 1 is an external view of a work machine based on an embodiment.

As illustrated in FIG. 1, a hydraulic excavator including a work implement 2 actuated by hydraulic pressure will be described as an example of a work machine applicable to the concept of the disclosure.

A work machine 100 includes a vehicle body 1 and the work implement 2.

The vehicle body 1 includes a revolving body 3, a cab 4, and a traveling device 5.

The revolving body 3 is disposed on the traveling device 5. The traveling device 5 supports the revolving body 3. The revolving body 3 can revolve about a revolving axis AX. The cab 4 is provided with an operator seat 4S on which an operator sits. The operator operates the work machine 100 in the cab 4. The traveling device 5 includes a pair of crawler belts 5Cr. The work machine 100 travels by revolving of the crawler belts 5Cr. The traveling device 5 may be constituted by wheels (tires).

A positional relationship of each part will now be described relative to the operator seated in the operator seat 4S. A front-rear direction refers to a front-rear direction of the operator seated in the operator seat 4S. A left-right direction refers to a left-right direction relative to the operator seated in the operator seat 4S. The left-right direction coincides with a width direction of the vehicle (vehicle width direction). A direction facing the front of the operator seated in the operator seat 4S is defined as a forward direction, and a direction opposite to the forward direction is defined as a rearward direction. When the operator seated in the operator seat 4S faces the front, a right side and a left side are referred to as a right direction and a left direction, respectively.

The revolving body 3 includes an engine room 9 accommodating an engine, and a counterweight provided at a rear portion of the revolving body 3. In the revolving body 3, a handrail 19 is provided in front of the engine room 9. An engine, a hydraulic pump, and the like are disposed in the engine room 9.

The work implement 2 is supported by the revolving body 3. The work implement 2 includes a boom 6, an arm 7, a bucket 8, a boom cylinder 10, an arm cylinder 11, and a bucket cylinder 12.

The boom 6 is connected to the revolving body 3 via a boom pin 13. The arm 7 is connected to the boom 6 via an arm pin 14. The bucket 8 is connected to the arm 7 via a bucket pin 15. The boom cylinder 10 drives the boom 6. The arm cylinder 11 drives the arm 7. The bucket cylinder 12 drives the bucket 8. A proximal end portion (boom foot) of the boom 6 and the revolving body 3 are connected. A distal end portion (boom top) of the boom 6 and a proximal end portion (arm foot) of the arm 7 are connected. A distal end portion (arm top) of the arm 7 and a proximal end portion of the bucket 8 are connected. Each of the boom cylinder 10, the arm cylinder 11, and the bucket cylinder 12 is a hydraulic cylinder driven by hydraulic oil.

The boom 6 can revolve relative to the revolving body 3 about the boom pin 13 serving as a revolving axis. The arm 7 can revolve relative to the boom 6 about the arm pin 14 that is a revolving axis parallel to the boom pin 13. The bucket 8 can revolve relative to the arm 7 about the bucket pin 15 that is a revolving axis parallel to the boom pin 13 and the arm pin 14.

The proximal end portion of the boom 6 is coupled to a revolving frame, and an inclination angle detection device 70, that is, an inertial measurement unit (IMU) sensor as an example herein, is provided at a distal end of the revolving frame.

FIG. 2 is a diagram for explaining the inclination angle detection device 70 according to the embodiment.

As illustrated in FIG. 2, a case is exemplified in which an IMU sensor, which is an example of the inclination angle detection device 70, is mounted onto the distal end of the revolving frame supporting the work implement 2.

The inclination angle detection device 70 is a sensor that detects an inclination angle of the work machine 100 and can detect, as an example, a pitch angle, a roll angle, and a yaw angle. The inclination angle detection device 70 is mounted at a location close to a center in a left-right direction. Based on the mounting location, the inclination angle of the work machine 100 can be accurately detected.

Specifically, the inclination angle detection device 70 detects the pitch angle indicating an inclination angle of the vehicle body 1 about an axis extending in the left-right direction of the work machine 100, the roll angle indicating an inclination angle of the vehicle body 1 about an axis extending in the front-rear direction of the work machine 100, and the yaw angle indicating an inclination angle of the vehicle body 1 about an axis extending in an up-down direction of the work machine 100.

FIG. 3 is a diagram for explaining a configuration of a controller 60 of the work machine 100 according to the embodiment. With reference to FIG. 3, the controller 60 of the work machine 100 includes a calculation unit 61, a storage unit 64, and an output unit 65.

The calculation unit 61 is, for example, a central processing unit (CPU), and executes various calculations. The storage unit 64 stores programs and data for executing various calculation processing executed by the calculation unit 61.

The calculation unit 61 includes a work classification unit 62 and an acquisition unit 63.

The acquisition unit 63 acquires an inclination angle that is a detection result of the inclination angle detection device 70. Note that the data acquired for the detection result may be used after being corrected.

The work classification unit 62 estimates the work state of the work machine 100 on the basis of a change in the inclination angle acquired by the acquisition unit 63.

The work classification unit 62 includes an excavation load determination unit 160, a revolving determination unit 162, and a dumping determination unit 164.

The excavation load determination unit 160 determines an excavating state and a loaded state on the basis of a change in the inclination angle acquired by the acquisition unit 63. Specifically, the excavating state is determined after an unloaded state. Further, the loaded state is determined after the excavating state.

The revolving determination unit 162 determines a revolving state on the basis of a change in the inclination angle acquired by the acquisition unit 63. Specifically, revolving after the loaded state is determined to be a loaded revolving state. Further, revolving after a dumping state is determined to be an unloaded revolving state.

The dumping determination unit 164 determines the dumping state on the basis of a change in the inclination angle acquired by the acquisition unit 63. Specifically, the dumping state is determined after the loaded revolving state.

The output unit 65 outputs a calculation result of the calculation executed by the calculation unit 61. As an example, the output unit 65 may be configured to output the calculation result to a display unit (not illustrated). Further, the output unit 65 may be configured to transmit the calculation result through a network. For example, the output unit 65 may transmit the estimated work state of the work machine 100 calculated by the calculation unit 61 to an external server through a network. Further, the output unit 65 may be configured to record the work state of the work machine 100 of one day as a report on a sheet.

FIG. 4 Is a Diagram for Explaining a Flow of Work States of the Work Machine 100 according to the embodiment.

With reference to FIG. 4, the work machine 100 repeatedly executes, as the work states, the various work states of a series including (1) excavation, (2) loaded, (3) loaded revolving, (4) dumping, (5) unloaded revolving, and (6) unloaded.

In the embodiment, the work states (1) to (6) described above of the work machine 100 are estimated on the basis of a detection result acquired by the inclination angle detection device 70.

FIG. 5 is a diagram for explaining estimation of the work state of the work machine 100 according to the embodiment. The vertical axis represents the pitch angle, and the horizontal axis represents time t.

With reference to FIG. 5, in this example, data of a pitch angle is shown as the inclination angle of the inclination angle detection device 70.

The work classification unit 62 estimates the work state of the work machine 100 on the basis of at least a change in the pitch angle that is the inclination angle acquired by the acquisition unit 63.

Specifically, as the work states, the various work states of a series including (1) excavation, (2) loaded, (3) loaded revolving, (4) dumping, (5) unloaded revolving, and (6) unloaded are estimated.

FIG. 6 Is a Table for Explaining Determination of the Work State of the Work Machine 100 according to the embodiment.

With reference to FIG. 6, the work classification unit 62 determines the excavating state when the work state is the unloaded state. The work classification unit 62 determines the loaded state when the work state is the excavating state. The work classification unit 62 determines the loaded revolving state when the work state is the loaded state. The work classification unit 62 determines the dumping state when the work state is the loaded revolving state. The work classification unit 62 determines the unloaded revolving state when the work state is the dumping state. The work classification unit 62 determines the unloaded state when the work state is the unloaded revolving state. Then, the processing returns to the initial processing again, and the work classification unit 62 determines the excavating state when the work state is the unloaded state.

FIG. 7 is a diagram for explaining a flow of the estimation processing of the work state of the work machine 100 according to the embodiment.

With reference to FIG. 7, the acquisition unit 63 acquires data from the inclination angle detection device 70 (step S2).

Next, the work classification unit 62 estimates the work state of the work machine 100 on the basis of a change in the inclination angle acquired by the acquisition unit 63 (step S4). The detailed processing of estimating the work state will be described below.

Next, the output unit 65 outputs the determination result (step S6).

Then, the processing is ended (end).

FIG. 8 is a flowchart for explaining the estimation processing of the work state by the work classification unit 62 according to the embodiment.

With reference to FIG. 8, the excavation load determination unit 160 executes excavation load determination processing for the work machine 100 on the basis of a change in the inclination angle acquired by the acquisition unit 63 (step S10). Details of the excavation load determination processing will be described below.

Next, the revolving determination unit 162 executes load revolving determination processing of the work machine 100 on the basis of a change in the inclination angle acquired by the acquisition unit 63 (step S12). Details of the load revolving determination processing will be described below.

Next, the dumping determination unit 164 executes dumping determination processing of the work machine 100 on the basis of a change in the inclination angle acquired by the acquisition unit 63 (step S14). Details of the dumping determination processing will be described below.

Next, the revolving determination unit 162 executes unloaded revolving determination processing of the work machine 100 on the basis of a change in the inclination angle acquired by the acquisition unit 63 (step S16). Details of the unloaded revolving determination processing will be described below.

Then, the determination is made whether the work of the work machine 100 ended (step S18).

When the determination is made in step S18 that the work of the work machine 100 has not ended (NO in step S18), the processing returns to step S10 and the processing described above is repeated.

On the other hand, when the determination is made in step S18 that the work of the work machine 100 ended (YES in step S18), the processing is ended (returned).

Excavation Load Determination Processing

FIG. 9 is a flowchart for explaining the excavation load determination processing by the excavation load determination unit 160 according to the embodiment.

With reference to FIG. 9, the excavation load determination unit 160 sets an excavation threshold and a loaded threshold for the pitch angle when the excavation load determination processing is started (step S20). As the pitch angle at the start of the excavation load determination processing, a pitch angle set in advance as an initial value may be used. For example, a pitch angle at the end of the previous unloaded revolving processing may be used.

Specifically, the excavation load determination unit 160 sets, as the excavation threshold (negative side; example of first threshold), a pitch angle lower by a predetermined value than an initial value or a pitch angle at the time when the previous unloaded revolving processing ended. Further, the excavation load determination unit 160 sets, as the loaded threshold (positive side; example of second threshold), a pitch angle higher by a predetermined value than the initial value or the pitch angle at the time when the previous unloaded revolving processing ended.

Next, the excavation load determination unit 160 determines whether the pitch angle is equal to or less than the excavation threshold (negative side; step S22). The excavation load determination unit 160 calculates and utilizes a time-averaged value of the pitch angles of a predetermined period. A length of the predetermined period can be adjusted as appropriate.

When the determination is made in step S22 that the pitch angle is not equal to or less than the excavation threshold (NO in step S22), the excavation load determination unit 160 maintains the previous state.

On the other hand, when the determination is made in step S22 that the pitch angle is equal to or less than the excavation threshold (YES in step S22), the excavation load determination unit 160 determines the state as the excavating state (step S24).

Next, the excavation load determination unit 160 determines whether the pitch angle is equal to or greater than the loaded threshold (positive side) (step S26).

When the determination is made in step S26 that the pitch angle is not equal to or greater than the loaded threshold (positive side; NO in step S26), the excavation load determination unit 160 maintains the previous state.

On the other hand, when the excavation load determination unit 160 determines in step S26 that the pitch angle is equal to or greater than the loaded threshold (positive side; YES in step S26), the excavation load determination unit 160 determines the state as the loaded state (step S28).

Then, the processing is ended (returned). Then, the processing proceeds to the next load revolving determination processing.

FIG. 10 is a diagram for explaining a specific example of the excavation load determination processing of the excavation load determination unit 160 according to the embodiment. The vertical axis represents the pitch angle, and the horizontal axis represents the time t.

With reference to FIG. 10, in the present example, initial values or pitch angles P1 to P3 at the time when the previous unloaded revolving processing ended are shown.

The excavation load determination unit 160 sets an excavation threshold PDth1 (negative side) and a loaded threshold PUth1 (positive side) relative to the pitch angle P1 of the initial value.

The excavation load determination unit 160 determines the state as excavation when the pitch angle is equal to or less than the excavation threshold PDth1 (negative side).

The excavation load determination unit 160 determines the state as loaded when the pitch angle is equal to or greater than the loaded threshold PUth1 (positive side).

Similarly, the excavation load determination unit 160 sets an excavation threshold PDth2 (negative side) and a loaded threshold PUth2 (positive side) relative to the pitch angle P2 at the time when the previous unloaded revolving processing ends.

The excavation load determination unit 160 determines the state as the excavating state when the pitch angle is equal to or less than the excavation threshold PDth2 (negative side).

The excavation load determination unit 160 determines the state as the loaded state when the pitch angle is equal to or greater than the loaded threshold PUth2 (positive side).

Similarly, the excavation load determination unit 160 sets an excavation threshold PDth3 (negative side) and a loaded threshold PUth3 (positive side) relative to the pitch angle P3 at the time when the previous unloaded revolving processing ends.

The excavation load determination unit 160 determines the state as the excavating state when the pitch angle is equal to or less than the excavation threshold PDth3 (negative side).

The excavation load determination unit 160 determines the state as the loaded state when the pitch angle is equal to or greater than the loaded threshold PUth3 (positive side).

According to this processing, the excavating state and the loaded state are determined on the basis of a change in the pitch angle of the inclination angle, making it possible to estimate the work state of the work machine by a simple method.

Typically, excavation is performed by retracting the boom, the arm, and/or the bucket rearward with a distal end of the bucket inserted into the ground, thereby gathering earth and sand in the bucket. When the earth and sand are gathered in the bucket and pulled up, the entire vehicle body is pulled forward and tilted frontward by a reaction force from the ground. When the earth and sand are pulled upward from the ground, a reaction also occurs during excavation, inclining the entire vehicle body rearward from the state before excavation. Thus, in the excavation work, the angle (pitch angle) in the front-rear direction of the vehicle body exhibits a characteristic change, making it possible to determine the excavating state and the loaded state.

The inventors focused on how the work state could be determined from subtle changes in pitch angle during excavation work and, after conducting various tests and confirming the effectiveness of this approach, arrived at the concept of the disclosure.

Predetermined fixed values may also be used as the thresholds used for the determination of the work state. However, the values may be adjusted according to work site, work content, individual differences in work vehicle, and the like. Therefore, by setting the thresholds on the basis of the initial value or the pitch angle at the time when the previous unloaded revolving processing ends, it is possible to determine the work state with higher accuracy.

Although the estimation method of the work state based on pitch angle alone has been described in the present example, the pitch angle and the roll angle may be used to estimate the work state. As described below, the revolving state can be determined on the basis of the pitch angle and the roll angle. That is, with the combination with a change in roll angle, it is possible to determine whether the pitch angle changed in association with revolving. By using the pitch angle and the roll angle in this way, it is possible to determine the excavating state and the loaded state more accurately.

Revolving Determination Processing

FIG. 11 is a diagram for explaining the revolving determination processing of the revolving determination unit 162 according to the embodiment. The vertical axis represents the pitch angle or the roll angle, and the horizontal axis represents the time t.

With reference to FIG. 11, the revolving determination unit 162 according to the embodiment utilizes changes in the pitch angle and the roll angle. Specifically, as shown in the diagram, during the revolving operation of the work machine 100, the pitch angle and the roll angle form sine waveforms and cosine waveforms having different phases. That is, the pitch angle and the roll angle have similar waveforms interlocked with each other. If the ground on which the work machine 100 is located is a completely horizontal surface, the pitch angle and the roll angle do not change even with revolving, making it difficult to determine the revolving state from the pitch angle and the roll angle. On the other hand, the ground on which the work machine 100 is located is typically not a perfectly horizontal surface, and the pitch angle and the roll angle change due to revolving. Therefore, the revolving state can be determined from changes in the pitch angle and the roll angle.

Accordingly, when the waveforms of the pitch angle and the roll angle are compared with each other and interlocked waveforms are detected, the revolving determination unit 162 determines the state as the revolving state.

FIG. 12 is a diagram for explaining the load revolving determination processing of the revolving determination unit 162 according to the embodiment.

With reference to FIG. 12, the revolving determination unit 162 determines the revolving state after the loaded state as loaded revolving. Specifically, the revolving determination unit 162 determines whether the pitch angle and the roll angle change in an interlocking manner (step S30). The revolving determination unit 162 calculates and utilizes time-averaged values of the pitch angles and the roll angles of a predetermined period. A length of the predetermined period can be adjusted as appropriate.

When the determination is made in step S30 that the pitch angle and the roll angle do not change in an interlocking manner (NO in step S30), the revolving determination unit 162 maintains the previous state.

On the other hand, when the determination is made that the pitch angle and the roll angle change in an interlocking manner (YES in step S30), the revolving determination unit 162 determines the state as the loaded revolving state (step S32).

Next, the revolving determination unit 162 determines whether the state in which the pitch angle and the roll angle change in an interlocking manner ended (step S34).

When the determination is made in step S34 that the state in which the pitch angle and the roll angle change in an interlocking manner has not ended (NO in step S34), the revolving determination unit 162 returns the processing to step S32 and maintains the state.

On the other hand, when the determination is made in step S34 that the state in which the pitch angle and the roll angle change in an interlocking manner ended (YES in step S34), the revolving determination unit 162 ends (returns) the processing. Then, the processing proceeds to the next dumping determination processing.

FIG. 13 is a diagram for explaining the unloaded revolving determination processing of the revolving determination unit 162 according to the embodiment.

With reference to FIG. 13, the revolving determination unit 162 determines that the revolving state after the dumping state is unloaded revolving. Specifically, the revolving determination unit 162 determines whether the pitch angle and the roll angle change in an interlocking manner (step S40). The revolving determination unit 162 calculates and utilizes the time-averaged values of the pitch angles and the roll angles of a predetermined period. A length of the predetermined period can be adjusted as appropriate.

When the determination is made in step S40 that the pitch angle and the roll angle do not change in an interlocking manner (NO in step S40), the revolving determination unit 162 maintains the previous state.

On the other hand, when the determination is made that the pitch angle and the roll angle change in an interlocking manner (YES in step S40), the revolving determination unit 162 determines the state as the unloaded revolving state (step S42).

Next, the revolving determination unit 162 determines whether the state in which the pitch angle and the roll angle change in an interlocking manner ended (step S44).

When the determination is made in step S44 that the state in which the pitch angle and the roll angle change in an interlocking manner has not ended (NO in step S44), the revolving determination unit 162 returns the processing to step S42 and maintains the state.

On the other hand, when the determination is made in step S44 that the state in which the pitch angle and the roll angle change in an interlocking manner ended (YES in step S44), the revolving determination unit 162 determines the state as the unloaded state (step S46). Then, the processing is ended (returned). Then, when the work continues, the processing returns to the initial excavation load determination processing.

Further, the pitch angle at the end of the unloaded revolving determination processing is stored. The pitch angle is used for the excavation threshold and the loaded threshold in the excavation load determination processing.

FIG. 14 is a diagram for explaining a specific example of the load revolving determination processing and the unloaded revolving determination processing of the revolving determination unit 162 according to the embodiment. The vertical axis represents the pitch angle or the roll angle, and the horizontal axis represents the time t.

With reference to FIG. 14, the revolving determination unit 162 according to the embodiment determines whether the pitch angle and the roll angle change in an interlocking manner by utilizing changes in the pitch angle and the roll angle. Specifically, the roll angle and the pitch angle change in the same direction during revolving, making it possible to obtain the respective amounts of change and determine the state as the revolving state when the amounts of change have the same positive or negative sign.

In the shaded area in this example, the value of the roll angle significantly changes as the pitch angle significantly changes. For example, it is understood that, in the leftmost shaded area, the roll angle significantly decreases and the pitch angle also significantly decreases slightly before then. Thus, although determination of the revolving state by the change in the pitch angle alone is difficult, it is possible to determine the revolving state by combining this change with the change in the roll angle.

As shown in the drawing, a case is shown in which the revolving state after loading is determined to be the loaded revolving state, and the revolving state after dumping is determined to be the unloaded revolving state.

According to this processing, the loaded revolving state and the unloaded revolving state are determined on the basis of changes in the pitch angle and the roll angle of the inclination angle, making it possible to estimate the work state of the work machine by a simple method.

Dumping Determination Processing

FIG. 15 is a diagram for explaining the dumping determination processing of the dumping determination unit 164 according to the embodiment.

With reference to FIG. 15, the dumping determination unit 164 determines whether the pitch angle of a predetermined period dropped by a predetermined value or more after the end of revolving (step S50). This can be determined on the basis of the fact that the work vehicle tilts slightly forward and the pitch angle changes as a result of the dumping work. The predetermined value may be an initial value determined in advance. The predetermined value may use a ratio value rather than a quantitative value. The change in the pitch angle associated with dumping may vary depending on the type of work vehicle, the target material, and the like, and thus the predetermined value may be adjusted according to the situation. Note that the predetermined value may be manually adjusted, or may be automatically calculated and adjusted on the basis of a transition in the pitch angle during work. The dumping determination unit 164 calculates and utilizes a time-averaged value of the pitch angles of a predetermined period. A length of the predetermined period can be adjusted as appropriate.

In step S50, when the determination is made that the pitch angle of the predetermined period did not drop by the predetermined value or more after the end of revolving (NO in step S50), the dumping determination unit 164 maintains the previous state.

On the other hand, in step S50, when the determination is made that the pitch angle of the predetermined period dropped by the predetermined value or more after the end of revolving (YES in step S50), the dumping determination unit 164 determines the state as the dumping state (step S52).

Then, the Processing Is Ended (returned). Then, the Processing Proceeds to the Next unloaded revolving determination processing.

FIG. 16 is a diagram for explaining a specific example of the dumping determination processing of the dumping determination unit 164 according to the embodiment. The vertical axis represents the pitch angle, and the horizontal axis represents the time t.

With reference to FIG. 16, a case is shown in which the dumping determination unit 164 according to the embodiment determines whether the pitch angle of the predetermined period drops by a predetermined value or more, and determines the state as dumping upon determination that the pitch angle dropped by the predetermined value or more.

According to this processing, the dumping state is determined on the basis of a change in the pitch angle of the inclination angle, making it possible to estimate the work state of the work machine by a simple method.

According to the processing described above, the work classification unit 62 according to the embodiment can estimate the various work states of a series including excavation, loaded, loaded revolving, dumping, unloaded revolving, and unloaded by a simple method by using at least the pitch angle as the inclination angle.

First Modification

In a first modification of the embodiment, excavation load determination processing having high accuracy will be described.

FIG. 17 is a flowchart for explaining the excavation load determination processing by the excavation load determination unit 160 according to the first modification of the embodiment.

With reference to FIG. 17, as compared with the flowchart in FIG. 9, the flowchart differs in the addition of steps S23 and S27. Other portions are similar, and thus detailed description thereof will not be repeated.

When the determination is made in step S22 that the pitch angle is equal to or less than the excavation threshold (YES in step S22), the excavation load determination unit 160 determines whether the pitch angle is equal to or less than the excavation threshold for a predetermined period or longer (step S23).

In step S23, when the determination is made that the pitch angle is equal to or less than the excavation threshold for the predetermined period or longer (YES in step S23), the excavation load determination unit 160 determines the state as the excavating state (step S24).

On the other hand, when the determination is made in step S23 that the pitch angle is not equal to or less than the excavation threshold for the predetermined period or longer (NO in step S23), the excavation load determination unit 160 returns the processing to step S22.

Further, when the determination is made in step S26 that the pitch angle is equal to or greater than the loaded threshold (positive side; YES in step S26), the excavation load determination unit 160 determines whether the pitch angle is equal to or greater than the loaded threshold for the predetermined period of time or longer (step S27).

When the determination is made in step S27 that the pitch angle is equal to or greater than the loaded threshold for the predetermined period of time or longer (YES in step S27), the excavation load determination unit 160 determines the state as the loaded state (step S28).

On the other hand, when the determination is made in step S27 that the pitch angle is not equal to or greater than the loaded threshold for the predetermined period or longer (NO in step S27), the excavation load determination unit 160 returns the processing to step S26.

According to this processing, the determination is made that the pitch angle is equal to or less than the excavation threshold or equal to or greater than the loaded threshold for a predetermined period of time or longer and, when the pitch angle is equal to or less than the excavation threshold or equal to or greater than the loaded threshold for the predetermined period of time or longer, the determination is made that the state is the excavating state or the loaded state.

According to this processing, the excavating state and the loaded state are determined on the basis of a change in pitch angle while avoiding erroneous determination caused by the influence of noise of the pitch angle as the inclination angle, making it possible to execute excavation or loaded determination processing with high accuracy.

Second Modification

FIG. 18 is a flowchart for explaining revolving determination by the revolving determination unit 162 according to a second modification of the embodiment.

With reference to FIG. 18, the revolving determination unit 162 determines whether the yaw angle is equal to or greater than a predetermined threshold or equal to or less than a predetermined threshold (step S60).

When the determination is made in step S60 that the yaw angle is equal to or greater than the predetermined threshold or equal to or less than the predetermined threshold (YES in step S60), the revolving determination unit 162 determines the state as the revolving state.

Then, the processing is ended (returned).

On the other hand, when the determination is made in step S60 that the yaw angle is not equal to or greater than the predetermined threshold or not equal to or less than the predetermined threshold (NO in step S60), the revolving determination unit 162 maintains the previous state.

For example, the revolving determination unit 162 determines the state as the loaded revolving state in the case of revolving after loading. Further, the revolving determination unit 162 determines the state as the unloaded revolving state in the case of revolving after dumping.

FIG. 19 is a diagram for explaining a specific example of the revolving determination processing by the revolving determination unit 162 according to the second modification of the embodiment. The vertical axis represents the yaw angle, and the horizontal axis represents the time t.

With reference to FIG. 19, a case is shown in which the revolving determination unit 162 according to the embodiment determines whether the yaw angle is equal to or greater than a predetermined threshold or equal to or less than a predetermined threshold, and determines the state as the revolving state upon determination that the yaw angle is equal to or greater than the predetermined threshold or equal to or less than the predetermined threshold.

As shown in the drawing, a case is shown in which the revolving state after loading is determined to be the loaded revolving state, and the revolving state after dumping is determined as the unloaded revolving state.

According to this processing, the revolving state is determined on the basis of a change in the yaw angle instead of the pitch angle and the roll angle as the inclination angle, making it possible to estimate the work state of the work machine by a simple method.

As illustrated in FIG. 2, the yaw angle is an angle indicating the revolving direction itself, making it possible to more accurately estimate the revolving state by utilizing a change in the yaw angle instead of the pitch angle and the roll angle.

Third Modification

FIG. 20 is a diagram for explaining a bucket angle during dumping according to the embodiment.

With reference to FIG. 20, when the bucket angle is equal to or less than a predetermined angle, the state can be determined to be dumping. The bucket angle is acquired by using a sensor (not illustrated) that is mounted onto the bucket 8 of the work machine 100 and detects the bucket angle that is an inclination angle from a reference line.

FIG. 21 is a flowchart for explaining the dumping determination processing of the dumping determination unit 164 according to a third modification of the embodiment.

With reference to FIG. 21, the dumping determination unit 164 determines whether the bucket angle is equal to or less than a predetermined threshold (step S70).

When the determination is made in step S70 that the bucket angle is equal to or less than the predetermined threshold (YES in step S70), the dumping determination unit 164 determines the state as the dumping state (step S72). Then, the processing is ended (returned).

On the other hand, when the determination is made in step S70 that the bucket angle is not equal to or less than the predetermined threshold (NO in step S70), the dumping determination unit 164 maintains the previous state.

FIG. 22 is a diagram for explaining a specific example of the dumping determination processing by the dumping determination unit 164 according to the third modification of the embodiment. The vertical axis represents the bucket angle and the horizontal axis represents the time t.

With reference to FIG. 22, a case is shown in which the dumping determination unit 164 according to the third modification of the embodiment determines whether the bucket angle is equal to or less than a predetermined threshold, and determines the state as the dumping state upon determination that the bucket angle is equal to or less than the predetermined threshold.

As shown in the drawing, a predetermined angle is set as the threshold, and the state can be determined to be the dumping state when the bucket angle is equal to or less than the predetermined threshold.

According to this processing, the dumping state is determined on the basis of a change in the bucket angle instead of the pitch angle as the inclination angle, making it possible to estimate the work state of the work machine by a simple method.

Note that, although a case of the bucket angle being utilized is described in this example, the bucket angle may be used in combination with the pitch angle, for example, to estimate the work state of the work machine.

Further, a value corrected by using the inclination angle acquired by the inclination angle detection device 70 during calculation of the bucket angle may be used to determine the dumping state of the work machine.

Other Embodiments

Teacher data obtained by combining the data of the inclination angle described above and, as correct data, the determination result of the work state may be generated, and a learning model that estimates the work state by executing learning using a machine learning algorithm may be created.

Further, the controller described above may be connected to a network (not illustrated) and execute data communication processing with an external device (server, for example).

At least some of the functions executed in the controller may be distributed and executed by a plurality of devices capable of communicating with each other via a network (wide area network and/or local network). Specifically, at least some of the various functions executed in the controller may be configured to be executed by a server.

In the embodiment described above, a hydraulic excavator is given as an example of the work machine. However, the work machine is not limited to a hydraulic excavator, and other types of work machines such as a wheel loader, a bulldozer, and a motor grader are also applicable.

Supplementary Notes

Such an embodiment as described above includes technical ideas such as described below.

Supplementary Note 1

A work state estimation system for a work machine, the work state estimation system including:

• • an inclination angle acquisition unit (63) configured to acquire an inclination angle of a work machine (100); and
  • a work state estimation unit (62) configured to estimate a work state of the work machine on the basis of a change in the inclination angle, wherein
  • the inclination angle includes at least a pitch angle.

Supplementary Note 2

The work state estimation system for a work machine according to Supplementary Note 1, wherein

• • the work machine includes a work implement (2), and
  • the work state includes an excavating state.

Supplementary Note 3

The work state estimation system for a work machine according to Supplementary Note 2, wherein

• • the work state includes a loaded state or an unloaded state.

Supplementary Note 4

The work state estimation system for a work machine according to any one of Supplementary Notes 2 and 3, wherein

• • the work state includes a dumping state.

Supplementary Note 5

The work state estimation system for a work machine according to any one of Supplementary Notes 1 to 4, wherein

• • the inclination angle further includes at least one of a roll angle or a yaw angle.

Supplementary Note 6

The work state estimation system for a work machine according to Supplementary Note 5, wherein

• • the work machine includes a revolving body (3), and
  • the work state includes a revolving state.

Supplementary Note 7

The work state estimation system for a work machine according to any one of Supplementary Notes 2 to 6, wherein

• • the work state estimation unit includes an excavation load determination unit (160) configured to determine the excavating state and a loaded state as the work state, and
  • the excavation load determination unit is configured to determine the excavating state on the basis of a comparison between the inclination angle and a first threshold.

Supplementary Note 8

The work state estimation system for a work machine according to Supplementary Note 7, wherein

• • the excavation load determination unit is configured to determine the loaded state on the basis of a comparison between the inclination angle and a second threshold.

Supplementary Note 9

The work state estimation system for a work machine according to Supplementary Note 8, wherein

• • the excavation load determination unit is configured to determine the loaded state when the inclination angle is equal to or greater than the second threshold for a predetermined period.

Supplementary Note 10

The work state estimation system for a work machine according to Supplementary Note 6, wherein

• • the work state estimation unit further includes a revolving determination unit (162) configured to determine revolving as the work state, and
  • the revolving determination unit is configured to determine the revolving on the basis of changes in the pitch angle and the roll angle or a change in the yaw angle.

Supplementary Note 11

The work state estimation system for a work machine according to Supplementary Note 4, wherein

• • the work state estimation unit further includes a dumping determination unit (164) configured to determine dumping as the work state, and
  • the dumping determination unit is configured to determine the dumping on the basis of a comparison between the inclination angle and a predetermined threshold.

Supplementary Note 12

A work state estimation method for a work machine, the work state estimation method including:

• • acquiring an inclination angle of a work machine (S2); and
  • estimating a work state of the work machine on the basis of a change in the inclination angle (S4), wherein
  • the inclination angle includes at least a pitch angle.

While the embodiments of the disclosure have been described above, it should be understood that the embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the disclosure is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

REFERENCE SIGNS LIST

• • 1 Vehicle body, 2 Work implement, 3 Revolving body, 4 Cab, 4S Operator seat, 5 Traveling device, 5Cr Crawler, 6 Boom, 7 Arm, 8 Bucket, 9 Engine room, 10 Boom cylinder, 11 Arm cylinder, 12 Bucket cylinder, 13 Boom pin, 14 Arm pin, 15 Bucket pin, 19 Handrail, 60 Controller, 61 Calculation unit, 62 Work classification unit, 63 Acquisition unit, 64 Storage unit, 65 Output unit, 70 Inclination angle detection device, 100 Work machine, 160 Excavation load determination unit, 162 Revolving determination unit, 164 Dumping determination unit.