Construction machine

Abstract

To provide a construction machine capable of estimating hardness of ground with high accuracy.SOLUTION: A construction machine 1 includes a machine body 1S, a work attachment 20 which has a bucket 23 for excavating and holding sediment constituting ground, and can execute excavation operation of the ground through the bucket 23 in a state of being mounted on the machine body 1S, a weight detection part capable of detecting a weight of sediment E held by the bucket 23, and a hardness estimation part for estimating hardness of the ground, wherein the hardness estimation part executes estimation processing of estimating hardness of the ground on the basis of a weight of the sediment E detected by the weight detection part, and hardness-associated data in which the weight of the sediment E and the hardness of the ground are associated with each other, when estimating the hardness of the ground, after predetermined excavation operation of changing the attitude of the work attachment 20 while satisfying a target speed condition from an excavation start attitude to an excavation completion attitude capable of holding the sediment E after excavation.SELECTED DRAWING: Figure 4C

Description

[Technical field]

[0001] The present invention relates to a construction machine. [Background technology]

[0002] Conventionally, there is known a construction machine that has a machine body and a working attachment supported on the machine body so as to be capable of raising and lowering, and is configured to be able to estimate the hardness of the ground. Patent Document 1 discloses an example of such a construction machine. This construction machine has a sensor including a strain sensor or an acceleration sensor attached to the working attachment, and a hardness estimation unit that estimates the hardness of the ground based on the detection value of the sensor.

[0003] The hardness estimation unit is configured to estimate the hardness of the ground based on a detection value of the sensor when a predetermined operation is performed to bring the working attachment into contact with the ground (ground) at a predetermined speed and a predetermined angle, and data in which the detection value of the sensor when the predetermined operation is performed is associated with the hardness of the ground. Specifically, the hardness estimation unit is configured to determine the characteristics of a waveform of the detection value by the sensor (for example, characteristics such as whether or not the waveform shows a large acceleration followed by a decrease in acceleration in a short time) and estimate the hardness of the ground according to the determined characteristics of the waveform (see, for example, paragraphs

[0054] -

[0055] of Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7073151 Summary of the Invention [Problem to be solved by the invention]

[0005] In the construction machine shown in Patent Document 1, when the hardness estimation unit estimates the hardness of the ground, it discriminates the characteristics of the waveform of the detection value by the sensor, which results in the problem that the calculation process becomes more complex and the risk of misjudgment increases compared to simply discriminating between the magnitude relationships of the detection values ​​(as a result, the accuracy of estimating the ground hardness decreases).

[0006] Furthermore, in the construction machine shown in Patent Document 1, in order to estimate the ground hardness with high resolution, it is necessary to finely classify the waveform characteristics of the sensor detection value according to the ground hardness and prepare data that corresponds to the ground hardness. However, if the waveform characteristics are finely classified, the accuracy of waveform discrimination in the hardness estimation unit decreases, which in turn causes a problem of a decrease in the accuracy of ground hardness estimation in the hardness estimation unit.

[0007] The present invention has been made in order to solve the above-mentioned problems, and has an object to provide a construction machine capable of estimating the hardness of the ground with high accuracy. [Means for solving the problem]

[0008] The present invention provides a machine body, a work attachment attached to the machine body, having a bucket capable of excavating and holding soil that constitutes the ground and capable of performing an excavation operation of the ground via the bucket, a weight detection unit capable of detecting the weight of the soil held in the bucket, and a hardness estimation unit that estimates the hardness of the ground, wherein the hardness estimation unit is configured to execute an estimation process to estimate the hardness of the ground based on the weight of the soil detected by the weight detection unit and first hardness correspondence data that specifies the change in weight of the soil due to differences in hardness of the ground after a predetermined excavation operation has been performed in which the work attachment changes its posture from a start of excavation posture to a completion of excavation posture capable of holding the soil after excavation while satisfying a target speed condition.

[0009] According to this configuration, the hardness of the ground is estimated based on the weight of the soil held in the bucket by the predetermined excavation operation of the working attachment and the hardness corresponding data, and thus the complicated calculation process for distinguishing the waveform detected by the sensor can be eliminated and the ground hardness can be easily estimated. Therefore, compared with the conventional case where the characteristics of the waveform detected by the sensor are distinguished by complicated calculation process, the risk of misjudgment can be reduced and the accuracy of the ground hardness estimation can be improved. In addition, in the conventional process, when the resolution for estimating the ground hardness is increased, the waveform detected by the sensor needs to be finely classified according to the ground hardness, so that the types of detected waveforms to be distinguished when estimating the ground hardness increase, and the accuracy of the discrimination decreases (and the accuracy of the ground hardness estimation decreases). In contrast, in this configuration, the ground hardness is estimated based on the weight of the soil held in the bucket, so even if the resolution of the ground hardness is increased, the number of discrimination targets does not increase, and it is only necessary to distinguish the size of the soil, so the accuracy of the ground hardness estimation does not decrease.

[0010] Furthermore, according to this configuration, a specified excavation operation can be incorporated into the normal excavation work performed by the work attachment so that the hardness estimation unit can estimate the hardness of the ground, eliminating the need for a dedicated operation just for estimating ground hardness, and allowing excavation work by the work attachment to be performed efficiently.

[0011] It is preferable that the construction machine is equipped with an operation data acquisition unit that acquires operation data related to the operating state of the work attachment during the excavation operation and correlated with the hardness of the ground that is the target of the excavation operation, and when executing the estimation process, the hardness estimation unit executes a first calculation process to calculate a ground hardness corresponding to the weight of the soil detected by the weight detection unit after the work attachment has performed the specified excavation operation as a first hardness based on the weight of the soil detected by the weight detection unit and the first hardness correspondence data, and a second calculation process to calculate a ground hardness corresponding to the acquired operation data as a second hardness based on the operation data acquired by the operation data acquisition unit during the specified excavation operation and second hardness correspondence data that defines changes in the operation data due to differences in ground hardness, and is configured to estimate the hardness of the ground based on the first hardness calculated in the first calculation process and the second hardness calculated in the second calculation process.

[0012] According to this configuration, the ground hardness is estimated based on not only the weight of soil held in the bucket by the predetermined excavation operation but also the operation data of the work attachment during the excavation operation, thereby improving the accuracy of estimating the ground hardness. That is, the weight of soil held in the bucket by the predetermined excavation operation easily changes due to changes in the bucket's trajectory caused by the bucket coming into contact with a foreign object during the excavation operation, roughness of the terrain, etc. For this reason, if the ground hardness is estimated based only on the weight of soil held in the bucket, there is a risk that the accuracy of estimating the ground hardness will decrease due to variations in the weight of soil held in the bucket. In contrast, in the above configuration, the ground hardness estimation process is performed based on the first hardness based on the weight of soil held in the bucket after the predetermined excavation operation and the second hardness based on the operation parameters of the work attachment during the predetermined excavation operation, thereby improving the estimation accuracy as much as possible compared to the case of estimating the ground hardness based only on the weight of soil.

[0013] It is preferable that the hardness estimation unit is configured to execute an operation determination process to determine whether or not the specified excavation operation has been performed correctly along a specified trajectory when the specified excavation operation is performed by the work attachment, and not to execute the estimation process if it determines that the specified excavation operation has not been performed correctly.

[0014] According to this configuration, if the predetermined excavation operation is not performed correctly, the estimation process by the hardness estimation unit is not performed, so that it is possible to prevent erroneous estimation of ground hardness by the hardness estimation unit. Here, if the predetermined excavation operation is not performed correctly, for example, if the speed state of the work attachment when the predetermined excavation operation is performed does not satisfy the target speed condition, such as when the bucket rotates freely in the air or when a push excavation operation is performed by rotating the machine body while pressing the bucket against the side of a trench or the ground. Note that not performing the estimation process includes both a case where the estimation process itself is not performed and a case where the estimation process is performed but the result is not output.

[0015] The operating data is numerical data relating to operating parameters which relate to the operating state of the work attachment during the excavation operation and which are correlated with the hardness of the ground which is the subject of the excavation operation, and it is preferable that the operating parameters include at least one of the load on a cylinder which drives the work attachment, the velocity of the center of gravity of the work attachment, the acceleration of the center of gravity of the work attachment, and the excavation reaction force acting on the work attachment.

[0016] In this way, by setting parameters that are highly correlated with the hardness of the ground as the operating parameters, the accuracy of the hardness estimation of the ground by the hardness estimation unit can be improved. That is, the harder the ground is, the greater the load on the drive cylinder of the working attachment. In addition, the harder the ground is, the greater the vibration of the working attachment during the excavation operation, so the velocity and acceleration of the center of gravity of the working attachment also change in a vibrational manner. In addition, the harder the ground is, the greater the excavation reaction force acting on the working attachment. In this way, since the four parameters are highly correlated with the hardness of the ground, by setting these as operating parameters, the degree of agreement between the second hardness based on the operating parameters and the actual hardness of the ground is increased, and thus the accuracy of the estimation of the ground hardness based on the second hardness and the first hardness can be improved.

[0017] The operating data is numerical data relating to at least one operating parameter which is related to the operating state of the work attachment during the excavation operation and which is correlated with the hardness of the ground which is the subject of the excavation operation, and it is preferable that the hardness estimation unit is configured, when executing the estimation process, to calculate at least one second hardness which corresponds to the at least one operating parameter and the first hardness which corresponds to the weight of the soil, and to estimate the hardness of the ground based on the calculated at least one second hardness and the first hardness and a weighting coefficient which is preset for each of the hardnesses.

[0018] According to this configuration, for each of at least one second hardness based on the value of at least one operating parameter and the first hardness based on the weight of the soil held in the bucket, a high weighting coefficient is set for an indicator that has a strong correlation with the ground hardness, and a low weighting coefficient is set for an indicator that has a low correlation, thereby improving the accuracy of estimating ground hardness.

[0019] It is preferable that the hardness estimation unit is configured to store the hardness of the ground estimated each time the specified excavation operation is performed, and to estimate and output the average value of the stored hardnesses for a specified number of times as the hardness of the ground.

[0020] According to this configuration, the estimated value of ground hardness output by the hardness estimation unit is the average value for a predetermined number of times, so that even if there is a large variation in the estimated values ​​of ground hardness, the estimation error of ground hardness can be reduced by taking the average value.

[0021] It is also preferable that the hardness estimation unit is configured to change the weighting coefficient based on the posture of the work attachment during the specified excavation operation or on time-series changes in the numerical values ​​in the operational data.

[0022] According to this configuration, by changing the weighting coefficient based on the posture of the work attachment and the time-series changes in the numerical values ​​in the operating data, the weighting coefficients of the indicators (soil weight and operating parameters) that have a large influence on the estimation accuracy of the ground hardness can be set relatively large depending on the situation during the excavation operation by the work attachment, thereby making it possible to improve the estimation accuracy of the ground by the hardness estimation unit as much as possible.

[0023] It is preferable that the hardness estimation unit is configured to execute the operation determination process based on the distance from the base end of the work attachment in the excavation start posture to the tip of the bucket and operation input information of the work attachment after the start of the specified excavation operation.

[0024] According to this configuration, by executing the motion determination process based on the distance from the base end of the work attachment in the excavation start attitude to the tip of the bucket, it is possible to prevent a state in which the work attachment is leveling the ground near the machine body from being erroneously determined to be the specified excavation motion. Also, by executing the motion determination process based on operation input information of the work attachment after the start of the specified excavation motion, it is possible to prevent a push excavation state in which the machine body is rotated while the bucket is pushed against the side of a trench or the ground from being erroneously determined to be the specified excavation motion.

[0025] The construction machine further includes a speed condition setting unit which sets the target speed condition, and the speed condition setting unit is configured to reset the target speed condition after the work attachment performs a predetermined number of times of a specified excavation operation while satisfying the target speed condition, and when resetting the target speed condition, the speed condition setting unit preferably obtains the ground hardness estimated by the hardness estimation unit at the time when the predetermined number of times of the specified excavation operation has been performed, and sets the amount of soil excavated by the bucket when ground of the obtained hardness is excavated by the specified excavation operation of the work attachment to an amount corresponding to the maximum load that the bucket can hold.

[0026] According to this configuration, even if the hardness of the ground changes from soft to hard or from hard to soft as the excavation of the ground by the predetermined excavation operation progresses, the target speed condition is changed according to the changed hardness of the ground. Therefore, a sufficient amount of soil can be excavated by the bucket. In other words, if the ground to be excavated is hard but the working attachment is driven under the target speed condition corresponding to soft soil, the amount of soil excavated by the bucket cannot be sufficiently ensured, which not only reduces the accuracy of estimating the hardness of the ground but also may reduce the efficiency of excavating the ground by the working attachment, which is the original purpose. However, according to the above configuration, the target speed condition is set according to the hardness of the ground, so the efficiency of excavation by the working attachment does not decrease.

[0027] It is preferable that the work attachment has a plurality of members including the bucket that are movable relative to one another, and the target speed condition comprises a condition that the speed of the center of gravity of one of the plurality of members, an arm connected to the bucket, or the speed of the combined center of gravity of the plurality of members, is constant.

[0028] According to this configuration, when the work attachment is made to perform a predetermined excavation operation, the excavation by the bucket can be stably performed, and the difference in excavation trajectory due to the difference in ground hardness can be clearly generated, and thus the estimation accuracy of the ground hardness can be improved. In particular, by making the speed of the composite center of gravity of the multiple members constant, the operation of the entire work attachment can be stabilized. That is, since the excavation operation by the work attachment is performed by the cooperation of multiple members (e.g., the boom, the arm, and the bucket), when the hardness estimation unit estimates the ground hardness, the excavation of the ground by the bucket can be stably (evenly) performed by making the work attachment perform a predetermined excavation operation so that the speed of the composite center of gravity of the multiple members is constant. Therefore, the reproducibility of the weight of soil held in the bucket after the predetermined excavation operation (in other words, the reproducibility of the weight of soil when the excavation operation is performed on the ground of the same hardness under the same speed conditions) is ensured, and the estimation accuracy of the ground hardness based on the weight of the soil can be improved.

[0029] It is preferable that the construction machine further includes a deviation calculation unit that detects the speed state of the work attachment while the specified excavation operation is being performed and calculates information relating to the deviation between the detected speed state and the target speed condition, and an alarm unit that notifies the information relating to the deviation calculated by the deviation calculation unit.

[0030] According to this configuration, the operator can recognize how much the speed state of the work attachment deviates from the target speed condition based on the information related to the deviation degree notified by the notification unit while the work attachment is performing a predetermined excavation operation. Then, based on this recognition, the operator can correct the manual operation he or she performs so that the speed state of the work attachment satisfies the target speed condition. Therefore, it is possible to prevent the speed of the composite center of gravity of the work attachment from varying due to the manual operation of the operator. In turn, it is possible to improve the reproducibility of the weight of soil held in the bucket after a predetermined excavation operation, and further improve the accuracy of the ground hardness estimation by the hardness estimation unit.

[0031] It is preferable that the construction machine comprises a speed state detection unit which detects the speed state of the work attachment while the specified excavation operation is being performed, a drive unit for driving the work attachment, and a control unit which, while the specified excavation operation is being performed by the work attachment, determines a command signal to the drive unit based on a comparison between the speed state of the work attachment detected by the speed state detection unit and the target speed condition so that the speed state satisfies the target speed condition, and executes control to transmit the determined command signal to the drive unit.

[0032] According to this configuration, while the work attachment is performing a predetermined excavation operation, a command signal is sent from the control unit to the drive unit so that the speed state of the work attachment satisfies the target speed condition (so-called feedback control is executed). Therefore, when the work attachment is caused to perform a predetermined excavation operation by manual operation by an operator, for example, it is possible to prevent the speed of the combined center of gravity of the work attachment from deviating from the target speed condition due to variations in the operator's manual operation, etc. Note that the predetermined excavation operation of the work attachment may be executed not by manual operation but by automatic control by a controller, for example, and in this case, similar effects can be obtained.

[0033] It is preferable that the target speed condition is set so that, when ground of a specified hardness on the softer side of the ground hardnesses specified in the hardness correspondence data is excavated by the specified excavation operation of the work attachment, the amount of soil excavated by the bucket corresponds to the maximum load that the bucket can hold.

[0034] According to this configuration, the accuracy of the estimation of the ground hardness by the hardness estimation unit can be further improved. That is, as the hardness of the ground becomes harder, the amount of soil excavated by the bucket also decreases. Therefore, if the amount of soil excavated when soft ground is excavated is small to begin with, the amount of soil excavated by the bucket becomes zero even if the hardness of the ground becomes slightly harder, and the above-mentioned estimation process of the ground hardness based on the weight of soil in the bucket cannot be executed. On the other hand, if the amount of soil excavated by the bucket when soft ground is excavated exceeds the maximum load capacity of the bucket (the load capacity in a heaped state where soil spills outside the bucket if more soil is loaded), some of the excavated soil spills out of the bucket, so the amount of soil held in the bucket is maintained at the maximum load capacity even if the ground hardness changes slightly. This causes a problem that the change in the ground hardness is not reflected in the weight of soil held in the bucket, and the ground hardness cannot be estimated accurately. Therefore, in this configuration, the target speed condition for performing the predetermined excavation operation is set so that the amount of soil excavated by the bucket when excavating ground of a predetermined hardness on the soft side of the hardness correspondence data corresponds to the maximum load that can be held in the bucket. This makes it possible to make the weight of soil held in the bucket by the predetermined excavation operation of the work attachment significantly different between when the ground is soft soil and when the ground is hard soil, thereby improving the accuracy of the estimation of the ground hardness by the hardness estimating unit.

[0035] It is preferable that the construction machine further includes an excavation time detection unit which detects the excavation time, which is the time required for the specified excavation operation, and the hardness estimation unit is configured to determine whether the weight of the soil detected by the weight detection unit is a specified weight or more after the specified excavation operation is performed by the work attachment, and if it is determined that the weight is less than the specified weight, to execute the estimation process to estimate the hardness of the ground based on the weight of the soil detected by the weight detection unit and the hardness correspondence data, while if it is determined that the weight is the specified weight or more, to execute the estimation process to estimate the hardness of the ground based on the excavation time detected by the excavation time detection unit.

[0036] According to this configuration, even if the ground hardness is excessively soft, the estimation accuracy of the ground hardness can be sufficiently ensured. That is, if the ground hardness is excessively soft, the amount of soil excavated by the bucket exceeds the maximum load that can be held in the bucket in the excavation completion posture, so even if the ground hardness changes, the weight of the soil held in the bucket remains constant and does not change because the excess falls off. For this reason, the estimation process based on the weight of soil held in the bucket described above cannot estimate the ground hardness with high accuracy. Therefore, in this configuration, when the weight of soil held in the bucket exceeds a predetermined weight (for example, a weight corresponding to the maximum load of the bucket) (that is, when the ground hardness is considered to be so soft that the weight of soil held in the bucket does not change even if the ground hardness changes), the estimation process of the ground hardness is performed based on the time required for the predetermined excavation operation. The excavation time required for the predetermined excavation operation is not limited by an upper limit value like the weight of soil held in the bucket, and the softer the ground hardness, the longer the excavation time. Therefore, when the ground hardness is excessively soft, the estimation accuracy can be improved by executing the ground hardness estimation process by the hardness estimating unit based on the excavation time in this manner.

[0037] The construction machine may further include a drive unit for driving the work attachment, and a control unit capable of generating a command signal for causing the work attachment to perform the specified excavation operation and executing control to input the generated command signal to the drive unit.

[0038] According to this configuration, by causing the control unit to execute the control, a command signal for causing the work attachment to execute a predetermined excavation operation is input to the drive unit. Therefore, for example, it is possible to cause the work attachment to automatically execute the predetermined excavation operation. When such automatic control is implemented, the work attachment can be operated without being influenced by the operation of the operator, so that the target speed condition can be reliably satisfied when executing the predetermined excavation operation, and thus the accuracy of the ground hardness estimation unit can be improved.

[0039] It is preferable that the construction machine further includes a communication unit that receives information on the ground hardness estimated by the hardness estimation unit and transmits the received hardness information to a management device provided at a location away from the construction machine.

[0040] According to this configuration, the information on the hardness of the ground transmitted from the communication unit to the management device can be utilized for reviewing the construction plan, managing the construction history, and the like. Effect of the Invention

[0041] According to the present invention, a construction machine capable of estimating ground hardness with high accuracy is provided. [Brief description of the drawings]

[0042] [Figure 1] FIG. 1 is a side view showing a construction machine according to a first embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing a hydraulic control circuit of the construction machine. [Diagram 3] 2 is a block diagram showing the configuration of a control system of the construction machine. FIG. [Figure 4A] FIG. 11 is an explanatory diagram for explaining a predetermined excavation operation by the work attachment, showing a state in which the work attachment is in an excavation start attitude. [Figure 4B] FIG. 1 is an explanatory diagram for explaining a predetermined excavation operation by a construction machine, showing a state in which a bucket of a work attachment is excavating soil and sand in the ground. [Figure 4C] FIG. 11 is an explanatory diagram for explaining a predetermined excavation operation by the construction machine, showing a state in which the work attachment is in an excavation completion attitude. [Diagram 5] 11 is a diagram showing dimensional information used in a moment balance equation when the weight of soil held in the bucket is calculated by the weight detection unit. FIG. [Figure 6] 1 is a diagram showing an example of hardness correspondence data that associates the weight of soil held in a bucket by a predetermined excavation operation of a work attachment with the hardness of the ground. FIG. [Figure 7A]FIG. 11 is an explanatory diagram illustrating that the amount of soil excavated by the bucket differs between soft soil and hard soil when a specified excavation operation is performed by a work attachment, and shows the excavation path when excavating soft soil with a dashed line. [Figure 7B] FIG. 11 is an explanatory diagram illustrating that the amount of soil excavated by the bucket differs between soft soil and hard soil when a specified excavation operation is performed by a work attachment, and shows the excavation path when excavating hard soil with a dashed line. [Figure 8] FIG. 4 is an explanatory diagram for explaining how to determine a target speed condition (in this example, the target speed of the composite center of gravity) when a predetermined excavation operation is performed by the work attachment. [Figure 9] 10 is a flowchart illustrating an example of a hardness estimation process executed by a controller. [Figure 10] FIG. 5 is a view corresponding to FIG. 3 and showing a modified example of the first embodiment. [Figure 11] FIG. 13 is a schematic diagram showing an example of a notification screen for notifying a deviation degree between a speed state of a work attachment and a target speed condition in a modified example of the first embodiment. [Figure 12] FIG. 5 is a view corresponding to FIG. 3 and showing a second embodiment. [Figure 13] FIG. 4 is a schematic diagram showing a change in cylinder load over time when a predetermined excavation operation is performed by the work attachment. [Figure 14] FIG. 10 is a view corresponding to FIG. 9 and shows a second embodiment. [Figure 15] FIG. 5 is a view corresponding to FIG. 3 and showing a third embodiment. [Figure 16] 5 is a diagram illustrating an example of operational data acquired by an operational data acquisition unit; FIG. [Figure 17] FIG. 10 is a view corresponding to FIG. 9 and shows a third embodiment. [Figure 18A] 13 is a graph showing an example of second hardness correspondence data. [Figure 18B] 13 is a graph showing an example of second hardness correspondence data. [Figure 18C] 13 is a graph showing an example of second hardness correspondence data. [Figure 19]FIG. 11 is a diagram showing an example of weighting coefficient data that defines weighting coefficients corresponding to each operating state-corresponding stiffness (second stiffness). [Figure 20] FIG. 13 is a diagram showing an example of data of the acquired results of hardness according to operating status. [Figure 21] FIG. 13 is a diagram showing an example of an information display screen. [Figure 22] FIG. 7 is a view corresponding to FIG. 6 and showing another modified embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0044] (First embodiment) FIG. 1 is a side view showing a hydraulic excavator 1 (construction machine) according to a first embodiment of the present invention. The hydraulic excavator 1 includes a crawler-type lower traveling body 10 capable of traveling on a traveling surface (the upper surface of the ground, i.e., the ground G), an upper rotating body 12 mounted on the lower traveling body 10 so as to be rotatable about a central axis of rotation perpendicular to the traveling surface, and a work attachment 20 (work device) mounted on the upper rotating body 12 so as to be capable of being raised and lowered. The work attachment 20 includes a boom 21 supported on the upper rotating body 12 so as to be capable of being raised and lowered, an arm 22 rotatably connected to the tip of the boom 21, and a bucket 23 (tip member) rotatably connected to the tip of the arm 22. The bucket 23 has a base end 23a connected to the arm 22 when viewed from the side, and a tip end 23b having a claw portion formed thereon. The upper rotating body 12 includes a revolving frame 121 and a cab 13. The lower running structure 10 and the upper rotating structure 12 constitute the machine body 1S.

[0045] The hydraulic excavator 1 includes a boom cylinder 21S that operates to raise and lower the boom 21 relative to the upper rotating body 12, an arm cylinder 22S that operates to rotate the arm 22 relative to the boom 21, and a bucket cylinder 23S that operates to rotate the bucket 23 relative to the arm 22. Each cylinder receives hydraulic oil from a hydraulic pump and operates to expand and contract.

[0046] 2 is a schematic diagram showing a hydraulic control circuit of a construction machine. In FIG. 2, g1 indicates the center of gravity of the boom 21, g2 indicates the center of gravity of the arm 22, g3 indicates the center of gravity of the bucket 23, and g indicates the combined center of gravity of the work attachment 20.

[0047] The hydraulic excavator 1 further includes an engine 100, a hydraulic first pump 2A and a hydraulic second pump 2B, a pilot pressure oil hydraulic pump 3, an operation unit 4, an electromagnetic proportional valve 5, a control valve 7, and a controller 50.

[0048] The engine 100 is controlled by an ECU 32 (described later) and rotates by receiving a predetermined injection amount of fuel. The first pump 2A and the second pump 2B are connected to an output shaft of the engine 100 and rotate by receiving the driving force of the engine 100. Each pump is a hydraulic pump and discharges hydraulic oil for operating the boom cylinder 21S, the arm cylinder 22S and the bucket cylinder 23S.

[0049] The boom cylinder 21S described above expands and contracts to raise (move) the boom 21 by receiving the hydraulic oil discharged by the first pump 2A. In this embodiment, the boom cylinder 21S has a cylinder body and a cylinder rod including a piston portion that divides the cylinder body into a head chamber and a rod chamber and that is movable relative to the cylinder body. The tip of the cylinder rod is connected to the boom 21 via a link mechanism (not shown). The boom cylinder 21S can extend to raise the boom 21 (boom-up operation) by receiving the hydraulic oil discharged by the first pump 2A into the head chamber via the control valve 7 and discharging the hydraulic oil from the rod chamber, while it can contract to lower the boom 21 (boom-down operation) by receiving the hydraulic oil discharged by the first pump 2A into the rod chamber via the control valve 7 and discharging the hydraulic oil from the head chamber. The arm cylinder 22S and the bucket cylinder 23S also have a structure similar to that of the boom cylinder 21S.

[0050] The operation unit 4 includes levers operated by an operator, and accepts manual operations for moving the boom 21, arm 22, and bucket 23 of the work attachment 20. That is, the operation unit 4 includes a boom operation unit, an arm operation unit, and a bucket operation unit. The operation direction and amount of each manual operation are variable. The operation unit 4 also accepts operations related to the rotation operation of the upper rotating body 12 and the traveling operation of the lower traveling body 10.

[0051] The control valve 7 is disposed between each hydraulic pump and the boom cylinder 21S, and has a spool that moves to change (control) the flow rate and flow path of the hydraulic oil supplied from each hydraulic pump to the boom cylinder 21S. Specifically, the control valve 7 mainly operates to supply hydraulic oil from the hydraulic pump to the boom cylinder 21S and to discharge hydraulic oil discharged from the boom cylinder 21S to a tank (not shown) when the boom 21 performs a boom-up operation and a boom-down operation. The control valve 7 is a pilot-operated three-position directional control valve having a pair of pilot ports.

[0052] When no pilot pressure is input to either of a pair of pilot ports, the control valve 7 is maintained in a neutral position, blocking communication between the hydraulic pump and the boom cylinder 21S.

[0053] When boom lowering pilot pressure is input to one pilot port, control valve 7 is switched from the neutral position to the boom lowering position with a stroke corresponding to the magnitude of the boom lowering pilot pressure. As a result, control valve 7 opens to allow hydraulic oil to be supplied from the hydraulic pump to the rod chamber of boom cylinder 21S at a flow rate corresponding to the stroke, and to allow hydraulic oil to be discharged from the head chamber of boom cylinder 21S. As a result, boom cylinder 21S is driven in the boom lowering direction at a speed corresponding to the boom lowering pilot pressure.

[0054] When boom-raising pilot pressure is input to another pilot port, control valve 7 is switched from the neutral position to the boom-raising position with a stroke corresponding to the magnitude of the boom-raising pilot pressure. As a result, control valve 7 opens to allow hydraulic oil to be supplied from the hydraulic pump to the head chamber of boom cylinder 21S at a flow rate corresponding to the stroke, and to allow hydraulic oil to be discharged from the rod chamber of boom cylinder 21S. As a result, boom cylinder 21S is driven in the boom-raising direction at a speed corresponding to the boom-raising pilot pressure.

[0055] A control valve 7 that performs the same operation as described above is disposed between each hydraulic pump and the arm cylinder 22S and between each hydraulic pump and the bucket cylinder 23S. The control valve 7 corresponding to the arm cylinder 22S can be switched between an arm pushing position, a neutral position, and an arm retracting position.

[0056] The solenoid proportional valve 5 opens so that a pilot pressure (secondary pressure) corresponding to an operation input to the operation unit 4 acts on each pilot port of the control valve 7 by pilot oil supplied from the pilot pressure oil hydraulic pump 3. The opening degree of the solenoid proportional valve 5 is adjusted by a proportional signal input from the controller 50. Note that in another embodiment, a remote control valve (not shown) that opens according to the angle of the lever of the operation unit 4 may transmit pressure to the control valve 7 as the secondary pressure. In this case, a proportional valve is provided between the lever and the control valve 7, and the secondary pressure may be adjusted by the proportional valve before it reaches the control valve 7.

[0057] As shown in FIG. 2, the boom cylinder 21S, the arm cylinder 22S, and the bucket cylinder 23S extend and retract by receiving hydraulic oil from the pumps 2A and 2B in response to an operation amount, which is the magnitude of the operation received by the operating unit 4. The boom cylinder 21S, the arm cylinder 22S, and the bucket cylinder 23S are supplied with hydraulic oil from the pumps 2A and 2B through a control valve 7 that switches the direction of the oil supply. In FIG. 2, the hydraulic circuit for moving the work attachment 20 and the engine 100 are collectively defined as the drive unit 30. The controller 50 inputs a command signal to the drive unit 30 in response to the operation amount. The controller 50 controls the drive of the work attachment 20 by controlling the hydraulic system shown in FIG. 2. The drive unit 30 has a function of moving each member of the work attachment 20 at a speed in response to a command signal (proportional signal) input to the solenoid proportional valve 5 to move the work attachment 20.

[0058] In this embodiment, the controller 50 measures or calculates the speed of the combined center of gravity of the boom 21, arm 22, and bucket 23 that constitute the work attachment 20, and determines (adjusts) a command signal for the electromagnetic proportional valve 5, which is part of the drive unit 30, using feedback control so that the speed follows a predetermined target value (satisfies the target speed condition).

[0059] FIG. 3 is a block diagram showing the configuration of the control system of the hydraulic excavator 1. In this embodiment, the controller 50 is mounted, for example, in a cab on the upper rotating body 12, and controls the overall operation of the hydraulic excavator 1. The controller 50 includes a computer, and each function is implemented by the computer executing a program. The computer includes a processor that operates according to the program as a main hardware configuration. The processor may be of any type as long as it can realize a function by executing a program, and may be configured with one or more electronic circuits including, for example, a semiconductor integrated circuit (IC) or an LSI (Large Scale Integration). The multiple electronic circuits may be integrated into one chip, or may be provided on multiple chips. The multiple chips may be integrated into one device, or may be provided on multiple devices. The program is recorded on a non-transitory recording medium such as a computer-readable ROM, an optical disk, or a hard disk drive. The program may be stored in the recording medium in advance, or may be supplied to the recording medium via a wide area communication network including the Internet. Details of the functions realized by the controller 50 will be described later.

[0060] The controller 50 is connected to the operation unit 4, the input unit 6, the attitude detection unit 31, an ECU (Engine Control Unit) 32, an IMU (Inertial Measurement Unit) 33, a display unit 34, and the electromagnetic proportional valve 5 so as to be able to send and receive signals.

[0061] The input unit 6 is provided in the cab 13, and accepts input of information necessary for control executed by the controller 50. The input unit 6 includes a mode setting input unit 6a. The mode setting input unit 6a includes a switch that can be manually operated by an operator, and is configured so that the current operation mode can be set to either a normal operation mode or a hardness estimation mode for estimating the hardness of the ground by operating the switch. The mode setting input unit 6a transmits the set mode information to the controller 50.

[0062] The posture detection unit 31 detects information related to the posture of the work attachment 20. More specifically, the posture detection unit 31 acquires information on the relative posture of the work attachment 20 with respect to the upper revolving body 12. As an example, the posture detection unit 31 includes three sensors attached to the boom cylinder 21S, the arm cylinder 22S, and the bucket cylinder 23S, respectively, and detects the stroke (extension amount, length) of each cylinder. The stroke of each cylinder detected by each sensor is used to calculate the position and posture of the boom 21, the arm 22, and the bucket 23, and is further used to calculate the position and speed Vg (see FIG. 2) of the composite center of gravity g of the work attachment 20. Note that, in order to calculate the position and posture of the boom 21, the arm 22, and the bucket 23, angle sensors that detect the rotation angles of the boom 21, the arm 22, and the bucket 23, respectively, may be used instead of the cylinder stroke sensors.

[0063] The ECU 32 receives a rotation speed command signal from the controller 50 and controls the engine 100 so as to rotate the engine 100 with a fuel injection amount according to the rotation speed command signal.

[0064] The IMU 33 detects information related to the attitude of the upper rotating body 12 with respect to the ground G. That is, the IMU 33 detects the attitude angle (inclination) of the body 1S of the hydraulic excavator 1. As an example, the IMU 33 is attached to the upper surface of the cab 13.

[0065] The display unit 34 is a liquid crystal display provided inside the cab 13, and displays various information such as the operating status of the hydraulic excavator 1 and the hardness of the ground estimated in the hardness estimation mode to inform the operator.

[0066] The controller 50 is composed of a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores a control program, a RAM (Random Access Memory) used as a working area for the CPU, and the like. The controller 50 has an attachment control unit 501, a weight detection unit 502, a hardness estimation unit 503, a storage unit 504, and a communication unit 505. The attachment control unit 501, the weight detection unit 502, and the hardness estimation unit 503 are functional units that are realized by the CPU executing the control program, the storage unit 504 is a functional unit that is realized by a non-transitory recording medium such as a ROM or a hard disk, and the communication unit 505 is a functional unit that is realized by a wireless communication device having a wireless LAN chip or the like. All or a part of the controller 50 is not limited to being provided within the hydraulic excavator 1, and may be disposed in a position different from the hydraulic excavator 1 when the hydraulic excavator 1 is remotely controlled. In addition, the control program may be transmitted to the controller 50 in the hydraulic excavator 1 from a remote server (which may be the server 35 described later) or the cloud and executed therein, or the control program may be executed on the server or cloud, and various command signals generated may be transmitted to the hydraulic excavator 1.

[0067] When the operator operates the operation unit 4 to cause the work attachment 20 to perform a predetermined excavation operation, the attachment control unit 501 calculates the resultant center-of-gravity velocity Vg of the work attachment 20 based on information from the attitude detection unit 31, and executes feedback control to adjust the boom input to the electromagnetic proportional valve 5 so that the calculated resultant center-of-gravity velocity Vg follows (approaches) the target center-of-gravity velocity r. The attachment control unit 501 functions as a speed state detection unit and a control unit of the present invention.

[0068] Specifically, as shown in Figs. 1 and 2, the pivot base end of the boom 21 of the work attachment 20 is set as the origin 0, the Y coordinate is taken in the vertical direction, and the X coordinate is taken in the horizontal direction. The mass of the boom 21 is defined as m1, the coordinates of the center of gravity g1 of the boom 21 as (x1(t), y1(t)), the mass of the arm 22 as m2, the coordinates of the center of gravity g2 of the arm 22 as (x2(t), y2(t)), the mass of the bucket 23 as m3, and the coordinates of the center of gravity g3 of the bucket 23 as (x3(t), y3(t)). Note that each coordinate changes as the work attachment 20 operates, and is therefore expressed as a variable of time t. In this case, the coordinates (xg(t), yg(t)) of the composite center of gravity g of the work attachment 20 can be expressed by the following equation 1.

[0069]

number

[0070] Furthermore, using equation 1, the velocity Vg(t) of the composite center of gravity g can be expressed by the following equation 2.

[0071]

number

[0072] The attachment control unit 501 adjusts the input u(t) of the boom operation during a predetermined excavation operation so that the resultant center-of-gravity velocity Vg(t) follows the target center-of-gravity velocity r(t). The input u(t) corresponds to a proportional signal input to the electromagnetic proportional valve 5. A PID (Proportional Integral Differential) control law can be used as the adjustment law for the input u(t). Note that uh(t) is the amount of boom operation by the operator, and uc(t) is the amount of boom operation set by the attachment control unit 501 of the controller 50.

[0073]

number

[0074]

number

[0075]

number

[0076] Here, in the PID control law shown in equation 4, Kp1 indicates a proportional gain, Ki1 indicates an integral gain, and Kd1 indicates a differential gain, and the input uc(t), i.e., the amount of boom operation, is adjusted according to the control deviation e(t).

[0077] The predetermined excavation operation is an excavation operation in which the posture of the work attachment 20 is changed from a predetermined excavation start posture to an excavation completion posture so as to satisfy a target speed condition (in this example, a condition that the combined center-of-gravity velocity Vg of the work attachment 20 is constant (=target center-of-gravity velocity r)). Figures 4A to 4C are explanatory diagrams for explaining this predetermined excavation operation, with Figure 4A showing a state in which the work attachment 20 is in the excavation start posture, Figure 4B showing a state in which the bucket 23 of the work attachment 20 is excavating soil and sand from the ground, and Figure 4C showing a state in which the work attachment 20 is in the excavation completion posture.

[0078] The excavation start posture is, for example, a maximum reach posture (a state in which the boom 21 and the arm 22 are most extended) in which the horizontal length of the boom 21 and the arm 22 is the longest, and the ground angle of the bucket 23 (the angle between the tip 23b (claw) of the bucket 23 and the ground G) is, for example, 70° to 120° (see FIG. 4A). When a predetermined excavation operation starts from the excavation start posture, the tilt angle of the boom 21 increases, and the arm 22 rotates so as to approach the boom 21, and the bucket 23 rotates in the counterclockwise direction in the figure with its base end 23a as a fulcrum (see FIG. 4B). As a result, the tip 23b of the bucket 23 penetrates (penetrates) into the ground, and the entire bucket 23 rotates with the base end 23a as a fulcrum, and the soil constituting the ground excavated by the tip 23b of the bucket 23 is guided into the bucket 23. At this time, the operation of the boom 21 is controlled by the controller 50 so that the speed Vg of the combined center of gravity g of the work attachment 20 is maintained at the target center-of-gravity speed r (see the black arrow in FIG. 4B). Then, after the bucket 23 rotates and its tip 23b breaks through the ground, it transitions to an excavation completion posture (see FIG. 4C). In the excavation completion posture, the opening of the bucket 23 faces upward, and the excavated soil E is held in the bucket 23.

[0079] Weight detection unit 502 detects (calculates) the weight of the soil held in bucket 23 based on the detection information by attitude detection unit 31. This "weight" includes both the meaning of "mass" and the meaning of "load", and may have either meaning. In other words, weight detection unit 502 may detect the mass of soil, or may detect the load. In this embodiment, the mass of soil is calculated as an example in (Equation 6) described later.

[0080] The weight detection unit 502 calculates the weight of the soil from a balance equation of the moment about the rotation fulcrum S at the base end of the boom 21, based on prestored dimensional information and weight information of the work attachment 20, the load on the boom cylinder 21S measured by a sensor (not shown, for example a load cell or pressure sensor), and the attitude of the work attachment 20 detected by the attitude detection unit 31. Fig. 5 is a diagram showing dimensional information used in this balance equation of the moment, in which the horizontal distance between the combined center of gravity g of the work attachment 20 in the excavation completion attitude and the rotation fulcrum S is indicated as L1, the horizontal distance between the position of the center of gravity of the soil (assumed to be the central position between the front and rear of the bucket 23) and the rotation fulcrum S is indicated as L2, and the distance between the axis of the boom cylinder 21S and the rotation fulcrum S is indicated as L3. Here, if the thrust of boom cylinder 21S is F1 (N), the weight of work attachment 20 (here, as an example, the cylinder weight is not included because it can be ignored), is F2 (kg), and the weight of soil E held in bucket 23 is X (kg), then the weight of soil E (kg) is expressed by the following equation 6 based on the balance of moments. Weight detection unit 502 calculates the weight of the soil held in bucket 23 (mass in this example) by performing calculations based on this equation 6.

[0081] X=(F1*L3-F2*g*L1) / (g*L2)…………(Formula 6) Note that "g" in this equation 6 refers to the acceleration due to gravity and does not mean the composite center of gravity mentioned above.

[0082] When the hardness estimation mode is set by the mode setting input unit 6a, after the above-mentioned specified excavation operation is performed by the work attachment 20, the hardness estimation unit 503 estimates the hardness of the ground based on the weight of the soil E on the bucket 23 detected by the weight detection unit 502 and hardness correspondence data D (see Figure 6 described later) that corresponds the weight of the soil E to the hardness of the ground.

[0083] The storage unit 504 stores parameters and thresholds required for various processes executed by the controller 50. The storage unit 504 also stores hardness correspondence data D that associates the weight of soil E excavated and held by the bucket 23 when the work attachment 20 executes a predetermined excavation operation with the hardness of the ground.

[0084] 6 is a diagram showing an example of hardness correspondence data D. In this hardness correspondence data D, the relationship between the weight of the soil E held in the bucket 23 and the hardness of the ground is defined by a linear first-order approximation line I. In this example, the hardness correspondence data D is graph data with the weight of the soil E held in the bucket 23 on the horizontal axis and the hardness of the ground on the vertical axis, but the data format is not limited to this and may be, for example, table data. It can also be said that the hardness correspondence data D is data that defines the change in weight of the soil E due to differences in ground hardness.

[0085] The hardness of the ground on the vertical axis can be expressed, for example, by the penetration resistance value obtained by a penetration test using a cone penetrometer, or the N value measured by a sounding test, but is not limited to these. For example, it may be expressed by the shear strength obtained by a shear strength test, or it may be expressed by a hardness level divided into stages as described in other embodiments below.

[0086] This hardness correspondence data D is created, for example, based on an excavation test conducted by the manufacturer before the hydraulic excavator 1 is shipped to the market. In this excavation test, for example, the above-mentioned predetermined excavation operation is performed by the working attachment 20 on multiple types of ground with different hardness. At this time, it is preferable that the ground on which the hydraulic excavator 1 is placed is level without inclination. The predetermined excavation operation by the working attachment 20 is performed by the operator operating the operation unit 4 so as to satisfy the target speed condition (in this example, so that the combined center-of-gravity speed Vg of the working attachment 20 becomes constant (= target center-of-gravity speed r)). At this time, it is preferable to turn on (enable) the feedback control function (function of adjusting the boom input to the electromagnetic proportional valve 5) by the attachment control unit 501 described above. Then, when the predetermined excavation operation is performed on multiple types of ground with different hardness (in this example, three types corresponding to the three data points P1 to P3 in FIG. 6), the weight detection unit 502 detects the weight of the soil E excavated and held by the bucket 23. Then, multiple data points P1-P3 that correspond to the detected weight of soil E and the hardness of the ground are plotted on a coordinate plane, and an approximation method such as the least squares method is used to calculate an approximation line I that best fits these multiple data points P1-3, thereby obtaining the hardness correspondence data D shown in Fig. 6. Note that in this example, the data points P1-P3 are based on the data points, but the number is not limited to three and may be two or more. Also, the approximation of the data points does not necessarily have to be a straight line, and may be a quadratic or higher order approximation curve.

[0087] The communication unit 505 transmits information on the hardness of the ground estimated by the hardness estimation unit 503 to the server 35 (an example of a management device). The information on the hardness of the ground transmitted to the server 35 can be viewed, for example, from another external terminal (for example, a personal computer or a smartphone) configured to be able to communicate with the server 35, and is used for reviewing the construction plan, managing the construction history, and the like.

[0088] Incidentally, the above-mentioned hardness correspondence data D (see FIG. 6) shows the characteristic that when the ground is hard, the weight of the soil E excavated and held by the bucket 23 is small, and when the ground is soft, the weight of the soil E excavated and held by the bucket 23 is large. However, such a characteristic is knowledge gained through intensive research into the invention, etc., and the reason for obtaining such a characteristic will be explained below with reference to FIG. 7A and FIG. 7B.

[0089] 7A and 7B are schematic diagrams showing, by dashed lines, the excavation path of the bucket 23 when the work attachment 20 performs a predetermined excavation operation.

[0090] In the predetermined excavation operation for hard soil shown in Fig. 7B, it can be seen that the depth A from the ground of the excavation path (path indicated by the dashed line) by the bucket 23 is shallower than that in the predetermined excavation operation for soft soil shown in Fig. 7A. That is, when excavation is performed by keeping the composite center-of-gravity velocity Vg of the working attachment 20 constant regardless of the hardness of the ground as in this embodiment (when performing a predetermined excavation operation that satisfies the target speed condition), the excavation resistance acting on the bucket 23 is higher in hard soil than in soft soil, so the speed of the arm 22 decreases early. Therefore, in order to compensate for the decrease in the composite center-of-gravity velocity Vg of the working attachment 20 caused by the decrease in the speed of the arm 22 (to make the composite center-of-gravity velocity Vg follow the target center-of-gravity velocity r), the boom 21 is rotated in the clockwise direction in the figure to pull the tip of the boom 21 upward (see the black arrow in Fig. 4B described above). As a result, the excavation resistance acting on bucket 23 decreases and the resultant center-of-gravity velocity Vg tracks the target center-of-gravity velocity r, but at this time, the excavation trajectory of bucket 23 shifts upward overall. As a result, in hard soil, excavation depth A by bucket 23 is shallower than in soft soil, and excavation distance B in the front-to-rear direction (left-to-right direction in Figs. 7A and 7B) is shorter, so the weight of soil E held by bucket 23 also decreases (see Fig. 7B).

[0091] In this embodiment, by performing a predetermined excavation operation so as to maintain the composite center-of-gravity velocity Vg of the work attachment 20 constant (=target center-of-gravity velocity r), the weight of the soil E held in the bucket 23 after the excavation operation is changed. The inventors have focused on this fact and estimated the hardness of the ground based on the above-mentioned hardness correspondence data D that associates the weight of the soil E with the hardness of the ground. The inventors have come to the conclusion that, from the viewpoint of improving the estimation accuracy, when estimating the hardness of the ground based on the weight of the soil E held in the bucket 23 in this way, it is preferable that the weight of the soil held in the bucket 23 be clearly different between when hard ground is excavated and when soft ground is excavated, and have devised a way to set the target center-of-gravity velocity r to make this possible.

[0092] FIG. 8 is an explanatory diagram for explaining the procedure for setting the target center-of-gravity velocity r. When setting the target center-of-gravity velocity r, for example, a ground corresponding to the softest hardness h1 (an example of a predetermined hardness) among the hardness range (h1 to h2 range in FIG. 6) defined in the hardness correspondence data D is prepared, and the target center-of-gravity velocity r is changed to a plurality of stages (three stages of high speed, medium speed, and low speed in the example of FIG. 8) for the ground, and a predetermined excavation operation is performed by the working attachment 20 for each target center-of-gravity velocity. In FIG. 8, the dashed lines K1, K2, and K3 show the excavation trajectory of the bucket 23 when the target center-of-gravity velocity r is high speed, medium speed, and low speed, respectively. As can be seen from FIG. 8, the excavation trajectory of the bucket 23 changes for each target center-of-gravity velocity r. Specifically, in the example of FIG. 8, in the excavation trajectory K1 where the target center of gravity speed r corresponds to a high speed, the amount of soil excavated by the bucket 23 falls below the maximum load that can be held by the bucket 23, and in the excavation trajectory K3 where the target center of gravity speed r corresponds to a low speed, the amount of soil excavated by the bucket 23 exceeds the maximum load of the bucket 23 (a part of the soil spills out from the bucket 23), whereas in the excavation trajectory K2 where the target center of gravity speed r corresponds to a medium speed, the amount of soil excavated by the bucket 23 corresponds to the maximum load of the bucket 23. Here, the "amount corresponding to the maximum load" is not limited to the case where the amount of soil excavated is exactly the same as the maximum load, and may include an error above and below. In this embodiment, by actually performing an excavation test in this manner, a target center of gravity speed r is found such that the amount of soil excavated by the bucket 23 corresponds to the maximum load, and this target center of gravity speed r is set as the target center of gravity speed r of the work attachment 20 when the hardness estimation mode is set. The target center-of-gravity velocity r thus set is stored in the memory unit 504 and used as the above-mentioned target center-of-gravity velocity r of the work attachment 20. According to this, when the work attachment 20 is caused to perform a predetermined excavation operation to excavate soft ground and hard ground, respectively, the weight of the soil E excavated and held in the bucket 23 can be made to differ greatly between the soft soil and the hard soil. Therefore, the hardness estimation process of this embodiment based on the weight of the soil E excavated and held in the bucket 23 can be executed with high accuracy.

[0093] FIG. 9 is a flowchart showing the contents of the hardness estimation process executed by the controller 50.

[0094] In step SA1, based on the mode setting information from the mode setting input unit 6a, the hardness estimation unit 503 determines whether or not the hardness estimation mode is set as the current operation mode of the hydraulic excavator 1. Then, if the hardness estimation unit 503 determines that the hardness estimation mode is not set (NO in step SA1), it returns, whereas if it determines that the hardness estimation mode is set (YES in step SA1), it proceeds to step SA2.

[0095] In step SA2, the hardness estimation unit 503 judges whether the work attachment 20 is in the excavation start posture (see FIG. 4A) based on the posture information of the work attachment 20 detected by the posture detection unit 31, and if it is judged that the work attachment 20 is not in the excavation start posture (NO in step SA2), it is presumed that the operator has not performed an operation for a predetermined excavation operation, so the process returns. On the other hand, if the hardness estimation unit 503 judges that the work attachment 20 is in the excavation start posture (YES in step SA2), it is presumed that the operator has started an operation for a predetermined excavation operation, so the process proceeds to step SA3.

[0096] In step SA3, the hardness estimation unit 503 determines whether the work attachment 20 is in the excavation completion posture (see Figure 4C) based on the posture information of the work attachment 20 detected by the posture detection unit 31. If it is determined that the posture of the work attachment 20 is not in the excavation completion posture (NO in step SA3), it is presumed that the work attachment 20 is in the middle of performing the specified excavation operation, and the determination process of this step SA3 is repeated until the specified excavation operation is completed. On the other hand, if it is determined that the work attachment 20 is in the excavation completion posture (YES in step SA3), it is presumed that the specified excavation operation has been completed, and the process proceeds to step SA4.

[0097] In step SA4, the weight detection unit 502 detects the weight of the earth and sand E held in the bucket 23.

[0098] In step SA5, the hardness estimation unit 503 judges whether or not the predetermined excavation operation by the working attachment 20 has been performed correctly. That is, for example, if the working attachment 20 is displaced without satisfying the target speed condition due to an operation error by the operator, the weight of the soil E excavated and held by the bucket 23 (i.e., the weight of the soil E detected in step SA4) may not satisfy the expected weight range of the soil E (for example, the range of the minimum soil weight w1 to the maximum soil weight w2 of the hardness correspondence data D (see FIG. 6)). In such a case, it is judged that the predetermined excavation operation has not been performed correctly. An example of an incorrect predetermined excavation operation is an empty excavation state in which the bucket 23 rotates in the air. Note that the judgment of whether or not the predetermined excavation operation has been performed correctly does not necessarily need to be based on the weight of the soil E held by the bucket 23, and may be based on, for example, whether or not the time waveform of the cylinder load (for example, the load of the bucket cylinder 23S) after the start of the excavation operation deviates by a predetermined amount or more from a predetermined reference waveform. Then, in the judgment process of this step SA5, if the hardness estimation unit 503 determines that the specified excavation operation by the work attachment 20 was not performed correctly, the process returns, whereas if the hardness estimation unit 503 determines that the specified excavation operation was performed correctly, the process proceeds to step SA6.

[0099] In step SA6, the hardness of the ground is estimated based on the weight of the soil E on the bucket 23 detected by the weight detection unit 502 in step SA4 and the hardness correspondence data D (see FIG. 6) stored in the memory unit 504. As an example, if the weight of the soil E detected by the weight detection unit 502 is w3 (see FIG. 6), the hardness estimation unit 503 substitutes the weight w3 into the approximation equation expressing the approximation line I of the hardness correspondence data D to calculate (estimate) hardness h3 as the hardness of the ground.

[0100] [Effects of the first embodiment] As described above, in this embodiment, the hydraulic excavator 1 is equipped with a weight detection unit 502 capable of detecting the weight of the soil E held in the bucket 23, and a hardness estimation unit 503 for estimating the hardness of the ground, and when estimating the hardness of the ground, the hardness estimation unit 503 is configured to estimate the hardness of the ground based on the weight of the soil E detected by the weight detection unit 502 and hardness correspondence data D that specifies the change in the weight of the soil E due to differences in ground hardness after a predetermined excavation operation is performed in which the work attachment 20 changes its posture from the excavation start posture to the excavation completion posture capable of holding the soil E after excavation while satisfying the target speed condition.

[0101] This configuration can reduce the risk of misjudgment and improve the accuracy of ground estimation, compared to the conventional method of discriminating the characteristics of the waveform detected by the sensor through complex arithmetic processing. Also, this configuration can estimate the ground hardness with high resolution by using the approximate straight line I to associate the soil weight specified in the hardness correspondence data D with the ground hardness. Moreover, this configuration can incorporate the predetermined excavation operation into the normal excavation work performed by the work attachment 20 to estimate the ground hardness by the hardness estimation unit 503, so that a dedicated operation just for estimating the ground hardness is not required, and the excavation work by the work attachment 20 can be performed efficiently.

[0102] In this embodiment, the target speed condition when the work attachment 20 performs a specified excavation operation is a condition that the combined center of gravity speed of the boom 21, arm 22, and bucket 23 that constitute the work attachment 20 is constant (= target center of gravity speed).

[0103] In this configuration, focusing on the fact that the excavation operation by the work attachment 20 is performed by cooperation between the boom 21, the arm 22, and the bucket 23, when the hardness estimation unit 503 estimates the hardness of the ground, the work attachment 20 is caused to perform a predetermined excavation operation so that the composite center-of-gravity velocity Vg of the boom 21, the arm 22, and the bucket 23 is constant, thereby making it possible to stably (evenly) excavate the ground by the bucket 23. This ensures the reproducibility of the weight of soil held in the bucket 23 after the predetermined excavation operation (the reproducibility of the weight of soil when an excavation operation is performed under the same speed conditions on ground of the same hardness), thereby improving the accuracy of the estimation of the ground hardness by the hardness estimation unit 503.

[0104] In this embodiment, while the work attachment 20 is performing the specified excavation operation, the controller 50 is configured to calculate (detect) the combined center of gravity velocity Vg of the boom 21, arm 22 and bucket 23 that constitute the work attachment 20, determine a command signal to the drive unit 30 (more specifically, the electromagnetic proportional valve 5 of the drive unit 30) so that the velocity Vg follows the target center of gravity velocity r (so as to satisfy the target velocity condition), and transmit the determined command signal to the drive unit 30.

[0105] According to this configuration, it is possible to prevent the resultant center-of-gravity velocity Vg of the work attachment 20 from deviating from the target center-of-gravity velocity r due to variations in the operator's manual operation, etc., thereby stabilizing the operation of the work attachment 20.

[0106] In this embodiment, the target center of gravity speed r (an example of a target speed condition) of the work attachment 20 is set so that when the softest ground (an example of a specified hardness) defined in the hardness correspondence data D is excavated by the specified excavation operation of the work attachment 20, the amount of soil excavated by the bucket 23 corresponds to the maximum load that can be held by the bucket 23.

[0107] According to this configuration, the weight of the soil E held in the bucket 23 by the specified excavation operation of the work attachment 20 can be made to differ greatly between when the ground is soft and when it is hard, thereby improving the accuracy of the estimation of ground hardness by the hardness estimation unit 503.

[0108] In addition, in this embodiment, when the specified excavation operation is performed by the work attachment 20, the hardness estimation unit 503 is configured to determine whether the specified excavation operation has been performed correctly or not, and if it is determined that the specified excavation operation has not been performed correctly, not to execute the ground hardness estimation process.

[0109] According to this configuration, if the specified excavation operation is not performed correctly by the work attachment 20, the estimation process by the hardness estimation unit 503 is not performed, thereby preventing erroneous estimation of ground hardness by the hardness estimation unit 503.

[0110] Moreover, in this embodiment, the hydraulic excavator 1 has a communication unit 505, which is configured to receive information on the ground hardness estimated by the hardness estimation unit 503 and transmit the received hardness information to a server 35 provided at a location away from the hydraulic excavator 1.

[0111] According to this configuration, the information on the hardness of the ground transmitted from the communication unit 505 to the server 35 can be utilized for reviewing the construction plan, managing the construction history, and the like.

[0112] (Modification of the first embodiment) Fig. 10 is a view equivalent to Fig. 3 showing a modified example of the first embodiment. This modified example differs from the first embodiment in that the controller 50 further includes a deviation calculation unit 506, and the deviation between the resultant center-of-gravity velocity Vg of the work attachment 20 and the target center-of-gravity velocity r calculated by the deviation calculation unit 506 is displayed on the display unit 34. In the following modified examples and embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0113] The deviation calculation unit 506 calculates the resultant center-of-gravity velocity Vg of the work attachment 20 while the work attachment 20 is performing a predetermined excavation operation, and calculates the deviation between the calculated resultant center-of-gravity velocity Vg and a target center-of-gravity velocity r. Here, the deviation may be, for example, a differential speed value between the resultant center-of-gravity velocity Vg and the target center-of-gravity velocity r, or may be a level of magnitude of the resultant center-of-gravity velocity Vg based on the target center-of-gravity velocity. In this modification, the deviation calculation unit 506 adopts the latter and calculates the level of magnitude of the resultant center-of-gravity velocity based on the target velocity as the deviation.

[0114] Then, the deviation calculation unit 506 visually notifies the operator of the deviation by displaying a notification screen 34a for notifying information related to the calculated deviation on the display unit 34. The display unit 34 functions as a notification unit.

[0115] 11 is a schematic diagram showing an example of the notification screen 34a displayed on the display unit 34. The notification screen 34a displays a deviation degree display meter 34b and an operation message area 34c.

[0116] The deviation degree display meter 34b is a vertically long rectangular level meter, and is divided into an upper region and a lower region of a reference line 34d corresponding to the target center-of-gravity speed. The region above the reference line 34d in the deviation degree display meter 34b means that the composite center-of-gravity speed Vg of the work attachment 20 is faster than the target center-of-gravity speed r, and the upper region means that the composite center-of-gravity speed Vg is faster (i.e., the deviation from the target center-of-gravity speed r is greater). The region below the reference line 34d in the deviation degree display meter 34b means that the composite center-of-gravity speed Vg of the work attachment 20 is slower than the target center-of-gravity speed r, and the lower region means that the composite center-of-gravity speed Vg is slower (i.e., the deviation from the target center-of-gravity speed r is greater).

[0117] A triangular indication mark 34e is displayed on the right side of the deviation degree display meter 34b, and the apex of this indication mark 34e indicates the level of the current resultant center-of-gravity velocity Vg, thereby notifying the operator of the deviation degree between the current resultant center-of-gravity velocity Vg and the target center-of-gravity velocity r.

[0118] The operation message area 34c is an area for notifying the operator in the form of a message of the operation required to reduce the deviation between the resultant center of gravity velocity Vg of the work attachment 20 and the target center of gravity velocity r (to bring the resultant center of gravity velocity closer to the target center of gravity velocity).

[0119] Specifically, in the operation message area 34c, the instruction message "Please excavate using only the arm and bucket" and the instruction message "Please raise the boom" are displayed side by side in two rows, one above the other. Check boxes 34f and 34g are displayed to the left of each message, and of the two check boxes 34f and 34g, the check box corresponding to the operation required of the operator is displayed as a black circle.

[0120] In the example of FIG. 11, the instruction mark 34e points to an area below the reference line 34d on the deviation degree display meter 34b, so it can be seen that the resultant center-of-gravity velocity Vg of the work attachment 20 is below the target center-of-gravity velocity r. In a situation in which the resultant center-of-gravity velocity Vg is below the target center-of-gravity velocity r, as mentioned in the explanation of FIG. 7A and FIG. 7B above, it is necessary to raise the boom 21 (increase the tilt angle) to bring the resultant center-of-gravity velocity Vg closer to the target center-of-gravity velocity r. Therefore, in the operation message area 34c of the notification screen 34a, the check box 34g corresponding to the instruction message "Raise the boom" is displayed as a black circle. Therefore, the operator can recognize that an operation to raise the boom 21 is necessary by seeing the state in which the check box 34g is displayed as a black circle (checked state).

[0121] (Functions and Effects of the Modification of the First Embodiment) As described above, in this modification, the hydraulic excavator 1 is provided with a deviation calculation unit 506 that detects the resultant center-of-gravity velocity Vg (an example of a speed state) while the work attachment 20 is performing a predetermined excavation operation and calculates information relating to the deviation between the detected resultant center-of-gravity velocity Vg and the target center-of-gravity velocity r, and a display unit 34 (an example of a notification unit) that displays the information relating to the deviation calculated by the deviation calculation unit 506. A notification screen 34a including the information relating to the deviation is displayed on the display unit 34.

[0122] According to this configuration, the operator can recognize how much the combined center-of-gravity velocity Vg of the work attachment 20 deviates from the target center-of-gravity velocity r by looking at the notification screen 34a displayed on the display unit 34 while the work attachment 20 is performing a predetermined excavation operation. Then, based on this recognition, the operator can correct his / her own manual operation so that the combined center-of-gravity velocity Vg of the work attachment 20 becomes the target center-of-gravity velocity r. Therefore, it is possible to prevent the combined center-of-gravity velocity Vg of the work attachment 20 from varying due to the operator's manual operation. In turn, it is possible to improve the reproducibility of the weight of the soil E excavated and held in the bucket 23 by the predetermined excavation operation by the work attachment 20, and further improve the accuracy of the estimation of the ground hardness by the hardness estimation unit 503.

[0123] In this modification, the deviation calculation unit 506 is configured to execute a process of calculating the composite center-of-gravity velocity Vg of the work attachment 20, but is not limited thereto, and may be configured, for example, to receive information on the composite center-of-gravity velocity of the work attachment 20 calculated by the attachment control unit 501 and calculate the deviation between the received composite center-of-gravity velocity Vg and a target center-of-gravity velocity r. In this case, the attachment control unit 501 assumes part of the function of the deviation calculation unit 506 (the function of calculating the composite center-of-gravity velocity), and such an embodiment may be adopted.

[0124] In addition, in this modified example, the notification unit is configured by the display unit 34 that visually notifies the operator of the information related to the deviation calculated by the deviation calculation unit 506, but is not limited to this. For example, the notification unit may be configured to audibly notify the operator of the information related to the deviation using a speaker or the like.

[0125] Second embodiment Fig. 12 is a diagram showing a second embodiment, which corresponds to Fig. 3. In this embodiment, the controller 50 further includes an excavation time detection unit 507, and differs from the first embodiment in that a process for estimating ground hardness based on the weight of soil E detected by the weight detection unit 502 and a process for estimating ground hardness based on the excavation time detected by the excavation time detection unit 507 are used in combination.

[0126] The digging time detection unit 507 detects the time required for the work attachment 20 to perform the specified digging operation (i.e., the time from the start of the digging operation from the digging start posture until the digging completion posture is reached). As one example, the digging time detection unit 507 detects the time required for the specified digging operation based on a change in cylinder load over time. As this cylinder load, any one of the load of the boom cylinder 21S, the load of the arm cylinder 22S, and the load of the bucket cylinder 23S can be adopted. In this embodiment, for example, the load of the arm cylinder 22S is detected as the cylinder load.

[0127] FIG. 13 is a graph showing an example of a change over time in the cylinder load (the load on the arm cylinder 22S in this embodiment) associated with the execution of a predetermined excavation operation by the work attachment 20. In FIG.

[0128] At time T1, the tip 23b of the bucket 23 comes into contact with the ground G as the work attachment 20 takes the excavation start posture, and as a result, the cylinder load of the arm cylinder 22S rises in a single go to U1. Next, when the work attachment 20 starts the predetermined excavation operation from the excavation start posture, the excavation resistance acting on the bucket 23 gradually increases as the bucket 23 rotates about the base end 23a as a fulcrum, and the cylinder load gradually increases from U1 to U2. Thereafter, the entire bucket 23 moves above the ground G and the work attachment 20 takes the excavation completion posture, and at the same time, the cylinder load drops in a single go to U3, and thereafter is maintained constant at a cylinder load that balances the weight of the soil E held in the bucket 23.

[0129] The excavation time detection unit 507 monitors the cylinder load of the arm 22 with a sensor (e.g., a load cell or a pressure sensor) not shown, and thereby acquires the time waveform of the cylinder load shown in Fig. 13 described above. Then, based on the acquired time waveform of the cylinder load, the excavation time detection unit 507 detects (calculates) the time from the time T1 to the time T2 (=T2-T1) as the excavation time, which is the time required for the work attachment 20 to perform a predetermined excavation operation.

[0130] FIG. 14 is a flowchart showing an example of a hardness estimation process executed by the controller 50 in the second embodiment.

[0131] The processes from step SB1 to step SB5 are the same as those from step SA1 to step SA5 in the first embodiment, and the processes from step SB6 onwards are different from those in the first embodiment. In the following, only the processes from step SB6 onwards will be described, and the description of the previous steps SB1 to SB5 will be omitted.

[0132] That is, in step SB6, hardness estimation unit 503 determines whether the weight of soil E in bucket 23 detected by weight detection unit 502 in the processing of step SB4 is less than a predetermined weight. Here, the predetermined weight is, for example, a weight corresponding to the maximum load of soil E in bucket 23 (a piled-up state in which soil would spill out of bucket 23 if more soil was loaded), and in this embodiment, it corresponds to, for example, the maximum soil weight w2 specified in hardness correspondence data D.

[0133] Then, if the hardness estimation unit 503 determines that the weight of the soil E in the bucket 23 detected by the weight detection unit 502 is less than the predetermined weight (YES in step SB6), the process proceeds to step SB7, and as in the first embodiment, the hardness estimation unit 503 estimates the hardness of the ground based on the weight of the soil E detected by the weight detection unit 502 and the hardness correspondence data D (step SB7), and then returns.

[0134] On the other hand, if the hardness estimation unit 503 determines that the weight of the soil E in the bucket 23 detected by the weight detection unit 502 is equal to or greater than the specified weight (NO in step SB6), the process proceeds to step SB8, where the excavation time detection unit 507 detects the excavation time required for the work attachment 20 to perform the specified excavation operation, and after this detection, the process proceeds to step SB9, where the hardness estimation unit 503 estimates the hardness of the ground based on the excavation time detected by the excavation time detection unit 507.

[0135] To explain an example of the ground hardness estimation process of step SB9, for example, when the excavation time when a specified excavation operation is performed on ground such that the weight of soil E excavated and held in the bucket 23 by the specified excavation operation corresponds to the maximum load capacity (in this example, ground of hardness h1 corresponding to the maximum soil weight w2 specified in the hardness correspondence data D in Figure 6) is Tmax, and the execution time of the specified excavation operation detected by the excavation time detection unit 507 is Treal, the ground hardness H can be estimated by the following equation 7.

[0136] H=h1*(Tmax / Treal)……(Formula 7) The Tmax may be measured during an excavation test when creating the hardness correspondence data D, and may be stored in the storage unit 504.

[0137] (Effects of the second embodiment) In this embodiment, the hydraulic excavator 1 further includes an excavation time detection unit 507 which detects the excavation time, which is the time required for a specified excavation operation of the work attachment 20. When estimating the hardness of the ground, the hardness estimation unit 503 determines whether the weight of the soil E detected by the weight detection unit 502 is equal to or greater than the specified weight after the specified excavation operation is performed by the work attachment 20, and if it is determined that the weight is equal to or greater than the specified weight, estimates the hardness of the ground based on the excavation time detected by the excavation time detection unit 507.

[0138] According to this configuration, even if the ground is too soft, the estimation accuracy of the ground hardness can be sufficiently ensured. That is, if the ground is too soft, the amount of soil excavated by the bucket 23 exceeds the maximum load that can be held by the bucket 23 in the excavation completion posture, so that even if the ground hardness changes, the weight of the soil E held by the bucket 23 remains constant because the excess falls off, and the estimation accuracy of the ground hardness cannot be sufficiently ensured. In contrast, in the above configuration, when the weight of the soil E held by the bucket 23 exceeds the predetermined weight (that is, when the ground is considered to be so soft that the weight of the soil held by the bucket 23 does not change even if the ground hardness changes), the estimation process of the ground hardness is performed based on the excavation time required for the predetermined excavation operation. The excavation time required for the predetermined excavation operation is not limited by an upper limit value, unlike the weight of soil held by the bucket 23, and the softer the ground is, the longer the excavation time becomes. Therefore, when the ground is excessively soft, the estimation accuracy can be improved by executing the ground hardness estimation process by the hardness estimation unit 503 based on the excavation time.

[0139] Third embodiment Fig. 15 is a view showing a third embodiment, which corresponds to Fig. 3. This embodiment differs from the first embodiment in that the hardness estimation unit 503 estimates the hardness of the ground based on the weight of soil held in the bucket 23 by a predetermined excavation operation and the operation data J of the work attachment 20 during the excavation operation acquired by the operation data acquisition unit 508.

[0140] Specifically, the controller 50 further includes an operation data acquisition unit 508. In addition, the controller 50 is connected to the cylinder load detection unit 36 ​​so as to be able to send and receive signals.

[0141] The cylinder load detection unit 36 ​​includes, as an example, a differential pressure sensor attached to the boom cylinder 21S. The differential pressure sensor detects the differential pressure between the pressure in the rod chamber and the pressure in the cylinder chamber of the boom cylinder 21S as the cylinder load. The cylinder load detection unit 36 ​​transmits information on the detected cylinder load to the controller 50. Note that the cylinder load is not limited to the differential pressure between the rod chamber and the cylinder chamber, but may be the pressure in the rod chamber or the pressure in the cylinder chamber. Also, the target cylinder is not limited to the boom cylinder 21S, but may be the arm cylinder 22S, the bucket cylinder 23S, or the like.

[0142] The operation data acquisition unit 508 acquires operation data J including operation parameters which are related to the operating state of the work attachment 20 and correlated with the hardness of the ground which is the subject of the excavation operation, and numerical values ​​relating to the operation parameters, and stores the acquired operation data J in the memory unit 504.

[0143] 16 is a diagram showing an example of operation data J acquired by the operation data acquisition unit 508. In the example of this figure, a cylinder load, a center of gravity acceleration of the work attachment 20, and an excavation reaction force acting on the work attachment 20 are illustrated as examples of the operation parameters. In addition, a maximum value of the cylinder load, a variance value of the center of gravity acceleration of the work attachment 20, and an integral value of the excavation reaction force are illustrated as values ​​related to each operation parameter. Note that the operation parameters listed here are merely examples, and may include, for example, the center of gravity jerk of the work attachment 20 (time rate of change of center of gravity acceleration), the center of gravity acceleration of the arm 22, the center of gravity velocity of the arm 22, the center of gravity jerk of the arm 22, etc.

[0144] The operation data acquiring unit 508 acquires the differential pressure between the rod chamber and the cylinder chamber of the boom cylinder 21S as an example of the cylinder load. This cylinder load is detected by the cylinder load detecting unit 36. During the excavation operation of the work attachment 20, the operation data acquiring unit 508 holds the maximum value of the differential pressure of the boom cylinder 21S received by the cylinder load detecting unit 36 ​​up to the present time, and updates the maximum value each time the differential pressure exceeds the current maximum value. In this way, the operation data acquiring unit 508 acquires the maximum cylinder load during the excavation operation of the work attachment 20.

[0145] Furthermore, the operation data acquisition unit 508 acquires (calculates) the center of gravity acceleration of the work attachment 20 based on information from the attitude detection unit 31. Specifically, when the operator operates the operation unit 4 to cause the work attachment 20 to perform a predetermined excavation operation, the operation data acquisition unit 508 calculates a composite center of gravity velocity Vg of the work attachment 20 based on information from the attitude detection unit 31, and calculates the time rate of change of the composite center of gravity velocity Vg as the center of gravity acceleration. Then, during the excavation operation of the work attachment 20, the operation data acquisition unit 508 acquires a time history of the center of gravity acceleration up to the present time, and calculates a variance value of the center of gravity acceleration based on the acquired time history. In this way, the operation data acquisition unit 508 acquires a variance value of the center of gravity acceleration of the work attachment 20 during the excavation operation of the work attachment 20.

[0146] Furthermore, the operation data acquisition unit 508 acquires (calculates) an integral value of an excavation reaction force acting on the bucket 23 while the work attachment 20 is performing a predetermined excavation operation. Here, the excavation reaction force is a reaction force that the bucket 23 receives from the ground during excavation. Specifically, the operation data acquisition unit 508 calculates the excavation reaction force at each time based on the loads on the three cylinders 21S to 23 detected by the cylinder load detection unit 36 ​​and information on the attitude of the work attachment 20 detected by the attitude detection unit 31, and calculates a value obtained by integrating the calculated excavation reaction force over the time from the start to the end of the predetermined excavation operation. Note that in order to acquire the excavation reaction force, a load detection sensor such as a load cell attached to the bucket 23 may be used.

[0147] The hardness estimation unit 503 executes a first calculation process to calculate a soil weight-corresponding hardness H0 (corresponding to a first hardness) corresponding to the weight of soil held in the bucket 23 after the excavation operation, and a second calculation process to calculate three operating status-corresponding hardnesses H1, H2, and H3 (corresponding to a second hardness) corresponding to the numerical values ​​of the three operating parameters in the operation data J acquired by the operation data acquisition unit 508 during the excavation operation. Then, the hardness estimation unit 503 estimates the hardness of the ground based on the soil weight-corresponding hardness H0 and the three operating status-corresponding hardnesses H1, H2, and H3.

[0148] The hardness estimation unit 503 stores the estimated hardness of the ground, outputs the average value of the hardness estimated a predetermined number of times as the hardness of the ground, and causes the display unit 34 to display it.

[0149] Next, Fig. 17 is a flowchart showing an example of the ground hardness estimation process executed by the hardness estimation unit 503 of this embodiment, and corresponds to Fig. 9 of embodiment 1. In the following description, the same process contents as those in Fig. 9 of embodiment 1 will be omitted as appropriate.

[0150] In step SC1, the same process as in step SA1 in the first embodiment is executed.

[0151] In step SC2, it is determined whether or not the working attachment 20 has actually started excavation from the state in which it took the excavation start posture (FIG. 4A). Here, whether or not the working attachment 20 is in the excavation start posture is estimated based on posture information of the working attachment 20 detected by the posture detection unit 31, as in step SA2, and whether or not the working attachment 20 has actually started excavation from the excavation start posture may be estimated based on an operation signal of an operating lever or the like input from the operation unit 4. If the determination in this step SC2 is NO (i.e., if the working attachment 20 takes the excavation start posture, which is the initial posture, but excavation does not start, or if excavation by the working attachment 20 has started but the initial posture was not the excavation start posture), the process returns, whereas if the determination is YES, the process proceeds to step SC3.

[0152] In step SC3, the process starts to acquire the operation data J. Specifically, the process starts to acquire the maximum value of the cylinder load, the variance value of the center of gravity acceleration of the work attachment 20, and the integral value of the excavation reaction force acting on the work attachment 20.

[0153] In step SC4, it is determined whether or not the predetermined excavation operation by the work attachment 20 has been completed, and if the determination is NO, the process of step SC4 continues, whereas if the determination is YES, the process proceeds to step SC5.

[0154] In step SC5, the acquisition of the operational data J ends.

[0155] In steps SC6 and SC7, the same processes as in steps SA4 and SA5 in the first embodiment are executed.

[0156] In step SC8, the first calculation process is executed to calculate a soil weight-corresponding hardness corresponding to the weight of soil held in the bucket 23. As in the first embodiment, this soil weight-corresponding hardness is calculated based on the weight of soil E in the bucket 23 detected by the weight detection unit 502 and the hardness correspondence data D shown in Fig. 6 (hereinafter referred to as the first hardness correspondence data D).

[0157] In step SC9, the second calculation process is executed to calculate the hardness corresponding to the operating state. The hardness corresponding to the operating state is calculated based on the maximum value of the cylinder load, the variance value of the acceleration of the center of gravity of the work attachment 20, and the integral value of the excavation reaction force of the work attachment 20 included in the operating data J acquired by the operating data acquisition unit 508, and the second hardness correspondence data F1, F2, and F3 (see Figs. 18A to 18C) previously stored in the storage unit 504. The second hardness correspondence data F1, F2, and F3 are data that associates the numerical values ​​related to the three operating parameters with the ground hardness, and are previously acquired by experiments or the like and stored in the storage unit 504. It can also be said that the second hardness correspondence data F1, F2, and F3 are data that specifies the change in the operating data J due to the difference in the hardness of the ground. As shown in Fig. 16, in this example, the maximum value of the cylinder load shown in the operation data J is X1, the center of gravity acceleration of the work attachment 20 is X2, and the integral value of the excavation reaction force is X3, so that based on the second stiffness correspondence data F1 to F3 shown in Fig. 18A to Fig. 18C, the operating status corresponding stiffness corresponding to the maximum value of the cylinder load X1 is calculated as H1, the operating status corresponding stiffness corresponding to the center of gravity acceleration of the work attachment 20 X2 is calculated as H2, and the operating status corresponding stiffness corresponding to the excavation reaction force X3 is calculated as H3. Fig. 20 shows data indicating the results of obtaining the operating status corresponding stiffness, and the data is stored in the storage unit 504.

[0158] In step SC10, the hardness of the ground is estimated based on the weight-based hardness H0 calculated in step SC8, the three operating status-based hardnesses H1, H2, and H3 corresponding to each operating parameter calculated in step SC9, and weighting coefficients W0, W1, W2, and W3 previously assigned to the soil weight and each operating parameter. Specifically, when the estimated hardness of the ground is Ih, Ih is calculated as Ih=H0*W0+H1*W1+H2*W2+H3*W3. FIG. 19 shows weighting coefficient data M that specifies the weighting coefficients W0, W1, W2, and W3, and is stored in the storage unit 504 in advance. The weighting coefficients W0, W1, W2, and W3 are set higher for the operating parameters that have a greater influence on the estimation of the ground hardness. The relationship W0+W1+W2+W3=1 is satisfied. After the processing of this step SC10 is completed, the process proceeds to step SC11.

[0159] In step SC11, the operation data J acquired in step SC3 is deleted, and the information on the ground hardness h1 estimated in step SC10 is output to the display unit 34, and then the process returns to step SC1. Then, the processes from step SC1 to step SC11 are repeated.

[0160] The hardness estimation unit 503 outputs the estimated ground hardness Ih to the display unit 34 every time the predetermined excavation operation is performed. Moreover, the hardness estimation unit 503 stores the estimated ground hardness Ih every time the predetermined excavation operation is performed, and when the stored ground hardness Ih reaches a predetermined number of times (the predetermined number is 2 or more), it calculates an average value Iave of the stored ground hardness Ih for the predetermined number of times and outputs the calculated average value Iave to the display unit 34.

[0161] Each time the hardness estimation unit 503 estimates the ground hardness Ih (i.e., each time the specified excavation operation is performed), the display unit 34 displays the most recent ground hardness Ih received from the hardness estimation unit 503 on the information display screen Q. In addition, each time the hardness estimation unit 503 calculates the average value Iave (=ΣIh / n) (i.e., each time the specified excavation operation is performed the specified number of times), the display unit 34 displays the most recent average value Iave received from the hardness estimation unit 503 on the information display screen Q.

[0162] FIG. 21 is a diagram showing an example of the information display screen Q displayed on the display unit 34. As shown in FIG.

[0163] The information display screen Q includes an operation mode display area q1 and a hardness information display area q2.

[0164] The operation mode display area q1 consists of a mode display section q11 that displays whether or not the normal operation mode is currently set, and an assist information display section q12 that displays information related to the above-mentioned excavation assist control. The mode display section q11 displays a display mark as a white circle when the normal operation mode is set, and displays a display mark as a black circle when the hardness estimation mode is set. The assist information display section q12 displays a display mark as a black circle when the assist control is enabled, and displays a display mark as a white circle when the assist control is disabled.

[0165] The hardness information display area q2 has a display section q21 that displays the most recent ground hardness Ih estimated by the hardness estimation unit 503, and a display section q22 that displays the average ground hardness Iave. An input box q23 is provided at the top right of the hardness information display area q2 for inputting the number of data items (the above-mentioned predetermined number of times) when performing the averaging process of the ground hardness calculated by the hardness estimation unit 503, and to the right of that is provided a display section q24 that displays the current acquisition and recovery of the ground hardness (the number of times estimated by the hardness estimation unit 503).

[0166] (Action and effect) As described above, in this embodiment, when the hardness estimation unit 503 executes the ground hardness estimation process, the hardness estimation unit 503 executes a first calculation process of calculating the hardness of the ground corresponding to the soil weight as a soil weight-corresponding hardness H0 based on the soil weight detected by the weight detection unit 502 after the execution of the predetermined excavation operation by the work attachment 20 and the first hardness correspondence data D, and a second calculation process of calculating the hardness of the ground corresponding to the acquired operation data J as an operation status-corresponding hardness H1, H2, H3 based on the operation data J acquired by the operation data acquisition unit 508 during the predetermined excavation operation and the second hardness correspondence data F1, F2, F3 that specifies the change in the operation data J due to differences in ground hardness. The hardness estimation unit 503 is configured to estimate the hardness of the ground based on the soil weight-corresponding hardness H0 calculated in the first calculation process and the second hardnesses H1, H2, H3 calculated in the second calculation process.

[0167] According to this configuration, the ground hardness is estimated based on not only the weight of the soil E held in the bucket 23 by the predetermined excavation operation but also the operation data J of the work attachment 20 during the excavation operation, so that the accuracy of estimating the ground hardness can be improved. That is, the weight of soil held in the bucket 23 by the predetermined excavation operation easily changes due to changes in the trajectory of the bucket 23 caused by the bucket 23 coming into contact with a foreign object during the excavation operation, roughness of the terrain, and the like. For this reason, if the ground hardness is estimated based only on the weight of soil held in the bucket 23, there is a risk that the accuracy of estimating the ground hardness will decrease due to variations in the weight of soil held in the bucket 23. In contrast, in the above configuration, the estimation process of the ground hardness is executed based on the soil weight-corresponding hardness H0 based on the weight of soil held in the bucket 23 after the predetermined excavation operation and the operating status-corresponding hardness based on the operating parameters of the work attachment 20 during the predetermined excavation operation, so that the estimation accuracy can be improved as much as possible compared to the case of estimating the ground hardness based only on the soil weight.

[0168] The operation data J is data including numerical values ​​related to operation parameters which are related to the operating state of the work attachment 20 during an excavation operation and correlated with the hardness of the ground that is the subject of the excavation operation. In this embodiment, as an example, the operation parameters include three items: the cylinder load of the work attachment 20, the acceleration of the center of gravity of the work attachment 20, and the excavation reaction force acting on the work attachment 20, and the maximum value, variance value, and integral value are obtained as numerical values ​​related to each of the parameters.

[0169] In this way, by setting parameters that are highly correlated with the hardness of the ground as the operating parameters, the accuracy of estimating the hardness of the ground by the hardness estimating unit 503 can be improved. That is, the harder the ground is, the greater the cylinder load of the working attachment 20. Also, the harder the ground is, the greater the vibration of the working attachment 20 during the excavation operation, so the acceleration of the center of gravity of the working attachment 20 also changes in a vibrational manner. Also, the harder the ground is, the greater the excavation reaction force acting on the working attachment 20. In this way, since the three parameters are highly correlated with the hardness of the ground, by setting these as operating parameters, the degree of agreement between the hardness corresponding to the operating condition based on the operating parameters and the actual hardness of the ground can be improved, and thus the accuracy of estimating the ground hardness based on the hardness corresponding to the operating condition and the weight-corresponding hardness can be improved.

[0170] In addition, in this embodiment, the hardness estimation unit 503 is configured, when executing the estimation process, to obtain three operating state-corresponding hardnesses H1, H2, H3 corresponding to the three operating parameters, i.e., the cylinder load, the center of gravity acceleration of the work attachment 20, and the excavation reaction force, as well as the soil weight-corresponding hardness H0, and to estimate the hardness of the ground based on preset weighting coefficients W0, W1, W2, W3 for each of the hardnesses H0, H1, H2, H3, respectively.

[0171] According to this configuration, the weighting coefficient is set high for indicators with a strong correlation with the hardness of the ground, and set low for indicators with a low correlation, thereby improving the accuracy of estimating the hardness of the ground. Note that the weighting coefficients W0, W1, W2, and W3 may all be the same value, in which case the estimated hardness Ih can be calculated as Ih=(H1+H2+H3+H4) / 4.

[0172] In addition, in this embodiment, the hardness estimation unit 503 stores the hardness of the ground each time the specified excavation operation is performed, and when the stored ground hardness reaches a specified number of times (the specified number is 2 or more), it calculates the average value Iave of the stored ground hardness for the specified number of times and outputs information on the calculated average value to the display unit 34.

[0173] According to this configuration, the average value of the ground hardness for a predetermined number of times is output as the ground hardness estimation result by the hardness estimation unit 503. This makes it possible to average out the variation in the ground hardness estimated by the hardness estimation unit 503. Therefore, by performing excavation work based on this averaged ground hardness, for example, an operator can perform appropriate excavation work according to the ground hardness.

[0174] (Modification 1 of the third embodiment) In the third embodiment, the cylinder load, the center of gravity acceleration of the work attachment 20, and the excavation reaction force acting on the work attachment 20 are given as examples of operating parameters, and the maximum value, variance value, and integral value are given as numerical values ​​related to these, but the present invention is not limited to these.

[0175] That is, the operating parameter may be, for example, any one of the cylinder load, the acceleration of the center of gravity of the work attachment 20, and the speed of the work attachment 20. The operating parameter may also include the velocity of the center of gravity of the work attachment 20. That is, the operating parameter may be any parameter as long as it is related to the operating state of the work attachment 20 during the excavation operation and correlates with the hardness of the ground that is the target of the excavation operation, and the number of operating parameters is not limited to multiple and may be one.

[0176] In the above embodiment, the maximum value, variance value, and integral value are given as the numerical values ​​related to the three operation parameters (indexes), but the present invention is not limited to these, and may be the numerical values ​​of the operation parameters themselves. Furthermore, the related numerical values ​​are not limited to constants, and may be time histories (i.e., waveform data showing changes over time).

[0177] (Modification 2 of the third embodiment) In the third embodiment, the first hardness correspondence data D and the second hardness correspondence data F1, F2, and F3 in the form of a graph are used to calculate the hardness corresponding to each index, and each hardness is multiplied by a weighting coefficient to estimate the hardness Ih of the ground, but this is not limited to the above, and hardness correspondence data divided into levels as shown in Fig. 22 described later may be used as the first hardness correspondence data D and the second hardness correspondence data F1, F2, and F3. In this case, for example, it may be determined which level of hardness the hardness corresponding to each index belongs to, the most common hardness level is identified, and the identified hardness may be estimated to be the hardness of the ground.

[0178] (Modification 3 of the third embodiment) In the third embodiment, the hardness estimation unit 503 sets the weighting coefficient as a predetermined constant, but this is not limiting and the weighting coefficient may be changed based on the posture of the work attachment 20 during a predetermined excavation operation or on time-series changes in the numerical values ​​in the operation data J. With this configuration, the accuracy of the ground hardness estimation by the hardness estimation unit 503 can be improved as much as possible by lowering the weight of the indicator that is predicted to have a lower estimation accuracy.

[0179] For example, when excavating a downward-facing slope or a ditch, the position of the bucket 23 in the excavation start posture is lower than the ground surface on which the hydraulic excavator 1 is located, but the lower the position of the bucket 23 from the ground surface, the easier it is for soil and sand to flow into the bucket 23 during excavation operation compared to when excavating flat ground surface, so that differences in soil and sand weight due to differences in ground hardness are less likely to appear. Therefore, the hardness estimation unit 503 may be configured to set the weighting coefficient W0 corresponding to the sand weight-based hardness H0 relatively small and set the other weighting coefficients W1, W2, and W3 relatively large when it is determined that a downward-facing slope or a ditch is being excavated based on, for example, the posture of the working attachment 20 detected by the posture detection unit 31. This allows the accuracy of the ground hardness estimation by the hardness estimation unit 503 to be improved as much as possible.

[0180] As another example, even if the ground is generally soft, if the tip of the bucket 23 gets caught on a locally existing rigid body such as a stone, the center of gravity acceleration of the work attachment 20 may become locally high. Therefore, the hardness estimation unit 503 may acquire waveform data showing the time change in the center of gravity acceleration of the work attachment 20, determine whether or not the waveform data contains a feature indicating contact between the bucket 23 and a rigid body (for example, a waveform feature in which the center of gravity acceleration increases vertically suddenly), and if it is determined that the feature exists, set the weighting coefficient for the indicator (center of gravity acceleration) relatively small and set the other weighting coefficients relatively large. This can improve the accuracy of the ground hardness estimation by the hardness estimation unit 503 as much as possible.

[0181] (Other embodiments) An example of a construction machine according to an embodiment of the present invention has been described above, but the present invention is not limited to this, and for example, the following modified embodiments can be adopted.

[0182] (1) In the above-described embodiments and modifications, the command signal for driving the arm 22 and the bucket 23 is a command signal corresponding to the amount of operation of the operation unit 4, and the command signal for driving the boom 21 is composed of a command signal corresponding to the amount of operation of the operation unit 4 and an adjustment command signal input from the controller 50 to the solenoid proportional valve 5, but the present invention is not limited to this. That is, the hydraulic excavator 1 may be provided with a controller (control unit) capable of executing control to generate a command signal for causing the work attachment 20 to perform the predetermined excavation operation and input the generated command signal to the drive unit. According to this configuration, for example, an automatic operation switch is provided, and the control is executed when the switch is turned on, so that the work attachment 20 can automatically perform the predetermined excavation operation that satisfies the target speed condition. This makes it possible to suppress variation in the operation of the work attachment 20 caused by manual operation by the operator, and ultimately improve the accuracy of the ground hardness estimation by the hardness estimation unit 503.

[0183] (2) In each of the above-mentioned embodiments and modifications, the hardness correspondence data D is graph data in which the soil weight of the bucket 23 obtained by the excavation test and the ground hardness are associated with each other by an approximation line I, but the present invention is not limited to this, and may be data in which the hardness of the ground is classified into a plurality of levels according to the soil weight. Fig. 22 is a diagram (corresponding to Fig. 6 in the above-mentioned first embodiment) showing an example of hardness correspondence data based on this classification. In the example of this diagram, the hardness of the ground is classified into three levels, namely, a hard soil level, an intermediate level, and a soft soil level, and the weight of soil corresponding to each hardness level is shown on the horizontal axis. In the example of this figure, a first threshold value that distinguishes between a hard soil level and an intermediate level, and a second threshold value that distinguishes between a soft soil level and an intermediate level are set, and if the weight of soil held in the bucket 23 after a specified excavation operation is less than the first threshold value, the ground hardness can be estimated to be at the hard soil level, if the weight of soil is within the range between the first threshold value and the second threshold value, the ground hardness can be estimated to be at the intermediate level, and if the weight of soil exceeds the second threshold value, the ground hardness can be estimated to be at the soft soil level.

[0184] (3) In the above-described embodiments and modified examples, the target speed condition when the working attachment 20 performs a predetermined excavation operation is set to a condition that the combined center-of-gravity velocity Vg of the working attachment 20 is constant (=target center-of-gravity velocity r), but this is not limited to the above. That is, the target target speed specified by the target speed condition does not necessarily have to be the combined center-of-gravity velocity Vg of the working attachment 20 as in the above-described embodiments, but may be the velocity of the center of gravity of the arm 22. Furthermore, the target speed specified by the target speed condition (target center-of-gravity velocity r in the above-described embodiments) does not necessarily have to be a constant value as in the above-described embodiments, and may be, for example, a speed profile that increases linearly over time, or a speed profile that increases linearly and then becomes a constant value. There are no limitations on how the target speed conditions are set, but the target speed conditions for the specified excavation operation of the work attachment 20 when creating the hardness correspondence data D and the target speed conditions for the specified excavation operation of the work attachment 20 when actually estimating the ground hardness must be the same.

[0185] (4) In each of the above-mentioned embodiments and modifications, the boom 21, the arm 22, and the bucket 23 are each configured to operate at a rotational angular velocity corresponding to the amount of operation of the operation unit 4, but the present invention is not limited thereto. For example, the controller 50 may execute control (hereinafter referred to as excavation assist control) for determining the rotational angular velocity of the bucket 23 based on the relative angular velocity between the boom 21 and the arm 22 (the angular velocity of the relative rotation of the arm 22 with respect to the boom 21). This stabilizes the operation of the work attachment 20, thereby improving the reproducibility of the amount of soil excavated by the bucket 23, and thus improving the accuracy of the estimation of the ground hardness. Here, the excavation assist control may be executed only in the hardness estimation mode, and the function may be turned off in the normal operation mode. In addition, the controller 50 may execute a process for changing a control parameter (e.g., the degree of change in the rotational angular velocity) when executing the excavation assist control to a value corresponding to the estimated ground hardness, based on the result of the estimation of the ground hardness by the hardness estimation unit 503.

[0186] (5) In each of the above-described embodiments and modifications, the excavation start posture of the predetermined excavation operation by the working attachment 20 is a state in which the tip 23b of the bucket 23 is in contact with the ground G, but this is not limited thereto, and may be, for example, a state in which the tip 23b of the bucket 23 penetrates the ground. In order to penetrate the tip 23b of the bucket 23 into the ground G, for example, the cylinder load may be monitored, the boom 21 may be lowered until the cylinder load (for example, the load of the boom cylinder 21S) reaches a predetermined load, and the lowering of the boom 21 may be stopped at the same time as the cylinder load reaches the predetermined load, and the posture of the working attachment 20 at the time of the stop may be set as the excavation start posture. As a result, the predetermined excavation operation can be started from a state in which the tip 23b of the bucket 23 is firmly biting into the ground G, so that the bucket 23 can be prevented from swinging out of the ground and the soil can be reliably excavated by the bucket 23. Therefore, a sufficient amount of soil can be excavated by the bucket 23, and the hardness estimation unit 503 can accurately estimate the ground hardness.

[0187] (6) In each of the above-described embodiments and variations, the weight detection unit 502 is configured to detect the weight of the soil E held in the bucket 23 based on the balance of moments around the rotation fulcrum S at the base end of the boom 21. However, this is not limited to this and may be configured, for example, by a weight sensor (load cell, etc.) arranged on the bottom surface of the bucket 23.

[0188] (7) In each of the above embodiments and modifications, the hardness correspondence data D is created based on an excavation test in which the work attachment 20 actually performs the predetermined excavation operation, but this is not limiting, and the hardness correspondence data D may be created, for example, based on a computer simulation that simulates the predetermined excavation operation of the work attachment 20. In this case, the hardness correspondence data D can be created more cheaply and in a shorter time than in the case of actually performing an excavation test.

[0189] (8) In the above-described embodiments and modifications, the maximum reach posture and the ground angle of the bucket 23 of 70° to 120° (see FIG. 4A) are given as an example of the excavation start posture when the work attachment 20 is caused to perform a predetermined excavation operation. However, the maximum reach posture is not necessarily required, and the ground angle of the bucket 23 is not necessarily required to be 70° to 120°. In other words, the excavation start posture may be the same posture when the hardness correspondence data D is created and when the actual ground hardness is estimated based on the hardness correspondence data D, and is not limited to the posture shown in FIG. 4A. Similarly, the excavation completion posture is not limited to the posture shown in FIG. 4C, and may be the same posture when the hardness correspondence data D is created and when the actual ground hardness is estimated based on the hardness correspondence data D.

[0190] (9) In each of the above-mentioned embodiments and modifications, in steps SA5, SB5, and SC7, the hardness estimation unit 503 executes the process of determining whether or not the predetermined excavation operation by the work attachment 20 has been performed correctly (operation determination process) based on whether or not the weight of soil held in the bucket 23 is within the range of the minimum soil weight w1 to the maximum soil weight w2, but the present invention is not limited to this. That is, the hardness estimation unit 503 may be configured to execute the process of determining the operation based on the distance from the base end of the work attachment 20 to the tip of the bucket 23 at the start of the excavation and the operation input information of the work attachment 20 after the start of the predetermined excavation operation. Specifically, the hardness estimation unit 503 may be configured to determine that the predetermined excavation operation has been performed correctly when the boom foot distance, which is the distance from the tip of the bucket 23 to the base end of the boom 21 at the start of the predetermined excavation operation (excavation start posture), is equal to or greater than a predetermined threshold value, and the pull operation input of the arm 22 during the predetermined excavation operation of the work attachment 20 is equal to or greater than a predetermined time. This makes it possible to prevent work such as leveling the ground around the machine body 1S from being erroneously determined as the predetermined excavation operation. A turning operation input during execution of the predetermined excavation operation by the work attachment 20 may be added to the determination conditions. This makes it possible to prevent the hardness estimation unit 503 from erroneously determining that a pushing excavation operation in which the work attachment 20 is turned while the bucket 23 is being pushed against the side of a ditch or the ground is the predetermined excavation operation.

[0191] (10) In each of the above-mentioned embodiments and modifications, the controller 50 (one example of a speed condition setting unit) may be configured to reset the target speed condition after the work attachment 20 executes a predetermined number of times of a predetermined excavation operation while satisfying the target speed condition. This predetermined number may be the same as the predetermined number of times, which is the number of samplings when the hardness estimation unit 503 calculates the average value of the hardness of the ground. When setting the target speed condition, the controller 50 acquires the hardness of the ground estimated by the hardness estimation unit 503 at the time when the predetermined number of times of the predetermined excavation operation is executed, and sets the target speed condition so that the excavation amount of the soil E excavated by the bucket 23 corresponds to the maximum load that can be held by the bucket 23 when the ground having the acquired hardness is excavated by the predetermined excavation operation of the work attachment 20. The target speed condition is set by the same method as that described in FIG. 8 of the first embodiment. The correspondence between the acquired hardness and the target speed condition such that the amount of soil in the bucket 23 corresponds to the maximum load may be acquired in advance by an experiment or the like and stored as target speed setting data in the storage unit 504. The hardness estimation unit 503 can set the target speed condition based on this target speed setting data and the acquired hardness.

[0192] According to this configuration, even if the hardness of the ground changes from soft to hard or from hard to soft as the excavation of the ground by the predetermined excavation operation progresses, the target speed condition is changed according to the changed hardness of the ground. Therefore, it is possible to ensure a sufficient amount of soil E excavated by the bucket 23. That is, for example, if the ground to be excavated is hard, but the working attachment 20 is driven at a target speed condition corresponding to soft soil, it is not possible to ensure a sufficient amount of soil E excavated. As a result, not only is the accuracy of estimating the hardness of the ground reduced, but there is also a risk of a reduction in the efficiency of excavating the ground by the working attachment 20, which is the original purpose. In contrast, according to the above configuration, the target speed condition is set according to the hardness of the ground, so that the problem of the reduction in excavation efficiency described above can be avoided.

[0193] (11) In each of the above embodiments and variations, the multiple components constituting the work attachment 20 are composed of three components: the boom 21, the arm 22, and the bucket 23; however, this is not limited to this and may be composed of, for example, two components including the bucket 23, or may be composed of four or more components.

[0194] (12) In the above embodiments and modifications, the hydraulic excavator 1 capable of traveling on the ground has been described as an example of a construction machine, but the present invention is not limited to this and may be a construction machine fixed to the ground. Furthermore, the drive system of the construction machine is not limited to a hydraulic drive system and may be, for example, an electric drive system.

[0195] (13) The present invention includes any combination of the above-described embodiments, modifications, and other embodiments. [Explanation of symbols]

[0196] D Hardness Data E Soil held in bucket G ground Vg Resultant center of gravity velocity g Composite center of gravity r Target center of gravity velocity 1. Hydraulic excavator (construction machinery) 1S aircraft 4 Control section 20 Work attachment 21 Boom (multiple components) 22 Arm (multiple parts) 23 Bucket (multiple components) 30 Drive unit 35 Server (management device) 50 Controller (control unit, speed condition setting unit) 501 Attachment control unit (speed state detection unit, control unit) 502 Weight detection unit 503 Estimation Department 504 Storage section 505 Communications Department 506 Deviation Calculation Unit 507 Excavation time detector

Claims

1. The aircraft and a work attachment that is attached to the machine body, has a bucket that can excavate and hold soil that constitutes the ground, and can perform an excavation operation of the ground through the bucket; a weight detection unit capable of detecting the weight of the soil held in the bucket; A hardness estimation unit that estimates the hardness of the ground, The hardness estimation unit is configured to execute an estimation process to estimate the hardness of the ground based on the weight of the soil detected by the weight detection unit and first hardness correspondence data that specifies the change in the weight of the soil due to differences in hardness of the ground, after a predetermined excavation operation is executed in which the working attachment changes its posture from an excavation start posture to an excavation completion posture capable of holding the soil after excavation while satisfying a target speed condition.

2. 2. The construction machine according to claim 1, an operation data acquisition unit that acquires operation data related to the operating state of the work attachment during the excavation operation and correlated with the hardness of the ground that is the subject of the excavation operation; The hardness estimation unit is a first calculation process for calculating, as a first hardness, a ground hardness corresponding to the weight of the soil detected by the weight detection unit after the work attachment has performed the predetermined excavation operation, based on the first hardness correspondence data and the weight of the soil detected by the weight detection unit when the estimation process is performed; A construction machine configured to execute a second calculation process to calculate the ground hardness corresponding to the acquired operation data as a second hardness based on the operation data acquired by the operation data acquisition unit during the specified excavation operation and second hardness correspondence data that specifies changes in the operation data due to differences in ground hardness, and to estimate the ground hardness based on the first hardness calculated in the first calculation process and the second hardness calculated in the second calculation process.

3. The construction machine according to claim 1 or 2, The hardness estimation unit is configured to, when the specified excavation operation is performed by the work attachment, execute an operation determination process to determine whether the specified excavation operation has been performed correctly along a specified trajectory, and not execute the estimation process if it determines that the specified excavation operation has not been performed correctly.

4. 3. The construction machine according to claim 2, The operation data is numerical data on an operation parameter related to an operating state of the work attachment during the excavation operation and correlated with the hardness of the ground that is the subject of the excavation operation, A construction machine, wherein the operating parameters include at least one of a load on a cylinder that drives the work attachment, a velocity of the center of gravity of the work attachment, an acceleration of the center of gravity of the work attachment, and an excavation reaction force acting on the work attachment.

5. 3. The construction machine according to claim 2, The operation data is numerical data on at least one operation parameter related to an operating state of the work attachment during the excavation operation and correlated with hardness of the ground that is the subject of the excavation operation, A construction machine wherein the hardness estimation unit is configured, when executing the estimation process, to calculate at least one second hardness corresponding to the at least one operating parameter and the first hardness corresponding to the weight of the soil and sand, and to estimate the hardness of the ground based on the calculated at least one second hardness and the first hardness and a weighting coefficient preset for each of the hardnesses.

6. The construction machine according to claim 1 or 2, The hardness estimation unit is configured to store the hardness of the ground estimated each time the specified excavation operation is performed, and to output the average value of the stored hardnesses for a specified number of times as the hardness of the ground.

7. The construction machine according to claim 5, A construction machine, wherein the hardness estimation unit is configured to change the weighting coefficient based on the posture of the work attachment during the specified excavation operation or on a time-series change in the numerical value in the operation data.

8. 4. The construction machine according to claim 3, a construction machine configured to execute the operation determination process based on the distance from the base end of the work attachment in the excavation start posture to the tip of the bucket and operation input information of the work attachment after the start of the specified excavation operation.

9. The construction machine according to claim 1 or 2, A speed condition setting unit that sets the target speed condition is further provided, the speed condition setting unit is configured to reset the target speed condition after the work attachment performs a predetermined number of predetermined excavation operations while satisfying the target speed condition; When resetting the target speed condition, the speed condition setting unit obtains the ground hardness estimated by the hardness estimation unit at the time when the specified excavation operation has been performed a specified number of times, and sets the amount of soil excavated by the bucket when ground of the obtained hardness is excavated by the specified excavation operation of the work attachment to an amount corresponding to the maximum load that the bucket can hold.

10. 2. The construction machine according to claim 1, The work attachment has a plurality of members including the bucket that are movable relative to one another, A construction machine, wherein the target speed condition is a condition that the speed of the center of gravity of an arm which is one of the plurality of members and is connected to the bucket, or the speed of a combined center of gravity of the plurality of members is constant.

11. The construction machine according to claim 1 or 2, a deviation calculation unit that detects a speed state of the work attachment during execution of the predetermined excavation operation and calculates information related to a deviation between the detected speed state and the target speed condition; The construction machine further comprises: a notification unit that notifies information related to the deviation calculated by the deviation calculation unit.

12. The construction machine according to claim 1 or 2, a speed state detection unit that detects a speed state of the work attachment during execution of the predetermined excavation operation; A drive unit for driving the working attachment; and a control unit that, while the work attachment is performing the specified excavation operation, determines a command signal to be sent to the drive unit based on a comparison between the speed state of the work attachment detected by the speed state detection unit and the target speed condition so that the speed state satisfies the target speed condition, and executes control to transmit the determined command signal to the drive unit.

13. The construction machine according to claim 1 or 2, The target speed condition is set so that when ground of a specified hardness on the softer side of the ground hardnesses defined in the hardness correspondence data is excavated by the specified excavation operation of the work attachment, the amount of soil excavated by the bucket corresponds to the maximum load that the bucket can hold, said construction machinery.

14. The construction machine according to claim 1 or 2, Further, a digging time detection unit is provided for detecting a digging time, which is a time required for the predetermined digging operation, The hardness estimation unit is configured to determine whether the weight of the soil detected by the weight detection unit is a predetermined weight or more after the work attachment has performed the predetermined excavation operation, and if it is determined that the weight is less than the predetermined weight, to perform the estimation process to estimate the hardness of the ground based on the weight of the soil detected by the weight detection unit and the hardness correspondence data, while if it is determined that the weight is equal to or more than the predetermined weight, to perform the estimation process to estimate the hardness of the ground based on the excavation time detected by the excavation time detection unit.

15. The construction machine according to claim 1 or 2, A drive unit for driving the working attachment; a control unit capable of executing control to generate a command signal for causing the work attachment to perform the specified excavation operation that satisfies the target speed condition, and to input the generated command signal to the drive unit.

16. The construction machine according to claim 1 or 2, A construction machine further comprising a communication unit that receives information on the ground hardness estimated by the hardness estimation unit and transmits the received hardness information to a management device provided at a location away from the construction machine.

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