JP7521024B2 - Excavators and systems for excavators - Google Patents

Description

The present invention relates to a shovel with an attachment and a system for a shovel.

A shovel is known that has a variable throttle that increases or decreases the flow rate of hydraulic oil flowing out of the rod-side oil chamber of the arm cylinder when the arm is closed (see Patent Document 1). This shovel monitors the pressure in the bottom-side oil chamber of the arm cylinder to control the variable throttle. If the pressure in the bottom-side oil chamber is below a predetermined value, it can be determined that the bucket is not in contact with the ground and the excavation attachment is operating in the air, and it can be determined that the flow rate of hydraulic oil flowing through the variable throttle should be reduced so that the arm does not fall under its own weight. Also, if the pressure in the bottom-side oil chamber is equal to or greater than a predetermined value, it can be determined that the bucket is in contact with the ground and it can be determined that the flow rate of hydraulic oil flowing through the variable throttle should be increased so that unnecessary pressure loss does not occur at the variable throttle.

JP 2010-230061 A

However, the above-mentioned excavator cannot determine whether to reduce or increase the flow rate of hydraulic oil flowing through the variable throttle until it detects contact between the bucket and the ground based on the pressure in the bottom oil chamber of the arm cylinder. As a result, the flow rate cannot be increased when excavation begins, causing unnecessary pressure loss at the variable throttle and reducing the working efficiency of the excavator. This is because the current shape of the ground being excavated is not recognized, and it is therefore not possible to determine in advance when the bucket will come into contact with the ground.

In view of the above, it is desirable to provide a shovel that can recognize the current shape of the ground being worked on.

A shovel according to an embodiment of the present invention is a shovel comprising a lower running body, an upper rotating body mounted on the lower running body, an attachment attached to the upper rotating body, an attitude detection device for detecting the attitude of the attachment, and a control device, wherein the control device updates soil shape information as a three-dimensional shape model of the work site where the shovel is located before an operation to change the shape of the soil is performed by the attachment, which is stored in a database so that the control device can refer to it, after an operation to change the shape of the soil is performed by the attachment and before another operation to change the shape of the soil is performed by the attachment, and the soil shape information updated by the control device includes the shape of the excavated ground and the shape of the removed soil, and the shape of the removed soil is determined based on pre-stored information .

The above-mentioned means provide a shovel that can recognize the current shape of the ground being worked on.

FIG. 1 is a side view of a shovel according to an embodiment of the present invention. 2 is a side view of the shovel showing an example of output contents of various sensors constituting a posture detection device mounted on the shovel of FIG. 1. FIG. 2 is a diagram showing a configuration example of a basic system mounted on the excavator shown in FIG. FIG. 2 is a functional block diagram showing a configuration example of an external calculation device. 4 is a conceptual diagram of information regarding the current shape of the ground surface to be excavated acquired by a ground surface shape information acquisition unit. FIG. 13 is a flowchart showing an example of the flow of a post-earth-discharging ground surface shape acquisition process. FIG. 11 is a diagram showing the relationship between the bucket angle and the soil discharge rate. FIG. 11 is a conceptual diagram of information regarding the ground shape after an earth removal operation. FIG. 2 is a diagram showing an example of the configuration of a drive system mounted on the shovel of FIG. 1 . FIG. 4 is a diagram showing an example of the configuration of a regeneration oil passage and a regeneration release valve. 13 is a flowchart showing a flow of an opening area adjustment process. FIG. 13 is a diagram showing the transition over time of various parameters when the controller adjusts the opening area of the regeneration release valve. FIG. 2 is a diagram showing the relationship between the depth of the ground to be excavated and a reference surface. FIG. 4 is a diagram showing the relationship between a bucket angle and an excavation reaction force. 13 is a flowchart showing a flow of automatic attitude adjustment processing. FIG. 2 is a functional block diagram showing a configuration example of an external calculation device. FIG. 2 is a functional block diagram showing a configuration example of an external calculation device. FIG. 2 is a functional block diagram showing a configuration example of an external calculation device. FIG. 2 is a functional block diagram showing a configuration example of an external calculation device.

First, referring to FIG. 1, a shovel as a construction machine according to an embodiment of the present invention will be described. FIG. 1 is a side view of a shovel according to an embodiment of the present invention. An upper rotating body 3 is mounted on a lower traveling body 1 of the shovel shown in FIG. 1 via a rotating mechanism 2. A boom 4 is attached to the upper rotating body 3. An arm 5 is attached to the tip of the boom 4, and a bucket 6 is attached to the tip of the arm 5. The boom 4, arm 5, and bucket 6 as working elements constitute an excavation attachment, which is an example of an attachment. The attachment may be other attachments such as a bed digging attachment, a leveling attachment, and a dredging attachment. The boom 4, arm 5, and bucket 6 are hydraulically driven by a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9, respectively. A cabin 10 is provided on the upper rotating body 3, and a power source such as an engine 11 is mounted on the upper rotating body 3. Additionally, a communication device M1, a positioning device M2, an attitude detection device M3, and a cylinder pressure detection device M4 are attached to the upper rotating body 3.

The communication device M1 is a device that controls communication between the shovel and the outside. In this embodiment, the communication device M1 controls wireless communication between a GNSS (Global Navigation Satellite System) surveying system and the shovel. Specifically, the communication device M1 acquires topographical information of the work site when the shovel starts work, for example, once a day. The GNSS surveying system employs, for example, a network-type RTK-GNSS positioning method.

The positioning device M2 is a device that measures the position and orientation of the shovel. In this embodiment, the positioning device M2 is a GNSS receiver with an integrated electronic compass, and measures the latitude, longitude, and altitude of the shovel's location, as well as the orientation of the shovel.

The attitude detection device M3 is a device that detects the attitude of the attachment. In this embodiment, the attitude detection device M3 is a device that detects the attitude of the excavation attachment.

The cylinder pressure detection device M4 is a device that detects the pressure of the hydraulic oil in the hydraulic cylinder. In this embodiment, the cylinder pressure detection device M4 includes a boom bottom pressure sensor that detects the pressure in the bottom oil chamber of the boom cylinder 7 (hereinafter referred to as the "boom bottom pressure").

Figure 2 is a side view of the excavator showing an example of the output contents of various sensors constituting the posture detection device M3 mounted on the excavator in Figure 1. Specifically, the posture detection device M3 includes a boom angle sensor M3a, an arm angle sensor M3b, a bucket angle sensor M3c, and a vehicle body inclination sensor M3d.

The boom angle sensor M3a is a sensor that acquires the boom angle θ1, and includes, for example, a rotation angle sensor that detects the rotation angle of the boom foot pin, a stroke sensor that detects the stroke amount of the boom cylinder 7, and an inclination (acceleration) sensor that detects the inclination angle of the boom 4. The boom angle θ1 is the angle of the line segment connecting the boom foot pin position P1 and the arm connecting pin position P2 with respect to the horizontal line in the XZ plane.

The arm angle sensor M3b is a sensor that acquires the arm angle θ2, and includes, for example, a rotation angle sensor that detects the rotation angle of the arm connecting pin, a stroke sensor that detects the stroke amount of the arm cylinder 8, and an inclination (acceleration) sensor that detects the inclination angle of the arm 5. The arm angle θ2 is the angle of the line segment connecting the arm connecting pin position P2 and the bucket connecting pin position P3 with respect to the horizontal line in the XZ plane.

The bucket angle sensor M3c is a sensor that acquires the bucket angle θ3, and includes, for example, a rotation angle sensor that detects the rotation angle of the bucket connecting pin, a stroke sensor that detects the stroke amount of the bucket cylinder 9, and an inclination (acceleration) sensor that detects the inclination angle of the bucket 6. The bucket angle θ3 is the angle of the line segment connecting the bucket connecting pin position P3 and the bucket toe position P4 with respect to the horizontal line in the XZ plane.

The vehicle body tilt sensor M3d is a sensor that acquires the tilt angle θ4 around the Y axis of the shovel and the tilt angle θ5 around the X axis of the shovel (not shown), and includes, for example, a two-axis tilt (acceleration) sensor. Note that the XY plane in FIG. 2 is a horizontal plane.

Next, the basic system of the excavator will be described with reference to FIG. 3. The basic system of the excavator mainly includes an engine 11, a main pump 14, a pilot pump 15, a control valve 17, an operating device 26, a controller 30, and an engine control unit (ECU) 74.

The engine 11 is the driving source of the excavator, and is, for example, a diesel engine that operates to maintain a predetermined rotation speed. The output shaft of the engine 11 is connected to the input shafts of the main pump 14 and the pilot pump 15.

The main pump 14 is a hydraulic pump that supplies hydraulic oil to the control valve 17 via a high-pressure hydraulic line 16, and is, for example, a swash plate type variable displacement hydraulic pump. The main pump 14 can adjust the stroke length of the piston by changing the angle (tilt angle) of the swash plate, thereby changing the discharge flow rate, i.e., the pump output. The swash plate of the main pump 14 is controlled by a regulator 14a. The regulator 14a changes the tilt angle of the swash plate in response to changes in the control current for the solenoid proportional valve (not shown). For example, by increasing the control current, the regulator 14a increases the tilt angle of the swash plate and increases the discharge flow rate of the main pump 14. Also, by decreasing the control current, the regulator 14a decreases the tilt angle of the swash plate and decreases the discharge flow rate of the main pump 14.

The pilot pump 15 is a hydraulic pump for supplying hydraulic oil to various hydraulic control devices via the pilot line 25, and is, for example, a fixed displacement hydraulic pump.

The control valve 17 is a hydraulic control valve that controls the hydraulic system of the forestry machine. The control valve 17 selectively supplies hydraulic oil supplied from the main pump 14 through the high-pressure hydraulic line 16 to one or more of the boom cylinder 7, arm cylinder 8, bucket cylinder 9, traveling hydraulic motor 1A (left), traveling hydraulic motor 1B (right), and swing hydraulic motor 2A, depending on pressure changes according to the operation direction and amount of levers or pedals 26A to 26C (described later). In the following description, the boom cylinder 7, arm cylinder 8, bucket cylinder 9, traveling hydraulic motor 1A (left), traveling hydraulic motor 1B (right), and swing hydraulic motor 2A are collectively referred to as "hydraulic actuators."

The operating device 26 is a device used by an operator to operate the hydraulic actuators. The operating device 26 supplies hydraulic oil supplied from the pilot pump 15 via the pilot line 25 through the pilot line 25a to the pilot ports of the flow control valves corresponding to each hydraulic actuator. The pressure of the hydraulic oil supplied to each pilot port is set to a pressure according to the direction and amount of operation of the levers or pedals 26A to 26C corresponding to each hydraulic actuator.

The controller 30 is a control device for controlling the shovel, and is composed of, for example, a computer equipped with a CPU, RAM, ROM, etc. The CPU of the controller 30 reads out programs corresponding to the operations and functions of the shovel from the ROM, loads them into the RAM, and executes the programs, thereby executing the processes corresponding to each of the programs.

The controller 30 controls the discharge flow rate of the main pump 14. For example, it changes the control current in response to the negative control pressure of a negative control valve (not shown) and controls the discharge flow rate of the main pump 14 via the regulator 14a.

The engine control unit (ECU) 74 is a device that controls the engine 11. For example, based on a command from the controller 30, it outputs to the engine 11 the fuel injection amount and the like for controlling the rotation speed of the engine 11 according to the engine rotation speed (mode) set by the operator using the engine rotation speed adjustment dial 75 described later.

The engine speed adjustment dial 75 is a dial provided inside the cabin 10 for adjusting the engine speed, and in this embodiment, the engine speed can be changed in five stages. That is, the engine speed adjustment dial 75 allows the engine speed to be changed in five stages: Rmax, R4, R3, R2, and R1. Note that FIG. 3 shows the state in which R4 is selected with the engine speed adjustment dial 75.

Rmax is the maximum engine speed of the engine 11 and is selected when the amount of work is to be prioritized. R4 is the second highest engine speed and is selected when both the amount of work and fuel efficiency are to be achieved. R3 and R2 are the third and fourth highest engine speeds and are selected when the excavator is to be operated with low noise while prioritizing fuel efficiency. R1 is the lowest engine speed (idling speed) and is the engine speed in the idling mode selected when the engine 11 is to be in an idling state. For example, Rmax (maximum speed) may be set to 2000 rpm, R1 (idling speed) may be set to 1000 rpm, and multiple steps may be set therebetween in increments of 250 rpm, such as R4 (1750 rpm), R3 (1500 rpm), and R2 (1250 rpm). The engine 11 is then constantly controlled at the engine speed set by the engine speed adjustment dial 75. Note that, although an example of adjusting the engine speed in five stages using the engine speed adjustment dial 75 is shown here, any number of stages is possible and is not limited to five stages.

The shovel also has an image display device 40 disposed near the driver's seat in the cabin 10 to assist the driver in driving. The driver can input information and commands to the controller 30 using the input unit 42 of the image display device 40. The shovel's operating status and control information can also be displayed on the image display unit 41 of the image display device 40, providing information to the driver.

The image display device 40 includes an image display unit 41 and an input unit 42. The image display device 40 is fixed to a console in the driver's seat. Generally, the boom 4 is disposed on the right side of the driver seated in the driver's seat, and the driver often operates the excavator while visually checking the arm 5 and bucket 6 attached to the tip of the boom 4. The frame on the front right side of the cabin 10 is a part that obstructs the driver's field of vision, but in this embodiment, this part is used to provide the image display device 40. As a result, the image display device 40 is disposed in a part that originally obstructed the field of vision, so that the image display device 40 itself does not significantly obstruct the driver's field of vision. Depending on the width of the frame, the image display device 40 may be configured so that the image display unit 41 is vertically long so that the entire image display device 40 fits within the width of the frame.

In this embodiment, the image display device 40 is connected to the controller 30 via a communication network such as CAN or LIN. The image display device 40 may also be connected to the controller 30 via a dedicated line.

The image display device 40 also includes a conversion processing unit 40a that generates an image to be displayed on the image display unit 41. In this embodiment, the conversion processing unit 40a generates a camera image to be displayed on the image display unit 41 based on the output of the imaging device M5. Therefore, the imaging device M5 is connected to the image display device 40 via, for example, a dedicated line. The conversion processing unit 40a also generates an image to be displayed on the image display unit 41 based on the output of the controller 30.

The conversion processing unit 40a may be realized as a function of the controller 30, rather than as a function of the image display device 40. In this case, the imaging device M5 is connected to the controller 30, rather than to the image display device 40.

The image display device 40 also includes a switch panel as an input unit 42. The switch panel is a panel that includes various hardware switches. In this embodiment, the switch panel includes a light switch 42a, a wiper switch 42b, and a window washer switch 42c as hardware buttons. The light switch 42a is a switch for switching the lights attached to the exterior of the cabin 10 on and off. The wiper switch 42b is a switch for switching the wipers on and off. The window washer switch 42c is a switch for spraying window washer fluid.

The image display device 40 operates by receiving power from the storage battery 70. The storage battery 70 is charged with power generated by the alternator 11a (generator) of the engine 11. The power of the storage battery 70 is also supplied to the controller 30, the electrical equipment 72 of the shovel other than the image display device 40, and the like. The starter 11b of the engine 11 is driven by power from the storage battery 70 to start the engine 11.

As described above, the engine 11 is controlled by the engine control unit (ECU) 74. The ECU 74 constantly transmits various data indicating the state of the engine 11 (for example, data indicating the cooling water temperature (physical quantity) detected by the water temperature sensor 11c) to the controller 30. Therefore, the controller 30 can store this data in a temporary storage unit (memory) 30a and transmit it to the image display device 40 when necessary.

In addition, various data are supplied to the controller 30 and stored in the temporary memory unit 30a of the controller 30 as follows:

First, data indicating the tilt angle of the swash plate is supplied to the controller 30 from the regulator 14a of the main pump 14, which is a variable displacement hydraulic pump. Data indicating the discharge pressure of the main pump 14 is also sent to the controller 30 from the discharge pressure sensor 14b. These data (data representing physical quantities) are stored in the temporary memory unit 30a. An oil temperature sensor 14c is also provided in the pipeline between the main pump 14 and a tank that stores the hydraulic oil to be sucked by the main pump 14, and data indicating the temperature of the hydraulic oil flowing through that pipeline is supplied from the oil temperature sensor 14c to the controller 30.

When the lever or pedals 26A to 26C are operated, the pilot pressure sent to the control valve 17 through the pilot line 25a is detected by the hydraulic sensors 15a and 15b, and data indicating the detected pilot pressure is supplied to the controller 30.

In addition, data indicating the engine speed setting status is constantly sent from the engine speed adjustment dial 75 to the controller 30.

The external calculation device 30E is a control device that performs various calculations based on the outputs of the communication device M1, the positioning device M2, the attitude detection device M3, the cylinder pressure detection device M4, the imaging device M5, etc., and outputs the calculation results to the controller 30. In this embodiment, the external calculation device 30E operates by receiving power from the storage battery 70.

Next, the function of the external calculation device 30E will be described with reference to FIG. 4. FIG. 4 is a functional block diagram showing an example of the configuration of the external calculation device 30E. In this embodiment, the external calculation device 30E receives outputs from the communication device M1, the positioning device M2, the attitude detection device M3, and the cylinder pressure detection device M4, executes various calculations, and outputs the calculation results to the controller 30. The controller 30 outputs, for example, a control command according to the calculation results to the control valve E1. The control valve E1 is a valve for controlling the movement of the attachment, and is, for example, a regeneration release valve 50, a pressure reducing valve for adjusting the pilot pressure, a relief valve, etc.

Specifically, the external calculation device 30E mainly includes a terrain database update unit 31, a position coordinate update unit 32, a ground shape information acquisition unit 33, and a ground contact determination unit 34.

The terrain database update unit 31 is a functional element that updates the terrain database that systematically stores the terrain information of the work site so that it can be referenced. In this embodiment, the terrain database update unit 31 acquires the terrain information of the work site through the communication device M1, for example, when the shovel is started, and updates the terrain database. The terrain database is stored in a non-volatile memory or the like. In addition, the terrain information of the work site is described, for example, in a three-dimensional terrain model based on the global positioning system.

The position coordinate update unit 32 is a functional element that updates the coordinates and orientation that represent the current position of the shovel. In this embodiment, the position coordinate update unit 32 acquires the position coordinates and orientation of the shovel in the global positioning system based on the output of the positioning device M2, and updates the data related to the coordinates and orientation that represent the current position of the shovel that are stored in a non-volatile memory or the like.

The ground shape information acquisition unit 33 is a functional element that acquires information about the current shape of the ground to be excavated. In this embodiment, the ground shape information acquisition unit 33 acquires information about the current shape of the ground to be excavated based on the terrain information updated by the terrain database update unit 31, the coordinates and orientation representing the current position of the shovel updated by the position coordinate update unit 32, the past changes in the attitude of the excavation attachment detected by the attitude detection device M3, and the boom bottom pressure detected by the cylinder pressure detection device M4.

Here, referring to FIG. 5, the process of the ground shape information acquisition unit 33 acquiring information on the ground shape after the excavation operation will be described. FIG. 5 is a conceptual diagram of information on the ground shape after the excavation operation. Note that the multiple bucket shapes shown by the dashed lines in FIG. 5 represent the trajectory of the bucket 6 during the previous excavation operation. The trajectory of the bucket 6 is derived from the transition of the posture of the excavation attachment previously detected by the posture detection device M3. Also, the thick solid line in FIG. 5 represents the current cross-sectional shape of the ground to be excavated as grasped by the ground shape information acquisition unit 33, and the thick dotted line represents the cross-sectional shape of the ground to be excavated before the previous excavation operation as grasped by the ground shape information acquisition unit 33. That is, the ground shape information acquisition unit 33 derives the current shape of the ground to be excavated by removing the part corresponding to the space through which the bucket 6 passed during the previous excavation operation from the shape of the ground to be excavated before the previous excavation operation. In this way, the ground shape information acquisition unit 33 can estimate the ground shape after the excavation operation. Additionally, each block extending in the Z-axis direction shown by the dashed dotted line in FIG. 5 represents an element of the three-dimensional terrain model. Each element is represented, for example, by a model having a unit area upper surface parallel to the XY plane and an infinite length in the -Z direction. The three-dimensional terrain model may also be represented by a three-dimensional mesh model.

Next, the process in which the ground shape information acquisition unit 33 acquires information on the ground shape after the soil discharge operation (hereinafter referred to as "ground shape acquisition process after soil discharge") will be described with reference to Figures 6 to 8. Figure 6 is a flowchart showing an example of the flow of the ground shape acquisition process after soil discharge. The ground shape information acquisition unit 33 executes the ground shape acquisition process after soil discharge when soil discharge operation is performed. For example, the ground shape information acquisition unit 33 executes the ground shape acquisition process after soil discharge when a bucket opening operation is performed after an excavation operation.

First, the ground shape information acquisition unit 33 estimates the amount of soil loaded (step S1). In this embodiment, the ground shape information acquisition unit 33 estimates the amount of soil loaded based on the attitude of the excavation attachment detected by the attitude detection device M3 and the boom bottom pressure detected by the cylinder pressure detection device M4. The amount of soil loaded is the amount of soil loaded into the bucket 6 by the excavation operation, and is calculated, for example, as the volume of soil loaded into the bucket 6. The amount of soil loaded is also limited by a predetermined maximum loading amount.

For example, the ground shape information acquisition unit 33 refers to a boom bottom pressure reference table to acquire the unloaded boom bottom pressure corresponding to the current posture of the excavation attachment. The unloaded boom bottom pressure means the boom bottom pressure when no soil is loaded in the bucket 6. The boom bottom pressure table is a reference table stored in advance in a ROM or the like, and is generated based on the analysis of actual measurement data. Specifically, the boom bottom pressure table stores the unloaded boom bottom pressure in association with the posture of the attachment detected by the posture detection device M3. Then, the weight of the soil loaded in the bucket 6 is estimated based on the difference between the current boom bottom pressure and the unloaded boom bottom pressure. Then, the volume of the soil loaded in the bucket 6 is estimated from the estimated soil weight and the soil properties (density, viscosity, etc.) input in advance.

The ground shape information acquisition unit 33 may also estimate the amount of soil and sand loaded based on changes in the ground shape.

Then, the ground shape information acquisition unit 33 calculates the amount of sediment discharged (step S2). In this embodiment, the ground shape information acquisition unit 33 calculates the amount of sediment discharged based on the amount of sediment loaded and the sediment discharge rate. Specifically, the ground shape information acquisition unit 33 calculates the amount of sediment discharged by multiplying the amount of sediment loaded by the sediment discharge rate.

The amount of soil discharged is the amount of soil discharged from the bucket 6 by the soil discharge operation, and is calculated by multiplying the soil load by the soil discharge rate. The amount of soil discharged is calculated, for example, as the volume of soil discharged by the bucket 6, similar to the soil load.

The soil discharge rate is the ratio of the soil discharge amount to the soil load amount, and is determined based on the change in the attachment's posture during soil discharge, the change in operating speed, the soil characteristics, etc. In this embodiment, the ground shape information acquisition unit 33 determines the soil discharge rate by referring to a soil discharge rate table. The soil discharge rate table is a reference table stored in advance in a ROM or the like, and is generated based on the analysis of actual measurement data. Specifically, the soil discharge rate table stores the soil discharge rate in association with the bucket angle during soil discharge detected by the posture detection device M3.

Figure 7 is a diagram showing the relationship between the bucket angle θ3 and the soil discharge rate. Specifically, Figure 7 (A) shows the attitude of the bucket 6 when the bucket angle is 30° and the attitude of the bucket 6 when the bucket angle is 180°. Also, Figure 7 (B) shows the transition of the soil discharge rate with respect to the bucket angle θ3. As shown in Figure 7 (B), the soil discharge rate is set to 0 [%] when the bucket angle θ3 is approximately 150 degrees or more. That is, the ground shape information acquisition unit 33 estimates that the soil in the bucket 6 has not yet been discharged if the bucket angle θ3 is approximately 150 degrees or more. On the other hand, the soil discharge rate increases as the bucket angle θ3 falls below approximately 150 degrees, and reaches 100 [%] when the bucket angle θ3 is approximately 50 degrees or less. That is, the ground shape information acquisition unit 33 estimates that all the soil in the bucket 6 has been discharged if the bucket angle θ3 is approximately 50 degrees or less.

Then, the ground shape information acquisition unit 33 estimates the ground shape after the soil discharge operation (step S3). In this embodiment, the ground shape information acquisition unit 33 estimates the ground shape after the soil discharge operation based on the amount of soil discharged, the ground shape before the most recent soil discharge operation, the height of the bucket 6 relative to the ground during the soil discharge operation, the change in the attachment's attitude during the soil discharge operation, the change in the operating speed, the soil characteristics, etc.

Figure 8 is a conceptual diagram of information on the ground shape after the soil dumping operation. Figure 8 (A) is a diagram showing the positional relationship between the dumped soil and the shovel, and the reference point RP is a point obtained by projecting the center point of the bucket 6 when the soil dumping operation starts onto the horizontal plane on which the shovel is located. The start of the soil dumping operation is, for example, the start of the bucket opening operation. The shape shown by the dashed line in Figure 8 (A) shows the shape of the part of the ground shape after the soil dumping operation that has been updated by the most recent soil dumping operation (hereinafter referred to as the "updated part shape"). In the following, the conditions of the soil dumping operation (including, for example, the amount of soil dumped, etc.) that resulted in the updated part shape shown by the dashed line in Figure 8 (A) are referred to as the "reference soil dumping conditions".

In addition, each of Figures 8(B1) to 8(B6) shows various updated partial shapes after the soil discharge operation that result from different soil discharge operation conditions, and the updated partial shapes shown by dashed lines in each figure correspond to the updated partial shape shown by dashed lines in Figure 8(A).

Specifically, the updated portion shape shown by the thick solid line in Figure 8 (B1) corresponds to the updated portion shape when the amount of sediment discharged is greater than that under the standard discharge conditions. In this way, the updated portion shape is determined to be larger as the amount of sediment discharged is greater.

The updated portion shape shown by the thick solid line in FIG. 8 (B2) corresponds to the updated portion shape when the ground shape before the most recent soil dumping operation is higher at the reference point RP than under the reference soil dumping conditions. In this way, the updated portion shape is determined according to the size (height) of the raised portion of the ground shape before the most recent soil dumping operation is performed.

The updated portion shape shown by the thick solid line in FIG. 8 (B3) corresponds to the updated portion shape when the ground shape before the most recent soil discharge operation is more depressed at the reference point RP than under the reference soil discharge conditions. In this way, the updated portion shape is determined according to the size (depth) of the depressed portion of the ground shape before the most recent soil discharge operation is performed.

The updated portion shape shown by the thick solid line in FIG. 8 (B4) corresponds to the updated portion shape when the height of the bucket 6 relative to the reference point RP during the most recent earth-discharging operation is higher than that under the reference earth-discharging conditions. In this way, the updated portion shape is determined so that it becomes lower and spreads out more to the periphery the higher the height of the bucket 6 during the most recent earth-discharging operation.

The updated portion shape shown by the thick solid line in FIG. 8 (B5) corresponds to the updated portion shape when the viscosity of the soil discharged in the most recent soil discharge operation is lower than that under the reference soil discharge conditions. In this way, the updated portion shape is determined so that it becomes lower and spreads out more to the surrounding area the lower the viscosity of the soil discharged in the most recent soil discharge operation.

The updated portion shape shown by the thick solid line in FIG. 8 (B6) corresponds to the updated portion shape when the operating speed (opening speed) of the bucket 6 during the most recent earth-discharging operation is faster than that under the reference earth-discharging conditions. In this way, the updated portion shape is determined so that the faster the opening speed of the bucket 6 during the most recent earth-discharging operation, the more biased the bucket 6 is in the opening direction with respect to the reference point RP.

In addition, in this embodiment, the ground shape information acquisition unit 33 determines the updated part shape by referring to the updated part shape table. The updated part shape table is a reference table stored in advance in a ROM or the like, and is generated based on the analysis of actual measurement data. Specifically, the updated part shape table stores the updated part shape in association with the amount of soil discharged, the ground shape before the most recent soil discharge operation, the height of the bucket 6 during the soil discharge operation, the transition of the attachment's attitude during the soil discharge operation, the transition of the operating speed, soil characteristics, etc.

In this way, the ground shape information acquisition unit 33 can estimate the ground shape after the soil discharge operation. Therefore, the ground shape information acquisition unit 33 can acquire not only information about the ground shape after the excavation operation, but also information about the ground shape after the soil discharge operation. In other words, the ground shape information acquisition unit 33 can more accurately grasp the shape of the ground to be excavated before the excavation operation is performed. The information acquired in this way is displayed on the display device 40. It may also be transmitted via the communication device M1 to a management device that manages the operating status of multiple excavators. The management device may then display the received information.

The ground contact determination unit 34 is a functional element that determines whether the attachment is in contact with the ground and controls the attachment. In this embodiment, the ground contact determination unit 34 determines whether the excavation attachment is in contact with the ground based on information about the current shape of the ground to be excavated acquired by the ground shape information acquisition unit 33, and controls the excavation attachment.

Specifically, the ground contact determination unit 34 determines the excavation state based on the current posture of the excavation attachment detected by the posture detection device M3 and the information on the current shape of the ground surface to be excavated acquired by the ground surface shape information acquisition unit 33. For example, the ground contact determination unit 34 determines whether the tip of the bucket 6 is in contact with the ground surface to be excavated. If it is determined that the tip of the bucket 6 is in contact with the ground surface to be excavated, the ground contact determination unit 34 outputs the determination result to the controller 30. The controller 30, which has received the determination result, outputs a control command to the regeneration release valve 50 as the control valve E1 to increase its opening area. The ground contact determination unit 34 may output the determination result that the tip of the bucket 6 will contact the ground surface to be excavated to the controller 30 just before the tip of the bucket 6 contacts the ground surface to be excavated. Furthermore, the excavation attachment may be controlled based on soil density information input in advance. In addition, although an example in which the external calculation device 30E is provided separately from the controller 30 has been described above, the controller 30 and the external calculation device 30E may be configured integrally.

Next, an example of control when the present invention is applied will be described. Figure 9 shows an example of the configuration of a drive system mounted on the excavator of Figure 1, with the mechanical power transmission line, high-pressure hydraulic line, pilot line, and electrical control line indicated by double lines, solid lines, dashed lines, and dotted lines, respectively.

In this configuration example, the drive system of the excavator mainly includes the engine 11, main pumps 14L and 14R, pilot pump 15, control valve 17, operation device 26, operation content detection device 29, controller 30, and external calculation device 30E.

The control valve 17 includes flow control valves 171-176 that control the flow of hydraulic oil discharged by the main pumps 14L and 14R. The control valve 17 selectively supplies hydraulic oil discharged by the main pumps 14L and 14R to one or more of the boom cylinder 7, arm cylinder 8, bucket cylinder 9, traveling hydraulic motor 1A (left), traveling hydraulic motor 1B (right), and swing hydraulic motor 2A through the flow control valves 171-176. The operation device 26 is a device used by an operator to operate the hydraulic actuators. In this embodiment, the operation device 26 supplies hydraulic oil discharged by the pilot pump 15 to the pilot ports of the flow control valves corresponding to each hydraulic actuator through the pilot line 25. The operation content detection device 29 is a device that detects the operation content of the operator using the operation device 26. In this embodiment, the operation content detection device 29 detects the operation direction and operation amount of the lever or pedal of the operation device 26 corresponding to each hydraulic actuator in the form of pressure, and outputs the detected value to the controller 30. Note that the operation content of the operation device 26 may be derived using the output of a sensor other than a pressure sensor, such as a potentiometer.

Main pumps 14L and 14R, driven by engine 11, circulate hydraulic oil through center bypass lines 40L and 40R to the hydraulic oil tank.

The center bypass line 40L is a high-pressure hydraulic line that passes through the flow control valves 171, 173, and 175 arranged in the control valve 17, and the center bypass line 40R is a high-pressure hydraulic line that passes through the flow control valves 172, 174, and 176 arranged in the control valve 17.

The flow control valves 171, 172, and 173 are spool valves that control the flow rate and direction of hydraulic oil flowing in and out of the travel hydraulic motor 1A (left), travel hydraulic motor 1B (right), and turning hydraulic motor 2A.

Furthermore, the flow control valves 174, 175, and 176 are spool valves that control the flow rate and flow direction of the hydraulic oil flowing in and out of the bucket cylinder 9, arm cylinder 8, and boom cylinder 7. In this embodiment, a regeneration oil passage is formed inside the flow control valve 175. In addition, a regeneration release valve 50 is installed between the flow control valve 175 and the hydraulic oil tank.

Figure 10 is a diagram showing an example of the configuration of the regeneration oil passage and the regeneration release valve. Specifically, Figure 10(A) is an enlarged view of a portion including the flow control valve 175 and the regeneration release valve 50 in the control valve 17 shown in Figure 9. Also, Figure 10(B) shows the flow of hydraulic oil when the opening area of the regeneration release valve 50 is minimized during the arm closing operation, and Figure 10(C) shows the flow of hydraulic oil when the opening area of the regeneration release valve 50 is maximized during the arm closing operation.

The regeneration oil passage 175a is an oil passage that allows hydraulic oil flowing out of the rod side oil chamber of the arm cylinder 8, which is the contraction side oil chamber, to flow (regenerate) into the bottom side oil chamber, which is the extension side oil chamber, during the arm closing operation. The regeneration oil passage 175a also includes a check valve that prevents hydraulic oil from flowing from the bottom side oil chamber to the rod side oil chamber. The regeneration oil passage 175a may be formed outside the flow control valve 175.

The regeneration release valve 50 is a valve that adjusts the flow rate of hydraulic oil that flows out of the rod side oil chamber of the arm cylinder 8 and into the hydraulic oil tank. In this embodiment, the regeneration release valve 50 is an electromagnetic valve that operates in response to a control command from the controller 30, and adjusts the flow rate of hydraulic oil flowing through each of the oil passage 50a and the regeneration oil passage 175a by increasing or decreasing the flow area of the oil passage 50a between the flow control valve 175 and the hydraulic oil tank.

Specifically, as shown in FIG. 10(B), the regeneration release valve 50 reduces the opening area in response to a control command from the controller 30 to reduce the flow rate of hydraulic oil flowing through the oil passage 50a and to increase the flow rate of hydraulic oil flowing through the regeneration oil passage 175a. With this configuration, the regeneration release valve 50 can prevent the arm 5 from falling under its own weight when the excavation attachment is operated in the air.

As shown in FIG. 10(C), the regeneration release valve 50 increases its opening area in response to a control command from the controller 30 to increase the flow rate of hydraulic oil flowing through the oil passage 50a and reduce or eliminate the flow rate of hydraulic oil flowing through the regeneration oil passage 175a. With this configuration, the regeneration release valve 50 can prevent unnecessary pressure loss in the oil passage 50a, which would reduce the excavation force, even when excavation is in progress, i.e., even when the excavation attachment is in contact with the ground.

The regeneration release valve 50 may be installed between the rod side oil chamber of the arm cylinder 8 and the flow control valve 175.

Next, referring to FIG. 11, the process in which the controller 30 adjusts the opening area of the regeneration release valve 50 (hereinafter referred to as the "opening area adjustment process") will be described. FIG. 11 is a flowchart showing the flow of the opening area adjustment process. The controller 30 repeatedly executes this opening area adjustment process at a predetermined control period while the excavator is in operation.

First, the controller 30 determines whether an arm closing operation has been performed (step S11). In this embodiment, the controller 30 determines whether the arm operating lever has been operated in the closing direction based on the output of the operation content detection device 29.

If it is determined that the arm closing operation has not been performed, the controller 30 ends the current opening area adjustment process.

When it is determined that the arm closing operation has been performed, the controller 30 determines whether the excavation attachment is in contact with the ground based on the calculation results of the external calculation device 30E (step S12). In this embodiment, the external calculation device 30E determines whether the tip of the bucket 6 is in contact with the ground based on the current position of the tip of the bucket 6 derived from the output of the attitude detection device M3 and information on the current shape of the ground to be excavated acquired by the ground shape information acquisition unit 33. Note that the information on the current shape of the ground to be excavated is information that reflects information on the ground shape after the excavation operation and information on the ground shape after the soil discharge operation.

If the external calculation device 30E determines that the excavation attachment is in contact with the ground, the controller 30 increases the opening area of the regeneration release valve 50 as necessary (step S13). In this embodiment, if the external calculation device 30E determines that the toe of the bucket 6 is in contact with the ground, it outputs the determination result to the controller 30. In response to the determination result, if the opening area of the regeneration release valve 50 is less than a predetermined value, the controller 30 increases the opening area to the predetermined value.

On the other hand, if the external calculation device 30E determines that the excavation attachment is not in contact with the ground, the controller 30 reduces the opening area of the regeneration release valve 50 as necessary (step S14). In this embodiment, if the external calculation device 30E determines that the toe of the bucket 6 is not in contact with the ground, it outputs the determination result to the controller 30. The controller 30, upon receiving the determination result, reduces the opening area of the regeneration release valve 50 to the predetermined value if the opening area of the regeneration release valve 50 is larger than a predetermined value.

Next, referring to FIG. 12, the time transition of various parameters when the controller 30 adjusts the opening area of the regeneration release valve 50 will be described. FIG. 12(A) shows the time transition of the pressure in the rod side oil chamber of the arm cylinder 8. FIG. 12(B) shows the time transition of the ground contact flag, and FIG. 12(C) shows the time transition of the opening area of the regeneration release valve 50. The time axis (horizontal axis) of each of FIG. 12(A) to FIG. 12(C) is common. The ground contact flag indicates the result of the judgment by the external calculation device 30E of the presence or absence of contact between the excavation attachment and the ground. Specifically, the value "OFF" of the ground contact flag indicates a state in which the external calculation device 30E judges that there is no contact, and the value "ON" of the ground contact flag indicates a state in which the external calculation device 30E judges that there is contact. The transition shown by the solid line in FIG. 12 indicates the transition when actual contact and the judgment of "contact" are made simultaneously. On the other hand, the transition shown by the dashed line in FIG. 12 represents the transition when the "contact" determination is made before the actual contact, and the transition shown by the dashed dotted line in FIG. 12 represents the transition when the "contact" determination is made after the actual contact.

Specifically, when the determination of "contact" is made before actual contact, the ground contact flag is switched from the value "OFF" to the value "ON" at time t1, as shown by the dashed line in FIG. 12(B). In this embodiment, actual contact occurs at time t2. When the ground contact flag is switched to the value "ON", the controller 30 increases the opening area of the regeneration release valve 50. Therefore, the opening area of the regeneration release valve 50 is adjusted from the value An to the value Aw (> An) at time t1, as shown by the dashed line in FIG. 12(C). Note that the value An is the opening area that is preset as the optimal value when the arm 5 is operated in the air, and the value Aw is the opening area that is preset as the optimal value when the arm 5 is operated during excavation. As a result, the pressure in the rod side oil chamber of the arm cylinder 8 begins to decrease at time t1, as shown by the dashed line in FIG. 12(A), and continues to decrease until actual contact occurs. This is because the arm 5 falls under its own weight. Then, after actual contact occurs at time t2 (between time t2 and time t3), it starts to increase, and then increases to a value corresponding to the excavation reaction force as a work reaction force.

In this way, if the controller 30 determines that "contact has occurred" before actual contact occurs, it will temporarily and suddenly reduce the pressure in the rod-side oil chamber of the arm cylinder 8, which may cause cavitation.

On the other hand, if the "contact" determination is made after the actual contact, the opening area of the regeneration release valve 50 remains small at time t2 when the actual contact occurs, so the pressure in the rod-side oil chamber rises. Then, the ground contact flag is switched from the value "OFF" to the value "ON" at time t3, as shown by the dashed line in FIG. 12(B). Therefore, the opening area of the regeneration release valve 50 is adjusted from the value An to the value Aw at time t3, as shown by the dashed line in FIG. 12(C). As a result, the pressure in the rod-side oil chamber of the arm cylinder 8 begins to increase at time t2 when the actual contact occurs, as shown by the dashed line in FIG. 12(A), and continues to increase until the opening area of the regeneration release valve 50 is increased to the value Aw at time t3. This is because it is affected by the excavation reaction force and the pressure loss in the regeneration release valve 50. Then, at time t3, the opening area of the regeneration release valve 50 increases to a value Aw, which then starts to decrease, and then decreases to a value corresponding to the excavation reaction force.

In this way, if the controller 30 determines that there is contact after actual contact has occurred, it temporarily increases the pressure in the rod-side oil chamber of the arm cylinder 8, which destabilizes the movement of the excavation attachment and reduces work efficiency.

The external calculation device 30E therefore determines whether the excavation attachment is in contact with the ground surface to be excavated based on the current attitude of the excavation attachment detected by the attitude detection device M3 and information on the current shape of the ground surface to be excavated acquired by the ground surface shape information acquisition unit 33. This is to make the "contact" determination at the same time as the actual contact occurs.

When the "contact" determination is made simultaneously with actual contact, the ground contact flag is switched from the value "OFF" to the value "ON" at time t2, as shown by the solid line in FIG. 12(B). Therefore, the opening area of the regeneration release valve 50 is adjusted from the value An to the value Aw at time t2, as shown by the solid line in FIG. 12(C). As a result, the pressure in the rod side oil chamber of the arm cylinder 8 begins to decrease at time t2 when actual contact occurs, as shown by the solid line in FIG. 12(A), and thereafter decreases to a value corresponding to the excavation reaction force. There is no temporary, sudden decrease before actual contact occurs, and there is no increase due to the influence of pressure loss in the regeneration release valve 50 after actual contact occurs.

With the above configuration, the controller 30 acquires information on the current shape of the ground to be worked on based on information on the ground shape after the excavation operation and information on the ground shape after the soil discharge operation. Then, the attachment is controlled based on the acquired information on the current shape of the ground to be worked on. In this embodiment, the controller 30 adjusts the opening area of the regeneration release valve 50 based on the current posture of the excavation attachment and the current shape of the ground to be excavated. Specifically, the opening area of the regeneration release valve 50 is adjusted based on the current position of the tip of the bucket 6 and the current shape of the ground to be excavated. Therefore, at the same time that the tip of the bucket 6 contacts the ground to be excavated, the pressure loss in the regeneration release valve 50 of the hydraulic oil flowing out from the rod side oil chamber of the arm cylinder 8 to the hydraulic oil tank can be reduced or eliminated. As a result, the controller 30 can more accurately determine the presence or absence of contact and suppress erroneous determination compared to the case where the presence or absence of contact between the tip of the bucket 6 and the ground to be excavated is determined based on the change in the arm cylinder pressure, etc. In addition, by suppressing erroneous determination of the presence or absence of contact, operability and work efficiency can be improved. Specifically, at the same time that the tip of the bucket 6 comes into contact with the ground, the pressure loss that occurs at the regeneration release valve 50 to prevent the arm 5 from falling under its own weight can be reduced or eliminated, preventing the force required for excavation from increasing by the amount of pressure loss. In addition, the arm 5 can be prevented from falling under its own weight before coming into contact with the ground, preventing the occurrence of cavitation.

The controller 30 can also accurately estimate the current shape of the ground being worked on, not only when excavation is taking place, but also when filling, backfilling, etc. are taking place. This allows accurate prediction of the timing at which the toe of the bucket 6 will come into contact with the ground being excavated, and allows more appropriate determination of the control timing of the control valves E1, such as the regeneration release valve 50.

In addition, the controller 30 may adjust the opening area of the regeneration release valve (not shown) for the boom cylinder 7, and may adjust the opening area of the regeneration release valve (not shown) for the bucket cylinder 9, in the same way as it adjusts the opening area of the regeneration release valve 50 for the arm cylinder 8.

Next, referring to Figures 13 to 15, another embodiment of excavation attachment control by the ground contact determination unit 34 of the external computing device 30E will be described. Note that Figure 13 is a diagram showing the relationship between the depth of the ground to be excavated and the reference plane. The reference plane is a plane that serves as a reference for determining the depth of the ground to be excavated. In this embodiment, the reference plane is a horizontal plane on which the center point R of the shovel is located, and the center point R is the intersection of the swivel axis and the ground contact surface of the lower traveling body 1.

Specifically, the excavation attachment shown by the dashed dotted line in FIG. 13 represents the posture of the excavation attachment when excavating the ground to be excavated at the same depth as the reference plane shown by the dashed dotted line. In this case, the depth D of the ground to be excavated is the same as the depth D0 (=0) of the reference plane. Note that the depth D of the ground to be excavated is derived based on information regarding the current shape of the ground to be excavated acquired by the ground shape information acquisition unit 33. The depth D of the ground to be excavated may also be derived based on the current posture of the excavation attachment detected by the posture detection device M3.

The digging attachment shown by the dashed line in FIG. 13 represents the posture of the digging attachment when digging the ground to be excavated shown by the dashed line. In this case, the depth D of the ground to be excavated is represented by depth D1 (>D0).

The excavation attachment shown by the solid line in FIG. 13 represents the posture of the excavation attachment when excavating the ground to be excavated shown by the solid line. In this case, the depth D of the ground to be excavated is represented by depth D2 (>D1).

The ground to be excavated may be located higher than the reference level. In this case, the depth D of the ground to be excavated may be expressed as a negative value.

Figure 14 is a diagram showing the relationship between bucket angle θ3 and excavation reaction force F. Specifically, Figure 14 (A) shows the change in the attitude of the bucket 6 when the bucket 6 is closed from a bucket angle of 30° to a bucket angle of 180°. Note that the bucket 6 shown by the dashed line in Figure 14 (A) represents the attitude when the bucket angle is 30°, and the bucket 6 shown by the solid line in Figure 14 (A) represents the attitude when the bucket angle is 180°.

Figure 14 (B) shows an example of the contents of a correspondence table that prestores the correspondence between the depth D of the ground to be excavated and the transition or peak value of the excavation reaction force F when a specified bucket closing operation is performed. Specifically, Figure 14 (B) shows the transition of the excavation reaction force F with respect to the bucket angle θ3 when closing the bucket 6 from a bucket angle of 30° to a bucket angle of 180°. The correspondence table is a data table that is generated based on the analysis of actual measurement data, and is preregistered in a non-volatile memory, for example.

Figure 14(C) shows the time progression of the bucket angle θ3, and Figure 14(D) shows the time progression of the excavation reaction force F calculated using the correspondence table in Figure 14(B). Note that the time axis (horizontal axis) of Figure 14(C) and Figure 14(D) is the same.

The transitions shown by the dashed lines in Figures 14(B) and 14(D) represent the transitions when the depth D of the ground to be excavated is depth D0. The transitions shown by the dashed lines represent the transitions when the depth D of the ground to be excavated is depth D1, and the transitions shown by the solid lines represent the transitions when the depth D of the ground to be excavated is depth D2.

When the bucket is closed with a bucket angle of 30° to 180° as shown in Figures 14(A) and 14(C), the excavation reaction force F increases until the bucket angle θ3 reaches a certain angle (e.g., 100°) and then starts to decrease, as shown in Figures 14(B) and 14(D), and reaches zero when the bucket angle θ3 reaches 180°. This tendency is the same regardless of the depth D of the ground to be excavated. However, the peak value of the excavation reaction force F changes according to the change in the depth D of the ground to be excavated. Figures 14(B) and 14(D) show, as an example, the tendency for the peak value of the excavation reaction force F to increase as the depth D of the ground to be excavated increases.

Therefore, the ground contact determination unit 34 of the external calculation device 30E derives the current depth D of the ground to be excavated based on the information on the current shape of the ground to be excavated acquired by the ground shape information acquisition unit 33. Then, the ground contact determination unit 34 estimates the peak value of the excavation reaction force F when a predetermined bucket closing operation is performed according to the current depth D of the ground to be excavated. Then, the ground contact determination unit 34 determines whether the estimated peak value of the excavation reaction force F exceeds a predetermined value. If it is determined that it exceeds the predetermined value, the ground contact determination unit 34 controls the movement of the excavation attachment so that the peak value does not exceed the predetermined value. This is to prevent the excavation reaction force F from becoming too large and causing the movement of the excavation attachment to become unstable. For example, the ground contact determination unit 34 automatically raises the boom 4 during the bucket closing operation, regardless of whether the operator raises the boom, so that the peak value of the excavation reaction force F does not exceed the predetermined value. For example, the ground contact determination unit 34 automatically raises the boom 4 at a rise rate (rotation angle of the boom 4 per unit time) that the operator does not notice. Therefore, the ground contact determination unit 34 can smooth the movement of the excavation attachment without the operator noticing that the boom 4 has automatically risen, improving the operability. In this case, the control target of the ground contact determination unit 34 is the flow control valve 176, not the regeneration release valve 50. For example, the ground contact determination unit 34 outputs a determination result that the estimated peak value of the excavation reaction force F exceeds a predetermined value to the controller 30. The controller 30, which receives this determination result, outputs a control command to a solenoid valve (not shown) serving as a control valve E1 that increases or decreases the pilot pressure of the flow control valve 176, thereby automatically moving the flow control valve 176.

Figure 15 is a flow chart showing the flow of the process (hereinafter referred to as "automatic posture adjustment process") in which the controller 30 automatically adjusts the posture of the excavation attachment so that the peak value of the excavation reaction force F does not exceed a predetermined value. The controller 30 repeatedly executes this automatic posture adjustment process at a predetermined control period while the excavator is in operation.

First, the controller 30 determines whether an excavation operation has been performed (step S21). In this embodiment, the controller 30 determines whether at least one of a boom operation, an arm operation, and a bucket operation has been performed based on the output of the operation content detection device 29.

If it is determined that an excavation operation has been performed (YES in step S21), the controller 30 determines whether the excavation attachment is in contact with the ground based on the calculation results of the external calculation device 30E (step S22). In this embodiment, the external calculation device 30E determines whether the toe of the bucket 6 is in contact with the ground based on the current position of the toe of the bucket 6 derived from the output of the attitude detection device M3 and information regarding the current shape of the ground to be excavated acquired by the ground shape information acquisition unit 33.

If it is determined that the excavation attachment is in contact with the ground (YES in step S22), the external calculation device 30E estimates the peak value of the excavation reaction force F (step S23). In this embodiment, the external calculation device 30E derives the current depth D of the ground to be excavated based on information on the current shape of the ground to be excavated acquired by the ground shape information acquisition unit 33. Then, the external calculation device 30E estimates the peak value of the excavation reaction force F when a predetermined bucket closing operation is performed according to the current depth D of the ground to be excavated. Specifically, the external calculation device 30E derives the peak value of the excavation reaction force F corresponding to the current depth D of the ground to be excavated by referring to a correspondence table such as that shown in FIG. 14 (B). In addition, the external calculation device 30E may calculate in real time the peak value of the excavation reaction force F when a predetermined bucket closing operation is performed based on the current depth D of the ground to be excavated. In addition, the external calculation device 30E may take into account the soil density, etc. when calculating the peak value. The soil density may be a value input by the operator through an on-board input device (not shown), or it may be a value calculated automatically based on the output of various sensors such as a cylinder pressure sensor.

Then, the external calculation device 30E determines whether the peak value of the estimated excavation reaction force F exceeds a predetermined value Fth (step S24).

If the external calculation device 30E determines that the peak value exceeds the predetermined value Fth (YES in step S24), the controller 30 automatically adjusts the attitude of the excavation attachment during the bucket closing operation (step S25). In this embodiment, the controller 30 automatically raises the boom 4 during the bucket closing operation, regardless of whether or not the operator performs a boom raising operation. Specifically, the controller 30 automatically raises the boom 4 in a predetermined operation pattern according to the change in the bucket angle θ3.

If the controller 30 determines that no excavation operation is being performed (NO in step S21), if the external calculation device 30E determines that the excavation attachment is not in contact with the ground (NO in step S22), or if the external calculation device 30E determines that the peak value is equal to or less than the predetermined value Fth (NO in step S24), the controller 30 ends the current automatic attitude adjustment process without automatically adjusting the attitude of the excavation attachment.

With the above configuration, the external calculation device 30E acquires information on the current shape of the ground surface to be worked on based on information on the ground surface shape after the excavation operation and information on the ground surface shape after the soil discharge operation. Then, the attachment is controlled based on the acquired information on the current shape of the ground surface to be worked on. In this embodiment, the external calculation device 30E can prevent the peak value of the excavation reaction force F from exceeding a predetermined value Fth during the bucket closing operation. This prevents the excavation reaction force F from increasing excessively, causing the movement of the excavation attachment to become unstable, improving the operability and work efficiency of the excavator. In addition, by using a low set predetermined value Fth, the external calculation device 30E can achieve the same effect in work other than excavation work, such as floor digging work and leveling work.

The above describes in detail preferred embodiments of the present invention, but the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention.

For example, in the above embodiment, the external calculation device 30E determines whether the excavation attachment is in contact with the ground surface to be excavated based on the current attitude of the excavation attachment detected by the attitude detection device M3 and the information on the current shape of the ground surface to be excavated acquired by the ground surface shape information acquisition unit 33. If it is determined that the excavation attachment is in contact with the ground surface to be excavated, the controller 30 outputs a control command to the regeneration release valve 50 to increase its opening area. Alternatively, if it is determined that the excavation attachment is in contact with the ground surface, the controller 30 estimates the peak value of the excavation reaction force F when a predetermined bucket closing operation is performed, and when the estimated peak value exceeds a predetermined value Fth, the boom 4 is automatically raised so that the actual peak value is equal to or less than the predetermined value Fth. However, the present invention is not limited to these configurations. For example, if it is determined that the excavation attachment is in contact with the ground surface, the external calculation device 30E may increase the driving force of the attachment (e.g., the excavation force by the excavation attachment). Specifically, the external calculation device 30E may increase the rotation speed of the engine 11 or increase the discharge volume of the main pumps 14L and 14R. In this case, the object of control of the ground contact determination unit 34 is not the regeneration release valve 50, but the regulator of the engine 11 or the main pump 14.

In addition, even in the case of remote operation or automatic excavation operation (unmanned operation), the external calculation device 30E may automatically raise the boom 4 when it determines that the peak value of the excavation reaction force F exceeds a predetermined value Fth. This is to reduce the excavation reaction force F and continue smooth excavation work.

In the above embodiment, the terrain database update unit 31 acquires terrain information of the work site through the communication device M1 when the shovel is started, and updates the terrain database. However, the present invention is not limited to this configuration. For example, the terrain database update unit 31 may acquire terrain information of the work site based on an image of the shovel's surroundings captured by an imaging device, and update the terrain database.

Figure 16 is a functional block diagram showing an example configuration of an external computing device 30E connected to an imaging device M5. The configuration of Figure 16 differs from the configuration of Figure 4 in that an imaging device M5 is connected instead of a communication device M1, but is otherwise common. Therefore, a description of the common parts will be omitted and the different parts will be described in detail.

The imaging device M5 is a device that captures images of the periphery of the shovel. In this embodiment, the imaging device M5 is a camera attached to the upper rotating body 3 of the shovel, and recognizes the distance to the ground around the shovel based on the captured images to acquire topographical information of the work site. Note that the imaging device M5 may also be a stereo camera, a distance imaging camera, a three-dimensional laser scanner, etc.

The imaging device M5 may also be attached to the outside of the shovel. In this case, the external computing device 30E may acquire the terrain information output by the imaging device M5 via the communication device M1. Specifically, the imaging device M5 may be attached to an aerial photography multicopter, a steel tower installed at the work site, or the like, and may acquire the terrain information of the work site based on an image of the work site viewed from above. When the imaging device M5 is attached to an aerial photography multicopter, it may acquire the terrain information of the work site by capturing an image of the work site viewed from above at a frequency of about once an hour or in real time. The terrain information acquired by the imaging device M5 is used to update the terrain database. When the acquisition interval of the terrain information is one hour or more, the update interval is longer than the update interval of the terrain database based on the signal from the attitude detection device M3.

Figures 17 to 19 are functional block diagrams showing another example of the configuration of the external computing device 30E connected to the imaging device M5. The configuration of Figure 17 differs from the configuration of Figure 4 in that the terrain database update unit 31 and the position coordinate update unit 32 each use the output of the imaging device M5 (particularly the imaging device M5 outside the shovel), but is common in other respects. In the embodiment of Figure 17, the terrain database update unit 31 obtains terrain information of the work site through the communication device M1, for example, once a day, and obtains terrain information of the work site through the imaging device M5 once an hour or in real time to update the terrain database. The position coordinate update unit 32 updates data related to the coordinates and orientation representing the current position of the shovel in real time using the output of the positioning device M2 and the output of the imaging device M5 in combination. The position coordinate update unit 32 may also update data related to the coordinates and orientation representing the current position of the shovel in real time based only on the output of the imaging device M5.

The configuration of FIG. 18 differs from the configuration of FIG. 4 in that the position coordinate update unit 32 uses only the output of the imaging device M5 and the positioning device M2 is omitted, but is otherwise common. Also, the configuration of FIG. 19 differs from the configuration of FIG. 4 in that the topographical database update unit 31 and the position coordinate update unit 32 each use only the output of the imaging device M5 and the communication device M1 and the positioning device M2 are omitted, but is otherwise common.

In this way, the external computing device 30E may obtain topographical information of the work site based on the output of the imaging device M5 and update the topographical database, and may update data regarding the coordinates and orientation representing the current position of the shovel in real time.

In addition, in the above embodiment, the external computing device 30E is described as a separate computing device external to the controller 30, but it may be integrated into the controller 30.

1: Lower traveling body 1A: Travel hydraulic motor (for left) 1B: Travel hydraulic motor (for right) 2: Swing mechanism 2A: Swing hydraulic motor 3: Upper rotating body 4: Boom 5: Arm 6: Bucket 7: Boom cylinder 8: Arm cylinder 9: Bucket cylinder 10: Cabin 11: Engine 11a: Alternator 11b: Starter 11c: Water temperature sensor 14L, 14R: Main pump 14a: Regulator 14b: Discharge pressure sensor 14c: Oil temperature sensor 15: Pilot pump 15a, 15b: Hydraulic sensor 16: High pressure hydraulic line 17: Control valve 25, 25a: Pilot line 26: Operation device 26A to 26C: Levers or pedals 29: Operation content detection device 30: Controller 30a: Temporary memory unit 30E: External calculation device 31: Terrain database update unit 32: Position coordinate update unit 33: Ground shape information acquisition unit 34: Ground contact determination unit 40: Image display device 40a: Conversion processing unit 40L, 40R: Center bypass pipe 41: Image display unit 42: Input unit 42a: Light switch 42b: Wiper switch 42c: Window washer switch 50: Regeneration release valve 50a: Oil passage 70: Storage battery 72: Electrical equipment 74: Engine control unit (ECU) 75: Engine speed adjustment dial 171-176: Flow control valve 175a: Regeneration oil passage E1: Control valve M1: Communication device M2: Positioning device M3: Attitude detection device M3a: Boom angle sensor M3b: Arm angle sensor M3c: Bucket angle sensor M3d: Vehicle body inclination sensor M4: Cylinder pressure detection device M5: Imaging device

Claims (4)

A lower running body;
An upper rotating body mounted on the lower traveling body;
An attachment attached to the upper rotating body;
a posture detection device for detecting a posture of the attachment;
A shovel comprising:
the control device updates shape information of the soil as a three-dimensional shape model of the work site where the shovel is located before an operation of changing the shape of the soil by the attachment is performed, which is stored in a database so that the control device can refer to, after an operation of changing the shape of the soil by the attachment is performed and before another operation of changing the shape of the soil by the attachment is performed;
The shape information of the soil and sand updated by the control device includes a shape of the excavated ground surface and a shape of the removed soil and sand,
The shape of the discharged soil is determined based on pre-stored information .
Shovel. The shape information of the discharged soil is acquired by an imaging device.
The shovel according to claim 1. The imaging device is provided on a multicopter,
The control device acquires shape information of the soil and sand from the imaging device via a communication device.
The shovel according to claim 2. A system for a shovel used in a shovel including a lower traveling body, an upper rotating body mounted on the lower traveling body, an attachment attached to the upper rotating body, and a posture detection device that detects the posture of the attachment,
A control device is provided.
the control device updates shape information of the soil as a three-dimensional shape model of the work site where the shovel is located before an operation of changing the shape of the soil by the attachment is performed, which is stored in a database so that the control device can refer to, after an operation of changing the shape of the soil by the attachment is performed and before another operation of changing the shape of the soil by the attachment is performed;
The shape information of the soil and sand updated by the control device includes a shape of the excavated ground surface and a shape of the removed soil and sand,
The shape of the discharged soil is determined based on pre-stored information .
System for excavators.

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