JP7474021B2 - Excavator - Google Patents

Description

The present invention relates to a shovel.

Conventionally, there is known a technique for correcting (suppressing) the movement of a shovel attachment in order to prevent the occurrence of movements unintended by the shovel operator (hereinafter simply referred to as "unintended movements") (see, for example, Patent Document 1).

Patent Document 1 discloses a technology that suppresses unintended movements of the shovel, such as dragging and lifting, by hydraulically controlling the pressure of the hydraulic cylinder that drives the shovel attachment so that it is equal to or lower than a predetermined maximum allowable pressure.

JP 2014-122510 A

However, in Patent Document 1, the operation of the shovel attachment is corrected without determining whether an unintended operation has actually occurred, which may worsen the operability of the operator.

In view of the above problems, the objective is to provide an excavator that can specifically determine whether or not an unintended action by the operator has occurred.

In order to achieve the above object, in one embodiment of the present invention,
A running body,
A rotating body rotatably mounted on the traveling body;
an attachment including a boom, an arm, and a bucket that is mounted on the rotating body and hydraulically driven by hydraulic oil supplied from a hydraulic pump;
A determination unit that determines whether or not a predetermined lift-up motion of the shovel occurs due to the operation of the attachment;
A first sensor that acquires information regarding a tilt state of the shovel ,
The determination unit determines whether the floating motion has occurred based on an output of the first sensor,
When the determination unit determines that the lift-up motion has occurred, the attachment is operated so as to suppress the lift-up motion by adjusting the output of a prime mover that drives the hydraulic pump or the hydraulic pump itself.
Shovel provided.
In another embodiment of the present invention,
A running body,
A rotating body rotatably mounted on the traveling body;
an attachment including a boom, an arm, and a bucket that is mounted on the rotating body and hydraulically driven by hydraulic oil supplied from a hydraulic pump;
A determination unit that determines whether or not a predetermined lift-up motion of the shovel occurs due to the operation of the attachment;
a second sensor that acquires information regarding a relative positional relationship between the shovel and an object around the shovel, the object including an object other than the ground;
The determination unit determines whether the floating motion has occurred based on an output of the second sensor,
When the determination unit determines that the lift-up motion has occurred, the attachment is operated so as to suppress the lift-up motion by adjusting the output of a prime mover that drives the hydraulic pump or the hydraulic pump itself.
Shovel provided.
In still another embodiment of the present invention,
A running body,
A rotating body rotatably mounted on the traveling body;
an attachment including a boom, an arm, and a bucket that is mounted on the rotating body and hydraulically driven by hydraulic oil supplied from a hydraulic pump;
A determination unit that determines whether or not a predetermined lift-up motion of the shovel occurs due to the operation of the attachment;
a third sensor that obtains information regarding the angular velocity of the attachment;
The determination unit determines whether the floating motion has occurred based on an output of the third sensor,
When the determination unit determines that the lift-up motion has occurred, the attachment is operated so as to suppress the lift-up motion by adjusting the output of a prime mover that drives the hydraulic pump or the hydraulic pump itself.
Shovel provided.
In still another embodiment of the present invention,
A running body,
A rotating body rotatably mounted on the traveling body;
an attachment including a boom, an arm, and a bucket that is mounted on the rotating body and hydraulically driven by hydraulic oil supplied from a hydraulic pump;
A determination unit that determines whether or not a predetermined lift-up motion of the shovel occurs due to the operation of the attachment;
a fourth sensor mounted on the bucket to acquire information regarding a forward/rearward acceleration of the bucket or information regarding an angular acceleration about a motion axis of the bucket;
a fifth sensor mounted on the boom or the arm and configured to acquire information regarding a forward/rearward acceleration of the boom or the arm, or information regarding an angular acceleration around a motion axis of the boom or the arm;
The determination unit determines whether or not the floating motion has occurred based on outputs of the fourth sensor and the fifth sensor,
When the determination unit determines that the lift-up motion has occurred, the attachment is operated so as to suppress the lift-up motion by adjusting the output of a prime mover that drives the hydraulic pump or the hydraulic pump itself.
Shovel provided.

According to the above-described embodiment, it is possible to provide a shovel that can specifically determine whether or not an unintended operation by the operator has occurred.

FIG. 1 is a diagram illustrating an example of a shovel according to an embodiment of the present invention. FIG. 1 is a block diagram showing an example of a basic configuration focusing on a drive system of a shovel according to an embodiment of the present invention. FIG. 13 is a diagram illustrating the forward dragging operation of the shovel. FIG. 13 is a diagram illustrating the rear dragging operation of the shovel. FIG. 13 is a diagram illustrating the lifting up operation of the front part of the shovel. FIG. 13 is a diagram illustrating the lifting up operation of the rear part of the shovel. FIG. 1 is a diagram illustrating a vibration operation of a shovel. FIG. 1 is a diagram illustrating a vibration operation of a shovel. 1A to 1C are diagrams for explaining a method for suppressing unintended operation of a shovel. FIG. 1 is a diagram illustrating an example of a dynamic model related to a forward dragging motion. FIG. 1 is a diagram illustrating an example of a dynamic model regarding a backward dragging motion. FIG. 1 is a diagram showing an example of a dynamic model relating to a front lift-up motion. FIG. 1 is a diagram showing an example of a dynamic model relating to rear lift-up motion. FIG. 4 is a diagram illustrating the relationship between the tipping fulcrum and the direction of the upper rotating body. FIG. 13 is a diagram illustrating the relationship between the tipping fulcrum and the state of the ground. 11A and 11B are diagrams illustrating an example of a process for setting a control condition when a floating motion occurs by a controller. FIG. 11 is a diagram showing a specific example of an operational waveform diagram relating to the vibration operation of a shovel. FIG. 11 is a diagram illustrating a method for obtaining a limit thrust. 11A and 11B are diagrams illustrating a first example of a method for determining whether or not a dragging motion has occurred. 13A and 13B are diagrams illustrating a second example of a method for determining whether or not a dragging motion has occurred. 13A and 13B are diagrams illustrating a third example of a method for determining whether or not a dragging motion has occurred. 13A and 13B are diagrams illustrating a fourth example of a method for determining whether or not a dragging motion has occurred. 11A and 11B are diagrams illustrating a first example of a method for determining whether or not a lifting motion has occurred. 13A and 13B are diagrams illustrating a second example of a method for determining whether or not a lifting motion has occurred. 13A and 13B are diagrams illustrating a third example of a method for determining whether or not a lifting motion has occurred. 13A and 13B are diagrams illustrating a fourth example of a method for determining whether or not a lifting motion has occurred. FIG. 1 is a diagram illustrating a first example of a characteristic configuration of a shovel. FIG. 13 is a diagram illustrating a second example of a characteristic configuration of a shovel. FIG. 13 is a diagram illustrating a third example of a characteristic configuration of a shovel. FIG. 13 is a diagram illustrating a fourth example of a characteristic configuration of a shovel. FIG. 13 is a diagram illustrating a fifth example of a characteristic configuration of a shovel. FIG. 13 is a diagram illustrating a sixth example of a characteristic configuration of a shovel. FIG. 13 is a diagram illustrating a seventh example of a characteristic configuration of a shovel. FIG. 13 is a diagram illustrating an eighth example of a characteristic configuration of a shovel. FIG. 13 is a diagram illustrating a ninth example of a characteristic configuration of a shovel. 10 is a flowchart illustrating an example of a process (predetermined operation suppression process) for suppressing unintended operation of a shovel by a controller. FIG. 11 is a diagram illustrating a first modified example of a shovel. FIG. 11 is a diagram illustrating a first modified example of a shovel. FIG. 11 is a diagram illustrating a second modified example of the shovel. FIG. 13 is a diagram illustrating a third modified example of the shovel.

Below, we will explain the form for implementing the invention with reference to the drawings.

[Outline of the excavator]
First, an overview of a shovel 100 will be described with reference to FIG.

Figure 1 is a side view of a shovel 100 according to this embodiment.

The excavator 100 according to this embodiment includes a lower carrier 1, an upper rotating body 3 mounted on the lower carrier 1 so as to be rotatable via a rotating mechanism 2, a boom 4, an arm 5, and a bucket 6 as attachments, and a cabin 10 in which the operator sits.

The lower traveling body 1 (an example of a traveling body) includes, for example, a pair of left and right crawlers, and each crawler is hydraulically driven by traveling hydraulic motors 1A, 1B (see Figure 2, etc.) to cause the excavator 100 to travel.

The upper rotating body 3 (an example of a rotating body) rotates relative to the lower traveling body 1 by being driven by a hydraulic rotating motor 21 (see FIG. 2) described later.

The boom 4 is pivotally attached to the front center of the upper rotating body 3 so that it can be raised and lowered, and an arm 5 is pivotally attached to the tip of the boom 4 so that it can rotate up and down, and a bucket 6 is pivotally attached to the tip of the arm 5 so that it can rotate up and down. The boom 4, arm 5, and bucket 6 are hydraulically driven by a boom cylinder 7, arm cylinder 8, and bucket cylinder 9, which serve as hydraulic actuators, respectively.

The cabin 10 is the cockpit where the operator sits and is mounted on the front left side of the upper rotating body 3.

[Basic configuration of excavator]
Next, the configuration of the shovel 100 according to this embodiment will be described in detail with reference to FIG.

Figure 2 is a block diagram showing an example of the configuration of the excavator 100 according to this embodiment, focusing on the drive system.

In the diagram, the mechanical power system is indicated by a double line, the high-pressure hydraulic lines are indicated by thick solid lines, the pilot lines are indicated by dashed lines, and the electric drive and control systems are indicated by thin solid lines.

The hydraulic drive system of the excavator 100 according to this embodiment includes an engine 11, a main pump 14, and a control valve 17. As described above, the hydraulic drive system according to this embodiment also includes traveling hydraulic motors 1A and 1B, a swing hydraulic motor 21, a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9 that hydraulically drive the lower traveling body 1, the upper rotating body 3, the boom 4, the arm 5, and the bucket 6, respectively.

The engine 11 is the driving power source for the excavator 100 and is mounted, for example, at the rear of the upper rotating body 3. The engine 11 is, for example, a diesel engine that uses diesel as fuel. The main pump 14 and pilot pump 15 are connected to the output shaft of the engine 11.

The main pump 14 is mounted, for example, at the rear of the upper rotating body 3, and supplies hydraulic oil to the control valve 17 through the high-pressure hydraulic line 16. As described above, the main pump 14 is driven by the engine 11. The main pump 14 is, for example, a variable displacement hydraulic pump, and the angle (tilt angle) of the swash plate is controlled by a regulator 14A (see Figure xx) described later, thereby adjusting the stroke length of the piston and controlling the discharge flow rate (discharge pressure).

The control valve 17 is, for example, a hydraulic control device mounted in the center of the upper rotating body 3, and controls the hydraulic drive system in response to the operation of the operating device 26 by the operator. The traveling hydraulic motors 1A (for right use) and 1B (for left use), the boom cylinder 7, the arm cylinder 8, the bucket cylinder 9, the swing hydraulic motor 21, etc. are connected to the control valve 17 via high-pressure hydraulic lines. The control valve 17 is a valve unit that is provided between the main pump 14 and each hydraulic actuator, and includes multiple hydraulic control valves, i.e., directional control valves (for example, the boom directional control valve 17A described later), that control the flow rate and direction of the hydraulic oil supplied from the main pump 14 to each hydraulic actuator.

Next, the operating system of the excavator 100 according to this embodiment includes a pilot pump 15, an operating device 26, a pressure sensor 29, etc.

The pilot pump 15 is mounted, for example, at the rear of the upper rotating body 3 and supplies pilot pressure to the mechanical brake 23 and the operating device 26 via a pilot line 25. The pilot pump 15 is, for example, a fixed displacement hydraulic pump, and is driven by the engine 11 as described above.

The operating device 26 includes lever devices 26A, 26B and a pedal device 26C. The operating device 26 is provided near the cockpit of the cabin 10, and is an operating means by which the operator operates each operating element (lower traveling body 1, upper rotating body 3, boom 4, arm 5, bucket 6, etc.). In other words, the operating device 26 is an operating means for operating each hydraulic actuator (travel hydraulic motor 1A, 1B, boom cylinder 7, arm cylinder 8, bucket cylinder 9, swing hydraulic motor 21) that drives each operating element. The operating device 26 (lever devices 26A, 26B, and pedal device 26C) is connected to the control valve 17 via a hydraulic line 27. As a result, a pilot signal (pilot pressure) corresponding to the operating state of the lower traveling body 1, upper rotating body 3, boom 4, arm 5, bucket 6, etc. in the operating device 26 is input to the control valve 17. Therefore, the control valve 17 can drive each hydraulic actuator according to the operating state in the operating device 26. The operating device 26 is also connected to a pressure sensor 29 via a hydraulic line 28.

The lever devices 26A and 26B are located on the left and right sides, respectively, as viewed from the operator seated in the cockpit inside the cabin 10, and each operating lever is configured to be tiltable in the forward/backward and left/right directions with respect to the neutral state (a state in which there is no operating input by the operator). As a result, any of the upper rotating body 3 (swing hydraulic motor 21), boom 4 (boom cylinder 7), arm 5 (arm cylinder 8), and bucket 6 (bucket cylinder 9) can be arbitrarily set as the operation target for each of the forward/backward and left/right tilts of the operating lever of the lever device 26A and the forward/backward and left/right tilts of the operating lever of the lever device 26B.

In addition, the pedal device 26C operates the lower traveling body 1 (traveling hydraulic motors 1A, 1B) and is located on the floor in front of the operator seated in the cockpit in the cabin 10, and the operating pedal is configured to be able to be depressed by the operator.

As described above, the pressure sensor 29 is connected to the operating device 26 via the hydraulic line 28, and detects the secondary pilot pressure of the operating device 26, i.e., the pilot pressure corresponding to the operating state of each operating element in the operating device 26. The pressure sensor 29 is connected to the controller 30, and a pressure signal (pressure detection value) corresponding to the operating state of the lower traveling body 1, upper rotating body 3, boom 4, arm 5, bucket 6, etc. in the operating device 26 is input to the controller 30. This allows the controller 30 to grasp the operating state of the lower traveling body 1, upper rotating body 3, and attachment of the excavator.

Next, the control system of the excavator 100 in this example includes a controller 30, various sensors 32, etc.

The controller 30 is the main control device that performs drive control in the excavator 100. The controller 30 may be realized by any hardware, software, or a combination thereof. The controller 30 may be configured, for example, around a microcomputer including a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), auxiliary storage device, I/O (Input-Output interface), etc., and various drive controls are realized by executing various programs stored in the ROM, auxiliary storage device, etc. on the CPU.

In this embodiment, the controller 30 determines whether or not a specific operation of the shovel 100 that is not intended by the operator (hereinafter simply referred to as an unintended operation) has occurred, that is, whether or not an operation of the shovel 100 that is undesirable to the operator has occurred. Then, when it is determined that such an unintended operation has occurred, the controller 30 corrects the operation of the attachment of the shovel 100 so as to suppress the operation. In this way, the unintended operation of the shovel 100 is suppressed.

The unintended motion includes, for example, a forward dragging motion in which the shovel 100 is dragged forward by an excavation reaction force or the like even though the operator is not operating the lower traveling body 1, and a backward dragging motion in which the shovel 100 is dragged backward by a reaction force from the ground during leveling work or the like. Hereinafter, the forward dragging motion and the backward dragging motion may not be distinguished from each other, and may simply be referred to as a dragging motion. The unintended motion also includes, for example, a lifting motion in which the front or rear of the shovel 100 is lifted up by an excavation reaction force or the like. Hereinafter, the lifting motion may be distinguished by referring to a front lifting motion when the front of the shovel 100 is lifted up and a rear lifting motion when the rear of the shovel 100 is lifted up. The unintended motion also includes, for example, a vibration motion of the vehicle body (lower traveling body 1, rotating mechanism 2, and upper rotating body 3) induced by a change in the moment of inertia during the aerial operation of the attachment of the shovel 100 (operation with the bucket 6 not on the ground). More details on unintended behavior will be provided below.

The controller 30 includes, for example, an operation determination unit 301 and an operation correction unit 302 as functional units realized by executing one or more programs stored in a ROM or auxiliary storage device on a CPU.

The operation determination unit 301 determines whether or not an unintended operation has occurred based on sensor information related to various states of the shovel 100 input from the pressure sensor 29 and various sensors 32. Details of the determination method will be described later.

When the operation determination unit 301 determines that an unintended operation has occurred, the operation correction unit 302 corrects the operation of the attachment to suppress the unintended operation. Details of the correction method will be described later.

The various sensors 32 are known detection means for detecting various conditions of the shovel 100 and various conditions around the shovel 100. The various sensors 32 may include an angle sensor for detecting the angle of the boom 4 at the connection point between the upper rotating body 3 and the boom 4 relative to a reference plane (boom angle), the relative angle between the boom 4 and the arm 5 (arm angle), and the relative angle between the arm 5 and the bucket 6 (bucket angle). The various sensors 32 may also include a pressure sensor for detecting the hydraulic state in the hydraulic actuator, specifically, the pressure in the rod side oil chamber and the bottom side oil chamber of the hydraulic cylinder. The various sensors 32 may also include sensors for detecting the respective operating states of the lower traveling body 1, the upper rotating body 3, and the attachment, such as an acceleration sensor, an angular acceleration sensor, and a three-axis inertial sensor (IMU: Inertial Measurement Unit) capable of outputting three-axis acceleration and three-axis angular acceleration. The various sensors 32 may also include a distance sensor or an image sensor for detecting the relative positional relationship between the shovel 100 and the surrounding terrain, obstacles, etc.

[Unintended shovel movement by the operator]
Next, with reference to Figs. 3 to 8, a detailed description will be given of an operation of the shovel 100 that is not intended by the operator.

<Forward dragging motion>
First, Fig. 3 is a diagram for explaining the forward dragging motion of the shovel 100. Specifically, Fig. 3 is a diagram showing a working situation of the shovel 100 in which the forward dragging motion occurs.

As shown in FIG. 3, the shovel 100 is excavating the ground 30a, and a force F2 acts from the bucket 6 to the ground 30a in a diagonally downward direction toward the vehicle body (lower running body 1, slewing mechanism 2, upper rotating body 3) of the shovel 100, mainly due to the closing operation of the arm 5 and bucket 6. At this time, a reaction force F3 corresponding to the horizontal component F2aH of the excavation reaction force F2a, that is, a reaction force F3 acting on the bucket 6, acts on the vehicle body (lower running body 1, slewing mechanism 2, upper rotating body 3) of the shovel 100 via the attachment. When the reaction force F3 exceeds the maximum static friction force F0 between the shovel 100 and the ground 30a, the vehicle body is dragged forward.

<Rear dragging motion>
Next, Fig. 4 is a diagram for explaining the backward dragging operation of the shovel 100. Specifically, Fig. 4(a) and (b) are diagrams showing a working situation of the shovel 100 in which the backward dragging operation occurs.

As shown in FIG. 4(a), the shovel 100 is leveling the ground 40a, and a force F2 is generated by the bucket 6 pushing the soil 40b forward, mainly due to the opening movement of the arm 5. At this time, a reaction force F3 corresponding to the reaction force of the force F2 acting on the bucket 6 acts on the body of the shovel 100 via the attachment. When the reaction force F3 exceeds the maximum static friction force F0 between the shovel 100 and the ground 40a, the body is dragged forward.

As shown in FIG. 4(b), the excavator 100 is used for river construction work, etc., mainly by opening the arm 5 to press the bucket 6 against the wall surface 40c of the inclined bank portion to compact the soil and level the ground. Even in such work, a reaction force F3 corresponding to the reaction force of the force F2 acting on the bucket 6 to press against the wall surface 40c acts to drag the vehicle body backward from the attachment.

<Front lift-up movement>
Next, Fig. 5 is a diagram for explaining the front lifting operation of the shovel 100. Specifically, Fig. 5 is a diagram showing a working situation of the shovel 100 in which the front lifting operation occurs.

As shown in FIG. 5, the shovel 100 is excavating the ground 50a, and a force F2 acts from the bucket 6 on the ground 50a in a diagonally downward direction toward the vehicle body of the shovel 100, mainly due to the closing operation of the arm 5 and the bucket 6. At this time, a reaction force F3 (force moment; hereinafter, simply referred to as "moment" in this embodiment) that tries to tilt the vehicle body backward, which corresponds to the vertical component F2aV of the excavation reaction force F2a, acts on the vehicle body of the shovel 100 via the attachment. Specifically, the reaction force F3 acts on the vehicle body as a force F1 that tries to pull up the boom cylinder 7. When the moment that tries to tilt the vehicle body backward due to this force F1 exceeds the force (moment) that tries to hold the vehicle body down to the ground based on gravity, the front part of the vehicle body is lifted up.

<Rear lift-up movement>
Next, Fig. 6 is a diagram for explaining the rear lifting operation of the shovel 100. Specifically, Fig. 6 is a diagram showing a working situation of the shovel 100 in which the rear lifting operation occurs.

As shown in Fig. 6, the excavator 100 is performing excavation work on the ground 60a. A force F2 (moment) is generated so that the bucket 6 digs into the slope 60b, and a force F3 (moment) is generated so that the boom 4 presses the bucket 6 against the slope 60b, in other words, so that the boom 4 tilts the vehicle body forward. At this time, a force F1 is generated to pull up the rod of the boom cylinder 7, and the force F1 acts to tilt the vehicle body of the excavator 100. If the moment that tries to tilt the vehicle body forward due to the force F1 exceeds the force (moment) that tries to press the vehicle body down to the ground due to gravity, the rear of the vehicle body will be lifted up.

In particular, if the bucket 6 is in contact with the ground or an object and is caught or embedded, the boom 4 will not move even if a force is applied to it, and the rod of the boom cylinder 7 will not be displaced. When the pressure in the oil chamber on the contracted side of the boom cylinder 7 (in this example, the rod side) increases, the force F1 lifting the boom cylinder 7 itself, i.e., the force tending to tilt the vehicle body forward, increases.

This situation can occur, for example, during ground leveling work on the forward slope shown in FIG. 6, as well as during deep digging work in which the bucket 6 is positioned below the vehicle body (lower running body 1). It can also occur when the arm 5 or bucket 6 is operated, not just when the boom 4 itself is operated.

<Vibration action>
Next, Fig. 7 and Fig. 8 are diagrams for explaining an example of the vibration operation of the shovel 100. Specifically, Fig. 7 is a diagram for explaining a situation in which the vibration operation occurs during the aerial operation of the shovel 100. Also, Fig. 8 is a diagram showing the time waveforms of the angle (pitch angle) in the pitching axis direction and the angular velocity (pitch angular velocity) accompanying the discharge operation of the shovel 100 in the situation shown in Fig. 7. In this example, a discharge operation for discharging a load DP in the bucket 6 will be described as an example of the aerial operation.

As shown in FIG. 7(a), the excavator 100 is in a state in which the bucket 6 and arm 5 are closed and the boom 4 is raised, and the bucket 6 contains a load DP such as soil and sand.

As shown in FIG. 7(b), when the excavator 100 performs a discharge operation from the state shown in FIG. 7(a), the bucket 6 and arm 5 are opened wide, the boom 4 is lowered, and the load DP is discharged outside the bucket 6. At this time, the change in the moment of inertia of the attachment acts to vibrate the body of the excavator 100 in the pitching direction shown by the arrow A in the figure.

At this time, as shown in FIG. 8, due to the aerial action, specifically the discharge action, an overturning moment that tends to overturn the shovel 100 is generated, and vibrations are generated around the pitch axis.

[Method of suppressing unintended excavator movements]
Next, a method for suppressing unintended operation of the shovel 100 described above will be described with reference to FIGS.

<Outline of method for suppressing unintended excavator movements>
First, Fig. 9 is a diagram for roughly explaining a method for suppressing unintended operation of the shovel 100. Specifically, Fig. 9(a) to (d) are plan views seen from directly above the shovel 100, showing states of the shovel 100 in which the combinations of the orientation of the lower traveling body 1 and the rotation position of the upper rotating body 3 are different from each other.

Regardless of the posture or work content, the attachments, i.e., the boom 4, arm 5, and bucket 6, always operate on the straight line L1 corresponding to the direction in which the attachment extends when viewed from a plan view, that is, on the same vertical plane. Therefore, it can be said that the reaction force F3 acting from the attachment during the operation of the attachment acts on the body of the shovel 100 on the vertical plane. This does not depend on the positional relationship (rotation angle) between the lower traveling body 1 and the upper rotating body 3. As shown in Figures 3 to 7, the direction of the reaction force F3 in a plan view can differ depending on the work content. In other words, when unintended movements such as dragging, lifting, and vibrating movements occur in the shovel 100, this indicates that the movements are caused by the movement of the attachment, and therefore, by controlling the attachment, the unintended movements described above can be suppressed.

<Method of suppressing dragging motion>
FIG. 10 is a diagram for explaining an example of a method for suppressing the forward dragging motion of the shovel 100. Specifically, FIG. 10 is a diagram showing an example of a dynamic model of the shovel 100 related to the forward dragging motion, and similar to FIG. 3, is a diagram showing forces acting on the shovel 100 when the shovel 100 is performing excavation work on the ground 100a. FIG. 11 is a diagram for explaining an example of a method for suppressing the backward dragging motion of the shovel 100. Specifically, FIG. 11 is a diagram showing an example of a dynamic model related to the backward dragging motion, and more specifically, similar to FIG. 4(a), is a diagram showing forces acting on the shovel 100 when the shovel 100 is performing leveling work on the earth 110b on the ground 110a.

As shown in Figures 10 and 11, the force F3 that the boom cylinder 7 exerts on the vehicle body (upper rotating body 3) in the horizontal direction (either forward or backward) is expressed by the following formula (1) based on the angle η1 between the boom cylinder 7 and the vertical axis 100c, 110c, and the force F1 that the boom cylinder 7 exerts on the upper rotating body 3, i.e., the force F1 acting on the vehicle body from the attachment.

F3=F1 sin η1 (1)
On the other hand, the maximum static friction force F0 is expressed by the following formula (2) based on the static friction coefficient μ between the lower traveling body 1 and the ground 100a, 110a, the vehicle body weight M, and the gravitational acceleration g.

F0 = μMg ... (2)
The condition for preventing the shovel 100 from being dragged by the reaction force F3 is expressed by the following equation (3).

F3<F0 ... (3)
Therefore, by substituting equations (1) and (2) into equation (3), the following equation (4) can be obtained.

F1 sin η1 < μMg ... (4)
In other words, the operation correction unit 302 can suppress the backward dragging operation of the excavator 100 by correcting the operation of the boom cylinder 7 so that the relational expression (4) holds true.

For example, the force F1 is expressed by a function f with arguments being the pressure (rod pressure) PR in the rod-side oil chamber of the boom cylinder 7 and the pressure (bottom pressure) PB in the bottom-side oil chamber, as shown in the following equation (5).

F1 = f (PR, PB) ... (5)
The motion correction unit 302 (force estimation unit) calculates (estimates) the force F1 that the boom cylinder 7 exerts on the upper rotating body 3 based on the rod pressure PR and the bottom pressure PB in accordance with the formula (5). At this time, the motion correction unit 302 may acquire the rod pressure PR and the bottom pressure PB based on an output signal of a pressure sensor that detects the rod pressure and the bottom pressure of the boom cylinder 7, which may be included in the various sensors 32.

As an example, the force F1 can be expressed by the following equation (6) using the pressure-receiving area AR on the rod side and the pressure-receiving area AB on the bottom side.

F1 = |AR·PR-AB·PB| ... (6)
Therefore, the motion correction unit 302 (force estimation unit) may calculate (estimate) the force F1 based on the formula (6).

The operation correction unit 302 (angle calculation unit) also calculates the angle η1 between the vertical axes 100c, 110c and the boom cylinder 7. The angle η1 can be calculated geometrically from the telescopic length of the boom cylinder 7, the dimensional specifications of the shovel 100, the inclination of the body of the shovel 100, and the like. For example, the operation correction unit 302 may calculate the angle η1 using the output of a sensor that detects the boom angle, which may be included in the various sensors 32.

In addition, the angle η1 may be obtained by using the output of a sensor that directly measures the angle η1, which may be included in the various sensors 32.

The operation correction unit 302 (pressure adjustment unit) controls the pressure of the boom cylinder 7, specifically, the pressure of either the rod side oil chamber or the bottom side oil chamber that is overpressurized, based on the force F1 and angle η1 obtained by calculation or the like, so that equation (4) holds. In other words, the operation correction unit 302 (pressure adjustment unit) adjusts the rod pressure PR or bottom pressure PB of the boom cylinder 7 so that equation (4) holds. More specifically, by employing various configurations (see Figures 26 to 34) described later, the operation correction unit 302 can adjust the pressure of the boom cylinder 7 and suppress the dragging operation of the excavator 100 by appropriately outputting a control command to the controlled object.

The static friction coefficient μ in formula (4) may be a typical predetermined value, or may be input by the operator depending on the ground conditions at the work site. The shovel 100 may further include a means for estimating the static friction coefficient μ. Specifically, the estimation means can calculate the static friction coefficient μ from the force F1 when the vehicle body slips (drags) during work with the attachment while the shovel 100 is stationary relative to the ground. In this case, for example, the occurrence of dragging can be determined by appropriately mounting an acceleration sensor or the like on the upper rotating body 3 of the shovel 100, as described below.

<Method of suppressing floating motion>
Next, Fig. 12 is a diagram for roughly explaining an example of a method for suppressing the front lift-up motion of the shovel 100. Specifically, Fig. 12 is a diagram showing a dynamic model of the shovel 100 related to the front lift-up motion, and similarly to Fig. 5, is a diagram showing forces acting on the shovel 100 when the shovel 100 is performing an excavation operation of the ground surface 120a.

As shown in FIG. 12, the tipping fulcrum P1 during the front lift-up operation of the excavator 100 can be considered to be the end of the effective ground contact area 120b of the lower traveling body 1 in the direction in which the attachment extends (the direction of the upper rotating body 3). Therefore, the moment τ1 that tries to lift the front of the vehicle body around the tipping fulcrum P1 is expressed by the following equation (7) based on the distance D3 between the extension line l2 of the boom cylinder 7 and the tipping fulcrum P1 and the force F1.

τ1=D3·F1 (7)
On the other hand, the moment τ2 of gravity trying to press the vehicle body down on the ground around the tipping fulcrum P1 is expressed by the following equation (8) based on the distance D1 between the center of gravity P3 of the excavator 100 and the tipping fulcrum P1 at the rear of the lower running body 1, the vehicle body weight M, and the gravitational acceleration g.

τ2 = D1 · Mg ... (8)
The condition (stability condition) under which the front part of the vehicle body is stable without lifting up is expressed by the following equation (9).

τ1<τ2 ... (9)
Therefore, by substituting equations (7) and (8) into equation (9), the following inequality (10) is obtained as the stability condition.

D3·F1<D1·Mg ... (10)
In other words, the operation correction unit 302 can prevent the front of the shovel 100 from lifting up by correcting the operation of the attachment so that inequality (10) holds as a control condition.

More specifically, FIG. 13 shows a mechanical model of the shovel related to rear lift-up, and like FIG. 6, shows the forces acting on the shovel 100 when excavating the ground 130a.

The tipping fulcrum P1 during the rear lift-up motion of the excavator 100 can be considered to be the very end of the effective ground contact area 130b of the lower running body 1 in the direction in which the attachment extends (the direction of the upper rotating body 3). Therefore, the moment τ1 that tries to tilt the vehicle body forward around the tipping fulcrum P1, i.e., the moment τ1 that tries to lift the rear of the vehicle body, is expressed by the following formula (11) based on the extension line l2 of the boom cylinder 7 and the distance D4 between the tipping fulcrum P1 and the force F1 that the boom cylinder 7 exerts on the upper rotating body 3.

τ1=D4·F1 (11)
On the other hand, the moment τ2 of gravity trying to press the vehicle body down on the ground around the tipping fulcrum P1 is expressed by the following equation (12) based on the distance D2 between the center of gravity P3 of the excavator and the tipping fulcrum P1 in front of the lower running body 1, the vehicle weight M, and the gravitational acceleration g.

τ2=D2·Mg... (12)
The condition (stable condition) under which the rear of the vehicle body does not lift up and is stable is expressed by the following equation (13), similar to equation (9).

τ1<τ2 ... (13)
Therefore, by substituting equations (11) and (12) into equation (13), the following inequality (14) is obtained as the stability condition.

D4·F1<D2·Mg ... (14)
In other words, if the operation correction unit 302 corrects the operation of the attachment so that inequality (14) holds as a control condition, the rear of the shovel 100 can be prevented from lifting up.

If distances D1 and D2 are set as distance DA, distances D2 and D4 are set as distance DB, and tipping fulcrum P1 is swapped between the front and rear, the control conditions (stability conditions) for the front lift-up and rear lift-up can be summarized as the following equation (15).

DB·F1<DA·Mg ... (15)
For example, the force F1 is expressed by a function f with the rod pressure PR and the bottom pressure PB of the boom cylinder 7 as arguments, as shown in the following equation (16), similar to the above equation (5).

F1=f(PR, PB) (16)
The motion correction unit 302 (force estimation unit) calculates (estimates) the force F1 that the boom cylinder 7 exerts on the upper rotating body 3 based on the rod pressure PR and the bottom pressure PB. At this time, as described above, the motion correction unit 302 may acquire the rod pressure PR and the bottom pressure PB based on the output signal of a pressure sensor that detects the rod pressure and the bottom pressure of the boom cylinder 7, which may be included in the various sensors 32.

As an example, the force F1 can be expressed by the following equation (17) using the pressure-receiving area AR on the rod side and the pressure-receiving area AB on the bottom side, similar to the above equation (6).

F1 = |AR·PR-AB·PB| ... (17)
The motion correction unit 302 (force estimation unit) may calculate (estimate) the force F1 based on the equation (17).

The motion correction unit 302 (distance acquisition unit) acquires the distances D1 and D3 or the distances D2 and D4. The motion correction unit (distance acquisition unit) may also acquire the ratio between them (D1/D3 or D2/D4).

The position of the center of gravity P3 of the vehicle excluding the attachments is constant regardless of the rotation angle θ of the upper rotating body 3, but the position of the tipping fulcrum P1 changes depending on the rotation angle θ. Therefore, in reality, the distances D1 and D2 can change depending on the rotation angle θ of the upper rotating body 3, but for simplicity, the distances D1 and D2 can be constants.

Distances D3 and D4 can be calculated geometrically based on the position of tipping fulcrum P1 and the angle of boom cylinder 7 (e.g., angle η1 between boom cylinder 7 and vertical axis 130c).

The angle η1 can be calculated geometrically from the extension/retraction length of the boom cylinder 7, the dimensional specifications of the shovel 100, the inclination of the body of the shovel 100, and the like. For example, the operation correction unit 302 may calculate the angle η1 using the output of a sensor that detects the boom angle, which may be included in the various sensors 32.

In addition, the angle η1 may be obtained by using the output of a sensor that directly measures the angle η1, which may be included in the various sensors 32.

The operation correction unit 302 (pressure adjustment unit) controls the pressure of the boom cylinder 7, specifically, the pressure of either the rod side oil chamber or the bottom side oil chamber, which is overpressurized, based on the force F1 acquired by calculation or the like and the distances D1, D3 or the distances D2, D4, so that inequality (15), i.e., inequality (10) or (14), holds. In other words, the operation correction unit 302 (pressure adjustment unit) adjusts the rod pressure PR or the bottom pressure PB of the boom cylinder 7 so that inequality (15) holds. More specifically, by employing various configurations (see Figures 26 to 34) described later, the operation correction unit 302 can adjust the pressure of the boom cylinder 7 and suppress the lifting operation of the excavator 100 by appropriately outputting a control command to the controlled object.

<Method of suppressing floating motion considering changes in the tipping fulcrum>
In the above description, the tipping fulcrum P1 is treated as fixed, but as described above, the position of the tipping fulcrum P1 can change, so it is also possible to take into account the change in the tipping fulcrum P1. Hereinafter, with reference to Figures 14 to 16, a method of suppressing the floating motion that takes into account the change in the tipping fulcrum will be described.

As described above, the control condition (stable condition) under which front lift and rear lift do not occur is inequality (15), i.e., inequalities (10) and (14). Inequalities (10) and (14) have distances D1, D2, D3, and D4 as parameters, and these distances depend on the position of the tipping fulcrum P1.

Figure 14 is a diagram that explains the relationship between the tipping fulcrum P1 and the direction of the upper rotating body 3 (rotation angle θ) when the rotation angle θ = 0° is when the direction in which the attachment extends (attachment orientation) and the direction of the lower traveling body 1 (traveling direction) are the same, and when right turning is the positive direction. Specifically, Figures 14(a) to (c) are diagrams that show the tipping fulcrum P1 when the rotation angle θ is 0°, 30°, and 90°, respectively. Also, Figure 15 is a diagram that explains the relationship between the tipping fulcrum P1 and the state of the ground 150a (work field).

In addition, in Figures 14(a) to (c), the rear lift is assumed, and the tipping fulcrum P1 is located at the front of the vehicle body. Also, line l1 in Figures 14(a) to (c) represents a line that is perpendicular to the direction in which the attachment extends (the direction of the upper rotating body 3) and passes through the most extreme end of the effective ground contact area 140a in the direction in which the attachment extends, and tipping fulcrum P1 is located on line l1. Also, in Figure 15, the solid line represents hard ground 150a, and the dashed line represents soft ground 150b.

As shown in Figures 14 and 15, the tipping fulcrum P1 moves depending on the orientation of the upper rotating body 3 and the condition of the ground.

For example, as shown in Figures 14(a) to (c), when the tipping fulcrum P1 moves, the distance D2 also changes. Similarly, the distance D4 also changes with the movement of the tipping fulcrum P1.

For example, as shown in FIG. 15, on hard ground 150a, tipping fulcrum P1 is located at the solid triangle. On the other hand, on soft ground 150b, tipping fulcrum P1a may be located at the dashed triangle. Furthermore, if there is a hard obstacle near tipping fulcrum P1 on the work field, or if the lower running body 1 runs over an obstacle, tipping fulcrum P1 may move further.

The movement of the tipping fulcrum P1 affects the distances D1 to D4, and thus the mechanical stability conditions under which the vehicle body does not tip over. Therefore, the operation correction unit 302 may set control conditions (stable conditions) according to the position of the tipping fulcrum P1, and correct the operation of the attachment based on the set control conditions so that the lift-up operation of the excavator 100 is suppressed.

For example, as described below, the operation determination unit 301 monitors the state of the vehicle body and the attachment based on input from various sensors 32, and identifies the moment when the front or rear of the lower running structure 1 is lifted up. Then, the operation correction unit 302 dynamically changes the control conditions (stability conditions) when correcting the operation of the attachment, i.e., inequalities (10) and (14) as examples, based on the state of the excavator 100 at the moment when the vehicle body (lower running structure 1) is lifted up.

The moment of lifting can be approximated as a state in which moment τ1, which is based on force F1 that the attachment exerts on the vehicle body, and moment τ2, which resists this force and is based on gravity, are balanced. Therefore, by identifying the moment of lifting and monitoring the state of the shovel 100, it is possible to adaptively set control conditions for suppressing lifting, and it is possible to appropriately suppress lifting under various usage conditions.

The operation determination unit 301 identifies (detects) the moment when the excavator 100 (lower running body 1) lifts up based on input from the various sensors 32. For example, the sensor 610 may detect rotation around the pitch axis based on output from an attitude sensor (tilt sensor), a gyro sensor (angular acceleration sensor), an acceleration sensor, an IMU, etc., which may be included in the various sensors 32 and are mounted on the upper rotating body 3, to identify the moment when the excavator 100 lifts up.

For example, when the motion determination unit 301 detects forward angular acceleration or angular velocity based on the output of the various sensors 32, the motion correction unit 302 (condition setting unit) sets control conditions for suppressing rear lift-up. On the other hand, when the motion determination unit 301 detects forward angular acceleration or angular velocity based on the output of the various sensors 32, the motion correction unit 302 (control condition setting unit) sets control conditions for suppressing front lift-up.

The operation correction unit 302 (condition setting unit) acquires the force F1 (force F1_INIT) that the boom cylinder 7 exerts on the upper rotating body 3 at the moment of lift-off identified (detected) by the operation determination unit 301. The operation correction unit 302 (condition setting unit) then acquires parameters related to the position of the tipping fulcrum P1 based on the acquired force F1_INIT, and sets control conditions based on the parameters.

For example, the above inequality (10) is used as the control condition for suppressing the front lift.

When the motion determination unit 301 detects rearward pitching that corresponds to the front lifting up, the moment τ1 and moment τ2 are balanced at the moment of lifting up, and the following equation (18) holds.

D3 · F1_INIT = D1 · Mg ... (18)
Since the force F1_INIT, the vehicle body weight M, and the gravitational acceleration g are known, formula (18) is considered to be a relational expression that should be satisfied by the distances D1 and D3 in the current usage status of the shovel 100.

If formula (18) is known, distances D1 and D3 are geometrically and uniquely determined. Therefore, the motion correction unit 302 (condition setting unit) obtains the current distances D1 and D3 (distances D1_DET and D3_DET) based on formula (18) and the posture of the attachment.

Note that obtaining distance D1 is equivalent to obtaining position information of tipping fulcrum P1. Because the position of vehicle center of gravity P3 is constant, once distance D1 is found, the position of tipping fulcrum P1 is uniquely determined.

Then, the operation correction unit 302 (condition setting unit) sets the subsequent control conditions to the following inequality (19).

D3_DET·F1<D1_DET·Mg (19)
The operation correction unit 302 corrects the operation of the attachment based on the control condition expressed by equation (19).

Once the distance D1 is acquired, the same value can be used as long as the direction of the upper rotating body 3 does not change and the ground conditions do not change. On the other hand, the distance D3 changes depending on whether the boom 4 is raised or lowered. Therefore, when the angle of the boom 4 changes, the operation correction unit 302 (condition setting unit) changes the distance D3 accordingly and reflects this in the control conditions.

A similar control is performed for rear lift-up. For example, the above-mentioned inequality (14) is used as the control condition for suppressing rear lift-up.

When the motion determination unit 301 detects pitching of the front half that corresponds to rear lift-up, the moment τ1 and moment τ2 are balanced at the moment of lift-up, and the following equation (20) holds.

D4 · F1_INIT = D2 · Mg ... (20)
Since the force F1_INIT, the vehicle body weight M, and the gravitational acceleration g are known, equation (20) is considered to be a relationship that should be satisfied by the distances D2 and D4 in the current usage status of the shovel 100.

The motion correction unit 302 (condition setting unit) obtains the current distances D2 and D4 (distances D2_DET and D4_DET) based on equation (18) and the posture of the attachment.

Note that obtaining distance D2 is equivalent to obtaining position information of tipping fulcrum P1.

Then, the operation correction unit 302 (condition setting unit) sets the subsequent control conditions to the following inequality (21) based on the above-mentioned inequality (14).

D2_DET·F1<D4_DET·Mg (21)
The operation correction unit 302 corrects the operation of the attachment based on the control condition expressed by equation (21).

Once the distance D2 is acquired, the same value can be used as long as the direction of the upper rotating body 3 does not change and the ground conditions do not change. On the other hand, the distance D4 changes depending on whether the boom 4 is raised or lowered. Therefore, when the angle of the boom 4 changes, the operation correction unit 302 (condition setting unit) changes the distance D4 accordingly and reflects it in the control conditions.

Figure 16 is a flowchart that shows an example of a process (condition setting process) for setting control conditions by the controller 30 (operation determination unit 301, operation correction unit 302). The process according to this flowchart may be executed periodically, i.e., at predetermined intervals, for example, from when the shovel is started to when it is stopped.

In step S1600, the operation determination unit 301 determines whether or not excavation work is being performed using an attachment. The conditions for determining whether or not excavation work is being performed using an attachment may be, for example, that the vehicle is not traveling, is not swinging, and a pressure equal to or greater than a predetermined pressure is being generated in at least one of the boom cylinder 7, arm cylinder 8, and bucket cylinder 9. If excavation work is being performed, the operation determination unit 301 proceeds to step S1602, and if excavation work is not being performed, the operation determination unit 301 ends the current process.

In addition, excavation work also includes leveling and backfilling work.

In step S1602, the operation determination unit 301 monitors whether or not the shovel 100 is floating up. If the operation determination unit 301 identifies (detects) floating up, the process proceeds to step S1804, and if the operation determination unit 301 does not identify (detect) floating up, the process ends.

In addition, in step S1602 before the control conditions are set, the body of the excavator 100 momentarily lifts up. If an appropriate combination of a processor and software program is used in the controller 30, the control conditions can be set in an extremely short time after the lift is identified (detected) and before the first lift in step S1602 develops into a large vehicle body tilt. Then, the operation correction unit 302 can start correcting the operation of the attachment before the lift develops into a large vehicle body tilt.

In step S1604, the operation correction unit 302 acquires information about the state of the shovel 100 at the moment of lift-off. The information about the state of the shovel 100 is, for example, the force F1_INIT described above.

In step S1606, the operation correction unit 302 calculates parameters related to the tipping support point P1, such as distances D1 to D4, based on the information about the state of the shovel acquired in step S1604, and sets the control conditions. Thereafter, the operation correction unit 302 corrects the operation of the attachment based on the set control conditions until the current excavation work is completed, unless the control conditions are modified by the processing of step S1610 described below.

In step S1608, the operation determination unit 301 determines whether the attitude of the boom 4 has changed. If the attitude of the boom 4 has changed, the operation determination unit 301 proceeds to step S1610, and if the attitude has not changed, the operation determination unit 301 proceeds to step S1612.

In step S1610, the operation correction unit 302 modifies the control conditions because the distances D3 and D4 have changed in response to the change in the attitude of the boom 4.

In step S1612, the operation determination unit 301 determines whether or not the excavation work has been completed. If the excavation work has not been completed, the operation determination unit 301 returns to step S1608, and if the excavation work has been completed, the operation determination unit 301 ends the current process.

In this example, the control conditions are defined by calculating the distances D1 to D4, but this is not the only option. For example, by transforming inequalities (10) and (14), the following inequalities (22) and (23) are obtained.

F1<D1/D3·Mg (22)
F1<D2/D4·Mg (23)
At the moment of lift-off, the following equations (24) and (25) hold.

F1_INIT=D1/D3×Mg (24)
F1_INIT=D2/D4×Mg (25)
Therefore, the operation correction unit 302 (condition setting unit) may obtain the force F1_INIT at the moment of lift-up, and set the control condition thereafter to equation (26).

F1<F1_INIT (26)
Here, the distances D1 to D4 or the position of the tipping fulcrum P1 are not explicitly calculated, but the control condition expressed by equation (26) naturally reflects correct position information of the tipping fulcrum P1.

In addition, in this example, the control conditions for suppressing floating are explicitly included in the force F1, but are not limited thereto. For example, the control conditions may be defined using another force or moment that is correlated with the force F1 instead of the force F1.

<Method of suppressing vibration>
17(a) to (c) are diagrams showing specific examples of operation waveforms related to the vibration operation of the shovel 100. Specifically, Fig. 19(a) to (c) are diagrams showing one example, another example, and yet another example of operation waveform diagrams when aerial operations are repeatedly performed in the shovel 100. Fig. 17(a) to (c) each show a different trial, and from the top, pitching angular velocity (i.e., vibration of the vehicle body), boom angular acceleration, arm angular acceleration, boom angle, and arm angle are shown.

In the figure, the X marks the points that correspond to the negative peaks of the pitch angular velocity.

As shown in Figures 17(a) to (c), it can be seen that vibratory motion is induced when the change in the boom angle stops. In other words, it can be said that the boom angular acceleration has the greatest effect on the occurrence of vibratory motion, and conversely, this shows that controlling the boom angular velocity is effective in suppressing vibratory motion. This can be intuitively understood from the fact that only the mass of the bucket 6 affects the moment of inertia (inertia) related to the bucket angle, and the mass of the bucket 6 and arm 5 affects the moment of inertia related to the arm angle, whereas the total mass of not only the boom 4 but also the arm 5 and bucket 6 affects the moment of inertia related to the boom angle.

Therefore, it is preferable that the operation correction unit 302 corrects the operation of the boom cylinder 7 as the control target. In other words, the operation correction unit 302 operates so that the thrust of the boom cylinder 7 does not exceed an upper limit value (limited thrust FMAX) based on the state of the attachment.

The thrust force F of the boom cylinder 7 is expressed by the following equation (27) based on the pressure-receiving area AR of the rod-side oil chamber, the rod pressure PR of the rod-side oil chamber, the pressure-receiving area AB of the bottom-side oil chamber, and the bottom pressure PB of the bottom-side oil chamber.

F = AB x PB - AR x PR ... (27)
Therefore, since the thrust F of the boom cylinder 7 needs to be smaller than the limit thrust FMAX, the following equation (28) needs to be satisfied.

FMAX>AB·PB-AR·PR ... (28)
Therefore, the following equation (29) is obtained from equation (28).

PB < (FMAX + AR · PR) / AB ... (29)
The right side of equation (29) corresponds to the upper limit value PBMAX of the bottom pressure PB corresponding to the limited thrust force FMAX, and the following equation (30) is obtained.

PBMAX=(FMAX+AR·PR)/AB (30)
The operation correction unit 302 corrects the operation of the attachment, i.e., the operation of the boom cylinder 7, so that equation (30) is satisfied. That is, the operation correction unit 302 adjusts the bottom pressure PB of the boom cylinder 7 so that equation (30) is satisfied. More specifically, by employing various configurations (see FIGS. 27 to 35) described later, the operation correction unit 302 can adjust the bottom pressure PB of the boom cylinder 7 and suppress the vibration operation of the excavator 100 by appropriately outputting a control command to the controlled object.

The operation correction unit 302 acquires the limited thrust FMAX based on the detection signals from the various sensors 32. In one embodiment, the limited thrust acquisition unit 586 acquires the limited thrust FMAX by performing a calculation using the state of the attachment, i.e., the detection signals from the various sensors 32, as input. As a result, the operation correction unit 302 can calculate the upper limit value PBMAX of the bottom pressure PB from equation (30) and adjust the bottom pressure PB of the boom cylinder 7 so that it does not exceed the calculated upper limit value PBMAX.

At this time, if the limit thrust FMAX is made too small, the boom 4 will move down, so the operation correction unit 302 should obtain the thrust capable of maintaining the attitude of the boom 4 (holding thrust FMIN) and set the limit thrust FMAX in a range higher than the holding thrust FMIN.

For example, FIG. 18 is a diagram explaining a method for acquiring the limited thrust FMAX by the operation correction unit 302. Specifically, FIG. 18 is a block diagram showing the configuration related to the function for acquiring the limited thrust FMAX in the operation correction unit 302.

As shown in FIG. 18, the operation correction unit 302 acquires (sets) the limit thrust FMAX based on table reference. The operation correction unit 302 includes a first lookup table 600, a second lookup table 602, a table selector 604, and a selector 606.

The first lookup table 600 receives the boom angle θ1, which is the output of the boom angle sensor included in the various sensors 32, and outputs the limited thrust FMAX. The first lookup table 600 may include multiple tables corresponding to multiple different states of the excavator 100 that are defined in advance.

The second lookup table 602 receives the boom angle θ1 and arm angle θ2 output from the boom angle sensor and arm angle sensor included in the various sensors 32, and outputs the retained thrust FMIN. Like the first lookup table 600, the second lookup table 602 may include multiple tables corresponding to multiple different states of the excavator 100 that are defined in advance.

The table selector 604 selects an optimal table from the first lookup table 600 using at least one of the bucket angle θ3, pitch angle θP, and swing angle θS of the vehicle body as parameters, which are output from the bucket angle sensor included in the various sensors 32, and the pitch angle sensor and swing angle sensor mounted on the vehicle body (upper rotating body 3).

The table selector 604 also selects an optimal table from the second lookup table 602 using at least one of the bucket angle θ3, the vehicle body pitch angle θP, and the swing angle θS as a parameter.

The selector 606 outputs the larger of the limit thrust FMAX and the maintained thrust FMIN. This makes it possible to suppress the vibration motion while preventing the boom from lowering.

The operation correction unit 302 may obtain the limit thrust FMAX by calculation instead of by referring to a table. Similarly, the operation correction unit 302 may obtain the retained thrust FMIN by calculation instead of by referring to a table.

[Method of determining unintended excavator operation]
Next, a method for determining an unintended action will be described with reference to FIGS.

<Method of determining dragging motion>
Fig. 19 is a diagram illustrating a first example of a method for determining the occurrence of a dragging motion of the shovel 100. Specifically, Fig. 19 is a diagram illustrating an example of the mounting position of the acceleration sensor 32A attached to the upper rotating body 3 of the shovel 100.

The various sensors 32 of the excavator 100 in this example include an acceleration sensor 32A.

As shown in FIG. 19, the acceleration sensor 32A is mounted on the upper rotating body 3.

The acceleration sensor 32A has a detection axis in a direction along a straight line L1 that corresponds to the direction in which the attachment extends when the shovel 100 is viewed in a plan view. The point of application of the force that the attachment exerts on the upper rotating body 3 is the base 3A of the boom 4. Therefore, it is desirable to provide the acceleration sensor 32A at the base 3A of the boom 4. This allows the operation determination unit 301 to suitably identify the occurrence of a dragging operation of the shovel 100 caused by the operation of the attachment based on the output signal of the acceleration sensor 32A.

If the acceleration sensor 32A is moved away from the rotation axis 3B, the acceleration sensor 32A will be affected by the centrifugal force caused by the rotational motion of the upper rotating body 3. Therefore, it is desirable to place the acceleration sensor 32A near the base 3A of the boom 4 and near the rotation axis 3B.

That is, it is desirable to place the acceleration sensor 32A in the region R1 between the base 3A of the boom 4 and the rotation axis 3B of the upper rotating body 3. This reduces the influence of the rotational motion contained in the output of the acceleration sensor 32A, so that the operation determination unit 301 can preferably detect the dragging motion caused by the operation of the attachment based on the output of the acceleration sensor 32A.

In addition, if the acceleration sensor 32A is positioned too far from the ground, the acceleration components caused by pitching and rolling are likely to be included in the output of the acceleration sensor 32A. From this perspective, it is preferable to position the acceleration sensor 32A as low as possible on the upper rotating body 3.

In addition, in this example, instead of the acceleration sensor 32A, a speed sensor that may be included in the various sensors 32 may be mounted at a similar position on the upper rotating body 3. This allows the operation determination unit 301 to identify the occurrence of a dragging operation of the excavator 100 based on the output corresponding to the speed along the straight line L1 detected by the speed sensor.

In this example, the various sensors 32 may further include an angular velocity sensor mounted on the upper rotating body 3 in addition to the acceleration sensor 32A. In this case, the motion correction unit 302 may correct the output of the acceleration sensor 32A based on the output of the angular velocity sensor. The output of the acceleration sensor 506 may include not only linear motion in a specific direction (dragging motion), but also rotational motion components in the pitching, yawing, and rolling directions. According to this modified example, by using the angular velocity sensor in combination, it is possible to eliminate the influence of rotational motion and extract only linear motion equivalent to dragging motion, thereby improving the accuracy of the motion determination unit 301 in determining the dragging motion.

In this example, the acceleration sensor 32A is provided on the upper rotating body 3, but it may also be provided on the lower running body 1. In this case, by also using the output of an angle sensor that detects the rotation angle (rotation position) of the upper rotating body 3, which may be included in the various sensors 32, the motion determination unit 301 can identify linear motion along the extension direction of the attachment (straight line L1) from the output of the acceleration sensor 32A of the lower running body 1, and identify the occurrence of a dragging motion in that direction.

Next, Figure 20 is a diagram explaining a second example of a method for determining whether a dragging motion has occurred.

In this example, the various sensors 32 include a distance sensor 32B.

As shown in FIG. 20, the distance sensor 32B is attached to the front end of the upper rotating body 3 of the shovel 100, and measures the distance between the terrain, such as the ground, obstacles, etc., in a predetermined range in front of the upper rotating body 3 of the shovel 100, and the vehicle body (upper rotating body 3) to which it is attached. The distance sensor 32B is, for example, a LIDAR (Light Detection and Ranging), a millimeter wave radar, a stereo camera, etc.

The operation determination unit 301 determines the occurrence of a dragging operation of the shovel 100 based on a change in the relative positional relationship between the upper rotating body 3 and a fixed reference object around the shovel 100 measured by the distance sensor 32B. Specifically, the operation determination unit 301 can determine that a dragging operation has occurred when the relative position of the ground 200a seen from the upper rotating body 3 moves in a substantially horizontal direction, specifically, substantially parallel to the plane on which the shovel 100 is located, based on the output of the distance sensor 32B. For example, as shown in FIG. 20, the operation determination unit 301 can determine that a forward dragging operation of the shovel 100 has occurred based on the output of the distance sensor 32B when the relative position of the ground 200a in front of the upper rotating body 3 moves substantially horizontally toward the side approaching the upper rotating body 3 (the position of the dotted line 200b). Conversely, the motion determination unit 301 can determine that a backward drag motion of the excavator 100 has occurred when the ground surface 200a in front of the upper rotating body 3 moves substantially horizontally away from the upper rotating body 3.

In addition, the operation determination unit 301 may determine the occurrence of a dragging operation by using another sensor, such as an image sensor (monocular camera), capable of detecting the relative positional relationship between the upper rotating body 3 and a fixed reference object in the vicinity of the excavator 100, instead of the distance sensor 32B.

In addition, the fixed reference object of the shovel 100 is not limited to the ground, but may be a structure or a specific object intentionally placed around the shovel 100 for use as a reference object.

The distance sensor 32B may be attached to the attachment instead of the upper rotating body 3. In this case, the motion determination unit 301 only needs to be able to measure not only the distance between the attachment and the reference object, but also the distance between the attachment and the upper rotating body 3. This allows the motion determination unit 301 to identify the relative positions of the reference object and the upper rotating body 3 as seen from the attachment based on the output of the distance sensor 32B, that is, to indirectly determine the relative positional relationship between the upper rotating body 3 and the reference object. Therefore, based on the output of the distance sensor 32B mounted on the attachment, the motion determination unit 301 can determine that a dragging motion has occurred when the relative positional relationship between the upper rotating body 3 and the reference object has changed and moved approximately parallel to the plane on which the upper rotating body 3 is located as seen from the upper rotating body 3.

21(a) and (b) are diagrams illustrating a third example of a method for determining whether a dragging motion has occurred. Specifically, FIG. 21(a) shows the shovel 100 when a dragging motion has not occurred, and FIG. 21(b) shows the shovel 100 when a dragging motion has occurred.

In this example, the various sensors 32 include an IMU 32C.

As shown in Figures 21(a) and (b), the IMU 32C is attached to the boom 4.

As shown in FIG. 21(a), when no dragging motion is occurring in the excavator 100, the IMU 32C of the boom 4 detects rotational motion corresponding to the raising and lowering of the boom 4, and the forward/rearward acceleration component detected by the IMU 32C is output as a relatively small value due to the rotational motion.

On the other hand, as shown in FIG. 21(b), when a dragging motion occurs in the shovel 100, the shovel 100 moves in the forward/backward direction, so the dragging direction, i.e., the acceleration component in the forward/backward direction, is output by the IMU 32C as a relatively large value.

Therefore, the motion determination unit 301 may determine that a dragging motion has occurred, for example, when the acceleration component detected by the IMU 32C is equal to or greater than a predetermined threshold. The predetermined threshold may be set appropriately based on experiments, simulation analysis, and the like. In addition, the motion determination unit 301 can determine whether the motion is a forward dragging motion or a backward dragging motion depending on the direction of the detected acceleration component.

In this example, a speed sensor, acceleration sensor, or the like may be used instead of the IMU 32C if it is possible to detect the movement of the boom 4 in the forward and backward directions. In this case, the operation determination unit 301 may determine that a dragging operation has occurred when the output value of the sensor becomes relatively large, similar to the case of the IMU 32C.

22(a) and (b) are diagrams illustrating a fourth example of a method for determining whether a dragging motion has occurred. Specifically, FIG. 22(a) shows the shovel 100 when a dragging motion has not occurred, and FIG. 22(b) shows the shovel 100 when a dragging motion has occurred.

In this example, the various sensors 32 include two IMUs 32C.

As shown in Figures 22(a) and (b), one of the IMUs 32C is attached to the arm 5, and the other IMU 32C is attached to the bucket 6.

As shown in FIG. 22(a), when no dragging motion is occurring in the shovel 100, the forward/rearward acceleration component detected by the IMU 32C of the bucket 6 is expressed as a combination of the acceleration component of the arm 5 and the angular acceleration component about the drive shaft of the bucket 6. Therefore, the acceleration component detected by the IMU 32C of the bucket 6 is relatively larger than the forward/rearward acceleration component detected by the IMU 32C of the arm 5.

On the other hand, as shown in FIG. 22(b), when a dragging motion occurs in the shovel 100, the arm 5 moves in the fore-and-aft direction in response to the dragging motion, but the bucket 6 is difficult to move because it is in contact with the ground due to excavation work. Therefore, the fore-and-aft acceleration component detected by the IMU 32C of the bucket 6 is somewhat smaller than the fore-and-aft acceleration component detected by the IMU 32C of the arm 5.

Therefore, the operation determination unit 301 may determine that a dragging motion has occurred, for example, when the difference between the acceleration components detected by the IMU 32C of the arm 5 and the bucket 6 is equal to or greater than a predetermined threshold. The predetermined threshold can be set appropriately based on experiments, simulation analysis, and the like. In addition, the operation determination unit 301 can determine whether a forward dragging motion or a backward dragging motion has occurred depending on the direction of the acceleration component of the arm 5.

In addition, it is preferable that the IMU 32C attached to the arm 5 is positioned as close as possible to the connection position between the boom 4 and the arm 5 rather than the connection position between the arm 5 and the bucket 6. This makes it possible to maximize the amount of movement of the attachment position of the IMU 32C on the arm 5 when a dragging motion of the excavator 100 occurs, with the connection position between the arm 5 and the bucket 6 as the fulcrum. This makes it easier for the motion determination unit 301 to determine the dragging motion based on the difference between the acceleration components detected by the IMU 32C of the arm 5 and the bucket 6.

In this example, a speed sensor, an acceleration sensor, or the like may be used instead of the IMU 32C as long as the forward and backward movements of the arm 5 and the bucket 6 can be detected. In this example, the IMU 32C is attached to the arm 5 and the bucket 6, but it may also be attached to the boom 4. This allows the presence or absence of dragging motion to be determined not only from the difference in the output values of the IMU 32C of the arm 5 and the bucket 6, but also from the difference in the output values of the IMU 32C of the boom 4 and the bucket 6, thereby improving the accuracy of the determination. The IMU 32C of the arm 5 may also be attached to the boom 4. In this case, the presence or absence of dragging motion can be determined from the difference in the output values of the IMU 32C of the boom 4 and the bucket 6.

<How to determine floating motion>
Fig. 23 is a diagram illustrating a first example of a method for determining the occurrence of a lifting motion of the shovel 100. Specifically, Fig. 23(a) to (c) are diagrams showing the time changes in the tilt angle, angular velocity, and angular acceleration in the front-to-rear direction (pitch direction) of the vehicle body when a lifting motion of the shovel occurs.

In this example, the operation determination unit 301 determines the occurrence of a lift-up operation of the excavator 100 based on the output of a sensor included in the various sensors 32 that is capable of outputting angle-related information regarding the inclination of the vehicle body in the fore-and-aft direction, i.e., the inclination angle in the pitch direction.

As a sensor capable of outputting angle-related information (tilt angle, angular velocity, angular acceleration, etc.) regarding the tilt angle of the vehicle body in the pitch direction, an inclination sensor (angle sensor), an angular velocity sensor, an IMU, etc. can be used.

For example, as shown in Figures 23(a) to (c), when a lift-up motion occurs, the tilt angle, angular velocity, and angular acceleration in the pitch direction of the shovel 100 become relatively large values, so the motion determination unit 301 can determine that a lift-up motion has occurred when these values become equal to or greater than a predetermined threshold value (a fixed value indicated by a dotted line in the figure). In addition, the motion determination unit 301 can determine whether a front lift-up motion or a rear lift-up motion has occurred based on the direction in which the tilt angle, angular velocity, and angular acceleration occur, i.e., whether the tilt is backward or forward around the pitch axis.

Next, Figure 24 is a diagram illustrating a second example of a method for determining whether a floating motion has occurred.

In this example, the various sensors 32 include a distance sensor 32B, as in the case of Figure 20.

As shown in FIG. 24, the distance sensor 32B is attached to the front end of the upper rotating body 3 of the shovel 100, as in the case of FIG. 20, and measures the distance between the terrain, such as the ground, obstacles, etc., in a predetermined range in front of the upper rotating body 3 of the shovel 100, and the vehicle body (upper rotating body 3) to which it is attached.

20, the operation determination unit 301 determines the occurrence of the lifting operation of the shovel 100 based on the change in the relative positional relationship between the upper rotating body 3 and a fixed reference object around the shovel 100 measured by the distance sensor 32B. Specifically, the operation determination unit 301 can determine that the lifting operation has occurred when the relative position of the ground 240a seen from the upper rotating body 3 moves in a substantially vertical direction, specifically, in a direction substantially perpendicular to the plane on which the shovel 100 is located, based on the output of the distance sensor 32B. For example, as shown in FIG. 24, the operation determination unit 301 can determine that the front lifting operation of the shovel 100 has occurred based on the output of the distance sensor 32B when the relative position of the ground 200a in front of the upper rotating body 3 moves in a substantially downward direction (dotted line 240b in the figure). Conversely, the motion determination unit 301 can determine that the rear of the excavator 100 has been lifted up when the relative position of the ground 240a in front of the upper rotating body 3 moves in a substantially upward direction.

In addition, instead of the distance sensor 32B, the operation determination unit 301 may use another sensor capable of detecting the relative positional relationship between the upper rotating body 3 and a fixed reference object in the vicinity of the excavator 100, such as an image sensor (monocular camera), to determine the occurrence of a lift-up operation.

In addition, the fixed reference object of the shovel 100 is not limited to the ground, but may be a structure or a specific object intentionally placed around the shovel 100 for use as a reference object.

The distance sensor 32B may be attached to the attachment instead of the upper rotating body 3. In this case, the motion determination unit 301 only needs to be able to measure not only the distance between the attachment and the reference object, but also the distance between the attachment and the upper rotating body 3. This allows the motion determination unit 301 to identify the relative positions of the reference object and the upper rotating body 3 as seen from the attachment based on the output of the distance sensor 32B, that is, to indirectly determine the relative positional relationship between the upper rotating body 3 and the reference object. Therefore, based on the output of the distance sensor 32B mounted on the attachment, the motion determination unit 301 can determine that a lift-up motion has occurred when the relative positional relationship between the upper rotating body 3 and the reference object has changed and moved approximately perpendicular to the plane on which the upper rotating body 3 is located as seen from the upper rotating body 3.

Next, Fig. 25 is a diagram illustrating a third example of a method for determining whether a lift-up motion has occurred. Specifically , Fig. 25(a) shows the shovel 100 when a lift-up motion has not occurred, and Fig. 25(b) shows the shovel 100 when a lift-up motion has occurred.

In this example, the various sensors 32 include an IMU 32C, as in the case of Figures 21 (a) and (b).

As shown in Figures 25(a) and (b), the IMU 32C is attached to the boom 4, similar to the case of Figures 21(a) and (b).

As shown in FIG. 25(a), when the excavator 100 is not lifting up, the IMU 32C of the boom 4 detects rotational motion corresponding to the relatively gradual raising and lowering of the boom 4, and the angular acceleration component detected by the IMU 32C is output as a relatively small value.

On the other hand, as shown in FIG. 25(b), when the shovel 100 is undergoing a lifting motion, the angular acceleration component in the lifting direction is output by the IMU 32C as a relatively large value.

Therefore, the motion determination unit 301 may determine that a lift-up motion of the shovel 100 has occurred, for example, when the angular acceleration component detected by the IMU 32C is equal to or greater than a predetermined threshold. The predetermined threshold may be set as appropriate based on experiments, simulation analysis, and the like. In addition, the motion determination unit 301 can determine whether a forward drag motion or a backward drag motion has occurred depending on the direction of the detected acceleration component.

In addition, if the direction in which the boom 4 is raised and lowered is opposite to the direction in which the shovel 100 is lifted, it may not be possible to determine whether or not a lifting operation has occurred based on only the absolute value of the angular acceleration generated in the boom 4. Therefore, the operation determination unit 301 may determine that a lifting operation of the shovel 100 has occurred when the amount of change or rate of change in the angular acceleration of the boom 4 based on the IMU 32C is equal to or greater than a predetermined threshold value.

In this example, a speed sensor, acceleration sensor, or the like may be used instead of the IMU 32C as long as it is possible to detect the movement of the boom 4 in the rotational direction. In this case, the operation determination unit 301 may determine that a lift-up operation has occurred when the output value of the sensor becomes relatively large or when the rate of change of the output value becomes relatively large, similar to the case of the IMU 32C.

Next, Figure 26 is a diagram illustrating a fourth example of a method for determining whether a floating motion has occurred.

Specifically, FIG. 26(a) shows the shovel 100 when no lifting action is occurring, and FIG. 26(b) shows the shovel 100 when a lifting action is occurring.

In this example, the various sensors 32 include two IMUs 32C, as in the case of Figures 22(a) and (b).

As shown in Figures 26(a) and (b), one of the IMUs 32C is attached to the arm 5, and the other IMU 32C is attached to the bucket 6.

As shown in FIG. 26(a), when the shovel 100 is not lifting up, the acceleration component in the front-rear direction detected by the IMU 32C of the bucket 6 is expressed as a combination of the acceleration component of the arm 5 and the angular acceleration component about the drive shaft of the bucket 6. Therefore, the acceleration component detected by the IMU 32C of the bucket 6 is relatively larger than the acceleration component in the front-rear direction detected by the IMU 32C of the arm 5.

On the other hand, as shown in FIG. 26(b), when the shovel 100 is lifting up, the arm 5 moves (rotates) around the contact point between the bucket 6 and the ground in response to the lifting up motion, but the bucket 6 is difficult to move because it is in contact with the ground due to excavation work. Therefore, the acceleration component in the front-rear direction and the angular acceleration component about the drive shaft detected by the IMU 32C of the bucket 6 are somewhat smaller than the acceleration component in the front-rear direction and the angular acceleration component detected by the IMU 32C of the arm 5.

Therefore, the operation determination unit 301 may determine that a lift-up motion has occurred, for example, when the difference between the acceleration components detected by the IMU 32C of the arm 5 and the bucket 6, or the angular acceleration around an axis parallel to the drive shaft of the attachment, becomes equal to or greater than a predetermined threshold. The predetermined threshold can be set appropriately based on experiments, simulation analysis, etc. Furthermore, the operation determination unit 301 can determine whether a forward lift-up motion or a backward lift-up motion has occurred depending on the direction of the acceleration component of the arm 5.

In addition, it is preferable that the IMU 32C attached to the arm 5 is positioned as close as possible to the connection position between the boom 4 and the arm 5 rather than the connection position between the arm 5 and the bucket 6. This makes it possible to maximize the amount of movement of the attachment position of the IMU 32C on the arm 5 when the shovel 100 is lifted up, with the connection position between the arm 5 and the bucket 6 as the fulcrum. This makes it easier for the operation determination unit 301 to determine the lifting up operation based on the difference between the acceleration components detected by the IMU 32C of the arm 5 and the bucket 6.

In this example, a speed sensor, an acceleration sensor, an angular acceleration sensor, or the like may be used instead of the IMU 32C if it is possible to detect the forward and backward movements of the arm 5 and the bucket 6 and the movements in the rotational direction around an axis parallel to the movement axis. In this example, the IMU 32C is attached to the arm 5 and the bucket 6, but it may also be attached to the boom 4. This allows the presence or absence of dragging motion to be determined not only from the difference in the output values of the IMU 32C of the arm 5 and the bucket 6, but also from the difference in the output values of the IMU 32C of the boom 4 and the bucket 6, thereby improving the accuracy of the determination. The IMU 32C of the arm 5 may also be attached to the boom 4. In this case, the presence or absence of lift-up motion can be determined from the difference in the IMU 32C of the boom 4 and the bucket 6.

<Method of determining occurrence of vibration movement>
The motion determination unit 301 can determine the occurrence of a vibration motion by mounting sensors capable of detecting vibrations included in the various sensors 32, such as an acceleration sensor, an angular acceleration sensor, an IMU, etc., on the vehicle body (upper rotating body 3). Specifically, the motion determination unit 301 may determine that a vibration motion is occurring when it can be determined that there is a vibration that matches a specific frequency of the vibration of the vehicle body induced by a change in the moment of inertia of the attachment based on the output of these sensors included in the various sensors 32.

As described above, the vibration motion occurs during the aerial movement of the attachment. Therefore, the movement determination unit 301 may determine that the vibration motion is occurring if it can determine, based on the output of the various sensors 32, that there is a vibration that matches the specific frequency of the vehicle body vibration induced by a change in the moment of inertia of the attachment during the aerial movement of the attachment.

[Details of configuration to correct attachment operation]
Next, with reference to Figs. 27 to 35, a specific example of a characteristic configuration of the shovel 100 according to this embodiment, that is, a configuration for correcting the operation of the attachment to suppress unintended operation, will be described.

First, FIG. 27 is a diagram showing a first example of a characteristic configuration of the excavator 100 according to this embodiment. Specifically, it is a diagram showing a first example of a configuration centered on a hydraulic circuit that supplies hydraulic oil to the boom cylinder 7 of the excavator 100 according to this embodiment.

In this example, it is assumed that the boom 4, i.e., the boom cylinder 7, is operated by the lever device 26A. The same applies to Figures 28 to 35 below. In addition, the hydraulic line 27 that transmits the secondary pilot pressure from the lever device 26A to the port of the boom directional control valve 17A that supplies hydraulic oil to the boom cylinder 7 in the control valve 17 is referred to as the hydraulic line 27A.

As shown in FIG. 27, in this example, bypass oil passages 281, 282 are provided that branch off between the boom directional control valve 17A in the control valve 17 and the rod side oil chamber and bottom side oil chamber of the boom cylinder 7, and discharge the hydraulic oil into the tank T.

The bypass oil passage 281 is provided with an electromagnetic relief valve 33 that discharges hydraulic oil from the rod side oil chamber of the boom cylinder 7 to T.

The bypass oil passage 282 is provided with an electromagnetic relief valve 33 that discharges hydraulic oil from the bottom oil chamber of the boom cylinder 7 into the tank T.

The bypass oil passages 281, 282 and the electromagnetic relief valves 33, 34 may be provided either inside or outside the control valve 17.

The various sensors 32 also include pressure sensors 32D and 32E that detect the rod pressure PR and bottom pressure PB of the boom cylinder 7, and their outputs are input to the controller 30.

The controller 30, i.e., the operation correction unit 302, can monitor the rod pressure PR and the bottom pressure PB based on the output signals input from the pressure sensors 32D and 32E. The operation correction unit 302 can also output current command values to the electromagnetic relief valves 33 and 34 as appropriate, forcibly discharging the hydraulic oil in the rod-side oil chamber or the bottom-side oil chamber of the boom cylinder 7 into the tank T, thereby suppressing the excessive pressure in the boom cylinder 7. Therefore, by adopting the correction method for correcting the operation of the boom cylinder 7 described with reference to Figures 9 to 17 and reducing the excessive pressure generated in the boom cylinder 7, it is possible to suppress unintended operations of the excavator 100, i.e., dragging operations and lifting operations.

Next, FIG. 28 is a diagram showing a second example of a characteristic configuration of the excavator 100 according to this embodiment. Specifically, it is a diagram showing a second example of a configuration centered on a hydraulic circuit that supplies hydraulic oil to the boom cylinder 7 of the excavator 100 according to this embodiment.

As shown in FIG. 28, in this example, an electromagnetic proportional valve 36 is provided in the hydraulic line 27A between the lever device 26A and the port of the boom directional control valve 17A.

The various sensors 32 also include pressure sensors 32D and 32E that detect the rod pressure PR and bottom pressure PB of the boom cylinder 7, as in the case of FIG. 27, and their outputs are input to the controller 30.

The controller 30, i.e., the operation correction unit 302, can monitor the rod pressure PR and the bottom pressure PB based on the output signals input from the pressure sensors 32D and 32E. In addition, the operation correction unit 302 can change the pilot pressure corresponding to the operation state of the lever device 26A by appropriately outputting a current command value to the electromagnetic proportional valve 36, and input it to the port of the boom direction control valve 17A. That is, the operation correction unit 302 can control the boom direction control valve 17A by appropriately outputting a current command value to the electromagnetic proportional valve 36, and appropriately discharge the hydraulic oil in the rod side oil chamber or the bottom side oil chamber of the boom cylinder 7 to the tank T, thereby suppressing excessive pressure in the boom cylinder 7. Therefore, by adopting the correction method for correcting the operation of the boom cylinder 7 described with reference to Figures 9 to 17 and reducing the excessive pressure generated in the boom cylinder 7, unintended operations of the excavator 100, i.e., dragging operation and lifting operation, can be suppressed.

Next, FIG. 29 is a diagram showing a third example of a characteristic configuration of the excavator 100 according to this embodiment. Specifically, it is a diagram showing a third example of a configuration centered on a hydraulic circuit that supplies hydraulic oil to the boom cylinder 7 of the excavator 100 according to this embodiment.

As shown in FIG. 29, the various sensors 32 include pressure sensors 32D, 32E that detect the rod pressure PR and bottom pressure PB of the boom cylinder 7, as in the case of FIG. 27, etc., and the outputs are input to the controller 30.

The controller 30, i.e., the operation correction unit 302, can monitor the rod pressure PR and the bottom pressure PB based on the output signals input from the pressure sensors 32D and 32E. The controller 30 can also control the output and flow rate of the main pump 14 by appropriately outputting a current command value to the regulator 14A, which controls the tilt angle of the swash plate of the main pump 14. That is, the operation correction unit 302 can appropriately output a current command value to the regulator 14A to limit the operation of the main pump 14, thereby limiting the flow rate of hydraulic oil supplied to the boom cylinder 7, and suppressing excessive pressure in the boom cylinder 7. Therefore, by adopting the correction method for correcting the operation of the boom cylinder 7 described with reference to Figures 9 to 17 and reducing the excessive pressure generated in the boom cylinder 7, unintended operations of the excavator 100, i.e., dragging operations and lifting operations, can be suppressed.

Next, FIG. 30 is a diagram showing a fourth example of a characteristic configuration of the excavator 100 according to this embodiment. Specifically, it is a diagram showing a fourth example of a configuration centered on a hydraulic circuit that supplies hydraulic oil to the boom cylinder 7 of the excavator 100 according to this embodiment.

As shown in FIG. 30, the various sensors 32 include pressure sensors 32D, 32E that detect the rod pressure PR and bottom pressure PB of the boom cylinder 7, as in the case of FIG. 27, etc., and the outputs are input to the controller 30.

The controller 30, i.e., the operation correction unit 302, can monitor the rod pressure PR and the bottom pressure PB based on the output signals input from the pressure sensors 32D and 32E. The operation correction unit 302 can also control the output of the engine 11 by outputting a control command to the ECM (Engine Control Module) 11A that controls the operating state of the engine 11 as appropriate. That is, the operation correction unit 302 can limit the output of the main pump 14 driven by the engine 11 and limit the flow rate of hydraulic oil supplied to the boom cylinder 7 by outputting a control command to the ECM 11A as appropriate and limiting the output of the engine 11. That is, the operation correction unit 302 can suppress excessive pressure in the boom cylinder 7. Therefore, by adopting the correction method for correcting the operation of the boom cylinder 7 described with reference to Figures 9 to 17 and reducing the excessive pressure generated in the boom cylinder 7, unintended operations of the excavator 100, i.e., dragging operations and lifting operations, can be suppressed.

Next, FIG. 31 is a diagram showing a fifth example of a characteristic configuration of the excavator 100 according to this embodiment. Specifically, it is a diagram showing a fifth example of a configuration centered on a hydraulic circuit that supplies hydraulic oil to the boom cylinder 7 of the excavator 100 according to this embodiment.

In this example, it is assumed that the various sensors 32 include pressure sensors similar to the pressure sensors 32D and 32E in Figures 27 to 30. The same applies to Figures 32 to 35 below.

As shown in FIG. 31, in this example, the control valve 17 includes an electromagnetic switching valve 38.

The electromagnetic switching valve 38 is provided in a manner that bypasses between the oil passage 311 that connects the boom directional control valve 17A and the bottom oil chamber of the boom cylinder 7, and the oil passage 312 that circulates the hydraulic oil to the tank T. As a result, when the electromagnetic switching valve 38 is in a connected state, it is possible to discharge the hydraulic oil in the bottom oil chamber of the boom cylinder 7 to the tank T.

The controller 30, that is, the operation correction unit 302, can monitor the rod pressure PR and the bottom pressure PB based on the output signals input from various sensors 32 (pressure sensors that detect the pressure in the rod-side oil chamber and the bottom-side oil chamber of the boom cylinder 7). In addition, the operation correction unit 302 can control the connected/disconnected state of the solenoid switching valve 38 by appropriately outputting a current command value to the solenoid switching valve 38. That is, the operation correction unit 302 can suppress the excessive pressure (bottom pressure PB) generated in the bottom-side oil chamber of the boom cylinder 7 by appropriately outputting a current command value to the solenoid switching valve 38 and discharging the hydraulic oil in the bottom-side oil chamber of the boom cylinder 7 to the tank T via the solenoid switching valve 38. Therefore, by adopting the correction method for correcting the operation of the boom cylinder 7 described with reference to Figures 9 to 17 and reducing the excessive pressure generated in the bottom-side oil chamber of the boom cylinder 7, unintended operations of the excavator 100, that is, dragging operations and lifting operations, can be suppressed.

In addition, an electromagnetic switching valve may be provided inside the control valve 17 to bypass between the oil passage connecting the boom directional control valve 17A and the rod-side oil chamber of the boom cylinder 7 and the oil passage 312 that circulates the hydraulic oil to the tank T. In this case, the operation correction unit 302 can also reduce excess pressure generated in the rod-side oil chamber of the boom cylinder 7 by appropriately outputting a current command value to the electromagnetic switching valve.

Next, FIG. 32 is a diagram showing a sixth example of a characteristic configuration of the excavator 100 according to this embodiment. Specifically, it is a diagram showing a fifth example of a configuration centered on a hydraulic circuit that supplies hydraulic oil to the boom cylinder 7 of the excavator 100 according to this embodiment. In the following figures, two boom cylinders 7 are shown, but the fact that a control valve 17 and a pressure retention circuit 40 (described later) are interposed between the main pump 14 and the boom cylinder 7 is the same for all boom cylinders 7, so the hydraulic circuit for one boom cylinder 7 (the boom cylinder 7 on the right side in the figure) will be mainly described.

In this embodiment, as in the case of FIG. 27, an electromagnetic relief valve 33 that discharges hydraulic oil from the rod-side oil chamber of the boom cylinder 7 to the tank T is provided in the oil passage that branches off between the control valve 17 and the rod-side oil chamber of the boom cylinder 7. The same applies to FIG. 33 below.

As shown in FIG. 32, the excavator 100 according to this example is provided with a pressure retention circuit 40 that keeps the hydraulic oil in the bottom oil chamber of the boom cylinder 7 from being discharged, even if the hydraulic hose is damaged due to bursting or the like. The same applies to FIGS. 33 to 35 below.

The pressure retention circuit 40 is disposed in the oil passage that connects the control valve 17 and the bottom oil chamber of the boom cylinder 7. The pressure retention circuit 40 mainly includes a retention valve 42 and a spool valve 44.

The retention valve 42 supplies hydraulic oil from the control valve 17 via the oil passage 321 to the bottom oil chamber of the boom cylinder 7, regardless of the state of the spool valve 44.

When the spool valve 44 is in a non-communicating state (spool state at the left end of the figure), the retention valve 42 holds the hydraulic oil in the bottom oil chamber of the boom cylinder 7 so that it is not discharged downstream of the pressure retention circuit 40. On the other hand, when the spool valve 44 is in a communicating state (spool state at the right end of the figure), the retention valve 42 allows the hydraulic oil in the bottom oil chamber of the boom cylinder 7 to be discharged downstream of the pressure retention circuit 40 via the oil passage 322.

The spool valve 44 is controlled in its connected/disconnected state according to the pilot pressure input to the port from the boom lowering remote control valve 26Aa, which is included in the lever device 26A that operates the boom cylinder 7 and outputs a pilot pressure corresponding to the lowering operation of the boom 4 (boom lowering operation). Specifically, when the spool valve 44 receives a pilot pressure indicating that the boom lowering operation is being performed from the boom lowering remote control valve 26Aa, the spool valve 44 is set to a spool state corresponding to the connected state (the spool state at the right end of the figure). On the other hand, when the spool valve 44 receives a pilot pressure indicating that the boom lowering operation is not being performed from the boom lowering remote control valve 26Aa, the spool valve 44 is set to a spool state corresponding to the disconnected state (the spool state at the left end of the figure). As a result, even if the hydraulic hose downstream of the pressure retention circuit 40 is damaged when the boom lowering operation is not being performed, the hydraulic oil (bottom pressure) in the bottom oil chamber of the boom cylinder 7 is maintained, so that the boom 4 can be prevented from falling.

The pressure maintenance circuit 40 also includes an electromagnetic relief valve 46.

The electromagnetic relief valve 46 is provided in an oil passage 324 that branches off from an oil passage 323 between the holding valve 42 in the pressure holding circuit 40 and the bottom oil chamber of the boom cylinder 7 and is connected to the tank T. In other words, the electromagnetic relief valve 46 relieves hydraulic oil from the oil passage 323 upstream of the holding valve, i.e., on the boom cylinder 7 side, to the tank T. Therefore, the electromagnetic relief valve 46 can discharge hydraulic oil from the bottom oil chamber of the boom cylinder 7 to the tank T regardless of the operating state of the pressure holding circuit 40, specifically, the connected/disconnected state of the spool valve 44. In other words, the pressure holding circuit 40 can prevent the boom 4 from falling by retaining the hydraulic oil in the bottom oil chamber of the boom cylinder 7, and can discharge the hydraulic oil from the bottom oil chamber of the boom cylinder 7 to the tank T regardless of whether the boom is lowered, thereby suppressing excessive bottom pressure.

The controller 30, that is, the operation correction unit 302, can monitor the rod pressure PR and the bottom pressure PB based on the output signals input from various sensors 32 (pressure sensors that detect the pressure in the rod-side oil chamber and the bottom-side oil chamber of the boom cylinder 7). In addition, the operation correction unit 302 can forcibly discharge the hydraulic oil in the rod-side oil chamber or the bottom-side oil chamber of the boom cylinder 7 to the tank T regardless of whether the boom is lowered or not by outputting a current command value to the electromagnetic relief valves 33, 46 as appropriate, thereby suppressing the excessive pressure in the boom cylinder 7. Therefore, by adopting the correction method for correcting the operation of the boom cylinder 7 described with reference to Figures 9 to 17 and reducing the excessive pressure generated in the boom cylinder 7, the unintended operation of the excavator 100, that is, the dragging operation and the lifting operation, can be suppressed.

Next, FIG. 33 is a diagram showing a seventh example of a characteristic configuration of the excavator 100 according to this embodiment. Specifically, it is a diagram showing a seventh example of a configuration centered on a hydraulic circuit that supplies hydraulic oil to the boom cylinder 7 of the excavator 100 according to this embodiment.

As shown in FIG. 33, in this example, an electromagnetic relief valve 50 is provided in an oil passage 332 that branches off from an oil passage 331 between the bottom oil chamber of the boom cylinder 7 and the pressure holding circuit 40 and is connected to the tank T. As a result, the electromagnetic relief valve 50 can discharge the hydraulic oil in the bottom oil chamber of the boom cylinder 7 to the tank T regardless of the operating state of the pressure holding circuit 40, specifically, the connected/disconnected state of the spool valve 44. In other words, the hydraulic oil in the bottom oil chamber of the boom cylinder 7 can be discharged to the tank T and excessive bottom pressure can be suppressed, while the hydraulic oil in the bottom oil chamber of the boom cylinder 7 can be discharged to the tank T regardless of the operating state of the boom cylinder 7 by the function of the pressure holding circuit 40 to hold the hydraulic oil in the bottom oil chamber of the boom cylinder 7.

The controller 30, i.e., the operation correction unit 302, can monitor the rod pressure PR and the bottom pressure PB based on output signals input from various sensors 32 (pressure sensors that detect the pressures in the rod-side oil chamber and the bottom-side oil chamber of the boom cylinder 7). In addition, the operation correction unit 302 can forcibly discharge the hydraulic oil in the rod-side oil chamber or the bottom-side oil chamber of the boom cylinder 7 to the tank T, regardless of the presence or absence of a boom lowering operation, by appropriately outputting a current command value to the electromagnetic relief valves 33, 50, thereby suppressing the excessive pressure in the boom cylinder 7. Therefore , by adopting the correction method for correcting the operation of the boom cylinder 7 described with reference to Figs . 9 to 17 and reducing the excessive pressure generated in the boom cylinder 7, it is possible to suppress unintended operations of the excavator 100, i.e., dragging operation and lifting operation.

Next, FIG. 34 is a diagram showing an eighth example of a characteristic configuration of the excavator 100 according to this embodiment. Specifically, it is a diagram showing an eighth example of a configuration centered on a hydraulic circuit that supplies hydraulic oil to the boom cylinder 7 of the excavator 100 according to this embodiment.

As shown in FIG. 34, a solenoid switching valve 52 and a shuttle valve 54 are provided in a pilot circuit that supplies pilot pressure corresponding to the operating state of the boom lowering operation from the boom lowering remote control valve 26Aa to the spool valve 44 of the pressure holding circuit 40.

The solenoid switching valve 52 is provided in an oil passage 341 that branches off from the pilot line 25A between the pilot pump 15 and the boom-lowering remote control valve 26Aa, bypasses the boom-lowering remote control valve 26Aa, and is connected to one input port of the shuttle valve 54. The solenoid switching valve 52 switches the oil passage 341 between connected and disconnected states.

In addition, an electromagnetic proportional valve may be used instead of the electromagnetic switching valve 52 to switch between the open and closed states of the oil passage 341.

As described above, one end of the oil passage 341 is connected to one input port of the shuttle valve 54, and the secondary oil passage 342 of the boom-lowering remote control valve 26Aa is connected to the other input port. The shuttle valve 54 outputs the higher pilot pressure of the two inputs to the spool valve 44. This allows the same pilot pressure as when the boom-lowering operation is being performed to be input to the spool valve 44 via the solenoid switching valve 52 and the shuttle valve 54, even when the boom-lowering operation is not being performed. In other words, even when the boom-lowering operation is not being performed, the hydraulic oil in the bottom-side oil chamber of the boom cylinder 7 can be discharged downstream of the pressure holding circuit 40.

In this example, electromagnetic relief valves 56 and 58 are provided inside the control valve 17.

The electromagnetic relief valves 56, 58 may be provided outside the control valve 17 as long as they are configured to bypass the oil passage between the boom directional control valve 17A and the pressure maintenance circuit 40 and discharge the hydraulic oil to the tank T.

The electromagnetic relief valve 56 is provided in an oil passage 343 that branches off from the oil passage between the rod-side oil chamber of the boom cylinder 7 and the boom directional control valve 17A and is connected to the tank T. This allows the electromagnetic relief valve 56 to discharge the hydraulic oil in the rod-side oil chamber of the boom cylinder 7 to the tank T.

The electromagnetic relief valve 58 is provided in an oil passage 344 that branches off from the oil passage between the pressure holding circuit 40 and the boom directional control valve 17A and is connected to the tank T. This allows the electromagnetic relief valve 56 to discharge hydraulic oil flowing out of the bottom oil chamber of the boom cylinder 7 to the tank T via the pressure holding circuit 40. That is, due to the action of the above-mentioned electromagnetic switching valve 52 and shuttle valve 54, the electromagnetic relief valve 58 can discharge hydraulic oil from the bottom oil chamber of the boom cylinder 7 to the tank T and suppress excessive bottom pressure PB even when the boom lowering operation is not being performed.

In this example, if the electromagnetic switching valve 38 of FIG. 35 is provided in the control valve 17, the function of the electromagnetic relief valve 58 may be replaced by the electromagnetic switching valve 38. Also, as described above, similar to the electromagnetic switching valve 38 of FIG. 35, a electromagnetic switching valve that bypasses between the oil passage connecting the boom directional control valve 17A and the rod side oil chamber of the boom cylinder 7 and the oil passage that circulates the hydraulic oil to the tank T may be provided in the control valve 17. In this case, the function of the electromagnetic relief valve 56 may be replaced by the electromagnetic switching valve. The same applies to FIG. 35 below.

The controller 30, i.e., the operation correction unit 302, can monitor the rod pressure PR and the bottom pressure PB based on the output signals input from various sensors 32 (pressure sensors that detect the pressure in the rod-side oil chamber and the bottom-side oil chamber of the boom cylinder 7). In addition, the operation correction unit 302 can forcibly discharge the hydraulic oil in the rod-side oil chamber or the bottom-side oil chamber of the boom cylinder 7 to the tank T regardless of whether the boom is lowered or not by outputting a current command value to the electromagnetic switching valve 52 and the electromagnetic relief valves 56, 58 as appropriate, thereby suppressing the excessive pressure in the boom cylinder 7. Therefore, by adopting the correction method for correcting the operation of the boom cylinder 7 described with reference to Figures 9 to 17 and reducing the excessive pressure generated in the boom cylinder 7, the unintended operation of the excavator 100, i.e., the dragging operation and the lifting operation, can be suppressed.

Next, FIG. 35 is a diagram showing a ninth example of a characteristic configuration of the excavator 100 according to this embodiment. Specifically, it is a diagram showing a ninth example of a configuration centered on a hydraulic circuit that supplies hydraulic oil to the boom cylinder 7 of the excavator 100 according to this embodiment.

As shown in Figure 35, in this example, an electromagnetic proportional valve 60 and a shuttle valve 54 similar to that in Figure 34 are provided in a pilot circuit that supplies pilot pressure corresponding to the operating state of the boom lowering operation from the boom lowering remote control valve 26Aa to the spool valve 44 of the pressure holding circuit 40.

The solenoid proportional valve 60 is provided in an oil passage 351 that branches off from the pilot line 25A between the pilot pump 15 and the boom lowering remote control valve 26Aa, bypasses the boom lowering remote control valve 26Aa, and is connected to one input port of the shuttle valve 54. The solenoid proportional valve 60 controls the switching between the connected and disconnected states of the oil passage 341, and controls the pilot pressure input to the shuttle valve 54.

As in the case of FIG. 34, one end of the oil passage 351 is connected to one input port of the shuttle valve 54, and the secondary oil passage 352 of the boom-lowering remote control valve 26Aa is connected to the other input port. The shuttle valve 54 outputs the higher of the two pilot pressures to the spool valve 44. This allows the same pilot pressure as when the boom-lowering operation is being performed to be input to the spool valve 44 via the solenoid proportional valve 60 and the shuttle valve 54, even when the boom-lowering operation is not being performed. In other words, even when the boom-lowering operation is not being performed, the hydraulic oil in the bottom-side oil chamber of the boom cylinder 7 can be discharged downstream of the pressure holding circuit 40.

In this example, an electromagnetic relief valve 56 is provided inside the control valve 17.

The electromagnetic relief valve 56 may be provided outside the control valve 17 as long as it is configured to bypass the oil passage between the boom directional control valve 17A and the pressure maintenance circuit 40 and discharge the hydraulic oil to the tank T.

As in the case of FIG. 34, the electromagnetic relief valve 56 is provided in an oil passage 353 that branches off from the oil passage between the rod-side oil chamber of the boom cylinder 7 and the boom directional control valve 17A and is connected to the tank T. This allows the electromagnetic relief valve 56 to discharge the hydraulic oil in the rod-side oil chamber of the boom cylinder 7 to the tank T.

The controller 30, i.e., the operation correction unit 302, can monitor the rod pressure PR and the bottom pressure PB based on output signals input from various sensors 32 (pressure sensors that detect the pressure in the rod-side oil chamber and the bottom-side oil chamber of the boom cylinder 7). In addition, the operation correction unit 302 can forcibly discharge the hydraulic oil in the rod-side oil chamber of the boom cylinder 7 into the tank T by outputting a current command value to the electromagnetic relief valve 56 as appropriate, thereby suppressing excess pressure (rod pressure) in the rod-side oil chamber of the boom cylinder 7.

In addition, by adopting the electromagnetic proportional valve 60, the pilot pressure input to the spool valve 44 can be finely controlled via the shuttle valve 54. Therefore, the controller 30 can finely adjust the flow rate of hydraulic oil flowing out of the bottom-side oil chamber of the boom cylinder 7 via the pressure holding circuit 40 by appropriately outputting a current command value to the electromagnetic proportional valve 60 and finely controlling the operating state of the electromagnetic proportional valve 60. In other words, the controller 30 can adjust the flow rate of hydraulic oil discharged from the bottom-side oil chamber of the boom cylinder 7 via the control valve 17 during the boom lowering operation without relying on the control valve 17. Therefore, the controller 30, i.e., the operation correction unit 302, can appropriately discharge the hydraulic oil in the bottom-side oil chamber of the boom cylinder 7 to the tank T regardless of whether the boom lowering operation is performed, by appropriately outputting a current command value to the electromagnetic proportional valve 60, thereby suppressing excessive pressure in the boom cylinder 7.

Therefore, by adopting the correction method for correcting the operation of the boom cylinder 7 described with reference to Figures 9 to 17 and reducing the excess pressure generated in the boom cylinder 7, unintended operations of the excavator 100, i.e., dragging operations and lifting operations, can be suppressed.

[Details of processing operation for correcting attachment operation]
Next, the process of correcting the movement of the attachment (movement correction process) performed by the controller 30 (movement determination unit 301, movement correction unit 302) will be described with reference to FIG.

Figure 36 is a flowchart that shows an example of the operation correction process by the controller 30 according to this embodiment. The process according to this flowchart is executed repeatedly at predetermined time intervals, for example, while the excavator 100 is in operation.

In step S3600, the operation determination unit 301 determines whether or not the shovel 100 is traveling based on input from the pressure sensor 29 and various sensors 32. If the shovel 100 is not traveling, the operation determination unit 301 proceeds to step S3602, and if the shovel 100 is traveling, the operation determination unit 301 ends the current process.

In step S3602, the operation determination unit 301 determines whether or not an attachment is being operated, i.e., whether or not work using an attachment is being performed (excavation work is being performed), based on input from the pressure sensor 29 and various sensors 32. If an attachment is being operated, the operation determination unit 301 proceeds to step S3604, and if an attachment is not being operated, the operation determination unit 301 ends the current process.

In step S3604, the operation determination unit 301 determines whether or not an unintended operation has occurred based on the input from the various sensors 32. At this time, the operation determination unit 301 determines whether or not an unintended operation has occurred by using the determination method described above, targeting all or some of the unintended operations described above. If an unintended operation has occurred, the operation determination unit 301 proceeds to step S3606, and if an unintended operation has not occurred, the operation determination unit 301 ends this processing.

In step S3606, the motion correction unit 302 acquires a control target value that matches the motion that is occurring (determined motion). For example, when it is determined that a vibration motion is occurring, the motion correction unit 302 acquires the limit thrust FMAX or the retained thrust FMIN as the control target value based on the contents described with reference to FIG. 18 above. Also, for unintended motions other than vibration motions, that is, dragging motions and lifting motions, the motion correction unit 302 may acquire the limit thrust as the control target value based on table reference, similar to the contents described with reference to FIG. 18.

In step S3608, the operation correction unit 302 outputs a control command to the control object to correct the operation of the attachment. As described above, the control object includes, for example, the electromagnetic relief valves 33 and 34, the electromagnetic proportional valve 36, the regulator 14A, the ECM 11A, the electromagnetic switching valve 38, the electromagnetic relief valve 46, the electromagnetic relief valve 50, the electromagnetic switching valve 52, the electromagnetic relief valves 56 and 58, the electromagnetic proportional valve 60, etc.

In this example, the occurrence of an unintended motion is determined by the motion determination unit 301. Then, the motion correction unit 302 corrects the motion of the attachment when the occurrence of an unintended motion is determined by the motion determination unit 301. In this way, the motion of the attachment is corrected after confirming that an unintended motion has actually occurred, so that it is possible to suppress unintended motion while suppressing deterioration of operability by the operator.

Although the above describes in detail the form for carrying out the present invention, the present invention is not limited to such specific embodiment, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

For example, in the above-described embodiment, a configuration (e.g., Figures 27, 31 to 35) has been mainly described in which hydraulic oil from both the rod-side oil chamber and the bottom-side oil chamber of the boom cylinder 7 can be discharged to the tank T, but a configuration in which hydraulic oil from only one of the oil chambers can be discharged to the tank T may also be used. Specifically, when the oil chamber whose pressure should be suppressed due to an anticipated unintended motion is known in advance (for example, when the control target is fixed to the bottom-side oil chamber, such as in the case of vibration motion), a configuration in which hydraulic oil from only one of the oil chambers can be discharged to the tank T may be employed.

In the above-described embodiment, the operation of the boom cylinder 7 of the attachment (specifically, the pressure of the boom cylinder 7) is mainly corrected, but it goes without saying that the operation of the arm cylinder 8 and the bucket cylinder 9 may also be controlled. Below, as a first modified example, a specific example of correcting the operation of the arm cylinder 8 will be described with reference to Figures 37 and 38.

37 and 38 are diagrams for explaining a first modified example of the shovel 100. Specifically, FIG. 37 is an operational waveform diagram relating to the dragging operation of the shovel 100. From the top, FIG. 37 shows the velocity v of the lower traveling body 1 along a straight line L1 corresponding to the direction in which the attachment extends, the acceleration α of the lower traveling body 1 along the straight line L1, the moment τ around the motion axis generated in the attachment (for example, the moment τ2 around the motion axis of the arm 5 shown in FIG. 38), and the force F3 along the straight line L1 that the motion of the attachment exerts on the body of the shovel 100. FIG. 38 is a diagram showing an example of a mechanical model corresponding to the excavation work by the shovel 100, and is a diagram showing an example of the forces acting on the shovel 100 during the excavation work.

In addition, in Figure 37, as a comparative example, the operating waveform when no correction of the attachment operation is made is shown by a dashed line.

First, we will explain the operation of the shovel 100 when no correction is made to the attachment operation.

As shown in FIG. 37, before time t0, no dragging occurs, the lower running body 1 is stationary with respect to the ground, and the velocity v is zero.

At time t0, when the operator further tilts the operating levers of the lever devices 26A and 26B, the moment τ2 (or the moments τ1 and τ3 around the motion axis of other attachments) increases. This increases the force F3 acting along the line L1 on the main body of the shovel 100. Then, at time t1, the force F3 exceeds the maximum static friction force μN. Then, the lower traveling body 1 begins to be dragged against the ground (begins to slip), and the velocity v increases as shown by the dashed line.

Next, we will explain the operation of the shovel 100 when the attachment operation is corrected.

As shown in FIG. 37, at time t1, when the lower running body 1 starts to slip, the acceleration α starts to increase. In other words, the dragging motion of the lower running body 1 appears as an increase in the acceleration α. Therefore, the motion determination unit 301 determines the occurrence of a dragging motion, for example, based on the acceleration α detected by the above-mentioned acceleration sensor 32A. For example, the motion determination unit 301 determines that a dragging motion has occurred when the acceleration α detected by the acceleration sensor 32A exceeds a predetermined threshold value αTH. Then, when the motion determination unit 301 makes this determination, the motion correction unit 302 activates correction control of the attachment motion (see FIG. 36).

Specifically, at time t2, the acceleration α exceeds the threshold value αTH, which enables the correction control by the operation correction unit 302. The correction control is enabled for the correction period T, during which the operation correction unit 302 reduces the moment τ2 around the motion axis of the arm 5, regardless of the operating state by the operator. When the moment τ2 decreases, the force F3 that the attachment exerts on the main body of the shovel 100 decreases. Then, when the force F3 falls below the kinetic friction force μ'N, the dragging motion ceases.

After the correction period T has elapsed, the correction control of the operation of the attachment (arm 5) is released and the original moment τ2 before correction based on the operation input by the operator is restored. The correction period T may be about 1 millisecond to 2 seconds, and considering the simulation results by the inventors, it is more preferable to set it to about 10 ms to 200 ms.

After the correction is released, the force F also increases to its original level, but because the lower running body 1 is stationary relative to the ground, it will remain stationary and no dragging action will occur again unless the force F exceeds the maximum static friction force μN.

For example, assuming the excavation work of FIG. 38, when the arm 5 is pulled (closed) with a large amount of soil loaded in the bucket 6, a force F3 is generated, and the lower traveling body 1 begins to be dragged forward. Then, the operation correction unit 302 instantly reduces the pressure of the arm cylinder 8 and limits the thrust in accordance with the judgment result by the operation judgment unit 301, thereby reducing the pulling force of the arm 5, i.e., the moment τ2. As a result, the force F3 applied from the attachment to the vehicle body (upper rotating body 3) decreases and falls below the kinetic friction force μ'N, and the dragging operation of the excavator 100 stops. After the dragging operation stops, the correction control by the operation correction unit 302 is released, and the moment τ2 of the arm 5 is returned to its original state, that is, it is returned to the moment τ2 according to the operation state by the operator. At this time, the maximum static friction force μN (> μ'N) is effective, so no dragging operation occurs. By periodically repeating this process at very short time intervals, dragging can be suppressed without requiring the operator to change the amount of operation of the control lever and without impairing the operator's operating feel (operability).

In this way, the movement of attachments other than the boom cylinder 7 can be corrected to prevent unintended movement.

In the above-described embodiment, the movement of the attachment is corrected by suppressing the pressure of the boom cylinder 7 etc. and limiting the thrust, but the movement of the attachment may be corrected in another manner. Below, as a second modified example, a method of correcting the movement of the attachment by displacing at least one of the attachments to finely adjust the attitude of the attachment will be described with reference to Fig. 39 .

Figure 39 is a diagram illustrating a second modified example of the shovel 100. Specifically, Figure 39 is a diagram illustrating a method of correcting an attachment in another aspect. Figure 39 shows the shovel 100 performing excavation work as viewed from the side. The state of the attachment before the operation correction is shown by a solid line, and the state of the attachment after the operation correction is shown by a dashed line.

For example, assume that a large amount of soil is loaded into the bucket 6, and the excavator 100 embraces the bucket 6 (i.e., closes the arm 5 and bucket 6). In this case, a moment T is generated with the bucket 6 as its center and the boom base 3A as its point of action. Of this moment T, the component parallel to the ground acts as a force F3 that drags the lower traveling structure 1.

When the operation of the attachment is corrected by the operation correction unit 302 and the posture of the attachment changes, the direction of the moment (force) acting on the base 3A changes from T to Ta. As an example, in FIG. 39, the operation correction unit 302 corrects the position of the boom 4 from the solid line to the dashed line 4a. The component Fa of the moment Ta after correction that is parallel to the ground (the force dragging the lower traveling body 1) becomes smaller than the force F3 before correction. This suppresses the dragging operation of the excavator 100. Specifically, the operation correction unit 302 realizes this correction by operating the arm cylinder 8 in the contraction direction (i.e., the direction in which the arm 5 is lowered) regardless of the operation state by the operator. More specifically, for example, the operation correction unit 302 may output a current command value for moving the arm cylinder 8 in the contraction direction to the electromagnetic proportional valve in FIG. 28.

In addition, when the direction of the moment changes from T to Ta, the component perpendicular to the ground, that is, the force pressing the lower running body 1 against the ground, increases. As a result, the normal force N increases compared to before correction, the kinetic friction force μ'N increases, and the dragging action is further suppressed.

In the example of FIG. 39, the dragging motion is suppressed by two actions: reducing the force F3 that affects the dragging motion and increasing the normal force N, but an embodiment using only one of these actions is also effective.

In this way, the posture of the attachment of the shovel 100 can be fine-tuned to correct the movement of the attachment and suppress unintended movement.

In the above-described embodiment, the operation of the attachment is corrected when it is determined that an unintended motion has occurred, but the operation of the attachment may be corrected so that the unintended motion is suppressed regardless of whether or not an unintended motion has occurred. Below, a method of correcting the operation of the attachment so that the unintended motion is suppressed regardless of whether or not an unintended motion has occurred will be described, taking the case of vibration motion as an example.

Figure 40 is a diagram illustrating a third modified example of the shovel 100. Specifically, it is a flowchart that shows an example of a process for suppressing vibration operation by the operation correction unit 302. The process according to this flowchart is executed repeatedly at predetermined time intervals, for example, while the shovel 100 is in operation.

In step S4000, the motion determination unit 301 determines whether or not an aerial motion is in progress. If the motion determination unit 301 determines that an aerial motion is in progress, the process proceeds to step S4002, and if the motion determination unit 301 determines that an aerial motion is not in progress, the process ends.

In step S4002, the operation correction unit 302 monitors the state of the attachment (e.g., boom angle θ1, arm angle θ2, bucket angle θ3, etc.).

In step S4004, the operation correction unit 302 determines, for example, the limit thrust FMAX depending on the state of the attachment (see Figure 18).

In step S4006, the operation correction unit 302 determines the holding thrust FMIN according to the state of the attachment (see Figure 18).

In step S4008, the operation correction unit 302 calculates the limit thrust FMAX and the holding thrust F
Based on MIN, an upper limit PMAX of the bottom pressure of the cylinder to be controlled (for example, boom cylinder 7) is determined (see FIG. 30).

In this way, the motion correction unit 302 may limit the thrust of the cylinder and suppress the vibration motion, regardless of the occurrence of the vibration motion. The same applies to the suppression of other unintended motions, that is, dragging motions and floating motions, and the motion correction unit 302 may execute control according to the control target value defined by the above-mentioned correction method (see FIGS. 9 to 18, etc.) and suppress the unintended motion, regardless of the occurrence of the unintended motion.

1. Lower running body (running body)
3. Upper rotating body (rotating body)
4 Boom (attachment)
5 Arm (attachment)
6 Bucket (attachment)
7 Boom cylinder 8 Arm cylinder 9 Bucket cylinder 21 Swing hydraulic motor 26 Operation device 26A, 26B Lever device 26C Pedal device 29 Pressure sensor 30 Controller 32 Various sensors (sensors)
32A Acceleration sensor 32B Distance sensor 32C IMU (first sensor, second sensor, third sensor)
32D, 32E Pressure sensor 33, 34 Solenoid relief valve 36 Solenoid proportional valve 38 Solenoid switching valve 40 Pressure holding circuit 42 Holding valve 44 Spool valve 46 Solenoid relief valve 50 Solenoid relief valve 52 Solenoid switching valve 54 Shuttle valve 56, 58 Solenoid relief valve 60 Solenoid proportional valve 301 Operation determination unit (determination unit)
302 Operation correction unit

Claims (7)

A running body,
A rotating body rotatably mounted on the traveling body;
An attachment including a boom, an arm, and a bucket that is mounted on the rotating body and is hydraulically driven by hydraulic oil supplied from a hydraulic pump;
A determination unit that determines whether or not a predetermined lift-up motion of the shovel occurs due to the movement of the attachment;
A first sensor that acquires information regarding a tilt state of the shovel ,
The determination unit determines whether the floating motion has occurred based on an output of the first sensor,
When the determination unit determines that the lift-up motion has occurred, the attachment is operated so as to suppress the lift-up motion by adjusting the output of a prime mover that drives the hydraulic pump or the hydraulic pump itself.
Shovel. A running body,
A rotating body rotatably mounted on the traveling body;
An attachment including a boom, an arm, and a bucket that is mounted on the rotating body and is hydraulically driven by hydraulic oil supplied from a hydraulic pump;
A determination unit that determines whether or not a predetermined lift-up motion of the shovel occurs due to the operation of the attachment;
a second sensor that acquires information regarding a relative positional relationship between the shovel and an object around the shovel, the object including an object other than the ground;
The determination unit determines whether the floating motion has occurred based on an output of the second sensor,
When the determination unit determines that the lift-up motion has occurred, the attachment is operated so as to suppress the lift-up motion by adjusting the output of a prime mover that drives the hydraulic pump or the hydraulic pump itself.
Shovel. A running body,
A rotating body rotatably mounted on the traveling body;
An attachment including a boom, an arm, and a bucket that is mounted on the rotating body and is hydraulically driven by hydraulic oil supplied from a hydraulic pump;
A determination unit that determines whether or not a predetermined lift-up motion of the shovel occurs due to the movement of the attachment;
a third sensor that obtains information regarding the angular velocity of the attachment ;
The determination unit determines whether the floating motion has occurred based on an output of the third sensor,
When the determination unit determines that the lift-up motion has occurred, the attachment is operated so as to suppress the lift-up motion by adjusting the output of a prime mover that drives the hydraulic pump or the hydraulic pump itself.
Shovel. A running body,
A rotating body rotatably mounted on the traveling body;
An attachment including a boom, an arm, and a bucket that is mounted on the rotating body and is hydraulically driven by hydraulic oil supplied from a hydraulic pump;
A determination unit that determines whether or not a predetermined lift-up motion of the shovel occurs due to the movement of the attachment;
a fourth sensor mounted on the bucket to acquire information regarding the acceleration of the bucket in a forward/rearward direction or information regarding the angular acceleration about a motion axis of the bucket;
a fifth sensor mounted on the boom or the arm and configured to acquire information regarding a forward/rearward acceleration of the boom or the arm, or information regarding an angular acceleration around a motion axis of the boom or the arm;
The determination unit determines whether or not the floating motion has occurred based on outputs of the fourth sensor and the fifth sensor,
When the determination unit determines that the lift-up motion has occurred, the attachment is operated so as to suppress the lift-up motion by adjusting the output of a prime mover that drives the hydraulic pump or the hydraulic pump itself.
Shovel as described. the determination unit determines whether or not the lift-up motion has occurred based on a difference between a forward/backward acceleration of the bucket and a forward/backward acceleration of the boom or the arm, or a difference between an angular acceleration about a motion axis of the bucket and an angular acceleration about a motion axis of the boom or the arm.
The shovel according to claim 4 . When the determination unit determines that the lift-up motion has occurred in a situation where the traveling body is not being operated and the attachment is being operated, the output of the prime mover or the hydraulic pump is adjusted to operate the attachment so as to suppress the lift-up motion.
A shovel according to any one of claims 1 to 5 . When the determination unit determines that the lift-up motion has occurred, the attachment is operated so as to adjust an output of the prime mover or the hydraulic pump to control an angular velocity of the boom.
A shovel according to any one of claims 1 to 6 .

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