Work machine, control system for work machine, control method for work machine

Abstract

A work machine includes a lower traveling body, an upper swivel body provided on the lower traveling body, an attachment assembly including a boom provided on the upper swivel body, an arm provided on the boom, and an end attachment provided on the arm, a tilt inertial measurement unit to detect a tilt angle and a tilt angular velocity of the end attachment, an angular velocity sensor to detect angular velocities of the boom, the arm, and the end attachment, and a controller to control an operation of the attachment assembly based on detection results of the tilt inertial measurement unit and the angular velocity sensor, wherein the controller switches between a detection mode in which the tilt angle is detected by the tilt inertial measurement unit, and an estimation mode in which the tilt angle is estimated from detection results of the tilt angular velocity and the angular velocities.

Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application is based on and claims priority to Japanese patent application No. 2025-057000 filed on Mar. 28, 2025, with the Japan Patent Office, the entire contents of which are hereby incorporated by reference.BACKGROUNDTechnical Field

[0002] The disclosures herein relate to work machines, control systems for work machines, and control methods for work machines.SUMMARY OF THE INVENTION

[0003] A work machine includes a lower traveling body, an upper swivel body provided on the lower traveling body so as to be capable of swiveling, an attachment assembly including a boom provided on the upper swivel body so as to be capable of raising and lowering, an arm provided on the boom so as to be capable of opening and closing, and an end attachment provided on the arm so as to be capable of opening and closing and tilting, a tilt inertial measurement unit configured to detect a tilt angle and a tilt angular velocity of the end attachment, an angular velocity sensor configured to detect angular velocities of the boom, the arm, and the end attachment, and a controller configured to control an operation of the attachment assembly based on detection results of the tilt inertial measurement unit and the angular velocity sensor, wherein the controller is configured to switch, based on an attitude of the attachment assembly, between a detection mode in which the tilt angle is detected by the tilt inertial measurement unit, and an estimation mode in which the tilt angle is estimated from detection results of the tilt angular velocity detected by the tilt inertial measurement unit and the angular velocities detected by the angular velocity sensor.

[0004] A control system for a work machine configured to control the work machine including a lower traveling body, an upper swivel body provided on the lower traveling body so as to be capable of swiveling, an attachment assembly including a boom provided on the upper swivel body so as to be capable of raising and lowering, an arm provided on the boom so as to be capable of opening and closing, and an end attachment provided on the arm so as to be capable of opening and closing and tilting, a tilt inertial measurement unit configured to detect a tilt angle and a tilt angular velocity of the end attachment, and an angular velocity sensor configured to detect angular velocities of the boom, the arm, and the end attachment, the control system includes a controller configured to control an operation of the attachment assembly based on detection results of the tilt inertial measurement unit and the angular velocity sensor, wherein the controller is configured to switch, based on an attitude of the attachment assembly, between a detection mode in which the tilt angle is detected by the tilt inertial measurement unit, and an estimation mode in which the tilt angle is estimated from detection results of the tilt angular velocity detected by the tilt inertial measurement unit and the angular velocities detected by the angular velocity sensor.

[0005] A method for controlling a work machine including a lower traveling body, an upper swivel body provided on the lower traveling body so as to be capable of swiveling, an attachment assembly including a boom provided on the upper swivel body so as to be capable of raising and lowering, an arm provided on the boom so as to be capable of opening and closing, and an end attachment provided on the arm so as to be capable of opening and closing and tilting, a tilt inertial measurement unit configured to detect a tilt angle and a tilt angular velocity of the end attachment, and an angular velocity sensor configured to detect angular velocities of the boom, the arm, and the end attachment, the method includes, when controlling an operation of the attachment assembly based on detection results of the tilt inertial measurement unit and the angular velocity sensor, switching, based on an attitude of the attachment assembly, between a detection mode in which the tilt angle is detected by the tilt inertial measurement unit, and an estimation mode in which the tilt angle is estimated from detection results of the tilt angular velocity detected by the tilt inertial measurement unit and the angular velocities detected by the angular velocity sensor.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 is a side view illustrating an embodiment of a work machine according to the present disclosure;

[0007] FIG. 2 is a block diagram schematically illustrating a configuration of the work machine shown in FIG. 1;

[0008] FIG. 3 is a functional block diagram illustrating a controller of the work machine shown in FIG. 2;

[0009] FIG. 4 is a side view illustrating an example of an excavation operation of the work machine shown in FIG. 1;

[0010] FIG. 5 is a graph illustrating mode switching with the controller of FIG. 3;

[0011] FIG. 6 is a graph illustrating mode switching with the controller of FIG. 3;

[0012] FIG. 7 is a block diagram illustrating a method of calculating an operation amount with the controller of FIG. 3;

[0013] FIG. 8 is a flow diagram illustrating an embodiment of a control method for the work machine according to the present disclosure; and

[0014] FIG. 9 is a schematic diagram illustrating an embodiment of a control system for the work machine according to the present disclosure.DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] In a related art, a system for supporting an operation of a work machine having an attachment assembly including an end attachment supported by a support via a tilt rotator is known.

[0016] The present disclosure provides a work machine for controlling the operation of an attachment assembly by detecting the tilt angle of the end attachment by an inertial measurement unit, and a control system for the work machine, and a control method for the work machine.

[0017] In the following, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the embodiments described below are not intended to limit the invention but are examples, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention. In the drawings, the same constituent elements are denoted with the same reference numerals, and redundant description thereabout may be omitted.Embodiment 1

[0018] First, an embodiment of a work machine according to the present disclosure will be described with reference to FIGS. 1 and 2. FIG. 1 is a side view illustrating an embodiment of the work machine according to the present disclosure. FIG. 2 is a block diagram schematically illustrating a configuration of the work machine 100 shown in FIG. 1. In FIG. 2, a mechanical power transmission system, a hydraulic oil line, a pilot line, and an electric control system are indicated by double lines, thick solid lines, thick broken lines, and dotted lines, respectively.

[0019] A work machine 100 according to an embodiment of the present disclosure is a hydraulic excavator including a lower traveling body 1, an upper swivel body 3 provided on the lower traveling body 1 so as to be capable of swiveling, an attachment assembly AT provided on the upper swivel body 3, and an actuator for driving these. The work machine 100 is not limited to the hydraulic excavator, and may be a forestry machine, a material-handling recycling machine, a demolition machine for demolishing houses, a specialized machine for civil engineering, logistics, and harbors, and the like.

[0020] The actuator for driving each part of the work machine 100 is, for example, a hydraulic actuator. The hydraulic actuators of the work machine 100 include hydraulic motors such as a left traveling hydraulic motor 2ML, a right traveling hydraulic motor 2MR, a swivel hydraulic motor 2A, and a rotator motor R1. The hydraulic actuators of the work machine 100 include hydraulic cylinders such as a boom cylinder 7, an arm cylinder 8, a bucket cylinder 9, and a tilt actuator T4.

[0021] The actuators for driving the respective parts of the work machine 100 may be electric actuators such as electric motors. That is, the work machine 100 may be a hybrid shovel or an electric shovel in which all or part of driven parts are driven by the electric actuators.

[0022] The lower traveling body 1 includes, for example, a pair of left and right crawlers 1C. Specifically, the crawlers 1C includes a left crawler 1CL and a right crawler 1CR. In the lower traveling body 1, the left crawler 1CL is driven by the left traveling hydraulic motor 2ML, and the right crawler 1CR is driven by the right traveling hydraulic motor 2MR, so that the work machine 100 moves straight, retreats, and turns.

[0023] The upper swivel body 3 is provided so as to be capable of swiveling with respect to the lower traveling body 1 via a swivel mechanism 2 and is driven by the swivel hydraulic motor 2A to slew with respect to the lower traveling body 1. An attachment assembly AT for performing various operations is attached to the front center of the upper swivel body 3. A control cabin 10 in which an operator of the work machine 100 rides is provided on the front left of the upper swivel body 3.

[0024] The front sides of the upper swivel body 3 and the work machine 100 correspond to sides on which the attachment assembly AT is attached to the upper swivel body 3 when the work machine 100 is viewed from directly above along the swivel axis of the upper swivel body 3. The left side, the right side, and the rear side of the work machine 100 and the upper swivel body 3 correspond to the left side, the right side, and the rear side, respectively, as seen from the operator seated in a driver's seat in the control cabin 10.

[0025] The control cabin 10 is also referred to as a cabin or a cab. However, the control cabin 10 may be omitted when the work machine 100 is remotely controlled or when the work machine 100 is operated by fully automatic operation.

[0026] The attachment assembly AT includes a boom 4, an arm 5, and a bucket 6. In the example shown in FIG. 1, the attachment assembly AT includes a tilt rotator TR.

[0027] The boom 4 is coupled to the upper swivel body 3 via a boom foot pin 4f and is provided and configured to be raised and lowered with respect to the upper swivel body 3. The boom 4 is driven by the boom cylinder 7 and is raised and lowered with respect to the upper swivel body 3.

[0028] The arm 5 is coupled to a tip of the boom 4 via a boom top pin 4t and pivotably provided with respect to the boom 4 by rotating with respect to the boom 4. The arm 5 is driven by the arm cylinder 8 and pivots with respect to the boom 4.

[0029] The bucket 6 is an example of an end attachment attached to the tip of the attachment assembly AT and is used for excavation work or the like. Other types of buckets 6, such as large buckets, buckets for slope surfaces, buckets for dredging, and the like, can be selected in accordance with work contents and the like. Further, harvesters, grapples, breakers, cutters, augers, magnets, and the like can be selected as end attachments in accordance with types of work machines 100.

[0030] The end attachment of the bucket 6 and the like is attached to the tip of the arm 5 via the tilt rotator TR. The tilt rotator TR is attached to the tip of the arm 5 via an arm top pin 5t, thereby supporting the end attachment of the bucket 6 and the like pivotably with respect to the arm 5. Specifically, the tilt rotator TR is connected to the bucket cylinder 9 via a link mechanism and is driven by the bucket cylinder 9 to rotate around the arm top pin 5t, thereby pivoting the end attachment of the bucket 6 and the like with respect to the arm 5.

[0031] The tilt rotator TR includes a tilt mechanism T and a rotator R. The end attachment of the bucket 6 and the like is tiltably provided at the tip of the arm 5 via the tilt mechanism T. The end attachment of the bucket 6 and the like is provided so as to be rotatable at the tip of the arm 5 via the rotator R. The work machine 100 need not have the rotator R.

[0032] The tilt mechanism T tilts an end attachment such as the bucket 6 with respect to the arm 5 by rotating the bucket 6 around a tilt shaft T2 substantially orthogonal to the longitudinal direction of the arm 5 and a width direction Dw of the bucket 6. The tilt mechanism T includes, for example, a base T1, a tilt shaft T2, a support plate T3, and a tilt actuator T4.

[0033] The base T1 of the tilt mechanism T is attached to the tip of the arm 5 via an arm top pin 5t. The tilt shaft T2 of the tilt mechanism T is supported by the base T1. The support plate T3 of the tilt mechanism T is pivotably attached to the base T1 via the tilt shaft T2 and supports the bucket 6.

[0034] The tilt actuator T4 includes, for example, hydraulic cylinders arranged on both sides or one side of the tilt shaft T2. When the tilt actuator T4 expands and contracts, the support plate T3 rotates around the tilt shaft T2, and the tilt angle of the bucket 6 supported by the support plate T3 changes. The tilt angle is a rotation angle of the bucket 6 around the tilt shaft T2.

[0035] The rotator R rotates the bucket 6 around a rotation axis substantially parallel to a longitudinal direction D1 of the bucket 6. The rotator R includes, for example, the rotator motor R1, a rotator shaft R2, and a connection part R3.

[0036] The rotator motor R1 of the rotator R is attached to the support plate T3 of the tilt mechanism T. One end of the rotator shaft R2 of the rotator R is connected to a rotating shaft of the rotator motor R1, and the other end is fixed to the connection part R3. The connection part R3 is connected to the end of the bucket 6 opposite to a tooth tip in the longitudinal direction D1 of the bucket 6.

[0037] The longitudinal direction D1 of the bucket 6 is a direction in which a length L of the bucket 6 is measured. The length L of the bucket 6 is, for example, a dimension from the end of the bucket 6 connected to the connection part R3 of the rotator R to the tooth tip of the bucket 6. The width direction Dw of the bucket 6 is a direction in which the width W of the bucket 6 is measured and is a direction orthogonal to the longitudinal direction D1 and a depth direction of the bucket 6.

[0038] When the rotating shaft of the rotator motor R1 is rotated, the rotator shaft R2 connected to the rotating shaft of the rotator motor R1 is rotated, and the connection part R3 fixed to the rotator shaft R2 is rotated. As a result, the bucket 6 connected to the connection part R3 is rotated about the rotating shaft of the rotator motor R1 and the rotator shaft R2.

[0039] The work machine 100 includes a drive system for driving the hydraulic actuator and an operation system for operating the hydraulic actuator. As shown in FIG. 2, the drive system of the work machine 100 includes an engine 11, a regulator 13, a main pump 14, a pilot pump 15, a control valve unit 17, and a discharge pressure sensor 28. The operation system of the work machine 100 includes an operating device 26, an operation sensor 29, a controller 30, and a valve 31.

[0040] The engine 11 is an example of a power source of the work machine 100 and is mounted at the rear of the upper swivel body 3. The power source of the work machine 100 may be a combination of a power source such as a battery or a fuel cell and an electric motor. Specifically, the engine 11 rotates at a predetermined target rotation speed under direct or indirect control by the controller 30 to drive the main pump 14 and the pilot pump 15. The engine 11 is, for example, a diesel engine using diesel fuel. The engine 11 may be a gasoline engine, a hydrogen engine, or the like.

[0041] The regulator 13 controls the discharge amount of the main pump 14. Specifically, the regulator 13 controls the discharge amount of the main pump 14 by adjusting an angle (tilt angle) of a swash plate of the main pump 14 in response to a control command from the controller 30.

[0042] The main pump 14 is mounted at the rear of the upper swivel body 3 in the same manner as the engine 11 and supplies hydraulic oil to the control valve unit 17 through a hydraulic oil line. In the illustrated example, the main pump 14 is a variable displacement hydraulic pump.

[0043] The pilot pump 15 is an example of a pilot pressure generating device and is configured to supply hydraulic oil to the control valve unit 17 through a pilot line. In the illustrated example, the pilot pump 15 is a fixed displacement hydraulic pump. However, the pilot pressure generating device may be achieved by the main pump 14. That is, the main pump 14 may have a function of supplying hydraulic oil to the control valve unit 17 through a pilot line in addition to a function of supplying hydraulic oil to the control valve unit 17 through a hydraulic oil line. In this case, the pilot pump 15 may be omitted.

[0044] The control valve unit 17 is one of hydraulic control devices for controlling a hydraulic system in the work machine 100. In the illustrated example, the control valve unit 17 includes control valves 171 to 178. The control valve unit 17 is configured to selectively supply hydraulic oil discharged from the main pump 14 to one or more hydraulic actuators through the control valves 171 to 178. The control valves 171 to 178 controls the flow rate of the hydraulic oil flowing from the main pump 14 to the hydraulic actuators and the flow rate of the hydraulic oil flowing from the hydraulic actuators to the hydraulic oil tank.

[0045] The discharge pressure sensor 28 is configured to detect the discharge pressure of the main pump 14. In the illustrated example, the discharge pressure sensor 28 outputs the detected value to the controller 30.

[0046] The operating device 26 is a device used by an operator to operate the actuators. The operating device 26 includes, for example, a left operating lever, a right operating lever, a left travel pedal, a right travel pedal, a left travel lever, a right travel lever, a left operating pedal, a left operating switch, and a right operating switch.

[0047] The operation sensor 29 is configured to detect the contents of an operation performed by an operator using the operating device 26. In the present embodiment, the operation sensor 29 detects an operation direction and an operation amount of the operating device 26 corresponding to each of the actuators, and outputs the detected values to the controller 30.

[0048] The controller 30 is configured by a computer including an electronic circuit such as a CPU, an FPGA, and an ASIC, a memory such as a volatile storage device and a nonvolatile storage device, and various input / output interfaces. The controller 30 executes various control operations and achieves various functions by, for example, executing an instruction code or a program stored in the memory by the CPU or the like, or by designing a circuit for a special application.

[0049] The valve 31 is arranged in a conduit connecting the pilot pump 15 and a pilot port of a control valve in the control valve unit 17, and is configured to change a flow path area of the conduit. In the illustrated example, the valve 31 is a solenoid valve that operates in response to a control command output from the controller 30.

[0050] The controller 30 controls an opening area of the valve 31 in response to an output of the operation sensor 29 so as to supply the hydraulic oil discharged from the pilot pump 15 to the pilot port of a corresponding control valve in the control valve unit 17. A pressure (pilot pressure) of the hydraulic oil supplied to the pilot port of each control valve of the control valve unit 17 is a pressure corresponding to the direction and amount of operation of the operating device 26 corresponding to each hydraulic actuator. As described above, an operation system of the work machine 100 is configured to supply the hydraulic oil discharged from the pilot pump 15 to the pilot port of the corresponding control valve in the control valve unit 17.

[0051] For example, when the operator operates the left operating lever of the operating device 26 with the left hand, the controller 30 controls the valve 31 in accordance with the output of the operation sensor 29 and supplies pilot pressure to the control valves 172 and 177, whereby the arm cylinder 8 and the swivel hydraulic motor 2A can be driven. Similarly, when the operator operates the right operating lever of the operating device 26 with the right hand, the controller 30 controls the valve 31 in accordance with the output of the operation sensor 29 and supplies pilot pressure to the control valves 171 and 173, whereby the boom cylinder 7 and the bucket cylinder 9 can be driven.

[0052] Similarly, when the operator operates the left travel pedal of the operating device 26 with the left foot, the controller 30 controls the valve 31 in accordance with the output of the operation sensor 29 and supplies pilot pressure to the control valve 176, whereby the left traveling hydraulic motor 2ML can be driven. Similarly, when the operator operates the right travel pedal of the operating device 26 with the right foot, the controller 30 controls the valve 31 in accordance with the output of the operation sensor 29 and supplies pilot pressure to the control valve 175, whereby the right traveling hydraulic motor 2MR can be driven.

[0053] Furthermore, when the operator operates the left travel lever of the operating device 26 while gripping it with the left hand, the left traveling hydraulic motor 2ML can be driven similarly to the operation via the left travel pedal. When the operator operates the right traveling lever of the operating device 26 while gripping it with his right hand, the right traveling hydraulic motor 2MR can be driven similarly to the operation via the right traveling pedal. The left traveling lever and the right traveling lever of the operating device 26 are arranged so that the operator can simultaneously operate the left traveling lever and the right traveling lever with one hand.

[0054] To tilt the bucket 6 by operating the tilt mechanism T, the operator operates the right operating pedal of the operating device 26 with his right foot or operates a right operation switch provided on the right operating lever of the operating device 26 with his right hand. Then, the controller 30 controls the valve 31 according to the output of the operation sensor 29 to supply pilot pressure to the control valve 174, thereby driving the tilt actuator T4 and tilting the bucket 6.

[0055] To rotate the bucket 6 around the rotator shaft R2 by operating the rotator R, the operator operates the left operating pedal of the operating device 26 with his left foot or operates a left operation switch provided on the left operating lever of the operating device 26 with his left hand. Then, the controller 30 controls the valve 31 according to the output of the operation sensor 29 to supply pilot pressure to the control valve 178, thereby driving the rotator motor R1 and rotating the bucket 6 around the rotator shaft R2.

[0056] The controller 30 is configured to control the work machine 100 by achieving various functions. The various functions of the controller 30 include a machine guidance function for displaying a target surface, a position of the bucket 6, and a distance between the tooth tip of the bucket 6 and the target surface on a display device D1 to guide the manual operation of the work machine 100 by the operator. The various functions of the controller 30 include a machine control function for moving the tooth tip of the bucket 6 along the target surface by controlling the valve 31 and automatically operating the hydraulic actuators in conjunction with each other when the operator operates a specific lever of the operating device 26. That is, the valve 31 functions as a control valve for machine control, and the controller 30 can adjust the pilot pressure acting on the pilot port of the control valve by the valve 31 in response to the operation of the operating device 26 by the operator.

[0057] The various functions of the controller 30 may include a contact avoidance function for automatically or autonomously operating or stopping the work machine 100 in order to avoid contact between the work machine 100 and an object existing within a monitoring range around the work machine 100. The work machine 100 may be configured to be remotely controlled from outside the work machine 100. When the work machine 100 is remotely controlled, the interior of the control cabin 10 may be unattended.

[0058] A part of the functions of the controller 30 may be achieved by another controller. That is, the functions of the controller 30 may be achieved in a distributed manner by a plurality of controllers. For example, the machine guidance function and the machine control function may be achieved by a dedicated controller.

[0059] The work machine 100 includes a tilt sensor S1, a boom sensor S2, an arm sensor S3, a bucket sensor S4, and a vehicle body sensor S5. The work machine 100 also includes an object detection device S6, a positioning device PS, a communication device CD, a display device D1, and an input device D2.

[0060] The tilt sensor S1 is a tilt inertial measurement unit for detecting a tilt angle and a tilt angular velocity of an end attachment such as the bucket 6. Hereinafter, an inertial measurement unit is abbreviated as IMU. The tilt angle and the tilt angular velocity are an angle and an angular velocity of an end attachment such as the bucket 6 rotating around a tilt shaft T2. The tilt angle and the tilt angular velocity of the end attachment such as the bucket 6 detected by the tilt sensor S1 are input to the controller 30.

[0061] The tilt sensor S1 is attached to, for example, a support plate T3 which is attached to the tilt mechanism T so as to be swingable with respect to the base T1 via a tilt shaft T2 and supports the end attachment such as the bucket 6, or to the end attachment such as the bucket 6. The rotation angle and rotation angular velocity, which are the angle and angular velocity of the end attachment driven by the rotator motor R1 and rotated around the rotator shaft R2, can be detected by, for example, an angle sensor such as an encoder. The rotation angle and rotation angular velocity of the end attachment detected by the angle sensor are input to the controller 30.

[0062] The boom sensor S2 is an angular velocity sensor for detecting the boom angle and the boom angular velocity, which are the angle and angular velocity of the boom 4 driven by the boom cylinder 7 and rotated around the boom foot pin 4f. The boom sensor S2 is, for example, a boom IMU attached to an intermediate portion in the longitudinal direction of the boom 4. The boom angle and the boom angular velocity detected by the boom sensor S2 are input to the controller 30.

[0063] The arm sensor S3 is an angular velocity sensor for detecting the arm angle and the arm angular velocity, which are the angle and angular velocity of the arm 5 driven by the arm cylinder 8 and pivotably rotated around the boom top pin 4t. The arm sensor S3 is, for example, an arm IMU attached to an intermediate portion in the longitudinal direction of the arm 5. The arm angle and the arm angular velocity detected by the arm sensor S3 are input to the controller 30.

[0064] The bucket sensor S4 is an angular velocity sensor for detecting the bucket angle and the bucket angular velocity which are the angle and the angular velocity of the end attachment such as the bucket 6 which is driven via the bucket cylinder 9 and the link mechanism and pivotably rotates around the arm top pin 5t. The bucket sensor S4 is a bucket IMU attached to the link mechanism for pivoting the end attachment such as the bucket 6 with respect to the arm 5. The link mechanism is provided with a plurality of links rotatably connected to the tip of a piston rod of the bucket cylinder 9, the tip of the arm 5, and the end attachment such as the bucket 6. The bucket angle and the bucket angular velocity detected by the bucket sensor S4 are input to the controller 30.

[0065] The vehicle body sensor S5 is a vehicle body IMU for detecting the swivel angle and the swivel angular velocity of the upper swivel body 3 driven by the swivel hydraulic motor 2A and swiveling with respect to the lower traveling body 1 via the swivel mechanism 2. The vehicle body sensor S5 detects an inclination angle and an inclination angular velocity of the upper swivel body 3 with respect to the horizontal plane. The vehicle body sensor S5 may detect the swivel angular velocity and the vehicle body angular velocity including the swivel angular velocity. The vehicle body sensor S5 is mounted, for example, on a floor of the control cabin 10 provided on the upper swivel body 3. The swivel angle, swivel angular velocity, inclination angle, and inclination angular velocity of the upper swivel body 3 detected by the vehicle body sensor S5 are input to the controller 30.

[0066] Note that the boom sensor S2, the arm sensor S3, the bucket sensor S4, and the vehicle body sensor S5 are not necessarily IMUs as long as they are sensors capable of detecting the angular velocity of the boom 4, the arm 5, the bucket 6, and the upper swivel body 3. Specifically, these sensors may be angle sensors or acceleration sensors. The boom sensor S2, the arm sensor S3, and the bucket sensor S4 may be cylinder stroke sensors for detecting a stroke amount of a hydraulic cylinder.

[0067] The object detection device S6 is attached to the upper swivel body 3 and detects objects around the work machine 100. The objects are, for example, the ground, a work object, a person, a vehicle, a construction machine, a building, and the like. The object detection device S6 may be configured to distinguish and detect a person from objects other than a person. That is, the object detection device S6 may be configured to function as a person detection device.

[0068] The object detection device S6 is provided in the upper swivel body 3 or the control cabin 10. The object detection device S6 includes an imaging device for imaging the surroundings around the work machine 100 and acquiring image information representing the surroundings around the work machine 100. In the illustrated example, the imaging device includes a front camera S6F, a left camera S6L, a right camera S6R, and a rear camera S6B.

[0069] The front camera S6F is a camera for imaging the front of the work machine 100 and is attached to the outside of the control cabin 10 such as a roof of the control cabin 10 and the side surface of the boom 4. The front camera S6F may be attached to the inside of the control cabin 10 such as a ceiling of the control cabin 10. The left camera S6L is a camera for imaging the left side of the work machine 100. The right camera S6R is a camera for imaging the right side of the work machine 100. The rear camera S6B is a camera for imaging the right side of the work machine 100. Specifically, the front camera S6F, the left camera S6L, the right camera S6R, and the rear camera S6B are all monocular wide-angle cameras equipped with an image sensor such as a CCD or CMOS, and output the captured image to the display device D1 (see FIG. 2). Information on the object detected by the object detection device S6 including the imaging device is input to the controller 30.

[0070] In the illustrated example, the front camera S6F is attached to the roof of the control cabin 10. The left camera S6L is attached to the left end of the upper surface of the upper swivel body 3. The right camera S6R is attached to the right end of the upper surface of the upper swivel body 3. The rear camera S6B is attached to the rear end of the upper surface of the upper swivel body 3.

[0071] The object detection device S6 may be composed of a device other than a camera. For example, the object detection device S6 may be a LiDAR. The LiDAR is a device capable of measuring, for example, a distance between a point group of one million or more points within a monitoring range and a LiDAR (laser source). The object detection device S6 may be another device capable of measuring a distance between the object and the object, such as a stereo camera, a range image camera, or a millimeter-wave radar.

[0072] When a millimeter-wave radar or the like is used as the object detection device S6, the object detection device S6 may transmit a large number of signals (laser beams or the like) toward the object and receive the reflected signals, thereby deriving the distance and direction of the object. The object detection device S6 may be a combination of 2 or more types of devices. For example, the object detection device S6 may be a combination of an imaging device and a lidar, a combination of an imaging device and a millimeter-wave radar, or a combination of an imaging device and a stereo camera.

[0073] The positioning device PS measures the position of the upper swivel body 3. The positioning device PS is, for example, a GNSS (Global Navigation Satellite System) compass, and detects the position and direction of the upper swivel body 3. A detection signal corresponding to the position and orientation of the upper swivel body 3 is input to the controller 30. The function of detecting the orientation of the upper swivel body 3 may be achieved by an orientation sensor attached to the upper swivel body 3.

[0074] The communication device CD communicates with an external device through a communication network including a mobile communication network, a satellite communication network, an Internet network, or the like. The communication device CD is, for example, a mobile communication module corresponding to a mobile communication standard such as LTE (Long Term Evolution), 4G (4th Generation), or 5G (5th Generation). The communication device CD is a communication module corresponding to a short-range wireless communication standard such as Wi-Fi (registered trademark) or Bluetooth (registered trademark), or a satellite communication module for connecting to a satellite communication network.

[0075] The display device D1 is an example of a user interface device. The display device D1 is provided in the control cabin 10 at a place easily visible to a seated operator, and displays various information images under the control of the controller 30. Specifically, the display device D1 is disposed in front of the driver's seat in the control cabin 10 on the right side, and is connected to the controller 30 via a dedicated line. The operator seated in the driver's seat can perform work using the work machine 100 while confirming various information displayed on the display device D1. The display device D1 may be provided with the input device D2.

[0076] The input device D2 is an example of a user interface device. The input device D2 is provided within reach of the operator seated in the driver's seat in the control cabin 10, receives various operation inputs from the operator, and outputs a signal corresponding to the operation inputs to the controller 30. The input device D2 includes a touch panel mounted on the display of the display device D1 for displaying various information images, a knob switch provided at the tip of one or more of the operating levers included in the operating device 26, or a button switch, lever, toggle switch, rotary dial, or the like provided around the display device D1. A signal corresponding to the content of the operation on the input device D2 is received by the controller 30.

[0077] FIG. 3 is a functional block diagram illustrating the machine control function and the machine guidance function of the controller 30 shown in FIG. 2. Hereinafter, “machine control” is abbreviated as “MC” and “machine guidance” is abbreviated as “MG”.

[0078] For example, as shown in FIG. 3, the controller 30 includes an MC / MG calculation part 301, an operation amount acquisition part 302, a detection result acquisition part 303, a mode switching part 304, an operation amount calculation part 305, and an operation control part 306. Each unit of the controller 30 shown in FIG. 3 represents each function of the controller 30 achieved by the CPU of the controller 30 reading a program stored in a nonvolatile storage device, loading the program into the volatile storage device, and executing the program.

[0079] The MC / MG calculation part 301 acquires, for example, operation contents by the operator from the input device D2, and determines whether or not the operator has switched the manual control mode of the work machine 100 to the MC mode or the MG mode. In the manual control mode, the operator operates the operating device 26 to manually control the work machine 100.

[0080] In the MC mode, the controller 30 controls the work machine 100 to form a design surface based on the position and shape of the design surface to be executed, the position and attitude of the work machine 100, and the amount of operation of the operating device 26.

[0081] In the MG mode, the target surface, the position of the bucket 6, and the distance between the tooth tip of the bucket 6 and the target surface are displayed on the display device D1 to guide the manual operation of the work machine 100 by the operator. The control mode of the controller 30 may include an automatic control mode in addition to the MC and MG modes. The automatic control mode is a mode in which the controller 30 automatically controls the work machine 100 based on the current position and shape of the work object, the position and shape of the design surface of the work object, and the position and attitude of the work machine 100 to automatically excavate the excavation object and form the design surface.

[0082] The MC / MG calculation part 301 acquires information about the target surface input to the controller 30 via the input device D2. The information about the target surface may be acquired by downloading the information from an external server by the MC / MG calculation part 301 and acquired, for example. The target surface is, for example, a surface to be a target when excavating a ground surface to be the work surface in the ground leveling work or slope improvement work by the work machine 100. That is, the target surface is, for example, a flat surface or a slope surface formed by excavating the work surface by the bucket 6. The target surface may be, for example, a curved surface or a surface having predetermined irregularities.

[0083] Information on the target surface is expressed, for example, in a reference coordinate system. The reference coordinate system is, for example, a World Geodetic System. The World Geodetic System is a three-dimensional orthogonal XYZ coordinate system in which the origin is located at the center of the Earth, the X-axis extends toward the intersection of the Greenwich meridian and the equator, the Y-axis extends toward 90 degrees east longitude, and the Z-axis extends toward the North Pole. The operator sets, for example, any point on the construction site as a reference point via the input device D2, and sets a target surface based on the relative positional relationship with the reference point.

[0084] Further, the MC / MG calculation part301 sets a target path of a control reference for moving the control reference of the attachment assembly AT along the target surface based on the acquired information on the target surface. As the control reference of the attachment assembly AT, for example, a tooth tip or a back surface of the bucket 6 as an end attachment attached to the tip of the attachment assembly AT is set.

[0085] The operation amount acquisition part 302 acquires the operation amount of the operating device 26 by the operator detected by the operation sensor 29. The operation amount of the operating device 26 includes, for example, the operation amount and operation direction related to the rotation of the left crawler 1CL and the right crawler 1CR by the left traveling hydraulic motor 2ML and the right traveling hydraulic motor 2MR, the swiveling of the upper swivel body 3 by the swivel hydraulic motor 2A of the swivel mechanism 2, and the operation of the attachment assembly AT.

[0086] The amount and direction of operation of the attachment assembly AT include, for example, the amount and direction of operation of the boom 4 by the boom cylinder 7, pivoting of the arm 5 by the arm cylinder 8, and pivoting of the bucket 6 by the bucket cylinder 9. The amount and direction of operation of the attachment assembly AT include the amount and direction of operation of tilting of the bucket 6 by the tilt actuator T4 and rotating of the bucket 6 by the rotator motor R1.

[0087] The detection result acquisition part 303 acquires the detection results of the tilt sensor S1, the boom sensor S2, the arm sensor S3, the bucket sensor S4, the vehicle body sensor S5, and the object detection device S6. Specifically, the detection result acquisition part 303 acquires the tilt angle and the tilt angular velocity of the bucket 6, which is an end attachment, from the tilt sensor S1, which is a tilt IMU.

[0088] The detection result acquisition part 303 acquires the detection results from the boom sensor S2, the arm sensor S3, and the bucket sensor S4. As described above, the boom sensor S2, the arm sensor S3, and the bucket sensor S4 are angular velocity sensors for detecting the angular velocities of the boom 4, the arm 5, and the bucket 6, respectively, and can employ an IMU.

[0089] That is, the detection result acquisition part 303 acquires the boom angular velocity, the arm angular velocity, and the bucket angular velocity from the boom sensor S2, the arm sensor S3, and the bucket sensor S4, and can calculate the boom angle, the arm angle, and the bucket angle. The detection result acquisition part 303 acquires the swivel angular velocity of the upper swivel body 3 from the vehicle body sensor S5, and can calculate the swivel angle of the upper swivel body 3. The detection result acquisition part 303 acquires the inclination angle of the upper swivel body 3 with respect to the horizontal plane from the vehicle body sensor S5. Thus, the detection result acquisition part 303 can acquire information about the current attitude of the attachment assembly AT. The detection result acquisition part 303 acquires the detection result of an object existing around the work machine 100, including the shape and position of the work object, from the object detection device S6.

[0090] The mode switching part 304 switches between a detection mode and an estimation mode according to the attitude of the attachment assembly AT. In the detection mode, the tilt angle of the bucket 6 as the end attachment is detected by the tilt sensor S1. In the estimation mode, the tilt angle of the bucket 6 is estimated from the detection result of the tilt angular velocity of the bucket 6 by the tilt sensor S1 and the detection result of the boom angular velocity, the arm angular velocity, and the bucket angular velocity by the angular velocity sensor. The tilt angle of the bucket 6 may be estimated by using the detection result of the swivel angular velocity of the upper swivel body 3 by the angular velocity sensor or the IMU.

[0091] FIG. 4 is a side view illustrating an example of an excavation operation of the attachment assembly AT of the work machine 100. For example, when the earth and sand SO to be executed is excavated by the attachment assembly AT of the work machine 100 to form a slope SL as a design surface, the angle of each part of the attachment assembly AT including the bucket 6 as an end attachment changes from moment to moment.

[0092] As shown in enlarged views A and B of FIG. 4, the tilt sensor S1, which is an IMU, detects acceleration in the respective axial directions of the X-axis, the Y-axis, and the Z-axis orthogonal to each other and angular velocity around each axis. Here, the X-axis direction of the tilt sensor S1 is a direction along the longitudinal direction D1 of the bucket 6. The Y-axis direction of the tilt sensor S1 is a direction substantially parallel to the width direction Dw of the bucket 6. The Z-axis direction of the tilt sensor S1 is a direction substantially parallel to an axial direction Dt of the tilt shaft T2.

[0093] Therefore, when the axial direction Dt of the tilt shaft T2 has a predetermined angle with respect to the vertical direction as shown in the upper portion of FIG. 4, the Z-axis direction of the tilt sensor S1 does not coincide with the direction of the gravitational acceleration g as shown in the enlarged view A. In this case, the tilt angle=arctan (ay / ax), which is the angle of the bucket 6 rotating about the tilt shaft T2, can be calculated based on the detected values ay and ax of the acceleration of the tilt sensor S1 in the X-axis direction and the Y-axis direction.

[0094] However, as shown in the lower portion of FIG. 4, when the axial direction Dt of the tilt shaft T2 approaches the vertical direction, the direction of the Z-axis of the tilt sensor S1 substantially coincides with the direction of the gravitational acceleration g, so that the tilt angle cannot be detected by the tilt sensor S1. This is because the X-axis and Y-axis of the tilt sensor S1 become substantially horizontal, so that the tilt angle=arctan(ay / ax), based on the detected values ay and ax of the acceleration in the X-axis direction and Y-axis direction of the tilt sensor S1 cannot be calculated.

[0095] Therefore, when the tilt shaft T2 of the bucket 6 serving as the end attachment is along the vertical direction, the mode switching part 304 switches the detection mode in which the tilt angle is detected by the tilt sensor S1 to the estimation mode in which the tilt angle is estimated. The mode switching part 304 can set, for example, whether or not to switch from the detection mode to the estimation mode via a user interface device such as the input device D2. Further, the mode switching part 304 may notify a user including an operator that the estimation mode is being executed via a user interface device such as the display device D1.

[0096] FIGS. 5 and 6 are graphs illustrating examples of switching modes M with the mode switching part 304.

[0097] In the graph of FIG. 5, the vertical axis represents the mode M, which is switched to a detection mode Md or an estimation mode Me with the mode switching part 304. In the graph of FIG. 5, the horizontal axis represents acceleration az in the Z-axis direction detected by the tilt sensor S1 which is the tilt IMU.

[0098] In the upper graph of FIG. 6, the vertical axis represents the acceleration az in the Z-axis direction detected by the tilt sensor S1, and the horizontal axis represents the time t. In the lower graph of FIG. 6, the vertical axis represents the mode M switched by the mode switching part 304 as in FIG. 5, and the horizontal axis represents the time t as in the upper graph of FIG. 6.

[0099] In the example shown in FIG. 5, the mode switching part 304 switches the detection mode Md to the estimation mode Me when the detection result of the acceleration az in the Z-axis direction of the tilt sensor S1 parallel to the tilt shaft T2 is greater than a first threshold value az1, which is smaller than the gravitational acceleration g. The first threshold value az1 is set according to the noise and resolution of the detection value of the tilt sensor S1 and can be set to approximately 9.4 m / s2, for example.

[0100] The value of the first threshold value az1 corresponds to the detection result of the acceleration az in the Z-axis direction of the tilt sensor S1 when the angle of the Z-axis of the tilt sensor S1 with respect to the vertical direction, that is, the angle of the tilt shaft T2 with respect to the vertical direction is approximately 16.6 deg. The mode switching part 304 may use the angle of the tilt shaft T2 with respect to the vertical direction as a threshold value for switching between the detection mode Md and the estimation mode Me.

[0101] Further, in the example shown in FIG. 5, the mode switching part 304 may switch from the estimation mode Me to the detection mode Md when the detection result of the acceleration az in the Z-axis direction of the tilt sensor S1 parallel to the tilt shaft T2 is smaller than a second threshold value az2, which is smaller than the first threshold value az1. The second threshold value az2 is determined according to a variation in the detected value of the acceleration az in the Z-axis direction of the tilt sensor S1 caused by, for example, vibration of the attachment assembly AT.

[0102] Specifically, when the detected value of the acceleration az in the Z-axis direction of the tilt sensor S1 varies within a range of approximately 0.2 m / s2 due to vibration of the attachment assembly AT, the second threshold value az2 is set to a value approximately 0.2 m / s2 lower than the first threshold value az1.

[0103] Further, as shown in FIG. 6, the mode switching part 304 may switch from the estimation mode Me to the detection mode Md when the detection result of the acceleration az in the Z-axis direction of the tilt sensor S1 parallel to the tilt shaft T2 remains smaller than the second threshold value az2 for a predetermined duration t1.

[0104] In the example shown in FIG. 6, in the estimation mode Me, the detected value of the acceleration az in the Z-axis direction of the tilt sensor S1 temporarily changes from the acceleration az3 larger than the second threshold value az2 to the acceleration az4 smaller than the second threshold value az2. However, when the detected value of the acceleration az in the Z-axis direction of the tilt sensor S1 returns to the acceleration az3 larger than the second threshold value az2 without elapsing a predetermined duration t1, the mode switching part 304 does not switch from the estimation mode Me to the detection mode Md.

[0105] Thereafter, when the detected value of the acceleration az in the Z-axis direction of the tilt sensor S1 changes again to the acceleration az4 smaller than the second threshold value az2 and the predetermined duration t1 elapses as it is, the mode switching part 304 switches the estimation mode Me to the detection mode Md. The mode switching part 304 may switch from the detection mode Md to the estimation mode Me when the detected result of the acceleration az in the Z-axis direction of the tilt sensor S1 parallel to the tilt shaft T2 exceeds the first threshold value az1 for a predetermined duration.

[0106] In the manual operation mode, the operation amount calculation part 305 shown in FIG. 3 calculates the operation amount of the actuator of the work machine 100 based on the operation amount of the operating device 26 by the operator acquired by the operation amount acquisition part 302. In the MC mode, the operation amount calculation part 305 calculates the operation amount of the actuator of the work machine 100 based on the target path of the control reference of the attachment assembly AT set by the MC / MG calculation part 301 and the current attitude of the attachment assembly AT. In the MG mode, the operation amount calculation part 305 calculates the operation amount of the actuator of the work machine 100 based on the target path of the control reference of the attachment assembly AT, the current attitude of the attachment assembly AT, and the operation amount of the operating device 26 by the operator.

[0107] FIG. 7 is a block diagram illustrating an example of a method of calculating an operation amount with the operation amount calculation part 305. With reference to FIG. 7, a method of calculating the operating amount of the tilt actuator T4 will be described as an example.

[0108] The operation amount calculation part 305 changes the method of calculating the operating amount of the tilt actuator T4 according to the mode M switched by the mode switching part 304. Specifically, the operation amount calculation part 305 calculates the operating amount Qt of the tilt actuator T4 using the tilt angle θtd detected by the tilt sensor S1 in the detection mode Md. More specifically, the operation amount calculation part 305 includes a control unit 305a and a converter 305b.

[0109] The control unit 305a calculates the target tilt angular velocity ωtt based on the difference between the target tilt angle θtt and the tilt angle θtd detected by the tilt sensor S1. The converter 305b converts the target tilt angular velocity ωtt into the operating amount Qt of the tilt actuator T4 based on the relationship between the tilt angular velocity and the operating amount Qt. In the example shown in FIG. 7, the difference between the target tilt angular velocity ωtt and the tilt angular velocity ωtd detected by the tilt sensor S1 is added to the target tilt angular velocity ωtt and input to the converter 305b.

[0110] In the estimation mode Me, instead of the tilt angle θtd used in the detection mode Md, the operation amount calculation part 305 calculates the operating amount Qt by using the tilt angle θte estimated based on the angular velocity of each part of the work machine 100 in the same manner as in the detection mode Md. Specifically, the operation amount calculation part 305 estimates the tilt angle θte by the following equations (1) and (2).θte=θt0+Σωte·Δt  (1)ωte=ωtd−R1·ωbm−R2·ωam−R3·ωbu−R4·ωs  (2)In the above equation (1), θt0 is the tilt angle detected by the tilt sensor S1 immediately before switching from the detection mode Md to the estimation mode Me, and ωte is the tilt angular velocity estimated by the equation (2). In the above equation (2), R1, R2, R3, and R4 are rotation matrices in the tilt direction, and ωbm, ωam, ωbu, and ωs are the boom angular velocity, the arm angular velocity, the bucket angular velocity, and the vehicle body angular velocity, respectively.

[0112] The boom angular velocity ωbm, the arm angular velocity ωam, the bucket angular velocity ωbu, and the vehicle body angular velocity ωs are detected by the boom sensor S2, the arm sensor S3, the bucket sensor S4, and the vehicle body sensor S5, which are IMUs including angular velocity sensors, respectively. When the upper swivel body 3 is not swiveled, the tilt angular velocity ωte can be estimated without using the vehicle body angular velocity ωs.

[0113] In addition, the operation amount calculation part 305 can calculate the operation amounts of the boom cylinder 7, the arm cylinder 8, the bucket cylinder 9, and the swivel hydraulic motor 2A in the same manner as the operating amount Qt of the tilt actuator T4 shown in FIG. 7 by using the detection results of the respective sensors.

[0114] The operation control part 306 shown in FIG. 3 operates the actuators of the work machine 100 based on the operation amounts of the actuators of the work machine 100 calculated by the operation amount calculation part 305. Specifically, the operation control part 306 controls the valve 31 based on the operation amounts of the tilt actuator T4, the rotator motor R1, the boom cylinder 7, the arm cylinder 8, the bucket cylinder 9, and the swivel hydraulic motor 2A calculated by the operation amount calculation part 305. Thus, the operation control part 306 can operate the actuators of the work machine 100 based on the operation amounts calculated by the operation amount calculation part 305.

[0115] FIG. 8 is a flow diagram illustrating an embodiment of a method of controlling the work machine according to the present disclosure. When the operator of the work machine 100 presses an MC switch included in the operating device 26 and inputs an instruction for starting the MC to the controller 30, the controller 30 starts the processing flow of a work machine control method CM shown in FIG. 8. First, the controller 30 executes a process P1 for determining whether or not the tilt shaft T2 of the attachment assembly AT is aligned in the vertical direction.

[0116] In this process P1, the mode switching part 304 of the controller 30 acquires the acceleration az of the tilt sensor S1 in the Z-axis direction via the detection result acquisition part 303. For example, as shown in the upper side of FIG. 4, when the angle difference between the axial direction Dt of the tilt shaft T2 and the vertical direction is sufficiently large, the detection result of the acceleration az of the tilt sensor S1 substantially parallel to the tilt shaft T2 in the Z-axis direction falls below the first threshold value az1 shown in FIG. 5. In this case, the mode switching part 304 determines that the tilt shaft T2 is not aligned in the vertical direction (NO), and executes a process P2 for setting the mode M of the controller 30 to the detection mode Md.

[0117] Next, the controller 30 executes MC in a process P3. Here, the controller 30 is set to the detection mode Md. Therefore, the operation amount calculation part 305 calculates the operation amount of each actuator using the tilt angle θtd, bucket angle, arm angle, boom angle, and the like acquired from each sensor via the detection result acquisition part 303. Further, the operation control part 306 controls the valve 31 according to the operation amount of each actuator acquired from the operation amount calculation part 305 to operate each actuator.

[0118] Thus, in the MC mode, the controller 30 automatically executes the operation of forming the slope SL as shown in FIG. 4 in response to the operation of the specific lever by the operator OP. Thereafter, the controller 30 executes the process P4 for determining whether or not to terminate the MC.

[0119] In the process P4, the operation amount calculation part 305 of the controller 30 determines whether or not to terminate the MC according to, for example, the pressed state of the MC switch included in the operating device 26. Specifically, the operation amount calculation part 305 determines whether to continue the MC (NO) when the MC switch is pressed, and determines whether to terminate the MC (YES) when the MC switch is not pressed. When the operation amount calculation part 305 determines that the MC is to be terminated (YES), the controller 30 terminates the process flow shown in FIG. 8. Conversely, when the operation amount calculation part 305 determines that the MC is to be continued (NO), the controller 30 executes the process P1 again.

[0120] Further, as shown in the lower portion of FIG. 4, when the angular difference between the axial direction Dt of the tilt shaft T2 and the vertical direction falls below a predetermined range, the detection result of the acceleration az in the Z-axis direction of the tilt sensor S1 substantially parallel to the tilt shaft T2 exceeds the first threshold value az1 shown in FIG. 5. Then, in process P1, the mode switching part 304 determines that the tilt shaft T2 is along the vertical direction (YES), and executes process P5 for setting the mode M of the controller 30 to the estimation mode Me.

[0121] Thereafter, in the next process P3, the controller 30 executes MC. Here, the controller 30 is set to the estimation mode Me. Therefore, the operation amount calculation part 305 acquires the tilt angular velocity ωtd, the boom angular velocity @bm, the arm angular velocity ωam, the bucket angular velocity ωbu, and the like detected by each sensor via the detection result acquisition part 303.

[0122] Further, the operation amount calculation part 305 estimates the tilt angle θte based on the aforementioned equations (1) and (2). Further, the operation amount calculation part 305 acquires the boom angle, the arm angle, the bucket angle, and the like detected by each sensor via the detection result acquisition part 303. The operation amount calculation part 305 may calculate the boom angle, the arm angle, the bucket angle, and the like from the boom angular velocity ωbm, the arm angular velocity ωam, the bucket angular velocity ωbu, and the like acquired via the detection result acquisition part 303.

[0123] Thereafter, as shown in FIG. 7, the operation amount calculation part 305 calculates the operating amount Qt of the tilt actuator T4 based on the estimated tilt angle θte and the tilt angular velocity ωtd detected by the tilt sensor S1. Further, the operation amount calculation part 305 similarly calculates the operating amounts of the boom cylinder 7, the arm cylinder 8, the bucket cylinder 9, and the swivel hydraulic motor 2A. Further, the operation control part 306 controls the valve 31 based on the operating amount calculated by the operation amount calculation part 305 to drive the boom cylinder 7, the arm cylinder 8, the bucket cylinder 9, and the swivel hydraulic motor 2A.

[0124] Thereafter, the controller 30 repeatedly executes the process P4, the process P1, either the process P2 or the process P5, and the process P3 until the operation amount calculation part 305 determines that the operation has been completed (YES) in the process P4 to complete the operation.

[0125] Hereinafter, the operation of the work machine 100 and the work machine control method CM of the present embodiment will be described.

[0126] As described above, the work machine 100 according to the present embodiment includes the lower traveling body 1, the upper swivel body 3 provided on the lower traveling body 1 so as to be capable of swiveling, and an attachment assembly AT. The attachment assembly AT includes the boom 4 coupled to the upper swivel body 3 and configured to be raised and lowered, the arm 5 pivotably coupled to the boom 4, and an end attachment such as the bucket 6 pivotably and tiltably coupled to the arm 5. The work machine 100 also includes a tilt sensor S1 as a tilt inertial measurement unit, a boom sensor S2, an arm sensor S3, and a bucket sensor S4 as angular velocity sensors, and the controller 30. The tilt inertial measurement unit detects a tilt angle θtd and a tilt angular velocity ωtd of the end attachment. The angular velocity sensor detects angular velocities ωbm, ωam, and ωbu of the boom 4, the arm 5, and the end attachment. The controller 30 controls the operation of the attachment assembly AT based on the detection results of the tilt inertial measurement unit and the angular velocity sensor, and switches between the detection mode Md and the estimation mode Me according to the attitude of the attachment assembly AT. The detection mode Md is a mode M for detecting the tilt angle θtd by the tilt inertial measurement unit. The estimation mode Me is a mode M for estimating the tilt angle θte from the detection results of the tilt angular velocity ωtd by the tilt inertial measurement unit and the angular velocities ωbm, ωam, and ωbu by the angular velocity sensor.

[0127] With this configuration, the work machine 100 of the present embodiment can detect the tilt angle θtd of the end attachment such as the bucket 6 by the tilt sensor S1, which is an inertial measurement unit, and control the operation of the attachment assembly AT.

[0128] Further, in the work machine 100 of the present embodiment, the controller 30 switches the detection mode Md to the estimation mode Me when the tilt shaft T2 of the end attachment such as the bucket 6 is along the vertical direction.

[0129] According to the work machine 100 of the present embodiment, even if the tilt angle θtd cannot be detected by the tilt sensor S1, the MC / MG can be continued by controlling the tilt angle of the end attachment such as the bucket 6 using the estimated tilt angle θte. More specifically, when the axial direction Dt of the tilt shaft T2 is aligned with the vertical direction by the attitude of the attachment assembly AT as shown in the lower side of FIG. 4, the Z-axis of the tilt sensor S1 which is substantially parallel to the tilt shaft T2 is also aligned with the vertical direction. Then, the tilt sensor S1 which is the tilt inertial measurement unit cannot detect the tilt angle θtd.

[0130] Even in such a case, the controller 30 can acquire the detection result of the tilt angular velocity ωtd from the tilt sensor S1. The controller 30 can acquire the boom angular velocity ωbm, the arm angular velocity ωam, and the bucket angular velocity ωbu from the boom sensor S2, the arm sensor S3, and the bucket sensor S4 which are the angular velocity sensors. Furthermore, the controller 30 can estimate the tilt angle θte based on the acquired tilt angular velocity ωtd, boom angular velocity ωbm, arm angular velocity ωam, and bucket angular velocity ωbu.

[0131] Thus, the controller 30 can control the tilt angle of the end attachment such as the bucket 6 by using the estimated tilt angle θte, and MC and MG can be continued. Therefore, according to the work machine 100 of the present embodiment, when MC including tilt angle control is performed by using the tilt inertial measurement unit for detecting the tilt angle of the end attachment such as the bucket 6, MC can be prevented from being stopped because of the attitude of the attachment assembly AT. When the upper swivel body 3 is swiveled, the controller 30 can estimate the tilt angle θte by using the vehicle body angular velocity ωs acquired from the vehicle body sensor S5 which is an angle sensor.

[0132] In the work machine 100 of the present embodiment, the axial direction of the tilt inertial measurement unit parallel to the tilt shaft T2 is the Z-axis direction of the tilt sensor S1. The controller 30 switches the detection mode Md to the estimation mode Me when the detection result of the acceleration az in the Z-axis direction of the tilt sensor S1 exceeds the first threshold value az1 which is smaller than the gravitational acceleration g. The controller 30 switches the estimation mode Me to the detection mode Md when the detection result of the acceleration az in the Z-axis direction of the tilt sensor S1 falls below the second threshold value az2 which is smaller than the first threshold value az1.

[0133] With such a configuration, chattering in which the detection mode Md and the estimation mode Me are frequently switched due to vibration of the attachment assembly AT and noise to the tilt sensor S1 can be suppressed. More specifically, when the tilt shaft T2 approaches the vertical direction and the detection result of the acceleration az in the Z-axis direction of the tilt sensor S1 exceeds the first threshold value az1, the detection mode Md is switched to the estimation mode Me. Thereafter, the detection result of the acceleration az in the Z-axis direction of the tilt sensor S1 may fall below the first threshold value az1 due to vibration or noise of the attachment assembly AT. Even in such a case, by setting the second threshold value az2 in consideration of the influence of vibration or noise of the attachment assembly AT, it is possible to prevent the estimation mode Me from being erroneously switched to the detection mode Md.

[0134] Further, in the work machine 100 of the present embodiment, the Z-axis direction of the tilt sensor S1 is the axial direction of the tilt inertial measurement unit parallel to the tilt shaft T2. When the detection result of the acceleration az in the Z-axis direction of the tilt sensor S1 falls below the second threshold value az2 for a predetermined duration t1, the controller 30 switches the estimation mode Me to the detection mode Md.

[0135] With such a configuration, it is possible to suppress chattering in which the detection mode Md and the estimation mode Me are frequently switched due to vibration of the attachment assembly AT or noise to the tilt sensor S1. More specifically, when the tilt shaft T2 approaches the vertical direction and the detection result of the acceleration az in the Z-axis direction of the tilt sensor S1 exceeds the first threshold value az1, the detection mode Md is switched to the estimation mode Me. Thereafter, the detection result of the acceleration az in the Z-axis direction of the tilt sensor S1 may fall below the second threshold value az2 for a short time or instantaneously due to vibration of the attachment assembly AT or noise. Even in such a case, the estimation mode Me can be prevented from being erroneously switched to the detection mode Md by setting the duration t1 in consideration of the influence of vibration and noise of the attachment assembly AT.

[0136] Further, in the work machine 100 of the present embodiment, the controller 30 can set whether the detection mode Md can be switched to the estimation mode Me via a user interface device such as the input device D2.

[0137] With this configuration, an operator who does not want the controller 30 to estimate the tilt angle θte can select a setting not permitting the switching from the detection mode Md to the estimation mode Me via a user interface device such as the input device D2. Thus, it is possible to switch the work machine 100 to the manual control mode by avoiding the estimation mode Me, which may lower the accuracy of the MC / MG as compared with the detection mode Md.

[0138] Further, in the work machine 100 of the present embodiment, the controller 30 notifies a user such as an operator via a user interface device such as the display device D1 that the estimation mode Me is being executed.

[0139] With this configuration, a user such as an operator of the work machine 100 can recognize that the controller 30 is executing the estimation mode Me via a user interface device such as the display device D1, a speaker, and a display lamp. This makes it possible to alert a user, such as an operator, in the estimation mode Me in which the accuracy of the MC / MG may be lower than that of the detection mode Md.

[0140] In the work machine 100 of the present embodiment, an angular velocity sensor for detecting the angular velocities of the boom 4, the arm 5, and the end attachments such as the bucket 6 is an inertial measurement unit (IMU).

[0141] With this configuration, the boom sensor S2, the arm sensor S3, and the bucket sensor S4, which are IMUs, can detect the accelerations in the directions of three axes orthogonal to each other and the angular velocities around the respective axes.

[0142] The work machine control method CM of the present embodiment is a method for controlling the work machine 100 described above. As described above, the work machine 100 includes the lower traveling body 1, the upper swivel body 3 pivotably provided on the lower traveling body 1, an attachment assembly AT, a tilt inertial measurement unit, and an angular velocity sensor. The attachment assembly AT includes the boom 4 coupled to the upper swivel body 3 and configured to be raised and lowered, the arm 5 pivotably coupled to the boom 4, and an end attachment such as the bucket 6 pivotably and tiltably coupled to the arm 5. The tilt inertial measurement unit includes a tilt sensor S1 for detecting a tilt angle θtd and a tilt angular velocity ωtd of the end attachment such as the bucket 6. The angular velocity sensor includes a boom sensor S2, an arm sensor S3, and a bucket sensor S4 for detecting the angular velocity of an end attachment such as the boom 4, the arm 5, and the bucket 6. The work machine control method CM of the present embodiment switches between the detection mode Md and the estimation mode Me according to the attitude of the attachment assembly AT when controlling the operation of the attachment assembly AT based on the detection results of the tilt inertial measurement unit and the angular velocity sensor. The detection mode Md is a mode for detecting the tilt angle θtd by the tilt inertial measurement unit. The estimation mode Me is a mode for estimating the tilt angle θte from the detection results of the tilt angular velocity ωtd by the tilt inertial measurement unit and the angular velocities ωbm, ωam, and ωbu by the angular velocity sensor.

[0143] With this configuration, according to the present embodiment, it is possible to provide a work machine control method CM for controlling the operation of the attachment assembly AT by detecting the tilt angle of the end attachment such as the bucket 6 by the tilt sensor S1 which is an inertial measurement unit.

[0144] As described above, according to the present embodiment, it is possible to provide the work machine 100 and a work machine control method CM for controlling the operation of the attachment assembly AT by detecting the tilt angle of the end attachment such as the bucket 6 by the tilt sensor S1 which is an inertial measurement unit.Embodiment 2

[0145] Next, an embodiment of a work machine control system according to the present disclosure will be described with reference to FIG. 1 and FIG. 9. FIG. 9 is a schematic diagram showing a configuration example of a work machine control system SYS according to the present embodiment.

[0146] The work machine control system SYS includes a controller 40 having the same function as the controller 30 mounted on the work machine 100 according to the above-described embodiment 1. In the example shown in FIG. 9, the controller 40 is installed in a remote control room RC for externally operating the work machine 100 described in the above-described embodiment 1.

[0147] The work machine control system SYS includes, for example, one or more work machines 100 and one or more remote control rooms RC. Since the work machine 100 has the same configuration as the work machine 100 shown in FIG. 1, the detailed configuration of the work machine 100 is omitted from FIG. 9.

[0148] The work machine 100 and the remote control room RC are connected to each other so that data can be transmitted and received via a communication network NW. The work machine 100 and the remote control room RC may be connected to each other so that data can be directly transmitted and received to and from each other without using the communication network NW. In the illustrated example, the work machine 100 transmits information about the work site to the remote control room RC. Thus, a remote operator RO of the remote control room RC can grasp the situation of the work site based on information from the work machine 100.

[0149] The work machine 100 is provided with a sensor capable of three-dimensionally recognizing the position and shape of an object existing at the work site. For example, the work machine 100 is provided with an object detection device S6 as a space recognition device. Therefore, the work machine 100 can transmit the result of three-dimensionally measuring the work site to the remote control room RC.

[0150] The space recognition device is a device for recognizing a space around the work machine 100. Specifically, the object detection device S6 as a space recognition device is a LiDAR. The lidar measures, for example, the distance between each of one million or more points in the monitoring range and the lidar. Note that the space recognition device may be any device capable of measuring the distance between objects. For example, the space recognition device may be a stereo camera or a combination of an imaging device and a range-finding device such as a millimeter-wave radar.

[0151] When the work machine control system SYS includes a plurality of work machines 100, the remote operator RO of a specific work machine 100 can acquire information about the work site acquired by one or more other work machines 100 in addition to information about the work site acquired by the specific work machine 100.

[0152] The remote control room RC is provided with a remote communication device CD2, the controller 40, a remote control device 26E, an operation sensor 43, and a display device DIE. The remote control room RC is provided with an operation seat DS in which the remote operator RO who remotely operates the work machine 100 seats.

[0153] The remote communication device CD2 is configured to communicate with the communication device CD attached to the work machine 100. The remote communication device CD2 receives the detection results of the tilt sensor S1, the boom sensor S2, the arm sensor S3, the bucket sensor S4, the vehicle body sensor S5, the object detection device S6 and the like of the work machine 100 from the communication device CD of the work machine 100 and outputs them to the controller 40.

[0154] The controller 40 has the same configuration as the controller 30 mounted on the work machine 100, as described above. Specifically, the controller 40 is composed of a computer including an electronic circuit such as a CPU, an FPGA and an ASIC, a memory such as a volatile storage device and a nonvolatile storage device, and various input / output interfaces. The controller 40 executes various control operations and achieves various functions by, for example, executing an instruction code or a program stored in the memory by a CPU or the like, or by designing a circuit for a special application.

[0155] The display device DIE is a device capable of displaying various types of information. The display device DIE displays an image based on information transmitted from the work machine 100 so that the remote operator RO of the remote control room RC can visually recognize the surroundings around the work machine 100. In the illustrated example, the display device DIE is a liquid crystal display for displaying an image captured by the imaging device of the object detection device S6 mounted on the work machine 100. Note that the display device DIE may be a display or a projector for achieving naked eye stereoscopic vision, or may be VR goggles or the like.

[0156] The remote control device 26E is provided with the operation sensor 43 for detecting the operation contents of the remote control device 26E. The operation sensor 43 is, for example, an inclination sensor for detecting an inclination angle of an operating lever, or an angle sensor for detecting a swing angle of an operating lever around a swing shaft. The operation sensor 43 may be composed of other sensors such as a pressure sensor, a current sensor, a voltage sensor, or a distance sensor. The operation sensor 43 outputs the detected information related to the operation contents of the remote control device 26E to the controller 40.

[0157] The controller 40 generates an operation signal based on the received information and transmits the generated operation signal to the work machine 100. The operation sensor 43 may be configured to generate an operation signal. In this case, the operation sensor 43 may output the operation signal to the remote communication device CD2 without passing through the controller 40. With this configuration, the remote operator RO can remotely operate the work machine 100 from the remote control room RC.

[0158] As described above, the work machine control system SYS of the present embodiment is a system for controlling the work machine 100. As in Embodiment 1, the work machine 100 is provided with the lower traveling body 1, the upper swivel body 3 so as to be capable of swiveling provided on the lower traveling body 1, an attachment assembly AT, a tilt inertial measurement unit, and an angular velocity sensor. The attachment assembly AT includes the boom 4 coupled to the upper swivel body 3 and configured to be raised and lowered, the arm 5 pivotably coupled to the boom 4, and an end attachment such as the bucket 6 pivotably and tiltably coupled to the arm 5. The tilt inertial measurement unit includes a tilt sensor S1 for detecting a tilt angle θtd and a tilt angular velocity ωtd of the end attachment such as the bucket 6. The angular velocity sensor includes a boom sensor S2, an arm sensor S3, and a bucket sensor S4 for detecting angular velocities of the boom 4, the arm 5, and the end attachment such as the bucket 6. Further, the control system SYS of the work machine includes the controller 40 for controlling the operation of the attachment assembly AT based on the detection results of the tilt inertial measurement unit and the angular velocity sensor. The controller 40 switches between the detection mode Md and the estimation mode Me in accordance with the attitude of the attachment assembly AT, as in the case of the controller 30 mounted on the work machine 100 of Embodiment 1. The detection mode Md is a mode for detecting the tilt angle θtd by the tilt inertial measurement unit. The estimation mode Me is a mode for estimating the tilt angle θte from the detection results of the tilt angular velocity ωtd by the tilt inertial measurement unit and the angular velocities ωbm, ωam, ωbu by the angular velocity sensor.

[0159] With this configuration, according to the present embodiment, it is possible to provide a control system SYS for a work machine which controls the operation of the attachment assembly AT by detecting the tilt angle of the end attachment such as the bucket 6 by the tilt sensor S1 which is an inertial measurement unit.

[0160] Further, the present invention is not limited to these embodiments, and various variations and modifications may be made without departing from the scope of the present invention.

Claims

1. A work machine comprising:a lower traveling body;an upper swivel body provided on the lower traveling body so as to be capable of swiveling;an attachment assembly including:a boom provided on the upper swivel body so as to be capable of raising and lowering;an arm provided on the boom so as to be capable of opening and closing; andan end attachment provided on the arm so as to be capable of opening and closing and tilting;a tilt inertial measurement unit configured to detect a tilt angle and a tilt angular velocity of the end attachment;an angular velocity sensor configured to detect angular velocities of the boom, the arm, and the end attachment; anda controller configured to control an operation of the attachment assembly based on detection results of the tilt inertial measurement unit and the angular velocity sensor, wherein the controller is configured to switch, based on an attitude of the attachment assembly, between:a detection mode in which the tilt angle is detected by the tilt inertial measurement unit; andan estimation mode in which the tilt angle is estimated from detection results of the tilt angular velocity detected by the tilt inertial measurement unit and the angular velocities detected by the angular velocity sensor.

2. The work machine according to claim 1, wherein the controller is further configured to switch from the detection mode to the estimation mode when a tilt shaft of the end attachment is along a vertical direction.

3. The work machine according to claim 2, wherein:the controller is further configured to switch:from the detection mode to the estimation mode when a detection result of acceleration in an axial direction of the tilt inertial measurement unit parallel to the tilt shaft is greater than a first threshold value, the first threshold value being smaller than gravity acceleration; andfrom the estimation mode to the detection mode when the detection result of the acceleration in the axial direction parallel to the tilt shaft is smaller than a second threshold value, the second threshold value being smaller than the first threshold value.

4. The work machine according to claim 3, wherein:the controller is further configured to switch from the estimation mode to the detection mode when the detection result of the acceleration in the axial direction parallel to the tilt shaft remains smaller than the second threshold value for a predetermined duration.

5. The work machine according to claim 1, wherein the controller is configured to allow, via a user interface device, enabling or disabling of switching from the detection mode to the estimation mode.

6. The work machine according to claim 1, wherein the controller is configured to notify a user that the estimation mode is being performed via a user interface device.

7. The work machine according to claim 1, wherein the angular velocity sensor is an inertial measurement unit.

8. A control system for a work machine configured to control the work machine including a lower traveling body, an upper swivel body provided on the lower traveling body so as to be capable of swiveling, an attachment assembly including a boom provided on the upper swivel body so as to be capable of raising and lowering, an arm provided on the boom so as to be capable of opening and closing, and an end attachment provided on the arm so as to be capable of opening and closing and tilting, a tilt inertial measurement unit configured to detect a tilt angle and a tilt angular velocity of the end attachment, and an angular velocity sensor configured to detect angular velocities of the boom, the arm, and the end attachment,the control system comprising a controller configured to control an operation of the attachment assembly based on detection results of the tilt inertial measurement unit and the angular velocity sensor,wherein the controller is configured to switch, based on an attitude of the attachment assembly, between:a detection mode in which the tilt angle is detected by the tilt inertial measurement unit; andan estimation mode in which the tilt angle is estimated from detection results of the tilt angular velocity detected by the tilt inertial measurement unit and the angular velocities detected by the angular velocity sensor.

9. A method for controlling a work machine including a lower traveling body, an upper swivel body provided on the lower traveling body so as to be capable of swiveling, an attachment assembly including a boom provided on the upper swivel body so as to be capable of raising and lowering, an arm provided on the boom so as to be capable of opening and closing, and an end attachment provided on the arm so as to be capable of opening and closing and tilting, a tilt inertial measurement unit configured to detect a tilt angle and a tilt angular velocity of the end attachment, and an angular velocity sensor configured to detect angular velocities of the boom, the arm, and the end attachment,the method comprising, when controlling an operation of the attachment assembly based on detection results of the tilt inertial measurement unit and the angular velocity sensor, switching, based on an attitude of the attachment assembly, between:a detection mode in which the tilt angle is detected by the tilt inertial measurement unit; andan estimation mode in which the tilt angle is estimated from detection results of the tilt angular velocity detected by the tilt inertial measurement unit and the angular velocities detected by the angular velocity sensor.

Images