WORK MACHINE, METHOD, AND SYSTEM FOR CONTROLLING WORK MACHINE

Abstract

A work machine includes a vehicle body, a traveling wheel supported by the vehicle body, a steering actuator, an articulate actuator, a travelling wheel steering angle sensor, an articulate angle sensor, an object sensor, and a controller. The vehicle body includes a rear frame and a front frame connected to the rear frame so as to be pivotable left and right. The steering actuator steers the traveling wheel to the left and right. The articulate actuator changes an articulate angle between the rear frame and the front frame. The object sensor detects an object in a periphery of the work machine and outputs a signal indicating the presence of the object. The controller sets a detection range in the periphery in accordance with the steering and articulate angles, and determines the presence of the object in the detection range based on the signal from the object sensor.

Description

BACKGROUND

Technical Field

The present invention relates to a work machine, a method, and a system for controlling a work machine.

Background Information

Conventionally, a technique for detecting a nearby person or an obstacle with a sensor such as a radar is used in work machines. For example, Japanese Patent Laid-open No. 2021-28266 discloses a forklift including an object detection system. The object detection system includes a radar device such as a millimeter wave radar. The radar device emits a radio wave or an ultrasonic wave and receives the radio wave or ultrasonic wave reflected by an object, thereby detecting the presence of the object.

When all of the objects that have entered the measurable range of the radar device are detected and alarms are outputted in the object detection system, the alarms are emitted frequently. As a result, a controller in the aforementioned object detection system sets a detection range in the periphery of the forklift and an alarm is emitted when an object is detected in the detection range. In addition, the detection range is changed in accordance with the vehicle speed and steering of the forklift.

SUMMARY

In the aforementioned object detection system, whether an object is present in the periphery of the forklift can be appropriately detected when the detection range is changed in accordance with the vehicle speed or steering. However, the use of only the abovementioned technology is insufficient in the case of a work machine having a large degree of freedom in the attitude of the vehicle body such as in a motor grader. An objective of the present invention is to appropriately assess whether an object is present in the periphery of a work machine.

A work machine according to a first aspect of the present invention includes a vehicle body, a traveling wheel, a steering actuator, an articulate actuator, a steering angle sensor, an articulate angle sensor, an object sensor, and a controller. The vehicle body includes a rear frame and a front frame. The front frame is connected to the rear frame so as to pivot left and right. The traveling wheel is supported by the vehicle body. The steering actuator steers the traveling wheel to the left and right. The articulate actuator changes the articulate angle between the rear frame and the front frame. The steering angle sensor detects the steering angle of the traveling wheel. The articulate angle sensor detects the articulate angle. The object sensor detects an object in the periphery of the work machine and outputs a signal indicating the presence of the object. The controller sets a detection range in the periphery of the work machine. The controller determines the presence of the object in the detection range based on the signal output by the object sensor. The controller sets the detection range in accordance with the steering angle and the articulate angle.

A method according to a second aspect of the present invention is a method for controlling a work machine. The work machine includes a rear frame, a vehicle body, a traveling wheel, a steering actuator, and an articulate actuator. The vehicle body includes a rear frame and a front frame. The front frame is connected to the rear frame so as to be able to pivot left and right. The traveling wheel is supported by the vehicle body. The steering actuator steers the traveling wheel to the left and right. The articulate actuator changes the articulate angle between the rear frame and the front frame. The method includes detecting the steering angle, detecting the articulate angle, receiving a signal indicating the presence of an object in the periphery of the work machine, setting a detection range in the periphery of the work machine in accordance with the steering angle and the articulate angle, and determining the presence of the object inside the detection range based on the signal from an object sensor.

A system according to a third aspect of the present invention is a system for controlling a work machine. The work machine includes a rear frame, a vehicle body, a traveling wheel, a steering actuator, and an articulate actuator. The vehicle body includes a rear frame and a front frame. The front frame is connected to the rear frame so as to be able to pivot left and right. The traveling wheel is supported by the vehicle body. The steering actuator steers the traveling wheel to the left and right. The articulate actuator changes the articulate angle between the rear frame and the front frame. The system includes a steering angle sensor, an articulate angle sensor, an object sensor, and a controller. The steering angle sensor detects the steering angle of the traveling wheel. The articulate angle sensor detects the articulate angle. The object sensor detects an object in the periphery of the work machine and outputs a signal indicating the presence of the object. The controller sets a detection range in the periphery of the work machine. The controller determines the presence of the object in the detection range based on the signal output by the object sensor. The controller sets the detection range in accordance with the steering angle and the articulate angle.

According to the present invention, a detection range for objects in the periphery of the work machine is set in accordance with the steering angle and the articulate angle. As a result, whether an object is present in the periphery of a work machine can be appropriately determined.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a work machine according to an embodiment.

FIG. 2 is a side view of the work machine.

FIG. 3 is a top view of a front part of the work machine.

FIG. 4 is a front view of the front part of the work machine.

FIG. 5 is a schematic view of a configuration of a control system of the work machine.

FIG. 6 is a top view illustrating an example of a detection range.

FIG. 7 is a flow chart illustrating processing for setting the detection range.

FIG. 8 is a flow chart illustrating processing for setting the detection range.

FIG. 9 is a top view of the detection range according to a first change process.

FIG. 10 is a top view of the detection range according to a second change process.

FIG. 11 is a top view of the detection range according to a third change process.

FIG. 12 is a top view of the detection range according to the third change process.

FIG. 13 is a top view of the detection range according to a fourth change process.

FIG. 14 is a top view of the detection range according to a change 5 process.

FIG. 15 is a top view of the detection range according to the change 5 process.

FIG. 16 is a top view of the detection range according to a sixth change process.

FIG. 17 is a top view of the detection range according to a seventh change process.

FIG. 18 is a top view of the detection range according to the seventh change process.

FIG. 19 is a top view of the detection range according to an eighth change process.

FIG. 20 is a top view of the detection range according to the eighth change process.

FIG. 21 is a top view of the detection range according to a ninth change process.

FIG. 22 is a top view of the detection range according to the ninth change process.

FIG. 23 is a top view of the detection range according to the ninth change process

FIG. 24 is a top view of the detection range according to the ninth change process.

FIG. 25 is a top view illustrating a detection range according to a modified example.

DETAILED DESCRIPTION OF EMBODIMENT(S)

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a work machine 1 according to the embodiment. FIG. 2 is a side view of the work machine 1. As illustrated in FIG. 1, the work machine 1 includes a vehicle body 2, traveling wheels 3A and 3B, and 4A to 4D, and a work implement 5. The vehicle body 2 includes a front frame 11, a rear frame, 12, a cab 13, and a power chamber 14.

The rear frame 12 is connected to the front frame 11. The front frame 11 is coupled to the rear frame 12 so as to allow pivoting with respect to the rear frame 12. As indicated below, the front frame 11 is configured to pivot to the left and right with respect to the rear frame 12.

In the following explanation, the front, rear, left, and right directions are defined as the front, rear, left, and right directions of the vehicle body 2 while the articulate angle of the front frame 11 with respect to the rear frame 12 is zero, that is, while the front frame 11 and the rear frame 12 are straight.

The cab 13 and the power chamber 14 are disposed on the rear frame 12. An unillustrated operator's seat is disposed in the cab 13. The cab 13 is disposed to the rear of the power chamber 14. The front frame 11 extends toward the front from the rear frame 12.

The traveling wheels 3A and 3B, and 4A to 4D are rotatably supported by the vehicle body 2. The traveling wheels 3A and 3B, and 4A to 4D include front wheels 3A and 3B and rear wheels 4A to 4D. The front wheels 3A and 3B are disposed away from each other in the left-right direction. The front wheels 3A and 3B are attached to the front frame 11. The rear wheels 4A to 4D are attached to the rear frame 12.

The work implement 5 is movably connected to the vehicle body 2. The work implement 5 includes a supporting member 15 and a blade 16. The supporting member 15 is movably connected to the vehicle body 2. The supporting member 15 supports the blade 16. The supporting member 15 includes a drawbar 17 and a circle 18. The drawbar 17 is disposed below the front frame 11.

The drawbar 17 is connected to a front part 19 of the front frame 11. The drawbar 17 extends toward the rear from the front part 19 of the front frame 11. The drawbar 17 is swingably supported at least in the up-down direction and the left-right direction of the vehicle body 2 with respect to the front frame 11. For example, the front part 19 includes a ball joint. The drawbar 17 is rotatably connected to the front frame 11 via the ball joint.

The circle 18 is connected to a rear part of the drawbar 17. The circle 18 is rotatably supported with respect to the drawbar 17. The blade 16 is connected to the circle 18. The blade 16 is supported by the drawbar 17 via the circle 18. As illustrated in FIG. 2, the blade 16 is supported by the circle 18 so as to be able to rotate about a tilt axis 21. The tilt axis 21 extends in the left-right direction.

FIG. 3 is a top view of a front part of the work machine 1. As illustrated in FIG. 3, the work machine 1 includes a first steering axis 43A and a second steering axis 43B. The first steering axis 43A and the second steering axis 43B are provided to the front frame 11. The first steering axis 43A and the second steering axis 43B extend in the up-down direction. The first front wheel 3A is supported so as to be able to rotate about the first steering axis 43A. The second front wheel 3B is supported so as to be able to rotate about the second steering axis 43B. That is, the front wheels 3A and 3B are traveling wheels that can be steered.

The work machine 1 includes a plurality of steering actuators 41A and 41B for steering the front wheels 3A and 3B. The plurality of steering actuators 41A and 41B are used for steering the front wheels 3A and 3B. For example, the plurality of steering actuators 41A and 41B are hydraulic cylinders. The plurality of steering actuators 41A and 41B are respectively connected to the front wheels 3A and 3B. The plurality of steering actuators 41A and 41B extend and contract due to hydraulic pressure. In the following explanation, the extension and contraction of hydraulic cylinders that include the steering actuators 41A and 41B are referred to as “stroke motions.”

The plurality of steering actuators 41A and 41B include a left steering actuator 41A and a right steering actuator 41B. The left steering cylinder 41A and the right steering cylinder 41B are disposed away from each other in the left-right direction.

The left steering actuator 41A is connected to the front frame 11 and the front wheel 3A. The right steering actuator 41B is connected to the front frame 11 and the front wheel 3B. The front wheels 3A and 3B are steered by the stroke motions of the left steering actuator 41A and the right steering actuator 41B.

The work machine 1 includes an articulate axis 44. The articulate axis 44 is connected to the front frame 11 and the rear frame 12. The articulate axis 44 extends in the up-down direction. The front frame 11 and the rear frame 12 are connected to each other so as to allow pivoting about the articulate axis 44.

In the following explanation, the state of the vehicle body 2 being bent due to the front frame 11 and the rear frame 12 mutually pivoting about the articulate axis 44 is referred to as an “articulated state.” A state other than the articulated state, that is, the state in which the front frame 11 and the rear frame 12 are aligned in a straight line, is referred to as a “linear state.”

The work machine 1 includes a plurality of articulating actuators 27 and 28. The plurality of articulating actuators 27 and 28 are used for pivoting the front frame 11 with respect to the rear frame 12. For example, the plurality of articulating actuators 27 and 28 are hydraulic cylinders. The plurality of articulating actuators 27 and 28 are connected to the front frame 11 and the rear frame 12. The plurality of articulating actuators 27 and 28 extend and contract due to hydraulic pressure.

The plurality of articulating actuators 27 and 28 include a left articulating cylinder 27 and a right articulating cylinder 28. The left articulating cylinder 27 and the right articulating cylinder 28 are disposed away from each other in the left-right direction.

The left articulating cylinder 27 is connected to the front frame 11 and the rear frame 12 on the left side of the vehicle body 2. The right articulating cylinder 28 is connected to the front frame 11 and the rear frame 12 on the right side of the vehicle body 2. The front frame 11 pivots to the left or right with respect to the rear frame 12 due to the stroke motions of the left articulating cylinder 27 and the right articulating cylinder 28.

FIG. 4 is a front view of the front part of the work machine 1. As illustrated in FIG. 4, the work machine 1 includes a leaning mechanism 6. The leaning mechanism 6 tilts the front wheels 3A and 3B to the left and right. The leaning mechanism 6 includes an axle beam 56, a leaning rod 57, and a leaning actuator 60. The axle beam 56 extends from the front frame 11 to the left and right. The axle beam 56 is supported by the front frame 11 so as to be able to rotate about a pivot axis 58.

The axle beam 56 is supported by the front wheel 3A via a wheel bracket 59A. The axle beam 56 supports the front wheel 3A so as to allow rotation about a leaning axis 54A. The axle beam 56 is supported by the front wheel 3B via a wheel bracket 59B. The axle beam 56 supports the front wheel 3B so as to allow rotation about a leaning axis 54B. The leaning axes 54A and 54B extend in the front-back direction.

The leaning rod 57 extends to the left and right through the front frame 11. The leaning rod 57 couples the front wheels 3A and 3B to each other. The leaning rod 57 is supported on the front wheel 3A via the wheel bracket 59A. The leaning rod 57 is supported on the front wheel 3B via the wheel bracket 59B.

The leaning actuator 60 is used for tilting (leaning) the front wheels 3A and 3B. The leaning actuator 60 is, for example, a hydraulic cylinder. The leaning actuator 60 is connected to the front frame 11 and the front wheels 3A and 3B. The leaning actuator 60 extends and contracts due to hydraulic pressure. That is, the front wheels 3A and 3B respectively rotate about the leaning axes 54A and 54B due to the extension and contraction of the leaning actuator 60. Consequently, the front wheels 3A and 3B are leaned to the left or right.

As illustrated in FIG. 2, the work machine 1 includes a plurality of actuators 22 to 26 for changing the attitude of the work implement 5. The plurality of actuators 22 to 25 are, for example, hydraulic cylinders. The actuator 26 is a rotation actuator. In the present embodiment, the actuator 26 is a hydraulic motor. The actuator 26 may be an electric motor.

The plurality of actuators 22 to 25 are connected to the work implement 5. The plurality of actuators 22 to 25 extend and contract due to hydraulic pressure. The plurality of hydraulic cylinders 22 to 25 change the attitude of the work implement 5 with respect to the vehicle body 2 by extending and contracting.

Specifically, the plurality of hydraulic cylinders 22 to 25 include a left lift cylinder 22, a right lift cylinder 23, a drawbar shift cylinder 24, and a blade tilt cylinder 25.

The left lift cylinder 22 and the right lift cylinder 23 are disposed away from each other in the left-right direction. The left lift cylinder 22 and the right lift cylinder 23 are connected to the drawbar 17. The left lift cylinder 22 and the right lift cylinder 23 are connected to the front frame 11 via a lifter bracket 29. The drawbar 17 swings up and down due to the stroke motions of the left lift cylinder 22 and the right lift cylinder 23. As a result, the blade 16 moves up and down.

The drawbar shift cylinder 24 is coupled to the drawbar 17 and the front frame 11. The drawbar shift cylinder 24 is connected to the front frame 11 via the lifter bracket 29. The drawbar shift cylinder 24 extends diagonally downward from the front frame 11 toward the drawbar 17. The drawbar 17 swings left and right due to the stroke motions of the drawbar shift cylinder 24.

The blade tilt cylinder 25 is connected to the circle 18 and the blade 16. The blade 16 rotates about the tilt axis 21 due to the stroke motions of the blade tilt cylinder 25.

The rotation actuator 26 is connected to the drawbar 17 and the circle 18. The rotation actuator 26 causes the circle 18 to rotate with respect to the drawbar 17. Consequently, the blade 16 rotates about a rotating axis that extends in the up-down direction.

FIG. 5 is a schematic view of a configuration of a control system of the work machine 1. As illustrated in FIG. 5, the work machine 1 includes a driving source 31, a hydraulic pump 32, and a power transmission device 33. The work machine 1 includes a steering valve 42A, an articulating valve 42B, a leaning valve 42C, and a work implement valve 34. The driving source 31 is, for example, an internal combustion engine. Alternatively, the driving source 31 may be an electric motor or a hybrid of an internal combustion engine and an electric motor.

The hydraulic pump 32 is driven by the driving source 31 thereby discharging hydraulic fluid. The hydraulic pump 32 supplies hydraulic fluid to the steering valve 42A, the articulating valve 42B, the leaning valve 42C, and the work implement valve 34. Consequently, the plurality of steering actuators 41A and 41B, the plurality of articulating actuators 27 and 28, the leaning actuator 60, and the plurality of actuators 22 to 26 operate. While only one hydraulic pump 32 is illustrated in FIG. 5, a plurality of hydraulic pumps may be provided.

The steering valve 42A is connected through a hydraulic circuit to the hydraulic pump 32 and the plurality of steering actuators 41A and 41B. The steering valve 42A controls the flow rate of hydraulic fluid supplied from the hydraulic pump 32 to the plurality of steering actuators 41A and 41B. The plurality of steering actuators 41A and 41B perform stroke motions due to the hydraulic fluid from the hydraulic pump 32 being supplied to the steering valve 42A.

The articulating valve 42B is connected to the hydraulic pump 32 and the plurality of articulating actuators 27 and 28 through the hydraulic circuit. The articulating valve 42B controls the flow rate of the hydraulic fluid supplied from the hydraulic pump 32 to the plurality of articulating actuators 27 and 28. The plurality of articulating actuators 27 and 28 perform stroke motions due to the hydraulic fluid from the hydraulic pump 32 being supplied to the articulating valve 42B.

The leaning valve 42C is connected through the hydraulic circuit to the hydraulic pump 32 and the leaning actuator 60. The leaning valve 42C controls the flow rate of hydraulic fluid supplied from the hydraulic pump 32 to the leaning actuator 60. The leaning actuator 60 performs stroke motions due to the hydraulic fluid being supplied from the hydraulic pump 32 to the leaning valve 42C.

The work implement valve 34 is connected to the hydraulic pump 32 and the plurality of actuators 22 to 26 via the hydraulic circuit. The work implement valve 34 includes a plurality of valves respectively connected to the plurality of actuators 22 to 26. The work implement valve 34 controls the flow rate of hydraulic fluid supplied from the hydraulic pump 32 to the plurality of actuators 22 to 26.

The power transmission device 33 transmits the driving power from the driving source 31 to the rear wheels 4A to 4D. The power transmission device 33 may include a torque converter and/or a plurality of speed change gears. Alternatively, the power transmission device 33 may be transmission of another type such as a hydrostatic transmission (HST) or a hydraulic mechanical transmission (HMT).

The work machine 1 includes a steering operating member 45, an articulate operating member 46, a leaning operating member 47, a work implement operating member 48, a shift operating member 49, and an accelerator operating member 50.

The steering operating member 45 is operable by an operator for steering the front wheels 3A and 3B. The steering operating member 45 is a lever such as a joy stick. Alternatively, the steering operating member 45 may be a member other than a lever. For example, the steering operating member 45 may be a steering wheel. The steering operating member 45 outputs a steering operation signal that indicates the operation on the steering operating member 45 by the operator.

The articulate operating member 46 is operable by the operator for pivoting the front frame 11 with respect to the rear frame 12. The articulate operating member 46 is a lever such as a joystick. Alternatively, the articulate operating member 46 may be a member other than a lever. The articulate operating member 46 outputs an articulating operation signal that indicates the operation on the articulate operating member 46 by the operator.

The leaning operating member 47 is operable by an operator for leaning the front wheels 3A and 3B. The leaning operating member 47 is a lever such as a joy stick. Alternatively, the leaning operating member 47 may be another member such as a switch or a touch screen. The leaning operating member 47 outputs a leaning operation signal that indicates the operation on the leaning operating member 47 by the operator.

The work implement operating member 48 is operable by the operator in order to change the attitude of the work implement 5. The work implement operating member 48 includes, for example, a plurality of work implement levers. Alternatively, the work implement operating member 48 may be another member such as a switch or a touch screen. The work implement operating member 48 outputs a signal that indicates the operation on the work implement operating member 48 by the operator.

The shift operating member 49 is operable by the operator for switching between forward travel and reverse travel of the work machine 1. The shift operating member 49 includes, for example, a shift lever. Alternatively, the shift operating member 49 may be another member such as a switch or a touch screen. The shift operating member 49 outputs a signal that indicates the operation of the shift operating member 49 by the operator.

The accelerator operating member 50 is operable by the operator for causing the work machine 1 to travel. The accelerator operating member 50 is, for example, an accelerator pedal. Alternatively, the accelerator operating member 50 may be another member such as a switch or a touch screen. The accelerator operating member 50 outputs a signal that indicates the operation of the accelerator operating member 50 by the operator.

As illustrated in FIG. 5, the work machine 1 includes a controller 37. The controller 37 includes a storage device 38 and a processor 39. The processor 39 is, for example, a CPU and executes a program for controlling the work machine 1. The storage device 38 includes a memory such as a RAM or a ROM, and an auxiliary storage device such as an SSD or an HDD. The storage device 38 stores programs and data for controlling the work machine 1.

The controller 37 controls the power transmission device 33 in response to an operation of the shift operating member 49. As a result, the traveling direction of the work machine 1 switches between forward travel and reverse travel. In addition, the velocity stages of the power transmission device 33 are switched. Alternatively, the shift operating member 49 may be mechanically connected to the power transmission device 33. The action of the shift operating member 49 may be mechanically transmitted to the power transmission device 33 whereby the gears for forward travel and reverse travel or the speed change gears of the power transmission device 33 may be switched.

The controller 37 controls the driving source 31 and the power transmission device 33 in response to an operation on the accelerator operating member 50. As a result, the work machine 1 travels. The controller 37 controls the hydraulic pump 32 and the work implement valve 34 in response to an operation on the work implement operating member 48. As a result, the work implement 5 moves.

The controller 37 acquires the operating amount of the steering operating member 45 from the steering operation signal from the steering operating member 45. The controller 37 causes the plurality of steering actuators 41A and 41B to extend and contract by controlling the steering valve 42A in accordance with the steering operation signal. As a result, the controller 37 changes a steering angle θs of the front wheels 3A and 3B.

As illustrated in FIG. 3, the steering angle θs is the angle that the front wheels 3A and 3B turn with respect to the front frame 11 about the first steering axis 43A and the second steering axis 43B respectively. Specifically, the steering angle θs is the rotation angle of the front wheels 3A and 3B with respect to a first center line L1 of the front frame 11. The first center line L1 extends in the front-back direction of the front frame 11.

The steering angle θs changes from a neutral position to the left or right due to the stroke motions of the plurality of steering actuators 41A and 41B. The steering angle θs at the neutral position is zero degrees. The front wheels 3A and 3B are disposed parallel to the first center line L1 of the front frame 11 at the neutral position. In FIG. 3, 3A′ and 3B′ represent the front wheels while steered by the steering angle θs from the neutral position to the right.

The controller 37 acquires the operating amount of the articulate operating member 46 from the articulating operation signal from the articulate operating member 46. The controller 37 controls the articulating valve 42B. For example, the controller 37 controls the articulating valve 42B in accordance with the articulating operation signal thereby causing the left articulating cylinder 27 and the right articulating cylinder 28 to extend and contract. As a result, the controller 37 changes an articulate angle θa.

As illustrated in FIG. 3, the articulate angle θa is the angle that the front frame 11 pivots with respect to the rear frame 12 about the articulate axis 44. Specifically, the articulate angle θa is the angle formed by the first center line L1 of the front frame 11 and a second center line L2 of the rear frame 12.

The second center line L2 extends in the front-back direction of the rear frame 12. The second center line L2 passes through the articulate axis 44 as seen in a top view of the work machine 1. The articulate angle θa changes from the neutral position to the left or right. The articulate angle θa in the neutral position is zero. The articulate angle θa toward the left is a positive value and the articulate angle θa toward the right is a negative value.

When the articulate angle θa is zero, the direction of the second center line L2 matches the direction of the first center line L1. That is, when the articulate angle θa is zero, the vehicle body 2 is in the linear state. FIG. 3 illustrates a state in which the front frame 11 is pivoted by the articulate angle θa about the articulate axis 44.

The controller 37 acquires the operating amount of the leaning operating member 47 from the leaning operation signal from the leaning operating member 47. The controller 37 controls the leaning valve 42C. For example, the controller 37 controls the leaning valve 42C in accordance with the leaning operation signal thereby causing the leaning actuator 60 to extend and contract. As a result, the controller 37 changes a leaning angle θl in accordance with the operation of the leaning operating member 47 by the operator.

As illustrated in FIG. 4, the leaning angle θl is the tilting angle in the left-right direction of the front wheels 3A and 3B as seen from the front of the vehicle body 2. For example, the leaning angle θl is the tilting angle in which the front wheels 3A and 3B respectively lean about the leaning axes 54A and 54B as seen from the front of the vehicle body 2.

In the following explanation, the state in which the front wheels 3A and 3B are perpendicular to a horizontal plane (3A and 3B depicted with solid lines) is referred to as the neutral state of the front wheels 3A and 3B. The leaning angle θl is zero degrees while the front wheels 3A and 3B are in the neutral state. In FIG. 4, 3A′ and 3B′ represent the front wheels leaned from the neutral position to the left and right by the leaning angle θl.

The work machine 1 includes a steering angle sensor 51, an articulate angle sensor 52, and a leaning angle sensor 53. The steering angle sensor 51 is used for detecting the steering angle θs of the front wheels 3A and 3B. The steering angle sensor 51 outputs a signal indicating the steering angle θs.

The articulate angle sensor 52 is used for detecting the articulate angle of the front frame 11 with respect to the rear frame 12. In this case, the articulate angle sensor 50 outputs a signal indicating the articulate angle θa. The leaning angle sensor 53 is used for detecting the leaning angle θl of the front wheels 3A and 3B. The leaning angle sensor 53 outputs a signal indicating the leaning angle θl.

The steering angle sensor 51, the articulate angle sensor 52, and the leaning angle sensor 53 may be inertial measurement devices (IMU). Alternatively, the steering angle sensor 51, the articulate angle sensor 52, and the leaning angle sensor 53 may be cameras. In this case, the controller 37 may analyze the images acquired by the sensors 51 to 53 thereby calculating the steering angle θs, the articulate angle θa, and the leaning angle θl.

Alternatively, the steering angle sensor 51, the articulate angle sensor 52, and the leaning angle sensor 53 may be sensors that respectively detect the stroke amounts of the steering actuator 41A, and 41B, the stroke amounts of the articulating cylinders 27 and 28, and the stroke amount of the leaning actuator 60. In this case, the controller 37 may calculate the respective steering angle θs, the articulate angle θa, and the leaning angle θl from the stroke amounts of the steering actuator 41A and 41B, the stroke amounts of the articulating cylinders 27 and 28, and the stroke amount of the leaning actuator 60.

Alternatively, the steering angle sensor 51 may detect the steering angle θs directly. The articulate angle sensor 52 may detect the articulate angle θa directly. The leaning angle sensor 53 may detect the leaning angle θl directly.

As illustrated in FIG. 5, the work machine 1 includes object sensors 61 and 62 and an output device 63. The object sensors 61 and 62 detect objects in the periphery of the work machine 1. The object sensors 61 and 62 are both, for example, a radar device such as a millimeter wave radar. Alternatively, the object sensors 61 and 62 may both be another type of sensor such as an ultrasonic sensor, a camera, or a light detection and ranging (LIDAR) device. The object sensors output signals indicating the presence of objects in the periphery of the work machine 1.

The object sensors 61 and 62 include the first object sensor 61 and the second object sensor 62. The first object sensor 61 detects objects in front of the vehicle body 2. The first object sensor 61 is attached, for example, to the front frame 11. Alternatively, the first object sensor 61 may be attached at another location such as the cab 13. The second object sensor 62 detects objects to the rear of the vehicle body 2. The second object sensor 62 is, for example, attached to the rear frame 12, or the second object sensor 62 may be attached at another location such as the cab 13 or the power chamber 14.

The output device 63 is, for example, a display. The output device 63 displays an image in accordance with an instruction signal from the controller 37. Alternatively, the output device 63 may be a speaker. The output device 63 may output a sound in accordance with an instruction signal from the controller 37.

The controller 37 sets detection ranges 71 and 72 in the periphery of the work machine 1 and determines the presence of objects in the detection ranges 71 and 72 based on the signals from the object sensors 61 and 62. As illustrated in FIG. 6 for example, the controller 37 sets a first detection range 71 in front of the vehicle body 2. The controller 36 sets a second detection range 72 to the rear of the vehicle body 2. The controller 36 causes the output device 63 to output a warning when an object 100 is detected in the detection ranges 71 or 72.

The controller 37 stores a first reference range 73 of the first detection range 71 and a second reference range 74 of the second detection range 72. The first reference range 73 and the second reference range 74 are set based on the width (referred to below as “vehicle width”) L0 of the vehicle body 2. The width of the first reference range 73 and the width of the second reference range 74 are both the same as the maximum vehicle width L0 of the work machine 1 excluding the work implement 5.

The controller 37 sets the detection ranges 71 and 72 in accordance with the steering angle θs, the articulate angle θa, and the leaning angle θl. The controller 37 changes the detection ranges 71 and 72 from the respective reference ranges 73 and 74 in accordance with the steering angle θs, the articulate angle θa, and the leaning angle θl. A method for setting the detection ranges 71 and 72 performed by the controller 37 will be explained below. FIGS. 7 and 8 are flow charts illustrating processing for setting the detection ranges 71 and 72 executed by the controller 37.

As illustrated in step S1 in FIG. 7, the controller 37 acquires the steering angle θs. The controller 37 acquires the steering angle θs from the signal from the steering angle sensor 51. In step S2, the controller 37 acquires the articulate angle θa. The controller 37 acquires the articulate angle θa from the signal from the articulate angle sensor 52. In step S3, the controller 37 acquires the leaning angle θl. The controller 37 acquires the leaning angle θl from the signal from the leaning angle sensor 53.

In step S4, the controller 37 determines whether the steering angle θs is zero. In step S5, the controller 37 determines whether the articulate angle θa is zero. In step S6, the controller 37 determines whether the leaning angle θl is zero.

When the steering angle θs, the articulate angle θa, and the leaning angle θl are zero, in step S7 the controller 37 sets the reference ranges 73 and 74 as the respective detection ranges 71 and 72. That is, the controller 37 sets the reference ranges 73 and 74 as the respective detection ranges 71 and 72 when the work machine 1 is traveling straight in the linear state without being steered or leaning. Specifically, as illustrated in FIG. 6, the controller 37 sets the first reference range 73 as the first detection range 71. The controller 37 also sets the second reference range 74 as the second detection range 72.

When the leaning angle θl is not zero in step S6, the process advances to step S8. In step S8, the controller 37 changes the reference ranges 73 and 74 according to a first change process thereby setting the detection ranges 71 and 72. FIG. 9 is a top view of the detection ranges 71 and 72 according to the first change process.

As illustrated in FIG. 9, in the first change process, the controller 37 increases the detection ranges 71 and 72 to the side that is the same as the direction (referred to below as “leaning direction”) that the front wheels 3A and 3B lean toward in the left-right direction. That is, the controller 37 increases the detection ranges 71 and 72 on the same side as the leaning direction when the work machine 1 is traveling straight while leaning in the linear state without being steered.

For example, when the front wheels 3A and 3B are leaning toward the left, the controller 37 increases the first detection range 71 from the first reference range 73 toward the left. The controller 37 increases the second detection range 72 from the second reference range 74 toward the left. The controller 37 also does not increase the detection ranges 71 and 72 toward the right. In this case, the width Lall of the detection ranges 71 and 72 is expressed by the following equation (1).

$\begin{array}{cc}\mathrm{LAll}=L0+Ll& \left(1\right)\end{array}$

Ll is the amount of increase of the detection ranges when leaning. The amount of increase Ll during leaning represents the displacement amount of the front wheels 3A and 3B toward the outside in the left-right direction due to the leaning. The amount of increase Ll during leaning is expressed by the following equation (2).

$\begin{array}{cc}\mathrm{Ll}=D\times \cos \theta l& \left(2\right)\end{array}$

As illustrated in FIG. 4, D is the outer diameter of the front wheels 3A and 3B. While not illustrated in the drawing, when the front wheels 3A and 3B are leaning toward the right in the first change process, the controller 37 increases the first detection range 71 toward the right from the first reference range 73 and increases the second detection range 72 toward the right from the second reference range 74.

When the articulate angle θa is not zero in step S5, the process advances to step S9. In step S9, the controller 37 determines whether the leaning angle θl is zero. When the leaning angle θl is zero in step S9, the process advances to step S10.

In step S10, the controller 37 changes the reference ranges 73 and 74 according to a second change process thereby setting the detection ranges 71 and 72. FIG. 10 is a top view of the detection ranges 71 and 72 according to the second change process. As illustrated in FIG. 10, in the second change process, the controller 37 curves the detection ranges 71 and 72 in accordance with the turning radius of the work machine 1 corresponding to the articulate angle θa. That is, when the work machine 1 turns in the articulated state without being steered and without leaning, the detection ranges 71 and 72 are curved according to locuses A1 and A2 of the turning of the work machine 1.

For example, when the work machine 1 turns toward the left in the articulated state, the controller 37 curves the detection ranges 71 and 72 toward the left. The controller 37 stores data that represents the relationship between the articulate angle θa and the turning radius of the work machine 1, and may calculate the turning radius form the articulate angle θa by referring to the data. The width Lall of the detection ranges 71 and 72 is the same as the width of the reference ranges 73 and 74 and is expressed by the following equation (3).

$\begin{array}{cc}\mathrm{LAll}=L0& \left(3\right)\end{array}$

While not illustrated in the drawing, when the work machine 1 turns toward the right in the articulated state, the controller 37 curves the detection ranges 71 and 72 toward the right in the second change process.

When the leaning angle θl is not zero in step S9, the process advances to step S11. In step S11, the controller 37 changes the reference ranges 73 and 74 according to a third change process thereby setting the detection ranges 71 and 72. FIGS. 11 and 12 are top views of the detection ranges 71 and 72 according to the third change process.

As illustrated in FIGS. 11 and 12, in the third change process, the controller 37 curves the detection ranges 71 and 72 and increases the detection ranges 71 and 72 on the same side as the leaning direction in accordance with the turning radius of the work machine 1 corresponding to the articulate angle θa and the leaning angle θl. That is, the controller 37 curves the detection ranges 71 and 72 and increases the detection ranges 71 and 72 on the same side as the leaning direction according to the locus of the turning of the work machine 1 in the same way as in the second change process when the work machine 1 is turning in the articulated state while leaning without being steered. For example, the controller 37 stores data that represents the relationship between the articulate angle θa, the leaning angle θl, and the turning radius of the work machine 1, and may calculate the turning radius from the articulate angle θa and the leaning angle θl by referring to the data.

For example, as illustrated in FIG. 11, when the work machine 1 turns toward the left in the articulated state while leaning toward the left, the controller 37 curves the detection ranges 71 and 72 toward the left and increases the detection ranges 71 and 72 by the amount of increase Ll toward the left. As illustrated in FIG. 12, when the work machine 1 turns toward the left in the articulated state while leaning toward the right, the controller 37 curves the detection ranges 71 and 72 toward the left and increases the detection ranges 71 and 72 by the amount of increase Ll toward the right. The width Lall of the detection ranges 71 and 72 is expressed by the abovementioned equation (1).

While not illustrated in the drawings, in the third change process, when the work machine 1 turns toward the right in the articulated state, the controller 37 curves the detection ranges 71 and 72 toward the right and increases the detection ranges 71 and 72 on the same side as the leaning direction.

When the steering angle θs is not zero in step S4, the process advances to step S12 in FIG. 8. In step S12, the controller 37 determines whether the articulate angle θa is zero. In step S13, the controller 37 determines whether the leaning angle θl is zero. When the articulate angle θa and the leaning angle θl are both zero, the process advances to step S14.

In step S14, the controller 37 changes the reference ranges 73 and 74 according to a fourth change process thereby setting the detection ranges 71 and 72. FIG. 13 is a top view of the detection ranges 71 and 72 according to the fourth change process. As illustrated in FIG. 13, in the fourth change process, the controller 37 curves the detection ranges 71 and 72 in accordance with the turning radius of the work machine 1 corresponding to the steering angle θs. That is, when the work machine 1 is turned by steering without leaning, the detection ranges 71 and 72 are curved according to the locus of the turning of the work machine 1.

For example, as illustrated in FIG. 13, when the work machine 1 turns toward the left by steering, the controller 37 curves the detection ranges 71 and 72 toward the left. For example, the controller 37 stores data that represents the relationship between the steering angle θs and the turning radius of the work machine 1, and may calculate the turning radius form the steering angle θs by referring to the data. The width Lall of the detection ranges 71 and 72 is the same as the width of the reference ranges 73 and 74 and is expressed by the abovementioned equation (3). While not illustrated in the drawing, when the work machine 1 turns toward the right by the steering, the controller 37 curves the detection ranges 71 and 72 toward the right in the fourth change process.

When the leaning angle θl is not zero in step S13, the process advances to step S15. In step S15, the controller 37 changes the reference ranges 73 and 74 according to a fifth change process thereby setting the detection ranges 71 and 72. FIGS. 14 and 15 are top views illustrating the detection ranges 71 and 72 according to the fifth change process.

As illustrated in FIGS. 14 and 15, in the fifth change process, the controller 37 curves the detection ranges 71 and 72 and increases the detection ranges 71 and 72 on the same side as the leaning direction in accordance with the turning radius of the work machine 1 corresponding to the steering angle θs and the leaning angle θl. That is, the controller 37 curves the detection ranges 71 and 72 and increases the detection ranges 71 and 72 on the same side as the leaning direction according to the locus of the turning of the work machine 1 when the work machine 1 turns by steering while leaning in the linear state. The controller 37 stores data that represents the relationship between the steering angle θs, the leaning angle θl, and the turning radius of the work machine 1, and may calculate the turning radius of the work machine 1 from the steering angle θs and the leaning angle θl by referring to the data.

For example, as illustrated in FIG. 14, when the work machine 1 turns toward the left while leaning toward the left, the controller 37 curves the detection ranges 71 and 72 toward the left and increases the detection ranges 71 and 72 by the amount of increase Ll toward the left. As illustrated in FIG. 15, when the work machine 1 turns toward the left while leaning toward the right, the controller 37 curves the detection ranges 71 and 72 toward the left and increases the detection ranges 71 and 72 by the amount of increase Ll toward the right. The width Lall of the detection ranges 71 and 72 is expressed by the abovementioned equation (1).

While not illustrated in the drawings, in the fifth change process, when the work machine 1 turns toward the right by steering, the controller 37 curves the detection ranges 71 and 72 toward the right and increases the detection ranges 71 and 72 on the same side as the leaning direction.

When the articulate angle θa is not zero in step S12, the process advances to step S16. In step S16, the controller 37 determines whether the value obtained by reversing the positive value of the articulate angle θa is the same as the steering angle θs (i.e., θs=−θa). When the value obtained by reversing the positive value of the articulate angle θa is the same as the steering angle θs, the processing advances to step S17. In step S17, the controller 37 determines whether the leaning angle θl is zero. When the leaning angle θl is zero, the process advances to step S18.

In step S18, the controller 37 changes the reference ranges 73 and 74 according to a sixth change process thereby setting the detection ranges 71 and 72. FIG. 16 is a top view of the detection ranges 71 and 72 according to the sixth change process.

As illustrated in FIG. 16, when the value obtained by reversing the positive value of the articulate angle θa is the same as the steering angle θs, the work machine 1 is traveling straight in the articulated state. In the sixth change process, the controller 37 increases the reference ranges 73 and 74 in the left-right direction in accordance with the articulate angle θa. The controller 37 increases the first detection range 71 from the first reference range 73 on the opposite side from the bending direction (referred to below as “articulated direction”) of the front frame 11 with respect to the rear frame 12 in the left-right direction. The controller 37 also increases the second detection range 72 from the second reference range 74 on the same side as the articulated direction.

For example, as illustrated in FIG. 16, when the work machine 1 is traveling straight while the front frame 11 is bent toward the left with respect to the rear frame 12, the controller 37 increases the first detection range 71 from the first reference range 73 toward the right and increases the second detection range 72 from the second reference range 74 toward the left. In this case, the width Lall of the detection ranges 71 and 72 is expressed by the following equation (4).

$\begin{array}{cc}\mathrm{Lall}=L0+\mathrm{La}& \left(4\right)\end{array}$

La is the amount of increase of the detection range in the articulated state. As illustrated in FIG. 4, the amount of increase La in the articulated state represents the displacement amount of the front wheels 3A and 3B to the outside in the left-right direction in the articulated state. The amount of increase La in the articulated state is expressed by the following equation (5).

$\begin{array}{cc}\mathrm{La}=\mathrm{Lf}\times \sin \theta a& \left(5\right)\end{array}$

As illustrated in FIG. 3, Lf is the distance between the articulate axis 44 and the center P1 of the axle beam 56. While not illustrated in the drawings, when the work machine 1 is traveling straight while the front frame 11 is bent toward the right with respect to the rear frame 12 in the sixth change process, the controller 37 increases the first detection range 71 from the first reference range 73 toward the left and increases the second detection range 72 from the second reference range 74 toward the right.

When the leaning angle θl is not zero in step S17, the process advances to step S19. In step S19, the controller 37 changes the reference ranges 73 and 74 according to a seventh change process thereby setting the detection ranges 71 and 72. FIGS. 17 and 18 are top views of the detection ranges 71 and 72 according to the seventh change process.

In the seventh change process as illustrated in FIG. 17, the controller 37 increases the reference ranges 73 and 74 in the left-right direction in accordance with the articulate angle θa and increases the detection ranges 71 and 72 on the same side as the leaning direction. That is, the controller 37 increases the detection ranges 71 and 72 in accordance with the articulate angle θa in the left-right direction from the reference ranges 73 and 74 and increases the detection ranges 71 and 72 from the reference ranges 73 and 74 on the same side as the leaning direction when the work machine 1 is traveling straight in an articulated state while leaning.

For example, as illustrated in FIG. 17, when the work machine 1 travels straight in the articulated state toward the left while leaning toward the left, the controller 37 increases the first detection range 71 by the amount of increase La toward the right and increases the first detection range 71 by the amount of increase Ll toward the left. In addition, the controller 37 increases the second detection range 72 by the amount of increase La toward the left and increases the second detection range 72 by the amount of increase Ll toward the left. In this case, the width Lall of the detection ranges 71 and 72 is expressed by the following equation (6).

$\begin{array}{cc}\mathrm{LAll}=L0+\mathrm{La}+\mathrm{Ll}& \left(6\right)\end{array}$

However, as illustrated in FIG. 18, when the leaning direction and the articulated direction are opposite, the controller 37 does not increase the detection ranges 71 and 72 by the amount of increase Ll when leaning. That is, the controller 37 performs the abovementioned seventh change process when the leaning direction and the articulated direction are the same.

While omitted in the drawings, in the seventh change process, when the work machine 1 travels straight in the articulated state toward the right while the front frame 11 is leaning toward the right, the controller 37 increases the detection range 71 by the amount of increase La toward the left and increases the detection range 71 by the amount of increase Ll toward the right. In addition, the controller 37 increases the second detection range 72 by the amount of increase La toward the right and increases the second detection range 72 by the amount of increase Ll toward the right.

In step S16, when the value of the steering angle θs and the value obtained by reversing the positive value of the articulate angle θa are different (that is θs≠θa), the processing advances to step S20.

In step S20, the controller 37 determines whether the leaning angle θl is zero. When the leaning angle θl is zero, the process advances to step S21. In step S21, the controller 37 changes the reference ranges 73 and 74 according to an eighth change process thereby setting the detection ranges 71 and 72. FIGS. 19 and 20 are top views illustrating the detection ranges 71 and 72 according to the eighth change process.

As illustrated in FIG. 19, in the eighth change process, when the turning direction and the articulated direction of the work machine 1 are the same, the controller 37 curves the detection ranges 71 and 72 in accordance with the turning radius of the work machine 1 corresponding to the articulate angle θa and the steering angle θs. That is, when the work machine 1 turns according to the articulate angle θa and the steering angle θs without leaning, the detection ranges 71 and 72 are curved according to the locus of the turning radius of the work machine 1.

For example, when the work machine 1 turns toward the left according to the articulate angle θa and the steering angle θs (θs>−θa), the controller 37 curves the detection ranges 71 and 72 toward the left. The controller 37 stores data that represents the relationship between the articulate angle θa, the steering angle θs, and the turning radius of the work machine 1, and may calculate the turning radius from the articulate angle θa and the steering angle θs by referring to the data. The width Lall of the detection ranges 71 and 72 is the same as the width of the reference ranges 73 and 74 and is expressed by the abovementioned equation (3).

While not illustrated in the drawing, in the eighth change process, when the turning direction and the articulated direction of the work machine 1 are the same and the work machine 1 turns toward the right according to the articulate angle θa and the steering angle θs (θs<−θa), the controller 37 curves the detection ranges 71 and 72 toward the right.

As illustrated in FIG. 20, in the eighth change process, when the value obtained by reversing the positive value of the articulate angle θa is different from the steering angle θs and the turning direction and the articulated direction of the work machine 1 are opposite, the controller 37 curves the detection ranges 71 and 72 in accordance with the turning radius of the work machine 1 corresponding to the articulate angle θa and the steering angle θs, and increases the reference ranges 73 and 74 in the left-right direction in accordance with the articulate angle θa.

For example, as illustrated in FIG. 20, when the articulated direction is toward the left and the steering direction of the work machine 1 is toward the right, the controller 37 increases the first detection range 71 from the first reference range 73 toward the right and curves the first detection range 71 toward the right. The controller 37 also increases the second detection range 72 from the second reference range 74 toward the left and curves the second detection range 72 toward the right. In this case, the width Lall of the detection ranges 71 and 72 is expressed by the abovementioned equation (4).

Although not illustrated in the drawings, in the eighth change process, when the value obtained by reversing the articulate angle θa is different from the steering angle θs, the articulated direction is toward the right and the turning direction of the work machine 1 is toward the left, the controller 37 increases the first detection range 71 from the first reference range 73 toward the left and curves the first detection range 71 toward the left. The controller 37 also increases the second detection range 72 from the second reference range 74 toward the right and curves the second detection range 72 toward the left.

When the leaning angle θl is not zero in step S20, the process advances to step S22. In step S22, the controller 37 changes the reference ranges 73 and 74 according to a ninth change process thereby setting the detection ranges 71 and 72. FIGS. 21 to 24 are top views illustrating the detection ranges 71 and 72 according to the ninth change process.

As illustrated in FIGS. 21 and 22, when the articulated direction and the turning direction of the work machine 1 are the same in the ninth change process, the controller 37 curves the detection ranges 71 and 72 and increases the detection ranges 71 and 72 on the same side as the leaning direction in accordance with the turning radius of the work machine 1 corresponding to the articulate angle θa, the steering angle θs, and the leaning angle θl. That is, the controller 37 curves the detection ranges 71 and 72 and increases the detection ranges 71 and 72 on the same side as the leaning direction according to the locus of the turning radius of the work machine 1 when the work machine 1 turns by the articulate angle θa and the steering angle θs while leaning. The controller 37 stores data that represents the relationship between the articulate angle θa, the steering angle θs, the leaning angle θl, and the turning radius of the work machine 1, and may calculate the turning radius from the articulate angle θa, the steering angle θs, and the leaning angle θl by referring to the data.

For example, as illustrated in FIG. 21, when the work machine 1 turns toward the left by the articulate angle θa and the steering angle θs while leaning toward the left, the controller 37 curves the detection ranges 71 and 72 toward the left and increases the detection ranges 71 and 72 by the amount of increase Ll toward the left. As illustrated in FIG. 22, when the work machine 1 turns toward the left by the articulate angle θa and the steering angle θs while leaning toward the right, the controller 37 curves the detection ranges 71 and 72 toward the left and increases the detection ranges 71 and 72 by the amount of increase Ll toward the right. The width Lall of the detection ranges 71 and 72 is expressed by the abovementioned equation (1).

While not illustrated in the drawings, in the ninth change process, when the articulated direction and the steering direction of the work machine 1 are the same and the work machine 1 turns toward the right in the articulated state, the controller 37 curves the detection ranges 71 and 72 toward the right and increases the detection ranges 71 and 72 on the same side as the leaning direction.

As illustrated in FIG. 23, when the articulated direction and the turning direction of the work machine 1 are opposite in the ninth change process, the controller 37 curves the detection ranges 71 and 72 and increases the detection ranges 71 and 72 in accordance with the turning radius of the work machine 1 corresponding to the articulate angle θa, the steering angle θs, and the leaning angle θl, and increases the reference ranges 73 and 74 in the left-right direction in accordance with the articulate angle θa and increases the detection ranges 71 and 72 on the same side as the leaning direction.

For example as illustrated in FIG. 23, when the articulated direction is toward the left, the steering direction of the work machine 1 is toward the right, and the leaning direction is toward the left, the controller 37 increases the first detection range 71 from the first reference range 73 toward the right by the amount of increase La in the articulated state, increases the first detection range 71 from the first reference range 73 toward the left by the amount of increase Ll during leaning, and curves the first detection range 71 toward the right. The controller 37 also increases the second detection range 72 from the second reference range 74 toward the left by the amount of increase La, increases the second detection range 72 from the second reference range 74 toward the left by the amount of increase Li, and curves the second detection range 72 toward the right. In this case, the width Lall of the detection ranges 71 and 72 is expressed by the abovementioned equation (6).

While not illustrated in the drawings, when the articulated direction is to the right, the steering direction of the work machine 1 is to the left, and the leaning direction is to the right, the controller 37 increases the first detection range 71 from the first reference range 73 toward the left by the amount of increase La, increases the first detection range 71 from the first reference range 73 toward the right by the amount of increase Ll, and curves the first detection range 71 toward the left. The controller 37 also increases the second detection range 72 from the second reference range 74 toward the right by the amount of increase La, increases the second detection range 72 from the second reference range 74 toward the right by the amount of increase Li, and curves the second detection range 72 toward the left.

However, as illustrated in FIG. 24, in the ninth change process, when the articulated direction and the turning direction of the work machine 1 are opposite and the leaning direction and the articulated direction are opposite, the increase of the detection ranges 71 and 72 by the amount of increase Li during leaning is not performed. In this case, the width Lall of the detection ranges 71 and 72 is expressed by the abovementioned equation (4).

In the work machine 1 according to the present embodiment explained above, the detection ranges 71 and 72 of objects in the periphery of the work machine 1 are set in accordance with the articulate angle θa, the leaning angle θl, and the steering angle θs. As a result, whether an object is present in the periphery of the work machine 1 can be appropriately determined.

Although an embodiment of the present invention has been described so far, the present invention is not limited to the above embodiment and various modifications may be made within the scope of the invention.

The configuration of the work machine 1 is not limited to the above embodiment and may be modified. For example, the configuration of the work implement 5 may be changed. A portion of the control system of the work machine 1 may be disposed outside of the work machine 1. For example, the various operating members 46 to 50 of the work machine 1 and the output device 63 may be disposed outside of the work machine 1.

The controller 37 may be configured by a plurality of controllers. The abovementioned processing may be distributed and executed among the plurality of controllers. In such a case, a portion of the plurality of controllers may be disposed outside of the work machine 1.

The process when an object is detected in the detection ranges 71 and 72 is not limited to the above embodiment and may be modified. For example, when an object is detected in the detection ranges 71 and 72, the controller 37 may perform a process for stopping or limiting the motion of the work implement 3 and/or the vehicle body 2.

The processes for detecting the setting the detection ranges 71 and 72 are not limited to the above embodiment and may be changed. The controller 37 may set the detection ranges for only one of the front and rear of the vehicle body 2. The controller 37 may set the first detection range 71 in front of the vehicle body 2 when the work machine 1 is traveling forward. The controller 37 may set the second detection range 72 to the rear of the vehicle body 2 when the work machine 1 is traveling in reverse.

The thresholds of the articulate angle θa, the steering angle θs, and the leaning angle θl for determining the process for changing the detection ranges 71 and 72 are not limited to zero and may be another value. For example, the threshold of the articulate angle θa may be a small value that allows the work machine 1 to be considered to be in the linear state. The threshold of the steering angle θs may be a small value that allows the work machine 1 to be considered not to be steered. The threshold of the leaning angle θl may be a small value that allows the work machine 1 to be considered not to be leaning. The changing of the detection ranges 71 and 72 in accordance with the leaning direction may be omitted.

The controller 37 may add an optional margin width that considers the tolerance of the detection to the abovementioned width Lall of the detection ranges 71 and 72. For example as illustrated in FIG. 25, the controller 37 may set the detection ranges 71 and 72 by adding margins Lt on the left and right of the reference ranges 73 and 74. The margin widths Lt on the right and left of the detection ranges 71 and 72 may be added in the same way for the detection ranges 71 and 72 determined in the abovementioned processes of the changes 1 to 9.

While the vehicle width in the front part and the vehicle width in the rear part of the vehicle body 2 are the same in the above embodiment, the vehicle widths in the front part and rear part of the vehicle body 2 may be different. In this case, the controller 37 may calculate the width of the first detection range 71 by using the vehicle width of the front part as the width of the first reference range 73. The controller 37 may calculate the width of the second detection range 72 by using the vehicle width of the rear part as the width of the second reference range 74.

According to the present invention, whether an object is present in the periphery of a work machine can be appropriately determined.

Claims

1. A work machine comprising: a vehicle body including a rear frame and a front frame connected to the rear frame so as to be pivotable left and right;a traveling wheel supported by the vehicle body;a steering actuator usable to steer the traveling wheel to the left and right;an articulate actuator usable to change an articulate angle between the rear frame and the front frame;a steering angle sensor configured to detect a steering angle of the traveling wheel;an articulate angle sensor configured to detect the articulate angle;an object sensor configured to detect an object in a periphery of the work machine and output a signal indicating a presence of the object; anda controller configured to set a detection range in the periphery of the work machine, anddetermine the presence of the object in the detection range based on the signal from the object sensor,the controller being configured to set the detection range in accordance with the steering angle and the articulate angle.

2. The work machine according to claim 1, wherein the controller is configured to set a reference range of the detection range based on a width of the vehicle body, andchange the detection range from the reference range in accordance with the articulate angle.

3. The work machine according to claim 2, wherein the controller is configured to curve the detection range in accordance with a turning radius of the work machine corresponding to the articulate angle when the work machine turns in accordance with the articulate angle.

4. The work machine according to claim 2, wherein the controller is configured to increase the detection range from the reference range in a left-right direction in accordance with the articulate angle when a direction of the articulate angle and a turning direction of the work machine are opposite.

5. The work machine according to claim 4, wherein the controller is configured to increase the detection range from the reference range on a same side as the rear frame with respect to the front frame in the left-right direction when the detection range is set in front of the front frame.

6. The work machine according to claim 4, wherein the controller is configured to increase the detection range from the reference range on a same side as the front frame with respect to the rear frame in a left-right direction when the detection range is set behind the rear frame.

7. The work machine according to claim 2, further comprising: a leaning actuator configured to change a leaning angle of the traveling wheel; anda leaning angle sensor configured to detect the leaning angle,the controller being configured to change the detection range from the reference range in accordance with the leaning angle.

8. The work machine according to claim 7, wherein the controller is configured to increase the detection range from the reference range in a same direction that the traveling wheel is leaning in a left-right direction.

9. The work machine according to claim 8, wherein the controller is configured not to increase the detection range corresponding to the leaning angle when a turning direction of the work machine and a direction of the articulate angle are in opposite directions anda direction that the traveling wheel is leaning matches the turning direction of the work machine.

10. A method for controlling a work machine, the work machine including a vehicle body that includes a rear frame and a front frame that is connected to the rear frame so as to be pivotable left and right, a traveling wheel supported by the vehicle body, a steering actuator for steering the traveling wheel to the left and right, and an articulate actuator for changing an articulate angle between the rear frame and the front frame, the method comprising: detecting a steering angle of the traveling wheel;detecting the articulate angle;receiving a signal indicating a presence of an object in a periphery of the work machine;setting a detection range in the periphery of the work machine in accordance with the steering angle and the articulate angle; anddetermining the presence of the object in the detection range based on the signal output by an object sensor.

11. The method according to claim 10, further comprising: setting a reference range of the detection range based on a width of the vehicle body; andchanging the detection range from the reference range in accordance with the articulate angle.

12. The method according to claim 11, further comprising: curving the detection range in accordance with a turning radius of the work machine corresponding to the articulate angle when the work machine turns in accordance with the articulate angle.

13. The method according to claim 11, further comprising: increasing the detection range from the reference range in a left-right direction in accordance with the articulate angle when a direction of the articulate angle and a turning direction of the work machine are opposite.

14. The method according to claim 13, further comprising: increasing the detection range from the reference range on a same side as the rear frame with respect to the front frame in the left-right direction when the detection range is set in front of the front frame.

15. The method according to claim 13, further comprising: increasing the detection range from the reference range on a same side as the front frame with respect to the rear frame in the left-right direction when the detection range is set behind the rear frame.

16. The method according to claim 11, wherein the work machine further includes a leaning actuator configured to change a leaning angle of the traveling wheel, and

17. The method according to claim 16, further comprising: increasing the detection range from the reference range in a same direction that the traveling wheel is leaning in a left-right direction.

18. The method according to claim 17, further comprising: not increasing the detection range corresponding to the leaning angle when a turning direction of the work machine and a direction of the articulate angle are in opposite directions anda direction that the traveling wheel is leaning matches the turning direction of the work machine.

19. A system for controlling a work machine, the work machine including a vehicle body that includes a rear frame and a front frame that is connected to the rear frame so as to be pivotable left and right, a traveling wheel supported by the vehicle body, a steering actuator for steering the traveling wheel to the left and right, and an articulate actuator for changing an articulate angle between the rear frame and the front frame, the system comprising: a steering angle sensor configured to detect a steering angle of the traveling wheel;an articulate angle sensor configured to detect the articulate angle;an object sensor configured to detect an object in a periphery of the work machine, and outputs a signal indicating a presence of the object; anda controller configured to set a detection range in the periphery of the work machine anddetermine the presence of the object in the detection range based on the signal from the object sensor,the controller being configured to set the detection range in accordance with the steering angle and the articulate angle.