A working machine, a method for controlling a working machine, and a system

Abstract

To provide a working machine with running wheels having leaning capability capable of improving driving stability.SOLUTION: The working machine includes a body, running wheels, a steering actuator, a leaning actuator, a leaning angle sensor, and a controller. The running wheels are supported by the body. The steering actuator changes the steering angle of the running wheels. The leaning actuator changes the leaning angle of the running wheels. The leaning angle sensor detects the leaning angle. The controller controls the steering actuator to execute the auto steering control to automatically steer the running wheels. The controller acquires the leaning angle. The controller restricts the running of the body according to the leaning angle or restricts the auto steering control.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a working machine, a method for controlling the working machine, and a system.

Background Art

[0002] Conventionally, in a working machine, a technique for automatically controlling the steering angle of a traveling wheel (hereinafter referred to as "autosteering control") is known. For example, in Patent Document 1, a control system generates a target path of a working machine and controls the steering angle so that the working machine moves along the target path.

[0003] In Patent Document 2, a controller of a working machine determines a target traveling direction of the working machine and controls the steering angle so that the working machine travels toward the target traveling direction. In Patent Document 3, a controller of a working machine determines a target change rate of the traveling direction. The controller of the working machine controls the steering angle so that the change rate of the traveling direction per unit travel distance is maintained at the target change rate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] The aforementioned work machine is equipped with a leaning mechanism that allows the driving wheels to lean from side to side. When auto-steering control is performed while the driving wheels are leaning from side to side, driving stability may decrease depending on the magnitude of the leaning angle. The object of the present invention is to improve driving stability in a work machine equipped with leaning driving wheels. [Means for solving the problem]

[0006] A work machine according to a first aspect of the present invention comprises a vehicle body, driving wheels, a steering actuator, a leaning actuator, a leaning angle sensor, and a controller. The driving wheels are supported by the vehicle body. The steering actuator changes the steering angle of the driving wheels. The leaning actuator changes the leaning angle of the driving wheels. The leaning angle sensor detects the leaning angle. The controller performs auto-steering control, which automatically steers the driving wheels by controlling the steering actuator. The controller acquires the leaning angle. The controller restricts the movement of the vehicle body or restricts the auto-steering control according to the leaning angle.

[0007] A second aspect of the present invention relates to a method for controlling a work machine. The work machine comprises a vehicle body, running wheels, a steering actuator, and a leaning actuator. The running wheels are supported by the vehicle body. The steering actuator changes the steering angle of the running wheels. The leaning actuator changes the leaning angle of the running wheels.

[0008] The method according to this embodiment includes performing auto-steering control, which automatically steers the driving wheels by controlling a steering actuator; acquiring a leaning angle; and restricting the vehicle's movement or restricting the auto-steering control according to the leaning angle.

[0009] A third aspect of the present invention is a system for controlling a work machine. The work machine comprises a vehicle body, running wheels, a steering actuator, and a leaning actuator. The running wheels are supported by the vehicle body. The steering actuator changes the steering angle of the running wheels. The leaning actuator changes the leaning angle of the running wheels.

[0010] The system according to this embodiment comprises a leaning angle sensor and a controller. The leaning angle sensor detects the leaning angle. The controller performs auto-steering control, which automatically steers the driving wheels by controlling the steering actuator. The controller acquires the leaning angle. The controller restricts the vehicle's movement or restricts the auto-steering control according to the leaning angle. [Effects of the Invention]

[0011] According to the present invention, the vehicle's movement is restricted or the auto-steering control is limited depending on the leaning angle. Therefore, when the leaning angle is large enough to reduce driving stability, the vehicle's movement can be restricted or the auto-steering control can be limited. This improves driving stability. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view of the work machine according to the embodiment. [Figure 2] This is a side view of the work machine. [Figure 3] This is a top view of the front of the work machine. [Figure 4] This is a front view of the front of the work machine. [Figure 5] This is a schematic diagram showing the configuration of the control system for a work machine. [Figure 6] This figure shows a directional control system, which is an example of auto steering control. [Figure 7] This flowchart shows the process of limit control performed by the controller. [Figure 8] It is a diagram showing automatic path following control which is another example of auto steering control.

Embodiments for Carrying Out the Invention

[0013] Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a working machine 1 according to an embodiment. FIG. 2 is a side view of the working machine 1. As shown in FIG. 1, the working machine 1 includes a vehicle body 2, traveling wheels 3A, 3B, 4A - 4D, and a working device 5. The vehicle body 2 includes a front frame 11, a rear frame 12, a cab 13, and a power chamber 14.

[0014] The rear frame 12 is connected to the front frame 11. The front frame 11 is pivotally connected to the rear frame 12 so as to be rotatable with respect to the rear frame 12. As will be described later, the front frame 11 can be articulated left and right with respect to the rear frame 12.

[0015] In the following description, the front, rear, left, and right directions are defined in a state where the articulation angle of the front frame 11 with respect to the rear frame 12 is zero, that is, in a state where the front frame 11 and the rear frame 12 are straight, for each of the front, rear, left, and right directions of the vehicle body 2.

[0016] The cab 13 and the power chamber 14 are arranged on the rear frame 12. A driver's seat (not shown) is arranged in the cab 13. The power chamber 14 is arranged behind the cab 13. The front frame 11 extends forward from the rear frame 12.

[0017] The traveling wheels 3A, 3B, 4A - 4D are rotatably supported by the vehicle body 2. The traveling wheels 3A, 3B, 4A - 4D include front wheels 3A, 3B and rear wheels 4A - 4D. The front wheels 3A, 3B are arranged apart from each other in the left - right direction. The front wheels 3A, 3B are attached to the front frame 11. The rear wheels 4A - 4D are attached to the rear frame 12.

[0018] The working machine 5 is movably connected to the vehicle body 2. The working machine 5 includes a support member 15 and a blade 16. The support member 15 is movably connected to the vehicle body 2. The support member 15 supports the blade 16. The support member 15 includes a drawbar 17 and a circle 18. The drawbar 17 is disposed below the front frame 11.

[0019] The drawbar 17 is connected to the front portion 19 of the front frame 11. The drawbar 17 extends rearward from the front portion 19 of the front frame 11. The drawbar 17 is supported by the front frame 11 so as to be swingable at least in the vertical direction and the lateral direction of the vehicle body 2. For example, the front portion 19 includes a ball joint. The drawbar 17 is rotatably connected to the front frame 11 via the ball joint.

[0020] The circle 18 is connected to the rear portion of the drawbar 17. The circle 18 is rotatably supported by 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 shown in FIG. 2, the blade 16 is rotatably supported by the circle 18 around a tilt axis 21. The tilt axis 21 extends in the lateral direction.

[0021] FIG. 3 is a top view of the front portion of the working machine 1. As shown in FIG. 3, the working machine 1 includes a first steering shaft 43A and a second steering shaft 43B. The first steering shaft 43A and the second steering shaft 43B are provided on the front frame 11. The first steering shaft 43A and the second steering shaft 43B extend in the vertical direction. The front wheel 3A is rotatably supported around the first steering shaft 43A. The front wheel 3B is rotatably supported around the second steering shaft 43B.

[0022] The work machine 1 is equipped with multiple steering actuators 41A and 41B for steering the front wheels 3A and 3B. The multiple steering actuators 41A and 41B are used to steer the front wheels 3A and 3B. For example, the multiple steering actuators 41A and 41B are hydraulic cylinders. The multiple steering actuators 41A and 41B are connected to the front wheels 3A and 3B, respectively. The multiple steering actuators 41A and 41B extend and retract hydraulically. In the following description, the extension and retraction of the multiple steering actuators 41A and 41B, for example, the extension and retraction of the hydraulic cylinders, will be referred to as "stroke motion".

[0023] The multiple steering actuators 41A, 41B include a left steering cylinder 41A and a right steering cylinder 41B. The left steering cylinder 41A and the right steering cylinder 41B are positioned apart from each other in the left-right direction.

[0024] The left steering cylinder 41A is connected to the front frame 11 and the front wheel 3A. The right steering cylinder 41B is connected to the front frame 11 and the front wheel 3B. The stroke action of the left steering cylinder 41A and the right steering cylinder 41B steers the front wheels 3A and 3B.

[0025] The working machine 1 includes an articulated shaft 44. The articulated shaft 44 is provided on the front frame 11 and the rear frame 12. The articulated shaft 44 extends in the vertical direction. The front frame 11 and the rear frame 12 are connected to each other so as to be rotatable around the articulated shaft 44.

[0026] The work machine 1 is equipped with a plurality of articulated actuators 27, 28. The plurality of articulated actuators 27, 28 are used to rotate the front frame 11 relative to the rear frame 12. For example, the plurality of articulated actuators 27, 28 are hydraulic cylinders. The plurality of articulated actuators 27, 28 are connected to the front frame 11 and the rear frame 12. The plurality of articulated actuators 27, 28 extend and retract hydraulically.

[0027] The multiple articulated actuators 27, 28 include a left articulated cylinder 27 and a right articulated cylinder 28. The left articulated cylinder 27 and the right articulated cylinder 28 are positioned apart from each other in the left-right direction.

[0028] The left articulated 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 articulated cylinder 28 is connected to the front frame 11 and the rear frame 12 on the right side of the vehicle body 2. The stroke action of the left articulated cylinder 27 and the right articulated cylinder 28 causes the front frame 11 to rotate left and right relative to the rear frame 12.

[0029] Figure 4 is a front view of the front of the work machine 1. As shown in Figure 4, the work machine 1 is equipped with a lean mechanism 6. The lean mechanism 6 tilts the front wheels 3A and 3B to the left and right. The lean mechanism 6 includes an axle beam 56, a leaning rod 57, and a leaning actuator 61. The axle beam 56 extends from the front frame 11 to the left and right. The axle beam 56 is supported on the front frame 11 so as to be rotatable around a pivot axis 58.

[0030] The axle beam 56 is connected to the front wheel 3A via the wheel bracket 59A. The axle beam 56 rotatably supports the front wheel 3A around the leaning axis 54A. The axle beam 56 is connected to the front wheel 3B via the wheel bracket 59B. The axle beam 56 rotatably supports the front wheel 3B around the leaning axis 54B. The leaning axes 54A and 54B extend in the longitudinal direction.

[0031] The leaning rod 57 extends from left to right through the front frame 11. The leaning rod 57 connects the front wheels 3A and 3B to each other. The leaning rod 57 is connected to the front wheel 3A via the wheel bracket 59A. The leaning rod 57 is connected to the front wheel 3B via the wheel bracket 59B.

[0032] The leaning actuator 61 is used to tilt the front wheels 3A and 3B. For example, the leaning actuator 61 is a hydraulic cylinder. The leaning actuator 61 is connected to the front frame 11 and the front wheels 3A and 3B. The leaning actuator 61 extends and retracts hydraulically. That is, by extending and retracting the leaning actuator 61, the front wheels 3A and 3B rotate around the leaning axes 54A and 54B. As a result, the front wheels 3A and 3B tilt to the left and right.

[0033] As shown in Figure 2, the work machine 1 is equipped with a plurality of actuators 22-26 for changing the posture of the work machine 5. For example, the plurality of actuators 22-25 are hydraulic cylinders. Actuators 26 are rotary actuators. In this embodiment, actuator 26 is a hydraulic motor. Actuator 26 may also be an electric motor.

[0034] Multiple actuators 22-25 are connected to the work implement 5. The multiple actuators 22-25 extend and retract hydraulically. By extending and retracting, the multiple actuators 22-25 change the posture of the work implement 5 relative to the vehicle body 2.

[0035] In detail, the multiple actuators 22-25 include a left lift cylinder 22, a right lift cylinder 23, a drawbar shift cylinder 24, and a blade tilt cylinder 25.

[0036] The left lift cylinder 22 and the right lift cylinder 23 are positioned apart 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 the lifter bracket 29. The stroke motion of the left lift cylinder 22 and the right lift cylinder 23 causes the drawbar 17 to swing up and down. As a result, the blade 16 moves up and down.

[0037] The drawbar shift cylinder 24 is connected to the drawbar 17 and the front frame 11. The drawbar shift cylinder 24 is connected to the front frame 11 via a lifter bracket 29. The drawbar shift cylinder 24 extends diagonally downward from the front frame 11 toward the drawbar 17. The stroke motion of the drawbar shift cylinder 24 causes the drawbar 17 to swing from side to side.

[0038] The blade tilt cylinder 25 is connected to the circle 18 and the blade 16. The stroke motion of the blade tilt cylinder 25 causes the blade 16 to rotate around the tilt axis 21.

[0039] The actuator 26 is connected to the drawbar 17 and the circle 18. The actuator 26 rotates the circle 18 relative to the drawbar 17. As a result, the blade 16 rotates around a rotation axis that extends in the vertical direction.

[0040] Figure 5 is a schematic diagram showing the configuration of the control system of the work machine 1. As shown in Figure 5, the work machine 1 includes a drive source 31, a hydraulic pump 32, and a power transmission device 33. The work machine 1 also includes a steering valve 42A, an articulate valve 42B, a leaning valve 42C, and a work machine valve 34. The drive source 31 is, for example, an internal combustion engine. Alternatively, the drive source 31 may be an electric motor, or a hybrid of an internal combustion engine and an electric motor.

[0041] The hydraulic pump 32 is driven by the drive source 31 and discharges hydraulic fluid. The hydraulic pump 32 supplies hydraulic fluid to the steering valve 42A, the articulate valve 42B, the leaning valve 42C, and the work machine valve 34. This operates multiple steering actuators 41A, 41B, multiple articulate actuators 27, 28, the leaning actuator 61, and multiple actuators 22-26. Although only one hydraulic pump 32 is shown in Figure 5, multiple hydraulic pumps may be provided.

[0042] The steering valve 42A is connected to the hydraulic pump 32 and a plurality of steering actuators 41A, 41B via a hydraulic circuit. The steering valve 42A controls the flow rate of hydraulic fluid supplied from the hydraulic pump 32 to the plurality of steering actuators 41A, 41B. The hydraulic fluid from the hydraulic pump 32 is supplied to the steering valve 42A, causing the plurality of steering actuators 41A, 41B to perform a stroke operation.

[0043] The articulated valve 42B is connected to the hydraulic pump 32 and the multiple articulated actuators 27 and 28 via a hydraulic circuit. The articulated valve 42B controls the flow rate of hydraulic fluid supplied from the hydraulic pump 32 to the multiple articulated actuators 27 and 28. The supply of hydraulic fluid from the hydraulic pump 32 to the articulated valve 42B causes the multiple articulated actuators 27 and 28 to perform a stroking motion.

[0044] The leaning valve 42C is connected to the hydraulic pump 32 and the leaning actuator 61 via a hydraulic circuit. The leaning valve 42C controls the flow rate of hydraulic fluid supplied from the hydraulic pump 32 to the leaning actuator 61. The supply of hydraulic fluid from the hydraulic pump 32 to the leaning valve 42C causes the leaning actuator 61 to perform a stroke motion.

[0045] The work equipment valve 34 is connected to the hydraulic pump 32 and a plurality of actuators 22-26 via a hydraulic circuit. The work equipment valve 34 includes a plurality of valves connected to each of the actuators 22-26. The work equipment valve 34 controls the flow rate of hydraulic fluid supplied from the hydraulic pump 32 to the plurality of actuators 22-26.

[0046] The power transmission device 33 transmits the driving force from the drive source 31 to the rear wheels 4A-4D. The power transmission device 33 may include a torque converter and / or multiple transmission gears. Alternatively, the power transmission device 33 may be a transmission such as an HST (Hydraulic Static Transmission) or an HMT (Hydraulic Mechanical Transmission). The power transmission device 33 is switchable to multiple speed gears. The multiple speed gears may include, for example, forward 1st to 4th speeds. The multiple speed gears may also include, for example, reverse 1st to 4th speeds. However, the number of speed gears is not limited to these and may be changed.

[0047] The work machine 1 includes a steering operating member 45, an articulating operating member 46, a leaning operating member 47, a work machine operating member 48, a shift operating member 49, and an accelerator operating member 50.

[0048] The steering control member 45 is operable by the operator to steer the front wheels 3A and 3B. The steering control member 45 is a lever such as a joystick. Alternatively, the steering control member 45 may be a member other than a lever. For example, the steering control member 45 may be a steering wheel. The steering control member 45 outputs a steering operation signal indicating the operator's operation of the steering control member 45.

[0049] The articulated operating member 46 is operable by an operator to rotate the front frame 11 relative to the rear frame 12. The articulated operating member 46 is a lever such as a joystick. Alternatively, the articulated operating member 46 may be a member other than a lever. The articulated operating member 46 outputs an articulated operation signal indicating operation by the operator on the articulated operating member 46.

[0050] The leaning control member 47 is operable by the operator to tilt the front wheels 3A and 3B. The leaning control member 47 is a lever such as a joystick. Alternatively, the leaning control member 47 may be a member other than a lever. The leaning control member 47 outputs a leaning operation signal indicating the operator's operation of the leaning control member 47.

[0051] The work implement operating member 48 is operable by the operator to change the posture 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 a switch or other component such as a touch panel. The work implement operating member 48 outputs a signal indicating operation by the operator to the work implement operating member 48.

[0052] The shift operating member 49 is operable by an operator to switch between forward and reverse movement of the work machine 1. The shift operating member 49 includes, for example, a shift lever. Alternatively, the shift operating member 49 may be other components such as a switch or a touch panel. The shift operating member 49 outputs a signal indicating operation by the operator to the shift operating member 49.

[0053] The accelerator operating member 50 is operable by an operator to move the work machine 1. The accelerator operating member 50 includes, for example, an accelerator pedal. Alternatively, the accelerator operating member 50 may be other components such as a switch or a touch panel. The accelerator operating member 50 outputs a signal indicating operation by the operator to the accelerator operating member 50.

[0054] The work machine 1 is equipped with a steering angle sensor 51, an articulate angle sensor 52, and a leaning angle sensor 53. The steering angle sensor 51 is used to detect the steering angle θ1 of the front wheels 3A and 3B. The steering angle sensor 51 outputs a steering angle signal indicating the steering angle θ1. The steering angle signal is, for example, the stroke amount of the multiple steering actuators 41A and 41B. Alternatively, the steering angle sensor 51 may directly detect the steering angle θ1.

[0055] As shown in Figure 3, the steering angle θ1 is the angle at which the front wheels 3A and 3B rotate relative to the front frame 11 around the first steering axis 43A and the second steering axis 43B. More specifically, the steering angle θ1 is the rotation angle of the front wheels 3A and 3B with respect to the first centerline L1 of the front frame 11. The first centerline L1 extends in the longitudinal direction of the front frame 11.

[0056] The steering angle θ1 changes from the neutral position to the left or right due to the stroke movement of multiple steering actuators 41A and 41B. The steering angle θ1 in the neutral position is zero degrees. In the neutral position, the front wheels 3A and 3B are positioned parallel to the first centerline L1 of the front frame 11. In Figure 3, 3A' and 3B' show the front wheels when they are steered to the right by a steering angle θ1 from the neutral position.

[0057] The articulated angle sensor 52 is used to detect the articulated angle of the front frame 11 relative to the rear frame 12. The articulated angle sensor 52 outputs an articulated angle signal indicating the articulated angle θ2. The articulated angle signal is, for example, the stroke amount between the left articulated cylinder 27 and the right articulated cylinder 28. Alternatively, the articulated angle sensor 52 may directly detect the articulated angle θ2.

[0058] As shown in Figure 3, the articulation angle θ2 is the angle at which the front frame 11 rotates relative to the rear frame 12 around the articulation axis 44. More specifically, the articulation angle θ2 is the angle formed by the first centerline L1 of the front frame 11 and the second centerline L2 of the rear frame 12.

[0059] The second centerline L2 extends in the front-rear direction of the rear frame 12. The second centerline L2 passes through the articulation axis 44 when viewed from above the work machine 1. The articulation angle θ2 changes from the neutral position to the left and right. The articulation angle θ2 at the neutral position is zero. When the articulation angle θ2 is zero, the direction of the second centerline L2 coincides with the direction of the first centerline L1. Note that Figure 3 shows the front frame 11 rotated by an articulation angle θ2 around the articulation axis 44.

[0060] The leaning angle sensor 53 is used to detect the leaning angle θ3 of the front wheels 3A and 3B. The leaning angle sensor 53 outputs a leaning angle signal indicating the leaning angle θ3. The leaning angle signal is, for example, the stroke amount of the leaning actuator 61. Alternatively, the leaning angle sensor 53 may directly detect the leaning angle θ3.

[0061] As shown in Figure 4, the leaning angle θ3 is the angle of tilt of the front wheels 3A and 3B in the left-right direction when viewed from the front of the vehicle body 2. For example, the leaning angle θ3 is the angle of tilt of the front wheels 3A and 3B around the leaning axes 54A and 54B when viewed from the front of the vehicle body 2. In the following explanation, the state in which the front wheels 3A and 3B are upright relative to the horizontal plane (shown by solid lines 3A and 3B) will be referred to as the neutral position of the front wheels 3A and 3B. When the front wheels 3A and 3B are in the neutral position, the leaning angle θ3 is zero degrees. In Figure 4, 3A' and 3B' represent the front wheels tilted to the left from the neutral position by a leaning angle θ3.

[0062] As shown in Figure 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, which executes a program for controlling the work machine 1. The storage device 38 includes memory such as RAM and ROM, and auxiliary storage such as an SSD or HDD. The storage device 38 stores the program and data for controlling the work machine 1.

[0063] The controller 37 controls the power transmission device 33 in response to the operation of the shift operating member 49. This switches the direction of travel of the work machine 1 between forward and reverse. It also switches the speed gear of the power transmission device 33. Alternatively, the shift operating member 49 may be mechanically connected to the power transmission device 33. By mechanically transmitting the operation of the shift operating member 49 to the power transmission device 33, the forward and reverse gears, or the variable gear, of the power transmission device 33 may be switched.

[0064] The controller 37 controls the drive source 31 and the power transmission device 33 in response to the operation of the accelerator operating member 50. This causes the work machine 1 to move. The controller 37 also controls the hydraulic pump 32 and the work machine valve 34 in response to the operation of the work machine operating member 48. This causes the work machine 5 to operate.

[0065] The controller 37 acquires the amount of movement of the steering control member 45 based on the steering control signal from the steering control member 45. The controller 37 extends and retracts multiple steering actuators 41A and 41B by controlling the steering valve 42A in response to the steering control signal. As a result, the controller 37 changes the steering angle θ1 of the front wheels 3A and 3B. The controller 37 acquires the steering angle signal from the steering angle sensor 51. The controller 37 calculates the steering angle θ1 of the front wheels 3A and 3B based on the steering angle signal.

[0066] The controller 37 obtains the amount of movement of the articulated operating member 46 based on the articulated operating signal from the articulated operating member 46. The controller 37 controls the articulated valve 42B. For example, the controller 37 extends and retracts the left articulated cylinder 27 and the right articulated cylinder 28 by controlling the articulated valve 42B in response to the articulated operating signal. This causes the controller 37 to change the articulated angle. The controller 37 obtains the articulated angle signal from the articulated angle sensor 52. The controller 37 calculates the articulated angle θ2 based on the articulated angle signal.

[0067] The controller 37 obtains the amount of operation of the leaning operating member 47 based on the leaning operation signal from the leaning operating member 47. The controller 37 controls the leaning valve 42C. For example, the controller 37 extends or retracts the leaning actuator 61 by controlling the leaning valve 42C in response to the leaning operation signal. In this way, the controller 37 changes the leaning angle θ3 in response to the operator's operation of the leaning operating member 47. The controller 37 obtains the leaning angle signal from the leaning angle sensor 53. The controller 37 calculates the leaning angle θ3 based on the leaning angle signal.

[0068] The work machine 1 is equipped with a direction sensor 62. The direction sensor 62 detects the direction of travel of the vehicle body 2. The direction sensor 62 outputs a direction signal indicating the direction of travel of the vehicle body 2. The controller 37 obtains the direction of travel of the vehicle body 2 from the direction signal from the direction sensor 62. The direction of travel of the vehicle body 2 is indicated, for example, by the yaw angle of the vehicle body 2.

[0069] The direction sensor 62 is, for example, an IMU (Inertial Measurement Unit). The controller 37 calculates the direction of travel of the vehicle body 2 based on the acceleration and angular velocity of the vehicle body 2. Alternatively, the direction sensor 62 may be a GNSS (Global Navigation Satellite System) position sensor such as a GPS (Global Positioning System). The controller 37 may also obtain the direction of travel of the vehicle body 2 from the change in position of the work machine 1 detected by the direction sensor 62.

[0070] The work machine 1 is equipped with an input device 63. The input device 63 is operable by the operator to set the auto-steering control on or off. In auto-steering control, the controller 37 automatically steers the front wheels 3a and 3B by controlling the steering actuators 41A and 41B. The input device 63 is, for example, a switch. Alternatively, the input device 63 may be another device operable by the operator, such as a touchscreen. When the auto-steering control is set to on by the input device 63, the controller 37 performs auto-steering control.

[0071] Figure 6 shows a diagram of a direction-keeping control, which is an example of auto-steering control. In direction-keeping control, the controller 37 determines the target direction of travel for the work machine 1 and controls the steering angle so that the work machine 1 travels in the target direction. For example, as shown in Figure 6, the work machine 1 is at position P1, the steering operating member 45 is in the neutral position N1, and the steering angle θ1 is zero.

[0072] When the operator moves the work machine 1 forward and manually operates the steering control member 45 to the left, the work machine 1 turns to the left and moves from position P1, through position P2, to position P3, and the steering angle θ1 is changed to θmax to the left. When the operator returns the steering control member 45 to the neutral position N1 at position P4, or operates it in the opposite direction, the steering angle θ1 returns to zero at position P5, and the work machine 1 starts moving in a straight line.

[0073] For example, the controller 37 stores the fact that the steering angle θ1 has returned to zero after the steering operating member 45 has been operated from the neutral position N1 as the start condition for direction-keeping control. However, the start condition for direction-keeping control is not limited to the steering angle θ1 returning to zero. The start condition for direction-keeping control may also be a command to start direction-keeping control, such as when a predetermined operation button is pressed by the operator. The controller 37 acquires the direction of travel of the work machine 1 when the start condition is met from the direction signal from the direction sensor 62. The controller 37 then sets the direction of travel of the work machine 1 when the start condition is met as the target direction of travel. That is, as shown in Figure 6, the controller 37 determines the direction of travel H1 of the work machine 1 at position P5 as the target direction of travel. The controller 37 controls the steering angle θ1 so that the direction of travel of the work machine 1 is maintained at the target direction of travel H1.

[0074] In addition, in auto-steering control, the travel speed of the work machine 1 may be adjusted manually using the accelerator operating member 50, or it may be adjusted automatically by the controller 37. The starting condition for direction-keeping control may be that the steering operating member 45 returns to the neutral position N1 at position P4.

[0075] If the auto-steering control described above is performed while the front frame 11 is significantly articulated from the neutral position relative to the rear frame 12, driving stability may decrease. Similarly, if the auto-steering control described above is performed while the front wheels 3A and 3B are significantly leaned from the neutral position, driving stability may decrease. Therefore, in the control system of the work machine 1 according to this embodiment, the controller 37 performs limiting control to restrict the auto-steering control according to the articulation angle θ2 and the leaning angle θ3.

[0076] Figure 7 is a flowchart showing the limit control process performed by the controller 37. As shown in Figure 7, in step S1, the controller 37 acquires the articulation angle θ2. The controller 37 acquires the articulation angle θ2 based on the articulation angle signal from the articulation angle sensor 52.

[0077] In step S2, the controller 37 acquires the leaning angle θ3. The controller 37 acquires the leaning angle θ3 based on the leaning angle signal from the leaning angle sensor 53.

[0078] In step S3, the controller 37 determines whether the articulation angle θ2 is within a first range. The first range represents the range of articulation angle θ2 in which good driving stability can be ensured. The first range includes the neutral position and is the range between the upper limit to the left and the upper limit to the right of the articulation angle θ2. If the articulation angle θ2 is within the first range, the process proceeds to step S4.

[0079] In step S4, the controller 37 determines whether the leaning angle θ3 is within the second range. The second range indicates the range of leaning angle θ3 in which good driving stability can be ensured. The second range includes the neutral position and is the range between the upper limit to the left and the upper limit to the right of the leaning angle θ3. If the leaning angle θ3 is within the second range, the process proceeds to step S5. In step S5, the controller 37 performs the auto steering control described above as normal control.

[0080] On the other hand, if the articulation angle θ2 is outside the first range in step S3, the process proceeds to step S6. For example, if the articulation angle θ2 is greater than the upper limit to the left, the process proceeds to step S6. Alternatively, if the articulation angle θ2 is greater than the upper limit to the right, the process proceeds to step S6.

[0081] In step S6, the controller 37 performs limit control. In limit control, the controller 37 disables auto steering control regardless of the operation of the input device 63. Therefore, if the articulate angle θ2 is outside the first range, even if auto steering control is set to ON by the input device 63 and the above-described start conditions are met, the controller 37 will not start auto steering control. Furthermore, during limit control, the controller 37 will notify the operator that auto steering control is disabled. Any known means can be used as a means of notification, such as displaying a warning lamp or generating a warning sound.

[0082] Similarly, if the leaning angle θ3 is outside the second range in step S4, the process proceeds to step S6, and the controller 37 performs limit control. For example, if the leaning angle θ3 is greater than the upper limit to the left, the controller 37 performs limit control. If the leaning angle θ3 is greater than the upper limit to the right, the controller 37 performs limit control.

[0083] In the work machine 1 according to this embodiment described above, if the articulation angle θ2 is outside the first range, the auto-steering control is restricted by the limiting control. Therefore, if the articulation angle θ2 is large enough to reduce driving stability, the auto-steering control is restricted. As a result, driving stability is improved.

[0084] Furthermore, if the leaning angle θ3 is outside the second range, the auto-steering control is restricted by the limiting control. Therefore, if the leaning angle θ3 is large enough to reduce driving stability, the auto-steering control is restricted. This improves driving stability.

[0085] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the invention.

[0086] The configuration of the work machine 1 is not limited to those described above and may be changed. For example, the configuration of the work machine 5 may be changed. Part of the control system of the work machine 1 may be located outside the work machine 1. For example, the various operating members and input device 63 of the work machine 1 may be located outside the work machine 1.

[0087] The controller 37 may be composed of multiple controllers. The processing described above may be distributed and executed across multiple controllers. Some of the multiple controllers may be located outside the work machine 1.

[0088] Auto steering control is not limited to the direction-keeping control described above; other types of control may also be used. For example, auto steering control may be automatic path-following control. In automatic path-following control, the controller 37 controls the steering angle θ1 so that the work machine 1 moves according to the target path.

[0089] Figure 8 shows an example of auto steering control, which is automatic path following control. As shown in Figure 8, the controller 37 acquires the target path R1. The controller 37 may also acquire the target path R1 from an external computer. The controller 37 starts automatic path following control (auto steering control) when a command to start control is received, such as when a predetermined operation button is pressed by the operator. Alternatively, the controller 37 may generate the target path R1 in response to the operation of the input device 63. In automatic path following control, the controller 37 controls the steering angle θ1 so that the work machine 1 moves according to the target path R1. The normal control and limit control in auto steering control have been explained using Figure 7, so the explanation is omitted here.

[0090] In the above embodiment, the controller 37 disables auto steering control in the limit control. However, the limit control is not limited to that of the above embodiment and may be modified.

[0091] For example, in limit control, the controller 37 may limit the movement of the vehicle body 2. In limit control, the controller 37 may limit the upper limit of the speed stage of the power transmission device 33. In normal control of auto steering control, the controller 37 may set the upper limit of the forward speed stage of the power transmission device 33 to the third gear. In limit control, the controller 37 may set the upper limit of the forward speed stage of the power transmission device 33 to the second gear. In normal control of auto steering control, the controller 37 may set the upper limit of the reverse speed stage of the power transmission device 33 to the third gear. In limit control, the controller 37 may set the upper limit of the reverse speed stage of the power transmission device 33 to the second gear.

[0092] The controller 37 may limit the upper limit of the vehicle speed of the work machine 1 in the limit control. For example, in the normal control of the auto steering control, the controller 37 may set the upper limit of the vehicle speed of the work machine 1 as a first upper limit vehicle speed. In the limit control, the controller 37 may set the upper limit of the vehicle speed of the work machine 1 as a second upper limit vehicle speed which is smaller than the first upper limit vehicle speed.

[0093] In the above embodiment, the controller 37 performs limit control even when the articulation angle θ2 is outside the first range. However, limit control according to the articulation angle θ2 may be omitted. [Industrial applicability]

[0094] According to the present invention, the running stability of a work machine equipped with leaning wheels is improved. [Explanation of Symbols]

[0095] 2: Vehicle body 3a,3B: Front wheel 33: Power transmission device 37: Controller 41A, 41B: Steering actuator 53: Leaning angle sensor 61: Leaning Actuator 63: Input device θ3: Leaning angle

Claims

1. The car body and, The running wheels supported by the vehicle body, A steering actuator that changes the steering angle of the aforementioned driving wheels, A leaning actuator that changes the leaning angle of the aforementioned running wheels, A leaning angle sensor for detecting the leaning angle, A controller that performs auto-steering control by controlling the steering actuator, which automatically steers the driving wheels, Equipped with, The aforementioned controller, The leaning angle is obtained, If the leaning angle is outside a predetermined range, the vehicle's movement is restricted, or the auto-steering control is restricted. The predetermined range includes the neutral position and is the range between the upper limit of the leaning angle to the left and the upper limit of the leaning angle to the right. A type of machinery used for industrial work.

2. The aforementioned work machine further includes a power transmission device that can be switched between multiple speed settings, The controller limits the upper limit of the plurality of speed stages when the leaning angle is outside the predetermined range. The work machine according to claim 1.

3. The controller limits the upper limit of the vehicle speed of the work machine when the leaning angle is outside the predetermined range. The work machine according to claim 1.

4. The controller disables the auto steering control when the leaning angle is outside the predetermined range. The work machine according to claim 1.

5. The system further includes an operable input device for setting the auto steering control to on or off. Regardless of the operation of the input device, the controller disables the auto steering control when the leaning angle is outside the predetermined range. The work machine according to claim 4.

6. A method for controlling a work machine, wherein the work machine comprises a vehicle body, running wheels supported by the vehicle body, a steering actuator for changing the steering angle of the running wheels, and a leaning actuator for changing the leaning angle of the running wheels, and the method is By controlling the steering actuator, auto steering control is performed to automatically steer the wheels. Obtaining the aforementioned leaning angle, When the leaning angle is outside a predetermined range, the vehicle's movement is restricted, or the auto-steering control is restricted. Equipped with, The predetermined range includes the neutral position and is the range between the upper limit of the leaning angle to the left and the upper limit of the leaning angle to the right. method.

7. The aforementioned work machine further includes a power transmission device that can be switched between multiple speed settings, The system further includes limiting the upper limit of the plurality of speed stages when the leaning angle is outside the predetermined range. The method according to claim 6.

8. The system further includes limiting the upper limit of the vehicle speed of the work machine when the leaning angle is outside the predetermined range. The method according to claim 6.

9. The system further includes disabling the auto steering control when the leaning angle is outside the predetermined range. The method according to claim 6.

10. The auto steering control is turned on or off in response to the operation of the input device, Regardless of the operation of the input device, if the leaning angle is outside the predetermined range, the auto steering control is disabled. Furthermore, The method according to claim 9.

11. A system for controlling a work machine, wherein the work machine comprises a vehicle body, running wheels supported by the vehicle body, a steering actuator for changing the steering angle of the running wheels, and a leaning actuator for changing the leaning angle of the running wheels. The aforementioned system, A leaning angle sensor for detecting the leaning angle, A controller that performs auto-steering control by controlling the steering actuator, which automatically steers the driving wheels, Equipped with, The aforementioned controller, The leaning angle is obtained, If the leaning angle is outside a predetermined range, the vehicle's movement is restricted, or the auto-steering control is restricted. The predetermined range includes the neutral position and is the range between the upper limit of the leaning angle to the left and the upper limit of the leaning angle to the right. system.

12. The aforementioned work machine further includes a power transmission device that can be switched between multiple speed settings, The controller limits the upper limit of the plurality of speed stages when the leaning angle is outside the predetermined range. The system according to claim 11.

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