Work machine and method for controlling a work machine

Abstract

A work machine includes a vehicle body, traveling wheels, a steering member, an actuator, and a controller. The steering member is operable in a left steering range, a right steering range, and a neutral range. In a case where the steering member is located in the neutral range, the actuator sets a steering angle of the traveling wheels to a predetermined neutral angle. The actuator changes the steering angle from the neutral angle to left and right, in accordance with an operation of the steering member. When the steering member is operated from the left steering range or the right steering range to the neutral range, the controller determines whether the steering angle returns to the neutral angle. The controller determines a traveling direction of the vehicle body at a time when the steering angle returns to the neutral angle as a target direction. The controller controls the actuator so that the traveling direction of the vehicle body is maintained on the target direction.

Description

Technical Field

[0001] This invention relates to working machinery and methods for controlling working machinery. Background Technology

[0002] The work machinery is equipped with steering components such as a steering wheel or steering lever for turning the wheels left and right. The steering components can be operated left and right from the neutral position. By operating the steering components, the operator of the work machinery changes the steering angle of the wheels from the neutral angle to the left or right. Thus, the work machinery turns left or right.

[0003] During operation, the load of sand or uneven road surface can easily cause machinery to deviate from its intended path. Therefore, operators must simultaneously operate the steering components while operating the bulldozer and other machinery to maintain the intended path. This operation is challenging and places a significant burden on the operator.

[0004] Therefore, Patent Document 1 discloses an automatic steering control system that automatically controls the steering angle to maintain the direction of travel of the working machinery. In this automatic steering control system, the orientation of the working machinery is determined as the target direction when the steering operation component stops. Moreover, the steering angle is automatically controlled to make the working machinery travel straight in the target direction.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2021-054269 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] However, as in Patent Document 1, when the working machine is traveling straight in the direction of the machine when the steering control component stops, the operator may sometimes experience discomfort from the machine's movement. The object of this invention is to reduce the operator's workload and discomfort by automatically controlling the steering angle.

[0010] means for solving problems

[0011] The working machine in the first aspect of the present invention includes a vehicle body, driving wheels, a steering component, an actuator, an operation sensor, a steering angle sensor, a direction sensor, and a controller. The driving wheels are supported on the vehicle body. The steering component is operable in a left steering range, a right steering range, and a neutral range. The neutral range is located between the left and right steering ranges. When the steering component is in the neutral range, the actuator uses the steering angle of the driving wheels as a predetermined neutral angle. Depending on the operation of the steering component, the actuator causes the steering angle to change left or right from the neutral angle. The operation sensor outputs an operation signal indicating the operation of the steering component. The steering angle sensor outputs an angle signal indicating the steering angle. The direction sensor outputs a direction signal detecting the travel direction of the vehicle body.

[0012] The controller acquires operation signals, angle signals, and direction signals. When the steering component moves from the left or right steering range to the neutral range, the controller determines whether the steering angle has returned to the neutral angle. The controller determines the travel direction when the steering angle returns to the neutral angle as the target direction. The controller controls the drive to keep the travel direction in the target direction.

[0013] The second aspect of the present invention is a method for controlling a working machine. The working machine includes a vehicle body, traveling wheels, and an actuator. The traveling wheels are supported on the vehicle body. The actuator causes the steering angle of the traveling wheels to change left or right from a predetermined neutral angle. The method in this aspect includes: acquiring an operation signal indicating the operation of a steering component capable of operating within a left steering range, a right steering range, or a neutral range between the left and right steering ranges; controlling the actuator to make the steering angle a predetermined neutral angle when the steering component is in the neutral range; controlling the actuator to change the steering angle left or right from the neutral angle according to the operation of the steering component; acquiring an angle signal indicating the steering angle; acquiring a direction signal detecting the travel direction of the vehicle body; determining whether the steering angle has returned to the neutral angle when the steering component operates from the left or right steering range to the neutral range; determining the travel direction when the steering angle is determined to have returned to the neutral angle as a target direction; and controlling the actuator to maintain the travel direction in the target direction.

[0014] Invention Effects

[0015] In this invention, the actuator is controlled to maintain the vehicle's direction of travel in the target direction. Furthermore, the vehicle's direction of travel is determined as the target direction not when the steering component is operated to the neutral range, but when the steering angle returns to the neutral angle. Therefore, the working machine is controlled to travel straight in the direction of travel when the steering angle actually returns to the neutral angle. This reduces the operator's workload and discomfort. Attached Figure Description

[0016] Figure 1It is a perspective view of the operating machinery for the implementation method.

[0017] Figure 2 This is a side view of the operating machinery.

[0018] Figure 3 This is a schematic diagram showing the structure of the operating machinery.

[0019] Figure 4 It is a top view showing the front of the machine.

[0020] Figure 5 This is a graph representing an example of steering speed data.

[0021] Figure 6 This diagram illustrates an example of how a work machine is driven by operating a first steering component.

[0022] Figure 7 This is a flowchart illustrating the process used to determine the start of automatic control. Detailed Implementation

[0023] The embodiments of the present invention will now be described with reference to the accompanying drawings. Figure 1 This is a perspective view of the operating machinery 1 in the implementation method. Figure 2 This is a side view of machine 1. (Example) Figure 1 As shown, the working machine 1 includes a body 2, front wheels 3A and 3B, rear wheels 4A-4D, and a working machine 5. The body 2 includes a front frame 11, a rear frame 12, a driver's cab 13, and a power compartment 14.

[0024] The rear frame 12 is connected to the front frame 11. The front frame 11 can engage with the rear frame 12 in the left and right directions. Furthermore, in the following description, the engagement angle in each direction (front, back, left, and right) is 0, which means that the front frame 11 and the rear frame 12 are in a straight position in each direction of the vehicle body 2.

[0025] The driver's compartment 13 and the engine compartment 14 are mounted on the rear frame 12. The driver's compartment 13 is equipped with a driver's seat (not shown). The engine compartment 14 is located behind the driver's compartment 13. The front frame 11 extends forward from the rear frame 12. The front wheels 3A and 3B are mounted on the front frame 11. The rear wheels 4A-4D are mounted on the rear frame 12.

[0026] The work machine 5 is movably connected to the vehicle body 2. The work machine 5 includes a support member 15 and a bulldozer blade 16. The support member 15 is movably connected to the vehicle body 2. The support member 15 supports the bulldozer blade 16. The support member 15 includes a drawbar 17 and a rotary disc 18. The drawbar 17 is located below the front frame 11.

[0027] The tow bar 17 is connected to the front portion 19 of the front frame 11. The tow bar 17 extends rearward from the front portion 19 of the front frame 11. The tow bar 17 is pivotally supported relative to the front frame 11, at least in the vertical and horizontal directions of the vehicle body 2. For example, the front portion 19 includes a ball joint. The tow bar 17 is rotatably connected to the front frame 11 via the ball joint.

[0028] A rotating disk 18 is connected to the rear of the drawbar 17. The rotating disk 18 is rotatably supported on the drawbar 17. A bulldozer blade 16 is connected to the rotating disk 18. The bulldozer blade 16 is supported on the drawbar 17 via the rotating disk 18. Figure 2 As shown, the bulldozer blade 16 is rotatably supported on the rotary disk 18 about the inclined axis 21. The inclined axis 21 extends laterally to the left and right.

[0029] The working machine 1 includes multiple actuators 22-26 for changing the posture of the working machine 5. Each actuator 22-26 includes multiple hydraulic cylinders 22-25. The multiple hydraulic cylinders 22-25 are connected to the working machine 5. The multiple hydraulic cylinders 22-25 extend and retract hydraulically. The extension and retraction of the multiple hydraulic cylinders 22-25 changes the posture of the working machine 5 relative to the vehicle body 2. In the following description, the extension and retraction of the hydraulic cylinders is referred to as "stroke action".

[0030] In detail, the multiple hydraulic cylinders 22-25 include a left lifting cylinder 22, a right lifting cylinder 23, a drawbar switching cylinder 24, and a bulldozer blade tilting hydraulic cylinder 25. The left lifting cylinder 22 and right lifting cylinder 23 are arranged separately on the left and right sides, facing upwards. The left and right lifting cylinders 22 and 23 are connected to the drawbar 17. The left and right lifting cylinders 22 and 23 are connected to the front frame 11 via a lifting bracket 29. The drawbar 17 swings up and down due to the stroke of the left and right lifting cylinders 22 and 23. This causes the bulldozer blade 16 to move up and down.

[0031] A drawbar conversion cylinder 24 is connected to the drawbar 17 and the front frame 11. The drawbar conversion cylinder 24 is connected to the front frame 11 via a lifting bracket 29. The drawbar conversion cylinder 24 extends diagonally downwards from the front frame 11 toward the drawbar 17. The drawbar 17 swings left and right according to the stroke of the drawbar conversion cylinder 24. A bulldozer blade tilting hydraulic cylinder 25 is connected to the rotary table 18 and the bulldozer blade 16. The bulldozer blade 16 rotates around the tilting axis 21 according to the stroke of the bulldozer blade tilting hydraulic cylinder 25.

[0032] Multiple actuators 22-26 include a rotary actuator 26. The rotary actuator 26 is connected to the drawbar 17 and the rotary disk 18. The rotary actuator 26 rotates the rotary disk 18 relative to the drawbar 17. As a result, the bulldozer blade 16 rotates about a rotation axis extending in the vertical direction.

[0033] Figure 3 This is a schematic diagram showing the structure of the operating machinery 1. For example... Figure 3As shown, the working machine 1 includes a drive source 31, a first hydraulic pump 32, a power transmission device 33, and a working 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. The first hydraulic pump 32 discharges working oil by being driven by the drive source 31.

[0034] The working machine valve 34 is connected via a hydraulic circuit to the first hydraulic pump 32 and a plurality of hydraulic cylinders 22-25. The working machine valve 34 includes a plurality of valves respectively connected to the plurality of hydraulic cylinders 22-25. The working machine valve 34 controls the flow rate of working oil supplied from the first hydraulic pump 32 to the plurality of hydraulic cylinders 22-25. The working machine valve 34 is, for example, an electromagnetic proportional control valve. Alternatively, the working machine valve 34 may also be a hydraulically pilot-operated proportional control valve.

[0035] In this embodiment, the rotary actuator 26 is a hydraulic motor. A working valve 34 is connected to the first hydraulic pump 32 and the rotary actuator 26 via a hydraulic circuit. The working valve 34 controls the flow rate of working oil supplied from the first hydraulic pump 32 to the rotary actuator 26. Alternatively, the rotary actuator 26 may also be an electric motor.

[0036] 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 also include a torque converter and / or multiple transmission gears. Alternatively, the power transmission device 33 may be a transmission such as HST (Hydraulic Static Transmission) or HMT (Hydraulic Mechanical Transmission).

[0037] The work machine 1 includes a work machine operating component 35, a gear shifting component 53, an accelerator operating component 36, and a controller 37. The work machine operating component 35 can be operated by an operator to change the posture of the work machine 5. The work machine operating component 35 includes, for example, multiple control levers. Alternatively, the work machine operating component 35 can also be other components such as a switch or a touch panel. The work machine operating component 35 outputs signals indicating the operator's operation of the work machine operating component 35.

[0038] The shift mechanism 53 can be operated by an operator to switch the forward and reverse movement of the working machine 1. The shift mechanism 53 includes, for example, a gear lever. Alternatively, the shift mechanism 53 can also be other components such as a switch or a touch panel. The shift mechanism 53 outputs a signal indicating the operator's operation of the shift mechanism 53. The accelerator operating mechanism 36 can be operated by an operator to move the working machine 1. The accelerator operating mechanism 36 includes, for example, an accelerator pedal. Alternatively, the accelerator operating mechanism 36 can also be other components such as a switch or a touch panel. The accelerator operating mechanism 36 outputs a signal indicating the operator's operation of the accelerator operating mechanism 36.

[0039] The controller 37 controls the power transmission device 33 according to the operation of the shifting component 53, thereby switching the forward and reverse movement of the working machine 1. Alternatively, the shifting component 53 can also be mechanically connected to the power transmission device 33. The forward and reverse gears of the power transmission device 33 can also be switched by mechanically transmitting the action of the shifting component 53 to the power transmission device 33.

[0040] The controller 37 controls the drive source 31 and the power transmission device 33 according to the operation of the accelerator operating component 36, thereby causing the working machine 1 to move. In addition, the controller 37 controls the first hydraulic pump 32 and the working machine valve 34 according to the operation of the working machine operating component 35, thereby causing the working machine 5 to operate.

[0041] The controller 37 includes a storage device 38 and a processor 39. The processor 39 is, for example, a CPU, which executes programs for controlling the machine 1. The storage device 38 includes RAM and ROM, as well as auxiliary storage devices such as SSDs or HDDs. The storage device 38 stores programs and data for controlling the machine 1.

[0042] The operating machinery 1 is equipped with a direction sensor 52. The direction sensor 52 detects the travel direction of the vehicle body 2. The direction sensor 52 outputs a direction signal representing the travel direction of the vehicle body 2. The controller 37 obtains the travel direction of the vehicle body 2 from the direction signal from the direction sensor 52. The travel direction of the vehicle body 2 is represented, for example, by the yaw angle of the vehicle body 2. The direction sensor 52 is, for example, an IMU (Inertial Measurement Unit). The controller 37 calculates the travel direction of the vehicle body 2 based on the acceleration and angular velocity of the vehicle body 2. Alternatively, the direction sensor 52 can also be a GNSS (Global Navigation Satellite System) receiver such as GPS (Global Positioning System). The controller 37 can also obtain the travel direction of the vehicle body 2 based on changes in the position of the operating machinery 1 detected by the direction sensor 52.

[0043] like Figure 3 As shown, the working machine 1 includes a steering angle sensor 40, a steering actuator 41, and a steering valve 42. The steering actuator 41 is a hydraulic cylinder. The steering actuator 41 extends and retracts via working oil from the first hydraulic pump 32. The steering actuator 41 steers the front wheels 3A and 3B by extending and retracting.

[0044] Figure 4 This is a top view showing the front of the operating machine 1. For example... Figure 4As shown, the front wheels 3A and 3B comprise a first front wheel 3A and a second front wheel 3B. The first front wheel 3A and the second front wheel 3B are arranged separately on the left and right sides, facing upwards. The first front wheel 3A is rotatably supported on the front frame 11 about a first steering shaft 43. The second front wheel 3B is rotatably supported on the front frame 11 about a second steering shaft 44. The first steering shaft 43 and the second steering shaft 44 extend in the vertical direction.

[0045] Steering actuator 41 is connected to the front wheels 3A and 3B and the front frame 11. Steering actuator 41 causes the steering angle θ1 of the front wheels 3A and 3B to change left or right from a predetermined neutral angle. Figure 4 As shown, the steering angle θ1 is the angle of the front wheels 3A and 3B relative to the longitudinal direction of the working machine 1. The longitudinal direction of the working machine 1 refers to the longitudinal direction of the front frame 11. However, the longitudinal direction of the working machine 1 can also refer to the longitudinal direction of the rear frame 12.

[0046] The neutral angle is a steering angle θ1 of 0 degrees. Therefore, a steering angle θ1 being a neutral angle means that the front wheels 3A and 3B are facing directly in front of the working machine 1. Furthermore, in Figure 4 In the diagram, 3A' shows the first front wheel 3A turning left from the neutral angle with a steering angle θ1. 3B' shows the second front wheel 3B turning left from the neutral angle with a steering angle θ1.

[0047] Steering valve 42 is connected to the first hydraulic pump 32 and the steering actuator 41 via a hydraulic circuit. Steering valve 42 controls the flow rate of working oil supplied from the first hydraulic pump 32 to the steering actuator 41. Steering valve 42 is a hydraulically pilot-operated control valve.

[0048] Steering angle sensor 40 detects steering angle θ1. Steering angle sensor 40 outputs an angle signal representing steering angle θ1. Controller 37 obtains the current steering angle θ1 from the angle signal from steering angle sensor 40. Steering angle sensor 40 detects, for example, the travel amount of steering actuator 41. Steering angle θ1 is calculated based on the travel amount of steering actuator 41. Alternatively, steering angle sensor 40 may also directly detect steering angle θ1.

[0049] The working machine 1 includes a first steering component 45 and a second steering component 46. The operator can operate the first steering component 45 and the second steering component 46 to change the steering angle θ1 of the front wheels 3A and 3B to the left or right. The first steering component 45 is a lever or similar rod. Alternatively, the first steering component 45 can be a component other than a lever. The first steering component 45 can tilt left or right from a neutral position N1. The first steering component 45 is connected to a first operation sensor 51. The first operation sensor 51 outputs a first operation signal from the operator's operation of the first steering component 45. The controller 37 obtains the operation amount of the first steering component 45 through the first operation signal from the first operation sensor 51.

[0050] The second steering component 46 is a steering wheel. Alternatively, the second steering component 46 may be a component other than a steering wheel. The second steering component 46 is rotatable about a rotation axis Ax1. A second operation sensor 47 is mounted on the second steering component 46. The second operation sensor 47 outputs a second operation signal indicating the operator's operation on the second steering component 46. For example, the second operation sensor 47 detects an angular displacement about the rotation axis Ax1 of the second steering component 46. The controller 37 obtains the operation amount of the second steering component 46 from the second operation signal from the second operation sensor 47. Furthermore, when the second steering component 46 is not operated by the operator, it remains in the last operated position.

[0051] The working machine 1 includes a second hydraulic pump 48, a first pilot valve 49, and a second pilot valve 50. The second hydraulic pump 48 discharges working oil by being driven by a drive source 31. The first pilot valve 49 is connected to the second hydraulic pump 48 and a directional valve 42 via a hydraulic circuit. The first pilot valve 49 controls the pressure of the working oil supplied from the second hydraulic pump 48 to the pilot port of the directional valve 42. The first pilot valve 49 is an electromagnetic proportional control valve.

[0052] The first pilot valve 49 is controlled by a signal from the controller 37. The controller 37 controls the first pilot valve 49 based on a first operation signal from the first operation sensor 51, thereby extending or retracting the steering actuator 41. Thus, the controller 37 controls the steering actuator 41 based on the operation of the first steering component 45 to change the steering angle θ1 of the front wheels 3A and 3B. The control of the steering angle θ1 by the first steering component 45 will be described in detail later.

[0053] The second pilot valve 50 is connected to the second hydraulic pump 48 and the steering valve 42 via a hydraulic circuit. The second pilot valve 50 is connected to the second steering component 46. The second pilot valve 50 controls the pressure of the working oil supplied from the second hydraulic pump 48 to the pilot port of the steering valve 42 according to the operation of the second steering component 46. As a result, the steering actuator 41 changes the steering angle θ1 of the front wheels 3A and 3B, so that the steering angle θ1 of the front wheels 3A and 3B becomes an angle corresponding to the operation amount of the second steering component 46.

[0054] With the operation amount of the second steering component 46 remaining constant, the steering actuator 41 maintains the steering angle θ1 of the front wheels 3A and 3B at an angle corresponding to the operation amount of the second steering component 46. Furthermore, similar to the first pilot valve 49, the second pilot valve 50 can also be an electromagnetic proportional control valve. In this case, the controller 37 can also control the second pilot valve 50 according to the operation of the second steering component 46.

[0055] Next, the control of the steering angle θ1 by the first steering component 45 will be explained. The controller 37 determines the target steering speed by referring to the steering speed data and based on the operation amount of the first steering component 45. The controller 37 controls the steering actuator 41 so that the steering angle θ1 changes with the target steering speed. The steering speed data specifies the target steering speed relative to the operation amount of the first steering component 45.

[0056] Figure 5 This is a graph representing an example of steering speed data. (Example) Figure 5 As shown, the first steering component 45 can operate within a neutral range, a left steering range, and a right steering range. The neutral range includes the position of the first steering component 45 at operation amount 0, i.e., the range including the neutral position N1. The neutral range lies between the left steering range and the right steering range. The left steering range lies to the left of the neutral range. The right steering range lies to the right of the neutral range.

[0057] Within the left-turn range, the target left-turn speed is defined as increasing from 0 to the maximum left-turn speed VL, based on the increase in the leftward operation amount of the first steering component 45. Therefore, when the first steering component 45 is within the left-turn range, the controller 37 controls the steering actuator 41 so that the steering angle θ1 of the front wheels 3A and 3B changes to the left at a speed corresponding to the operation amount of the first steering component 45.

[0058] For example, when the first steering component 45 is operated with a leftward operation amount A1, the controller 37 determines the steering speed V1 corresponding to the operation amount A1 as the target steering speed. Furthermore, the controller 37 controls the steering actuator 41 so that the steering angle θ1 of the front wheels 3A and 3B changes to the left at the steering speed V1. Additionally, while the first steering component 45 is held at the leftward operation amount A1, the steering angle θ1 of the front wheels 3A and 3B continues to change to the left at the steering speed V1 until the maximum leftward steering angle is reached.

[0059] Within the right-turn range, the target right-turn speed is defined as increasing from 0 to the maximum right-turn speed VR, based on the increase in the rightward operation amount of the first steering component 45. Therefore, when the first steering component 45 is within the right-turn range, the controller 37 controls the steering actuator 41 so that the steering angle θ1 of the front wheels 3A and 3B changes to the right at a speed corresponding to the operation amount of the first steering component 45.

[0060] For example, when the first steering component 45 is operated with a rightward operation amount A2, the controller 37 determines the steering speed V2 corresponding to the operation amount A2 as the target steering speed. Furthermore, the controller 37 controls the steering actuator 41 so that the steering angle θ1 of the front wheels 3A and 3B changes to the right at the steering speed V2. Additionally, while the first steering component 45 is maintained at the rightward operation amount A2, the steering angle θ1 of the front wheels 3A and 3B continues to change to the right at the steering speed V2 until the maximum rightward steering angle is reached.

[0061] When the first steering component 45 is within the neutral range, the controller 37 controls the steering actuator 41 so that the steering angle θ1 remains at the neutral angle. For example, when the steering angle θ1 is at the neutral angle and the first steering component 45 is within the neutral range, the steering angle θ1 does not change and remains at the neutral angle.

[0062] Furthermore, when both the first steering component 45 and the second steering component 46 are operated simultaneously, the controller 37 prioritizes the operation of the second steering component 46. Therefore, when both the first steering component 45 and the second steering component 46 are operated simultaneously, the controller 37 does not control the steering angle θ1 using the first steering component 45. Thus, the steering angle θ1 changes according to the operation of the second steering component 46.

[0063] Next, the automatic control of the steering angle θ1 will be explained. The controller 37 performs automatic control to control the steering actuator 41 so that the steering angle θ1 becomes a predetermined target angle. The automatic control includes a center-turning mode and a steering stability mode.

[0064] In center turn mode, controller 37 controls steering actuator 41 so that when the first steering component 45 returns from the left or right steering range to the neutral range, the steering angle θ1 automatically returns to the neutral angle.

[0065] For example, when the steering angle θ1 is a predetermined angle to the left, when the first steering component 45 returns to the neutral range, the controller 37 controls the steering actuator 41 so that the steering angle θ1 returns from the predetermined angle to the left to the neutral angle. When the steering angle θ1 is a predetermined angle to the right, when the first steering component 45 returns to the neutral range, the controller 37 controls the steering actuator 41 so that the steering angle θ1 returns from the predetermined angle to the right to the neutral angle.

[0066] Figure 6 This diagram illustrates an example of how the work machinery 1 is driven by operating the first steering component 45. (See diagram for example.) Figure 6As shown, when the machine 1 is at location P1, the first steering component 45 is in the neutral position N1. The steering angle θ1 is the neutral angle, and the machine 1 travels straight. At location P2, when the operator moves the first steering component 45 to the left operating range by an operation amount A1, the steering angle θ1 of the front wheels 3A and 3B begins to change from the neutral angle to the left. Thus, the machine 1 turns left.

[0067] During the transition from point P2 to point P3, when the operator holds the first steering component 45 at the operating position A1, the steering angle θ1 of the front wheels 3A and 3B continues to increase to the maximum leftward steering angle θmax. Thus, the machine 1 continues to turn left.

[0068] Furthermore, at location P3, when the operator returns the first steering component 45 to the neutral range, due to the center turning mode, the steering angle θ1 of the front wheels 3A and 3B decreases from the maximum steering angle θmax towards the neutral angle. Moreover, at location P5, the steering angle θ1 of the front wheels 3A and 3B returns to the neutral angle.

[0069] In steering stability mode, controller 37 controls the steering angle θ1 to keep the vehicle body 2 in the target direction. For example... Figure 6 As shown, at location P3, after the operator returns the first steering component 45 to the neutral range, the controller 37 determines whether the steering angle θ1 has returned to the neutral angle. At location P5, the controller 37 determines that the steering angle θ1 has returned to the neutral angle. The controller 37 determines the travel direction H1 of the vehicle body 2 when the steering angle θ1 has returned to the neutral angle as the target direction. Then, the controller 37 controls the steering actuator 41 to maintain the travel direction of the vehicle body 2 in the target direction (H1). Thus, the working machine 1 travels straight in the target direction (H1).

[0070] In detail, the controller 37 determines the target angle of the steering angle θ1 based on the difference between the current travel direction of the vehicle body 2 and the target direction. The controller 37 controls the steering actuator 41 to make the steering angle θ1 the target angle. For example, the controller 37 determines the target angle of the steering angle θ1 by multiplying the difference between the current travel direction of the vehicle body 2 and the target direction by a predetermined gain. As the vehicle speed increases, the controller 37 decreases the gain. Thus, the higher the vehicle speed, the smaller the target angle. The controller 37 controls the steering actuator 41 through feedback control to keep the steering angle θ1 at the target angle.

[0071] Furthermore, the controller 37 can also calculate the vehicle speed based on the position change of the working machine 1 detected by the aforementioned GNSS receiver. Alternatively, a rotation sensor for detecting the output rotational speed of the power transmission device 33 can also be installed on the working machine 1. The controller 37 can then calculate the vehicle speed based on the output rotational speed of the power transmission device 33.

[0072] Figure 7 This is a flowchart illustrating the process used to determine the start of automatic control. For example... Figure 7 As shown, in step S101, the controller 37 determines whether to perform a steering operation. When at least one of the first steering component 45 and the second steering component 46 is operated, the controller 37 determines that a steering operation is to be performed.

[0073] When the first steering component 45 is within the left or right steering range, the controller 37 determines that the first steering component 45 has been operated via the first operation signal. When the first steering component 45 is within the neutral range, the controller 37 determines that the first steering component 45 has been operated via the first operation signal.

[0074] The controller 37 obtains the operating speed of the second steering component 46 through the second operation signal. When the operating speed is greater than a threshold, the controller 37 determines that the second steering component 46 is operated. When the operating speed is less than the threshold, the controller 37 determines that the second steering component 46 is not operated. For example, the controller 37 calculates the angular velocity of the second steering component 46. When the angular velocity of the second steering component 46 is less than the threshold, the controller 37 determines that the second steering component 46 is not operated.

[0075] In step S101, when the controller 37 determines that a steering operation is to be performed, the process proceeds to step S106. In step S106, the steering actuator 41 is controlled in manual mode. That is, the controller 37 does not perform automatic control, but controls the steering actuator 41 according to the operator's operation on the first steering component 45 or the second steering component 46, as described above.

[0076] In step S101, if the controller 37 determines that no steering operation has been performed, the process proceeds to step S102. In step S102, the controller 37 determines whether the first steering component 45 of the first steering component 45 and the second steering component 46 was last operated. In step S102, if the controller 37 determines that the first steering component 45 of the first steering component 45 and the second steering component 46 was not last operated, the process proceeds to step S106. That is, when the second steering component 46 was last operated, the controller 37 does not perform automatic control, and the steering actuator 41 is controlled in manual mode.

[0077] In step S102, when the controller 37 determines that the first steering component 45 was last operated, the process proceeds to step S103. In step S103, after the controller 37 switches from manual mode to automatic control, it determines whether the steering angle θ1 has returned to the neutral angle, even if it only returns once. After switching from manual mode to automatic control, if the controller 37 determines that the steering angle θ1 has not returned to the neutral angle even once, the process proceeds to step S104.

[0078] In step S104, the controller 37 controls the steering actuator 41 in center-turn mode. That is, as... Figure 6 As shown at locations P3 to P5, controller 37 controls steering actuator 41 to return steering angle θ1 to neutral angle.

[0079] In step S103, after transitioning from manual mode to automatic control, when the controller 37 determines that the steering angle θ1 returns to the neutral angle even once, the process proceeds to step S105. In step S105, in steering stability mode, the controller 37 controls the steering actuator 41. Figure 6 As shown at location P5, in steering stability mode, controller 37 controls the steering angle θ1 to keep the vehicle body 2 in the target direction (H1).

[0080] In the work machine 1 described above, the steering actuator 41 is controlled to keep the travel direction of the vehicle body 2 in the target direction. Furthermore, the travel direction of the vehicle body 2 is determined as the target direction not when the first steering component 45 is operated to the neutral range, but when the steering angle θ1 returns to the neutral angle.

[0081] For example Figure 6 As shown at location P3, the travel direction H2 of the vehicle body 2 when the first steering component 45 is operated to the neutral range is different from the travel direction H1 of the vehicle body 2 when the steering angle θ1 returns to the neutral angle. In the working machine 1 of this embodiment, the travel direction H1 of the vehicle body 2 when the steering angle θ1 returns to the neutral angle is determined as the target direction. Therefore, the working machine 1 is controlled to travel straight in the travel direction H1 when the steering angle θ1 actually returns to the neutral angle. As a result, the operator's workload can be reduced, and the operator's discomfort can be decreased.

[0082] The above describes one embodiment of the present invention, but the present invention is not limited to the above embodiment and various modifications can be made without departing from the spirit of the invention.

[0083] The operating machinery 1 is not limited to motorized graders, but can also be other operating machinery such as wheel loaders, dump trucks, and forklifts. The number of steering actuators 41 is not limited to one, but can also be two or more. The steering actuator 41 is not limited to hydraulic cylinders, but can also be a hydraulic motor or an electric motor.

[0084] The steering speed data is not limited to that described in the above embodiment and can be modified. Alternatively, the center turn mode can be omitted. In the above embodiment, the controller 37 controls the steering actuator 41 to change the steering angle θ1 at a speed corresponding to the operation amount of the first steering component 45. However, the controller 37 can also control the steering actuator 41 to make the steering angle θ1 an angle corresponding to the operation amount of the first steering component 45. That is, the control of the steering angle θ1 by the first steering component 45 is not limited to the speed control type, but can also be the position control type.

[0085] When vehicle body 2 reverses, controller 37 can also reverse the target angle of steering angle θ1 relative to when vehicle body 2 is moving forward. For example, if the target direction when moving forward is to the left of the working machine 1, controller 37 determines the target angle to be closer to the left than the neutral angle. If the target direction when reversing is to the left of the working machine 1, controller 37 determines the target angle to be closer to the right than the neutral angle. If the target direction when moving forward is to the right of the working machine 1, controller 37 determines the target angle to be closer to the right than the neutral angle. If the target direction when reversing is to the right of the working machine 1, controller 37 determines the target angle to be closer to the left than the neutral angle.

[0086] Furthermore, the controller 37 can also determine whether the vehicle body 2 is moving forward or backward based on the signal from the shifting component 53. Alternatively, the controller 37 can also determine whether the vehicle body 2 is moving forward or backward based on the position change of the working machinery 1 detected by the GNSS receiver. Alternatively, the controller 37 can also determine whether the vehicle body 2 is moving forward or backward based on the rotation direction of the output shaft of the power transmission device 33.

[0087] Industrial availability

[0088] According to the present invention, the operator's workload can be reduced and the operator's discomfort can be decreased through automatic control of the steering angle.

[0089] Explanation of reference numerals in the attached figures

[0090] 2: Body

[0091] 3A, 3B: Front wheels

[0092] 37: Controller

[0093] 40: Steering angle sensor

[0094] 41: Steering actuator

[0095] 45: First steering component

[0096] 51: First operating sensor

[0097] 52: Orientation sensor

Claims

1. A type of operating machinery, characterized in that, have: Body; The driving wheels are supported on the vehicle body; Steering components, which are capable of steering in the left steering range, the right steering range, and the ranges of the left and right steering. Operations within a neutral range; An actuator that, when the steering component is in the neutral range, uses the steering angle of the driving wheel as... The predetermined neutral angle is adjusted to the left or right based on the operation of the steering component. The sensor operates, and its output is an operation signal indicating the operation of the steering component; A steering angle sensor, whose output is an angle signal representing the steering angle; A direction sensor that outputs a direction signal indicating the direction of travel of the vehicle body; The controller acquires the operation signal, the angle signal, and the direction signal. When the steering component moves from the left steering range or the right steering range to the neutral range, the control The controller determines whether the steering angle has returned to the neutral angle. The direction of travel when the steering angle returns to the neutral angle is determined as the target direction. Control the actuator to keep the direction of travel in the target direction.

2. The operating machinery as described in claim 1, characterized in that, The controller determines the target angle of the steering angle based on the difference between the traveling direction and the target direction. The actuator is controlled to make the steering angle the target angle.

3. The operating machinery as described in claim 2, characterized in that, The controller obtains the vehicle speed of the vehicle body, and the greater the vehicle speed, the smaller the target angle.

4. The operating machinery as described in claim 2 or 3, characterized in that, The controller determines whether the vehicle body is moving forward or backward. When the vehicle body moves backward, the target angle is reversed from left to right relative to when the vehicle body moves forward.

5. A method for controlling a work machine, the work machine comprising a body and wheels supported on the body; An actuator that causes the steering angle of the traveling wheel to change from a predetermined neutral angle to the left or right, characterized in that: include: Obtain an operation signal, the operation signal indicating that it is possible to turn left within the turning range, turn right within the turning range, and turn left within the turning range. Operation of the steering component within the neutral range between the stated right turning range; When the steering component is within the neutral range, the actuator is controlled to make the steering angle become The predetermined neutral angle; Based on the operation of the steering component, the actuator is controlled to change the steering angle from the neutral angle to the left or right. change; Obtain the angle signal representing the steering angle; A direction signal is acquired, and the direction signal is used to detect the travel direction of the vehicle body; When the steering component operates from the left steering range or the right steering range towards the neutral range, it determines that... Whether the steering angle returns to the neutral angle; The direction of travel when the steering angle is determined to return to the neutral angle is defined as the target direction. Control the actuator to keep the direction of travel in the target direction.

6. The method as described in claim 5, characterized in that, It also has: The target angle of the turning angle is determined based on the difference between the travel direction and the target direction; The actuator is controlled to make the steering angle the target angle.

7. The method as described in claim 6, characterized in that, It also has: Obtain the vehicle speed of the vehicle body; The higher the vehicle speed, the smaller the target angle.

8. The method as described in claim 6 or 7, characterized in that, It also has: Determine whether the vehicle body is moving forward or backward; When the vehicle body moves backward, the target angle is reversed from left to right relative to when the vehicle body moves forward.

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