Work machine traveling system

Abstract

To enable a work machine to travel stably even if there is a change in an inclination of a traveling surface of the work machine.SOLUTION: A controller 60 acquires pre-traveling supporting force Fa0. The pre-traveling supporting force Fa0 is supporting force F detected by a supporting force sensor 31 when an attachment 15 is in contact with a supporting surface S5 and before a machine body 10a starts traveling. The controller 60 sets target supporting force Ft based on the pre-traveling supporting force Fa0. The controller 60 controls an attachment driving device 23 so that the supporting force (Fa) detected by the supporting force sensor 31 is maintained at the target supporting force Ft when the attachment 15 is in contact with the supporting surface S5 and the machine body 10a is traveling.SELECTED DRAWING: Figure 4D

Description

[Technical field]

[0001] The present invention relates to a work machine travel system for a work machine that is equipped with a travellable machine body. [Background technology]

[0002] For example, Patent Document 1 describes a technique for loading a work machine onto a trailer while monitoring the attitude stability of the work machine. In the technique described in this document, automatic loading control (travel control) onto the trailer is stopped or continued based on the attitude stability of the work machine (see

[0198] in the same document). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 101007 Summary of the Invention [Problem to be solved by the invention]

[0004] It is desirable to allow a work machine to travel stably even if the slope of the traveling surface on which the work machine travels changes.

[0005] An object of the present invention is to provide a work machine travel system that enables the work machine to travel stably even if there is a change in the inclination of the travel surface of the work machine. [Means for solving the problem]

[0006] The work machine traveling system includes a machine body, an attachment, an attachment drive device, a support force sensor, and a controller. The machine body is a main body of a work machine and is capable of traveling. The attachment is attached to the machine body so as to be capable of rising and lowering. The attachment drive device drives the attachment. The support force sensor detects a support force that is a force acting from the attachment to a support surface when the attachment contacts the support surface. The controller acquires a pre-traveling support force. The pre-traveling support force is the support force detected by the support force sensor in a state in which the attachment contacts the support surface and before the machine body travels. The controller sets a target support force based on the pre-traveling support force. The controller controls the attachment drive device so that the support force detected by the support force sensor is maintained at the target support force when the attachment contacts the support surface and the machine body is traveling. Effect of the Invention

[0007] The above-described work machine traveling system enables the work machine to travel stably even if there is a change in the inclination of the traveling surface of the work machine. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a side view of a work machine 10 of a work machine traveling system 1. [Diagram 2] FIG. 1 is a block diagram showing a work machine travel system 1. [Diagram 3] 3 is a flowchart of a process of the controller 60 shown in FIG. 2. [Figure 4A] 2 is a diagram showing the work machine 10 and a detected supporting force Fa, etc., when the work machine 10 shown in FIG. 1 is stopped on flat ground Sa. [Figure 4B] 4A, showing a state in which the working machine 10 shown in FIG. 4A has moved forward from the state shown in FIG. 4A. [Figure 4C]4A, showing the working machine 10 shown in FIG. 4B in a state further forward from the state shown in FIG. 4BA. [Figure 4D] 4A and illustrates a state in which the work machine 10 illustrated in FIG. 4C travels on a slope Sb. [Diagram 5] FIG. 2 is a diagram showing the work machine 10 shown in FIG. 1 when the work machine 10 moves forward and climbs a slope Sb. [Figure 6] FIG. 2 is a diagram showing the work machine 10 and the like when the work machine 10 shown in FIG. 1 moves backward and descends a slope Sb. [Figure 7] FIG. 2 is a diagram showing the work machine 10 and the like shown in FIG. 1 when the work machine 10 moves backward and up a slope Sb. [Figure 8] 1. FIG. 4 is a diagram showing the working machine 10 and the like when the machine body 10a travels while maintaining the position of the support surface contact portion 15d relative to the support surface S5 shown in FIG. [Figure 9] 2 is a diagram showing the center of gravity of the attachment 15 shown in FIG. 1, a tipping fulcrum 11t of the work machine 10, and the like. [Figure 10] 4 is a graph showing the relationship between the target supporting force Ft and the overturning moment M due to the own weight of the attachment 15 shown in FIG. [Figure 11] 2 is a graph showing the relationship between the traveling speed V of the machine body 10a shown in FIG. 1 and the target supporting force Ft. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The work machine travel system 1 will be described with reference to Figs. 1 to 11.

[0010] The work machine traveling system 1 is a system for stably traveling the work machine 10 shown in Fig. 1. The work machine traveling system 1 suppresses rocking and tipping of the work machine 10 when the inclination of the traveling surface S1 (traveling path) on which the work machine 10 travels changes. The work machine traveling system 1 includes the work machine 10, an imaging device 51 shown in Fig. 2, an input device 53, and a controller 60.

[0011] As shown in FIG. 1, the work machine 10 is a machine that performs work. The work machine 10 is, for example, a construction machine that performs construction work, such as a shovel. The work machine 10 may be configured to be capable of automatic operation. The work machine 10 may be operated by a worker (operator) in a cab 13c (described later), or may be remotely operated. The work machine 10 includes a machine body 10a, an attachment 15, an actuator 20, an actuator control unit 28 shown in FIG. 2, a supporting force sensor 31, and an attitude sensor 40.

[0012] 1, the machine body 10a is a main body portion of the work machine 10. The machine body 10a is capable of traveling. The machine body 10a includes a lower traveling body 11 and an upper rotating body 13.

[0013] The lower traveling body 11 can travel on a traveling surface S1. The lower traveling body 11 may be equipped with a crawler or may be equipped with a wheel. The traveling surface S1 may be the ground, a concrete surface, or a metal surface.

[0014] The upper rotating body 13 is rotatably mounted on the lower traveling body 11. A central axis of rotation of the upper rotating body 13 relative to the lower traveling body 11 is defined as a central rotation axis 13a. The upper rotating body 13 includes a cab 13c. The cab 13c is a section where an operator can operate the work machine 10.

[0015] (direction) The direction in which the revolving central axis 13a extends is defined as the "machine up-down direction." The side (direction) in which the attachment 15 protrudes relative to the upper revolving body 13 is defined as the machine front side X1 in the machine fore-and-aft direction X. The side opposite the machine front side X1 in the machine fore-and-aft direction X is defined as the machine rear side X2. As shown in FIG. 4A, the traveling direction of the machine body 10a when the machine body 10a (more specifically, the lower traveling body 11) is traveling is defined as the traveling front side D1 in the traveling fore-and-aft direction D. The side opposite the traveling front side D1 in the traveling fore-and-aft direction D is defined as the traveling rear side D2.

[0016] As shown in Fig. 1, the attachment 15 is attached to the machine body 10a so that it can be raised and lowered (i.e., can rotate in the vertical direction of the machine). The attachment 15 is the part that performs work. The attachment 15 supports the work machine 10 when the work machine 10 is traveling (details will be described later). The attachment 15 includes, for example, a boom 15a, an arm 15b, and a tip attachment 15c. The attachment 15 includes a support surface contact portion 15d.

[0017] The boom 15a is attached so as to be able to rise and fall (more specifically, so as to be able to rotate in the machine up-down direction and the machine front-rear direction X) to the upper rotating body 13. The arm 15b is attached so as to be able to rotate (more specifically, so as to be able to rotate in the machine up-down direction and the machine front-rear direction X) to the boom 15a.

[0018] The tip attachment 15c is provided at the tip of the attachment 15. The tip attachment 15c is rotatably attached to the arm 15b (specifically, rotatable in the machine vertical direction and the machine front-rear direction X). The tip attachment 15c may be, for example, a bucket for scooping and excavating a work object. The tip attachment 15c may be a device for clamping a work object (grapple, nibbler, etc.), a device for crushing a work object (breaker, etc.), or a magnet for attracting a metal work object. The following mainly describes the case where the tip attachment 15c is a bucket. In this case, the tip attachment 15c includes a bucket tip 15c1, a bucket opening 15c3, and a bucket bottom 15c5.

[0019] The bucket tip 15c1 is the tip of the tip attachment 15c. The bucket tip 15c1 is the end of the tip attachment 15c opposite the attachment portion (base end) to the arm 15b. The bucket opening 15c3 is the opening surface of the tip attachment 15c. The bucket bottom 15c5 is provided in the tip side portion (the portion farther from the arm 15b) of the tip attachment 15c. The bucket bottom 15c5 is the portion that is disposed at the bottom (lower portion) of the tip attachment 15c when the tip attachment 15c is disposed so that the bucket opening 15c3 faces upward and toward the machine body 10a. The bucket bottom 15c5 is flat.

[0020] The support surface contact portion 15d is a portion that comes into contact with the support surface S5. The support surface S5 may be the ground, a concrete surface, or a metal surface, similar to the traveling surface S1. The contact of the support surface contact portion 15d with the support surface S5 is also referred to as "ground contact." The support surface contact portion 15d is, for example, the tip attachment 15c, for example, the bucket bottom 15c5. Note that the support surface contact portion 15d may be a portion of the attachment 15 other than the bucket bottom 15c5.

[0021] The actuator 20 is a device that moves the work machine 10. The actuator 20 may be equipped with a hydraulic actuator that is driven by hydraulic pressure, or may be equipped with an electric actuator that is driven by electricity. The actuator 20 may be equipped with a motor, or may be equipped with an extendable cylinder. Specifically, the actuator 20 is equipped with a travel motor 21 and an attachment drive device 23.

[0022] The traveling motor 21 drives the lower traveling body 11 to cause the lower traveling body 11 to travel. The traveling motor 21 may be, for example, a hydraulic motor or an electric motor.

[0023] The attachment driving device 23 is a device that drives the attachment 15. The attachment driving device 23 changes the angle of each joint of the attachment 15. Specifically, the attachment driving device 23 includes a boom cylinder 23a, an arm cylinder 23b, and a tip attachment cylinder 23c. The boom cylinder 23a raises and lowers the boom 15a relative to the upper rotating body 13. The boom cylinder 23a is, for example, a cylinder (hydraulic cylinder) that is driven by hydraulic pressure (the same applies to the arm cylinder 23b and the tip attachment cylinder 23c). The arm cylinder 23b rotates the arm 15b relative to the boom 15a. The tip attachment cylinder 23c rotates the tip attachment 15c relative to the arm 15b. If the tip attachment 15c itself is drivable, for example, as a device for clamping an object, the attachment driving device 23 may include a cylinder or a motor for driving the tip attachment 15c.

[0024] The actuator control section 28 (see FIG. 2) controls the actuator 20. The actuator control section 28 may include a hydraulic circuit for controlling a hydraulic actuator. The actuator control section 28 may include an electric circuit for controlling an electric actuator.

[0025] The supporting force sensor 31 (see FIG. 2) detects the supporting force F. The supporting force F detected by the supporting force sensor 31 is defined as a detected supporting force Fa (see FIG. 4A). The supporting force F is a force acting from the attachment 15 to the supporting surface S5 when the attachment 15 comes into contact with the supporting surface S5. The supporting force F is a force acting from the supporting surface S5 to the supporting surface contacting portion 15d when the supporting surface contacting portion 15d comes into contact with the supporting surface S5. The supporting force F is a force with which the supporting surface contacting portion 15d presses down on the supporting surface S5, for example. The supporting force F may be an amount that can be converted into a force acting from the attachment 15 to the supporting surface S5 (hereinafter referred to as a "convertible amount").

[0026] For example, the supporting force sensor 31 may detect the supporting force F by detecting the amount of distortion (amount of deformation) (an example of a convertible amount) of the attachment 15. For example, the supporting force sensor 31 may detect at least one of the amount of distortion of the boom 15a, the amount of distortion of the arm 15b, and the amount of distortion of the tip attachment 15c.

[0027] For example, the supporting force sensor 31 may detect the supporting force F by detecting a force acting on the attachment driving device 23 (an example of a convertible amount). For example, the supporting force sensor 31 may detect a force acting on each of the boom cylinder 23a, the arm cylinder 23b, and the tip attachment cylinder 23c (hereinafter also referred to as "each cylinder") (an example of a convertible amount). For example, the supporting force sensor 31 may detect the strain (deformation) (an example of a convertible amount) of each cylinder. The supporting force sensor 31 may detect the hydraulic pressure (an example of a convertible amount) of each cylinder. In this case, as shown in FIG. 2, the supporting force sensor 31 includes a boom pressure sensor 31a, an arm pressure sensor 31b, and a tip attachment pressure sensor 31c. In FIG. 2, "attachment" is written as "ATT".

[0028] The boom pressure sensor 31a detects the pressure of hydraulic oil that extends and retracts the boom cylinder 23a shown in FIG. 1 (hydraulic pressure of the boom cylinder 23a, boom pressure). The arm pressure sensor 31b (see FIG. 2) detects the pressure of hydraulic oil that extends and retracts the arm cylinder 23b (hydraulic pressure of the arm cylinder 23b, arm pressure). The tip attachment pressure sensor 31c (see FIG. 2) detects the pressure of hydraulic oil that extends and retracts the tip attachment cylinder 23c (hydraulic pressure of the tip attachment cylinder 23c, tip attachment pressure). When the tip attachment 15c is a bucket, the tip attachment pressure sensor 31c is a "bucket pressure sensor."

[0029] In this example, the supporting force sensor 31 detects the hydraulic pressure of each cylinder. In this case, the controller 60 shown in FIG. 2 acquires the detection values ​​of the boom pressure sensor 31a, the arm pressure sensor 31b, and the tip attachment pressure sensor 31c. Then, the controller 60 calculates the force acting on the supporting surface S5 from the supporting surface contact portion 15d shown in FIG. 1 based on the balance of forces from the acquired detection values. The controller 60 may set the calculated force as the detected supporting force Fa. When the controller 60 calculates the supporting force F, the controller 60 may be included in the supporting force sensor 31.

[0030] The attitude sensor 40 detects the attitude of the work machine 10. The attitude sensor 40 includes a reference position sensor 41, an inclination sensor 43, and an attachment attitude sensor 45.

[0031] The reference position sensor 41 detects the position and orientation of a reference portion of the work machine 10 with respect to the work site. The reference portion of the work machine 10 may be, for example, a specific portion of the upper rotating body 13 or the lower running body 11, for example, a specific portion on the rotating central axis 13a, for example, the mounting portion (boom foot) of the boom 15a to the upper rotating body 13. The reference position sensor 41 may perform detection using a positioning system using light or radio waves. For example, the positioning system may be a satellite positioning system, for example, a global navigation satellite system (GNSS), or a system using a (terrestrial) transmitter and receiver without using a satellite. For example, the positioning system may use a total station. In FIG. 1, the reference position sensor 41 is designated by the reference position sensor 41 as the antenna (for example, a GNSS antenna) used when the reference position sensor 41 performs detection using the positioning system.

[0032] The inclination sensor 43 detects a body angle θ (see FIG. 9), which is the inclination angle of the machine body 10a with respect to the horizontal plane. The inclination sensor 43 is, for example, an inertial measurement device.

[0033] The attachment attitude sensor 45 detects the attitude of the attachment 15. The attachment attitude sensor 45 includes a boom sensor 45a, an arm sensor 45b, and a tip attachment sensor 45c. The boom sensor 45a detects the attitude of the boom 15a. The boom sensor 45a may detect the angle (tilt) of the boom 15a with respect to the horizontal direction, or may detect the angle (boom angle, rotation angle) of the boom 15a with respect to the upper rotating body 13. Specifically, the boom sensor 45a may include an angle sensor (e.g., a rotary encoder, etc.) attached to the rotation shaft or rotation support part of the boom 15a with respect to the upper rotating body 13. The boom sensor 45a may include a sensor (e.g., an inertial measurement device, etc.) that detects the angle (tilt) of the boom 15a with respect to the horizontal direction. The boom sensor 45a may include a stroke sensor that detects the stroke (extension and contraction position) of the boom cylinder 23a. The boom sensor 45a may detect the attitude of the boom 15a based on at least one of a two-dimensional image and a distance image. In this case, at least one of the two-dimensional image and the distance image may be captured by an imaging device 51 (see FIG. 2). The arm sensor 45b detects the posture of the arm 15b. The tip attachment sensor 45c detects the posture of the tip attachment 15c. Specific examples of the arm sensor 45b and the tip attachment sensor 45c are similar to the specific example of the boom sensor 45a.

[0034] The imaging device 51 captures an image of an object to be imaged. The object to be imaged by the imaging device 51 may be an object in the vicinity of the work machine 10. For example, the object to be imaged by the imaging device 51 may include the travel surface S1, the support surface S5, flat ground Sa (see FIG. 4A) (described later), or a slope Sb (see FIG. 4A) (described later). The object to be imaged by the imaging device 51 may include at least a part of the work machine 10. The object to be imaged by the imaging device 51 may include an object in the vicinity of the support surface contact portion 15d (for example, the tip attachment 15c). When the imaging device 51 is used as the attachment attitude sensor 45, the object to be imaged by the imaging device 51 may include the attachment 15.

[0035] The imaging device 51 may detect two-dimensional information of an object to be imaged (e.g., a position or a shape in an image). The imaging device 51 may include a camera (monocular camera) that detects two-dimensional information. The imaging device 51 may obtain a distance image, and may detect three-dimensional information of the object to be imaged (e.g., three-dimensional coordinates or three-dimensional shape) based on the distance image. The imaging device 51 may include a stereo camera. The imaging device 51 may detect a distance to the object to be imaged by irradiating the object with waves such as electromagnetic waves and detecting the reflected waves. The imaging device 51 may include a TOF (Time Of Flight) sensor that detects a distance based on the time from irradiation of the waves to the return of the reflected waves, or may include a sensor that detects a distance based on the frequency of the reflected waves. The imaging device 51 may include a device that detects three-dimensional information using light (e.g., laser light), and may include, for example, a LIDAR (Light Detection and Ranging). The imaging device 51 may include a device that detects three-dimensional information using radio waves (e.g., a millimeter wave radar, etc.). The imaging device 51 may detect three-dimensional information of the imaged object based on the distance image and the two-dimensional image. Only one imaging device 51 may be provided, or multiple imaging devices may be provided. The imaging device 51 may be mounted on the work machine 10, or may be disposed outside the work machine 10 (e.g., at the work site). The same applies to the input device 53 (see FIG. 2) and the controller 60, which may be mounted on the work machine 10, or may be disposed outside the work machine 10 (e.g., at the work site).

[0036] The input device 53 (see FIG. 2) is a device that is operated by an operator. For example, the input device 53 may be disposed in the operator's cab 13c, or may be disposed in a remote control device for remotely controlling the work machine 10. The input device 53 may be part of a personal computer, a tablet, a smartphone, or the like. The input device 53 may include a lever, a pedal, a switch, or the like.

[0037] The controller 60 is a computer that performs input and output of signals, calculation (processing), storage of information, etc. For example, the functions of the controller 60 are realized by executing a program stored in a storage unit 60a shown in FIG. 2 by a calculation unit 60b. The controller 60 and other devices may be connected by wireless communication or by wired communication. For example, signals are input to the controller 60 from the supporting force sensor 31, the attitude sensor 40, the imaging device 51, and the input device 53. For example, the controller 60 controls the actuator 20 by outputting a command for operating the work machine 10 (see FIG. 1) to the actuator control unit 28. When the actuator control unit 28 includes a hydraulic circuit for controlling a hydraulic actuator, the controller 60 controls the actuator 20 by controlling a valve (such as a proportional valve). When the actuator control unit 28 includes an electric circuit for controlling an electric actuator, the controller 60 controls the actuator 20 by controlling the electric circuit. The controller 60 includes an automatic driving control unit 61 and a supporting force processing unit 63.

[0038] The automatic driving control unit 61 automatically drives the work machine 10 (see FIG. 1). For example, the automatic driving control unit 61 outputs a command to the attachment driving device 23 so that the work machine 10 automatically operates in accordance with a preset work plan. The automatic driving control unit 61 controls the operation of the work machine 10 based on the detection value of the attitude sensor 40.

[0039] The supporting force processing unit 63 performs processing (calculation) related to the supporting force F (see FIG. 1).

[0040] (Activation) The work machine traveling system 1 (mainly the supporting force processing unit 63) is configured to operate as follows.

[0041] The operation of the work machine traveling system 1 is outlined as follows. As shown in Fig. 4A, the controller 60 (specifically, the supporting force processing unit 63) acquires a pre-traveling supporting force Fa0, which is the detected supporting force Fa before the work machine 10 travels. The controller 60 (see Fig. 2) sets a target supporting force Ft based on the pre-traveling supporting force Fa0. The controller 60 controls the attachment driving device 23 (see Fig. 2) so that the detected supporting force Fa is maintained at the target supporting force Ft when the attachment 15 comes into contact with the support surface S5 and the machine body 10a travels (during the attachment ground contact traveling). Graphs showing the relationship between the supporting force F and time T are shown in each of Figs. 4A, 4B, 4C, and 4D.

[0042] The operation of the work machine travel system 1 will be described in detail with reference to the flowchart shown in Fig. 3. Below, the work machine 10 (including the components of the work machine 10 such as the attachment 15) will be described with reference to Fig. 1, and the controller 60 will be described with reference to Fig. 2. Each step (S11 to S50) of the flowchart will be described with reference to Fig. 3. Note that the order of each step can be changed in various ways.

[0043] The controller 60 may constantly execute the following processing (supporting force processing) during operation of the work machine 10 shown in Fig. 1. Alternatively, the controller 60 may execute the supporting force processing only when a predetermined condition is satisfied. For example, the controller 60 may be configured to be able to set whether a mode in which the work machine 10 travels with the attachment on the ground (attachment on the ground traveling mode) is on or off. In this case, the controller 60 may execute the supporting force processing only when the attachment on the ground traveling mode is on.

[0044] In step S11, the controller 60 acquires the posture of the attachment 15. The controller 60 acquires the posture of the attachment 15 detected by the attachment posture sensor 45. For example, the controller 60 continues to acquire the posture of the attachment 15 while the work machine 10 is operating.

[0045] In step S12, the controller 60 acquires the grounding state of the attachment 15. The "grounding state of the attachment 15" is information for determining whether or not the attachment 15 is on the ground (see step S21 for the determination). The controller 60 may acquire a detection value of the supporting force sensor 31 (see FIG. 2) as the grounding state of the attachment 15. The controller 60 may acquire an image captured by the imaging device 51 as the grounding state of the attachment 15.

[0046] In step S13, the controller 60 acquires the running state of the machine body 10a. The controller 60 acquires at least information on whether the machine body 10a is running or not (whether the machine body 10a is running or not). The controller 60 may further acquire the running speed V of the machine body 10a (described later). For example, the controller 60 may acquire the running state of the machine body 10a by acquiring the driving state of the lower traveling body 11. Specifically, the controller 60 may acquire the driving state of the traveling motor 21 (e.g., whether or not it rotates, the number of rotations, etc.). For example, the controller 60 may acquire the running state of the machine body 10a by acquiring information on a traveling command for driving the lower traveling body 11 (e.g., whether or not there is a traveling command, the magnitude of the command value of the traveling command, etc.). The traveling command acquired by the controller 60 may be a command output from the controller 60 to the actuator control unit 28 (see FIG. 2). Furthermore, when a worker (operator) manually operates the work machine 10, the travel command acquired by the controller 60 may be a command input to the controller 60 from an input device 53 (see FIG. 2). For example, the controller 60 may acquire information on the movement of the machine body 10a to acquire the travel state of the machine body 10a. In this case, the controller 60 may acquire information on the movement of the machine body 10a by acquiring a detection value of the reference position sensor 41 (see FIG. 2).

[0047] In steps S21 and S22, the controller 60 determines whether or not the work machine 10 is in a state in which it can obtain the pre-travel supporting force Fa0 (see FIG. 4A).

[0048] In step S21, the controller 60 determines whether the attachment 15 is grounded. The controller 60 determines whether the attachment 15 is grounded based on the grounding state of the attachment 15 acquired in step S12. For example, the controller 60 may determine whether the attachment 15 is grounded based on the detected support force Fa (see FIG. 4A). In this case, the controller 60 may determine that the attachment 15 is grounded when the detected support force Fa is equal to or greater than the grounding threshold, and may determine that the attachment 15 is not grounded when the detected support force Fa is less than the grounding threshold. The above-mentioned "grounding threshold" is set in advance (before this determination) in the controller 60. The controller 60 may determine whether the attachment 15 is grounded based on an image captured by the imaging device 51.

[0049] If the controller 60 determines that the attachment 15 is on the ground (YES in step S21), the controller 60 advances the process to step S22. If the controller 60 determines that the attachment 15 is not on the ground (NO in step S21), the controller 60 ends the current process (the flow proceeds to "END"). After ending the current process, the controller 60 may start the next process (the flow may return to "START").

[0050] In step S22, the controller 60 determines whether or not the machine body 10a is stopped. The controller 60 determines whether or not the machine body 10a is stopped, based on the running state of the machine body 10a acquired in step S13.

[0051] When the controller 60 determines that the machine main body 10a is traveling (NO in step S22), the controller 60 ends the current process (the flow proceeds to "END").

[0052] When the attachment 15 is on the ground (YES in step S21) and the machine body 10a is stopped (YES in step S22), the controller 60 determines that the pre-travel supporting force Fa0 can be acquired. In this case, the controller 60 causes the process to proceed to step S31.

[0053] In step S31, the controller 60 acquires the pre-traveling support force Fa0 (see FIG. 4A). The pre-traveling support force Fa0 is the detected support force Fa (see FIG. 4A) before the work machine 10 travels with the attachment on the ground. In detail, the pre-traveling support force Fa0 is the support force F detected by the support force sensor 31 (see FIG. 2) when the attachment 15 is on the ground and before the machine body 10a travels (i.e., while traveling is stopped).

[0054] The conditions for the controller 60 to acquire the pre-traveling support force Fa0 (see FIG. 4A) include at least that the attachment 15 is on the ground and that the machine body 10a is stopped from traveling. The conditions for the controller 60 to acquire the pre-traveling support force Fa0 may further include conditions different from these conditions. For example, the conditions for the controller 60 to acquire the pre-traveling support force Fa0 may include that a mode for acquiring the pre-traveling support force Fa0 is selected. Whether or not the mode is the "pre-traveling support force Fa0 acquiring mode" may be selectable by the operator by operating the input device 53 (see FIG. 2), or may be automatically selectable by the controller 60 based on some condition.

[0055] In step S32, the controller 60 sets the target support force Ft (see FIG. 4A). The controller 60 sets the target support force Ft based on the pre-traveling support force Fa0. The target support force Ft is a target value of the support force F. The target support force Ft may be a certain target value (target support force value Fta) or a target range (target support force range Ftb) having one or both of an upper limit value and a lower limit value. The target support force Ft may be the pre-traveling support force Fa0 (i.e., it may coincide with the pre-traveling support force Fa0). The target support force Ft does not have to be the pre-traveling support force Fa0. The controller 60 may set the target support force Ft based on the pre-traveling support force Fa0 and information other than the pre-traveling support force Fa0. The above-mentioned "information other than the pre-traveling support force Fa0" may be information indicating the state of the work machine 10 or information indicating the state around the work machine 10 (details will be described later). The controller 60 stores the set target supporting force Ft (the target supporting force Ft is stored in the storage unit 60a).

[0056] After the pre-travel supporting force Fa0 (see FIG. 4a) is acquired by the controller 60 in step S31 above, the machine body 10a starts traveling, either manually by the operator or automatically. At this time, the machine body 10a starts traveling with the attachment 15 still in a grounded state (see FIGS. 4a and 4b). That is, the work machine 10 starts attachment grounded traveling.

[0057] In step S41, the controller 60 judges whether or not the work machine 10 is traveling with the attachment on the ground. More specifically, the controller 60 judges whether or not the attachment 15 is on the ground and the machine body 10a is traveling. If the work machine 10 is traveling with the attachment on the ground (YES in step S41), the controller 60 advances the process to step S50. If the work machine 10 is not traveling with the attachment on the ground (NO in step S41), the controller 60 ends the current process (the flow proceeds to "END"). Specifically, if the attachment 15 leaves the support surface S5 after the target supporting force Ft (see FIG. 4A) is set (after step S32), the controller 60 judges that the work machine 10 is not traveling with the attachment on the ground. Also, if the machine body 10a stops traveling after the target supporting force Ft (see FIG. 4A) is set, the controller 60 judges that the work machine 10 is not traveling with the attachment on the ground.

[0058] In step S50, the controller 60 controls the attachment driving device 23 so that the supporting force F (i.e., the detected supporting force Fa (see FIG. 4D)) detected by the supporting force sensor 31 (see FIG. 2) is maintained at the target supporting force Ft. This control is referred to as "supporting force control." As shown in FIG. 4D, when the target supporting force Ft is one value (target supporting force value Fta), the controller 60 controls the attachment driving device 23 so that the deviation between the detected supporting force Fa and the target supporting force Ft becomes 0. When the target supporting force Ft is within the target range (target supporting force range Ftb), the controller 60 controls the attachment driving device 23 so that the detected supporting force Fa falls within the target supporting force range Ftb. When the detected supporting force Fa deviates from the target supporting force Ft, the controller 60 controls the attachment driving device 23 so that the detected supporting force Fa approaches the target supporting force Ft. For example, the controller 60 may perform feedback control, such as PID (Proportional Integral Differential) control. For example, the controller 60 may perform feedforward control. The controller 60 may perform various combinations of feedback control, feedforward control, and other types of control.

[0059] The controller 60 calculates a target force (target force of each cylinder) of each cylinder of the attachment driving device 23 shown in FIG. 1 based on the target supporting force Ft. The target force of each cylinder may be the thrust (target thrust) of each cylinder or the hydraulic pressure (target hydraulic pressure) of each cylinder. The controller 60 calculates the target force of each cylinder based on the target supporting force Ft (see FIG. 4D) and information on the attitude of the attachment 15. At this time, the controller 60 may calculate the target force of each cylinder by a solution using a mathematical method (for example, a solution using a mathematical model). The controller 60 may calculate the target force of each cylinder by using an equation of motion (state equation) of each part of the attachment 15, by using inverse kinematics, or by using convergence calculation. Then, the controller 60 controls each cylinder so that the force (for example, thrust, hydraulic pressure) of each cylinder of the attachment driving device 23 becomes the calculated target force (for example, target thrust, target pressure).

[0060] In this way, the controller 60 controls the attachment driving device 23 so that the detected supporting force Fa (see FIG. 4D) is maintained at the target supporting force Ft (see FIG. 4D). Therefore, the attachment 15 (specifically, the support surface contact portion 15d) comes into contact with the supporting surface S5, and the machine body 10a travels on the traveling surface S1 while supporting the work machine 10 with the target supporting force Ft. Here, as shown in FIG. 4C and FIG. 4D, when the inclination of the traveling surface S1 changes, the inclination of the machine body 10a changes (for example, suddenly changes). Even in this case, the attachment 15 supports the work machine 10 with the target supporting force Ft, so that swaying and tipping of the work machine 10 are suppressed.

[0061] As described above, the work machine 10 shown in FIG. 1 may be manually operated by an operator in the cab 13c, may be manually operated by an operator via remote control, or may be automatically operated (automatically driven) by the controller 60 (automatic driving control unit 61) shown in FIG. 2. As shown in FIG. 4A, the operation of grounding the attachment 15 before the work machine 10 travels on the ground may be manual or automatic. As shown in FIG. 4B, the operation of the travel when the work machine 10 travels on the ground may be manual or automatic. The operation amount of the attachment 15 when the work machine 10 travels on the ground is automatically operated (controlled) by the controller 60. The operation of the rotation direction of the attachment 15 when the work machine 10 travels on the ground may be automatic or manual. When the rotation direction of the attachment 15 when the work machine 10 travels on the ground is manually operated, the controller 60 may limit the direction in which manual operation is possible.

[0062] (Specific examples include attachment ground running) When the working machine 10 travels with the attachment on the ground, the inclination of the travel surface S1 and the support surface S5 and the travel direction of the machine body 10a are various. The machine body 10a may go down the slope (see FIG. 4D, FIG. 6, FIG. 8, and FIG. 9, etc.) or up the slope (see FIG. 5 and FIG. 7). The travel direction of the machine body 10a may be forward (see FIG. 4A and FIG. 5, etc.) or reverse (see FIG. 6 and FIG. 7). As shown in FIG. 4A, the forward travel direction is the travel direction of the machine body 10a in which the travel front side D1 is the machine front side X1 (the side where the attachment 15 protrudes relative to the upper rotating body 13). As shown in FIG. 6, the reverse travel direction is the travel direction of the machine body 10a in which the travel front side D1 is the machine rear side X2. As shown in FIG. 4A, the travel surface S1 may include flat ground Sa or may include a slope Sb (similarly to the support surface S5). The flat ground Sa is a surface that extends in a horizontal or substantially horizontal direction. The slope Sb is a surface that is inclined more inclined relative to the horizontal direction than the flat ground Sa. Below, a specific example of the operation of the work machine traveling system 1 when the work machine 10 travels with the attachment on the ground will be described.

[0063] (Example 1-1: Moving forward downwards) An example (example 1-1) in which the machine body 10a moves forward, travels on flat ground Sa, and then descends a slope Sb will be described with reference to Figs. 4A, 4B, 4C, and 4D.

[0064] (Before attachment touchdown (state 1-1A)) As shown in FIG. 4A, a specific example of the state (state 1-1A) before the work machine 10 travels with the attachment on the ground is as follows. The lower traveling body 11 comes into contact with the flat ground Sa. Just as the contact of the support surface contact portion 15d with the support surface S5 is referred to as "contact with the ground," the contact of the lower traveling body 11 with the travel surface S1 (here, the flat ground Sa) is also referred to as "contact with the ground." The support surface contact portion 15d comes into contact with the slope Sb. The support surface contact portion 15d comes into contact with the ground at a position lower than the position where the lower traveling body 11 comes into contact with the ground. In this state, the controller 60 calculates the target supporting force Ft based on the pre-travel supporting force Fa0.

[0065] (Support capacity reduction pattern (condition 1-1B)) As shown in FIG. 4B, a specific example of a state (state 1-1B) in which the work machine 10 travels on flat ground Sa with the attachment on the ground is as follows. With the attachment 15 in contact with the support surface S5, the machine body 10a advances on the travel surface S1 (specifically, travels toward the travel front side D1 and the machine front side X1). Here, the center of gravity of the work machine 10 is directly above the flat ground Sa. At this time, the attachment 15 (specifically, the support surface contact portion 15d) tries to move away from the support surface S5 (in this example, the slope Sb). Then, the detected support force Fa becomes smaller than the target support force Ft (support force decreasing pattern). At this time, the controller 60 controls (support force control) the attachment driving device 23 (see FIG. 2) so that the detected support force Fa becomes larger. As a result, the detected support force Fa approaches the target support force Ft.

[0066] This control changes the attitude of the attachment 15. Specifically, the attitude of the attachment 15 is controlled so that the attachment 15 does not move away from the support surface S5 (slope Sb in this example). Thus, the attachment 15 maintains a state of contact with the support surface S5. At this time, the direction of movement of each part of the attachment 15 (boom 15a, arm 15b, and tip attachment 15c) differs depending on the structure (dimensions and shape) of the attachment 15, the inclination of the support surface S5, and the inclination of the running surface S1. For example, the boom 15a is rotated to the raising side (see FIG. 4B) or the lowering side (see FIG. 4C). The arm 15b is rotated to the side approaching the machine body 10a (pulling side). In addition, in Figure 4B, the position of attachment 15 when it is assumed that attachment 15 does not move relative to upper rotating body 13 while work machine 10 is traveling is shown by a two-dot chain line (the same applies to Figures 4C, 4D, and 5 to 8).

[0067] (Support capacity increase pattern (condition 1-1C, condition 1-1D)) As shown in FIG. 4C, the machine body 10a moves further forward from the state of state 1-1B (see FIG. 4B). Then, the center of gravity of the work machine 10 moves to the traveling front side D1 from the flat ground Sa, and moves directly above the slope Sb (state 1-1C). Then, the machine body 10a tries to rotate with the front lowered. More specifically, the machine body 10a tries to rotate in a direction in which the machine front side X1 part of the upper rotating body 13 moves downward (vertically downward). Then, the weight of the work machine 10 is transmitted from the attachment 15 to the support surface S5 (slope Sb in this example). At this time, the attachment 15 presses down the support surface S5 and receives a reaction force from the support surface S5. Then, the detected support force Fa becomes larger than the target support force Ft (support force increasing pattern). At this time, the controller 60 controls the attachment driving device 23 so that the detected support force Fa becomes smaller. As a result, the detected supporting force Fa approaches the target supporting force Ft (see FIG. 4D).

[0068] By this control, the machine body 10a shown in Fig. 4D gradually rotates downward with the front side while being supported by the attachment 15. At this time, the inclination angle of the machine body 10a with respect to the horizontal direction (referred to as the body angle θ) gradually increases. The traveling front side D1 portion of the lower traveling body 11 gradually approaches the slope Sb and comes into contact with the slope Sb (state 1-1D). When the machine body 10a rotates downward with the front side, the attitude of the attachment 15 changes. In the example shown in Fig. 4D, the boom 15a is rotated to the raising side, and the arm 15b is rotated to the pulling side.

[0069] (Suppression of rocking, etc.) Here, it is assumed that the controller 60 does not perform the support force control. In this assumption, the attachment 15 does not support the machine body 10a, as shown by the two-dot chain line in FIG. 4C. In this state, the inclination of the traveling surface S1 on which the machine body 10a travels changes. In the example shown in FIG. 4C, the machine body 10a moves from the flat ground Sa to the slope Sb. Then, the machine body 10a may become unstable. Specifically, the machine body 10a may swing or fall over. On the other hand, in this embodiment, the controller 60 performs the support force control. Therefore, the machine body 10a travels while the attachment 15 supports the machine body 10a with the target support force Ft (or approximately the target support force Ft). Therefore, even if the inclination of the traveling surface S1 changes and the body angle θ (see FIG. 4D) of the machine body 10a changes (even if the machine body 10a is tilted downward in this example), the machine body 10a can travel stably. Specifically, the machine body 10a is prevented from shaking and tipping over.

[0070] As described above, the detected supporting force Fa changes from a supporting force decreasing pattern to a supporting force increasing pattern (or vice versa) with the change in the inclination of the traveling surface S1. When this pattern changes, the rotation direction of each part of the attachment 15 may change. For example, the boom 15a may change from a state in which it is rotating toward the lowering side to a state in which it is rotating toward the raising side (see FIG. 4D) (or may change from the raising side to the lowering side). Also, for example, the arm 15b may change from a state in which it is rotating toward the pulling side to a state in which it is rotating toward the pushing side (or may change from the pushing side to the pulling side). The controller 60 may control the switching of the rotation direction of each part of the attachment 15 based on the relationship between the target supporting force Ft and the detected supporting force Fa (which is larger). Also, when the rotation direction of the attachment 15 is manually operated by the operator, the controller 60 may limit (specify, limit) the operation direction of the rotation of each part of the attachment 15.

[0071] As described below, the movement of the attachment 15 may be controlled so that the position of the support surface contact portion 15d with respect to the support surface S5 does not change when the work machine 10 travels with the attachment on the ground. The position of the support surface contact portion 15d with respect to the support surface S5 may change when the work machine 10 travels with the attachment on the ground.

[0072] (Example 1-2: Moving forward) An example (example 1-2) in which the machine body 10a moves forward, travels on flat ground Sa, and then climbs a slope Sb will be described with reference to Fig. 5. Differences between this example 1-2 and the above example 1-1 (forward downward movement) (see Figs. 4A to 4D) will be described.

[0073] (Before attachment touchdown (state 1-2A)) In a state (state 1-2A) before the work machine 10 travels with the attachment on the ground, the work machine 10 is in the same state as the above-mentioned state 1-1A (see FIG. 4A).

[0074] (Increased bearing capacity pattern (condition 1-2B)) A specific example of the state of the working machine 10 when the attachment travels on the ground is as follows. The machine body 10a advances on the travel surface S1 while the attachment 15 is in contact with the support surface S5 (state 1-2B). This advance causes the attachment 15 to push the support surface S5 (slope Sb in this example). Then, the detected support force Fa becomes larger than the target support force Ft (see FIG. 4C) (support force increasing pattern). Therefore, the controller 60 controls the attachment driving device 23 (see FIG. 1) so that the detected support force Fa becomes smaller. As a result, the detected support force Fa approaches the target support force Ft (see FIG. 4D). This control causes the posture of the attachment 15 to change. In the example shown in FIG. 5, when changing from state 1-2A to state 1-2B, the boom 15a is rotated to the lifting side, and the arm 15b is rotated to the pulling side.

[0075] (Support capacity reduction pattern (condition 1-2C)) The machine body 10a moves further forward from the state of state 1-2B described above. Then, the machine body 10a moves up the slope Sb (state 1-2C). At this time, the machine body 10a rotates with the front side raised. More specifically, the machine body 10a rotates in a direction in which the machine front side X1 portion of the upper rotating body 13 moves upward (vertically upward). Due to this rotation, the attachment 15 tries to move away from the support surface S5 (in this example, the slope Sb). Then, the detected support force Fa becomes smaller than the target support force Ft (see FIG. 4B) (support force decreasing pattern). At this time, the controller 60 controls the attachment driving device 23 (see FIG. 1) so that the detected support force Fa becomes larger. As a result, the detected support force Fa approaches the target support force Ft (see FIG. 4B).

[0076] This control changes the posture of the attachment 15. Specifically, the posture of the attachment 15 is controlled so that the attachment 15 does not move away from the support surface S5 (the slope Sb in this example). Therefore, the attachment 15 maintains a state in contact with the support surface S5. In the example shown in Fig. 5, when changing from state 1-2B to state 1-2C, the boom 15a is rotated downward and the arm 15b is rotated toward the pull side.

[0077] (Suppression of rocking, etc.) Here, if the machine body 10a travels from the flat ground Sa to the slope Sb without the attachment 15 supporting the machine body 10a, the machine body 10a may become unstable. On the other hand, in this embodiment, the machine body 10a travels while the attachment 15 supports the machine body 10a with the target support force Ft (or approximately the target support force Ft). Therefore, even if the inclination of the travel surface S1 changes and the body angle θ (see FIG. 4D) of the machine body 10a changes (even if the front of the machine body 10a is tilted upward in this example), the machine body 10a can travel stably. Specifically, the shaking and tipping over of the machine body 10a are suppressed.

[0078] (Example 1-3: Downhill reverse) 6, an example (Example 1-3) in which the machine body 10a moves backward, travels on flat ground Sa, and then descends a slope Sb will be described. Differences between this Example 1-3 and the above-mentioned Example 1-1 (forward downward movement) and Example 1-2 (forward upward movement) will be described.

[0079] (Before attachment touchdown (state 1-3A)) In the state (state 1-3A) before the work machine 10 travels with the attachment on the ground, the work machine 10 is in the same state as the above-mentioned state 1-1A (see FIG. 4A).

[0080] (Attachment ground running (state 1-3B)) With the attachment 15 in contact with the support surface S5, the machine body 10a moves backward on the travel surface S1 (i.e., travels toward the travel front side D1 and the machine rear side X2) (state 1-3B). Here, the center of gravity of the work machine 10 is directly above the flat ground Sa.

[0081] (Support capacity reduction pattern (condition 1-3C)) The machine body 10a moves further backward from the state of the above-mentioned state 1-3B. Then, the center of gravity of the work machine 10 moves to the traveling front side D1 from the flat ground Sa, and moves directly above the slope Sb. Then, the machine body 10a rotates downward toward the rear. More specifically, the machine body 10a rotates in a direction in which the machine rear side X2 portion of the upper rotating body 13 moves downward (vertically downward). Due to this rotation, the machine rear side X2 portion of the lower traveling body 11 contacts the slope Sb (state 1-3C). At this time, the attachment 15 tries to move away from the support surface S5 (in this example, the flat ground Sa). Then, the detected support force Fa becomes smaller than the target support force Ft (see FIG. 4B) (support force decreasing pattern). At this time, the controller 60 controls the attachment driving device 23 (see FIG. 1) so that the detected support force Fa becomes larger. As a result, the detected support force Fa approaches the target support force Ft (see FIG. 4B).

[0082] This control changes the posture of the attachment 15. Specifically, the posture of the attachment 15 is controlled so that the attachment 15 does not move away from the support surface S5 (flat ground Sa in this example). Therefore, the attachment 15 maintains a state in contact with the support surface S5. In the example shown in Fig. 6, when changing from state 1-3B to state 1-3C, the boom 15a is rotated to the lowering side, and the arm 15b is rotated to the pushing side.

[0083] (Suppression of rocking, etc.) In this example, the machine body 10a travels while the attachment 15 supports the machine body 10a with the target supporting force Ft (or approximately the target supporting force Ft). Therefore, even if the inclination of the travel surface S1 changes and the body angle θ (see FIG. 4D) of the machine body 10a changes (even if the machine body 10a tilts downward in this example), the machine body 10a can travel stably. Specifically, the shaking and tipping over of the machine body 10a are suppressed.

[0084] (Example 1-4: Uphill reverse) 7, a case where the machine body 10a moves backward, travels on flat ground Sa, and then moves up a slope Sb (Example 1-4) will be described. Differences between Example 1-4 and the above-mentioned Examples 1-1 (forward downward movement), 1-2 (forward upward movement), and 1-3 (backward downward movement) will be described.

[0085] (Before attachment touchdown (state 1-4A)) In a state (state 1-4A) before the work machine 10 travels with the attachment on the ground, the work machine 10 is in the same state as the above-mentioned state 1-1A (see FIG. 4A).

[0086] (Attachment ground running (state 1-4B)) With the attachment 15 in contact with the support surface S5, the machine body 10a moves backward on the travel surface S1 (state 1-4B).

[0087] (Increased bearing capacity pattern (condition 1-4C)) The machine body 10a moves further backward from the state 1-4B described above. Then, the machine body 10a climbs the slope Sb. At this time, the machine body 10a rotates rearward upward. More specifically, the machine body 10a rotates in a direction in which the machine rear side X2 portion of the upper rotating body 13 moves upward (vertically upward). This rotation causes the attachment 15 to press down the support surface S5 and support the work machine 10. Then, the detected support force Fa becomes larger than the target support force Ft (see FIG. 4C) (support force increasing pattern). Therefore, the controller 60 controls the attachment driving device 23 (see FIG. 1) so that the detected support force Fa becomes smaller. As a result, the detected support force Fa approaches the target support force Ft (see FIG. 4D). This control causes the posture of the attachment 15 to change. In the example shown in FIG. 7, when changing from state 1-4B to state 1-4C, the boom 15a is rotated to the raising side, and the arm 15b is rotated to the pushing side.

[0088] (Suppression of rocking, etc.) In this example, the machine body 10a travels while the attachment 15 supports the machine body 10a with the target supporting force Ft (or approximately the target supporting force Ft). Therefore, even if the inclination of the travel surface S1 changes and the body angle θ (see FIG. 4D) of the machine body 10a changes (even if the machine body 10a tilts upward at the rear in this example), the machine body 10a can travel stably. Specifically, the shaking and tipping over of the machine body 10a are suppressed.

[0089] (Example 1-5: Other examples) In each of the above examples (Example 1-1, Example 1-2, Example 1-3, and Example 1-4), the machine body 10a traveled from the flat ground Sa to the slope Sb. The machine body 10a may travel from the slope Sb to the flat ground Sa, or may travel from the slope Sb to a slope Sb having a different inclination from the slope Sb.

[0090] When the work machine 10 travels with the attachment on the ground, the support surface contact portion 15d is preferably disposed in front of the front traveling side D1 or the rear traveling side D2 of the lower running structure 11. When the work machine 10 travels with the attachment on the ground, it is preferable that the traveling fore-and-aft direction D and the machine fore-and-aft direction X coincide as much as possible. In this case, oscillation of the work machine 10 in the traveling fore-and-aft direction D is suppressed.

[0091] (Example 2: Control to maintain the position of the support surface contact portion 15d) When the working machine 10 shown in FIG. 8 travels with the attachment on the ground, the support surface contact portion 15d may move relative to the support surface S5 (not shown). For example, when the travel surface S1 and the support surface S5 are parallel or approximately parallel, the machine body 10a travels without moving the attachment 15 relative to the upper rotating body 13. In this case, the support surface contact portion 15d moves relative to the support surface S5 while in contact with the support surface S5 (is dragged by the support surface S5). At this time, since the travel surface S1 and the support surface S5 are parallel or approximately parallel, the machine body 10a can travel while the detected support force Fa (see FIG. 4A) remains constant or approximately constant and the detected support force Fa is maintained at the target support force Ft (see FIG. 4A). However, when the support surface contact portion 15d moves relative to the support surface S5, the attachment 15 may come into contact with an object (e.g., an obstacle) other than the support surface S5. Therefore, an excessive load may be applied to the attachment 15 and the attachment driving device 23 (see FIG. 1). In addition, when the support surface contact portion 15d moves relative to the support surface S5, the support surface S5 may be deformed (e.g., scraped). The deformation of the support surface S5 may be undesirable.

[0092] Therefore, when the work machine 10 travels with the attachment on the ground, it is preferable that the machine body 10a travels so that the attachment 15 is not dragged on the ground. Specifically, when the work machine 10 travels with the attachment on the ground, it is preferable that the controller 60 controls the attachment driving device 23 (see FIG. 1) so that the position of the support surface contacting part 15d with respect to the support surface S5 is maintained. This control is called "support position maintaining control." It is preferable that the controller 60 performs the support position maintaining control from before the attachment travels with the ground to during the attachment travels with the ground. The position of the support surface contacting part 15d with respect to the support surface S5 does not need to be maintained strictly. The controller 60 may control the attachment driving device 23 so that the support surface contacting part 15d moves with respect to the support surface S5 in a direction in which the position of the support surface contacting part 15d with respect to the support surface S5 is maintained.

[0093] A specific example of the support position maintenance control is as follows: The controller 60 controls the position of the support surface contact portion 15d with respect to the upper rotating body 13 based on the travel distance L1 traveled by the machine body 10a. Specifically, the controller 60 changes the attachment distance L2 based on the travel distance L1.

[0094] The travel distance L1 is the distance traveled by the machine body 10a. For example, the travel distance L1 may be the distance in the travel front-rear direction D, or the distance in the horizontal direction. For example, the travel distance L1 is the distance traveled by the machine body 10a in a unit time. The above-mentioned "unit time" may be the control cycle (control cycle) of the controller 60, the product of the control cycle and a predetermined number, or a specific number of seconds (such as 1 second). The controller 60 may acquire the travel distance L1 based on the amount by which the lower traveling body 11 is driven. Specifically, the controller 60 may acquire (calculate) the travel distance L1 based on the amount of drive (such as the number of rotations) of the traveling motor 21 (see FIG. 1). The calculation is included in the acquisition (same below). The controller 60 may acquire the travel distance L1 from the detection result of the reference position sensor 41 (see FIG. 1). The controller 60 may acquire the travel distance L1 based on an image including the traveling surface S1 and the lower traveling body 11 captured by the imaging device 51 (see FIG. 1).

[0095] The attachment distance L2 is a distance from a specific position of the upper rotating body 13 to a specific position of the tip attachment 15c (specifically, a specific position of an element of the attachment 15 including the support surface contact portion 15d). For example, the attachment distance L2 may be a distance in the travel front-rear direction D, or a distance in the horizontal direction. The "specific position of the upper rotating body 13" may be, for example, the position of the rotation central axis 13a, or the attachment position of the boom 15a to the upper rotating body 13 (the position of the boom foot). The "specific position of the tip attachment 15c" may be, for example, the bucket tip 15c1, a specific position (such as the center) of the bucket bottom 15c5 (see FIG. 1), or a connection portion of the tip attachment 15c to the arm 15b. The controller 60 may acquire the attachment distance L2 from the attitude of the attachment 15 detected by the attitude sensor 40 (see FIG. 2). The controller 60 may obtain the attachment distance L2 based on an image including the upper rotating body 13 and the attachment 15 captured by the imaging device 51 (see FIG. 2).

[0096] When the machine body 10a moves forward (when the traveling front side D1 is the machine front side X1), the controller 60 performs the following control. In this case, the controller 60 moves the support surface contact portion 15d to the machine rear side X2 with respect to the upper rotating body 13 (i.e., moves closer to the upper rotating body 13) so that the attachment distance L2 becomes smaller by the traveling distance L1. Specifically, the controller 60 acquires the attachment distance L2 (pre-travel distance L2a) at a certain point in time (for example, before traveling). From this point in time, the machine body 10a moves forward by the traveling distance L1. At this time, the controller 60 sets the distance obtained by subtracting the traveling distance L1 from the pre-travel distance L2a as the target distance L2b of the attachment distance L2. Then, the controller 60 controls the attachment driving device 23 (see FIG. 1) so that the actual attachment distance L2 becomes this target distance L2b.

[0097] Contrary to when the machine body 10a moves forward, when the machine body 10a moves backward, the controller 60 moves the support surface contact portion 15d to the front side X1 of the machine (i.e., away from the upper rotating body 13) so that the attachment distance L2 is increased by the traveling distance L1.

[0098] When the work machine 10 travels with the attachment on the ground, the inclination of the travel surface S1 on which the machine body 10a travels changes. For example, in the example shown in FIG. 8, the machine body 10a moves from flat ground Sa to a slope Sb (changing from state 2A to state 2B). Even after the inclination of the travel surface S1 changes, the controller 60 controls the attachment drive device 23 (see FIG. 1) so that the position of the support surface contact portion 15d relative to the support surface S5 is maintained. For example, when the machine body 10a travels on the slope Sb, the controller 60 may control the attachment distance L2 in the travel front-rear direction D based on the travel distance L1 in the travel front-rear direction D. The controller 60 may also convert the travel distance L1 in the travel front-rear direction D to the travel distance L1 in the horizontal direction based on the body angle θ, and control the attachment distance L2 in the horizontal direction.

[0099] The controller 60 may detect a positional deviation (movement) of the support surface contact portion 15d relative to the support surface S5 based on an image including the support surface S5 and the support surface contact portion 15d captured by the imaging device 51 (see FIG. 2). When the position of the support surface contact portion 15d relative to the support surface S5 has deviated (for example, when it has deviated by a predetermined amount or more), the controller 60 may perform the following process. In this case, the controller 60 may control the attachment driving device 23 (see FIG. 1) to eliminate or reduce the deviation of the support surface contact portion 15d relative to the support surface S5.

[0100] (Example 3: Setting the target bearing force Ft based on additional information) As described above, the controller 60 sets the target support force Ft based on the pre-traveling support force Fa0 (see FIG. 4A). As shown in FIG. 10, the controller 60 may set the target support force Ft based on the pre-traveling support force Fa0 and information other than the pre-traveling support force Fa0. The information other than the pre-traveling support force Fa0 (hereinafter also referred to as "additional information") may include the state of the work machine 10 shown in FIG. 9, or may include the state of the travel surface S1 around the work machine 10. For example, the additional information may include information on the attitude of the attachment 15. The additional information may include information on the travel speed V of the machine body 10a (see FIG. 11). The additional information may include information on the inclination of the travel surface S1, or may include information on the inclination (body angle θ) of the machine body 10a. The additional information may be one piece of information or a plurality of pieces of information among the above pieces of information.

[0101] By setting the target support force Ft based on the pre-traveling support force Fa0 and the additional information, the controller 60 can set an appropriate target support force Ft according to the state of the work machine 10 or the state of the travel surface S1 around the work machine 10. As a result, the support force F is prevented from being too high or too low. Here, if the support force F is too high, the attachment 15 may lift the machine body 10a from the travel surface S1 (the machine body 10a may rise up). If the support force F is too high, power (unnecessary power, wasted power) that exceeds the power required for stable travel of the work machine 10 is required. If the support force F is too low, the effect of suppressing the rocking of the machine body 10a when the inclination of the travel surface S1 changes is limited. If the support force F is too low in the support force reduction pattern, the attachment 15 may move away from the support surface S5.

[0102] On the other hand, in this example 3, the controller 60 sets the target support force Ft based on the pre-travel support force Fa0 and the additional information. Therefore, the support force F is prevented from being too high or too low. Therefore, problems caused by the support force F being too high or too low are prevented.

[0103] Specifically, for example, the controller 60 may set the pre-traveling supporting force Fa0 as the "pre-correction target supporting force Ft" (an example of the target supporting force value Fta) (see FIG. 4A). The controller 60 corrects the "pre-correction target supporting force Ft" based on the additional information to set it as the "corrected target supporting force Ft". Then, the controller 60 may set the "corrected target supporting force Ft" as the target supporting force Ft used in the supporting force control (step S50 in FIG. 3).

[0104] A specific example in which the controller 60 sets the target supporting force Ft based on the pre-traveling supporting force Fa0 and the additional information is as follows.

[0105] (Example 3-1: Posture of attachment 15) The controller 60 may set the target supporting force Ft based on the pre-traveling supporting force Fa0 (see FIG. 4A) and the attitude of the attachment 15 (an example of additional information).

[0106] The reason why the controller 60 sets the target supporting force Ft based on the posture of the attachment 15 shown in Fig. 9 is as follows. Here, the overturning moment M due to the weight (mass) of the attachment 15 will be considered. This overturning moment M is a moment at which the weight of the attachment 15 rotates the work machine 10 to the machine front side X1 around the end (tipping fulcrum 11t) of the lower traveling body 11 on the machine front side X1. The magnitude of the overturning moment M is the product of the distance L3 and the weight (mass) of the attachment 15. The distance L3 is the horizontal distance from the tipping fulcrum 11t to the center of gravity of the attachment 15 (referred to as the attachment center of gravity G15). The closer the attachment center of gravity G15 is to the upper rotating body 13 (i.e., toward the machine rear side X2), the smaller the overturning moment M becomes. Therefore, the smaller the overturning moment M, the smaller the supporting force F required to support the work machine 10.

[0107] For example, when the work machine 10 performs the attachment ground contact traveling and the support surface contact portion 15d approaches the upper rotating body 13, the distance L3 becomes shorter (for example, a change from state 3A to state 3B). As a result, the overturning moment M becomes smaller, and the supporting force F required to support the work machine 10 becomes smaller. Also, for example, when the work machine 10 performs the attachment ground contact traveling and the support surface contact portion 15d moves away from the upper rotating body 13 (see Figures 6 and 7), the distance L3 becomes longer (for example, a change from state 3B to state 3A). As a result, the overturning moment M becomes smaller, and the supporting force F required to support the work machine 10 becomes larger.

[0108] Therefore, it is preferable that the controller 60 sets the target supporting force Ft based on the attitude of the attachment 15. More specifically, it is preferable that the controller 60 sets the target supporting force Ft based on the overturning moment M. Specifically, as shown in FIG. 10, the controller 60 sets the target supporting force Ft (Ft-M2) when the overturning moment M is a second value (M2) to be greater than the target supporting force Ft (Ft-M1) when the overturning moment M is a first value (M1). Here, the second value (M2) is greater than the first value (M1). For example, the controller 60 sets the target supporting force Ft to a smaller value as the overturning moment M becomes smaller. For example, the controller 60 sets the target supporting force Ft to a larger value as the overturning moment M becomes larger. Specifically, for example, the controller 60 may set the target supporting force Ft to a linear function of the overturning moment M.

[0109] 10, when the overturning moment M is within a specific range, the controller 60 decreases the target supporting force Ft as the overturning moment M decreases. In this case, the controller 60 may keep the target supporting force Ft constant when the overturning moment M is outside the specific range.

[0110] FIG. 10 shows an example in which the machine body 10a moves forward and the position of the support surface contact portion 15d relative to the support surface S5 is maintained (see, for example, FIGS. 4A to 4D, 5, and 9). In detail, the pre-travel support force Fa0 (pre-correction target support force Ft) before the working machine 10 travels with the attachment on the ground is the maximum value of the target support force Ft. Then, as shown in FIG. 9, the machine body 10a moves forward, the distance L3 becomes smaller, and the overturning moment M becomes smaller, as shown in FIG. 10, the controller 60 reduces the target support force Ft. Note that, when the machine body 10a moves backward and the position of the support surface contact portion 15d relative to the support surface S5 is maintained (see FIGS. 6 and 7), the pre-travel support force Fa0 is set to the minimum value of the target support force Ft. Note that the relationship between the overturning moment M and the target support force Ft shown in FIG. 10 is one example and can be changed in various ways.

[0111] (Example 3-2: Traveling speed V) As shown in FIG. 11, the controller 60 may set the target supporting force Ft based on the pre-traveling supporting force Fa0 and the traveling speed V of the machine body 10a (an example of additional information).

[0112] The reason why the controller 60 sets the target support force Ft based on the traveling speed V is as follows. As shown in FIG. 8, when the inclination of the traveling surface S1 on which the machine body 10a travels (forward or backward) changes, the machine body 10a may sway. Due to the swinging of the machine body 10a, the support surface contact portion 15d presses the support surface S5 and receives a reaction force (dynamic support reaction force) from the support surface S5. The faster the traveling speed V (see FIG. 11), the more likely the machine body 10a is to swing. Therefore, the faster the traveling speed V, the greater the support force F required to suppress the swinging of the work machine 10.

[0113] Furthermore, when the machine body 10a moves forward, depending on the angle between the traveling surface S1 and the support surface S5, the support surface contact portion 15d (see FIG. 8) may push the support surface S5 toward the traveling front side D1. In this case, the support surface contact portion 15d receives a reaction force (support reaction force due to traveling) from the support surface S5. The faster the traveling speed V, the greater the support reaction force due to traveling. Therefore, the faster the traveling speed V, the greater the supporting force F required to support the work machine 10 against (against) the reaction force received from the support surface S5.

[0114] Therefore, it is preferable that the controller 60 sets the target support force Ft based on the traveling speed V as shown in FIG. 11. Specifically, the controller 60 sets the target support force Ft (Ft-V2) when the traveling speed V is a second value (V2) to be greater than the target support force Ft (Ft-V1) when the traveling speed V is a first value (V1). Here, the second value (V2) is greater than the first value (V1). For example, the controller 60 sets the target support force Ft to a greater value as the traveling speed V increases. For example, the controller 60 sets the target support force Ft to a smaller value as the traveling speed V decreases. Specifically, for example, the controller 60 may set the target support force Ft to a linear function of the traveling speed V.

[0115] In the example shown in Fig. 11, the controller 60 sets the pre-traveling supporting force Fa0 (target supporting force Ft before correction) as the minimum value of the target supporting force Ft. When the traveling speed V is within a range from 0 to a predetermined speed, the controller 60 increases the target supporting force Ft as the traveling speed V increases. When the traveling speed V is higher than the predetermined speed, the controller 60 may set the target supporting force Ft to be constant. Note that the relationship between the traveling speed V and the target supporting force Ft shown in Fig. 11 is an example and can be changed in various ways.

[0116] (Example 3-3: Tilt angle) The controller 60 may set the target supporting force Ft based on the pre-traveling supporting force Fa0 and the inclination angle of the machine body 10a (referred to as the body angle θ) as shown in FIG.

[0117] The reason why the controller 60 sets the target supporting force Ft based on the body angle θ is as follows. The force with which the support surface contact portion 15d presses the support surface S5 changes depending on the body angle θ shown in Fig. 9. Specifically, when the machine body 10a is tilted downward at the front, the larger the body angle θ (the greater the inclination), the greater the force with which the support surface contact portion 15d presses the support surface S5, and the greater the reaction force that the support surface contact portion 15d receives from the support surface S5. Therefore, the larger the body angle θ, the greater the supporting force F required to support the work machine 10 against (against) the reaction force received from the support surface S5.

[0118] On the other hand, when the machine body 10a is tilted upward at the front (see Figs. 5 and 6), the larger the body angle θ (the greater the inclination), the smaller the force with which the support surface contact portion 15d presses the support surface S5, and the smaller the reaction force that the support surface contact portion 15d receives from the support surface S5. Therefore, the larger the body angle θ, the smaller the supporting force F required to support the work machine 10 against (against) the reaction force received from the support surface S5.

[0119] Therefore, it is preferable that the controller 60 sets the target supporting force Ft based on the main body angle θ detected by the tilt sensor 43, as shown in FIG.

[0120] For example, when the machine body 10a is tilted downward at the front, the controller 60 sets the target supporting force Ft (Ft-θ2) when the body angle θ is a second value (θ2) to be greater than the target supporting force Ft (Ft-θ1) when the body angle θ is a first value (θ1). Here, the second value (θ2) is greater than the first value (θ1). For example, as shown in FIG. 9, when the machine body 10a is tilted downward at the front, the controller 60 sets the target supporting force Ft to a greater value as the body angle θ increases.

[0121] Furthermore, when the machine body 10a is front-up (see Figs. 5 and 6), the controller 60 sets the target supporting force Ft when the body angle θ is a second value (θ2) to be smaller than the target supporting force Ft when the body angle θ is a first value (θ1) (not shown). For example, when the machine body 10a is front-up, the controller 60 sets the target supporting force Ft to a smaller value as the body angle θ increases.

[0122] 10 and 11 show an example in which the additional information is the body angle θ and additional information other than the body angle θ (specifically, the overturning moment M or the traveling speed V). On the other hand, the additional information may be only the body angle θ. The controller 60 may set the target supporting force Ft based only on the pre-travel supporting force Fa0 and the body angle θ.

[0123] (Effects of the first invention) The effects of the work machine traveling system 1 shown in Fig. 1 are as follows. The work machine traveling system 1 includes a machine body 10a, an attachment 15, an attachment driving device 23, a supporting force sensor 31 (see Fig. 2), and a controller 60. The machine body 10a is the main body of the work machine 10 and is capable of traveling. The attachment 15 is attached to the machine body 10a so that it can be raised and lowered. The attachment driving device 23 drives the attachment 15.

[0124] [Configuration 1] The support force sensor 31 (see FIG. 2) detects the support force F. The support force F is a force acting from the attachment 15 to the support surface S5 when the attachment 15 comes into contact with the support surface S5. The controller 60 acquires the pre-traveling support force Fa0 shown in FIG. 4A (see step S31 in FIG. 3). The pre-traveling support force Fa0 is the support force F detected by the support force sensor 31 (see FIG. 2) when the attachment 15 comes into contact with the support surface S5 and before the machine body 10a travels. The controller 60 sets a target support force Ft based on the pre-traveling support force Fa0 (see step S32 in FIG. 3). The controller 60 performs the following process when the attachment 15 comes into contact with the support surface S5 and the machine body 10a is traveling (during attachment grounding traveling). As shown in FIG. 4D, the controller 60 controls the attachment driving device 23 (see FIG. 1) so that the supporting force F (detected supporting force Fa) detected by the supporting force sensor 31 is maintained at the target supporting force Ft when the attachment is traveling with the ground on the ground (see step S50 in FIG. 3).

[0125] The above [Configuration 1] makes it possible to maintain the supporting force F when the work machine 10 is traveling with the attachment on the ground at the target supporting force Ft or approximately the target supporting force Ft. Therefore, the machine body 10a can travel while the attachment 15 supports the machine body 10a at the target supporting force Ft or approximately the target supporting force Ft. Therefore, even if there is a change in the inclination of the traveling surface S1 on which the work machine 10 travels, the work machine 10 can travel stably. Specifically, it is possible to suppress rocking and tipping of the work machine 10 when the work machine 10 travels.

[0126] (Effects of the second invention) [Configuration 2] The target supporting force Ft is the pre-traveling supporting force Fa0 (see the target supporting force value Fta in FIG. 4D).

[0127] In the above [Configuration 2], the controller 60 can set the target supporting force Ft by a simple process. For example, compared to the case where the controller 60 sets the target supporting force Ft based on the pre-traveling supporting force Fa0 and the above additional information, the controller 60 can set the target supporting force Ft by a simple process.

[0128] (Effects of the third invention) [Configuration 3] The controller 60 performs the following process while the machine body 10a is traveling. As shown in Fig. 8, the controller 60 controls the attachment driving device 23 (see Fig. 1) so that the portion of the attachment 15 that is in contact with the support surface S5 (support surface contact portion 15d) is kept in position relative to the support surface S5.

[0129] The above [Configuration 3] enables the attachment 15 to reliably support the working machine 10 while it is traveling. Furthermore, the above [Configuration 3] prevents the attachment 15 from coming into contact with an object (obstacle) other than the support surface S5. This prevents the attachment 15 from coming into contact with an obstacle, which would result in excessive load being placed on the attachment 15 and the attachment drive device 23 (see FIG. 1).

[0130] (Effect of the fourth invention) [Configuration 4] The controller 60 sets the target supporting force Ft based on one or more of the following information in addition to the pre-traveling supporting force Fa0: Information on the posture of the attachment 15 shown in FIG. 9; Information on the traveling speed V of the machine body 10a (see FIG. 11); Information on the inclination (body angle θ) of the traveling surface S1 on which the machine body 10a travels.

[0131] The above [Configuration 4] provides the following effect. The support force F changes depending on the posture of the attachment 15, the traveling speed V (see FIG. 11), and the inclination of the traveling surface S1 (main body angle θ) (as described above in detail). Therefore, in the above [Configuration 4], the controller 60 sets the target support force Ft based on one or more pieces of information among the posture information of the attachment 15, the traveling speed V, and the inclination information of the traveling surface S1 (see FIG. 10 and FIG. 11). Therefore, the controller 60 can set an appropriate target support force Ft according to these pieces of information, compared to a case where the target support force Ft is set without being based on these pieces of information.

[0132] (Modification) The above embodiment may be modified in various ways. For example, the modified examples of the above embodiment may be combined in various ways. For example, the number of components (including modified examples) of the above embodiment may be changed, and some of the components may not be provided. For example, the components may be fixed or connected directly or indirectly. For example, the connection of each component shown in FIG. 2 may be changed. For example, the arrangement of the components may be changed. For example, the inclusion relationship of the components may be changed in various ways. For example, a component described as a lower component included in a higher-level component may not be included in this higher-level component, and may be included in another component. For example, a component described as a plurality of different members or parts may be treated as a single member or part. For example, a component described as a single member or part may be provided as a plurality of different members or parts. For example, the order of the steps in the flowchart shown in FIG. 3 may be changed, and some of the steps may not be performed. For example, the various parameters used for controlling the controller 60 (see FIG. 2) may not be the same as the various parameters, and may be parameters that can be converted into the various parameters. For example, the controller 60 may perform substantially the same processes (calculation, determination, etc.) as those in the above-described embodiment (including modified examples). The controller 60 may perform various combinations of the various processes. For example, each component may have only a part of each feature (function, arrangement, shape, operation, etc.). [Explanation of symbols]

[0133] 1 Work machine travel system 10. Working Machinery 10a Machine body 15 Attachment 23 Attachment drive device 31 Support force sensor 60 Controller F Supporting capacity Fa0 Support force before running Ft Target bearing capacity S1 Running surface S5 support surface

Claims

1. A machine main body which is a main body of a working machine and is capable of traveling; an attachment attached to the machine body in a manner that allows it to be raised and lowered; an attachment driving device that drives the attachment; a support force sensor that detects a support force acting on a support surface from the attachment when the attachment comes into contact with the support surface; A controller; Equipped with The controller: A pre-travel support force, which is the support force detected by the support force sensor when the attachment is in contact with the support surface and before the machine body travels, is acquired; A target support force is set based on the pre-travel support force, controlling the attachment driving device so that the supporting force detected by the supporting force sensor is maintained at the target supporting force when the attachment is in contact with the supporting surface and the machine body is traveling; Work machine traction system.

2. 2. A work machine travel system according to claim 1, The target supporting force is the supporting force before traveling. Work machine traction system.

3. 2. A work machine travel system according to claim 1, the controller controls the attachment drive device so that a position of a portion of the attachment in contact with the support surface is maintained relative to the support surface while the machine body is traveling. Work machine traction system.

4. 2. A work machine travel system according to claim 1, The controller further sets the target supporting force based on one or more of the following information: information on the posture of the attachment, information on the running speed of the machine body, and information on the inclination of a running surface on which the machine body runs. Work machine traction system.

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