JP2020033789A - Blade control device of work machine - Google Patents

Abstract

To provide a blade control device enabling swell of a formation level to be effectively suppressed.SOLUTION: A blade operation control part 15 in a blade control device 100 outputs an instruction for causing a blade 4 to ascend/descend so that a positional deviation Δx between a blade target position xref and a blade position x calculated by a blade position calculation part 12 comes close to zero when a blade load f is a second load threshold f2 or below, and outputs an instruction for causing the blade 4 to ascend when the blade load f is greater than the second load threshold f2. A target position setting part 14 updates the blade target position xref on the basis of the blade position x when a preset update condition in which the blade load f is correlated with a first load threshold f1 is satisfied.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a blade control device provided in a work machine having a blade.

  2. Description of the Related Art Conventionally, work machines provided with blades used for excavating the ground, leveling the ground, and transporting earth and sand have been widely used. Patent Literature 1 discloses a bulldozer load control device that automatically controls the raising and lowering operations of a blade so that the blade load applied to the blade becomes substantially constant. However, in the load control device described in Patent Literature 1, the undulation of the construction surface caused by moving the blade up and down becomes a problem.

  Patent Literature 2 discloses a blade control device for addressing the above problem of Patent Literature 1. Patent Document 2 discloses that the blade is controlled such that the blade does not approach the design surface more than the virtual design surface, and that the blade can be prevented from descending greatly, whereby a continuous swell is formed on the excavation surface. It is disclosed that this can be suppressed. In the blade control device described in Patent Literature 2, when the blade load is smaller than the first set load value, the blade is lowered, and the blade load is changed from the second set load value larger than the first set load value. Raise the blade if too big. That is, in the blade control device described in Patent Literature 2, the raising / lowering operation of the blade is controlled based on a comparison between the blade load and the first set load value and the second set load value.

Japanese Patent No. 3537182 Japanese Patent No. 5285805

  In the blade control device described in Patent Literature 2 described above, when the blade is located above the virtual design surface, the raising / lowering operation of the blade is controlled based on the blade load, and controlled based on the position of the blade. Therefore, the undulation of the construction surface largely depends on the increase and decrease of the blade load. For this reason, in the blade control device of Patent Literature 2, the effect of suppressing the undulation of the construction surface is limited, and is not necessarily sufficient.

  The present invention provides a blade control device provided in a work machine equipped with a blade for controlling the raising and lowering operation of the blade, wherein the blade control device can effectively suppress undulation of a construction surface. The purpose is to:

  Provided is a blade control device provided on a work machine including a machine main body and a blade attached to the machine main body so as to be able to move up and down, and controlling a raising and lowering operation of the blade, A target design surface setting unit that sets a target design surface that specifies a target shape to be excavated by the blade, a position information acquisition unit that acquires position information about the work machine, and the position information that is acquired by the position information acquisition unit. A blade position calculating unit that calculates a blade position that is the position of the blade in a global coordinate system, a blade load obtaining unit that obtains a blade load that is a load applied to the blade, and a threshold value of the blade load. A storage for storing a first load threshold and a second load threshold that is a threshold of the blade load and is larger than the first load threshold. A target position setting unit that sets a blade target position that is a target position of the blade position and is a position above the target design plane, and the blade load acquired by the blade load acquisition unit is the blade load. When the load is equal to or less than the second load threshold, a command for elevating and lowering the blade is output so that a position deviation, which is a deviation between the blade position calculated by the blade position calculator and the blade target position, approaches zero. And when the blade load acquired by the blade load acquisition unit is greater than the second load threshold, a blade operation control unit that outputs a command to raise the blade, and the target position The setting unit associates the blade load with the first load threshold, and when a preset update condition is satisfied, the update condition is determined. Based on the said blade position when are met to update the blade target position.

  When the blade load is larger than the second load threshold, the blade control device of the present invention performs control to raise the blade, thereby preventing a stack or the like due to an excessive load from occurring, and stably running the work machine. enable. On the other hand, when the blade load is equal to or less than the second load threshold, the controller controls the raising / lowering operation of the blade such that the positional deviation between the blade position and the blade target position approaches zero. In this manner, even when the blade load is equal to or less than the second load threshold, performing position control of the blade so that the position deviation approaches zero, the blade load is controlled to the second set load value as in Patent Document 2 described above. Also in the following cases, it is possible to effectively suppress the undulation of the construction surface as compared with the device described in Patent Document 2 in which the elevating operation of the blade is controlled based on the blade load. And the effective suppression of the undulation of the construction surface improves the efficiency of the excavation work.

  Further, in the blade control device of the present invention, the first load threshold is set to a value corresponding to an appropriate blade load at which the work machine can run stably. The update condition is set in advance by associating the actual blade load that fluctuates during the excavation work with the first load threshold value that is a value corresponding to an appropriate blade load. Since the blade target position is updated based on the blade position when the update condition is satisfied, the blade target position is associated with the blade position when the blade load is appropriate. Therefore, by repeatedly updating the blade target position in the excavation work, the blade load during the excavation work is easily stabilized regardless of the state of the ground to be excavated (for example, the hardness of the earth and sand, the type of earth and sand, etc.). Become.

  Further, in the blade control device of the present invention, the second load threshold is a value set in order to prevent occurrence of a situation in which a blade load becomes excessive and a stack or the like occurs, and the first load threshold is the first load threshold. This value is larger than the load threshold. According to the present invention, when the blade load becomes larger than the second load threshold, control for raising the blade is performed. This reduces the blade load as described above, and prevents a stack or the like due to an excessive load from occurring, thereby enabling stable running of the work machine.

  From the above, the blade control device of the present invention can effectively suppress the undulation of the construction surface, and also enables a stable and efficient excavation operation of the working machine.

  In the blade control device, the update condition may include a condition that the blade load reaches the first load threshold, or the first load threshold for determining that the blade load has approached the first load threshold. It is preferable to include a condition that the blade load reaches a determination value set based on the blade load. In this aspect, the blade target position is updated based on the blade position when the blade load has reached or approached the first load threshold, so that the blade target position substantially matches the blade position when the blade load is appropriate. It will be. Therefore, the blade load during the excavation work is more easily stabilized.

  In the blade control device, the storage unit stores a first state indicating that the update of the blade target position is permitted when the blade load becomes larger than a flag threshold value that is a preset threshold value, When the blade target position is updated, a second state indicating that the update of the blade target position is not permitted is stored in place of the first state, and the update condition is that the first state is the storage state. The condition that the blade load reaches the first load threshold when stored in the storage unit, or the condition that the blade load reaches the first load threshold when the first state is stored in the storage unit. A condition that the blade load reaches a determination value set based on the first load threshold value in order to determine that the blade load has approached. In this aspect, while the update of the blade target position is permitted when the update flag of the blade target position is in the first state, the update of the blade target position is not permitted when the update flag is in the second state. Frequent updating of the blade target position can be suppressed.

  In the blade control device, the blade target position updated by the target position setting unit is set to a position on a plane passing through the blade position when the update condition is satisfied and parallel to the target design plane. Is preferred. In this aspect, the lifting / lowering operation of the blade is controlled such that the positional deviation between the blade target position and the blade position set at a position on a plane parallel to the target design surface approaches zero. The efficiency of the excavation work to bring the distance closer to the target design surface is further improved.

  In the blade control device, the storage unit stores a target trajectory that is a target of the blade load increase process when the blade load approaches the first load threshold while increasing, the blade operation control unit includes: Before the blade target position is set by the target position setting unit, a command for raising and lowering the blade so that the blade load approaches the first load threshold while following an increasing process close to the target trajectory is issued. It may be configured to output. When the target trajectory is set as in this aspect, even before the blade target position is set, the blade load approaches the first load threshold while following an increasing process close to the target trajectory. In addition, it is possible to prevent the blade from entering the ground at an appropriate descending speed and increase the depth of the blade entering the ground when the blade load reaches the first load threshold. As a result, the change in the amount of soil on the blade with respect to the travel distance of the work machine is small, and the change in the blade load is also small. As a result, the effect of suppressing undulation on the construction surface can be further enhanced. Then, in this aspect, when the blade load reaches or approaches the first load threshold while following an increasing process close to the target trajectory and the update condition is satisfied, the blade target position is set by the target position setting unit. Is done. Then, after the blade target position is set, the blade operation control unit controls the raising / lowering operation of the blade so that the positional deviation between the blade position and the blade target position approaches zero.

  The blade control device further includes a load threshold setting unit that sets the first load threshold, the position information acquisition unit includes a vehicle body position acquisition unit that acquires a vehicle body position that is a position of the machine main body, The threshold setting unit is configured such that the main body distance is smaller than the first distance than when the main body distance that is a distance between the vehicle body position acquired by the vehicle body position acquisition unit and the target design surface is a first distance. The first load threshold may be updated such that the first load threshold becomes smaller when the distance is the second distance. In this aspect, when the main body distance is the second distance (that is, when the machine main body is close to the target design surface), when the main body distance is the first distance (that is, the machine main body) Is far from the target design surface), the blade load more easily reaches the first load threshold. This increases the frequency of updating the blade target position, and increases the possibility that the blade target position is set to a more appropriate position corresponding to the state of the ground to be excavated. The following are specific examples of this embodiment. For example, the first load threshold when the leveling operation is performed in the final stage of the operation by the work machine is set to a value smaller than the first load threshold when the excavation operation is performed in the initial stage or the intermediate stage of the operation. Is set. In such a case, the same control algorithm can be used for both the excavation operation where quick excavation work is more important than the leveling operation and the leveling operation where emphasis is placed on the accuracy of bringing the construction surface closer to the target design surface. become.

  In the blade control device, the blade operation control unit includes, as a variable, a position deviation that is a height difference between the blade position and the blade target position, based on a function having a term including a position gain that is multiplied by the position deviation. Outputting the command, the blade control device further includes a position gain setting unit that sets the position gain, wherein the position gain setting unit sets the position when the blade position is lower than the blade target position. Preferably, the position gain is updated such that the rising speed of the blade increases based on the deviation. In this aspect, since the rising speed of the blade is increased when the blade position is below the blade target position, the effect of suppressing the ground to be excavated from being excavated below the blade target position is further enhanced. As a result, the effect of suppressing the ground from being excavated below the target design surface is further enhanced.

  In the blade control device, the function further includes a term including a load deviation that is a deviation obtained by subtracting the second load threshold from the blade load as a variable and including a load gain by which the load deviation is multiplied. The blade control device further includes a load gain setting unit configured to set the load gain, wherein the load gain setting unit is configured to control the blade based on the load deviation when the blade load is greater than the second load threshold. It is preferable to update the load gain so that the rising speed of the load increases. In this aspect, when the blade load is greater than the second load threshold, the blade ascending speed is increased, so that the blade load is reduced more quickly, a stack or the like due to an excessive load is prevented, and the working machine is stabilized. The effect of enabling traveling can be further enhanced.

  As described above, according to the present invention, there is provided a blade control device capable of effectively suppressing undulation on a construction surface.

1 is a side view illustrating a hydraulic excavator as an example of a work machine on which a blade control device according to an embodiment of the present invention is mounted. FIG. 3 is a block diagram illustrating main functions of the blade control device. 5 is a graph showing a relationship between a blade position, a blade target position, and a blade elevating operation in the blade control device. 4 is a graph showing a relationship among a blade load, a first load threshold, a second load threshold, and a blade elevating operation in the blade control device. 4 is a flowchart illustrating an example of a control operation executed by a controller included in the blade control device. 4 is a graph showing a target trajectory of a blade load and a transition of an actual blade load in the blade control device. 5 is an example of a time chart for explaining a blade target position updated based on a blade load in the blade control device. 9 is another example of a time chart for explaining a blade target position updated based on a blade load in the blade control device. FIG. 7 is a schematic diagram for explaining updating of a first load threshold based on a distance between a vehicle body position of a machine main body and a target design surface in the blade control device. 6 is a graph for explaining updating of a first load threshold based on a distance between a vehicle body position of a machine body and a target design surface in the blade control device. 9 is a graph for explaining that the blade control device updates a position gain based on a deviation between a blade position and a blade target position. 9 is a graph for explaining that the blade controller updates a load gain based on a deviation between a blade load and a second load threshold. It is the schematic which compared the construction surface by the working machine provided with the said blade control apparatus, and the construction surface by the conventional working machine.

  Preferred embodiments of the present invention will be described with reference to the drawings.

[Overall structure of work machine]
FIG. 1 is a side view showing a hydraulic excavator 1 as an example of a work machine on which a blade control device according to an embodiment of the present invention is mounted. The hydraulic excavator 1 includes a traveling device 2 (a lower traveling body) that can travel on the ground G, a vehicle body 3 (an upper revolving superstructure) mounted on the traveling device 2, and a working device mounted on the vehicle body 3. And a blade 4 mounted on the traveling device 2 or the vehicle body 3. The traveling device 2 and the vehicle body 3 constitute a machine body of the work machine. The vehicle body 3 has a turning frame, an engine, a cab, and the like.

  The working device mounted on the vehicle body 3 includes a boom 5, an arm 6, and a bucket 7. The boom 5 has a base end supported at the front end of the revolving frame so as to be able to undulate, that is, rotatable around a horizontal axis, and a tip end on the opposite side. The arm 6 has a base end that is rotatably mounted on the front end of the boom 5 about a horizontal axis, and a front end opposite to the base end. The bucket 7 is rotatably attached to the tip of the arm 6.

  The hydraulic excavator 1 has a boom cylinder, an arm cylinder, and a bucket cylinder provided for each of the boom 5, the arm 6, and the bucket 7. The boom cylinder is interposed between the vehicle body 3 and the boom 5, and extends and contracts so as to cause the boom 5 to perform an up-and-down operation. The arm cylinder is interposed between the boom 5 and the arm 6, and expands and contracts so as to cause the arm 6 to perform a rotating operation. The bucket cylinder is interposed between the arm 6 and the bucket 7, and expands and contracts so as to cause the bucket 7 to perform a rotating operation.

  The blade 4 mounted on the traveling device 2 or the vehicle body 3 is provided for performing operations such as excavation of the ground, leveling, and transportation of earth and sand. Specifically, the blade 4 is supported by a lift frame 4a, and the lift frame 4a is supported rotatably about the horizontal axis 4b with respect to the traveling device 2. Therefore, the blade 4 can be displaced vertically with respect to the traveling device 2.

  The excavator 1 has a lift cylinder 8 provided for the blade 4. The lift cylinder 8 has a head-side chamber 8h and a rod-side chamber 8r (see FIG. 1). When hydraulic oil is supplied to the head-side chamber 8h, the lift cylinder 8 extends to move the blade 4 in a lowering direction and to move the rod-side chamber 8r. While the hydraulic oil in the inside is discharged, the hydraulic oil is supplied to the rod side chamber 8r to contract and move the blade 4 in the upward direction, and to discharge the hydraulic oil in the head side chamber 8h.

  The hydraulic excavator 1 has a hydraulic circuit (not shown). The hydraulic circuit includes the boom cylinder, the arm cylinder, the bucket cylinder, and the lift cylinder 8. The hydraulic circuit further includes a hydraulic pump 9 (see FIG. 1), a lift cylinder control proportional valve 41 (see FIG. 2), and a lift cylinder flow control valve (not shown).

[Blade control unit]
FIG. 2 is a block diagram illustrating main functions of the blade control device 100. The blade control device 100 is provided to control the elevating operation of the blade 4. The blade control device 100 includes a controller 10 (mechatronic controller), a position information acquisition unit, a blade load acquisition unit 34, an automatic control switch 35, and a traveling lever 36. The controller 10 includes, for example, a microcomputer and controls the operation of each element included in the hydraulic circuit.

  The position information acquisition unit has a function of acquiring position information on the excavator 1. Specifically, in the present embodiment, the position information acquisition unit includes a vehicle body position acquisition unit 31, a vehicle body angle acquisition unit 32, and a blade angle acquisition unit 33. The vehicle body position acquisition unit 31 has a function of acquiring a vehicle body position that is the position of the machine body. The vehicle body position acquisition unit 31 is configured by, for example, a GNSS (Global Navigation Satellite System) receiver (GNSS sensor), and receives GNSS data indicating the position of the machine body. The vehicle body angle acquisition unit 32 has a function of acquiring the angle of the machine body. The vehicle body angle acquisition unit 32 is configured by a vehicle body angle sensor that detects the angle of the machine body in the global coordinate system (in the present embodiment, the angle of the vehicle body 3). The blade angle acquisition unit 33 has a function of acquiring the angle of the blade 4. The blade angle acquisition unit 33 is configured by a blade angle sensor that detects the angle of the blade 4 in the global coordinate system.

  As shown in FIG. 1, the vehicle body position obtaining unit 31 and the vehicle body angle obtaining unit 32 are mounted on the upper part of the vehicle body 3, and the blade angle obtaining unit 33 is mounted on the upper part of the blade 4. The embodiment is not limited to the specific example shown in FIG. Detection signals, which are electric signals generated by the acquisition units 31, 32, and 33, are input to the controller 10.

  In the present embodiment, the blade load obtaining unit 34 has a function of obtaining a blade load that is a load applied to the blade 4 during excavation work. The blade load corresponds to, for example, the pump pressure of the hydraulic pump 9 that drives the blade 4. Therefore, the blade load acquisition unit 34 can detect the blade load by detecting the pump pressure. In the present embodiment, the blade load acquisition unit 34 includes a head pressure sensor 34H that detects a head pressure P1 that is a pressure of hydraulic oil in the head-side chamber 8h of the lift cylinder 8, and a hydraulic pressure in the rod-side chamber 8r of the lift cylinder 8. And a rod pressure sensor 34R for detecting a rod pressure P2 as a pressure. Each of the sensors 34H and 34R converts the detected physical quantity into a detection signal, which is an electric signal corresponding to the detected physical quantity, and inputs the detection signal to the controller 10.

  The automatic control switch 35 is arranged in the cab and is electrically connected to the controller 10. The automatic control switch 35 receives an operation for switching the control mode of the controller 10 from the manual operation mode to the automatic control mode, and inputs a mode command signal relating to the operation to the controller 10. The controller 10 is switched from the manual operation mode to the automatic control mode by a mode command signal input from the automatic control switch 35.

  In the automatic control mode, the controller 10 is configured to automatically control the operation of the lift cylinder 8 so that the construction surface constructed by the blade 4 approaches a preset target design surface. When a command value (command current) to the lift cylinder control proportional valve 41 for controlling the operation of the lift cylinder 8 is output from the controller 10, the secondary pressure of the proportional valve 41 is increased according to the command value. The opening degree of the lift cylinder flow control valve changes according to the secondary pressure. As a result, the supply flow rate and the supply direction of the hydraulic oil supplied from the hydraulic pump 9 to the lift cylinder 8 change, and the operation speed and the drive direction of the lift cylinder 8 are controlled.

  The controller 10 includes a target design surface setting unit 11, a blade position calculation unit 12, a storage unit 13, a target position setting unit 14, a blade operation control unit 15, as functions for executing the automatic control. It has a load threshold setting unit 16, a position gain setting unit 17, a load gain setting unit 18, and a distance calculation unit 19.

  The target design surface setting unit 11 sets a target design surface (see FIG. 10) for specifying a target shape of an excavation target by the blade 4. The target design surface setting unit 11 stores the design surface input by the target design surface input unit provided in the cab, and inputs the design surface to the target position setting unit 14 as a target design surface. This target design surface is a surface that is a target shape of the ground to be excavated and specifies a three-dimensional design terrain. The target design surface may be specified by external data such as CIM, or may be set based on the position of the aircraft.

  The blade position calculation unit 12 calculates a blade position x, which is the position of the blade 4 in a global coordinate system, based on the position information acquired by the position information acquisition unit. In the present embodiment, the blade position calculating unit 12 obtains the vehicle body position obtained by the vehicle body position obtaining unit 31, the angle of the machine body obtained by the vehicle body angle obtaining unit 32, and the blade position obtaining unit 33. The blade position x is calculated based on the angle of the blade 4. That is, the blade position x is calculated from the sum of a vector from the reference point to the vehicle body position and a vector from the vehicle body position to the blade position. As described above, in the present embodiment, the blade position x is calculated based on the relative angle between the angle of the machine body and the angle of the blade 4 in the global coordinate system, but the method of calculating the blade position x is not limited to this. The blade position x may be calculated based on, for example, the length of the lift cylinder 8, or a GNSS receiver (GNSS sensor) may be attached to the blade 4 and calculated based on GNSS data received by the GNSS sensor. .

  In the present embodiment, the blade position x is set at the cutting edge position, which is the tip of the blade 4 (the position of the lower edge of the tip of the blade 4), but may be set at another part of the blade 4. .

  The storage unit 13 stores a first load threshold f1 which is a threshold of the blade load f and a second load threshold f2 which is a threshold of the blade load f and is larger than the first load threshold f1. The first load threshold f1 is set to a value corresponding to an appropriate blade load f at which the excavator 1 can run stably. The second load threshold value f2 is a value set in order to prevent the occurrence of a situation in which the blade load f becomes excessive and a stack or the like occurs. That is, the second load threshold f2 is a value set to realize a stable and efficient excavation operation. These load thresholds f1 and f2 may be manually input to the controller 10 by the operator before the excavation work, or may be appropriately calculated and stored by the controller 10 during the excavation work.

  The storage unit 13 stores a preset update condition. The update condition is a condition that is set in advance by associating the blade load f with the first load threshold, and is a criterion for determining whether or not the target position setting unit 14 updates the blade target position xref. It becomes. The update condition includes the condition that the blade load f approaches the first load threshold value f1 and these deviations become sufficiently small. In the present embodiment, the update condition is a condition that the blade load f reaches the first load threshold value f1 or the second condition in order to determine that the blade load f approaches the first load threshold value f1. It includes a condition that the blade load f reaches a determination value set based on one load threshold f1. The determination value is a value that can determine that the deviation (f−f1) obtained by subtracting the first load threshold value f1 from the blade load f has become sufficiently small. The determination value is a threshold value set in advance through a simulation, an experiment, or the like.

  The storage unit 13 stores a target trajectory (see FIG. 6 described later). The target trajectory is a target of an increasing process of the blade load f when the blade load f approaches the first load threshold f1 while increasing. The target trajectory is set such that the blade load f follows a preferred increase process up to the first load threshold f1 when the blade target position xref is not set at the start of the excavation operation in which the automatic control mode is selected. This is set in advance to control the elevating operation of the blade 4.

  The target position setting unit 14 sets a blade target position xref which is a target position of the blade position x and a position above the target design plane. The target position setting unit 14 sets the blade target position xref based on, for example, the blade load f and the blade position x.

  The load threshold setting unit 16 sets the first load threshold f1. The position gain setting unit 17 sets the position gain kx. The load gain setting unit 18 sets the load gain kf. The details of the load threshold setting unit 16, the position gain setting unit 17, and the load gain setting unit 18 will be described later.

  The blade operation control unit 15 calculates and outputs a command value to the lift cylinder control proportional valve 41 for controlling the operation of the lift cylinder 8. Specifically, it is as follows.

  FIG. 3 is a graph showing the relationship between the blade position x, the blade target position xref, and the raising / lowering operation of the blade 4 in the blade control device 100. The blade operation control unit 15 is for raising and lowering the blade 4 so that a position deviation Δx, which is a deviation between the blade position x calculated by the blade position calculation unit 12 and the blade target position xref, approaches zero. The command (command value) is calculated and output.

  The control of the blade position x is feedback control that changes the control amount according to the magnitude of the position deviation Δx, which is the deviation between the blade position x and the blade target position xref. Specifically, the blade operation control unit 15 includes, as a variable, a position deviation Δx which is a height difference between the blade position x and the blade target position xref, and a term including a position gain kx by which the position deviation Δx is multiplied. The command is calculated and output based on the function of the command. In FIG. 3, the blade target position xref is located at a position corresponding to the origin on the horizontal axis of the graph, and is provided with a hysteresis for suppressing hunting. That is, when the blade position x is included in a predetermined range based on the blade target position xref (for example, a range of the blade target position xref ± α as shown in FIG. 3), the blade operation control unit 15 Does not control the position x.

  FIG. 4 is a graph showing the relationship among the blade load f, the first load threshold f1, the second load threshold f2, and the lifting / lowering operation of the blade 4 in the blade control device 100. As shown in FIG. 4, when the blade load f acquired by the blade load acquisition unit 34 is larger than the second load threshold f2, the blade operation control unit 15 raises the blade 4. The command (command value) is calculated and output. Specifically, the blade operation control unit 15 includes, as a variable, a load deviation Δf which is a deviation (f−f2) obtained by subtracting the second load threshold f2 from the blade load f, for example. The command is calculated and output based on a function having a term including the load gain kf multiplied by the deviation Δf.

  In this embodiment, priority is given to the position control of the blade 4 as shown in FIG. On the other hand, when the blade load f becomes larger than the second load threshold value f2, the blade position is controlled so that the blade 4 moves up quickly. By performing such position control priority control, stable and efficient excavation work can be performed while suppressing the undulation of the construction surface.

  Next, a control operation performed by the controller 10 for driving the blade 4 in the automatic control mode will be described with reference to a flowchart of FIG.

  The controller 10 determines whether or not the automatic control switch 35 is turned on, that is, whether or not the automatic control mode is selected (Step S1). If the automatic control mode is not selected (NO in step S1), the controller 10 ends the process without performing the control in the automatic control mode.

  When the automatic control mode is selected (YES in step S1), the controller 10 captures a signal input to the controller 10, specifically, a detection signal or a designation signal of each sensor (step S2). . The designation signal includes a signal about a target design surface designated by an operation of an input unit of the target design surface by the operator, a signal about a blade load f acquired by the blade load acquisition unit 34, and a signal about the vehicle body position acquisition unit 31. The signal about the acquired vehicle body position, the signal about the angle of the machine main body acquired by the vehicle body angle acquisition unit 32, the signal about the angle of the blade 4 acquired by the blade angle acquisition unit 33, and the traveling lever 36 A signal about the traveling speed corresponding to the operation to be received is included. Based on these designation signals, the controller 10 acquires the initial state of the excavator 1. Further, the target design surface setting unit 11 of the controller 10 sets a target design surface based on the signal for the target design surface.

  Next, the controller 10 determines whether or not the blade target position xref has been set (Step S3). If the blade target position xref has not been set (NO in step S3), the blade operation control unit 15 causes the blade load f to approach the first load threshold f1 while following an increasing process close to the target trajectory. Then, a command for raising and lowering the blade 4 is output (step S4). Although the setting of the target trajectory is not essential in the blade control device of the present invention, the target trajectory is set as in the present embodiment, and the blade position x is controlled based on the target trajectory. There are advantages as follows. Specifically, it is as follows.

  FIG. 6 is a graph showing the target trajectory of the blade load f and the transition of the actual blade load f in the blade control device 100. In FIG. 6, a curve indicated by a dashed line is the target trajectory, and a curve indicated by a solid line is a change in the actual blade load f.

  If the target trajectory as shown in FIG. 6 is not set, and excavation work is started at a stage before the blade target position xref is set, the blade 4 may enter the ground at a large descent speed. In addition, when the blade load f reaches the first load threshold value f1, the depth of the blade 4 entering the ground tends to increase. In such a case, the change in the amount of soil on the blade 4 with respect to the traveling distance of the excavator 1 is large, and the fluctuation of the blade load f may be large.

  On the other hand, when the target trajectory shown in FIG. 6 is set as in the present embodiment, even before the blade target position xref is set, the blade load f follows an increasing process close to the target trajectory. While approaching the first load threshold f1, the blade 4 enters the ground at an appropriate descent speed, and the blade 4 enters the ground at a depth when the blade load f reaches the first load threshold f1. The increase can be suppressed. Thus, the change in the amount of soil on the blade 4 with respect to the travel distance of the excavator 1 is small, and the fluctuation of the blade load f is also small. As a result, the effect of suppressing undulation on the construction surface can be further enhanced.

  In the present embodiment, when the condition that the blade load f approaches the first load threshold value f1 while following the increasing process close to the target trajectory and the load deviation, which is the deviation thereof, is sufficiently small is satisfied. The target position setting section 14 sets the blade target position xref. In the present embodiment, the condition is that the blade load f reaches the first load threshold value f1, and more specifically, the load deviation, which is the deviation (f−f1), changes from a negative value to a positive value. Condition. In the present embodiment, the blade target position xref set by the target position setting unit 14 is set to a position on a plane parallel to the target design plane, passing through the blade position x when the condition is satisfied. You. After the target blade position xref is set, the blade operation control unit 15 controls the raising / lowering operation of the blade 4 so that the positional deviation Δx between the blade position x and the target blade position xref approaches zero.

  Next, the controller 10 compares the blade load f obtained by the blade load obtaining unit 34 with a flag threshold value which is a preset threshold value (Step S5). In the present embodiment, the flag threshold is the same as the second load threshold f2, but is not limited thereto, and may be different from the second load threshold f2. However, the flag threshold is set to a value larger than the first load threshold f1.

  When the blade load f is larger than the second load threshold f2 (flag threshold) (f> f2, NO in step S5), the storage unit 13 indicates that the update of the blade target position xref is permitted. The first state (update flag = 1) is stored (step S6). On the other hand, when the blade load f is equal to or less than the second load threshold f2 (flag threshold) (f ≦ f2, YES in step S5), the storage of the update flag is not changed.

  Next, the controller 10 sets a condition (update condition) including that the first state is stored in the storage unit 13 (update flag = 1) and that the blade load f reaches the first load threshold f1. It is determined whether or not the condition is satisfied (step S7). Specifically, in the present embodiment, the controller 10 determines that the first condition is that the first state is stored in the storage unit 13 (update flag = 1), and that the controller 10 has acquired the first condition this time. The second condition that the blade load f is larger than the first load threshold f1 (f> f1), and that the blade load f previously obtained by the blade load obtaining unit 34 is smaller than the first load threshold f1 (f It is determined whether or not an update condition including the third condition of <f1) is satisfied (step S7).

  When the update condition is satisfied (YES in step S7), the target position setting unit 14 updates the blade target position xref (step S8). In the present embodiment, the blade target position xref updated by the target position setting unit 14 is set to a position on a plane that passes through the blade position x and is parallel to the target design plane when the update condition is satisfied. Is done. When the blade target position xref is updated, the storage unit 13 stores a second state (update flag = 0) indicating that the update of the blade target position xref is not permitted, in place of the first state (step). S8).

  The processing of steps S5 to S8 will be described more specifically with reference to FIG. FIG. 7 is an example of a time chart for describing the blade target position xref updated in the blade control device 100 based on the blade load f.

  At times t1 and t2 shown in FIG. 7, the second condition and the third condition among the update conditions are satisfied. However, at times t1 and t2, the storage unit 13 stores the second state (update flag = 0) indicating that the update of the blade target position xref is not allowed. The condition has not been met. Therefore, at times t1 and t2, the update condition is not satisfied (NO in step S7), so that the target position setting unit 14 does not update the blade target position xref.

  On the other hand, at time t3 shown in FIG. 7, the blade load f becomes larger than the second load threshold f2 (flag threshold), and the storage unit 13 stores the first state (update flag = 1) (step S3). S6) At time t4, all of the update conditions are satisfied (YES in step S7). Therefore, at time t4, the target position setting unit 14 updates the blade target position xref.

  The update of the blade target position xref is not limited to the mode shown in FIG. FIG. 8 is another example of a time chart for explaining the blade target position xref updated based on the blade load f. In the mode illustrated in FIG. 8, the update condition does not include the first condition, but includes the second condition and the third condition among the first condition, the second condition, and the third condition. In the mode shown in FIG. 7, the target position setting unit 14 updates the blade target position xref at times when the update condition is satisfied, that is, at times t1, t2, and t4 when the second condition and the third condition are satisfied. I do.

  In the mode shown in FIG. 7, while the update of the blade target position xref is permitted when the update flag of the blade target position xref is in the first state (update flag = 1), the update flag is set in the second state (update). When the flag is at (0), the update of the blade target position xref is not allowed, so that the frequent update of the blade target position xref can be suppressed.

  Next, the blade operation control unit 15 calculates a command value to the lift cylinder control proportional valve 41 for controlling the operation of the lift cylinder 8 (Step S9). The blade operation control unit 15 determines whether the command value is equal to or less than a preset upper limit value (Step S10). If the command value is equal to or less than the preset upper limit value (YES in step S10), blade operation control section 15 outputs the command value, and the output command value is output to proportional valve 41 (FIG. 2). ), And the control is applied (step S12). On the other hand, if the command value is larger than the preset upper limit value (NO in step S10), the blade operation control unit 15 sets the value cut off to the upper limit value as a command value (step S11). The command value that has been cut off is output, and the output command value is input to the proportional valve 41 (see FIG. 2), and the control is applied (step S12).

  In the present embodiment, the command value calculated by the blade operation control unit 15 in step S9 is calculated based on, for example, a function represented by the following equation (1).

Command value = kx (Δx) × Δx + kf (Δf) × Δf (1)
The function represented by the above equation (1) includes a position deviation Δx which is a height difference between the blade position x and the blade target position xref as a variable, and includes a position gain kx multiplied by the position deviation Δx. And a term including a load deviation Δf, which is a deviation (f−f2) obtained by subtracting the second load threshold f2 from the blade load f, as a variable, and including a load gain kf by which the load deviation is multiplied.

  FIG. 9 is a schematic diagram for explaining updating the first load threshold value f1 based on the distance between the vehicle body position of the machine main body and the target design surface in the blade control device 100. FIG. It is a graph for explanation.

  As shown in FIGS. 9 and 10, the load threshold setting unit 16 determines that the main body distance Z, which is the distance between the vehicle body position acquired by the vehicle body position acquisition unit 31 and the target design plane, is a first distance Z1. When the main body distance Z is the second distance Z2 smaller than the first distance Z1, the first load threshold f1 is updated so that the first load threshold f1 is smaller than when there is a certain distance. Is configured. The distance calculation unit 19 calculates the main body distance Z based on the target design surface and the vehicle body position.

  In this embodiment, when the main body distance Z is the second distance Z2 (that is, when the machine main body is close to the target design surface), the main body distance Z is equal to the first distance Z1. The blade load f is more likely to reach the first load threshold f1 than in a certain case (that is, when the machine body is far from the target design surface). This is because the distance ΔZ2 between the vehicle body position and the blade target position xref in the former case is smaller than the distance ΔZ1 between the vehicle body position and the blade target position xref in the latter case. This increases the frequency of updating the blade target position xref, and increases the possibility that the blade target position xref is set to a more appropriate position corresponding to the state of the ground to be excavated.

  The following are specific examples of this embodiment. For example, the first load threshold f1 when the ground leveling operation is performed in the final stage of the operation by the excavator 1 is larger than the first load threshold f1 when the excavation operation is performed in the initial stage or the intermediate stage of the operation. Set to a small value. In such a case, the same control algorithm can be used for both the excavation operation where quick excavation work is more important than the leveling operation and the leveling operation where emphasis is placed on the accuracy of bringing the construction surface closer to the target design surface. become.

  In the present embodiment, as shown in FIG. 10, the load threshold value setting unit 16 sets the load threshold value in a part of the entire range of the main body distance Z including the first distance Z1 and the second distance Z2. The first load threshold f1 is updated so that the first load threshold f1 decreases as the body distance Z decreases. Then, the load threshold setting unit 16 does not update the first load threshold f1 in a range where the body distance Z is larger than the partial range and in a range where the body distance Z is smaller than the partial range. However, the update of the first load threshold f1 is not limited to the specific example shown in FIG.

  FIG. 11 is a graph for explaining that the blade control device 100 updates the position gain kx based on the position deviation Δx which is the deviation (x−xref) between the blade position x and the blade target position xref. .

  As shown in FIG. 11, when the blade position x is lower than the blade target position xref, the position gain setting unit 17 sets the position gain Δ such that the rising speed of the blade 4 is increased based on the position deviation Δx. Update the position gain kx. In this aspect, when the blade position x is below the blade target position xref, the rising speed of the blade 4 is increased, so that the ground to be excavated is prevented from being excavated below the blade target position xref. As a result, the effect of suppressing the ground from being excavated below the target design surface is further increased.

  When the blade load f is larger than the second load threshold f2 (YES in step S5), the blade operation control unit 15 outputs a command value for raising the blade 4. FIG. 12 is a graph for explaining that the blade controller 100 updates the load gain kf based on the deviation Δf between the blade load f and the second load threshold f2.

  As shown in FIG. 12, when the blade load f is larger than the second load threshold f2, the load gain setting unit 18 controls the load so that the rising speed of the blade 4 is increased based on the load deviation Δf. Update the gain kf. As a result, when the blade load f is larger than the second load threshold f2, the rising speed of the blade 4 is increased, so that the blade load f is reduced more quickly, a stack or the like due to an excessive load is prevented, and the hydraulic excavator is prevented. 1, the effect of enabling stable running is further enhanced.

  According to the device described above, for example, as shown in FIG. 13, the undulating surface of the hydraulic shovel 1 including the blade control device 100 according to the present embodiment has an undulation as compared with the conventional hydraulic shovel 1. Effectively suppressed.

  The present invention is not limited to the embodiment described above. The present invention includes the following embodiments, for example.

  The work machine to which the blade control device according to the present invention is applied is not limited to a hydraulic shovel. The present invention can be widely applied to other work machines including a blade, such as a wheel loader, a bulldozer, and a grader.

1 Hydraulic excavator (an example of a working machine)
2 Traveling device (part of machine body)
3 Body (part of machine body)
Reference Signs List 4 blade 8 lift cylinder 10 controller 11 target design surface setting unit 12 blade position calculation unit 13 storage unit 14 target position setting unit 15 blade operation control unit 16 load threshold setting unit 17 position gain setting unit 18 load gain setting unit 31 body position acquisition Unit 32 body angle obtaining unit 33 blade angle obtaining unit 34 blade load obtaining unit 100 blade control device f blade load f1 first load threshold f2 second load threshold kf load gain kx position gain x blade position xref blade target position Δf Load deviation from second load threshold Δx Position deviation between blade position and blade target position Z Body distance which is the distance between vehicle body position and target design surface Z1, Z2 First distance, second distance

Claims (8)

A blade control device provided in a work machine including a machine main body and a blade that is attached to the machine main body so as to be able to move up and down, and controls a raising and lowering operation of the blade.
A target design surface setting unit that sets a target design surface that specifies a target shape of the excavation target by the blade,
A position information acquisition unit that acquires position information about the work machine,
A blade position calculation unit that calculates a blade position that is a position of the blade based on the position information acquired by the position information acquisition unit,
A blade load acquisition unit that acquires a blade load that is a load applied to the blade,
A storage unit that stores a first load threshold value that is a threshold value of the blade load and a second load threshold value that is a threshold value of the blade load and is larger than the first load threshold value;
A target position setting unit that sets a blade target position that is a target position of the blade position and is a position above the target design surface.
When the blade load acquired by the blade load acquisition unit is equal to or less than the second load threshold, a position deviation, which is a deviation between the blade position calculated by the blade position calculation unit and the blade target position, is zero. Output a command for raising and lowering the blade so as to approach the, if the blade load acquired by the blade load acquisition unit is greater than the second load threshold, a command to raise the blade Output blade operation control unit,
The target position setting unit, when an update condition set in advance by associating the blade load and the first load threshold is satisfied, based on the blade position when the update condition is satisfied, A blade controller that updates the blade target position.   The update condition is set based on the first load threshold to determine whether the blade load reaches the first load threshold or to determine that the blade load has approached the first load threshold. The blade control device according to claim 1, further comprising a condition that the blade load reaches a determination value. The storage unit stores a first state indicating that the update of the blade target position is permitted when the blade load becomes larger than a flag threshold that is a preset threshold, while the blade target position is updated. Then, a second state indicating that the update of the blade target position is not permitted is stored instead of the first state,
The update condition is a condition that the blade load reaches the first load threshold when the first state is stored in the storage unit, or the first state is stored in the storage unit. The method according to claim 1, further comprising a condition that the blade load reaches a determination value set based on the first load threshold to determine that the blade load has approached the first load threshold. A blade controller as described.   The said blade target position updated by the said target position setting part is set to the position on the plane parallel to the said target design surface through the said blade position when the said update condition is satisfy | filled. The blade control device according to any one of claims 1 to 4. The storage unit stores a target trajectory that is a target of the blade load increasing process when the blade load approaches the first load threshold while increasing.
Before the blade target position is set by the target position setting unit, the blade operation control unit controls the blade load so that the blade load approaches the first load threshold while following an increasing process close to the target trajectory. The blade control device according to any one of claims 1 to 4, which outputs a command for raising and lowering the blade. A load threshold setting unit that sets the first load threshold;
The position information acquisition unit includes a vehicle body position acquisition unit that acquires a vehicle body position that is the position of the machine body,
The load threshold setting unit is configured such that the main body distance is greater than the first distance than when the main body distance that is a distance between the vehicle body position acquired by the vehicle body position acquisition unit and the target design surface is a first distance. The blade control device according to any one of claims 1 to 5, wherein the first load threshold is updated so that the first load threshold becomes smaller when the second distance is smaller than the first load threshold. The blade operation control unit outputs the command based on a function including a term including a position gain that is a variable including a position deviation that is a height difference between the blade position and the blade target position, and multiplying the position deviation,
The blade controller further includes a position gain setting unit that sets the position gain,
The position gain setting unit according to claim 1, wherein when the blade position is below the blade target position, the position gain is updated such that a rising speed of the blade is increased based on the position deviation. The blade control device according to claim 1. The function further includes a term including a load gain that is multiplied by the load deviation while including, as a variable, a load deviation that is a deviation obtained by subtracting the second load threshold from the blade load,
The blade control device further includes a load gain setting unit that sets the load gain,
The blade control according to claim 7, wherein the load gain setting unit updates the load gain so as to increase a rising speed of the blade based on the load deviation when the blade load is larger than the second load threshold. apparatus.

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