JP2020033788A - Blade control device of work machine - Google Patents

Abstract

To provide a blade control device that allows for selection of control appropriate for an actual excavation condition.SOLUTION: A blade operation control part 15 of a blade control device 100 controls an operation of a blade 4 so that the blade 4 descends and a positional deviation ΔZ comes close to zero when a blade load f is a first load threshold f1 or below and when the positional deviation ΔZ is a position threshold Z1 or above. The blade operation control part 15 controls the operation of the blade 4 so that the blade 4 ascends regardless of the positional deviation ΔZ when the blade load f is a second load threshold f2 or above.SELECTED DRAWING: Figure 4

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. In such a working machine, the operator performs the operation of moving the blade up and down together with the traveling operation, so that the blade position (the height of the blade edge) is adjusted, and ground excavation and leveling are performed.

  Patent Literature 1 discloses a blade control system that automatically controls the blade position. The blade control system described in Patent Literature 1 executes excavation control when the distance determination unit determines that the distance between the design surface and the blade edge is greater than the first distance, and performs the excavation control on the design surface and the blade. When the distance determination unit determines that the distance to the blade edge is smaller than the second distance, the controller performs leveling control, and the distance between the design surface and the blade edge is equal to or less than the first distance and equal to or more than the second distance. When the distance is determined by the distance determination unit, excavation control or terrain control is performed. In Patent Literature 1, the excavation control is control for maintaining a blade load at a target load in order to perform efficient excavation work. The terrain control is a control for maintaining the distance between the blade tip and the design surface at a target distance in order to make the terrain a target shape.

Japanese Patent No. 5247939

  However, the blade control system of Patent Literature 1 has a problem in that it is not possible to select a control suitable for an actual excavation situation, that is, to select from the excavation control and the leveling control. For example, if the distance between the design surface and the blade edge is smaller than the second distance, even if the blade load is large, be sure to perform the terrain control, that is, set the distance between the blade edge and the design surface to the target distance. , The blade load becomes excessive depending on the condition of the ground to be excavated (for example, the hardness of the earth and sand, the type of earth and sand, etc.). As a result, the working machine may be stuck. On the other hand, when the distance between the design surface and the blade edge is greater than the first distance, even if the blade load is small and control (leveling control) for adjusting the blade edge to the design surface is possible, leveling is performed. Since the excavation control is performed without performing the control, high construction efficiency cannot be obtained.

  An object of the present invention is to provide a blade control device provided in a work machine provided with a blade and capable of selecting a control suitable for an actual excavation situation.

  A blade control device according to the present invention is provided on a work machine including a machine body and a blade that is attached to the machine body so as to be able to move up and down, and is a device for controlling the up and down operation of the blade. The blade control device, a target design surface setting unit that sets a target design surface that specifies a target shape of an excavation target by the blade, a position information acquisition unit that acquires position information about the work machine, and the position information acquisition unit A blade position calculation unit that calculates a blade position that is the position of the blade based on the position information obtained by a deviation calculation unit that calculates a position deviation that is a deviation between the blade position and the target design surface. A blade load obtaining unit that obtains a blade load that is a load applied to the blade, a first load threshold that is a threshold of the blade load, and a second load threshold that is a threshold of the blade load and is larger than the first load threshold. And a storage unit that stores a position threshold value that is a threshold value of the position deviation, and a blade operation control unit that controls the operation of the blade. The blade operation control unit is configured such that, when the blade load is equal to or less than the first load threshold, and the position deviation is equal to or greater than the position threshold, the blade descends and the position deviation approaches zero. Controlling the operation of the blade, the blade operation control unit, when the blade load is greater than or equal to the second load threshold, regardless of the position deviation, controls the operation of the blade so that the blade rises I do.

  In the blade control device of the present invention, since the above-described control is performed, it is possible to select a control suitable for an actual excavation condition. Specifically, it is as follows. In this blade control device, control is performed to bring the blade position closer to the target design surface when the blade load is a small value equal to or smaller than the first load threshold even if the position deviation is equal to or larger than the position threshold. This makes it possible to quickly bring the construction surface with the blade closer to the target design surface, thereby improving construction efficiency. Further, in the blade control device of the present invention, when the blade load is a large value equal to or larger than the second load threshold, control is performed to raise the blade regardless of the position deviation even if the position deviation is small. This suppresses the blade load from becoming excessive regardless of the state of the ground to be excavated, and prevents the working machine from being stuck.

  In the blade control device, when the blade load is larger than the first load threshold and smaller than the second load threshold, and the position deviation is equal to or more than the position threshold, the blade with respect to the machine main body. Is preferably maintained.

  In this aspect, since an increase in the blade load is suppressed, the occurrence of undulation on the construction surface is suppressed. Specifically, it is as follows. In this aspect, the intermediate load region in which the blade load is larger than the first load threshold and smaller than the second load threshold is a region where an appropriate load is applied to the blade. When the position deviation is equal to or greater than the position threshold (first position threshold), specifically, when the deviation between the blade position and the target design surface is large, when control is performed to make the position deviation close to zero, There is a high possibility that the blade load will increase from the moderate load to the second load threshold or more due to the blade penetrating too deeply into the ground. When the blade load is equal to or greater than the second load threshold, control is performed to raise the blade regardless of the position deviation. The elevation of the blade position in this way causes the construction surface to undulate (undulate). Therefore, in the present aspect, when the position deviation is equal to or larger than the position threshold (first position threshold) in the intermediate load region in an appropriate load state, the blade operation control unit sets the relative position of the blade to the machine body. The relative position is maintained without performing control to change the position. This suppresses an increase in blade load and suppresses undulation on the construction surface.

  In the blade control device, the blade operation control unit, when the blade load is larger than the first load threshold and smaller than the second load threshold, and, when the position deviation is smaller than the position threshold, The operation of the blade may be controlled so that the position deviation approaches zero.

  In this aspect, in the intermediate load region, when the position deviation is smaller than the position threshold (first position threshold), the blade operation control unit performs control to bring the blade position closer to the target design surface. This improves construction efficiency. Specifically, it is as follows. If the position deviation is smaller than the position threshold value (first position threshold value), specifically, if the deviation between the blade position and the target design surface is small, it is assumed that control has been performed to bring the position deviation closer to zero. Also, since the blade position is close to the target design surface, there is a low possibility that the blade enters the ground too deeply and the blade load increases beyond the second load threshold. Therefore, in this aspect, in such a case, the blade operation control unit performs control to bring the blade position closer to the target design surface. This makes it possible to quickly bring the construction surface with the blade closer to the target design surface, thereby improving construction efficiency.

  In the blade control device, the position threshold is a first position threshold, and the storage unit further stores a second position threshold that is a threshold of the position deviation and is smaller than the first position threshold. The control unit is configured such that, when the blade load is equal to or less than the first load threshold, and the position deviation is equal to or less than the second position threshold, the blade moves up so that the position deviation approaches zero. The operation of the blade may be controlled.

  In this aspect, when the position deviation is equal to or less than the second position threshold, control is performed to raise the blade, so that excessive digging due to the blade falling below the target design surface can be suppressed.

  As described above, according to the present invention, a blade control device capable of selecting control suitable for an actual excavation situation is provided.

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 a blade control device according to the embodiment. It is a schematic diagram for explaining the relation between a target design surface, a current condition surface, and a position deviation. 5 is a flowchart illustrating an example of a control operation executed by a controller included in the blade control device according to the embodiment. 6 is a graph illustrating an example of control of blade operation based on a position deviation that is a deviation between the blade position and the target design surface in the blade control device according to the embodiment. 9 is a graph illustrating another example of the control of the operation of the blade based on a position deviation that is a deviation between the blade position and the target design surface in the blade control device according to the embodiment. 9 is a graph showing still another example of the control of the operation of the blade based on a position deviation that is a deviation between the blade position and the target design surface in the blade control device according to the embodiment. 6 is a graph illustrating an example of control of blade operation based on a blade load in the blade control device according to the embodiment.

  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 (dozer) mounted on the traveling device 2 or the vehicle body 3. The traveling device 2 and the vehicle body 3 constitute a 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 for operating the blade 4. 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 vehicle body position, which is the position of the vehicle body 3. The vehicle body angle obtaining unit 32 has a function of obtaining a vehicle body angle which is an angle of the vehicle body 3. The vehicle body angle acquisition unit 32 is configured by a vehicle body angle sensor that detects the angle of the vehicle body 3 in the global coordinate system. 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. On the other hand, in the manual operation mode, when the operator operates the travel lever 36, an operation signal is input to the controller 10, and a command value to the lift cylinder control proportional valve 41 is output from the controller 10.

  The controller 10 includes, as functions for executing the automatic control, a target design surface setting unit 11, a blade position calculation unit 12, a storage unit 13, a deviation calculation unit 14, a blade operation control unit 15, A setting unit 16.

  The target design surface setting unit 11 sets a target design surface that specifies a target shape to be excavated by the blade 4. The target design surface setting unit 11 stores a design surface input by a target design surface input unit provided in the cab. 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 calculator 12 calculates a blade position, which is the position of the blade 4 in a global coordinate system, based on the position information acquired by the position information acquirer. In the present embodiment, the blade position calculation unit 12 includes the vehicle body position acquired by the vehicle body position acquisition unit 31, the vehicle body angle acquired by the vehicle body angle acquisition unit 32, and the blade position acquired by the blade angle acquisition unit 33. The blade position is calculated based on the angle of the blade 4. That is, the blade position 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 is calculated based on the relative angle between the vehicle body angle and the angle of the blade 4 in the global coordinate system, but the method of calculating the blade position is not limited to this. The blade position 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.

  The deviation calculator 14 calculates a position deviation ΔZ, which is a deviation between the blade position and the target design surface SD.

  FIG. 3 is a schematic diagram for explaining the relationship between the target design plane SD, the current plane SP, and the positional deviation ΔZ. In FIG. 3, the excavator 1 (work machine) is shown in a simplified manner. In the present embodiment, as shown in FIG. 3, the blade position is set at the blade edge position (the lower edge position of the blade 4), which is the tip of the blade 4, but is set at another position of the blade 4. It may be set. The position deviation ΔZ is a deviation between the blade position and the target design surface SD. That is, the positional deviation ΔZ is obtained by subtracting the height of the target design surface SD from the blade position (the cutting edge height of the blade 4). The current plane SP shown in FIG. 3 is the ground to be excavated.

  The threshold value setting unit 16 sets a first load threshold value f1, a second load threshold value f2, a first position threshold value Z1, and a second position threshold value Z2 used for the calculation in the blade operation control unit 15. These thresholds may be manually input to the controller 10 by the operator before the excavation work, or may be appropriately calculated by the controller 10 during the excavation work.

  The storage unit 13 stores the first load threshold f1, the second load threshold f2, the first position threshold Z1, and the second position threshold Z2 set by the threshold setting unit 16.

  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 f2 is a value set to realize a stable and efficient excavation operation. The second load threshold value f2 prevents the occurrence of a situation in which the blade load f becomes excessive and a stack (a state in which the blade load f becomes excessive and the work machine becomes difficult to move forward) or the like occurs. It is the value set to perform. Therefore, the second load threshold f2 is set to a value larger than the first load threshold f1. It is preferable that the second load threshold f2 be set to a value smaller than the blade load f in which the above-described situation occurs. That is, the second load threshold f2 is preferably set to a value at which the work machine can travel even when the blade load f has reached the second load threshold f2.

  The first position threshold value Z1 is based on a criterion for determining whether or not to control the operation of the blade so that the blade 4 descends and the position deviation approaches zero when the blade load f is equal to or less than the first load threshold value f1. Value. When the blade load f is in the intermediate load region, that is, when the blade load f is larger than the first load threshold f1 and smaller than the second load threshold f2, the first position threshold Z1 is determined by the blade 4 with respect to the body of the aircraft. This is a value that serves as a reference for determining whether to maintain the relative position. The first position threshold value Z1 is set to, for example, zero or a positive value. The second position threshold value Z1 is a value that serves as a criterion for determining whether or not to control the operation of the blade 4 so as to raise the blade 4 so that the position deviation approaches zero when the blade load f is in the intermediate region. is there. Therefore, the second position threshold value Z2 is set to a value smaller than the first position threshold value Z1.

  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. The blade operation control unit 15 includes an automatic control switch operation signal of the automatic control switch 35, a traveling lever operation signal of the traveling lever 36, a blade load f acquired by the blade load acquiring unit 34, and a setting by the threshold setting unit 16. The respective threshold values stored in the storage unit 13 and the position deviation ΔZ calculated by the deviation calculation unit 14 are input, and a command current to be output to the lift cylinder control proportional valve 41 is calculated based on these.

  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.

  When the automatic control switch 35 (see FIG. 2) is turned on, the controller 10 performs an initial operation of the automatic control (Step S0). In the initial operation, the controller 10 captures a signal input to the controller 10, specifically, a detection signal or a designation signal of each sensor. 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 acquired signal about the vehicle body position, the signal about the vehicle body angle 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 operation received by the travel lever 36 For example, a signal about a corresponding traveling speed 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. Then, the blade operation control unit 15 of the controller 10 controls the operation of the blade 4 as described below.

  The blade operation control unit 15 determines whether the blade load f acquired by the blade load acquisition unit 34 is equal to or more than the second load threshold f2 (Step S1). If the blade load f is equal to or greater than the second load threshold f2 (YES in step S1), the blade operation control unit 15 controls the operation of the blade 4 so that the blade 4 moves up (step S2), and the controller 10 The process of step S1 is performed again.

  When the blade load f is smaller than the second load threshold f2 (NO in step S1), the blade operation control unit 15 determines whether the blade load f is equal to or less than the first load threshold f1 (step S3).

  If the blade load f is equal to or less than the first load threshold f1 (YES in step S3), the blade operation control unit 15 determines whether the position deviation ΔZ is equal to or greater than the first position threshold Z1 (step S4). .

  When the position deviation ΔZ is equal to or larger than the first position threshold value Z1 (YES in step S4), the blade operation control unit 15 performs leveling control (step S5). Specifically, the blade operation control unit 15 controls the operation of the blade 4 so that the blade 4 descends and the position deviation ΔZ approaches zero (Step S5), and the controller 10 performs the processing of Step S1. Do again.

  On the other hand, when the position deviation ΔZ is smaller than the first position threshold value Z1 (NO in step S4), the blade operation control unit 15 determines whether the position deviation ΔZ is equal to or smaller than the second position threshold value Z2 (step S4). S6).

  When the position deviation ΔZ is equal to or smaller than the second position threshold value Z2 (YES in step S6), the blade operation control unit 15 performs the leveling control. Specifically, the blade operation control unit 15 controls the operation of the blade 4 so that the blade 4 rises and the position deviation ΔZ approaches zero (Step S7), and the controller 10 performs the processing of Step S1. Do again.

  When the position deviation ΔZ is smaller than the first position threshold value Z1 (NO in step S4) and when the position deviation ΔZ is larger than the second position threshold value Z2 (NO in step S6), the blade operation control unit 15 The control for changing the relative position of the blade 4 with respect to the main body (control for raising or lowering the blade 4) is not performed, the relative position is maintained, and the controller 10 performs the process of step S1 again.

  When the blade load f is smaller than the second load threshold f2 (NO in step S1) and the blade load f is larger than the first load threshold f1 (NO in step S3), that is, when the blade load f is equal to the intermediate load. If it is in the area, the blade operation control unit 15 determines whether the position deviation ΔZ is equal to or greater than the first position threshold value Z1 (Step S8).

  When the position deviation ΔZ is equal to or greater than the first position threshold value Z1 (YES in step S8), the blade operation control unit 15 performs control to change the relative position of the blade 4 with respect to the body of the aircraft (moving the blade 4 up or down). The relative position is maintained without performing the operation control) (step S9). In other words, the blade operation control unit 15 does not output a command to the lift cylinder control proportional valve 41. That is, the previous lift value of the blade 4 with respect to the body of the aircraft is maintained. Thereafter, the controller 10 performs the process of step S1 again.

  On the other hand, when the position deviation ΔZ is smaller than the first position threshold value Z1 (NO in step S8), the blade operation control unit 15 performs the leveling control (step S10). Specifically, the blade operation control unit 15 controls the operation of the blade 4 so that the blade 4 descends or rises and the positional deviation ΔZ approaches zero (Step S10), and the controller 10 performs the processing of Step S1. Do again.

  The control by the blade control device 100 shown in the flowchart of FIG. 4 described above is summarized as follows. The controller 10 of the blade control device 100 executes a first control mode, a second control mode, and a third control mode. The first control mode performs leveling control, the second control mode performs blade elevation control (lift elevation control), and the third control mode includes blade retention control (lift retention control). ).

  The leveling control in the first control mode controls the operation of the blade 4 so that the position deviation ΔZ approaches zero. In other words, in the leveling control, the operation of the blade 4 is controlled such that the blade edge (the blade position) of the blade 4 substantially matches the target design surface. The first control mode is performed when the blade load f is equal to or less than the first load threshold f1. Specifically, in the present embodiment, the first control mode is performed when the blade load f is equal to or less than the first load threshold value f1 and the position deviation ΔZ is equal to or greater than the first position threshold value Z1 (step S1). S5). The first control mode is also performed when the blade load f is equal to or less than the first load threshold f1 and the position deviation ΔZ is equal to or less than the second position threshold Z2 (step S7). Further, the first control mode is also performed when the position deviation ΔZ is smaller than the first position threshold value Z1 in the intermediate load region (Step S10).

  In the second control mode, the operation of the blade 4 is controlled so that the blade 4 moves up. The second control mode is performed when the blade load f is equal to or more than the second load threshold f2 (Step S2).

  In the third control mode, the relative position of the blade 4 with respect to the body of the aircraft is maintained. The third control mode is performed when the position deviation ΔZ is equal to or larger than the first position threshold value Z1 in the intermediate load region (Step S9). In the present embodiment, the third control mode includes a case where the blade load f is equal to or less than the first load threshold f1 and the position deviation ΔZ is smaller than the first position threshold Z1 and larger than the second position threshold Z2 (step S1). (NO in S6).

  FIGS. 5, 6, and 7 are graphs respectively showing examples of the control of the operation of the blade 4 based on the positional deviation ΔZ between the blade position and the target design surface SD. The control of the operation of the blade 4 shown in FIGS. 5, 6, and 7 is used for the leveling control in the first control mode.

  In the specific example shown in FIG. 5, the first position threshold value Z1 is set to a positive value, and the second position threshold value Z2 is set to zero. In the specific example shown in FIG. 6, the first position threshold value Z1 is set to a positive value, and the second position threshold value Z2 is set to a negative value. In the specific example shown in FIG. 7, only the first position threshold value Z1 is set, and the second position threshold value Z2 is not set. As described above, the position deviation ΔZ is a value obtained by subtracting the height of the target design surface SD from the blade position (the cutting edge height of the blade 4). Therefore, when the blade position is higher than the height of the target design surface SD, the position deviation ΔZ is a positive value, and when the blade position is lower than the height of the target design surface SD, the position deviation ΔZ is Becomes a negative value.

  In the control examples of FIGS. 5, 6, and 7, when the position deviation ΔZ is equal to or larger than the first position threshold value Z1 (YES in step S4), as the position deviation ΔZ increases, a blade lowering command (a lift lowering command) is issued. Command value increases. In these control examples, when the position deviation ΔZ is equal to or more than a predetermined value, the command value is set to a constant value (maximum value). The command value may be set to a fixed value (maximum value) as soon as the position deviation ΔZ becomes equal to or greater than the first position threshold value Z1.

  The operating speed of the lift cylinder 8 increases and the operating speed of the blade 4 increases as the command value increases.

  In the control examples of FIGS. 5 and 6, the first position threshold value Z1 is set to a positive value slightly larger than zero, and in the control example of FIG. 7, the first position threshold value Z1 is set to zero.

  In the control examples of FIGS. 5 and 6, when the position deviation ΔZ is equal to or smaller than the second position threshold value Z2 (YES in step S6), as the position deviation ΔZ decreases, the command value of the blade lifting command (lift lifting command) increases. growing. In the control example of FIG. 7, when the position deviation ΔZ is equal to or smaller than the first position threshold value Z1, the command value of the blade raising command (lifting command) increases as the position deviation ΔZ decreases. In these control examples, when the position deviation ΔZ is equal to or smaller than a predetermined value, the command value is set to a constant value (maximum value). Note that the command value may be set to a constant value (maximum value) as soon as the position deviation ΔZ becomes equal to or less than the second position threshold value Z2.

  In the control example of FIG. 5, the second position threshold value Z2 is set to zero, and in the control example of FIG. 6, the second position threshold value Z2 is set to a negative value slightly smaller than zero. In the control example of FIG. 7, the first position threshold value Z1 is set to zero.

  In the control examples of FIGS. 5 and 6, when the position deviation ΔZ is smaller than the first position threshold value Z1 and larger than the second position threshold value Z2 (NO in step S6), the blade lowering operation (lift lowering) and the blade raising operation (lifting) ) Is not performed, and the relative position of the blade 4 with respect to the machine body is maintained (the above-described third control mode). By providing a region (dead zone) in which the relative position is held in a region where the positional deviation ΔZ is near zero, it is possible to prevent excessive movement of the blade 4 in a region where the positional deviation ΔZ is near zero. Can be suppressed.

  In a region where the blade load f is smaller than the second load threshold f2, when the condition for executing the first control mode is satisfied, the edge height of the blade 4 is increased as in the control examples of FIGS. 5, 6, and 7. When the height is higher than the target design plane SD, the blade lowering operation (lift lowering) is executed so that the command value of the blade lowering command (lift lowering command) increases as the position deviation ΔZ increases. . On the other hand, when the cutting edge height of the blade 4 is lower than the target design surface SD, the blade lift command (lift) is made smaller as the position deviation ΔZ becomes smaller (as the absolute value of the position deviation ΔZ becomes larger). The blade raising operation (lift raising) is performed so that the command value of the raising command is increased. By executing such a first control mode, the lift amount (the relative position of the blade 4 with respect to the machine main body) is controlled so that the cutting edge height of the blade 4 matches the height of the target design surface SD. Leveling is performed by

  FIG. 8 is a graph illustrating an example of control of the operation of the blade 4 based on the blade load f. The control of the operation of the blade 4 shown in FIG. 8 is used for the blade raising control (lift raising control) in the second control mode.

  In the control example of FIG. 8, when the blade load f is equal to or more than the second load threshold f2 (YES in step S1), the command value of the blade lift command (lift command) increases as the blade load f increases. In this control example, when the blade load f is equal to or more than a predetermined value, the command value is set to a constant value (maximum value). Note that the command value may be set to a constant value (maximum value) as soon as the blade load f becomes equal to or more than the second load threshold value f2.

  When the second control mode is executed when the blade load f is equal to or more than the second load threshold f2 as in the control example shown in FIG. 8, the lift-up control is performed according to the increase in the blade load f. The blade edge of the blade 4 rises, and the blade load f decreases. Thereby, it is possible to prevent the traveling of the work machine from being stuck due to an increase in the blade load f.

  When the position deviation ΔZ is equal to or larger than the first position threshold value Z1 in the intermediate load region (YES in step S8), the third control mode is executed, and the relative position of the blade 4 with respect to the body of the aircraft is held. You. As a result, the excavation is performed while the cutting edge height of the blade 4 is fixed within a range where the traveling of the working machine does not stack, so that unnecessary vertical movement of the blade 4 is suppressed, and the construction surface (excavation surface) is made smooth. The effect to be obtained is obtained.

  Further, when the position deviation ΔZ is smaller than the first position threshold value Z1 in the intermediate load region (NO in step S8), the first control mode is executed. Here, when the second position threshold value Z2 (the first position threshold value Z1 in the control example of FIG. 7) is set to, for example, zero as in the control example of FIG. 5, the cutting edge height of the blade 4 is lower than the target design surface SD. In this case, the blade raising operation (lift raising) is performed in the first control mode, thereby suppressing the problem of over-digging caused by the blade tip height of the blade 4 becoming lower than the target design surface SD. The effect to be obtained is obtained.

  As shown in the control examples of FIGS. 5 and 6, the first position threshold value Z1 may be set to a positive appropriate value. In these cases, when the blade load f is between the first position threshold value Z1 and the second position threshold value Z2 and the cutting edge height of the blade 4 is higher than the target design surface SD, the position deviation ΔZ is reduced to the first position threshold value Z1. If smaller, a blade lowering operation (lift lowering) is performed. Thereby, it is possible to perform leveling in which the height of the blade tip of the blade 4 matches the height of the target design surface SD. However, if the first position threshold value Z1 is set to an excessively large value, the blade load f is between the first load threshold value f1 and the second load threshold value f2, and the blade edge height of the blade 4 is higher than the target design surface SD. The blade lowering operation (lift lowering) is executed even at a relatively large distance. In such a case, the blade load f increases and the blade load f immediately becomes equal to or more than the second load threshold f2, so that the possibility that the blade raising operation (lift lift) is performed is increased. In such a case, the blade lowering operation (lift lowering) and the blade raising operation (lift raising) are frequently performed, and undulation (undulation) is likely to occur on the construction surface (excavation surface). Therefore, even when the blade deviation operation (lift down) is performed with the position deviation ΔZ being in a range where the position deviation ΔZ is smaller than the first position threshold value Z1 and larger than zero, the blade load f becomes the second position threshold Z1. It is preferable that the value is set to a value that does not exceed the load threshold value f2. When the first position threshold value Z1 is set to such a value, the position deviation ΔZ becomes smaller than the first position threshold value Z1, a blade lowering operation (lift lowering) is performed, and the blade load f gradually increases. In addition, since the blade load f is unlikely to be equal to or more than the second load threshold value f2, the generation of undulation on the construction surface due to frequent vertical movement of the blade 4 is suppressed in the intermediate load region, and stable leveling control is performed. Thus, the effect of increasing the construction efficiency can be obtained.

  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 deviation calculation unit 15 blade operation control unit 16 threshold setting unit 31 vehicle body position acquisition unit 32 vehicle body angle acquisition unit 33 blade angle acquisition unit 34 Blade load acquisition unit 100 Blade control device SD Target design surface Z1 First position threshold Z2 Second position threshold ΔZ Position deviation f Blade load f1 First load threshold f2 Second load threshold

Claims (4)

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 deviation calculation unit that calculates a position deviation that is a deviation between the blade position and the target design surface,
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, a second load threshold value that is a threshold value of the blade load, and a position threshold value that is a threshold value of the position deviation, and
A blade operation control unit that controls the operation of the blade,
The blade operation control unit is configured such that, when the blade load is equal to or less than the first load threshold, and the position deviation is equal to or greater than the position threshold, the blade descends and the position deviation approaches zero. Controlling the operation of the blade,
The blade control device, wherein the blade operation control unit controls the operation of the blade so that the blade rises regardless of the positional deviation when the blade load is equal to or greater than the second load threshold.   When the blade load is larger than the first load threshold and smaller than the second load threshold, and the position deviation is equal to or larger than the position threshold, the relative position of the blade with respect to the machine main body is held. The blade control device according to claim 1, wherein:   The blade operation control unit, the blade load is larger than the first load threshold and smaller than the second load threshold, and, when the position deviation is smaller than the position threshold, the position deviation to zero The blade control device according to claim 1, wherein the operation of the blade is controlled so as to approach the blade. The position threshold is a first position threshold,
The storage unit further stores a second position threshold that is a threshold of the position deviation and is smaller than the first position threshold,
When the blade load is equal to or less than the first load threshold and the position deviation is equal to or less than the second position threshold, the blade moves up and the position deviation approaches zero. The blade control device according to claim 1, wherein the operation of the blade is controlled as described above.

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