JP2872456B2 - Work control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for automatically controlling the driving of a bucket in a working machine such as an excavating machine or a loading machine having a bucket.

[0002]

2. Description of the Related Art In general, in a working device having a bucket, such as a wheel loader or a hydraulic shovel, the operation of the bucket is currently performed manually based on an operator's feeling. Table 1 below shows an outline of typical driving operations performed in the excavator.

[0003]

[Table 1]

[0004] However, the operation of the bucket by such manual operation requires considerable skill and puts a heavy burden on the operator. On the other hand, even if a skilled operator performs the operation, efficient operation is not always performed. Not exclusively.
Therefore, a device for automatically controlling the driving of the bucket has been developed.

Conventionally, as a method of performing such automatic control of bucket driving, a method of controlling a work trajectory of a bucket has been proposed. For example, JP-A-60-21
No. 9332 discloses an apparatus in which the trajectory of the bucket blade tip according to the work is determined in advance, and the bucket is driven along this trajectory.

[0006]

The above-mentioned apparatus for performing so-called excavation trajectory control has the following problems.

(1) In general, there is a point where the excavation force temporarily becomes excessive in ordinary excavation. However, the above point cannot be avoided simply by controlling the excavation trajectory. Therefore, at the above-mentioned points, the bucket and the like may be adversely affected in strength, and the bucket operating speed may be reduced.

(2) The digging trajectory of the bucket naturally depends on the digging target and the shape of the ground, but the digging trajectory control method cannot flexibly cope with this.

(3) In order to control the excavation trajectory, it is necessary to provide sensors such as potentiometers and encoders in all rotating parts, and it is necessary to detect the acting force of all actuators. A sensor is required, leading to increased costs.

(4) In the excavation trajectory control, a complicated calculation needs to be performed and a large-capacity CPU is required, which leads to an increase in cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a work control device capable of performing accurate bucket drive control in accordance with an actual operation state with a simple and low-cost structure. I do.

[0012]

SUMMARY OF THE INVENTION In a working machine having a bucket as described above, the point at which the excavation resistance increases and the point at which the moment acting on the bucket increases substantially coincide with each other. In this state, the greater the bite of the bucket into the excavation target, the greater the excavation resistance. Therefore, the judgment items of the bucket operation as shown in Table 1 can be replaced with the problem of the magnitude of the moment acting on the bucket.

The present invention has been made in view of such a point, and includes a bucket, a bucket supporting member rotatably supporting the bucket, a main body rotatably supporting the bucket supporting member, and A work machine comprising: a bucket rotation drive unit configured to rotate the bucket with respect to a bucket support member; and a bucket lifting drive unit configured to rotate the bucket support member with respect to a main body to move the bucket up and down with respect to a work surface. A bucket attitude detecting means for detecting the attitude of the bucket, an action force detecting means for detecting an action force for rotating the bucket, and a moment for momentarily calculating a work moment about the rotation axis of the bucket from the bucket attitude and the action force. Calculating means, and a bucket for controlling bucket rotation drive based on the calculated working moment And preparative rotation control means, in which a bucket elevator control means for controlling the bucket elevator driven based on the working moment.

Further, in addition to the above moment calculating means,
A moment time change amount calculating means for calculating a time change amount of the work moment; and a bucket rotation control means configured to control bucket rotation drive based on the work moment and the time change amount. By configuring the bucket lifting / lowering control means so as to control the bucket lifting / lowering drive based on the time change amount, more excellent effects as described later can be obtained (claim 2).

[0015]

According to the first aspect of the present invention, the bucket posture and the acting force on the bucket are detected during the work operation by the bucket, and the work moment, that is, the rotation of the bucket around its rotation axis is detected from these values. Is momentarily calculated, and based on the magnitude of the work moment, the control of the rotation driving of the bucket and the control of the elevation drive with respect to the excavation surface are executed.

According to the second aspect of the present invention, the time change amount is calculated in addition to the work moment,
Based on both values, the bucket drive control is performed in consideration of the increasing / decreasing tendency of the working moment.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS.

In this embodiment, the present invention is applied to a wheel loader as shown in FIG. The wheel loader includes a bucket 1, and the bucket 1 is pivotally mounted on a tip end of a boom (bucket support member) 2 so as to be rotatable about a shaft 9. The base end of the boom 2 is pivotally connected to the main body 8 so as to be rotatable around an axis 12, and the boom 2 is a boom cylinder (bucket elevating drive means).
The bucket 1 is driven to move up and down with respect to the excavation surface G during excavation by driving the boom 2.

An intermediate portion of the arm 3 is pivotally attached to an intermediate portion of the boom 2 so as to be rotatable around an axis 11. The upper end of the arm 3 is a bucket cylinder (bucket rotation drive means)
The lower end of the arm 3 is connected to the bucket 1 at a position different from the shaft 9 via the link 4 and the shaft 10, and the arm 3 is expanded and contracted by the bucket cylinder 5. The bucket 1 rotates so that the bucket 1 is driven to rotate around the shaft 9.

The bucket cylinder 5 is provided with a cylinder pressure sensor (acting force detecting means) 14 as shown in FIG. The cylinder pressure is detected. In addition, the shaft 1
2 includes a boom angle sensor (constituting a bucket attitude detecting means) for detecting a rotation angle of the boom 2 with respect to the main body 8.
The shaft 9 is provided with a bucket angle sensor (constituting bucket attitude detecting means) 18 for detecting a rotation angle of the bucket 1 with respect to the boom 2.

The detection signals of these sensors 14, 16, 18 are input to a controller 20 as shown in FIG.
Based on these detection signals, the controller 20 controls the rotation driving and the lifting / lowering driving of the bucket 1.

More specifically, the controller 20 includes a bucket attitude calculating means 21, a moment calculating means 22, a bucket rotation control calculating section 23, and a bucket elevating control calculating section 24.

The bucket attitude calculating means (constituting a bucket attitude detecting means) 21 is based on each rotation angle detected by the boom angle sensor 16 and the bucket angle sensor 18, based on the bucket attitude, that is, the ground angle of the bucket 1 and the above-mentioned operation. This is to calculate the radius of the moment about the axis 9 of the force. During the excavation work, based on the bucket attitude calculated by the bucket attitude calculating means 21 and the acting force detected by the cylinder pressure sensor 14, the moment calculating means 22
This is for calculating the excavation moment around the axis 9 acting on the bucket 1.

The bucket rotation control calculation unit 23 calculates a command signal to be output to the bucket cylinder oil pressure control unit 31 based on the magnitude of the excavation moment calculated by the moment calculation means 22. The expansion / contraction control, that is, the rotation control of the bucket about the axis 9 is executed. Similarly, the bucket raising / lowering control calculation unit 24 calculates a command signal to be output to the boom cylinder oil pressure control unit 32 based on the magnitude of the excavation moment, and controls the expansion / contraction of the boom cylinder 6 based on the command signal. Execute bucket lifting control.

Next, the control contents will be described with reference to the graph of FIG.

In this control, basic characteristics at the time of excavation by the bucket 1 are used. First, the operation of the bucket 1 is divided into bucket rotation, bucket lifting / lowering with respect to the excavation surface G (that is, rotation of the boom 2), and forward / backward movement of the bucket 1, and the bucket rotation is directed toward the rake side around the shaft 9. (Rotation counterclockwise in FIG. 2; retract)
And rotation to the discharge side (rotation in the clockwise direction in FIG. 2; dump). Among them, the advance of the bucket 1 is performed by the advance of the entire body 8, so that the drive control of the boom 2 and the bucket 1 is performed. Has no direct relationship with. Also, during excavation, it is not necessary to consider the backward movement of the bucket 1.

If the basic operation at the time of excavation is bucket advance, the following matters can be said with respect to the relationship between other operations, ie, the bucket rotating operation and the bucket elevating operation, and the state of the bucket 1. (a) Retracting the bucket reduces the excavation moment. That is, the resistance (the arrow R in FIG. 2) that the bucket 1 receives from the excavation target decreases. Conversely, when the bucket 1 is dumped or neutralized, the bite of the bucket 1 into the excavation target increases, and the excavation moment increases. (b) When the bucket 1 is lowered with respect to the excavation surface G, the bite of the bucket 1 into the excavation target increases. vice versa,
When the bucket 1 is raised, the bucket 1 moves in a direction to reduce the bite into the excavation target.

Therefore, in this embodiment, an appropriate limit value is set for the excavation moment calculated by the moment calculating means 22 shown in FIG. 1, and based on a comparison between this control value and a calculated value calculated every moment. In addition to performing bucket drive control, a series of operations from the start to the end of excavation by the bucket 1 are divided into the following three periods, and control according to each period is performed.

1) First Step (Initial Excavation) First, in the initial stage of excavation, it is necessary to stop the rotation of the bucket 1 in order to make the bucket 1 sufficiently dig into the object to be excavated. Therefore, the bucket rotation command is not issued until the excavation moment reaches the limit value M-1 shown in FIG.
When the excavation moment reaches the limit value M-1, the next second
Move to step. On the other hand, when raising and lowering the bucket 1, the bucket 1 may be raised even at the initial stage of excavation. In this embodiment, taking this point into consideration, the excavation moment is set to the limit value WM-4 (≦ M−
At the point of time exceeding 1), a command to raise the bucket (ie, rotate the boom 2 counterclockwise in FIG. 2) is issued.

2) Second Step (During Excavation) After the excavation moment reaches the limit value M-1, the second step
The process proceeds to a step where both bucket rotation and bucket lifting and lowering are controlled according to the excavation moment. In this embodiment, two types of limit values WM-2 and WM-3 (0 <WM-3 <WM-2) are set for the bucket rotation drive, and one type of limit value WM-5 is set for the bucket elevation drive.
(<0) is set, and the following control is performed. (a) If the excavation moment is higher than the limit value WM-2, it is considered that the excavation resistance is high and the bucket is sufficiently engaged, so that the bucket 1 is retracted. (b) When the excavation moment is equal to or greater than the limit value WM-3, the limit value WM
In the case of −2 or less, the bucket 1 is held neutral or dumped to make the bucket 1 bite further.
In this embodiment, the bucket 1 is actively dumped instead of being held neutral, and so-called swing excavation (heavy excavation) in which dumping and retraction are alternately repeated. (c) If the excavation moment is lower than the limit value WM-2, it is considered that abnormal excavation has occurred, and the bucket 1 is retracted to prevent the vehicle body 8 from floating. (d) When the excavation moment is larger than the limit value WM-5, the bucket is kept neutral for lifting and lowering, but when the excavation moment is smaller than the limit value WM-5 (in this case, the excavation moment is always negative). In this case, abnormal excavation is determined, and the bucket 1 is raised from the excavation surface G so that the vehicle body 8 does not rise. Therefore, when the limit value WM-5 is set to a small value, the boom 2 hardly moves and the excavation mode is only the bucket rotation, and when the limit value WM-5 is set to a sufficiently large value, the bucket 1 is Excavation surface G
Excavation mode while raising By executing such control based on the excavation moment, the bucket 1 performs smooth excavation while automatically avoiding a point where the excavation resistance becomes excessive.

3) Third Step (Late Excavation) When the above excavation proceeds, the bucket 1 is filled with the excavated material, while the bucket rotation angle increases, and finally the bottom surface of the bucket 1 is not the cutting edge but the object. And no more effective drilling can be expected. Therefore, after the bucket rotation angle reaches the predetermined limit value A-1, the second step is finished and the process proceeds to the third step, where control by the excavation moment is stopped and the bucket rotation angle is reduced to the limit value A-2 ( The bucket 1 is retracted until it reaches> A-1), and the excavation operation ends when the limit value A-2 is reached.

According to such an apparatus, in particular, the bucket 1
In the second step that requires precise control of the above, by performing control based on the magnitude of the excavation moment, it is possible to perform an accurate bucket operation in accordance with an actual operation state. In other words, unlike the conventional method of controlling the excavation trajectory, the bucket control can be flexibly adapted to any ground shape and the object to be excavated, and the bucket 1 can be subjected to excessive excavation resistance. However, good excavation can be realized while avoiding such a problem.

FIG. 4 shows the change over time of the bucket rotation angle, the excavation resistance, and the moment (excavation moment) due to the excavation resistance when the bucket operation is performed based on the driver's feeling as in the prior art, respectively, by lines 41 and 41. FIG. 5 shows the change over time of the bucket rotation angle, the excavation resistance, and the excavation moment under the control of the apparatus shown in the above embodiment by lines 51, 52, and 53, respectively. Things. As is clear from comparison between the two graphs, according to the apparatus of the present embodiment, the digging resistance and digging moment acting on the bucket 1 during digging are reduced over the entire area, as compared with the case where digging is performed manually as in the conventional case. It can be suppressed to a low value, and it is possible to reduce the strength load on the bucket 1 and perform efficient excavation.

Next, a second embodiment will be described. here,
An example in which the present invention is applied to a hydraulic excavator (backhoe) as shown in FIG. 6 will be described. This backhoe also has a bucket 1, a boom (constituting a bucket supporting member) 2, an arm 3 (constituting a bucket supporting member) 3, a link 4, a bucket cylinder 5, a boom cylinder 6, a main body 8, and a shaft similarly to the wheel loader. The arm 3 has a base end connected to a distal end of the boom 2 via a shaft 11.
Is driven to rotate. The bucket 1 is mounted on the tip of the arm 3 and connected to a bucket cylinder 5 attached to the arm 3 via a link 4 and a shaft 10. It is driven to rotate around nine turns.

Even in such a backhoe, there is no great difference from the wheel loader except that the bucket 1 is moved by the arm pulling operation. Therefore, the first step (the initial stage of excavation) and the third step (the first step) shown in the first embodiment are performed. The same control may be performed for the latter stage of excavation). The same applies to the second step (middle stage of excavation).
In the step, for example, better excavation can be realized by executing control as shown in FIG. That is, one type of limit value HM-5 is set for the bucket rotation drive.
(> 0), and two types of limit values HM-2 and HM-3 (0 <HM-3 <HM-2) for the bucket lifting drive.
Is set, and the following control is performed. (a) If the excavation moment is higher than the limit value HM-5, it is considered that the bucket 1 is sufficiently engaged, and the bucket 1 is retracted. (b) When the excavation moment is less than or equal to the limit value HM-5,
The bucket 1 is held neutral or dumped to make the bucket 1 bite further. In the example shown, bucket 1
Is held neutral. (c) When the excavation moment is larger than the limit value HM-2, the bucket 1 is considered to have sufficiently bite and the excavation resistance is large, so the rotation of the boom 2 moves the bucket 1 to the excavation surface G. Raise against. (d) When the excavation moment is equal to or greater than the limit value HM-3, the limit value HM
In the case of -2 or less, it is considered that good excavation has been performed, so that the bucket is kept neutral for lifting and lowering. (e) When the excavation moment is below the limit value HM-3, HM-4
If it is equal to or greater than 0 (in the example shown in the figure), the boom 2 is rotated to lower the bucket 1 in order to make the bucket 1 more bite into the excavation target. (f) Excavation moment is less than HM-4 (negative value in the figure)
In the case of, it is considered that abnormal excavation has occurred, and the bucket 1 is raised as in the case of (a).

By executing such control, the rotation angle of the digging blade of the bucket 1 and the height of the bucket pin (ie, the shaft 9 which is the rotation axis of the bucket 1) are as shown in the middle and lower parts of FIG. become. The area indicated by the dotted line in the middle graph of FIG. 7 is an area where the excavation blade angle of the bucket 1 is naturally changed by driving the boom 2 and the arm 3 even though the bucket rotation drive is not performed. .

This embodiment can be similarly applied to other hydraulic shovels, for example, a loading shovel as shown in FIG.

Next, a third embodiment will be described. In each of the embodiments described above, a plurality of limit values are set for the excavation moment, and the drive control of the bucket is performed in the second step based on the comparison between the limit value and the excavation moment calculated every moment. In the embodiment, the fuzzy control is applied to the bucket driving control in the second step. That is, a memory storing a fuzzy rule and a membership function is connected to the bucket rotation control operation unit 23 and the bucket elevation control operation unit 24 shown in FIG. 1, and the output value of the bucket cylinder drive command signal and the boom cylinder drive command In the figure, the output values of the signals are calculated.

In this embodiment, the work machine to be controlled is a wheel loader as in the first embodiment, and the excavation method is bucket swing excavation in which dumping and retraction are alternately repeated.

FIGS. 9 to 12 show membership functions of each variable in the fuzzy control, and Table 2 below shows the relationship between the antecedent and consequent parts, that is, rules. Table 3 shows a comparison between the main rules and the actual operation contents of the operator.

[0041]

[Table 2]

[0042]

[Table 3]

Of the variables shown here, Mn is a value obtained by normalizing the excavation moment calculated by the moment calculation means 22 for fuzzy control, and the reference value is set to 0 and −1 to +
This is a value set in the range of 1. In addition, SBMU indicates a bucket raising operation, SBK indicates an output value of a command signal for a bucket retract operation and a bucket dump operation, and when SBK is a positive value, it is a retract operation command, and when SBK is negative, a dump operation command. Means that.

As shown in Table 2, in a region where the excavation moment is greater than or equal to the reference value, the bucket retract operation is executed at a speed corresponding to the magnitude, and in a region where the excavation moment is equal to or less than the reference value, the dump operation is performed. However, when the excavation moment is abnormally low, the bucket retract operation is performed.
Further, the bucket raising operation is performed mainly on a region where the excavation moment is slightly lower than the reference value.

Executing such fuzzy control makes it possible to realize more precise bucket control in accordance with the actual excavation state.

In this embodiment, the case of rocking swing excavation (heavy excavation) is shown. On the other hand, when performing normal bucket excavation, that is, excavation operation in which bucket retraction and neutral holding are repeated, Since a bucket dump operation command is unnecessary, a rule for setting SBK to ZO when the excavation moment is NM or NS may be introduced. That is, in this case, rules such as those shown in Tables 4 and 5 below may be set.

[0047]

[Table 4]

[0048]

[Table 5]

Such fuzzy control is performed according to FIGS.
Needless to say, the present invention can also be effectively applied to the hydraulic excavator shown in FIG.

Next, a fourth embodiment will be described with reference to FIGS.

As shown in FIG. 12, the apparatus shown in this embodiment includes, in addition to the moment calculating means 22 for calculating the excavating moment every moment, a moment time change calculating means 25 for calculating the temporal change of the excavating moment. In addition, fuzzy control is performed on the rotation and elevation of the bucket 1 based on both the current excavation moment and the amount of change over time. The moment time change amount calculating means 25 calculates a difference between the currently obtained excavation moment calculation value and the excavation moment calculation value obtained by the previous calculation, and divides the difference by a sampling cycle of the excavation moment value to obtain a moment. It is configured to output as a time change amount. In the present invention, for example, a plurality of calculation values calculated in the past may be sampled and the average thereof may be obtained regardless of the calculation procedure of the moment time change amount.

This embodiment shows a case where normal excavation is performed in the backhoe shown in FIG. 6, and the variables used are the values Mn, SBK, SBM shown in the previous embodiment.
In addition to U, a standardized moment time variation ΔM and an arm pull signal output value SAME are introduced. The membership functions of these variables are shown in FIGS. 13 and 14, the rules for the arm pull signal output value SAME are shown in Table 6, the rules for the bucket rotation operation signal output value SBK are shown in Table 7, and the boom elevating operation signal output Table 8 shows rules for the value SBMU, and FIG. 15 shows specific control operations.

[0053]

[Table 6]

[0054]

[Table 7]

[0055]

[Table 8]

In Tables 6 to 8, the conditions relating to the excavation moment specification value Mn and the moment time variation ΔM are linked by “and” in the antecedent part. For example, the upper left area in Table 6 is If Mn = NB and ΔM = NB Then SAME = ZO.

First, regarding the arm pulling operation, as shown in Table 6, in the region where the excavation moment standard value Mn is close to the reference value and the moment time variation ΔM is close to 0, the arm pulling operation, that is, the bucket forward operation is performed. The arm pulling speed is reduced as the excavation moment standard value Mn becomes farther from the reference value. Even when the excavation moment standard value Mn is close to the reference value, if the absolute value of the moment time variation ΔM is large, the moment value is likely to be far from the reference value in the future. Speed is reduced. further,
When the excavation moment standard value Mn is very low and decreases at high speed, and when the excavation moment standard value Mn is very high and increases at high speed, the arm pulling operation is controlled in the stop direction.

As shown in Table 7, when the excavation moment specification value is equal to or less than the reference value, the bucket rotation operation is controlled in the direction of maintaining neutrality, as shown in Table 7.
Even in this case, when the moment time variation ΔM is extremely large, the bucket retract operation is performed because the excavation moment standard value Mn is likely to increase in the future. Conversely, even when the excavation moment standard value Mn is high, if the time variation ΔM is negative, that is, if the moment is decreasing, there is a high possibility that the excavation moment standard value Mn will approach the reference value in the future. Therefore, the bucket retract operation is suppressed.

The same applies to the bucket lifting operation.
As shown in Table 8, when the excavation moment standard value Mn is close to the reference value and the change amount ΔM is small, the control is advanced in a direction in which the bucket lifting / lowering operation is not performed. If the excavation moment specification value Mn is lower than the reference value and it is increasing even if the excavation moment specification value Mn is lower than the reference value, there is a high possibility that the excavation moment specification value Mn will return to the reference value in the future. Bucket raising operation is suppressed. On the other hand, when both the excavation moment standard value Mn and its time change amount ΔM are large, the bucket raising operation is promoted. Conversely, when both the excavation moment standard value Mn and its time change amount ΔM are small, the bucket lowering operation is performed. Is promoted. However, when both the excavation moment standard value Mn and the time change ΔM are extremely low, abnormal bucket is currently occurring, or abnormal excavation is very likely to occur in the future. The control is performed in the raising direction.

According to such an apparatus, by considering not only the current value of the excavation moment but also the time change thereof, more efficient automatic excavation while predicting the fluctuation of the future excavation moment. Can be realized. Further, the control in consideration of the moment time change amount is also applicable to a wheel loader and other working machines, and is also applicable to swing excavation instead of normal excavation. Instead of the fuzzy control as described above, a limit value is provided for both the excavation moment and its time change amount in the same manner as described in the first embodiment, and the drive control of the bucket 1 is performed by comparing the limit value. You may do so.

The present invention is not limited to the above-described embodiments, but may take the following forms as examples.

(1) In the first embodiment, the cylinder pressure sensor 14 for detecting the cylinder pressure of the bucket cylinder 5 is used as the means for detecting the acting force for rotating the bucket 1. The present invention is not limited to this, and various types can be used as long as the action force can be detected.
For example, the same effect as described above can be obtained by using a strain sensor that detects the distortion of the shaft 10 that transmits the rotational force to the bucket, the distortion of the link 4 connected to the shaft 10, and the like.

(2) In the first embodiment, the means for detecting the bucket attitude is such that the rotation angle of the bucket 1 with respect to the boom 2 and the rotation angle of the boom 2 with respect to the main body 8 are detected. The bucket attitude can be detected by detecting other values. For example, in the case of a wheel loader, detection of the ground angle of the bucket 1 and the rotation angle of the bucket 1 with respect to the boom 2, detection of the length of the bucket cylinder 5 and the length of the boom cylinder 2,
Alternatively, the posture of the bucket can be ascertained by detecting these values in an appropriate combination. In the case of a hydraulic shovel, the angle of the bucket 1 to the ground and the angle of the bucket 1 to the arm are detected. Cylinder 5
Of the bucket posture by detecting the length of the bucket 1, the arm angle of the bucket 1 with respect to the arm 3 and the boom angle of the arm 3 with the body angle of the boom 2, or by appropriately combining the values described above. .

(3) In the first and second embodiments, the limit value WM-
2, WM-3, HM-2, HM-3, etc. are shown as being constant during excavation. However, these values may be changed according to the bucket rotation angle during the excavation period. For example, when the limit values WM-2 and WM-3 are changed as shown in the graph of FIG. 16, the limit value WM-2 is low immediately after the start and immediately before the end of the middle excavation period, so that the bucket retract operation is performed. Will be encouraged. In the first half of the excavation, the excavation state is relatively unstable. Therefore, even if the excavation is not abnormal, a negative excavation moment may temporarily occur. Since the value is set to a negative value, it is possible to prevent the bucket 1 from being unnecessarily retracted even though there is no excavation abnormality.

The limit value relating to the excavation moment or the limit value relating to the time variation of the excavation moment may be appropriately set according to the type and size of the machine.

(4) In the third and fourth embodiments, seven labels are set for the membership function of each variable. However, the number of labels is appropriately determined according to the structure of the machine and the contents of the variables. It may be increased or decreased.

[0067]

First, according to the first aspect of the present invention, a work moment about the rotation axis of the bucket is calculated every moment by detecting a bucket posture and an acting force for rotating the bucket, and the bucket rotation is performed based on the work moment. Since the driving and the bucket lifting / lowering driving are controlled, the following effects can be obtained.

(A) Since the bucket drive control is performed while monitoring the work moment during the work, the bucket can be operated so as to avoid the point where the work resistance becomes extremely high. Therefore, unlike a conventional device that performs work trajectory control irrespective of the work moment, a large load is applied at the above points to reduce durability, and the traveling speed of the bucket does not extremely decrease. Even without skill, even an unskilled operator can perform a smooth and efficient operation (a large load amount and a short cycle time). There is also an advantage that energy consumption during excavation is reduced.

(B) Since the control is based on the work moment without depending on the trajectory of the bucket, it is possible to flexibly cope with a wide range of work conditions regardless of the work object or the shape of the ground. Therefore, it is particularly effective when the work object is uneven or when the shape of the ground is complicated.

(C) Since control can be performed as long as the value required for calculating the working moment is detected at a minimum, the required number of sensors is greatly reduced as compared with the case where excavation trajectory control is performed. In addition, since the operation contents are simplified, the required capacity of the CPU is small, so that a significant cost reduction can be achieved.

Further, according to the second aspect of the present invention, in addition to the above-mentioned work moment, the amount of change over time is calculated, and the bucket rotation drive and the bucket lifting drive are controlled based on both values. By considering not only the current work moment value but also its increasing and decreasing tendency, it is possible to perform control while predicting future fluctuations of the excavation moment, and realize more efficient automatic excavation. effective.

[Brief description of the drawings]

FIG. 1 is a block diagram of an excavation control device according to a first embodiment of the present invention.

FIG. 2 is an overall side view of a wheel loader provided with the excavation control device.

FIG. 3 is a graph showing a control operation example by the excavation control device.

FIG. 4 is a graph showing a time change of an excavation state in excavation by a manual operation of a driver.

FIG. 5 is a graph showing a time change of an excavation state in excavation under the control of the excavation control device.

FIG. 6 is an overall side view of a backhoe provided with an excavation control device in a second embodiment.

FIG. 7 is a graph showing a control operation example by the excavation control device.

FIG. 8 is an overall side view of a loading shovel provided with an excavation control device.

FIG. 9 is a diagram showing a membership function of an excavation moment standard value which is a variable used in fuzzy control in the third embodiment.

FIG. 10 is a diagram showing a membership function of a bucket rotation operation signal output value which is a variable used in the fuzzy control.

FIG. 11 is a diagram showing a membership function of a bucket raising operation signal output value which is a variable used in the fuzzy control.

FIG. 12 is a block diagram of an excavation control device according to a fourth embodiment.

FIG. 13 is a diagram showing a membership function of a moment time variation, which is a variable used in fuzzy control performed by the excavation control device.

FIG. 14 is a diagram showing a membership function of an arm pulling operation command signal output amount which is a variable used in the fuzzy control.

FIG. 15 is a graph showing a control operation example by the excavation control device.

FIG. 16 is a graph showing a setting example of a limit value of an excavation moment.

[Explanation of symbols]

Reference Signs List 1 bucket 2 boom 3 arm 5 bucket cylinder (bucket rotation driving means) 6 boom cylinder (bucket lifting / lowering driving means) 8 main body 14 cylinder pressure sensor (acting force detecting means) 16 boom angle sensor (constituting bucket attitude detecting means) 18 bucket Angle sensor (constituting bucket attitude detecting means) 20 controller 21 bucket attitude calculating means (constituting bucket attitude detecting means) 22 moment calculating means 23 bucket rotation control calculating section 24 bucket elevating control calculating section 25 moment time change calculating means

Claims (2)

(57) [Claims] 1. A bucket, a bucket support member rotatably supporting the bucket, a main body rotatably supporting the bucket support member, and bucket rotation driving means for rotating the bucket with respect to the bucket support member. A bucket attitude detecting means for detecting the attitude of the bucket, comprising: a bucket attitude detecting means for detecting the attitude of the bucket; and a bucket elevating drive means for elevating the bucket with respect to a work surface by rotating the bucket supporting member with respect to the main body. Acting force detecting means for detecting an acting force to be rotated; moment computing means for momentarily computing a working moment about the rotation axis of the bucket from the bucket posture and acting force; and bucket rotation driving based on the computed working moment. Bucket rotation control means for controlling the And a bucket elevating control means for controlling the lifting / lowering of the bucket. 2. A bucket, a bucket supporting member that rotatably supports the bucket, a main body that rotatably supports the bucket supporting member, and bucket rotation driving means that rotates the bucket with respect to the bucket supporting member. A bucket attitude detecting means for detecting the attitude of the bucket, comprising: a bucket attitude detecting means for detecting the attitude of the bucket; and a bucket elevating drive means for elevating the bucket with respect to a work surface by rotating the bucket supporting member with respect to the main body. Acting force detecting means for detecting the acting force to be rotated, moment calculating means for momentarily calculating the working moment of the bucket from the bucket posture and acting force, and moment for computing the time variation of the momentarily calculated working moment Time change amount calculation means, based on the work moment and its time change amount A bucket rotation control means for controlling the bucket rotation drive, and a bucket lifting control means for controlling the bucket lifting drive based on the work moment and the time variation thereof.