JPS6360329A - Controller for starting attitude for excavation in loading machine - Google Patents

Abstract

PURPOSE:To raise the efficiency of excavation by a method in which a target value of bucket angle at the beginning of excavation is set up, the set target value is corrected by every excavation according to the minimum value of vertical resistance of bucket, and the bucket is rotationally operated on a place corresponding to the corrected target value at the beginning of next excavation. CONSTITUTION:The detected value theta1 of the angle sensor 2 of bucket is put in a micro computer 10 where vertical component, etc., of excavation resistance to be applied to bucket 1 during the excavation period is calculated using the value theta1. On the basis of the calculated values, the operation of the oil-pressure circuit of bucket cylinder 7 at the automatic excavation mode is controlled. At the beginning of automatic excavation, the switch-on of a reset button 12 is judged by the computer 10, the target value (theta1) of bottom plate angle theta1 of the bucket 1 is reset to initial value thetac, and the bucket 1 is rotationally operated. The detected output of the sensor 2 is then fed back. The value (theta1) is corrected to the target value (theta1') obtained then the set up. In the same way, the circuit 20 is controlled so that the bottom plate angle theta1 of the bucket 1 becomes the value (theta1').

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a loading machine such as a wheel loader, payloader, or tractor shovel that has a boom and a bucket as a working machine, and that automatically adjusts the bucket posture at the start of excavation. The present invention relates to an optimized device.

[Prior Art] Loading machines such as wheel loaders, payloaders, and tractor excavators that have booms and buckets as work-specific actuators are compact, have a small turning radius, and are inexpensive to purchase, so they are widely used at civil engineering work sites, in the livestock industry, and in the livestock industry. It is used in a wide range of fields such as horticulture, landscaping, and snow removal work.

In this type of loading machine, a boom cylinder rotates the boom up and down, and a bucket cylinder causes the bucket to perform tilt and dump operations, and these rotation operations of the boom and bucket move the earth and sand away. Carry out excavation and loading work.

In such a loading machine, the attitude of the working machine at the start of excavation is usually fixed at one position, and the bucket is set so that the bottom plate is substantially horizontal in terms of penetrability. This attitude of the bucket is good when the particle size of the excavated soil is small, but in the case of coarse-grained soil that contains gravel, rocks, etc., the coarse-grained soil may get caught between the bucket and the ground. As a result, upward load resistance acts on the bucket, and in this case, tire slippage or upward slippage of the bucket often occurs, resulting in insufficient excavated soil volume.

Therefore, with conventional equipment, in the case of such coarse-grained soil,
At the start of excavation, the operator manually adjusts the attitude of the bucket so that the blade edge of the bucket points slightly downward by operating the lever for each job as appropriate.

[Problems to be Solved by the Invention] As described above, in the conventional equipment, adjustment and control of the excavation start position of the working machine relies heavily on the operator's control.
For this reason, there is a problem in that work efficiency varies greatly depending on the driving technique of the driver.

[Means for Solving Problems] Therefore, the present invention provides a setting means for setting a target value of the bucket angle at the start of excavation, and a means for sequentially calculating the vertical component of the excavation resistance applied to the bucket during excavation. a set value correcting means for determining a minimum value of vertical excavation resistance and correcting the bucket angle target value set in the setting means for each excavation according to the minimum value; and a drive means for rotationally driving the bucket to an excavation start position corresponding to the corrected target value of the setting means.

[Operation] According to this configuration, the bucket posture at the start of excavation is optimized for each excavation based on the minimum value of vertical excavation resistance in the previous excavation.

[Embodiment 1] Fig. 2 shows an example of the external configuration of a wheel loader to which the present invention is applied. A boom angle sensor 4 detects the angle θ2, a hydraulic sensor 6 (not shown in FIG. 2) detects the hydraulic pressure Pa of the pressure oil supplied to the boom cylinder 5, and a hydraulic pressure Pb of the pressure oil supplied to the bucket cylinder 7. Oil pressure sensor 8 (
(not shown in FIG. 2) is provided.

The detected values θ1, θ2, Pa and pb of the bucket angle sensor 2, boom angle sensor 4, and oil pressure sensors 6 and 8 are input to the microcomputer 10 as shown in FIG. The microcomputer 10 sequentially calculates the horizontal component Rh and vertical component Rv of the excavation resistance applied to the bucket 1 during excavation using these detected values, and in the automatic excavation mode, the hydraulic circuit 20 is activated based on these calculated values Rh and Rv. The drive control is performed.

The calculated horizontal resistance Rh and vertical resistance RV are stored in a memory (not shown) in the microcomputer 10, and the stored vertical resistance Rv is used to determine the bucket attitude at the start of excavation. Used for performance f9 (described later).

The hydraulic circuit 20 is composed of a boom control pulp that drives the boom cylinder 5, a bucket control valve that drives the bucket cylinder, etc., and expands and contracts the boom cylinder 5 and bucket cylinder 7 according to commands from the microcomputer 10 to control the boom 3. The bucket 1 is moved up and down and the bucket 1 is tilted and dumped. Note that 11 is a switch for specifying the own vJ excavation U-do, and 12 is a switch for initializing the bucket attitude angle at the start of excavation.

Before explaining the bucket attitude angle control at the start of excavation according to the configuration of this embodiment, an example of a method for deriving the horizontal resistance Rh and the vertical resistance Rv will be explained with reference to FIGS. 3 and 4.

In this method, the input information is bucket rotation angle θ1,
Using the boom rotation angle θ2, the oil pressure Pa of the pressure oil supplied to the boom cylinder 5, and the oil pressure Pb of the pressure oil supplied to the bucket cylinder 7, the horizontal resistance Rh and the vertical resistance Rv are derived using these detected values.

Now, if the cross-sectional areas of the boom cylinder 5 and bucket cylinder 7 are Sa and Sb, respectively, the cylinder forces Fa and Fb of each cylinder 5 and 7 are Fa = Pa -8a
−(1)Fb =Pb −8b
...(2) becomes.

Here, it is assumed that the resistance action point PD (XD, YD) changes as shown in FIG. 4 in response to the rotation of the bucket 1 (rotation angle θ1). In the graph shown in FIG. 4, the vertical axis is the distance DL between the tip of the bottom plate of the bucket and the point of resistance PO, and the horizontal axis is the bucket rotation angle θ1.
θh (fixed value) is the angle at which the side edge 1a of the bucket 1 becomes horizontal, and lc is the length of the side edge 1a.

Now, consider the X-Y coordinates centered on pin Po, and calculate the coordinates of pin P1 (X1', Y
1'), the coordinates (Xl, Yl) of Pl after the boom 3 rotates by θ2 are as follows, and the illustrated distance between the bucket pin P1 and the tip point of the bucket bottom plate is 101.The angle formed by the bucket bottom plate and the side edge 1a of the bucket is When ψ is ψ, the coordinates of PO (XD, YD) after bucket 1 and boom 3 rotate by θ1 and θ2 are:
ψ・(4)YD=Y1+j e Sinθ1−DL
sin ψ・(5), and based on the graph in Figure 4, θ
The coordinates of the PD after 1.02 rotations can be specified.

Now, the dimensions shown in Figure 3 are Ll and L2.

L3. L4. L5 and considering the balance of moments around pin Po, Rv -XD +Rh -YD -Fa -14-Fb
-Ls=O... (6) Also, considering the balance of moments around pin P1, Rv ・(XD +X1)-Rt+ ・(Yl-YD
)−Fb′ L3 =O (7). Since the following holds true, Rh and RV can be obtained by solving these equations fG) (7) and (8).

Next, the bucket attitude control and automatic excavation operation according to the configuration of this embodiment will be explained with reference to the flowchart shown in FIG.

When performing self-vJ excavation, the operator is white! Turn on the J+ excavation mode switch 11.

Next, the operator presses the reset button 12 when it is detected that the amount of excavated soil has changed drastically. At the start of excavation, the microcomputer 10 determines whether or not the reset button 12 is pressed (step 100), and as long as the reset button 12 is pressed, the bottom plate angle θ1 of the bucket 1 at the start of excavation (6th (see figure) △ target value θ1 is set to a predetermined initial value θC (for example, downward 2.5
At the same time, the target value bone 2 of the rotation angle θ2 (see FIG. 6) of the boom 3 at the start of excavation is initialized to a predetermined initial value θd (step 110).

Thereafter, the microcomputer 10 appropriately controls the hydraulic circuit 20 to drive the bucket cylinder 7, rotates and stops the bucket 1 so that the bottom plate angle θ1 of the bucket 1 becomes the target value θC (step 130). At this time, the detection output of the bucket angle sensor 2 is used as a feedback signal. Furthermore, microcomputer 1
0 controls the hydraulic circuit 20 to drive the boom cylinder 5, rotates and stops the boom 3 so that the boom angle θ2 becomes the target value θd (step 140). At this time too,
The detection output of the boom angle sensor 4 is used as a feedback signal.

However, in the determination in step 100, if the reset button 12 is not pressed, the microcomputer 10 corrects and sets the bucket bottom plate angle target value θ1 to the target value Δ61' obtained after the completion of the previous excavation. Set the boom rotation angle target value θ2 to the target value obtained after the completion of the previous excavation.
△ Correct to △02'. These target values 61' and 62' will be explained in detail later. In this case, the microcomputer 10 then controls the hydraulic circuit 2.
0, the bucket is driven (step 140) so that the bottom plate angle θ1 of the bucket 1 becomes the target value 01' (step 140).

After the bucket, bucket 1, and boom 3 are each set at one of the excavation start positions in this manner, automatic excavation is started.

As for this automatic excavation, for example, Japanese Patent Application No. 61-65182
The automatic excavation technology shown in the issue is used. That is, for the horizontal resistance, the upper and lower limit setting values Rhu and Rhd shown in FIG. 7 are set, and for the vertical resistance, the settings fii Rvs are set as shown in FIG. By alternately tilting the bucket and rotating the boom upward according to the bundling, the horizontal resistance Rh is made to reciprocate between the upper limit setting value Rhu and the lower limit setting value Rhd (7th (see figure), then the vertical resistance detected value RV becomes the ship's set value RVS.
After exceeding this point, automatic excavation is performed by tilting the bucket to the stroke end.

The horizontal resistance Rh and vertical resistance RV sequentially determined during this automatic excavation are sequentially accumulated and stored in the memory within the microcomputer 10, and after the automatic excavation is completed (step 160), the stored vertical resistance Rh and vertical resistance RV are By using the resistance RV, the gate value θ1 of the bucket bottom plate angle at the next excavation can be
′ is determined.

Δ That is, this target value 01' is determined according to the following equation (step 170), l.

△C θ1' = θ1-Gl (Rvn-Rv) = (9) In the above equation, G1 is the initial value θC1 set in step 110 or the current excavation 0 set in step 120.
The nine mark value θ... (obtained after the completion of the previous excavation), and Rvn is the minimum value of the vertical resistance RV during the current excavation, as shown in Figure 7, and is usually a negative value (upward force).
Take. Further, RV is a target value that the minimum value Rvn+ of the vertical resistance should take, and is usually set to about 11,000 kg for an 8-ton vehicle. G1 is a gain constant.

Next, the microcomputer 10 corrects the marker value θ2 of the boom angle θ2 so that the height of the bucket cutting edge is constant according to the target value 01' of the bucket bottom plate angle determined according to the equation (9) (step 180). . In FIG. 6, consider the X-Y coordinates with point Pa as the origin. The position of the bucket pin is Pl, the position of the bucket tip is P
2. When the bucket bottom plate is horizontal, the bucket cutting edge position is P2', the angle between line segment PIP2' and the horizontal line is θe (fixed value), the angle between line segment P1P2 and the horizontal line is θ, bucket bottom plate angle G1, Pa P1=J11, P1
P2 = J12, if the Y coordinate of P2 is P2 (Y), θ = θ1 + θe P2 (Y) = J11Sinθ2 +12 sin
(θ1+θe)... (10) It becomes.

Here, 02 = 92'(92' is the corrected boom angle concavity target value), θ1 = θ1', and the above (10)...
・(11) becomes P2(Y)1. ! ! 1.12 and θe are fixed values, so find the target value 02' of the boom angle at which the bucket cutting edge height P2 (Y) remains constant according to the corrected target value 01' of the bucket bottom plate angle. be able to.

△ △ 01' and 62' obtained in this way are stored in the memory in the microcomputer 10, and are used at the next excavation.
When the reset button 12 is not pressed, these values are used as target values for the bucket bottom plate angle and the boom angle.

In other words, the bucket angular posture at the start of excavation will be automatically corrected for each excavation according to the minimum value of vertical resistance during the previous excavation, unless the reset button 12 is pressed, and the bucket 1 will always maintain the excavation load. It is possible to take the optimal position for starting excavation according to the situation. Then, when the amount of excavated soil has changed significantly, the operator presses the reset button 12 and returns to the initial position! Hi! Make sure to remove it.

In addition, in the present invention, the horizontal resistance Rh and the vertical resistance RV
The performance method for determining this is not limited to the method explained using FIGS. 3 and 4. For example, the load applied to the bucket may be detected using a load meter such as a load cell,
Rh and Rv may be determined based on the force balance between the detected value and the horizontal and vertical resistances Rh and Rv.

Furthermore, the method of automatic excavation is not limited to the one described in Japanese Patent Application No. 61-65182, and other automatic excavation techniques may be used.

Furthermore, when controlling the bucket posture, it is preferable to drive the boom so that the height of the bucket tip is constant at the start of excavation, but it is preferable to drive only the bucket based on the previous excavation resistance to optimize the initial bucket posture. It is also possible.

Furthermore, the loading machine to which the present invention is applied is not limited to wheel loaders, but may also include payloaders, tractor excavators, etc.
It is applicable to all machines that have a boom and a bucket as work equipment actuators.

[Effects of the Invention] As explained above, according to the present invention, the posture of the work machine at the start of excavation is automatically corrected based on the change in the previous excavation resistance, so the bucket can be moved regardless of the type of soil to be excavated. It is now possible to always set the optimum initial position, which makes it possible to equalize the amount of excavated soil and improve excavation efficiency.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of the control configuration of an embodiment of the present invention, Fig. 2 is a side view showing the external structure of a wheel loader and an example of arrangement of each sensor, and Fig. 3 is a block diagram showing an example of the control configuration of an embodiment of the present invention.
A diagram for explaining an example of calculation for determining h and Rv. Figure 4 shows one of the set movement loci of the resistance application point used in the calculation example
Graph showing an example, Figure 5 is a flowchart showing a concrete example of the operation of the same example, Figure 6 is a diagram to explain how to correct the boom angle target value at the start of excavation, Figure 7 is a horizontal diagram during excavation. Graphs showing examples of changes in resistance and vertical resistance over time,
FIG. 8 is a graph showing the relationship between the vertical resistance setting value Rvs and the bucket height y. 1...Bucket, 2...Bucket angle sensor, 3...
- Boom, 4... Boom angle hinge, 5... Boom cylinder, 6.8... Oil pressure sensor, 7... Bucket cylinder, 10... Microcomputer, 11...
Automatic zero excavation designation switch, 12...Bucket attitude initialization switch, 20...Hydraulic circuit. Figure 3 Figure 4 Figure 6

Claims (3)

[Claims] (1) In an excavation start position control device for a loading machine that automatically controls the excavation start position of the bucket in a loading machine having a boom and a bucket, a setting means for setting a target value of the bucket angle at the time of starting excavation; The vertical component of excavation resistance applied to the bucket during excavation is sequentially calculated, the minimum value of the calculated vertical excavation resistance is determined, and the bucket angle target value set in the setting means is corrected for each excavation according to the minimum value. and a drive means for rotating a bucket to an excavation start position corresponding to the target value of the setting means corrected by the set value correcting means when excavation is started next time. Excavation start attitude control device. (2) The target value of the setting means is initialized to a predetermined initial value by turning on a predetermined switch.
Excavation start position control device for the loading machine described in ). (3) In an excavation start position control device for a loading machine that automatically controls the excavation start position of the bucket in a loading machine having a boom and a bucket, settings for setting target values of the bucket angle and boom angle at the time of starting excavation, respectively. means: sequentially calculating vertical components of excavation resistance applied to the bucket during excavation, determining the minimum value of the calculated vertical excavation resistance, and setting each bucket angle target value set in the setting means according to the minimum value; a first set value correcting means that is corrected for each excavation; and a boom that is set in the setting means according to the bucket angle target value that has been corrected by the first set value correcting means so that the height of the bucket cutting edge is constant. a second set value correcting means for correcting the corner target value for each excavation; and when the next excavation starts, excavation corresponding to each target value of the setting means corrected by the first and second set value correcting means. An excavation start position control device for a loading machine, comprising a drive means for rotationally driving a bucket and a boom to a starting position.