JPS63118426A - Controller and controlling method for blade of bulldozer - Google Patents

Abstract

PURPOSE:To permit composite control on tilting or angling action by using two cylinders to put the blade to tilting and angling actions. CONSTITUTION:A blade 10 is connected to a C-frame 11 in a tilting or angling manner and the first and second cylinders 15 and 16 are set between the blade 10 and the C-frame. An indicator by which to indicate the tilting angle and angling angle of the blade 10 is also provided, and a device to calculate target cylinder length on the basis of indications of the indicator and a cylinder controller to control the length of the cylinder to target length are provided. Composite control can thus be made for two cylinders 15 and 16 for only tilting or angling action.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a bulldozer blade control device and method in which the bulldozer blade is tilted and angled by a cylinder.

[Conventional technology]

In the conventional mechanism for tilting and angulating the blade of a bulldozer using a cylinder, as shown in Fig. 14, the blade 1 is connected to the C frame 3 by a ball joint, and is also connected by a rod 9 to rotate the blade at an angle. Two angle cylinders 5a, 5b and one tilt cylinder 6 are installed between the C frame 3 and the blade 1.

When the blade 1 is angled to the left or to the right, the length of the tilt cylinder 6 is fixed and the length of the left and right angle cylinders 5a is fixed.

When changing the length of the blade 5b or tilting the blade 1 to the left or right, use the left and right angle cylinders 5.
This is done by changing the length of the tilt cylinder 6 while keeping the lengths a and 5b fixed.

In addition, in the same figure, 7.8 is a lift cylinder, and 9 is a pitching prevention rod.

[Problem that the invention seeks to solve]

However, the above-mentioned conventional blade tilt and angle control device has a problem in that the number of cylinders is large, the mechanism becomes complicated, and the amount of suspension of the work machine increases.

The object of the present invention was made in view of the above-mentioned circumstances.The purpose of the present invention is to reduce the number of cylinders that tilt and angle the blade to two, simplify the mechanism, reduce the suspension of the work machine, and only perform tilt or angle operations. It is an object of the present invention to provide a blade control device for a bulldozer that can perform combined control of the two cylinders as described above.

Another object of the present invention is to take appropriate measures in the event that the blade changes its posture unexpectedly due to the load applied to the blade, etc. when changing the posture of the blade through combined control of the two cylinders. An object of the present invention is to provide a method for controlling a bulldozer blade.

[Means and operations for solving the problem] According to the present invention, the blade is connected to the C frame so as to be tiltable and angular, and the blade is connected to the C frame so as to be able to tilt and angle freely, and there is a gap between the blade and the C frame depending on the combination of the lengths of each cylinder. The first and second cylinders are arranged in such a manner that the tilt angle and angle angle of the blade are uniquely determined, and an instruction means is provided for independently indicating the target tilt angle and angle angle of the blade, When the target tilt angle and angle angle of the blade are instructed by this instruction means, it is necessary to set the blade to the target tilt angle and target angle based on the instructed target tilt angle and target angle angle. The target cylinder lengths of the first and second cylinders are converted, and the first and second cylinders are adjusted so that the actual cylinder lengths of the first and second cylinders become the converted target cylinder lengths. We are trying to have multiple control over these.

Further, when controlling the blade as described above, the tilt angle and angle angle before the blade is controlled are stored in advance as initial values, and the target angle of either one of the tilt angle and the angle angle of the blade is specified. Said first
, after the combined control of the second cylinder, the deviation of the other angle that was not instructed from the initial value is determined, and the deviation is adjusted so that the deviation falls within the allowable range without changing the current angle of the one angle. The first and second cylinders are further controlled in a combined manner to correct an unexpected change in the attitude of the blade.

Furthermore, during the above-mentioned blade control, during the combined control of the first and second cylinders based on an instruction of a target angle of at least one of the tilt angle and the angle angle of the blade,
Control of the first and second cylinders is prohibited when at least one of the expansion and contraction speeds of the first and second cylinders is equal to or lower than an allowable minimum speed to prevent an unexpected change in attitude of the blade. ing.

Furthermore, in the above-mentioned control, the tilt angle and the angle angle before the blade is controlled are stored in advance as initial values, and the tilt angle and the angle angle of the blade are adjusted according to an instruction of a target angle of at least one of the tilt angle and the angle angle of the blade. First,
During the combined control of the second cylinder, when the expansion and contraction speeds of the first and second cylinders are both below the allowable minimum speed, the control of the first and second cylinders using the target angle is prohibited, and then The first and second cylinders are jointly controlled using the stored initial value as a target angle to return the blade to its initial blade attitude.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a perspective view showing one embodiment of a bulldozer blade mechanism according to the present invention. In the figure, blade 10
is connected to the C frame 11 so as to be tiltable and angular. That is, the bracket 13 on which the center pin 12 of the blade 10 is disposed is connected to the center shaft 14 of the C frame 11, and the blade 10 is moved around the axis of the center pin 12 (angle direction).
and the direction around the axis of the center shaft 14 (tilt direction)
It is designed so that it can be rotated.

Two cylinders 15 and 16 are attached between the blade 10 and the frame 11 to angle and tilt the blade 10. As shown, the cylinders 15 and 16 are attached asymmetrically with respect to the attachment portion of the blade 10, and the cylinders 15 and 16 perform a combined operation to cause the blade 10 to angle and tilt.

Next, a preferred manner of mounting the cylinders 15, 16 will be explained in detail.

First, before explaining how the cylinders 15 and 16 are asymmetrically mounted, a case where two cylinders are mounted symmetrically will be described.

In this case, the relationship between the combination of the left and right cylinder lengths and the blade posture (defined by the angle angle and tilt angle) is as shown in FIG. 3(a). In the figure, each curve connects points showing the combination of left and right cylinder lengths when the tilt angle is sequentially changed while the angle is kept constant. Moreover, FIG. 3(b) is a partially enlarged view of FIG. 3(a). Note that a curve 1 indicated by a broken line indicates a change in the left and right cylinder lengths when the angle angle is changed when the tilt angle is Oo.

In Figure 3(b), the intersection P of the two curves m and n is
This shows that there are two blade postures for one combination of left and right cylinder lengths. in particular,
The first blade posture tilts to the right (moves in the direction of arrow B) at the angle angle in song I1m and reaches the intersection point P, and the angle angle at curve n that is angled to the right (in the direction of the arrow) from this angle angle. A second blade posture in which the blade tilts to the left (in the six directions of the arrow) and reaches the intersection point P exists in the same combination of cylinder lengths.

Therefore, there is a possibility that the blade may change from the first blade attitude to the second blade attitude or vice versa due to external force.

In addition, in order to change the blade posture, it is necessary to change the left and right cylinder lengths at a rate indicated by the slope of the tangent at that point from the point on the curve that indicates the current posture. ), the slope of the tangent line when tilting matches the slope of the tangent line when angulating, and the left and right cylinder lengths are changed at the rate indicated by the slope of this tangent line. In this case, it is not clear whether to angle or tilt.

Therefore, preferably the two cylinders are installed in such a manner that the above problems do not occur.

That is, the two cylinders are installed so that the combination of the lengths of the left and right cylinders and the blade posture as shown in the graph of FIG. 4 are obtained. Note that arrows A, B, and C in the same figure
, D are the same as the blade movement direction shown in FIG. 3(b).

Regarding the relationship between the blade operation and the expansion and contraction of the left and right cylinders shown in this graph, as shown in Table 1, the cylinder stroke changes are completely different for each of the four operations: left angle, right angle, left tilt, and right tilt.

Table 1 FIGS. 5 and 6 show the preferred mounting manner of the left and right cylinders 15, 16, respectively, in top and rear views of FIG. That is, according to this mounting mode,
As shown in Table 1, left cylinder 15 when left angle
is retracted, the right cylinder 16 is extended, and at the right angle, the left cylinder 15 is extended, and the right cylinder 16 is f! Retire,
(See FIG. 7). Also, when tilting to the left, both the left and right cylinders extend, and when tilting to the right, both left and right cylinders retract fa (see FIG. 8).

Next, a device for controlling the cylinder will be explained.

FIG. 1 is a block diagram showing an embodiment of a bulldozer blade control device according to the present invention.

In the same figure, the tilt lever 20 and the angle lever
22 commands the tilt angular velocity and angle angular velocity of the blade 10, respectively, and the tilt angular velocity signal generator 24 and the angle angular velocity signal generator 26 command the tilt angular velocity according to the lever operation amount of the tilt lever 20 and the angle lever 22, respectively. An analog signal indicating α and angle angular velocity Br is output to the A/D converter 28.

The tilt angle sensor 30 and the angle angle sensor 32 detect the tilt angle and angle angle of the blade 10, respectively, and are composed of, for example, potentiometers that detect the rotation angle of the center shaft 14 and center pin 12 of the blade 10 shown in FIG. be done. These tilt angle sensor 30 and angle angle sensor 32 output analog signals indicating the detected tilt angle α and angle angle β, respectively, to the A/D converter 28.

The A/D converter converts each of the four input analog signals into digital signals and performs central processing yf! Device (CPU) 3
Output to 4.

The CPU 34 receives input via the A/D converter 28.
'r Based on the four input data (α, β, α, β), calculate each cylinder control value for the two cylinders 15° and 16 so that the blade 10 has the specified tilt angle or angle angle. . Note that details of the operation of the CPU 34 will be described later.

Cylinder control values (flow rate command values to each cylinder) calculated by the CPU 34 are applied to the hydraulic pulp 42 via amplifiers 38 and 40. Hydraulic valves 42 and 44 are supplied with pressure oil from a hydraulic source (not shown) and are connected to amplifier 3.
The required flow ff1 (including the supply direction) of hydraulic oil is supplied to the cylinder 15.1 according to the flow rate command value input via 8.40.
Add to 6.

As a result, the cylinders 15, 16 each have a predetermined cylinder length, and the blade 10 is controlled to have the specified tilt angle or angle.

Next, the operation of the CPU 34 will be explained in detail with reference to the flowchart shown in FIG.

In FIG. 9, first, the current tilt angle α and angle angle β of the blade are input (step 100). next,
It is determined whether the tilt lever and the angle lever are both neutral (step 110). Note that this determination is made when the tilt angular velocity command 5r and the angle angular velocity command β are O.
It depends on whether or not.

When both the tilt lever and the angle lever are neutral, the tilt angle α and the angle angle β input in step 100 are respectively stored as initial values (9o, β0) (step 190).

On the other hand, if at least one of the tilt lever and the angle lever is operated, step 120
Proceed to and here calculate each cylinder length L 1 , L 2 of the current cylinder 15.16.

[R In this calculation, as described above, in the present invention, the left and right cylinders are provided so that the combination of the lengths of the left and right cylinders and the blade posture (tilt angle, angle angle) correspond one-to-one. Therefore, the left and right cylinder lengths are calculated from the tilt angle and angle angle.

FIG. 13 is a graph showing the tilt angle and angle angle determined by the left cylinder length and the right cylinder length. In the figure, point O indicates the left and right cylinder lengths when both the tilt angle and the angle angle are zero. When the relationship between the left and right cylinder lengths goes in the direction of the arrow, it will tilt to the left, if it goes in the direction of arrow B, it will tilt to the right, if it goes in the direction of arrow C, it will tilt to the left, and if it goes in the direction of the arrow, it will angle to the right.

These relationships are equivalent to those shown in FIG. 4 above.

In the present invention, a conversion table for determining the left and right cylinder lengths based on the tilt angle and the angle angle is stored in advance in the memory 36 (FIG. 1) from the relationship between the left and right cylinder lengths and the blade posture shown in FIG. 13 above. The left and right cylinder lengths determined by the tilt angle and angle angle are read out from this conversion table.

Next, the tilt angular velocity command: aゝ and the angle angular velocity command Br are input (step 130), and the target tilt angle α and target angle angle β1 are calculated from the following equation (step 140).

α1←α1+mi1・Δt (1) β −βr+, 3r・Δt “As shown in the above formula, each target angle is calculated by adding the angle increment instructed by the lever to each previous target angle. It is determined by adding. Note that Δt indicates the processing time of one cycle shown in this flowchart. Also, when determining the first target angle, the initial values (α, β) stored in step 190 are used. Use.

From each of the target angles (α, β1) obtained above, the target cylinder length (
L, r, Rr) (step 150).

Next, set the target cylinder length (LL', R') Deviation Δo from the current cylinder length (L, L).

[R Δ1R is the following formula, Δj [=1.　’　　−L[ ・・・・・・(2) [ ΔJIR=LR-LR Step 160), this deviation Δj[.

Flow rate command value V1. to the left and right cylinders required to quickly bring Δ, IlR to zero. V1 is obtained from the following formula % formula % [ (step 170). In addition, in the above formula,
A.8. C is each coefficient of proportional, differential, and integral compensation elements.

Flow rate command value V4. thus obtained. vR is output from the CPU 34 as described above (step 180)
. Steps 100 to 180 are then repeated until both the tilt and angle levers are in neutral, resulting in the blade tilting or angulating at each speed instructed by the levers.

Next, we will explain how to handle cases where the cylinder is overloaded or reaches the end of its stroke, the hydraulic circuit that supplies pressure oil to the cylinder is relieved, and the left and right cylinders do not move as instructed.

When a command to change only the tilt angle of the blade is given, if the left and right cylinders do not move as instructed, the angle angle changes from its initial value. Similarly, when a command is given to change only the angle of the blade, if the left and right cylinders do not move as instructed, the tilt angle changes from its initial value.

The process shown below corrects the blade posture when the blade posture error (tilt or angle) becomes larger than a certain value after the blade is controlled by the lever operation described above, and adjusts the tilt angle or angle to the initial position. I'm trying to change it back to .

FIG. 10 is a flowchart for executing the above processing. Note that the same processes as those shown in FIG. 9 (parts surrounded by dashed-dotted lines, etc.) are given the same reference numerals, and their explanations will be omitted.

In the same figure, F is first set to 1 (step 20
0). This flag F is a flag indicating whether it is "1" before the start of blade control by lever operation or 110 II after the control ends.

If the tilt lever and the angle lever are both neutral in step 110, the process proceeds to step 205;
Here, it is determined whether F=1.

In the case of F=1, since the blade control has not yet started, the current tilt angle α and angle angle β are set to the initial values (α., β.).
(step 190).

Now, a case will be described in which the blade attitude is changed by operating either the tilt lever or the angle lever.

In this case, in step 180, an Fffi command [(V4.V, >) is output to the left and right cylinders in response to the lever operation, and then the process proceeds to step 210, where it is determined whether the tilt lever has been operated.

Then, if the tilt lever is operated, 1 is applied to T.
(step 215), and if the angle lever is being operated, set it to A (step 220).
).

Subsequently, O is set in F (step 225), and the process returns to step 100. In this way, the blade attitude control is performed, and after that, both the tilt lever and the angle lever become neutral and the control is completed, step 205
Proceed to.

In step 205, since the blade control is completed (F=O), the process proceeds to step 230, where the tilt lever is operated (T=1>) or the angle lever is operated (
A determination is made as to whether A=1). The initial value β of the angle when the tilt lever is operated. step 235), and this initial value β. The absolute value of the deviation between the angle and the current angle β is determined, and it is determined whether or not this absolute value is within the allowable error ε (step 240). Similarly, when the angle lever is operated, the initial value α of the tilt angle. step 245), and this initial value α. and the current tilt angle, and this absolute value is the allowable error ε
It is determined whether or not the value is within the range (step 250).

In steps 240 and 250, if 1β-βo1≦ε or 1α-αo1≦ε, the blade attitude is not corrected, and if 1β-β1>ε or α-αoI>ε, the process proceeds to step 255.

In step 255, if the tilt lever is operated, the current tilt angle α and the initial value β of the angle angle are determined. Find the target cylinder length (L r, LR') based on
When the angle lever is operated, the current angle angle β and the initial value α of the tilt angle. The target cylinder length (L, ', L
R') is determined and the process proceeds to step 160.

In this way, an unexpected change in the posture of the blade is corrected by returning the angle, which should not normally change, to its initial value.

Next, another processing method when the left and right cylinders do not move as instructed will be described.

This processing method detects the speed of the left and right cylinders, and when it is determined that either cylinder is almost at a standstill, blade control is prohibited to prevent unplanned changes in blade posture. .

FIG. 11 is a flowchart for executing the above processing. Note that the same processes as those shown in FIG. 9 (portions surrounded by a dashed line) are given the same reference numerals, and their explanations will be omitted.

In the figure, initial left and right cylinder lengths (L, L) are calculated based on the initial values (α0.β0) of the blade posture stored in step 190 [OR0 (step 300).

Now, based on the operation of the tilt lever or angle lever, the flow rate command value (V,) is sent to the left and right cylinders.

VR) is output (Step 180), first, the absolute value of the deviation between the previous left cylinder length 'LT and the current left cylinder length L1 is taken, and it is determined whether this absolute value is within the allowable value ε. step 310).

If l L, ■-LL+≦ε, proceed to step 320; if l L[■-L, l >ε, proceed to step 3
Proceed to 30. In steps 320 and 330, the absolute value of the deviation between the previous right cylinder length LrI□ and the current cloth cylinder length R is again determined, and it is determined whether this absolute value is within the allowable value ε. In step 320, when ILR-LR1≦ε, the process advances to step 340, and when ILR,-LRl>ε, the control is stopped. Also, in step 330, l LRl
When −LR1≦ε, the control is stopped, l L,, −LRl
>ε, the process proceeds to step 340.

In step 340, the current left and right cylinder lengths (L, L)
(LL) and return to step 100. Note that the initial LL [■・RT is the initial cylinder length (calculated in step 300).
L, L) is used. Also, since one cycle of processing in this Flow 10 RO chart is repeatedly executed in a fixed period of time, the absolute value obtained in steps 310, 320 and 330 is the absolute value of the change in cylinder length per cycle time, that is, the cylinder speed. indicates the absolute value of The allowable value ε corresponds to a value at which the cylinder speed becomes approximately O.

That is, in steps 310, 320, and 330, it is determined that one of the expansion and contraction speeds of the left and right cylinders reaches approximately 0, and in this case, blade control is prohibited. This is because, as shown in the graph of Figure 13, when the blade is tilted or angle controlled, the left and right cylinders are always controlled simultaneously, and as mentioned above, during blade control, one of the cylinders is This is because if the cylinder is almost stopped, it is considered that the cylinder is overloaded and the pressure oil is relieved.

In this way, an unexpected change in the posture of the blade is prevented.

Next, another processing method when the left and right cylinders do not move as instructed will be described.

This processing method detects the speed of the left and right cylinders, and when it is determined that both cylinders have almost stopped, prohibits blade control by lever operation and returns the blade posture to its initial state. It is something to do.

FIG. 12 is a flowchart for executing the above processing. Note that the same processes as those shown in FIG. 9 (portions surrounded by a dashed line) are given the same reference numerals, and their explanations will be omitted.

In the figure, the initial left and right cylinder lengths (LL) are calculated based on the initial values (α, β) of the blade postures stored in step 190 [0·RO (step 400).

Now, when the flow rate command value (V[, VR) to the left and right cylinders is output based on the tilt lever or angle operation (step 180), the left and right cylinders are controlled in the same way as the process shown in FIG. 11 above. The speed is determined and it is determined whether the speed is close to zero.

That is, in step 405, the previous left cylinder length L
The absolute value of the deviation between 1□ and the current left cylinder length is taken, and it is determined whether this absolute value is within the allowable value ε.

IL[■-L[If l≦ε, proceed to step 410; if l L[, -L, l>ε, step 415
Proceed to. In step 410, the absolute value of the deviation between the previous right cylinder length R□ and the current right cylinder length 11 is again determined, and it is determined whether this absolute value is within the allowable value ε. Then, if l LR, -LR1≦ε, step 420
If l LRl−LRl >ε, the process advances to step 415.

Step 415 rewrites the current left and right cylinder lengths (L, L) to (LL), and returns to step 100.

On the other hand, when it is determined that both the expansion and contraction speeds of the left and right cylinders are close to O and the process proceeds to step 420, the blade attitude is returned to the initial state by performing the processes of steps 420 to 445.

That is, in step 420, a deviation (Δ1.

Δ, IIR) respectively.

Then, the absolute value of these deviations is 1ΔJLl.

It is determined whether or not both 1ΔJR1 are within the tolerance value ε near 0 (step 425), and if they are within the tolerance value ε, it is determined that the blade posture has returned to the initial state and the process is stopped.

On the other hand, if it is not within the tolerance value ε, step 4
Based on the deviations Δ1 and ΔJn obtained in step 20, the flow rate command values for the left and right cylinders are calculated (step 430). Note that this flow rate command value is measured in step 1.
This is done in the same manner as in 70.

In step 435, the above-determined F'1 command value ■[.

VR is output, and in step 440, the tilt angle α and angle angle β of the blade controlled by the above command values are input. Then, the current left and right cylinder lengths (L, L) are calculated using the input tilt angle α and angle angle β (step 445), and the process returns to step 420 to calculate the deviation from the initial value again.

Note that the method of giving the target tilt angle and the target angle angle of the blade is not limited to this embodiment, and the target tilt angle and the target angle angle may be given directly by, for example, a dial or the like. Further, the actual measurement of the cylinder length is not limited to the present embodiment in which the measurement is performed based on the tilt angle and the angle angle of the blade, and the cylinder length may be directly measured.

Furthermore, the expansion and contraction speed of the cylinder can also be determined by measuring the amount of oil per unit time that flows into and out of the cylinder.

Furthermore, the method is not limited to the method of determining the flow rate command value for the left and right cylinders based on the deviation between the target cylinder length and the actual cylinder length.
The flow rate ratios to the left and right cylinders required for right and left angles are prepared in advance in a memory table, and the desired flow rate ratios are calculated from the memory table based on the current blade posture and the tilt or angle operation command for the blade. Alternatively, the flow rate command values for the left and right cylinders may be determined so as to match the read flow rate ratio.

〔Effect of the invention〕

As explained above, according to the present invention, since there are two cylinders for tilting and angulating the blade, it is possible to use M4 construction, and the above-mentioned two cylinders can be used to tilt and angle the blade. The book cylinder can be controlled in multiple ways.

In addition, if the blade changes its posture in an unplanned manner due to a load applied to the blade, etc., appropriate measures can be taken, thereby further improving the controllability of the blade. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a bulldozer blade controlling device according to the present invention, and FIG. 2 is a block diagram showing an embodiment of a bulldozer blade a4! according to the present invention. FIG. 3(a) is a graph showing the relationship between the combination of the left and right cylinder lengths and the blade posture when the cylinders are installed symmetrically, and FIG. 3(b) is a perspective view showing one embodiment of I. A partially enlarged view of figure (a),
Figures 4 and 13 are graphs showing the preferred relationship between the combination of left and right cylinder lengths and the blade posture, Figures 5 and 6 are the top and rear views of Figure 2, respectively, and Figures 7 and 8. 9 to 12 are flowcharts showing the processing procedure of the CPU shown in FIG. 1 according to the present invention, and FIG. 14 is a conventional diagram FIG. 2 is an exploded perspective view showing an example of blade twisting. 10...Blade, 11...C frame, 12...
・Senta Bin, 14...Senta Shirt Small, 15.16
...Cylinder, 20...Tilt lever, 22...
Angle lever, 30...Tilt angle sensor, 32...
・Angle angle sensor, 34...Central processing bag @ (CPU
), 36...memory, 42.44...hydraulic pulp. Fig. 2 (0) (b) Fig. 3 Fig. 4 Fig. 9 @ = 1-] Cylinder) (mm) 5゜ Fig. 14

Claims (6)

[Claims] (1) A first blade disposed between a C frame and a blade connected to the C frame so as to be tiltable and angular.
, a second cylinder, the first and second cylinders arranged in such a manner that the tilt angle and angle angle of the blade are uniquely determined by the combination of the lengths of these cylinders; and the target of the blade. an instruction means for respectively instructing a tilt angle and a target angle angle; and an instruction means for instructing the first and second cylinders necessary to make the blade reach the target tilt angle and the target angle angle based on the target tilt angle and the target angle angle. means for converting respective target cylinder lengths; detection means for detecting respective cylinder lengths of the first and second cylinders; and the converted target cylinder length of the first cylinder and the detected first cylinder length. a first cylinder control means that controls the first cylinder to have the target cylinder length based on the detected cylinder length of the second cylinder; A bulldozer blade control device comprising: second cylinder control means for controlling the second cylinder to have the target cylinder length based on the detected cylinder length of the cylinder. (2) The means for converting the target cylinder length includes a storage means for storing each cylinder length of the first and second cylinders determined by the tilt angle and the angle angle, and a means for converting the target cylinder length based on the target tilt angle and the target angle angle. A bulldozer blade control device according to claim 1, further comprising reading means for reading each cylinder length of the corresponding first and second cylinders from the storage means. (3) The detection means for detecting the cylinder length includes an angle detection means for detecting the tilt angle and the angle angle of the blade, and the first and the first cylinder lengths based on the tilt angle and the angle angle detected by the angle detection means. 2. A bulldozer blade control device according to claim 1, comprising means for converting each cylinder length of two cylinders. (4) A mode in which the blade is connected to the C frame so as to be tiltable and angular, and the tilt angle and angle of the blade are uniquely determined by the combination of the lengths of the respective cylinders between the blade and the C frame. A method for controlling a bulldozer blade in which first and second cylinders are arranged and the first and second cylinders are jointly controlled based on a target tilt angle and an angle angle, wherein: before the blade is controlled; detecting a tilt angle and an angle angle, storing these as initial values, and instructing a target angle for either one of the tilt angle and the angle angle of the blade; After completing the combined control of the cylinder, detect the other angle that was not instructed, take the deviation between the detected other angle and the initial value of the other angle, and do not change the current angle of the one angle. A bulldozer blade control method, characterized in that the first and second cylinders are further controlled in a combined manner so that the deviation falls within an allowable range, thereby correcting an unplanned attitude change of the blade. (5) A mode in which the blade is connected to the C frame so that it can tilt and angle freely, and the tilt angle and angle of the blade are uniquely determined by the combination of the length of each cylinder between the blade and the C frame. First,
A method for controlling a blade of a bulldozer, in which a second cylinder is arranged and the first and second cylinders are jointly controlled based on a target tilt angle and an angle angle, at least among the tilt angle and the angle angle of the blade. one target angle is instructed, and during the combined control of the first and second cylinders according to the instruction of the target angle, at least one of the expansion and contraction speeds of the first and second cylinders is below a certain allowable minimum speed; If it is determined that at least one of the expansion and contraction speeds of the first and second cylinders has become below a certain allowable minimum speed, the first and second cylinders 1. A method for controlling a bulldozer blade, characterized in that control is prohibited to prevent an unexpected change in attitude of the blade. (6) A mode in which the blade is connected to the C frame so as to be tiltable and angular, and the tilt angle and angle of the blade are uniquely determined by the combination of the lengths of the respective cylinders between the blade and the C frame. In a method for controlling a bulldozer blade, which includes a first cylinder and a second cylinder, and performs combined control of the first and second cylinders based on a target tilt angle and an angle angle, before the blade is controlled. detecting a tilt angle and an angle angle of the blade, storing the detected values as initial values, and instructing a target angle of at least one of the tilt angle and the angle angle of the blade; During the combined control of the cylinder, it is determined whether the expansion and contraction speeds of the first and second cylinders are both below a certain allowable minimum speed; When it is determined that the speed has fallen below the allowable minimum speed, control of the first and second cylinders based on the target angle instruction is prohibited, and then the first and second cylinders are controlled using the stored initial value as the target angle.
A method for controlling a bulldozer blade, characterized in that a second cylinder is controlled in a combined manner to return the blade to an initial blade posture.