JPH0480168B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an excavation trajectory control device for a pump-controlled hydraulic excavator, and more particularly to a device for controlling the motion trajectory of a bucket cutting edge.

[Background of the invention]

A hydraulic excavator generally includes a boom installed on a revolving structure, a boom cylinder that raises and raises the boom, and a boom cylinder that raises and lowers the boom.
The boom includes an arm attached to the tip of the boom, an arm cylinder for swinging the arm, a bucket attached to the tip of the arm, and a bucket cylinder for swinging the bucket. Usually, each cylinder is operated by an operating lever located at the driver's seat.

When performing simple excavation work using the bucket of this hydraulic excavator, it is sufficient to operate each hydraulic cylinder in sequence by operating each lever, but it is not necessary to perform simple excavation work using the bucket of this hydraulic excavator. ,
When moving the bucket cutting edge along a fixed straight line, levers corresponding to a plurality of cylinders must be operated at the same time, which not only requires a considerable amount of kneading but also reduces work efficiency.

In order to solve this problem, various measures have been proposed to automate the straight-line movement operation of the bucket cutting edge of a hydraulic excavator, so-called straight-line excavation. One such solution is described in Japanese Patent Publication No. 54-37406. This linear excavation control device controls the movement locus of the tip of the arm to follow a desired straight line, and also controls the attitude of the bucket to maintain a constant value with respect to fixed coordinates (surface to be excavated).
This control method can always maintain a bucket position at the cutting edge angle with good excavation efficiency in relation to the surface to be excavated.
This can increase excavation efficiency, but on the other hand, the relative angle of the bucket to the arm must be changed as digging progresses, so when the bucket gets close to the vehicle body, the bucket cylinder will reach the end of its stroke, and the straight line The disadvantage is that the area that can be excavated is narrowed. Furthermore, if the bucket angle is changed by manual priority control during straight-line excavation, there is a drawback that the excavation trajectory will deviate significantly from the desired straight line.

[Purpose of the invention]

The present invention controls each cylinder of the boom and arm so that the trajectory of the tip of the bucket of a hydraulic excavator does not deviate from the desired linear trajectory even if the posture of the bucket is arbitrarily changed by manual operation during automatic linear excavation. It is an object of the present invention to provide a linear excavation control device for a hydraulic excavator that can widen the range of linear excavation.

[Summary of the invention]

The excavation trajectory control bottom plate of the present invention allows the bucket position of the hydraulic excavator to be changed according to the operator's will even during straight excavation operation, and also detects changes in the bucket position to control the boom, arm, etc. , and controls the movement of the tip of the bucket so that it follows a desired straight line regardless of the bucket posture.

[Embodiments of the invention]

FIG. 1 shows a front mechanism of a hydraulic excavator equipped with an example of the control device of the present invention.
3 is an arm attached to the tip of the boom 2, and 4 is a bucket attached to the tip of the arm 3. These boom 2, arm 3
and bucket 4 are respectively boom cylinders C ₁ ,
It is operated by an arm cylinder C ₂ and a bucket cylinder C ₃ . These boom 2, arm 3
The relative angle of the bucket 4 is detected by detectors 5 to 7 provided at or near each pivot point.
The detection values of the detectors 5 to 7 are transmitted to the input side by a detection circuit 8. An input device 9 is installed in the driver's seat (not shown) of the hydraulic excavator. The input device 9 includes dials for setting the slope of the excavated surface W, operating levers for setting the excavation speed, and operating levers for operating the hydraulic excavator in a conventional manner. The excavation speed is decomposed by the input device 9 into a horizontal component v _x and a vertical component v _y according to the slope of the excavation surface, and the signal is sent to the arithmetic device 10 .

The calculation device 10 calculates the velocity components v _x , v _y of the bucket tip.
Since the bucket tip (x, y) passes through the desired excavation trajectory, that is, the excavation start point (x ₀ , y ₀ ), and moves along the straight line expressed by the angle φ set with the excavation angle setting dial. Calculate the operating speed of boom cylinder C ₁ and arm cylinder C ₂ required for do. For example, if the pump is an axial piston type variable displacement swash plate pump, the pump discharge amount command value is calculated as the pump swash plate tilt position command value. This discharge amount command signal is sent to the pump control device 11. Furthermore, since the present invention is characterized in that the bucket 4 can be operated in a normal manner, the flow rate to be supplied to the bucket cylinder C ₃ is determined independently of the excavation trajectory, and the flow rate necessary to realize this is determined independently of the excavation trajectory. A pump discharge amount command signal is sent to the pump control device 11.

The pump control device 11 controls each hydraulic pump 1
Discharge amount detectors 2, 13, and 14, for example, if the pump is the swash plate pump, the swash plate tilt position detector 1
5, 16, and 17 and the pump's discharge amount command signal, and if there is an error between the two, each pump 1 is adjusted to reduce the error.
2 to 14 are controlled. Hydraulic pump 12~
The 14 discharged pressure oils are directly connected to each cylinder.
Guided by C ₁ to C ₃ . As a result, the tip of the bucket belt 4 of the hydraulic excavator moves along a desired linear trajectory. In the hydraulic circuit shown in Figure 1, the hydraulic pump and single-rod hydraulic cylinder are shown directly connected for simplicity, but in an actual hydraulic circuit, the pump discharge flow rate and suction flow that occur as the hydraulic cylinder expands and contracts. It is equipped with hydraulic equipment such as a charge pump and flushing valve to compensate for excess or deficiency in flow rate.

The arithmetic and control unit 10 shown in FIG. 1 will be explained in more detail.

FIG. 2 is a functional block diagram of the arithmetic and control unit 10. The arithmetic and control device 10 is composed of a bucket tip speed calculation block 15, an angular velocity calculation block 16, a servo control block 17, and a pump flow rate conversion block 18. In the bucket tip speed calculation block 15, the speed input lever 1 of the input device 9
Connection speed signal from 9 v _t and angle setting dial 20
This is a part that calculates the velocity components v _x and v _y of the tip of the bucket from the excavation angle signal φ from the excavation angle signal φ, and the input/output relationship in this calculation block 15 can be expressed as follows. That is, v _x = v _t cosφ (1) v _y = v _t sinφ (2) The angular angular velocity calculation block 16 calculates the bucket tip velocity components v _x and v _y which are the outputs of the bucket tip velocity calculation block 15 and the bucket tip of the input device 9 The relative angular velocities of the boom 2, arm 3, and bucket 4 are determined based on the bucket angular velocity command value γ〓 _r from the operating lever 21 and the relative angle signals β, α, and γ of the boom 2, arm 3, and bucket 4 from the detection circuit 8. Command signal β〓 _r ,
α〓 _r and γ〓 _r and relative angles β _r , α _r , γ _r are calculated and output.

In order to carry out this calculation, the angles and lengths of each part of the hydraulic excavator are determined as follows based on FIG. An X, Y coordinate system is constructed in the horizontal and vertical directions with the boom foot pin position O as the coordinate origin. The pivot point of arm 3 relative to boom 2 is A,
Let B be the rotation fulcrum of the bucket 4 relative to the arm 3, and P be _the tip _of the bucket _. After determining the height, the X and Y coordinate values (X _p , Y _p ) of the bucket tip P are as follows (1), (2)
It is expressed as follows.

X _p =L _b ×cosβ+L _a ×sin (α+β) −L _d ×cos (α+β+γ) …(1) Y _p =L _b ×sinβ−L _a ×cos (α+β) −L _d ×sin (α+β+γ) … ...(2) By differentiating these equations (1) and (2), the velocity components v _x and v _y in the X and Y directions at the bucket tip P can be expressed as the following equations (3) and (4). Ru.

v _x = {−L _b ×sinβ+L _a ×cos (α+β) +L _d ×sin (α+β+γ)}×β〓 +{L _a ×cos (α+β) +L _d ×sin (α+β+γ)}×α〓 +L _d ×sin (α+β+γ)×γ〓 ……(3) v _y = {L _b ×cosβ+L _a ×sin (α+β) −L _d ×cos (α+β+γ)}×β〓 +{L _a ×sin (α+β) −L _d × cos (α+β+γ)}×α〓 −L _d ×cos(α+β+γ)×γ〓 ……(4) Also, from equations (3) and (4) above, the angular velocity β of boom 2
and the angular velocity α of arm 3 can be expressed as shown in equations (5) and (6) below.

β〓=[−v _x ×{L _a ×sin (α+β) −L _d ×cos (α+β+γ)} ＋v _y ×{L _a ×cos (α+β) +L _d ×sin (α+β+γ)} +γ〓×L _a × L _d ×cosγ] / [L _b ×{L _a ×cosα +L _d ×sin (α+γ)}] …(5) α〓=[v _x ×{L _b ×cosβ +L _a ×sin (α+β) −L _d ×cos (α+β+γ)} −v _y ×{−L _b ×sinβ +L _a ×cos (α+β) +L _d ×sin (α+β+γ)} −γ〓×L _d ×{L _a ×cosγ +L _b ×sin (α+γ )}] /[L _b ×{L _a ×cosα +L _d ×sin (α+γ)}] ...(6) Also, the relationship between the angular velocities α〓, β〓, γ〓 and the angles α, β, γ is expressed as Assuming that t is the initial value of the angles α, β, and γ (values at the start of automatic operation) are α ₀ , β ₀ , and γ ₀ , then α(t)=∠ ^t 〓 α〓dt＋α ₀ …… (7) β(t)=∠ ^t 〓 β〓dt+β ₀ ...(8) γ(t)=∠ ^t 〓 γ〓dt+γ ₀ ...(9).

FIG. 4 is a block diagram representing the calculations of equations (5) to (9).

Target angular velocities β〓 _{r , α〓 r , γ〓 r of the boom 2, arm 3 and bucket 4 of the hydraulic excavator are calculated using the outputs γ〓 r ,} v _x , v _y of the input device 9 and the bucket tip speed calculation block ₁₅ as _inputs . It also calculates and outputs target angles β _r , α _r and γ _r . In Figure 4,
AD is an addition block, MU is a multiplication block,
DI is a division block, IN is an integration block, SI is a sine function block, CO is a cosine function block,
K represents a coefficient block.

Next, the servo control block 17 will be explained in detail. FIG. 5 is a block diagram showing the processing in the servo control block 17. The symbols in the figure are the same as in FIG. 4, where AD represents an adder and K represents a coefficient unit. That is, to explain the arm system, the arm angle command value _α〓r , which is the output of the angular velocity calculation block 16, is compared with the actual arm angle α, the difference is taken, and the coefficient K〓 is added to the value ε〓. The multiplied result is added to the arm angular velocity command value α _r which is the output of the angular velocity calculation block 16, and a new arm angular velocity command value α is output. Similar processing is performed for the boom system and the bucket system, and the boom angular velocity command value β〓 and the bucket angular velocity command value γ〓 are output.

Next, regarding the pump flow rate conversion block 18, the sixth
This will be explained using figures. 21-23 in Figure 6
is a function generator which inputs the angle signals α, β, and γ of each member of the shovel and outputs the ratio between the cylinder velocity and the angular velocity of each member. That is, when arm angle α is input to the function generator 21, the ratio of cylinder speed Z〓 ₂ and arm angular velocity α〓 to that α is output. By multiplying this Z〓 ₂ /α〓 by α〓, the arm cylinder speed Z〓 ₂ at that time can be obtained. Boom cylinder speed Z〓 ₁ and bucket cylinder speed Z ₃ are obtained in the same way. Hydraulic cylinder to these cylinder speeds
Multiplying the pressure receiving areas of C ₁ , C ₂ , and C ₃ gives the hydraulic pump 1
2, 13, 14 flow rates to be discharged are obtained,
Since the hydraulic cylinder used in a hydraulic excavator is a single-rod cylinder, the problem is whether to select the area on the head side or the area on the rod side as the pressure receiving area of the hydraulic cylinder. Since the pump control system for the hydraulic excavator has been described as an example, a method for determining the effective pressure receiving area of the hydraulic cylinder based on the position of the flushing valve provided in the hydraulic closed circuit will be described.

Figure 7 shows arm cylinder C ₂ and hydraulic pump 13.
It is a circuit diagram of a hydraulic circuit including. This circuit includes a charge pump 2 to compensate for the shortage of pressure oil in the circuit that occurs when the single rod cylinder C ₂ is pushed out, and for the leakage that flows out from the hydraulic closed circuit.
4. Flushing valve 2 for returning excess pressure oil generated when the hydraulic cylinder is drawn into the tank
5, low pressure relief valve 26, check valve 27, 28
etc. are provided.

The flushing valve 25 connects the lower circuit of either the rod side or the head side of the hydraulic cylinder _C2 to the low pressure relief valve. Therefore, the hydraulic cylinder
The moving speed of C ₂ is the discharge flow rate of the hydraulic pump 13,
This is the value divided by the pressure receiving area on the high pressure side, either the head side or the rod side.

Now put the limit switch 2 on the flushing valve 25.
9 is provided so that the signal S〓 is output when the pressure on the head side is high, that is, when the flushing valve is in state I. In this state, the effective pressure receiving area of the hydraulic cylinder C ₂ is the area A ₁ 〓 on the head side, and when this is not the case, that is, when the signal S 〓 is not output, the effective pressure receiving area of the hydraulic cylinder C ₂ is the pressure receiving area A ₂ on the rod side. 〓 becomes.

The right side of FIG. 6 is a block for determining the flow rate q to be discharged by the hydraulic pump using this principle. That is, the signal from the limit switch,
By S〓, S〓, S〓, hydraulic cylinder speed Z〓 ₂ , Z〓 ₁
，
The configuration is such that the correct discharge flow rate can be obtained by switching the coefficient multiplier corresponding to the area to be multiplied by Z= ₁ .

In this way, the flow rate command signals q〓, q〓, q〓 obtained by the arithmetic and control device 10 are sent to the pump control device 11, respectively.

The pump control device 11 controls the tilting position of the swash plate of each pump so that each pump 12, 13, 14 discharges a flow rate corresponding to this flow rate command signal.

When the linear excavation control device for a hydraulic excavator is configured in this way, the tip of the bucket of the hydraulic excavator moves on a straight line trajectory with an inclination φ at a speed given by the operation laser 19 of the input device 9, and The attitude angle γ of No. 4 can be operated at any time using the bucket operation lever 21 of the input device 9. Even if the attitude angle γ of the bucket cart 4 is arbitrarily changed, the tip of the bucket cart 4 will not deviate from the desired linear trajectory.

In the above description, the contents of the arithmetic and control device 10 have been explained in analog terms for ease of understanding; however, the present invention may be implemented even if the arithmetic and control device 10 is configured by digital means such as a microcomputer. This does not deviate from the main idea.

In addition, in the description of the embodiment, a variable discharge amount pump was used as a flow rate control means for supplying to a hydraulic cylinder, but the control device of the present invention uses a hydraulic control valve (servo valve).
Needless to say, it can also be configured using .

〔Effect of the invention〕

As described above, according to the present invention, it is possible to change the attitude of the bucket at any time during the process of automatic linear excavation, and even if the attitude of the bucket is changed, the movement trajectory of the tip of the bucket does not deviate from the desired linear trajectory. do not have. Therefore, the stroke of straight-line excavation can be made longer, the operability of the hydraulic excavator is improved, and the work efficiency of straight-line excavation is significantly improved.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of a hydraulic circuit of a hydraulic excavator equipped with an example of the control device of the present invention, Fig. 2 is a functional block diagram of the arithmetic and control device used in the present invention, and Fig. 3 is the geometry of the hydraulic excavator. FIG. 4 is a block diagram showing the execution processing contents of the angular velocity calculation block constituting the present invention;
Fig. 5 is a block diagram showing the execution processing contents of the servo control block constituting the present invention, Fig. 6 is a block diagram showing the execution processing contents of the flow rate conversion block constituting the present invention, and Fig. 7 is a block diagram showing the execution processing contents of the flow rate conversion block constituting the present invention. FIG. 2 is a circuit configuration diagram of a hydraulic closed circuit including: FIG. 1...Swivel body, 2...Boom, 3...Arm,
4... Bucket, 5-7... Detector, 8... Detection circuit, 9... Input device, 10... Arithmetic control device,
11...Pump control device, 12-14...Hydraulic pump, _C1 ...Boom cylinder, _C2 ...Arm cylinder, _C3 ...Bucket cylinder, 21...Bucket angular velocity command value input means (bucket operation lever) ).

Claims (1)

[Claims] 1. Conditions such as the slope of the excavation surface and the excavation speed are given by input means, and the boom, arm, and bucket, which are the components of the front mechanism of the hydraulic excavator, are operated under these conditions. Bucket angular velocity command that manually changes the posture of the bucket in a device that sequentially calculates the amount of operation of a hydraulic cylinder and uses the calculation results as an input signal to control the movement of each member and move the cutting edge of the bucket on a desired linear trajectory. A boom, an arm, and a boom, an arm, which prevents the tip of the bucket from deviating from a desired linear trajectory, based on the value input means, the bucket angular velocity command value, the slope of the excavation surface, the excavation speed, and the detected relative angle of the boom, arm, and bucket.
1. A linear excavation control device for a hydraulic excavator, comprising a calculation control means for calculating the flow rate of pressure oil to each hydraulic cylinder of a bucket. 2. The calculation control means includes a calculation unit that calculates the bucket tip speed based on the slope of the excavation surface and the excavation speed from the input device, and a bucket tip speed from the calculation unit and the bucket angular velocity command value from the bucket angular velocity command input means. and a calculation unit that calculates target angles and target angular velocities of the boom, arm, and bucket based on detected values of relative angles of the boom, arm, and bucket; and each target angle, each target speed, and each relative angle from this calculation unit. boom, arm,
The servo control unit calculates each actual angular velocity command value of the bucket, and calculates the ratio of the preset speed of each cylinder to the relative angular velocity with respect to each relative angle input signal of the boom, arm, and bucket, and calculates the ratio of the relative angular velocity to this ratio. a calculation unit that calculates the boom cylinder speed, arm cylinder speed, and bucket cylinder speed by multiplying each angular velocity command value, and calculates the flow rate of pressure oil to each cylinder by multiplying each cylinder speed by the pressure receiving area of each hydraulic cylinder. A linear excavation control device for a hydraulic excavator according to claim 1.