JPH05295753A - Automatic control method for construction machine - Google Patents

Abstract

PURPOSE:To heighten the excavating accuracy by allowing a controller to sink the objective value of excavation moment to its specified level in conformity to the signal given by a bucket attitude sensing means when the foremost part of the bucket approaches the objective depth of excavation. CONSTITUTION:From time to time, a controller 37 calculates the coordinations for the position of the bucket foremost part while automatic excavation is conducted by a hydraulic shovel. When the bucket foremost is reaching the objective depth, an appropriate depth signal is fed to the controller 37. In conformity to the depth signal, controller 7 performs the depressing process for the objective value of excavation moment entered in advance in the controller 7. When the value of moment attains the specified value, the controller 7 gives a boom-up command signal to a solenoid-operated proportional decompression valve 30. The pilot secondary pressure led from this decompression valve 30 is applied to a boom pilot selector valve 20 through a shuttle valve 24 to cause a boom cylinder 8 to elongate, which lifts a boom 4 to limit the depth of excavation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for an automatic excavation operation of a construction machine such as a hydraulic excavator or a work vehicle.

[0002]

2. Description of the Related Art FIG. 4 is a side view showing a backhoe type hydraulic excavator. In the figure, 1 is an upper revolving structure,
2 is a lower traveling body, 3 is a work attachment mounted on the front part of the upper swing body 1, 4 is a boom, 5 is an arm, 6
Is a bucket, 7 is a bucket link, 8 is a boom cylinder, 9 is an arm cylinder, 10 is a bucket cylinder, 1
Reference numeral 1 is a boom angle sensor (constituting a bucket attitude detecting means) that detects a rotation angle of the boom 4 with respect to the main body of the upper swing body 1, and 12 is an arm angle sensor (bucket attitude detecting means) that detects a rotation angle of the arm 5 with respect to the boom 4. , 13 is a bucket angle sensor that detects the rotation angle of the bucket 6 with respect to the arm 5 (constitutes a bucket attitude detection means), and 14 is a cylinder pressure sensor that detects the cylinder pressure of the bottom side oil chamber of the bucket cylinder 10 (excavation). Action force detecting means), 15 is a controller equipped inside the upper swing body 1, 0 is a boom base end pin which is the rotation center of the boom 4, A is an arm base end pin, and B is a bucket base end. Pins and C are tips of buckets.

FIG. 5 is a side view of the hydraulic excavator in FIG. 4 viewed from the opposite side. In the figure, the length of each part is determined as follows. OS = L0, OA = L1, A
B = L2, BC = L3, AH = u, OA, AH,
The angles that BC makes with the horizontal line (HL) are a1 and a2, respectively.
, A3.

In the hydraulic excavator shown in FIGS. 4 and 5,
A work attachment 3 in which a boom 4, an arm 5, and a bucket 6 are sequentially connected to each other so as to be rotatable in the front-rear direction is attached to the front portion of the upper turning pair 1, and a boom angle sensor 11 and an arm angle sensor that are bucket attitude detecting means. 1
2. A bucket angle sensor 13 and a cylinder pressure sensor 14, which is an excavation force detection means, are provided, and the controller 15 performs arithmetic processing based on output signals from these detection means to perform bucket rotation drive and bucket up / down drive. The excavation moment of the bucket 6 is used as a parameter for automatic excavation. The value of the excavation moment is calculated based on the acting force F on the bucket cylinder 10 and the distance l from the bucket base end pin B to the bucket link 7. Also, the excavation depth h from the ground (GL) (see FIG. 5) is a fixed dimension specification L0,
L1, L2, L3 and varying angles a1, a2, a3,
And the coordinates of the bucket tip C (x,
It is read by calculating y).

[0005]

In a hydraulic excavator in which automatic excavation control is performed using the excavation moment of a bucket as a parameter, when the excavation moment is large due to the target soil condition, boom raising adjustment is automatically performed to make it shallow. (The depth hN shown in FIG. 4) is excavated, and conversely, when the excavation moment is small, it can be deeply excavated (the depth hP shown in FIG. 4), so it was difficult to limit the required target excavation depth hS. .. It is an object of the present invention to provide an automatic control method that can solve the above problems.

[0006]

According to an automatic control method for a construction machine of the present invention, in an automatic excavation control device for performing automatic excavation using a bucket excavation moment as a parameter, a target excavation moment value and a target excavation depth are obtained. When the bucket tip is about to reach the target excavation depth when automatic excavation is performed, the controller makes a determination based on the output signal from the bucket attitude detection means, and the controller makes the determination. By lowering the target excavation moment value to a predetermined value, the actual excavation depth was restricted so as not to exceed the target excavation depth.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a circuit diagram of essential parts of a hydraulic excavator that enables the automatic control method of the present invention. In the figure, the same reference numerals are given to those using the same constituent elements as those in the prior art. Reference numerals 17, 18, and 19 denote hydraulic remote control valves for booms, arms, and buckets (the hydraulic remote control valves can be operated in the front, rear, left, and right cross directions, but are shown separately for convenience of explanation), 20 , 21, 22 are pilot directional control valves, which are directional control valves, 23, ...,
28 is a shuttle valve for selecting pilot pressure, 2
9, to 34 are electromagnetic proportional pressure reducing valves which are electro-oil converters respectively, 35 is a main pump, 36 is a pilot pump, 3
Reference numeral 7 is a controller, 38 is a volume operating section for the driver to preset a target excavation moment value when performing automatic excavation, and 39 is a volume operating section for presetting a target excavation depth. FIG. 2 is a side view of a hydraulic excavator equipped with the circuit of FIG. 1. 1'is an upper swing body.

Next, the automatic control method of the present invention will be described with reference to FIGS. When performing automatic excavation with a hydraulic excavator, the driver sets the target excavation moment value MS of the bucket, for example, the value MS, to the volume operating unit 38, and the target excavation depth C of the bucket tip C (the toe of the bucket 6), for example, the depth hS. The volume operation unit 39 is set in advance. The above signals from the volume operation units 38 and 39 are
It is stored in the controller 37. When the excavation moment acting on the bucket 6 reaches the target excavation moment value MS when the hydraulic excavator starts automatic excavation, the bucket 6
Rotates and the work attachment 3 performs an automatic excavation cycle. In this case, the coordinates (x, y) of the position of the bucket tip C that moves is momentarily calculated and read by the controller 37. When the bucket tip C is about to reach the target excavation depth hS, that is, when the actual excavation depth becomes (hS-Δh), the depth signal is input to the controller 37. The controller 37 makes a determination based on the depth signal, and performs a process of lowering the target excavation moment value MS that has been input in advance to the controller 37. Figure 3
[Fig. 4] is a chart showing a state of a lowering process of the controller 37. As shown in FIG. 3, after the excavation depth reaches (hS-Δh), the target excavation moment value decreases, and when the excavation depth reaches hS, the target excavation moment value reaches a predetermined value 0. Become. The controller 37 makes a determination based on the lowering processing signal and outputs a boom raising command signal to the electromagnetic proportional pressure reducing valve 30. Since the secondary pilot pressure derived from the electromagnetic proportional pressure reducing valve 30 acts on the boom pilot switching valve 20 via the shuttle valve 24, the boom cylinder 8 extends. Therefore, when the excavation depth reaches the required target excavation depth hS during the automatic excavation work, the boom 4 is automatically raised and the excavation depth can be limited.

[0009]

According to the hydraulic excavator of the prior art in which the excavation moment of the bucket is used as a parameter for automatic excavation control, when the excavation moment is large due to the target soil condition, boom raising adjustment is automatically performed to shallow excavation. On the contrary, when the excavation moment is small, it is possible to dig deeply, so it was difficult to limit the required target excavation depth hS. However, in the automatic control method of the present invention, when performing automatic excavation, the driver sets the target excavation moment value and the target excavation depth of the bucket in separate volume operation units. When the bucket tip is about to reach the target excavation depth hS during automatic excavation, that is, when the actual excavation depth becomes (hS-Δh), the depth signal is input to the controller. The controller makes a determination based on the depth signal, and performs a process of lowering the target excavation moment value MS that has been input in advance to the controller. After the excavation depth reaches (hS-Δh), the target excavation moment value decreases, and when the excavation depth reaches hS, the target excavation moment value becomes a predetermined value, for example, 0. The controller makes a determination based on the lowering processing signal, and outputs a boom raising command signal to the boom pilot switching valve via the electro-hydraulic converter. This automatically raises the boom and limits the excavation depth to the target excavation depth hS. Therefore, the hydraulic excavator that enables the automatic control method of the present invention can ensure the excavation depth accuracy during the automatic excavation work.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a main part of a hydraulic excavator that enables an automatic control method of the present invention.

FIG. 2 is a side view of a hydraulic excavator equipped with the circuit of FIG.

FIG. 3 is a chart showing a state of a controller lowering process in the present invention.

FIG. 4 is a side view showing a backhoe type hydraulic excavator.

FIG. 5 is a side view of the hydraulic excavator in FIG. 4 viewed from the opposite side.

[Explanation of symbols]

 3 Work Attachment 4 Boom 5 Arm 6 Bucket 8 Boom Cylinder 9 Boom Cylinder 9 Arm Cylinder 10 Bucket Cylinder 11, 12, 13 Angle Sensor 14 Cylinder Pressure Sensor 15, 37 Controller 17, ~, 19 Hydraulic Remote Control Valve 20, ~, 22 Pilot Switching Valve 29 , ~, 34 Electromagnetic proportional pressure reducing valve 38, 39 Volume operation part

Claims (1)

[Claims] 1. A work attachment, in which a boom, an arm, and a bucket are sequentially connected to each other so as to be rotatable in the front-rear direction, is attached to a front portion of a vehicle body, and a bucket attitude detecting means and an excavating acting force detecting means are provided. In the automatic excavation control device, which controls the bucket rotation drive and the bucket ascent / descent drive based on the output signal from the means, and performs the automatic excavation using the bucket excavation moment as a parameter, the target excavation moment value and the target excavation When the depth is input to the controller in advance and automatic excavation is performed, when the bucket tip is about to reach the target excavation depth, the controller makes a determination based on the output signal from the bucket attitude detection means, and the controller By lowering the target excavation moment value to a predetermined value by judgment, the actual excavation depth is targeted. An automatic control method for a construction machine, characterized in that the excavation depth is restricted so as not to exceed the depth.