JPH0881977A - Hydraulic shovel - Google Patents

Abstract

PURPOSE: To improve excavation efficiency by changing the place of the slewing of a boom in response to the magnitude of excavation reaction received from a ground surface of a bucket at the time of excavation and upwards deflecting the bucket by the boom at the time of large excavation force measured. CONSTITUTION: The pressure of a stick cylinder 5 mainly using excavation force is fuzzy-controlled by the rule group of an excavation region controlling the pressure of the stick cylinder 5 at a value close to set pressure and the rule group of a soil take-in region in the operation of a boom 4. A bucket is fuzzy-controlled by the rule group of an excavation region conducting control in response to the movement of the stick 5 and the bucket 6 and the rule group of the soil take-in region in the operation of the bucket 6. The pressure of the stick cylinder 5 is controlled by a function to the angle of the bucket in the operation of the stick 5. Accordingly, efficient excavation corresponding to the nature of soil and excavation depth is enabled by the same automatic operation as excavation by the manual operation of a skilled operator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic excavator,
In particular, the present invention relates to a hydraulic excavator in which excavation efficiency is automatically kept high.

[0002]

2. Description of the Related Art In a conventional hydraulic excavator, the excavation efficiency changes greatly depending on the hardness of the ground or the operator of the hydraulic excavator, and it is possible to keep the excavation efficiency high by making the best use of the ability of the hydraulic excavator. could not.

[0003]

According to the present invention, even if the hardness of the ground changes or the operation of the operator is different, it is possible to prevent the excavation efficiency from decreasing and to keep the excavator ability constant. A hydraulic excavator that is fully utilized to keep excavation efficiency high is provided.

[0004]

[Means for Solving the Problem and Its Action] A hydraulic excavator having a boom, a stick, a bucket, a revolving structure for supporting the boom, and a traveling structure for traveling on the ground with the revolving structure mounted thereon are provided. ADVANTAGE OF THE INVENTION According to this invention, the apparatus which measures the magnitude | size of the excavation reaction force which a bucket receives from the ground at the time of excavation which a bucket advances in the ground so that the ground may be excavated, and the measured excavation reaction force (during excavation, almost In the traveling direction, the boom turning angle (αbm) is changed according to the magnitude of the force applied to the bucket from the ground, and if the measured excavation force (= excavation reaction force) is large (if fuzzy control,
If relatively large (as assessed by the membership function), the boom deflects upward in the direction of travel of the bucket (mainly determined by the sum of the swing velocity vectors of the boom and stick). And further have. According to the present invention, if the measured excavation force is large, the boom moves upward in the traveling direction of the bucket so that the excavation depth to the ground is reduced and the excavation force is reduced according to the magnitude of the excavation reaction force. Biasing (of course, if the measured digging force is small, the boom is prevented or suppressed from deflecting the direction of travel of the bucket upwards and reducing the digging force), so that the bucket is unnecessarily The excavation speed does not decrease, the excavation force is kept large, the excavation force does not excessively reduce the rotation speed of the bucket or stick, the excavation speed is kept high, and the excavator's capacity is always fully utilized. Keep the excavation efficiency high.

The excavation reaction force may be measured from the magnitude of the force of extension of the hydraulic cylinder that drives the stick or the hydraulic cylinder that drives the bucket during excavation. The force that the hydraulic cylinder extends may be obtained from the differential pressure of the hydraulic pressure applied to both ends of the hydraulic cylinder, or the side where the hydraulic pressure is supplied from the hydraulic source (the side opposite to the hydraulic pressure return side to the tank).
It may be obtained from the internal pressure of the hydraulic cylinder.

The excavation reaction force is a degree of opening of a flow control valve for controlling the flow rate of hydraulic fluid supplied to a hydraulic cylinder driving a stick or a hydraulic cylinder driving a bucket (a command value to the flow control valve). (Corresponding) and the magnitude of the hydraulic pressure during excavation supplied to the flow control valve (pressure set slightly by the operator slightly below the maximum output pressure of the hydraulic pressure source), the hydraulic cylinder or bucket that drives the stick. Displacement speed that is uniquely determined for a predetermined load (preferably no load) of the hydraulic cylinder that drives the stick, and actual displacement speed during excavation of the hydraulic cylinder that drives the stick (supplied to the flow control valve If the pressure and the opening degree of the flow rate control valve are constant, it may be measured from the difference between the load, that is, the magnitude of the excavating force.

The measured excavation force is a predetermined excavation force (ie,
When the excavation force is larger than the desired excavation force, which is selected and adjusted according to the excavation conditions such as the condition of soil and bucket movement, the boom is moved upward according to the difference between the measured excavation force and the predetermined excavation force. The acceleration urging the bucket may be changed (to a value exceeding zero), or the traveling direction of the bucket may be deflected upward by a predetermined degree. To adjust the acceleration of the movement of the boom is to change the opening degree (corresponding to the command value to the flow rate control valve) of the flow rate control valve that controls the flow rate of the hydraulic fluid supplied to the hydraulic cylinder that drives the boom. . The difference between the measured excavation force and the predetermined excavation force may be substantially proportional to the change amount of the opening degree of the flow control valve or the command value to the flow control valve. Furthermore, when the acceleration that urges the boom upwards exceeds a value of zero, the acceleration that urges the boom upward is increased according to the difference between the measured excavation force and the predetermined excavation force. May be. When the acceleration that urges the boom upward is negative (when the acceleration that urges the boom downward is greater than zero), depending on the difference between the measured excavation force and the predetermined excavation force, The acceleration that urges the boom downward may be reduced.

When the bucket faces upward by a predetermined degree or more (that is, when the scraping of soil by the bucket progresses by a predetermined degree or more), the boom moves the bucket in the upward direction in accordance with the measured excavation force. Biasing towards may be prevented.

The flow rate of the hydraulic fluid supplied to the hydraulic cylinder for driving the stick is controlled until the bucket faces upward by a predetermined degree or more (that is, until the scraping of soil by the bucket progresses by a predetermined degree or more). The opening degree of the flow control valve during excavation may be substantially constant (preferably fully open).

When the tip of the stick approaches the revolving structure to a predetermined degree or more (that is, when the scraping of the sand by the bucket progresses to a predetermined degree or more), the boom advances the bucket according to the measured excavating force. Deflection of the direction upwards may be prevented.

Until the tip of the stick approaches the revolving structure to a predetermined degree (that is, until the scraping of the sand by the bucket progresses to a predetermined degree or more), the hydraulic fluid supplied to the hydraulic cylinder for driving the stick is The opening degree of the flow control valve for controlling the flow rate during excavation may be substantially constant (preferably fully open).

After the magnitude of the extension force of the hydraulic cylinder that drives the boom exceeds a predetermined amount (that is, after the bucket is pushed down to the ground with a predetermined force or more and bites into the ground), the control device: The swing angle of the boom may be changed according to the magnitude of the measured excavation reaction force, and if the excavation force is measured, the boom may deflect the traveling direction of the bucket upward.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, an upper revolving structure 2 is mounted on a lower traveling structure 1 so as to freely rotate. The front part 3 is configured by rotatably connecting a boom 4, a stick 5, and a bucket 6, and all the operations of the front part 3 are achieved by hydraulic cylinders 7, 8, 9. Boom 4,
Angle detectors 11, 12, and 13 that detect the angles at which the stick 5 and the bucket 6 rotate are attached to their respective fulcrum pins. Further, the boom cylinder 7 is provided with pressure detectors 14 and 15 for detecting the expansion side and contraction side pressures thereof, and the stick cylinder 8 is supplied with a non-rod side thereof (hydraulic pressure for extending the cylinder). Side)
A pressure detector 16 is provided to detect the pressure Ps.

The outputs of the angle detectors 11, 12, 13 are input to the bucket position calculating means 53. The bucket position calculating means 53 is composed of a bucket angle calculating means 53a and a bucket tip position calculating means 53b. The bucket angle calculating means 53a geometrically calculates the angle phi of the bucket with respect to the horizontal plane to calculate the bucket tip position. The position Y of the bucket tip is calculated geometrically by the calculation means 53b.
tip is calculated. The bucket angle in this embodiment
Definitions of phi and bucket tip position Ytip are shown in FIG. The bucket angle phi is the angle formed by the straight line extending from the fulcrum pin of the bucket to the tip of the bucket and the horizontal axis, and the bucket tip position Ytip is the deepest point of one excavation and the height to the lower traveling body.

The output of the stick pressure detecting means 16 is input to the stick pressure deviation / change amount calculating means 51, and the outputs of the angle detectors 12 and 13 are input to the cylinder speed converting means 52 provided corresponding to each. . The conversion means 5
In 2, the stick cylinder speed Vst and the bucket cylinder speed Vbk are calculated from the amount of change in the stick angle and the bucket angle per control unit time.

In the calculation means 51, the deviation ΔPst (= Ps-Pset) of the measured stick pressure Ps with respect to the stick pressure set value Pset input from the set pressure input means 55 and the stick pressure change which is the change amount of the stick pressure with the passage of time. The amount ΔPst (= ΔPst / Δt) is calculated. The amount of change corresponds to the gradient of the stick pressure Ps over time. The stick pressure deviation ΔPst, the stick pressure change amount ΔPst, the bucket angle phi from the bucket position calculating means 53, and the bucket tip position Ytip are calculated by the calculating means 56.
Is input to the boom operation control rule group calculating means 56a. Further, the stick cylinder speed Vst, the bucket cylinder speed Vbk, the bucket angle phi, and the bucket tip position Ytip are input to the bucket operation control rule group computing means 56b in 56. Further, the bucket angle phi is input to the stick operation setting means 56c.

The amount of change ΔJbm (corresponding to the amount of change in boom speed, ie acceleration) of the command value (commanding the opening of the flow rate control valve) to the boom operation flow control valve is output from the boom computing means 56a. The ratio of the actual command value to the bucket operation flow control valve relative to the reference value of the preset command value (commanding the opening of the flow control valve) to the bucket operation flow control valve from the bucket computing means 56b. The operation rate γJbk is output. Also, the stick operation setting means 5
Command value Jst to the flow control valve for stick operation from 6c
It is designed to output itself. The boom operation amount calculation means 57 receives the amount of change ΔJbm in the command value to the boom operation flow control valve from the boom operation means 56a, and outputs the boom operation amount Jbm. The operation rate γJbk from the bucket operation means 56b is input to the bucket operation amount calculation means 58, and the bucket operation amount Jbk is output.
The determination means 59 has an output Jbm from the boom operation amount calculation means 57, an output Jbk from the bucket operation amount calculation means 58,
The output Jst from the stick operation setting means 56c, the output value from the bucket position calculation means (corresponding to the position and attitude of the bucket), the non-rod side and rod side pressures Pb1 and Pb2 of the boom cylinder 7, and the console 60 which is the input means. Signal is input to perform the landing determination of the bucket, the command value output at the start of excavation, the command value output during excavation, the determination of the end of excavation, and the command value output at that time.

Reference numeral 54 is a storage means (memory), and the storage means 54 stores the control rules shown as examples in FIGS. 2 and 3 and the functions shown as examples in FIGS. 4 and 5. FIG. 2 shows a rule group applied to the boom operation control rule group calculation means 56a. The rule group BM1 in the excavation area shown in part (a) and the rule group BM2 in the soil uptake area shown in part (b).
It consists of and. FIG. 3 shows a rule group applied to the bucket operation control rule group calculation means 56b.
It is composed of a rule group BK1 of the excavation area shown in the section and a rule group BK2 of the soil uptake area shown in the section (b). Also,
The function applied to the stick operation setting means 56c is shown in FIG. 5, and in this example, a linear function that uniquely sets the stick operation amount Jst with respect to the bucket angle phi is shown.

A method of expressing rules will be briefly described by taking the rule group BM1 shown in part (a) of FIG. 2 as an example. In the figure, the rules are expressed in a table format, but this is the same as that expressed in the if-, then- formats, as shown below.

[Equation 1] if (phi is PB) and (ΔPst is
PB) and (ΔPst is NB) then (ΔJbm1 is
ZO) (The above rule corresponds to the shaded area in Figure 2 (a).) In the rule, PB is Positive Big and PM is P
Positive Medium, PS is Positive Small
(Positive / Small), ZO stands for ZERO, and in the rule,
NB is Negative Big, NM is Negative Me
dium (negative / medium) and NS represent Negative Small (negative / small). PB, NB, etc. are called labels. ΔP
st is the amount of change in ΔPst per control step time. Also,
In order to quantitatively express the control rule using the labels shown in FIGS. 2 and 3, the membership function as shown in parts (a) and (b) of FIG. 4 is used.

Next, the operation of the present invention will be described focusing on the calculating means 56, the calculating means 57, 58 and the judging means 59. First, the operation of the calculating means 56 will be specifically described. Here, the rule groups BM1 and BM2 of the calculating means 56a will be described as an example with reference to FIG. FIG. 6 shows a rule group BM of part (a) of FIG.
1 of 1 (lower right of the table) and 1 of rule group BM2 in part (b)
It shows the case of one (lower left of the table), and it is expressed in the if ~ then ~ format as follows. "Rule group BM1"

(2) if (phi is PB) and (ΔPst is
PB) and (ΔPst is PB) then (ΔJbm is
PB) "Rule group BM2"

[Equation 3] if (phi is PM) and (Ytip is P
S) then (ΔJbm is PM) In the “rule group BM1” on the left side of FIG. 6 (rule antecedent part), the value of the membership function corresponding to each label is obtained from the input data, phi, ΔPst, and ΔPst, respectively, and these Select the smallest of the three membership values of (min operation). Similarly for the antecedent part of the "rule group BM2", the value of the membership function corresponding to each label is obtained from the input data, phi, and Ytip, and the minimum value thereof is selected. Next, each membership function on the right side (rule consequent part) of FIG. 6 is modified based on the minimum membership function calculated in the antecedent part described above (the modified membership function is indicated by the solid line in FIG. 6). Is shown). The above-mentioned correction process is performed for both the consequent parts of the "rule group BM1" and the "rule group BM2". The weighted average value of all the corrected membership functions is calculated, and the weighted average value is used as the output of the fuzzy control, that is, the output value ΔJbm of the calculation means 56a of the control rule group. In addition,
The above description outlines the operation of the calculation means 56 by extracting one rule from each of the rule group BM1 and the rule group BM2, but specifically, parts (a) and (b) of FIG. Calculation is performed for all the antecedent rules shown in. That is, regarding the rule group BM1,
(Phi is PB) 1 x (ΔPstis NB to PB)
5 × (ΔPst is NB to PB), total of 2
The value of the antecedent part membership function is obtained for the five rules, the minimum value of the membership function in each rule is found, and the membership function of the consequent part of each rule is corrected by the minimum value. Similarly for the rule group BM2, three (phiis ZO to PM) × (Yti
p is PS to PB), the value of the antecedent membership function is calculated for a total of 9 rules, the minimum value of the membership function in each rule is calculated, and each rule is calculated by the minimum value. Correct the membership function in the consequent part. Then, the weighted average value of the membership function is calculated for all the modified consequent part membership functions (25 + 9), and the average value is used as the output of the fuzzy control.

Bucket operating control rule group computing means 5
The processing method of 6b is the same as that described above, but in this example, the stick, bucket cylinder speed ratios γst, γbk are added to the input data.
Are using. The speed ratio is defined by the following equation.

[Equation 4] γst = Vst / V ^* st

## EQU00005 ## .gamma.bk = (Vbk / V ^* bk) -1 where Vst and Vbk are sticks and bucket cylinder speeds V ^* st and V ^* bk are preset stick and bucket cylinder reference speeds. The output of 56b is the operation rate γJbk with respect to the reference command value J ^* bk to the bucket operation flow rate control valve.

The data used together in the rule groups shown in FIGS. 2 and 3 is the bucket angle phi, which is (a)
The label in the rule group of the excavation area shown in the section is "PB"
(Ifphi is PB). In contrast,
In the rule group of the soil uptake area shown in part (b), the bucket angle
PM to ZO are used for phi. That is, the rule groups BM1 and BK1 in the excavation area are applied in the range where the bucket angle phi during excavation is relatively large, but the rule groups BM2 and BK2 in the soil uptake area are applied in the latter half of the excavation when the bucket angle phi becomes small. Will be. As described above, since the rule group applied by the bucket angle phi changes, the area mainly for excavation operation is continuously switched to the area mainly for operation to take in excavated soil.

Here, in FIG. 2, the rule group BM1 of the boom operating excavation area shown in part (a) of the stick cylinder pressure Ps follows the set pressure Pset (the difference between them is as small as possible). The rule group BM2 of the soil uptake area shown in part (b) of the boom is a rule for operating the boom, and when the bucket angle phi becomes small, the change amount of the command value to the boom operation flow control valve (acceleration of the boom cylinder).
However, as the depth Ytip of the bucket tip becomes deeper (PB), the bucket operation is pulled up and excavated. Therefore, the command value to the boom operation flow control valve is relatively set compared to when the depth Ytip is shallow (PS). The total amount of change is increased (PS → PM, PM → PB).

In FIG. 3, the rule group BK1 of the excavation area of the operation shown in part (a) operates the bucket so that the bucket speed maintains the reference speed when the stick speed is sufficiently fast (PB), Stick speed slows down (PS)
Then, the bucket operation is also lowered by that amount, which is a group of rules for operating the bucket according to the movement (speed) of the stick. The rule group BK2 of the soil uptake area shown in part (b) is a rule for operating the bucket with respect to the bucket angle phi and the depth Ytip of the bucket tip based on the same idea as the rule group BM2 described above. .

FIG. 5 shows a setting function of the command value to the stick flow control valve (corresponding to the opening of the flow control valve). When the bucket angle phi becomes small due to the excavation operation, the command value Jst to the stick operation flow control valve is set. Is small. This is because in the soil uptake area, the speed of excavation by the stick is reduced, soil is successfully taken in, and the stop shock at the end of excavation is reduced.

The boom operation amount calculation means 57 in FIG. 1 inputs the output ΔJbm from the calculation means 56a and calculates the boom operation amount Jbm using the following equation.

[Equation 6] Jbm ^(k) = Jbm ^(k-1) + ΔJbm ^(k) · Δt where (k) represents the current step, (k-1) represents the previous step, and Δt represents the control step time. Is. In this way, the integrated value of the output from the calculation means 56a and the control time interval is added to the operation amount of the previous step. The bucket operation amount calculation means 58 in FIG. 1 inputs the output γJbk from the calculation means 56b and calculates the bucket operation amount Jbk using the following equation.

## EQU00007 ## Jbk ^(k) = J ^* bk (1 + .gamma.Jbk) where J ^* bk is the bucket reference operation amount.

The final operation command value for each cylinder of the boom, stick and bucket is input to the judging means 59. Further, the determination means 59 includes the boom cylinder non-rod side pressure detector 14 and the rod side pressure detector 1.
The signal of No. 5 and the output (bucket tip position) from the bucket position calculating means 53 are input. Further, the start position of the excavation work is further input to the determination means 59 using the console (input means) 60. Although the example in which the console 60 and the judging means 59 are directly connected is shown here, the input may be made to the judging means 59 remotely.

The processing by the judging means 59 is executed by the procedure as shown in FIG. That is, if the excavation start position DP is input by the operator (step 401) and the automatic operation is started (step 402), the actual bucket tip position BP calculated by the bucket tip position detection means 53 is set as the excavation start position. It is moved to DP (step 403). Further, whether or not the bucket has landed on the excavated ground is determined by the pressure difference between the pressure Pb1 detected by the pressure detector 14 on the rod side of the boom cylinder and the pressure Pb2 detected by the pressure detector 15 on the rod side. That is, when Pb1 <Pb2, it is determined that the bucket has landed (step 404). Next, the initial command value is output to the boom, stick, and bucket for Δt seconds after landing the bucket (406). For example, since the operation amount of the stick is usually 100%, that value is used as an initial command, and since the boom is not operated at the start of excavation, the initial command value is 0.
%, The bucket is slightly operated at the start of excavation, so the initial command value is output as 20%.

After landing on the bucket, it exceeds Δt seconds (405)
And a command value to each flow rate control valve based on the control rule of the present invention, that is, the boom operation means 57, the bucket operation means 58, and the stick operation setting means 56c is output (40
7). Hydraulic pressure is supplied to each cylinder by each cylinder drive means based on this command value. In the embodiment of the present invention, the stick operation command is not based on a rule similar to the rules shown in FIG. 2 and FIG.
This is to simplify the stick operation command, and can be expressed in the fuzzy control rule format. Therefore,
The stick operation is also summarized in step 407. Next, the present bucket tip position BP is received from the bucket tip position calculating means 53b (408), it is judged whether or not the bucket tip position BP is above the ground surface (step 409), and it is below the ground surface. In this case, the process returns to step 407 and the output of the operation command value is repeated. When the current bucket tip position BP is above the ground surface in step 409, the bucket 6 is moved to a predetermined position so as not to spill the soil by the same control as the conventional trajectory control, and the soil is discharged (410). ), And returns to step 401. In step 408 described above, the bucket tip position BP is not used, the bucket angle phi from the bucket angle calculation means 53a is used, and when the bucket angle phi becomes horizontal in step 409, it is regarded as the end of the automatic excavation, You may move to step 410.

As described above, according to the present invention, when the boom is operated during automatic excavation, the pressure of the stick cylinder, which is the main component of the excavation force, is made to follow the set pressure (the difference between them should be as small as possible). ) Fuzzy control is performed by the rule group MB1 of the excavation area to be controlled and the rule group BM2 of the soil uptake area based on the bucket angle and the excavation depth at the bucket tip, and the bucket operation is performed according to the movement (speed) of the stick or bucket. Group of excavation areas controlled by BK
1 and the above-mentioned soil collection area rule group BK2 are fuzzy controlled, and the stick operation is controlled by a function (or rule) with respect to the bucket angle. Therefore, a movement similar to that performed by a skilled operator by manual operation is performed. Can be realized even during automatic operation, and efficient excavation can be performed according to soil quality and excavation depth.

The set pressure of the stick cylinder is set by the input means 55, and when the excavation soil is hard, the set pressure is increased in order to increase the stick excavation force, whereby automatic excavation according to the soil quality can be performed. . Further, the setting by the input means may be performed remotely or automatically. Although the angle detectors 11, 12, and 13 that detect the rotation angle of each pin are used as the position detecting means in the above-described embodiment, the present invention is not limited to this, and the boom cylinder is not limited thereto. 7, stick cylinder 8,
The position of the bucket cylinder 9 may be detected using a position detector that detects the amount of expansion and contraction.

[Brief description of drawings]

FIG. 1 is a schematic view showing a main configuration of a hydraulic excavator according to the present invention.

FIG. 2 is a table showing a set of fuzzy control rules for determining a command value change to a boom operating flow control valve according to the present invention.

FIG. 3 is a table showing a set of fuzzy control rules for determining a command value for a bucket operating flow control valve according to the present invention.

FIG. 4 is a membership function (part a) for evaluating measured values used for fuzzy control according to the present invention, and a hydraulic cylinder command value (or command value change amount) based on the evaluation value determined by the membership function. The diagram which shows the membership function (b part) for determining.

FIG. 5 is a diagram showing a relationship between a bucket angle and a command value to a stick operation flow control valve in the present invention.

FIG. 6 uses a membership function for evaluating a measured value and a membership function for determining a hydraulic cylinder command value (or command value change amount) based on the evaluation value determined by the present invention. A diagram showing an example of a data processing method when performing.

FIG. 7 is a schematic view showing a standard for measuring the position and orientation of a bucket according to the present invention.

FIG. 8 is a flowchart showing an outline of the overall configuration of a hydraulic excavator control sequence incorporating the control according to the present invention.

[Explanation of symbols]

 1 Lower Traveling Body 2 Upper Revolving Body 4 Boom 5 Stick 6 Bucket 7 Hydraulic Cylinder 8 Hydraulic Cylinder 9 Hydraulic Cylinder 11 Angle Detector 12 Angle Detector 13 Angle Detector 14 Pressure Detector 15 Pressure Detector 16 Pressure Detector 50 Control Device

[Procedure amendment]

[Submission date] May 17, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

Front Page Continuation (72) Inventor Makoto Samejima 2-5-1, Marunouchi, Chiyoda-ku, Tokyo Sanryo Heavy Industries Co., Ltd.

Claims (14)

[Claims] 1. A hydraulic excavator having a boom, a stick, a bucket, a revolving structure that supports the boom, and a traveling structure that travels on the ground with the revolving structure mounted thereon. The bucket excavates the ground. Device that measures the magnitude of the excavation reaction force that the bucket receives from the ground during excavation when the ground excavates, and the swing angle of the boom is changed according to the magnitude of the measured excavation reaction force to measure the excavation reaction force. If the force is large, the boom further includes a control device that deflects the traveling direction of the bucket upward. 2. The hydraulic excavator according to claim 1, wherein the digging reaction force is measured from the magnitude of the force of extension of the hydraulic cylinder that drives the stick during digging. 3. The hydraulic excavator according to claim 1, wherein the excavation reaction force is measured from the magnitude of the force of extension of the hydraulic cylinder that drives the bucket during excavation. 4. The excavation reaction force is a magnitude of an opening degree during excavation of a flow rate control valve that controls a flow rate of hydraulic fluid supplied to a hydraulic cylinder that drives a stick and a hydraulic pressure during excavation that is supplied to the flow rate control valve. And a predetermined displacement speed that is uniquely determined for a predetermined load of the hydraulic cylinder that drives the stick, and the actual displacement speed during excavation of the hydraulic cylinder that drives the stick. The hydraulic excavator according to Item 1. 5. The excavation reaction force is a magnitude of an opening degree during excavation of a flow rate control valve that controls a flow rate of hydraulic fluid supplied to a hydraulic cylinder that drives a bucket and a hydraulic pressure during excavation that is supplied to the flow rate control valve. And a predetermined displacement speed that is uniquely determined for a predetermined load of the hydraulic cylinder that drives the bucket, and an actual displacement speed during excavation of the hydraulic cylinder that drives the bucket. The hydraulic excavator according to Item 1. 6. The method according to claim 1, wherein when the measured excavation reaction force is larger than a predetermined excavation force, the traveling direction of the bucket is deflected upward with an acceleration that biases the boom upward. Hydraulic excavator. 7. The hydraulic excavator according to claim 1, wherein when the measured excavation reaction force is large, the boom deflects the traveling direction of the bucket upward by a predetermined degree. 8. The method according to claim 1, wherein when the bucket faces upward by a predetermined amount or more, the boom is prevented from deflecting the traveling direction of the bucket upward according to the measured excavation reaction force. Hydraulic excavator. 9. The opening degree during excavation of a flow control valve that controls the flow rate of hydraulic fluid supplied to a hydraulic cylinder that drives a stick is substantially constant until the bucket faces upward by a predetermined degree or more. The hydraulic excavator according to claim 1. 10. The boom is prevented from deflecting the traveling direction of the bucket upward in accordance with the measured excavation reaction force when the tip of the stick approaches the swing structure to a predetermined extent or more. The hydraulic excavator according to Item 1. 11. The opening degree at the time of excavation of the flow rate control valve for controlling the flow rate of the hydraulic fluid supplied to the hydraulic cylinder that drives the stick is substantially constant until the tip of the stick approaches the swinging body to a predetermined degree. The hydraulic excavator according to claim 1, which is constant. 12. The control device changes the swing angle of the boom according to the magnitude of the measured excavation reaction force after the magnitude of the force for extending the hydraulic cylinder for driving the boom exceeds a predetermined level. If the measured excavation force is large, the boom will deflect the bucket's direction of travel upwards,
The hydraulic excavator according to claim 1. 13. When the measured excavation reaction force is larger than a predetermined excavation force, with the acceleration for urging the boom upward,
The hydraulic excavator according to claim 1, wherein the traveling direction of the bucket is deflected upward, and the magnitude of acceleration is changed according to the difference between the measured excavation reaction force and a predetermined excavation force. 14. When the measured excavation reaction force is larger than a predetermined excavation force, with the acceleration for urging the boom upward,
2. The bucket according to claim 1, wherein the traveling direction of the bucket is deflected upward, and the magnitude of the acceleration is changed according to a rate of change of a difference between the measured excavating force and a predetermined excavating force with respect to time progress. Hydraulic excavator.