JP2006194823A - Device for measuring positions of working tools for working machines - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for measuring the positions of working tools for working machines capable of improving the measurement accuracy of measurement points in the height direction of the working tool for the working machine. <P>SOLUTION: A means 27 for operating vehicle positions calculates the three-dimensional position of the rotational center of a boom 8, based on a three-dimensional position positioned by GPS antenna devices 16, 17, and a means 28 for calculating the bucket position calculates the three-dimensional position of a bucket 10, based on the three-dimensional position of the rotational center and the detection result of boom angle detectors 18-21. Reference height is inputted by a device 22 for inputting reference heights with a laser 31 emitted by a laser generator 30 arranged at a reference height position received by a photoreceiver 32 mounted on a working device 7. When a correction command switch 25 is turned on, a means 29 for correcting the bucket height calculates the height of the photoreceiver 32 to correct the height of the bucket 10, based on the difference between the height and the reference height. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is provided in a work machine including an articulated work device having a work tool at a tip, and the work machine performs the measurement of the three-dimensional position of the work tool automatically in conjunction with the operation of the work machine. The present invention relates to a tool position measuring device.

  As a conventional technique related to a position measuring device for a work tool of a work machine, a state quantity related to a posture of a multi-joint type work device having a positioning means for measuring a three-dimensional position at a predetermined position of a vehicle body of the work machine and a work tool at a tip. A state quantity detection means for detecting the position of the work tool, and a work tool position calculation means for calculating the three-dimensional position of the work tool based on the three-dimensional position measured by the positioning means and the state quantity detected by the state quantity detection means. There is something to have.

  As this type of prior art, for example, there is one disclosed in Patent Document 1. This prior art is applied to a hydraulic excavator, and includes a GPS antenna device provided at a rear portion of a rotating body of the hydraulic excavator as positioning means. The state quantity detection means includes a displacement sensor for detecting the extension amount of the boom cylinder, a displacement sensor for detecting the extension amount of the arm cylinder, and a displacement sensor for detecting the extension amount of the bucket cylinder. Further, a computer that calculates the three-dimensional position of the bucket using the three-dimensional position measured by the GPS antenna device, the turning angle information from the rotation angle sensor, and the elongation amount information from each displacement sensor as the work tool position calculation means. It has.

In the conventional technology configured as described above, the computer uses the three-dimensional position of the bucket based on the three-dimensional position measured by the GPS antenna device, the turning angle detected by the rotation angle sensor, and the amount of extension detected by each displacement sensor. Calculate the position. Thereby, the measurement of the three-dimensional position of the bucket is automatically performed in conjunction with the operation of the front work apparatus.
Japanese National Patent Publication No. 9-500700

  In the above-described prior art, the error of the measurement point in the height direction measured by the GPS antenna device is very small, but the measurement result of the three-dimensional position of the bucket includes the state of play of the work device and the posture of the work device. There has been a problem that a large error occurs due to accumulation of quantity detection errors and the like.

  The present invention has been made in consideration of the above-described actual situation, and an object of the present invention is to provide a work tool position measuring device for a work machine that can improve the measurement accuracy of measurement points in the height direction of the work tool of the work machine. Is to provide.

  [1] In order to achieve the above-mentioned object, the present invention relates to a state relating to the posture of a multi-joint type work device having a positioning means for positioning a three-dimensional position at a predetermined position of a vehicle body of a work machine and a work tool at the tip. Based on the state quantity detection means for detecting the quantity, the three-dimensional position at the predetermined location of the vehicle body measured by the positioning means, and the state quantity relating to the posture of the working device detected by the state quantity detection means, In a work tool position measurement device for a work machine that includes a work tool position calculation unit that calculates a three-dimensional position of the work tool, at a height position that is the same as a reference position whose height is measured in advance outside the work machine, The three-dimensional position at the predetermined position of the vehicle body measured by the positioning means in a state where the predetermined position of the working device is arranged, and the work detected by the state quantity detecting means The height of the work tool calculated by the work tool position calculation means based on the difference between the height of the predetermined position of the work device calculated based on the state quantity related to the posture of the device and the height of the reference position. A work tool position measuring device for a work machine, comprising: a work tool height correcting means for correcting.

  In the present invention configured as described above, the positioning means measures the three-dimensional position at a predetermined position of the vehicle body. Further, the state quantity detection means detects a state quantity related to the posture of the work device. The work tool position calculation means calculates the three-dimensional position of the work tool based on the three-dimensional position measured by the positioning means and the state quantity detected by the state quantity detection means. The work tool height correction means is a three-dimensional position measured by the positioning means in a state where a predetermined position of the work device is arranged at the same height position as a reference position whose height is measured in advance outside the work machine. And the height of a predetermined portion of the work device based on the state quantity detected by the state quantity detection means, and calculated by the work tool position calculation means based on the difference between this height and the height of the reference position. Correct the height of the work implement. In other words, the height direction of the work tool of the work machine is obtained by executing the correction of the height of the work tool by the work tool height correction means in a state where the predetermined position of the work device is arranged at the same height as the reference height. The measurement accuracy of the measurement points can be improved.

  [2] According to the present invention, in the invention described in [1], a laser generating unit that emits a laser in a horizontal direction from the reference position, a light receiving unit that is provided at a predetermined position of the working device, and receives the laser. And a notifying means for notifying that the laser beam has been received.

  [3] In the invention according to [1], the present invention is characterized by comprising correction command means for instructing execution of correction by the work implement height correction means, and cancellation means for canceling execution of correction.

  [4] The present invention provides the boom according to the invention described in [1], wherein the work device is coupled to the vehicle body so as to be pivotable in the vertical direction, and an arm coupled so as to be pivotable in the boom vertical direction. And the predetermined position of the working device is a portion included in the arm.

  As described above, the present invention calculates the height of a predetermined portion of the work device, and corrects the height of the work tool based on the difference between this height and the reference height. Thereby, the measurement accuracy of the measurement point in the height direction of the work implement of the work machine can be improved.

  An embodiment of a work tool position measuring device for a work machine according to the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing a hydraulic excavator to which an embodiment of a position measuring device for a work tool of a working machine according to the present invention is applied, FIG. 2 is a block diagram showing a system configuration of this embodiment, and FIG. FIG. 4 is a diagram showing the reference height input device and the correction command switch shown in FIG. 2, FIG. 4 is an enlarged view of the light receiver and the alarm device shown in FIG. 1, and FIG. The figure which shows an alarm, (b) is the figure which shows the light receiver and the alarm which were seen from the cab side, and FIG. 5 is used when calculating the three-dimensional position of the toe of a bucket with the computer shown in FIG. FIG. 6 is a flowchart showing the procedure of calculation processing performed by the computer shown in FIG. 2, and FIG. 7 is a flowchart showing details of the calculation processing performed in step S4 shown in FIG.

  This embodiment is applied to the hydraulic excavator 1 shown in FIG. The hydraulic excavator 1 includes a traveling body 2 that constitutes a lower part of the hydraulic excavator 1 and travels the hydraulic excavator 1, and a revolving body 3 that is turnably provided on the traveling body 2.

  The swivel body 3 includes a cab 4, a machine room 5, and a counterweight 6. The cab 4 is provided on the left side of the front part of the swivel body 3. The machine room 5 is provided behind the cab 4 and stores a hydraulic circuit (not shown) that drives the excavator 1, a hydraulic control device 14 (see FIG. 2) that controls the hydraulic circuit, and the like. . The counterweight 6 is provided behind the machine room 5, that is, at the rear end of the swing body 3.

  The excavator 1 also includes an articulated working device 7 having a working tool, for example, a bucket 10 at the tip. This working device 7 is located on the right side of the cab 4 and in the center of the front portion of the revolving structure 3. The boom 8 is pin-coupled so as to be pivotable in the vertical direction, and is rotated up and down at the free end of the boom. An arm 9 that is movably pin-coupled is provided. The bucket 10 is pivotally connected to the free end of the arm 9, that is, the tip of the working device 7. Each of the boom 8, the arm 9, and the bucket 10 is driven by a boom cylinder 11, an arm cylinder 12, and a bucket cylinder 13 that are controlled by the hydraulic control device 14.

  Further, as shown in FIG. 2, the excavator 1 sets an excavation depth D (see FIG. 5) as a target excavation depth with reference to the rotation center P <b> 0 of the boom 8 with respect to the swing body 3. An area setting unit 15 is provided. The hydraulic control device 14 adjusts the boom cylinder 11 so that the toe P3 of the bucket 10 does not move to a position deeper than the excavation depth D according to the excavation depth D set by the excavation area setting device 15. The arm cylinder 12 and the bucket cylinder 13 are controlled.

  As shown in FIG. 2, the present embodiment includes GPS antenna devices 16 and 17 as positioning means for measuring a three-dimensional position at a predetermined location of the vehicle body of the work machine. As shown in FIG. 1, the GPS antenna device 16 is installed on the left side of the rear part of the revolving unit 3, measures its own three-dimensional position, and outputs a position signal indicating this three-dimensional position. Yes. The GPS antenna device 17 is installed on the right side of the rear part of the revolving unit 3, measures its own three-dimensional position, and outputs a position signal indicating this three-dimensional position.

  In the present embodiment, as shown in FIG. 2, for example, a boom angle detector 18, an arm angle detector 19, and a bucket angle detector 20 are used as state quantity detection means for detecting a state quantity related to the posture of the work device 7. The tilt angle detector 21 is provided. Although not shown, the boom angle detector 18 is provided at a pin coupling portion between the boom 8 and the revolving body 3. The boom angle detector 18 detects the rotation angle α of the boom 8 with respect to the revolving body 3 and indicates the rotation angle α. Output boom angle signal. Although not shown, the arm angle detector 19 is provided at a pin coupling portion between the arm 9 and the boom 8. The arm angle detector 19 detects the rotation angle β of the arm 9 relative to the boom 8, and shows the rotation angle β. Output a signal. Although not shown, the bucket angle detector 20 is provided at a pin coupling portion between the bucket 10 and the arm 9, detects the rotation angle γ of the bucket 10 with respect to the arm 9, and outputs a bucket angle signal indicating the rotation angle γ. Output. Although not shown, the tilt angle detector 21 is provided in the machine room 5, detects the tilt angle of the swivel body 3 in the front-rear direction with respect to the horizontal plane, and outputs a tilt angle signal indicating the tilt angle.

  As shown in FIG. 5, the rotation angle α of the boom 8 includes the horizontal plane k including the rotation center P0 when the revolving body 3 is assumed to be horizontal, the rotation center P0 of the boom 8 and the arm 9. Is an angle formed by a line segment a connecting with the rotation center P1. The rotation angle β of the arm 9 is an angle formed by a line segment b connecting the rotation center P1 of the arm 9 and the rotation center P2 of the bucket 10 and the line segment a. The rotation angle γ of the bucket 10 is an angle formed by a straight line c connecting the bucket 10 rotation center P2 and the toe P3 of the bucket 10 and a line segment b.

  Further, as shown in FIG. 2, the present embodiment is connected to GPS antenna devices 16 and 17, a boom angle detector 18, an arm angle detector 19, a bucket angle detector 20, and an inclination angle detector 21, and these Is provided with a computer 26 for processing the signal from the computer according to a program stored in advance.

  The computer 26 includes vehicle body position calculation means 27 for calculating the three-dimensional position (X0, Y0, Z0) of the pivot center P0 of the boom 8 as the three-dimensional position of the vehicle body. The three-dimensional position of the vehicle body is obtained by using a trigonometric function based on the three-dimensional position of the GPS antenna device 16 measured by the GPS antenna device 16 and the three-dimensional position of the GPS antenna device 17 measured by the GPS antenna device 17. Calculated. Trigonometric functions indicating the positional relationship between the rotation center P0 and the GPS antenna devices 16 and 17 are stored in the computer 26 in advance.

  The computer 26 also includes bucket position calculation means 28 that calculates the three-dimensional position (X3, Y3, Z31) of the toe P3 of the bucket 10 as the three-dimensional position of the bucket 10. The three-dimensional position of the bucket 10 is the three-dimensional position (X0, Y0, Z0) of the rotation center P0 calculated by the vehicle body position calculation means 27, the rotation angle α detected by the boom angle detector 18, and the arm angle detection. Is calculated using a trigonometric function based on the rotation angle β detected by the detector 19, the rotation angle γ calculated by the bucket angle detector 20, and the inclination angle detected by the inclination angle detector 21. . The length dimension La of the line segment a, the length dimension Lb of the line segment b, and the length dimension Lc of the line segment c used when using the trigonometric function are stored in the computer 26 in advance.

  In the present embodiment, the height Zb (hereinafter referred to as “reference height Zb”) of the reference position Pb where the three-dimensional position (Xb, Yb, Zb) outside the excavator 1 is previously measured is input to the computer 26. As a means for this, a reference height input device 22 is provided. The reference height input device 22 is provided in the cab 4, for example, and as shown in FIG. 3, for example, an input operation unit 23 having a plurality of push buttons for inputting the reference height Zb, and the input operation unit And a display unit 24 for displaying the reference height Zb input by the control unit 23.

  Further, as shown in FIG. 1, the present embodiment includes a laser generator 30 installed at a reference position Pd as laser generation means for emitting a laser 31 from the reference height Zb in the horizontal direction. In addition, a light receiver 32 attached to the left side surface of the arm 9 is provided as a light receiving means provided at a predetermined position of the work device 7 to receive the laser 31. In addition, a notification device 40 is provided as notification means for notifying that the light receiver 32 has received the laser 31.

  For example, as shown in FIG. 4A, the light receiver 32 has a plurality of light receiving portions 33 to 39 arranged in the vertical direction, and the alarm device 40 is, for example, as shown in FIG. 4B, the light receiving portion 33. There are notification lamps 41 to 47 provided corresponding to .about.39. The notification lamp 44 located at the center of the notification lamps 41 to 47 is lit in red, and is turned on when the light receiving unit 36 located at the center of the light receiving units 33 to 39 receives the laser 31. . In addition, the notification lamps 41 to 43 above the notification lamp 44 are lit in green, and light up when the corresponding one of the light receiving units 33 to 35 above the light receiving unit 36 receives the laser. . Similarly, the notification lamps 45 to 47 arranged below the notification lamp 44 are also lit in green, and when the corresponding one of the light receiving units 37 to 39 below the light receiving unit 36 receives the laser 31, respectively. Lights up.

  That is, the notification device 40 notifies that the light receiver 32 is receiving the laser 31 at an appropriate position by the central notification lamp 44, and receives the light receiver 32 by the other notification lamps 41 to 43 and 45 to 47. The amount of deviation with respect to the laser 31 is notified.

  Further, as shown in FIG. 2, the computer 26 corrects the height Z31 of the toe P3 calculated by the bucket position calculating means 28 (hereinafter also referred to as “toe height Z31”). It has. The bucket height correcting means 29 is configured to provide a difference (Zb) between the height Z4 of the light receiver 32 (hereinafter also referred to as “light receiver height Z4”) and the reference height Zb input by the reference height input device 22. Based on -Z4), the toe height Z31 is corrected.

  The light receiver height Z4 is the three-dimensional position (X0, Y0, Z0) of the rotation center P0 calculated by the vehicle body position calculation means 27, and the rotation angle α of the boom 8 detected by the boom angle detector 18. Based on the rotation angle β of the arm 9 detected by the arm angle detector 19, the rotation angle γ of the bucket 10 detected by the bucket angle detector 20, and the inclination angle detected by the inclination angle detector 21. , Calculated using a trigonometric function. The length dimension Ld used when using the trigonometric function and the angle θ formed by the line segment d and the line segment b are stored in the computer 26 in advance. The length dimension Ld is a length dimension of a line segment d connecting the rotation center P1 of the arm 9 and the mounting position P4 of the light receiver 32.

  Further, the present embodiment includes a correction command means for instructing execution of correction by the bucket height correction means 29, and a cancellation means for canceling execution of correction. These correction command means and cancellation means are correction command switches 25 that are provided in the vicinity of the input operation unit 23 of the reference height input device 22 and are turned on / off by a pressing operation, for example, as shown in FIG. The correction command switch 25 is connected to the computer 26. The computer 26 executes correction by the bucket height correcting means 29 when the correction command switch 25 is turned on, and cancels the correction when the correction command switch 25 is turned off.

  Here, the calculation processing procedure of the computer 26 will be described with reference to FIGS.

  As shown in FIG. 6, the computer 26 calculates the three-dimensional position of the vehicle body, that is, the three-dimensional position (X0, Y0, Z0) of the pivot center P0 of the boom 8 by the vehicle body position calculation means 27 (step S1). ). Next, the three-dimensional position (X3, Y3, Z31) of the toe P3 of the bucket 10 is calculated by the bucket position calculation means 28 (step S2). Next, when the correction command switch 25 is turned on (YES in step S3), the bucket height correcting unit 29 corrects the height Z31 of the toe P3 of the bucket 10, and the process returns to step S1. If the correction command switch 25 is not turned on (NO in step S3), steps S1 and S2 are repeated.

  The calculation process of step S4 will be described in detail. As shown in FIG. 7, the bucket height correcting means 29 calculates the receiver height Z4 (STEP 41). Next, the reference height Zb input by the reference height input unit 22 is read (STEP 42). Next, “Zb−Z4” is calculated to calculate the correction value Zc (STEP 43). Next, “Z31−Zc” is calculated to calculate the toe height Z32, that is, the toe height Z31 calculated by the bucket position calculation means 28 is corrected to the toe height Z32 by the correction value Zc (STEP 45). .

  The present embodiment configured as described above operates as follows.

  When the excavator 1 is started, the GPS antenna devices 16 and 17 each measure their own three-dimensional position and output a position signal to the computer 26. Accordingly, the computer 26 calculates the three-dimensional position (X0, Y0, Z0) of the rotation center P0 of the boom 8 by the vehicle body position calculation means 27.

  The boom angle detector 18 detects the rotation angle α of the boom 8 and outputs a boom angle signal to the computer 26. The arm angle detector 19 detects the rotation angle β of the arm 9 and outputs an arm angle signal to the computer 26. The bucket angle detector 20 detects the rotation angle γ of the bucket 10 and outputs a bucket angle signal to the computer 26. The inclination angle detector 21 detects the inclination angle of the revolving structure 3 in the front-rear direction and outputs an inclination angle signal to the computer 26. Accordingly, the computer 26 calculates the three-dimensional position (X0, Y0, Z0) of the rotation center P0 of the boom 8 calculated by the vehicle body position calculation means 27, the rotation angle α of the boom 8, and the rotation angle of the arm 9. The three-dimensional position (X3, Y3, Z31) of the toe P3 of the bucket 10 is calculated by the bucket position calculation means 28 based on β, the rotation angle γ of the bucket 10 and the inclination angle of the swing body 3. The calculation of the three-dimensional position of the toe P3 is repeatedly performed every predetermined time.

  Before the excavation work is performed, the operator operates the working device 7 and applies the laser 31 emitted from the laser generator 30 installed at the reference position Pb to the light receiving unit 36 of the light receiving device 32 to notify the notification device 40. The lamp 44 is turned on. That is, the light receiver 32 is arranged at the same height as the reference position Pb.

  Next, the operator operates the input operation unit 23 of the reference height input device 22 to input the reference height Zb, and then turns on the correction command switch 25. Accordingly, the computer 26 corrects the toe height Z31 to the toe height Z32 by the bucket height correcting means 29. That is, the three-dimensional position (X3, Y3, Z31) of the toe P3 calculated by the bucket position calculating means 28 is corrected to the three-dimensional position (X3, Y3, Z32), and the three-dimensional position of the toe P3 is measured. finish.

  When the measurement of the three-dimensional position of the toe P3 of the bucket 10 is thus completed, the computer 26 outputs a bucket position signal indicating the three-dimensional position (X3, Y3, Z32) of the toe P3 to the hydraulic control device 14. As a result, the hydraulic excavator 1 compares the height Z32 indicated by the bucket position signal with the excavation depth D set by the excavation area setting unit 15 by the hydraulic control device 14, and the toe P3 of the bucket 10 excavates. The boom cylinder 11, the arm cylinder 12 and the bucket cylinder 13 are controlled so as not to move to a position exceeding the depth D.

  According to this embodiment, the following effects can be obtained.

  In the present embodiment, the toe height Z31 calculated by the bucket position calculation means 28 is corrected to the toe height Z32 by the bucket height correction means 29 in a state where the light receiver 32 is disposed at the reference height Zb. As a result, the play of the pin coupling portion between the boom 8 and the revolving structure 3, the play of the pin coupling portion between the arm 9 and the boom 8, the detection error of the boom angle detector 18, and the detection error of the arm angle detector 19 are accumulated. The measurement error at the measurement point in the height direction of the toe P3 of the bucket 10 can be eliminated. As a result, the measurement accuracy of the measurement point in the height direction of the toe P3 of the bucket 10 can be improved.

  Moreover, in this embodiment, since the laser generator 30 installed in the reference position Pb, the light receiver 32 attached to the working device 7, and the notification device 40 for notifying that the light receiver 32 has received the laser are provided. It is easy to arrange a predetermined portion of the working device 7 at the reference height Zb.

  In the present embodiment, the correction command switch 25 can be used to command or cancel the execution of correction by the bucket height correction means 29. Therefore, the measurement accuracy of the height of the toe P3 of the bucket 10 can be changed to the contents of excavation work. Can be selected accordingly.

  In addition, although this embodiment is an example provided with GPS antenna apparatus 16 and 17 as a positioning means which measures the three-dimensional position in the predetermined location of a vehicle body, the positioning means of this invention is not restricted to this example, hydraulic pressure Any means that measures the three-dimensional position based on radio waves, lasers, and the like emitted from a plurality of positions outside the excavator 1 may be used.

  Moreover, although this embodiment is an example provided with the boom angle detector 18, the arm angle detector 19, and the bucket angle detector 20 as a state quantity detection means which detects the state quantity regarding the attitude | position of the working device 7, this invention. The state quantity detection means is not limited to this example, but a displacement sensor that detects the extension amount of the boom cylinder 11, a displacement sensor that detects the extension amount of the arm cylinder 12, and a displacement that detects the extension amount of the bucket cylinder 13. It may be a sensor.

  Moreover, although this embodiment is an example provided with the reference | standard height input device 22 provided in the cab 4 as a means to input reference | standard height, this invention is not limited to this, The hydraulic shovel 1 of the excavator 1 is provided. It may be a means for inputting a reference height from outside using radio.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a hydraulic excavator to which an embodiment of a work tool position measuring device for a work machine according to the present invention is applied. It is a block diagram which shows the system configuration | structure of one Embodiment of this invention. It is a figure which shows the reference | standard height input device and correction command switch which are shown in FIG. 1 is an enlarged view of the light receiver and the alarm shown in FIG. 1, (a) is a diagram showing the light receiver and the alarm seen from the laser generator side, and (b) is the light receiver and the alarm seen from the cab side. FIG. It is a figure which shows the angle and dimension used when calculating the three-dimensional position of the toe of a bucket with the computer shown in FIG. It is a flowchart which shows the procedure of the arithmetic processing performed by the computer shown in FIG. It is a flowchart which shows the detail of the arithmetic processing performed in procedure S4 shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydraulic excavator 2 Running body 3 Revolving body 4 Operator's room 5 Machine room 6 Counterweight 7 Working device 8 Boom 9 Arm 10 Bucket 11 Boom cylinder 12 Arm cylinder 13 Bucket cylinder 14 Hydraulic control device 15 Excavation area setting device 16, 17 GPS antenna Device 18 Boom angle detector 19 Arm angle detector 20 Bucket angle detector 21 Inclination angle detector 22 Reference height input device 23 Input operation unit 24 Display unit 25 Correction command switch 26 Computer 27 Car body position calculation means 28 Bucket position calculation means 29 Bucket height correction means 30 Laser generator 31 Laser 32 Light receiver 33-39 Light receiver 40 Alarm 41-47 Notification lamp

Claims (4)

Positioning means for positioning a three-dimensional position at a predetermined position of the body of the work machine, state quantity detecting means for detecting a state quantity relating to the posture of an articulated work device having a work tool at the tip, and positioning by the positioning means. And a work tool position calculating means for calculating a three-dimensional position of the work tool based on a three-dimensional position at a predetermined position of the vehicle body and a state quantity related to the posture of the work device detected by the state quantity detecting means. In the position measuring device of the work tool of the work machine provided,
3D at a predetermined position of the vehicle body measured by the positioning means in a state where the predetermined position of the working device is arranged at the same height position as a reference position whose height is measured in advance outside the work machine. The position of the work tool based on the difference between the height of the predetermined position of the work device calculated based on the position and the state amount related to the posture of the work device detected by the state amount detection means and the height of the reference position A work tool position measuring device for a work machine, comprising: a work tool height correcting unit that corrects the height of the work tool calculated by a calculation unit. In the invention of claim 1,
Laser generating means for emitting a laser in a horizontal direction from the reference position, light receiving means for receiving a laser provided at a predetermined position of the working device, and notification means for notifying that the light receiving means has received the laser. An apparatus for measuring a position of a work implement of a work machine. In the invention of claim 1,
An apparatus for measuring a position of a work tool of a work machine, comprising: correction command means for instructing execution of correction by the work tool height correction means; and cancellation means for canceling execution of correction. In the invention of claim 1,
The working device includes a boom coupled to the vehicle body so as to be pivotable in the vertical direction, and an arm coupled so as to be pivotable in the boom vertical direction,
A position measurement device for a work implement of a work machine, wherein the predetermined portion of the work device is a portion included in the arm.

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