System for calibrating construction machine and method for calibrating construction machine

Abstract

This system for calibrating a construction machine comprises: a reference axis generator 201 for setting a reference axis 230 comprising a vertical axis or a horizontal axis on movable parts 111-113; an external measurement device 301 for measuring the relative position between the reference axis 230 and a mark 200 provided on the movable parts 111-113; and a calibration device 401 for calculating a calibration value of an attachment angle parameter 251 on the basis of positional relationships among the reference axis 230, the mark 200, and straight lines preset on the movable parts 111-113. Accordingly, the work of calibrating a parameter indicating the attachment angle of an angle sensor installed on a work machine is easily performed.

Description

Calibration system for construction machine and calibration method for construction machine

[0001] The present invention relates to a system and method for calibrating a parameter indicating the mounting angle of an angle sensor installed in a work machine provided in a construction machine such as a hydraulic excavator.

[0002] Among construction machines, there are excavators equipped with machine guidance functions that calculate the position and attitude of working implements such as booms, arms, and buckets and present the relative position of the work implements to the operator, as well as machine control functions that control the work implements to move along the target construction surface. To achieve high-quality construction, it is necessary to improve the measurement accuracy of the work implement's position and attitude. Generally, to calculate the position and attitude of the work implement, an inclination sensor such as an inertial measurement unit (IMU) is installed on the work implement, and the detected angle of the inclination sensor is used. To accurately detect the position and attitude of the work implement from the detected angle of the inclination sensor, it is necessary to calibrate a parameter (mounting angle parameter) that indicates the mounting angle of the inclination sensor relative to the work implement. Patent Document 1, for example, is a prior art document that discloses a method for calibrating the mounting angle parameter of an inclination sensor.

[0003] Patent Document 1 discloses a construction machine having a vehicle body, a first moving part rotatably supported on the vehicle body, a second moving part rotatably supported on the first moving part, a third moving part rotatably supported on the second moving part, a first angle detection part attached to the first moving part at a first attachment angle and detecting the tilt angle of the first moving part, a second angle detection part attached to the second moving part at a second attachment angle and detecting the tilt angle of the first moving part, a third angle detection part attached to the third moving part at a third attachment angle and detecting the tilt angle of the first moving part, and a calculation device configured to calculate a preset position on the third moving part based on the first to third attachment angles, the tilt angles of the first to third moving parts detected by the first to third angle detection parts, and dimensional information of the first to third moving parts. The present invention discloses a calibration method for a construction machine for calibrating a first mounting angle (mounting angle parameter), the method comprising: a first step of measuring, by an external measuring device, a first measurement point on the rotation axis of the first moving part relative to the front vehicle body, a second measurement point on the rotation axis of the second moving part relative to the first moving part, a third measurement point on the rotation axis of the third moving part relative to the second moving part, and a fourth measurement point on the third moving part; a second step of calculating, by the computing device, the tilt angles of the first to third moving parts based on at least the first to fourth measurement points measured in the first step; and a third step of calculating the first to third mounting angles (mounting angle parameter) based on the tilt angles of the first to third moving parts calculated in the second step and the tilt angles detected by the first to third angle detection parts.

[0004] JP 2017-181340 A

[0005] However, to measure the position of measurement points such as the boom foot pins of a work machine, a prism installed at the measurement point is typically measured using a total station. However, in this case, measurement errors increase as the laser incident angle on the prism increases. Therefore, when measuring prisms installed at both ends of a large work machine, the total station must be placed away from the work machine to prevent the laser incident angle on the prism from becoming too large, which can make calibration difficult in places with limited work space. Furthermore, depending on the model of construction machine, the boom foot pin, which is the rotation axis connecting the work machine (boom) to the vehicle body, is hidden by the vehicle body structure, preventing the laser from reaching the boom foot pin. Therefore, in order to reach the measurement point on the boom foot pin, it is necessary to remove the vehicle body structure or install dedicated equipment at the measurement point. Thus, the calibration method of Patent Document 1, which places the measurement point on the rotation axis of the work machine, can be time-consuming.

[0006] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a construction machine calibration system and a construction machine calibration method that enable easy calibration of parameters that indicate the mounting angle of an angle sensor installed on a work machine.

[0007] In order to achieve the above object, the present invention provides a construction machine calibration system that calibrates the mounting angle parameter of a construction machine that includes a vehicle body, an articulated work machine rotatably supported on the vehicle body, an angle detector installed on a movable part of the work machine and that detects the inclination angle of the work machine relative to a horizontal axis, and a controller that calculates the attitude of the movable part based on the angle detected by the angle detector and a mounting angle parameter that indicates the mounting angle of the angle detector.The system comprises a reference axis generator that sets a reference axis consisting of a vertical axis or a horizontal axis on the movable part, an external measurement device that measures the relative position between a mark on the movable part and the reference axis, and a calibration device that calculates a calibration value of the mounting angle parameter based on the positional relationship between the reference axis, the mark, and a straight line that is preset on the movable part.

[0008] Further, the present invention provides a construction machine calibration method for calibrating an installation angle parameter for a construction machine including a vehicle body, an articulated work machine rotatably supported on the vehicle body, an angle detector installed on a movable part of the work machine and detecting the inclination angle of the work machine relative to a horizontal axis, and a controller that calculates the attitude of the movable part based on the angle detected by the angle detector and an installation angle parameter that indicates the installation angle of the angle detector, the method comprising: a first step of setting a reference axis consisting of a vertical axis or a horizontal axis on the movable part; a second step of measuring the relative position between a mark on the movable part and the reference axis; and a third step of calculating a calibration value of the installation angle parameter based on the positional relationship between the reference axis, the relative position, and a straight line that is set in advance on the movable part.

[0009] According to the present invention, when calibrating parameters indicating the mounting angle of an angle detector installed on a work machine, the measurement points using an external measuring device are concentrated near the marks on the movable part, eliminating the need to measure the positions of the rotating shafts at both ends of the movable part of the work machine, making it possible to perform the calibration work easily.

[0010] FIG. 1 is a diagram showing an overview of a hydraulic excavator; FIG. 2 is a diagram showing an overview of a control system for a hydraulic excavator; FIG. 3 is a diagram showing a calibration operation; FIG. 4 is a diagram showing a calibration system; FIG. 5 is a diagram showing a modified example of the calibration system;

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the same components are designated by the same reference numerals throughout the drawings, and duplicated explanations will be omitted. [Configuration] First, the schematic configuration of a hydraulic excavator 100 (construction machine) used in this embodiment will be described with reference to FIG. 1. FIG. 1 is a diagram showing an overview of the hydraulic excavator 100. The hydraulic excavator 100 includes an articulated work machine 110 and a vehicle body 130.

[0012] The vehicle body 130 includes a lower traveling body 132 and an upper rotating body 131 mounted on the lower traveling body 132. The upper rotating body 131 rotates when driven by a rotation motor 124. The lower traveling body 132 travels in the forward and backward directions when driven by a right traveling motor 125 and a left traveling motor 126 (see FIG. 2).

[0013] The work machine 110 is a device for performing excavation, earth loading, and the like, and includes a boom 111 (movable part) whose base end is rotatably connected to an upper rotating body 131, an arm 112 (movable part) rotatably connected to the tip of the boom 111, and a bucket 113 (movable part) rotatably connected to the tip of the arm 112. The boom 111 is driven by a boom cylinder 121, the arm 112 is driven by an arm cylinder 122, and the bucket 113 is driven by a bucket cylinder 123. The tip of the bucket cylinder 123 is rotatably connected to the tip of the arm 112 via a bucket link 113a (movable part). The bucket link 113a constitutes part of the bucket 113.

[0014] The upper rotating body 131 also includes a cab 151. The cab 151 is equipped with an operating lever 152, a monitor 153, and a buzzer 154 (see FIG. 2).

[0015] The boom 111 is provided with a boom angle detector 181 (angle detector) that detects the attitude of the boom 111. The arm 112 is provided with an arm angle detector 182 (angle detector) that detects the attitude of the arm 112. The bucket link 113a is provided with a bucket angle detector 183 (angle detector) that detects the attitude of the bucket 113. The upper rotating body 131 is provided with a rotation angle detector 184 that detects the attitude (rotation angle) of the upper rotating body 131, a right GNSS receiver 171, a left GNSS receiver 172, and an attitude detection device 173 that detects the inclination angle of the vehicle body 130 with respect to the direction of gravity. The attitude detection device 173 and the angle detectors 181 to 184 are configured, for example, by an IMU (Inertial Measurement Unit) or the like. The angle detectors 181 to 183 detect their own inclination angles with respect to the horizontal axis. The information controller 161, which will be described later, calculates the attitudes (ground angles) of the movable parts 111 to 113 by subtracting pre-stored parameters (mounting angle parameters) indicating the mounting angles of the angle detectors 181 to 183 from the angles detected by the angle detectors 181 to 183. Therefore, in order to detect the accurate attitudes of the movable parts 111 to 113, it is necessary to match the mounting angle parameters with the actual mounting angles of the angle detectors 181 to 183 (to calibrate the mounting angle parameters). [Control System] Next, an overview of the control system for the hydraulic excavator 100 will be described with reference to FIG. 2. FIG. 2 is a diagram showing an overview of the control system for the hydraulic excavator 100.

[0016] As shown in Fig. 2, the hydraulic excavator 100 further includes an engine 143, a hydraulic pump 142, a control valve 141, a main controller 162, and an information controller 161. The hydraulic pump 142 is operated by power from the engine 143. When the operator operates the control lever 152, the operation information is converted into a control signal by the main controller 162. The control signal is sent to the hydraulic pump 142, the control valve 141, and the engine 143, which drive the swing motor 124, the right traveling motor 125, the left traveling motor 126, the boom cylinder 121, the arm cylinder 122, and the bucket cylinder 123.

[0017] Furthermore, in accordance with the design surface information and bucket tip position information transmitted from the information controller, the main controller 162 adjusts the control signals so that the smaller the deviation between the design surface and the bucket tip position, the more it limits the operating speeds of the boom cylinder 121, arm cylinder 122, and bucket cylinder 123, in order to prevent the bucket from digging too deep.

[0018] The information controller 161 is configured using a computer in which a CPU 1611 , a RAM 1612 , a ROM 1613 and an external I / F 1614 are connected to one another via a bus 1615 .

[0019] The external I / F 1614 is connected to the main controller 162, the buzzer 154, the monitor 153, and the storage medium 155. The information controller 161 presents information to the operator via the buzzer 154 and the monitor 153, and outputs control instructions for the control valve 141 to the main controller 162.

[0020] In addition, the external I / F 1614 is connected to the right GNSS receiver 171, the left GNSS receiver 172, the attitude detection device 173, and the angle detectors 181 to 184.

[0021] The information controller 161 is also connected to a wireless communication device 157 that transmits and receives design surfaces, correction signals for RTK-GNSS positioning, terrain shape information, and control data to and from external parties outside the hydraulic excavator 100 (for example, a control server or other construction machinery). The wireless communication device 157 is a communication device that connects to a wireless LAN, Wi-Fi, Bluetooth (registered trademark), a mobile line, or the like. The wireless communication device 157 and the monitor 153 correspond to output devices that are the output destinations of the bucket tip position and design surfaces determined by the information controller 161, and the detected angles required for the calibration process of the mounting angle parameters of the angle detectors 181 to 183. [Calibration System and Calibration Method] Hereinafter, a system (calibration system) and a method (calibration method) for calibrating the mounting angle parameters of the angle detectors 181 to 183 installed on the work machine 110 will be described with reference to FIGS. 3 to 8.

[0022] FIG. 3 is a diagram illustrating a calibration operation. In this embodiment, when calibrating the mounting angle parameters of the boom angle detector 181, a reference axis is set on a marker 200 affixed or printed on the side of the boom 111 using a reference axis generator 201. In this embodiment, a vertical axis is used as the reference axis 230, but a horizontal axis may also be used. The reference axis generator 201 may be, for example, a laser projector marking device used in construction and civil engineering. A laser projector marking device has an internal tilt sensor and can set a reference line on the marker 200 by projecting a linear laser beam that extends horizontally or vertically relative to the ground onto the marker 200. The reference axis generator 201 is not limited to a laser projector marking device, and a plumb bob may also be used. The plumb bob can set a reference axis on the marker 200 by overlapping a plumb line stretched vertically with the marker 200 as viewed from the camera 301.

[0023] The marker 200 is a mark for measuring the ground angle of the boom 111. The mark is not limited to the marker 200, but may be an uneven surface on the side of the movable parts 111 to 113 or a logo such as a company name. The shape of the marker 200 in this embodiment is a rectangle having four vertices 200a to 200d as shown in FIG.

[0024] 4 shows a calibration system 400 according to this embodiment. The calibration system 400 includes a calibration device 401, a reference axis generator 201, and a camera 301.

[0025] The calibration device 401 is configured as a computer including a CPU 402, a RAM 403, a ROM 404, a wireless communication device 405, a storage medium 406, and an external I / F 407. The CPU 402, the RAM 403, the ROM 404, the wireless communication device 405, and the external I / F 407 are connected to one another via a bus 408. The calibration device 401 in this embodiment is assumed to be configured as a tablet, a smartphone, or the like that can be easily carried by a worker who performs the calibration work, but the form and configuration of the calibration device 401 are not limited to these.

[0026] The ROM 404 or storage medium 406 stores the shape and dimensions of the marker 200, and a marker relative angle 242 (mark relative angle), which is the angle between a line (line segment AB) connecting point A on the base-end rotation shaft 210 of the boom 111 and point B on the tip-end rotation shaft 211, and a line connecting two vertices 200c, 200d of the marker 200. Note that, if the irregularities on the side surfaces of the movable parts 111-113 are used as marks instead of the marker 200, the angle formed by the line segment AB and a line connecting two points on the irregularities whose positions can be identified by the camera 301 is stored instead of the marker relative angle 242. Note that, if a logo of a company name or the like is used as a mark instead of the marker 200, the angle formed by the line segment AB and a line connecting two points on the logo whose positions can be identified by the camera 301 is stored instead of the marker relative angle 242.

[0027] The wireless communication device 405 performs wireless communication with the wireless communication device 157 mounted on the construction machine 100, and acquires the angles detected by the angle detectors 181 to 183 required for calibration.

[0028] In this embodiment, a camera 301 independent of the calibration device 401 is used as the external measurement device, but a camera 409 built into the calibration device 401 as shown in Figure 5 may also be used, or other measurement devices such as a total station may also be used.

[0029] The calibration method will be described below with reference to Figures 6 to 8. Figure 6 shows a flowchart of the calibration method, Figure 7 shows images of marker 200 and reference axis 230 captured by camera 301, and Figure 8 shows a method for calculating the mounting angle parameters of boom angle detector 181. Here, the method for calibrating the mounting angle parameters of boom angle detector 181 will be described, but the same applies to the arm angle detector 182 and bucket angle detector 183.

[0030] First, the reference axis generator 201 is used to set the reference axis 230 on the marker 200 (step S601).

[0031] Following step S601, the camera 301 measures the relative position between the marker 200 and the reference axis 230 generated by the reference axis generator 201 (step S602). When the camera 301 is directly facing the marker 200 and the reference axis 230, the distance from the camera 301 to each of the vertices 200a to 200d of the marker 200 is uniform, and the shape of the photographed marker 200 is not distorted. However, when the camera 301 is not directly facing the marker 200 and the reference axis 230, the distance from the camera 301 to each of the vertices 200a to 200d of the marker 200 becomes non-uniform, and the shape of the marker 200 is distorted as shown in FIG. 7. Therefore, the image distortion is corrected based on the marker shape information recorded in the calibration device 401 so that the shape shown in FIG. 8 is obtained. Image distortion correction can be performed by detecting the vertices 200a to 200d of the marker 200 in the image and converting them so that they match the marker shape recorded in the calibration device 401. Note that other distortion correction methods may also be used.

[0032] Following step S602, the calibration device 401 detects the reference axis 230 from the distortion-corrected image and calculates the angle between the reference axis 230 and the line connecting the two vertices 200c, 200d on the marker 200 as the marker-to-reference axis angle 240 (movable part-to-reference axis angle) (step S603).

[0033] Following step S603, the calibration device 401 acquires the marker relative angle 242 recorded in the calibration device 401 (step S604).

[0034] Following step S604, the calibration device 401 calculates the difference between the marker-to-reference axis angle 240 calculated in step S603 and the marker relative angle 242 acquired in step S604 as the boom-to-reference axis angle 241 (movable part-to-reference axis angle) (step S605).

[0035] Following step S605, the calibration device 401 acquires the detected angle 233 of the boom angle detector 181 and calculates the angle detector-to-reference axis angle 250, which is the tilt angle of the boom angle detector 181 with respect to the reference axis 230 (step S606). In this embodiment, the vertical axis 231 is used as the reference axis 230, so the angle detector-to-reference axis angle 250 is obtained by adding 90 degrees to the detected angle 233. Note that if the horizontal axis 232 is used as the reference axis 230, the detected angle 233 becomes the angle detector-to-reference axis angle 250 as is.

[0036] Following step S606, the calibration device 401 calculates the difference between the angle detector-to-reference shaft angle 250 acquired in step S605 and the boom-to-reference shaft angle 241 calculated in step S604 as the calibration value of the mounting angle parameter 251 of the angle detector 181 (step S607), and ends this flow. The calculated calibration value of the mounting angle parameter 251 is recorded in the ROM 404 or storage medium 406 in the calibration device 401, and is also transmitted to the information controller 161 using the wireless communication device 405. The information controller 161, which has received this updated value, updates the value of the mounting angle parameter 251 stored therein with this calibrated value.

[0037] (Summary) In this embodiment, a construction machine 100 is provided with a vehicle body 130, an articulated work machine 110 rotatably supported on the vehicle body 130, angle detectors 181 to 183 installed on movable parts 111 to 113 of the work machine 110 to detect the inclination angle of the work machine 110 relative to a horizontal axis, and a controller 161 that calculates the attitude of the movable parts 111 to 113 based on a detected angle 233 of the angle detectors 181 to 183 and an attachment angle parameter 251 that indicates the attachment angle of the angle detectors 181 to 183. A calibration system 400 for calibrating an attachment angle parameter 251 includes a reference axis generator 201 that sets a reference axis 230 consisting of a vertical axis or a horizontal axis on the movable parts 111 to 113, an external measurement device 301 that measures the relative position of a mark 200 on the movable parts 111 to 113 and the reference axis 230, and a calibration device 401 that calculates a calibration value of the attachment angle parameter 251 based on the positional relationship between the reference axis 230, the mark 200, and a straight line that is set in advance on the movable parts 111 to 113.

[0038] Furthermore, in this embodiment, the calibration device 401 calculates a mark-to-reference axis angle 240, which is the angle between the mark 200 and the reference axis 230, based on the relative position of the mark 200 and the reference axis 230 measured by the external measurement device 301, and calculates a difference between the mark relative angle 242, which is the angle between the mark 200 and the line connecting the first points A, B, and C and the second points B, C, and D on the movable parts 111 to 113, and the mark-to-reference axis angle 240, as a movable part-to-reference axis angle 241, which is the angle between the movable parts 111 to 113 and the reference axis 230, and calculates an angle detector-to-reference axis angle 250, which is the tilt angle of the angle detectors 183 to 185 with respect to the reference axis 230, based on the reference axis 230 and the detection angle 233, and calculates the difference between the angle detector-to-reference axis angle 250 and the movable part-to-reference axis angle 241 as the calibration value.

[0039] In this embodiment, the construction machine 100 includes a vehicle body 130, an articulated work machine 110 rotatably supported on the vehicle body 130, angle detectors 181 to 183 installed on movable parts 111 to 113 of the work machine 110 to detect the inclination angle of the work machine itself relative to the horizontal axis, and a controller 16 that calculates the attitude of the movable parts 111 to 113 based on a detected angle 233 of the angle detectors 181 to 183 and a mounting angle parameter 251 that indicates the mounting angle of the angle detectors 181 to 183. This construction machine calibration method for calibrating a meter 251 includes a first step S601 of setting a reference axis 230 consisting of a vertical axis or a horizontal axis on the movable parts 111 to 113, a second step S602 of measuring the relative position of a mark 200 on the movable parts 111 to 113 and the reference axis 230, and third steps S603 to S607 of calculating a calibration value of the mounting angle parameter 251 based on the positional relationship between the reference axis 230, the mark 200, and a straight line set in advance on the movable parts 111 to 113.

[0040] In this embodiment, the third steps S603 to S607 include a fourth step S603 of calculating a mark-to-reference axis angle 240, which is the angle between the mark 200 and the reference axis 230, based on the relative positions of the mark 200 and the reference axis 230; and a fourth step S604 of calculating a difference between the mark relative angle 242, which is the angle between the mark 200 and a line connecting the first points A, B, and C and the second points B, C, and D on the movable parts 111 to 113, and the mark-to-reference axis angle 240. The method includes a fifth step S605 of calculating a movable part to reference axis angle 241, which is the angle formed with the reference axis 230; a sixth step S606 of calculating an angle detector to reference axis angle 250, which is the tilt angle of the angle detectors 183 to 185 with respect to the reference axis 230, based on the reference axis 230 and the detected angle 233; and a seventh step S607 of calculating the difference between the angle detector to reference axis angle 250 and the movable part to reference axis angle 241 as the calibration value.

[0041] According to this embodiment configured as described above, when calibrating the mounting angle parameters of the angle detectors 181 to 183 installed on the work machine 110, the measurement points by the external measuring device 301 are concentrated near the marks 200 on the movable parts 111 to 112, and there is no need to measure the positions of the rotation axes 210 to 213 at both ends of the movable parts 111 to 112 of the work machine 110, making it possible to perform the calibration work easily.

[0042] In this embodiment, the first points A, B, and C are points on one of the rotation axes 210, 211, and 212 of the movable parts 111 to 113, and the second points B, C, and D are points on the other of the rotation axes 211, 212, and 213 of the movable parts 111 to 113. This makes it possible to define the mounting angle parameter 251 of the angle detectors 181 to 183 as a relative angle with respect to a line connecting a point on one of the rotation axes 210, 211, and 212 of the movable parts 111 to 113 and a point on the other of the rotation axes 211, 212, and 213.

[0043] In this embodiment, the reference axis generator 201 is configured with a laser projector mark or a plumb bob, which makes it possible to align the reference axis 230 with the movable parts 111 to 113 with high precision.

[0044] In this embodiment, the mark 200 is configured by a marker 200 attached to or printed on the movable parts 111 to 113. This makes it possible to measure the angles of the movable parts 111 to 113 with respect to the ground with high accuracy.

[0045] In this embodiment, the shape of the marker 200 is a rectangle having four vertices 200a to 200d, which makes it possible to correct distortion of the marker 200 captured by the camera 301.

[0046] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those having all of the described configurations.

[0047] 100... Hydraulic excavator (construction machine), 110... Work machine, 111... Boom (movable part), 112... Arm (movable part), 113... Bucket (movable part), 113a... Bucket link (movable part), 121... Boom cylinder, 122... Arm cylinder, 123... Bucket cylinder, 124... Swing motor, 125... Right traveling motor, 126... Left traveling motor, 130... Vehicle body, 131... Upper rotating body, 132... Lower traveling body, 141 ...Control valve, 142...Hydraulic pump, 143...Engine, 151...Driver's cab, 152...Operating lever, 153...Monitor, 154...Buzzer, 155...Storage medium, 157...Wireless communication device, 161...Information controller, 162...Main controller, 171...Right GNSS receiver, 172...Left GNSS receiver, 173...Attitude detection device, 181...Boom angle detector, 182...Arm angle detector, 183...Bucket Angle detector, 184... turning angle detector, 200... marker (mark), 200a... vertex, 200a to 200d... vertices, 201... reference axis generator, 210 to 213... rotation axis, 230... reference axis, 231... vertical axis, 232... horizontal axis, 233... detected angle, 240... marker to reference axis angle (mark to reference axis angle), 241... boom to reference axis angle (movable part to reference axis angle), 242... marker relative angle (mark relative angle), 250... angle Detector-to-reference axis angle, 251...mounting angle parameters, 301...camera (external measurement device), 400...calibration system, 401...calibration device, 402...CPU, 403...RAM, 404...ROM, 405...wireless communication device, 406...storage medium, 407...external I / F, 408...bus, 409...camera (external measurement device), 1611...CPU, 1612...RAM, 1613...ROM, 1614...external I / F, 1615...bus.

Claims

1. A calibration system for a construction machine that calibrates an installation angle parameter for a construction machine that includes a vehicle body, an articulated work machine rotatably supported on the vehicle body, an angle detector installed on a movable part of the work machine and that detects the inclination angle of the work machine relative to a horizontal axis, and a controller that calculates the attitude of the movable part based on the angle detected by the angle detector and an installation angle parameter that indicates the installation angle of the angle detector, the calibration system for a construction machine comprising: a reference axis generator that sets a reference axis consisting of a vertical axis or a horizontal axis on the movable part; an external measurement device that measures the relative position between a mark on the movable part and the reference axis; and a calibration device that calculates a calibrated value of the installation angle parameter based on the positional relationship between the reference axis, the mark, and a straight line that is preset on the movable part.

2. A calibration system for construction machinery as described in claim 1, wherein the calibration device calculates a mark-to-reference axis angle, which is the angle between the mark and the reference axis, based on the relative position of the mark and the reference axis measured by the external measuring device; calculates a movable part-to-reference axis angle, which is the angle between the movable part and the reference axis, as the difference between a mark relative angle, which is the angle between the mark and a line connecting a first point and a second point on the movable part, and the mark-to-reference axis angle; calculates an angle detector-to-reference axis angle, which is the tilt angle of the angle detector with respect to the reference axis, based on the reference axis and the detected angle; and calculates the difference between the angle detector-to-reference axis angle and the movable part-to-reference axis angle as the calibration value.

3. A calibration system for a construction machine according to claim 2, wherein the first point is a point on one of the rotation axes of the movable part, and the second point is a point on the other of the rotation axes of the movable part.

4. A calibration system for construction machinery according to claim 1, characterized in that the reference axis generator is configured as a laser projector type marking device or a plumb bob.

5. A calibration system for a construction machine according to claim 1, characterized in that the mark is composed of a marker attached or printed on the movable part.

6. A calibration system for a construction machine according to claim 5, wherein the shape of the marker is a rectangle having four vertices.

7. A method for calibrating a construction machine comprising a vehicle body, an articulated work machine rotatably supported on the vehicle body, an angle detector installed on a movable part of the work machine and detecting the inclination angle of the work machine relative to a horizontal axis, and a controller for calculating the attitude of the movable part based on the angle detected by the angle detector and an installation angle parameter indicating the installation angle of the angle detector, the method comprising: a first step of setting a reference axis consisting of a vertical axis or a horizontal axis on the movable part; a second step of measuring the relative position between a mark on the movable part and the reference axis; and a third step of calculating a calibrated value of the installation angle parameter based on the positional relationship between the reference axis, the relative position, and a straight line previously set on the movable part.

8. A method for calibrating a construction machine as set forth in claim 7, wherein the third step comprises: a fourth step of calculating a mark-to-reference axis angle, which is the angle between the mark and the reference axis, based on the relative position of the mark and the reference axis; a fifth step of calculating a movable part-to-reference axis angle, which is the angle between the movable part and the reference axis, as the difference between the mark relative angle, which is the angle between the mark and a line connecting a first point and a second point on the movable part, and the mark-to-reference axis angle; a sixth step of calculating an angle detector-to-reference axis angle, which is the tilt angle of the angle detector with respect to the reference axis, based on the reference axis and the detected angle; and a seventh step of calculating the difference between the angle detector-to-reference axis angle and the movable part-to-reference axis angle as the calibration value.

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