Work machine

Abstract

This work machine comprises: a work device having a front member; an acceleration sensor and an angular velocity sensor attached to the front member; and a controller that calculates the attitude of the work device using dimensional data of the work device and outputs from the acceleration sensor and the angular velocity sensor, wherein the controller, on the basis of measurement states of the acceleration sensor and the angular velocity sensor, the calculated attitude of the work device, and a plurality of target attitudes of the work device for calibration of errors of the acceleration sensor and the angular velocity sensor, outputs, to a display device, an operation instruction to an operator for any of the plurality of target attitudes and a stationary instruction to the operator in any of the plurality of target attitudes.

Description

Work machine

[0001] The present invention relates to a work machine having an angular velocity sensor and an acceleration sensor.

[0002] Some work machines have a working device. For example, a hydraulic excavator has a working device (also referred to as a front working device) in front of the vehicle body.

[0003] In a hydraulic excavator, in order to measure the posture of the working device, attitude sensors such as an IMU (Inertial Measurement Unit) are mounted on each front member (for example, boom, arm, and attachment (for example, bucket)) constituting the working device and on the vehicle body to which the front working device is attached. The posture of each front member and the vehicle body can be measured from the detection values of each attitude sensor, and the position and posture of the front working device in a predetermined coordinate system (for example, a coordinate system set on the vehicle body) can be calculated.

[0004] The IMU consists of an acceleration sensor and an angular velocity sensor, and by fusing the inclination angle obtained by the acceleration sensor at rest and the angle change amount calculated from the integrated value of the angular velocity obtained by the angular velocity sensor during operation, the attitude angles of each front member and the vehicle body can be obtained.

[0005] By the way, the measurement accuracy of the angle by the IMU depends on the performance of the acceleration sensor and the angular velocity sensor. The zero offset error of the acceleration sensor and the scale factor error of the angular velocity sensor may cause a decrease in the measurement accuracy of the attitude angle over time depending on the use environment and storage environment. Therefore, it is necessary to calibrate the IMU regularly (check the zero offset error and scale factor error). As a technique for calibrating the IMU on a hydraulic excavator, for example, there is one disclosed in Patent Document 1.

[0006] According to Patent Document 1, the zero offset error of the acceleration and the scale factor error of the angular velocity are estimated using the values of the acceleration when the front working device is stationary in three or more postures and the value of the angular velocity when the posture changes the most, thereby improving the performance.

[0007] Specification of Chinese Patent Application Publication No. 115790651

[0008] However, Patent Document 1 does not provide a specific method or process for changing the front working device to multiple positions for the purpose of calibrating the IMU.

[0009] For example, when automatically controlling the front work device to change to a predetermined position, the front work device can be operated based on operation signals from a controller (control device) generated according to a predetermined flow. However, when manually changing the front work device to a predetermined position, the hydraulic excavator operator does not know what position to change it to or when to start the operation to change the position. Also, when manually operating the front work device to calibrate the IMU, it is necessary to keep the front work device still in the predetermined position during the calibration process, but the operator does not know how long it should be kept still. As a result, the work efficiency during calibration may decrease, or proper calibration may not be possible.

[0010] In other words, when performing IMU calibration manually, it is desirable to be able to show the hydraulic excavator operator when and what actions should be taken.

[0011] The object of the present invention is to provide a work machine that can manage the state of the calibration process and provide appropriate operating instructions to the operator of the work machine in order to calibrate the errors (i.e., zero offset error and scale factor error) of the acceleration sensor and angular velocity sensor mounted on the work machine.

[0012] The present invention includes multiple means for solving the above problems, but to give one example, in a work machine comprising a work device having connected front members, an acceleration sensor and an angular velocity sensor attached to the front members, a controller that calculates the posture of the work device using the dimensional data of the work device and the outputs of the acceleration sensor and the angular velocity sensor, and a display device that notifies the operator of the work machine of the calculation results by the controller, the controller outputs to the display device an operation instruction to the operator to one of the multiple target postures and an instruction to the operator to remain still in one of the multiple target postures, based on the measurement state of the acceleration sensor and the angular velocity sensor, the calculated posture of the work device, and a plurality of target postures of the work device for calibration of errors of the acceleration sensor and the angular velocity sensor.

[0013] According to the present invention, in the calibration work of acceleration sensors and angular velocity sensors mounted on a work machine, the operator of the work machine can accurately grasp the timing of stopping and operating the work device, thereby improving the efficiency and accuracy of the calibration work.

[0014] A schematic side view showing the appearance of a hydraulic excavator, which is an example of a work machine according to this embodiment. A configuration diagram of an example of the controller 60 and its peripheral equipment. A flowchart showing the processing of the controller 60 (state management calculation unit 62). A diagram showing an example of the screen displayed on the display (notification device) 67 during calibration work according to this embodiment. A flowchart relating to the calculation of errors (offset error and scale factor error) by the IMU 50 to be calibrated.

[0015] Embodiments of the present invention will be described below with reference to the drawings.

[0016] Figure 1 is a schematic side view showing the external appearance of a hydraulic excavator, which is an example of a work machine according to this embodiment. In the following description, a hydraulic excavator equipped with a bucket as an attachment located at the tip of the front work device will be described, but it is possible to replace the bucket with various other attachments such as a grapple, breaker, or lifting magnet.

[0017] In Figure 1, the hydraulic excavator 100 comprises a multi-joint front working device (simply referred to as a working device) 30, which is made up of multiple front members (for example, a boom 31, an arm 33, and a bucket 35) that rotate around their base ends and are connected in series, and an upper slewing body 20 and a lower traveling body 10 that constitute the vehicle body.

[0018] The upper slewing body 20 is provided so as to be rotatable relative to the lower traveling body 10. The upper slewing body 20 is constructed by arranging each component on a slewing frame 21, and the slewing frame 21 that constitutes the upper slewing body 20 is rotatable relative to the lower traveling body 10. Furthermore, the base end of the boom 31 located at the base end of the front working device 30 is attached to the front of the upper slewing body 20 that constitutes the vehicle body so as to be rotatable in the vertical direction, the base end of the arm 33 is supported so as to be rotatable in the vertical direction at the tip of the boom 31, and the bucket 35 is supported so as to be rotatable in the vertical direction at the tip of the arm 33.

[0019] The lower traveling body 10 comprises a pair of crawlers 11a (11b) wrapped around a pair of left and right crawler frames 12a (12b), and a travel hydraulic motor 13a (13b) (including a reduction mechanism not shown) that drives each of the crawlers 11a (11b). Note that for each component of the lower traveling body 10, only one of the left and right pairs of components is shown and given a reference numeral, while the other component is omitted from the illustration and only shown with a reference numeral in parentheses in the figure.

[0020] The boom 31, arm 33, bucket 35, and lower traveling body 10 are driven by hydraulic actuators, namely the boom cylinder 32, arm cylinder 34, bucket cylinder 36, and left and right traveling hydraulic motors 13a (13b), respectively. The upper slewing body 20 is similarly driven by a slewing hydraulic motor 23, which is a hydraulic actuator, via a reduction mechanism 24, and performs a slewing motion in either the left or right direction relative to the lower traveling body 10.

[0021] On the slewing frame 21 that constitutes the upper slewing body 20, there is a cab (operator's room) 25 equipped with operating levers (operating devices) for operating the operating targets, including the front working device 30 (multiple front members 31, 33, 35), the upper slewing body 20, and the lower traveling body 10. In addition, a hydraulic circuit system 41 is mounted on the engine 22, which is the prime mover, along with a hydraulic pump that supplies hydraulic fluid to multiple hydraulic actuators such as the boom cylinder 32, arm cylinder 34, bucket cylinder 36, slewing hydraulic motor 23, and left and right traveling hydraulic motors 13a (13b).

[0022] (IMU 50) IMUs (Inertial Measurement Units) 50a-50d are attached to the boom 31, arm 33, and bucket 35, which are front components of the front work device 30, and to the upper slewing body 20, respectively. In Figure 1, an example is shown in which the IMU 50c for the bucket 35 is attached to a component (bucket link member) of the link mechanism that connects the bucket 35 to the tip of the arm 33. However, based on the design data of the hydraulic excavator, etc., it can be treated as if the IMU 50c is mounted on the bucket 35.

[0023] The IMU 50a-50d are devices for detecting the three-dimensional inertial motion of the boom 31, arm 33, bucket 35, and upper slewing body 20 to which they are attached. Each is equipped with an acceleration sensor and an angular velocity sensor (neither of which are shown). The acceleration sensor can detect (calculate) acceleration, tilt angle (in the direction of gravity), velocity, displacement, and translation, while the angular velocity sensor can detect (calculate) angular velocity, angle, and rotational motion. The tilt angle obtained by the acceleration sensor and the angle obtained by the angular velocity sensor can be used as attitude data for the boom 31, arm 33, bucket 35, and upper slewing body 20. Hereafter, the four IMUs 50a, 50b, 50c, and 50d may be collectively referred to as IMU 50.

[0024] Each of the IMUs 50a to 50d may be assigned unique identification information. By adding this identification information to the detection data of each IMU 50 and outputting it to the in-vehicle network, it is possible to identify which IMU 50 each detection data transmitted over the in-vehicle network is from.

[0025] The cab 25 is equipped with a controller 60, an alarm device 67, and an input device 68.

[0026] The controller 60 is a computer that performs calculations and controls related to the hydraulic excavator 100 by executing programs stored in a memory device such as a semiconductor memory using a processor such as a CPU. The controller 60 can, for example, perform attitude calculations of the boom 31, arm 33, bucket 35 (hereinafter, the boom 31, arm 33, and bucket 35 may be referred to as front members 31, 33, and 35) and the upper slewing body 20 using the output of the IMU 50, and can also perform processing related to the calibration of the zero offset error of the acceleration sensor and the scale factor error of the angular velocity sensor in the IMU 50. Furthermore, the controller 60 can output to the notification device 67 an operation instruction to the operator of the hydraulic excavator 100 to one of the target positions (described later) and an instruction to the operator of the hydraulic excavator 100 to remain stationary in one of the target positions (described later), based on the measurement status of the IMU 50 (accelerometer and angular velocity sensor) (whether or not measurement is in progress), the attitude data of the work device 30, and multiple target positions of the work device 30 for calibration of the IMU 50 error (the first to fourth target positions described later).

[0027] The storage device (not shown) in the controller 60 stores the mounting angles of the IMUs 50a to 50d attached to the front members 31, 33, 35 and the upper slewing body 20, respectively. It may also store excavation target surface data that defines the three-dimensional shape of the terrain to be excavated by the hydraulic excavator 100. By using the position data of the hydraulic excavator 100, the attitude data of the work device 30 and the upper slewing body 20, and the excavation target surface data, the distance between the tip of the bucket 35 located at the front of the work device 30 and the excavation target surface can be calculated. The position data and orientation data of the hydraulic excavator 100 can be acquired by mounting multiple positioning antennas and receivers on the hydraulic excavator 100.

[0028] The notification device 67 notifies the operator of the calculation results of the controller 60. For example, in the calibration work for the error of the IMU 50, the operator of the hydraulic excavator 100 needs to manually operate the work equipment to assume multiple target positions. The notification device 67 may provide the operator with instructions to operate the equipment to one of these target positions, or instructions to keep the equipment stationary in one of these target positions.

[0029] The notification device 67 is, for example, a display (monitor), and in addition to the operation instructions and stationary instructions mentioned above, it may also display positional relationship information between the bucket 35 and the terrain surface (current terrain or target excavation surface) (for example, the relative position and distance between the two). In addition to the display mentioned above, speakers, buzzers, and warning lights can also be used as the notification device 67.

[0030] The input device 68 is, for example, a switch, button, touch panel, etc., and input operations related to calibration work and other operations are input by the operator of the hydraulic excavator 100.

[0031] Figure 2 is a configuration diagram of an example of a controller 60 and its peripheral equipment. The controller 60 is connected to pressure sensors 73b-73d, 74b-74d that detect the drive pressure of actuators 32, 34, 36 that drive a plurality of front members 31, 33, 35, as well as IMUs 50a-50d, a display as an notification device 67, and a switch as an input device 68. As shown in the figure, the IMUs 50a-50d may also be connected via an in-vehicle network (e.g., CAN) 70. Within the controller 60 in the figure, the functions that can be executed by the processor in the controller 60 are shown as blocks.

[0032] The pressure sensors 73b-73d and 74b-74d are sensors for detecting the operating status of the front members 31, 33, and 35 (i.e., IMUs 50a-50c). Specifically, the pressure sensors 73b-73d and 74b-74d used in this embodiment are pressure sensor 73b for detecting the rod-side pressure of the boom cylinder 32, pressure sensor 74b for detecting the bottom-side pressure of the boom cylinder 32, pressure sensor 73c for detecting the rod-side pressure of the arm cylinder 34, pressure sensor 74c for detecting the bottom-side pressure of the arm cylinder 34, pressure sensor 73d for detecting the rod-side pressure of the bucket cylinder 36, and pressure sensor 74d for detecting the bottom-side pressure of the bucket cylinder 36. In other words, the pressure sensors 73b-73d and 74b-74d are also sensors for detecting the operating state (operation state) of the actuators 32, 34, and 36. Hereafter, some or all of the pressure sensors 73b-73d and 74b-74d may be collectively referred to as pressure sensors 73 and 74.

[0033] In addition to the pressure sensors 73b-73d and 74b-74d mentioned above, sensors that detect the amount of operation of the operating device for the front members 31, 33, and 35, or the operation signals (pilot pressure or voltage) for the flow control valves of the hydraulic cylinders 32, 34, and 36, may also be used as sensors to detect the operating state of the front members 31, 33, and 35. That is, if the operation of each actuator 32, 34, and 36 (each front member 31, 33, and 35) is performed by an electric lever, the voltage value output from the controller 60 to the flow control valve operation signal may be detected. Furthermore, each IMU 50 may be used as a sensor to detect the operating state of the front members 31, 33, and 35 (IMU 50a-50c).

[0034] The controller 60 can function as an operating state estimation unit 61, a state management calculation unit 62, an instruction calculation unit 63, and a basic data storage unit 64 by executing a program stored in the memory device using the processor.

[0035] The operating state estimation unit 61 estimates the operating state of each front member 31, 33, 35 (each IMU 50) and each actuator 32, 35, 36 based on the detected values ​​(outputs) of the pressure sensors 73, 74. The operating state estimation unit 61 can also calculate and output the operating speed of each front member 31, 33, 35.

[0036] The state management calculation unit 62 manages the state of the IMU 50 during the calibration process in response to signals indicating the measurement state of the IMU 50 input from the IMU 50 (e.g., calibration start response, measurement end response, calibration end response), the measured values ​​of the IMU 50 (accelerometer and angular velocity sensor), and commands input via the input device 68 (e.g., calibration start instruction). In other words, the state management calculation unit 62 manages what state each IMU 50 is in at each stage of the calibration work. In this embodiment, the "state" is distinguished in relation to the posture of the work device 30 from the start to the end of the calibration work, and ten states from S1 to S10, which will be described later, are defined.

[0037] The instruction calculation unit 63 generates information to be notified by the notification device 67 based on the posture data of the work device 30 calculated using the dimensional data of the work device 30 and the output of the IMU 50, the measurement state of the IMU 50 (accelerometer and angular velocity sensor) calculated by the state management calculation unit 62, the operating state of each front member 31, 33, 35 estimated by the operating state estimation unit 61, and information on multiple target postures stored in the basic data storage unit 64. This information includes, for example, an operation instruction to the operator of the hydraulic excavator 100 to change the work device 30 to one of multiple target postures, an instruction to the operator to remain stationary in one of the multiple target postures, the current posture of the work device 30, an instruction for the target posture of the work device 30 related to the operation instruction, and an instruction for the amount of operation of the operating device (operating lever in the cab) (operation of the front members 31, 33, 35) suitable for calibration of the IMU 50 (accelerometer and angular velocity sensor) when changing the work device 30 to a target posture.

[0038] The basic data storage unit 64 stores basic data including dimensional data of the work device 30, including each of the front members 31, 33, and 35, data of four target postures (first target posture, second target posture, third target posture, and fourth target posture) used for calibration work, and the mounting angles of each of the multiple front members 31, 33, and 35 and the IMU (accelerometer and angular velocity sensor) 50 attached to the upper rotating body 20. Hardware examples include semiconductor memory such as memory or SSDs, and magnetic storage devices such as HDDs.

[0039] The notification device 67 notifies information based on the information calculated by the instruction calculation unit 63. The method of notifying information may be to display an image on the display, or to provide guidance using a buzzer or voice guidance. The display may also display a picture, or the status may be displayed using numbers or symbols, and instructions on how to operate according to the status may be provided in a separately defined instruction manual.

[0040] The input device 68 is, for example, a switch, and can be operated by the driver to instruct the state management calculation unit 62 of the controller 60 to start the calibration operation. The switch may be a dedicated one for instructing the start of the calibration operation, or when the notification device 67 is a touch panel display, the switch displayed on the screen may be used. Further, a cancel switch for canceling the calibration operation may be added.

[0041] Next, the processing of the controller 60 (processor) will be described using FIG. 3. Here, the notification device 67 is a display (monitor) and may be referred to as the display 67. Also, for the sake of simplicity of explanation, the upper swing body 20 is arranged on a horizontal plane, and it is assumed that the posture of the working device 30 can be calculated from the outputs of the three IMUs 50 related to the front members 31, 33, and 35.

[0042] FIG. 3 is a flowchart showing the processing of the controller 60 (state management calculation unit 62). This processing can start periodically (for example, at a cycle of 10 milliseconds).

[0043] (Step S10) When the processing starts, in step S10, the controller 60 waits for an input of a calibration start instruction (calibration start instruction) from the driver of the hydraulic excavator 100 via the input device 68. When a signal instructing the start of calibration is input from the input device 68, the process proceeds to step S20.

[0044] (Step S20) In step S20, the controller 60 determines that the calibration state at that time is a state (first posture transition state) S1 in which the posture of the working device 30 is transitioned from the posture at the time of input of the calibration start instruction (referred to as the initial posture) to the first target posture, and displays (outputs) an instruction (operation instruction) to operate to the first target posture to the driver on the display 67, and the process proceeds to step S30.

[0045] (Step S30) In Step S30, the attitude of the working device 30 is calculated from the attitude data of the working device 30 calculated from the outputs of the three IMUs 50 and the mounting angles of the three IMUs 50 stored in the basic data storage unit 64, and it is determined whether or not the attitude has become the same as the first target attitude stored in the basic data storage unit 64. That is, it is confirmed whether or not the change from the initial attitude to the first target attitude has been completed.

[0046] Note that the "same attitude" can be determined, for example, when the difference in the angles of the respective front members 31, 33, 35 is within ±3 degrees (the same applies to other target attitudes hereinafter).

[0047] If it is determined that the working device 30 has reached the first target attitude, the process proceeds to Step S40. (Step S40) In Step S40, the controller 60 outputs a calibration start instruction (which is also a measurement start instruction) instructing the start of measurement by the acceleration sensor to the IMU 50 to be calibrated (here, the IMUs 50a, 50b, 50c attached to the front members 31, 33, 35), and determines that the calibration state is the state (calibration start response waiting state) S2 of waiting for a signal (calibration start response) indicating that the measurement by the IMU 50 for calibration has started, and proceeds to Step S50.

[0048] (Step S50) In Step S50, the controller 60 determines whether an input of a calibration start response has been received from the IMU 50 that output the calibration start instruction in S40. If a calibration start response has been received, the process proceeds to Step S60.

[0049] (Step S60) In Step S60, the controller 60 displays (outputs) an instruction (stop instruction) to stop (prohibit operation) in the first target attitude to the driver on the display 67, and determines that the calibration state is the state (first attitude waiting state) S3 of waiting for the completion of measurement by the acceleration sensor in the first target attitude, and proceeds to Step S70.

[0050] (Step S70) In step S70, the controller 60 determines whether the measurement of the first target attitude by the acceleration sensor of the IMU 50 to be calibrated has been completed. As for the method of determination, if the measurement time by the acceleration sensor of the IMU 50 is predetermined, the determination may be made by whether the time from the input of the calibration start response has reached the said measurement time, or if a signal indicating that the measurement of the first target attitude by the acceleration sensor has been completed (measurement completion response) is input from the IMU 50, the determination may be made using that signal. Here, we will explain the case in which the measurement completion response is used.

[0051] If it is determined that the measurement in the first target posture is complete, proceed to step S80.

[0052] (Step S80) In step S80, the controller 60 determines that the calibration state at that time is a state in which the posture of the work device 30 is transitioned from the first target posture to the second target posture (second posture transition state) S4, and displays (outputs) an instruction (operation instruction) on the display 67 to the operator to operate to the second target posture, and proceeds to step S90.

[0053] (Step S90) In step S90, the posture of the work device 30 is calculated from the posture data of the work device 30 calculated from the output of the IMU 50 and the mounting angle of the IMU 50 stored in the basic data storage unit 64, and it is determined whether the posture is the same as the second target posture stored in the basic data storage unit 64.

[0054] If it is determined at this point that the second target posture has been achieved, proceed to step S100.

[0055] (Step S100) In step S100, the controller 60 displays (outputs) an instruction (stop instruction) on the display 67 to the driver to stop (prohibit operation) in the second target posture, outputs a measurement start instruction to the IMU 50 which performs calibration to start measurement by the acceleration sensor in the second target posture, determines the calibration state to be a state of waiting for the completion of measurement by the acceleration sensor in the second target posture (second posture waiting state) S5, and proceeds to step S110.

[0056] (Step S110) In step S110, the controller 60 determines whether the measurement of the second target attitude by the acceleration sensor of the IMU 50 performing calibration has been completed. The method of determination is the same as in step S70. That is, here, the controller determines that the measurement has been completed when a signal (measurement completion response) indicating that the measurement of the second target attitude by the acceleration sensor is received from the IMU 50 is completed.

[0057] If it is determined that the measurement in the second target posture is complete, proceed to step S120.

[0058] (Step S120) In step S120, the controller 60 determines that the calibration state at that time is a state in which the posture of the work device 30 is transitioned from the second target posture to the third target posture (third posture transition state) S6, and displays (outputs) an instruction (operation instruction) on the display 67 to the operator to operate to the third target posture, and proceeds to step S130.

[0059] (Step S130) In step S130, the posture of the work device 30 is calculated from the posture data of the work device 30 calculated from the output of the IMU 50 and the mounting angle of the IMU 50 stored in the basic data storage unit 64, and it is determined whether the posture is the same as the third target posture stored in the basic data storage unit 64.

[0060] If it is determined at this point that the third target posture has been achieved, proceed to step S140.

[0061] (Step S140) In step S140, the controller 60 displays (outputs) an instruction (stop instruction) on the display 67 to the driver to stop (prohibit operation) in the third target posture, outputs a measurement start instruction to the IMU 50 which is performing calibration to start measurement by the acceleration sensor in the third target posture, determines the calibration state to be a state of waiting for the completion of measurement by the acceleration sensor in the third target posture (third posture waiting state) S7, and proceeds to step S150.

[0062] (Step S150) In step S150, the controller 60 determines whether the measurement of the third target attitude by the acceleration sensor of the IMU 50 performing calibration has been completed. The method of determination is the same as in step S70. That is, here, the controller determines that the measurement has been completed when a signal (measurement completion response) indicating that the measurement of the third target attitude by the acceleration sensor is received from the IMU 50 is completed.

[0063] If it is determined that the measurement in the third target posture is complete, proceed to step S160.

[0064] (Step S160) In step S160, the controller 60 determines that the calibration state at that time is a state in which the posture of the work device 30 is transitioned from the third target posture to the fourth target posture (fourth posture transition state) S8, and displays (outputs) an instruction (operation instruction) on the display 67 to the operator to operate to the fourth target posture, and proceeds to step S170.

[0065] (Step S170) In step S170, the posture of the work device 30 is calculated from the posture data of the work device 30 calculated from the output of the IMU 50 and the mounting angle of the IMU 50 stored in the basic data storage unit 64, and it is determined whether the posture is the same as the fourth target posture stored in the basic data storage unit 64.

[0066] If it is determined at this point that the fourth target posture has been achieved, proceed to step S180.

[0067] (Step S180) In step S180, the controller 60 displays (outputs) an instruction (stop instruction) on the display 67 to the driver to stop (prohibit operation) in the fourth target posture, outputs a measurement start instruction to the IMU 50 which is performing calibration to start measurement by the acceleration sensor in the fourth target posture, determines the calibration state to be a state of waiting for the completion of measurement by the acceleration sensor in the fourth target posture (fourth posture waiting state) S9, and proceeds to step S190.

[0068] (Step S190) In step S190, the controller 60 determines whether the measurement of the fourth target attitude by the acceleration sensor of the IMU 50 performing calibration has been completed. The method of determination is the same as in step S70. That is, here, the controller determines that the measurement has been completed when a signal (measurement completion response) indicating that the measurement of the fourth target attitude by the acceleration sensor is received from the IMU 50 is completed.

[0069] If it is determined that the measurement in the fourth target posture is complete, proceed to step S200.

[0070] (Step S200) In step S200, the controller 60 determines the calibration state to be the calibration completion state S10 and terminates the series of processes.

[0071] The above is the processing flow of the controller 60.

[0072] Regarding the target posture of the work device 30, the explanation was given using the case where the IMU 50 is measured with four target postures. However, due to the unknowns in the formulas used to calculate the offset error and scale factor error, it is sufficient to measure with three or more target postures. Furthermore, the number of target postures can be changed to match the number of calibration cycles for the IMU 50.

[0073] Furthermore, in each of the posture standby states S3, S5, S7, and S9, if there is input from the pressure sensors 73 and 74 or if the angle value of the IMU 50 changes (for example, by 3 degrees or more), it may be determined that calibration cannot be performed correctly, and the calibration process may be stopped. This may be instructed to the IMU 50 or displayed on the display 67. Also, if the time taken in each posture transition state S4, S6, and S8 from step S80 onward exceeds a predetermined time (for example, 10 seconds), it may be determined that calibration cannot be performed correctly, and the calibration process shown in Figure 3 may be terminated midway. In addition, if a cancellation means such as a cancel switch is provided as an input device 68, the calibration process may be terminated midway when the cancel switch is pressed.

[0074] Figure 4 shows an example of a screen displayed on the display (notification device) 67 during calibration work according to this embodiment. Each screen in Figure 4 is displayed on the display 67 by the calibration posture instruction calculation unit 63 of the controller 60.

[0075] The calibration posture instruction calculation unit 63 generates displays related to operation instructions and stationary instructions based on the state of the IMU 50 (S1-S10) determined by the state management calculation unit 62.

[0076] Figure 4(a) shows the screen displayed on the display 67 when an operation to start the calibration work is input to the input device (e.g., a switch) 68 and the first posture transition state S1 is determined (steps S20-S30). In addition to the first target posture and the operation instruction to achieve the first target posture ("Please set the target posture to the one shown in the figure"), the current posture of the work device 30 is also displayed.

[0077] Figure 4(b) shows the screen displayed on the display 67 when it is determined that the calibration start response waiting state S2 and the first posture waiting state S3 are in place (steps S40-S70). This screen displays a stationary instruction ("Do not operate the shovel") instructing the operator to keep the work device 30 stationary in the first target posture.

[0078] Figure 4(c) is the screen displayed when the second posture transition state S4 is determined (steps S80-S90). Similar to Figure 4(a), in addition to the target posture (second target posture) and operation instructions for the operator, the current posture of the work device 30 is displayed. The only difference between the first target posture and the second target posture is the angle of the boom 31 (i.e., the angles of the arm 33 and bucket 35 are the same), and the operator of the hydraulic excavator 100 can change from the first target posture to the second target posture by operating the boom only. For example, the second target posture shown in Figure 4(c) is the posture when the boom cylinder 32 is at its longest length, and the transition from the first target posture to the second target posture can be made by raising the boom only.

[0079] Figure 4(d) shows the screen displayed when the second posture standby state S5 is determined (steps S100-S110). At this time, similar to Figure 4(b), the message "Do not operate the shovel" is displayed as a stop instruction to the operator.

[0080] Figure 4(e) is the screen displayed when the third posture transition state S6 is determined (steps S120-130). Similar to Figures 4(a) and (c), in addition to the third target posture and operation instructions, the current posture of the work device 30 is displayed. The only difference between the second target posture and the third target posture is the angle of the boom 31, and the operator of the hydraulic excavator 100 can change to the third target posture by operating the boom alone. For example, the third target posture shown in Figure 4(e) is the posture in which the boom cylinder 32 is retracted from the second target posture in Figure 4(c), and the transition from the second target posture to the third target posture can be made by lowering the boom alone.

[0081] Figure 4(f) shows the screen displayed when the third-position standby state S7 is determined (steps S140-S150). At this time, similar to Figure 4(b), the message "Do not operate the shovel" is displayed as a stop command to the operator.

[0082] Figure 4(g) is the screen displayed when the fourth posture transition state S8 is determined (during steps S160-S170). Similar to Figures 4(a), (c), and (e), it displays the operation instructions and the fourth target posture, as well as the current posture of the work device 30. The operator achieves the fourth posture solely by operating the boom.

[0083] Figure 4(h) shows the screen displayed when the fourth posture standby state S9 is determined (S180-S190). At this time, similar to Figure 4(b), the message "Do not operate the shovel" is displayed as a stop command to the operator.

[0084] Figure 4(i) shows the screen displayed when the calibration completion state S10 is determined (S200). In other words, this screen is for notifying that the calibration work has been completed. In the example of Figure 4(i), the display 67 is a touch panel display and shows an "End" button, which is operated by the driver when the calibration work is finished, and a "Re-run" button, which is operated by the driver when the calibration work is to be repeated.

[0085] Figure 4(j) shows the screen displayed when the cancel button 68 is pressed or when the calibration process is canceled due to unexpected movement. In the example of Figure 4(j), the display 67 is a touch panel display, and it shows an "End" button, which is pressed by the driver when the calibration process is finished, and a "Restart" button, which is pressed by the driver when the calibration process is restarted.

[0086] If the display is a touch panel display, a cancel button 68 for interrupting the calibration process may be placed on the eight screens shown in Figures 4(a) to 4(h).

[0087] Next, the processing of the IMU 50 will be explained using Figure 5. Figure 5 is the flow for the IMU 50 to be calibrated, which is paired with the flow for the controller 60 in Figure 3, and has processing (steps) that correspond to the steps in the flow of Figure 3. The number of IMU 50 to be calibrated is one to three, and the IMU 50 to be calibrated communicates with the controller 60. As with Figure 3, for the sake of simplicity, the upper rotating body 20 is assumed to be positioned on a horizontal plane.

[0088] Figure 5 is a flowchart showing the calculation of errors (offset error and scale factor error) by the IMU 50 being calibrated. The IMU 50 can, for example, start the flowchart in Figure 5 at a predetermined period.

[0089] (Step SS40) When the process starts, in step SS40, the IMU 50 to be calibrated is in a state of waiting for input of a calibration start instruction (measurement start instruction) output by the controller 60 in step S40 (Figure 3). When input of a calibration start instruction (measurement start instruction) is received from the controller 60, the process proceeds to step SS50.

[0090] (Step SS50) In step SS50, the IMU 50 to be calibrated starts the calibration process on its own side, outputs a calibration start response to the controller 60, and proceeds to step SS70.

[0091] (Step SS70) In step SS70, the system is in a first-position standby state S3, where a stationary instruction is output to the display 67 (step S60 in Figure 3), and the IMU 50 starts measuring with the acceleration sensor while the hydraulic excavator 100 is stationary. The measurement by the acceleration sensor may be performed for a certain period of time (e.g., 5 seconds), during which the measured values ​​stored are averaged, and the average value is taken as the acceleration value of the IMU 50 in the first target position. This averaging process may also be performed by the controller 60. Once the measurement is complete, the IMU 50 outputs a measurement completion response to the controller 60, which is a signal indicating that the measurement in the first target position has been completed (this measurement completion response is used in step S70 in Figure 3). As previously mentioned, if the measurement time by the acceleration sensor is predetermined, it may be determined that "the measurement is complete" when that measurement time has elapsed. Once the measurement of acceleration in the first target posture is complete, an operation instruction to transition from the first target posture to the second target posture is displayed on the display 67, and the transition to the second target posture is initiated by the driver's operation (step S80 in Figure 3).

[0092] (Step SS75) In step SS75, the amount of angle change is calculated by accumulating and summing the values ​​of the angular velocity sensor of the IMU 50 during the time it takes for the work device 30 to change from the first target posture to the second target posture. This calculation of the amount of angle change may also be performed on the controller 60 side by inputting the measured values ​​of the angular velocity sensor.

[0093] (Step SS90) In step SS90, it is determined whether the work device 30 is stationary in the second target posture. If it is confirmed that it is stationary in the second target posture, the process proceeds to the next step SS110. Alternatively, the determination of whether or not it is stationary in the second target posture can be made by the controller 60 outputting a signal to the IMU 50 when it outputs a stationary instruction in step S100 (Figure 3), and the determination that it is stationary in the second target posture can be made based on the input of this signal.

[0094] (Step SS110) In step SS110, the system is in a second-position standby state S5, where a stationary instruction is output to the display 67 (step S100 in Figure 3). The IMU 50 performs measurements using an acceleration sensor while the hydraulic excavator 100 is stationary. Note that, as explained in SS70, the acceleration sensor measurement is performed for a certain period of time (for example, 5 seconds), and the measured values ​​stored during that time are averaged. The average value is then used as the acceleration value of the IMU 50 in the second target position. Once the measurement is complete, the IMU 50 outputs a measurement completion response to the controller 60, which is a signal indicating that the measurement in the second target position has been completed. After the acceleration measurement in the second target position is complete, an operation instruction to transition from the second target position to the third target position is displayed on the display 67, and the transition to the third target position is initiated by the operator's operation (step S120 in Figure 3).

[0095] (Step SS130) In step SS130, it is determined whether the work device 30 is stationary in the third target posture. If it is confirmed that it is stationary in the third target posture, the process proceeds to the next step SS110. The determination of whether or not it is stationary in the third target posture is performed in the same manner as in step S90.

[0096] (Step SS150) In step SS150, the system is in a third-position standby state S7, with a stationary instruction output to the display 67 (step S140 in Figure 3). The IMU 50 performs measurements using the acceleration sensor while the hydraulic excavator 100 is stationary. The acceleration sensor measurements are performed in the same manner as in SS70. Once the measurement is complete, the IMU 50 outputs a measurement completion response to the controller 60, which is a signal indicating that the measurement in the third target position has been completed. After the acceleration measurement in the third target position is completed, an operation instruction to transition from the third target position to the fourth target position is displayed on the display 67, and the transition to the fourth target position is initiated by the operator's operation (step S160 in Figure 3).

[0097] (Step SS170) In step SS170, it is determined whether the work device 30 is stationary in the fourth target posture. If it is confirmed that it is stationary in the fourth target posture, the process proceeds to the next step SS180. The determination of whether or not it is stationary in the fourth target posture is performed in the same manner as in step S90.

[0098] (Step SS180) In step SS180, the system is in the fourth posture standby state S9, with a stationary instruction output to the display 67 (Step S180 in Figure 3), and the IMU 50 performs measurements with the acceleration sensor while the hydraulic excavator 100 is stationary. The measurement with the acceleration sensor is performed in the same manner as in SS70. Once the measurement is complete, the IMU 50 outputs a measurement completion response to the controller 60, which is a signal indicating that the measurement in the fourth target posture has been completed. Once the measurement of acceleration in the fourth target posture is complete, the system proceeds to step SS182.

[0099] (Step SS182) In step SS182, the offset error of the acceleration sensor of the IMU 50 to be calibrated is calculated using the acceleration values ​​for the first to fourth target attitudes acquired in SS70, SS110, SS150, and SS180. If there are multiple IMU 50s to be calibrated, the offset error is calculated for each IMU 50 based on its acceleration value (measured for the four target attitudes).

[0100] (Step SS184) In step SS184, the angular difference between the first target posture and the second target posture is calculated using the acceleration value (SS70) obtained in the first target posture and the acceleration value (S110) obtained in the second target posture. The scale factor error of the angular velocity sensor in the IMU 50 is calculated from this calculated angular difference, the offset error obtained in SS182, and the amount of angular change obtained in SS75. In addition, similar to the calculation of the offset error, if there are multiple IMU 50s to be calibrated, the scale factor error is calculated for each IMU 50 based on the measured values ​​of the angular velocity sensor of each IMU 50 (measured in the four target postures).

[0101] (Step SS190) In step SS190, the IMU 50 outputs a signal to the controller 60 indicating that the error calibration is complete (calibration work completion response), and the series of processes ends.

[0102] This completes the calibration of the IMU50 (accelerometer and angular velocity sensor) by correcting the offset error and scale factor error calculated in SS182 and SS184 to zero.

[0103] (Note) This embodiment can be modified in various ways. For example, in the above embodiment, the system is configured so that the posture can be changed to three different positions, from the second target posture to the fourth target posture, by operating only the boom 31 (boom cylinder 32). However, it is also possible to set a target posture that requires the operation of multiple front members (hydraulic cylinders) and output an operation instruction to the notification device 67 to change to that target posture.

[0104] Furthermore, instructions on how to operate the control device (which control lever to move) may be added as "operational instructions" to the operator for changing the posture of the work device 30 to the target posture.

[0105] Furthermore, when outputting an operation instruction to the notification device 67 to transition to the target posture, the notification device 67 may also output an instruction (speed instruction) for the operating speed of the front members 31, 33, 35 and hydraulic cylinders 32, 34, 36, which are suitable for measurement of the IMU 50 (i.e., calibration of the error of the IMU 50). Figure 4(k) is a diagram showing an example of the screen (which includes operation instructions and speed instructions) displayed on the display 67 when it is determined that the transition state to the target posture is S4, S6, or S8. In any of these states S4, S6, or S8, measurement may be performed by the angular velocity sensor of the IMU 50 to be calibrated, but if the driver's operating speed is slow at that time, the angular velocity sensor in the IMU 50 may mistakenly recognize that the front member is stationary and fail to measure. Therefore, as shown in Figure 4(k), a lower limit threshold for the operating speed is set, and if it falls below this lower limit threshold, the speed instruction shown ("Please increase the operating speed") is output. By outputting such a speed instruction to the driver, the possibility of the angular velocity sensor failing to measure can be reduced. Furthermore, by operating at a speed above a certain level, the noise error of the angular velocity sensor can be reduced when accumulating and adding the values ​​of the angular velocity sensor during transitions between two target attitudes, thereby improving the calculation accuracy of the angular velocity sensor's scale factor error.

[0106] The lower limit of the operating speed can be set based on factors such as the resolution of the angular velocity sensor and the desired measurement accuracy. The operating speed can be defined by the value of the angular velocity sensor (angular velocity) or the amount of operation of the operating device (operating pressure in the case of a hydraulic operating lever). For example, the lower limit can be set to 15 degrees / second for the angular velocity sensor and 1.5 MPa for the operating pressure of the operating lever.

[0107] In this explanation, we have described the case where speed instructions are displayed on the display 67 in addition to operation instructions, but speed instructions may also be displayed on the display 67 at a different timing than the operation instructions.

[0108] (Effects) The effects of this embodiment, configured as described above, will now be explained.

[0109] (1) The work machine according to the above embodiment comprises a work device 30 having a plurality of connected front members 31, 33, 35, acceleration sensors and angular velocity sensors (IMU 50) attached to each of the plurality of front members 31, 33, 35, a controller 60 that calculates the posture of the work device 30 using the dimensional data of the work device 30 and the outputs of the acceleration sensors and the angular velocity sensors (IMU 50), and a notification device 67 that notifies the operator of the work machine 100 of the calculation results by the controller 60. The controller 60 outputs to the notification device 67 an operation instruction to the operator to one of the plurality of target postures and an instruction to the operator to remain still in one of the plurality of target postures, based on the measurement state of the acceleration sensors and the angular velocity sensors (IMU 50), the calculated posture of the work device 30, and a plurality of target postures of the work device 30 for calibration of the errors of the acceleration sensors and the angular velocity sensors (IMU 50).

[0110] In this way, by outputting an operation instruction to one of the multiple target postures and an instruction to stop in one of the multiple target postures to the notification device 67, the operator of the work machine can accurately understand when to change the posture of the work device 30 to a target posture and when to stop the work device 30, thereby improving the efficiency and optimization of the calibration work of the acceleration sensor and angular velocity sensor (IMU 50). In addition, it is possible to suppress the failure of the calibration work midway.

[0111] (2) In the work machine described in (1) above, preferably the notification device 67 is a display 67 mounted in the operator's cab 25 of the work machine 30, the controller 60 stores the mounting angles of the acceleration sensors and angular velocity sensors (IMUCH 50) attached to each of the plurality of front members 31, 33, and 35, and the controller 60 displays the current posture of the work machine 30 and the target posture related to the operation instruction on the display 67 along with the operation instruction.

[0112] By displaying the current and target postures of the work device 30 on the display 67 in this way, it becomes easier for the operator to understand the difference between the two postures, thereby further improving the efficiency of the calibration work. Although there is also a technique for calibrating the mounting angles of the acceleration sensor and angular velocity sensor (IMU 50), this invention is for calibrating the errors (offset error and scale factor error) of these two sensors, and the posture of the work device 30 is calculated using the mounting angles of the acceleration sensor and angular velocity sensor stored in the controller 60.

[0113] (3) In the work machine described in (2) above, preferably the work device 30 has a boom 31, an arm 33 and an attachment 35 as the plurality of front members 31, 33, and 35, and the plurality of target postures are postures that can be changed simply by operating the boom 31, except for the first target posture which is initially instructed by the controller 60 when the calibration work starts.

[0114] By defining the target posture in this way, the operator's operation when changing the posture of the work device 30 is simplified, and the correct target posture can be quickly changed, thereby further improving the work efficiency of the calibration work. In the above embodiment, the second target posture, the third target posture, and the fourth target posture differ only in the angle of the boom 31, while the angles of the arm 33 and bucket 35 are the same.

[0115] (4) In the work machine described in (1) above, preferably, the machine further includes an operating device operated by an operator for operating each of the multiple front members 31, 33, and 35, and the controller 60 notifies the operator via the notification device 67 of a speed instruction, which is an instruction for the operating speed of the multiple front members suitable for calibrating the errors of the acceleration sensor and angular velocity sensor (IMU 50), when an operation instruction is given.

[0116] By providing speed instructions suitable for calibration during operation, the possibility of measurement failure by the angular velocity sensor can be reduced, and the occurrence of noise errors in the angular velocity sensor can be reduced, thereby improving the calculation accuracy of the angular velocity sensor's scale factor error.

[0117] In addition, when issuing this speed instruction, the controller 60 may calculate the operating speeds of the multiple front members 31, 33, and 35 based on the amount of operation input to the operating device, and if at least one of the operating speeds is slower than a predetermined threshold, it may output an instruction to increase the operating speed (an instruction to increase the amount of operation of the operating device is also acceptable) as a speed instruction to the notification device 67.

[0118] (5) In the above embodiment, four target postures were set in order to improve the accuracy of error calculation, but error calibration itself is possible if at least three target postures are set. Also, the amount of angular velocity change calculated by the angular velocity sensor can be measured during either the transition from the first target posture to the second target posture or the transition from the second target posture to the third target posture. The processing of the controller 60 when there are three target postures is as follows.

[0119] In other words, in the work machine described in (1) above, preferably, when calibration of the errors of the acceleration sensor and the angular velocity sensor (IMU 50) is started, the controller 60 presents the first target posture and an operation instruction to the first target posture to the notification device 67, confirms whether the change to the first target posture has been completed based on the calculated posture of the work device 30, and after confirming the completion of the change to the first target posture, outputs a measurement start instruction to the acceleration sensor and outputs a stationary instruction to the notification device 67 in the first target posture. Then, after the measurement by the acceleration sensor in the first target posture is completed, the controller 60 presents the second target posture and an operation instruction to the second target posture to the notification device 67, confirms whether the change to the second target posture has been completed based on the calculated posture of the work device 30, and after confirming the completion of the change to the second target posture, outputs a measurement start instruction to the acceleration sensor and outputs a stationary instruction to the notification device 67 in the second target posture. Then, after the completion of measurement by the acceleration sensor in the second target posture, the controller 60 presents the third target posture and an operation instruction to the notification device as one of the multiple target postures, and confirms whether the change to the third target posture has been completed based on the calculated posture of the work device 30. After confirming the completion of the change to the third target posture, the controller 60 outputs a measurement start instruction to the acceleration sensor and outputs a stationary instruction in the third target posture to the notification device 67. Then, during the first time when the posture change from the first target posture to the second target posture is taking place, or during the second time when the posture change from the second target posture to the third target posture is taking place, the controller 60 calculates the amount of angle change in the first or second time by accumulating the measured values ​​from the angular velocity sensor, and estimates the offset error of the acceleration sensor based on the measured values ​​from the acceleration sensor in the first target posture, the second target posture, and the third target posture. When the controller 60 calculates the angle change amount for the first time as the angle change amount, it calculates the angle difference between the first target posture and the second target posture based on the measured value of the acceleration sensor at the first target posture and the measured value of the acceleration sensor at the second target posture, and estimates the scale fact error of the angular velocity sensor based on the calculated angle difference, the angle change amount for the first time, and the estimated offset error.Furthermore, when the controller 60 calculates the angle change amount for the second time as the angle change amount, it calculates the angle difference between the second target posture and the third target posture based on the measured value of the acceleration sensor at the second target posture and the measured value of the acceleration sensor at the third target posture, and estimates the scale fact error of the angular velocity sensor based on the calculated angle difference, the angle change amount for the second time, and the estimated offset error.

[0120] With this configuration, by taking three target postures, it is possible to calculate (estimate) the errors between the acceleration sensor and the angular velocity sensor.

[0121] In the above embodiment, the amount of angle change was calculated using an angular velocity sensor during the transition from the first target posture to the second target posture. However, the amount of angle change can be calculated while the posture of the work device 30 is being changed between the two target postures. That is, the amount of angle change can also be calculated during the transition from the second target posture to the third target posture, and from the third target posture to the fourth target posture. However, it should be noted that the larger the angle change between the two postures, the more accurate the calculated amount of angle change will be.

[0122] (Other) The present invention is not limited to the embodiments described above, and includes various modifications that do not depart from the spirit of the invention. For example, the present invention is not limited to having all the configurations described in the embodiments described above, and includes those in which some of the configurations have been omitted. Furthermore, it is possible to add or replace a part of the configuration of one embodiment with a configuration of another embodiment.

[0123] Furthermore, some or all of the configurations related to the controller 60, as well as the functions and execution processes of each of those configurations, may be implemented in hardware (for example, by designing the logic for executing each function using an integrated circuit). Also, the configurations related to the controller 60 may be expressed as a program (software) that is read and executed by an arithmetic processing unit (e.g., a CPU) to realize each of the functions related to the controller 60. Information related to such a program can be stored, for example, in semiconductor memory (flash memory, SSD, etc.), magnetic storage devices (hard disk drives, etc.), and recording media (magnetic disks, optical disks, etc.).

[0124] Furthermore, in the descriptions of each embodiment above, the control lines and information lines shown are those deemed necessary for the description of that embodiment, but this does not necessarily mean that all control lines and information lines related to the product are shown. In reality, it is safe to assume that almost all components are interconnected.

[0125] 10...Lower traveling body, 20...Upper slewing body, 25...Cab (operator's cabin), 30...Working equipment, 31...Boom, 32...Boom cylinder, 33...Arm, 34...Arm cylinder, 35...Attachment, 36...Bucket cylinder, 50...IMU (Accelerometer and angular velocity sensor), 60...Controller, 61...Operating state estimation unit, 62...State management calculation unit, 63...Calibration posture instruction calculation unit, 64...Basic data storage unit, 67...Display (notification device), 68...Input device (e.g., switch), 73b-73d...Pressure sensor, 74b-74d...Pressure sensor, 100...Hydraulic excavator

Claims

1. A work machine comprising: a work device having a front member; an acceleration sensor and an angular velocity sensor attached to the front member; a controller that calculates the posture of the work device using the dimensional data of the work device and the outputs of the acceleration sensor and the angular velocity sensor; and a display device that notifies the operator of the calculation results by the controller, wherein the controller outputs to the notification device an operation instruction to the operator to one of the multiple target postures and an instruction to the operator to remain stationary in one of the multiple target postures, based on the measurement state of the acceleration sensor and the angular velocity sensor, the calculated posture of the work device, and a plurality of target postures of the work device for calibration of errors of the acceleration sensor and the angular velocity sensor.

2. The work machine according to claim 1, wherein the notification device is a display mounted in the operator's cab of the work machine, the controller stores the mounting angles of the acceleration sensor and the angular velocity sensor attached to the front member, and the controller displays the current posture of the work machine and the target posture related to the operation instruction on the display together with the operation instruction.

3. The work machine according to claim 2, wherein the work device has a boom, an arm and an attachment as the front member, and the plurality of target postures, except for the first target posture initially instructed by the controller, each have a different boom angle but the same arm and attachment angles.

4. A work machine according to claim 1, further comprising an operating device operated by the operator for operating the front member, wherein the controller notifies the operator via the display device of a speed instruction, which is an instruction for the operating speed of the front member suitable for calibrating the errors of the acceleration sensor and the angular velocity sensor, when an operation instruction is given.

5. In the work machine according to claim 1, when calibration of the errors of the acceleration sensor and the angular velocity sensor is started, the controller presents a first target posture from among the plurality of target postures and an operation instruction to the first target posture on the display device, confirms whether the change to the first target posture has been completed based on the calculated posture of the work device, and after confirming the completion of the change to the first target posture, outputs a measurement start instruction to the acceleration sensor and a stationary instruction in the first target posture to the notification device, and after the completion of measurement by the acceleration sensor in the first target posture, presents a second target posture from among the plurality of target postures and an operation instruction to the second target posture on the notification device, confirms whether the change to the second target posture has been completed based on the calculated posture of the work device, and after confirming the completion of the change to the second target posture, outputs a measurement start instruction to the acceleration sensor and a stationary instruction in the second target posture to the notification device. After the completion of measurement by the acceleration sensor in the second target posture, the notification device is presented with a third target posture from among the multiple target postures and an operation instruction to the third target posture, and it is confirmed whether the change to the third target posture has been completed based on the calculated posture of the work device, and after confirmation that the change to the third target posture has been completed, the notification device is output with a measurement start instruction to the acceleration sensor and a stationary instruction in the third target posture, the angle change amount in the first time or second time is calculated by accumulating and adding the measured values ​​from the angular velocity sensor during the first time or second time, and the offset error of the acceleration sensor is estimated based on the measured values ​​of the acceleration sensor in the first target posture, the second target posture and the third target posture. When the angle change amount for the first time is calculated as the angle change amount, the angle difference between the first target posture and the second target posture is calculated based on the measured value of the acceleration sensor at the first target posture and the measured value of the acceleration sensor at the second target posture, and the scale fact error of the angular velocity sensor is estimated based on the calculated angle difference, the angle change amount for the first time, and the offset error.A work machine characterized in that, when the angle change amount for the second time is calculated as the angle change amount, the angle difference between the second target posture and the third target posture is calculated based on the measured value of the acceleration sensor at the second target posture and the measured value of the acceleration sensor at the third target posture, and the scale fact error of the angular velocity sensor is estimated based on the calculated angle difference, the angle change amount for the second time, and the offset error.

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