JP5840565B2 - Excavator - Google Patents

Description

  The present invention relates to a fall prevention device for a construction machine.

  DESCRIPTION OF RELATED ART Conventionally, the fall prevention apparatus of the hydraulic shovel provided with a boom, an arm, and a turning mechanism is known (for example, refer patent document 1).

  This overturn prevention device calculates the center of gravity of the aircraft based on the outputs of the boom angle sensor, arm angle sensor, and turning angle sensor, and calculates the safety center of gravity of the aircraft based on the outputs of the turning angle sensor and the tilt angle sensor. To do. The overturn prevention device outputs an alarm when the position of the center of gravity of the body located inside the safety center of gravity of the body approaches the boundary of the safety center of gravity of the body.

  In this manner, this overturn prevention device outputs the alarm before the possibility of overturning, thereby reliably preventing the excavator from overturning.

JP-A-7-207711

  However, the fall prevention device described in Patent Document 1 determines whether or not to output an alarm based only on the relationship between the position of the center of gravity of the aircraft and the safety center of gravity of the aircraft without detecting any signs of falling. Therefore, if the center of gravity position of the aircraft is inside the safety center of gravity of the aircraft center, even if a sign of falling appears, an alarm cannot be output and the excavator may not be prevented from falling.

  In view of the above points, an object of the present invention is to provide a fall prevention device that can more reliably prevent a fall of a construction machine.

  In order to achieve the above-described object, a fall prevention device according to an embodiment of the present invention is a fall prevention device for a construction machine, and includes an inclination angular velocity acquisition unit that acquires the inclination angular velocity of the construction machine, and the inclination angular velocity acquisition. A fall sign detection unit that detects a fall sign based on the inclination angular velocity acquired by the unit.

  By the above-described means, the present invention can provide a tipping prevention device that can prevent the tipping of the construction machine more reliably.

It is the schematic of the shovel mounted with the fall prevention apparatus which concerns on the Example of this invention. It is a functional block diagram which shows the structure of the fall prevention apparatus of FIG. It is a figure explaining the detection method of the turning position by a turning information acquisition apparatus. It is a flowchart which shows the flow of a fall sign warning process. It is a flowchart which shows the flow of a 1st threshold value determination process. It is a flowchart which shows the flow of a 2nd threshold value determination process. It is a flowchart which shows the flow of a 3rd threshold value determination process. It is a flowchart which shows the flow of a 4th threshold value determination process.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating a configuration example of an excavator 50 as a construction machine on which a fall prevention device according to an embodiment of the present invention is mounted. The upper swing body 3 is mounted on the lower traveling body 1 of the excavator 50 via the swing mechanism 2. A boom 4 is attached to the upper swing body 3, an arm 5 is attached to the tip of the boom 4, and a bucket 6 is attached to the tip of the arm 5. The boom 4, the arm 5, and the bucket 6 constitute an excavation attachment that is an example of an attachment, and are hydraulically driven by a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9. The upper swing body 3 is equipped with a power source such as an engine, a hydraulic pump driven by the power source, a control valve for controlling the flow of hydraulic oil discharged from the hydraulic pump, and the like. Further, the upper swing body 3 includes a tilt information acquisition device 21 that acquires tilt information regarding the tilt of the excavator 50, and a swing information acquisition device 22 that acquires swing information regarding the swing of the upper swing body 3 with respect to the lower traveling body 1. Installed. The upper swing body 3 is provided with a cabin 10, and a control device 20 and an output device 24 are mounted inside the cabin 10. The excavation attachment is equipped with a posture information acquisition device 23 that acquires posture information regarding the posture of the excavation attachment.

  FIG. 2 is a functional block diagram showing the configuration of the fall prevention device 100 according to the embodiment of the present invention. The fall prevention device 100 includes a control device 20 and is connected to an inclination information acquisition device 21, a turning information acquisition device 22, an attitude information acquisition device 23, and an output device 24.

  The control device 20 is a device that controls the operation of the fall prevention device 100, and is, for example, a computer including a CPU, a RAM, a ROM, and the like. In the present embodiment, the control device 20 reads programs corresponding to the functional elements of the tilt angular velocity acquisition unit 200, the turning position acquisition unit 201, the attachment posture acquisition unit 202, the fall sign detection unit 203, and the warning output unit 204 from the ROM. The data is read out and loaded into the RAM, and the processing corresponding to each functional element is executed by the CPU.

  The inclination information acquisition apparatus 21 is an apparatus that acquires inclination information related to the inclination of the construction machine main body. In the present embodiment, the tilt information acquisition device 21 is a gyro sensor that detects the tilt angular velocity of the excavator 50 with respect to the horizontal plane, and outputs the detected tilt angular velocity to the control device 20. The inclination information acquisition device 21 may be an inclination angle sensor or a horizontal sensor that detects an inclination angle of the excavator 50 with respect to the horizontal plane, or a distance measurement sensor that measures a distance between the upper swing body 3 and the ground.

  The turning information acquisition device 22 is a device that acquires turning information related to turning of the construction machine. In this embodiment, the turning information acquisition device 22 is a pair of distance measuring sensors that detect the relative turning position of the upper turning body 3 with respect to the lower traveling body 1, and outputs the detected turning position to the control device 20. To do.

  FIG. 3 is a diagram for explaining a method of detecting the relative turning position of the upper turning body 3 with respect to the lower traveling body 1 by a pair of distance measuring sensors 22 a and 22 b as the turning information acquisition device 22. FIG. 3 shows a state in which the pair of distance measuring sensors 22a and 22b attached to the bottom of the upper swing body 3 and the lower traveling body 1 are viewed from vertically above. In FIG. 3, as indicated by the dotted line, the upper swing body 3 always faces upward in the drawing. FIG. 3 shows the state in which the distance measuring sensors 22a and 22b detect the crawlers 1a and 1b of the lower traveling body 1 by black circles, and the state in which the distance measuring sensors 22a and 22b detect the ground, that is, the crawler. A state where no is detected is indicated by a white circle.

  As shown in FIG. 3A, when the lower traveling body 1 faces upward in the drawing, the distance measuring sensor 22a detects the crawler 1a, and the distance measuring sensor 22b detects the crawler 1b. In addition, as shown in FIG. 3B, when the lower traveling body 1 faces obliquely upward to the left in the figure, the distance measuring sensor 22a detects the crawler 1a and the distance measuring sensor 22b detects the ground. Further, as shown in FIG. 3C, when the lower traveling body 1 faces leftward in the figure, the distance measuring sensor 22a detects the crawler 1a, and the distance measuring sensor 22b also detects the crawler 1a. As shown in FIG. 3D, when the lower traveling body 1 faces diagonally to the left of the drawing, the distance measuring sensor 22a detects the ground, and the distance measuring sensor 22b detects the crawler 1a. As shown in FIG. 3E, when the lower traveling body 1 faces downward in the figure, the distance measuring sensor 22a detects the crawler 1b, and the distance measuring sensor 22b detects the crawler 1a. Further, as shown in FIG. 3F, when the lower traveling body 1 faces diagonally downward to the right in the figure, the distance measuring sensor 22a detects the crawler 1b, and the distance measuring sensor 22b detects the ground. As shown in FIG. 3G, when the lower traveling body 1 faces rightward in the figure, the distance measuring sensor 22a detects the crawler 1b, and the distance measuring sensor 22b also detects the crawler 1b. As shown in FIG. 3H, when the lower traveling body 1 faces diagonally upward to the right in the figure, the distance measuring sensor 22a detects the ground, and the distance measuring sensor 22b detects the crawler 1b.

  As described above, the control device 20 performs the above-described operation of the upper swing body 3 with respect to the lower traveling body 1 based on the turn direction indicated by the output of the turn operation lever (not shown) and the output results of the pair of distance measuring sensors 22a and 22b. The current relative turning position can be specified from the eight patterns of relative turning positions. In this case, for example, the control device 20 recognizes the state of FIG. 3A as the initial relative turning position.

  The turning information acquisition device 22 may be a resolver, an encoder, or the like that can detect the relative turning position of the upper turning body 3 with respect to the lower traveling body 1.

  The posture information acquisition device 23 is a device that acquires posture information regarding the posture of the construction machine. In the present embodiment, the posture information acquisition device 23 is a sensor for acquiring posture information of the excavation attachment of the excavator 50, and outputs the acquired posture information to the control device 20. Sensors for acquiring posture information include, for example, a boom angle sensor 23 a that detects the tilt of the boom 4 with respect to the upper swing body 3, an arm angle sensor 23 b that detects the tilt of the arm 5 with respect to the boom 4, and a bucket with respect to the arm 5. 6 includes a bucket angle sensor 23c for detecting the inclination of 6. Note that the bucket angle sensor 23c may be omitted.

  The output device 24 is a device that outputs various types of information. In the present embodiment, the output device 24 is a liquid crystal display, LED, speaker, buzzer, or the like installed in the cabin 10.

  Next, various functional elements in the control device 20 will be described.

  The inclination angular velocity acquisition unit 200 is a functional element for acquiring the inclination angular velocity of the construction machine. The inclination angular velocity acquisition unit 200 acquires, for example, the angular velocity output from the gyro sensor as the inclination information acquisition device 21 as the inclination angular velocity of the excavator 50.

  In addition, the inclination angular velocity acquisition unit 200 acquires, as the inclination angular velocity of the shovel 50, the change in the inclination angle output by the inclination angle sensor or the horizontal sensor as the inclination information acquisition device 21 in a predetermined period (for example, one sampling period). May be.

  Alternatively, the inclination angular velocity acquisition unit 200 may calculate the inclination angular velocity of the excavator 50 from a change amount in a predetermined period (for example, one sampling cycle) of the distance output by the distance measuring sensor as the inclination information acquisition device 21. For example, the distance measuring sensor measures the distance between the upper swing body 3 and the ground. Then, the inclination angular velocity acquisition unit 200 calculates the inclination angle of the shovel 50 based on the distance between the attachment position of the distance measurement sensor and the position of the falling fulcrum through which the inclination axis passes and the output of the distance measurement sensor. In addition, the inclination angular velocity acquisition unit 200 acquires the change in the inclination angle as the inclination angular velocity.

  The turning position acquisition unit 201 is a functional element for acquiring the relative turning position of the upper turning body 3 with respect to the lower traveling body 1. For example, the turning position acquisition unit 201 acquires one of the eight patterns of turning positions as the current turning position based on the outputs of the pair of distance measuring sensors 22a and 22b as the turning information acquisition device 22.

  Further, the turning position acquisition unit 201 may acquire one of the three patterns of turning positions as the current turning position based on the outputs of the pair of distance measuring sensors 22a and 22b. In the three patterns, the turning position where the direction of the upper swing body 3 is parallel to the direction of the lower traveling body 1 (including the opposite direction), and the direction of the upper swing body 3 is relative to the direction of the lower traveling body 1. And a turning position where the direction of the upper turning body 3 is neither parallel nor perpendicular to the direction of the lower traveling body 1.

  Further, the turning position acquisition unit 201 may acquire the relative turning position of the upper turning body 3 with respect to the lower traveling body 1 based on the output of a resolver, an encoder, or the like as the turning information acquisition device 22.

  The attachment posture acquisition unit 202 is a functional element for acquiring posture information regarding the posture of the attachment of the construction machine. For example, the attachment posture acquisition unit 202 calculates the turning radius of the excavation attachment based on the outputs of the boom angle sensor 23a and the arm angle sensor 23b, and acquires the calculated turning radius as the posture information of the excavation attachment. The turning radius of the excavation attachment means, for example, the distance between the turning shaft and the tip of the arm 5.

  Further, the attachment posture acquisition unit 202 may calculate the turning radius of the excavation attachment by additionally considering the output of the bucket angle sensor 23c. In this case, the turning radius of the excavation attachment means, for example, the distance between the turning shaft and the tip of the bucket 6.

  Note that the attachment posture acquisition unit 202 may calculate the position of the center of gravity of the excavation attachment instead of the turning radius of the excavation attachment and acquire the calculated position of the center of gravity as posture information of the excavation attachment.

  The fall sign detection unit 203 is a functional element for detecting a fall sign of the construction machine. The fall sign detection unit 203 determines that a fall sign has appeared, for example, when the tilt angular velocity acquired by the tilt angular velocity acquisition unit 200 is equal to or greater than a predetermined threshold.

  Further, the fall sign detection unit 203 may determine a predetermined threshold value to be compared according to the inclination angle of the excavator 50 acquired by the inclination information acquisition device 21. For example, the fall sign detection unit 203 determines the predetermined threshold so that the predetermined threshold decreases as the inclination angle of the excavator 50 increases. That is, the predetermined threshold is determined so that the inclination angular velocity acquired by the inclination angular velocity acquisition unit 200 easily exceeds the predetermined threshold.

  Further, the fall sign detection unit 203 may determine a predetermined threshold value to be compared according to the relative turning position of the upper turning body 3 with respect to the lower traveling body 1 acquired by the turning position acquisition unit 201. . For example, the fall sign detection unit 203 determines the predetermined threshold value such that the predetermined threshold value decreases as the angle between the direction of the lower traveling body 1 and the direction of the upper swing body 3 approaches 90 degrees.

  Moreover, the fall sign detection unit 203 may determine a predetermined threshold value to be compared according to the posture information of the excavation attachment acquired by the attachment posture acquisition unit 202. For example, the fall sign detection unit 203 determines the predetermined threshold value so that the predetermined threshold value decreases as the turning radius of the excavation attachment increases.

  Further, the fall sign detection unit 203 corresponds to a combination of at least two parameters of the inclination angle of the excavator 50, the relative turning position of the upper turning body 3 with respect to the lower traveling body 1, and the attitude information of the excavation attachment. A predetermined threshold value to be compared may be determined. At that time, the fall sign detection unit 203 may determine a predetermined threshold based on an evaluation value obtained by weighting and synthesizing each parameter.

  Further, the fall sign detection unit 203 may stop the movement of the shovel 50 or operate the shovel 50 so as to cancel the fall sign when detecting the fall sign of the shovel 50. For example, the overturn sign detection unit 203 stops an engine as a power source, or shuts off hydraulic oil flowing into the boom cylinder 7, arm cylinder 8, and bucket cylinder 9. Further, the fall sign detection unit 203 may automatically move the boom 4, the arm 5, etc. so as to cancel the fall sign.

  The warning output unit 204 is a functional element for outputting a warning to the operator of the construction machine. For example, when the fall sign detection unit 203 detects a fall sign, the warning output unit 204 outputs a control signal to the output device 24 to notify the operator of the excavator 50 that a fall sign has appeared. .

  Further, the warning output unit 204 outputs a control signal to the output device 24 when the inclination output by the inclination sensor as the inclination information acquisition device 21 is equal to or greater than a predetermined angle, and indicates that the excavator 50 may fall over. The operator may be notified.

  Next, with reference to FIG. 4, a process (hereinafter referred to as “falling sign warning process”) in which the fall prevention device 100 warns the operator that a sign of the shovel 50 has fallen will be described. FIG. 4 is a flowchart showing the flow of the overturn sign warning process. The overturn prevention device 100 repeatedly executes the overturn sign warning process at a predetermined cycle during the operation of the excavator 50. In addition, when the excavator 50 is traveling, the fall prevention device 100 may omit the fall sign detection process. This is because the inclination angular velocity of the excavator 50 may change excessively and frequently by traveling on rough ground.

  First, the control device 20 of the fall prevention device 100 acquires the inclination angular velocity of the excavator 50 by the inclination angular velocity acquisition unit 200 (step S1).

  After that, the control device 20 determines whether or not the fall sign of the excavator 50 has appeared by the fall sign detection unit 203 (step S2). Specifically, the fall sign detection unit 203 compares the inclination angular velocity acquired by the inclination angular velocity acquisition unit 200 with a predetermined threshold TH.

  When it is determined that a sign of the excavator 50 has fallen, that is, when the inclination angular velocity is equal to or higher than the threshold value TH (YES in step S <b> 2), the fall sign detecting unit 203 outputs a control signal to the warning output unit 204. The warning output unit 204 outputs a warning according to the control signal from the fall sign detection unit 203 (step S3). For example, the warning output unit 204 sounds a buzzer to notify the operator of the shovel 50 that a sign of the shovel 50 has fallen.

  On the other hand, when it is determined that there is no sign of the shovel 50 falling, that is, when the inclination angular velocity is less than the threshold value TH (NO in step S2), the fall sign detecting unit 203 controls the warning output unit 204 with a control signal. This is the end of the fall sign warning process.

  Next, a process (hereinafter referred to as “first threshold determination process”) in which the fall prevention device 100 determines a predetermined threshold TH according to the inclination angle of the excavator 50 will be described with reference to FIG. 5. FIG. 5 is a flowchart showing the flow of the first threshold value determination process, and the overturn prevention device 100 repeatedly executes the first threshold value determination process at a predetermined cycle while the excavator 50 is in operation. The fall prevention device 100 desirably executes the first threshold value determination process at the same cycle as the fall sign warning process before executing the fall sign warning process.

  First, the control device 20 acquires the inclination angle of the excavator 50 based on the output of the inclination angle sensor as the inclination information acquisition device 21 (step S11).

  Thereafter, the control device 20 determines a predetermined threshold value TH according to the inclination angle of the excavator 50 by the fall sign detection unit 203 (step S12). Specifically, the fall sign detection unit 203 decreases the threshold TH as the inclination of the excavator 50 with respect to the horizontal plane increases. This is because when the excavator 50 is located on the slope, the fall is more likely to occur than when the excavator 50 is located on the horizontal plane.

  Next, a process (hereinafter referred to as “second threshold determination process”) in which the fall prevention device 100 determines a predetermined threshold TH according to the turning position of the excavator 50 will be described with reference to FIG. 6. FIG. 6 is a flowchart showing the flow of the second threshold value determination process, and the overturn prevention device 100 repeatedly executes the second threshold value determination process at a predetermined cycle during the operation of the excavator 50. The fall prevention device 100 desirably executes the second threshold value determination process at the same cycle as the fall sign warning process before executing the fall sign warning process.

  First, the control device 20 acquires the turning position of the excavator 50 by the turning position acquisition unit 201 (step S21).

  Thereafter, the control device 20 determines a predetermined threshold value TH according to the turning position of the excavator 50 by the fall sign detection unit 203 (step S22). Specifically, the fall sign detection unit 203 decreases the threshold value TH as the angle between the direction of the lower traveling body 1 and the direction of the upper swing body 3 approaches 90 degrees. When the direction of the lower traveling body 1 and the direction of the upper revolving body 3 are orthogonal to each other, the direction of the lower traveling body 1 and the direction of the upper revolving body 3 are more likely to fall than when the direction of the lower traveling body 1 and the direction of the upper revolving body 3 are parallel. is there.

  Next, a process (hereinafter referred to as “third threshold determination process”) in which the fall prevention device 100 determines a predetermined threshold TH according to the attitude information of the excavation attachment will be described with reference to FIG. FIG. 7 is a flowchart showing the flow of the third threshold value determination process, and the overturn prevention device 100 repeatedly executes the third threshold value determination process at a predetermined cycle during the operation of the excavator 50. The fall prevention device 100 desirably executes the third threshold value determination process at the same cycle as the fall sign warning process before executing the fall sign warning process.

  Initially, the control apparatus 20 acquires the attitude | position information of a digging attachment by the attachment attitude | position acquisition part 202 (step S31).

  Then, the control apparatus 20 determines the predetermined threshold value TH according to the posture information of the excavation attachment by the fall sign detection unit 203 (step S32). Specifically, the fall sign detection unit 203 decreases the threshold value TH as the turning radius of the excavation attachment increases. This is because, when the turning radius of the excavation attachment is large, a fall is more likely to occur than when the turning radius is small.

  Next, referring to FIG. 8, the fall prevention device 100 determines a predetermined threshold TH according to the combination of the inclination angle of the excavator 50, the turning position of the excavator 50, and the posture information of the excavation attachment (hereinafter, referred to as “the threshold value TH”). The “fourth threshold value determination process” will be described. FIG. 8 is a flowchart showing the flow of the fourth threshold value determination process, and the overturn prevention device 100 repeatedly executes the fourth threshold value determination process at a predetermined cycle while the excavator 50 is in operation. The fall prevention device 100 desirably executes the fourth threshold value determining process at the same cycle as the fall sign warning process before executing the fall sign warning process.

  First, the control device 20 acquires the inclination angle of the excavator 50 based on the output of the inclination angle sensor as the inclination information acquisition device 21 (step S41).

  Moreover, the control apparatus 20 acquires the turning position of the shovel 50 by the turning position acquisition part 201 (step S42).

  Moreover, the control apparatus 20 acquires the attitude | position information of a digging attachment by the attachment attitude | position acquisition part 202 (step S43).

  Note that steps S41 to S43 are out of order, and three processes may be executed simultaneously.

  After that, the control device 20 determines a predetermined threshold value TH according to the combination of the inclination angle of the excavator 50, the turning position of the excavator 50, and the attitude information of the excavation attachment by the fall sign detection unit 203 (step S44). The fall sign detection unit 203 has, for example, the inclination angle of the excavator 50 equal to or greater than a predetermined angle, the direction of the lower traveling body 1 and the direction of the upper swing body 3 are orthogonal, and the turning radius of the excavation attachment is greater than or equal to a predetermined value. In this case, the threshold value TH is minimized. This is because a fall is most likely to occur.

  In addition, the fall prevention device 100 may determine the predetermined threshold value TH according to two combinations of the inclination angle of the shovel 50, the turning position of the shovel 50, and the attitude information of the excavation attachment.

  With the above configuration, the overturn prevention device 100 detects the sign of the excavator 50 overturning based on a change in the inclination angle of the excavator 50 and issues a warning to the operator of the excavator 50, thereby preventing the overturn of the excavator 50. Can be prevented.

  In addition, the fall prevention device 100 detects the fall of the excavator 50 based on the change in the inclination angle of the excavator 50 regardless of the attitude information of the excavation attachment and the relative turning position of the upper turning body 3 with respect to the lower traveling body 1. Can detect signs. Therefore, it is possible to detect a sign of the excavator 50 falling over easily and quickly without executing complicated calculations. Further, since it is not affected by parameters other than the inclination angle, it is possible to detect a sign of the excavator 50 falling over with high reliability while suppressing erroneous detection. Further, in the fall prevention device 100, the sensors other than the inclination information acquisition device 21, that is, the turning information acquisition device 22 and the posture information acquisition device 23 may be omitted, and the cost can be reduced.

  In addition, the fall prevention device 100 issues a warning to the operator of the excavator 50 even though there is no sign of the excavator 50 falling, that is, the inclination angle is small or not present. It is possible to prevent the user from feeling uncomfortable.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, in the above-described embodiment, the fall prevention device 100 is applied to the excavator 50, but may be applied to other construction machines such as a crane.

  DESCRIPTION OF SYMBOLS 1 ... Lower traveling body 2 ... Turning mechanism 3 ... Upper turning body 4 ... Boom 5 ... Arm 6 ... Bucket 7 ... Boom cylinder 8 ... Arm cylinder 9 ... Bucket cylinder 10 ... cabin 20 ... control device 21 ... tilt information acquisition device 22 ... turn information acquisition device 23 ... attitude information acquisition device 23a ... boom angle sensor 23b ... arm Angle sensor 23c ... Bucket angle sensor 24 ... Output device 50 ... Excavator 100 ... Fall prevention device 200 ... Inclination angular velocity acquisition unit 201 ... Turning position acquisition unit 202 ... Attachment posture acquisition Section 203 ... Falling sign detection section 204 ... Warning output section

Claims (6)

An excavator comprising a lower traveling body and an upper swinging body mounted on the lower traveling body via a turning mechanism,
An inclination angular velocity acquisition unit for acquiring the inclination angular velocity of the excavator ;
A fall sign detection unit for detecting a fall sign based on the tilt angular speed acquired by the tilt angular speed acquisition unit;
A turning position obtaining unit for obtaining a turning position of the upper turning body relative to the lower traveling body ,
The fall sign detection unit determines a predetermined threshold according to the relative turning position acquired by the turning position acquisition unit, and detects that the inclination angular velocity is equal to or higher than the predetermined threshold as a fall sign. ,
The predetermined threshold value is smaller as the angle between the direction of the lower traveling body and the direction of the upper turning body is closer to 90 degrees,
Excavator . An excavator comprising a lower traveling body, an upper revolving body mounted on the lower traveling body via a turning mechanism, and an attachment attached to the upper revolving body,
An inclination angular velocity acquisition unit for acquiring the inclination angular velocity of the excavator;
  A fall sign detection unit for detecting a fall sign based on the tilt angular speed acquired by the tilt angular speed acquisition unit;
  An attachment posture acquisition unit for acquiring the posture of the attachment;
  The fall sign detection unit determines a predetermined threshold according to the posture of the attachment acquired by the attachment posture acquisition unit, and detects that the tilt angular velocity is equal to or higher than the predetermined threshold as a fall sign.
  The predetermined threshold is smaller as the turning radius of the attachment is larger,
  Excavator. An inclination angle sensor for detecting an inclination angle of the excavator with respect to a horizontal plane;
The tilt angular velocity acquisition unit acquires a change in tilt angle detected by the tilt angle sensor as a tilt angular velocity,
The fall symptom detecting unit determines the predetermined threshold value according to the inclination angle the tilt angle sensor detects,
The predetermined threshold value is smaller as the tilt angle detected by the tilt angle sensor is larger,
The shovel according to claim 1 or 2. Comprising a swivel position acquisition unit that acquires a relative pivoting position of the upper swing structure to the previous SL undercarriage,
The fall symptom detecting unit determines the predetermined threshold value depending on the relative pivoting position in which the pivot position acquisition unit acquires,
The predetermined threshold value is smaller as the angle between the direction of the lower traveling body and the direction of the upper turning body is closer to 90 degrees,
The shovel according to claim 2 . And an attachment attached to the upper rotating body,
And an attachment posture acquisition unit that acquires the attitude of the previous SL attachment,
The fall symptom detecting unit determines the predetermined threshold in accordance with the attitude of the attachment the attachment posture acquisition section acquires,
The predetermined threshold is smaller as the turning radius of the attachment is larger,
The excavator according to claim 1 . The turning position acquisition unit acquires a relative turning position of the upper turning body with respect to the lower traveling body, based on outputs of a pair of distance measuring sensors attached downward to the upper turning body.
The excavator according to claim 1 or 4.

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