Overturning evaluation system, overturning evaluation method and work machine

Abstract

To provide an overturning evaluation system for evaluating the overturning possibility of a work machine in view of the relation of a turning movement to an overturning direction.SOLUTION: An energy calculation part calculates an energy amount required for overturning of a work machine when a side serves as a rotation axis, for each of the multiple sides of a supporting polygon of the work machine. An evaluation part evaluates the overturning possibility of the work machine on the basis of the calculated energy amount for each side.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a fall assessment system, a fall assessment method, and a work machine. [Background technology]

[0002] Patent Document 1 discloses a technology that calculates the ZMP (Zero Moment Point) of a work machine and notifies the operator of information regarding the possibility of tipping over. The ZMP is the point where the moments in the pitch and roll axis directions become zero. If the ZMP is located on or inside the side of a support polygon that connects the work machine and the contact point without forming a concave, it can be determined that the work machine is stably on the ground. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2011 / 148946 Summary of the Invention [Problem to be solved by the invention]

[0004] The calculation method described in Patent Document 1 may determine that there is a high possibility of tipping over when the inertial force of the work machine itself causes the machine body to lift up. For this reason, a method is sometimes used to evaluate the possibility of tipping over using an energy stability margin instead of the ZMP. The energy stability margin refers to the energy required to tip over in a certain attitude state.

[0005] The support polygon of a work machine may change depending on the working state. For example, in a hydraulic excavator, the upper rotating body rotates relative to the lower traveling body, and the position of the center of gravity relative to the support polygon changes as the machine rotates.

[0006] An object of the present disclosure is to provide a tipping evaluation system, a tipping evaluation method, and an excavation machine that can evaluate the possibility of tipping of a work machine in consideration of the relationship between the swing operation and the tipping direction. [Means for solving the problem]

[0007] According to a first aspect of the present invention, a tipping evaluation system is a tipping evaluation system for a work machine having a work implement, and includes a processor. The processor includes an energy calculation unit that calculates, for each of a plurality of sides of a support polygon of the work machine, the amount of energy required for the work machine to tip over when the side serves as an axis of rotation, and an evaluation unit that evaluates the possibility of the work machine tipping over based on the calculated amount of energy for each of the sides.

[0008] According to a second aspect of the present invention, a tipping evaluation method includes a step of calculating, for each of a plurality of sides of a support polygon of a work machine having a work implement, the amount of energy required for the work machine to tip over when the side serves as an axis of rotation, and a step of evaluating the possibility of the work machine tipping over based on the calculated amount of energy for each of the sides.

[0009] According to a third aspect of the present invention, a work machine comprises a running body, a rotating body rotatably supported on the running body, a work implement attached to the rotating body, and a processor, the processor comprising a center of gravity position calculation unit that calculates the position of the center of gravity of the work machine, an energy calculation unit that calculates, for each of a plurality of sides of the support polygon of the running body, the amount of energy required for the work machine to tip over when the side serves as the axis of rotation based on the position of the center of gravity of the work machine, and an evaluation unit that evaluates the possibility of the work machine tipping over based on the calculated amount of energy for each of the sides. [Effects of the Invention]

[0010] According to the above aspect, it is possible to evaluate the possibility of the work machine tipping over in consideration of the relationship between the turning operation and the tipping direction. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing the configuration of a work machine according to a first embodiment. [Figure 2] 1 is a schematic block diagram showing the configuration of a control device according to a first embodiment. [Figure 3] FIG. 10 is a diagram for explaining an energy stability margin. [Figure 4] FIG. 10 is a diagram illustrating the relationship between the energy stability margin and the position of the center of gravity. [Figure 5] FIG. 2 is a diagram showing an example of a fall risk indication according to the first embodiment. [Figure 6] 5 is a flowchart showing the operation of the control device according to the first embodiment. [Figure 7] FIG. 10 is a schematic block diagram showing the configuration of a control device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] First Embodiment <Configuration of work machine 100> Hereinafter, the embodiments will be described in detail with reference to the drawings. 1 is a schematic diagram showing the configuration of a work machine according to a first embodiment. The work machine according to the first embodiment is, for example, a hydraulic excavator. The work machine 100 includes a traveling body 110, a rotating body 130, a work implement 150, a cab 170, and a control device 190.

[0013] The running body 110 supports the work machine 100 so that it can run. The running body 110 is, for example, a pair of left and right endless tracks. The pair of endless tracks are arranged parallel to a line extending in the direction of travel and are line-symmetrical. Therefore, the support polygon represented by the convex hull of the ground contact points of the running body 110 in the first embodiment is a rectangle. A convex hull is the smallest convex polygon that contains all specific points. A specific point is, for example, a point where the crawler tracks contact the ground. Hereinafter, the rectangle that is the convex hull of the ground contact points of the running body 110 will be referred to as the support rectangle R.

[0014] The rotating body 130 is supported by the running body 110 so as to be able to rotate around a rotation center. The work implement 150 is supported on the front of the revolving unit 130 so that it can be driven in the vertical direction. The work implement 150 is driven hydraulically. The work implement 150 includes a boom 151, an arm 152, and a bucket 153. The base end of the boom 151 is rotatably attached to the revolving unit 130. The base end of the arm 152 is rotatably attached to the tip of the boom 151. The base end of the bucket 153 is rotatably attached to the tip of the arm 152. Here, the portion of the revolving unit 130 to which the work implement 150 is attached is referred to as the front. Furthermore, with respect to the revolving unit 130, the opposite portion from the front portion will be referred to as the rear portion, the left portion will be referred to as the left portion, and the right portion will be referred to as the right portion.

[0015] The operator's cab 170 is provided at the front of the revolving unit 130. Inside the operator's cab 170, there are provided an operating device for the operator to operate the work machine 100, and an alarm device for notifying the operator of the risk of tipping over. The alarm device according to the first embodiment notifies the operator of the risk of tipping over by means of a speaker and a display device.

[0016] The control device 190 controls the traveling body 110, the revolving body 130, and the work machine 150 based on the operation of the operation device by the operator. The control device 190 is provided inside the operator's cab 170, for example.

[0017] The work machine 100 is equipped with a plurality of sensors for detecting the work state of the work machine 100. Specifically, the work machine 100 is equipped with a tilt detector 101, a swing angle sensor 102, a boom angle sensor 103, an arm angle sensor 104, a bucket angle sensor 105, and a payload meter 106.

[0018] The inclination detector 101 measures the acceleration and angular velocity of the rotating unit 130 and detects the inclination (e.g., roll angle and pitch angle) of the rotating unit 130 relative to a horizontal plane based on the measurement results. The inclination detector 101 is installed, for example, below the operator's cab 170. An example of the inclination detector 101 is an IMU (Inertial Measurement Unit).

[0019] The turning angle sensor 102 is provided at the center of rotation of the rotating body 130 and detects the turning angle between the running body 110 and the rotating body 130. The measurement value of the turning angle sensor 102 indicates zero when the directions of the running body 110 and the rotating body 130 are the same.

[0020] The boom angle sensor 103 detects the boom angle, which is the rotation angle of the boom 151 relative to the revolving structure 130. The boom angle sensor 103 may be an IMU attached to the boom 151. In this case, the boom angle sensor 103 detects the boom angle based on the inclination of the boom 151 with respect to the horizontal plane and the inclination of the revolving structure measured by the inclination detector 101. The measurement value of the boom angle sensor 103 indicates zero when the direction of a line passing through the base end and tip end of the boom 151 coincides with the fore-and-aft direction of the revolving structure 130. Note that the boom angle sensor 103 according to other embodiments may be a stroke sensor attached to a boom cylinder. Furthermore, the boom angle sensor 103 according to other embodiments may be an angle sensor provided on a pin connecting the revolving structure 130 and the boom 151.

[0021] The arm angle sensor 104 detects the arm angle, which is the rotation angle of the arm 152 relative to the boom 151. The arm angle sensor 104 may be an IMU attached to the arm 152. In this case, the arm angle sensor 104 detects the arm angle based on the inclination of the arm 152 with respect to the horizontal plane and the boom angle measured by the boom angle sensor 103. The measurement value of the arm angle sensor 104 indicates zero when the direction of a line passing through the base end and tip end of the arm 152 matches the direction of a line passing through the base end and tip end of the boom 151. Note that, in other embodiments, the arm angle sensor 104 may calculate the angle by attaching a stroke sensor to the arm cylinder. The arm angle sensor 104 may also be a rotation sensor provided on a pin connecting the boom 151 and the arm 152.

[0022] The bucket angle sensor 105 detects the bucket angle, which is the rotation angle of the bucket 153 relative to the arm 152. It may be a stroke sensor provided in a bucket cylinder that drives the bucket 153. In this case, the bucket angle sensor 105 detects the bucket angle based on the stroke amount of the bucket cylinder. The measurement value of the bucket angle sensor 105 indicates zero when the direction of a line passing through the base end and cutting edge of the bucket 153 matches the direction of a line passing through the base end and tip of the arm 152. Note that the bucket angle sensor 105 according to another embodiment may be an angle sensor provided on a pin that connects the arm 152 and the bucket 153. Furthermore, the bucket angle sensor 105 according to another embodiment may be an IMU attached to the bucket 153.

[0023] The payload meter 106 measures the weight of the load held in the bucket 153. The payload meter 106 measures, for example, the bottom pressure of the cylinder of the boom 151 and converts it into the weight of the load. Alternatively, for example, the payload meter 106 may be a load cell.

[0024] Configuration of the control device 190 2 is a schematic block diagram showing the configuration of the control device 190 according to the first embodiment. The control device 190 is a computer including a processor 210, a main memory 230, a storage 250, and an interface 270.

[0025] Storage 250 is a non-transitory tangible storage medium. Examples of storage 250 include a magnetic disk, an optical disk, a magneto-optical disk, and a semiconductor memory. Storage 250 may be an internal medium directly connected to the bus of control device 190, or may be an external medium connected to control device 190 via interface 270 or a communication line. Storage 250 stores a program for controlling work machine 100.

[0026] The program may be for realizing some of the functions to be performed by the control device 190. For example, the program may be combined with other programs already stored in the storage 250 or other programs implemented in other devices to perform the functions. In other embodiments, the control device 190 may include a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device) in addition to or instead of the above configuration. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions realized by the processor may be realized by the integrated circuit.

[0027] The storage 250 stores geometry data representing the dimensions and center of gravity of the running body 110, the revolving body 130, the boom 151, the arm 152, and the bucket 153, as well as the weights of the running body 110, the revolving body 130, the boom 151, the arm 152, and the bucket 153. The geometry data is data representing the position of an object in a predetermined coordinate system. The coordinate systems according to the first embodiment include a world coordinate system and a local coordinate system. The world coordinate system is a system in which the Z coordinate system extends in the vertical direction. w axis and Z w Orthogonal to the X axis w axis and Y w A local coordinate system is a Cartesian coordinate system with the origin at the reference point of an object.

[0028] The geometry data of the vehicle 110 is the center of gravity position (x tb_com , y tb_com , z tb_com ), and the length L, width w, and height h of the endless track. The vehicle coordinate system is an X coordinate system that extends in the front-to-rear direction with the turning center of the vehicle 110 as the reference. tb axis, Y extending left and right tb Axis, extending vertically Z tb It is a coordinate system consisting of axes.

[0029] The geometry data of the rotating body 130 is the position (x bm , y bm , z bm ), the position of the origin of the vehicle coordinate system (x tb , y tb , z tb ) and the center of gravity position (x sb_com , y sb_com , z sb_com The rotating body coordinate system is an X axis extending in the front-rear direction with the center of rotation of the rotating body 130 as the reference. sb axis, Y extending left and right sb Axis, extending vertically Z sb It is a coordinate system consisting of axes.

[0030] The geometry data of the boom 151 is the position (x am , y am , z am ) and the center of gravity position of the boom 151 (x bm_com , y bm_com , z bm_com The boom coordinate system is based on the position of the pin connecting the boom 151 and the rotating body 130, and is defined by an X axis extending in the longitudinal direction. bm Y axis extends in the direction in which the pin extends bm axis, X bm Axis and Y bm Z perpendicular to the axis bm It is a coordinate system consisting of axes.

[0031] The geometry data of the arm 152 is the position (x bk , y bk , z bk ) and the center of gravity position of the arm 152 (x am_com , y am_com , z am_com The arm coordinate system is based on the position of the pin connecting the arm 152 and the boom 151, and is defined by an X axis extending in the longitudinal direction. am Y axis extends in the direction in which the pin extends am axis, X am Axis and Y am Z perpendicular to the axis am It is a coordinate system consisting of axes.

[0032] The geometry data of the bucket 153 is the cutting edge position (x ed , y ed , z ed ), the center of gravity of bucket 153 (x bk_com , y bk_com , z bk_com ), and the center of gravity of the cargo (x pl_com , y pl_com , z pl_com The bucket coordinate system is based on the position of the pin connecting the bucket 153 and the arm 152, and is expressed as X θ extending in the direction of the cutting edge.bk Y axis extends in the direction in which the pin extends bk axis, x bk Axis and Y bk Z perpendicular to the axis bk It is a coordinate system consisting of axes.

[0033] <Software Configuration> The processor 210 executes the program to function as an acquisition unit 211, a position identification unit 212, a center of gravity calculation unit 213, an energy calculation unit 214, a normalization unit 215, an evaluation unit 216, and an output unit 217.

[0034] The acquisition unit 211 acquires measurement values ​​from the tilt detector 101, the swing angle sensor 102, the boom angle sensor 103, the arm angle sensor 104, the bucket angle sensor 105, and the payload meter 106, respectively.

[0035] The position identification unit 212 identifies the center of gravity position of each part of the work machine 100 based on the various measurement values ​​acquired by the acquisition unit 211 and the geometry data recorded in the storage 250. Specifically, the position identification unit 212 identifies the center of gravity positions in the world coordinate system of the traveling body 110, the revolving body 130, the boom 151, the arm 152, the bucket 153, and the load in the following procedure.

[0036] The position specifying unit 212 determines the pitch angle θ p and roll angle θ r Based on the measured values, the rotating body-world transformation matrix T is calculated using the following formula (1) to transform the rotating body coordinate system into the world coordinate system. sb w Generate the rotating body-world transformation matrix T sb w is Y sb Pitch angle θ around the axis p and a rotation matrix that rotates by X sb Roll angle θ around the axis r It is expressed by multiplying it by a rotation matrix that rotates the object by the given amount.

[0037]

number

[0038] The position specifying unit 212 determines the rotation angle θ of the running body 110 and the rotating body 130 acquired by the acquisition unit 211. s Based on the measured values ​​and the geometry data of the rotating body 130, a running body-rotating body transformation matrix T for transforming from the running body coordinate system to the rotating body coordinate system is calculated using the following equation (2): tb sb Generate the vehicle-rotating vehicle transformation matrix T tb sb is Z tb Pitch angle θ around the axis p and the deviation between the origin of the rotating body coordinate system and the origin of the running body coordinate system (x tb , y tb , z tb ) is a matrix that translates the rotational body-world transformation matrix T sb w and the vehicle-rotor transformation matrix T tb sb The vehicle-world transformation matrix T is used to convert from the vehicle coordinate system to the world coordinate system. tb w Generate.

[0039]

number

[0040] The position specifying unit 212 determines the boom angle θ bm Based on the measurement values ​​and the geometry data of the rotating unit 130, a boom-to-rotating unit transformation matrix T for transforming from the boom coordinate system to the rotating unit coordinate system is calculated using the following equation (3): bm sb Generate the boom-rotating body transformation matrix T bm sb is Y bm Boom angle θ around the axis bm and the deviation between the origin of the rotating body coordinate system and the origin of the boom coordinate system (x bm , y bm , z bm) is a matrix that translates the rotational body-world transformation matrix T sb w and the boom-rotating body transformation matrix T bm sb The boom-to-world transformation matrix T is used to transform from the boom coordinate system to the world coordinate system. bm w Generate.

[0041]

number

[0042] The position specifying unit 212 determines the arm angle θ acquired by the acquisition unit 211. am Based on the measurement values ​​and the geometry data of the boom 151, an arm-boom transformation matrix T for transforming from the arm coordinate system to the boom coordinate system is calculated by the following equation (4). am bm The arm-boom transformation matrix T am bm is Y am Arm angle θ around the axis am and the deviation between the origin of the boom coordinate system and the origin of the arm coordinate system (x am , y am , z am ) is a matrix that translates the position by the boom-world transformation matrix T bm w and the arm-boom transformation matrix T am bm The arm-world transformation matrix T is used to transform from the arm coordinate system to the world coordinate system. am w Generate.

[0043]

number

[0044] The position specifying unit 212 determines the bucket angle θ bkBased on the measured values ​​and the geometry data of the arm 152, a bucket-arm transformation matrix T for transforming from the bucket coordinate system to the arm coordinate system is calculated using the following equation (5): bk am Generate the bucket-arm transformation matrix T bk am is Y bk Bucket angle θ around the axis bk and the deviation between the origin of the arm coordinate system and the origin of the bucket coordinate system (x bk , y bk , z bk ) is a matrix that translates the arm-world transformation matrix T am w and the bucket-arm transformation matrix T bk am The bucket-world transformation matrix T is used to transform from the bucket coordinate system to the world coordinate system by multiplying the bk w Generate.

[0045]

number

[0046] The position specifying unit 212 determines the relative position (x tb_com , y tb_com , z tb_com ) into the vehicle-world transformation matrix T tb w Using the absolute position T tb_com w The position specifying unit 212 converts the relative position (x sb_com , y sb_com , z sb_com ) into the rotating body-world transformation matrix T sb w Using the absolute position T sb_com w The position specifying unit 212 converts the relative position (x bm_com , y bm_com , zbm_com ) into the Boom-World transformation matrix T bm w Using the absolute position T bm_com w The position specifying unit 212 converts the relative position (x am_com , y am_com , z am_com ) into the arm-world transformation matrix T am w Using the absolute position T am_com w The position specifying unit 212 converts the relative position (x bk_com , y bk_com , z bk_com ) into the bucket-world transformation matrix T bk w Using the absolute position T bk_com w The position specifying unit 212 converts the relative position (x pl_com , y pl_com , z pl_com ) into the bucket-world transformation matrix T bk w Using the absolute position T pl_com w Convert to.

[0047] The center of gravity calculation unit 213 calculates the center of gravity position of the entire working machine 100 based on the center of gravity positions and weights of the parts identified by the position identification unit 212. Specifically, the center of gravity calculation unit 213 calculates the center of gravity position of the entire working machine 100 based on the known weight m of the traveling body 110. tb , weight of the rotating body 130 m sb , Weight of boom 151 m bm , weight of arm 152 m am and the weight of the bucket 153 m bk and the measurement value m of the payload meter 106 pl Based on this, the affine matrix T com w ´ and the affine matrix T com w ´ to the center of gravity position T of the entire work machine 100 comw Calculate.

[0048]

number

[0049] By calculating equation (6), the center of gravity calculation unit 213 calculates a 4×4 affine matrix T com w ´ is obtained.

[0050]

number

[0051] The center of gravity calculation unit 213 calculates the obtained affine matrix T com w By extracting the translational component of ´, i.e., the affine matrix T com w By replacing the rotational component of ' with a unit matrix, the center of gravity position T com w Calculate.

[0052]

number

[0053]

number

[0054] That is, the energy stability margin is determined by the height z of the center of gravity of the work machine 100. com w and the height z of the center of gravity of the work machine 100 when the center of gravity is located directly above the rotation shaft. r_comw is obtained by multiplying the difference Q between these values ​​by the weight M of the work machine 100 and the gravitational acceleration g. The energy calculation unit 214 calculates the energy stability margin by setting each side of the support rectangle R that includes the ground contact point of the running object 110 as the rotation axes ax1-ax4.

[0055] Rotation axis X ax axis, and the axis extending vertically is Z ax axis, x ax axis and Z ax The axis perpendicular to the Y axis ax When considering a rotation axis coordinate system with the axis as the axis, the rotation axis-world transformation matrix T is used to convert from the rotation axis coordinate system to the world coordinate system. ax1 w ~T ax4 w is expressed as in equation (10) using the length L of the endless track of the running body 110, the height h of the endless track, and the width w of the endless track.

[0056]

number

[0057] The energy calculation unit 214 calculates the rotation axis-to-world transformation matrix T obtained by equation (10). ax w Based on this, the tilt angle θ around the rotation axis ax of the earth's surface gnd ax The energy calculation unit 214 also calculates the rotation axis-world transformation matrix T ax w and the center of gravity position T of the entire work machine 100 com w The product of these two gives the relative position T of the center of gravity of the work machine 100 in the rotation axis coordinate system. com ax The energy calculation unit 214 calculates the relative position T of the center of gravity as shown in equation (11). com ax Z ax axis translational component z com ax and Y ax axis translational component y com axBased on this, the elevation angle θ of the center of gravity as seen from the axis of rotation com ax Calculate.

[0058]

number

[0059] The energy calculation unit 214 calculates the tilt angle θ as shown in equation (12). gnd ax and the elevation angle of the center of gravity θ com ax Based on this, the rotation angle θ required for the center of gravity of the entire work machine 100 to be positioned directly above the rotation axis is calculated. sup ax Calculate.

[0060]

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[0061] The energy calculation unit 214 calculates the relative position T com ax and rotation angle θ sup ax and the rotation axis-world transformation matrix T ax w Based on this, the work machine 100 is rotated at a rotation angle θ sup ax The absolute position T of the center of gravity of the entire work machine 100 when rotated by r_com w Calculate.

[0062]

number

[0063] The energy calculation unit 214 calculates the absolute position T of the center of gravity after rotation. r_com w Z w axis translational component z r_com wand the absolute position of the center of gravity before rotation T com w Z w axis translational component z com w The difference Q between these is calculated as the energy stability margin. The energy stability margin obtained here is equal to the energy normalized to the unit of length. As shown in equation (7), the absolute position T of the center of gravity after rotation is r_com w and the absolute position of the center of gravity before rotation T com w Z w The difference in axial translation components Q is multiplied by the weight of the work machine 100 and the acceleration of gravity to obtain the unnormalized energy stability margin. Therefore, the absolute position of the center of gravity after rotation T r_com w and the absolute position of the center of gravity before rotation T com w Z w Calculating the difference Q of the axial translation component is equivalent to calculating the energy stability margin.

[0064] The normalization unit 215 calculates a normalized margin (normalized value) by dividing the energy stability margin calculated by the energy calculation unit 214 by the length of another side perpendicular to the side related to the rotation axis. The normalized margin is a dimensionless quantity that indicates the degree of approximation to the most stable state of the work machine 100 with respect to rotation about the rotation axis. For example, the normalization unit 215 calculates the normalized margin by dividing the energy stability margin when rotating around the side end of the endless track (around the rotation axis ax2 or ax4) by the width w of the endless track. Alternatively, for example, the normalization unit 215 calculates the normalized margin by dividing the energy stability margin when rotating around a straight line connecting the front or rear ends of the pair of endless track (around the rotation axis ax1 or ax3) by the length L of the endless track.

[0065] Fig. 4 is a diagram showing the relationship between the energy stability margin and the position of the center of gravity. As shown in Fig. 4, the energy stability margin calculated by equation (7) is higher the lower the position of the center of gravity and the greater the distance between the rotation axis and the center of gravity. In other words, the energy stability margin of the work machine 100 for a certain rotation axis is greatest when the center of gravity is located on the support rectangle R and at the point farthest from the rotation axis. Therefore, the energy stability margin calculated by the energy calculation unit 214 can be made dimensionless by dividing the energy stability margin by the length of the other side perpendicular to the side related to the rotation axis.

[0066] The evaluation unit 216 evaluates the risk of tipping over of the work machine 100 based on the normalized margin calculated by the normalization unit 215. Specifically, the evaluation unit 216 determines whether or not the magnitude of the normalized margin for each rotation axis exceeds a threshold value. The threshold value may be a caution threshold value th c , warning threshold th w However, attention threshold th c is the warning threshold th w Also, each threshold is greater than 0 and less than 1.

[0067] The output unit 217 generates a sign indicating the risk of tipping over of the work machine to be displayed on the display device of the warning device based on the evaluation result of the evaluation unit 216. FIG. 5 is a diagram showing an example of a sign of the risk of tipping over according to the first embodiment. The sign of the risk of tipping over displays an icon I1 of the running unit 110, an icon I2 of the revolving unit 130, and multiple indicator marks I3. The icon I2 of the revolving unit 130 is always displayed with the front (forward) facing upward. The icon I1 of the running unit 110 displays the risk of tipping over when the revolving angle θ sThe indicator marks I3 are displayed at an angle depending on the direction of the tipping risk. The multiple indicator marks I3 are displayed surrounding the icon I2 of the rotating unit 130. In the example shown in FIG. 5, the tipping risk indication has 12 indicator marks I3 arranged at equal intervals on a circle centered on the icon I2. The indicator marks I3 change color to indicate the level of tipping risk in the direction indicated by the indicator mark I3. For example, the indicator mark I3 turns yellow when the tipping risk is at a caution level, and turns red when the tipping risk is at a warning level.

[0068] The output unit 217 outputs the evaluation result of the evaluation unit 216 to an alarm device. The output unit 217 outputs the generated indication indicating the risk of the work machine tipping over to the alarm device. Furthermore, the output unit 217 outputs an instruction to the alarm device to sound an alarm when the normalized margin for at least one rotation axis falls below the alarm threshold for a certain period of time or more.

[0069] <<Operation of the control device 190>> 6 is a flowchart showing the operation of the control device 190 according to the first embodiment. When the control device 190 starts up and executes a program, it executes the following processing at regular intervals. The acquisition unit 211 acquires measurement values ​​from the tilt detector 101, the swing angle sensor 102, the boom angle sensor 103, the arm angle sensor 104, the bucket angle sensor 105, and the payload meter 106 (step S1). The position identification unit 212 identifies the absolute positions of the traveling body 110, the swing body 130, the boom 151, the arm 152, the bucket 153, and the center of gravity of the load based on the various measurement values ​​acquired in step S1 and the geometry data recorded in the storage 250 (step S2).

[0070] The center of gravity calculation unit 213 calculates the absolute position T com wBased on the center of gravity position calculated in step S3, the energy calculation unit 214 calculates the height Q, which corresponds to the energy stability margin, which is the amount of energy required for the work machine 100 to tip over, for each side of the support rectangle R of the work machine 100 (step S4).

[0071] The normalization unit 215 obtains a dimensionless normalization margin by dividing the height Q calculated in step S4 by the length of another side perpendicular to the side related to the rotation axis (step S5). The evaluation unit 216 compares the normalization margin of each side calculated in step S5 with the attention threshold th c and warning threshold th w (Step S6).

[0072] The output unit 217 determines the angle of the icon I1 of the running object 110 indicating the risk of tipping over based on the measurement value of the turning angle sensor 102 acquired in step S1 (step S7). The output unit 216 also determines the color of each indicator mark I3 based on the comparison result of step S6 (step S8). Specifically, the colors of the indicator mark I3 facing the side that serves as the rotation axis and the indicator marks I3 on ​​both sides of it are determined to be colors according to the comparison result of the normalized margin related to the rotation axis.

[0073] The output unit 217 outputs a display instruction for the generated fall risk sign to the warning device (step S9). Furthermore, the output unit 217 determines whether the normalized margin for at least one rotation axis is equal to or greater than the warning threshold th based on the comparison result of step S6. w The output unit 217 determines whether the normalized margin for at least one rotation axis is below the warning threshold th for a certain period of time or more (step S10). w If the temperature drops below this value for a certain period of time or more (step S10: YES), an instruction to issue an alarm sound is output to the alarm device (step S11).

[0074] Actions and Effects In this way, the control device 190 according to the first embodiment evaluates the possibility of tipping over of the work machine 100 for each side of the support rectangle R represented by the convex hull related to the ground contact point of the work machine 100, based on the energy stability margin of the work machine 100 when that side serves as the axis of rotation, and the length of the side of the support rectangle R. This allows the control device 190 to evaluate the possibility of tipping over for each tipping direction in which tipping may occur during a swing operation.

[0075] In addition, the control device 190 according to other embodiments can evaluate the possibility of tipping over in the same manner as the first embodiment, even when the convex hull relating to the ground contact point of the work machine 100 is not rectangular, by using the longest distance from the axis of rotation to the multiple vertices of the convex hull.

[0076] Furthermore, the control device 190 according to the first embodiment calculates the normalized margin by dividing the energy stability margin by the length of the side of the support rectangle R. This allows the control device 190 to evaluate the possibility of tipping over for each side using the same threshold (caution threshold, warning threshold). Because the normalized margin is a dimensionless quantity, the control device 190 can perform evaluation using the same threshold regardless of individual differences between work machines 100. Note that the control device 190 according to other embodiments may evaluate the unnormalized energy stability margin by using a threshold multiplied by the length of the side of the support rectangle R.

[0077] Second Embodiment 7 is a schematic block diagram showing the configuration of a control device 190 according to the second embodiment. The control device 190 according to the second embodiment includes a limiting unit 218 instead of the output unit 217 of the first embodiment. Furthermore, the evaluation unit 216 according to the second embodiment does not need to generate an indication of the risk of falling.

[0078] The limiting unit 218 limits the operations of the traveling unit 110, the revolving unit 130, and the work machine 150 based on the evaluation result of the evaluating unit 216. For example, the limiting unit 218 limits the operations of the traveling unit 110, the revolving unit 130, and the work machine 150 based on the evaluation result of the evaluating unit 216. wIf the load drops below this value, the control device 190 stops the traveling unit 110, the rotating unit 130, and the work machine 150. This allows the control device 190 to reduce the possibility of the work machine 100 tipping over due to its operation.

[0079] Note that the limiting unit 218 according to other embodiments may limit the operation of the running body 110, the revolving body 130, and the work machine 150 by reducing their operating speeds instead of stopping them. Furthermore, the limiting unit 218 according to other embodiments may limit the operation of any one or two of the running body 110, the revolving body 130, and the work machine 150. In this case, when the normalized margin becomes equal to or greater than the warning threshold value thw by changing the posture so as to reduce the possibility of the work machine 100 tipping over by operating the movable parts that are not restricted, the limiting unit 218 releases the restriction on the operation.

[0080] Other Embodiments Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design modifications are possible. That is, in other embodiments, the order of the above-described processes may be changed as appropriate. Furthermore, some processes may be executed in parallel.

[0081] The control device 190 according to the embodiment described above may be configured by a single computer, or the configuration of the control device 190 may be divided among multiple computers that cooperate with each other to function as the control device 190. In this case, some of the computers that make up the control device 190 may be mounted inside the work machine 100, and other computers may be provided outside the work machine 100.

[0082] The work machine 100 according to the embodiment described above is equipped with a speaker and a display device as an alarm device, but in other embodiments, this is not limited to this and the work machine may have only one of a speaker and a display device. Furthermore, the alarm device is not limited to a speaker and a display device. For example, an alarm device according to other embodiments may be an actuator provided in the control device. The actuator may warn the operator by applying a reaction force to the operation of the control device by the operator. Furthermore, the actuator may warn the operator by generating vibrations in the control device.

[0083] The work machine 100 according to the embodiment described above is a hydraulic excavator, but is not limited to this. For example, the work machine 100 according to other embodiments may be a wheel loader or the like that is equipped with tires instead of tracks. Furthermore, the work machine 100 according to other embodiments may not have a traveling function. Furthermore, in other embodiments, the support polygon does not have to be rectangular. Furthermore, the work machine 100 according to other embodiments may be equipped with other attachments such as a grappler, breaker, or crusher instead of the bucket 153. [Explanation of symbols]

[0084] 100... Work machine 101... Tilt detector 102... Swing angle sensor 103... Boom angle sensor 104... Arm angle sensor 105... Bucket angle sensor 106... Payload meter 110... Traveling body 130... Swinging body 150... Work machine 151... Boom 152... Arm 153... Bucket 170... Operator's cab 190... Control device 210... Processor 211... Acquisition unit 212... Position identification unit 213... Center of gravity calculation unit 214... Energy calculation unit 215... Normalization unit 216... Evaluation unit 217... Output unit 218... Swing limit unit 230... Main memory 250... Storage 270... Interface

Claims

1. A tipping evaluation system for a work machine having a work implement, a processor; The processor: an energy calculation unit that calculates, for each of a plurality of sides of a support polygon of the work machine, the amount of energy required for the work machine to overturn when the side serves as an axis of rotation; an evaluation unit that evaluates the possibility of the work machine tipping over based on the calculated amount of energy for each of the sides; A fall assessment system comprising:

2. The processor further includes a center of gravity position calculation unit that calculates the center of gravity position of the work machine, The energy calculation unit calculates the amount of energy required to cause the work machine to overturn based on the position of the center of gravity of the work machine. The fall assessment system according to claim 1 .

3. The evaluation unit evaluates the possibility of tipping over of the work machine based on the longest distance from the side of the support polygon represented by a convex hull related to the ground contact point to a plurality of vertices of the convex hull. The fall evaluation system according to claim 1 or 2.

4. the support polygon is rectangular; The evaluation unit evaluates the possibility of the work machine tipping over based on the amount of energy of each of the sides and the length of the side perpendicular to the side. The fall evaluation system according to any one of claims 1 to 3.

5. The evaluation unit evaluates the possibility of the work machine tipping over by comparing a normalized value obtained by dividing the amount of energy for each of the edges of the support polygon represented by a convex hull related to the ground contact point by the longest distance from the edge to a plurality of vertices of the convex hull with a threshold. The fall evaluation system according to any one of claims 1 to 4.

6. a display device; The processor further comprises an output unit; The output unit generates an indication indicating the risk of tipping over of the work machine based on the evaluation result of the possibility of tipping over by the evaluation unit, and outputs the indication to the display device. The fall evaluation system according to any one of claims 1 to 5.

7. The markings include an icon representing the appearance of the work machine and a plurality of indicator marks provided so as to surround the icon, The output unit differentiates the state of one of the plurality of indicator marks that is provided at a position corresponding to a side determined by the evaluation unit to have a high possibility of the work machine tipping over from the state of the other indicator marks. The fall assessment system according to claim 6 .

8. The processor: a limiting unit that limits the operation of the work machine when the result of the tipping possibility assessment indicates that there is a high possibility of tipping. The fall evaluation system according to claim 1 , comprising:

9. a step of calculating, for each of a plurality of sides of a support polygon of a work machine having a work implement, the amount of energy required for the work machine to overturn when the side serves as an axis of rotation; assessing the possibility of overturning of the work machine based on the calculated amount of energy for each of the edges; A fall assessment method comprising:

10. A work machine, A running body, a rotating body rotatably supported on the traveling body; a work machine attached to the rotating body; a processor; wherein the processor: a center of gravity position calculation unit that calculates the center of gravity position of the work machine; an energy calculation unit that calculates, for each of a plurality of sides of the support polygon of the traveling body, the amount of energy required for the work machine to overturn when the side serves as an axis of rotation based on the position of the center of gravity of the work machine; an evaluation unit that evaluates the possibility of the work machine tipping over based on the calculated amount of energy for each of the sides; A work machine comprising:

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