Footstand monitoring device, footstand, and footstand monitoring system

Abstract

To provide a stepladder monitoring device and the like that are capable of highly accurately grasping that a user is in an unsafe state and suppressing the occurrence of the fall or the like of a stepladder by measuring the acting force of a leg to a grounding part.SOLUTION: A stepladder monitoring device 10 includes a control device 11, and load measuring devices 12a to 12d for measuring loads acting on ground contact portions 25a to 25d of a stepladder 20. The controller 11 determines what stage of rungs of the stepladder 20 the user of the stepladder 20 has his / her feet on from the measurement values of the load measuring devices 12a to 12d, and determines whether the user is in an unsafe state on the basis of a predetermined range corresponding to the rung on which the feet of the user are placed. This configuration allows the control unit 11 to make highly accurate determination corresponding to the stage number on which the user performs work, thereby preventing the stepladder 20 from falling over or other problems.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a step ladder monitoring device, a step ladder, and a step ladder monitoring system. More specifically, the present invention relates to a step ladder monitoring device, a step ladder, and a step ladder monitoring system having a load measuring device for measuring the acting force on the grounding portion of the legs of the step ladder.

Background Art

[0002] Since a step ladder is formed by combining two ladders in a V-shape and can stand on its own, it can be easily used when working in places that are out of reach, and the work efficiency can be improved. On the other hand, because it can be used easily, when it is used without ensuring safety, accidents may occur where the step ladder itself falls during work or the user of the step ladder falls from the step ladder.

[0003] Patent Document 1 discloses a step ladder monitoring device for suppressing the occurrence of these accidents. This step ladder monitoring device includes an angle measuring unit that measures the inclination angle during the use of the step ladder, and when an angle of a predetermined value is measured, it emits a warning sound to ensure safety for those using the step ladder and suppress the occurrence of the step ladder falling and the user of the step ladder falling.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the measurement of the angle by the angle measuring unit detects the inclination angle only when the step ladder is actually inclined. This state where the step ladder is inclined cannot be said to be a state where the work is being carried out safely, and there is a problem that it is practically difficult to suppress the occurrence of the step ladder falling or the like.

[0006] In addition, Patent Document 1 also discloses a configuration in which a pressure gauge side for measuring the ground contact pressure of the legs of a step ladder is provided. In this configuration, the planar center of gravity position is obtained based on the pressure from the pressure gauge side, and a warning is issued when the planar center of gravity position is outside the rectangle formed by the ground contact positions of the legs. However, when the foot is placed on a step at a relatively low position such as the bottom step, the planar center of gravity position immediately appears outside the rectangle, while when the foot is placed on a higher step, the planar center of gravity position does not appear outside the rectangle. That is, when the foot is placed on a step at a relatively safe lower position, a warning is immediately issued, while when the foot is placed on a step at a relatively unsafe higher position, there is a problem that a warning is not easily issued.

[0007] In view of the above circumstances, an object of the present invention is to provide a step ladder monitoring device, a step ladder, and a step ladder monitoring system that can accurately grasp that a user is in an unsafe state by measuring the acting force on the ground contact portion of the leg and suppress the occurrence of tipping over of the step ladder.

Means for Solving the Problems

[0008] The step ladder monitoring device of the first invention has a control device and a load measuring device for measuring the load acting on the ground contact portion of the step ladder, and the control device determines from the measured value by the load measuring device which step of the step ladder the user of the step ladder has placed their foot on At the same time, calculate the position of the center of gravity of the user from the measurement value by the load measuring device, Based on a predetermined range corresponding to the step on which the user's foot is placed, it is determined whether the user is in an unsafe state and determine that the user is in an unsafe state when at least one of the position of the center of gravity or the center of gravity movement speed of the center of gravity is not within a reference range that is the predetermined range This is the gist. The 2 step ladder monitoring device of the invention, in the first invention, the step ladder monitoring device is provided with a warning device for warning the user, and when the control device determines that the user is in an unsafe state, the warning device warns the user. The 3 step ladder of the invention is characterized in that it is equipped with the step ladder monitoring device of the first invention or the second invention This is the gist. No. 4 The step ladder monitoring system of the first invention or the second invention comprises a step ladder monitoring device and a monitoring terminal for transmitting and receiving signals from the control device, and the monitoring terminal is characterized in that it receives a signal indicating whether the user is in an unsafe state.

Advantages of the Invention

[0009] According to the first invention, after the control device determines from the measured value by the load measuring device which step of the step ladder the user of the step ladder has placed their foot on, by determining whether the user is in an unsafe state, the control device can make a highly accurate determination corresponding to the number of steps at which the user is working, and can suppress the occurrence of the step ladder tipping over or the like. Further, it is also possible to use the step ladder equipped with this step ladder monitoring device as training equipment for work safety or the like. Also, The control device calculates the center of gravity point by the user according to the number of steps at which the user is working, and determines that the user is in an unsafe state when this center of gravity point is not within the reference range case Since the center of gravity point can be obtained by relatively simple calculations, the determination can be made in a short time. Also, Adding the center of gravity point movement speed as a parameter for the control device's determination case can more appropriately determine whether the user is in an unsafe state. No. 2 According to the second invention, when the control device determines that the user is in an unsafe state, the warning device alerts the user, so it can be easily determined that the user of the step ladder is in an unsafe state, and the occurrence of the step ladder tipping over or the like can be more effectively suppressed. Further, in the case of an unsafe state, not only the user of the step ladder but also those around can be informed of the state by a warning buzzer or the like. No. 3 According to the third invention, since the step ladder is equipped with the step ladder monitoring device of the first invention or of the second invention it is possible to constantly monitor whether the user is in an unsafe state during the use of the step ladder, and suppress the occurrence of the step ladder tipping over or the like. No.4 According to the invention, since the step ladder monitoring system has a monitoring terminal that transmits and receives signals from the control device, it is possible to grasp the situation of a step ladder located at a position away from the monitoring terminal. For example, even when multiple step ladders are used in a large area inside a building, the usage status of multiple step ladders can be monitored remotely, and the occurrence of a step ladder falling over or the like can be suppressed.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0011] Next, embodiments of the present invention will be described with reference to the drawings. However, the embodiments shown below illustrate a footstool monitoring device, a footstool, and a footstool monitoring system for embodying the technical idea of the present invention, and the present invention is not limited to the following footstool monitoring device, footstool, and footstool monitoring system. Note that the sizes or positional relationships of the members shown in each drawing may be exaggerated for clarity of explanation.

[0012] (Footstool monitoring device 10) FIG. 1 shows a block configuration diagram of a footstool monitoring device 10 according to an embodiment of the present invention, and FIG. 2 shows a perspective view of a footstool 20 on which the footstool monitoring device 10 is mounted. The footstool monitoring device 10 is a device that monitors the state of the footstool 20 being used by a user. The state of the footstool 20 refers to a state in which there is a possibility of unsafe use, such as a risk of the footstool 20 tipping over or the user falling. The footstool monitoring device 10 includes a control device 11 composed of a microcomputer and load measuring devices 12a to 12d for measuring the loads acting on the grounding portions 25a to 25d of the footstool 20. First, the control device 11 determines, from the measurement values obtained by the load measuring devices 12a to 12d, on which step of the footstool 20 the user has placed their foot. Then, based on a predetermined range selected according to the step on which the foot is placed, it is determined whether the user is in an unsafe state.

[0013] The footstool monitoring device 10 according to the present embodiment includes a control device 11 and four load measuring devices 12a to 12d. The solid lines between the control device 11 and the four load measuring devices 12a to 12d in FIG. 1 indicate that these devices are electrically connected. In addition, the footstool monitoring device 10 includes a warning buzzer 14, a warning LED 15, a battery 16, and an environmental measurement unit 17. These devices are electrically connected to the control device 11. In the present embodiment, the control device 11 and these devices are connected by wire, but it is not limited to this. For example, they may be connected wirelessly.

[0014] The footstool monitoring device 10 according to this embodiment has a housing 13. In this embodiment, this housing 13 is installed below the left top plate 24f of the footstool 20. And a control device 11, a warning buzzer 14, a warning LED 15, and a battery 16 are provided inside this housing 13.

[0015] In this embodiment, the control device 11 is a dedicated microcomputer. However, it is not limited to this. The control device 11 periodically acquires measurement values of the load from the load measuring devices 12a to 12d. The control device 11 has a storage device for storing the measurement values of the load. This storage device is preferably a replaceable one such as a micro SD.

[0016] In this embodiment, the warning buzzer 14 emits a warning sound according to a signal from the control device 11. That is, the warning buzzer 14 is one of the warning devices for attracting the attention of the user of the footstool 20 by sound. This warning buzzer 14 can emit a plurality of different warning sounds according to the degree of insecurity of the user's state. Also, in this embodiment, the warning LED 15 displays the degree of insecurity of the user's state according to a signal from the control device 11. The battery 16 is a power source for the control device 11 etc. and is in a replaceable form.

[0017] In this embodiment, the warning LED 15 gives a warning according to a signal from the control device 11. That is, the warning LED 15 is one of the warning devices for attracting the attention of the user of the footstool 20 by display. This warning LED 15 can blink or light up the warning LED 15 according to the degree of insecurity of the user's state. In addition, it is also possible to change its color or display.

[0018] In this embodiment, the load measuring devices 12a to 12d measure the loads acting on the grounding portions 25a to 25d of the step ladder 20. In this embodiment, the load measuring devices 12a to 12d are configured using strain gauges. However, other configurations may be adopted as long as they can measure the loads acting on the grounding portions 25a to 25d. In this embodiment, the grounding portions 25a to 25d are anti-slip members provided at the lower ends of the columns 21a, 21b, 23a, and 23b of the step ladder 20, and strain gauges are incorporated into these anti-slip members.

[0019] In this embodiment, the environmental measurement unit 17 is provided outside the housing 13. In this embodiment, the environmental measurement unit 17 can measure the temperature, humidity, illuminance, noise, and presence or absence of dust in the environment where the step ladder monitoring device 10 is placed.

[0020] (Step ladder 20) The step ladder 20 provided in the step ladder monitoring device 10 according to this embodiment will be described. FIG. 3(A) is a front view of this step ladder 20, FIG. 3(B) is a side view thereof, and FIG. 4 is an enlarged partial cross-sectional view from the front direction near the upper end portion of the step ladder 20. In this document, the depth direction in the plane of FIG. 3(A) is defined as the front-back direction, and the front side is represented as the front. In addition, the depth direction in the plane of FIG. 3(B) is defined as the left-right direction, and the right side toward this figure is represented as the right, and the left side is represented as the left.

[0021] This step ladder 20 is configured by fixing the front ladder 23 and the rear ladder 21 in a chevron shape with a fastening device or the like. The rear ladder 21 has a rear right support column 21a and a rear left support column 21b, and has five rear steps 22a to 22e therebetween. The rear steps 22a to 22e are, from bottom to top, the first rear step 22a, the second rear step 22b, the third rear step 22c, the fourth rear step 22d, and the fifth rear step 22e. The rear ladder 21 also has a rear top plate 22f at the top. Note that although there are five steps 22a to 22e in this step ladder 20, the number is not limited to five. Similarly, the front ladder 23 has a front right support column 23a and a front left support column 23b, and has five front steps 24a to 24e therebetween. The front steps 24a to 24e are, from bottom to top, the first front step 24a, the second front step 24b, the third front step 24c, the fourth front step 24d, and the fifth front step 24e. The front ladder 23 also has a front top plate 24f at the top.

[0022] The housing 13 of the step ladder monitoring device 10 is provided below the front top plate 24f of the step ladder 20. Further, load measuring devices 12a to 12d are respectively provided at the grounding portions 25a to 25d of the step ladder 20. That is, the first load measuring device 12a is provided at the first grounding portion 25a, the second load measuring device 12b is provided at the second grounding portion 25b, the third load measuring device 12c is provided at the third grounding portion 25c, and the fourth load measuring device 12d is provided at the fourth grounding portion 25d. Each of the load measuring devices 12a to 12d is electrically connected to a control device 11 housed in the housing 13 by an electric wire.

[0023] (Step ladder monitoring system 30) FIG. 5 shows a block configuration diagram of a step ladder monitoring system 30 including the step ladder monitoring device 10 according to the present embodiment. The step ladder monitoring system 30 includes the step ladder monitoring device 10 according to the present embodiment and a monitoring terminal 31 that transmits and receives signals from the control device 11 provided in the step ladder monitoring device 10. The monitoring terminal 31 can receive a signal indicating whether the user of the step ladder 20 is in an unsafe state. The monitoring terminal 31 can be at least either the first monitoring terminal 31a or the second monitoring terminal 31b without any problem.

[0024] The footstool monitoring device 10 in FIG. 5 includes the configuration of the footstool monitoring device 10 according to the above embodiment, and has a terminal wireless communication unit 32. This terminal wireless communication unit 32 is electrically connected to the control device 11 and can perform wireless communication with the first monitoring terminal 31a. The first monitoring terminal 31a corresponds to, for example, a smartphone. However, it is not limited thereto, and a tablet PC or a normal PC is also acceptable. This first monitoring terminal 31a can receive a signal indicating whether the user of the footstool 20 equipped with the footstool monitoring device 10 is in an unsafe state, and can receive and analyze the data of the load measuring devices 12a to 12d constituting the footstool monitoring device 10 in real time. In addition, the first monitoring terminal 31a can also perform operation settings of the footstool monitoring device 10.

[0025] In addition, the terminal wireless communication unit 32 can perform wireless communication with other footstool monitoring devices 10a, 10b. For example, this wireless communication is multi-hop wireless communication. Through this multi-hop wireless communication, the footstool monitoring device 10 can perform wireless communication with the second monitoring terminal 31b. The second monitoring terminal 31b corresponds to a normal PC. However, it is not limited thereto, and a smartphone or a tablet PC is also acceptable. This second monitoring terminal 31b can perform wireless communication with a plurality of footstool monitoring devices 10, 10a, 10b, and can receive signals indicating whether the users of the respective footstools 20 are in an unsafe state from these plurality of footstool monitoring devices 10, 10a, 10b. Also, the second monitoring terminal 31b can be connected to the Internet line via an LTE router 33 that constitutes a LAN or WiFi network.

[0026] (Method for calculating the position of the center of gravity point G, the center of gravity point movement speed GV, and its scalar quantity GVs) FIG. 6 shows an explanatory diagram of the calculation of the position of the center of gravity point G and the like in the step ladder monitoring device 10. FIG. 6 is a plan view of the grounding portions 25a to 25d of the step ladder 20 as viewed from above. Here, the “center of gravity point G” refers to the position of the apparent center of gravity of the user of the step ladder 20 calculated based on the measurement values by the load measuring devices 12a to 12d in the plan view. The following calculation method shows an example of the method for calculating the position of the center of gravity point G, and the calculation of the position of the center of gravity point G is not limited to this method. However, the position of the center of gravity point G needs to be calculated using the measurement values of the load measuring devices 12a to 12d and is used to determine whether the user of the step ladder 20 is in an unsafe state.

[0027] FIG. 6 shows the four grounding portions 25a to 25d and the positions of the load measuring devices 12a to 12d respectively provided on these grounding portions 25a to 25d. The rear rung 21 is located on the upper side of the paper surface of FIG. 6, and the front rung 23 is located on the lower side. Therefore, the user of the step ladder 20 gets on and off the step ladder 20 from the upper side or the lower side of the paper surface of FIG. 6. In FIG. 6, the quadrilateral formed by the four grounding portions 25a to 25b is a square, but it is not limited to this.

[0028] First, as shown by the arrow represented by the solid line in the upper part of the paper surface of FIG. 6, the X-axis and the Y-axis are defined. That is, in the present embodiment, the axis passing through the diagonally located second grounding portion 25b and third grounding portion 25c is defined as the X-axis, and the axis passing through the first grounding portion 25a and fourth grounding portion 25d is defined as the Y-axis. And the intersection of this X-axis and Y-axis is set to 0. And when the measurement value of the first load measuring device 12a at a certain time is Y2, the measurement value of the second load measuring device 12b is X1, the measurement value of the third load measuring device 12c is X2, and the measurement value of the fourth load measuring device 12d is Y1, the position of the center of gravity point G (BX, BY) in this case is defined as follows.

[0029] [Equation 1] BX = (X2 - X1) / (X1 + X2 + Y1 + Y2)

[0030] [Equation 2] BY = (Y2 - Y1) / (X1 + X2 + Y1 + Y2)

[0031] X1: Measurement value by the second load measuring device 12b X2: Measurement value by the third load measuring device 12c Y1: Measurement value by the fourth load measuring device 12d Y2: Measurement value by the first load measuring device 12a

[0032] Next, the center of gravity point movement speed GV is obtained as follows. That is, the center of gravity point movement speed GV is defined by the movement distance of the center of gravity point G with respect to a predetermined time length. FIG. 6 shows a state where the position of the center of gravity point G moves from G1 to G9 between time t = 1 and t = 9. For example, when the center of gravity point G8 moves to the center of gravity point G9 from t = 8 to t = 9, the vector drawn from the center of gravity point G8 to the center of gravity point G9 is the center of gravity point movement speed GV, and the scalar amount GVs thereof is defined by Equation 3 below.

[0033] [Equation 3] GVs = ((BX t+1 - BX t ) 2 +(BY t+1 - BY t ) 2 ) 1 / 2

[0034] BX t+1 : Value of BX at time t + 1 BX t : Value of BX at time t BY t+1 : Value of BY at time t + 1 BY t : Value of BY at time t

[0035] Based on at least one of the position of the center of gravity point G, the center of gravity point movement speed GV, or the scalar amount GVs of the center of gravity point movement speed GV calculated according to the above definition, the control device 11 determines whether the user of the footstool 20 is in an unsafe state.

[0036] (Method for determining the stepping height and the reference range R at the stepping height) In the footstool monitoring device 10 according to the present embodiment, the control device 11 determines, from the measurement values obtained by the load measuring devices 12a to 12d, on which step of the footstool 20 the user of the footstool 20 has placed their foot (hereinafter, the height of the step on which this foot is placed is referred to as the "step height").

[0037] Here, let the step height coefficient used to determine the step height be F. In the present embodiment, this F is defined by the following Equation (4).

[0038] [Equation (4)] F = │(X1 + Y2 - Y1 - X2)│ / (X1 + X2 + Y1 + Y2)

[0039] The numerical value represented by this F is expressed as a linear function with the numerical value representing which step of the step height. Therefore, by calculating F, the control device 11 can determine the step height, that is, on which step of the footstool 20 the user of the footstool 20 has placed their foot. Note that since the value of F varies, when F is within a predetermined range, the control device 11 determines the step height in that case. Also, there may be a case where the user of the footstool 20 places one foot on a certain step of the footstool 20 and the other foot one step above or one step below that step. In this case, since the load of the user mainly acts on the foot in the lower position, the control device 11 determines that the step on which the foot in the lower position of both feet or one foot of the user is placed is the step height. Note that when one foot is placed on the first step from the bottom and the other is on the ground, almost no load is applied to the first step from the bottom. In this case, the control device 11 determines that no user is on the footstool.

[0040] The control device 11 stores a reference range R corresponding to the pre-stepping height in the storage device. This reference range R is at least for the above-mentioned center of gravity point G. The storage device also stores a range of a pre-determined center of gravity movement speed GV or its scalar quantity GVs corresponding to the pre-stepping height. For example, FIG. 6 shows the reference range R for the center of gravity point G. In this case, the reference range R is circular. After determining the stepping height, the control device 11 uses the corresponding reference range R to determine whether the user of the step ladder 20 is in an unsafe state. The range of this reference range R becomes smaller as the stepping height increases.

[0041] (First operation flow) FIG. 7 shows the first operation flow diagram of the step ladder monitoring device 10 according to the present embodiment. Note that only the main operations are described in the operation flow diagram, and other operations are omitted. In the following description, descriptions such as step 001 are described in the form of S001.

[0042] In S001, the control device 11 of the step ladder monitoring device 10 measures the loads acting on the grounding parts 25a to 25d by the four load measuring devices 12a to 12d. The control device 11 can calculate the load by the user of the step ladder 20 by subtracting the weight of the step ladder 20 itself stored in the storage device of the control device 11 from each value of the load measuring devices 12a to 12d.

[0043] In S002, when the load calculated from the four load measuring devices 12a to 12d is equal to or less than a pre-determined load, the control device 11 determines that the user has not yet applied a load to the first pre-stepping 24a, etc., and stores the current values of the load measuring devices 12a to 12d in the storage device in the control device 11 as the weight of the step ladder 20 itself. Then, in the next control cycle, it subtracts the weight of the step ladder 20 newly stored in the storage device from the values of the load measuring devices 12a to 12d in S001.

[0044] In S003, the control device 11 determines the stepping height. "Determining the stepping height" means judging which step of the step ladder 20 the user of the step ladder 20 has placed their foot on. This determination of the stepping height can be made in various ways. For example, it can be determined by the method of determining the stepping height shown in this specification.

[0045] In S004, the control device 11 calculates the position of the center of gravity point G. Here, the "center of gravity point G" refers to the apparent center of gravity of the user of the step ladder 20 calculated based on the measurement values by the load measuring devices 12a to 12d in the plan view. However, the position of the center of gravity point G is calculated using the measurement values of the load measuring devices 12a to 12d and is necessary to be used to determine whether the user of the step ladder 20 is in an unsafe state. There are various methods for calculating the position of the center of gravity point G. For example, it can be calculated by the method of calculating the position of the center of gravity point G shown in this specification.

[0046] In S005, the control device 11 determines whether the calculated position of the center of gravity point G is within the reference range R. This reference range R corresponds to each determined stepping height in S003 and has already been stored in the storage device within the control device 11. The control device 11 selects the reference range R corresponding to each stepping height. In this embodiment, this reference range R is represented as a circle centered on the intersection of the X-axis and the Y-axis as shown in FIG. 6, for example, but is not particularly limited thereto. For example, it may be in an elliptical shape. When the position of the center of gravity point G is not within the reference range R, for example, outside the reference range R, the control device 11 emits a warning sound by the warning buzzer 14 or displays a warning on the warning LED 15. If the position of the center of gravity point G is within the reference range R, the control device 11 proceeds to S006 and continues the cycle without giving a warning.

[0047] After the control device 11 determines from the measurement values by the load measuring devices 12a to 12d which step of the stepladder 20 the user of the stepladder 20 has placed their foot on, by determining whether the user is in an unsafe state, the control device 11 can make a highly accurate determination according to the number of steps at which the user is working, and can suppress the occurrence of the stepladder 20 tipping over or the like. Also, it is possible to use the stepladder 20 equipped with the stepladder monitoring device 10 of the present embodiment as training equipment for work safety or the like.

[0048] When the control device 11 calculates the center of gravity point G by the user and determines that the case where this center of gravity point G is not within the reference range R means that the user is in an unsafe state, since the center of gravity point G can be obtained by relatively simple calculations, the determination can be made in a short time.

[0049] When the control device 11 determines that the user is in an unsafe state, by alerting the user by means of an alert device, it can be easily determined that the user of the stepladder 20 is in an unsafe state, and the occurrence of the stepladder 20 tipping over or the like can be suppressed more effectively. Also, in the case of an unsafe state, not only the user of the stepladder 20 but also those around can be informed of the state by means of a warning buzzer 14 or the like.

[0050] In addition, in S005, the control device 11 may issue a warning even when the position of the center of gravity point G is not within the reference range R, for example, when it is further inside the reference range R. For example, when the reference range R is the area between two concentric circles with the same center, and the position of the center of gravity point G is further inside the inner concentric circle, the control device 11 determines that the position of the center of gravity point G is not within the reference range R and issues a warning. Note that when the position of the center of gravity point G is further inside the inner concentric circle, it corresponds to the case where the user of the step ladder 20 is on the top plates 22f and 24f, or the case where the user of the step ladder 20 places feet on both the rear ladder 21 and the front ladder 23 across the top plates 22f and 24f. The actions of the user getting on the top plates 22f and 24f, or placing feet on both the rear ladder 21 and the front ladder 23 and straddling are prohibited as dangerous actions in use, and in such cases, it can be determined that the user is in an unsafe state.

[0051] (Second operation flow) FIG. 8 shows a second operation flow diagram of the step ladder monitoring device 10 according to the present embodiment. Since S101 to S103 of the second flow are the same as S001 to S003 of the first flow, the description thereof is omitted.

[0052] In S104, the control device 11 calculates the scalar amount GVs of the center of gravity point moving speed GV. The center of gravity point moving speed GV is defined by the moving distance of the center of gravity point G at a predetermined time. However, the center of gravity point moving speed GV needs to be calculated using the measured values of the load measuring devices 12a to 12d and is used to determine whether the user of the step ladder 20 is in an unsafe state. There are various methods for calculating the center of gravity point moving speed GV. For example, the center of gravity point moving speed GV is calculated by the method for calculating the scalar amount GVs of the center of gravity point moving speed GV shown in this specification. Also, the scalar amount GVs is calculated from this center of gravity point moving speed GV.

[0053] In S105, the control device 11 determines whether the scalar amount GVs of the calculated center-of-gravity point movement speed GV is within a predefined range. This range corresponds to each depression height determined in S103 and is already stored in the storage device within the control device 11. The control device 11 selects the range corresponding to each depression height. When the scalar amount GVs is not within the predefined range, for example, when it is a value larger than that range, the control device 11 emits a warning sound through the warning buzzer 14 or displays a warning on the warning LED 15. If the position of the center of gravity G is within the reference range R, the control device 11 proceeds to S106 and continues the control cycle without issuing a warning.

[0054] By making a determination based on the center-of-gravity point movement speed GV, the control device 11 has more parameters for making a determination, so it can more appropriately determine whether the user is in an unsafe state.

[0055] (Third operation flow) FIG. 9 shows a third operation flow diagram of the step ladder monitoring device 10 according to the present embodiment. Since S201 to S203 of the third flow are the same as S001 to S003 of the first flow, the description thereof is omitted.

[0056] In S204, the control device 11 calculates the position of the center of gravity G and the scalar amount GVs of the center-of-gravity point movement speed GV. The position of the center of gravity G and the scalar amount GVs of the center-of-gravity point movement speed GV are the same as those described in the first flow and the second flow.

[0057] In S205, the control device 11 determines whether the position of the calculated center of gravity point G is within the reference range R and whether the scalar amount GVs of the center of gravity point movement speed GV is within a predetermined range. That is, the control device 11 uses these two parameters to determine whether to issue a warning. For example, when the position of the center of gravity point G is outside the reference range R, the control device 11 emits a warning sound of 3500 Hz from the warning buzzer 14 once. In addition, when the scalar amount GVs of the center of gravity point movement speed GV exceeds a predetermined range, the control device 11 emits a warning sound of 2450 Hz from the warning buzzer 14 twice. Furthermore, when the position of the center of gravity point G is inside the reference range R, the control device 11 emits a warning sound of 3000 Hz from the warning buzzer 14 three times. Note that the way of issuing a warning is not limited to this method. When the position of the center of gravity point G is within the reference range R and the scalar amount GVs of the center of gravity point movement speed GV is within a predetermined range, the control device 11 continues the control cycle without issuing a warning.

[0058] (Others) In the second and third flows, the control device 11 determines whether the user is in an unsafe state using the scalar amount GVs of the center of gravity point movement speed GV, but it is also possible to make a determination using the center of gravity point movement speed GV.

Industrial Applicability

[0059] In this article, as an embodiment, the step ladder monitoring device 10 has been described using a combined step ladder that can also be used as a ladder, but the step ladder monitoring device 10 of the present application can also be used for a dedicated step ladder, a scaffolding step ladder, and a tripod step ladder. In the case of a tripod step ladder or the like, the number of load measuring devices 12 used for calculating the center of gravity point G is three.

Explanation of Signs

[0060] 10 Step ladder monitoring device 11 Control device 12 Load measuring device 20 Step ladder 30 Step ladder monitoring system G Center of gravity point GV Center of gravity point movement speed Scalar quantity of the moving speed of the center of gravity of GVs R reference range

Claims

1. A control device, a load measuring device for measuring a load acting on the grounding part of the step ladder, and the control device judges from the measured value by the load measuring device where the user of the step ladder has placed their foot on which step of the step ladder, and calculates the position of the center of gravity by the user from the measured value by the load measuring device, judges whether the user is in an unsafe state based on a predetermined range corresponding to the step on which the user's foot is placed, and judges that the user is in an unsafe state when at least one of the position of the center of gravity or the center of gravity movement speed of the center of gravity is not within a reference range which is the predetermined range. A step ladder monitoring device characterized by the above.

2. The step ladder monitoring device is provided with a warning device for warning the user, and when the control device judges that the user is in an unsafe state, it warns the user by the warning device. The step ladder monitoring device according to Claim 1, characterized by the above.

3. A step ladder characterized by being equipped with the step ladder monitoring device according to Claim 1 or 2.

4. A step ladder monitoring system comprising the step ladder monitoring device according to Claim 1 or 2, and a monitoring terminal for transmitting and receiving signals from the control device, where the monitoring terminal receives a signal indicating whether the user is in an unsafe state. ​ ​

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