Load measurement device and load measurement method

Abstract

To provide a load measurement device and a load measurement method that can improve measurement accuracy of loading capacity of a vehicle.SOLUTION: A load measurement device 10 comprises a load sensor 100 for measuring and outputting a strain of a rear axle 3, and a load calculation unit 201 for calculating a load acting on the rear axle 3 from an output value of the load sensor 100 using conversion information for converting the output value of the load sensor 100 into the load acting on the rear axle 3. The load calculation unit 201 determines the conversion information based on a reference value that is the output value of the load sensor 100 when dual tires 2 are in a horizontal state, a load converted from the reference value using the conversion information, and the output value of the load sensor 100 in a state in which the load acts on the rear axle 3, and calculates the load acting on the rear axle 3 from the output value of the load sensor 100 using the determined conversion information.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a live load measuring device and a live load measuring method. [Background technology]

[0002] A known live load measuring device has a strain gauge attached to an axle shaft via a base plate (see, for example, Patent Document 1). In the live load measuring device described in Patent Document 1, the strain gauge detects the strain of the axle shaft caused by the live load and outputs a detection signal. The detection signal output from the strain gauge is amplified by an amplifier and calculated by a controller to calculate the live load of the vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-71437 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the case of a vehicle with dual tires, if one side of the dual tires is lifted off the ground due to unevenness in the road surface, the point of force of the load acting on the axle shaft from the road surface changes. This changes the magnitude of the bending moment acting on the axle shaft, causing a change in distortion of the axle shaft. In the live load measuring device described in Patent Document 1, the change in distortion of the axle shaft caused by the inclination of dual tires or wide tires affects the measurement accuracy of the live load of the vehicle.

[0005] In view of the above circumstances, an object of the present invention is to provide a live load measuring device and a live load measuring method that can improve the measurement accuracy of the live load of a vehicle. [Means for solving the problem]

[0006] The live load measuring device of the present invention comprises a strain measuring unit that measures and outputs a strain of an axle, and a load calculation unit that calculates the load acting on the axle from the output value of the strain measuring unit using conversion information for converting the output value of the strain measuring unit into a load acting on the axle, the load calculation unit performing a first process of acquiring and storing a first output value that is an output value of the strain measuring unit when a tire attached to the axle is in a horizontal state and a first load that is a load converted from the first output value, a second process of acquiring, after the first process, a second output value that is an output value of the strain measuring unit in a state in which the first load is acting on the axle, and if, after the second process, the second output value is between a first threshold value that is less than or equal to the first output value and a second threshold value that is greater than or equal to the first output value, A third process is executed to determine the conversion information to be first conversion information, and if the second output value is equal to or less than the first threshold, to determine the conversion information to be second conversion information, and if the second output value is equal to or greater than the second threshold, to determine the conversion information to be third conversion information; and a fourth process is executed to calculate a second load acting on the axle from the third output value of the strain measuring unit using the conversion information determined in the third process, wherein the first conversion information includes a first gain that amplifies the output value of the strain measuring unit, the second conversion information includes a second gain that amplifies the output value of the strain measuring unit, and the third conversion information includes a third gain that amplifies the output value of the strain measuring unit, the second gain is greater than the first gain, and the third gain is smaller than the first gain.

[0007] The live load measuring method of the present invention is a method for measuring a live load using a strain measuring unit that measures and outputs a strain of an axle, and a computer that calculates the load acting on the axle from the output value of the strain measuring unit using conversion information for converting the output value of the strain measuring unit into a load acting on the axle, the method including a first step of acquiring and storing a first output value that is the output value of the strain measuring unit when the tire attached to the axle is horizontal and a first load that is the load converted from the first output value, a second step of acquiring, after the first step, a second output value that is the output value of the strain measuring unit when the first load is acting on the axle, and after the second step, storing the second output value between a first threshold value that is less than or equal to the first output value and a second threshold value that is greater than or equal to the first output value. In a certain case, a third step is executed of determining the conversion information to be first conversion information, and if the second output value is equal to or less than the first threshold, determining the conversion information to be second conversion information, and if the second output value is equal to or greater than the second threshold, determining the conversion information to be third conversion information; and a fourth step is executed of calculating a second load acting on the axle from a third output value of the strain measuring unit using the conversion information determined in the third step, wherein the first conversion information includes a first gain that amplifies the output value of the strain measuring unit, the second conversion information includes a second gain that amplifies the output value of the strain measuring unit, and the third conversion information includes a third gain that amplifies the output value of the strain measuring unit, the second gain is greater than the first gain, and the third gain is smaller than the first gain. Effect of the Invention

[0008] According to the present invention, the measurement accuracy of the load of a vehicle can be improved. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the configuration of a live load measuring device according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing the relationship between the force point, fulcrum, and point of action of a rear axle to which dual tires are attached. [Diagram 3] FIG. 3 is a diagram showing the relationship between the fulcrum, the force point, and the point of action when the tire on the inner side in the vehicle width direction runs over a bump on the road surface. [Figure 4] FIG. 4 is a diagram showing the relationship between the fulcrum, the force point, and the point of action when the tire on the outer side in the vehicle width direction runs over a bump on the road surface. [Diagram 5] FIG. 5 is a graph showing the relationship between the unevenness of the road surface under the dual tires, the output value of the load sensor, and the calculated value of the load. [Figure 6] FIG. 6 is a graph for explaining a method of converting the output value of the load sensor into a load when the tire on the inner side in the vehicle width direction runs over a bump on the road surface. [Figure 7] FIG. 7 is a graph for explaining a method of converting the output value of the load sensor into a load when the tire on the outer side in the vehicle width direction runs over a bump on the road surface. [Figure 8] FIG. 8 is a flowchart showing a process for measuring the load of a vehicle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described below along with preferred embodiments. Note that the present invention is not limited to the embodiments shown below, and the embodiments shown below can be modified as appropriate within the scope of the present invention. In addition, in the embodiments shown below, some configurations are omitted from illustration and description, but for the details of the omitted technologies, publicly known or well-known technologies are applied as appropriate within the scope of no contradiction with the contents described below.

[0011] Fig. 1 is a diagram showing the configuration of a live load measurement device 10 according to one embodiment of the present invention. A vehicle 1 on which the live load measurement device 10 shown in this figure is mounted is a truck, a lorry, or the like in which a live load acts on a rear axle 3 and a front axle (not shown), and dual tires 2 are attached to the rear axle 3.

[0012] The live load measuring device 10 includes a plurality of load sensors 100 and an in-vehicle device 200. The number of the load sensors 100 installed is twice the number of axles of the vehicle 1. In this embodiment, since the vehicle 1 has two axles, four load sensors 100 are provided. Two load sensors 100 are attached to the front axle, and two load sensors 100 are attached to the rear axle 3. Each load sensor 100 is a strain gauge, and detects the amount of strain of the front axle or the rear axle 3 as a voltage and transmits a voltage signal to the in-vehicle device 200.

[0013] The vehicle-mounted device 200 is a display device that displays the live load of the vehicle 1, and includes a load calculation unit 201 that calculates the live load of the vehicle 1 based on the voltage signals transmitted from each load sensor 100, and a display unit 202 that displays the calculated live load of the vehicle 1. The vehicle-mounted device 200 stores load / voltage conversion information such as a formula, table, map, etc. for converting the voltage values ​​transmitted from each load sensor 100 into loads. The vehicle-mounted device 200 also calculates the live load of the vehicle 1 by adding up the calculated loads for each load sensor 100.

[0014] 2 is a diagram showing the relationship between the force point, fulcrum, and point of action of the rear axle 3 to which the dual tires 2 are attached. As shown in this figure, the dual tires 2 include a tire 2A on the inside in the vehicle width direction and a tire 2B on the outside in the vehicle width direction. In the dual tires 2, the tires 2A and 2B are arranged side by side, and a wheel center 2C is provided between the tires 2A and 2B.

[0015] The position of the load sensor 100 serves as the point of application. In addition, both axial ends of the rear axle 3 serve as points of application of force from the dual tires 2. In addition, a leaf spring 5 is attached to the rear axle 3 between the wheel center 2C and the differential gear 4. The attachment position of the leaf spring 5 on the rear axle 3 serves as a fulcrum that supports the load applied to the rear axle 3. The load sensor 100 is disposed between the fulcrum and the point of application of force on the rear axle 3.

[0016] Here, when the dual tires 2 are positioned on a horizontal road surface and the tires 2A, 2B are horizontal, the point of force is located at the wheel center 2C, but if the road surface underneath the dual tires 2 is uneven, the point of force will shift to the tire 2A side or the tire 2B side.

[0017] 3 is a diagram showing the relationship between the fulcrum, the force point, and the point of action when the tire 2A on the inner side in the vehicle width direction runs over a bump on the road surface. As shown in this diagram, when the tire 2A on the inner side in the vehicle width direction runs over a bump on the road surface, the force point is displaced inward in the vehicle width direction, and the angle θ between the dual tires 2 and the rear axle 3 narrows. As a result, the amount of distortion of the rear axle 3 is smaller than when the dual tires 2 are located on a level road surface, and the output value of the load sensor 100 is smaller.

[0018] 4 is a diagram showing the relationship between the fulcrum, the force point, and the point of action when the tire 2B on the outer side in the vehicle width direction runs over a bump on the road surface. As shown in this figure, when the tire 2B on the outer side in the vehicle width direction runs over a bump on the road surface, the force point is displaced outward in the vehicle width direction, and the angle θ between the dual tires 2 and the rear axle 3 increases. As a result, the amount of distortion of the rear axle 3 increases compared to when the dual tires 2 are located on a horizontal road surface, and the output value of the load sensor 100 increases.

[0019] 5 is a graph showing the relationship between the unevenness of the road surface under the double tires 2, the output value of the load sensor 100, and the calculated value of the load. As shown in this graph, when the tire 2A on the inside in the vehicle width direction runs over a bump in the road surface, the output value of the load sensor 100 is offset in a direction to become smaller compared to when the road surface under the double tires 2 is horizontal. Therefore, if the output value of the load sensor 100 is converted into a load using the same conversion information as when the road surface under the double tires 2 is horizontal, an error will occur in the calculated value of the load such that the calculated value of the load will be smaller than the actual weight.

[0020] On the other hand, when the tire 2B on the outer side in the vehicle width direction runs over a bump on the road surface, the output value of the load sensor 100 is offset in the direction to be larger compared to when the road surface under the dual tires 2 is horizontal. Therefore, if the output value of the load sensor 100 is converted into load using the same conversion information as when the road surface under the dual tires 2 is horizontal, an error will occur in the calculated load value such that the calculated load value will be larger than the actual weight.

[0021] For example, assume that the output value of the load sensor 100 when a load of 100 kg is carried is 100 when the twin tires 2 are horizontal, 90 when the tire 2A on the inside in the vehicle width direction is riding on a bump in the road surface, and 120 when the tire 2B on the outside in the vehicle width direction is riding on a bump in the road surface. Under this assumption, a negative error equivalent to -10 occurs when the tire 2A on the inside in the vehicle width direction is riding on a bump in the road surface, and a positive error equivalent to +20 occurs when the tire 2B on the outside in the vehicle width direction is riding on a bump in the road surface.

[0022] Therefore, in the load measuring device 10 of this embodiment, the inclination of the dual tires 2 caused by the tires 2A, 2B riding over a bump on the road surface is detected, and conversion information for converting the output value of the load sensor 100 into a load is determined based on the detected inclination of the dual tires 2.

[0023] Fig. 6 is a graph for explaining a method for converting the output value of the load sensor 100 into a load when the tire 2A on the inner side in the vehicle width direction runs over a bump on the road surface. Fig. 7 is a graph for explaining a method for converting the output value of the load sensor 100 into a load when the tire 2B on the outer side in the vehicle width direction runs over a bump on the road surface. Fig. 6 shows a straight line graph represented by the conversion formulas (1) and (2) below, and a straight line graph of the threshold values ​​α and β represented by the conversion formulas (4) and (5) below. Fig. 7 also shows a straight line graph represented by the conversion formulas (1) and (3) below, and a straight line graph of the threshold values ​​α and β represented by the conversion formulas (4) and (5) below.

[0024] The following conversion formula (1) is a formula for converting the output value of the load sensor 100 when the dual tires 2 are horizontal into a load. The solid line graphs in Figures 6 and 7 show the relationship between the output value of the load sensor 100 and the calculated value of the load when the dual tires 2 are horizontal.

[0025] The following conversion formula (2) is a formula for converting the output value of the load sensor 100 into a load when the tire 2A on the inner side in the vehicle width direction runs over a bump on the road surface. The straight line graph shown by the dashed dotted line in Fig. 6 shows the relationship between the output value of the load sensor 100 and the calculated value of the load when the tire 2A on the inner side in the vehicle width direction runs over a bump on the road surface.

[0026] The following conversion formula (3) is a formula for converting the output value of the load sensor 100 into a load when the tire 2B on the outer side in the vehicle width direction runs over a bump on the road surface. The straight line graph indicated by the two-dot chain line in Fig. 7 shows the relationship between the output value of the load sensor 100 and the calculated value of the load when the tire 2B on the outer side in the vehicle width direction runs over a bump on the road surface.

[0027] The following conversion formula (4) is a formula for converting the output value of the load sensor 100 into a threshold value α for distinguishing between when the dual tires 2 are horizontal and when the tire 2A on the inner side in the vehicle width direction runs over a bump on the road surface. The straight broken line graphs on the left side of Figures 6 and 7 show the relationship between the output value of the load sensor 100 and the threshold value α.

[0028] The following conversion formula (5) is a formula for converting the output value of the load sensor 100 into a threshold value β for distinguishing between when the dual tires 2 are horizontal and when the outer tire 2B in the vehicle width direction runs over a bump on the road surface. The straight dashed line graphs on the right side of Fig. 6 and Fig. 7 show the relationship between the output value of the load sensor 100 and the threshold value β.

[0029] Y = a1 * X + b1 … (1) Y = a2 * X + b2 … (2) Y = a3 * X + b3 … (3) α = a4 * X + b4 … (4) β=a5*X+b5…(5) Y is the calculated value of the load. X is the output value of the load sensor 100. a1, a2, a3, a4, and a5 are the slopes and gains of the conversion equations. b1, b2, b3, b4, and b5 are the intercepts of the conversion equations, and the relationship is b2>b4>b1>b5>b3. Note that b1 is 0.

[0030] Here, a1, a2, a3, a4, and a5 have the relationship a2>a4>a1>a5>a3. That is, the gain a2 when the tire 2A on the inner side in the vehicle width direction runs over a protrusion on the road surface is greater than the gain a1 when the dual tires 2 are horizontal, and the gain a3 when the tire 2B on the outer side in the vehicle width direction runs over a protrusion on the road surface is less than the gain a1 when the dual tires 2 are horizontal. Also, the gain a4 for converting the output value of the load sensor 100 into the threshold value α is greater than the gain a1 and less than the gain a2. Furthermore, the gain a5 for converting the output value of the load sensor 100 into the threshold value β is less than the gain a1 and greater than the gain a3.

[0031] 8 is a flowchart showing a process for measuring the load of the vehicle 1. First, the vehicle 1 loaded with cargo is parked in a predetermined parking space to acquire the reference value A1 of the load sensor 100 and the load L1 (steps S1 and S2). The predetermined parking space is a parking space where the road surface under the dual tires 2 is horizontal.

[0032] When an instruction is input to the vehicle-mounted device 200 by the user (YES in step S1), the load calculation unit 201 of the vehicle-mounted device 200 acquires the output value of the load sensor 100 (A1 in Figs. 6 and 7, hereinafter, reference value A1), converts the reference value A1 to load L1 using the conversion formula (1) above, and stores the reference value A1 and load L1 in memory (step S2). Note that when the load L1 is clear, the load calculation unit 201 of the vehicle-mounted device 200 may accept the input of the load L1 by the user and convert the input load L1 to the reference value A1 using the conversion formula (1) above.

[0033] After that, the vehicle 1 moves to a position where the load L1 is loaded and unloaded. At that time, before loading and unloading the load, a conversion formula is determined according to the state of the road surface under the dual tires 2 (steps S3 to S7). First, when a command is input to the vehicle-mounted device 200 by the user (YES in step S3), the load calculation unit 201 acquires the output value A2 (see Figs. 6 and 7) of the load sensor 100 (step S4). Next, the load calculation unit 201 determines whether the output value A2 satisfies the relationship of threshold value α<output value A2<threshold value β (step S5). The threshold value α is the output value of the load sensor 100 converted from the load L1 by the above formula (4). Moreover, the threshold value β is the output value of the load sensor 100 converted from the load L1 by the above formula (5).

[0034] If the output value A2 satisfies the relationship of threshold value α<output value A2<threshold value β (YES in step S5), the load calculation unit 201 determines the conversion formula to be the conversion formula (1) when the dual tires 2 are horizontal (step S6). On the other hand, if the output value A2 does not satisfy the relationship of threshold value α<output value A2<threshold value β (NO in step S5), the load calculation unit 201 determines whether the output value A2 is smaller than the reference value A1 (step S7).

[0035] If the output value A2 is smaller than the reference value A1 (YES in step S7), the load calculation unit 201 determines the conversion formula to be the conversion formula (2) when the tire 2A on the inside in the vehicle width direction runs over a bump on the road surface (step S8). On the other hand, if the output value A2 is larger than the reference value A1 (NO in step S7), the load calculation unit 201 determines the conversion formula to be the conversion formula (3) when the tire 2B on the outside in the vehicle width direction runs over a bump on the road surface (step S9).

[0036] After that, loading and unloading is started, and the live load is measured by the live load measuring device 10 (steps S10 to S12). First, when a command is input to the vehicle-mounted device 200 by the user (YES in step S10), the load calculation unit 201 acquires the output value A3 of the load sensor 100 (see Figs. 6 and 7), and converts the output value A3 of the load sensor 100 into a load L2 using the conversion formula determined in steps S6, S8, and S9 (step S11).

[0037] Thereafter, the processes of steps S11 and S12 are repeated until the user inputs an instruction to end loading / unloading to the vehicle-mounted device 200 (NO in step S12). On the other hand, when the user inputs an instruction to end loading / unloading to the vehicle-mounted device 200 (YES in step S12), the process ends.

[0038] As described above, in the live load measuring device 10 of this embodiment, the load calculation unit 201 executes the following first to fourth processes when calculating the load acting on the rear axle 3 from the output value of the load sensor 100 using the conversion formulas (1) to (3) above. First, in the first process, the load calculation unit 201 acquires the reference value A1, which is the output value of the load sensor 100 when the dual tires 2 attached to the rear axle 3 are in a horizontal state, and the load L1, which is the load converted from the reference value A1, and stores them in memory. Next, in the second process, the load calculation unit 201 acquires the output value A2 of the load sensor 100 in a state in which the load L1 acts on the rear axle 3. Next, in a third process, the load calculation unit 201 determines the conversion formula to be the conversion formula (1) above if the output value A2 is between the threshold value α (≦reference value A1) and the threshold value β (≧reference value A1), determines the conversion formula to be the conversion formula (2) above if the output value A2 is equal to or less than the threshold value α, and determines the conversion formula to be the conversion formula (3) above if the output value A2 is equal to or more than the threshold value β. Next, in a fourth process, the load calculation unit 201 calculates the load L2 acting on the rear axle 3 from the output value A3 of the load sensor 100 using the conversion formula determined in the third process.

[0039] Here, the conversion formula (1) above includes a gain a1 that amplifies the output value of the load sensor 100, the conversion formula (2) above includes a gain a2 that amplifies the output value of the load sensor 100, and the conversion formula (3) above includes a gain a3 that amplifies the output value of the load sensor 100. The gain a2 is greater than the gain a1, and the gain a3 is smaller than the gain a1.

[0040] As a result, as shown in Fig. 6, when the tire 2A on the inner side in the vehicle width direction runs over a bump on the road surface, the output value A2 smaller than the threshold value α is converted to a load L2 using the conversion formula (2) including gain a2 (> gain a1), and a negative error with respect to the actual load is corrected. Also, as shown in Fig. 7, when the tire 2B on the outer side in the vehicle width direction runs over a bump on the road surface, the output value A3 larger than the threshold value β is converted to a load L3 using the conversion formula (3) including gain a3 (< gain a1), and a positive error with respect to the actual load is corrected. Therefore, the measurement accuracy of the live load of the vehicle 1 can be improved.

[0041] In the live load measuring device 10 of this embodiment, the first process is performed in a space under the double tires 2 where the road surface is horizontal, and the second process is performed at the user's command after the vehicle 1 has moved from the space and under the load L1 before the loading and unloading of the cargo. This makes it possible to compare the output value (reference value A1) when the double tires 2 are horizontal with the output value A2 when one of the double tires 2A, 2B runs over a bump on the road surface under the same load L1, and to determine the presence or absence and direction of the inclination of the double tires 2. After the conversion formula is determined in the third process, the load L3 after the start of loading and unloading of the cargo is calculated using the determined conversion formula, making it possible to measure the load L2 with the error due to the inclination of the double tires 2 corrected.

[0042] The present invention has been described above based on the above embodiment, but the present invention is not limited to the above embodiment, and modifications may be made to the above embodiment without departing from the spirit of the present invention, and publicly known or well-known technologies may be combined as appropriate.

[0043] For example, in the above embodiment, the vehicle 1 has double tires 2 attached to the rear axle 3, but the present invention is not limited to double tires 2 and can also be applied to vehicles with a wide single tire attached to the axle.

[0044] In addition, in the above embodiment, the first to third conversion information are the conversion formulas (1) to (3) above, but the first to third conversion information may be in the form of a map, table, or the like as long as it includes a gain that amplifies the output value of the load sensor 100. [Explanation of symbols]

[0045] 1: Vehicle 2: Double tires (tires) 3: Rear axle (axle) 10: Load measuring device 100: Load sensor (strain measurement part) 200: Car-mounted device (computer) 201: Load calculation section A1: Reference value (first output value) A2: Output value (second output value) a1: Gain (first gain) a2: Gain (second gain) a3: Gain (third gain) L1: Load (first load) L2: Load (second load) α: Threshold (first threshold) β: Threshold (second threshold)

Claims

1. A distortion measuring unit that measures and outputs distortion of the axle; a load calculation unit that calculates a load acting on the axle from an output value of the strain measurement unit using conversion information for converting an output value of the strain measurement unit into a load acting on the axle; Equipped with The load calculation unit is a first process of acquiring and storing a first output value, which is an output value of the strain measuring unit when the tire attached to the axle is in a horizontal state, and a first load, which is a load converted from the first output value; a second process of acquiring a second output value, which is an output value of the strain measuring unit in a state in which the first load acts on the axle after the first process; a third process for determining, after the second process, the conversion information to be first conversion information if the second output value is between a first threshold value equal to or less than the first output value and a second threshold value equal to or more than the first output value, determining the conversion information to be second conversion information if the second output value is equal to or less than the first threshold, and determining the conversion information to be third conversion information if the second output value is equal to or more than the second threshold; a fourth process of calculating a second load acting on the axle from a third output value of the strain measuring unit by using the conversion information determined in the third process; Run the first conversion information includes a first gain for amplifying an output value of the distortion measuring unit, the second conversion information includes a second gain for amplifying an output value of the distortion measuring unit, the third conversion information includes a third gain that amplifies an output value of the distortion measuring unit, The second gain is greater than the first gain, and the third gain is less than the first gain. Load measuring device.

2. The second process is executed after the vehicle has moved from the execution time of the first process and before loading or unloading of the cargo; The fourth process is executed after the start of unloading of the cargo. The load measuring device according to claim 1.

3. The tire is a double tire.

3. The load measuring device according to claim 1 or 2.

4. A method for measuring a live load using a strain measuring unit that measures and outputs a strain of an axle, and a computer that calculates the load acting on the axle from the output value of the strain measuring unit using conversion information for converting the output value of the strain measuring unit into a load acting on the axle, a first step of acquiring and storing a first output value, which is an output value of the strain measuring unit when the tire attached to the axle is in a horizontal state, and a first load, which is a load converted from the first output value; a second step of acquiring a second output value, which is an output value of the strain measuring unit in a state in which the first load acts on the axle, after the first step; a third step of determining, after the second step, that the conversion information is first conversion information when the second output value is between a first threshold value equal to or less than the first output value and a second threshold value equal to or more than the first output value, determining that the conversion information is second conversion information when the second output value is equal to or less than the first threshold, and determining that the conversion information is third conversion information when the second output value is equal to or more than the second threshold; a fourth step of calculating a second load acting on the axle from a third output value of the strain measuring unit using the conversion information determined in the third step; Run the first conversion information includes a first gain for amplifying an output value of the distortion measuring unit, the second conversion information includes a second gain for amplifying an output value of the distortion measuring unit, the third conversion information includes a third gain that amplifies an output value of the distortion measuring unit, The second gain is greater than the first gain, and the third gain is less than the first gain. How to measure live load.

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