JP2014126508A - Vehicle eigen frequency detector and center-of-gravity position measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle eigen frequency detector capable of accurately detecting the eigen frequency of a vehicle, and to provide a center-of-gravity position measurement device capable of accurately measuring the height of the center of gravity of the vehicle using the vehicle eigen frequency detector.SOLUTION: The vehicle eigen frequency detector includes: a plurality of load cells 5, 6, 7, and 8 for detecting a load; a pedestal 3 that is supported by the load cells 5-8 and is mounted with a vehicle 4; a hydraulic cylinder 32 that oscillates the vehicle 4 on the pedestal 3 and stops the oscillation of the pedestal 3 oscillated together with the vehicle 4; and an MPU 40 that calculates the eigen frequency of the vehicle 4 on the basis of load signals of the load cells 5-8 and calculates the height of the center of gravity of the vehicle 4 on the basis of the eigen frequency.

Description

  The present invention relates to a vehicle natural frequency detection device that detects a natural frequency of a vehicle and a center-of-gravity position measurement device using the same.

  Conventionally, as a device for measuring the height of the center of gravity of a vehicle such as a cargo truck or a trailer at a fixed position, there is a center-of-gravity height measuring device proposed in Patent Document 1, for example.

JP 2011-53206 A

  In the center-of-gravity height measuring device according to Patent Document 1, the platform is freely oscillated in the horizontal direction in a state where the vehicle is placed on the platform supported by a plurality of load cells, and the displacement of the platform at this time, Based on the acceleration and the load signal of the load cell, the height of the center of gravity of the vehicle is measured.

  However, in this center-of-gravity height measurement device, the measurement is performed in a state where both the platform and the vehicle are freely vibrated together, so the vibration component of the platform that can be regarded as a rigid body and the equipment such as the suspension However, there is a problem that the vibration component of the vehicle that cannot be regarded as a rigid body is mixed, and the height of the center of gravity of the vehicle cannot be measured with high accuracy.

  Therefore, if the vehicle natural frequency based on the inherent vibration component of the vehicle can be accurately detected excluding the vibration component of the platform, the center of gravity height can be measured with high accuracy based on the vehicle natural frequency. Therefore, the advent of a vehicle natural frequency detection device and a center-of-gravity position measurement device using the same has been desired.

  The present invention has been made in view of the above-described problems and the like, and provides a vehicle natural frequency detection device capable of accurately detecting the natural frequency of the vehicle, and the vehicle natural frequency detection device. An object of the present invention is to provide a center-of-gravity position measuring apparatus that can measure the center of gravity of a vehicle with high accuracy.

In order to achieve the above object, a vehicle natural frequency detection device according to the first invention comprises:
A vehicle natural frequency detection device for detecting a natural frequency of a vehicle,
A plurality of load cells for detecting the load;
A platform that is supported by the load cell and carries a vehicle;
Rocking means for rocking the vehicle on the table,
Anti-sway means for stopping the shaking of the table,
A natural frequency calculating means for calculating a natural frequency of the vehicle based on a load signal from the load cell;
It is characterized by providing.

  In the first invention, the natural frequency calculating means may calculate a vertical frequency of the vehicle based on a load signal from the load cell when the vehicle gets on the table. invention).

  In the first invention or the second invention, the vehicle on the table is rocked in the width direction by the rocking means, and the natural frequency calculating means is prevented from shaking the table by the rocking means. The rolling frequency of the vehicle can be calculated on the basis of the load signal from the load cell in the state where the load cell has been turned on (third invention).

  In the first or second aspect of the invention, the vehicle on the table is rocked in the full length direction by the rocking means, and the natural frequency calculating means is prevented from shaking the table by the rocking means. The pitching frequency of the vehicle can be calculated on the basis of the load signal from the load cell in the state where the load cell is in the state (fourth invention).

Next, the vehicle natural frequency detection device according to the fifth aspect of the present invention provides:
A vehicle natural frequency detection device for detecting a natural frequency of a vehicle,
A plurality of load cells for detecting the load;
A platform that is supported by the load cell and carries a vehicle;
Stops shaking of the preceding table that is swung with the vehicle by the force that the preceding table receives from the vehicle by the approach of the preceding table or the force that the preceding table receives from the vehicle by stopping the vehicle on the preceding table Anti-sway means,
A natural frequency calculating means for calculating a natural frequency of the vehicle based on a load signal from the load cell;
It is characterized by providing.

A center-of-gravity position measuring apparatus according to the sixth invention
A gravity center position measuring device using the vehicle natural frequency detection device according to the first or fifth invention,
It is characterized by comprising a center-of-gravity height calculating means for calculating the height of the center of gravity of the vehicle based on the natural frequency of the vehicle calculated by the natural frequency calculating means.

  In a sixth aspect of the invention, it is preferable to include a two-dimensional center-of-gravity position calculating means for calculating a two-dimensional center-of-gravity position of the vehicle based on a load signal from the load cell (seventh aspect).

In the vehicle natural frequency detection device according to the first to fourth aspects of the invention, the vertical frequency of the vehicle is calculated based on load signals from a plurality of load cells when the vehicle gets on the platform. Here, because the platform supported by the plurality of load cells is not rocked in the vertical direction due to the structure, the load change due to the vibration component in the vertical direction of the vehicle excluding the vibration component of the platform is caused by the plurality of load cells. As a result, the vertical frequency of the vehicle can be accurately detected.
In addition, after the vehicle gets on the platform, the vehicle on the platform is swung in the width direction or the full length direction by the swinging means, and then the swinging of the mount that is swung with the vehicle is prevented from shaking. Stopped by. As a result, load changes caused by vibration components in the rolling direction or pitching direction of the vehicle, excluding vibration components of the platform, are detected by multiple load cells, and the rolling frequency or pitching frequency of the vehicle is accurately detected. can do.

Also in the vehicle natural frequency detection device of the fifth aspect of the invention, the vertical frequency of the vehicle is calculated based on load signals from a plurality of load cells when the vehicle gets on the platform. Similar to the first to fourth inventions, the platform supported by the plurality of load cells is not rocked in the vertical direction because of the structure. Therefore, the vibration component in the vertical direction of the vehicle excluding the vibration component of the platform. The load change due to is detected by a plurality of load cells, and the vertical frequency of the vehicle can be accurately detected.
In addition, due to the force received by the platform from the vehicle by entering the vehicle platform or the force received by the platform from the vehicle by stopping on the vehicle platform, the platform is swung in the full length direction of the vehicle together with the vehicle, Thereafter, the shaking of the platform that is being swung with the vehicle is stopped by the shaking stopping means. As a result, the load change due to the vibration component in the pitching direction of the vehicle excluding the vibration component of the platform is detected by the plurality of load cells, and the pitching frequency of the vehicle can be accurately detected.

  According to the vehicle natural frequency detection device of the first to fifth inventions, the vibration component of the mounting base is removed, and a load change due to only the vibration component of the vehicle is detected by a plurality of load cells. Since the vehicle natural frequency such as the vertical frequency, rolling frequency, and pitching frequency of the vehicle is calculated based on this, the vehicle natural frequency can be detected accurately.

According to the center-of-gravity position measuring apparatus of the sixth aspect of the invention, the center-of-gravity height of the vehicle is calculated based on the vertical frequency, rolling frequency, and pitching frequency of the vehicle detected by the vehicle natural frequency detection device. Therefore, the height of the center of gravity of the vehicle can be measured with high accuracy.
Furthermore, according to the center-of-gravity position measurement apparatus of the seventh aspect of the invention, since the two-dimensional center of gravity position of the vehicle is calculated based on load signals from a plurality of load cells, the three-dimensional center of gravity position of the vehicle including the center of gravity height can be accurately determined. Can be measured.

It is explanatory drawing of the track scale which concerns on the 1st Embodiment of this invention, (a) is a top view, (b) is the sectional view on the AA line of (a). It is a figure explaining the example of the vehicle which is a measuring object, (a) is a 3 axis vehicle, (b) is a 4 axis vehicle. It is explanatory drawing of the support structure of the mounting stand by a load cell. It is theory explanatory drawing of the restoring force generation | occurrence | production by a load cell. FIGS. 2A and 2B are cross-sectional views taken along the line B-B in FIG. 1, in which FIG. 1A is a state diagram before the platform is swung, and FIG. It is a block diagram of a control system. It is a model figure of the vibration analysis of the vehicle on a mount, (a) is a vertical vibration model figure, (b) is a rolling vibration model figure. (A) is a figure showing the vertical vibration waveform data at the time of boarding of the vehicle on a mounting base, (b) is a figure showing the FFT analysis result of the vertical vibration waveform data of (a). It is a figure showing the waveform data at the time of rolling vibration of a vehicle, (a) is a case where the gravity center height of a vehicle is high, (b) is a case where the gravity center height of a vehicle is low. It is explanatory drawing of how to obtain | require the tread width of a vehicle. It is a figure showing the change of the addition value of all the load cells at the time of boarding of the vehicle on a mounting base. It is explanatory drawing of how to obtain | require the shift | offset | difference of the width direction of the vehicle center with respect to a mounting base. It is explanatory drawing of the method of calculating | requiring the wheel load of a vehicle. It is a definition explanatory drawing of the coordinate system regarding the two-dimensional gravity center position of the vehicle with respect to a mounting base. In diagram showing how the load changes when the vehicle gets into the mounting base is a diagram illustrating the relationship between the position of the first axle x and P _{13 (x)} and P _{13 (t).} It is a flowchart showing the processing content of MPU at the time of track scale measurement operation. In the explanatory view (1) of another example of the swinging / swaying-preventing means, (a) is a state diagram before the stage is swung, and (b) is pressed against the wall surface of the pit after the stage is swung. FIG. In the explanatory view (2) of another example of the swinging / swaying prevention means, (a) is a state diagram before the stage is swung, and (b) is pressed against the wall surface of the pit after the stage is swung. FIG. It is explanatory drawing (3) of another example of a rocking | fluctuation / swaying prevention means, (a) is a top view which shows arrangement | positioning of the link which restrains the displacement of a mounting base, (b) is the theoretical explanatory drawing of the displacement restraint of a mounting base. It is. It is explanatory drawing of the track scale which concerns on the 2nd Embodiment of this invention, (a) is a top view, (b) is the CC line sectional drawing of (a), The state figure before a mounting base is rocked, ( c) is a cross-sectional view taken along the line C-C of (a) and is a state diagram in which the stage is pressed against the wall surface of the pit after being shaken. FIG. 6 is a structural explanatory diagram of a pressure-sensitive rubber / electric resistance wire type tread sensor which is another example of the position information measuring means when the vehicle gets on the platform, and (a) is a diagram seen from the front side in the vehicle traveling direction; (B) is a sectional view taken along line DD of (a), and is a free state diagram, and (c) is a sectional view taken along line DD of (a), and is a conductive rubber compression energized state diagram. FIG. 2 is a schematic diagram for explaining the principle of a pressure sensitive rubber / electric resistance wire type tread sensor, in which (a) is a free state diagram, (b) is an operation state diagram, (c) is an equivalent circuit diagram of (a), (d ) Is an equivalent circuit diagram of (b).

  Next, specific embodiments of the vehicle natural frequency detection device and the gravity center position measurement device according to the present invention will be described with reference to the drawings.

  In the following, a description will be given of a truck scale having both functions of a vehicle natural frequency detection device and a gravity center position measurement device.

[First Embodiment]
<Description of schematic configuration of track scale>
A track scale 1 shown in FIGS. 1 (a) and 1 (b) includes a platform 3 incorporated in a pit 2 formed by digging the ground.
The platform 3 is made of a rectangular plate-like member having a size in a plan view so that a vehicle 4 such as a cargo truck or a trailer can be placed, and the four corners thereof are installed on the bottom surface of the pit 2. 2 load cells 6, third load cells 7 and fourth load cells 8.

<Vehicle description>
In the present embodiment, for example, a cargo truck as shown in FIG. The vehicle 4 shown in FIG. 2 (a) includes a first axle 11 on which the first wheels 9 and 10 are mounted on the left and right sides, and a second axle 14 on which the second wheels 12 and 13 are mounted on the left and right sides, respectively. And a third axle 17 on which the third wheels 15 and 16 are mounted on the left and right, respectively, the first axle 11 is provided below the driver's seat, and the second axle 14 and the third axle 17 are provided below the loading platform. This is a three-axis vehicle.

  In the following description, the front-rear and left-right directions are determined based on the forward direction of the vehicle 4, and the width direction and the full-length direction of the vehicle 4 in the state where the vehicle 4 moves forward and gets on the platform 3 are the width of the platform 3. It shall be made to correspond to a direction and a full length direction, respectively.

<Description of basic structure of first load cell to fourth load cell>
As shown in FIG. 3, each of the load cells 5 to 8 is a column type load cell using a double convex loading type strain gauge, and includes an elastic body 21 and a sealed casing 22.
The elastic body 21 is made of, for example, a metal such as an aluminum alloy or stainless steel and is formed in a substantially cylindrical shape, and is disposed upright with its axis line directed in the vertical direction.
The elastic body 21 has a strain generating portion 23 formed at the central portion in the axial direction, an upper convex surface 24 formed at the upper end, and a lower convex surface 25 formed at the lower end. Both the upper convex surface 24 and the lower convex surface 25 are formed in a partial spherical shape having a predetermined radius of curvature R.
The elastic body 21 is incorporated in the sealed casing 22 in a state where the strain-generating portion 23 is hermetically housed in the sealed casing 22 and the upper end portion and the lower end portion are exposed from the sealed casing 22, respectively.
A required strain gauge (not shown) attached to the strain generating portion 23 converts the load applied to the elastic body 21 into an electrical load signal according to the magnitude and outputs the electrical load signal.

An upper receiving member 26 is interposed between the upper end portion of the elastic body 21 and the mounting table 3. The upper receiving member 26 has a horizontal seating surface 27, and is fixed to the mounting table 3 with the horizontal seating surface 27 being in contact with the upper convex surface 24 of the elastic body 21.
A lower receiving member 28 is interposed between the lower end of the elastic body 21 and the bottom surface of the pit 2. The lower receiving member 28 has a horizontal seating surface 29 and is fixed to the pit 2 with the horizontal seating surface 29 in contact with the lower convex surface 25 of the elastic body 21.

In each of the load cells 5 to 8, a restoring force F _y is generated with respect to the displacement y ₀ of the mounting table 3 in the horizontal width direction (the width direction of the vehicle 4). Similarly, a restoring force F _x is generated with respect to a displacement x ₀ of the mounting table 3 in the horizontal full length direction (the full length direction of the vehicle 4). As a representative, the restoring force _Fy will be described below with reference to FIG.

In FIG. 4, the elastic body 21 of each load cell 5 to 8 moves from the vertical state to the lateral direction by y ₀ along with the displacement y ₀ in the horizontal width direction (the width direction of the vehicle 4) of the mounting table 3, and only θ. An inclined state is shown. Symbols in the figure are defined as follows.
y ₀ : Movement amount of the upper part of the elastic body 21 S: Contact point length between the upper and lower parts of the elastic body 21 H: Height of the elastic body 21 (height of the load cells 5 to 8)
A: radius of curvature of upper convex surface 24 (= R)
B: radius of curvature of lower convex surface 25 (= R)
N: vertical load acting on the elastic body 21 θ: inclination angle of the elastic body 21

In FIG. 4, if the value of the inclination angle θ of the elastic body 21 is very small, the following expression (1) is established.
tan θ≈y ₀ / H (1)

Further, the contact point length S between the upper and lower portions of the elastic body 21 can be expressed by the following equation (2).
S≈A · tan θ + (B−H) tan θ
= (A + B−H) · y ₀ / H (2)

Then, the ratio K between the normal load N and restoring force F _y can be represented by the following formula (3).
K = F _y / N≈S / H = (A + B−H) · y ₀ / H ² (3)

From the above equation (3), the restoring force F _y can be expressed by the following equation (4).
F _y = N · (A + B−H) · y ₀ / H ² (4)
The restoring force F _x can be expressed as the following formula (5) with the aid of the formula (4) with respect to the displacement x ₀ of the mounting table 3 in the horizontal full length direction (the full length direction of the vehicle). it can.
F _x = N · (A + B−H) · x ₀ / H ² (5)

<Description of swinging means and steadying means>
As shown in FIG. 5 (a), a metal fitting 31 protrudes from the lower surface of the mounting table 3, and a hydraulic cylinder 32 is installed inside the pit 2, and the tip of the cylinder rod of the hydraulic cylinder 32 is provided. A pressing metal 33 that can come into contact with the contact metal 31 is attached to the part.
A stopper 34 protrudes from one side surface of the mounting table 3 with a predetermined gap between it and the wall surface of the pit 2.

By the extension operation of the hydraulic cylinder 32, the thrust of the hydraulic cylinder 32 is transmitted from the push fitting 33 to the mounting base 3 through the contact fitting 31, and the mounting base 3 is moved as shown in FIGS. 5 (a) to 5 (b). towards the wall of the pit 2 is pushing on one side in the width direction of the vehicle 4 (see FIG. 5 (b) medium symbol X ₁ in the direction of the arrow). Then, as shown in FIG. 5B, the hydraulic cylinder 32 presses the mounting table 3 against the wall surface of the pit 2 via the stopper 34 and keeps the state.
After the platform 3 is swung toward the one side in the width direction of the vehicle 4 together with the vehicle 4 on the platform 3 by the extension operation of the hydraulic cylinder 32, the platform 3 is moved through the stopper 34 to the wall surface of the pit 2. When the state is held by the hydraulic cylinder 32, the shaking of the mounting table 3 is stopped, while only the vehicle 4 on the mounting table 3 is swung in the width direction.
The hydraulic cylinder 32 functions as a swinging means that swings the vehicle 4 on the mounting table 3, and also functions as a rocking prevention unit that stops the swinging of the mounting table 3 that is swung together with the vehicle 4.
Incidentally, when the oil pressure cylinder 32 is deflated pushing force against the platform 3 does not act, by the action of the restoring force F _y of the load cell 5 to 8, the platform 3 is returned to its original position.

<Description of control system>
Next, the control system of the track scale 1 will be described below with reference to FIG.
In the control system shown in FIG. 6, each signal output from each load cell 5, 6, 7, 8 is amplified to a size that can be A / D converted by the amplifier 35, and then low-pass by the low-pass filter 36. Only the frequency is passed as a signal and fed into the multiplexer 37. The plurality of signals sent to the multiplexer 37 are selectively sent to the A / D converter 38 based on the command of the selection control signal, converted into digital signals by the A / D converter 38, and then the I / D converter 38. Is sent to the MPU 40 via the / O circuit 39.
The MPU 40 fetches signals from the I / O circuit 39 according to a predetermined program stored in the memory 41, reads various data stored in the memory 41, and performs predetermined operations based on these signals and data. Execute. The calculation result is displayed on the display device 42.
The MPU 40 corresponds to “natural frequency calculation means”, “centroid height calculation means”, and “two-dimensional center-of-gravity position calculation means” of the present invention.

<Theoretical explanation of how to find the height of the center of gravity>
Next, how to obtain the height of the center of gravity of the center of gravity G of the vehicle 4 will be described with reference to FIG.
Here, the meanings of symbols used in FIG. 7 and in the theoretical formula are defined as follows.
H _G : Height of center of gravity of vehicle 4 T _r : Tread width of vehicle 4 (effective tread width)
m: total weight of the vehicle 4 k: suspension spring constant of the vehicle 4 h ₁ : height from the platform 3 to above the suspension spring of the vehicle 4 (unsprung height)
h ₂ : Height from above the suspension spring of the vehicle 4 to the center of gravity G g: Gravitational acceleration θ: Rotational angle of the vehicle 4 in the rolling direction Δ: Suspension deformation amount of the vehicle 4 ω: Vertical frequency of the vehicle 4 ω _θ : Vehicle Rolling frequency which is rotational vibration around the center of gravity G in the width direction of 4

First, in FIG. 7A, the equation of motion is established in the vertical direction as follows.

θが微小なとき、ｓｉｎθ≒θとなるので、

Next, in FIG. 7B, considering the balance of moments for rolling vibration, the following is obtained.

Since sin θ≈θ when θ is very small,

前記式（７）より、

前記式（８）の計算結果の正の値（ｈ_２＞０）と、車両４の車種によってある程度決まった値であるばね下高さｈ_１とから下記式（９）を用いて車両４の重心高さＨ_Ｇを求めることができる。
Ｈ_Ｇ＝ｈ_１＋ｈ_２ ・・・（９） In the above formulas (6) and (7), k / m is common, so it is deleted.
From the formula (6),

From the equation (7),

From the positive value (h ₂ > 0) of the calculation result of the equation (8) and the unsprung height h ₁ that is a value determined to some extent depending on the vehicle type of the vehicle 4, the following equation (9) is used to determine the vehicle 4 it can be determined centroid height H _G.
H _G = h ₁ + h ₂ (9)

Next, the values of the vertical frequency ω, the rolling frequency ω _θ and the tread width (distance between the center of the left and right wheels) _Tr of the vehicle 4 required for the calculation using the equation (8) are as follows. How to find it will be explained in order below.

<Explanation of how to find the vertical frequency ω>
FIG. 8A shows the waveforms of the load signals of the load cells 5 to 8 immediately after all the axes of the vehicle 4 have entered the platform 3. FIG. 8B shows the result of FFT (Fast Fourier Transform) analysis of the waveform of FIG.
To calculate the center of gravity height H _G of the vehicle 4, it is necessary to frequency in the vertical direction of the vehicle 4 (Formula (8)), and when boarded to the platform 3 of the vehicle 4, FIG. 8 ( The waveform data shown in a) is acquired.
The vertical frequency ω can be obtained based on the data in FIG. 8B, which is the result of the FFT analysis in FIG.

<Explanation of how to find rolling frequency ω _θ >
FIG. 9 shows the waveform of the load signal of the load cells 5 and 6 (7, 8) with respect to the displacement in the horizontal width direction of the mounting table 3 on which the vehicle 4 is mounted, where the height of the center of gravity of the vehicle 4 is high (a) and low. Case (b) is shown respectively.
In FIG. 9 (a) (b), the line indicated by the symbol L _y0 represents the displacement amount in the horizontal width direction of the platform 3, the line indicated by the symbol L _LC is the load cell 5 in the left column of the platform 3 , 6 represents the waveform data of the load signal. Instead of the load signal waveform data of the load cells 5 and 6 in the left column of the platform 3, the waveform data of the load signals of the load cells 7 and 8 in the right column of the platform 3 may be used. Further, instead of the outputs of the load cells 5 and 6 in the left column (or the load cells 7 and 8 in the right column), the outputs of any one or more load cells on the left or right side may be used.
As is clear from comparison of the load signal waveforms of the load cells 5 and 6 in FIGS. 9A and 9B, when the height of the center of gravity of the vehicle 4 is high (FIG. 9A), the vibration cycle becomes long. In other words, the vibration frequency becomes low, and when the height of the center of gravity of the vehicle 4 is low (FIG. 9B), the vibration cycle becomes short, in other words, the vibration frequency becomes high.

In order to calculate the height of the center of gravity of the vehicle 4, the frequency in the rolling direction of the vehicle 4 is required (see the above formula (8)).
Therefore, as shown in FIGS. 5A and 5B, the platform 3 is moved along with the vehicle 4 on the platform 3 by the extension operation of the hydraulic cylinder 32 (see FIG. 5 (FIG. 5 (B)). b) rocked toward the middle symbol X ₁ arrow), pressed against the wall surface of the pit 2 to the platform 3 through the stopper 34, after stopping the shaking of the platform 3 retain their state by the hydraulic cylinder 32, After waiting for a predetermined stabilization time, waveform data is acquired, subjected to filter processing, and FFT analysis is performed.
Based on the result of the FFT analysis, the rolling frequency ω _θ can be obtained.

<Description of how to obtain tread width _Tr >
In obtaining the tread width _Tr of the vehicle 4, as shown in FIG. 10, for example, a laser beam type distance sensor 43 that measures the distance to the left and right wheels 9, 10; 12, 13; 44 measured values are used.
The distance sensors 43 and 44 are installed on the ground at predetermined intervals on both the left and right sides of the vehicle 4 on the platform 3. The measurement signals of these distance sensors 43 and 44 are given to the MPU 40 via the I / O circuit 39 (see FIG. 6).
Here, D a space set between the left and right distance sensors 43, 44, _{d 1} measured value to the left side wheels 9, 12 and 15 by the left distance sensor 43, the right wheel by the right distance sensors 44 10,13,16 D ₂ , left and right wheels 9, 10; 12, 13; 15, 16 width dimensions u, left wheel 9, 12, 15 outer surface and right wheel 10, 13, 16 outer surface As shown in FIG. 10, the following formulas (10) and (11) are established, where U is the distance of.
D = d ₁ + U + d ₂ (10)
U = T _r + (u / 2) + (u / 2) (11)
From the formulas (10) and (11), the tread width _Tr can be expressed by the following formula (12).
T _r = D−u− (d ₁ + d ₂ ) (12)
Since the value of the installation interval D of the left and right distance sensors 43, 44 is known, and the value of the width dimension u of the left and right wheels 9, 10; 12, 13; 15, 16 is substantially determined by the vehicle type, etc. If the measured values of the left and right distance sensors 43 and 44 are obtained, the value of the tread width _Tr can be obtained from the equation (12).

In this embodiment, in addition to the tread width _Tr described above when the vehicle 4 enters the platform 3, the axle load, wheel load, two-dimensional center of gravity position, etc. of the vehicle 4 are calculated. How to determine each of the axial load, wheel load, and two-dimensional center of gravity position will be described below.

<Explanation of how to calculate axle load>
The relationship between the total load of each load cell 5 to 8 and time is a step-like graph as shown in FIG.
The load value PL ₁ when the first axle 11 is placed on the platform 3, the load value PL ₂ when both the first axle 11 and the second axle 14 are placed on the platform 3, and the entire axles 11, 14. , 17 based on the load value PL ₃ when placed on the platform 3, the axle weight W ₁ of the first axle 11, the axle weight W ₂ of the second axle 14, and the axle weight W of the third axle 17. ₃ can be obtained by the following equations (13), (14), and (15).
W ₁ = PL ₁ (13)
W ₂ = PL ₂ −PL ₁ (14)
W ₃ = PL ₃ -PL ₂ -PL ₁ (15)

<Description of how to calculate wheel load>
In order to accurately obtain the wheel load of the vehicle 4 that has entered the platform 3, information on the boarding position in the width direction of the vehicle 4 is required. The boarding position of the vehicle 4 on the platform 3 can be obtained as follows using the measured values d ₁ and d ₂ of the left and right distance sensors 43 and 44 shown in FIG.
Here, the center line showing the a CL _S, the center position in the width direction of the tread width T _r (intermediate position between the second load cell 6 and the fourth load cell 8) an intermediate position between the first load cell 5 and the third load cell 7 the center line showing the a CL _T, and the distance between these center lines CL _T and the center line CL _S is is f, as is clear from FIG. 12, the following equation holds (16).
D / 2 = d ₁ + U / 2 + f (16)
Since D is d ₁ + d ₂ + U (see the above formula (10)), f can be expressed as the following formula (17).
f = | d ₂ −d ₁ | / 2 (17)

As shown in FIG. 13, the distance between the first load cell 5 and the third load cell 7 (the distance between the second load cell 6 and the fourth load cell 8) is b _W , for example, the left of the first axle 11 The wheel loads of the wheel 9 and the right wheel 10 are W _L1 and W _R1 , respectively, the total load of the first load cell 5 and the second load cell 6 is P _12, and the total load of the third load cell 7 and the fourth load cell 8 is P _34. Then, the following equation holds.
That is, the following equation (18) is established from the balance of loads in the vertical direction.
P ₁₂ + P ₃₄ = W _L1 + W _R1 (18)
From the balance of moments around the first load cell 5, the following equation (19) is established.
W _L1 × {b _W / 2− (T _r / 2 + f)} + W _R1 × {b _W / 2 + (T _r / 2−f)}} = P ₃₄ × b _W (19)
From these equations (18) and (19), the following equations (20) and (21) are obtained.
W _L1 = {P ₁₂ (b _W / 2 + T _r / 2-f) −P ₃₄ (b _W / 2−T _r / 2 + f)} / T _r
... (20)
W _R1 = {− P ₁₂ (b _W / 2−T _r / 2−f) + P ₃₄ (b _W / 2 + T _r / 2 + f)} / T _r
(21)

In the formulas (20) and (21), the distance b _W is a value inherent to the installed platform 3, the loads P ₁₂ and P ₃₄ are measured values by the load cells 5 to 8, and the tread width T _{Since r} is a calculated value according to the equation (12) and the distance f is a calculated value according to the equation (17), these wheel weight values W _L1 and W _R1 can be obtained by substituting these values. .

<Explanation of how to obtain the two-dimensional center of gravity position of the center of gravity G of the vehicle>
Next, how to obtain the coordinates (X _G , Y _G ) of the two-dimensional center of gravity position (horizontal center of gravity position) of the center of gravity G of the vehicle 4 will be described mainly with reference to FIGS.
In FIG. 14, the X axis is defined along the vehicle center line that passes through the center position in the width direction of the vehicle 4 and extends in the full length direction, the Y axis is defined along the first axle 11, and the first axle 11 of the vehicle 4 and the vehicle An orthogonal coordinate system O-XY is defined by taking the origin at the intersection with the center line.
An x-axis is defined along the center line extending in the full length direction through the center position in the width direction of the mounting table 3, a y axis is defined along the center line extending in the width direction through the center position in the full length direction of the mounting table 3, An orthogonal coordinate system o-xy is determined by taking the origin at the center of the stage 3.
Assume that the outputs of the load cells 5 to 8 are adjusted to zero when there is no load.

<Explanation of symbol definitions>
The meanings of symbols used in FIGS. 14 to 15 and in the theoretical formula are defined as follows.
G: Center of gravity of vehicle 4 X _G : Position of center of gravity of vehicle 4 in the full length direction in coordinate system O-XY Y _G : Position of center of gravity in width direction of vehicle 4 in coordinate system O-XY x _G : Vehicle in coordinate system o-xy 4 centroid position in the full length direction y _G : centroid position in the width direction of the vehicle 4 in the coordinate system o-xy a _L : center distance between the first load cell 5 and the second load cell 6 (the third load cell 7 and the fourth load cell) (Center-to-center distance)
V: the platform 3 of the total length dimension l _0: between the centers of the second load cell 6 (fourth load cell 8) and the first axle 11 a distance l _{1, l 2:} inter-axle distance f: the X-axis and the x-axis distance (distance between the center line CL _T and the center line CL _S)
W: Total weight (= W ₁ + W ₂ + W ₃ )
P _i : force acting on the i-th load cell (static load) [= force acting on the loading table 3 from the load cell (static load)]
P _j : force acting on the jth load cell (static load) [= force acting on the mount 3 from the load cell (static load)]
P _ij : P _i + P _j
P = P ₁ + P ₂ + P ₃ + P ₄
^Pi : Effect of the i-th axle on P

<Explanation of measurement of X _G , l _j >
FIG. 15 is a diagram showing the state of load change when the vehicle is placed on the platform, and shows the relationship between the position x of the first axle and P ₁₃ (x) and P ₁₃ (t). Yes.
For the measurement of X _G, it is essential to measure the _{l j.} L _j can be obtained from the waveforms of the outputs P ₁ (t) to P ₄ (t) of the first load cell 5 to the fourth load cell 8.

<Description of how to obtain l ₁ and l ₂ >
The time when the peak first occurs in the P ₁₃ (t) waveform is taken as the time origin (t = 0), and the time when the extreme value occurs after that is defined as t ₁ , t ₂ , and t ₃ .
Let r be the distance between the position x of the first axle 11 corresponding to P ₁₃ (0) and the upstream end of the vehicle forward travel path of the platform 3. This r is equivalent to half the tire ground contact length. Further, s is the distance between the position x of the first axle 11 corresponding to P ₁₃ (0) and the center point of the first load cell 5 (third load cell 7).
For the distance s, the following equation (22) is established.
P ¹ (0) / (a _L + s) = W ₁ / a _L (22)
Here, W ₁ = P ¹ (t), 0 <t <t ₁ .
S can be obtained from the equation (22) as shown in the following equation (23).
s = {P ¹ (0) / W ₁ −1} a _L (23)
On the other hand, the following equation (24) is established for the distance r and the distance s.
r + s = V / 2−a _L / 2 (24)
From the above equation (24), r can be obtained as shown by the following equation (25).
r = V / 2−a _L / 2−s (25)

With respect to the distance l ₁ between the first axle 11 and the second axle 14, a relational expression represented by the following expression (26) is established.
P ¹ (0) / (a _L + s) = P ¹ (t ₁ ) / (a _L + s−l ₁ + r) (26)
From the above equation (26), l ₁ can be obtained as shown in the following equation (27).
l ₁ = (a _L + s) {1−P ¹ (t ₁ ) / P ¹ (0)} + r (27)

In obtaining the distance l ₂ between the second axle 14 and the third axle 17, first, P ¹ (t ₂ ) and P ² (t ₂ ) are obtained.
For P ¹ (t ₂ ), the relational expression shown by the following expression (28) is established.
P ¹ (0) / (a _L + s) = P ¹ (t ₂ ) / (a _L + s−l ₁ ) (28)
From the formula (28), P ¹ (t ₂ ) can be obtained as shown in the following formula (29).
P ¹ (t ₂ ) = {(a _L + s−l ₁ ) / (a _L + s)} P ¹ (0) (29)
^Further, P 2 _{(t 2)} can be obtained from the following equation (30).
P ² (t ₂ ) = P ₁₃ (t ₂ ) −P ¹ (t ₂ ) (30)

Next, P ¹ (t ₃ ) and P ² (t ₃ ) are represented by P ¹ (t ₂ ), P ² (t ₂ ), and l ₂ .
For P ¹ (t ₃ ), the following equation (31) is established.
P ¹ (t ₂ ) −P ¹ (t ₃ ) = {(l ₂ −r) / (a _L + s)} P ¹ (0)
... (31)
From the equation (31), P ¹ (t ₃ ) can be obtained as shown in the following equation (32).
P ¹ (t ₃ ) = P ¹ (t ₂ ) − {(l ₂ −r) / (a _L + s)} P ¹ (0)
... (32)
Further, the following equation (33) is established for P ² (t ₃ ).
_{^{P 2 (t 2) -P 2}} (t 3) = {(l 2 -r) / (a L + s)} P 2 (t 2)
... (33)
From the equation (33), P ² (t ₃ ) can be obtained as shown by the following equation (34).
P ² (t ₃ ) = P ² (t ₂ ) − {(l ₂ −r) / (a _L + s)} P ² (t ₂ )
... (34)

P ₁₃ (t ₃ ) can be expressed by the following equation (35).
P ₁₃ (t ₃ ) = P ¹ (t ₃ ) + P ² (t ₃ ) (35)
The formula (32) and the formula (34) are substituted into the formula (35), respectively.
P ₁₃ (t ₃ ) = P ¹ (t ₂ ) − {(l ₂ −r) / (a _L + s)} P ¹ (0)
+ P ² (t ₂ ) − {(l ₂ −r) / (a _L + s)} P ² (t ₂ )
... (36)
The equation (36) can be modified as shown in the following equation (37).
{(L ₂ −r) / (a _L + s)} · (P ¹ (0) + P ² (t ₂ )) =
P ¹ (t ₂ ) + P ² (t ₂ ) −P ₁₃ (t ₃ ) (37)
From the equation (37), l ₂ can be obtained as shown by the following equation (38).
l ₂ = (a _L + s) [{(P ¹ (t ₂ ) + P ² (t ₂ ) −P ₁₃ (t ₃ )} / {(P ¹ (0) + P ² (t ₂ )}] + r.・ (38)

<Determination of the description of _{X G>}
As is clear from FIG. 14 (a), the center-of-gravity position X _G in the overall length direction of the vehicle 4 can be expressed by the following equation (39).
X _G = − {(a _L / 2−l ₀ ) −x _G } (39)
From the moment balance in a state where all the wheels 9, 10; 12, 13; 15, 16 are placed on the platform 3 (t ₄ <t <t ₅ : see FIG. 7B), the following equation (40) is obtained. To establish.
WV1 ₀ + W ₂ (l ₀ + l ₁ ) + W ₃ (l ₀ + l ₁ + l ₂ ) −P ₁₃ a _L = 0
... (40)
From the equation (40), l ₀ can be obtained as shown by the following equation (41).
l ₀ = {P ₁₃ a _L −W ₂ l ₁ −W ₃ (l ₁ + l ₂ )} / W (41)

Similarly, the following equation (42) is established from the moment balance of the vehicle 4 at time t (t ₄ <t <t ₅ ).
(A _L / 2 + x _G ) P = a _L P ₂₄ (42)
Wherein _{x G} from formula (42) can be obtained as shown in the following equation (43).
x _G = a _L (P ₂₄ / P−1 / 2) (43)
Formula (39) (41) (43) to be able to determine the center of gravity position _{X G} in the overall length direction of the vehicle 4.

<Description of the method of obtaining the _{Y G>}
In FIG. 14, the center-of-gravity position y _G in the coordinate system o-xy of the vehicle 4 can be obtained by the following expression (44) using the outputs P ₁ , P ₂ , P ₃ , and P ₄ of the load cells 5 to 8.
y _G = (P ₁ + P ₂ ) b _W / W−b _W / 2 (44)
However, W = P ₁ + P ₂ + P ₃ + P ₄ .
W may be measured after all the axles 11, 14, and 17 have been placed on the platform 3. The calculation performed using each measurement value does not need to be performed in real time, and may be performed after waveform processing is performed at a necessary timing stored in the memory 41.
Then, the gravity center position Y _G in the Y direction of the vehicle 4 can be obtained by the following equation (45).
Y _G = y _G −f (45)
By substituting the calculated value of the equation (44) and the calculated value of the equation (17) into the equation (45), the value of the gravity center position Y _G of the vehicle 4 can be obtained.

<Description of track scale measurement operation>
The processing contents of the MPU during the track scale measurement operation configured as described above will be described below with reference to the flowchart of FIG. In FIG. 16, the symbol “S” represents a step.

<Description of Processing Contents of Steps S11 to S14>
As the vehicle 4 enters the platform 3, data necessary for calculation such as tread width, axle load, wheel load, two-dimensional center of gravity position, and vertical frequency is acquired (S1).
Next, after a time when a predetermined stabilization time has elapsed after the vehicle 4 is stopped, X _G is expressed by using the equations (39), (41), (43), and the equations (17), (44), ( respectively calculating a _{Y G} using 45) (S2).
Next, a predetermined drive control signal is output toward a drive device (not shown) for the hydraulic cylinder 32 (S3). As a result, by the extension operation of the hydraulic cylinder 32, the mounting table 3 is rocked together with the vehicle 4 on the mounting table 3 toward one side in the width direction of the vehicle 4 (in the direction of the arrow X ₁ in FIG. 5B). After that, the mounting table 3 is pressed against the wall surface of the pit 2 through the stopper 34, and the state is held by the hydraulic cylinder 32, and the shaking of the mounting table 3 is stopped, while only the vehicle 4 on the mounting table 3 is stopped. Is swung in the width direction.
Then, to get the data required for the operation of the rolling angular frequency omega _theta (S4), the equation (8), calculates the center of gravity height _{H G} of (9) (S5).
Then, the measurement result of the three-dimensional center of gravity position of the vehicle 4 is displayed from the calculation result of the two-dimensional center of gravity position (X _G , Y _G ) in step S2 and the calculation result of the center of gravity height H _G in step S5. (S6).

<Description of effects>
In the truck scale 1 of the first embodiment, the vertical frequency ω of the vehicle 4 is calculated based on load signals from the load cells 5, 6, 7, and 8 when the vehicle 4 gets on the platform 3. The Here, since the platform 3 supported by each of the load cells 5 to 8 is not rocked in the vertical direction because of the structure, the load change due to the vibration component in the vertical direction of the vehicle 4 excluding the vibration component of the platform 3. Is detected by each of the load cells 5 to 8, and the vertical frequency ω of the vehicle 4 can be accurately detected.
Further, after the vehicle 4 gets on the mounting table 3, the mounting table 3 is moved along with the vehicle 4 on the mounting table 3 by the extension operation of the hydraulic cylinder 32 (FIG. 5B). After swaying in the direction of the middle symbol X1 (arrow ₁ ), the platform 3 is pressed against the wall surface of the pit 2 via the stopper 34, and this state is held by the hydraulic cylinder 32 to stop the platform 3 from shaking. On the other hand, only the vehicle 4 on the platform 3 is swung in the width direction. Thereby, the load change due to the vibration component in the rolling direction of the vehicle 4 excluding the vibration component of the pedestal 3 is detected by each of the load cells 5 to 8, and the rolling frequency ω _θ of the vehicle 4 is accurately detected. can do.

According to the track scale 1 of the first embodiment, the vibration component of the mounting table 3 is removed, and the load change due to only the vibration component of the vehicle 4 is detected by each of the load cells 5 to 8. Since the vehicle natural frequency such as the vertical frequency ω and the rolling frequency ω _{θ of} the vehicle 4 is calculated based on the signal, the vehicle natural frequency can be accurately detected, and based on these vehicle natural frequencies. the center of gravity height H _G of the vehicle 4 is calculated Te, it is possible to measure the height of center of gravity H _G of the vehicle 4 with high accuracy. Further, since the two-dimensional center of gravity position (X _G , Y _G ) of the vehicle is calculated based on the load signals from the load cells 5 to 8, the three-dimensional center of gravity position of the vehicle 4 including the center of gravity height H _G is accurately determined. Can be measured.

この式（４６）中のＬ_Ｗは、車両４のホイールベースである。
ホイールベースＬ_Ｗは、車両４の第２車軸１４と第３車軸１７との中間に仮想の第２車軸があるものとして、次式（４７）から求めることができる。
Ｌ_Ｗ＝ｌ_１＋ｌ_２／２ ・・・（４７） <Description of a method for determining the center of gravity height H _G with pitching vibration frequency omega _alpha>
In the first embodiment, in the above equation (8), the vehicle 4 necessary for obtaining the center of gravity height H _G using the rolling frequency ω _θ that is the rotational vibration around the center of gravity G in the width direction of the vehicle 4 is used. although an example of obtaining a height h ₂ from the suspension spring to the center of gravity, in place of the rolling vibration frequency omega _theta, using a pitching vibration frequency omega _alpha is a rotational oscillation of the center of gravity G around the entire length direction of the vehicle 4 Then, the value of h ₂ may be obtained.
In this case, it goes without saying that the arrangement or the like of the hydraulic cylinder 32 is changed so that the mounting table 3 is pushed toward one side in the full length direction of the vehicle 4 toward the wall surface of the pit 2 by the extension operation of the hydraulic cylinder 32. Yes. In addition, the following equation (46) is used as the calculation formula with the aid of the equation (8).

_{L W} in the formula (46) is a wheel base of the vehicle 4.
Wheelbase L _W include, but are in the middle of the second axle 14 of the vehicle 4 and the third axle 17 has a virtual second axle can be determined from the following equation (47).
_{L W = l 1 + l 2} /2 ··· (47)

<Explanation of another example of swinging / swaying prevention means>
In the first embodiment, an example in which the hydraulic cylinder 32 is installed inside the pit 2 has been described, but the present invention is not limited to this. For example, the hydraulic cylinder 32 may be provided outside the pit 2. Alternatively, the mounting base 3 may be moved and displaced by attaching the hydraulic cylinder 32 to the mounting base 3 and pressing the metal fitting 33 directly against the side wall of the pit 2.
In addition to using the hydraulic cylinder 32, for example, an electric cylinder may be used, and it is only necessary to apply a force to the mounting table 3 so as to press or pull it against the wall surface of the pit 2. A linear motion mechanism may be used.

In place of the hydraulic cylinder 32 in the first embodiment, as shown in FIG. 17A, a movable stopper 45 is provided on the other side surface of the mounting base 3, and the movable stopper 45 is extended to extend the same figure (FIG. As shown in b), the mounting table 3 may be pressed against the wall surface of the pit 2 via the other stopper 34. Here, examples of the mechanism for expanding and contracting the movable stopper 45 include a mechanism using a hydraulic cylinder and an electric cylinder, and a linear motion mechanism using an electric motor as a drive source. Incidentally, when the pressing force against the platform 3 movable stopper 45 is deflated it does not act, by the action of the restoring force F _y of the load cell 5 to 8, the platform 3 is returned to its original position.

Further, instead of the hydraulic cylinder 32 in the first embodiment, an electromagnet 46 may be used as shown in FIG. That is, for example, an electromagnet 46 is disposed between one side surface of the mounting table 3 and the wall surface of the pit 2 facing the mounting table 3, and the mounting table 3 is pulled toward the wall surface of the pit 2 by the magnetic force of the electromagnet 46. The table 3 may be pressed against the wall surface of the pit 2 via the electromagnet 46 as shown in FIG. Alternatively, the other side surface of the pedestal 3 may be pressed against the wall surface of the pit 2 by applying a repulsive force between the one side surface of the pedestal 3 and the wall surface of the pit 2. Incidentally, when to release the excitation of the electromagnet 46, by the action of the restoring force F _y of the load cell 5 to 8, the platform 3 is returned to its original position.

Further, instead of the hydraulic cylinder 32 in the first embodiment, as shown in FIG. 19A, a mechanism in which a required link 47 for connecting the platform 3 and the pit 2 and an electromagnet 46 are combined. It may be adopted.
Here, as shown in FIG. 19B, the link 47 is arranged with an inclination of θ with respect to the x coordinate axis. By this link 47, the displacements x ₀ and y _{0 in} the x direction and the y direction of the mounting table 3 are constrained by the relationship represented by the following equation (48).
y ₀ = αx ₀ , α = 1 / tan θ (known) (48)
On the other hand, the electromagnet 46 is disposed between the side surface in the positive direction of the y-axis of the mounting table 3 and the wall surface of the pit 2 facing it.
Then, when the vehicle 4 traveling in the positive direction of the x-axis stops shortly before entering the platform 3, the force received from the vehicle 4 due to the restraint of the movement direction of the platform 3 by the link 47 is used. Then, the platform 3 is swung in the positive direction of the y-axis, and the platform 3 is pushed toward one side in the width direction of the vehicle 4 (in the direction of arrow y in FIG. 19B) toward the wall surface of the pit 2. If it is pressed against the wall surface of the pit 2 and the state is held by the electromagnet 46, the shaking of the mounting table 3 is stopped, while only the vehicle 4 on the mounting table 3 is swung in the width direction.
In this example, the link 47 functions as a swinging means for swinging the vehicle 4 on the mounting table 3 in the width direction, and the electromagnet 46 functions as a shaking stopping means for stopping the shaking of the mounting table 3 that is swung together with the vehicle 4. .
The electromagnet 46 may have a performance that can maintain the state in which the mounting table 3 is pressed against the wall surface of the pit 2. Further, when releasing the excitation of the electromagnet 46, by the action of the restoring force F _y of the load cell 5 to 8, the platform 3 is returned to its original position.

[Second Embodiment]
20A and 20B are explanatory views of a track scale according to the second embodiment of the present invention, in which FIG. 20A is a plan view and FIG. 20B is a cross-sectional view taken along the line CC of FIG. (C) is a cross-sectional view taken along the line C-C of (a) and is a state diagram in which the mounting table is pressed against the wall surface of the pit after being shaken.
In the second embodiment, the same or similar parts as those of the first embodiment described above are designated by the same reference numerals in the drawings, and detailed description thereof will be omitted. The description will focus on differences from the first embodiment.

  In the track scale 1A of the second embodiment, the hydraulic cylinder 32 and the like provided in the track scale 1 of the first embodiment are omitted, while the positive direction of the x-axis of the platform 3 (the vehicle 4 An electromagnet 46 is disposed between the side surface in the traveling direction) and the wall surface of the pit 2 facing the side surface. Other configurations are basically the same as those in the first embodiment.

Also in the track scale 1A of the second embodiment, the vertical frequency ω of the vehicle 4 is calculated based on load signals from the load cells 5, 6, 7, and 8 when the vehicle 4 gets on the platform 3. The Similar to the first embodiment, the platform 3 supported by each of the load cells 5 to 8 is not rocked in the vertical direction because of the structure, and therefore the vertical direction of the vehicle 4 excluding the vibration component of the platform 3. The load change due to the vibration component is detected by each of the load cells 5 to 8, and the vertical frequency ω of the vehicle 4 can be accurately detected.
Further, as shown in FIGS. 20B to 20C, the vehicle 4 is caused by the force received by the platform 3 from the vehicle 4 due to the vehicle 4 entering the platform 3 or by the stop of the vehicle 4 on the platform 3. Due to the force received by the mounting table 3, the mounting table 3 is shaken in the full length direction of the vehicle 4 together with the vehicle 4, and thereafter the shaking of the mounting table 3 being swung together with the vehicle 4 is stopped by the electromagnet 46. Thereby, the load change due to the vibration component in the pitching direction of the vehicle 4 excluding the vibration component of the mounting table 3 is detected by each of the load cells 5 to 8, and the pitching frequency of the vehicle 4 is accurately detected. Can do. In this case, the formula as the calculation formula for determining the h ₂ (46) is of course used.
In the second embodiment, special swinging means such as the hydraulic cylinder 32 provided in the first embodiment is not required, and the electromagnet 46 is prevented from shaking the platform 3 that is swung together with the vehicle 4. It functions only as a means.

According to the track scale 1A of the second embodiment, the vibration component of the mounting table 3 is removed, and the load change due to only the vibration component of the vehicle 4 is detected by each load cell 5-8. Since the vehicle natural frequency such as the vertical frequency ω and the pitching frequency ω _{α of} the vehicle 4 is calculated based on the signal, the same effects as the track scale 1 of the first embodiment can be obtained.

  As described above, the vehicle natural frequency detection device and the gravity center position measurement device of the present invention have been described based on a plurality of embodiments. However, the present invention is not limited to the configuration described in the above embodiments, The configuration can be changed as appropriate without departing from the scope.

<Description of another example of measuring means for distance f and tread width _Tr >
In each of the above-described embodiments, the distance sensors 43 and 44 are exemplified as means for measuring the distance f and the tread width _Tr that are the position information of the boarding position of the vehicle 4 on the platform 3. For example, a pressure sensitive rubber / electric resistance wire type tread sensor 60 as shown in FIG. 21 may be used.
In the tread sensor 60 of pressure-sensitive rubber / electric resistance wire type shown in FIGS. 21 (a) and 21 (b), the cover rubber 61 is embedded in the groove on the road surface on the near side that enters the platform 3. A ribbon-like conductive wire 62, a pressure-sensitive conductive rubber 63, and an electric resistance wire 64 are installed in a sandwich state.
When the vehicle 4 passes through the upper surface of the cover rubber 61, if the cover rubber 61 is stepped on the left wheel 9 of the first axle 11, for example, as shown in FIG. Only the pressure-sensitive conductive rubber 63 is compressed, the upper conductive wire 62 and the lower electric resistance wire 64 are short-circuited, and the pressure-sensitive conductive rubber 63 is energized.
FIG. 22A is a state diagram before being stepped on a wheel, FIG. 22C is an equivalent circuit diagram at that time, and FIG. 22B is a state diagram when being stepped on a wheel. ) Is an equivalent circuit diagram at that time.
In the following description, it is assumed that the voltage is measured by each voltmeter, AD conversion is performed, and various calculations are performed as digital values.

When the state of the equivalent circuit shown in FIG. 22 (c), the current _{I 0} flows associated with voltage _{E d0} to resistor _R 0, _{R d} is the resistance _{R d.} This is obtained by measuring the voltage E ₀ with the voltmeter V _d .
I ₀ = E _d / R _d
Also,
I ₀ = E ₀ / (R ₀ + R _d )
From this, the resistance R ₀ is derived.
R ₀ = E ₀ / I ₀ −R _d
Here, R ₀ is a resistance value corresponding to the distance half out of the center line CL _S.

Next, as in the state of the equivalent circuit diagram shown in FIG. _22D , the portion of Rt is short-circuited and becomes conductive, and the current I ₁ flows through the resistor R ₁ + R ₂ + R _d . This is obtained by measuring the voltage E _d1 with the voltmeter V _d .
I ₁ = E _d1 / R _d
Also,
I ₁ = E ₀ / (R ₁ + R ₂ + R ₃ )
From this, the resistance (R ₁ + R ₂ ) is derived.
(R ₁ + R ₂ ) = E ₀ / I ₁ −R _d
(R ₁ + R ₂ ) is a resistance value corresponding to a distance obtained by subtracting the tread width (L _t , R _t ) from half the width dimension (L ₀ , R ₀ ) of the mounting table 3.

Next, the voltage in the state of the equivalent circuit diagram shown in FIG. 22D is measured to derive the resistance value.
From the voltage E ₁ measured by the voltage V ₁ ,
R ₁ = E ₁ / I ₂
From voltage E ₂ measured by voltmeter V ₂ R ₂ = E ₂ / I ₂
When these are converted into distance,
L ₁ = L ₀ R ₁ / (R ₁ + R ₂ )
L ₂ = L ₀ R ₂ / (R ₁ + R ₂ )
L _t = L ₀ -L ₁ -L ₂
= R ₀ -R ₁ -R ₂
It becomes.

The distance S from the center of the mounting table 3 to the center of the tread width _Tr can be obtained by S = L _t + L _t / 2, and the tread width _Tr of the vehicle 4 is S (= L _t + L of the opposite tread sensor). It is obtained by adding _t / 2).
The amount of eccentricity f between the center of the vehicle 4, that is, the center of the tread width _{Tr and} the center of the mounting table 3 is obtained as f = S−T _r / 2.

By the way, since the tread width _Tr takes a value determined to some extent depending on the vehicle type, the tread width _Tr is input in advance based on the vehicle information such as the specification table of the vehicle 4, and the input tread width _Tr You may make it perform calculations, such as a gravity center height, using a value.
Also, if the suspension spring constant k from the vehicle information such as the specifications Table of the vehicle 4 is known, the height h ₂ from the spring to the center of gravity can be obtained without using the vertical frequency [omega.

In each of the above-described embodiments, the example in which the two distance sensors 43 and 44 are provided in order to obtain the distance f that is the position information of the boarding position of the vehicle 4 on the platform 3 has been described. Assuming that the data related to the tread width _Tr is known, only one of the two distance sensors 43 and 44 may be used as the distance sensor for obtaining the distance f.

<Description of another method for calculating the two-dimensional center of gravity position>
Instead of the two distance sensors 43 and 44 in each of the above-described embodiments, a distance sensor that can detect the front wheel position and the rear wheel position of the vehicle 4 mounted on the mounting table 3 is used. The displacement amount S _{FR in} the front-rear direction and the displacement amount S _{LR in the} left-right direction of the vehicle 4 with respect to a reference region (region surrounded by the load cells 5, 6, 7, 8 in plan view) supported by 5, 6, 7, 8 Are obtained, the apparent two-dimensional center of gravity position of the vehicle 3 projected on the reference region of the mounting base 3 is obtained based on the load signals from the load cells 5, 6, 7, and 8, and the apparent two-dimensional center of gravity position is obtained. On the other hand, the two-dimensional center-of-gravity position of the vehicle 4 may be obtained by correcting the displacement amount _SFR and the displacement amount _SLR .

<Description of calculation method for vehicles with 4 axles or more>
In each of the above-described embodiments, the case where the measurement target is a three-axis vehicle as shown in FIG. 2A has been described. However, the four-axis vehicle shown in FIG. In addition, each axle load and inter-axis distance can be obtained in the same manner as the calculation method described in the above embodiment.
For example, in the trailer of the four-axis vehicle shown in FIG. 2B, it is difficult to obtain the axle weights and the inter-shaft distances on the condition that the distance between the third axle 17 and the fourth axle 18 is too short. In such a case, a virtual third axle is set at an intermediate position between the third axle 17 and the fourth axle 18 and is regarded as the three-axle vehicle shown in FIG. Thus, the weight of each shaft and the distance between the shafts may be obtained.

  The vehicle natural frequency detection device and the center-of-gravity position measurement device of the present invention detect a load change due to only the vibration component of the vehicle by a plurality of load cells, and based on the detection signals of these load cells, the vertical frequency and rolling frequency of the vehicle, Since it has the characteristic of calculating the pitching frequency, it can be suitably used for the purpose of detecting the natural frequency of the vehicle and the purpose of measuring the height of the center of gravity of the vehicle using it.

1 Truck scale (vehicle natural frequency detection device, center of gravity position measurement device)
3 Mounting platform 4 Vehicle 5, 6, 7, 8 Load cell 32 Hydraulic cylinder (oscillating means, anti-sway means)
40 MPU (natural frequency calculation means, centroid height calculation means, two-dimensional centroid position calculation means)
45 Movable stopper (swinging means, shaking prevention means)
46 Electromagnet (oscillating means, anti-sway means)
47 Link (swinging means)

Claims (7)

A vehicle natural frequency detection device for detecting a natural frequency of a vehicle,
A plurality of load cells for detecting the load;
A platform that is supported by the load cell and carries a vehicle;
Rocking means for rocking the vehicle on the table,
Anti-sway means for stopping the shaking of the table,
A natural frequency calculating means for calculating a natural frequency of the vehicle based on a load signal from the load cell;
A vehicle natural frequency detection device comprising:   2. The vehicle natural vibration according to claim 1, wherein the natural frequency calculating means calculates a vertical frequency of the vehicle based on a load signal from the load cell when the vehicle gets on the table. Number detection device. The vehicle on the table is swung in the width direction by the swinging means,
2. The natural frequency calculating means calculates a rolling frequency of a vehicle based on a load signal from the load cell in a state where the shaking of the table is stopped by the shaking preventing means. Or the vehicle natural frequency detection apparatus of 2 or 2. The vehicle on the table is swung in the full length direction by the swinging means,
2. The natural frequency calculating means calculates a pitching frequency of a vehicle based on a load signal from the load cell in a state in which the shaking of the table is stopped by the shaking preventing means. Or the vehicle natural frequency detection apparatus of 2 or 2. A vehicle natural frequency detection device for detecting a natural frequency of a vehicle,
A plurality of load cells for detecting the load;
A platform that is supported by the load cell and carries a vehicle;
Stops shaking of the preceding table that is swung with the vehicle by the force that the preceding table receives from the vehicle by the approach of the preceding table or the force that the preceding table receives from the vehicle by stopping the vehicle on the preceding table Anti-sway means,
A natural frequency calculating means for calculating a natural frequency of the vehicle based on a load signal from the load cell;
A vehicle natural frequency detection device comprising: A center-of-gravity position measurement device using the vehicle natural frequency detection device according to claim 1,
A center-of-gravity position measuring device comprising center-of-gravity height calculating means for calculating the height of the center of gravity of the vehicle based on the natural frequency of the vehicle calculated by the natural frequency calculating means. The center-of-gravity position measuring device according to claim 6, further comprising a two-dimensional center-of-gravity position calculating unit that calculates a two-dimensional center-of-gravity position of the vehicle based on a load signal from the load cell.

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