JP2013040795A - Axle weight measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve measurement accuracy of axle weight by enhancing noise attenuation effect of vibration noise applied to a load sensor, and to reduce cost.SOLUTION: As load sensors, three or more wheel load sensors on each of which only one side wheel of right and left wheels is placed to measure weight of the wheel are used. All of the wheel load sensors 11, 12... are located at positions different from each other in a travelling direction of a vehicle travel road 40, and are arranged in a state of being separated to a left side traffic lane part 40a and a right side traffic lane part 40b.

Description

  The present invention relates to an axle weight measuring device for measuring an axle weight (axle weight) of a vehicle.

  The axle weight measuring device measures the axle weight based on the output signal of the load sensor embedded in the vehicle travel path. The running vehicle vibrates due to road surface unevenness and acceleration / deceleration of the vehicle. Since the instantaneous value of the load measured in (1) fluctuates, it is not possible to obtain an accurate value only by measuring the axle load at one place on the vehicle travel path.

  Therefore, for example, as shown in FIG. 16, axle load sensors 21, 22, and 23 that simultaneously load both the left and right wheels 32 and 33 of the vehicle axle 31 and measure the weight of the axle are connected to the arrow of the vehicle travel path 40. Arrangement of at least three or more units along the traveling direction of the vehicle indicated by the symbol A, and taking into consideration the frequency and phase of the sine wave noise signal included in the measured axle weight, and reducing the measurement error by computer simulation The proposal about the space | interval is made | formed (refer patent document 1, 2).

  On the other hand, as an axle weight measuring apparatus using a wheel load sensor that measures the load of a wheel on one side, which is shorter in the width direction of the vehicle travel path 40 than the axle load sensors 21, 22, and 23, for example, 17, the three wheel load sensors 11a, 11b, and 12b are moved to the first and second positions P1 and P2 along the traveling direction of the vehicle indicated by the arrow A of the vehicle traveling path 40, as shown in FIG. Some are arranged (see Patent Document 3). In this axle weight measuring device, wheel load sensors 11a and 11b for measuring the loads of the left and right wheels 32 and 33 on the left and right sides of the axle 31 are arranged at the first position P1, and one side at the second position P2. For example, a wheel load sensor 12b that measures the load of the right wheel 33 is disposed.

  In this axle weight measuring device, the load measured by the left and right wheel load sensors 11a and 11b at the first position P1 is added to calculate the axle weight at the first position P1, and the ratio of the left and right measured loads is calculated. Then, using this ratio, the load of the left wheel 32 is calculated from the measured load of the wheel load sensor 12b at the second position P2, and the calculated load on the left side and the measured load on the right side of the wheel load sensor 12b 2 is calculated. The average value of the axle weight at the first position P1 and the axle weight at the second position P2 is used as the axle weight of the axle.

  Further, in order to simplify the configuration and reduce the cost, for example, as shown in FIG. 18, the two wheel load sensors 11 a and 12 b are connected to the vehicle travel direction indicated by the arrow A of the vehicle travel path 40. Are arranged at the first and second positions P1 and P2 along the line (see Patent Document 4). A wheel load sensor 11a that measures the load on one side of the axle 31, for example, the left wheel 32, is disposed at the first position P1, and a wheel that measures the load on the right wheel 33 is disposed at the second position P2. A load sensor 12b is arranged. In this axle weight measuring apparatus, the measured load by the wheel load sensor 11a is doubled to obtain the axial weight at the first position P1, and the measured load by the wheel load sensor 12b is doubled to obtain the axial weight at the second position P2. The average value of the axle weights at both positions P1 and P2 is used as the axle weight of the axle.

JP 2000-12418 A JP 2004-271378 A Japanese Patent Laying-Open No. 2005-127951 (Patent No. 4114591) JP 2010-223755 A

  There are many types of vehicles that pass over the load sensor of the axle weight measuring device, and the structure and mass of the vehicle body are also various. Further, the speed of the vehicle passing through the load sensor also varies from the speed just before the stop to around 100 km / h. As a result, the period of the sinusoidal vibration noise signal included in the signal measured by the load sensor varies from several Hz to about 10 Hz depending on the vehicle type, the vehicle body mass, and the vehicle-mounted spring constant. When measuring by installing a plurality of load sensors on the vehicle travel path, the phase of the sinusoidal vibration noise with respect to the load measurement timing by the plurality of load sensors varies depending on the vehicle speed and frequency.

  Therefore, in the case of a load sensor installed at a predetermined interval as in the prior art described above, the relationship between the load measurement timing and the phase of the vibration noise signal is inconsequential under conditions where the speed and frequency of the vehicle are different each time. The vibration noise applied to each load sensor is extremely difficult to cancel out by calculation, and the attenuation effect of the vibration noise, that is, the measurement accuracy is different for each conventional technique.

  Based on this, it is possible to evaluate the measurement accuracy of each of these conventional technologies, and based on this, when various vehicles travel on the load sensor at various speeds, they are measured statistically as the measurement results of the axle weight of the entire passing vehicle. It is desired to develop an axle weight measuring device that has high accuracy and is advantageous for cost development.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a low-cost axle weight measuring apparatus with high axle load measurement accuracy.

  In order to achieve the above object, the present invention is configured as follows.

  The axle weight measuring device according to the present invention includes a plurality of wheel load sensors that are arranged on a vehicle traveling path and measure wheel weights that are the weights of wheels on one side of the left and right wheels of the axle, and the plurality of wheel load sensors. An axle weight measuring device comprising a computing unit for computing axle weight based on the measured wheel weight measured by the vehicle, comprising three or more wheel load sensors as the plurality of wheel load sensors. The wheel load sensors of the pedestal or higher are all located at different positions along the vehicle traveling direction of the vehicle traveling path, and the left side of the lane that divides one lane of the vehicle traveling path into left and right in the width direction; They are arranged separately on the right side of the lane.

  All the wheel load sensors are located at different positions along the vehicle traveling direction on the vehicle traveling path because the wheel load sensors are arranged at the same position in the vehicle traveling direction along the vehicle traveling direction. This means that the wheel load sensors are arranged at intervals along the traveling direction of the vehicle on the vehicle traveling path.

  The relationship between the number of wheel load sensors arranged on the left side of the lane and the number of wheel load sensors arranged on the right side of the lane is arbitrary in the left side of the lane and the right side of the lane that divides one lane in the width direction. is there. The left side may be more, and conversely, the right side may be more. When the total number is an even number, the left and right sides may be the same number. The left / right distribution is completely arbitrary.

  Accordingly, one or more units may be arranged on the left side (or right side) and one or more units on the right side (or left side) along the traveling direction of the vehicle. The number of repetitions of is also arbitrary. For example, one or more units may be arranged on the left side (or right side), one or more units on the right side (or left side), and one or more units on the left side (or right side) along the traveling direction of the vehicle. Alternatively, one or more units on the left side (or right side), one or more units on the right side (or left side), one or more units on the left side (or right side), or right side (or right side) Alternatively, one or more units may be arranged on the left side, and further, one or more units on the left side (or right side), one or more units on the right side (or left side), and the left side along the traveling direction of the vehicle One or more units (or right side), one or more units on the right side (or left side), and one or more units on the left side (or right side) may be arranged. Is also optional.

  As described above, regarding the arrangement of the first wheel load sensor at the most upstream position in the traveling direction, it may be the lane left side or the lane right side.

  According to the axle weight measuring device of the present invention, at least three wheel load sensors for measuring the wheel weight, which is the weight of one wheel, are all located at different positions along the traveling direction of the vehicle on the vehicle traveling path. Moreover, by separately arranging the lane left side portion and the lane right side portion, the noise attenuation effect of the vibration noise included in the signal measured by the wheel load sensor is increased as described later, and the measurement accuracy is improved. In other words, since independent random noise can be measured by the number of installed units in each wheel load sensor, a large noise attenuation effect can be obtained in the axle weight measurement value obtained by the averaging process. In other words, the present invention provides a wheel load sensor arrangement method that has the highest noise attenuation effect for the number of wheel load sensors used in measuring the axle weight value.

  In addition, compared to the case of using an axle load sensor that measures the weight of the axle by placing both the left and right wheels at the same time, a wheel load sensor that measures the wheel weight that is the weight of the wheel on one side is used. Moreover, since all the wheel load sensors are arranged at different positions in the traveling direction of the vehicle traveling path, two wheel load sensors are linearly arranged at the same left and right positions in the traveling direction of the prior art. As compared with the case where the vehicle is laid side by side, the wheel load sensor can be laid efficiently in the vehicle travel path.

  In a preferred embodiment of the axle weight measuring apparatus according to the present invention, when the wheel load sensors arranged on the left side of the lane include a plurality of wheel load sensors, the calculation unit is configured to measure the wheel load by each of the plurality of wheel load sensors. When the wheel load sensor arranged on the left side of the lane is one, the wheel load sensor measured by the one wheel load sensor is used as the measurement wheel weight on the left side of the lane. When there are a plurality of wheel load sensors arranged on the right side of the lane, the average value of the measured wheel weights of the plurality of wheel load sensors is measured on the right side of the lane. When the number of wheel load sensors arranged on the right side of the lane is one, the measurement wheel weight of the one wheel load sensor is used as the measurement wheel weight of the right side of the lane, and the left side of the lane Measurement Heavy said by adding the lane right portion of the measuring wheel load calculating the axle weight.

  According to this embodiment, when there are a plurality of wheel load sensors arranged on one side of the left or right lane, the average value of the measurement wheel weights by the plurality of wheel load sensors is measured on the measurement wheel on the one side of the lane. If there is only one wheel load sensor arranged on one side of the lane, the measurement wheel weight of the one wheel load sensor is taken as the measurement wheel weight on the one side of the lane, and both the left and right lanes By calculating the axle load by adding the wheel load on one side, as described later, it is excellent in the noise attenuation effect of vibration noise contained in the signal measured by the wheel load sensor, and increases the axle load measurement accuracy. Can do.

  According to the axle weight measuring device of the present invention, the noise attenuation effect of vibration noise applied to the load sensor can be enhanced to improve the measurement accuracy, and the cost can be reduced.

The block diagram which shows the structure of the axle weight measuring apparatus of embodiment of this invention. Explanatory drawing of the arrangement | positioning pattern 1 of the wheel load sensor of the axle weight measuring apparatus of this invention Explanatory drawing of the arrangement pattern 2 of the wheel load sensor of the axle weight measuring apparatus of this invention Explanatory drawing of the arrangement pattern 3 of the wheel load sensor of the axle weight measuring apparatus of this invention Explanatory drawing of the arrangement | positioning pattern 4 of the wheel load sensor of the axle weight measuring apparatus of this invention Explanatory drawing of the arrangement | positioning pattern 5 of the wheel load sensor of the axle weight measuring apparatus of this invention Explanatory drawing of the arrangement | positioning pattern 6 of the wheel load sensor of the axle weight measuring apparatus of this invention Explanatory drawing of the arrangement pattern 7 of the wheel load sensor of the axle weight measuring apparatus of this invention Explanatory drawing of the arrangement | positioning pattern 8 of the wheel load sensor of the axle weight measuring apparatus of this invention Explanatory drawing of the arrangement | positioning pattern 9 of the wheel load sensor of the axle weight measuring apparatus of this invention Explanatory drawing of an example of arrangement of a conventional axle load sensor Explanatory drawing of simulation about variation index and damping rate of vibration noise signal in axle weight performed by the present inventors Explanatory drawing of the example of arrangement of other prior art wheel load sensors Explanatory drawing of another example of arrangement of other prior art wheel load sensors Further, an illustration of an arrangement example of another conventional wheel load sensor The figure which shows the example of arrangement | positioning of the axle load sensor of a prior art. The figure which shows the example of arrangement | positioning of the wheel load sensor of another prior art Furthermore, the figure which shows the example of arrangement | positioning of the wheel load sensor of another prior art

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an axle weight measuring apparatus according to one embodiment of the present invention.

  In the figure, 11, 12, 13, and 14 are wheel load sensors that measure the wheel weight, which is the weight of a wheel on one side, 2 is an amplifying unit, 3 is an A / D converter, 4 is an input / output unit, and 5 is an arithmetic unit. , 6 is a storage unit, 7 is a display unit, and 8 is an operation unit / data input unit. Reference numeral 31 denotes a vehicle axle, reference numerals 32 and 33 denote wheels, reference numeral 40 denotes a vehicle travel path, reference numeral 40a denotes a left side lane that divides the vehicle travel path 40 left and right in the width direction, and reference numeral 40b denotes a right side lane. FIG. 1 representatively shows an arrangement pattern of wheel load sensors, and specific various arrangement patterns will be described later.

  The wheel load sensors 11, 12, 13, and 14 are, for example, loading plate type wheel load sensors that measure the entire weight of the wheel on one side of the traveling vehicle with a loading plate that is wider than the ground contact width of the tire. The wheel load sensors 11, 12, 13, and 14 may be bar-type wheel load sensors that measure the partial pressure value of the wheel on one side with a sensor that is narrower than the ground contact width of the tire. Integrates the partial pressure value measured by the bar-type wheel load sensor to calculate the total weight of the wheel on one side.

  The output terminals of the plurality of wheel load sensors 11, 12, 13, and 14 are connected to the input terminal of the amplifying unit 2, and the output terminal of the amplifying unit 2 is connected to the input terminal of the A / D conversion unit 3 in units of wheel load sensors. The output terminal of the A / D conversion unit 3 is connected to the calculation unit 5 via the input / output unit 4. The arithmetic unit 5 is constituted by a microcomputer, for example, and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory) and the like. A storage unit 6 is connected to the calculation unit 5, and the storage unit 6 is composed of, for example, a hard disk. A display unit 7 and an operation unit / data input unit 8 are connected to the input / output unit 4.

  Load signals w 1, w 2, w 3, w 4 from the wheel load sensors 11, 12, 13, 14 are input to the amplifying unit 2 and are amplified in the amplifying unit 2. The amplified analog load signal output from the amplifier 2 is converted into digital load data by the A / D converter 3. The load data generated by the A / D conversion unit 3 is input to the calculation unit 5 via the input / output unit 4.

  The calculation unit 5 operates according to a program read from the ROM while using the RAM as a work memory, performs predetermined calculation processing based on the load data (w1, w2, w3, w4) from the A / D conversion unit 3, The obtained calculation result is stored in the storage unit 6. The result includes the axle weight W of one axle that should be finally obtained. In addition, the calculation unit 5 outputs display data obtained based on the processing result to the display unit 7 via the input / output unit 4. The operator uses the operation unit / data input unit 8 to give various commands or input various data.

  Each wheel load sensor 11, 12, 13, 14 has a plurality of load cells and a weighing platform on the top thereof. As shown in FIG. 1, the length L of the weighing platform is shorter than the one-side traffic area dimension L3 of the vehicle travel path 40 and shorter than the inner dimension L1 between the tires of the left and right wheels 32 and 33 of the axle 31. Is set. Further, for example, when it is assumed that the wheel load sensor 13 of the lane right side portion 40b is arranged at the same position in the vehicle traveling direction as the wheel load sensor 11 of the lane left side portion 40a, the distance between the wheel load sensors 11, 13 is assumed. Is L4, that is, a distance obtained by adding the distance from the wheel load sensor 11 to the center of the lane and the distance from the wheel load sensor 13 to the center of the lane is L4, the inner dimension L1 of the tire and the width L2 of the wheels 32 and 33 The value (L1 + L2) obtained by adding is set to be smaller than the value (L4 + L) obtained by adding the distance L4 and the length L of the weighing table, that is, (L1 + L2) <(L4 + L). This is to ensure that the tire having the width L2 of one of the wheels is completely placed on the weighing platform when the vehicle passes on the vehicle travel path 40.

  When an initial load such as a weighing platform load in the wheel load sensor 11 or the like is input using the operation unit / data input unit 8 at the installation stage, the data is held in the storage unit 6 via the calculation unit 5. Further, the zero point variation amount is also held in the storage unit 6. At the time of actual measurement when the left and right wheels of the vehicle pass over the weighing table, only the load on the weighing table is calculated as wheel loads w1, w2, w3, w4 by offset calculation and displayed on the display unit 7, and also the storage unit 6 is stored.

  The present invention includes three or more wheel load sensors, has a feature in its arrangement pattern, can measure the axial weight with high accuracy, and can reduce the cost.

  Prior to the description of the specific wheel load sensor arrangement pattern of the present invention, a method for evaluating the measurement accuracy of the axle load will be described.

  In this measurement accuracy evaluation method, vibration noise included in the measurement signal of the load sensor is regarded as random noise, and the measurement accuracy is evaluated based on the noise attenuation effect.

  That is, as described above, vibration is caused in the traveling vehicle body by the unevenness of the vehicle traveling road surface and the acceleration / deceleration of the vehicle. The vibration is transmitted to the tire that elastically supports the vehicle body, and a sinusoidal vibration noise signal is superimposed on the axial load measurement signal. There are various types of vehicles to be measured, such as the structure and weight of the vehicle body, and the running speed varies from the speed just before the stop to around 100 km / h, so the frequency of the vibration noise signal is also several Hz to 10 Hz. Until the ward.

  Therefore, when various vehicles pass through the load sensor at various speeds, it is considered that the state becomes almost the same as when random noise is individually applied to the load sensor.

  Therefore, such vibration noise is treated as random noise, and the measurement accuracy of the axle weight measuring device is evaluated based on the noise attenuation effect.

  Here, first, the axle weight measuring devices according to the prior art shown in FIGS. 16 to 18 are evaluated.

  The above-described evaluation of the prior art shown in FIG. 16 will be described with reference to FIG.

  As shown in FIG. 11A corresponding to FIG. 16, three axle load sensors 21, 22, 23 are arranged. These axle load sensors place both the left and right wheels 32 and 33 of the axle 31 of the vehicle and measure the weight of the axle. The three axle load sensors 21, 22, and 23 are arranged at different positions along the traveling direction of the vehicle indicated by the arrow A in the vehicle traveling path 40.

When the left and right wheels 32 and 33 of the axle 31 pass through the first axle load sensor 21, the axle load W1 measured by the first axle load sensor 21 adds the loads of the left and right wheels 32 and 33. Is equivalent to When the left and right wheels of the same axle pass through the second axle load sensor 22, the axle weight measured by the second axle load sensor 22 is W2, and the left and right wheels of the same axle are the third axle load sensor. If the axle weight measured by the third axle load sensor 23 when passing through the axle 23 is W3, the axle weight W of one axle to be finally obtained is the three axle load sensors 21, 22, 23. It is expressed by a simple average value of the axial weights W1, W2, and W3. That is, as shown in FIG.
W = (W1 + W2 + W3) / 3 (1)
It is.

  Here, the vibration noise signal superimposed on the axle load measurement signal is treated as random noise as described above, and the standard deviation of the vibration noise signal superimposed on the axle load detection signal including the left and right wheel loads is combined. Is “σ”. This vibration noise signal is applied to the left and right wheels 32 and 33 with substantially the same magnitude and the same phase. Therefore, a total of standard deviation (2σ) noise signals are added to one axle load sensor.

  By the way, since the three axle load sensors have the same specifications and are installed under the same conditions, signals from the same noise source are added. However, in most vehicle traveling, a special cancellation condition due to the phase relationship of the sine wave is not established between a plurality of axle load sensors having different installation positions. Therefore, the noise signals of each of the plurality of axle load sensors may be regarded as independent from each other and can be treated as random noise.

Therefore, as described above, if a noise signal having a standard deviation (2σ) is superimposed on one axle load sensor and this is similarly applied to the three axle load sensors 21, 22, and 23, a simple average is obtained. The variation index S of the vibration noise signal with respect to the axle weight W is
S = {(2σ) ² + (2σ) ² + (2σ) ² } ^1/2 / 3
= (4/3) ^1/2 σ = 1.155σ (2)
It becomes. Here, “divide by 3” corresponds to “divide by 3” in Equation (1). With reference to the standard deviation (2σ) for the one axle load sensor, the noise signal is attenuated at the axle weight W = (W1 + W2 + W3) / 3 when the three axle load sensors 21, 22, 23 are used. The rate R is
R = (1.155σ) / (2σ) = 0.777 (3)
It becomes. The attenuation rate is preferably as the value R is smaller, because the noise attenuation effect is better. That is, the measurement accuracy of the axle weight W is more excellent as the attenuation rate R is smaller.

  As described above, the measurement accuracy of the axle weight W based on the total of the measurement axle weights W1, W2, and W3 by the plurality of load sensors used can be evaluated by the attenuation rate R. In other words, the standard deviation (2σ) of the vibration noise signal applied to each of the plurality of load sensors is integrated to obtain the vibration noise signal variation index S in the axle weight W obtained by the simple average as the final target. Further, the ratio of the variation index S of the vibration noise signal in the axle weight W obtained by a simple average with respect to the standard deviation (2σ) for one axle load sensor is obtained as an attenuation rate R, and this attenuation rate R is used to determine the axle weight W. Evaluate measurement accuracy.

  The above description is for the case where there are three axle load sensors. As a reference, the case of an axle weight measuring device in which two, four, and five axle load sensors are arranged will be described next (FIG. 11 (b). ) Refer to the lower part).

When two units are installed, the variation index S and the attenuation rate R of the vibration noise signal in the axle weight W obtained by the simple average as described above are as follows:
S = {(2σ) ² + (2σ) ² } ^1/2 / 2 = 2 ^1/2 σ
= 1.414σ …………… (4)
R = (1.414σ) / (2σ) = 0.707 (5)
It becomes.

When four units are installed, the variation index S and the attenuation rate R of the vibration noise signal in the axle weight W obtained by the simple average as described above are:
S = {(2σ) ² + (2σ) ² + (2σ) ² + (2σ) ² } ^1/2 / 4
= 2 ・ (2σ) / 4 = σ (6)
R = 0.5 (7)
It becomes.

When five units are installed, the variation index S and the damping rate R of the vibration noise signal in the axle weight W obtained by the simple average as described above are as follows:
S = {(2σ) ² + (2σ) ² + (2σ) ² + (2σ) ² + (2σ) ² } ^1/2 / 5
= 5 ^1/2 · (2σ) / 5 = (2/5 ^1/2 ) σ = 0.894σ (8)
R = (0.8944σ) / (2σ) = 0.447 (9)
It becomes.

  The above is the theoretical value of the attenuation rate R with respect to the number of installed units when random noise is applied.

  The inventors of the present invention simulated how much the damping rate R based on the above-described theoretical value has as an index for evaluating the measurement accuracy of the axle weight W.

It is assumed that the vibration noise signal is a sine wave having a frequency of 2 Hz, 3 Hz, and 4 Hz with respect to the attenuation rate based on the above theoretical value, and the vehicle travels at various speeds of 30 to 90 km / h. When the number of axle load sensors is 2, 3, 4, and 5, each simulates the case of using one wide loading plate type sensor and the rest using an elongated bar type sensor. Then, the attenuation rate R of the measurement error of the axle weight in the region exceeding the vehicle speed of 30 km / h was obtained. as a result,
R = 0.85 when two units are installed
In case of 3 units, R = 0.7
In case of 4 units, R = 0.5
R = 0.3 when 5 units are installed
It became.

  FIG. 12 shows a graph comparing the above theoretical values with simulation results.

  In the case of the theoretical value indicated by ○, the attenuation rate is 0.707 for 2 units, 0.577 for 3 units, 0.577 for 4 units, 0.5 for 5 units, and 0.477 for attenuation rate. It was. On the other hand, in the simulation results indicated by ◆, the number of the two units was 0.85, the number of the three units was 0.7, the number of the four units was 0.5, and that of the five units was 0.3.

  Comparing the above theoretical values (0.707, 0.577, 0.5, 0.477) with the simulation results (0.85, 0.7, 0.5, 0.3), the vibration noise signal is The attenuation rate for random noise when considered as random noise may be approximately approximate. Here, there is no particularly effective effect due to the phase cancellation in the attenuation rate. Therefore, this evaluation method devised by the present inventors can be regarded as valid in the relationship between the number of installed vehicles and the attenuation rate when various vehicles travel at various speeds.

  One axle load sensor measures both the weight of the axle by placing both the left and right wheels at the same time. Therefore, the axle load sensor is manufactured as having a long dimension in the width direction perpendicular to the traveling direction of the vehicle on the vehicle traveling path. In other words, it has a length sufficient to occupy a large portion of the entire road width. The axle load sensor includes a plate-like weighing platform on which the left and right wheels are simultaneously mounted, and a plurality of load cells that support the weighing platform and detect applied weight under the weighing platform, but the weighing platform is long. Due to the size and the large number of load cells associated with the long weighing platform, the initial cost of the axle load sensor is high. Furthermore, the construction for embedding this long axle load sensor on the road surface becomes large and the installation cost is high.

  For this reason, in recent years, the use of “wheel load sensors” having a length that is approximately half the length of “axle load sensors” has increased.

  Next, the evaluation of the above-described prior art of FIG. 17 using such a wheel load sensor will be described with reference to FIG.

  As shown in FIG. 13A corresponding to FIG. 17, three wheel load sensors 11a, 11b, and 12b are arranged. The arrangement is two positions P1, P2 separated along the traveling direction of the vehicle indicated by the arrow A of the vehicle traveling path 40. At the first position P1, the wheel load sensor 11a is disposed at the lane left side 40a of the vehicle travel path 40, and the wheel load sensor 11b is disposed at the lane right side 40b. These two wheel load sensors 11a and 11b are disposed at the same first position P1 in the traveling direction of the vehicle traveling path 40. At the second position P2, the wheel load sensor 12b is disposed on the lane right side portion 40b.

  The size of the wheel load measured by the wheel load sensor 11a on the left side lane 40a at the first position P1 is w1a, and the size of the wheel load measured by the wheel load sensor 11b on the right side lane 40b at the first position P1 is also set. Let w1b be the size of the wheel load measured by the wheel load sensor 12b on the right side lane 40b of the second position P2, and let it be w2b.

  At the second position P2, the wheel load sensor is not disposed on the left side lane 40a of the lane, but it is assumed that the wheel load sensor is disposed here, and the wheel load sensor measured by the virtual wheel load sensor is used. Is estimated, and this is defined as w2a ′. The wheel load w2a ′ measured by the wheel load sensor on the virtual lane left side 40a is obtained by calculation.

The ratio r of the left and right measurement wheel weights at the first position P1 is
r = w1a / w1b (10)
It is. Using the right and left measurement wheel weight ratio r, the virtual left measurement wheel weight w2a ′ is obtained from the right measurement wheel weight w2b at the second position P2.
w2a '= r.w2b = (w1a / w1b) .w2b
It becomes.

In this prior art, the axial load W1 at the first position P1 is determined from the left measurement wheel weight w1a and the right measurement wheel weight w1b.
W1 = w1a + w1b
It is said.

The axial load W2 at the second position P2 is calculated from the left virtual wheel load w2a 'and the right wheel load w2b.
W2 = w2a ′ + w2b
It is said.

The obtained axle weight W of one axis is obtained by taking an average value at the first position P1 and the second position P2.
W = (W1 + W2) / 2
= {(W1a + w1b) + (w2a ′ + w2b)} / 2 (11)
It is said.

When various vehicles pass over the wheel load sensor at an arbitrary vehicle speed, sinusoidal vibration noise signals having substantially the same phase and the same magnitude are applied to the left measurement wheel weight w1a and the right measurement wheel weight w1b. Let Δe be the error due to noise. The error Δe is sufficiently small compared to the measurement wheel weights w1a and w1b, but is assumed to be a value that cannot be ignored as the magnitude of the error. The left measurement wheel weight and the right measurement wheel weight including the error Δe are (w1a + Δe) and (w1b + Δe), respectively. Therefore, the ratio r of the left and right measurement wheel weights is
r = (w1a + Δe) / (w1b + Δe)
Multiply the denominator and numerator of this equation by (w1b-Δe) respectively.
r = {(w1a + Δe) · (w1b−Δe)} / {(w1b + Δe) · (w1b−Δe)}
= (W1a · w1b + w1b · Δe−w1a · Δe−Δe ² ) / (w1b ² −Δe ² )
≒ (w1a · w1b + w1b · Δe-w1a · Δe) / w1b ²
= W1a / w1b + (w1b-w1a) · Δe / w1b ²
Here, if there is no large weight difference between the left and right wheels, w1a≈w1b and (w1b−w1a) ≈0. Since Δe is also small, Δe ² ≒ 0, may be considered as (w1b-w1a) · Δe / w1b 2 ≒ 0. as a result,
r≈w1a / w1b (12)
It becomes. Therefore, it can be considered that the error r due to the noise signal is not included in the ratio r of the left and right measurement wheel weights at the first position P1. The same applies to the ratio r of the left and right measurement wheel weights at the second position P2. As a result, the left measurement wheel weight w1a and the right measurement wheel weight w1b include noise signals having the same phase and substantially the same amplitude, and the left measurement wheel weight w2a ′ and the right measurement wheel weight w2b Are considered to include noise signals having the same phase and substantially the same amplitude.

As in the case of the prior art of FIG. 11 above, the standard deviations of the vibration noise signals received by the left and right tires are each “σ”. Then, the axial weight W1 = (w1a + w1b) at the first position P1 and the axial weight W2 = (w2a ′ + w2b) at the second position P2 each include random noise with a standard deviation (2σ). become. Therefore, the variation index S of the vibration noise signal in the axle weight W obtained by the simple average corresponding to the equation (11) is the same as the case where two axle load sensors are arranged in the end.
S = {(2σ) ² + (2σ) ² } ^1/2 / 2 = 2 ^1/2 σ
= 1.414σ …………… (13)
It becomes. Here, “divide by 2” corresponds to “divide by 2” in Equation (11).

The attenuation rate R at this time is
R = (1.414σ) / (2σ) = 0.707 (14)
It becomes. This performance is inferior to the axle weight measuring device of FIG. However, since the wheel load sensor is used instead of the axle load sensor as shown in FIG. 11, the cost is low.

  Furthermore, as another arrangement example of the prior art, as shown in FIG. 14, evaluation is performed for a case where four wheel load sensors 11a, 11b, 12b, and 13b are arranged. The wheel load sensors 11a, 11b, 12b, and 13b are arranged at three positions P1, P2, and P3 separated along the traveling direction of the vehicle indicated by the arrow A on the vehicle traveling path. At the first position P1, the wheel load sensor 11a is disposed at the lane left side 40a of the vehicle travel path 40, and the wheel load sensor 11b is disposed at the lane right side 40b. These two wheel load sensors 11a and 11b are disposed at the same first position P1 in the traveling direction of the vehicle traveling path. At the second position P2, the wheel load sensor 12b is disposed on the lane right side portion 40b. At the third position P3, the wheel load sensor 13b is disposed on the lane right side portion 40b.

  The size of the wheel load measured by the wheel load sensor 11a on the left side lane 40a at the first position P1 is w1a, and the size of the wheel load measured by the wheel load sensor 11b on the right side lane 40b at the first position P1 is also set. Let w1b be the size of the wheel load measured by the wheel load sensor 12b on the right side lane 40b of the second position P2, and let w2b be the size of the wheel load measured by the wheel load sensor 13b on the right side lane 40b of the third position P3. Let w3b.

At the second position P2, the wheel load sensor is not disposed on the left side lane 40a of the lane, but it is assumed that the wheel load sensor is disposed here, and the wheel load sensor measured by the virtual wheel load sensor is used. Is estimated, and this is defined as w2a ′. The wheel load w2a ′ measured by the wheel load sensor on the virtual lane left side 40a is obtained by calculation. As in the case of the prior art shown in FIG. 13 above, r = w1a / w1b
w2a '= r.w2b = (w1a / w1b) .w2b
It becomes.

At the third position P3, no wheel load sensor is arranged on the left side lane 40a of the lane, but it is assumed that a wheel load sensor is arranged here, and the wheel load sensor measured by the virtual wheel load sensor is used. Is estimated and is set as w3a ′. When calculating the wheel load w3a ′ measured by the wheel load sensor in the virtual lane left side 40a,
w3a ′ = r · w3b = (w1a / w1b) · w3b
It becomes.

Therefore, the total uniaxial axle weight W at the first position P1, the second position P2, and the third position P3 takes an average value.
W = {(w1a + w1b) + (w2a ′ + w2b) + (w3a ′ + w3b)} / 3
= {(W1a + w1b) + (r · w2b + w2b) + (r · w3b + w3b)} / 3 (3)
It becomes.

As in the case of the prior art of FIG. 13 above, the standard deviations of the vibration noise signals received by the left and right tires are each “σ”. Then, the axial weight W1 = (w1a + w1b) at the first position P1, the axial weight W2 = (w2a ′ + w2b) at the second position P2, and the axial weight W3 = (w3a ′) at the third position P3. + W3b) includes random noise of standard deviation (2σ). Therefore, corresponding to Equation (15), the variation index S of the vibration noise signal in the axle weight W obtained by the simple average is
S = {(2σ) ² + (2σ) ² + (2σ) ² } ^1/2 / 3
= (4/3) ^1/2 σ = 1.155σ (16)
It becomes.

The attenuation rate R at this time is
R = (1.155σ) / (2σ) = 0.777 (17)
It becomes. This performance is the same as that of the axle weight measuring apparatus of FIG.

  Next, evaluation of the prior art in FIG. 18 will be described based on FIG.

  As shown in FIG. 15A corresponding to FIG. 18, two wheel load sensors 11a and 12b are arranged. The arrangement is two positions P1 and P2 separated along the traveling direction of the vehicle indicated by the arrow A on the vehicle traveling path. In the first position P1, the wheel load sensor 11a is disposed on the left side lane 40a of the vehicle travel path 40. At the second position P2, the wheel load sensor 12b is disposed on the lane right side portion 40b.

  The size of the wheel load measured by the wheel load sensor 11a on the left side lane 40a of the first position P1 is w1a, and the size of the wheel load measured by the wheel load sensor 12b on the right side 40b of the second position P2 is w2b. And

At the first position P1, the wheel load sensor is not arranged on the right side portion 40b of the lane. However, assuming that the wheel load sensor is arranged here, the wheel load sensor measured by the virtual wheel load sensor is used. Is estimated and is set as w1b ′. The wheel load sensor w1b 'measured by the wheel load sensor on the virtual lane right side 40b is the same as the wheel load w1a measured by the wheel load sensor 12b on the lane right side 40b.
w1b '= w1a
It is said.

The axial load W1 at the first position P1 is calculated from the left measurement wheel weight w1a and the right virtual measurement wheel weight w1b ′.
W1 = w1a + w1b ′ = 2w1a
It is said.

At the second position P2, the wheel load sensor is not disposed on the left side lane 40a of the lane, but it is assumed that the wheel load sensor is disposed here, and the wheel load sensor measured by the virtual wheel load sensor is used. Is estimated, and this is defined as w2a ′. The wheel load sensor w2a ′ measured by the wheel load sensor in the virtual lane left side 40a is the same as the wheel load w2b measured by the wheel load sensor 12b in the lane right side 40b.
w2a '= w2b
It is said.

The axial load W2 at the second position P2 is calculated from the left virtual wheel load w2a 'and the right wheel load w2b.
W2 = w2a ′ + w2b = 2w2b
It is said.

The obtained axle weight W of one axis is obtained by taking an average value at the first position P1 and the second position P2.
W = (W1 + W2) / 2 = (2w1a + 2w2b) / 2
= W1a + w2b …………… (18)
It becomes.

Corresponding to the equation (18), the vibration noise signal variation index S in the axle weight W obtained by the simple average is the same as the case where two axle load sensors are arranged.
S = {(2σ) ² + (2σ) ² } ^1/2 / 2 = 2 ^1/2 σ
= 1.414σ …………… (19)
It becomes.

The attenuation rate R at this time is
R = (1.414σ) / (2σ) = 0.707 (20)
It becomes. This performance is inferior to the axle weight measuring device of FIG. However, the cost is lower than the axle weight measuring apparatus of FIG. 11 using three axle load sensors.

  Note that the prior art shown in FIG. 15 has a restriction that the speed of the vehicle and the frequency of the vibration noise signal are within a specific range, and is not originally designed to be suitable for random noise.

  The evaluation of the measurement accuracy of the conventional axle weight measuring device has been completed as described above. Next, the arrangement of the plurality of wheel load sensors according to the embodiment of the present invention will be described.

<< 1 >> Arrangement Pattern 1: In the Case of Three Wheel Load Sensors As shown in FIG. 2A, the number of wheel load sensors used is three, 11a, 12b, and 13b. Three positions P1, P2, and P3 are defined at intervals along the traveling direction of the vehicle indicated by the arrow A of the vehicle traveling path 40. The intervals between these three positions P1, P2, and P3 may be equal to each other or may be different. At the first position P1, the first wheel load sensor 11a is arranged at the left side lane 40a of the vehicle travel path 40, and at the second position P2, the second wheel load sensor 12b is arranged at the right side lane 40b. The third wheel load sensor 13b is disposed on the right side portion 40b of the lane at the third position P3.

  In the manner of arrangement of these three wheel load sensors 11a, 12b, and 13b, all of them are different in position in the traveling direction of the vehicle traveling path 40 (P1, P2, P3), and the vehicle traveling path 40 It is arranged in a state of being divided into a lane left side 40a and a lane right side 40b in one lane. In other words, not all of the wheel load sensors are arranged only in the lane left side 40a, and all are not arranged only in the lane right side 40b, but they are always arranged in both the lane left side 40a and the lane right side 40b. I try to do it.

Placement pattern is [Left, Right, Right]
Besides,
[Left, Right, Left],
[Left, Left, Right]
When,
[Right, Left, Left],
[Right, Left, Right],
[Right, Right, Left]
The total number of patterns is 6. The first wheel load sensor at the most upstream position in the traveling direction is the wheel load sensor at the first position P1 in this example, which is disposed on the lane left side 40a. You may arrange | position to 40b.

  In this example, the number of wheel load sensors arranged in the lane left side 40a is 1, and the number of wheel load sensors arranged in the lane right side 40b is 2, but as shown in the above pattern change, Two units may be provided on the left side 40a, and one unit may be provided on the lane right side 40b. Further, the arrangement pattern of this example is [left, right, right], and the second wheel load sensor 12b and the third wheel load sensor 13b are continuously arranged in the same lane right side portion 40b. In the case of [Left, Left, Right] and [Right, Left, Left], they are continuously arranged on the same lane side. However, instead of this, the left lane portion 40a and the right lane portion 40b may be alternately arranged as [left, right, left], [right, left, right].

  The size of the wheel load measured by the first wheel load sensor 11a is set to w1a, the size of the wheel load measured by the second wheel load sensor 12b is set to w2b, and the size of the wheel load measured by the third wheel load sensor 13b is set. Is w3b.

Here, as shown in FIG. 2B, the wheel load ωb of the lane right side portion 40b is considered. The wheel load ωb of the right side lane 40b is obtained by adding the wheel load w2b measured by the second wheel load sensor 12b and the wheel load w3b measured by the third wheel load sensor 13b, and obtaining a simple average value of the addition result. Is. That is,
ωb = (w2b + w3b) / 2 (27)
It is. In FIG. 2B, 12b ′ represents a virtual wheel load sensor related to the synthesis of the second wheel load sensor 12b and the third wheel load sensor 13b.

As for the wheel load ωa of the lane left side 40a, only one of the first wheel load sensors 11a is arranged in the lane left side 40a.
ωa = w1a …………… (28)
It is. In FIG. 2B, 11a 'is the same as the first wheel load sensor 11a, but this is because there is only one wheel load sensor.

  Hereinafter, a method for calculating the random noise variation index S and the attenuation rate R in the measured value of the axle weight W and the measured value of the axle weight W will be described with reference to FIG.

The measured value of the axle weight W to be finally obtained in this example is the sum of the wheel load ωa of the lane left side 40a and the wheel load ωb of the lane right side 40b. That is,
W = ωa + ωb
= W1a + (w2b + w3b) / 2 ......... (29)
It becomes.

  The calculation unit 5 inputs the measurement wheel weights w1a, w2b, and w3b from the first to third wheel load sensors 11a, 12b, and 13b via the amplification unit 2, the A / D conversion unit 3, and the input / output unit 4, respectively. Then, the calculation of the above mathematical formulas (27) to (29) is performed to calculate the axle weight W of one axis to be finally obtained.

  Next, examination will be made based on the above formula (29).

  The vibration noise applied to the left or right wheel is regarded as random noise, and the standard deviation of the vibration noise signal superimposed on the load signal measured by the left or right wheel load sensor is σ. To do. The standard deviation of the first wheel load sensor 11a, the standard deviation of the second wheel load sensor 12b, and the standard deviation of the third wheel load sensor 13b are common, and the standard deviation is “σ”.

The standard deviation Σb corresponding to the wheel weight ωb, which is a simple average value of the measurement wheel weight w2b and the measurement wheel weight w3b, is an average value of the standard deviation σ of the measurement wheel weight w2b and the standard deviation σ of the measurement wheel weight w3b. Is
Σb = (σ ² + σ ² ) ^1/2 / 2 = (1/2) ^1/2 σ (30)
It can be expressed as. Here, “divide by 2” corresponds to “divide by 2” in Equation (27).

On the other hand, the standard deviation Σa corresponding to the wheel load ωa that is the measurement wheel weight w1a itself is the standard deviation σ of the measurement wheel weight w1a.
Σa = σ …………… (31)
It is. This corresponds to Equation (28).

The random noise variation index S in the measured value (= ωa + ωb) of the axle weight W obtained by adding the wheel load ωa and the wheel load ωb is a combination of the standard deviation Σa and the standard deviation Σb.
S = (Σa ² + Σb ² ) ^1/2
= {Σ ² + {(1/2) ^1/2 σ} ² } ^1/2
= (3/2) ^1/2 σ = 1.225σ (32)
The attenuation rate R at this time is
R = (1.225σ) / (2σ) = 0.613 (33)
It becomes.

  In the present embodiment of the present invention, the average value of the measured wheel weights is taken when obtaining the wheel weight, but when the axle weight is obtained from the left and right wheel weights, the average value is simply taken instead of the average value. In addition, when calculating the standard deviation, the average value of the standard deviation of each measurement wheel load is taken, but when determining the random noise variation index S in the axle weight W from the left and right standard deviations, it is synthesized instead of averaged. Yes (do not divide by 2).

  Comparison between this example and the prior art of FIGS. 11 and 13 to 15 is as follows.

  First, the prior art of FIG. 15 is too high with an attenuation factor R = 0.707, and the number of units used is two in the first place. It will not be.

  Next, although it is the prior art of FIG. 11, this is R = 0.777 and is lower than this example. However, the axle load sensor of FIG. 11 extends over almost the entire width of the vehicle travel path, which is too costly and is not a subject of comparison in this example.

  Next, in the prior art of FIG. 14, this is an attenuation factor R = 0.777, which is lower than this example, but the number of units used is four in the first place, and this example uses three units. Therefore, this is not a comparison target of this example.

  The prior art of FIG. 13 uses a wheel load sensor as a load sensor, and the number of units used is three, and the conditions are the same as in this example, and therefore is a comparison target of this example. Compared with the attenuation rate R = 0.707 of this prior art, the attenuation rate R = 0.613 of this example, therefore, this example is comparable in cost to the prior art of FIG. In terms of W measurement accuracy, accuracy has been improved.

<< 2 >> Arrangement pattern 2: In case of four wheel load sensors (part 1)
As shown in FIG. 3A, the number of wheel load sensors used is four, 11a, 12b, 13b, and 14b. Four positions P1, P2, P3, and P4 are defined at intervals along the traveling direction of the vehicle indicated by the arrow A of the vehicle traveling path 40. The intervals between these four positions P1, P2, P3, and P4 may be equal to each other or may be different. At the first position P1, the first wheel load sensor 11a is arranged at the left side lane 40a of the vehicle travel path 40, and at the second position P2, the second wheel load sensor 12b is arranged at the right side lane 40b. The third wheel load sensor 13b is disposed at the lane right side portion 40b at the third position P3, and the fourth wheel load sensor 14b is disposed at the lane right side portion 40b at the fourth position P4.

  In the arrangement of these four wheel load sensors 11a, 12b, 13b, 14b, all of them are different in position in the traveling direction of the vehicle traveling path 40 (P1, P2, P3, P4), and the lane It is arranged in a state of being divided into a left side portion 40a and a lane right side portion 40b.

Placement pattern is [Left, Right, Right, Right]
Besides,
[Right, Left, Right, Right],
[Right, Right, Left, Right],
[Right, Right, Right, Left]
When,
[Right, Left, Left, Left],
[Left, Right, Left, Left],
[Left, Left, Right, Left],
[Left, Left, Left, Right]
And the total number of patterns is 8. The matter common to these arrangement patterns is that one vehicle is in one of the lane left side 40a and the lane right side 40b, and 3 in the other.

  In this example, the number of wheel load sensors arranged in the lane left side 40a is 1, and the number of wheel load sensors arranged in the lane right side 40b is 3, but as shown in the above pattern change, Three units may be provided on the left side 40a and one unit on the lane right side 40b. Further, the arrangement pattern of this example is [left, right, right, right], and the second wheel load sensor 12b, the third wheel load sensor 13b, and the fourth wheel load sensor 14b are in the same lane right side. 40b is arranged continuously. There may be two consecutive cars, or the lane left side 40a and the lane right side 40b may be alternately arranged.

  The size of the wheel load measured by the first wheel load sensor 11a is set to w1a, the size of the wheel load measured by the second wheel load sensor 12b is set to w2b, and the size of the wheel load measured by the third wheel load sensor 13b is set. W3b, and the size of the wheel load measured by the fourth wheel load sensor 14b is w4b.

Here, as shown in FIG. 3B, the wheel load ωb of the lane right side portion 40b is considered. The wheel load ωb of the right side lane 40b is obtained by measuring a wheel load w2b measured by the second wheel load sensor 12b, a wheel load w3b measured by the third wheel load sensor 13b, and a wheel load w4b measured by the fourth wheel load sensor 14b. Addition is performed, and a simple average value of the addition result is obtained. That is,
ωb = (w2b + w3b + w4b) / 3 (34)
It is. In FIG. 3B, 12b 'represents a virtual wheel load sensor related to the synthesis of the second wheel load sensor 12b, the third wheel load sensor 13b, and the fourth wheel load sensor 14b.

As for the wheel load ωa of the lane left side 40a, only one of the first wheel load sensors 11a is arranged in the lane left side 40a.
ωa = w1a …………… (35)
It is. In FIG. 3B, 11a 'is the same as the first wheel load sensor 11a, but this is because there is only one wheel load sensor.

  Hereinafter, a method of calculating the random noise variation index S and the attenuation rate R in the measured value of the axle weight W and the measured value of the axle weight W will be described with reference to FIG.

In the present embodiment, the measurement value of the axle weight W to be finally obtained is the sum of the wheel load ωa of the lane left side 40a and the wheel load ωb of the lane right side 40b. That is,
W = ωa + ωb
= W1a + (w2b + w3b + w4b) / 3 (3)
It becomes.

  The calculation unit 5 receives the measurement wheel weights w1a, w2b, and w3b from the first to fourth wheel load sensors 11a, 12b, 13b, and 14b via the amplification unit 2, the A / D conversion unit 3, and the input / output unit 4, respectively. , W4b are input, and the above mathematical formulas (34) to (36) are calculated to calculate the axle weight W of one axis to be finally obtained.

  Next, examination will be made based on the above formula (36).

  The standard deviation of the first wheel load sensor 11a, the standard deviation of the second wheel load sensor 12b, the standard deviation of the third wheel load sensor 13b, and the standard deviation of the fourth wheel load sensor 14b are common. The standard deviation is “σ”.

The standard deviation Σb corresponding to the wheel weight ωb, which is a simple average value of the measurement wheel weight w2b, the measurement wheel weight w3b, and the measurement wheel weight w4b, is measured with the standard deviation σ of the measurement wheel weight w2b and the standard deviation σ of the measurement wheel weight w3b. The average value of the standard deviation σ of the wheel load w4b,
Σb = (σ ² + σ ² + σ ² ) ^1/2 / 3 = (1/3) ^1/2 σ (37)
It becomes. Here, “divide by 3” corresponds to “divide by 3” in Equation (34).

On the other hand, the standard deviation Σa corresponding to the wheel load ωa that is the measurement wheel weight w1a itself is the standard deviation σ of the measurement wheel weight w1a.
Σa = σ …………… (38)
It is. This corresponds to Equation (35).

The random noise variation index S in the measured value (= ωa + ωb) of the axle weight W obtained by adding the wheel load ωa and the wheel load ωb is a combination of the standard deviation Σa and the standard deviation Σb.
S = (Σa ² + Σb ² ) ^1/2
= [Σ ² + {(1/3) ^1/2 σ} ² ] ^1/2
= (4/3) ^1/2 σ = 1.155σ (39)
The attenuation rate R at this time is
R = (1.155σ) / (2σ) = 0.777 (40)
It becomes.

  A comparison between this example and the prior art of FIG. 14 is as follows. The prior art shown in FIGS. 11, 13, and 15 in which the number of load sensors used is different is out of comparison. The attenuation rate R of the prior art in FIG. 14 is 0.577, and this example has the same value. That is, even if all the wheel load sensors are arranged at different positions along the traveling direction of the vehicle traveling path 40, an attenuation factor R comparable to that of the prior art can be obtained. And since all the wheel load sensors can be arrange | positioned in a different position, the efficient construction of the wheel load sensor in the road surface of the vehicle travel path 40 becomes easier. Further, when two wheel load sensors are laid in a straight line at the same place on the left and right, a problem such as a road surface crack may occur, but such an inconvenience is unlikely to occur in this example.

<< 3 >> Arrangement pattern 3: In case of four wheel load sensors (part 2)
As shown to Fig.4 (a), the number of the wheel load sensors to be used is four, 11a, 12a, 13b, 14b. At the first position P1, the first wheel load sensor 11a is arranged at the left side lane 40a of the vehicle travel path 40, and at the second position P2, the second wheel load sensor 12a is arranged at the left side lane 40a. The third wheel load sensor 13b is disposed at the lane right side portion 40b at the third position P3, and the fourth wheel load sensor 14b is disposed at the lane right side portion 40b at the fourth position P4. The difference from FIG. 3A is that the second wheel load sensor 12a is arranged on the lane left side 40a.

  In the manner of arrangement of these four wheel load sensors 11a, 12a, 13b, and 14b, all of them differ from each other along the traveling direction of the vehicle indicated by the arrow A of the vehicle traveling path 40, and It is arranged in a state of being divided into a lane left side 40a and a lane right side 40b.

Placement pattern is [Left, Left, Right, Right]
Besides,
[Left, Right, Left, Right],
[Left, Right, Right, Left],
When,
[Right, Right, Left, Left],
[Right, Left, Right, Left],
[Right, Left, Left, Right]
The total number of patterns is 6. The matters common to these arrangement patterns are two in the lane left side 40a and two in the lane right side 40b.

  The arrangement pattern of this example is [left, left, right, right], and the first wheel load sensor 11a and the second wheel load sensor 12a are continuously arranged on the same lane left side 40a, and the third The wheel load sensor 13b and the fourth wheel load sensor 14b are continuously arranged in the same lane right side portion 40b. However, as described above, it may be considered that random noise is added to each wheel load sensor, so the arrangement of the wheel load sensors may be continuous with the second and third units, Alternatively, the lane left side 40a and the lane right side 40b may be alternately arranged.

  The size of the wheel load measured by the first wheel load sensor 11a is set to w1a, the size of the wheel load measured by the second wheel load sensor 12a is set to w2a, and the size of the wheel load measured by the third wheel load sensor 13b is set. W3b, and the size of the wheel load measured by the fourth wheel load sensor 14b is w4b.

Here, as shown in FIG. 4B, the wheel load ωa of the left lane portion 40a is considered. The wheel load ωa of the left side lane 40a is obtained by adding the wheel load w1a measured by the first wheel load sensor 11a and the wheel load w2a measured by the second wheel load sensor 12a, and obtaining a simple average value of the addition result. Is. That is,
ωa = (w1a + w2a) / 2 (41)
It is. In FIG. 4B, 11a ′ represents a virtual wheel load sensor related to the synthesis of the first wheel load sensor 11a and the second wheel load sensor 12a.

On the other hand, the wheel load ωb of the right side lane 40b is obtained by adding the wheel load w3b measured by the third wheel load sensor 13b and the wheel load w4b measured by the fourth wheel load sensor 14b, and obtaining a simple average value of the addition result. It is a thing. That is,
ωb = (w3b + w4b) / 2 (2)
It is. In FIG. 4B, 12b 'represents a virtual wheel load sensor related to the synthesis of the third wheel load sensor 13b and the fourth wheel load sensor 14b.

  Hereinafter, a method of calculating the random noise variation index S and the attenuation rate R in the measured value of the axle weight W and the measured value of the axle weight W will be described with reference to FIG.

In this example, the measured value of the axle weight W to be finally obtained is the sum of the wheel load ωa of the lane left side portion 40a and the wheel load ωb of the lane right side portion 40b. That is,
W = ωa + ωb
= (W1a + w2a) / 2 + (w3b + w4b) / 2
…………… (43)
It becomes.

  The calculation unit 5 receives the measurement wheel weights w1a, w2a, and w3b from the first to fourth wheel load sensors 11a, 12a, 13b, and 14b via the amplification unit 2, the A / D conversion unit 3, and the input / output unit 4, respectively. , W4b are input, and the above mathematical formulas (41) to (43) are calculated to calculate the axle weight W of one shaft to be finally obtained.

  Next, examination will be made based on the above formula (43).

  The standard deviation of the first wheel load sensor 11a, the standard deviation of the second wheel load sensor 12a, the standard deviation of the third wheel load sensor 13b, and the standard deviation of the fourth wheel load sensor 14b are the same. The standard deviation is “σ”.

The standard deviation Σa corresponding to the wheel weight ωa, which is a simple average value of the measurement wheel weight w1a and the measurement wheel weight w2a, is an average value of the standard deviation σ of the measurement wheel weight w1a and the standard deviation σ of the measurement wheel weight w2a.
Σa = (σ ² + σ ² ) ^1/2 / 2 = (1/2) ^1/2 σ (44)
It becomes. Here, “divide by 2” corresponds to “divide by 2” in Equation (41).

The standard deviation Σb corresponding to the wheel weight ωb, which is a simple average value of the measurement wheel weight w3b and the measurement wheel weight w4b, is an average value of the standard deviation σ of the measurement wheel weight w3b and the standard deviation σ of the measurement wheel weight w4b. Yes,
Σb = (σ ² + σ ² ) ^1/2 / 2 = (1/2) ^1/2 σ (45)
It becomes. Here, “divide by 2” corresponds to “divide by 2” in Equation (42).

The random noise variation index S in the measured value (= ωa + ωb) of the axle weight W obtained by adding the wheel load ωa and the wheel load ωb is a combination of the standard deviation Σa and the standard deviation Σb.
S = (Σa ² + Σb ² ) ^1/2
= [{(1/2) ^1/2 σ} ² + {(1/2) ^1/2 σ} ² ] ^1/2
= Σ …………… (46)
The attenuation rate R at this time is
R = σ / (2σ) = 0.5 (47)
It becomes.

  A comparison between this example and the prior art of FIG. 14 is as follows. In terms of cost, it is equivalent to the prior art. The attenuation rate R of the prior art in FIG. 14 is 0.577, and this example has a lower value. That is, when all the wheel load sensors are disposed at different positions along the traveling direction of the vehicle traveling path 40, and two vehicles are disposed on each of the lane left side portion 40a and the lane right side portion 40b, the conventional technology is used. A low attenuation factor R is obtained, and the attenuation effect is improved.

  And since all the wheel load sensors can be arrange | positioned in a different position, the efficient construction of the wheel load sensor in the road surface of the vehicle travel path 40 becomes easier. Further, when two wheel load sensors are laid in a straight line at the same place on the left and right, a problem such as a road surface crack may occur, but such an inconvenience is unlikely to occur in this example.

  4 and 3 are compared with the pattern of FIG. 3 in which one is arranged on one side and three on the other side, and two are arranged on one side and two are arranged on the other side. It can be said that the pattern No. 4 has a lower attenuation rate and is more preferable for improving the accuracy of measuring the axle weight W.

<< 4 >> Arrangement pattern 4: In case of five wheel load sensors (part 1)
As shown in FIG. 5A, the number of wheel load sensors used is five, 11a, 12a, 13b, 14b, and 15b. As shown in the case of four vehicles, the configuration in which only one vehicle is arranged in one lane cannot expect a small attenuation rate for the number of installed vehicles. Therefore, in this example, in the first position P1, the lane left side 40a The first wheel load sensor 11a is disposed, the second wheel load sensor 12a is disposed at the lane left side 40a at the second position P2, and the third wheel load sensor is disposed at the lane right side 40b at the third position P3. 13b is disposed, the fourth wheel load sensor 14b is disposed at the lane right side portion 40b at the fourth position P4, and the fifth wheel load sensor 15b is disposed at the lane right side portion 40b at the fifth position P5. .

  In the manner of arrangement of these five wheel load sensors 11a, 12a, 13b, 14b, 15b, all of them differ from each other along the traveling direction of the vehicle indicated by the arrow A of the vehicle traveling path 40, And it arrange | positions in the state divided into the lane left side part 40a and the lane right side part 40b.

Placement pattern is [Left, Left, Right, Right, Right]
Besides,
[Left, Right, Left, Right, Right],
[Left, Right, Right, Left, Right],
[Left, Right, Right, Right, Left],
[Right, Left, Left, Right, Right],
[Right, Left, Right, Left, Right],
[Right, Left, Right, Right, Left],
[Right, Right, Left, Left, Right],
[Right, right, left, right, left],
[Right, Right, Right, Left, Left]
And the total number of patterns is 10. The matters common to these arrangement patterns are that there are two cars on the left side lane 40a and three cars on the right side lane 40b.

  The arrangement pattern of this example is [left, left, right, right, right], and the first wheel load sensor 11a and the second wheel load sensor 12a are continuously arranged on the same lane left side 40a, The third wheel load sensor 13b, the fourth wheel load sensor 14b, and the fifth wheel load sensor 15b are continuously arranged in the same lane right side portion 40b. However, the second and third units may be continuous, the third and fourth units may be continuous, the fourth and fifth units may be continuous, Alternatively, the first, second, and third units may be continuous, the second, third, and fourth units may be continuous, and the third and fourth units. The fifth unit may be continuous. Alternatively, the lane left side 40a and the lane right side 40b may be alternately arranged.

  The size of the wheel load measured by the first wheel load sensor 11a is set to w1a, the size of the wheel load measured by the second wheel load sensor 12a is set to w2a, and the size of the wheel load measured by the third wheel load sensor 13b is set. Is w3b, the size of the wheel load measured by the fourth wheel load sensor 14b is w4b, and the wheel load measured by the fifth wheel load sensor 15b is w5b.

Here, as shown in FIG. 5B, the wheel load ωa of the left side lane 40a is considered. The wheel load ωa of the left side lane 40a is obtained by adding the wheel load w1a measured by the first wheel load sensor 11a and the wheel load w2a measured by the second wheel load sensor 12a, and obtaining a simple average value of the addition result. Is. That is,
ωa = (w1a + w2a) / 2 (48)
It is. In FIG. 5B, 11a ′ represents a virtual wheel load sensor related to the synthesis of the first wheel load sensor 11a and the second wheel load sensor 12a.

On the other hand, the wheel load ωb of the right side lane 40b is determined by the wheel load w3b measured by the third wheel load sensor 13b, the wheel load w4b measured by the fourth wheel load sensor 14b, and the wheel load w5b measured by the fifth wheel load sensor 15b. Are obtained, and a simple average value of the addition results is obtained. That is,
ωb = (w3b + w4b + w5b) / 3 (49)
It is. In FIG. 5B, 12b ′ represents a virtual wheel load sensor related to the synthesis of the third wheel load sensor 13b, the fourth wheel load sensor 14b, and the fifth wheel load sensor 15b.

  Hereinafter, a method of calculating the random noise variation index S and the attenuation rate R in the measured value of the axle weight W and the measured value of the axle weight W will be described with reference to FIG.

In this example, the measured value of the axle weight W to be finally obtained is the sum of the wheel load ωa of the lane left side portion 40a and the wheel load ωb of the lane right side portion 40b. That is,
W = ωa + ωb
= (W1a + w2a) / 2 + (w3b + w4b + w5b) / 3 (5)
It becomes.

  The calculation unit 5 receives the measurement wheel weights w1a and w2a from the first to fifth wheel load sensors 11a, 12a, 13b, 14b, and 15b via the amplification unit 2, the A / D conversion unit 3, and the input / output unit 4, respectively. , W3b, w4b, and w5b are input, and the calculations of the above formulas (48) to (50) are performed to calculate the axle weight W of one axis to be finally obtained.

  Next, examination will be made based on the above formula (50).

  The standard deviation of the first wheel load sensor 11a, the standard deviation of the second wheel load sensor 12a, the standard deviation of the third wheel load sensor 13b, and the standard deviation of the fourth wheel load sensor 14b are both the fifth wheel. The standard deviation of the load sensor 15b is also common, and the standard deviation is “σ”.

The standard deviation Σa corresponding to the wheel weight ωa, which is a simple average value of the measurement wheel weight w1a and the measurement wheel weight w2a, is an average value of the standard deviation σ of the measurement wheel weight w1a and the standard deviation σ of the measurement wheel weight w2a.
Σa = (σ ² + σ ² ) ^1/2 / 2 = (1/2) ^1/2 σ (51)
It is. Here, “divide by 2” corresponds to “divide by 2” in Equation (48).

The standard deviation Σb corresponding to the wheel weight ωb, which is a simple average value of the measurement wheel weight w3b, the measurement wheel weight w4b, and the measurement wheel weight w5b, is the standard deviation σ of the measurement wheel weight w3b and the standard deviation σ of the measurement wheel weight w4b. And the average value of the standard deviation σ of the measurement wheel weight w5b,
Σb = (σ ² + σ ² + σ ² ) ^1/2 / 3 = (1/3) ^1/2 σ (52)
It becomes. Here, “divide by 3” corresponds to “divide by 3” in Equation (49).

The random noise variation index S in the measured value (= ωa + ωb) of the axle weight W obtained by adding the wheel load ωa and the wheel load ωb is a combination of the standard deviation Σa and the standard deviation Σb.
S = (Σa ² + Σb ² ) ^1/2
= [{(1/2) ^1/2 σ} ² + {(1/3) ^1/2 σ} ² ] ^1/2
= (5/6) ^1/2 σ = 0.9131σ (53)
The attenuation rate R at this time is
R = 0.457 …………… (54)
It becomes.

<< 5 >> Arrangement pattern 5: In the case of five wheel load sensors (part 2)
As shown in FIG. 6A, the number of wheel load sensors used is five, 11a, 12a, 13a, 14b, and 15b. The arrangement pattern of these four wheel load sensors 11a, 12a, 13a, 14b, 15b is as follows:
[Left, Left, Left, Right, Right]
But besides this,
[Left, Left, Right, Left, Right],
[Left, Left, Right, Right, Left],
[Left, Right, Left, Left, Right],
[Left, Right, Left, Right, Left],
[Left, Right, Right, Left, Left],
[Right, Left, Left, Left, Right],
[Right, Left, Right, Left, Left],
[Right, right, left, left, left],
[Right, Left, Left, Right, Right]
And the total number of patterns is 10. The matters common to these arrangement patterns are that there are three vehicles in the lane left side portion 40a and two vehicles in the lane right side portion 40b.

In this case, the wheel load ωa of the lane left side 40a is
ωa = (w1a + w2a + w3a) / 3 (5)
It is. In FIG. 6B, 11a ′ represents a virtual wheel load sensor related to the synthesis of the first wheel load sensor 11a, the second wheel load sensor 12a, and the third wheel load sensor 13a.

The wheel load ωb on the right side lane 40b is
ωb = (w4b + w5b) / 2 (56)
It is. In FIG. 6B, 12b ′ represents a virtual wheel load sensor related to the synthesis of the fourth wheel load sensor 14b and the fifth wheel load sensor 15b.

The final measured axle weight W is:
W = ωa + ωb
= (W1a + w2a + w3a) / 3 + (w4b + w5b) / 2
…………… (57)
It becomes.

  The calculation unit 5 receives the measurement wheel weights w1a and w2a from the first to fifth wheel load sensors 11a, 12a, 13a, 14b, and 15b via the amplification unit 2, the A / D conversion unit 3, and the input / output unit 4, respectively. , W3a, w4b, and w5b are input, and the calculation of the above mathematical formulas (55) to (57) is performed to calculate the axle weight W of one axis to be finally obtained.

  Next, examination will be made based on the above formula (57).

The standard deviation Σa corresponding to the wheel load ωa, which is a simple average value of the measurement wheel weight w1a, the measurement wheel weight w2a, and the measurement wheel weight w3a,
Σa = (σ ² + σ ² + σ ² ) ^1/2 / 3 = (1/3) ^1/2 σ (58)
It becomes. Here, “divide by 3” corresponds to “divide by 3” in Equation (55).

Further, the standard deviation Σb corresponding to the wheel load ωb, which is a simple average value of the measurement wheel weight w4b and the measurement wheel weight w5b, is
Σb = (σ ² + σ ² ) ^1/2 / 2 = (1/2) ^1/2 σ (59)
It becomes. Here, “divide by 2” corresponds to “divide by 2” in Equation (56).

The random noise variation index S in the measured value (= ωa + ωb) of the axle weight W obtained by adding the wheel load ωa and the wheel load ωb is a combination of the standard deviation Σa and the standard deviation Σb.
S = (Σa ² + Σb ² ) ^1/2
= [{(1/3) ^1/2 σ} ² } ^1/2 + {(1/2) ^1/2 σ} ² ] ^1/2
= (5/6) ^1/2 σ = 0.9131σ (60)
The attenuation rate R at this time is
R = 0.457 …………… (61)
It becomes. This is the same as in the case of FIG.

<< 6 >> Arrangement pattern 6: In the case of five wheel load sensors (part 3)
The arrangement pattern in FIG. 7A is [left, right, left, right, right], which is the second of the arrangement pattern group (part 1) already described.

In this case, the wheel load ωa of the lane left side 40a is
ωa = (w1a + w3a) / 2 (62)
It is. In FIG. 7B, 11a ′ represents a virtual wheel load sensor related to the synthesis of the first wheel load sensor 11a and the third wheel load sensor 13a.

The wheel load ωb on the right side lane 40b is
ωb = (w2b + w4b + w5b) / 3 (63)
It is. In FIG. 7B, 12b ′ represents a virtual wheel load sensor related to the synthesis of the second wheel load sensor 12b, the fourth wheel load sensor 14b, and the fifth wheel load sensor 15b.

The measured value of axle weight W in this case is
W = (w1a + w3a) / 2 + (w2b + w4b + w5b) / 3
…………… (64)
It becomes.

  The calculation unit 5 receives the measurement wheel weights w1a and w2b from the first to fifth wheel load sensors 11a, 12b, 13a, 14b, and 15b via the amplification unit 2, the A / D conversion unit 3, and the input / output unit 4, respectively. , W3a, w4b, w5b are input, and the calculation of the above formula (64) is performed to calculate the axle weight W of one axis to be finally obtained.

The random noise variation index S in the measured value (= ωa + ωb) of the axle weight W obtained by adding the wheel load ωa and the wheel load ωb is:
S = (Σa ² + Σb ² ) ^1/2
= [{(Σ ² + σ ² ) ^1/2 / 2} ² + {(σ ² + σ ² + σ ² ) ^1/2/3 } ² ] ^1/2
= (5/6) ^1/2 σ = 0.9131σ …………… (65)
The attenuation rate R at this time is
R = 0.457 ............... (66)
It becomes. This is also the same as in the case of FIG.

  An example of the arrangement patterns 4, 5, 6 is compared with the prior art shown in FIG.

  Since the comparison is based on five vehicles, illustration is omitted as a comparison target, but in FIG. 14, a fourth wheel load sensor 14b is added to the right side of the lane 40b and further to the right side of the third wheel load sensor 13b. Consider a case where the total number of units is five. It is assumed that the first wheel load sensor 11a in the lane left side portion 40a and the first wheel load sensor 11b in the lane right side portion 40b are at the same position P1 in the length direction of the vehicle travel path.

W = {(w1a + w1b) + (w2b + r · w2b) + (w3b + r · w3b) + (w4b + r · w4b)} / 4 (6)
It becomes. At this time, the variation index S of the vibration noise signal in the axle weight W obtained by the simple average is
S = {(2σ) ² + (2σ) ² + (2σ) ² + (2σ) ² } ^1/2 / 4
= Σ ………… (68)
The attenuation rate R is
R = σ / (2σ) = 0.5 (69)
It becomes. This does not reach the noise attenuation effect in the case of the five units according to the embodiment of the present invention.

  In the case of the arrangement patterns 4, 5, and 6, the attenuation rate R = 0.457, which is lower than that of the comparative example in which one unit is added to the conventional technique of FIG. 14 described above. That is, all the wheel load sensors are disposed at different positions along the traveling direction of the vehicle traveling path 40, and two are disposed on one of the lane left side 40a and the lane right side 40b, and three are disposed on the other. In this case, an attenuation rate R lower than that of the comparative example is obtained, and the attenuation effect is improved.

  And since all the wheel load sensors can be arrange | positioned in a different position, the efficient construction of the wheel load sensor in the road surface of the vehicle travel path 40 becomes easier. Further, when two wheel load sensors are laid in a straight line at the same place on the left and right, a problem such as a road surface crack may occur, but such an inconvenience is unlikely to occur in this example.

<< 7 >> Arrangement Pattern 7: Case of Six Wheel Load Sensors (Part 1)
As shown in FIG. 8A, the number of wheel load sensors used is six, 11a, 12a, 13a, 14b, 15b, and 16b. At the first position P1, the first wheel load sensor 11a is arranged at the lane left side 40a, at the second position P2, the second wheel load sensor 12a is arranged at the lane left side 40a, and at the third position P3. The third wheel load sensor 13a is arranged at the left side lane 40a, the fourth wheel load sensor 14b is arranged at the right side lane 40b at the fourth position P4, and the third wheel load sensor 14b is arranged at the fifth side P4 at the fifth position P5. No. 5 wheel load sensor 15b is arranged, and the sixth wheel load sensor 16b is arranged on the right side portion 40b of the lane at the sixth position P6.

  In the arrangement of these six wheel load sensors 11a, 12a, 13a, 14b, 15b, 16b, all of them are different from each other in the traveling direction of the vehicle indicated by the arrow A of the vehicle traveling path 40, And it arrange | positions in the state divided into the lane left side part 40a and the lane right side part 40b.

Placement pattern is [Left, Left, Left, Right, Right, Right]
Besides,
[Left, Left, Right, Left, Right, Right],
[Left, Left, Right, Right, Left, Right],
[Left, Left, Right, Right, Right, Left],
[Left, Right, Left, Left, Right, Right],
[Left, Right, Left, Right, Left, Right],
[Left, Right, Left, Right, Right, Left],
[Left, Right, Right, Left, Right, Left],
[Left, Right, Right, Left, Left, Right],
[Left, Right, Right, Right, Left, Left],
When,
[Right, Left, Left, Left, Right, Right],
[Right, Left, Left, Right, Left, Right],
[Right, Left, Left, Right, Right, Left],
[Right, Left, Right, Left, Left, Right],
[Right, Left, Right, Left, Right, Left],
[Right, Left, Right, Right, Left, Left],
[Right, Right, Left, Right, Left, Left],
[Right, right, left, left, right, left],
[Right, Right, Left, Left, Left, Right],
[Right, Right, Right, Left, Left, Left]
And the total number of patterns is 20. The matters common to these arrangement patterns are three in the lane left side 40a and three in the lane right side 40b.

In the case of FIG. 8, the wheel load ωa of the lane left side 40a is
ωa = (w1a + w2a + w3a) / 3 (3) (70)
It is. In FIG. 8B, 11a ′ represents a virtual wheel load sensor related to the synthesis of the first wheel load sensor 11a, the second wheel load sensor 12a, and the third wheel load sensor 13a.

The wheel load ωb on the right side lane 40b is
ωb = (w4b + w5b + w6b) / 3 (1)
It is. In FIG. 8B, 12b 'represents a virtual wheel load sensor related to the synthesis of the fourth wheel load sensor 14b, the fifth wheel load sensor 15b, and the sixth wheel load sensor 16b.

The final measured axle weight W is:
W = ωa + ωb
= (W1a + w2a + w3a) / 3 + (w4b + w5b + w6b) / 3 (72)
It becomes.

  The calculation unit 5 receives the measurement wheel weight w1a from the first to sixth wheel load sensors 11a, 12a, 13a, 14b, 15b, and 16b via the amplification unit 2, the A / D conversion unit 3, and the input / output unit 4, respectively. , W2a, w3a, w4b, w5b, w6b are input, and the above formulas (70) to (72) are calculated to calculate the axle weight W of one axis to be finally obtained.

  Next, examination will be made based on the above formula (72).

The standard deviation Σa corresponding to the wheel load ωa, which is a simple average value of the measurement wheel weight w1a, the measurement wheel weight w2a, and the measurement wheel weight w3a,
Σa = (σ ² + σ ² + σ ² ) ^1/2 / 3 = (1/3) ^1/2 σ (73)
It becomes. Here, “divide by 3” corresponds to “divide by 3” in Equation (70).

The standard deviation Σb corresponding to the wheel load ωb, which is a simple average value of the measurement wheel weight w4b, the measurement wheel weight w5b, and the measurement wheel weight w6b,
Σb = (σ ² + σ ² + σ ² ) ^1/2 / 3 = (1/3) ^1/2 σ (74)
It becomes. Here, “divide by 3” corresponds to “divide by 3” in Equation (71).

The random noise variation index S in the measured value (= ωa + ωb) of the axle weight W obtained by adding the wheel load ωa and the wheel load ωb is a combination of the standard deviation Σa and the standard deviation Σb.
S = (Σa ² + Σb ² ) ^1/2
= [{(1/3) ^1/2 σ} ² + {(1/3) ^1/2 σ} ² ] ^1/2
= (2/3) ^1/2 σ = 0.816σ (75)
The attenuation rate R at this time is
R = 0.408 ......... (76)
It becomes.

<< 8 >> Arrangement pattern 8: In the case of six wheel load sensors (part 2)
The arrangement pattern of FIG. 9A is [Left, Right, Left, Right, Left, Right], which is the sixth of the arrangement pattern group of (Part 1) already described.

In this case, the wheel load ωa of the lane left side 40a is
ωa = (w1a + w3a + w5a) / 3 (3) (77)
It is. In FIG. 9B, 11a ′ represents a virtual wheel load sensor related to the synthesis of the first wheel load sensor 11a, the third wheel load sensor 13a, and the fifth wheel load sensor 15a.

The wheel load ωb on the right side lane 40b is
ωb = (w2b + w4b + w6b) / 3 (8)
It is. In FIG. 9B, 12b 'represents a virtual wheel load sensor related to the synthesis of the second wheel load sensor 12b, the fourth wheel load sensor 14b, and the sixth wheel load sensor 16b.
The final measured axle weight W is:
W = ωa + ωb
= (W1a + w3a + w5a) / 3 + (w2b + w4b + w6b) / 3 (79)
It becomes. This mathematical formula (79) has the same result as the mathematical formula (72) in the case of FIG.

  The calculation unit 5 receives the measurement wheel weight w1a from the first to sixth wheel load sensors 11a, 12b, 13a, 14b, 15a and 16b via the amplification unit 2, the A / D conversion unit 3 and the input / output unit 4, respectively. , W2b, w3a, w4b, w5a, w6b are input, and the above formulas (77) to (79) are calculated to calculate the axle weight W of one axis to be finally obtained.

The standard deviation Σa corresponding to the wheel load ωa and the standard deviation Σb corresponding to the wheel load ωb are the same as (No. 1),
Σa = (σ ² + σ ² + σ ² ) ^1/2 / 3 = (1/3) ^1/2 σ (80)
It becomes. Here, “divide by 3” corresponds to “divide by 3” in Equation (77).

Σb = (σ ² + σ ² + σ ² ) ^1/2 / 3 = (1/3) ^1/2 σ (81)
It becomes. Here, “divide by 3” corresponds to “divide by 3” in Equation (78).

The random noise variation index S and the attenuation rate R in the measured value (= ωa + ωb) of the axle weight W obtained by adding the wheel load ωa and the wheel load ωb are the same as in the case of FIG.
S = (Σa ² + Σb ² ) ^1/2 = (2/3) ^1/2 σ
= 0.816σ …………… (82)
R = 0.408 ............... (83)
It becomes.

<< 9 >> Arrangement Pattern 9: Six Wheel Load Sensors (Part 3)
As shown in FIG. 10A, the number of wheel load sensors used is six, 11a, 12a, 13b, 14b, 15b, and 16b. At the first position P1, the first wheel load sensor 11a is arranged at the lane left side 40a, at the second position P2, the second wheel load sensor 12a is arranged at the lane left side 40a, and at the third position P3. A third wheel load sensor 13b is disposed at the right lane portion 40b, a fourth wheel load sensor 14b is disposed at the lane right portion 40b at the fourth position P4, and a third wheel load sensor 14b is disposed at the fifth position P5. No. 5 wheel load sensor 15b is arranged, and the sixth wheel load sensor 16b is arranged on the right side portion 40b of the lane at the sixth position P6.

  In the arrangement of the six wheel load sensors 11a, 12a, 13b, 14b, 15b, and 16b, all of them are different from each other along the vehicle traveling direction indicated by the arrow A of the vehicle traveling path 40. And it is arranged in a state of being divided into a lane left side 40a and a lane right side 40b.

Placement pattern is [Left, Left, Right, Right, Right, Right]
Besides,
[Left, Right, Left, Right, Right, Right],
[Left, Right, Right, Left, Right, Right],
[Left, Right, Right, Right, Left, Right],
[Left, Right, Right, Right, Right, Left],
[Right, Left, Left, Right, Right, Right],
[Right, Left, Right, Left, Right, Right],
[Right, Left, Right, Right, Left, Right],
[Right, Left, Right, Right, Right, Left],
[Right, Right, Left, Left, Right, Right],
[Right, Right, Left, Right, Left, Right],
[Right, Right, Left, Right, Right, Left],
[Right, right, right, left, left, right],
[Right, right, right, left, right, left],
[Right, Right, Right, Right, Left, Left]
When,
[Right, Right, Left, Left, Left, Left],
[Right, Left, Right, Left, Left, Left],
[Right, Left, Left, Right, Left, Left],
[Right, Left, Left, Left, Right, Left],
[Right, Left, Left, Left, Left, Right],
[Left, Right, Right, Left, Left, Left],
[Left, Right, Left, Right, Left, Left],
[Left, Right, Left, Left, Right, Left],
[Left, Right, Left, Left, Left, Right],
[Left, Left, Right, Right, Left, Left],
[Left, Left, Right, Left, Right, Left],
[Left, Left, Right, Left, Left, Right],
[Left, Left, Left, Right, Right, Left],
[Left, Left, Left, Right, Left, Right],
[Left, Left, Left, Left, Right, Right]
And the total number of patterns is 30. A matter common to these arrangement patterns is that there are two vehicles on either the lane left side portion 40a and the lane right side portion 40b and four on the other side.

In the case of FIG. 10, the wheel load ωa of the lane left side 40a is
ωa = (w1a + w2a) / 2 (84)
It is. In FIG. 10B, 11a 'represents a virtual wheel load sensor related to the synthesis of the first wheel load sensor 11a and the second wheel load sensor 12a.

The wheel load ωb on the right side lane 40b is
ωb = (w3b + w4b + w5b + w6b) / 4 (5)
It is. In FIG. 10B, reference numeral 12b ′ denotes a virtual wheel load related to the synthesis of the third wheel load sensor 13b, the fourth wheel load sensor 14b, the fifth wheel load sensor 15b, and the sixth wheel load sensor 16b. Represents a sensor.

The final measured axle weight W is:
W = ωa + ωb
= (W1a + w2a) / 2 + (w3b + w4b + w5b + w6b) / 4
………… (86)
It becomes.

  The calculation unit 5 receives the measurement wheel weight w1a from the first to sixth wheel load sensors 11a, 12a, 13b, 14b, 15b, and 16b via the amplification unit 2, the A / D conversion unit 3, and the input / output unit 4, respectively. , W2a, w3b, w4b, w5b, w6b are input, and the above formulas (84) to (86) are calculated to calculate the axle weight W of one axis to be finally obtained.

  Next, examination will be made based on the above formula (86).

The standard deviation Σa corresponding to the wheel load ωa, which is a simple average value of the measurement wheel weight w1a and the measurement wheel weight w2a, is
Σa = (σ ² + σ ² ) ^1/2 / 2 = (1/2) ^1/2 σ (87)
It becomes. Here, “divide by 2” corresponds to “divide by 2” in Equation (84).

Further, the standard deviation Σb corresponding to the wheel load ωb, which is a simple average value of the measurement wheel weight w3b, the measurement wheel weight w4b, the measurement wheel weight w5b, and the measurement wheel weight w6b,
Σb = (σ ² + σ ² + σ ² + σ ² ) ^1/2 / 4
= (1/4) ^1/2 σ …………… (88)
It becomes. Here, “divide by 4” corresponds to “divide by 4” in Equation (85).

The random noise variation index S in the measured value (= ωa + ωb) of the axle weight W obtained by adding the wheel load ωa and the wheel load ωb is a combination of the standard deviation Σa and the standard deviation Σb.
S = (Σa ² + Σb ² ) ^1/2
= [{(1/2) ^1/2 σ} ² + {(1/4) ^1/2 σ} ² ] ^1/2
= (3/4) ^1/2 σ = 0.866σ (89)
The attenuation rate R at this time is
R = 0.433 (90)
It becomes.

  An example of the arrangement patterns 7, 8, and 9 is compared with the prior art shown in FIG.

  Since the comparison is based on six units, illustration is omitted as a comparison target, but in FIG. 14, two wheel load sensors 14b and 15b are additionally arranged on the right side of the lane 40b and further on the right side of the wheel load sensor 13b. Consider a case where the total number is six. It is assumed that the wheel load sensor 11a of the lane left side 40a and the wheel load sensor 11b of the lane right side 40b are at the same position P1 in the length direction of the vehicle travel path.

W = {(w1a + w1b) + (w2b + r · w2b) + (w3b + r · w3b) + (w4b + r · w4b) + (w5b + r · w5b)} / 5 (91)
It becomes. At this time, the variation index S of the vibration noise signal in the axle weight W obtained by the simple average is
S = {(2σ) ² + (2σ) ² + (2σ) ² + (2σ) ² + (2σ) ² } ^1/2 / 5
= (20 ^1/2 / 5) σ = (2/5 ^1/2 ) σ = 0.894σ
…………… (92)
The attenuation rate R is
R = 0.894σ / (2σ) = 0.447 (93)
It becomes. This does not reach the noise attenuation effect in the case of the six units of the embodiment of the present invention.

  In the case of the arrangement patterns 7 and 8, the attenuation rate R = 0.408, and in the example of the arrangement pattern 9, the attenuation rate R = 0.433. Has a low value. That is, all the wheel load sensors are arranged at different positions along the traveling direction of the vehicle on the vehicle traveling path 40, and three vehicles are arranged in one of the lane left side portion 40a and the lane right side portion 40b, and 3 in the other side. When the units are arranged, or when two units are arranged on one side and four units are arranged on the other side, an attenuation factor R lower than that of the prior art is obtained, and the noise attenuation effect is improved.

  And since all the wheel load sensors can be arrange | positioned in a different position, the efficient construction of the wheel load sensor in the road surface of the vehicle travel path 40 becomes easier. Further, when two wheel load sensors are laid in a straight line at the same place on the left and right, a problem such as a road surface crack may occur, but such an inconvenience is unlikely to occur in this example.

  8 and 9 are compared with FIG. 10 in comparison with the pattern of FIG. 10 in which there are two units on one side and four units on the other side, and three units on one side and three units on the other side. The arrangement patterns shown in FIGS. 8 and 9 have a lower attenuation rate and are more preferable for increasing the accuracy of measuring the axle weight W.

  As described above, in the embodiment of the present invention, when four or more wheel load sensors are provided and a plurality of wheel load sensors are arranged on both the left side and the right side of the lane, various vehicles are operated at various speeds. In the passing condition, the measurement accuracy of the axle weight measuring device of FIG. 11 that has been widely used in the past is not lower, the cost is lower than the method of FIGS. 13 and 14 that is a conventional technique using a wheel load sensor, and more The noise attenuation effect can be enhanced.

  As described above, in the present invention, the measurement accuracy of the axial load becomes higher than that of the prior art or equal to that of the prior art at the worst. Even in an equivalent case, in the case of the present invention, since all the wheel load sensors are arranged at different positions in the length direction of the vehicle travel path, efficient laying work of the wheel load sensors on the road surface of the vehicle travel path is possible. In addition to being easier, it is possible to avoid problems such as road surface cracks in the case where two wheel load sensors are laid in a straight line at the same left and right positions in the prior art.

  The present invention relates to an axle weight measuring device that measures the axle weight of a running vehicle, while advantageously promoting cost development against various frequency changes of vibration noise caused by various changes in vehicle type and running speed. This is useful as a technique for measuring axle weight with high noise attenuation effect.

2 Amplifying section 3 A / D conversion section 4 Input / output section 5 Calculation section 6 Storage section 7 Display section 8 Operation section / data input section 11, 12, 13, 14, 15, 16 Wheel load sensor 11a, 12a, 13a, 15a Wheel load sensor 12b, 13b, 14b, 15b, 16b arranged on the left side of the lane Wheel load sensor 11a 'arranged on the right side of the lane Virtual wheel load sensor 12b' related to the synthesis of a plurality of wheel load sensors on the left side of the lane Virtual wheel load sensor involved in the synthesis of a plurality of wheel load sensors on the right side of the lane 31 Axle 32, 33 Wheel 40 Vehicle travel path 40a Lane left side 40b Lane right side w1, w2, w3, w4, w5, w6 Measuring wheel Weight ωa Wheel weight on the left side of the lane ωb Wheel weight on the right side of the lane W Ultimate axle weight to be obtained σ Standard deviation of each measured wheel weight Σa Corresponding to the wheel weight ωa Standard deviation Σb Standard deviation corresponding to wheel load ωb S Variation index of vibration noise signal in axle weight R Damping rate

Claims (3)

Based on a plurality of wheel load sensors that are disposed on the vehicle travel path and measure the wheel weight, which is the weight of one wheel of the left and right wheels of the axle, and the measured wheel weights measured by each of the plurality of wheel load sensors. An axle weight measuring device comprising an arithmetic unit for calculating axle weight,
There are three or more wheel load sensors as the plurality of wheel load sensors, all of these three or more wheel load sensors are located at different positions along the traveling direction of the vehicle on the vehicle traveling path, and , One lane of the vehicle travel path is divided into a left side lane and a right side lane that are divided into right and left in the width direction.
Axle weight measuring device characterized by that. In the case where there are a plurality of wheel load sensors arranged on the left side of the lane, the arithmetic unit uses the average value of the measured wheel load by each of the plurality of wheel load sensors as the measured wheel weight of the left side of the lane. When the number of wheel load sensors arranged on the left side of the lane is one, the measurement wheel weight by the one wheel load sensor is used as the measurement wheel weight of the left side of the lane, while the right side of the lane When there are a plurality of wheel load sensors arranged, the average value of the measured wheel weights of the plurality of wheel load sensors is set as the measured wheel weight of the right side of the lane, and is arranged on the right side of the lane. When there is one wheel load sensor, the measurement wheel weight of the one wheel load sensor is used as the measurement wheel weight of the right side of the lane, and the measurement wheel weight of the left side of the lane and the measurement wheel weight of the right side of the lane. And the car To calculate the weight,
The axle weight measuring device according to claim 1. The plurality of wheel load sensors is four or more, and each of the plurality of wheel load sensors is disposed on the left side of the lane and the right side of the lane, respectively.
The axle weight measuring device according to claim 1 or 2.

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