JP5456433B2 - Wheel or axle weight measurement system - Google Patents

Description

  The present invention relates to a vehicle wheel or axle weight measurement system, and more particularly to a vehicle wheel or axle weight measurement system that measures the weight of a running vehicle.

  Conventionally, there are systems disclosed in Patent Documents 1 and 2 as systems for measuring the wheel weight or axle weight of a running vehicle.

  In the technique of Patent Document 1, the weighing platform is arranged at the same height as the road surface, and the length of the weighing platform in the vehicle passing direction is longer than the contact surface length of the wheel tire and shorter than the inter-axis distance of the vehicle. Is set. A load cell is installed at each corner of the weighing platform. In the technique of Patent Document 2, the weighing platform is installed at the same height as the road surface, and the length of the weighing platform in the vehicle passing direction is set to be shorter than the length of the contact surface of the wheel tire.

Japanese Patent Publication No.53-23099 JP-A 63-286724

  According to the technique of Patent Document 1, extremely accurate weight measurement is possible when the vehicle is stopped or very close to stopping, but a large weighing platform or many load cells are used. Cost. In addition, when the vehicle passes over the weighing platform at high speed, accurate weight measurement cannot be performed due to vibration noise caused by unevenness on the road surface or a spring by the suspension of the vehicle.

  According to the technique of Patent Document 2, the structure is simple and the cost can be reduced. However, if the speed changes when the vehicle passes over the weighing platform, the vehicle is stopped on the weighing platform. If it is in a state close to, the weight cannot be measured accurately. In addition, since the width of the weighing platform in the vehicle traveling direction is shorter than the width of the ground contact surface of the vehicle tire, the ground contact surface of the tire is in contact with not only the weighing platform but also the road surface. Like the influence of vibration noise.

  In order to solve the above problems, the applicant of the present application uses the technique disclosed in Patent Document 1 and the technique disclosed in Patent Document 2 to perform the measurement disclosed in Patent Document 1. One stand is provided, and a plurality of weighing stands disclosed in Patent Document 2 are installed on the road surface in the traveling direction of the vehicle. When the vehicle speed is low, only the measurement value by the weighing stand of Patent Literature 1 is adopted, When the speed of the vehicle becomes higher than a predetermined speed, it has been proposed to reduce the vibration noise component by statistical processing such as averaging the measured values of both weighing platforms.

  However, in the technique of Patent Document 2, since the tire load is divided into a weighing table and a road surface, and the weight is measured, the road surface near the weighing table is worn, and the upper surface of the weighing table is higher than the road surface. Then, compared to the case where the upper surface of the weighing table and the road surface coincide with each other, the load applied to the upper surface of the weighing table becomes larger, and the weight measurement value appears larger. Conversely, if sediment accumulates on the road surface in the vicinity of the weighing table and the upper surface of the weighing table is lower than the road surface, the load applied to the weighing table is reduced and the measured value appears smaller.

  Also, since the weight is measured including the process of the tire moving from the road surface to the upper surface of the weighing table, the tire ground contact surface continuously collides with the weighing table during the process of the tire moving to the upper surface of the weighing table, and the impact generated continuously. The load is added to the weight measurement and the weight cannot be measured accurately. In particular, when the upper surface of the weighing table and the road surface do not coincide with each other, the impact load increases and the weight cannot be measured more accurately.

  In addition, the difference in level between the top of the weighing platform and the road surface changes with the passage of time after the installation of the weighing platform, and the state where the weight measurement appears larger or smaller changes with time, The error due to impact load also changes over time.

  These problems are not improved even in the proposed technique.

  The present invention relates to a wheel or axle weight measurement system that measures the weight of a wheel or axle while the vehicle is running, and eliminates errors that change with time due to the difference in height between the weighing platform and the road surface. Objective.

The wheel / axle weight measuring system according to one aspect of the present invention includes a first measuring instrument. The first weighing instrument has a first weighing platform having a dimension longer than the length of the ground contact surface of the vehicle tire in the traveling direction of the vehicle, and the tire ground contact surface is not in contact with the road surface. Measure vehicle wheel or axle weight. At least one second weighing instrument has a second weighing platform having a dimension shorter than the length of the ground contact surface of the vehicle in the traveling direction of the vehicle, and the ground contact surface of the tire is in contact with the road surface. And measuring the axle or axle weight of the vehicle. The first and second weighing platforms are installed on substantially the same plane as the road surface, but the second weighing table may cause a height difference with the road surface over time. The first and second weighing platforms are arranged along the traveling direction of the vehicle, and the arrangement is made at a distance such that the tires do not ride on the first and second weighing tables at the same time. Error correction means, the vehicle is multiple weight measurements of a plurality of weight measurements of the first and second metering stage and second metering devices when passing over a plurality of times first meter A correction value is obtained based on the comparison result with, and an error peculiar to the weight measurement value of the second measuring instrument is corrected by this correction value . As a comparison result, for example, there are a case where a difference between the two is obtained and a ratio between both are obtained.

The error correction means is based on a comparison result of a plurality of latest weight measurement values of the first and second measuring instruments obtained when the vehicle passes the first and second weighing platforms a plurality of times. A correction value is obtained, and an error peculiar to the weight measurement value of the second measuring instrument can be automatically corrected by the correction value .

Further, the error correction means corrects an error inherent in the weight measurement value of the second weighing device , based on the speed of the vehicle.

  Further, the error correction means calculates a correction value by an addition value of a value obtained by multiplying a weight measurement value of the first weighing instrument by a first coefficient and a value obtained by multiplying the vehicle speed by a second coefficient. The first and second coefficients are calculated from the speed of the vehicle, the weight measurement value of the first weighing instrument, and the difference between the weight measurement values of the first and second weighing instruments. Can do.

Further, the error correction means may correct an error peculiar to the weight measurement value of the second measuring device based on the speed of the vehicle and the axle or wheel weight.

The wheel or axle weight measurement system according to another aspect of the present invention includes the first and second weighing instruments as in the above aspect, and the first and second weighing platforms are arranged in the same manner as described above. Further, the error correction means determines whether the speed of the vehicle and the weight measurement value of the first or second weighing instrument correspond to a predetermined rank, and based on the correction value corresponding to the corresponding rank, Correct the weight measurement value of the measuring instrument of 2 . Each time the vehicle passes through the first and second weighing platforms, the correction value is the first and second in the rank to which the speed at that time and the weight measurement values of the first and second weighing instruments belong. It is the difference of the average value of the accumulated value which accumulated the weight measurement value of the measuring instrument .

  As described above, according to the present invention, even if a road surface change in the vicinity of the weighing platform of this system occurs as a result of being used over a long period of time, the weight measurement value of the second weighing instrument that is greatly affected by Are measured on the first weighing platform and corrected by the weight measurement value of the first weighing instrument that is not affected by changes in the road surface. The error of the weight measurement value can be automatically corrected.

It is a block diagram of the wheel and axle weight measurement system of one embodiment of the present invention. It is a figure which shows the change of the output signal of each measuring instrument as a tire passes on the measuring instrument of the wheel and axle weight measuring system of FIG. It is the front view which shows the structure of the 2nd measuring device of the wheel and axle weight measuring system of FIG. 1, a top view, a side view, and the front view of the state which mounted the tire on the 2nd measuring device. It is explanatory drawing of the measurement principle in the 2nd measuring device of the wheel and axle weight measurement system of FIG. It is a figure which shows a part of flowchart of the wheel and axle weight measurement system of FIG. It is a figure which shows the flowchart following the flowchart of FIG. It is a figure which shows the flowchart following the flowchart of FIG. It is a figure which shows the flowchart following the flowchart of FIG.

  In the wheel / axle weight measuring system of one embodiment of the present invention, it is assumed that a vehicle not shown on the road surface 2 travels in the direction of the arrow as shown in FIG. A first measuring instrument 4 is installed on the road surface 2. The weighing instrument 4 has a weighing platform 6 as shown in FIG. 2 (a), and a plurality of, for example, two first weight value measuring means, for example, two vehicles on the lower surface of the weighing platform 6 are provided. The load cell 8a supports, and a plurality of, for example, two first weight value measuring means, for example, the load cell 8b, support the exit side of the vehicle on the lower surface of the weighing platform 6. Two weighing platforms 6 are provided in the width direction of the road surface 2 in order to individually measure the weights of two wheels attached to the same shaft of the vehicle. In addition, when measuring the weight of two wheels attached to one axle of the vehicle by the first measuring instrument 4, that is, the weight of the axle simultaneously, the two wheels in the width direction of the road surface 2 are placed simultaneously. One weighing platform 6 having a width dimension is used. As shown in FIG. 2A, these weighing platforms 6 have a length dimension L in the traveling direction of the vehicle that is larger than the length L ′ in the traveling direction of the vehicle on the road surface 2 of the tire 9 of the vehicle. ing.

  The output signals of the load cells 8a and 8b are amplified by the amplifier 10, digitally converted by the A / D converter 12, and supplied to the processing means, for example, the arithmetic circuit 14. The arithmetic circuit 14 includes, for example, a CPU, a memory, an input / output circuit, and the like.

  A plurality of, for example, two second measuring instruments 16 and 18 are provided at intervals on the road surface 2 away from the first measuring instrument 4 in the traveling direction of the vehicle. The second measuring instruments 16 and 18 have the same structure, and only the second measuring instrument 16 will be described. As shown in FIG. 3B, the second measuring instrument 16 has a length in the traveling direction of the vehicle of L2 or less, and the length in the width direction of the road surface 2 is L2 ′ as shown in FIG. A plurality of, for example, four second weight value measuring means, such as four load cells 22a, 22b, 22c, and 22d, arranged in the width direction of the road surface 2 are arranged on the load cells 22a to 22d. The weighing table 24 having a length L2 along the traveling direction of the vehicle is arranged. L2 is set to be shorter than the length L ′ of the ground contact surface of the tire 9 in the vehicle traveling direction. Therefore, even when the ground contact surface of the tire 9 is on the weighing table 24, the total load of the tire 9 is divided and applied to the road surface 2 and the weighing table 24 at a certain ratio.

  In addition, the distance between the two is set so that the tire 9 does not exist across the first measuring instrument 4 and the second measuring instrument 16, and the tire straddles between the second measuring instruments 16 and 18. The interval between them is set so that 9 does not exist. The upper surfaces of the weighing platforms 6 and 24 are installed so as to coincide with the road surface. However, the road surface in the vicinity of the weighing platforms 6 and 24 is worn due to frequent passing of the vehicle. As a result, the upper surfaces of the weighing platforms 6 and 24 are higher than the road surface, and earth and sand are placed on the weighing platforms 6 and 24. The road surface may be higher than the upper surfaces of the weighing platforms 6 and 25.

  When individually measuring the weights of two wheels provided on one shaft of the vehicle, the outputs of the load cells 22a and 22b are synthesized for one wheel and the load cells 22c and 22d are used for the other wheel. Synthesize the output of. When measuring the weights of two wheels simultaneously, the outputs of the load cells 22a to 22d are all combined. The output signals of these load cells 22 a to 22 d are amplified by the amplifier 10, digitally converted by the A / D converter 12, and supplied to the arithmetic circuit 14.

  Processing of the output signal of the first measuring instrument 4 performed in the arithmetic circuit 14 will be described with reference to FIGS. 2 (a) and 2 (b). The load signal in FIG. 2 is an output signal of the load cells 8a and 8b corresponding to the movement of the tire center position. In addition, although the following description is a case where the weight of one wheel is measured, on the basis of the following description, measuring the weight (axial weight) of two wheels provided on one shaft, It will be obvious to those skilled in the art. The first weighing device 4 can measure in two modes, a dynamic weight measurement mode and a static weight measurement mode.

  In order to measure in both of these modes, the tire 9 is completely on the weighing platform 6, the position p 1 immediately after the contact between the ground contact surface of the tire 9 and the road surface 2 is lost, and the tire that has entered the weighing platform 6. A position p2 that contacts the road surface 2 when 9 moves forward on the weighing platform 6 and further advances is determined on the output signals of the load cells 8a and 8b. When the distance between the positions p1 and p2 is L11, it is possible to lengthen the time that the tire 9 stays in the L11 section on the weighing platform 6 and before the ground contact surface of the tire that proceeds to the weighing platform 6 touches the weighing platform 6. In addition, the length L1 of the weighing platform 6 and the positions p1 and p2 are set so that the tire 9 is separated from L11.

  The positions p1 and p2 are defined as positions where a predetermined condition is established between the ratio of the output signals of the load cells 8a and 8b and a predetermined constant value. That is, assume that the output signal of the load cell 8a is w1, the output signal of the load cell 8b is w2, and these are sampled at the same timing at the time interval T to obtain w1 (k) and w2 (k) as sampling weight measurement values. The ratio Rw is obtained by w1 (k) / w2 (k). Then, w1 (k) at the position p1 is defined as w11 (k), w2 (k) is defined as w21 (k), and the predetermined value is defined as w11 (k) / w21 (k) = f1, When the ratio Rw becomes larger than f1 and then decreases from f1, it is determined that the position p1 has been reached.

  Similarly, w1 (k) at position p2 is set to w12 (k), w2 (k) is set to w22 (k), w22 (k) / w12 (k) = f2, and after position p1 is determined, Rw The time when becomes larger than f2 is defined as the time when the position p2 is reached.

  Thus, if the positions p1 and p2 are defined by the ratio of w1 (k) and w2 (k), these positions are not affected by the size of the wheel weight.

By obtaining w1 (k) and w2 (k) between the positions p1 and p2, the sampling weight value wi of the tire 9 is
wi = w1 (k) + w2 (k)
The weight measurement value W1 of the tire 9 is W1 = Σwi / N, where N is the number of sampling weight values between the positions p1 and p2.
Sought by. Obtaining W1 in this way is called a dynamic gravity measurement mode.

The dynamic weight measurement mode is based on the premise that the vehicle passes smoothly on the weighing platform 6. However, the vehicle may travel such that the vehicle stops while the tire 9 is on the weighing platform 6 or the tire 9 passes over the weighing platform 6 at a very low speed. The sampling time interval T can be set at a short time interval of several milliseconds in order to attenuate noise superimposed on w1 (k) and w2 (k) and to measure Rw with high sensitivity and accuracy. Many. Therefore, in the case as described above, Σwi takes a very large value. Therefore, in order to start counting from the time point when the position p1 is detected, a counter operation is started, and a timer T1 that is incremented at every sampling time interval T is provided. When the count value Ts of this timer becomes equal to or greater than a predetermined Nm , Wi is stopped and the weight measurement value W1s is
W1s = ΣWi / Nm
Ask for. Obtaining W1s in this way is called a static weight measurement mode.

  It should be noted that Nm is set to a value that can be sufficiently attenuated by averaging as described above even if a low-frequency noise signal is superimposed on w1 (k) and w2 (k).

  As is clear from the above description, the weight measurement mode in the first measuring instrument 4 is automatically switched according to the traveling speed state of the vehicle.

  Processing of the output signals of the second measuring devices 16 and 18 performed in the arithmetic circuit 14 will be described. In the following description, the weight of one wheel is measured, but it is known to those skilled in the art to measure the weight (axial weight) of two wheels provided on one shaft based on the following description. Is self-explanatory.

FIG. 4A shows the contact surface of the tire 9, where the contact width of the tire 9 is Ai, the distance that the tire 9 moves at every sampling time interval T is Di, and the load per unit area of the tire 9 is P. When the contact area is S, the total load W of the contact surface of the tire 9 is
W = P * S = P * Σ (Ai * Di)
It is. Assuming that the vehicle speed is V, the distance Di that the tire 9 moves at every sampling time interval T is Di = V * T in FIG.
It is. Since the contact length L ′ of the tire 9 is longer than the length L2 of the weighing platform of the second measuring devices 16 and 18, as described above, the load on the entire tire contact surface is applied to the portion L2 and the road surface 2. Assuming that the portion of the weighing platform length L2 of the second measuring devices 16, 18 receives a load with respect to the load W of the entire ground contact surface of the tire 9, the second measuring devices 16, 18 are The measurement value of the load received from the tire 9, that is, the weight measurement value Wi obtained by sampling the output signals of the second measuring devices 16 and 18, is shown in FIG.
Wi = P * Ai * L2
It is represented by If this is transformed,
P * Ai = Wi / L2
From the above equation for the total load W on the tire contact surface, the equation for the movement distance Di, and the equation for P * Ai, the total load W on the tire contact surface, which is the weight of the tire 9, is
W = P * S = P * Σ (Ai * Di) = Σ (P * Ai * Di) = Σ (P * Ai * V * T)
= Σ [(Wi * V * T) / L2] = (V * T / L2) ΣWi
It is calculated by the following formula. If the output signal of the second measuring devices 16 and 18 is w3, and the weight measurement value obtained by sampling the output signal at each time interval T is w3 (k),
W2 = (V * T / L2) Σw3 (k)
It is expressed. This measurement can accurately measure the weight of the tire 9 only when the vehicle is traveling at a constant speed V, and obtaining W2 in this way is called a dynamic weight measurement mode in the second weighing instrument. .

  As described above, in order to calculate W2, it is necessary to determine the start timing of ΣW3 (k) (positions p3 and p4 shown in FIG. 2B). For p3 and p4, a boundary weight Wf is determined in advance in the direction of load with respect to the output signal w3 (k) of the second weighing device 16 and 18, and after determining the position p2, w3 (k) exceeds wf. The time point is set to p3, and after the position p3 is determined and w3 (k) returns to the zero point, the time point when w3 (k) exceeds wf for the first time is set to p4.

  When the vehicle stops in a state where the tire 9 is present on the second weighing units 16 and 18, or the vehicle advances such that the tire passes on the weighing table at an extremely low speed, the value of Σw3 (k) is Become enormous. Therefore, timer counters T4 and T5 are provided, and when the points p3 or p4 are detected, the counters are counted at T4 and T5 at every sampling time interval T. When the count value exceeds the predetermined values Nm1 and Nm2, the weight measurement value Is stopped, and the dynamic weight measurement by the second weighing units 16 and 18 is stopped.

  Dynamic weight measurement at the second scales 16,18 requires the speed of the vehicle passing through the second scales 16,18. Further, as will be described later, the speed at which the vehicle passes through the second weighing units 16 and 18 is used to switch between the measurement with the first weighing unit 4 and the measurement with the second weighing units 16 and 18. To do. For this purpose, the arithmetic circuit 14 performs these speed measurements.

First, detection of the velocity V passing on the first measuring instrument 4 will be described. In the first weighing device 4, when the load cells 8a and 8b support the weighing table 6, the points qa and qb are shown in FIG. 2A, and the distance between the points qa and qb is A. The distance A1 between the position q1 corresponding to the position p1 on the output signal of the load cell 8a and the point qa is approximated when the output signals of the load cells 8a and 8b at the points qa and qb are peak and equal. By using f1 described above, approximately A1≈ (1 / f1) * A
Sought by. Similarly, the distance between the position q2 corresponding to the position p2 on the output signal of the load cell 8b and the point qb is also approximately obtained from f2 and A. Therefore, by setting the distance A between the load cells 8a and 8b and f1 and f2 in the arithmetic circuit 14, L11 (distance between the positions p1 and p2) shown in FIG. 2B is automatically calculated. Then, when the count at the timer counter T1 is started from the position p1 and stopped at the position p2, and the count value C1 is obtained, the vehicle speed V is
V = L11 / C1
Is calculated by

The detection of the speed V3 passing over the second measuring instrument 18 will be described. As the speed V3, the speed at which the vehicle passes from the center q0 of the weighing platform 6 of the first weighing instrument 4 to the input end q3 of the second weighing instrument 16 is used. This is because it is unlikely that the speed will change rapidly immediately before the tire 9 is placed on the weighing platform of the second weighing instrument 16. When the tire 9 reaches the point q0, the output signals w1 (k) and w2 (k) of the load cells 8a and 8b become equal. Therefore, the time when w1 (k) ≦ w2 (k) is first established is defined as q0 point. Further, the time when the tire 9 reaches the input end q3 of the second measuring instrument 16 substantially coincides with the position p3. Therefore, the timer counter T3 starts counting from the position p0, and V3 is set to V3 = V3 = V3 using the count value C3 when the position p3 is reached and the distance L31 between q0 and q3 set in advance. L31 / (C3 * T)
Detect as. T is the sampling time interval described above.

The detection of the velocity V4 passing over the second measuring instrument 18 will be described. The timer counter T3 continues counting until the position P4 is detected. If the distance L41 between q3 and q4 set in advance and the count value at the position P4 is C4, V4 is
V4 = L41 / [(C4-C3) * T]
Can be detected.

  There is a case where the vehicle stops or becomes close to the first measuring instrument 4 or is slow or fast.

  When the vehicle is stopped or close to it, rather than detecting the speed of the vehicle, the time that the vehicle stays on the first weighing platform 6 is detected, and if the stay time exceeds Nm * T described above, The weight measurement value W1s in the static weight measurement mode described above is set as the wheel weight measurement value. The weight measurement value W1s in the static weight measurement mode indicates that the vehicle is almost stopped and the amplitude of various noise signals included in the output signals of the first and second load cells 8a and 8b is basically small. Even if there is a noise signal, the noise signal can be smoothed by a sufficiently long sampling measurement time (Nm * T), so that it is not necessary to use a weight measurement value by the second measuring instruments 16 and 18.

  When the speed of the vehicle is slow relative to the first measuring instrument 4, even if the vehicle is running, if the vehicle is running at a low speed, the tire 9 is not in contact with the road surface 2 in the first measuring instrument 4. Since a certain amount of weight measurement time can be taken, a good weight measurement value W1 can be obtained. Moreover, even if shifting is performed during measurement, since one sampling weight measurement value represents the load of the tire 9, no error occurs in the measurement principle.

  Further, when the vehicle speed is higher than that of the first measuring instrument 4, the output signal of the load cells 8a and 8b of the first measuring instrument 4 includes an error component and an impact load due to a low-frequency noise signal generated by the spring of the vehicle. However, when the vehicle speed is high as described above, the measurement time (time to pass from position p1 to p2) is shortened and the number of samplings is reduced, so that the noise smoothing processing capability is low. Become. Accordingly, if only the weight measurement value of the first weighing device 4 is used, the error becomes large, so that in addition to the weight measurement value of the first weighing device 4, the weight measurement value W2 of the second weighing device 16, 18. , W3 is also used to obtain a weight measurement.

  As the vehicle speed increases, the amplitude of random noise and vibration noise gradually increases, and when the vehicle speed is low, the high accuracy characteristic of the first measuring instrument 4 is lost. In this embodiment, weight measurement is performed on the basis of the weighing units 4, 16, and 18 of the present invention.

  When using the weight measurements of the first and second scales 4, 16, 18, the error can be offset by determining the average value of each weight measurement. As for the low-frequency noise signal, as the number of measuring instruments increases, the positive and negative amplitudes at various phase points of the periodic noise signal can be added, so that the attenuation of the noise signal can be increased. As for the random noise signal, the standard deviation can be reduced as the number of second measuring instruments increases.

  In order to determine whether to use only the weight measurement value of the first weighing device 4 or the weight measurement values of the first and second weighing devices 4, 16, 18, the above was obtained. It is determined whether the vehicle speed V is faster or slower than a predetermined speed v1.

In addition, if the wheel weight etc. are measured using the weight measurement value of the 1st and 2nd measuring devices 4, 16, and 18, random noise can be reduced greatly. That is, if the weight measurement values of the first and second measuring instruments 4, 16, and 18 are W1, W2, and W3, since these are all weight measurement values for the same wheel, the weight measurement values W1, W2, and W3. Is superimposed with random noises of standard deviations σ1, σ2, and σ3, respectively, the weight measurement value Wt of the wheel is
Wt = (W1 + W2 + W3) / 3
The standard deviation σ as Wt is obtained by calculating the average value by
^{σ = (σ1 2 + σ2 2} + σ3 2) 1/2 / 3
Therefore, if σ1, σ2, and σ3 are all equal to σ1,
σ = σ1 / 3 ^1/2
Thus, the random noise is effectively attenuated. Therefore, as the number of second measuring instruments increases, the attenuation of random noise can be increased.

  Table 1 shows the operation of this wheel / axle weight measuring system.

  If the passing speed of the first weighing instrument 4 is greater than v1, even if wheels or axles with different weights have passed over the first and second weighing instruments 4, 16, 18 and the first and second Even if vibration weight is included in each of the weight measurement values W1, W2, and W3 of the weighing units 4, 16, and 2, the average value (W1 + W2 + W3) / 3 is obtained by adding W1, W2, and W3. Variations due to vibration noise are almost offset in the average value, and the only error that occurs in the average value is that the difference in level between the top surface of the weighing platform and the road surface differs depending on the second weighing devices 6 and 18. .

  Since this error component correlates with the weight of the axle or wheel and the speed of the vehicle, the vehicle speed V is measured as described above while the operation is continued, and the first and second measuring instruments 4, 16, 18 are used. The weight of the vehicle is measured, and classified and totaled in a list in the memory in the arithmetic circuit 14 according to the vehicle speed and a predetermined speed. However, when classifying and summing the weight measurement values of the first and second measuring instruments 4, 16, 18, the weight measurement value of the first measuring instrument 4 is always used as the weight value for determining the weight range on the list. use.

  In the case where the vehicle speed V is less than v1, as shown in Table 1, it is represented by the weight measurement of the first measuring instrument 4, and is set as the weight of the wheel or the axle.

  The vehicle speed V is classified as belonging to any range of p (v1 ≦ V <v2), q (v2 ≦ V <V3), and r (V ≧ v3). In each speed range p, q, r, any one of i (W1 <w1), j (w1 ≦ W1 <w2), and k (W1 ≧ w2) based on the measured weight value W1 of the first weighing unit 4 Classify whether it belongs to a range.

  If y is a range to which the measured vehicle speed belongs among p, q and r, and x is a range to which the measured W1 belongs to i, j and k, the weight measurement value W1 of the first weighing 4 is The weight measurement value W2 of the second weighing instrument 16 is accumulated in the ΣW2xy register, the weight measurement value W3 of the third weighing instrument 18 is accumulated in the ΣW3xy register, and is counted in the ΣW1xy register. The measurement number counter Cxy to be incremented.

  In this way, the weight measurement values of the first weighing device 4 and the second weighing devices 16 and 18 and the vehicle speed V during operation are obtained, and the weight measurement value W1 of the weighing table 4 is used to obtain i, j, the weight range of k is determined, the vehicle speed V is used to determine the speed range of p, q, and r, the weight measurement value W1 of the first weighing device 4, the second The weight measurement value W2 of the weighing instrument 16 and the weight measurement value W3 of the third weighing instrument 18 are accumulated in one of the ΣW1ip to ΣW3rk registers corresponding to the determined weight range and speed range, and the corresponding measurement counter Cip Any one of Ckr is incremented. Table 2 shows the relationship between the speed ranges p, q, r, the weight ranges i, j, k, the registers ΣW1ip to W3kr, and the measurement counter measurement counters Cip to Ckr.

When the average value is obtained, and N is the number of times that the vibration noise included in the weight measurement values W1 to W3 can be made sufficiently small, when the number of times the number of measurements is N among the measurement counters Cip to Ckr, When the cumulative value of the ΣW1xy register corresponding to the measurement counter is ΣW1xy, ΣW1xy / N is obtained, and ΣW2xy / N and ΣW3xy / N are obtained in the same manner.

Estimate errors e2xy and e3xy are
e2xy = ΣW2xy / N−ΣW1xy / N
e3xy = ΣW3xy / N−ΣW1xy / N
As this estimation error value. When these values are determined, the contents of the measurement counters Cxy, ΣW1xy, ΣW2xy, ΣW3xy registers are reset to 0 to prepare for the next error detection.

  The obtained estimation errors e2xy and e3xy are replaced with the previous data in the correction value memory list (also built in the memory of the arithmetic circuit 14) for each speed range and each weight range shown in Table 3. It is stored as a new correction value.

From the next measurement, the second weighing device in which the velocity V belongs to the velocity range p to r and the weight measurement value W1 of the first weighing device 4 is in the weight range to which the weight range i to k belongs. The correction values 16 and 18 are read out as e2xy and e3xy, and the correction weight values W2 ′ and W3 ′ of the second weighing units 16 and 18 are read out.
W2 '= W2-e2xy
W3 '= W3-e3xy
W2 and W3 are corrected based on the weight measurement value W1 of the first weighing instrument, and the axle weight or wheel weight Wt of this axle / wheel weight measurement system is
Wt = (W1 + W2 ′ + W3 ′) / 3
Calculate as

Thus, every time the total number of the first and second measuring devices 4, 16, and 18 reaches N, the latest correction value is obtained, and thereafter, the axle or wheel weight is obtained using the latest correction value. Since the measurement value is corrected, the latest level difference between the weighing platform 24 on the second weighing instruments 16 and 18 and the road surface 2 gradually changes. Corrections are made while updating the sequential estimation error using N weight measurements. Therefore, even if the height difference between the upper surface of the weighing platform 24 and the road surface 2 gradually changes due to the passage of the vehicle, the weight measurement value of the first weighing instrument 4 that is not affected by the change in the height difference is used. Since the correction is performed following the change in the error due to the height difference, the wheel / axle measurement system can be always free from the influence of the error based on the height difference.

  5 to 8 show flowcharts of processing performed by the arithmetic circuit 14. Various counters used in the following description are reset at the beginning. First, as shown in FIG. 5, it is determined whether the tire 9 has reached the position p1 based on w1 (k) and w2 (k) obtained by digitizing the output signals of the load cells 8a and 8b (step S2). Since the method for obtaining the position p1 has been described above, the description thereof will be omitted. Step S2 is repeated until the answer to the determination in step S2 is yes. If the answer to this determination is yes, the timer counters T1 to T5 are reset (step S3), and the timer counter T1 and the sampling number counter N are respectively incremented (step S4). Next, w1 (k) and w2 (k) are added to obtain Wi (step S6), and this is accumulated by the accumulation counter ΣWi (step S8).

  Next, it is determined using w1 (k) and w2 (k) as described above whether the tire has passed the position p0 (step S10). If the answer is yes, the timer counter T3 for measuring V3 is incremented (step S12).

  Subsequent to step S12 or when the answer to the determination in step S10 is no, it is determined whether the tire 9 has reached the position p2 based on w1 (k) and w2 (k) (step S14). Since the method for obtaining the position p2 has been described above, the description thereof will be omitted. If the answer to this determination is no, it is determined whether the count value of the timer counter T1 is greater than or equal to a predetermined Nm (step S16). If the answer to this determination is no, the process is executed again from step S4.

  If the answer to step S16 is yes, the value of the timer counter T1 is greater than or equal to Nm before the tire 9 reaches the position p2, so the vehicle is stopped or close to it, so the static weight As a measurement mode, the accumulated value of the accumulated counter ΣWi is divided by Nm to obtain a measured value W1s, and the weight of one wheel is obtained, and this process ends (step S18).

  If the answer to the determination in step S14 is yes, the vehicle speed V is calculated using the count value T1 of the timer counter T1, the sampling interval T, and L11 set in advance as described above. (Step S20), this is stored (Step S21). Next, since the answer to the determination in step S14 is yes, the first weighing device 4 is in the dynamic weight measurement mode, so the cumulative value of the cumulative counter ΣWi is divided by the count value of the sampling number counter N. The dynamic weight W1 is calculated (step S22).

  Next, it is determined whether or not the speed V calculated in step S20 is equal to or lower than a predetermined speed Vh2 (step S24). If the answer to this determination is no, it can be determined that the vehicle speed is slow, so the calculation is performed in step S22. The wheel weight is calculated using the W1 as it is, and this processing is terminated. If the answer to the determination in step S24 is yes, the speed of the vehicle is fast, and the wheel or axle weight cannot be calculated only with W1, so W1 is stored (step S26).

  As shown in FIG. 6, following step S26, it is determined whether the tire 9 has reached the position p3 (step S28). Since the method for determining whether or not this has been reached has been described above, a description thereof will be omitted. Step S28 is repeated until the answer to this determination becomes yes, and when the answer becomes yes, using the previously set L31, the count value C3 of the timer counter T3 and the sampling interval T as described above, The vehicle speed V2 heading toward the second measuring instrument 16 is measured (step S30).

  Next, the counter T4 for ending the weight measurement by the second measuring instrument 16 is incremented (step S32), and w3 (k) obtained by digitizing the outputs of the load cells 24a and 24b is accumulated by the accumulation counter ΣW3 ( Step S34). Then, it is determined whether the count value of the timer counter T4 is equal to or greater than a predetermined value Nm1 (step S36). If the answer to this determination is no, repeat from step S32.

  If the answer to the determination in step S36 is yes, the dynamic weight W2 in the second measuring instrument 16 is calculated using V3 calculated in step S30, the sampling interval T, the preset L3, and the cumulative value of the cumulative counter ΣW3. Calculate (step S38). Since the fact that W2 can be calculated by the equation shown in step S38 has been described above, a description thereof will be omitted. The calculated W2 is stored (step S39).

  Next, it is determined whether the tire 9 has reached the position p4 (step S40). Since this determination method has been described above, a description thereof will be omitted. Step S40 is repeated until the answer to the determination in step S40 is yes. If the answer to the determination in step S40 is yes, the count value C4 of the timer T1 that has continued counting as described above, the previous count value C3, the sampling interval T, and a preset L41 are obtained. The vehicle speed V4 toward the second measuring instrument 18 is calculated (step S42).

  Next, the counter T5 for ending the weight measurement in the second measuring instrument 18 is incremented (step S44), and w4 (k) obtained by digitizing the output of the load cell of the second measuring instrument 18 is added to the cumulative counter ΣW4. (Step S46). Then, it is determined whether the count value of the timer counter T5 is equal to or greater than a predetermined value Nm2 (step S48). If the answer to this determination is no, repeat from step S44.

  If the answer to the determination in step S48 is yes, the dynamic weight W3d in the second weighing unit 18 is calculated using V4 calculated in step S42, the sampling interval T, the preset L2, and the cumulative value of the cumulative counter ΣW4. Calculate (step S50). Since it has been described above that W3 can be calculated by the equation shown in step S50, the description thereof is omitted. The calculated W3 is stored (step S51).

  Next, as shown in FIG. 7, one of the predetermined speed ranges p, q, r is selected by the speed V stored in step S21, and the weight range i determined in advance by the weight W1 stored in step S26. , J, k are selected (step S52). The selected speed range is hereinafter referred to as y, and the selected weight range is hereinafter referred to as x.

  The weight W1 stored in step S26 in step S39 is stored in the accumulation register ΣW1xy of the first weighing unit 4 in Table 2, the accumulation register ΣW2xy for the second weighing unit 16, and the accumulation register ΣW3xy for the second weighing unit 18. The stored weight W2 and the weight W3 stored in step S51 are added (step S54). Then, the measurement number counter Cxy is incremented (step S56).

Next, as shown in FIG. 8, the estimated error values e2xy and e3xy for the second weighing units 16 and 18 are selected from the correction value memory list of Table 3 according to the weight range x and the speed range y (Step 3). S58). Using the read estimated error values e2xy and e3xy, the measured weights W2 and W3 of the second weighing units 16 and 18 are corrected to the corrected weights W2 ′ and W3 ′ according to the following formula (step S60).
W2 '= W2-exy
W3 '= W3-exy

Using the weight W1 of the first measuring instrument 4 and the corrected weights W2 ′ and W3 ′ of the corrected second measuring instruments 16 and 18, the weight measurement value of this axle / wheel weight measuring system according to the following formula: Wt is calculated (step S62).
Wt = (W1 + W2 ′ + W3 ′) / 3

  Then, it is determined whether the value of the measurement number counter Cxy is equal to or greater than N described above (step S64). If the answer to this determination is no, the measured weights W1, W2, and W3 of the first and second measuring devices 4, 16, and 18 have not been obtained until the number of times that a new estimated error value is obtained. finish.

  If the answer to this determination is yes, the measured weights W1, W2, and W3 of the first and second measuring instruments 4, 16, and 18 sufficient to obtain a new estimated error value have been obtained, so that ΣW1xy The integrated values ΣW1xy, ΣW2xy, ΣW3xy of the registers, ΣW2xy registers, and ΣW3xy registers are divided by the above N to calculate the average values of the weights W1, W2, and W3 of the first and second measuring instruments 4, 16, and 18 ( Step S64).

  The difference (ΣW2xy / N) − (ΣW1xy / N) between the average value ΣW2xy / N of the weight W2 of the second weighing device 16 and the average value ΣW1xy / N of the weight W1 of the first weighing device 4 is the second weighing. A difference between the average value ΣW3xy / N of the weight W2 of the second weighing unit 18 and the average value ΣW1xy / N of the weight W1 of the first weighing unit 4 (ΣW3xy / N) − ( (ΣW1xy / N) is set as the estimated error value e3xy of the second measuring instrument 18, and the contents of Table 3 are updated (step S66). Then, the W1xy register, the ΣW2xy register, the ΣW3xy register, and the measurement number counter Cxy are reset (step S68). This process ends.

  The weight Wt measured in this way is displayed on the display 40 shown in FIG. The data such as L1 described above is set in the arithmetic circuit 14 when the user operates the operation unit 42.

  As described above, the measured weights W2 and W3 of the second weighing devices 16 and 18 including the error due to the height difference of the road surface 2 are not affected by the error due to the height difference of the road surface 2. The measurement weight of 4 is used for correction. Moreover, although the height difference of the road surface 2 changes with time, the estimated error values e2xy and e3xy used for correction are updated following the change in the height difference.・ Axle weight measurement system is not accepted.

  In the above embodiment, the error in the measured weight of the second weighing units 16 and 18 is corrected by assuming that both the weight and the speed are affected at the same time, but the error is related to only one of the weight and the speed. Correction can also be performed as a thing.

  Further, based on the difference between the measured weights W2, W3 of the second measuring instruments 16, 18 and the measured weight of the first measuring instrument 4, the measured weights W2, W3 of the second measuring instruments 16, 18 are corrected. Calculates the ratio between the measured weights W2 and W3 of the second measuring instruments 16 and 18 and the measured weight W1 of the first measuring instrument 4, and the measured weights of the second measuring instruments 16 and 18 based on this ratio. W2 and W3 can also be corrected.

In the above embodiment, a total of nine sets of estimated error values e2ip to e3kr are calculated from the speed ranges p, q, r and the weight ranges i, j, k, and are used to calculate the second weighing unit 16. , 18 is corrected, but the estimation errors E2 and E3 with respect to the measured weights of the second weighing devices 16 and 18 are calculated as a function of the measured weight W1 of the first weighing device 4 and the vehicle speed V, for example, E2 = ( α21 * W1 + α22 * V)
E3 = (α31 * W1 + α32 * V)
It can also comprise so that it may calculate by. However, α21 and α31 are first coefficients, and α22 and α32 are second coefficients.

  In this case, the coefficients α21 to α32 are determined for each of the speed ranges p, q, and r, and are updated according to a change in the state of the road surface 2. Each coefficient α21 to α32 is determined as follows. In the following description, the case where the vehicle speed V is in the speed range p will be described. However, the coefficients α21 to α32 are similarly determined for the other speed ranges q and r.

N measured weights of the first measuring instrument 4 and the second measuring instruments 16 and 18 in which the vehicle speed V during operation is in the speed range p are collected. The u-th (u is 1 to N) -th measured weight is defined as W1u, W2u, W3u, and an actual measurement error e2u between the measured weight W2u of the second weighing device 16 and the measured weight W1u of the first weighing device 4 An actual measurement error e3u between the measured weight W3u of the measuring instrument 18 and the measured weight W1u of the first measuring instrument 4 is
e2u = W2u-W1u
e3u = W3u-W1u
Is calculated each time the measured weights of the first and second weighings 4, 16, and 18 are obtained.

The deviation d2u between the actual measurement error e2u and the estimation error E2 of the second measuring instrument 16, the deviation d3u between the actual measurement error e3u and the estimation error E3 of the second measuring instrument 18, and the vehicle speed at that time as Vu,
d2u = e2u− (α21 * W1 + α22 * Vu)
d3u = e3u− (α31 * W1 + α32 * Vu)
The coefficients α21 and α22 that minimize the sum of squares of d2u are
α12 = {ΣVu ² * Σ (W1u * e2u) −Σ (W1u * Vu) * Σ (Vu * e2u)} / [ΣW1u ² * ΣVu ² − {Σ (W1u * Vu)} ² ]
α22 = {ΣW1u ² * Σ (Vu * e2u) −Σ (W1u * Vu) * Σ (W1u * e2u)} / [ΣW1u ² * ΣVu ² − {Σ (W1u * Vu)} ² ]
Is required. Note that Σ means accumulation from 1 to N. α31 and α32 are similarly calculated.

  The estimation errors E2 and E3 are calculated by the estimation formulas using the coefficients α21 to α32 obtained in this way, and thereafter the measured weights W2 and W3 of the second measuring devices 16 and 18 are corrected by the estimation errors E2 and E3. To do. This correction is performed until N new measured weights W1, W2, W3 and vehicle speed V in the speed range p are collected, and when N are collected, new coefficients α21 to α21 to α32 is calculated, and thereafter correction using new coefficients α21 to α32 is performed. Thereafter, the same is repeated.

When the arithmetic circuit 14 detects the measured values W1u, W2u, W3u and the vehicle speed V of the first and second measuring instruments 4, 16, 18 and the vehicle speed V is less than the predetermined v1, the above-described implementation is performed. W1u is used as the measurement weight in the same way as the form. In order to calculate α21 and α22 when N pieces of data are collected when the vehicle speed V is v1 or higher, ΣVu ² register, ΣW1u ² register, Σ (W1u * e2) register, Σ (Vu * e2u) Registers, Σ (W1u * Vu) registers are provided. These are provided for each vehicle speed range p, q, r. When the vehicle speed V belongs to the speed range p, when the measured weights W1u, W2u, and W3u at that time are obtained, the actual measurement errors e2u (= W2u−W1u), e3u (= W3u−W1u), Vu ² , W1u ² , W1u * e2, Vu * e2, and W1u * Vu are calculated and integrated with the corresponding ones of the above registers for the speed range p. Separately, a measurement counter is provided for each speed range, the number of measurements is counted, and in the speed range where the count value is N, the coefficients α21 and α22 are calculated as described above, and the next N weight measurements are performed. An error estimation formula to be used is calculated, and the measurement value of the second measuring instrument 16 is corrected by this estimation formula. Although explanation is omitted, α231 and α32 are similarly calculated, and the measurement value of the second measuring instrument 18 is corrected.

  Although the above program steps have been described as an example of a measurement process for one wheel or axle weight, a plurality of wheels may be used before one wheel or axle finishes the correction of the low weight area of the second weighing unit 18. Alternatively, the axle may pass through the first measuring instrument 4. In such a case, a predetermined number of processes may be performed in parallel based on the steps of FIGS. 5 to 8 from the detection of the position P1 to the end of the correction of the weight measurement value.

  As described above, according to the present invention, the measured weights of the second weighing devices 16 and 18 are compared with the measured weight of the first weighing device 4, and the difference obtained as a result is corrected. .

  In the above embodiment, the two second measuring instruments 16 and 18 are used. However, three or more second measuring instruments can be used, and conversely, one second measuring instrument 16 is used. You can also use only.

2 road surface 4 first measuring instrument 14 arithmetic circuit (correction means)
16 18 Second measuring instrument

Claims (6)

A first weighing platform having a dimension longer than a length of a ground contact surface of the vehicle tire in a traveling direction of the vehicle, and the wheel or axle weight of the vehicle when the ground contact surface of the tire is not in contact with a road surface; A first measuring instrument to measure;
A second weighing platform having a dimension shorter than the length of the ground contact surface of the vehicle tire in the traveling direction of the vehicle, and the axle or axle weight of the vehicle when the ground contact surface of the tire is in contact with the road surface; At least one second measuring instrument to be measured,
The first and second weighing platforms are arranged along the traveling direction of the vehicle, and the arrangement is made at a distance such that the tires do not ride on the first and second weighing tables at the same time.
Comparison result between the plurality of weight measurement values of the second weighing device and the plurality of weight measurement values of the first weighing device when the vehicle passes the weighing table of the first and second weighing devices a plurality of times. A wheel / axle weight measurement system provided with error correction means for obtaining a correction value based on the above and correcting an error peculiar to the weight measurement value of the second measuring instrument by the correction value . 2. The wheel / axle weight measuring system according to claim 1, wherein the error correction means includes a plurality of latest first and second obtained when the vehicle passes through the first and second weighing platforms a plurality of times . A wheel / axle weight measurement system that obtains the correction value based on a comparison result of a weight measurement value of a measuring instrument and automatically corrects an error peculiar to the weight measurement value of the second measuring instrument. In claim 2 wheels and axles weighing system, wherein the error correction means, also based on the speed of the vehicle, wheels and axles weighing system to correct for errors inherent in the weight measurement value of the second weighing instrument . 4. The wheel / axle weight measurement system according to claim 3, wherein the error correction means multiplies the weight measurement value of the first weighing instrument by a first coefficient and the vehicle speed by a second coefficient. An error estimated value is calculated by adding the value, and the first and second coefficients are the vehicle speed, the weight measurement value of the first measuring instrument, and the weight measurement of the first and second measuring instrument. Axle / wheel weight measurement system that calculates from the difference in values. 3. The wheel / axle weight measurement system according to claim 2, wherein the error correction means corrects an error peculiar to the weight measurement value of the second measuring instrument based on the speed of the vehicle and the axle or wheel weight.・ Axle weight measurement system. A first weighing platform having a dimension longer than a length of a ground contact surface of the vehicle tire in a traveling direction of the vehicle, and the wheel or axle weight of the vehicle when the ground contact surface of the tire is not in contact with a road surface; A first measuring instrument to measure;
A second weighing platform having a dimension shorter than the length of the ground contact surface of the vehicle tire in the traveling direction of the vehicle, and the axle or axle weight of the vehicle when the ground contact surface of the tire is in contact with the road surface; At least one second measuring instrument to be measured,
The first and second weighing platforms are arranged along the traveling direction of the vehicle, and the arrangement is made at a distance such that the tires do not ride on the first and second weighing tables at the same time.
It is determined whether the speed of the vehicle and the weight measurement value of the first or second measuring instrument correspond to a predetermined rank, and the weight of the second measuring instrument is based on the estimated error value corresponding to the corresponding rank. Error correction means for correcting an error peculiar to the weight measurement value of the second weighing device by correcting the measurement value, and the error estimated value is determined when the vehicle passes the first and second weighing platforms. each time, is the difference between the average value of the accumulated value obtained by accumulating the weight measurements of the first and second weighing instrument in the velocity and weight measurements and belongs rank of the first and second measuring instrument at that time Wheel / axle weight measurement system.

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