JP2006284439A - Weight measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a weight measuring device having a function capable of detecting early speed of a vehicle 2 running on a metering stand 3 without providing separately a special detection means. <P>SOLUTION: A total weight signal Wcd is generated based on each weight signal from the third load cell 4c arranged on the position P0 side of the metering stand 3 and the fourth load cell 4d, and the point of time when the total weight signal Wcd is shifted to decrease inclination and the point of time when a rear wheel 2b runs onto the metering stand 3 are estimated based on a waveform change of the total weight signal Wcd. Values of the total weight signal Wcd generated during that time are stored in the order of time series, and an attenuation straight line is estimated from the stored total weight signal Wcd, and the vehicle 2 speed is detected based on the attenuation straight line. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a weight measuring device for measuring the weight of a vehicle in a running state on a weighing platform, and more particularly to a weight measuring device having a vehicle speed detection function on a weighing platform.

  2. Description of the Related Art Conventionally, a measuring method for measuring the weight of a vehicle in a running state using a weighing platform having a length capable of simultaneously loading all the wheels of the vehicle is known.

  Since this measurement method can significantly reduce the measurement time per vehicle compared to the method of measuring the weight of the vehicle by stopping the vehicle on the weighing platform, the measurement work efficiency can be improved. There is an advantage.

  On the other hand, if the speed at which the vehicle gets into the weighing platform or the speed on the weighing platform is too fast, the weight signal will vibrate greatly due to the impact on the weighing platform, and the axle weight will be measured. When the weight of one axle is measured, the next axle gets on the weighing platform for a short time and the time for the transient response vibration noise included in the weight signal to converge cannot be expected. Therefore, there is a problem that an accurate measurement result cannot be obtained.

  Therefore, in Patent Document 1, a transmitter is provided in the vehicle, and a receiver is provided at the start and end of the weighing table. In the receiver on the start end side of the weighing table, an output signal from the transmitter is received by the front wheel of the vehicle. The receiver on the terminal side receives the output signal from the transmitter at the timing when the rear wheel of the vehicle descends from the weighing platform, and the receiver on the terminal end receives the signal from the transmitter. The time required from receiving the signal until the terminal receiver receives the signal from the transmitter, that is, the time required for the front wheel of the vehicle to enter the weighing platform and the rear wheel of the vehicle to descend from the weighing platform. If the vehicle speed is detected based on the distance from the start to the end of the weighing platform and the vehicle speed exceeds a predetermined range, the accuracy of the measurement results cannot be guaranteed. For the driver Alarm to emit a weight measuring device to prompt re-weighing of the vehicle has been proposed.

JP-A-6-50801

  However, in the method described in Patent Document 1, in order to determine whether or not the vehicle speed is within an appropriate range, at least the rear wheel of the vehicle must pass through the end of the weighing platform. When it is determined that re-weighing is necessary because the speed is too high, the vehicle has already passed the weighing platform. Therefore, in order to prepare for reweighing, it is necessary to move the vehicle that has passed through the weighing platform to the front of the weighing platform, or to bypass the weighing platform and position it again before the weighing platform. There is a problem that it takes time to prepare for weighing, and as a result, the weight measurement time is prolonged. In addition, special speed detection means such as a transmitter and a receiver need to be prepared separately, which causes a problem that the configuration of the apparatus is complicated and the cost is increased.

  The present invention has been made to solve such a problem, and it is possible to detect the vehicle speed on the weighing platform without providing a special speed detection means separately, which necessitates reweighing of the vehicle. Even if it is a case, it aims at providing the weight measuring apparatus which can shorten the time prepared for the re-weighing.

In order to achieve the above object, the weight measuring device according to the present invention comprises:
Weighing the vehicle in a running state on the weighing platform with a weighing platform that has a length that allows all wheels of the vehicle to be loaded simultaneously and a load sensor that outputs a weight signal corresponding to the load applied to the weighing platform. In a weight measuring device that performs
Vehicle speed detecting means for detecting the speed of the vehicle from a change state of a signal due to wheel weight output from the load sensor is provided (first invention).

  The vehicle speed detecting means extracts a section in which a weight signal from the load sensor, which changes as a result of movement of a vehicle wheel on the weighing table, changes as a speed detection section, and a weighing table from the weight signal in the speed detection section. It is preferable to detect the speed of the upper vehicle (second invention).

  The allowable speed setting means for setting a predetermined allowable speed, the vehicle speed detected by the vehicle speed detecting means and the allowable speed set by the allowable speed setting means are compared, and the vehicle speed is determined as the allowable speed. It is preferable to provide an alarm signal transmission means for outputting an alarm signal when exceeding (Third invention).

  According to the first aspect of the present invention, the speed of the vehicle traveling on the weighing platform can be detected based on the weight signal output from the load sensor, which is an essential component of the weight measuring device. In addition, it is not necessary to provide special speed detecting means (transmitter / receiver) separately. Therefore, it is possible to prevent the apparatus configuration from becoming complicated and to prevent the cost from increasing. Further, the vehicle speed can be detected at an early stage by using a weight signal generated immediately after the vehicle gets on the weighing platform. Therefore, even if the vehicle speed deviates from the appropriate range for weight measurement, the driver can recognize the fact relatively early and be prepared for reweighing by moving the vehicle backward a short distance. Therefore, the time required for preparing for reweighing can be reduced as compared with the conventional one. As a result, there is an effect that the delay of the weight measurement time can be prevented.

  In addition, if the configuration of the second invention is adopted, speed detection is performed for a section where there are relatively few factors leading to an error, such as a section where the variation tendency of the weight signal is clear (for example, a section where the weight signal tends to decrease overall). By extracting as a section, the speed of the vehicle on the weighing platform can be measured more accurately.

  Furthermore, if the configuration of the third invention is adopted, when the vehicle speed deviates from the appropriate speed, the fact can be surely recognized by the driver of the vehicle, and re-weighing can be promoted. .

  Next, specific embodiments of the weight measuring device according to the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a weight measuring device according to an embodiment of the present invention, and FIGS. 2A to 2C are diagrams showing a positional relationship diagram between a weighing platform and a vehicle. FIG. 3 is an explanatory diagram for explaining the basic principle of vehicle speed detection.

  As shown in FIG. 1, the weight measuring device 1 according to this embodiment is a weighing platform 3 that is manufactured to a size that allows all the wheels of a vehicle 2 that travels from left to right in the drawing to be placed. And at the four corners below the weighing table 3, the weighing table 3 is disposed at a position slightly inside the weighing table 3, supports the weighing table 3, and transmits a weight signal corresponding to the load applied to the weighing table 3. Based on a total of four load cells (load sensors) 4a to 4d and weight signals supplied from the load cells 4a to 4d, a function for calculating the speed and weight of the vehicle 2 traveling on the weighing platform 3, An arithmetic unit (vehicle speed detecting means, allowable speed setting means, alarm signal transmitting means) 5 having various functions such as a function for setting an appropriate range of speed of the vehicle 2 and a function for transmitting an alarm signal, and the arithmetic unit 5 Various information such as calculation results Display specific contents of the alarm signal output from the arithmetic unit 5 is configured to include a display device 6 to recognize the driver of the vehicle 2.

  Each of the load cells 4a to 4d includes a built-in A / D conversion circuit and a filter circuit having a sufficient attenuation effect for a noise signal of several tens of Hz, and each load cell 4a to 4d has a short time interval. The weight signal digitized in (1) is subjected to noise processing and supplied to the arithmetic unit 5.

  In addition, the arithmetic unit 5 executes a required program / arithmetic processing based on an input / output circuit (not shown) and the weight signals supplied via the input / output circuit. An arithmetic processing unit (CPU; not shown) having a function for calculating speed and the like, and temporarily storing the program, various setting values necessary for arithmetic processing, and intermediate data for arithmetic processing (described later) For example, the total weight signal Wcd value Wn, the elapsed time measurement timer value, the count values of the first and second counters Cx1 and Cx2) and the like. The display device 6 is provided at a position where the display content can be easily recognized by the driver of the vehicle 2.

  Here, the edge of the weighing platform 3 that is the side on which the vehicle 2 enters is the start position P0 (hereinafter simply referred to as “position P0”), and the end of the weighing platform 3 on the side where the vehicle 2 gets off. The edge is defined as a terminal position Pe (hereinafter simply referred to as “position Pe”). Of the two load cells 4a, 4b on the position Pe side of the weighing platform 3, the load cell disposed on the right side when viewed from the driver of the vehicle 2 is defined as the first load cell 4a, and the load cell disposed on the left side. Is the second load cell 4b. Of the two load cells 4c, 4d on the position P0 side of the weighing platform 3, the load cell arranged on the right side when viewed from the driver side is the third load cell 4c, and the load cell arranged on the left side is the first load cell. 4 load cell 4d.

  Further, when the weighing platform 3 is viewed from the side (direction orthogonal to the traveling direction of the vehicle 2), the center position of the third (fourth) load cell 4c (4d) is defined as a position P1 (FIG. 2A). , (B)), the position of the front wheel 2a when the rear wheel 2b gets into the position P0 is the position P2, and the center position of the first (second) load cell 4a (4b) is the position P3 ( (See FIG. 3 (c)). Further, the distance from the position P0 to the position P1 of the weighing platform 3 is L ′, and the distance from the position P1 to the position P3 is L. In addition, although it does not specifically limit as a form of the vehicle 2, In the following description, the case where the speed detection of the vehicle 2 of 2 axis | shafts 4 wheels provided with the front wheel 2a and the rear-wheel 2b is demonstrated.

[Basic principle of vehicle speed detection]
Next, the basic principle for detecting the speed of the vehicle 2 traveling on the weighing platform 3 using the weight measuring device 1 of the present embodiment will be described. When it is assumed that all of the weight of the front wheel 2a is added to the ground contact center of the front wheel 2a, the total weight signal of the third load cell 4c and the fourth load cell 4d (hereinafter referred to as the total weight signal Wcd). When the waveform is drawn in accordance with the movement of the front wheel 2a, it is ideally as shown in FIG. Here, the total weight signal Wcd shown in FIG. 3 does not include error elements such as vibration noise and response delay caused by the weight signals of the load cells 4c and 4d passing through the filter circuit. To do.

  The ideal total weight signal Wcd shown in FIG. 3 will be described. When the grounding center of the front wheel 2a reaches the position P0 of the weighing platform 3, the total weight signal Wcd immediately becomes the value of W1 that is the weight of the front wheel 2a. Stand up until. Actually, the total weight signal Wcd starts to rise slightly before the front wheel 2a reaches the position P0. However, since this phenomenon is not directly related to the gist of the present invention, it rises vertically in FIG. It draws like so.

  During the period from when the ground contact center of the front wheel 2a reaches the position P0 to the position P1 (while the vehicle 2a moves from FIG. 2 (a) to FIG. 2 (b)), the weight W1 of the front wheel 2a is all third. In addition, since it is applied only to the fourth load cells 4c and 4d, the value of the total weight signal Wcd is kept constant at W1.

  When the ground contact center of the front wheel 2a advances toward the position Pe side beyond the position P1, the weight W1 of the front wheel 2a gradually increases to the (first and second) load cells 4a and 4b on the position Pe side. Since the total weight signal Wcd is distributed, the value of the total weight signal Wcd decreases linearly from the value of W1. Assuming that the rear wheel 2b does not get on the weighing platform 3, the value of the total weight signal Wcd becomes substantially zero when the ground center of the front wheel 2a reaches the position P3 ( (See the straight line indicated by the broken line Z1 in FIG. 3). However, actually, when the front wheel 2a reaches the position P2 (when the rear wheel 2b reaches the position P0 of the weighing table 3; see FIG. 2C), the value of the total weight signal Wcd is the rear wheel. It increases by the axle weight W2 of 2b and then decreases as the vehicle 2 moves forward (indicated by a solid line Z2 in FIG. 3).

  In order to obtain the speed of the vehicle 2 based on the waveform of the ideal total weight signal Wcd described above, the load cells 4c and 4d according to the weight of the front wheel 2a from the position P0 to the position P2 of the ground contact center of the front wheel 2a. A method of calculating the speed of the front wheel 2a can be employed depending on the state of change drawn by the total weight signal Wcd. The speed calculation method includes the following methods.

(1) Speed calculation method 1
If the time t1 until the ground contact center of the front wheel 2a (hereinafter simply referred to as “front wheel 2a”, the same applies to the rear wheel 2b) moves from the position P0 to the position P1 is measured, the position P0 and the position P1 The vehicle speed V1 is obtained by the following equation from the distance L ′ between them and the time t1.
V1 = L '/ t1

(2) Speed calculation method 2
After the front wheel 2a passes the position P1, a section where the total weight signal Wcd shows a change tendency is extracted to obtain the speed of the vehicle 2. To do this, the total weight signal is given at an arbitrary timing (t = tα) from when the front wheel 2a passes the position P1 until it reaches the position P2 (until the rear wheel 2b reaches the position P0). The value Wα of Wcd is measured (at this time, the front wheel 2a is assumed to be at the position Pα). The time tα until the front wheel 2a reaches the position Pα is measured using the time when the front wheel 2a passes the position P1 as a reference (t = 0), and the distance Lα from the position P1 to the position Pα is obtained. Here, if it is assumed that the rear wheel 2b does not get in, the value of the total weight signal Wcd generated when the front wheel 2a reaches the position P3 is 0 as described above. When attention is paid to the triangles c, P1, and P3 having the points c, P1, and P3 as vertices, and the triangles d, Pα, and P3 having the points d, Pα, and P3 as the vertices, ) Can be obtained.
(L−Lα) / L = Wα / W1 (1)
Further, the speed V1 of the vehicle 2 is expressed by the following equation (2) by the time tα from the front wheel 2a passing through the position P1 to the position Pα and the distance Lα from the position P1 to the position Pα.
V1 = Lα / tα (2)
And the speed V1 of the vehicle 2 on the weighing platform 3 can be calculated | required by solving Formula (1), (2).

(3) Speed calculation method 3
When the speed calculation method 2 is used, the total weight signal Wcd of the third load cell 4c and the fourth load cell 4d actually includes vibration noise, so that the vibration error of the measured values W1 and Wα is large. Therefore, the accuracy of the speed V1 is lowered. Therefore, in the speed calculation method 3, the value of the total weight signal Wcd is measured at a plurality of timings between the position P1 and the position Pα.

More specifically, in the coordinate system in which the position P1 is the origin, the vertical axis is the value of the total weight signal Wcd, and the horizontal axis is the time, the time until the front wheel 2a of the vehicle 2 reaches the position P2 from the position P1. The value of each total weight signal Wcd and the time during which the value of each total weight signal Wcd is measured are obtained, and the time until the front wheel 2a reaches the position P3 from the position P1 using the least square method is obtained from these values. The linear equation (3) indicating the decreasing tendency of the total weight signal Wcd is estimated.
W (t) = r · t + q (3)

  When the linear equation (3) is estimated, the estimated value W (0) of the total weight signal Wcd when the front wheel 2a is at the position P1 (t = 0) and the front wheel 2a is at the position Pα (t = Tα), the estimated value W (tα) of the total weight signal Wcd is obtained. When these estimated values W (0) and W (tα) are replaced with W1 and Wα in the previous equation (1), the position P1 is changed to the position P1. A distance Lα to Pα can be obtained. Next, the speed V1 of the vehicle 2 traveling on the weighing platform 3 can be obtained by substituting the distance Lα and the time tα into the previous equation (2). The speed V1 of the vehicle 2 obtained as described above is an error due to vibration noise as compared with the speed obtained based on the two total weight signals Wcd (W1, Wα of the speed calculation method 2) each including vibration noise. The accuracy is high as much as is suppressed.

[Specific example of vehicle speed calculation / judgment method]
The principle of the speed detection method of the vehicle 2 has been described above. In addition to the vibration noise described above, the response generated by the load cells 4a to 4d passing through the filter circuit is included in the total weight signal Wcd that is actually generated. Delay will be included. Therefore, in order to actually calculate the vehicle speed, etc., the speed calculation method 3 based on the above speed calculation method 3 is taken into consideration, and vibration speed and response delay are taken into consideration, and the speed calculation more in line with the actual fluctuation of the total weight signal Wcd. The law is executed. In addition, it is also determined whether or not the speed obtained by this speed calculation method is suitable for weight measurement. Hereinafter, a method for calculating and determining the speed of the vehicle 2 based on the total weight signal Wcd actually detected (including signal noise and response delay) will be described with reference to the drawings.

  FIG. 4 shows an actual waveform diagram (upper half) of the total weight signal Wcd generated when the vehicle 2 travels on the weighing platform 3, determination timings of the flags F1 to F4, and counters Cx1, Cx2 (flags). (Details of F1 to F4 and counters Cx1 and Cx2 will be described later.) FIG. 5 shows a timing chart (lower half), and FIG. 5 is a flowchart showing the flow of flag determination. Each shows a flowchart showing a flow of speed calculation / determination.

  Here, in the arithmetic unit 5 (digital) from each of the load cells 4a to 4d at a time interval shorter than 1/10 of the transient response vibration noise period generated when the vehicle 2 gets on the weighing platform 3. It is assumed that the weight signal is captured, and the load cells 4a to 4d are performing A / D conversion at a cycle shorter than the weight signal capture interval. Specifically, (analog) weight signals from the load cells 4a to 4d are digitized by an A / D conversion circuit every 0.5 msec, and then temporarily stored in the internal memories in the load cells 4a to 4d. The arithmetic unit 5 reads a (digital) weight signal stored in the internal memory of each of the load cells 4a to 4d every cycle of 2 msec. In other words, in the present embodiment, the arithmetic unit 5 samples the weight signals from the load cells 4a to 4d in a cycle of 2 msec.

  Further, if the frequency of vibration noise generated in the weighing table 3 is 10 Hz (cycle 100 msec), the arithmetic unit 5 outputs the weight signal from each of the load cells 4a to 4d at an extremely short cycle of 1/50 of the natural cycle. In addition, the amplitude of the vibration noise itself is sufficiently smaller than the axle weight of the vehicle 2. Therefore, it can be considered that the weight signals from the load cells 4a to 4d read into the arithmetic unit 5 within one cycle hardly change due to a shift in the read timing. Therefore, the weight signals from the load cells 4a to 4d sampled by the arithmetic unit 5 are handled as being read at substantially the same timing.

  The weight signals output from the load cells 4a to 4d are delayed in response by passing through the filter circuit. Therefore, a response delay naturally occurs in the total weight signal Wcd that is the sum of the weight signals of the third load cell 4c and the fourth load cell 4d (details will be described later). Furthermore, although the filter circuit exhibits a certain attenuation effect for a noise signal having a relatively fast period of several tens of Hz, a sufficient attenuation effect cannot be expected for a transient response vibration noise signal having a relatively slow period of about 10 Hz. Therefore, the total weight signal Wcd appears as a oscillating waveform as shown in FIG.

  Under the above conditions, the arithmetic unit 5 generates a total weight signal Wcd by summing the weight signals from the third load cell 4c and the fourth load cell 4d read in one cycle. Every time the total weight signal Wcd is generated, that is, every 2 msec which is a weight signal reading cycle, it is determined whether or not the flags F1 to F4 shown in the flowchart of FIG. 5 are set (hereinafter referred to as flag determination). )I do. Further, in the flag determination process, there is an operation of extracting a section (speed detection section) in which the vibrating total weight signal Wcd tends to decrease as a whole and storing the total weight signal Wcd generated in the section in the memory. Done.

  Further, in the arithmetic unit 5, in parallel with the flag determination, the speed calculation / determination shown in the flowchart of FIG. 6 is executed at predetermined time intervals (for example, every 10 msec), and the flag F5 (described later) is set. Determination of whether or not, calculation of the speed of the vehicle 2 traveling on the weighing platform 3, and determination of whether or not the speed of the vehicle 2 is suitable for weight measurement are performed.

  Next, the flow of flag determination will be described with reference to FIG. At the start of flag determination, the vehicle 2 is in a state of traveling toward the weighing platform 3 at a position immediately before the weighing platform 3, and all the flags F1 to F5 are not set (F1 to F5 = 0). Shall.

[Step A1]
When the total weight signal Wcd is generated in each arithmetic unit 5, whether or not the value Wn of the total weight signal Wcd exceeds the first set value Wzt registered in the memory area of the arithmetic unit 5. Make a decision. Here, as the first set value Wzt, a value sufficiently larger than the amplitude of the total weight signal Wcd when the vehicle 2 is not on the weighing platform 3 is adopted. Therefore, when the value Wn of the total weight signal Wcd does not exceed the first setting Wzt, it can be considered that the front wheels 2a are not on the weighing platform 3 and the flag determination is terminated. When the front wheel 2a moves forward and the value Wn of the total weight signal Wcd exceeds the first set value Wzt, it is determined that the start of the front wheel 2a entering the weighing platform 3 is reflected in the total weight signal Wcd, and the process goes to step A2. move on.

[Step A2]
It is determined whether or not a flag F1 for determining whether or not the front wheel 2a (the ground contact center) has entered the weighing platform 3 is set. If this flag is set (F1 = 1), the process proceeds to step A3, which will be described later, and if not (F1 = 0), the process proceeds to step A21. Immediately after the entry of the front wheel 2a onto the weighing platform 3 is reflected in the total weight signal Wcd, the flag F1 is not set, so the process proceeds to step A21.

[Step A21]
After the value Wn of the total weight signal Wcd exceeds the first set value Wzt, it is determined whether or not the peak value (maximum value Wmax1) of the first total weight signal Wcd has been reached. Specifically, the value Wn of the total weight signal Wcd is compared with the value Wn-1 of the total weight signal Wcd generated at the timing immediately before this Wn, and the following expression (4) is satisfied. Determine whether or not.
Wn <Wn-1 (4)
When the expression (4) is not satisfied, the total weight signal Wcd is in the process of simple increase, and since the maximum value Wmax1 has not been reached, the flag determination is once ended and every time the total weight signal Wcd is generated. Similar flag determination is repeated. When the total weight signal Wcd reflects that the front wheel 2a has entered the position P0 of the weighing platform 3, the equation (4) is satisfied. In this case, the sign of the slope of the total weight signal Wcd is reversed, and the maximum value Wmax1 is reached, so the process proceeds to the next step A22.

[Step A22]
When Expression (4) is satisfied, the value Wn−1 of the total weight signal Wcd is set to the maximum value Wmax1, the flag F1 is set (F1 = 1), and the process proceeds to the next step A23. As described above, the total weight signal Wcd is generated based on the weight signal including the response delay that has passed through the filter circuit. There is a slight time lag between the time point reflected in the weight signal Wcd. Therefore, when the maximum value Wmax1 is detected, the front wheel 2a is not located at the position P0, but is located at a position P0 ′ slightly ahead of the position P0.

[Step A23]
The count value of the first counter Cx1 stored in the memory of the arithmetic unit 5 is incremented by +1 (in this case, from the initial value 0). Next, using the count value of the first counter Cx1 and the generation interval (20 msec) of the total weight signal Wcd, the time is converted into the elapsed time from the time when the maximum value Wmax1 is detected (the time when the flag F1 is set). It is updated and stored in the memory as the measurement timer value. The process of step A23 is performed not only when the route follows step A2 to step A22 but also when another route is followed.

[Step A24, Step A25]
The value of the elapsed time measurement timer is stored in the memory before the entry of the rear wheel 2b onto the weighing platform 3 is reflected in the total weight signal Wcd (before detection of Wmaxk described later; before the flag F4 is set). It is confirmed whether or not the minimum set time T1 to be reached has been reached (step A24). Here, the minimum set time T1 is determined as follows. That is, the upper limit speed at which the weight measurement result can be obtained with high accuracy is determined based on actual measurement, etc., and the time until the front wheel 2a reaches the position P2 from the position P0 when the vehicle 2 travels at the upper limit speed is minimized. It is set time T1. If the elapsed time timer value becomes larger than the minimum set time T1 before reaching the position P2, it is determined that the vehicle 2 is traveling at a speed that can be accurately measured. Therefore, when the value of the elapsed time measurement timer reaches the minimum set time T1 before the ride of the rear wheel 2b is reflected in the total weight signal Wcd (before detection of Wmaxk described later), flag determination or a later described Needless to calculate the speed in step B3, it is clear that the vehicle 2 is traveling on the weighing platform 3 at a low speed to such an extent that the accuracy of weight measurement is not impaired, and all the flags F1 to F5 are set. Standing (F1 to F5 = 1; Step A25), the speed calculation process in Step B3 described later is omitted.

  On the other hand, if the minimum set time T1 has not been reached before the rear wheel 2b has entered the total weight signal Wcd, it cannot be determined whether or not the accuracy of the weight measurement result can be ensured. . In this case, the flag determination is once ended, and the same flag determination is performed when the next total weight signal Wcd is generated.

  When the total weight signal Wcd is generated after a certain time interval has elapsed, the same flag determination is performed. In this case, since the front wheel 2a is at the position P0 ′ and the flag F1 is set, the process proceeds to step A3 after the determination in step A1 and step A2.

[Step A3]
It is determined whether or not the flag F2 is set. Here, the flag F2 indicates whether or not the minimum value of the first total weight signal Wcd is detected after the entry of the vehicle 2 into the weighing platform 3 is reflected in the total weight signal Wcd (after detection of the maximum value Wmax1). It is a flag for determining whether or not. If the flag F2 is set, the process proceeds to step A4. In the flow of explanation (immediately after detection of the maximum value Wmax1), the flag F2 is not set, so the process proceeds to step A31 without proceeding to step A4.

[Step A31]
In step A31, after the maximum value Wmax1 of the total weight signal Wcd is detected in the previous step A21, it is determined whether or not the first minimum value of the total weight signal Wcd is detected. Specifically, the value Wn of the total weight signal Wcd generated after detection of the maximum value Wmax1 is compared with the value Wn−1 of the total weight signal Wcd generated at the immediately preceding timing, and the following equation (5 ) Is satisfied.
Wn> Wn-1 (5)
If the expression (5) is not satisfied, the total weight signal Wcd is in the process of simple decrease, and is regarded as not reaching the minimum value, and proceeds to step A23 and step A24, and the same processing and determination as described above are performed. Do. In step A24, if the value of the elapsed time measurement timer has not reached the minimum set time T1, the flag determination is terminated without proceeding to step A25 (hereinafter, the vehicle 2 travels at a certain speed). Therefore, it is assumed that the process of step A25 is not performed.) The determination / processing after step A31 and step A23 is repeatedly performed every time the total weight signal Wcd is generated until the previous equation (5) is satisfied. When the previous equation (5) is satisfied, the process proceeds to the next step A32.

[Step A32]
When the previous equation (5) is satisfied, at the timing when the value Wn-1 of the total weight signal Wcd is generated, after the detection of the maximum value max1, the first sign of the slope of the total weight signal Wcd is reversed, that is, After the detection of the maximum value Wmax1, it is determined that the first minimum value of the total weight signal Wcd has been reached, and the flag F2 is set (F2 = 1).

[Step A33, Step A34]
Next, the value Wn−1 of the total weight signal Wcd is used as a minimum value Wmin1, and this minimum value Wmin1, the second set value Wat registered in the memory, and the following arithmetic expression (6) are used to obtain the initial minimum The value Wmink is obtained (step A33) and stored in the memory (step A34).
Wmink = Wmin1 (Wn−1) −Wat (6)

  Thereafter, after performing the processing and determination after step A23 described above, the flag determination is terminated, and the same flag determination is performed when the next total weight signal Wcd is transmitted. In this case, since the flag F1 and the flag F2 are set, the process proceeds to step A4.

[Step A4]
It is determined whether or not a flag F3 for determining whether or not the total weight signal Wcd has shifted to a decreasing tendency is set. When the flag F3 is set, the process proceeds to Step A5 described later. At the present stage (immediately after the flag F2 is set), since the flag F3 is not set, the process proceeds to the next step A41.

[Step A41]
It is determined whether the value Wn of the total weight signal Wcd is less than the initial minimum value Wmink. When the value Wn of the total weight signal Wcd is not less than the initial minimum value Wmink, the processing from step A23 described above is performed.

[Step A42, Step A43]
When the value Wn of the total weight signal Wcd falls below the initial minimum value Wmink, it is determined that the front wheel 2a has moved forward from the position P1 is reflected in the total weight signal Wcd. As described above, since the total weight signal Wcd includes a response delay, when the value Wn of the total weight signal Wcd falls below the initial minimum value Wmink, the front wheel 2a is not at the position P1, but at the position P1. It will be located in the position P1 'ahead. Thereafter, the total weight signal Wcd is considered to shift to a decreasing trend as a whole while vibrating, and the flag F3 is set (F3 = 1; step A42). Next, the value Wn of the total weight signal Wcd when it is below the initial minimum value Wmink is updated as a new minimum value Wmink and stored in the memory (step A43).

[Step A44, Step A45]
Next, the value Wn of the total weight signal Wcd is stored in a predetermined memory area indicated by the value of the second counter Cx2 (in this case, the initial value 1) (step A44), and the count value of the second counter Cx2 Is incremented by 1 (step A45).

  Here, the reason why it is considered that the total weight signal Wcd has shifted to a downward trend when the value Wn of the total weight signal Wcd falls below the initial minimum value Wmink. When the front wheel 2a reaches the position P0 ′ (when the front wheel 2a enters the weighing platform 3 position P0 is reflected in the total weight signal Wcd), the total weight signal Wcd is gradually attenuated after suddenly rising. (Refer to the section represented by X0 in FIG. 4). Therefore, from the time when the front wheel 2a is at the position P0 ′ to the time when the position reaches the position P1 ′ (until the total weight signal Wcd reflects that the front wheel 2a is ahead of the position P1), the total is obtained. The value of the weight signal Wcd cannot fall below the minimum value Wmin1.

  On the other hand, when the front wheel 2a moves forward from the position P1 ′, the load on the front wheel 2a is applied not only to the third and fourth load cells 4c and 4d but also to the first and second load cells 4a and 4b. Therefore, the value of the total weight signal Wcd based on the weight signals from the third and fourth load cells 4c and 4d inevitably decreases with time. However, since the actual total weight signal Wcd vibrates as shown in the figure, it is difficult to determine an accurate timing for shifting to a decreasing trend. Therefore, a reference value smaller than the minimum value Wmin1 is set as the initial minimum value Wmink, and it is determined that the total weight signal Wcd has shifted to a decreasing tendency when the value Wn of the total weight signal Wcd falls below the initial minimum value Wmink. I tried to do that.

  In the previous step A44, the value Wn of the total weight signal Wcd is stored in the memory corresponding to the value of the second counter Cx2, and when the second counter Cx2 is incremented by +1 in step A45, The processing / determination after step A23 described above is performed, and the flag determination is terminated. Then, the same flag determination is performed when the next total weight signal Wcd is generated. In the explanation flow, since the flags F1 to F3 are set, the process proceeds to step A5 after the determination in step A2 to step A4.

[Step A5]
It is determined whether or not a flag F4 for determining whether or not the rear wheel 2b has entered the weighing platform 3 is set. In the explanation flow, since the flag F4 is not set, the process proceeds to step A51.

[Step A51, Step A52]
It is determined whether or not the value Wn of the total weight signal Wcd is below the minimum value Wmink (step A51). If the value Wn of the total weight signal Wcd is below the minimum value Wmink, the value of the total weight signal Wcd is updated as a new minimum value Wmink, stored in the memory (step A52), and the process proceeds to step A53. . If not, the process proceeds to step A53 without performing the process of step A52. The determination process of step A51 and the update process of step A52 when the determination of step A51 is satisfied are performed every time the total weight signal Wcd is generated until the flag F4 is set, and the memory is always the latest. The minimum value Wmink is stored.

[Step A53]
In step A53, whether or not the value Wn of the total weight signal Wcd is equal to or greater than the latest minimum value Wmink plus the third set value Wut stored in the memory of the arithmetic unit 5, that is, It is determined whether or not the following expression (7) is satisfied.
Wn ≧ Wmink + Wut (7)
Here, the third set value Wut is set to a sufficiently large value compared to the amplitude of the total weight signal Wcd, and the total weight signal Wcd rises abruptly due to the entry of the rear wheel 2b. (7) is not established. In the stage of explanation (the stage immediately after the front wheel 2a exceeds the position P1 ′), naturally, the previous equation (7) does not hold. In this case, the processing / determination of Step A44, Step A45, Step A23, and Step A24 described above is performed. It should be noted that the processes of step A44, step A45, step A23, and step A24 are repeated every time the total weight signal Wcd is generated until the flag determination is completed.

[Step A54]
As the vehicle 2 moves forward, the entry of the rear wheel 2b onto the weighing platform 3 is reflected in the waveform of the total weight signal Wcd, and the total weight signal Wcd suddenly rises. When Formula (7) is established, the flag F4 is set (F4 = 1). Thereafter, the processing of step A44 and step A45 is performed, and the value Wn (indicated by Wmaxk in FIG. 4) of the total weight signal Wcd when the previous expression (7) is established is the second counter Cx2 at the time of establishment. Is stored in a predetermined memory indicated by the count value. Thereafter, the processes of steps A44 and A45 are not performed, and the value Wn of the total weight signal Wcd when the previous equation (7) is established becomes the value Wn (Wmaxk) of the last total weight signal Wcd stored in the memory. . Therefore, a sudden rising of the total weight signal Wcd (establishment of the previous expression (7)) is observed in the predetermined area of the memory from the time when the total weight signal Wcd has a decreasing tendency (the flag F3 is set). The value Wn of each total weight signal Wcd generated while being recognized is stored in time-series order together with the count value of the second counter Cx2 corresponding to each value Wn. Similarly to the first counter Cx1, the second counter Cx2 is incremented by +1 every time the total weight signal Wcd is generated, so that the generation interval of the total weight signal Wcd is referred to. Each count value can be easily converted into the generation timing of each total weight signal Wcd. Hereinafter, together with the count value of the second counter Cx2, the generation timing of the total weight signal Wcd stored in the memory first is t = t0, and the generation timing of the last total weight signal Wcd (value Wmaxk) is t = Tm, and the generation timing of the total weight signal Wcd stored immediately before the last is represented by t = tm-1.

  After the processes of the last step A54, step A44, and step A45, the determination / process by the last step A23 and step A24 is performed, and the flag determination is once ended. Then, the final flag determination is executed when the next total weight signal Wcd is generated.

  In the final flag determination, since all the flags F1 to F4 are set, the flag determination is terminated after the determination in Step A1 to Step A5.

  Next, a flow of speed calculation / determination performed in parallel with flag determination will be described with reference to FIG. In the present embodiment, the vehicle speed calculation / determination is executed at predetermined time intervals (for example, several tens of milliseconds). However, a method of determining priority and performing interrupt processing may be employed. The speed calculation / determination flow will be described starting from a state immediately before the rear wheel 2b gets on the weighing platform 3.

[Step B1]
First, it is determined whether or not a flag F5 for determining whether or not the speed calculation / determination of the vehicle 2 on the weighing platform 3 has been completed is set. When the flag F5 is set (when the speed calculation / determination of the vehicle 2 has been completed, or when the process of step A25 has been performed), the process proceeds to step B11 described later. At the stage immediately before the rear wheel 2b gets on the weighing platform 3, the flag F5 is not set, so the process proceeds to the next step B2.

[Step B2]
It is determined whether or not the flag F4 is set. At the stage of explanation, the flag F4 is not set. In this case, assuming that there is not enough data to calculate the speed of the vehicle 2, this flow is temporarily terminated. When the flag F4 is set by the forward movement of the vehicle 2, sufficient data (the value Wn of the total weight signal Wcd) sufficient to calculate the speed of the vehicle 2 on the weighing platform 3 is stored in the memory. Advances to the next step B3.

[Step B3]
The speed of the vehicle 2 on the weighing platform 3 is calculated based on the value Wn of the total weight signal Wcd stored in time series in the memory of the arithmetic unit 5. In order to do this, from the timing (t = t0) in which the value Wn of the total weight signal Wcd is first stored in the memory together with the count value of the second counter Cx, the expression (7) is established (t = tm). The interval (indicated by X in FIG. 4) up to the previous timing (t = tm−1 in FIG. 4) is the interval (speed detection interval) in which the total weight signal Wcd tends to decrease. Extract as Based on the value Wn of each total weight signal Wcd generated in the extracted section and the generation timing of each total weight signal Wcd, an approximate calculation by the least square method is performed. Thereby, the straight line represented by the previous formula (3) is estimated.

[Step B4 to Step B7]
Thereafter, in the same manner as the speed calculation method 3 described above, the calculation using the straight line represented by the previous expression (3) and the previous expressions (1) and (2) is performed, and the speed of the vehicle 2 on the weighing platform 3 is determined. Calculate (step B4). Next, it is determined whether or not the calculated speed of the vehicle 2 exceeds the allowable upper limit speed stored in the memory area of the arithmetic unit 5 in advance (step B5). Assuming that the accuracy of the result cannot be ensured, an alarm signal indicating that the vehicle is stopped and re-weighing is transmitted and displayed on the display device 6. At that time, the display device 6 displays the allowable upper limit speed and the calculated speed together (step B6). As a result, the driver of the vehicle 2 can recognize that the vehicle speed is not appropriate, and the vehicle 2 can be urged to go back to the front of the weighing platform 3 and to enter the weighing platform 3 at an appropriate speed. . Thereafter, the flag F5 is set (F5 = 1; Step B7), and this flow is finished. After the required time has elapsed, this flow is performed again.

  On the other hand, if the speed of the vehicle 2 is equal to or lower than the allowable upper limit speed, it is considered that the weight measurement can be performed correctly, the flag F5 is set in step B7 without performing the process of step B6, and this flow is ended. This flow is executed again. In this case, the calculation unit 5 performs a weight measurement calculation based on the weight signals from the load cells 4a to 4d, and measures the weight of the vehicle 2 traveling on the weighing platform 3 (the present invention). This is not directly related to the purpose of the above, so a detailed description will be omitted.)

[Step B1]
As described above, it is determined whether or not the flag F5 is set (whether or not the speed calculation of the vehicle 2 has been completed). In the explanation flow, since the flag F5 is set, the process proceeds to Step B11 without proceeding to Step B2.

[Step B11]
In step B11, it is determined whether or not the value Wn of the total weight signal Wcd is lower than the first set value Wzt. If not lower, it is assumed that a part of the vehicle 2 is still on the weighing platform 3, and this flow is temporarily terminated. Thereafter, the same flow is repeatedly executed until the value Wn of the total weight signal Wcd falls below the first set value Wzt. When the value Wn of the total weight signal Wcd falls below the first set value Wzt, it is considered that the vehicle 2 has got off the weighing platform 3, and the processing from Step B12 to Step B14 is performed.

[Step B12 to Step B14]
When the vehicle 2 is regarded as getting off the weighing platform 3, all the flags F1 to F5 are cleared (F1 to F5 = 0; Step B12), and the first and second counters Cx1 and Cx2 are cleared (Step B13). Then, the value Wn and the count value of the total weight signal Wcd stored in the memory of the arithmetic unit 5 are cleared (step B14). With the above, all the speed detection processes for the vehicle 2 are completed, and preparation for speed detection of the following vehicle is made.

  In the present embodiment, the speed of the vehicle 2 on the weighing platform 3 can be obtained without providing any special means other than the load cells 4a to 4d and the arithmetic unit 5 which are essential components for the weight measuring device 1. it can. Therefore, it is possible to prevent the apparatus configuration from becoming complicated, and to eliminate a factor of high cost.

  Further, in the present embodiment, the determination as to whether or not the speed of the vehicle 2 is within the appropriate range is made when the rear wheel 2b enters the weighing platform 3, that is, when the vehicle 2 is still on the weighing platform 3. If the detection result exceeds the appropriate range, the fact and the fact that re-weighing is performed are promptly output and displayed on the display device 6. Therefore, the driver of the vehicle 2 can recognize at an early stage that the vehicle 2 is on the weighing table 3 that the need for re-weighing has occurred. You can quickly prepare for reweighing by moving backwards a distance. Thereby, the time required for reweighing can be shortened, and as a result, the efficiency of weight measurement can be improved.

  In the present embodiment, a section where the total weight signal Wcd is decreasing is extracted, and the speed of the vehicle 2 on the weighing platform 3 is calculated based on the total weight signal Wcd generated in the section. However, it is also possible to calculate the speed of the vehicle 2 based on the total weight signal Wcd before shifting to a decreasing trend. To do this, first, the value of the total weight signal Wcd generated before the front wheel 2a reaches from the position P0 ′ (detection timing of the maximum value Wmax1) to the position P1 ′ (detection timing of the initial minimum value Wmink). Are stored in the memory in chronological order, and the timing at which the maximum value Wmax2 of the total weight signal Wcd is finally obtained before the detection of the initial minimum value Wmink is obtained (this is substantially the same as the above-described detection method of the maximum value Wmax1). Is omitted.) At this time, it can be considered that the front wheel 2a has moved by the distance L ′ at the time td from when the maximum value Wmax1 is detected until the last maximum value Wmax2 is detected, and therefore, the expression V1 = L ′ / The speed of the vehicle 2 on the weighing platform 3 can be obtained from td. By adopting such a method, the speed of the vehicle 2 can be obtained at an earlier stage, so that even if it is necessary to perform reweighing, the time required for the reweighing can be further shortened. . In addition, although the speed detection timing is slightly delayed, it is of course possible to calculate the speed of the vehicle 2 based on the waveform drawn by the total weight signal Wcd when the rear wheel 2b gets on the weighing platform 3. It is.

Schematic configuration diagram of weight measuring device Figures (a) to (c) showing the positional relationship between the weighing platform and the vehicle Explanatory diagram for explaining the basic principle of vehicle speed detection A diagram showing an actual waveform diagram (upper half) of the total weight signal Wcd generated when the vehicle 2 travels on the weighing platform 3, determination timings of the flags F1 to F4, and count timings of the counters Cx1 and Cx2. (Lower half) Flow chart showing the flow of flag determination Flow chart showing the flow of speed calculation / judgment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Weight measuring apparatus 2 Vehicle 2a Front wheel 3 Weighing base 3A Starting end 3B Ending 4a-4d Load cell 5 Arithmetic unit 6 Display apparatus

Claims (3)

Weighing the vehicle in a running state on the weighing platform with a weighing platform that has a length that allows all wheels of the vehicle to be loaded simultaneously and a load sensor that outputs a weight signal corresponding to the load applied to the weighing platform. In a weight measuring device that performs
A weight measuring device comprising vehicle speed detecting means for detecting a vehicle speed from a change state of a signal due to wheel weight output from the load sensor.   The vehicle speed detecting means extracts a section in which a weight signal from the load sensor, which changes as a result of movement of a vehicle wheel on the weighing table, changes as a speed detection section, and a weighing table from the weight signal in the speed detection section. The weight measuring device according to claim 1, wherein the weight measuring device detects the speed of the upper vehicle.   The allowable speed setting means for setting a predetermined allowable speed, the vehicle speed detected by the vehicle speed detecting means and the allowable speed set by the allowable speed setting means are compared, and the vehicle speed is determined as the allowable speed. The weight measuring device according to claim 1, further comprising an alarm signal transmission means for outputting an alarm signal when the value exceeds.

Images