JPS5944572B2 - Vehicle axle load measuring device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a vehicle axle load measuring device.

Conventionally, to measure the axle load value, wheel load, or weight by adding these together, a fast-response electric load detector is installed on the road surface, and the detected output is processed using a sophisticated method. , the axle value was used.

At this time, for structural and economical reasons, a detector with a length of about 1 meter in the running direction is used to measure the axle load or wheel load.

Figure 1a is a diagram showing the state in which the wheel passes over the detector.
1 schematically represents the wheels of the vehicle, 2 represents the loading plate, and 3
a t 3 b is a load transducer group, 2 and 3 a
t 3 b and the like are collectively called a detector.

When the wheel passes over it, the load transducer group 3 a t
For the output of 3b, the heights of 5a and 5b in Figure 1 and their composite wave 5 are the true loads, and the waveform is expected to be a trapezoidal wave.

However, there is vibration in the vehicle passing over the detector, and its amplitude and phase are not necessarily constant, so the output of the detector has a waveform like 7 in Figure 2 or 8 in Figure 3, which is the true load. It is different from Figure 1, No. 4.

In most cases, the vehicle passes over the detector while making a substantially sinusoidal steady vibration as indicated by the dotted line 6 in FIG.

Figure 4 a, b, and c'' show axle load values determined from the outputs of the load transducer group using the following methods: (1) peak hold method, (11) divisional integral peak hold force method, and (i++) integral method. In the figure showing the force, 9 is the output waveform, 10 is the waveform obtained by processing the output waveform using the division integral force equation, and 11 is the waveform obtained by processing the output waveform using the integral force equation.
, b are diagrams illustrating the force determined by the integral method from the output waveforms of the load converter group, and 12 and 13 are waveforms obtained by processing the output waveforms by the integral method.

Conventionally, the axle load value was determined from the output of the detector through the following processing.

(I) A so-called peak hold force formula that captures the maximum value of the detector output waveform (for example, IC in FIG. 2 or 8c in FIG. 3) and uses that value as the axle load value.

(II) Divide the detector output waveform at 9 in Figure 4a at regular time intervals as shown at 10 in Figure 4, average the area of the waveform at each divided time, and calculate the maximum The so-called split-integration peak hold method captures the value and uses it as the axle load value.

(Il[) The output waveform of the detector 9 in Fig. 4a is
The axle load value is the area averaged value between states 11a and 11b, where the wheels are completely placed on the detector and all of the weight of the vehicle, so-called axle load, applied to the wheels is on the load converter group, as shown in step 11. The so-called integral method.

Each of these methods had the following drawbacks.0 The peak hold force formula (I) also uses the load transducer group 3 to account for the effects of disturbances such as vehicle vibration acceleration and noise on the output waveform. Receive at a t 3 b.

Although the division-integration peak hold method (n) considerably alleviates the influence of peak noise, it does not reach the level of alleviating the influence of vibration acceleration of the vehicle.

The integral method (Ill) is effective in the case of low-speed running that includes several cycles or more of vibration acceleration of the vehicle within the effective waveform of the detection waveform (between 12a and 12b) as shown in Fig. 5a. It will not be effective if you are driving at a high speed like this.

There are disadvantages such as, all of them eliminate the influence of vehicle acceleration,
It was not possible to measure the correct axle.

The non-invention is to calculate the acceleration g from the dynamic load W and perform load correction, and the purpose is to measure the axle load with a very small error from the true load Wo. The present invention will be described in detail.

Two examples in which the dynamic load W obtained by the detector differs depending on the phase relationship of vibrations of the vehicle are shown in the output waveform 14 in FIG. 6 and the output waveform 15 in FIG. 7.

It is the sum of the dynamic load w (vertical acceleration of the vehicle!!t) and the true load (static load) Wo.

Now, the vertical acceleration is expressed using the unit of gravitational acceleration, where k is the amplitude, θ is the phase, t is the time, and f is the frequency of the acceleration.
．． 9=ksin(2πft10) −・−
...-(1), the dynamic load wi! vv-W' o + k W-o s+n (2πfT
+θ)−···−(2).

In the output waveform 14 in FIG. 6, at an arbitrary time t1. t2
．． The detected dynamic loads at t3 are Wl and W2, respectively.
, w3, a simultaneous equation is established from equation (2), and by solving this, the following is obtained.

That is, once the frequency f of the vertical acceleration of the vehicle and the sampling time tljt2jt3 for detecting the dynamic load are determined, the true load W is determined.

is found. Among these f t t+t t2t ts, for tljt2tt3, the sampling interval is always constant and treated as a constant in the calculation process, or the interval is set according to the vehicle speed using an appropriate method each time the measurement is made, so that the calculation is not too complicated. , can be processed using that value.

Furthermore, it has been empirically said that the frequency f of the vertical acceleration of the vehicle is approximately 3I-(z), especially when the heavy vehicle being measured is loaded, so t is treated as a nearly constant. It is also possible to install a vibration meter near the detector and use it to detect the frequency caused by vehicle vibration.
6) It is also possible to obtain f to be substituted into the equation.

Also, as mentioned above, we take data from 4 points instead of 3 points to create 4 simultaneous equations, let f be an unknown, and set θ to w−(,
It is also possible to obtain it by calculation in the same way as .

In any case, the right side of equation (6) will be composed of these set values or detected values, and the target true load W
.

can be found.

Furthermore, since the right side of equation (6) does not include θ, it is unrelated to the phase, and the output waveform 15 in Figure 7 is exactly the same as the output waveform 14 in Figure 6 if considered under the same conditions as... It is clear that the results are obtained.

Also, f=F1t2-11=t3-t2=T1t3-11
= 2T, and if these are considered as constant numbers, then f! , (6
), the following equation is obtained.

Furthermore, C1=1/(22cos2πFT)C2=cos
2πFT/(1-cos2πFT), since F and T are constant numbers, C1 and C2 are constants, and W = CI(W1+W3) C2W2 °° (
8) Unlike equation (6), equation (8) is a four-arithmetic equation that does not include trigonometric functions, making calculation extremely simple.

FIG. 8 is a block diagram of an embodiment of the present invention.

In FIG. 8, the outputs of converter groups 16a and 16b included in the detector are independently amplified by amplifiers 17a and 17b, and the outputs of amplifiers 17a and 17b (i.e., 14a and 14b in FIG. 6) are amplified by an adder 18. , the output waveform 1 in Figure 6
Combine as in 4.

Reference numeral 19 is a comparator, and the operating point of the comparator 19 is set in advance at a desired position using a resistor, and the amplifier 1
The outputs of 7 a t 17 b are compared by this comparator to detect 11 in FIG. 6 (or 1+ in FIG. 7).

21 and 22 are timers that detect arbitrarily set times t2jt3 from the time t1 detected by the comparator 19, and send the analog output of the adder 18 to the A/D converter 23.
The values of wl9w21w3 in FIG. 6 are recorded in the memories 24, 25 and 26 based on the commands of the comparator 19 and timer 21, 22, respectively.

20 is a comparator, which detects the time point p when the output waveform 14 in FIG. The arithmetic unit 2T detects the time point q when the value becomes smaller than the value
With 25 data and arbitrarily set constants, (8)
Execute calculations faithfully using formulas.

Note that f 2 tt) t2) t is not a constant, but is determined according to the vibration mode and traveling speed of the vehicle, and the true load W is determined by equation (6).

There is also a way to find out. Operation result W.

is displayed on the display 28 and recorded on the recorder 29.

As explained above, the vehicle axle load measuring device of the present invention has the advantage of being able to obtain a measurement value that is extremely close to the true load even if there is load variation due to vibration acceleration of the vehicle.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a state in which the alt wheel passes over the detector,
Figure 1 is an output waveform diagram of the load transducer group when a wheel passes over the detector in Figure 1a, and Figures 2 and 3 are load transducers due to a difference in one phase of vehicle vibration. The output waveform diagram of the group, Figure 4 ayb and c, shows the axle load value calculated from the output of the load transducer group using each of the following methods: (i) peak hold method, (1[) division integral peak hold method, and (area component force formula). Figure 5 apb is a diagram showing how to determine the axle load value using the integral method from the output waveform of the load transducer group, Figures 6 and 7 are output waveform diagrams of the load transducer group, Fig. 8 is a configuration diagram of an embodiment of the present invention. 1... Wheels, 2... Loading device, 3 a
t 3 b...Load transducer group, 4...
True load, 5.5 a) 5 b...Output waveform of load converter group, 6...Imaginary waveform of vehicle vertical acceleration, ? , 8, 9... Output waveform, 10.
...Waveform obtained by processing the output waveform using the division integral force formula, 11.12,13... Waveform obtained by processing the output waveform using the integral method, 14,15...・Output waveform, 16a, 16b...Load converter group, 1
7a, 17b...Amplifier, 18...Adder, 19.20...Comparator, 2L22...Tice 23...A/D converter ,24,25,2
6...Memory, 27...Arithmetic unit, 28
...Display device, 29...Recorder.

Claims (1)

[Claims] 1. An electric load detector is installed on the road surface where the vehicle passes,
With the wheel fully placed on this detector, time t,...
t2) Detector output Wl at ts. w2. Measure W3, set f to the frequency of the vertical acceleration of the vehicle, and use the following formula to determine the axle load value W. A vehicle axle load measuring device characterized by determining . 2 Install an electric load detector on the road surface where vehicles pass,
With the wheel completely resting on this detector, time t1.
t2. Detector output Wljw2, W3 at t3
and t2-t1=t3 t2=T, t3 tl=2T, f is the frequency of the vertical acceleration of the vehicle, and f=F, T and F are constant numbers, C,=1/( 2-2cos2πFT), C2=cos2
As πFT/ (1-cos27rFT), Wo=C
Axle load value W from the formula I(W1+W3) C2W2. A vehicle axle load measuring device characterized by determining .