JPH03565B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to electronic balances.

In general, with high-sensitivity electronic balances, after placing the object to be weighed on the weighing pan, it takes several seconds for the load measurement indication value to stabilize and remain still. Furthermore, the time required for the vehicle to come to rest is extended, and sometimes it may be necessary to wait more than ten seconds for the vehicle to come to rest. In addition, there are cases where the indicated value is not stable due to the influence of airflow for air conditioning in the weighing room, and the current situation is that the measurer is struggling to take countermeasures against this problem.

The present invention has been made in view of the above, and an object of the present invention is to provide an electronic balance that can automatically estimate and display a static value without waiting for the indicated value to become stable and static.

A feature of the present invention is that the maximum and minimum values of the step response waveform of the load detection output in the electronic balance are detected, and when the maximum and minimum values have been updated, the waveform is updated based on the maximum and minimum values. A temporary average value is calculated, and the elapsed time from when the output waveform that vibrates around the temporary average value intersects with the temporary average value until it crosses again, and the peak value of the waveform within that elapsed time. is detected, the product of the temporary average value of the peak value and the elapsed time is calculated, and the correction value is calculated by dividing the sum of the above products for two consecutive positive and negative peak values by the sum of the elapsed time. The reason is that the provisional average value that has already been determined is corrected and that value is estimated to be the static value of the output.

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

The load detection unit 1 converts the load detection data on the plate into digital data one after another at predetermined minute intervals, for example, every 0.01 seconds, and outputs the converted data to the control unit 2. The control unit 2 is composed of a microprocessor, and is a central processing unit that executes various calculations and programs and controls each peripheral device.
A CPU, a read-on memory ROM in which processing programs, etc. are written, a random access memory RAM equipped with an area for storing digital conversion values of detection data from the load detection section 1 and areas for various registers, and a temporary average value ₀ , which will be described later. , a storage device group 5 for storing the output waveform maximum value P ₁ , the output waveform minimum value P ₂ , positive and negative waveform half-cycle peak values H and L, and two elapsed times S and T, respectively,
These are connected to each other by bus lines. Connected to the control section 2 are a display 3 that displays calculation results based on command signals from the control section 2, and a keyboard 4 that includes various operation keys and a numeric keypad for input. Furthermore, random access memory
The detected data storage area of RAM can store up to n+1 pieces of data, and the latest data d ₀
The configuration is such that the oldest data DN is discarded each time it is stored. In addition, the load detection section 1
The gain of the servo loop is increased so that the braking ratio is close to zero, and the beam system of the balance mechanism is adjusted so that it can always perform approximate free vibration.

Next, we will discuss the effect. FIG. 2 is a flowchart showing a processing program according to an embodiment of the present invention.

When an object to be measured is placed on the load detection section 1, its output waveform becomes as shown in FIG. Detection data d ₀ from load detection unit 1 is loaded into random access memory RAM every 0.01 seconds (ST1,
ST2). The value of data d ₀ at the beginning of placing the object to be weighed increases moment by moment as shown in the section in Figure 3, so each time data d ₀ is taken in, the value is read into the maximum value register and maximum value memory. Furthermore, the value is also collected in the minimum value register (ST4, ST5).
Then, the values of the data d ₀ are displayed one after another on the display 3 (ST9, ST10). Eventually, after the value of data d ₀ reaches the peak value P ₁ and enters the interval shown in Figure 3, the peak value P ₁ remains in the maximum value memory, and the minimum value register and minimum value memory store their contents one after another. is updated (ST6, ST7). and data d ₀
When the value of reaches the downward peak value P ₂ , the value of the downward peak value P ₂ remains in the minimum value memory.
In this way, the maximum value P ₁ and minimum value P ₂ of the initial total amplitude of the output step response waveform are detected, and if they are no longer updated,
Using P ₁ and P ₂ , a temporary average value ₀ of the output waveform is calculated according to the following equation (1), and the value is stored (ST8).

₀ = P ₁ + P ₂ /2 ...... (1) The data d ₀ taken in after the provisional average value ₀ is calculated increases sequentially within the interval shown in Figure 3, but the value is not the provisional average value. compared to the value ₀ (ST13) ₀
The flag S' is set until it reaches (ST14). This flag S′ has data d ₀ as the temporary average value _0.
This indicates that the value is smaller than . Next, when the data _d0 reaches ₀ , it is determined whether the flag S' is set, and if it is set, the flag S' is reset and the flag S is set (ST15, ST16). This flag S indicates that data d ₀ exists in the section shown in FIG. If data d ₀ is captured while flag 7 is set, register S is counted up by 1 each time data d ₀ is captured (every 0.01 seconds) (ST11, ST21), and the peak value in that section is detected. is stored in the maximum peak value register H (ST21,
ST22). If the value of data d ₀ exceeds the maximum value P ₁ already stored, return to ST5, rewrite the contents of the maximum value memory, clear the contents of various registers, and restart the original routine. carried out (ST23). If the data _d0 after the peak value is detected becomes equal to the temporary average value ₀ again, the flag S is reset and the flag T is set (ST24,
ST25). This flag T is data in section V in Figure 3.
Indicates that d ₀ exists. If data _d0 is fetched while this flag T is set, the register T
is counted up by 1, and the interval V
The downward peak value at is detected and stored in the minimum peak value register L (ST12, ST29,
ST30, ST31). Similarly, data d ₀ is the minimum value P ₂
If it becomes smaller, the process returns to ST7, the value in the minimum value memory is rewritten, the contents of various registers are cleared, and the original routine is performed again (ST3).
2). After the downward peak value in section V is detected, if the value of data _d0 again matches the temporary average value ₀ , flag T is reset and flag S is set (ST33, ST34). At this point, the maximum wave height value H in the section is already stored in register H, and the time of the section is also stored in register S.
Since it is known by the value of registers H and S
Based on the values of registers L and T, a correction value ΔW is calculated by the following equation (2) (ST35, ST36).

ΔW=(H-W/- ₀ )×S+(L-W/- ₀ )×T/S
+T……(2) The meaning of ΔW in equation (2) is the sum of the area (positive) shown in the shaded area of the section in Figure 3 and the area (negative) shown in the shaded area of section V. is divided by the sum of the times of the section and the section V, and can be regarded as the deviation of the temporary mean value ₀ from the true mean value in the approximate free vibration waveform.

Then, the temporary average value ₀ is captured using this correction value ΔW, the corrected value is displayed, and the values of registers H and S are cleared and the display pass flag is set (ST36, ST37, ST18, ST19). ). When the data d ₀ is taken in after the temporary average value ₀ is corrected, the process proceeds from ST11 to ST20, and the peak value and time of the section shown in Figure 3 are detected using the same procedure.
In ST26, registers L and T are already in section V.
Since the values are stored in , Equation (2) is calculated using these values and the values of registers H and S in the newly detected interval, and the temporary average value ₀ is further corrected (ST27 , ST28). In addition, the provisional average value _{is 0}
Until a new correction is added to , the temporary average value ₀ up to that point is held and displayed (ST17). Also,
When the object to be weighed is removed or added to the weighing pan, the value of data _d0 becomes larger or smaller than the maximum value _P1 or the minimum value _P2 , so proceed to flowchart ST5 or ST7. The temporary average value ₀ , etc. is cleared, and the original routine is executed to find new maximum and minimum values.

In this way, two successive positives every half period,
The provisional average value is continuously corrected and displayed using the above-mentioned area related to the negative peak value.

In addition, in the above embodiment, an example was shown in which the correction value was calculated using two areas for each half period, but the sum of the positive and negative areas for each period of the waveform was calculated for each period. The correction value may be calculated by calculating and accumulating the accumulated value and dividing the accumulated value by the elapsed time. In this case, registers H, S, L, and T can be implemented by not clearing them in ST28 and ST37, but by sequentially transferring them to other registers and adding them.

As explained above, according to the present invention, when the step response waveform of the balance mechanism of the load detection section enters a free vibration state, the static value is automatically calculated without waiting for the vibration to stop. The displayed value can be read without having to wait from a few seconds to more than 10 seconds, unlike conventional methods. Furthermore, by continuously updating the correction value, a more accurate estimation can be made. In addition, since the electronic balance according to the present invention always performs measurements with the beam system of the balance mechanism in a free vibration state, it is hardly affected by disturbances such as air flow caused by air conditioning facilities or disturbances caused by continuous minute vibrations. I never receive it.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a flow chart showing its processing program, and FIG. 3 is a graph showing an example of the step response characteristic of the output of the load detecting section. 1...Load detection unit, 2...Control unit, 3...Display unit, 4...Keyboard, 5...Storage device group.

Claims (1)

[Scope of Claims] 1. Means for sampling and storing the digitally converted output value from the load detection section at predetermined time intervals, means for detecting the maximum and minimum values of vibration of the output value, and means for detecting the maximum and minimum vibration values of the output value. means for calculating a provisional average value of the output values using the maximum value and minimum value when updating of the minimum value is completed; and after calculating the provisional average value, the output value matches the provisional average value again from the point in time when the output value matches the provisional average value; means for detecting the elapsed time until
means for detecting the upward or downward peak value of the output value within the elapsed time; means for calculating the product of the difference between the peak value and the temporary average value and the elapsed time; Means is provided for correcting the provisional average value by adding the products of the peak values (upward and downward) and dividing the added value of the products by the sum of consecutive elapsed times as a correction value, An electronic balance configured to estimate a corrected temporary average value as a static value of the oscillating output value. 2. The electronic device according to claim 1, wherein the electronic device is configured to continue calculating the product even after estimating the static value, and sequentially update the correction value to calculate the static value. Balance.