JPH0139538B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for dynamically weighing articles to be weighed by means of a weighing conveyor.

In a weighing conveyor that combines a belt conveyor and a weighing device, the zero point fluctuates even in a no-load state due to the unevenness of the distributed load on the belt of the belt conveyor and the eccentric load of the pulley that drives the belt. There was a problem that it was not possible to perform highly accurate measurements. For this reason, there has conventionally been a method of determining the zero point weight at appropriate n points during one rotation of a belt conveyor, and dynamically measuring the weight by using the average value of these values as the zero point weight value. However, even with this method, if there are large variations in the belt's distributed load or if there is a large eccentric load on the pulleys, the difference between the average zero point weight value and the actual zero point weight value will become large, so it is still not possible to achieve high accuracy. I was unable to weigh it.

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly accurate dynamic weighing method even when there are large variations in the distributed load on a belt or when there is a large eccentric load on a pulley.

Therefore, the dynamic weighing method according to the present invention divides the entire length of the conveyor in one revolution into a plurality of sections sufficient to maintain weighing accuracy, rotates the conveyor at least once in a no-load state, and calculates the zero point weight of each section. When conveying the article to be weighed by a conveyor, obtain the weight value of the section in which the article to be weighed is being conveyed, and calculate the difference between this weight value and the zero point weight value corresponding to this section. It is calculated.

Hereinafter, this invention will be explained in detail based on two embodiments. A first embodiment is shown in FIGS. 1 to 4. In Figure 1, 1 is a belt conveyor, 2
3 is a weighing section, 3 is a load cell, 4 is a sequential comparison type or double integration type A/D converter 5, and 4 is a pulse generator, which gives conversion timing to the A/D converter 4 and also controls a control section 9, which will be described later. This provides the zero point detection timing. 6 is a detector for detecting that the article to be weighed has reached the weighing section 2; 7 is a rotation detector that generates a pulse every time the belt conveyor rotates once.

detector 6, rotation detector 7, pulse generator 5,
Each output of the A/D converter 4 is input to a microcomputer 8. The microcomputer 8 is
As shown in the figure, a control section 9, a calculation section 10, a register 11, an A/D timing pulse counter (hereinafter referred to as a timing counter) 12, a belt rotation number counter (hereinafter referred to as a CHC counter) 1
3. It is equivalent to one equipped with a display section 14. 15
is a keyboard that supplies start signals and the like to the microcomputer 8.

The microcomputer 8 is programmed according to the flowcharts shown in FIGS. 3 and 4 to carry out the dynamic weighing method according to the present invention. FIG. 3 shows the main routine, and FIG. 4 shows the interrupt routine. In this program, dynamic zero measurement command flag DZRF, dynamic zero measurement end flag
DZPF, start pulse flag STPF, belt start flag CHSF, measurement processing command flag
INTF and measurement processing completion flag INTPF are used.
All of these are initially set to 0. First, when a start signal is input from the keyboard 15, the control section 9 determines whether or not the belt of the conveyor 1 is being driven (step S1). Static weighing is performed when the machine is not in operation. Since this is irrelevant to the present application, the explanation will be omitted. If it is being driven, the control unit 9 clears the register 11 (step S2), and then clears the CHC counter 13 (step S2).
S3), and set the dynamic zero measurement command flag DZRF to "1" (step S4). Then, it waits for the pulse generator 5 to generate a pulse signal (step S5), and when it occurs, jumps to the interrupt routine shown in FIG.

In the interrupt routine, it is first determined whether the rotation detector 7 generates a pulse (step S6), and if a pulse is generated, the control section 9 determines whether the start pulse flag STPF is "0" or "1" (step S7). Since the start pulse flag is initially set to "0" here, the timing counter 12 is cleared (step S8) and the belt start flag is
Set CHSF to "1" (step S9).

Next, it is determined whether the weight is being measured (step
S10). Since the conveyor 1 is currently not transporting any articles to be weighed, the answer to step S10 is NO, and then it is determined whether the dynamic zero measurement flag DZRF is "1" (step S11). ). Here, since it is set to "1" in the main routine, the answer is YES, and then it is determined whether or not the belt start flag CHSF is "1" (step S12). Here, the belt start flag has already been set to "1", so the answer is YES.
Next, the CHC counter 13 is set to "1" (step S13). Next, it is determined whether the CHC counter 13 is 0 (step S14). In addition, the above-mentioned determination of the dynamic zero measurement command flag DZRF, determination of the belt start flag CHSF, and CHC counter 1
The purpose of determining whether or not 3 is zero is to ensure that the measurement is not affected even if the microcomputer malfunctions.

Then, the count value of CHC counter 13 becomes 0.
Therefore, it is determined whether the count value of the CHC counter 13 is a value obtained by adding 1 to the predetermined number of revolutions N of the conveyor (step S15). Since the two are not equal yet, the data from the A/D converter 4 is read (step S16). The count value of the timing counter 12 (currently "0") is stored in the register indicated (step
S17). In other words, the operation so far is as shown in Figure 2 a.
When the pulse generator 5 generates a pulse (16 in e in the figure) for the first time after the belt start pulse shown in b in the figure is generated, the output of the load cell 3 shown in FIG. It is something I have memorized. Thereafter, the process returns to the main routine shown in FIG. 3 again, and it is determined whether or not the dynamic zero measurement end flag DZPF is "1" (step S18). Since the initial value remains "0" here, when the timing pulse is input again, the interrupt routine returns again.

In the interrupt routine, it is determined in step S6 whether or not there is a belt start pulse again.
Since the conveyor 1 has not yet made one revolution, there is no start pulse, and the answer to step S6 is NO, setting the start pulse flag STPF to "0" (step S19) and incrementing the timing counter 12 by one (step S20). ), that is, set to "1", and then set the belt start pulse flag CHSF to "0" (step S21). Thereafter, as described above, it is determined in step S10 whether or not the weight is being measured, and the dynamic zero measurement command flag is set in step S11.
It is determined whether DZRF is "1" or not, and then, in step S12, it is determined whether or not the belt start flag CHSF is "1". Here are the steps
Since it was set to “0” in S21, CHC counter 1
In other words, step S13 is jumped without incrementing CHC counter 13, step S14 is executed, and it is determined whether or not CHC counter 13 is "0". Hereafter, execute steps S15, S16, and S17 in the same way as the first time,
Read the A/D data into register address 1 and return to the main routine. Thereafter, A/D data is sequentially read into each address of the register 11 in the same manner until the next start pulse is input. The number of A/D data obtained in this way is assumed to be m. Therefore, from address 0 to address m-1 of register 11, each A/
D data is read.

When the next start pulse is input, a new A/R signal will be added from 0 to m-1 of register 11 in the same way.
D data is integrated and CHC counter 13 is "2"
advance to Thereafter, in the same manner, belt conveyor 1
When the conveyor rotates N times, the cumulative value of N zero point measurement values for the same section of the conveyor is stored at address 0, and the same goes for other addresses. And belt conveyor 1
When the CHC counter 13 rotates N times, the count value of the CHC counter 13 becomes N+1, so the answer of step S15 is
YES, the CHC counter 13 is cleared (step S22), the dynamic zero measurement command flag DZRF is set to "0" (step S23), the dynamic zero measurement end flag DZPF is set to "1", (step S24), Return to main routine.

In the main routine, it is determined in step S18 whether the dynamic zero measurement end flag DZPF is "1" or not. Since it is "1" here, the dynamic zero measurement command flag DZPF is set to "0" (step S25). , the integrated values stored in addresses 0 to m-1 of the register 11 are divided by N to obtain an average value, and each integrated value is returned to its original address (step S26). Next, it is determined whether the measurement processing completion flag is “1” (step
S27) is initially set to "0", so it is determined whether there is a next key input (step S28).

When there is a key input, it is processed (step S29), and when the A/D input timing pulse is input, it jumps to the interrupt routine and goes through steps S6, S7, S8, and S9 again in the same manner as described above. The process is executed up to step S10, where it is determined whether weight measurement is in progress. Here, if the key input in step S29 is to instruct weight measurement, step S10 is performed.
If the answer is YES, it is determined whether a detection signal is input from the detector 6 (step S30). This answer
If YES, the measurement processing command flag INTF is set to "1" (step S31), the A/D data is read (step S32), and the average value zero point data specified by the address specified by the timing counter 13 (currently address 0) is read. (Step S33), the average value zero point data is subtracted from the A/D data and stored in the register 11 (Step S34), and the addition number counter is incremented by one (Step S35). Then, it is determined whether the number of additions is a predetermined value of 4 (step S36).
Currently, this is not 4, so the process returns to step S27 of the main routine. That is, this means that the output of the load cell 3 shown in FIG. 2c is detected by the detector 6 shown in FIG.
A/
The A/D converted signal is subjected to D conversion, and the corresponding average zero point data is subtracted from this A/D converted signal.

At step S27, the measurement processing end flag is set.
Determine whether INTPF is "1" or not, but now,
Since this is initially set to "0", the answer is NO, and step S28 is executed, but since there is no key input, the interrupt routine is entered in the same way as described above, and steps S6, S19, S20, and so on are executed. After passing through S21 and S10, the measurement command pulse (detector 6
The process is executed until it is determined whether or not the edge of the pulse) is detected. Here, edges are not detected, so
It is detected whether the measurement processing command flag INTF is "1" (step S37). Since this flag has already been set to "1" here, the A/D data is read in step S32, and thereafter the processing is carried out in the same manner as the previous time. When such processing is performed four times, the measured weight value integration register in the register 11 contains A when the pulse generator 5 generates four pulse signals after the detection pulse of the detector 6 rises. /D data minus the corresponding average zero point data is integrated. When the fourth integration is completed, that is, the answer in step S36 is
If YES, the measurement processing command flag INTF is set to "0" (step S38), and the measurement processing end flag is set.
Set INTPF to "1" (step S39) and return to step S27 of the main routine.

In step S27, since the measurement processing completion flag is "1", the accumulated measured weight value is divided by 4 to obtain an average value, which is displayed on the display section 14 (step S40). Then, the measurement processing completion flag is set to "0" (step S41), and the input of the A/D timing pulse is waited for.

In the second embodiment, as shown in FIG. 5, the present invention is implemented without using a microcomputer. In the same figure, 20-1 to 20-m
are registers, which correspond to the integration registers of the first embodiment. A counter 22 counts the pulses generated by the pulse generator, and corresponds to the timing counter of the first embodiment. A counter 24 counts the pulses generated by the rotation detector 7, and corresponds to the CHC counter of the first embodiment. 26 is a temporary memory, 28 is an adder, 30 is a divider, 32
34 is a subtracter, and 34 is a weighted average arithmetic circuit, which correspond to the arithmetic unit of the first embodiment.

Next, the operation will be explained. Now, the registers 20-1 to 20-m and the counter 24 have been reset, the conveyor 1 is rotating, and the A/D converter 4 is outputting A/D data based on the pulses generated by the pulse generator 5. It is assumed that the dynamic zero point adjustment signal is supplied to the AND gate 35.

In this state, when the rotation detector 7 generates a pulse signal, the counter 22 is reset and the count value of the counter 24 becomes "1". At this time, since the count value of the counter 22 is "0", the address pointer 36 specifies the register 20-1. The A/D data at that time is passed through the temporary storage register 26 and the adder 28 to the register 20-
1 is stored. Next, when the pulse generator 5 generates a pulse, the count value of the counter 22 becomes "1", the address pointer 36 specifies the register 20-2, and the A/D data at that time is similarly stored. Thereafter, similarly, while the conveyor 1 rotates once, A/D data is sequentially stored up to the register 20-m.

When the belt conveyor 1 rotates once and the rotation detector 7 generates a rotation pulse again, the value of the counter 24 becomes 2, the counter 22 is reset, and the register 20-1 is designated again. As a result, the value stored in the register 20-1 is called into the adder 28, and is added to the value stored at that time in the temporary storage register 26, and the added value is returned to the register 20-1.
will be returned to. Thereafter, integrated data is similarly stored up to the register 20-m. If you repeat this N times,
The register 20-1 stores N integrated values of the same section in one rotation of the belt conveyor. The same applies to other registers.

When the belt conveyor 1 rotates N times, the dynamic zero point adjustment signal disappears and the AND gate 35 is closed.
N is supplied from the counter 24 to the divider 30.
Then, according to the N+1st rotation, register 20
The integrated values are sequentially supplied from -1 to 20-m, and the divider 30 sequentially divides them by N and returns them to the respective registers 20-1 to 20-m. Note that the divider 30
The signal C supplied to the counter 24 is a division command signal, and is supplied when the count value of the counter 24 reaches N.

Next, when the belt conveyor 1 is transporting the article to be weighed, it is assumed that the AND gate 38 is supplied with a measurement command signal and is open. When the rotation detector 7 generates a rotation pulse in this state, the counter 22 sequentially registers the registers 20-1 to 20-1.
-call m. When the article to be weighed reaches the weighing section 2 and the detector 6 generates a detection signal, the subtracter 32 uses the A/D data from the A/D converter 4 to calculate the value stored in the register called at that time. is subtracted and supplied to the weight average calculation circuit 4. The subtracter 32 performs this subtraction every time the pulse generator 5 generates a pulse signal while the detector 6 generates a detection signal. The weight average calculation circuit 34 integrates and averages these subtracted values, outputs the average value, and displays it on the display section.

In the method according to the present invention, the belt conveyor is rotated once in an unloaded state, the total length of this one rotation is divided into a plurality of sections, the A/D conversion output of each section is stored, and the article to be weighed is conveyed. Since the no-load A/D conversion output corresponding to this section is subtracted from the A/D conversion output of the section where the conveyance is being carried out, even if the dispersion of the distributed load on the belt is large, the pulley Even if the eccentric load is large, highly accurate weighing can be performed.

In both of the above embodiments, the belt conveyor was rotated N times in a no-load state to obtain the average zero point value for each section, but in some cases, the belt conveyor may be rotated only once. In addition, in the above embodiment, the number of sections in one rotation of the belt conveyor 1 is m, but there is a possibility that the number of sections is not always m due to the transmission characteristics of the motor or gear, that is, the number of sections in one rotation of the belt conveyor 1 is m. If there is a possibility that the pulse generator 5 generates m or more pulses while the pulse generator 5
If the number of pulses exceeds m, m+1, m
The A/D data is stored in the +2...th register, and when the number of pulses of the pulse generator 5 is m, all the remaining registers are stored with the m-th A/D data (in the second embodiment, the 1 o'clock The A/D data in the storage register 26 may be stored. moreover,
Although four differences between the A/D data and the average zero point data are averaged and displayed on the display section, the number may be changed depending on the situation. Furthermore, although the pulse generator 5 and the rotation detector 7 are provided separately, the pulses and the rotation detection signal may be generated by one device. Further, in the above embodiments, the present invention was implemented on a belt conveyor, but it can also be implemented on a chain conveyor. Furthermore, in the above embodiment,
Although the weighing section 2 is provided at the lower part of the belt conveyor 1, the entire belt conveyor including other driving sections may be weighed by a weighing machine.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the device used in the first embodiment of the dynamic weighing method according to the present invention, FIG. 2 is an output waveform diagram of each part of the device in FIG. 1, and FIG. 3 is the first embodiment. Main routine flowchart, 4th
This figure is a flowchart of the interrupt routine of the first embodiment, and FIG. 5 is a block diagram of the apparatus used in the second embodiment. 1...belt conveyor, 3...load cell, 4...
A/D converter, 5...pulse generator.

Claims (1)

[Scope of Claims] 1. A weighing unit installed in the middle of a traveling conveyor, a rotation detector that generates a rotation detection pulse every time the conveyor rotates once, and a rotation detector that responds every time the rotation detection pulse is generated. A counter that starts pulse counting, a register whose number is equal to the count value of the counter from the time when the rotation detection pulse is generated to immediately before the next generation of the rotation detection pulse, and a detection when the conveyed article reaches the weighing section. In a weighing conveyor equipped with a detector that generates a signal, the counter counts pulses at least from when the rotation detection pulse is generated until the next rotation detection pulse is generated when the conveyor is in an unloaded state. a step of storing the measured value of the weighing section at that time in a register corresponding to the count value at that time; and a step of determining whether or not a detection signal of the detector is generated while the conveyor is conveying the article. , a step of subtracting the stored value of the register corresponding to the count value of the counter at that time from the measured value of the scale unit at that time when a detection signal of the detector is generated. .