JP2516273B2 - Weighing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention stores a supply unit for supplying articles such as powder and granules in a variable supply amount, and stores the articles supplied by the supply unit. And a control unit (4) for controlling the supply unit so as to decrease the supply amount as the measured value by the measuring unit approaches the final measurement target value. Regarding the weighing device.

[Conventional technology]

The weighing device controls the supply unit so that the article supply amount decreases as the measured value by the measuring unit approaches the final weighing target value, and adversely affects the weighing accuracy when approaching the final weighing target value. It is intended that more accurate weighing can be performed by reducing the vibration and the like at the time of article supply that affects, but if the article supply rate is reduced as the final measurement target value is approached,
There is a problem that the weighing time required to complete the weighing tends to be long, and conventionally, when the weighing value on the way to the final weighing target value reaches the preset set target value, the supply amount is switched to the decreasing side. Each time weigh a weighing item, the actual time required to reach the set weighing target value is measured, and the set weighing target value is corrected based on the measurement result. The supply amount is controlled so that the measurement is completed within the time (for example, JP-A-63-2791).
(See Publication No. 20).

[Problems to be Solved by the Invention]

According to the above-mentioned conventional technique, the time timing for switching the supply amount of the weighing articles to the decreasing side on the way to the final weighing target value is set to the time actually required until the weighing value reaches the preset set weighing target value. Because it is changed while learning based on the time taken to reach the set weighing target value,
In other words, the temporal timing for switching the supply amount to the decreasing side depends on the supply state of the weighing article, that is, the amount of the weighing article or the distribution of the weighing article in the supply unit, or the change in the properties such as the particle size and the viscosity of the weighing article. The weighing time required to reach the final weighing target value tends to fluctuate each time, making it difficult to complete the weighing within the desired target time.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a weighing device that easily completes weighing within a desired target time even if the supply state of weighing articles changes.

[Means for solving the problem]

A first characteristic configuration of the present invention for achieving the above-mentioned object is a supply unit for supplying a variable supply amount of an article, and a weighing unit for storing the article supplied by the supply unit and measuring the stored amount. And a control means for controlling the supply unit so as to decrease the supply amount as the measured value by the measuring unit approaches the final target value for measurement, and a set time from the start of the measurement. After the lapse of time, the final weighing target value is reached, and storage means is provided for storing a time-series weighing target value that is determined so as to reduce the supply amount with the lapse of time from the start of weighing, and the control means is provided. It is configured to control the amount of articles supplied by the supply unit so that the measured value by the measuring unit matches the time-series target value stored in the storage unit.

The second characteristic configuration is that a supply unit that supplies the supply amount of the product is freely changeable, a measuring unit that stores the product supplied by the supply unit and measures the stored amount, and a measurement value by the measuring unit is the final value. A metering device comprising a control means for controlling the supply unit so as to reduce the supply amount as the measurement target value is approached, and the final measurement target value is reached after a set time has elapsed from the middle of measurement, Storage means is provided for storing a time-series measurement target value that is set so as to reduce the supply amount with the lapse of time from the middle of the measurement, and the control means controls the measurement unit to operate from the middle of the middle of the measurement. It is configured to control the amount of articles supplied by the supply unit so that the measured value matches the time-series target value stored in the storage means.

A third characteristic configuration is the first or second characteristic configuration, wherein the control means controls the article supply amount by fuzzy inference based on a deviation between the measurement value and the measurement target value and a change amount of the deviation. It is configured to do so.

[Work]

According to the first characteristic configuration, the article supply amount is controlled so that the measured value by the measuring unit matches the time-series measured target value stored in the storage means, so the measured target after a predetermined time has elapsed. If the value is set to the final weighing target value and control is performed, the weighing will be completed almost at the specified time.In particular, the final weighing target value is reached after the set time has elapsed from the start of weighing, and Since the article supply amount is controlled so as to match the time-series measurement target value that is set so as to reduce the supply amount with the lapse of time from the start, the accumulation amount and accumulation distribution of the measurement item in the supply unit, Alternatively, even if the properties such as the particle size and the viscosity of the weighing article change, the article supply amount is controlled so as to match the weighing target value at that time.

Further, by appropriately setting the time-series measurement target value (for example, decreasing the amount of articles supplied as the final measurement target value is approached), accurate measurement can be performed in the same manner as the conventional weighing device.

According to the second characteristic configuration, a large amount of articles are supplied to the weighing unit until the middle of the weighing to shorten the supply time, and the supply state is changed due to the change in the supply state of the weighing articles. Therefore, from the midpoint of the weighing process in which the weighing time is likely to vary, the article supply amount is controlled so that the weighing value by the weighing unit matches the time-series weighing target value stored in the storage means. Therefore, if the weighing target value after the lapse of a predetermined time is set as the final weighing target value and the control is performed, the weighing will be completed almost at the predetermined time. The supply amount is controlled so that it reaches the final weighing target value after the passage of time and meets the time-series weighing target value that is set to decrease the feeding amount with the passage of time from the middle of weighing. Metrology Deposition amount and deposition distribution of goods, or, even if the properties of such particle size and viscosity of the weighing article changes, the article supply amount is controlled to match the weighing target value at that time.

Further, by appropriately setting the time-series measurement target value (for example, decreasing the amount of articles supplied as the final measurement target value is approached), accurate measurement can be performed in the same manner as the conventional weighing device.

According to the third characteristic configuration, the control of the article supply amount in the first and second characteristic configurations is obtained by fuzzy inference using the deviation between the measurement value and the measurement target value and the change amount of the deviation as input variables. It is performed based on the manipulated variable.

〔The invention's effect〕

According to the first characteristic configuration, even if the accumulation amount and distribution of the weighing articles in the supply unit or the properties such as the particle size and the viscosity of the weighing articles change, the articles are adjusted so as to match the weighing target value at that time. Since the supply amount is controlled, it is easy to complete the measurement within a desired target time even if the supply state of the measurement article changes.

According to the second characteristic configuration, by using a large amount of supply in a short time up to the middle of the weighing and a fixed time weighing from the middle of the weighing to the completion of the weighing, it is possible to perform quick weighing with less variation in the weighing time. Although it is possible, even if the accumulation amount and accumulation distribution of the weighing articles in the supply unit, or the properties such as the particle size and viscosity of the weighing articles change, the article supply amount so that it will match the weighing target value at that time. Is controlled, it is easy to complete weighing within a desired target time even if the supply state of the weighing articles changes.

According to the third characteristic configuration, since the fuzzy inference is applied to the control for the fixed time weighing, the characteristics of the article to be weighed,
It was possible to implement the control that is not easily affected by the state or disturbance relatively easily.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the weighing device of the present invention,
In the figure, (1) is a supply unit that supplies the product (A) so that the supply amount can be changed, and (2) temporarily stores the product (A) supplied by the supply unit (1). It is a measuring unit that measures the amount.

Specifically, the supply unit (1) includes an article storage hopper (12) including a supply cylinder (11) having an open lower end in a lower portion, and an opening / closing gate provided in a lower end opening of the supply cylinder (11). (13) and are provided. The opening / closing gate (13) is driven by a link (16) linked with an output shaft of a speed reducer (15) that is interlocked with a servomotor (14) so as to rotate around a pivotal support (13a), and its drive Depending on the supply cylinder (1
The opening degree of the lower end opening of 1) is adjusted.

The measuring unit (2) is specifically the supply unit (1).
Is formed of a hopper-shaped tubular body (21) having a lower end opening arranged below the lower end of the container, and a discharge gate (22) capable of being opened and closed is provided at the lower end opening. Then, the discharge gate (2
The article (A) supplied from the supply section (1) can be temporarily stored in the hopper-shaped cylindrical body (21) in the state where 2) is closed, and the stored amount can be measured. . Specifically, the weighing means uses the load cell (23) arranged so that the weight of the hopper-shaped tubular body (21) is applied to the supporting portion of the hopper-shaped tubular body (21), and the article (A) is A means for measuring the weight of the hopper-shaped tubular body (21) in the stored state is adopted.

The weighing value information (analog voltage) obtained by the weighing section (2) is amplified by the amplifier (61), and the A / D converter (6
After being converted into a digital value in 2), it is input to the control means (4) as a measured value. Further, the final weighing target value set by the setting unit (63) and the time-series weighing target value from the start of weighing stored in the storage unit (5) to the final weighing target value are also controlled by the control unit. Input to (4).

The control means (4) is equipped with a microcomputer, and based on the above-mentioned respective input information, the supply section (1).
A control signal for controlling the opening degree of the open / close gate (13) is output. This control signal is a digital amount corresponding to the opening degree, is converted into an analog voltage by the D / A converter (64), and is then input to the servo driver (65). Then, the servo driver (65) drives the servo motor (14) according to the analog voltage, and thereby adjusts the opening degree of the opening / closing gate (13) of the supply unit (1).

The information regarding the time-series measurement target value stored in the storage means (5) is, for example, as shown in FIG. FIG. 2 shows time t on the horizontal axis and the target value W on the vertical axis, and shows the time-series target values from the time t _{0 of the} start of measurement to the time te of completion of measurement te from the final target value We of measurement. Is. In this example, from the start of weighing t ₀ to some time t ₁
After a certain amount of time has passed, the increase of the weighing target value is started, and at first, the slope representing the product supply amount per unit time (ΔW / Δ in the figure
(corresponding to t) is increased, the inclination is reduced with the lapse of time, and the measurement target value is continuously changed so that the inclination becomes almost zero when the final measurement target value is reached. Actually, a line graph having a plurality of inclinations may be simplified. That is, it is sufficient to store in the storage means (5) a table of measurement target values with respect to time at a plurality of bending points.

Then, the control means (4) controls the weighing unit (2) at regular intervals.
The supply amount of the article by the supply unit (1) is controlled so that the measured value sampled by follows the time-series graph of the measured target value stored in the storage unit (5). That is, the supply unit (1) is set so that the deviation D between the weighing target value W and the weighing value ω at an arbitrary sampling timing ti from the start of weighing to the completion of weighing is set to zero.
The opening degree of the open / close gate (13) is controlled. In particular,
Based on the deviation D and the amount of change ΔD thereof, the opening degree, that is, the digital amount output to the D / A converter (64) is determined by fuzzy inference. Hereinafter, description will be added according to the control block diagram of FIG. 3 and the flowchart of FIG.

As described above, the control means (4) stores the weighing target value W corresponding to the time from the start of weighing from the storage means (5) and the amplifier (61) and A / D from the weighing section (2). The measured value ω is input via the converter (62). As shown in FIG. 3, the deviation calculation unit (41) first calculates the deviation D = W−ω from these two input information, and then the deviation change amount calculation unit (42) calculates the deviation change amount ΔD. = D-Dp (where Dp is the previous value of the deviation) is calculated. Then, the calculation results D and ΔD are input variables to the fuzzy controller (4
Given to 3). The fuzzy controller (43) includes a rule storage unit (44) for storing a plurality of rules (control rules) described later, and the input variables D and ΔD for these rules.
And a fuzzy inference unit (45) for obtaining an output result (manipulation amount V). The operation amount V is a digital amount corresponding to the opening degree of the opening / closing gate (13) of the supply unit (1) as described above.

In this way, the control means (4) controls the opening degree of the opening / closing gate (13) so that the measured value sampled at regular intervals matches the measured target value stored in the storage means (5). , This control is repeated until the final weighing target value We is obtained (see FIG. 4). And the final weighing target value
When We is obtained, the measurement is completed, and after that, the discharge gate (22) is opened and the article (A) is discharged to another container or the like (not shown).

Next, the fuzzy controller (43) will be described. Rule storage section of fuzzy controller (43) (4
The rule stored in 4) is expressed as follows, for example.

IF D = PB AND ΔD = N THEN V = NS While D and ΔD obtained by the input deviation calculation unit (41) and deviation change amount calculation unit (42) are single quantities, this rule is applied. The described D and ΔD are fuzzy variables represented by the membership function. Similarly, V is also a fuzzy variable here, or symbols such as PB, N, and NS are labels of values that each fuzzy variable can take. For reference, if the above rule is described in words, if the deviation (D) is positive large (PB) and the amount of change (ΔD) is negative (N), the manipulated variable (V) is negative. Small (N
S) Anyway.

Becomes This is because if the measured value is much larger than the measured target value and its deviation is decreasing,
This means that the output to the D / A converter (64) is set to a negative small value, the servo motor (14) is slightly reversed, and the opening degree of the opening / closing gate (13) is slightly narrowed.

Input variables D and ΔD of the antecedent part for all rules
Table 1 shows the relationship between the operation amount V of the consequent part and the operation amount V in a matrix.

Although the description of the membership function of each fuzzy variable is omitted, as can be seen from Table 1, D is 5 labels, ΔD
Is represented by three labels. Then, 15 combinations of rules are defined by the combination thereof, and the value of the manipulated variable V of the consequent part of each rule is represented by 5 labels.

Fuzzy inference unit (45) of fuzzy controller (43)
Applies the values of the input amounts D and ΔD from the deviation calculation unit (41) and the deviation change amount (42) to each of the above rules, and obtains the operation amount V of the consequent part from the matching degree. The MAX-MIN method is used as the inference method in this case. Then, the operation amount V obtained by each rule is integrated to obtain the final single operation amount V. The centroid method is used for this calculation. MAX-MIN above
The method and the barycentric method are well known as general fuzzy inference methods in fuzzy control, and therefore description thereof is omitted here.

As described above, the fuzzy controller (43)
The operation amount V corresponding to the adjustment amount of the opening degree of the opening / closing gate (13) of the supply unit (1) is determined from the deviation D between the measurement target value and the measurement value and the change amount ΔD thereof. This manipulated variable is input to the servo driver (65) after V is converted into an analog voltage by the D / A converter (64) as described above. The servomotor (14) is driven according to the analog voltage, and the opening degree of the opening / closing gate (13) of the supply unit (1) is adjusted accordingly.

[Another embodiment]

In the fuzzy inference of the above-described embodiment, only the deviation D between the measurement target value and the measurement value and its change amount ΔD are used as input variables, but it is also possible to add other conditions to the input variables and perform finer control. To be For example, setting means for setting the flowability of an article (powder, granules, etc.) to be weighed may be provided, and the set value may be added to the input variable. Note that the rules and inference methods for fuzzy inference shown in the embodiment are not limited to this, and can be variously modified.

In the embodiment, when a plurality of final weighing target values are set by the setting unit (63), a plurality of time-series weighing target values corresponding to the plurality of final weighing target values are stored in the storage means (5). However, as another method, the final measurement target value We is used as a parameter, and the measurement target value is expressed as a function having the time t as a variable, and this function is stored in the storage means (5). However, it is also possible to obtain the time-series measurement target value by every calculation according to the set final measurement target value.

Further, the information stored in the storage unit is set as a time-series measurement target value from the middle of measurement to the final target value, and the opening of the supply unit is increased until the middle of measurement. An example is also conceivable in which a large amount of articles are supplied to the supply section in a short time, and from the middle of the measurement, the constant time measurement is performed in the same manner as the above-described embodiment.

The present invention can be applied not only when weighing by weight measurement as in the above embodiment, but also when performing weighing by volume measurement, for example.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the structures of the accompanying drawings by this entry.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a weighing device according to the present invention, FIG. 2 is a graph showing time-series weighing target values stored in its storage means, and FIG. 3 is a control block diagram. ,
FIG. 4 is a flow chart of control. (1) ... Supply unit, (2) ... Measuring unit, (4) ... Control means, (5) ... Storage means, (A) ... Goods.

Claims (3)

(57) [Claims] 1. A supply unit (1) for supplying the article (A) in a variable supply amount, and a weighing for storing the article (A) supplied by the supply unit (1) and measuring the stored amount. Department (2)
And a control means (4) for controlling the supply unit (1) so as to decrease the supply amount as the measured value by the measuring unit (2) approaches the final target value for measurement. A storage means for storing a time-series measurement target value that is set so as to reach the final measurement target value after a lapse of a set time from the start of measurement and decrease the supply amount with the lapse of time from the start of measurement. (5) is provided, and the control means (4) supplies the measured value by the measuring section (2) to match the time-series measured target value stored in the storage means (5). A metering device configured to control the amount of article supply by the section (1). 2. A supply unit (1) for supplying the article (A) in a variable supply amount, and a metering for storing the article (A) supplied by the supply unit (1) and measuring the stored amount. Department (2)
And a control means (4) for controlling the supply unit (1) so as to decrease the supply amount as the measured value by the measuring unit (2) approaches the final target value for measurement. And a storage means for storing a time-series measurement target value that is determined so as to reach the final measurement target value after a lapse of a set time from the middle of measurement and to decrease the supply amount with the lapse of time from the middle of measurement. (5) is provided, and the control means (4) sets the measurement value obtained by the measurement section (2) to the time-series measurement target value stored in the storage means (5) from the middle of the measurement. A metering device configured to control the amount of article supply by said supply section (1) to match. 3. The control means (4) is configured to control the article supply amount by fuzzy inference based on a deviation between the measurement value and the measurement target value and a change amount of the deviation. The weighing device according to claim 1 or 2.