JP3068885B2 - Weighing controller for batch weighing system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weighing control device for a batch weighing system for weighing a weighing object having a set weight value by controlling a flow rate of a weighing object such as a powder or a granule or a liquid to be charged. Things.

[0002]

2. Description of the Related Art Conventionally, the following weighing control method is used as a weighing control method by a weighing control device of this kind of batch weighing system. i) 2-stage metering control method (FIG. 15) to set the charged flow of two stages of full flow rate value Q ₁ and dribble flow rate value Q _2, the actual weight value reaches a predetermined charged flow rate switching換重weight value W _C until turning on the objects to be weighed by the full flow rate value Q _1. Then, near the predetermined charged flow rate switching換重weight value W _C to be weighed set weight value W _F are switched to dribble flow rate value Q ₂ Once arrived charged with the objects to be weighed set weight value W _F Get.

[0003] ii) introducing the continuously variable metering control system (16) full flow rate value Q ₁ and full flow rate value Q ₁ were added objects to be weighed to the insertion rate of two stages of dribble flow rate value Q ₂ DIS section, even small with the introduction flow rate value Q ₂ sets small projecting section to be turned on, the actual weight value is a first predetermined introduced flow rate switching換重weight values W ₁
DIS section to reach the turning on the objects to be weighed by the full flow rate value Q ₁ to. Then, until it reaches the predetermined charged flow rate switching換重weight value W ₂ of the second nearby set weight value W _F where the small projecting section to inject the weighing dribble flow rate value Q ₂ begins defines a turned flow advance It is continuously changed according to the set optimal algorithm. When the second predetermined input flow rate switching weight value W ₂ is reached, the small input flow rate value Q
₂ switched set weight value W in a small projecting section up to _F by introducing the objects to be weighed by the dribble flow rate value Q ₂ set weight value W
Obtain the weighing object of _F.

[0004]

However, in the above-described two-stage weighing control system, an overshoot may occur as shown in FIG. 15, and the overshoot actually causes the set weight value W to increase. There is a problem that a measurement error occurs because it is considered to be quantitative before reaching _F. Further, in the stepless weighing control method described above, there is no problem that overshoot occurs as in the above-described two-step weighing control method, but the weighing time varies due to the characteristics of the object to be weighed and other external factors. There is a problem that occurs. An object of the present invention is to solve the above-described problems and to provide a weighing control device of a batch weighing system that can perform weighing in a short time with a small weighing error and high weighing accuracy with little variation in weighing time. To provide.

[0005]

In order to achieve the above-mentioned object, a weighing control device for a batch weighing system according to the present invention controls an input flow rate of an input object to be weighed to measure a set weight value. In a weighing control device of a batch weighing system that weighs an object, the antecedent variable of a control rule is obtained by subtracting a ratio of an actual weight value to a set weight value from a ratio of an actual elapsed time after the start of weighing to a predetermined reference time. A fuzzy control unit is provided which is adapted to correspond to the value and to make the consequent variable of the control rule correspond to the input flow rate value.

[0006]

According to a control characteristic diagram used in the description of the embodiment according to the present invention, FIG. 6 is compared with the conventional control by the above-described two-stage weighing control system shown in FIGS. In the case of the control according to the present invention shown in FIG. 8 to FIG. 8, there is no overshoot and the weighing error is small. Also, in comparison with the conventional control using the above-described stepless weighing control method shown in FIGS. 12 to 14, the control according to the present invention shown in FIGS. There is little variation.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a specific embodiment in which a weighing control device of a batch weighing system according to the present invention is applied to an additive batch weighing system will be described with reference to the drawings. In FIG. 1, a feed screw (not shown) in an input feeder 2 provided at the bottom of the storage hopper 1 is rotationally driven by a servomotor 3, and the measured object stored in the storage hopper 1 by the rotational driving of the feed screw. An object is put into the receiving container 4. In addition, the rotation speed of the feed screw corresponds to the input flow rate of the object to be weighed which is input from the storage hopper 1 to the receiving container 4.

[0008] The receiving container 4 is provided with a load cell 5 for outputting a detection signal corresponding to the weight of the object to be weighed. After the weight detection signal from the load cell 5 is amplified by the load cell amplifier 6,
The data is converted into a digital value by the D converter 7 and supplied to the CPU 8. The CPU 8 processes the digitized weight detection signal to calculate the actual weight value of the object to be weighed put into the receiving container 4, and measures the actual elapsed time after the start of weighing by a built-in timer counter. I do. The actual weight value, the actual elapsed time, and the like are given to the fuzzy controller 9. In the fuzzy controller 9, the input flow rate switching weight value for switching to the small input flow rate set from the ratio of the actual elapsed time to the reference time for switching to the small input flow rate A fuzzy calculation is performed according to a predetermined control rule based on a value obtained by subtracting a ratio of the actual weight value from the actual weight value, and an input flow rate value for weighing the object having the set weight value with high accuracy in a short time is calculated. The calculated input flow value is returned to the CPU 8, and the CPU 8 outputs the input flow value and the calculated actual weight value, further, the set weight value, the set first and second input flow rate switching weight values, and the like. A command signal for the rotation of the feed screw of the feeder 2 is supplied to the servo driver 10 on the basis of the large / small input flow rate value set in (1) and the reference time for switching to the small input flow rate. The servo driver 10 controls the servo motor 3 based on the command signal to adjust the rotation speed of the feed screw of the input feeder 2 and the like.

[0009] The charging pattern in one cycle in the act of weighing an object to be weighed into the receiving container 4 from the storage hopper 1 will be described with reference to FIG. Actual weight value from the weighing start to reach the first turned flow rate switching換重weight value W ₁ (t ₁ -0) times the objects to be weighed are fed by full flow rate value to Q ₁ constant flow rate. Next, the (t ₂ −t ₁ ) time from when the first input flow rate switching weight value W ₁ reaches the second input flow rate switching weight value W ₂ is determined by fuzzy inference. Thus, the object to be weighed is input. Then, the objects to be weighed are fed in the second-on flow rate switching from換重weight value W ₂ up to set weight value W _F (t _f -t ₂₎ time dribble flow rate value Q ₂ of the constant flow rate again.

Next, fuzzy inference in the fuzzy controller 9 will be described with reference to FIG. First, the CPU 8 receives the actual weight value W and the actual elapsed time t from the CPU 8 at predetermined sampling intervals, and supplies the actual weight value W and the actual elapsed time t to the variable value calculating section 9A, and further sets the second input. based on the reference time t ₂ to switch the flow rate switching換重weight value W ₂ and the small-on flow rate, the following computation is performed. Deviation weight value W _e (g):

(Equation 1) The value t _{W obtained} by subtracting the weight ratio from the time ratio t _W :

(Equation 2)

[0011] Next, given (1), (2) the fuzzy operation unit 9B in real time from the obtained deviation by weight values W _e and the value t _W obtained by subtracting the weight ratio from the time ratio is a predetermined sampling interval expression. In the fuzzy operation unit 9B, based on the predetermined control rule deviation weight value W _e of the first antecedent, also the value t _W obtained by subtracting the weight ratio from time ratio second
A fuzzy calculation is performed with the input flow rate value v as the consequent part as the antecedent part. The input flow value v of the consequent part is subjected to fuzzy calculation as a control voltage V, and the control voltage V _S actually given as a command signal from the CPU 8 to the servo driver 10 is expressed by the following equation. In addition, k _W is an operation amount of gain.

(Equation 3)

Next, the fuzzy inference method and the like used in this embodiment will be specifically described. As a fuzzy inference method, the MAX- of the Mumdani method based on the composition rule of fuzzy relations
In addition to using the MIN method, the defuzzification uses the center of gravity method, and the inference formula, in other words, the first in the control rule.
The antecedent and consequent of FIG. 4 use the triangle shown in FIG. 4 as the membership function of the fuzzy variable, and the second antecedent of FIG. 5 as the membership function of the fuzzy variable. Triangles are used. The fuzzy level in FIG. 4 has the following meaning. V
B: Very large. VS: Very small. B: Large. M: About medium. S: Small. MB: A little larger. MS: a little small. The fuzzy level in FIG. 5 has the following meaning. PL: positive and large. NL: Negative and large. PM: Positive and medium. Z: zero. NM: Negative and medium. PS: Positive and small. NS: Negative and small. Incidentally, the real value of the value t _W obtained by subtracting the weight ratio from the difference weight value W _e and the time ratio of each sampling the variable value computing section 9
In A, the value is normalized to a value in the section [−3, 3] and provided to the fuzzy operation unit 9B.

By the way, the deviation weight value W _e and the first antecedent, the control rule that the introduced flow rate value v and the consequent value t _W obtained by subtracting the weight ratio from the time ratio as the second antecedent An example is shown in Table 1 below, which is composed of a total of 23 rules.

[Table 1] The following is an example of one expression of the control rule.

(Equation 4)

When the control characteristic diagram is obtained by an experiment based on this embodiment of the addition type batch weighing system to which the above-described batch weighing system of the present invention is applied, the following results are obtained. Apparatus specifications used in the experiment ・ Feeding feeder type Feed screw Maximum capacity 6l / h Maximum rotation speed 30rpm Screw outer diameter φ20mm Screw inner diameter φ10mm Screw pitch 10mm (Servo motor 15W DC servo motor) ・ Measuring device Load cell Rated 1kg

[0015] Granulated sugar was used as an object to be weighed, and a set weight value and a set weight value were further determined.
The small input flow value and the reference time for switching to the small input flow are
The settings were as follows. Set weight value: 4.0 g Large input flow value: 2.0 g / s Small input flow value: 0.1 g / s Reference time for switching to small input flow rate: 6.0 s

[0016] The first and second charged flow rate switching換重weight value W _1, W ₂ is set, the operation amount gain k _W, even deviations weight value W _e, the value t _W obtained by subtracting the weight ratio from time ratio Three types of experiments were performed by changing the initial value of each fuzzy set of the input flow rate value v and the fuzzy set as shown in Table 2 below.

[Table 2]

When the same control characteristic diagram and the like are obtained by the conventional two-stage metering control system and the stepless metering control system, the following results are obtained.

[Table 3]

From the above results, the weighing time in the case of the so-called fuzzy weighing control system according to the present embodiment is the same as that of the conventional two-stage weighing control system and the stepless weighing control system in the same weighing time and weighing accuracy. It was clear that the variation in the size was smaller.

Although the present embodiment has been described using the input feeder 2 having a feed screw, an input gate capable of changing the opening degree of the gate may be used. In addition, when the capacity ratio is not so required for driving the feed screw and the input gate, the servo motor 3 is used.
Alternatively, an inverter motor may be used. In this embodiment, the case where the batch control system according to the present invention is applied to the batch control system is described. However, it is needless to say that the batch control system can be applied to the loss-in-weight batch control system.

[0020]

As described above, according to the present invention, weighing can be performed with high accuracy with less weighing error as compared with the conventional two-stage weighing control system, and compared with the conventional stepless weighing control system. As a result, there is little variation in the weighing time, and weighing can be performed in a short time.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a specific embodiment in a case where a batch control system according to the present invention is applied to an additive batch metering system.

FIG. 2 is a charging pattern diagram in an additive batch weighing system to which a weighing control device for a batch weighing system according to the present invention is applied.

FIG. 3 is a block circuit diagram of the fuzzy controller described in FIG.

FIG. 4 is a membership function diagram of a first antecedent part and a consequent part of a fuzzy variable used in the embodiment.

FIG. 5 is a membership function diagram of a second antecedent part of a fuzzy variable used in the embodiment.

FIG. 6 is a control characteristic diagram according to the present embodiment.

FIG. 7 is a control characteristic diagram according to the present embodiment.

FIG. 8 is a control characteristic diagram according to the present embodiment.

FIG. 9 is a control characteristic diagram according to a conventional two-stage weighing control method.

FIG. 10 is a control characteristic diagram according to a conventional two-stage weighing control method.

FIG. 11 is a control characteristic diagram according to a conventional two-stage weighing control method.

FIG. 12 is a control characteristic diagram according to a conventional stepless weighing control method.

FIG. 13 is a control characteristic diagram according to a conventional stepless weighing control method.

FIG. 14 is a control characteristic diagram according to a conventional stepless weighing control method.

FIG. 15 is an injection pattern diagram according to a conventional two-stage weighing control method.

FIG. 16 is a diagram showing an injection pattern according to a conventional stepless weighing control method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Storage hopper 2 Input feeder 3 Servo motor 4 Receiving container 5 Load cell 6 Load cell amplifier 7 A / D converter 8 CPU 9 Fuzzy controller 10 Servo driver

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01G 13/12 G01G 13/29

Claims (1)

(57) [Claims] In a weighing control device of a batch weighing system for controlling an input flow rate of an input weighing object and weighing an weighing object having a set weight value, a precondition variable of a control rule is measured for a predetermined reference time. Fuzzy control means for making a value corresponding to a value obtained by subtracting a ratio of an actual weight value to a set weight value from a ratio of an actual elapsed time after the start and a consequent variable of a control rule corresponding to an input flow rate value provided. A weighing control device for batch weighing systems.