JP7680859B2 - Control method and system - Google Patents

Description

The present invention relates to a method for controlling a certain controlled value so that it coincides with or approaches a target value, and a system for carrying out this method.

For example, in a sludge treatment facility, a feeder is provided between a storage tank for storing dehydrated cake and an incinerator for incinerating the dehydrated cake to temporarily store the dehydrated cake to be fed into the incinerator. A first pump supplies the dehydrated cake from the storage tank to the feeder's supply port, and a second pump discharges the dehydrated cake from the feeder's discharge port and feeds it into the incinerator.

Here, in the feeder, it is necessary to keep the amount of dehydrated cake stored at a roughly constant level so that the stored dehydrated cake does not exceed the capacity and overflow, or conversely, the feeder does not become empty and interfere with the operation of the second pump. In other words, the amount of dehydrated cake stored in the feeder is set as the control target value, and it is necessary to control it so that it matches the target value or does not deviate significantly from the target value.

Note that examples of prior art documents that describe technology related to controlling the supply volume of stored material in such facilities include the following Patent Document 1.

Japanese Patent Application Publication No. 2-249812

In facilities like the one described above, in order to keep the amount of dehydrated cake stored, which is the controlled value, close to the target value, a common method is to monitor the amount of stored material in the feeder, for example, and adjust the operation of the first pump accordingly. If the amount of stored material is less than the target value or is decreasing, the rotation speed of the first pump is increased to increase the amount of stored material supplied per hour, and if the amount of stored material is greater than the target value or is increasing, the rotation speed is decreased to decrease the amount supplied.

However, this method has a problem in that the control of the storage amount through the supply amount has low tracking ability with respect to the storage amount of the stored material in the feeder. For example, if the discharge amount of the second pump is increased significantly in a short period of time, the rotation speed of the first pump is increased after a decrease in the storage amount in the feeder is measured, and as a result, the storage amount in the feeder increases and exceeds the target value, the rotation speed of the first pump is decreased, and if the storage amount falls below the target value again, the rotation speed of the first pump is increased again. By repeating this control, the storage amount fluctuates up and down and gradually converges to the target value. In other words, the control target value has low tracking ability with the target value, and becomes temporarily unstable due to fluctuations in the factors that affect the control target value (discharge amount).

In view of this situation, the present invention aims to provide a control method and system that can control the control target value with good tracking to the target value.

The present invention provides a control method for controlling a control object value by defining a control factor, which is a value that can be manipulated to control the control object value, and a fluctuation factor, which is a value other than the control factor that has the greatest effect on the control object value, and controlling the control factor in response to the fluctuation factor,
This applies to equipment equipped with a storage section for storing a substance,
The amount of the stored matter in the storage unit is set as the control target value,
The control factor is the supply amount of the stored material to the storage section or a value related thereto;
The discharge amount of the stored matter from the storage portion or a value related thereto is treated as the fluctuation factor;
The control factor is defined as a function of the fluctuation factor, and a correction value C according to the operation status of the equipment is added to the function,
The correction value is based on C=1,
The correction value is set to a value of C>1 under at least one of the following conditions: when the control object value is smaller than the target value; when the control object value is on a decreasing trend ; and when the control factor is smaller than the designed supply amount of the stored material to the storage unit or a value related thereto ;
This control method is characterized in that the correction value is set to a value C<1 under at least one of the following conditions: when the control object value is larger than the target value, when the control object value is tending to increase , and when the control factor is greater than the designed supply amount of the stored material to the storage section or a value related thereto.

The present invention provides a control method for controlling a control object value by defining a control factor, which is a value that can be manipulated to control the control object value, and a fluctuation factor, which is a value other than the control factor that has the greatest effect on the control object value, and controlling the control factor in response to the fluctuation factor,
This applies to equipment equipped with a flow rate regulator that adjusts the flow rate of the target object.
An actual measurement value of a flow rate of the object discharged from the flow rate adjustment unit is set as the control target value,
A value related to a flow rate of an object that can be manipulated by the flow rate adjusting unit is set as the control factor;
A target value of the flow rate of the object discharged from the flow rate adjustment unit is treated as the fluctuation factor;
The control factor is defined as a function of the fluctuation factor, and a correction value C according to the operation status of the equipment is added to the function,
The correction value is based on C=1,
The correction value is set to a value C>1 under at least one of the following conditions: when the control object value is smaller than a target value; when the control object value is on a decreasing trend ; and when the control factor is smaller than a design flow rate of an object that can be operated in the flow rate adjusting unit or a value related thereto ;
This control method is characterized in that the correction value is set to a value C<1 under at least one of the following conditions: when the control object value is larger than the target value , when the control object value is tending to increase, and when the control factor is larger than the design flow rate of the object that can be operated in the flow adjustment unit or a value related thereto.

In the control method of the present invention, when controlling the control factor, an influencing factor, which is a value that can affect at least one of the control target value or the control factor, can be taken into account.

In the control method of the present invention, the correction value can be calculated using at least one of the control target value and the control factor, or an influencing factor that is a value that can affect at least one of the control target value, as a variable.

The present invention also relates to a control system configured to execute the above-mentioned control method.

The control method and system of the present invention can achieve the excellent effect of controlling the controlled object value with good tracking to the target value.

1 is a schematic diagram showing an example (first embodiment) of the configuration of a control system according to an embodiment of the present invention; 11 is a graph showing an example of a relationship between a control factor and a fluctuation factor, and explaining correction of a proportionality coefficient. 11 is a graph showing an example of fluctuations in supply amount and storage amount relative to fluctuations in discharge amount assumed when control according to the present invention is performed. 11 is a graph showing an example of fluctuations in supply amount and storage amount with respect to fluctuations in discharge amount assumed when control is performed by a conventional method, as a reference example of the present invention. 11 is a graph showing the variation in supply amount and storage amount with respect to the variation in discharge amount observed when control according to the present invention is implemented. 1 is a flowchart illustrating an example of a procedure of a control method according to an embodiment of the present invention. FIG. 11 is a schematic diagram showing another example (second embodiment) of the configuration of a control system according to the present invention. FIG. 11 is a schematic diagram showing yet another example (third embodiment) of the configuration of a control system according to the present invention. 4 is a graph illustrating an example of the relationship between the opening degree of a regulator valve and a flow rate. 4 is a graph illustrating an example of the relationship between the opening degree of a regulator valve and a flow rate. 13 is a graph illustrating an example of a relationship between a control factor and a fluctuation factor and correction of a coefficient in the third embodiment. 13 is a graph illustrating another example of the relationship of the control factor to the fluctuation factor and correction of the coefficient in the third embodiment.

The following describes an embodiment of the present invention with reference to the attached drawings.

Figure 1 shows an example (first embodiment) of the configuration of a system capable of implementing the control method of the present invention, and assumes the case in which the present invention is applied to a sludge treatment facility. The material (dehydrated cake D) stored in a storage tank 1 is transferred to a feeder 2, which serves as a storage section for temporarily storing the material D, and then fed into an incinerator 3. A first pump 4 and a second pump 5 are provided between the storage tank 1 and the feeder 2, and between the feeder 2 and the incinerator 3, respectively. The first pump 4 supplies the dehydrated cake D from the storage tank 1 to the feeder 2, and the second pump 5 discharges the dehydrated cake D from the feeder 2 and feeds it into the incinerator 3. The first pump 4 is, for example, a screw pump, and the second pump 5 is, for example, a single-shaft eccentric pump.

The operation of the first pump 4, second pump 5, and incinerator 3 is controlled by the control unit 6. The control unit 6 is a device that monitors and controls the operation of each part of the facility, and for the first and second pumps 4, 5, it inputs operation signals to the motors 4a, 5a of the first and second pumps 4, 5 to control their on/off and rotation speed. In addition, signals indicating the rotation speed are input from the motors 4a, 5a to the control unit 6 at any time.

The feeder 2 is provided with a level meter 7 as a controlled object measuring part that measures the amount of dehydrated cake D stored inside. The controlled object measuring part (level meter) 7 is, for example, an ultrasonic distance sensor. The measured amount of dehydrated cake D is input to the control part 6 as a measurement signal from the level meter 7. In addition, in a facility such as the first embodiment, any device that can measure the amount of stored material may be used as the controlled object measuring part or level meter for measuring the amount of stored material as a controlled object value. The level meter may be, for example, a laser type in addition to an ultrasonic type. In addition, in the case of a level meter, the amount of stored material is measured as a height, but a device other than a level meter may be used as the controlled object measuring part, and the amount of stored material may be measured as a weight or volume, for example.

The storage tank 1 is provided with a moisture content meter 8 as a property measuring unit that measures the properties of the dehydrated cake D supplied from the first pump 4 to the feeder 2. A load cell 9 is provided at the connection between the storage tank 1 and the first pump 4 as a weight measuring unit that measures the weight of the dehydrated cake D in the storage tank 1 that is added to the inlet of the first pump 4. The measured values of the moisture content meter 8 and the load cell 9 are input to the control unit 6 as measurement signals. These values are used as values (influencing factors) that can affect the storage amount and supply amount of the dehydrated cake D, and are used to control the supply amount of the dehydrated cake D, which will be described later. Note that, as the property measuring unit and weight measuring unit, various devices other than the moisture content meter and the load cell may be used as long as the properties and weight of the dehydrated cake D can be appropriately measured. For example, a viscometer may be used instead of the moisture content meter to measure the viscosity as a property of the dehydrated cake D.

Here, for the sake of convenience, in this first embodiment, the rotation speed of the first pump 4 is treated as the "control factor" and the rotation speed of the second pump 5 is treated as the "variation factor". The control factor refers to a value that can be manipulated to control the control target value (in this first embodiment, the amount of dehydrated cake D stored in the feeder 2), and in this first embodiment, it is the supply amount of dehydrated cake D in the first pump 4 or a value related thereto (for example, the rotation speed of the first pump 4, or the rotation speed and output of the motor 4a). The variation factor refers to a value other than the control factor that can have the greatest effect on the control target value, and in this first embodiment, it is the discharge amount of dehydrated cake D in the second pump 5 or a value related thereto (for example, the rotation speed of the second pump 5, or the rotation speed and output of the motor 5a. Alternatively, a flow meter (not shown) may be provided on the path of the dehydrated cake D from the second pump 5 to the incinerator 3, and the measured value thereof may be used). The greatest feature of the present invention is, as explained below, that in order to keep the control object value (the amount of stored material (dehydrated cake) D in the storage section (feeder) 2) close to the target value, the control factor (the rotational speed of the first pump 4) is controlled in accordance with the fluctuation factor (the discharge amount of the stored material D in the second pump 5), and that in order to keep the control object value close to the target value, the control factor is defined as a function of the fluctuation factor. In other words, the control factor is directly correlated with the fluctuation factor rather than being fed back to the control object value, and the largest factor to be considered in determining the control factor is the fluctuation factor rather than the control object value.

Of course, the variables of the function that defines the control factor may incorporate the controlled object value in addition to the fluctuation factor, and may also incorporate various other values (referred to as "influencing factors") that may affect the controlled object value or the controlled factor. In the case of this first embodiment, the properties of the dehydrated cake D, which is the stored matter (values measured by the property measuring unit (moisture content meter 8)) and the weight of the dehydrated cake D at the inlet of the first pump 4 (values measured by the weight measuring unit (load cell 9)) are treated as influencing factors, and by taking these influencing factors into account when calculating the control factor, the control factor is corrected to a more appropriate value depending on the operating conditions, and the controlled object value is controlled with high precision.

A specific control method will be described. In the case of the sludge treatment facility described above, in order to maintain the amount of dehydrated cake D stored in the feeder 2, which is the controlled value, at a constant value, the supply amount of dehydrated cake D by the first pump 4 may be controlled to be equal to the discharge amount by the second pump 5. Therefore, the control factor (the rotation speed of the first pump 4), which is a value related to the supply amount of dehydrated cake D, is defined as a function of the fluctuation factor (the rotation speed of the second pump 5), which is a value related to the discharge amount. In the case of the example shown here, it is sufficient to define this function as a simple linear proportional equation as follows, and the control factor can be easily calculated according to the value of the fluctuation factor by such a calculation equation.
(Control factor) = A × C × (Variation factor) ... Equation (1)

In the above formula, A is a preset coefficient, and can be determined as a design value that makes the supply amount of dehydrated cake D by the first pump 4 equal to the discharge amount of dehydrated cake D by the second pump 5, taking into consideration, for example, the design relationship between the rotation speed and the conveying amount of the first pump 4 and the design relationship between the rotation speed and the conveying amount of the second pump 5. In other words, by operating the first pump 4 with A as the proportionality coefficient of the control factor for the variable factor, the supply amount and discharge amount to the feeder 2 are balanced, and the amount of dehydrated cake D stored can be kept constant.

However, depending on the actual operating conditions, the fluctuating factors and the control factors may not match simply by making them proportional to a fixed coefficient. For example, if the first pump 4 is a screw pump and the second pump 5 is a single-shaft eccentric pump, the second pump 5, which is a single-shaft eccentric pump, can transport an amount of dehydrated cake D that is almost proportional to the rotation speed, but the first pump 4, which is a screw pump, may have a variable amount of dehydrated cake D transported per rotation speed depending on the amount and properties of the dehydrated cake D stored in the storage tank 1. For example, when a large amount of dehydrated cake D is stored in the storage tank 1, a large amount of dehydrated cake D is pushed into the first pump 4 by its own weight, so that the transport amount is larger even if the rotation speed is the same, and the supply amount to the storage section (feeder 2) is larger than when the amount of dehydrated cake D stored in the storage tank 1 is small. Also, if the dehydrated cake D is hard, it is difficult for the first pump 4 to cut it out, so the transport amount is smaller, and if the dehydrated cake D is soft, the transport amount is larger.

In the case of this first embodiment, therefore, a variable C is set on the right hand side of the above equation as a correction value that is taken into account depending on the operating conditions of the equipment, thereby allowing control to be performed that is suited to the operating conditions at each time. This correction value C is calculated using an appropriate control method, such as fuzzy control, PID control, or logic control, with influencing factors (measurements from the property measuring unit (moisture content meter 8) and weight measuring unit (load cell 9)) as variables (note that the calculation method for correction value C is not limited to these, and other control methods and calculation methods may also be used as appropriate).

In addition to these influencing factors, the control target value (the amount of dehydrated cake D stored in feeder 2) may also be used as a variable in calculating correction value C. For example, the accuracy of control of the control target value can be further improved by controlling to set correction value C larger when the control target value is smaller than the target value or is on a downward trend, and smaller when the control target value is large or is on an upward trend.

The calculation of the correction value C may use only the influencing factors or the controlled value. As the influencing factors, only some of the examples given here may be used, or other values may be used instead or in addition to them as appropriate. For example, other sensors not shown may be provided, and the measured values of these sensors may be used as influencing factors.

In this way, by defining the control factor as an appropriate function in advance, the control factor can be appropriately calculated by simple calculation processing when executing control.

Figure 2 shows an example of a proportional relationship when controlling the control factor as a proportional value to the variable factor as described above. When C = 1, control is performed according to the relationship shown by the solid line in the figure (proportionality coefficient = A). When the amount of dehydrated cake D stored in feeder 2 (control target value) is less than the target value, or when the amount of storage is tending to decrease, when dehydrated cake D is hard and the amount of transport by first pump 4 is small, or when the weight added to first pump 4 by dehydrated cake D in storage tank 1 is small and the amount of transport by first pump 4 is small, correction value C is set to a value greater than 1 (see dashed line in the figure). On the other hand, when the amount of dehydrated cake D stored in the feeder 2 is greater than the target value, when the amount is increasing, when the dehydrated cake D is soft and the amount of the first pump 4 is large, or when the weight of the dehydrated cake D in the storage tank 1 applied to the first pump 4 is large and the amount of the first pump 4 is large, the correction value C is set to a value smaller than 1 (see the dashed line in the figure). Note that the specific correction value C is appropriately determined by fuzzy control, as described above. In addition, the upper and lower limits of the correction value C may be appropriately set, or the upper and lower limits may be made variable.

In this way, when the fluctuation factor is set as a value related to the discharge amount, the control factor is set as a value related to the supply amount, and the control factor is varied according to the fluctuation factor, the storage amount, which is the controlled value, can be controlled with good tracking to the fluctuation of the discharge amount, for example, as shown in Fig. 3. In Fig. 3, it is assumed that the discharge amount of the second pump 5 increases rapidly from time _t1 to _t2 , and then decreases rapidly from time _t3 to _t4 (see the upper part). In the case where the discharge amount varies in this way, by changing the supply amount according to the fluctuation of the discharge amount as described above (see the middle part), the controlled value (storage amount) can be accurately maintained near the target value even if the discharge amount varies (see the lower part).

In contrast, in conventional control in which the supply amount varies according to the storage amount, the storage amount has low follow-up ability to the variation in the discharge amount. An example of the variation in the supply amount and the storage amount assumed in such a case is shown as a reference example in FIG. 4. In this reference example, when the discharge amount (upper stage) increases at time t ₁ to t ₂ , the storage amount (lower stage) decreases first, and in response to this, control is performed to increase the supply amount (middle stage). As a result, the storage amount increases beyond the target value, and in response to this, the supply amount is subsequently decreased. By repeating this, the storage amount gradually approaches the target value while fluctuating up and down. At time t ₃ to t ₄ (when the discharge amount decreases), the storage amount also converges to the target value while fluctuating greatly. In this way, in the conventional control method, it takes time for the storage amount to stabilize in response to the variation in the discharge amount.

5 shows the results of actual measurements of the supply and storage volumes in response to fluctuations in the discharge volume in the first embodiment described above. In this actual operation, the second pump 5 is turned on at time _t0 , and then the discharge volume increases rapidly from time t5 to time _t7 , and then decreases rapidly from time _t6 to time _t7 . After that, the discharge volume gradually increases (see the upper dashed line).

The supply amount of the first pump 4 quickly follows such fluctuations in the discharge amount, fluctuating while generally balancing with the discharge amount (see the solid line in the upper part). The storage amount of the feeder 2 is kept approximately close to the target value after time _t0 (see the lower part). It does not converge over time as in the reference example shown in FIG. 4, but quickly follows the increase and decrease in the discharge amount.

The procedure for executing the above control method in a system can be summarized, for example, in a flowchart as shown in Figure 6.

First, a target value for the control object value (amount of dehydrated cake D stored in feeder 2) is set (step S1). Next, a coefficient A is set (step S2) to be used for controlling the control factor (rpm of first pump 4) against the fluctuation factor (rpm of second pump 5). The actual value of the control object value (measurement value of level meter 7) is obtained (step S3), and the influencing factor (measurement value of moisture content meter 8 and load cell 9) is obtained (step S4). A correction value C is calculated based on the values obtained in steps S3 and S4 (step S5).

Once the value corresponding to the fluctuation factor (the rotation speed of the second pump 5) is obtained (step S6), it is multiplied by coefficient A and correction value C to calculate the value corresponding to the control factor (the rotation speed of the first pump 4) (step S7). Based on this control factor, the operation of the first pump 4, which is the controlled device, is controlled (step S8). In other words, the motor 4a is controlled so that the rotation speed of the first pump 4 becomes the value calculated in step S7. Return to step S3 and repeat the subsequent steps.

The control method described above is merely an example. For example, when calculating a control factor according to a variable factor, the function to be set is not limited to the proportional formula as described above. For example, a constant term or other variable term may be provided on the right side of the proportional formula, or a quadratic function, exponential function, or other various functions may be set. In addition, the procedure shown in FIG. 6 is also variable, and the order of steps may be changed as appropriate, some steps may be omitted, or other steps may be added.

The control method is not limited to being applied to sludge treatment facilities as described above. The present invention can be widely applied to facilities that have a "control target value" that needs to be kept close to a target value, a "variation factor" that significantly affects the control target value, and an element that can be manipulated in response to the variation factor and can be considered a "control factor" that can be used to control the control target value.

Figure 7 shows another example (second embodiment) of the configuration of a system capable of implementing the control method of the present invention, and assumes the application of the present invention to a facility that pumps water from a water tank. Water W stored in water tank 10 is pumped out by the operation of pump 11 and sent to the outside. Pump 11 is controlled to turn on and off and to rotate at a speed according to an operation signal input from control unit 12, and functions as a flow rate adjustment unit that adjusts the flow rate of the target object.

A water tank 10 is fitted with a water level gauge 13 that measures the level of the water W in the water tank 10. A flow meter 14 that measures the amount of water W discharged from the pump 11 is provided downstream of the pump 11. Measurement values from the water level gauge 13 and the flow meter 14 are input to the control unit 12 as measurement signals.

In this second embodiment, the discharge volume of the object (water W), i.e., the actual flow rate measured by the flow meter 14, is treated as the value to be controlled. In other words, the flow meter 14 corresponds to the measurement unit to be controlled. The fluctuation factor is the target value of the discharge volume.

The control factor is a value related to the flow rate of the object that can be operated in the flow rate adjustment unit (pump 11), and in this second embodiment, it is the rotation speed input to the pump 11 as an operation signal. That is, for the pump 11, the rotation speed used to control the operation is defined as a function with the target value of the discharge volume as a variable. In addition, the measurement value of the water level gauge 13 is used as the influencing factor. In this case, as in the control in the first embodiment, it is sufficient to set a proportional equation as the function (see FIG. 2 and the above formula (1)). As the coefficient A, a value set in advance in consideration of the relationship between the design rotation speed and discharge volume of the pump 11 can be used. Then, the water level in the water tank 10 (measurement value of the water level gauge 13) is used as an influencing factor, and the correction value C is calculated by taking into account the fluctuation factor (target value of the discharge volume) and the like as necessary. In this way, the rotation speed of the pump 11 is controlled while correcting the proportional coefficient as shown in FIG. 2.

In this type of control, for example, if the demand for water W downstream of the pump 11 increases and the target value (variation factor) is suddenly set higher than the current actual value (control target value) of the discharge rate grasped as the measurement value of the flowmeter 14, the rotation speed (control factor) of the pump 11 can be increased in response to the fluctuation of this variation factor, thereby allowing the actual discharge rate to vary with good tracking relative to the target value of the discharge rate. In addition, at that time, the coefficient can be corrected by taking into account the water level in the water tank 10 as an influencing factor. For example, if the water level in the water tank 10 is high and high water pressure is applied to the inlet of the pump 11, it is conceivable that the amount of water W transported per rotation speed of the pump 11 will be large, and such factors can also be taken into account in the operation control of the pump 11.

The control in this second embodiment can be performed in a procedure similar to that shown in FIG. 6. However, in this second embodiment, the "target value of the control target value" is the fluctuation factor, so step S1 is not required.

Figure 8 shows yet another example (third embodiment) of the configuration of a system capable of implementing the control method of the present invention. This third embodiment also assumes a facility in which water is pumped from a water tank, and much of the configuration is the same as the second embodiment shown in Figure 7, but in this third embodiment, a control valve 15 for adjusting the flow rate is provided downstream of the pump 11, and the discharge amount of water W is controlled by the opening of this control valve 15. The opening of the control valve 15 is controlled by input of an opening signal from the control unit 12. That is, in this third embodiment, the control valve 15 corresponds to the flow rate adjustment unit.

Accordingly, in this third embodiment, the opening of the control valve 15 is treated as the control factor. As in the second embodiment, the controlled value, the fluctuation factor, and the influencing factor are respectively the discharge volume of water W (measured value of the flow meter 14), the target value of the discharge volume, and the water level in the water tank 10 (measured value of the water level meter 13).

In this case, the control factor cannot necessarily be controlled with a simple linear proportional relationship to the fluctuation factor as shown in FIG. 2 or the above formula (1). This is because there is usually no proportional relationship between the valve opening and the flow rate. For example, in a globe valve, the relationship between the opening and the flow rate (flow rate characteristics of a control valve) is as shown in FIG. 9, and in a diaphragm valve, the flow rate characteristics are as shown in FIG. 10. When using such a valve as a flow rate regulator, the control factor as a function with the fluctuation factor as a variable must be set to a function other than a proportional relationship or a linear function, as shown in, for example, FIG. 11 and FIG. 12 (note that FIG. 11 corresponds to the flow rate characteristics of FIG. 9, and FIG. 12 corresponds to the flow rate characteristics of FIG. 10, respectively).

11, when the fluctuation factor is x, the control factor f(x) can be expressed by, for example, the following approximate formula (quadratic function): In the following formula (2), p and q are coefficients, and r is a constant.
f(x)=C×(px ² +qx+r) …Formula (2)

12, the control factor f(x) can be expressed by, for example, the following approximate formula (quartic function): In the following formula (3), p, q, r, and s are coefficients, and t is a constant.
f(x)=C×(px ⁴ +qx ³ +rx ² +sx+t) ...Formula (3)

In either case, by varying the correction value C, the coefficient is adjusted as shown by the dashed or dashed lines in Figures 11 and 12, and this allows the control factor (pump 11 rotation speed) to follow the fluctuation factor (target value of discharge volume), making it possible to quickly bring the controlled value (actual measured value of discharge volume) closer to the target value.

In the above formulas (1) to (3), the correction value C is multiplied by the entire right side of the function, but the setting of the correction value can be changed as appropriate when implementing the invention. For example, a correction value can be set only for some terms, the correction value can be used as an addition or subtraction value rather than a multiplication value, or a different correction value can be used for each term.

The control in this third embodiment can be performed in a procedure similar to that shown in FIG. 6. However, in this third embodiment, as in the second embodiment, the "target value of the controlled value" is the fluctuation factor, and step S1 is unnecessary. In addition, in this third embodiment, since the fluctuation factor and the control factor do not have a simple proportional relationship, it is not sufficient to set the value of one coefficient in step S2, and it may be necessary to set the function itself or to set the coefficients of multiple terms. In addition, with regard to the calculation of the correction value (step S5), it is also conceivable that it may be necessary to set a different correction value for each of the multiple terms.

As described above, in the control method of each of the above embodiments, a control factor, which is a value that can be manipulated to control a control target value, and a fluctuation factor, which is a value other than the control factor that has the greatest effect on the control target value, are defined, and the control factor is controlled according to the fluctuation factor, thereby controlling the control target value. In this way, by controlling the control factor to fluctuate according to the fluctuation factor, the control target value can be controlled with good tracking ability to fluctuations in the fluctuation factor.

In addition, in each embodiment, when controlling the control factor, an influencing factor, which is a value that can affect at least one of the control target value or the control factor, is taken into account. In this way, control can be performed that is suited to the driving conditions at each time.

In addition, in each embodiment, the control factor is defined as a function of the fluctuation factor. In this way, the supply amount can be appropriately calculated by simple calculation processing.

In addition, in each embodiment, a correction value according to the operating status of the equipment is added to the function. In this way, the supply amount can be calculated more appropriately with simple calculation processing.

In addition, in each embodiment, the correction value is calculated using as a variable at least one of an influencing factor, which is a value that can affect at least one of the controlled object value and the controlled factor, and the controlled object value. In this way, control can be performed that is suited to the driving situation at each time.

In some embodiments, the present invention is applied to equipment having a storage section 2 that stores the stored material (dehydrated cake) D, with the amount of stored material D in the storage section 2 being treated as the controlled value, the amount of stored material supplied to the storage section 2 or a value related thereto being treated as the controlled factor, and the amount of stored material D discharged from the storage section 2 or a value related thereto being treated as the variable factor. In this way, the above-mentioned effects can be achieved in equipment having a storage section 2 that stores the stored material D.

In some embodiments, the present invention is applied to equipment equipped with a flow rate adjustment unit (pump 11, adjustment valve 15) that adjusts the flow rate of the object (water) W, and the actual measured value of the flow rate of the object W discharged from the flow rate adjustment unit 11, 15 is treated as the controlled value, the value related to the flow rate of the object that can be manipulated in the flow rate adjustment unit 11, 15 is treated as the control factor, and the target value of the flow rate of the object W discharged from the flow rate adjustment unit 11, 15 is treated as the fluctuation factor. In this way, the above-mentioned action and effect can be achieved in equipment equipped with the flow rate adjustment unit 11, 15 that adjusts the flow rate of the object W.

In addition, the control system of each embodiment is configured to be able to execute the above-mentioned control method, so that the system can achieve the above-mentioned effects.

Therefore, according to the above embodiment, the control object value can be controlled to closely track the target value.

The control method and system of the present invention are not limited to the above-mentioned embodiments, and various modifications can be made without departing from the spirit of the present invention.

2 Storage section 11 Flow rate adjustment section (pump)
15 Flow rate adjustment section (control valve)
D Retention material (dehydrated cake)
W Object (water)

Claims (5)

A control method for controlling a control object value by defining a control factor, which is a value that can be manipulated to control a control object value, and a fluctuation factor, which is a value other than the control factor that has the greatest effect on the control object value, and controlling the control factor in response to the fluctuation factor, comprising:
This applies to equipment equipped with a storage section for storing a substance,
The amount of the stored matter in the storage unit is set as the control target value,
The control factor is the supply amount of the stored material to the storage section or a value related thereto;
The discharge amount of the stored matter from the storage portion or a value related thereto is treated as the fluctuation factor;
The control factor is defined as a function of the fluctuation factor, and a correction value C according to the operation status of the equipment is added to the function,
The correction value is based on C=1,
The correction value is set to a value of C>1 under at least one of the following conditions: when the control object value is smaller than the target value; when the control object value is on a decreasing trend ; and when the control factor is smaller than the designed supply amount of the stored material to the storage unit or a value related thereto ;
A control method characterized in that the correction value is set to a value C<1 under at least one of the following conditions: when the control object value is greater than a target value, when the control object value is tending to increase , and when the control factor is greater than the designed supply amount of the stored material to the storage section or a value related thereto . A control method for controlling a control object value by defining a control factor, which is a value that can be manipulated to control a control object value, and a fluctuation factor, which is a value other than the control factor that has the greatest effect on the control object value, and controlling the control factor in response to the fluctuation factor, comprising:
This applies to equipment equipped with a flow rate regulator that adjusts the flow rate of the target object.
An actual measurement value of a flow rate of the object discharged from the flow rate adjustment unit is set as the control target value,
A value related to a flow rate of an object that can be manipulated by the flow rate adjusting unit is set as the control factor;
A target value of the flow rate of the object discharged from the flow rate adjustment unit is treated as the fluctuation factor;
The control factor is defined as a function of the fluctuation factor, and a correction value C according to the operation status of the equipment is added to the function,
The correction value is based on C=1,
The correction value is set to a value C>1 under at least one of the following conditions: when the control object value is smaller than a target value; when the control object value is on a decreasing trend ; and when the control factor is smaller than a design flow rate of an object that can be operated in the flow rate adjusting unit or a value related thereto ;
A control method characterized in that the correction value is set to a value C<1 under at least one of the following conditions: when the control object value is greater than a target value, when the control object value is on an increasing trend, and when the control factor is greater than the design flow rate of the object that can be operated in the flow adjustment unit or a value related thereto. 3. The control method according to claim 1, further comprising the step of: taking into consideration an influencing factor, which is a value that can influence at least one of the control target value and the control factor, when controlling the control factor. The control method according to claim 1 or 2, wherein the correction value is calculated using at least one of the control object value and an influencing factor, which is a value that can affect at least one of the control object value and the control factor, as a variable. A control system configured to execute the control method according to any one of claims 1 to 4.

Images