Control device

Abstract

To make it easier to approximate nonlinear characteristics using broken lines.SOLUTION: An instruction circuit 104 causes a control circuit 102 to control a device 121 with each of a plurality of selective control values selected by a selection circuit 103. An acquisition circuit 105 acquires measured values that measure a state of each of controlled objects controlled by the device 121 as a result of the control circuit 102 controlling the device 121 with each of the plurality of selective control values. A correction circuit 106 determines, for each of the plurality of selective control values, a correction value for making a relation between each of the plurality of selective control values and the state of each of the controlled objects be linear, from a relation between each of the plurality of selective control values and the measured value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control device for controlling an object having a nonlinear characteristic. [Background technology]

[0002] There are cases where the control characteristics of a control target are nonlinear. It is generally difficult to control a target with nonlinear characteristics. To improve controllability, there is a technology that approximates nonlinear characteristics with a broken line (broken line approximation) so that the target can be treated as a linear control target (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-097735 A Summary of the Invention [Problem to be solved by the invention]

[0004] Currently, piecewise linear approximation is done manually. However, piecewise linear approximation is very time-consuming because, for example, the control characteristics differ depending on the controlled object, and piecewise linear approximation must be done one by one. For example, it can take about an hour to perform a piecewise linear approximation of the characteristics of one valve.

[0005] The present invention has been made to solve the above problems, and has an object to make it possible to more easily approximate nonlinear characteristics using broken line segments. [Means for solving the problem]

[0006] The control device of the present invention comprises a memory circuit configured to store a control characteristic indicating the relationship between the state of a controlled object and a control value; a control circuit configured to control an equipment that controls the controlled object with a control value determined based on the control characteristic so that the measured value of the state of the controlled object becomes a set value; a selection circuit configured to select a set number of different selective control values ​​within a control range of the control value; an instruction circuit configured to cause the control circuit to control the equipment with each of the multiple selective control values; an acquisition circuit configured to acquire a measured value measuring each state of the controlled object controlled by the equipment controlled by the control circuit with each of the multiple selective control values; a correction circuit configured to determine, for each of the multiple selective control values, a correction value for making the relationship between each of the multiple selective control values ​​linear for each of the multiple selective control values ​​from the relationship between each of the multiple selective control values ​​and the measured value; and a generation circuit configured to generate a control characteristic that linearly approximates the relationship between the control value and the state of the controlled object based on the correction value determined by the correction circuit for each of the multiple selective control values.

[0007] In one configuration example of the control device, the selection circuit selects different control values ​​at equal intervals within the control range.

[0008] In one configuration example of the control device, the storage circuitry stores the control characteristic generated by the generation circuitry. Effect of the Invention

[0009] As described above, according to the present invention, correction values ​​are calculated from measurement values ​​obtained by controlling an equipment using a plurality of selected control values, and a control characteristic is generated by linear approximation using the calculated correction values, thereby making it easier to linearly approximate non-linear characteristics. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing the configuration of a control device 100 according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a flowchart showing an example of the operation of the control device according to the embodiment of the present invention. [Diagram 3] FIG. 3 is a characteristic diagram showing an example of a control characteristic that indicates the relationship between the state (measured value) of the controlled object and the control value by a broken line approximation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A control device 100 according to an embodiment of the present invention will be described below with reference to Fig. 1. The control device 100 controls a device 121 connected via a network 151 such as a field bus, and controls a control target controlled by the device 121. The state of the control target is measured by a sensor 122 connected via the network 151, and the device 121 is controlled based on the measured value measured by the sensor 122. For example, the control target is a fluid, the device 121 is a valve, and the flow rate of the fluid is measured by the sensor 122.

[0012] The control device 100 includes a memory circuit 101, a control circuit 102, a selection circuit 103, an instruction circuit 104, an acquisition circuit 105, a correction circuit 106, a generation circuit 107, and an input circuit .

[0013] The memory circuit 101 stores a control characteristic indicating the relationship between the state of the controlled object and a control value. The memory circuit 101 stores, for example, a control characteristic indicating the relationship between the flow rate of a fluid and the opening degree (control value) of a valve. The control circuit 102 controls the device 121 that controls the controlled object with the control value determined based on the control characteristic so that the measured value of the state of the controlled object becomes a set value.

[0014] The selection circuit 103 selects a set number of different selected control values ​​within the control range of the control values. For example, a set number input by a person in charge through the operation of an input device (not shown) and accepted by the input circuit 108 can be set as the selected number of the above-mentioned selected control values. The selection circuit 103 can select different control values ​​at equal intervals within the control range. For example, the selection circuit 103 can select valve openings of 0%, 25%, 50%, 75%, and 100% as the selected control values.

[0015] The instruction circuit 104 causes the control circuit 102 to control the device 121 with each of the multiple selected control values ​​selected by the selection circuit 103. The acquisition circuit 105 acquires measured values ​​that measure the state of each of the controlled objects controlled by the device 121 as a result of the control circuit 102 controlling the device 121 with each of the multiple selected control values. The acquisition circuit 105 acquires, for example, a flow rate value measured by the sensor 122.

[0016] The correction circuit 106 determines, for each of the plurality of selective control values, a correction value for making the relationship between each of the plurality of selective control values ​​and the state of each of the controlled objects linear, from the relationship between each of the plurality of selective control values ​​and the measured value.

[0017] The generation circuit 107 generates a control characteristic that approximates the relationship between the control value and the state of the controlled object with a broken line based on the correction value obtained for each of the multiple selected control values ​​by the correction circuit 106. The memory circuit 101 stores the control characteristic generated by the generation circuit 107.

[0018] Next, an example of the operation of the control device 100 will be described with reference to FIG.

[0019] First, in a first step S101, the selection circuit 103 selects a set number of different selected control values ​​within the control range of the control value. For example, the selection circuit 103 selects the openings of a valve, which is the device 121, of 0%, 25%, 50%, 75%, and 100% as the selected control values.

[0020] Next, in a second step S102, the instruction circuit 104 causes the control circuit 102 to control the device 121 with each of the multiple selected control values ​​selected by the selection circuit 103. For example, the instruction circuit 104 instructs the control circuit 102 to set the opening degree of the valve, which is the device 121, to 0%. Next, in a third step S103, the control circuit 102 that has received the instruction transmits a control signal to the valve, which is the device 121, to set the opening degree to 0%.

[0021] Next, in a fourth step S104, the acquisition circuit 105 acquires a measurement value that measures the state of the control target controlled by the device 121 as a result of the control circuit 102 controlling the device 121 with the selected control value. For example, the acquisition circuit 105 acquires a flow rate value output from the sensor 122 that measures the flow rate of a fluid whose flow rate is controlled by a valve that has received a control signal with an opening degree of 0%.

[0022] After the above-mentioned instruction of a selected control value, control using the instructed selected control value, and acquisition of the measured value of the state of the controlled object have been performed for all selected control values ​​selected by the selection circuit 103 (yes in the fifth step S105), in the sixth step S106, the correction circuit 106 calculates a correction value for each of the multiple selected control values ​​from the relationship between each of the multiple selected control values ​​and the measured value, to make the relationship between each of the multiple selected control values ​​and each of the states of the controlled objects linear.

[0023] For example, if the relationship between valve opening and flow rate is linear, then when the valve is opened 0%, the flow rate will be 0% of the maximum flow rate, when the valve is opened 25%, the flow rate will be 25% of the maximum flow rate, when the valve is opened 50%, the flow rate will be 50% of the maximum flow rate, and when the valve is opened 100%, the flow rate will be 100% of the maximum flow rate.

[0024] In contrast, if measured flow rates are obtained for each valve opening (%) as shown in Table 1, and the measured flow rate is 15% smaller than the linear case at an opening of 25% and 15% larger than the linear case at an opening of 75% as shown in Table 2, a correction value can be found for each valve opening (%).

[0025] [Table 1]

[0026] Next, in a seventh step S107, the generation circuit 107 generates a control characteristic that approximates the relationship between the control value and the state of the controlled object with a broken line based on the correction value obtained for each of the multiple selected control values ​​by the correction circuit 106. The control characteristic generated by the generation circuit 107 is stored in the memory circuit 101.

[0027] Here, an example of calculating the correction value for the broken line approximation will be described. For example, the correction value L of the broken line approximation obtained using N selected control values ​​is n can be calculated using the following formula (1).

[0028]

number

[0029] Here, L n is the correction value for the nth selected control value among the N selected control values. Also, MV 1 ,MV 2 , M.V. n , , MV N are the N selected control values. 1 ,T 2 , T n , ,T N are the measurements taken corresponding to the N selected control values.

[0030] Correction value L obtained for linear relationship n By correcting with , it is possible to obtain a control characteristic that shows the relationship between the state (measured value) of the controlled object and the control value as a broken line approximation, as shown by the solid line in FIG.

[0031] The control device according to the above-mentioned embodiment may be a computer device including a CPU (Central Processing Unit), a main storage device, an external storage device, a network connection device, etc., and each of the above-mentioned functions may be realized by the CPU operating (executing) a program deployed in the main storage device. The above-mentioned program is a program for causing a computer to execute each of the functions shown in the above-mentioned embodiment. The network connection device connects to a network. Also, each function may be distributed to multiple computer devices.

[0032] The control device according to the above-mentioned embodiment can also be configured by a programmable logic device (PLD) such as a field-programmable gate array (FPGA). For example, the logic element of the FPGA can be provided with each of the above-mentioned circuits to function as a control device. Each of the memory circuit, control circuit, selection circuit, instruction circuit, acquisition circuit, correction circuit, and generation circuit can be written into the FPGA by connecting a predetermined writing device. Furthermore, each of the above-mentioned circuits written into the FPGA can be confirmed by a writing device connected to the FPGA.

[0033] As described above, according to the present invention, correction values ​​are calculated from measurement values ​​obtained by controlling an equipment using a plurality of selected control values, and a control characteristic is generated by linear approximation using the calculated correction values, thereby making it easier to linearly approximate non-linear characteristics.

[0034] It should be noted that the present invention is not limited to the above-described embodiments, and it is apparent that many modifications and combinations can be made by a person having ordinary knowledge in the art within the technical concept of the present invention. [Explanation of symbols]

[0035] 100...control device, 101...memory circuit, 102...control circuit, 103...selection circuit, 104...instruction circuit, 105...acquisition circuit, 106...correction circuit, 107...generation circuit, 108...input circuit, 121...device, 122...sensor, 151...network.

Claims

1. A memory circuit configured to store a control characteristic indicating a relationship between a state of a controlled object and a control value; a control circuit configured to control a device that controls the controlled object with the control value determined based on the control characteristic so that a measured value of a state of the controlled object becomes a set value; a selection circuit configured to select a set number of different selected control values ​​from within the control range of the control values; an instruction circuit configured to cause the control circuit to control the device with each of the plurality of selected control values; an acquisition circuit configured to acquire a measurement value that measures a state of each of the control targets controlled by the device controlled by the control circuit at each of the plurality of selected control values; a correction circuit configured to obtain, for each of the plurality of selected control values, a correction value for making a relationship between each of the plurality of selected control values ​​and a state of each of the controlled objects linear, based on a relationship between each of the plurality of selected control values ​​and the measurement value; a generation circuit configured to generate the control characteristic by linearly approximating the relationship between the control value and the state of the controlled object based on the correction value obtained by the correction circuit for each of the plurality of selected control values; A control device comprising:

2. 2. The control device according to claim 1, The control device wherein the selection circuit selects different control values ​​at equal intervals within the control range.

3. 3. The control device according to claim 1, The storage circuit is a control device that stores the control characteristic generated by the generation circuit.

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