Fluid control apparatus, fluid control apparatus control unit, fluid control method, and fluid control program

Abstract

To make it possible to accurately control a flow rate while realizing a high-speed response.SOLUTION: An observer: obtains a model error estimation value obtained by estimating the model error of a flow rate sensor model with regard to a flow rate sensor, and a flow rate error estimation value obtained by estimating a flow rate error according to a change of a fluid control valve, on the basis of the deviation between a flow rate measurement value outputted from the flow rate sensor and a flow rate estimation value outputted from the flow rate sensor model; inputs the model error estimation value into the flow rate sensor model; and outputs the estimation values to a feedback controller on the basis of the flow rate error estimation value and the valve flow rate estimation value outputted from the valve model.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a fluid control device, a control unit for a fluid control device, a fluid control method, and a fluid control program. [Background technology]

[0002] Conventionally, a fluid control device (mass flow controller) has been used to control the flow rate of a fluid flowing through a flow path. As shown in Patent Document 1, this fluid control device includes a fluid control valve and a flow rate sensor, and is configured to perform feedback control of the fluid control valve based on the deviation between the measured flow rate of the flow rate sensor and a set flow rate.

[0003] However, when the flow sensor is a thermal flow sensor, its response speed is slower than that of a pressure flow sensor, resulting in a longer response time for fluid control. Furthermore, the opening of a fluid control valve changes even when the same drive voltage is applied due to changes in its hysteresis, aging, or thermal influence from the surroundings. As a result, the control parameter conditions change, causing overshooting, for example, in the fluid control, making it difficult to perform accurate flow control.

[0004] As shown in Patent Document 2, a flow control device has been considered that uses an observer having an estimation model for estimating the flow rate passing through a downstream valve, but this merely estimates the flow rate passing through a downstream valve and does not focus on flow rate errors due to changes in the response speed of the flow sensor or the fluid control valve. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-140292 [Patent Document 2] Japanese Patent Application Publication No. 2022-83378 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made to solve the above-mentioned problems, and its main object is to enable accurate flow rate control while realizing high-speed response. [Means for solving the problem]

[0007] That is, the fluid control device according to the present invention comprises a fluid control valve that controls a fluid, a flow sensor that measures the flow rate of the fluid, and a valve control unit that controls the fluid control valve, wherein the valve control unit comprises a valve model that estimates a valve flow rate, which is the flow rate passing through the fluid control valve, based on a control signal input to the fluid control valve, and a flow sensor model that simulates the flow sensor, an observer that outputs an estimated value, and a feedback controller that feedback controls the fluid control valve based on the estimated value obtained by the observer, wherein the observer obtains a model error estimate that estimates a model error of the flow sensor model for the flow sensor based on the deviation between the flow measurement value output by the flow sensor and the flow rate estimate value output by the flow sensor model, and a flow error estimate that estimates a flow rate error due to changes in the fluid control valve, inputs the model error estimate to the flow sensor model, and outputs the estimate based on the flow error estimate and the valve flow rate estimate value output by the valve model.

[0008] According to this fluid control device, a high-speed response can be achieved by using an observer having a valve model that estimates the valve flow rate, which is the flow rate of the fluid control valve, and a flow sensor model that simulates the flow sensor. Furthermore, a flow error estimate that estimates the flow rate error due to changes in the fluid control valve and a model error estimate that estimates the model error of the flow sensor model for the flow sensor are calculated, and the model error estimates are input to the flow sensor model. An estimate is output based on the flow error estimate and the valve flow rate estimate output by the valve model, so that the flow rate error due to changes in the fluid control valve and the model error of the flow sensor model for the flow sensor can be accurately compensated for. As a result, accurate flow control can be achieved while achieving a high-speed response.

[0009] As a specific embodiment of the observer, it is desirable that the observer comprises a first observer gain unit that multiplies the deviation between the flow measurement value output by the flow sensor and the flow estimation value output by the flow sensor model by a first observer gain to output the error estimation value, and a second observer gain unit that multiplies the deviation between the flow measurement value output by the flow sensor and the flow estimation value output by the flow sensor model by a second observer gain to output the model error estimation value.

[0010] The fluid control device of the present invention preferably further comprises a valve model update unit that updates the valve model of the observer. With this configuration, the error between the actual valve and the valve model can be reduced as needed by updating the valve model in accordance with changes in the fluid control valve, such as aging or thermal effects, making it possible to achieve highly accurate flow rate control.

[0011] The fluid control valve is preferably a piezo valve using a piezo stack. The opening of a piezoelectric valve changes even when the same drive voltage is applied due to hysteresis in the piezoelectric stack, deterioration over time, thermal influence from the surroundings, etc. By feeding back an error estimate that estimates the flow rate error due to changes in the fluid control valve as in the present invention, it is possible to accurately compensate for the flow rate error that occurs due to the above-mentioned hysteresis, deterioration over time, thermal influence from the surroundings, etc.

[0012] The flow rate sensor is preferably a thermal flow rate sensor. Since thermal flow sensors have a slower response speed than pressure flow sensors, by using an observer for control as in the present invention, the effects of a fluid control device using a thermal flow sensor can be made even more pronounced.

[0013] Further, a control unit for a fluid control device according to the present invention is a control unit used in a fluid control device having a fluid control valve that controls a fluid and a flow sensor that measures the flow rate of the fluid, and is equipped with: a valve model that estimates a valve flow rate, which is the flow rate passing through the fluid control valve, based on a control signal input to the fluid control valve; and a flow sensor model that simulates the flow sensor, an observer that outputs an estimated value; and a feedback controller that feedback controls the fluid control valve based on the estimated value obtained by the observer, wherein the observer obtains a model error estimate that estimates a model error of the flow sensor model for the flow sensor based on the deviation between the flow measurement value output by the flow sensor and the flow rate estimate value output by the flow sensor model, and a flow error estimate that estimates a flow rate error due to changes in the fluid control valve, and inputs the model error estimate to the flow sensor model, and outputs the estimate based on the flow error estimate and the valve flow rate estimate value output by the valve model.

[0014] Furthermore, a fluid control method according to the present invention is a fluid control method using a fluid control device including a fluid control valve for controlling a fluid and a flow sensor for measuring a flow rate of the fluid, and uses a valve model that estimates a valve flow rate, which is the flow rate passing through the fluid control valve, based on a control signal input to the fluid control valve, and a flow sensor model that simulates the flow sensor, an observer that outputs an estimated value, and a feedback controller that feedback controls the fluid control valve based on the estimated value obtained by the observer, and the observer obtains a model error estimate that estimates a model error of the flow sensor model for the flow sensor based on the deviation between the flow measurement value output by the flow sensor and the flow rate estimate value output by the flow sensor model, and a flow error estimate that estimates a flow rate error due to changes in the fluid control valve, and inputs the model error estimate to the flow sensor model, and outputs the estimate based on the flow error estimate and the valve flow rate estimate value output by the valve model.

[0015] Furthermore, the fluid control program according to the present invention is a fluid control program used in a fluid control device equipped with a fluid control valve for controlling a fluid and a flow sensor for measuring the flow rate of the fluid, and is provided on a computer having a valve model that estimates a valve flow rate, which is the flow rate passing through the fluid control valve, based on a control signal input to the fluid control valve, and a flow sensor model that simulates the flow sensor, and is equipped with a function as an observer that outputs an estimated value, and a function as a feedback controller that feedback controls the fluid control valve based on the estimated value obtained by the observer, and the observer obtains a model error estimate that estimates a model error of the flow sensor model for the flow sensor based on the deviation between the flow measurement value output by the flow sensor and the flow rate estimate value output by the flow sensor model, and a flow error estimate that estimates a flow rate error due to changes in the fluid control valve, and inputs the model error estimate into the flow sensor model, and outputs the estimate based on the flow error estimate and the valve flow rate estimate value output by the valve model.

[0016] The fluid control program may be distributed electronically or may be recorded on a program recording medium such as a CD, DVD, or flash memory. [Effects of the Invention]

[0017] According to the present invention configured in this way, it is possible to realize high-speed response and highly accurate flow rate control. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram showing the configuration of a liquid material vaporization device incorporating a fluid control device according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing the configuration of the flow sensor of the embodiment. [Figure 3] FIG. 2 is a schematic diagram showing the configuration of the vaporizer of the embodiment. [Figure 4] FIG. 2 is a control block diagram showing details of a valve control unit of the embodiment. [Figure 5] 4 is a graph showing response waveforms in flow rate control of a conventional example and the present embodiment. [Figure 6] 10 is a graph showing partially enlarged response waveforms in flow rate control of a conventional example and the present embodiment. [Figure 7] 10 is a graph illustrating the effect of feeding back a model error estimate to a flow sensor model. [Figure 8] 10 is a graph showing that the flow rate error estimated value is able to accurately estimate the flow rate error due to changes in the fluid control valve. [Figure 9] FIG. 10 is a control block diagram showing details of a valve control unit according to a modified embodiment. [Figure 10] FIG. 10 is a schematic diagram showing a fluid control device according to a modified embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of a vaporizer incorporating a fluid control device according to the present invention will be described with reference to the drawings. In addition, in all of the drawings shown below, for the sake of clarity, some parts are omitted or exaggerated as appropriate, and the same components are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0020] The vaporizer 200 according to this embodiment is used, for example, in a semiconductor manufacturing process, and vaporizes a liquid material (raw material liquid) to generate a material gas (raw material gas) to be supplied into a chamber. The fluid control device according to the present invention is configured by a liquid flow rate sensor 2, a fluid control valve 3, and a valve control unit 4, which will be described below.

[0021] 1, the vaporizer 200 includes a vaporizer 201, a liquid material supply line L1 that supplies a liquid material to the vaporizer 201, a carrier gas supply line L2 that supplies a carrier gas to the vaporizer 201, and an outlet line L3 that outputs a mixed gas of the carrier gas and the material gas from the vaporizer 201. The vaporizer 201 and the devices provided on each of the lines L1 to L3 can be controlled by a control unit CTL.

[0022] One end of the liquid material supply line L1 is connected to a tank 202 in which the liquid material is stored, and a liquid flow sensor 2 that measures the flow rate of the liquid material is provided between the tank 202 and the vaporizer 201.

[0023] 2, the fluid flow sensor 2 is a thermal flow sensor. The fluid flow sensor 2 includes a cooling device 22, such as a Peltier element, that cools a portion of a flow pipe 21 through which a liquid material flows, a first temperature detection unit 23 that detects the temperature of a cooled region 21a of the flow pipe 21, a second temperature detection unit 24 for feedback control that detects the temperature of a portion of the cooling device 22 that is distant from the flow pipe 21, and a third temperature detection unit 25 that detects the temperature of a non-cooled region of the flow pipe 21 upstream of the cooled region 21a. The cooling device 22 is controlled so that the difference (t3-t2) between the temperature t2 detected by the second temperature detection unit 24 and the temperature t3 detected by the third temperature detection unit 25 is constant. The first temperature detection unit 23 measures the temperature change when the liquid material flows through the flow pipe 21, and the flow rate of the liquid material is calculated based on the temperature difference (t1-t2) between the temperature t2 detected by the second temperature detection unit 24 and the temperature t1 detected by the first temperature detection unit 23.

[0024] Here, the control of the cooling device 22 described above is performed by the control unit CTL, and the calculation of the flow rate described above is performed by the flow rate calculation section 5 of the control unit CTL. Note that although the flow rate calculation section 5 in this embodiment is provided in the control unit CTL, it may be provided separately from the control unit CTL.

[0025] Additionally, a mass flow controller 203 is provided in carrier gas supply line L2 to control the flow rate of carrier gas such as nitrogen supplied to vaporizer 201. Mass flow controller 203 is a unit in which a valve, a flow rate sensor, and a control board (not shown) are packaged, and the valve opening is controlled by feedback control based on the deviation between a set flow rate and the flow rate measured by the flow rate sensor. Mass flow controller 203 in this embodiment controls the flow rate so that, for example, a constant flow rate of carrier gas is supplied to vaporizer 201.

[0026] As shown in FIG. 3, the vaporizer 201 includes a fluid control valve 3 and a vaporizing section 204 provided downstream of the fluid control valve 3.

[0027] The fluid control valve 3 is a piezo valve using a piezo stack. Specifically, the fluid control valve 3 includes a metal body 31 having a flow path formed therein and a valve seat 33 formed on the upper surface thereof, a metal diaphragm structure 32 provided on the upper surface of the body 31 and equipped with a diaphragm 321 that functions as a valve element 34 that moves toward and away from the valve seat 33, and a piezo actuator 35 made of a piezo stack that drives the diaphragm 321. The opening between the valve seat 33 and the valve element 34 is adjusted by the piezo actuator 35, thereby controlling the flow rate of the liquid material.

[0028] A liquid inlet port P1, through which liquid material is introduced into the body 31 from the liquid material line L1, and a gas inlet port P2, through which carrier gas is introduced into the interior from the carrier gas line L2, are formed on the side of the body 31 of the fluid control valve 3. The liquid material and carrier gas introduced into the body 31 pass through an internal flow path and flow into a gas-liquid mixing section, which is the space formed between the top surface of the body 31 and the diaphragm structure 32, where they are mixed. The gas-liquid mixture of the liquid material and carrier gas passes through the internal flow path and flows out to the outside from an outlet port P3 that opens on the side of the body 31. The outlet port P3 of the control valve 3 is connected to the inlet of the vaporization section 204, which is adjacent to the downstream stage.

[0029] Furthermore, a valve heater 36 is built into the body 31, and the temperature is regulated so that the inside of the fluid control valve 3 is maintained at a predetermined temperature. For example, the temperature of the fluid control valve 3 is set to a temperature higher than that of the liquid material in the tank 202 and lower than that of the vaporizer 204 where the liquid material is vaporized. In other words, the liquid material flowing into the vaporizer 204 is preheated by the fluid control valve 3 so that it is easily vaporized, and the temperature regulated by the valve heater 36 is set so that the liquid material does not vaporize inside the fluid control valve 3.

[0030] Vaporizing unit 204 is configured to heat and reduce the pressure of the gas-liquid mixture to vaporize it and generate a material gas. Specifically, vaporizing unit 204 includes nozzle 204a whose flow path diameter expands downstream, and vaporization heater 204b that heats the gas-liquid mixture flowing inside nozzle 204a.

[0031] The control unit CTL is a computer having a CPU, internal memory, input / output interface, AD converter, communication means, etc. The control unit CTL functions as a valve control unit 4 described below by the CPU and peripheral devices working together in accordance with a fluid control program stored in the internal memory.

[0032] As shown in FIG. 4, the valve control unit 4 includes an observer 41 having models of the fluid control valve 3 and the flow rate sensor 2, and a feedback controller 42 that feedback controls the fluid control valve 3 based on the estimated values ​​obtained by the observer 41.

[0033] The observer 41 outputs an estimated value that is fed back to the feedback controller 42, and includes a valve model 41a that estimates the valve flow rate (u), which is the flow rate of the fluid control valve 3, based on a control signal (e.g., a drive voltage) input to the fluid control valve 3, and a flow sensor model 41b that simulates the flow sensor 2.

[0034] Here, the valve model 41a simulates the behavior or characteristics such as the response speed of the fluid control valve 3, and can be configured by relational data such as a look-up table that shows the relationship between at least the control signal (drive voltage) and the valve flow rate in the initial state of the fluid control valve 3. Furthermore, the flow sensor model 41b simulates the behavior or characteristics such as the response speed of the thermal flow sensor 2.

[0035] Then, based on the deviation y-y' between the flow measurement value y output by the flow sensor 2 and the flow estimate value y' output by the flow sensor model 41b, the observer 41 calculates a model error estimate m' that estimates the model error m of the flow sensor model 41b for the flow sensor 2, and a flow error estimate u2' that estimates the flow error u2 due to changes in the fluid control valve 3.

[0036] The observer 41 also feeds back and inputs the model error estimate m' to the flow sensor model 41b, and feeds back to the feedback controller 42 an estimate obtained based on the flow error estimate u2' and the valve flow rate estimate u' output by the valve model 41a. The observer 41 of this embodiment superimposes the flow error estimate u2' on the valve flow rate estimate u' output by the valve model 41a and feeds it back. The observer 41 may multiply the flow error estimate u2' by a gain and superimpose it on the valve flow rate estimate u'. The observer 41 may also filter the flow error estimate u2' or may filter the model error estimate m'. Furthermore, the observer 41 may feed back other estimates, such as an estimate of a drive voltage, obtained based on the flow error estimate u2' and the valve flow rate estimate u' output by the valve model 41a, in addition to the estimate obtained by superimposing the flow error estimate u2' and the valve flow rate estimate u'. Alternatively, a gain or a filter may be applied to the estimated value fed back from the observer 41 to the feedback controller 42 .

[0037] Here, the observer 41 includes a first observer gain unit 41c that outputs a model error estimated value m', and a second observer gain unit 41d that outputs a flow rate error estimated value u2'.

[0038] The first observer gain unit 41c outputs a model error estimate value m' by multiplying the deviation y-y' between the flow measurement value y output by the flow sensor 2 and the flow estimate value y' output by the flow sensor model 41b by the first observer gain L1.

[0039] In addition, the second observer gain unit 41d integrates the deviation y-y' between the flow measurement value y output by the flow sensor 2 and the flow estimation value y' output by the flow sensor model 41b using an integrator and multiplies it by the second observer gain L2 to output the flow error estimation value u2'.

[0040] Here, the first observer gain L1 compensates for the error of the flow sensor model 41b with respect to the flow sensor 2. The second observer gain L2 estimates the flow error u2 due to changes in the fluid control valve 3. This flow error u2 is generated by disturbances such as hysteresis of the piezo stack, deterioration over time, or the influence of ambient heat.

[0041] These gains L1 and L2 are set to values ​​with large absolute values ​​on the negative side relative to the control gain of the feedback controller 42. The gains L1 and L2 may be determined by optimization calculations so that the deviation y-y' between the measured flow rate value y output by the flow sensor 2 and the estimated flow rate value y' output by the flow sensor model 41b converges within a predetermined time (for example, within one second).

[0042] The feedback controller 42 feedback-controls the fluid control valve 3 based on the estimated value obtained by the observer 41. Here, the feedback controller 42 feedback-controls the fluid control valve 3 based on the valve flow rate estimated value u'+u2' on which the flow rate error estimated value u2' is superimposed. In other words, the feedback controller 42 controls the fluid control valve 3 based on the valve flow rate estimated value u'+u2' superimposed on the set flow rate Q set The fluid control valve 3 is feedback-controlled so that: The feedback controller 42 of this embodiment performs, for example, integral control (I control), but may also perform PID control, state feedback control, or model predictive control (MPC control).

[0043] Next, verification results of flow rate control using the fluid control device configured in this manner will be described with reference to FIGS.

[0044] 5 and 6, the "conventional example" performs feedback control of the fluid control valve based on the flow rate measured by the flow sensor. Meanwhile, the "present embodiment" performs feedback control of the fluid control valve 3 based on the valve flow rate estimated value superimposed with the flow rate error estimated value obtained using the observer 41 described above.

[0045] In this verification, the response time of the flow rate was measured when the set flow rate was changed from 0% to 100% (full-scale flow rate). The response time of the "conventional example" was measured using the measured flow rate of the flow sensor, while the response time of the "present example" was measured using the valve flow rate estimate value superimposed with the flow rate error estimate value obtained using observer 41. As can be seen from Figures 4 and 5, the response time is significantly shorter than that of the conventional example.

[0046] Next, the effect of feeding back and inputting the model error estimate m' to the flow sensor model 41b is shown in Figure 7. When the model error estimate m' is not used, the flow rate estimate (model) and the measured flow rate (y) of the actual flow rate sensor 2 do not match. On the other hand, when the model error estimate m' is used, the model error of the flow sensor model is compensated for, and the flow rate estimate y' (y_hat in Figure 7) matches the measured flow rate (y) of the actual flow rate sensor 2.

[0047] Furthermore, Fig. 8 shows that the flow rate error estimated value u2' accurately estimates the flow rate error u2 caused by changes in the fluid control valve 3. When the flow rate error (u2) is set to 10% of the full-scale flow rate, the flow rate error estimated value u2' (u2_hat in Fig. 8) matches the flow rate error (u2) due to the second observer gain L2.

[0048] <Effects of this embodiment> According to the fluid control device 100 of this embodiment configured as described above, a high-speed response can be achieved by using an observer 41 having a valve model 41a that estimates the valve flow rate u, which is the flow rate of the fluid control valve 3, and a flow sensor model 41b that simulates the flow sensor 2. Furthermore, a model error estimate m' that estimates the model error m of the flow sensor model for the flow sensor 2, and a flow error estimate u2' that estimates the flow error u2 due to a change in the fluid control valve 3 are each calculated, and the model error estimates are input to the flow sensor model. The flow error estimate u2' is superimposed on the valve flow rate estimate u' output by the valve model 41a, so that the flow error u2 due to a change in the fluid control valve 3 and the model error m of the flow sensor model 41b for the flow sensor 2 can be accurately compensated for. As a result, it is possible to achieve high-speed response and highly accurate flow control.

[0049] <Other embodiments> For example, in addition to the configuration of the above embodiment, as shown in Fig. 9, a valve model updating unit 43 that updates the valve model 41a of the observer 41 may be further provided. This valve model updating unit 43 updates the valve model 41a in accordance with changes such as aging deterioration or thermal effects of the fluid control valve 3. The valve model 41a updated by the valve model updating unit 43 may be one selected from a plurality of valve models 41a prepared in advance, or may be one in which parameters included in the valve model 41a have been changed in accordance with changes.

[0050] Furthermore, the optimal first observer gain L1 and second observer gain L2 may be determined by solving an algebraic Riccati equation for each sampling.

[0051] 10, the fluid control device 100 may be a so-called thermal mass flow controller, and may include a fluid control valve 3 that controls the fluid, a flow rate sensor 3 that measures the flow rate of the fluid, and a valve control unit 4 that controls the fluid control valve 3. The configuration of the valve control unit 4 is the same as in the above embodiment.

[0052] The fluid control valve 3 is a piezoelectric valve using a piezoelectric stack. The fluid control valve 3 is mounted on a flow path block 10 in which an internal flow path R is formed, and controls the flow rate of the fluid flowing through the internal flow path R.

[0053] The flow sensor 2 is a thermal flow sensor that uses a heating resistor. The flow sensor 2 is provided in a measurement flow path ML that bypasses the upstream and downstream sides of a laminar flow element 11 provided in the internal flow path R, and has an upstream heating resistor 3m and a downstream heating resistor 3n provided in the measurement flow path ML. The flow sensor 3 also has a flow rate calculation unit 5 that measures the flow rate through the internal flow path R from the difference in resistance values ​​of the heating resistors 3m and 3n. The flow rate calculation unit 33 is provided in the control unit CTL together with the valve control unit 4, but may be provided separately from the control unit CTL.

[0054] In addition, various modifications and combinations of the embodiments may be made as long as they do not go against the spirit of the present invention. [Explanation of symbols]

[0055] 100 Fluid control device 2. Flow sensor 3. Fluid Control Valve 4. Valve control unit (control unit) 41 Observer 41a···Valve model 41b Flow sensor model 41c First observer gain section 41d...Second Observer Gain Section 42 Feedback Controller 43 Valve Model Update Section

Claims

1. a fluid control valve for controlling the fluid; a flow sensor for measuring the flow rate of the fluid; a valve control unit that controls the fluid control valve, The valve control unit The fluid control valve is controlled based on a control signal input to the fluid control valve. an observer having a valve model that estimates a valve flow rate, which is a flow rate passing through the valve, and a flow rate sensor model that simulates the flow rate sensor, and that outputs an estimated value; a feedback controller that feedback-controls the fluid control valve based on the estimated value obtained by the observer, The observer calculates a model error estimate that estimates a model error of a flow sensor model for the flow sensor based on the deviation between the flow measurement value output by the flow sensor and the flow estimate value output by the flow sensor model, and a flow error estimate that estimates a flow error due to a change in the fluid control valve, inputs the model error estimate to the flow sensor model, and outputs the estimate based on the flow error estimate and the valve flow estimate value output by the valve model.

2. The observer a first observer gain unit that multiplies a deviation between a flow rate measurement value output by the flow rate sensor and a flow rate estimation value output by the flow rate sensor model by a first observer gain and outputs the model error estimation value; 2. The fluid control device according to claim 1, further comprising a second observer gain unit that multiplies the deviation between the flow rate measurement value output by the flow rate sensor and the flow rate estimation value output by the flow rate sensor model by a second observer gain to output the flow rate error estimation value.

3. The fluid control device according to claim 1 or 2, further comprising a valve model update unit that updates the valve model of the observer.

4. 4. The fluid control device according to claim 1, wherein the fluid control valve is a piezo valve using a piezo stack.

5. The fluid control device according to claim 1 , wherein the flow rate sensor is a thermal flow rate sensor.

6. A control unit used in a fluid control device having a fluid control valve for controlling a fluid and a flow rate sensor for measuring a flow rate of the fluid, an observer that includes a valve model that estimates a valve flow rate, which is a flow rate passing through the fluid control valve, based on a control signal input to the fluid control valve, and a flow rate sensor model that simulates the flow rate sensor, and outputs an estimated value; a feedback controller that feedback-controls the fluid control valve based on the estimated value obtained by the observer, The observer calculates a model error estimate that estimates a model error of a flow sensor model for the flow sensor based on the deviation between the flow measurement value output by the flow sensor and the flow estimate value output by the flow sensor model, and a flow error estimate that estimates a flow error due to a change in the fluid control valve, inputs the model error estimate to the flow sensor model, and outputs the estimate based on the flow error estimate and the valve flow estimate value output by the valve model.

7. A fluid control method using a fluid control device including a fluid control valve that controls a fluid and a flow rate sensor that measures a flow rate of the fluid, an observer that includes a valve model that estimates a valve flow rate, which is a flow rate passing through the fluid control valve, based on a control signal input to the fluid control valve, and a flow rate sensor model that simulates the flow rate sensor, and outputs an estimated value; a feedback controller that feedback-controls the fluid control valve based on the estimated value obtained by the observer, The observer calculates a model error estimate that estimates a model error of a flow sensor model for the flow sensor based on the deviation between the flow measurement value output by the flow sensor and the flow estimate value output by the flow sensor model, and a flow error estimate that estimates a flow error due to a change in the fluid control valve, inputs the model error estimate to the flow sensor model, and outputs the estimate based on the flow error estimate and the valve flow estimate value output by the valve model.

8. A fluid control program used in a fluid control device including a fluid control valve for controlling a fluid and a flow rate sensor for measuring a flow rate of the fluid, a valve model that estimates a valve flow rate, which is a flow rate passing through the fluid control valve, based on a control signal input to the fluid control valve; and a flow rate sensor model that simulates the flow rate sensor, and functions as an observer that outputs an estimated value; a computer is provided with a function as a feedback controller that feedback controls the fluid control valve based on the estimated value obtained by the observer, The observer calculates a model error estimate that estimates a model error of a flow sensor model for the flow sensor based on the deviation between the flow measurement value output by the flow sensor and the flow rate estimate value output by the flow rate sensor model, and a flow rate error estimate that estimates a flow rate error due to a change in the fluid control valve, inputs the model error estimate value to the flow rate sensor model, and outputs the estimate value based on the flow rate error estimate value and the valve flow rate estimate value output by the valve model.

Images