Fluid control device, control unit for fluid control device, fluid control method, and storage medium

Abstract

The invention provides a fluid control device, a control unit for the fluid control device, a fluid control method, and a storage medium, which can realize high-speed response and high-precision flow rate control, and an observer determines the flow rate of the fluid based on the deviation between a flow rate measurement value output by a flow rate sensor and a flow rate estimation value output by a flow rate sensor model. A model error estimation value that estimates a model error of the flow sensor model with respect to the flow sensor and a flow error estimation value that estimates a flow error due to a change in the fluid control valve are obtained, and the model error estimation value is input into the flow sensor model. And outputs an estimated value to a feedback controller on the basis of the flow rate error estimated value and a valve flow rate estimated value output by the valve model.

Description

Technical Field

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

[0002] Conventionally, fluid control devices (mass flow controllers) have been used to control the flow rate of fluids flowing through flow channels. As shown in Patent Document 1, this fluid control device comprises a fluid control valve and a flow sensor. Feedback control of the fluid control valve is performed based on the deviation between the flow rate measured by the flow sensor and the set flow rate.

[0003] However, thermal flow sensors have slower response speeds than pressure flow sensors, resulting in longer response times for fluid control. Furthermore, even when the same drive voltage is applied, the opening of a fluid control valve can vary due to hysteresis, aging degradation, and ambient heat. This results in changes in control parameter conditions, causing overshoot in fluid control, making high-precision flow control difficult.

[0004] In addition, as shown in Patent Document 2, a flow control device using an observer can be considered. The observer has an estimation model for estimating the flow through the downstream valve, but it only estimates the flow through the downstream valve and does not take into account the response speed of the flow sensor or the flow error caused by changes in the fluid control valve.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-140292 Patent Document 2: Japanese Patent Application Laid-Open No. 2022-83378 Summary of the Invention

[0006] Therefore, the present invention has been made to solve the above-mentioned problems, and a main object of the present invention is to achieve high-speed response and high-precision flow control.

[0007] That is, the fluid control device of the present invention includes: a fluid control valve for controlling a fluid; a flow sensor for measuring the flow rate of the fluid; and a valve control unit for controlling the fluid control valve, the valve control unit including: an observer for outputting an estimated value, the valve model for estimating a valve flow rate as 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 for simulating the flow sensor; and a feedback controller for performing feedback control of the fluid control valve based on the estimated value obtained by the observer, the observer calculating a model error estimated value for estimating a model error of the flow sensor model relative to the flow sensor and a flow error estimated value for estimating a flow error caused by a change in the fluid control valve based on a deviation between a flow measurement value output by the flow sensor and a flow estimate value output by the flow sensor model, inputting the model error estimated value into the flow sensor model, and outputting the estimated value based on the flow error estimated value and the valve flow estimate value output by the valve model.

[0008] This fluid control device achieves high-speed response by using an observer including 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, an estimated flow error value that estimates the flow rate error caused by changes in the fluid control valve and an estimated model error value that estimates the model error of the flow sensor model relative to the flow sensor are calculated. The estimated model error value is input into the flow sensor model, and an estimated value is output based on the estimated flow error value and the estimated valve flow rate value output by the valve model. This allows for high-precision compensation of both the flow rate error caused by changes in the fluid control valve and the model error of the flow sensor model relative to the flow sensor. As a result, high-speed response and high-precision flow control are achieved.

[0009] As a specific embodiment of the observer, it is preferred that the observer includes: 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, and outputs the model 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, and outputs the flow error estimation value.

[0010] Preferably, the fluid control device of the present invention further includes a valve model updating unit that updates the valve model of the observer. With this structure, the valve model is updated according to changes in the fluid control valve such as aging, thermal effects, etc., thereby reducing the error between the actual valve and the valve model. As a result, high-precision flow control can be achieved.

[0011] Preferably, the fluid control valve is a piezoelectric valve using a piezoelectric stack. The opening degree of a piezoelectric valve can vary even when the same driving voltage is applied, due to factors such as hysteresis caused by the piezoelectric stack, aging degradation, and ambient heat. By providing feedback of an estimated error value used to estimate flow rate errors caused by variations in the fluid control valve, as in the present invention, flow rate errors resulting from these factors, such as hysteresis, aging degradation, and ambient heat, can be accurately compensated.

[0012] Preferably, the flow sensor is a thermal flow sensor. Thermal flow sensors have a slower response speed than pressure flow sensors. Therefore, by performing control using an observer as in the present invention, the effect can be more pronounced in a fluid control device using a thermal flow sensor.

[0013] In addition, the control unit for a fluid control device of the present invention is a control unit for a fluid control device having a fluid control valve for controlling a fluid and a flow sensor for measuring the flow rate of the fluid, and includes: an observer that outputs an estimated value, having a valve model that estimates a valve flow rate as a 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 a feedback controller that performs feedback control on the fluid control valve based on the estimated value obtained by the observer, the observer calculating a model error estimated value for estimating a model error of the flow sensor model relative to the flow sensor, and a flow error estimated value for estimating a flow error caused by a change in the fluid control valve based on a deviation between a flow measurement value output by the flow sensor and a flow estimate value output by the flow sensor model, inputting the model error estimated value into the flow sensor model, and outputting the estimated value based on the flow error estimated value and the valve flow estimate value output by the valve model.

[0014] Furthermore, the fluid control method of the present invention uses a fluid control device including a fluid control valve for controlling a fluid and a flow sensor for measuring the flow rate of the fluid, wherein an observer and a feedback controller are used, the observer outputting an estimated value, the observer including a valve model for estimating a valve flow rate as a flow rate passing through the fluid control valve based on a control signal input to the fluid control valve, and a flow sensor model for simulating the flow sensor, the feedback controller performing feedback control of the fluid control valve based on the estimated value obtained by the observer, the observer calculating a model error estimated value for estimating a model error of the flow sensor model relative to the flow sensor and a flow error estimated value for estimating a flow error caused by a change in the fluid control valve based on a deviation between a flow measurement value output by the flow sensor and a flow estimate value output by the flow sensor model, the observer inputting the model error estimated value into the flow sensor model, and outputting the estimated value based on the flow error estimated value and the valve flow estimate value output by the valve model.

[0015] Furthermore, a storage medium of the present invention stores a fluid control program for use in 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. The fluid control program causes a computer to function as an observer and a feedback controller, the observer outputting an estimated value and including a valve model for estimating a valve flow rate as a flow rate passing through the fluid control valve based on a control signal input to the fluid control valve, and a flow sensor model for simulating the flow sensor. The feedback controller performs feedback control of the fluid control valve based on the estimated value obtained by the observer. The observer calculates an estimated model error value for estimating a model error of the flow sensor model relative to the flow sensor, and an estimated flow error value for estimating a flow error caused by a change in the fluid control valve, based on a deviation between a measured flow rate value output by the flow sensor and an estimated flow rate value output by the flow sensor model. The model error estimated value is input to the flow sensor model, and the computer outputs the estimated value based on the estimated flow error value and the estimated valve flow rate value output by the valve model.

[0016] In addition, the fluid control program may be distributed electronically or stored on a program storage medium such as a CD, DVD, or flash memory.

[0017] According to the present invention thus constituted, high-speed response can be achieved while performing high-precision flow rate control. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram showing the structure of a liquid material vaporizing device incorporating a fluid control device according to one embodiment of the present invention. Figure 2It is a schematic diagram showing the structure of a flow sensor according to the same embodiment. Figure 3 It is a schematic diagram showing the structure of the vaporizer in the same embodiment. Figure 4 This is a control block diagram showing details of a valve control unit according to the same embodiment. Figure 5 Graphs showing response waveforms in flow rate control according to the conventional example and the present embodiment. Figure 6 It is a graph showing partially enlarged response waveforms in flow rate control of the conventional example and the present embodiment. Figure 7 This is a graph showing the effect of feeding back the model error estimate value to the flow sensor model. Figure 8 This is a graph showing that the flow rate error estimation value can estimate the flow rate error caused by the change of the fluid control valve with high accuracy. Figure 9 It is a control block diagram showing details of a valve control unit according to a modified embodiment. Figure 10 It is a schematic diagram showing a fluid control device according to a modified embodiment. DETAILED DESCRIPTION

[0019] Hereinafter, one embodiment of a vaporizer incorporating the fluid control device of the present invention will be described with reference to the drawings. In addition, for the sake of easy understanding, the following figures are schematically depicted with appropriate omissions or exaggerations. The same components are denoted by the same reference numerals, and description thereof is omitted as appropriate.

[0020] The vaporization device 200 of this embodiment is used, for example, in semiconductor manufacturing processes to vaporize a liquid material (raw material liquid) to generate a material gas (raw material gas) that is supplied to a chamber. Furthermore, the fluid control device of the present invention comprises a liquid flow sensor 2 (hereinafter referred to as flow sensor 2), a fluid control valve 3, and a valve control unit 4, as shown below.

[0021] Specifically, if Figure 1 As shown, vaporization apparatus 200 includes: a vaporizer 201; a liquid material supply line L1 for supplying liquid material to vaporizer 201; a carrier gas supply line L2 for supplying carrier gas to vaporizer 201; and an outflow line L3 for allowing a mixture of carrier gas and material gas to flow out of vaporizer 201. Each device provided in vaporizer 201 and lines L1-L3 can be controlled by a control unit CTL.

[0022] A container 202 storing the liquid material is connected to one end of the liquid material supply line L1 , and a liquid flow sensor 2 for measuring the flow rate of the liquid material is provided between the container 202 and the vaporizer 201 .

[0023] The liquid flow sensor 2 is a thermal flow sensor. Figure 2 As shown, the liquid flow sensor 2 includes a cooling device 22, such as a Peltier element, for cooling a portion of a flow tube 21 through which a liquid material flows; a first temperature detector 23 for detecting the temperature of a cooling region 21a of the flow tube 21; a second temperature detector 24 for feedback control, for detecting the temperature of a portion of the cooling device 22 separated from the flow tube 21; and a third temperature detector 25 for detecting the temperature of an uncooled region of the flow tube 21 upstream of the cooling region 21a. The cooling device 22 is controlled so that the difference (t3-t2) between the temperature t2 detected by the second temperature detector 24 and the temperature t3 detected by the third temperature detector 25 is constant. The first temperature detector 23 measures the temperature change of the liquid material as it flows through the flow tube 21. 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 detector 24 and the temperature t1 detected by the first temperature detector 23.

[0024] Here, the control unit CTL controls the cooling device 22, and the flow rate calculation unit 5 of the control unit CTL calculates the flow rate. In this embodiment, the flow rate calculation unit 5 is provided in the control unit CTL, but may be provided independently of the control unit CTL.

[0025] Furthermore, a mass flow controller (MFC) 203 is provided in the carrier gas supply line L2. This MFC 203 controls the flow rate of a carrier gas, such as nitrogen, supplied to the vaporizer 201. The MFC 203 incorporates a valve, a flow sensor, and a control board (not shown) into a single unit. The MFC 203 controls the valve opening through feedback control based on the deviation between the set flow rate and the flow rate measured by the flow sensor. In this embodiment, the MFC 203 controls the flow rate so that, for example, a fixed flow rate of carrier gas is supplied to the vaporizer 201.

[0026] like Figure 3 As shown, the vaporizer 201 includes a fluid control valve 3 and a vaporization section 204 provided on the downstream side of the fluid control valve 3 .

[0027] The fluid control valve 3 is a piezoelectric valve that utilizes a piezoelectric stack. Specifically, the fluid control valve 3 comprises a metal body 31 with a flow channel formed internally and a valve seat 33 formed on its upper surface; a metal diaphragm structure 32, mounted on the upper surface of the body 31 and comprising a diaphragm 321 that functions as a valve core 34 that engages and disengages the valve seat 33; and a piezoelectric actuator 35, comprised of a piezoelectric stack that drives the diaphragm 321. The piezoelectric actuator 35 adjusts the opening between the valve seat 33 and the valve core 34, thereby controlling the flow rate of the liquid material.

[0028] The side of the main body 31 of the fluid control valve 3 is formed with a liquid inlet P1 for introducing liquid material from the liquid material supply line L1 into the main body 31, and a gas inlet P2 for introducing carrier gas from the carrier gas supply line L2. Furthermore, the liquid material and carrier gas introduced into the main body 31 flow through an internal flow channel and flow into the gas-liquid mixing section, which is the space formed between the upper surface of the main body 31 and the diaphragm structure 32, where they mix. The gas-liquid mixture formed by the liquid material and the carrier gas flows through the internal flow channel and flows out from an outlet P3 opened on the side of the main body 31. The outlet P3 of the fluid 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 provided within the main body 31 to regulate and maintain the temperature within the fluid control valve 3 at a predetermined temperature. For example, the temperature of the fluid control valve 3 is set to be higher than the temperature of the liquid material within the container 202, but lower than the temperature of the vaporization section 204, which vaporizes the liquid material. Specifically, the temperature regulated by the valve heater 36 is set so that the liquid material flowing into the vaporization section 204 is preheated by the fluid control valve 3 to facilitate vaporization, while preventing vaporization of the liquid material within the fluid control valve 3.

[0030] The vaporization unit 204 is configured to vaporize the gas-liquid mixture by heating and reducing its pressure to generate a material gas. Specifically, the vaporization unit 204 includes a nozzle 204a whose flow path diameter increases toward the downstream side, and a vaporization heater 204b that heats the gas-liquid mixture flowing through the nozzle 204a.

[0031] The control unit CTL is a computer having a CPU, internal memory, input / output interfaces, an AD converter, communication components, etc. Furthermore, the control unit CTL functions as the valve control unit 4 described below by coordinating the CPU and peripheral devices according to a fluid control program stored in the internal memory.

[0032] like Figure 4 As shown, 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 performs feedback control on the fluid control valve 3 based on an estimated value obtained by the observer 41 .

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

[0034] Here, valve model 41a simulates the behavior or characteristics of fluid control valve 3, such as its response speed. It can be composed of relational data, such as a lookup table, that represents the relationship between at least the control signal (driving voltage) and the valve flow rate in the initial state of fluid control valve 3. Furthermore, flow sensor model 41b simulates the behavior or characteristics of thermal flow sensor 2, such as its response speed.

[0035] Moreover, the observer 41 calculates a model error estimated value m' of the estimated flow sensor model 41b relative to the model error m of the flow sensor 2, and a flow error estimated value u2' of the estimated flow error u2 caused by the change in the fluid control valve 3, based on the deviation y-y' between the flow measurement value y output by the flow sensor 2 and the flow estimated value y' output by the flow sensor model 41b.

[0036] Furthermore, the observer 41 feeds back the model error estimate m' into the flow sensor model 41b and feeds back an estimated value, obtained based on the flow error estimate u2' and the valve flow rate estimate u' output by the valve model 41a, to the feedback controller 42. In this embodiment, the observer 41 superimposes the flow error estimate u2' on the valve flow rate estimate u' output by the valve model 41a and provides feedback. Alternatively, the observer 41 may multiply the flow error estimate u2' by a gain and superimpose the result on the valve flow rate estimate u'. Furthermore, the observer 41 may filter the flow error estimate u2' or the model error estimate m'. Furthermore, in addition to feeding back the estimated value obtained by superimposing the flow error estimate u2' and the valve flow rate estimate u', the observer 41 may also provide feedback of other estimated values, such as an estimated driving 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 this, 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 41 c that outputs a model error estimated value m′, and a second observer gain unit 41 d that outputs a flow rate error estimated value u2 ′.

[0038] The first observer gain unit 41 c multiplies the deviation y−y′ between the flow rate measurement value y output by the flow rate sensor 2 and the flow rate estimated value y′ output by the flow rate sensor model 41 b by the first observer gain L1 to output a model error estimated value m′.

[0039] Furthermore, the second observer gain unit 41d integrates the deviation y-y' between the flow rate measurement value y output by the flow rate sensor 2 and the flow rate estimated value y' output by the flow rate sensor model 41b using an integrator, multiplies the result by the second observer gain L2, and outputs a flow rate error estimated value u2'.

[0040] Here, the first observer gain L1 is used to compensate for the error in the flow sensor model 41b relative to the flow sensor 2. Furthermore, the second observer gain L2 is used to estimate the flow error u2 caused by changes in the fluid control valve 3. This flow error u2 arises from interference such as hysteresis of the piezoelectric stack, aging degradation, and ambient heat effects.

[0041] These gains L1 and L2 are set to values ​​with larger absolute values ​​on the negative side relative to the control gain of the feedback controller 42. Furthermore, the gains L1 and L2 can be determined through optimization calculations so that the deviation y-y' between the flow rate measurement value y output by the flow rate sensor 2 and the flow rate estimate value y' output by the flow rate sensor model 41b converges within a predetermined time (e.g., within 1 second).

[0042] The feedback controller 42 performs feedback control on the fluid control valve 3 based on the estimated value obtained by the observer 41. Here, the feedback controller 42 performs feedback control on the fluid control valve 3 based on the valve flow rate estimated value u'+u2' superimposed with the flow rate error estimated value u2'. That is, the feedback controller 42 controls the valve flow rate estimated value u'+u2' to be equal to the set flow rate Q set 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] Then refer to Figure 5 and Figure 6 The verification results of the flow rate control of the fluid control device constructed in this manner will be described.

[0044] Figure 5 and Figure 6 The conventional example described above performs feedback control on the fluid control valve based on the flow rate measured by the flow sensor. In the present embodiment, feedback control is performed on the fluid control valve 3 based on the valve flow rate estimate obtained by the observer 41 and superimposed with the flow rate error estimate.

[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). In addition, the response time of the "conventional example" was measured using the flow rate measured by the flow sensor, and the response time of the "present embodiment" was measured using the valve flow rate estimated value obtained by using the observer 41 and superimposed with the flow rate error estimated value. Figure 5 and Figure 6 It can be seen that the response time is significantly shortened compared to the conventional example.

[0046] Next, Figure 7 The effect of feeding back the model error estimated value m' to the flow sensor model 41b is shown. Figure 7 In , set indicates the set flow rate. If the model error estimated value m' is not used, the flow rate estimated value (model) will not match the measured flow rate (y) of the actual flow sensor 2. On the other hand, if the model error estimated value m' is used, the model error of the flow sensor model is compensated, and the flow rate estimated value y' (in Figure 7 y_hat) is consistent with the measured flow rate (y) of the physical flow sensor 2.

[0047] also, Figure 8 This shows that the flow error estimate u2' can estimate the flow error u2 caused by the change of the fluid control valve 3 with high accuracy. When the flow error (u2) is set to 10% of the full scale flow, the flow error estimate u2' (at Figure 8 is u2_hat) which is consistent with the flow error (u2).

[0048] (Effects of this embodiment) The fluid control device 100 of this embodiment, thus configured, achieves high-speed response by using an observer 41 comprising a valve model 41a that estimates the valve flow rate u, or the flow rate of the fluid control valve 3, and a flow rate sensor model 41b that simulates the flow rate sensor 2. Furthermore, an estimated model error value m', which estimates the model error m of the flow rate sensor model relative to the flow rate sensor 2, and an estimated flow rate error value u2', which estimates the flow rate error u2 caused by changes in the fluid control valve 3, are calculated. These estimated model error values ​​are input into the flow rate sensor model, and the estimated flow rate error value u2' is added to the estimated valve flow rate value u' output by the valve model 41a. This allows for high-precision compensation of both the flow rate error u2 caused by changes in the fluid control valve 3 and the model error m of the flow rate sensor model 41b relative to the flow rate sensor 2. As a result, high-speed response and high-precision flow rate control are achieved.

[0049] (Other Implementation Methods) For example, based on the structure of the above embodiment, Figure 9 As shown, the system further includes a valve model updating unit 43 for updating the valve model 41a of the observer 41. The valve model updating unit 43 updates the valve model 41a in accordance with changes in the fluid control valve 3 due to age-related degradation or thermal effects. The valve model 41a updated by the valve model updating unit 43 can be selected from a plurality of pre-prepared valve models 41a, or parameters included in the valve model 41a can be modified in accordance with the changes.

[0050] In addition, the first observer gain L1 and the second observer gain L2 can also be obtained by solving the algebraic Riccati equation for each sample to obtain the optimal gains L1 and L2.

[0051] Moreover, if Figure 10 As shown, the fluid control device 100 may also be a so-called thermal mass flow controller, which includes a fluid control valve 3 for controlling the fluid, a flow sensor 2 for measuring the flow rate of the fluid, and a valve control unit 4 for controlling the fluid control valve 3. The structure of the valve control unit 4 is the same as that of the above-described embodiment.

[0052] The fluid control valve 3 is a piezoelectric valve using a piezoelectric stack and 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 using heating resistors. It is located in the measurement flow channel ML and includes a heating resistor 2m on the upstream side and a heating resistor 2n on the downstream side of the measurement flow channel ML, which bypasses the laminar flow element 11 located in the internal flow channel R. Furthermore, the flow sensor 2 includes a flow calculation unit 5 that measures the flow rate through the internal flow channel R based on the difference in resistance between these heating resistors 2m and 2n. The flow calculation unit 5 is provided in the control unit CTL along with the valve control unit 4, but may also be provided independently of the control unit CTL.

[0054] In addition, various modifications and combinations of the embodiments can be made within the scope not departing from the spirit of the present invention. Description of Reference Numerals

[0055] 100 Fluid Control Devices 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 department.

Claims

1. A fluid control device comprising: Fluid control valve, controls fluid; A flow sensor for measuring the flow rate of the fluid; as well as a valve control unit, controlling the fluid control valve, The valve control unit includes: an observer that outputs an estimated value and includes a valve model that estimates a valve flow rate as a 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; as well as a feedback controller that performs feedback control on the fluid control valve based on the estimated value obtained by the observer, The observer calculates a model error estimate value for estimating the model error of the flow sensor model relative to the flow sensor, and a flow error estimate value for estimating the flow error caused by changes in the fluid control valve 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, inputs the model error estimate value into the flow sensor model, and outputs the estimate value based on the flow error estimate value and the valve flow estimate value output by the valve model.

2. The fluid control device according to claim 1, wherein: The observer comprises: 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; and The second observer gain unit 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 second observer gain, and outputs the flow rate error estimation value.

3. The fluid control device according to claim 1 or 2, wherein: The method further includes a valve model updating unit for updating the valve model of the observer.

4. The fluid control device according to any one of claims 1 to 3, wherein: The fluid control valve is a piezoelectric valve using a piezoelectric stack.

5. The fluid control device according to any one of claims 1 to 4, wherein: The flow sensor is a thermal flow sensor.

6. A control unit for a fluid control device, comprising: a fluid control valve for controlling a fluid; and a flow sensor for measuring a flow rate of the fluid; an observer that outputs an estimated value and includes a valve model that estimates a valve flow rate as a 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; as well as a feedback controller that performs feedback control on the fluid control valve based on the estimated value obtained by the observer, The observer calculates a model error estimate value for estimating the model error of the flow sensor model relative to the flow sensor, and a flow error estimate value for estimating the flow error caused by changes in the fluid control valve 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, inputs the model error estimate value into the flow sensor model, and outputs the estimate value based on the flow error estimate value 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 for controlling a fluid and a flow sensor for measuring a flow rate of the fluid, wherein: Using an observer and a feedback controller, The observer outputs an estimated value and includes a valve model for estimating a valve flow rate as a flow rate passing through the fluid control valve based on a control signal input to the fluid control valve, and a flow sensor model for simulating the flow sensor. The feedback controller performs feedback control on the fluid control valve based on the estimated value obtained by the observer. The observer calculates a model error estimate value for estimating the model error of the flow sensor model relative to the flow sensor, and a flow error estimate value for estimating the flow error caused by changes in the fluid control valve 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, inputs the model error estimate value into the flow sensor model, and outputs the estimate value based on the flow error estimate value and the valve flow estimate value output by the valve model.

8. A storage medium storing a fluid control program for use in 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, wherein: The fluid control program enables the computer to function as an observer and feedback controller. The observer outputs an estimated value and includes a valve model for estimating a valve flow rate as a flow rate passing through the fluid control valve based on a control signal input to the fluid control valve, and a flow sensor model for simulating the flow sensor. The feedback controller performs feedback control on the fluid control valve based on the estimated value obtained by the observer. The observer calculates a model error estimate value for estimating the model error of the flow sensor model relative to the flow sensor, and a flow error estimate value for estimating the flow error caused by changes in the fluid control valve 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, inputs the model error estimate value into the flow sensor model, and outputs the estimate value based on the flow error estimate value and the valve flow estimate value output by the valve model.

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