Coriolis force sensor driving control method based on state observation model

Abstract

This invention discloses a Coriolis force sensor drive control method based on a state observation model, specifically comprising: Step 1, establishing an electromechanical coupling dynamic model of the Coriolis force sensor to obtain the transfer function at the first natural frequency of the Coriolis force sensor; Step 2, performing peak detection and phase difference calculation on the actual output signal of the Coriolis force sensor, and then comparing the calculated values ​​with the effective model solution information to form the drive signal of the Coriolis force sensor; Step 3, introducing normalized phase error as measurement information for phase control, used to excite the natural modes of the Coriolis force sensor during transient changes and verify whether the Coriolis force sensor has reached a stable state; Step 4, using the state observation model to estimate the disturbance of the Coriolis force sensor online, and when the coupling disturbance between the fluid and the sensing tube increases, compensating the estimated disturbance value of the Coriolis force sensor online. This method can accurately track the dynamic response changes of the Coriolis force sensor.

Description

Technical Field

[0001] This invention belongs to the field of instrumentation technology, specifically relating to a Coriolis force sensor drive control method based on a state observation model. Background Technology

[0002] With the continuous progress of society and the economy, and the rapid development of various industries, flow meters, as one of the most widely used metering instruments in industrial production and process control, play a crucial role in the accuracy of their measurement results throughout the entire production process. Compared to traditional volumetric flow meters, Coriolis force sensors can directly measure not only the mass flow rate of fluids but also their density, and they possess higher measurement accuracy. Therefore, they are widely used in industrial and agricultural production, scientific research, and foreign trade. Currently, most domestic Coriolis force sensor manufacturers use analog driving formulas. This method directly amplifies the vibration signal detected by the sensor and uses it as the excitation signal through gain control output. Due to its simple control architecture, it is widely used in various models of Coriolis force sensors. However, in the practical application of Coriolis force sensors, this traditional driving formula has significant problems. On the one hand, due to the influence of the experimental environment and the special nature of the measurement, it is easily affected by external noise, which causes the excitation signal in the analog drive to also contain these noise and interference signals, thereby reducing the measurement accuracy of the Coriolis force sensor. On the other hand, when the Coriolis force sensor measures unconventional fluids (such as batch flow or gas / liquid two-phase flow), it cannot accurately track the dynamic response changes of the Coriolis force sensor, thereby reducing the stability of the flow meter's dynamic performance. Summary of the Invention

[0003] The purpose of this invention is to provide a Coriolis force sensor drive control method based on a state observation model. This method converts vibration signals into phasor expression formulas for calculation and suppresses external interference through internal feedback formulas, thereby ensuring accurate tracking of the dynamic response changes of the Coriolis force sensor and exhibiting good tracking performance.

[0004] The technical solution adopted in this invention is a Coriolis force sensor drive control method based on a state observation model, and the specific steps are as follows:

[0005] Step 1: Establish an electromechanical coupling dynamic model of the Coriolis force sensor, and further obtain the transfer function of the Coriolis force sensor at the first natural frequency;

[0006] Step 2: Perform peak detection and phase difference calculation on the actual output signal of the Coriolis force sensor, and then compare the calculated value with the effective model solution information to form the driving signal of the Coriolis force sensor.

[0007] Step 3: Introduce normalized phase error as measurement information for phase control, which is used to excite the inherent mode of the Coriolis force sensor during transient changes and to verify whether the Coriolis force sensor has reached a stable state.

[0008] Step 4: Use the state observation model to estimate the disturbance of the Coriolis force sensor online. When the coupling disturbance between the fluid and the sensing tube increases, the estimated disturbance value of the Coriolis force sensor is compensated online.

[0009] The invention is further characterized in that,

[0010] Step 1 is implemented in the following steps:

[0011] Step 1.1: When the Coriolis force sensor is working normally, according to Newton's laws of motion, we get:

[0012] (1)

[0013] In formula (1), The output force of the exciter. m The equivalent mass including the fluid-sensitive tube, For the equivalent damping of the sensing tube, k The equivalent stiffness of the two sensitive tubes, t represents the displacement of the sensing tube, and t represents time.

[0014] in,

[0015] The output force of the exciter is expressed as:

[0016] (2)

[0017] The output voltage signal of the Coriolis force sensor is expressed as:

[0018] (3)

[0019] In formulas (2) and (3), and These represent the conductor lengths of the excitation coil and the detection coil, respectively. and These represent the magnetic induction intensity of the excitation magnet and the detection magnet, respectively. The output voltage of the detector. To excite the current of the coil, For the speed of the sensor, k 1 represents the output force coefficient. k 2 represents the output voltage coefficient;

[0020] Step 1.2: Based on the dynamic model shown in formula (1), perform Laplace transform on formulas (2) and (3) to obtain the transfer function at the first natural frequency of the Coriolis force sensor. :

[0021] (4)

[0022] In formula (4), , , , d 1 represents the damping factor of the Coriolis force sensor. The natural angular frequency of the Coriolis force sensor. k 3 is the proportionality coefficient.

[0023] Step 2 is implemented in the following steps:

[0024] Step 2.1: When the Coriolis force sensor is in a stable state, its linear differential equation and the output expression of the Coriolis force sensor are given as follows:

[0025] (5)

[0026] (6)

[0027] In formula (5) d 1 represents the damping factor of the Coriolis force sensor. The natural angular frequency of the Coriolis force sensor. and These are the input signal and the output signal, respectively. k u The input signal coefficients;

[0028] displacement in formula (5) If it is a function of time, then the function , and Rewrite it as a related phasor expression formula:

[0029] (7)

[0030] (8)

[0031] (9)

[0032] in, X 1R and X 1I Time-domain function Corresponding to the real and imaginary parts of the phasor, Time-domain function The vector angle corresponding to the phasor, Im is the imaginary part;

[0033] Substituting equations (7) to (9) into equation (5), the differential equation can be written as a phasor-shaped formula for the real and imaginary parts:

[0034] (10)

[0035] Accordingly, the harmonic excitation signal of the Coriolis force sensor can be expressed as a phasor formula:

[0036] u 1( t )=Im{( U 1R + jU 1I ) e jΦ’(t) (11)

[0037] in, U 1R and U 1I Time-domain function Corresponding to the real and imaginary parts of the phasor, Φ’(t) Time-domain function The vector angle corresponding to the phasor, as shown in formula (10), determines the parameter of the Coriolis force sensor. d 1 and ;

[0038] Step 2.2: Based on the phasor expression formula of the Coriolis force sensor, the reference phasor model is defined by linearization control as follows:

[0039] (12)

[0040] (13)

[0041] in, , , , , and In formula (10) A 1. A 0、 K u , U 1. U 1R and U 1I The corresponding reference quantity, X 1 represents the deflection value of the Coriolis force sensor's sensing tube;

[0042] The expression for the input excitation amplitude of the Coriolis force sensor is as follows:

[0043] (14)

[0044] Step 2.3: Based on the properties of the Laplace transform, transform the transfer function (4) in the time domain to the frequency domain (i.e., Therefore, the transfer function of the Coriolis force sensor can be written as:

[0045] (15)

[0046] To calculate the amplitude response, the transfer function is expanded using the conjugate complex form formula, yielding expressions for the real and imaginary parts:

[0047] (16)

[0048] The formula for the phase control of the Coriolis force sensor is as follows:

[0049] (17)

[0050] Based on equations (14) and (17), the design of the Coriolis force sensor model parameter controller is realized.

[0051] Step 3 is implemented in the following steps:

[0052] Step 3.1, use X 1n , U 1n These are respectively represented as the deflection of the sensing tube. X 1 and excitation force U The vector normalization of 1 is expressed by the following formula:

[0053] (18)

[0054] (19)

[0055] Let the normalized length of the vector be 1. If the vector X 1n and U 1n If the product of the vectors is zero or the diagonals of the parallelogram they form are equal, then the vectors are vectors. X 1n and U 1n It has the orthogonality shown in formula (20):

[0056] (20)

[0057] Step 3.2: Combining the phase angles in formula (20) and formula (17), we obtain:

[0058] (twenty one)

[0059] Step 3.3: Use normalized phase error To replace the phase angle in the steady state, it is expressed as:

[0060] (twenty two)

[0061] As can be seen from the above formula, the normalized phase error is suitable as a measurement variable, and the result of this variable can be used to verify whether the excitation frequency has reached the natural frequency value.

[0062] Step 3.4: To verify whether the Coriolis force sensor has reached a stable state, the excitation signal of the system is... u 1 and output signal y 1. Using phasor signals U 1 and Y 1 indicates that the phase difference between the input and output of the Coriolis force sensor is derived using the normalized phase of the input and output:

[0063] (twenty three)

[0064] In phasor control, the proportional factor K m Used to control phase error The size of the expected error Then the formula for expressing the angular acceleration of the Coriolis force sensor can be written as:

[0065] (twenty four).

[0066] Step 4 is implemented in the following steps:

[0067] Step 4.1: By applying phasor control to the output signal of the Coriolis force sensor, the amplitude and period of the sensor tube's vibration can be obtained. Then, the actual amplitude and the desired amplitude are compared to obtain the input signal of the Coriolis force sensor. The corresponding mathematical formula is as follows:

[0068] (25)

[0069] In the formula, u 0 represents the input after signal synthesis. ζ This represents the error between the expected amplitude and the actual amplitude. f The frequency of the feedback signal, x The desired amplitude of the Coriolis force sensor;

[0070] Step 4.2: The synthesized input signal and the filtered interference observation signal are superimposed as the actual input signal of the Coriolis force sensor, which is then expressed as:

[0071] (26)

[0072] In the formula, u 0、 u 01 These are the input after signal synthesis and the input after compensation, respectively. The disturbance signal estimated by the state observation model. This is the filtered interference signal. ω f , The center frequency and damping coefficient of the bandpass filter are used to observe the interference, and K is the control gain;

[0073] Step 4.3: In practical applications, the actual input signal of the Coriolis force sensor after being subjected to actual interference. u 1 is represented as:

[0074] (27)

[0075] Substituting formula (26) into formula (27), the actual input signal of the Coriolis force sensor is expressed as:

[0076] (28)

[0077] Then, by rearranging formula (28), the actual interference signal of the Coriolis force sensor can be derived:

[0078] (29)

[0079] So, through the actual output signal x 1 and the inverse model of the Coriolis force sensor 1 / G ( s The input signal of the Coriolis force sensor can be estimated, and its expression formula is as follows:

[0080] (30)

[0081] Step 4.4: Input the estimated signal from the Coriolis force sensor. The actual input signal of the expression formula (27) is replaced by the expression formula. u 1. Simultaneously use estimated interference signal Replace actual interference signal The interference signal estimated by the state observation model is then obtained after processing:

[0082] (31).

[0083] The beneficial effects of this invention are:

[0084] (1) The method of the present invention solves the vibration signal of the Coriolis force sensor by digital signal processing, extracts the natural frequency and amplitude parameters of the sensitive tube, and synthesizes the two into a driving signal to excite the flow meter. The external interference is suppressed by the internal feedback formula, thereby ensuring that the dynamic response change of the Coriolis force sensor can be accurately tracked and ensuring that the driving algorithm has good tracking performance and stability.

[0085] (2) The method of the present invention compensates the drive system through the state observer model, avoiding the problem of inaccurate measurement of the Coriolis force sensor under external interference, thereby improving the stability of the Coriolis force sensor and providing engineering practice reference for improving the drive control performance of the Coriolis force sensor.

[0086] (3) The method of this invention takes the driving formula of the Coriolis force sensor as the research object, analyzes the vibration characteristics of the flowmeter through frequency response, and establishes an electromechanical coupling dynamic model of the Coriolis force sensor. At the same time, based on the digital signal processing method of vibration signal, a driving phasor control method for the Coriolis force sensor based on the state observation model is proposed. Attached Figure Description

[0087] Figure 1 This is a schematic diagram of the Coriolis force sensor structure;

[0088] Figure 2 This is a block diagram illustrating the electromechanical coupling dynamics model of the Coriolis force sensor in the method of this invention.

[0089] Figure 3 This is an overall architecture diagram of the driving phasor control method in the present invention;

[0090] Figure 4 This is a schematic diagram of the input and output signals of the Coriolis force sensor under dynamic conditions in the method of the present invention;

[0091] Figure 5 This is a vector normalization diagram of the excitation at the natural frequency in the method of the present invention;

[0092] Figure 6 This is a block diagram illustrating the principle of the driving phasor control method based on the state observation model in this invention.

[0093] Figure 7 It is the amplitude of the signal detected in the drive control experiment;

[0094] Figure 8 It is the amplitude of the drive signal in the drive control experiment.

[0095] In the diagram, 1. exciter, 2. left detector, 3. right detector, 4. sensing tube, 5. housing. Detailed Implementation

[0096] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0097] This invention provides a Coriolis force sensor drive control method based on a state observation model. This method is applied to the exciter and detector of a Coriolis force sensor. Currently, commercially available Coriolis force sensors have similar structural distributions, differing only in sensor shape. Their structural diagrams are shown below. Figure 1 As shown in the figure, 1 is the exciter, 2 is the left detector, 3 is the right detector, 4 is the sensing tube, and 5 is the housing. Since the exciter 1, left detector 2, and right detector 3 within the housing 5 are assembled onto the sensing tube 4, they are considered as a single mass unit for analysis. When the Coriolis force sensor is in a fluid steady state, the damping of the sensing tube 4 is very small and does not change much; therefore, the damping of the sensing tube 4 can be considered a constant. The corresponding Coriolis force sensor dynamic model is as follows: Figure 2 As shown, the specific steps are as follows:

[0098] Step 1: Analyze the vibration characteristics of the Coriolis force sensor through frequency response, establish an electromechanical coupling dynamic model of the Coriolis force sensor, and further obtain the transfer function of the Coriolis force sensor at the first natural frequency.

[0099] Step 1: Follow these steps in detail:

[0100] Step 1.1 When the Coriolis force sensor is working normally, according to Newton's laws of motion, we get:

[0101] (1)

[0102] In formula (1), The output force of the exciter. m The equivalent mass including the fluid-sensitive tube, For the equivalent damping of the sensing tube, k The equivalent stiffness of the two sensitive tubes, t represents the displacement of the sensing tube, and t represents time.

[0103] In practical operation, the Coriolis force sensor sends an alternating current signal to the energized coil of the exciter via an external signal generator. This generates an electromagnetic force under the influence of a magnetic field, which is also the output force of the exciter. The output force of the exciter is expressed as:

[0104] (2)

[0105] It is the electromagnetic force that excites the sensing tube, causing it to vibrate back and forth. This induces an electromotive force (EMF) in the detector, which is called the output voltage signal of the Coriolis force sensor. Its formula is as follows:

[0106] (3)

[0107] In formulas (2) and (3), and These represent the conductor lengths of the excitation coil and the detection coil, respectively. and These represent the magnetic induction intensity of the excitation magnet and the detection magnet, respectively. The output voltage of the detector. To excite the current of the coil, For the speed of the sensor, k 1 represents the output force coefficient. k 2 represents the output voltage coefficient;

[0108] Step 1.2: Based on the dynamic model shown in formula (1), perform Laplace transform on formulas (2) and (3) to obtain the transfer function at the first natural frequency of the Coriolis force sensor. :

[0109] (4)

[0110] In formula (4), , , , d 1 represents the damping factor of the Coriolis force sensor. The natural angular frequency of the Coriolis force sensor. k 3 is the proportionality coefficient.

[0111] Step 2: In practical applications of Coriolis force sensors, the drive system exhibits good stability when measuring a single medium or in a stable fluid state. However, in multi-medium or unstable flow states, the disturbance between the fluid and the sensing tube affects the tracking performance of the drive system. To ensure measurement accuracy under unstable fluid conditions, it is necessary to track the natural frequency of the fluid change within a short period, ensuring that the excitation frequency matches the natural frequency of the sensing tube. Therefore, an effective phasor model is proposed to describe the dynamic vibration behavior of the Coriolis force sensor, and the corresponding control method is as follows: Figure 3 As shown, the actual output signal of the Coriolis force sensor is subjected to peak detection and phase difference calculation, and then the calculated value is compared with the effective model solution information to form the driving signal of the Coriolis force sensor.

[0112] Step 2 is implemented in the following steps:

[0113] Step 2.1: When the Coriolis force sensor is in a stable state, its linear differential equation and the output expression of the Coriolis force sensor are given as follows:

[0114] (5)

[0115] (6)

[0116] In formula (5) d 1 represents the damping factor of the Coriolis force sensor. The natural angular frequency of the Coriolis force sensor. and These are the input signal and the output signal, respectively. k u The input signal coefficients;

[0117] displacement in formula (5) If it is a function of time, then the function , and Rewrite it as a related phasor expression formula:

[0118] (7)

[0119] (8)

[0120] (9)

[0121] in, X 1R and X 1I Time-domain function Corresponding to the real and imaginary parts of the phasor, Time-domain function The vector angle corresponding to the phasor, Im is the imaginary part; substituting equations (7) to (9) into equation (5), the differential equation is written as a phasor-shaped formula with real and imaginary parts:

[0122] (10)

[0123] Accordingly, the harmonic excitation signal of the Coriolis force sensor can be expressed as a phasor formula:

[0124] u 1( t )=Im{( U 1R + jU 1I ) e jΦ’(t) (11)

[0125] in U 1R and U 1I Time-domain function Corresponding to the real and imaginary parts of the phasor, Φ’(t) Time-domain function The vector angle corresponding to the phasor, as can be seen from formula (10), determines the parameter of the Coriolis force sensor. d 1 and .

[0126] Step 2.2: Based on the phasor expression formula of the Coriolis force sensor, the reference phasor model is defined by linearization control as follows:

[0127] (12)

[0128] (13)

[0129] in , , , , and In formula (10) A 1. A 0、 K u , U 1. U 1R and U 1I The corresponding reference quantity, X 1 represents the deflection value of the Coriolis force sensor's sensing tube.

[0130] Due to the uncertainty of fluids, practical Coriolis force sensors exhibit time-varying characteristics, thus the matrix in equation (10)... A 0 and A 1 dependency and The change. Therefore, the expression for the input excitation amplitude of the Coriolis force sensor is:

[0131] (14)

[0132] Step 2.3: Based on the properties of the Laplace transform, transform the transfer function (4) in the time domain to the frequency domain (i.e., Therefore, the transfer function of the Coriolis force sensor can be written as:

[0133] (15)

[0134] To calculate the amplitude response, the transfer function is expanded using the conjugate complex form formula, yielding expressions for the real and imaginary parts:

[0135] (16)

[0136] The formula for the phase control of the Coriolis force sensor is as follows:

[0137] (17)

[0138] Based on equations (14) and (17), the design of the Coriolis force sensor model parameter controller is realized.

[0139] Step 3: Since the phase angle is defined only under steady-state conditions, a normalized phase error can be introduced. Measurement information, used for phase control, is employed to excite the intrinsic modes of the Coriolis force sensor during transient changes.

[0140] Step 3 is implemented in the following steps:

[0141] Step 3.1: Due to normalization, the speed of the sensing tube was not selected. Instead of using the phase error as a measurement variable, the deflection of the sensing tube is adopted. X 1. When the Coriolis force sensor is excited at its natural frequency, if the excitation force... U 1 and the deflection of the sensing tube X 1 exists The phase shifts, then their vector normalization is as follows: Figure 4 As shown, using X 1n , U 1n These are respectively represented as the deflection of the sensing tube. X 1 and excitation force U The vector normalization of 1 is expressed by the following formula:

[0142] (18)

[0143] (19)

[0144] Let the normalized length of the vector be 1. If the vector X 1n and U 1n If the product of the vectors is zero or the diagonals of the parallelogram they form are equal, then the vectors are vectors. X 1n and U 1n It has the orthogonality shown in formula (20):

[0145] (20)

[0146] Step 3.2: Combining the phase angles in formula (20) and formula (17), we obtain:

[0147] (twenty one)

[0148] Step 3.3: Use normalized phase error To replace the phase angle in the steady state, it is expressed as:

[0149] (twenty two)

[0150] As can be seen from the above formula, the normalized phase error is suitable as a measurement variable, and the result of this variable can be used to verify whether the excitation frequency has reached the natural frequency value.

[0151] Step 3.4: To verify whether the Coriolis force sensor has reached a stable state, the excitation signal of the system is... u 1 and output signal y 1. Using phasor signals U 1 and Y 1 indicates, such as Figure 5 As shown, the phase difference between the input and output of the Coriolis force sensor is derived using the normalized phase of the input and output:

[0152] (twenty three)

[0153] In phasor control, the proportional factor K m Used to control phase error The size of the expected error Therefore, the formula for expressing the angular acceleration of the Coriolis force sensor can be written as:

[0154] (twenty four).

[0155] Step 4: In practical applications of the Coriolis force sensor, it is subject to interference from external factors (e.g., density, flow rate, pressure). Changes in these factors not only affect the original vibration characteristics of the Coriolis force sensor but also cause significant changes in its natural frequency, thus affecting the measurement accuracy. Based on digital drive control, this study utilizes a state observation model to estimate the disturbance of the Coriolis force sensor online. When the coupling disturbance between the fluid and the sensing tube increases, the estimated disturbance value of the Coriolis force sensor is compensated online. The corresponding control method architecture is as follows: Figure 6 As shown in the figure x The desired amplitude of the Coriolis force sensor; ζ This represents the error between the expected amplitude and the actual amplitude. f The frequency of the feedback signal; u 0、u 01 These are the input after signal synthesis and the input after compensation, respectively; This is the actual interference signal from the Coriolis force sensor; The input signal is the estimated input signal; The disturbance signal estimated for the state observation model; This is the filtered interference signal; ω f , λ To filter out noise signals from the Coriolis force sensor, the center frequency and damping coefficient of the bandpass filter used for interference observation are adjusted. G ( s ) is the transfer function of the Coriolis force sensor; 1 / G ( s ) is the inverse model of the Coriolis force sensor.

[0156] Step 4 is implemented in the following steps:

[0157] Step 4.1: By applying phasor control to the output signal of the Coriolis force sensor, the amplitude and period of the sensor tube's vibration can be obtained. Then, the actual amplitude and the desired amplitude are compared to obtain the input signal of the Coriolis force sensor. The corresponding mathematical formula is as follows:

[0158] (25)

[0159] In the formula, u 0 represents the input after signal synthesis. ζ This represents the error between the expected amplitude and the actual amplitude. f The frequency of the feedback signal, x The desired amplitude of the Coriolis force sensor;

[0160] Step 4.2: The synthesized input signal and the filtered interference observation signal are superimposed as the actual input signal of the Coriolis force sensor, which is then expressed as:

[0161] (26)

[0162] In the formula, u 0、 u 01 These are the input after signal synthesis and the input after compensation, respectively. The disturbance signal estimated by the state observation model. This is the filtered interference signal. ω f , The center frequency and damping coefficient of the bandpass filter are used to observe the interference, and K is the control gain;

[0163] Step 4.3: In practical applications, the actual input signal of the Coriolis force sensor after being subjected to actual interference. u 1 is represented as:

[0164] (27)

[0165] Substituting formula (26) into formula (27), the actual input signal of the Coriolis force sensor is expressed as:

[0166] (28)

[0167] Then, by rearranging formula (28), the actual interference signal of the Coriolis force sensor can be derived:

[0168] (29)

[0169] So, through the actual output signal x 1 and the inverse model of the Coriolis force sensor 1 / G ( s The input signal of the Coriolis force sensor can be estimated, and its expression formula is as follows:

[0170] (30)

[0171] Step 4.4: Input the estimated signal from the Coriolis force sensor. The actual input signal of the expression formula (27) is replaced by the expression formula. u 1. Simultaneously use estimated interference signal Replace actual interference signal The interference signal estimated by the state observation model is then obtained after processing:

[0172] (31)

[0173] As can be seen from the above formula, the disturbance terms present in the Coriolis force sensor can be estimated using the actual output signal and the inverse model of the controlled object. Therefore, using the state observation model can reduce the influence of external disturbances on the Coriolis force sensor, thereby improving the measurement accuracy of the Coriolis force sensor.

[0174] Adopting such Figure 1 The Coriolis force sensor shown has a sensing tube made of 316L stainless steel with a wall thickness of 2.5 mm and an inner diameter of 32 mm. A two-phase flow experiment (air / liquid flow) was used to verify the effectiveness of the state-observation-based Coriolis force sensor drive control. In the experiment, the German dSPACE real-time simulation system sent a drive control signal to the exciter coil of the Coriolis force sensor, and then input the acquired detector signal into the Simulink Coriolis force sensor density calculation algorithm of the simulation system.

[0175] from Figure 7-8 As can be seen from the amplitudes of the detection signal and the driving signal, both the traditional PID drive and the digital drive method proposed in this invention exhibit significant signal attenuation in gas / liquid two-phase flow. However, the digital drive method proposed in this invention has a larger driving amplitude and a significantly faster system response speed. Therefore, compared to the traditional PID drive formula, the novel digital drive method introduces a digital signal processing system into the entire control loop, performing amplitude control and frequency analysis on the Coriolis force sensor output signal, ensuring that the drive system has good tracking performance when the fluid undergoes sudden changes.

Claims

1. A Coriolis force sensor-driven control method based on a state observation model, characterized in that, The specific steps are as follows: Step 1: Establish an electromechanical coupling dynamic model of the Coriolis force sensor, and further obtain the transfer function of the Coriolis force sensor at the first natural frequency; Step 2: Perform peak detection and phase difference calculation on the actual output signal of the Coriolis force sensor, and then compare the calculated value with the effective model solution information to form the driving signal of the Coriolis force sensor. Step 3: Introduce normalized phase error as measurement information for phase control, which is used to excite the inherent mode of the Coriolis force sensor during transient changes and to verify whether the Coriolis force sensor has reached a stable state. Step 4: Use the state observation model to estimate the disturbance of the Coriolis force sensor online. When the coupling disturbance between the fluid and the sensing tube increases, the estimated disturbance value of the Coriolis force sensor is compensated online. Step 4 is implemented in the following steps: Step 4.1: By applying phasor control to the output signal of the Coriolis force sensor, the amplitude and period of the sensor tube's vibration can be obtained. Then, the actual amplitude and the desired amplitude are compared to obtain the input signal of the Coriolis force sensor. The corresponding mathematical formula is as follows: （25） In the formula, u 0 represents the input after signal synthesis. ζ This represents the error between the expected amplitude and the actual amplitude. f The frequency of the feedback signal, x The desired amplitude of the Coriolis force sensor; Step 4.2: The synthesized input signal and the filtered interference observation signal are superimposed as the actual input signal of the Coriolis force sensor, which is then expressed as: （26） In the formula, u 0、 u 01 These are the input after signal synthesis and the input after compensation, respectively. The disturbance signal estimated by the state observation model. This is the filtered interference signal. ω f , The center frequency and damping coefficient of the bandpass filter are used to observe the interference, and K is the control gain; Step 4.3: In practical applications, the actual input signal of the Coriolis force sensor after being subjected to actual interference. u 1 is represented as: （27） Substituting formula (26) into formula (27), the actual input signal of the Coriolis force sensor is expressed as: （28） Then, by rearranging formula (28), the actual interference signal of the Coriolis force sensor is derived: （29） So, through the actual output signal x 1 and the inverse model of the Coriolis force sensor 1 / G ( s The input signal of the Coriolis force sensor is estimated, and its expression formula is as follows: （30） In the formula, The transfer function of the Coriolis force sensor at its first natural frequency; Step 4.4: Input the estimated signal from the Coriolis force sensor. The actual input signal of the expression formula (27) is replaced by the expression formula. u 1. Simultaneously use estimated interference signal Replace actual interference signal The interference signal estimated by the state observation model is then obtained after processing: （31）。 2. The Coriolis force sensor drive control method based on a state observation model according to claim 1, characterized in that, Step 1 is implemented in the following steps: Step 1.1: When the Coriolis force sensor is working normally, according to Newton's laws of motion, we get: （1） In formula (1), The output force of the exciter. m The equivalent mass including the fluid-sensitive tube, For the equivalent damping of the sensing tube, k The equivalent stiffness of the two sensitive tubes, t represents the displacement of the sensing tube, and t represents time. in, The output force of the exciter is expressed as: （2） The output voltage signal of the Coriolis force sensor is expressed as: （3） In formulas (2) and (3), and These represent the conductor lengths of the excitation coil and the detection coil, respectively. and These represent the magnetic induction intensity of the excitation magnet and the detection magnet, respectively. The output voltage of the detector. To excite the current of the coil, For the speed of the sensor, k 1 represents the output force coefficient. k 2 represents the output voltage coefficient; Step 1.2: Based on the dynamic model shown in formula (1), perform Laplace transform on formulas (2) and (3) to obtain the transfer function at the first natural frequency of the Coriolis force sensor. : （4） In formula (4), , , , d 1 represents the damping factor of the Coriolis force sensor. The natural angular frequency of the Coriolis force sensor. k 3 is the proportionality coefficient.

3. The Coriolis force sensor drive control method based on a state observation model according to claim 2, characterized in that, Step 2 is implemented in the following steps: Step 2.1: When the Coriolis force sensor is in a stable state, its linear differential equation and the output expression of the Coriolis force sensor are given as follows: （5） （6） In formula (5) d 1 represents the damping factor of the Coriolis force sensor. The natural angular frequency of the Coriolis force sensor. and These are the input signal and the output signal, respectively. k u The input signal coefficients; displacement in formula (5) If it is a function of time, then the function , and Rewrite it as a related phasor expression formula: （7） （8） （9） in, X 1R and X 1I Time-domain function Corresponding to the real and imaginary parts of the phasor, Time-domain function The vector angle corresponding to the phasor, Im is the imaginary part; Substituting equations (7) to (9) into equation (5), the differential equation can be written as a phasor-shaped formula for the real and imaginary parts: （10） Accordingly, the harmonic excitation signal of the Coriolis force sensor can be expressed as a phasor formula: u 1( t )=Im{( U 1R + jU 1I ) e jΦ’(t) }(11) in, U 1R and U 1I Time-domain function Corresponding to the real and imaginary parts of the phasor, Φ’(t) Time-domain function The vector angle corresponding to the phasor, as shown in formula (10), determines the parameter of the Coriolis force sensor. d 1 and ; Step 2.2: Based on the phasor expression formula of the Coriolis force sensor, the reference phasor model is defined by linearization control as follows: （12） （13） in, , , , , and In formula (10) A 1. A 0、 , U 1. U 1R and U 1I The corresponding reference quantity, X 1 represents the deflection value of the Coriolis force sensor's sensing tube; The expression for the input excitation amplitude of the Coriolis force sensor is as follows: （14） Step 2.3: Based on the properties of the Laplace transform, transform the transfer function (4) in the time domain to the frequency domain, i.e. Therefore, the transfer function of the Coriolis force sensor can be written as: （15） To calculate the amplitude response, the transfer function is expanded using the conjugate complex form formula, yielding expressions for the real and imaginary parts: （16） The formula for the phase control of the Coriolis force sensor is as follows: （17） Based on equations (14) and (17), the design of the Coriolis force sensor model parameter controller is realized.

4. The Coriolis force sensor drive control method based on a state observation model according to claim 3, characterized in that, Step 3 is implemented in the following steps: Step 3.1, use X 1n , U 1n These are respectively represented as the deflection of the sensing tube. X 1 and excitation force U The vector normalization of 1 is expressed by the following formula: （18） （19） Let the normalized length of the vector be 1. If the vector X 1n and U 1n If the product of the vectors is zero or the diagonals of the parallelogram they form are equal, then the vectors are vectors. X 1n and U 1n It has the orthogonality shown in formula (20): （20） Step 3.2: Combining the phase angles in formula (20) and formula (17), we obtain: （21） Step 3.3: Use normalized phase error To replace the phase angle in the steady state, it is expressed as: （22） As can be seen from the above formula, the normalized phase error is suitable as a measurement variable, and the result of this variable can be used to verify whether the excitation frequency has reached the natural frequency value. Step 3.4: To verify whether the Coriolis force sensor has reached a stable state, the excitation signal of the system is... u 1 and output signal y 1. Using phasor signals U 1 and Y 1 indicates that the phase difference between the input and output of the Coriolis force sensor is derived using the normalized phase of the input and output: （23） In phasor control, the proportional factor K m Used to control phase error The size of the expected error Then the formula for expressing the angular acceleration of the Coriolis force sensor can be written as: （24）。

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