Method for constructing high-precision analytical balance by using anti-magnetic suspension

Abstract

The invention discloses a method for constructing a high-precision analytical balance by using anti-magnetic suspension, and relates to the technical field of energy intelligent control, and the method specifically comprises the following steps: S1, constructing a magnetic suspension oscillator system; s2, constructing a corresponding xyz three-axis system by taking the gravity direction of the vibrator as a z axis and a rod fixed at the center of the vibrator as an x axis, and detecting and solving the rotation frequency of the vibrator around the y axis at the moment; s3, measuring light intensity conversion coefficients of laser light paths at the two ends of the oscillator; and S4, the detection precision of the balance is calculated after correction. According to the analytical balance, an electromagnetic force sensor is generally used to form a closed-loop automatic adjusting system, when a weighed object is added on a scale pan, a position detector signal of the sensor changes, the current in a sensor coil is increased through feedback of an amplifier, the current generates a feedback force in a constant magnetic field to be balanced with an applied load, and the load is balanced with the feedback force. The minimum force which can be measured is 10-13N and corresponds to the mass of 0.1 ng, so that the measurement precision of the analytical balance is improved.

Description

Technical Field

[0001] The invention relates to the field of mechanical resonator systems, and in particular to a method for constructing a high-precision analytical balance by utilizing anti-magnetic suspension. Background Art

[0002] Analytical balances usually use electromagnetic force sensors to form a closed-loop automatic adjustment system. When the object is added to the scale, the position detector signal of the sensor changes, and the current in the sensor coil increases through the amplifier feedback. This current generates a feedback force in a constant magnetic field that is balanced with the added load; at the same time, the voltage value of the current on the measuring resistor Rm is sent to the microprocessor through a filter and an analog / digital converter for data processing to obtain the mass value of the object. However, in actual use, due to the influence of the sensor's corresponding coefficient and low-frequency current noise, the minimum resolution of this type of analytical balance does not exceed 1ug. For experiments with higher mass resolution requirements, such as gravitational measurement, this type of analytical balance cannot be used.

[0003] To this end, we propose a method of constructing a high-precision analytical balance using anti-magnetic suspension to solve the technical problems in the background technology. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies in the prior art, the present invention provides a method for constructing a high-precision analytical balance using anti-magnetic suspension to solve the technical problem of measurement accuracy.

[0006] (II) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] A method for constructing a high-precision analytical balance using anti-magnetic suspension comprises the following steps:

[0009] S1. Construct a magnetic levitation vibrator system;

[0010] S2. Take the gravity direction of the vibrator as the z-axis and the rod fixed at the center of the vibrator as the x-axis, construct the corresponding xyz three-axis system, and detect and solve the rotation frequency of the vibrator around the y-axis at this time;

[0011] S3, measure the light intensity conversion coefficient of the laser light path at both ends of the oscillator; S4, calculate the detection accuracy of the balance after correction.

[0012] Preferably, in step S1, a magnetic field B is generated at the small magnet by a large magnet. 1 (z), the attraction generated by the large magnet is equal to the gravity of the small magnet. The calculation formula is as follows:

[0013]

[0014] Among them, M 2 is the magnetization intensity of the small magnet, m is the mass of the small magnet, V 1 is the volume of the small magnet.

[0015] Preferably, based on the principle of anti-magnetic suspension, a magnetic field B generated by a small magnet at the anti-magnetic material is used. 2 (x), interacts with the diamagnetic material to obtain the diamagnetic potential energy U(x) of the small magnet. The calculation formula of the diamagnetic potential energy U(x) under vacuum conditions is as follows:

[0016]

[0017] Where χ is the magnetic susceptibility of the diamagnetic material, μ 0 =4π×10 -7 N / A 2 is the vacuum permeability, V 2 is the volume of the diamagnetic material. The formula here is applicable to the xyz directions, not just the x direction.

[0018] Preferably, the calculation formula of the eigenfrequency of the vibrator rotating around the y-axis is:

[0019]

[0020] Where I represents the moment of inertia of the balance, the moment of inertia of the balance:

[0021]

[0022] Among them, M 1 Indicates that the mass of the suspended magnet is 200 mg, l 1 and l 2 They represent that the side lengths of the vertical axis of the suspended square magnet are 12 mm and 6 mm respectively; M 2 and L represent the mass and length of the thin rod on the side of the suspended magnet, which are 20 mg and 12 cm respectively; m represents the mass of the object to be measured on the balance, which is xx.

[0023] Preferably, the light intensity-displacement conversion coefficient is measured at this time, and in the y direction, it is better than the light blocking rod 3 having a certain translation invariance, and the displacement voltage in the y direction is basically unchanged, and in the z direction, after actual measurement, its conversion coefficient is also more than one order of magnitude smaller than that in the x direction, so it can be considered that the change in the total voltage only reflects the displacement in the x direction.

[0024] Preferably, the resonant frequency ω is obtained by Lorentz fitting 0 =13.077Hz, and at the resonance point ω 0 At, the voltage power spectrum S VV (ω 0)=2.34×10 -5 V 2 / Hz, corresponding to the displacement detection sensitivity

[0025] Angular displacement detection sensitivity

[0026]

[0027] At the resonance point, the force detection sensitivity Minimum force that can be detected Where T min Indicates the measurement time, that is, when the measurement time is 100 seconds, the minimum force that can be measured is 10 -13 N, corresponding to a mass of 0.1ng, which is far beyond the measurement accuracy of the most sensitive analytical balance currently available.

[0028] (III) Beneficial effects

[0029] Analytical balances usually use electromagnetic force sensors to form a closed-loop automatic adjustment system. When the object is added to the scale pan, the position detector signal of the sensor changes, and the current in the sensor coil increases through feedback from the amplifier. This current generates a feedback force in a constant magnetic field that balances the added load. At the same time, the voltage value of the current on the measuring resistor Rm is sent to the microprocessor through a filter and an analog / digital converter for data processing to obtain the mass value of the object. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings.

[0031] Figure 1 This is an overall schematic diagram of a high-precision analytical balance constructed by using anti-magnetic suspension according to the present invention;

[0032] Figure 2 The output voltage power spectrum S of the photoelectric converter of the method for constructing a high-precision analytical balance using anti-magnetic suspension of the present invention is VV picture;

[0033] Figure 3 This is a structural diagram of a support plate in a method for constructing a high-precision analytical balance using anti-magnetic suspension according to the present invention. DETAILED DESCRIPTION

[0034] The embodiment of the present application solves the problem in the prior art that it is difficult for current balances to detect extremely low mass objects by providing a method for constructing a high-precision analytical balance using anti-magnetic levitation. In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for constructing a high-precision analytical balance using anti-magnetic levitation, so as to construct a high-precision magnetic levitation analytical balance, whose mass measurement accuracy exceeds 0.1ng, and the overall size of the device is less than 5cm×10cm×10cm, so as to solve the problem that current balances are difficult to detect extremely low mass objects.

[0035] Example 1

[0036] The technical solution in the embodiment of the present application is to solve the above problems, and the overall idea is as follows:

[0037] In view of the problems existing in the prior art, the present invention provides a method for constructing a high-precision analytical balance using anti-magnetic suspension, comprising the following steps:

[0038] S1. Construct a magnetic levitation vibrator system;

[0039] S2. Take the gravity direction of the vibrator as the z-axis and the rod fixed at the center of the vibrator as the x-axis, construct the corresponding xyz three-axis system, and detect and solve the rotation frequency of the vibrator around the y-axis at this time;

[0040] S3, measure the light intensity conversion coefficient of the laser light path at both ends of the oscillator; S4, calculate the detection accuracy of the balance after correction.

[0041] In step S1, a magnetic field B is generated at the small magnet 3 by the large magnet 1. 1 (z), the attraction force generated by the large magnet 1 is equal to the gravity of the small magnet 3, and the calculation formula is as follows:

[0042]

[0043] Among them, M 2 is the magnetization intensity of the small magnet 3, m is the mass of the small magnet 3, V 1 is the volume of the small magnet 3.

[0044] Based on the principle of anti-magnetic levitation, the magnetic field B generated by a small magnet on the anti-magnetic material is used. 2 (x), interacts with the diamagnetic material to obtain the diamagnetic potential energy U(x) of the small magnet. The calculation formula of the diamagnetic potential energy U(x) under vacuum conditions is as follows:

[0045]

[0046] Where χ is the magnetic susceptibility of the diamagnetic material, μ 0 =4π×10 -7 N / A 2 is the vacuum permeability, V2 is the volume of the diamagnetic material. The formula here is applicable to the xyz direction, not just the x direction;

[0047] The calculation formula of the eigenfrequency of the oscillator rotating around the y-axis is:

[0048]

[0049] Where I represents the moment of inertia of the balance, the moment of inertia of the balance:

[0050]

[0051] Among them, M 1 Indicates that the mass of the suspended magnet is 200 mg, l 1 and l 2 They represent that the side lengths of the vertical axis of the suspended square magnet are 12 mm and 6 mm respectively; M 2 and L represent the mass and length of the thin rod on the side of the suspended magnet, which are 20 mg and 12 cm respectively; m represents the mass of the object to be measured on the balance, which is xx.

[0052] A position change measurement module is built on the suspended magnetic vibrator, using the detection optical path in patent 2021219703555 "A lens-free displacement detection device", and a light-blocking rod fixed on the vibrator. A set of pre-set optical fibers is used, where the optical fiber is connected to the laser for inputting laser light, and the optical fiber is connected to the finished commercial photoelectric converter for receiving laser light. The voltage fluctuation of the photoelectric converter is measured to reflect the movement of the light-blocking plate.

[0053] Since the voltage of the photoelectric converter is proportional to the received light intensity, it is only necessary to directly measure the relationship curve between the movement of the light-blocking sheet and the voltage. By quantitatively moving the optical fiber group in the x direction, the fluctuation of the voltage Vx is measured. In subsequent practical use, the optical fiber group is moved to the position where the voltage is most sensitive to displacement, that is, the red frame in the figure. At this time, the voltage and displacement are approximately linear, so it can be written as ΔVx = ξx·Δx, where Δx represents the displacement of the sheet in the x direction, ΔVx represents the voltage change under the displacement, and ξx represents the voltage-displacement conversion coefficient in the x direction (this formula also holds for the y and z directions).

[0054] like Figure 3 As shown, the light intensity-displacement conversion coefficient is measured at this time. In the y direction, it is better than the light blocking rod 3 having a certain translation invariance, and the displacement voltage in the y direction is basically unchanged. In the z direction, after actual measurement, its conversion coefficient is also more than one order of magnitude smaller than that in the x direction. Therefore, it can be considered that the change in the total voltage only reflects the displacement in the x direction.

[0055] like Figure 2 As shown, the resonant frequency ω is obtained by Lorentz fitting 0=13.077Hz, and at the resonance point ω 0 At, the voltage power spectrum S VV (ω 0 )=2.34×10 -5 V 2 / Hz, corresponding to the displacement detection sensitivity

[0056]

[0057] Angular displacement detection sensitivity

[0058]

[0059] At the resonance point, the force detection sensitivity Minimum force that can be detected Where T min Indicates the measurement time, that is, when the measurement time is 100 seconds, the minimum force that can be measured is 10 -13 N, corresponding to a mass of 0.1ng, which is far beyond the measurement accuracy of the most sensitive analytical balance currently available.

[0060] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present invention.

Claims

1. A method for constructing a high-precision analytical balance using anti-magnetic suspension, characterized in that: The specific steps are as follows: S1. Construct a magnetic levitation vibrator system; S2. Take the gravity direction of the vibrator as the z-axis and the rod fixed at the center of the vibrator as the x-axis, construct the corresponding xyz three-axis system, and detect and solve the rotation frequency of the vibrator around the y-axis at this time; S3, measure the light intensity conversion coefficient of the laser light path at both ends of the oscillator; S4, calculate the detection accuracy of the balance after correction.

2. A method for constructing a high-precision analytical balance using anti-magnetic suspension as claimed in claim 1, characterized in that: In step S1, a magnetic field B1(z) is generated by a large magnet at the small magnet, satisfying that the attraction generated by the large magnet is equal to the gravity of the small magnet. The calculation formula is as follows: Where M2 is the magnetization of the small magnet, m is the mass of the small magnet, and V1 is the volume of the small magnet.

3. A method for constructing a high-precision analytical balance using anti-magnetic suspension as claimed in claim 2, characterized in that: Based on the principle of diamagnetic levitation, the magnetic field B2(x) generated by the small magnet at the diamagnetic material interacts with the diamagnetic material to obtain the diamagnetic potential energy U(x) of the small magnet. The calculation formula of the diamagnetic potential energy U(x) under vacuum conditions is as follows: Where χ is the magnetic susceptibility of the diamagnetic material, μ0 = 4π × 10 -7 N / A 2 is the magnetic permeability of vacuum, V2 is the volume of diamagnetic material, and the formula here is applicable to the xyz directions, not just the x direction.

4. A method for constructing a high-precision analytical balance using anti-magnetic suspension as claimed in claim 3, characterized in that: The calculation formula of the eigenfrequency of the oscillator rotating around the y-axis is: Where I represents the moment of inertia of the balance, the moment of inertia of the balance: Among them, M1 represents the mass of the suspended magnet, which is 200 mg; l1 and l2 represent the side lengths of the vertical axis of the suspended square magnet, which are 12 mm and 6 mm respectively; M2 and L represent the mass and length of the thin rod on the side of the suspended magnet, which are 20 mg and 12 cm respectively; and m represents the mass of the object to be measured on the balance, which is xx.

5. A method for constructing a high-precision analytical balance using anti-magnetic suspension as claimed in claim 4, characterized in that: The resonant frequency obtained by Lorentz fitting is ω0 = 13.077 Hz, and at the resonance point ω0, the voltage power spectrum S VV (ω0)=2.34×10 -5 V 2 / Hz, corresponding to the displacement detection sensitivity Angular displacement detection sensitivity At the resonance point, the force detection sensitivity Minimum force that can be detected Where T min Indicates the measurement time, that is, when the measurement time is 100 seconds, the minimum force that can be measured is 10 -13 N, corresponds to the mass of 0.1ng.

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