A continuous force value standard device based on planck quantum flattening traceability

Abstract

The application discloses a continuous force value standard device based on Planck quantum flattening traceability. The application comprises an unequal arm balance, a permanent magnet system, an induced voltage synchronous measurement system and a laser interference displacement and speed measurement system. The permanent magnet system is used to generate a standard electromagnetic force of the order of kN, and the electromagnetic force continuously changes by changing the size and direction of the coil current. The induced voltage synchronous measurement system is used to measure the induced voltage generated by the magnetic induction line cut by the coil. The laser interference displacement and speed measurement system is used to measure the displacement and speed of the coil. The unequal arm balance is used to amplify the standard electromagnetic force generated by the coil and acts on the force sensor to be calibrated. The application can trace the generated electromagnetic force to the Planck constant, improve the calibration accuracy, and promote the flattening of the mechanical quantity value measurement traceability.

Description

TECHNICAL FIELD

[0001] The present application relates to a force value standard device for calibrating a force sensor, in particular a continuous force value standard device based on Planck quantum flattening traceability. BACKGROUND

[0002] Metrology refers to a series of activities for realizing unit unification and accurate and reliable quantity value. The purpose of force value metrology is to realize the unification of force value units and ensure accurate and reliable force value. This series of activities includes: accurate measurement of force value / weight in the fields of transportation, aerospace, bridge construction, engineering construction, material testing, biomedicine, etc. by various force / weight sensors; then, accurate measurement of force / weight sensors by high-precision force value standards; finally, force value standards are traced to national standards. The force value standards in these force value metrology activities are a set of force standard devices with value traceability, based on different principles and different accuracies (precisions).

[0003] Force standard machines can be divided into static weight force standard machines [1] , lever force standard machines, hydraulic force standard machines and superimposed force standard machines [2] according to their working principles. The first three are force value standards with force value weights as force sources, which are transmitted by counterforce frames, levers or hydraulic systems and then applied to the measured sensors. The superimposed force standard machine uses a high-precision standard force sensor as a force value standard and a high-precision hydraulic servo control system as a force source. At present, the metrology and calibration of small and medium force values (10N-1MN) still take static weight force standard machines as the basis, and the force value is traced to the weight of the weight. The discreteness of the weight mass and the stability of the gravitational acceleration of the measurement point limit the accuracy and efficiency of the force value metrology traceability.

[0004] In November 2018, the 26th International Measurement Conference (CGPM) passed a historic resolution on the revision of the International System of Units (SI) [3] , which redefined all seven SI base units by determining the basic physical constants [4] . In the new definition, the kilogram is redefined by fixing the value of the Planck constant h [5] , eliminating uncertainty and establishing a quantum standard for mass [6] . The power balance method [7] , energy balance method [8] and silicon ball method are the three mainstream methods for most national metrology institutions to establish the relationship between the kilogram and the Planck constant h, among which the power balance method is the most widely used [9] .

[0005] In summary, in the fully realized quantized definition of international units of measurement, the kilogram, a unit of mass, has been redefined using Planck's constant. To improve the accuracy and efficiency of force measurement traceability, a continuous force standard machine based on standard electromagnetic force, namely the Planck force standard machine, is proposed. Considering the calibration needs and technical capabilities of force sensors on the market, this force standard machine mainly addresses the calibration traceability problem of force sensors in the range of 100N to 100kN under the new definition. It adopts the principle of "power balance method" to trace the standard electromagnetic force back to Planck's constant, achieving flattened traceability of force values.

[0006] References

[0007] [1]HAYASHI T,ZHU J.Evaluation of newly developed 50 N dead-weighttype force standard machine using tuning-fork type force transducer[J].Precision Engineering-Journal of the International Societies for PrecisionEngineering and Nanotechnology,2021,68(158-65.

[0008] [2] Zhu Yongmei, Gao Dongsheng. Current status and development trend of mechanical metrology technical standard devices [J]. Science and Technology Innovation and Application, 2015, (28): 31-32.

[0009] [3] STOCK M, DAVIS R, DE MIRANDES E, et al. The revision of the SI-theresult of three decades of progress in metrology[J]. Metrologia, 2019, 56(2).

[0010] [4]Taylor B,Mohr P J.Letter to the Editor:On the redefinition of thekilogram[J].Metrologia,1999,36(1):63-64.

[0011] [5]Mills I M, Mohr P J, Quinn T J, et al. Redefinition of the kilogram: a decision whose time has come[J]. Metrologia, 2005, 42(2): 71-80.

[0012] [6]Karshenboim S G. On the redefinition of the kilogram and ampere in terms of fundamental physical constants[J]. Physics-Uspekhi, 2006, 49(9): 947-954.

[0013] [7]ROBINSON I A, SCHLAMMINGER S. The watt or Kibble balance: a technique for implementing the new SI definition of the unit of mass[J]. Metrologia, 2016, 53(5): A46-A74.

[0014] [8]ROBINSON I A. Watt and joule balances Foreword[J]. Metrologia, 2014, 51(2): S1-S3.

[0015] [9]SCHLAMMINGER S, HADDAD D, SEIFERT F, et al. Determination of the Planck constant using a watt balance with a superconducting magnet system at the National Institute of Standards and Technology[J]. Metrologia, 2014, 51(2): S15-S24. Summary of the Invention

[0016] To address the limitations of existing force standard machines mentioned in the background section, this invention proposes a continuous force standard device based on Planck quantum flattening traceability. This invention generates a standard electromagnetic force through a permanent magnet system, amplifies it via an unequal-arm balance, and applies it to the sensor to be calibrated. By rationally setting the positions and connections of each component, the displacement of the coil and the induced voltage generated are accurately measured. The entire force standard device for calibrating force sensors has a small footprint, a large measurement range, and can perform continuous measurements, greatly promoting the flattening of mechanical quantity metrological traceability.

[0017] To achieve this objective, the present invention adopts the following technical solution:

[0018] This invention provides a continuous force value standard device based on Planck quantum flattening tracing, the continuous force value standard device including an unequal arm balance, a permanent magnet system, an induced voltage synchronous measurement system, and a laser interferometric displacement velocity measurement system.

[0019] The permanent magnet system is used to generate a standard electromagnetic force on the order of kN. By changing the magnitude and direction of the coil current, a continuously varying electromagnetic force can be obtained.

[0020] The induced voltage synchronous measurement system is used to measure the induced voltage generated by the coil cutting magnetic field lines;

[0021] The laser interferometric displacement-velocity measurement system is used to measure the displacement and velocity of the coil;

[0022] The unequal-arm balance is used to amplify the standard electromagnetic force generated by the coil and apply it to the force sensor to be calibrated.

[0023] Furthermore, the permanent magnet system includes a permanent magnet, an inner yoke, an outer yoke, and the coil;

[0024] The permanent magnets at both ends are symmetrically inserted into the inner and outer yokes relative to the middle permanent magnet; a highly uniform annular magnetic field, i.e., an air gap, is formed between the inner and outer yokes; two suspended coils are placed in the upper and lower air gaps respectively.

[0025] Furthermore, the air gap uniformity is 1.8 × 10⁻⁶. -4 T; The length of a single air gap is 140mm.

[0026] Furthermore, the enameled wire of the coil is connected to a low thermoelectric scanning switch in the synchronous measurement system of the induced voltage.

[0027] Furthermore, the aforementioned induced voltage synchronous measurement system includes a digital multimeter, a programmable Josephson quantum voltage standard system, and a low thermoelectric potential scanning switch;

[0028] The low thermoelectric potential scanning switch is connected in series with the induced voltage output by the coil and the standard voltage generated by the programmable Josephson quantum voltage standard system to compensate for the induced voltage output by the coil.

[0029] There are three digital multimeters connected in parallel to collect the induced voltage output by the compensated coil of the low thermoelectric potential scanning switch.

[0030] Furthermore, the induced voltage synchronous measurement system also includes a rubidium atomic clock, which provides a frequency reference; the output of the rubidium atomic clock is connected to four arbitrary waveform generators; the frequency reference is converted by the four arbitrary waveform generators to obtain the time base required by the field programmable gate array and digital multimeter.

[0031] Furthermore, the field-programmable gate array is used to keep the induced voltage generated by the uniform motion of the coil synchronized with the standard voltage generated by the programmable Josephson quantum voltage standard system.

[0032] Furthermore, the left side of the unequal-arm balance is connected to the permanent magnet system via piezoelectric ceramics and a cross; the right side tray holds the counterweight, and the sensor to be calibrated is fixed below the counterweight.

[0033] Furthermore, the laser interferometric displacement velocity measurement system includes a prism, a laser, and a signal processing circuit, with the prism fixed on the coil frame.

[0034] The beneficial effects of this invention are as follows: The continuous force value standard device based on Planck quantum flattening traceability provided by this invention adopts the power balance method. The electromagnetic force after being amplified by the unequal arm balance will not depend on the local gravitational acceleration. At the same time, it is not necessary to know the lever amplification ratio accurately. By tracing the measured current, voltage and velocity to the quantum reference, the generated electromagnetic force can be traced to Planck's constant, improving the calibration accuracy. At the same time, it greatly promotes the flattening of the traceability of mechanical quantity measurement. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the magnet system design of the Planck standard machine according to an embodiment of this application.

[0036] Figure 2 This is a diagram showing the vertical distribution of the magnetic field in the uniform region of the upper and lower air gaps of the magnet system in an embodiment of this application.

[0037] Figure 3 This is a schematic diagram of the synchronous measurement system for induced voltage according to an embodiment of this application.

[0038] Figure 4 This is a schematic diagram of a laser interferometric displacement velocity measurement system according to an embodiment of this application.

[0039] Figure 5This is a schematic diagram of the overall structure of the Planck standard machine according to an embodiment of this application. Detailed Implementation

[0040] Based on the "power balance method", this application presents a continuous force standard device that enables Planck quantum flattening traceability, including a constant current source, a permanent magnet system, an unequal-arm lever balance, an induced voltage synchronous measurement system, and a laser interferometric displacement velocity measurement system.

[0041] The constant current source in this application is a coil drive source. The permanent magnet system generates a standard electromagnetic force on the order of kN in two modes. By changing the magnitude and direction of the coil current, a continuously varying electromagnetic force can be obtained. In the velocity measurement mode, the induced voltage synchronous measurement system measures the induced voltage generated by the coil cutting magnetic field lines. The laser interferometric displacement-velocity measurement system measures the displacement and velocity of the coil in real time and detects the five degrees of freedom of the coil, reducing collimation error. The generated standard electromagnetic force is amplified by an unequal-arm lever balance and then applied to the force sensor to be calibrated. The value of the amplified electromagnetic force is calculated from the current in the coil, the synchronously measured induced voltage, and the velocity of the coil. Thus, according to the principle of the "power balance method," the amplified electromagnetic force will not depend on local gravitational acceleration. At the same time, it is not necessary to know the exact lever amplification ratio. By tracing the measured current, voltage, and velocity to a quantum reference, the generated electromagnetic force can be traced back to Planck's constant, improving calibration accuracy and greatly promoting the flattening of the traceability of mechanical quantity measurements.

[0042] Figure 1 This is a schematic diagram of the magnet system design of the Planckian standard machine provided in this application embodiment. To reduce heating power and voltage, a permanent magnet system is designed with two air gaps, namely an upper air gap 1.1 and a lower air gap 1.3, and each air gap contains a suspension coil to generate electromagnetic force. The magnet system uses three permanent magnets, and the magnetic flux of each permanent magnet passes through an air gap formed by an inner magnetic yoke 1.5 and an outer magnetic yoke 1.2. Since the north pole of one magnet is opposite to the south pole of the adjacent magnet, the magnetic flux of the two permanent magnets is squeezed against each other, forming a highly uniform and strong magnetic field in the air gap. The magnetic flux directions at the two air gaps are opposite in the radial direction. The three permanent magnets are connected internally and externally by magnetic yokes, and the outer magnetic yoke 1.2 provides near-perfect shielding for the magnet system. Figure 1 The overall structure of the magnet system is rotationally symmetric with respect to the vertical z-axis and vertically symmetric with respect to the x-plane. Two equal permanent magnets, 1.4 and 1.7, are symmetrically inserted into the inner and outer yokes with respect to the central permanent magnet 1.6. Because the magnetic poles are in opposite directions, magnetic flux will pass through the air gap formed by the inner and outer yokes, generating a radial magnetic field in the air gap region. The permanent magnet material in the system is Sm2Co17, and the yoke is made of high-permeability DT4C. Figure 2This is a diagram showing the vertical distribution of the magnetic field in the uniform regions of the upper and lower air gaps of the magnet system. The diagram shows that the uniform regions in both air gaps are 140 mm in diameter, with a uniformity of 1.8 × 10⁻⁶. -4 T.

[0043] Furthermore, in this embodiment, the permanent magnet is made of samarium cobalt; the inner and outer magnetic yokes are made of electrical pure iron; the coil is made of enameled wire; the suspension coil is wound on the coil frame and connected by six aluminum rods; the enameled wire of the suspension coil is led out and connected to the low thermoelectric potential scanning switch in the induced voltage synchronous measurement system.

[0044] Figure 3 This is a schematic diagram of the induced voltage synchronous measurement system provided in this application embodiment. In speed mode, it is necessary to synchronously acquire the induced voltage during the coil's movement. Traditional Σ-Δ samplers, although having a high sampling rate, suffer from high noise and a sampling dead zone problem. To reduce the impact of noise on voltage acquisition, a dead-zone-free, time-resetting, synchronous voltage acquisition system based on three 3458A 3.2 8-bit digital multimeters is designed. Taking a suspension coil 3.5 in the magnet system as an example, the induced voltage generated by its movement and the standard voltage generated by the programmable Josephson quantum voltage standard system (PJVS) are connected in series via a low thermoelectric potential scanning switch 3.6 to compensate for the induced voltage output by the suspension coil. The compensated induced voltage is acquired by an acquisition system consisting of three 3458A 8-bit digital multimeters connected in parallel. A programmable logic array (FPGA) is used to generate a synchronous trigger signal 3.3 to ensure time synchronization between the two voltage signals. Simultaneously, a rubidium clock 3.4 provides a 10MHz frequency reference to ensure time / frequency consistency between different devices in the entire measurement system. The time base required by the FPGA and the 3458A digital multimeter is obtained by conversion using four arbitrary waveform generators 3.1.

[0045] Figure 4This is a schematic diagram of a laser interferometric displacement velocity measurement system provided in an embodiment of this application. A dual-frequency stabilized laser outputs a beam of orthogonally linearly polarized light with frequencies f1 and f2 (assuming f1 > f2). After passing through a beam splitter BS, approximately 10% of the output light is reflected, and the remaining 90% is transmitted. The reflected light is analyzed by an analyzer P1 to generate a beat frequency signal, which is received by a photodetector PD1 and converted into a reference signal with frequencies f1-f2. The transmitted light from the beam splitter BS is incident on a polarizing beam splitter PBS. The polarizing beam splitter PBS reflects the light component with frequency f2 to a reference prism RR1, while the light component with frequency f1 is transmitted through the polarizing beam splitter PBS into a measuring prism RR2. The light components with frequencies f1 and f2 are referred to as the reference light and the measuring light, respectively. The reference light and the measuring light are reflected back to the polarizing beam splitter PBS by two pyramidal prisms, and interfere after passing through an analyzer P2. The interference signal is received by the photodetector PD2 and converted into a measurement signal. When the measuring prism RR2 moves, the frequency of the measurement light changes from f1 to f1+Δf due to the Doppler effect. d Therefore, the frequency of the measured signal becomes f1 + Δf d -f2. After the reference signal and measurement signal are processed by the heterodyne signal processing system, the displacement L of the measuring prism RR2 can be obtained. Since the prism is fixed on the coil frame, this displacement L is the relative displacement of the coil. This method uses high-speed heterodyne laser interferometry based on spatial separation. It introduces spatially separated reference light and measurement light into the optical path, eliminating optical aliasing in the interferometry system, thereby greatly reducing the nonlinear error of the interferometry.

[0046] Figure 5 This is a schematic diagram of the overall structure of the Planck force standard machine provided in this application embodiment. The force standard machine mainly consists of a constant current source 5.4 as a coil drive source, a permanent magnet system 5.2, an unequal-arm lever balance 5.3, an induced voltage synchronous measurement system, and a laser interferometric displacement velocity measurement system. On one side of the unequal-arm lever balance is the force sensor 5.6 to be calibrated and a counterweight 5.5 used to balance the force on the other side. On the other side, a piezoelectric ceramic 5.1 is connected to one end and is connected to the magnet system via a cross, two flexible hinges, and six aluminum rods. By using an unequal-arm lever balance, the standard electromagnetic force is amplified to the kN level. At the same time, combined with the dual-mode measurement principle of the "power balance method", the accurate measurement of the lever amplification ratio is avoided, achieving high-precision and wide-range electromagnetic force calibration.

[0047] The force standard machine proposed in this embodiment has two measurement stages: force measurement mode and speed measurement mode.

[0048] Step one: Perform force measurement. Two coils are supplied with currents of equal magnitude but opposite directions, generating a standard electromagnetic force F in an air gap with a uniform magnetic field.

[0049]

[0050] Where I is the coil current; This is the integral term for the magnetic field.

[0051] Step two, conduct the speed measurement mode. The two coils move at a constant speed v in a uniform magnetic field region. z Vertical motion generates an induced voltage U:

[0052]

[0053] Among them, v z The measurements were obtained using a laser interferometric displacement velocity measurement system. The induced voltage U was measured using an induced voltage synchronous measurement system during coil movement.

[0054] Step 3, eliminate the integral term:

[0055] Fv = UI.

[0056] Since the coil frame can be used in conjunction with a laser interferometry calibration system to eliminate collimation errors, we can obtain:

[0057]

[0058] The coil current I can be accurately obtained by measuring the voltage U′ across the standard resistor R.

[0059] Step four: Trace the electromagnetic force back to Planck's constant h and calibrate the force sensor. Characterize the voltage and resistance in the above equation using the Josephson quantum voltage reference and the quantized Hall resistance reference, respectively. Let the amplification factor of the unequal-arm lever balance be k, then the amplified electromagnetic force F acting on the force sensor is... z ′ is represented as:

[0060]

[0061] Where n, n′, and i are all positive integers representing quantum steps; f is the microwave frequency loaded in the Josephson junction, traceable to a time-frequency reference. z ′ represents the velocity at the counterweight end, i.e., the end of the force sensor being calibrated, and is related to v. z It is in the proportion of 1 / k.

[0062] The above description is merely a specific embodiment of the present invention and is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this patent should be included within the protection scope of the present invention.

Claims

1. A continuous force value standard device based on Planck quantum flattening tracing, characterized in that, This includes an unequal-arm balance, a permanent magnet system, an induced voltage synchronous measurement system, and a laser interferometric displacement velocity measurement system; The permanent magnet system is used to generate a standard electromagnetic force on the order of kN. By changing the magnitude and direction of the coil current, a continuously varying electromagnetic force can be obtained. The induced voltage synchronous measurement system is used to measure the induced voltage generated by the coil cutting magnetic field lines; The laser interferometric displacement-velocity measurement system is used to measure the displacement and velocity of the coil; The unequal-arm balance is used to amplify the standard electromagnetic force generated by the coil and apply it to the force sensor to be calibrated.

2. The continuous force value standard device based on Planck quantum flattening tracing as described in claim 1, characterized in that, The permanent magnet system includes a permanent magnet, an inner yoke, an outer yoke, and the coil. The permanent magnets at both ends are symmetrically inserted into the inner and outer yokes relative to the middle permanent magnet; a highly uniform annular magnetic field, i.e., an air gap, is formed between the inner and outer yokes; two suspended coils are placed in the upper and lower air gaps respectively.

3. The continuous force value standard device based on Planck quantum flattening tracing as described in claim 2, characterized in that, The air gap uniformity is 1.8 × 10⁻⁶. -4 T; The length of a single air gap is 140mm.

4. A continuous force value standard device based on Planck quantum flattening tracing as described in claim 2 or 3, characterized in that, The enameled wire of the coil is connected to the low thermoelectric scanning switch in the synchronous measurement system of the induced voltage.

5. A continuous force value standard device based on Planck quantum flattening tracing as described in claim 1, characterized in that, The aforementioned induced voltage synchronous measurement system includes a digital multimeter, a programmable Josephson quantum voltage standard system, and a low thermoelectric potential scanning switch; The low thermoelectric potential scanning switch is connected in series with the induced voltage output by the coil and the standard voltage generated by the programmable Josephson quantum voltage standard system to compensate for the induced voltage output by the coil. There are three digital multimeters connected in parallel, used to collect the induced voltage output by the compensated coil after the output of the low thermoelectric potential scanning switch.

6. A continuous force value standard device based on Planck quantum flattening tracing as described in claim 5, characterized in that, The induced voltage synchronous measurement system also includes a rubidium atomic clock, which provides a frequency reference; the output of the rubidium atomic clock is connected to four arbitrary waveform generators; the frequency reference is converted by the four arbitrary waveform generators to obtain the time base required by the field programmable gate array and digital multimeter.

7. A continuous force value standard device based on Planck quantum flattening tracing as described in claim 6, characterized in that, The field-programmable gate array is used to keep the induced voltage generated by the uniform motion of the coil synchronized with the standard voltage generated by the programmable Josephson quantum voltage standard system.

8. A continuous force value standard device based on Planck quantum flattening tracing as described in claim 1, characterized in that, The left side of the unequal-arm balance is connected to the permanent magnet system via piezoelectric ceramics and a cross; the right side tray holds the counterweight, and the sensor to be calibrated is fixed below the counterweight.

9. A continuous force value standard device based on Planck quantum flattening tracing as described in claim 1, characterized in that, The laser interferometric displacement velocity measurement system includes a prism, a laser, and a signal processing circuit, with the prism fixed on the coil frame.

Images