CN103364073A - Method and system for measuring micro-vibration by using magnetic field - Google Patents

Abstract

The invention discloses a method for measuring micro-vibration by using a magnetic field. The method comprises the following steps: fixedly connecting a permanent magnet and a micro-vibration tested element; measuring the variable quantity of magnetic field strength through a magnetic field strength measurement device, so as to calculate the minimal angular displacement and linear displacement of the micro-vibration. By using fixed connection of the permanent magnet and a mechanical structure, changes of position and vector direction of a magnetic dipole on the permanent magnet are driven by mechanical vibration. A magnetic field signal detected on a fixed magnetometer changes due to changes of the direction of the magnetic dipole and the position of a magnetic source. The detected change of the magnetic field signal is caused by mechanical vibration, so that micro-vibration of the machine can be measured at high accuracy.

Description

Utilize the method and system of the little vibration of magnetic-field measurement

Technical field

The invention belongs to space satellite remote-sensing flatform research field, specifically, the present invention relates to a kind of method and system of utilizing the little vibration of magnetic-field measurement.

Background technology

Little vibration of spacer remote sensing platform causes the performance degradation of high score imaging device on the spacecraft.In order to suppress little vibration of spacecraft structure spare, the information such as disturbing source that at first will in the vibration test of structural member, need to measure the angular displacement of little vibration of structural member and displacement of the lines, vibration frequency and produce little vibration.Measuring at present the structural member vibration takes accelerometer, laser interferometer etc. to measure little vibration of structural member usually.

The little vibration of spacecraft is the key factor that affects the critical natures such as high precision spacecraft pointing accuracy and high-resolution imaging quality, optical system is very responsive to ambient vibration, little vibration interference comparatively seriously influences the resolution generation of high score remotely sensed image, directly affects the imaging of optical systems quality.

The means of seeking feasible effective ground survey and inflight measurement are one of key points of optical system stability study, high-resolution optics imaging.The measurement of little vibration needs high-precision detection system, adopt at present such as accelerometer, piezoelectric sensor, micromechanical gyro, optics vibration measuring technology, laser interferometer etc., all can't satisfy the measuring accuracy demand of high-resolution camera, particularly high-precision real-time measurement.The measuring accuracy of accelerometer is 10 ^-5-10 ^-6Gal, the angular vibration that can measure is about 10 ^-2Rad, the angular vibration measuring accuracy of piezoelectric sensor are about the rad level; The angle-measurement accuracy of micromechanical gyro also is about the rad level; Optics vibration measuring technology can be measured micron-sized translation, and angle-measurement accuracy is in the rad level; And the high score remote-sensing imaging system need to be better than 10 at present ^-4Measurement and the control accuracy of rad are to reach the imaging level of 0.5 meter face resolution.Therefore, the little angle of throw displacement transducer technology of microvibration measuring active demand high precision.

Summary of the invention

The present invention, has set up magnetic field originally and has transmitted little vibration information measuring system for improving China's high score remote sensing technology according to microvibration measuring precision and the measurement means limitation present situation of China's satellite platform self and remote sensing equipment.Measuring little vibration by magnetic field is a kind of brand-new method, and never the people can expect or hint and can utilize the little vibration of magnetic-field measurement.Measuring system of the present invention and measuring method can be applied to the inflight measurement of spacecraft.Specifically, in order to obtain the high score imaging, when ground test, measure little vibration of optical imaging system, find out vibration source, the vibration isolation; Adopt magnetic field measurement system in little vibration of rail Real-Time Monitoring optical system on the high score imaging satellite, for the clear processing of image provides real-time vibration parameters.This patent makes the horizontal vibration precision of little vibration of measurement be better than 10 nanoscales by the little vibration of high precision magnetic vector detector measurement, and angular vibration is better than 10 ^-4The rad level.

In order to solve the problems of the technologies described above, the technical solution used in the present invention is as follows:

A kind of method of utilizing the little vibration of magnetic-field measurement may further comprise the steps:

Permanent magnet and little vibration measured piece are connected, and measure the change of magnetic field strength amount that the quadrature three parts makes progress by the magnetic field intensity measurement mechanism (preferred vector magnetometer) that arranges around the measured piece;

The change of magnetic field strength amount that measures by the magnetic field intensity measurement mechanism is obtained minimum angular displacement and the displacement of the lines of little vibration by following mathematical relation and formula,

Wherein, minimum angular displacement and displacement of the lines are directly proportional namely with change rate of magnetic density:

$\mathrm{\Δ}{\mathrm{\θ}}_{\min }=K_{\mathrm{\θ}}\frac{\mathrm{\Δ}{B}_r}{B_r}$

$\mathrm{\Δr}=K_r\frac{{\mathrm{\ΔB}}_r}{B_r}$

K θ, Kr are coefficients, and span is respectively 0.28-0.40, and Δ Br can be expressed as Δ Br(t, θ with the variable quantity in the magnetic field of vibration), both represent identical implication in this article, wherein t is the time.

Further, described method can be applicable to measure little vibration of spacecraft.

Further, the Measurement Resolution of magnetometer is better than 0.01nT; Dynamic range: ± 10 ⁶NT; Response frequency: from DC to 5kHz.

A kind of system that utilizes the little vibration of magnetic-field measurement, comprise the permanent magnet that is connected on little vibration measured piece, be arranged on measured piece vector magnetometer on every side, distance between vector magnetometer and the permanent magnet remains between the 1cm-1m, preferred 20-50cm, and the compensation permanent magnet and the data Collection ﹠ Processing System that are used for the compensation high-intensity magnetic field, data Collection ﹠ Processing System and vector magnetometer telecommunication also obtain the change of magnetic field strength amount calculation process of collection minimum angular displacement and the displacement of the lines of the little vibration of measured piece.

Further, the resolution of described vector magnetometer is 0.01NT, and the dynamic range of measurement is ± 10 ⁶NT, response frequency is from DC to 5kHz.

Further, the system of the little vibration of described magnetic-field measurement is used for measuring little vibration of spacecraft.

The present invention utilizes permanent magnet and physical construction fixed, and mechanical vibration drive the change of magnetic dipole position, direction vector on the permanent magnet.This magnetic source position, magnetic dipole are pointed to change and are caused the field signal variation of surveying on the fixing magnetometer.The variation of the field signal that detects is owing to mechanical vibration cause, thereby the accurately little vibration of measurement mechanical.

In addition, magnetic field is transmitted the microvibration measuring technology and is provided new measurement means for the ground microvibration measuring, can be simultaneously satellite in orbit high-precision microvibration measuring is provided.On remote sensing and explorer satellite, obtain accurate little vibration information with this technology by ground with at rail, carry out again pixel compensation, revise and eliminate little vibration to the interference of optical system, improve useful load pointing accuracy, degree of stability and resolution.This measuring technique need to break through the noiselike signal treatment technology of high-precision microvibration measuring instrument, improves measuring instrument resolution; And measuring instrument carried out accurate demarcation.Need are finished frequency spectrum examination and the information extraction of environmental perturbation information from hardware and data correction analysis module.

Description of drawings

Fig. 1 is the system schematic of utilizing the little vibration of magnetic-field measurement of the present invention.

Embodiment

Be elaborated referring to the structure of accompanying drawing to the spacecraft mass characteristic combined test stand based on the sphere air-bearing of the present invention, but should describe only exemplaryly, be not intended to protection scope of the present invention is carried out any restriction.

Referring to Fig. 1, Fig. 1 has shown the system schematic of utilizing the little vibration of magnetic-field measurement spacecraft of the present invention.System of the present invention comprises the permanent magnet that is connected on little vibration measured piece, be arranged on the magnetometer of measured piece vector (three directions) on every side, distance between vector magnetometer and the permanent magnet remains between the 1cm-1m, preferred 20-50cm, and the compensation permanent magnet and the data Collection ﹠ Processing System that are used for the compensation high-intensity magnetic field, data Collection ﹠ Processing System and vector magnetometer telecommunication also obtain the change of magnetic field strength amount calculation process of collection minimum angular displacement and the displacement of the lines of little vibration of measured piece.The distance apart from vibrating member of the compensation permanent magnet of compensation high-intensity magnetic field does not have concrete restriction, its role is to the magnetic field that is connected in the permanent magnet on the tested vibrating member is compensated so that the magnetic field intensity measurement mechanism can be measured magnetic field dynamic change in time in range ability, as seen the effect that compensates permanent magnet only be the size of compensating field so that it is in the range ability of magnetometer be the variable quantity in magnetic field and irrelevant with its absolute size because the method pays close attention to.

Usually, the resolution of described vector magnetometer is 0.01NT, and the dynamic range of measurement is ± 10 ⁶NT, response frequency is from DC to 5kHz.

In the present invention, the permanent magnet that is cemented in measured piece passes near the high precision magnetometer that is fixed on the shaking platform with the displacement of Platform Machinery vibrational line and angular displacement information with the intensity in magnetic field and Vector Message, the field signal variation that magnetometer detects is by the position of magnetic dipole in the sensor and points to change and cause, therefore field signal changes with mechanical vibration to corresponding, and therefore measurement mechanical is vibrated accurately.Can eliminate environmental perturbation and noise by magnetic dipole compensation and Magnetic Gradient Measurement.

The method of utilizing changes of magnetic field to measure little vibration of the present invention is as follows:

1) permanent magnet and unit under test rigidity are connected;

2) the high precision magnetometer is installed in apart from the suitable distance of measured piece and (determines by the field strength values that on-the-spot magnetometer records with the permanent magnet distance, about 7～80,000 nT of the measured magnetic field intensity of magnetometer when keeping static measurement, magnetometer can be with the compensation magnets integral packagings;

3) connect high-speed data acquisition and disposal system and high precision magnetometer;

4) magnetometer and data acquisition processing system are switched on, and gather the changes of magnetic field Vector Message data of little generation of vibration, the storage data;

5) data are carried out Treatment Analysis, the little vibration information of inverting high precision.

Specifically, the 5th) in the step, the changes of magnetic field vector by little generation of vibration of collecting carries out minimum angular displacement and the displacement of the lines that following computing obtains little vibration:

According to physics magnetics knowledge as can be known, a little rumble spectrum responsor in the magnetic field of space generation is:

$B_r(r,\mathrm{\θ})=\frac{{\mathrm{\μ}}_{0}M\cos \mathrm{\θ}}{4{\mathrm{\πr}}^3}---\left(1\right)$

$B_{\mathrm{\θ}}(r,\mathrm{\θ})=\frac{{\mathrm{\μ}}_{0}M\sin \mathrm{\θ}}{4{\mathrm{\πr}}^3}---\left(2\right)$

Wherein, M is magnetic moment, μ ₀Be permeability of vacuum, r is the distance that magnetic dipole arrives the high precision magnetometer, and θ is the angle between magnetic dipole magnetic axis and the r direction.

The permanent magnet rigidity sticks on the tested structural member, the vibration of little generation of vibration dipole of structural member, and under vibration condition, r and θ are time dependent sine functions, and ω 1 ω 2 is the cycle, and φ 1 φ 2 is initial phase.

Owing to generation of vibration (r+ Δ r), (θ+Δ θ), cause the changes of magnetic field of measurement:

$\frac{\mathrm{\Δr}}{r}=\tan \mathrm{\Δ\θ}---\left(5\right)$

Br, B θ is respectively the component under the spherical coordinate system.

$B_r(r,\mathrm{\θ})=2{\mathrm{\μ}}_{0}M\frac{\cos (\mathrm{\θ}+\mathrm{\Δ\θ})}{4\mathrm{\π}{(r+\mathrm{\Δr})}^3}=\frac{2{\mathrm{\μ}}_{0}M}{4\mathrm{\π}{r}^3}\frac{\cos \mathrm{\θ}\cos \mathrm{\Δ\θ}-\sin \mathrm{\θ}\sin \mathrm{\Δ\θ}}{{(r+\frac{\mathrm{\Δr}}{r})}^3}$

$B_{\mathrm{\θ}}(r,\mathrm{\θ})=2{\mathrm{\μ}}_{0}M\frac{\sin (\mathrm{\θ}+\mathrm{\Δ\θ})}{4\mathrm{\π}{(r+\mathrm{\Δr})}^3}=\frac{2{\mathrm{\μ}}_{0}M}{4\mathrm{\π}{r}^3}\frac{\sin \mathrm{\θ}\cos \mathrm{\Δ\θ}+\mathrm{cons\θ}\sin \mathrm{\Δ\θ}}{{(r+\frac{\mathrm{\Δr}}{r})}^3}$

Under little Vibration Condition, Δ θ/θ＜＜1, Δ r/r＜＜1, following formula launches and ignores senior a small amount of, can obtain minimum angular displacement and displacement of the lines and be directly proportional with change rate of magnetic density:

$\mathrm{\Δ}{\mathrm{\θ}}_{\min }=K_{\mathrm{\θ}}\frac{{\mathrm{\ΔB}}_r}{B_r}---\left(8\right)$

$\mathrm{\Δr}=K_r\frac{\mathrm{\ΔB}}{B_r}---\left(11\right)$

Wherein, K is coefficient, and Δ Br can be expressed as Δ Br(t, θ with the variable quantity in the magnetic field of vibration).

The resolution of present existing High-precision Vector magnetometer is to 0.002nT, and frequency response can reach 10KHz.Therefore adopt the method for the little vibration of magnetic-field measurement, the little vibrational system of high precision magnetic-field measurement of foundation, the line vibration precision of measuring little vibration is better than nanoscale, and the minimum angles changes delta θ min that then can measure is better than 10 ^-4(rad), spectral range is to 10KHz.Usually the little vibration of spacecraft of paying close attention to is in hundreds of Hz arrives a few KHz scopes.

Although above the specific embodiment of the present invention has been given to describe in detail and explanation; but what should indicate is; we can carry out various equivalences to above-mentioned embodiment according to conception of the present invention and change and modification; when its function that produces does not exceed spiritual that instructions and accompanying drawing contain yet, all should be within protection scope of the present invention.

Claims (8)

1. method of utilizing the little vibration of magnetic-field measurement may further comprise the steps:

Permanent magnet and little vibration measured piece are connected, and measure the change of magnetic field strength amount that the quadrature three parts makes progress by the magnetic field intensity measurement mechanism that arranges around the measured piece;

The change of magnetic field strength amount that measures by the magnetic field intensity measurement mechanism is obtained minimum angular displacement and the displacement of the lines of little vibration by following mathematical relation and formula,

Wherein, minimum angular displacement and displacement of the lines are directly proportional namely with change rate of magnetic density:

$\mathrm{\Δ}{\mathrm{\θ}}_{\min }=K_{\mathrm{\θ}}\frac{\mathrm{\Δ}{B}_r}{B_r}$

$\mathrm{\Δr}=K_r\frac{{\mathrm{\ΔB}}_r}{B_r}$

K θ, Kr are coefficients, and span is respectively 0.28-0.40, and Δ Br is expressed as Δ Br(t with the variable quantity in the magnetic field of vibration), t is the time.

2. the method for claim 1, wherein described magnetic field intensity measurement mechanism is three vector magnetometers.

3. the method for claim 1, wherein described method little vibration of being applied to measure spacecraft.

4. such as each described method of claim 1-3, wherein, the Measurement Resolution of magnetometer is better than 0.01nT; Dynamic range: ± 10 ⁶NT; Response frequency: from DC to 5kHz.

5. system that utilizes the little vibration of magnetic-field measurement, comprise the permanent magnet that is connected on little vibration measured piece, be arranged on measured piece vector magnetometer on every side, distance between vector magnetometer and the permanent magnet remains between the 1cm-1m, and the compensation permanent magnet and the data Collection ﹠ Processing System that are used for the compensation high-intensity magnetic field, data Collection ﹠ Processing System and vector magnetometer telecommunication also obtain the change of magnetic field strength amount calculation process of collection minimum angular displacement and the displacement of the lines of the little vibration of measured piece.

6. system as claimed in claim 5, wherein, the distance between vector magnetometer and the permanent magnet is 20-50cm.

7. system as claimed in claim 5, wherein, the resolution of described vector magnetometer is 0.01NT, the dynamic range of measurement is ± 10 ⁶NT, response frequency is from DC to 5kHz.

8. such as each described system of claim 5-7, the system of the little vibration of wherein said magnetic-field measurement is used for measuring little vibration of spacecraft.

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