CN1021784C - Measuring method for athletic posture and apparatus thereof - Google Patents
Measuring method for athletic posture and apparatus thereof Download PDFInfo
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- CN1021784C CN1021784C CN 90103139 CN90103139A CN1021784C CN 1021784 C CN1021784 C CN 1021784C CN 90103139 CN90103139 CN 90103139 CN 90103139 A CN90103139 A CN 90103139A CN 1021784 C CN1021784 C CN 1021784C
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Abstract
The present invention relates to a measurement method for movement attitudes and a device thereof, which belongs to laser Doppler measurement technology. The measurement method adopts an optical path system with a quasi-common light path, four light beams and double focuses, and a photoelectric receiver receives scattered light of two light spots and detects the frequencies and the phases of two groups of signals. A movement attitude measurement instrument designed by using the method can detect the linear displacement larger than 0.05 micrometre and the angular displacement of 2.5' in the X direction and the Z direction of a measured object, and detect the linear speed from 0.2 micrometre /sec to 0.1 micrometre /sce and the angular speed of 10<7> angular seconds /second to 5 angular seconds /second. The present invention can be used for broad fields of analyzing the weak vibration of a mechanical system, analyzing rusty creep deformation and weld bead temperature distortion, etc.
Description
The invention belongs to the laser measuring technique field, particularly the technology of laser Doppler measuring speed and vibration.
Laser doppler measurement technique is a kind of non-contact measurement method that grows up in the sixties.It is to utilize the Doppler shift of measured object scattered light to obtain velocity information, can be used to measure the movement velocity of solid, and the vibration situation of solid surface.Extensively adopt the single-focusing method of twin-beam to constitute optical system at present, the light that is about to the LASER Light Source outgoing is divided into two bundles, again this two bundle is produced certain frequency difference post-concentration and becomes a bit to be mapped on the measured object.Receive reflected light and scattered light from the tested object point by photelectric receiver.Perhaps with the beam convergence directive measured object in the above-mentioned two-beam, another bundle is as directly being received by photelectric receiver with reference to light.Testing circuit detects the frequency of the signal of photelectric receiver output, obtains the movement velocity and the vibration situation of measured object.According to said method, produced Laser Doppler Velocimeter (LDA) and laser doppler vibrometer (LDV), be respectively applied for velocity survey and machinery vibration analysis.Fig. 1 is the light path principle and the structural representation of at present popular in the world commercial lasers Doppler anemometer (LDA), in Fig. 1, laser beam is divided into two-beam by spectroscope (2), catoptron (4) wherein a branch of light turns to, make it and another bundle parallel light, frequency displacement device (3) makes this two-beam produce a frequency difference, has the light beam of frequency difference, it is little to converge to measured target (6) through lens (5), and is scattered.Scattered light is received by photelectric receiver (9) after lens (5), catoptron (7), lens (8) are collected, and the frequency and the measured target of the electric signal of photelectric receiver output are proportional along the movement velocity of directions X.By detecting the frequency of photosignal, just can measure target moving along directions X.It can be used for measuring the movement velocity (directions X) of flow velocity or the solid surface vertical with optical axis.Because the vibration of optical element, the vibration of support, the acousto-optic drive power frequency jitter, the influence of disturbing factors such as air turbulence makes the phase place randomized jitter of photosignal.So just can not measure the micro-displacement and the small movements speed of solid surface, be limited to 100 μ m/s under its measuring speed.Fig. 2 is the light path principle and the structural representation of laser doppler vibrometer (LDV), among the figure, the light beam that laser instrument (1) sends is divided into two-beam by spectroscope (2), catoptron (4) wherein a branch of light turns to, make it and another bundle parallel light, this two-beam produces certain frequency difference behind frequency shifter (3).Having a branch of in the two-beam of frequency difference is mapped on the measured target through semi-transparent semi-reflecting lens (10) as measuring beam.Another bundle is as reference light.Reference light with produce difference interference by the measuring light of measurement target scattering or reflected back at photelectric receiver (9).The frequency and the measured target of the photosignal of photelectric receiver output are proportional along the speed of Z direction.Just can obtain the motion conditions of target by the variation that detects frequency along the Z direction.It can be used for measuring the vibration along optical axis direction (Z direction).
In many practical applications, need to measure simultaneously with optical axis vertical direction (directions X) with along the motion conditions of optical axis direction (Z direction), therefore must use LDA and two instruments of LDV, when using LDA, extraneous vibration can be introduced measurement result and cause error, because phase noise is big, can not carry out phase measurement, make resolution be difficult to improve.In addition, measured object except that translation is arranged, also has rotation in the plane vertical with optical axis.Two kinds of above-mentioned instruments all can not be measured the rotational angle of measured object.
The objective of the invention is to overcome outside the deficiency of above-mentioned measuring method, a kind of measuring method of multiple athletic posture of energy measurement object is proposed, improve measuring accuracy and resolution, enlarge measurement range, the present invention designs a kind of athletic posture measuring instrument according to this measuring method, can make things convenient for conversion also can measure the rotational angle of object to LDA and LDV.
The present invention proposes a kind of measuring method for athletic posture, adopt laser doppler measurement technique, be about to be mapped on the tested object point after laser beam focuses on, the light that this measured object point reflection and scattering are returned is received and is converted to electric signal output by photelectric receiver, signal processing system detects the frequency of this electric signal, analyze, obtain the athletic posture of measured point, it is characterized in that adopting the accurate bifocal light path system of road four light beams altogether, promptly said laser beam is divided into the polarized light that four bundles have two kinds of different polarization directions with beam splitter, the polarized light that makes wherein two bundles have the different polarization direction with frequency modulator produces a certain amount of frequency difference with other two bundle polarized lights makes the light beam more than said two bundles form two luminous points not far from one another with collective optics again, said measured object is placed on said two luminous point places, the reflected light and the scattered light of the tested object point at two focus places of said photelectric receiver reception also converts electric signal output to, and said signal processing system detects the frequency and the phase place of said two groups of electric signal.
The light path system of above-mentioned measuring method also can constitute twin-beam differential type light path, be that said collective optics is focused into the two-beam that has identical polarization direction in the said four bundle light a bit, two-beam with another polarization direction is focused into another point, and said photelectric receiver receives the reflected light and the scattered light of the tested object point in bifocal place.
The light path system of above-mentioned measuring method also can constitute reference light formula light path, being said optically focused light spare is focused into the two-beam that has same frequency in the said four bundle light on 2 that are mapped to said measured object after two focuses, the reflected light of said tested object point, scattered light are received by said electric light receiver, said other two-beam focuses on the back by the said photelectric receiver of the direct directive of optical inversion element as reference light.
Measuring method for athletic posture of the present invention is characterized in that being provided with in the said light path system realization twin-beam differential type light path of light path selection and the conversion method of reference light formula light path.Principle of the present invention as shown in Figure 3, the light that laser instrument 1 sends is divided into two bundles by beam splitter (12), frequency shifter (13) makes this two-beam produce frequency difference.Two-beam with frequency difference is divided into four bundles behind optical splitter (14).Four intrafascicular two-beams (A, B) are mapped to the testee surface behind beam condensing unit (16), in addition two-beam (A ', B ') is controlled by a light path selector.1. when measuring along the moving of directions X, light path selector make light beam A ', B ' is mapped to measured surface by beam condensing unit, (light that enter into detecting device this moment is closed) is focused at 2 P on the measured surface with other two-beam A, B respectively
1, P
2P
1, P
22 scattered beams of locating are collected and are walked around by detecting device (17) and change electric signal into.Electric signal is handled by the subsequent treatment device can obtain body surface moving along directions X.2. move when measuring on the Z direction, light path selector makes light A ', B ' enter detecting device (17) (light that enter into beam condensing unit this moment is closed), as reference light, with from the light beam A of measured surface, B at P
1, P
22 scattered beams of locating are interfered mutually, and interference signal converts electric signal to and send the subsequent treatment device, can obtain body surface after the processing along moving on the Z direction.
In the present invention, represent P
1, P
2The expression formula of the photo-signal of 2 movable informations is:
i
1（t）＝I
01+A
1COS（2πf
0t
1+φ
1+φ
01）
i
2（t）＝I
02+A
2COS（2πf
0t
2+φ
2+φ
02）
In the formula: φ
1, φ
2Be and the proportional phase term of measurement point displacement, φ
01, φ
02It is initial phase; I
01, I
02Be average current, A
1, A
2It is random amplitude.
Have for the directions X motion measurement:
φ
1＝R
X·d
X1
φ
2＝R
X·d
X2
Motion has to the Z direction:
φ
1＝R
Z·d
Z1
φ
2＝R
Z·d
Z2
R wherein
X, R
ZBe by the directions X of light path system decision, the scale factor of Z direction.
d
X1, d
X2, d
Z1, d
Z2, be respectively P
1, P
2The point X to Z to displacement.
Signal processor can detect phase
1, φ
2Thereby obtain measured target X side and Z to motion.
Have for the rotation in the plane vertical with optical axis (Z to):
Corner: φ
X=(d
X1-d
X2)/L
Rotational angular velocity: ω
X=d φ
X/ dt
Have for the rotation in optical axial plane:
Corner: φ
Z=(d
Z1-d
Z2)/L
Rotational angular velocity: ω
Z=d φ
Z/ dt
L is P in the formula
1, P
2Distance between two points.
The conversion method of twin-beam differential type light path of the present invention and reference light formula light path has two kinds of concrete schemes, and one said four bundles have two bundle same frequencys in the light, places a steering component movably in one the tunnel.When this steering component shifts out outside the light path, constitute the differential type light path, when this steering component is placed in this light path, then constitute with reference to the formula light path.
They are two years old, what have two bundle same frequencys in the said four bundle light is one the tunnel, in this light path, place a beam splitter, this road light is divided into the first via light beam that is undertaken by former direction, and has changed the second road light beam of direction, a light switch is set respectively in this first via and the second tunnel, and make two on off states opposite, when the light switch open in the first via light, then constitute the differential type light path, when the light switch open in the second road light, then constitute with reference to the formula light path.
The present invention designs a kind of athletic posture measuring instrument as stated above, by LASER Light Source, beam splitter, the optical inversion element, the optical system that collective optics is formed, photelectric receiver, signal processing system is formed, it is characterized in that said optical system is constructed as follows: the light beam by the LASER Light Source outgoing is divided into two-beam by first beam splitter, this two-beam is respectively through producing certain frequency difference behind the frequency modulator, two light beam light that have frequency difference become the orthogonal four bundle light in polarization direction by polarizer respectively, and this four bundles light is converged to two luminous points separated by a distance in twos by collective optics.
The optical system of this athletic posture measuring instrument also can be provided with an optical inversion element movably, with its conversion that realizes twin-beam differential type light path and reference light formula light path, the quick conversion of second beam splitter and two kinds of light paths of two alternative above-mentioned movably optical inversion element realizations of light switches is set perhaps.
Signal processing system block diagram in the athletic posture measuring instrument of the present invention comprises and gives treatment circuit A as shown in Figure 4
1, A
2, A
3; Tracking filter and modulator-demodular unit (T
1, T
2, T
3); Select system (S); Frequency difference multiplier and subtracter (L); Phase detectors (P); IO interface (I/O); Frequency displacement power supply and frequency mixer (M); Part such as computing machine (PC) is formed.
Measuring instrument of the present invention can carry out multiple measurement to moving object, the measuring accuracy height, and measurement range is wide, to the microvibration analysis of mechanical system, the corrosion creep, fields such as weld seam thermal deformation analysis have wide practical use.
Brief Description Of Drawings:
Fig. 1 is existing smooth Doppler anemometer (LDA) light path principle and structural representation.
Fig. 2 is existing laser doppler vibrometer (LDV) light path principle and structural representation.
The measuring method for athletic posture principle schematic that Fig. 3 the present invention proposes.
Fig. 4 signal processing system block diagram of the present invention.
Fig. 5 a kind of most preferred embodiment optical principle of the present invention and structural representation.
Fig. 6 a kind of most preferred embodiment signal processing system The general frame of the present invention.
It is the multi-functional magnetic head flight attitude measuring instrument that is used for the magnetic head of metering computer hard disk drive that the present invention proposes a kind of most preferred embodiment.Now 5,6 be described in detail in conjunction with the accompanying drawings.Fig. 5 is the overall light path and the structural representation of present embodiment.Is that the He-Ne laser instrument of 0.6328 μ m sends linearly polarized laser by power for the 5mw wavelength, polarization spectroscope (18) is divided into laser beam two perpendicular bundle laser of two polarization directions and is reflected into two parallel beams by reflecting prism (19), (20), two directional lights produce frequency displacement respectively behind acousto-optic modulator (21), (22), the light beam that has a frequency displacement behind λ/4 wave plates (23), (24), becomes circularly polarized light respectively.Prism (25) is stepped in wet Lars, (26) become two circularly polarized lights into the orthogonal four bundle light of four bundle polarizations.Two wet Lars are stepped on the prism splitting angle and are equated and symmetric arrangement.Prism is stepped in each wet Lars can make the plane at its plane, two light beam places that separates and the two light beam places that separated by another Wo Lasi prism be parallel to each other around the rotation of its optical axis, and two planes and surface level are perpendicular.Catoptron (27), (28) are fixed on the guide rail and can move so that light path is fit to different measurement needs along direction shown in the arrow.In measuring the magnetic head face during attitude, moving guide rail makes wet Lars step on the two-beam that prism (25) sends and directly shines diaphragm (34), obtains four light beam bifocus differential type light paths.When measuring the vertical attitude of magnetic head, moving guide rail makes reflecting prism (28) that the two-beam that prism (25) sends is stepped in wet Lars and blocks, and reflexes to reflecting prism (27), makes this two-beam as reference light, forms twin-beam bifocus reference light formula light path.Catoptron (36), lens (5), lens (8), catoptron (7), polarization spectroscope (31) and two analyzers (30), (32), photelectric receiver (29), (33), light path for dual mode is all fixed, the conversion of two kinds of metering systems only needs translation catoptron (27), (28) to get final product.
Bifocal spacing L is the focal distance f of lens (5) on the measured object surface
5Step on the function of prism splitting angle θ with wet Lars, can get by geometrical optics:
L＝f
5·tgθ
Can select different L values according to concrete measuring object.After the L value is determined, can at first determine the θ value, determine f again
5Change the focal length of lens, can change the spacing of two measuring points.
In the present embodiment, measure for magnetic head, the distance of bifocal is in 2～4mm scope.Form the light beam of bifocal, the polarization direction is vertical mutually, and experiment shows, and is not serious in the scattered light and the catoptrical depolarization of measurement point, so available polarization spectroscope separates the scattered light of two measuring points.
In the present embodiment, the frequency of the acousto-optic drive power of acousto-optic modulator (21), (22) is chosen 40MHZ and 41MHZ respectively, and its frequency difference is 1MHZ, and two photelectric receivers are selected the PIN photelectric receiver for use.The signal processing system The general frame of present embodiment as shown in Figure 6.Its principle of work is as follows: two photelectric receivers receive centre frequency f
0Be the photosignal of 1MHZ, also comprise much noise, the signal that contains noise is f by centre frequency
0, bandwidth is the most of noise of elimination behind wave filter BF1, the BF2 of △ f, obtains the amplitude Stochastic Modulation, centre frequency is f
0Signal.This signal becomes the sinusoidal signal of constant amplitude behind automatic gain control circuit AGC, obtain square-wave signal again behind rest-set flip-flop.The centre frequency of this square-wave signal is f
0, correspondingly being directly proportional with the displacement of measurement point, phase place is that the frequency of signal is directly proportional with speed over time.Two acousto-optic power supply AOS
1AOS
2The signal of output is through mixting circuit M
1Carry out mixing, again through bandpass filter BF
3After to obtain frequency be f
0Standard signal.RS
1, RS
2The two-way measuring-signal of output is by tracking filter TF
1, TF
2After obtain and the output of the proportional simulation output of measurement point speed and square wave RS
3The standard signal of output passes through TF
3After obtain standard square wave output, these three kinds of square-wave signals send counter C after through selector switch input frequency difference multiplier * 10
1Counting.When selecting switch connection TF
1, TF
2The time, C
1Umber of pulse that counter is counted is the relative displacement of two measuring points; When selecting switch connection TF
1, TF
3Or TF
2, TF
3The time, C
1Umber of pulse that counter is counted is the absolute displacement of a measuring point.Counter C
1Output send into COMPUTER CALCULATION by the computer interface circuit.RS
1With RS
2, RS
1With RS
3Output also can send into phase detectors respectively and obtain and the phase differential of two signals or the aanalogvoltage of direct ratio, again through low-pass filter filtering, its analog quantity output can directly be carried out record by registering instrument, also can carry out computing by A/D conversion input computing machine.
The described multi-functional magnetic head flight attitude measuring instrument of present embodiment can and be measured the displacement of the lines and 2.5 of 0.05 μ m in the vertical direction of optical axis, and " the angle place value is measured the linear velocity and 10 of 0.2m/sec～0.1 μ m/sec along optical axis direction
7Rad/S～5 rad/S angular velocity have been satisfied the surveying work to the magnetic head motion state fully.
Claims (7)
1, a kind of measuring method for athletic posture, adopt laser doppler measurement technique, be about to be mapped on the tested object point after laser beam focuses on, the light that this measured object point reflection and scattering are returned is received and is converted to electric signal output by photelectric receiver, testing circuit detects the frequency and the phase place of this electric signal, analyze, obtain the athletic posture of measured point, it is characterized in that adopting the accurate bifocal light path system of road four light beams altogether, promptly said laser beam is divided into the polarized light that four bundles have two kinds of different polarization directions with beam splitter, the polarized light and other two that makes wherein two bundles have the different polarization direction with frequency modulator is restrainted polarized lights and is produced a certain amount of frequency difference, with collective optics the two-beam that has identical polarization direction in the said four bundle light is focused into a bit again, two-beam with another polarization direction is focused into another point, and said photelectric receiver receives the reflected light and the scattered light of the tested object point in bifocal place; Or said collective optics two-beam that said four bundles are had same frequency in the light is focused on 2 that are mapped to said measured object after two focuses, the reflected light of said tested object point, scattered light is received by said electric light receiver, said other two-beam is as reference light, focus on the back by the said photelectric receiver of the direct directive of optical inversion element, said testing circuit detects the frequency and the phase place of said two groups of electric signal.
2, a kind of as the said measuring method for athletic posture of claim 1, it is characterized in that being provided with in the said light path system light path selector, realize twin-beam differential type light path and conversion with reference to the formula light path.
3, a kind of measuring method for athletic posture as claimed in claim 2, it is characterized in that said light path selector is for movably rotating to element, what be that said four bundles have two bundle same frequencys in the light is one the tunnel, in this light path, place said movably steering component, when this steering component weighs up outside the light path, then constitute the differential type light path, when this steering component is placed in this light path, then constitute with reference to the formula light path.
4, various measuring method for athletic posture as claimed in claim 2, it is characterized in that said light path selector is made up of steering component and light switch, be said four bundles have in the light two bundle same frequencys for a kind of, in this light path, place a beam splitter, this road light is divided into the first via light beam that is undertaken by former direction and changed the second road light beam of direction, a light switch is set respectively in this first via and the second tunnel, and make two on off states opposite, when the light switch open in the first via, then constitute with reference to the formula light path.
5, a kind of employing is the athletic posture measuring instrument of method according to claim 1, by LASER Light Source, beam splitter, the optical inversion element, the optical system that collective optics is formed, photelectric receiver, signal processing system is formed, it is characterized in that said optical system is constructed as follows: the light beam by the LASER Light Source outgoing is divided into two-beam by first beam splitter, this two-beam is respectively through producing certain frequency difference behind the frequency modulator, two light beams that have frequency difference have two polarizers to become the orthogonal four bundle light in polarization direction respectively, said optical inversion element is an optical inversion element movably, light path after this steering component places a said polarizer, then the said photelectric receiver of the direct directives of light is restrainted in the polarization direction that forms behind this polarizer orthogonal two, and the orthogonal two bundle light in the polarization direction that forms behind another polarizer are converged to two luminous points separated by a distance by collective optics; When this steering component shifts out this light path, said four bundle light make the identical light beam in polarization direction be converged to two luminous points separated by a distance in twos by collective optics.
6, athletic posture measuring instrument as claimed in claim 5 is characterized in that said optical inversion element includes second beam splitter and two light switches.
7, athletic posture measuring instrument as claimed in claim 5 is characterized in that said signal processing system comprises to give treatment circuit; Tracking filter and modulator-demodular unit; Selector switch; Frequency difference multiplier and subtracter; Phase detectors; IO interface; Frequency displacement power supply and frequency filter; Computing machine.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 90103139 CN1021784C (en) | 1990-06-28 | 1990-06-28 | Measuring method for athletic posture and apparatus thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 90103139 CN1021784C (en) | 1990-06-28 | 1990-06-28 | Measuring method for athletic posture and apparatus thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1057907A CN1057907A (en) | 1992-01-15 |
| CN1021784C true CN1021784C (en) | 1993-08-11 |
Family
ID=4877921
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 90103139 Expired - Fee Related CN1021784C (en) | 1990-06-28 | 1990-06-28 | Measuring method for athletic posture and apparatus thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1021784C (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4093971B2 (en) * | 2004-02-12 | 2008-06-04 | シャープ株式会社 | Optical movement information detection apparatus, movement information detection system, electronic apparatus and encoder |
| CN101169320B (en) * | 2007-10-29 | 2010-10-13 | 北京交通大学 | Moving article transient posture measuring apparatus |
| CN101799318B (en) * | 2010-03-22 | 2011-11-09 | 电子科技大学 | Laser homodyne vibration detection optical system |
| CN102359814B (en) * | 2011-07-04 | 2012-11-07 | 苏州舜新仪器有限公司 | Three-dimensional laser motion attitude measuring system and method |
| JPWO2017038659A1 (en) * | 2015-09-01 | 2018-06-14 | 国立大学法人 東京大学 | Motion detection device and three-dimensional shape measurement device using the same |
| CN108693247B (en) * | 2017-04-07 | 2020-09-01 | 天津大学 | Laser surface acoustic wave detection system based on double measuring beams and use method thereof |
| CN113687091A (en) * | 2021-09-22 | 2021-11-23 | 深圳市天辰防务通信技术有限公司 | Laser speed measuring device |
-
1990
- 1990-06-28 CN CN 90103139 patent/CN1021784C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN1057907A (en) | 1992-01-15 |
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