CN104296691B - Aircraft engine tail profile measurement device and method based on machine vision - Google Patents

Abstract

The invention discloses an aircraft engine tail profile measurement device and method based on machine vision. The device comprises a computer, two CCD cameras, two linear array semiconductor lasers and modulators. The output of the computer is connected with a pulse generator, the pulse generator is connected with the CCD cameras and the linear array semiconductor lasers, the linear array semiconductor lasers are connected with laser emission heads through the modulators, and the CCD cameras capture linear array profiles and upload the linear array profiles to the computer through image acquisition cards. The measurement method includes the steps that the CCD cameras capture images respectively, profile diagrams are acquired from strong light in a laser lock-on imaging mode, and after the profiles are corrected, the images acquired by the two CCD cameras are fused. According to the aircraft engine tail profile measurement device and method based on machine vision, the two CCD cameras are used for partially capturing the profile diagrams of the linear arrays of the tail of an engine in the field of view and capture flames on the tail in the field of view, the working conditions of the engine are studied in the aspect of tail flame images and the aspect of tail profile changes, and thus the reliability of detection is improved.

Description

Aircraft engine drive end unit contour outline measuring set and method based on machine vision

Technical field

The invention belongs to aero-engine performance detection field, is related to the skills such as image procossing, laser and optics, computer Art, a kind of method for proposing aircraft engine drive end unit profile measurement and afterbody flame analysis, and in particular to one kind is regarded based on machine The aircraft engine drive end unit contour outline measuring set of feel and method.

Background technology

With the fast development of national economy, air transportation is more and more important in the life of people.Aircraft so that it is quick, Comfortably with it is comparatively safe the features such as, be increasingly becoming the most important trip mode of people.But in recent years the rate of meeting accident of aircraft is big Big to improve, so strengthening Flight Safety becomes very important task, and the service behaviour of aircraft engine is winged One important step of machine flight safety, its state directly affects the service behaviour of aircraft.

Aircraft engine is the thermal machine of a kind of high complexity and precision, and for airborne vehicle sending out for flight required drive is provided Motivation, as the heart of aircraft, is described as " flower of industry ", and it directly affects performance, reliability and the economy of aircraft, is one The important embodiment of individual national science and technology, industry and military capability of the country.It is that gas turbine starts that at present aero-engine is most widely used Machine, mainly includes turbofan and turbojet, and turbofan is mainly used in that speed is higher to fly Machine, turbojet is mainly used in supersonic plane.They are mainly by air intake duct, compressor, combustor, turbine and spray Mouth composition.

Operationally, jet pipe nozzle temperature is high for aircraft engine, and about 60～200 DEG C of ambient temperature, gas flow temperature are close to 2000K, jet pipe exhaust velocity is fast, and tail jet luminous intensity is greatly and hot jet pipe is in motion (contraction, extensional motion and axle To movement) state, so the detection to its afterbody profile becomes very difficult.Current Measuring Object profile means are generally divided For two kinds：One is contact type measurement, and two is non-contact measurement.The ultimate principle of contact type measurement is all that machine takes one by one a little, Measurement head is contacted with testee, and operating process is loaded down with trivial details, and measuring speed is slow, especially when testee is larger, takes very much.Cause Tail temperature is high when working for aircraft engine, and size is big, and traditional contact-type 3 D measuring method is no longer suitable for.Based on machine The contour of object detection of vision, belongs to noncontact measurement, and it adopts structure light as light source, when project structured light is to object During surface, profiled outline light belt can be formed on testee, capture the dispersion image of testee with ccd video camera, then Through a series of images process, afterbody profile diagram is restored.

The content of the invention

It is an object of the invention to overcome the deficiencies in the prior art, there is provided one kind is separately mounted to two ccd video cameras Above rear side is retreaded and obliquely downward, partial field of view capture electromotor afterbody linear array profile diagram and visual field capture afterbody flame, from Two aspects of wake flame image and afterbody profile variations are studying the aircraft engine based on machine vision of the working condition of electromotor Drive end unit contour outline measuring set.

It is a further object to provide a kind of aircraft engine drive end unit contour measuring method based on machine vision, Contour images are obtained from high light using laser lock imaging to the image that ccd video camera is obtained, by upper and lower two parts profile diagram As carrying out merging the image for obtaining 180 degree, because electromotor afterbody has bilateral symmetry, you can obtain 360 degree by upset Contour images, it is easy to detect, calculate simple.

The purpose of the present invention is achieved through the following technical solutions：Aircraft engine drive end unit wheel based on machine vision Wide measurement apparatus, the relative position in electromotor afterbody side is provided with laser beam emitting head, electromotor rear side retread top and The relative position of obliquely downward is respectively equipped with ccd video camera；

Further, computer, pulse generator, linear array semiconductor laser and manipulator are also included, computer Controlled output connects ccd video camera by delay circuit, and the controlled output of computer is also connected with pulse generator, pulse generation The output of device is connected respectively with ccd video camera and linear array semiconductor laser, the line laser battle array of linear array semiconductor laser Intensity modulation is carried out into manipulator, the line laser battle array after modulators modulate is by laser beam emitting head vertical illumination to starting Drive end unit side, ccd video camera capture electromotor afterbody linear array profile diagram, and the image for obtaining is uploaded by image pick-up card To computer.

Further, described laser beam emitting head is coplanar, and ccd video camera is coplanar, and Laser emission head plane is imaged with CCD Machine plane is parallel.

Further, to avoid ccd video camera in saturation, under the irradiation of strong direct light source, must add before ccd video camera Optical attenuator and optically filtering piece, with weaken into ccd video camera light intensity and eliminate bias light, but by filter plate simultaneously Strong bias light can not be completely eliminated, flame image is still too strong, profile diagram can be obtained from high light with laser lock imaging. The digital pulse signal that linear array semiconductor laser is sent by computer, target scattering enters ccd video camera focal plane arrays (FPA) Light intensity be to determine frequency sinusoidal variations signal, corresponding grey scale signal is also sinusoidal variations, and bias light is then different, Corresponding grey scale signal Changing Pattern is uncertain.Some width images are taken in a cycle of modulating frequency, and is stored in Sinusoidal signal in calculator memory carries out multiplication and low pass filter operation, and the gray scale of bias light is filtered, and only retains laser Grey scale signal.Because multiplication and low pass filter process are the phase demodulation processes in phaselocked loop, so referred to as laser lock imaging.It is logical Cross laser lock imaging, the grey scale signal in the only region of laser lighting is retained, bias light (including detector dark current) Filtered completely.

Because the present invention is applied in aircraft engine monitoring, because area of detection is excessive, jet pipe nozzle temperature is high, ring About 60～200 DEG C of border temperature, the close 2000K of gas flow temperature, jet pipe exhaust velocity is fast, and tail jet luminous intensity is big and hot Jet pipe does some improvement in motion (contraction, extensional motion and axial movement) state, needs in original technical foundation：Will The power of linear array semiconductor laser increases to 1W from 100mW；Line laser is set to into line laser battle array, to cover engine jet pipe Dynamic range；The use of time of exposure is 1ms high speed cameras；Using certain cooling water circulation measure protection equipment.

The aircraft engine drive end unit contour measuring method based on machine vision of the present invention, comprises the following steps：

S1：Using principle of triangulation, the image that characteristic point is imaged in ccd video camera, i.e. image coordinate system are obtained in advance Relation, recycle position relationship of the characteristic point in world coordinate system, obtain between world coordinate system and image coordinate system Mapping relations formula；

S2：Image is obtained, linear array semiconductor laser is opened, two ccd video cameras distinguish capture images, ccd video camera The image of acquisition includes afterbody flame figure and profile diagram；

S3：Bias light is eliminated, profile diagram is obtained from high light using laser lock imaging：In a cycle of modulating frequency Some width images are inside taken, and storage sinusoidal signal in a computer carries out multiplication and low pass filter operation, by bias light Gray scale is filtered, and only retains laser grey scale signal, obtains engines tail contouring image；

S4：Image semantic classification, the engines tail contouring image obtained to S3 is filtered, smooths and micronization processes, obtains To single pixel contour images；

S5：Contour correction, using the mapping relations formula between world coordinate system and image coordinate system, by laser light belt image The anti-image coordinate for pushing away world coordinate system of coordinate system, so as to obtain the three-dimensional information of testee；

S6：Image co-registration, the image that two ccd video cameras are obtained is merged, and obtains final product aircraft engine drive end unit 180 degree Profile.

Further, the detailed process of bias light is eliminated in described step S3 includes following sub-step：

S31：If the grey scale signal function of the consecutive image that ccd video camera is gathered is：

G (m)=G_B(m)+G_L(m) (1)

Wherein, G_BThe gradation of image of m bias light that () is scattered by target, G_LThe image of m laser that () is scattered by target Gray scale；

For Sine Modulated laser, have：

G_L(m)=G_L0(1+ξsin(ωΔtm+φ)) (2)

Wherein, G_L0Be constant with φ, ξ represents modulation degree, ω represents modulation angular frequency, Δ t be between two width images when Between it is poor；

S32：Carry out multiplying：

If：G_BM () is slow change, after integration：

Complex background gray scale G is processed more than_MM () is filtered out, bias light gray scale is disappeared, and is only left target scattering and swashs Light grey scale signal.

The invention has the beneficial effects as follows：

1st, using upper and lower linear array laser vertical illumination electromotor afterbody side, two ccd video cameras are separately mounted to afterbody Retread top and obliquely downward, partial field of view capture electromotor afterbody linear array profile diagram and visual field capture afterbody flame for side, profile diagram For monitoring electromotor afterbody three-D profile, afterbody flame is used for the spark that diagnosis is likely to occur, from wake flame image and afterbody wheel Exterior feature changes two aspects to study the working condition of electromotor, increased the reliability of detection；

2nd, electromotor afterbody is irradiated using line laser battle array, the dynamic range of engine jet pipe can be covered, improved and survey The accuracy of amount；

3rd, using optical attenuator and optically filtering piece is arranged before ccd video camera, the light intensity into ccd video camera is weakened With elimination bias light, contour images are obtained from high light using laser lock imaging to the image that ccd video camera is obtained, will be upper and lower Two parts contour images carry out merging the image for obtaining 180 degree, because electromotor afterbody has bilateral symmetry, you can by turning over Turn the contour images for obtaining 360 degree, it is easy to detect, calculate simple, while apparatus cost can also be reduced；

4th, using laser power is increased to into 1W from 100mW, line laser is set to into linear array, the use of time of exposure is 1ms High-speed camera and using certain cooling water circulation measure protection equipment etc. operate, can adapt to big compared with high and area of detection Temperature environment, improve detection degree of accuracy；

5th, measuring method of the invention can be not only used for the detection of aircraft engine, can be also used for other aircraft and sends out The detection of motivation, there is the good suitability.

Description of the drawings

Fig. 1 is the measurement apparatus structural representation of the present invention；

Fig. 2 is the measurement apparatus scheme of installation of the present invention；

Fig. 3 is the mapping relations schematic diagram between the world coordinate system and image coordinate system of the present invention；

Fig. 4 is the image co-registration process schematic of the present invention.

Specific embodiment

The interference of the bias light strong for electromotor afterbody, we make use of laser lock imaging technology.Lock imaging Ultimate principle be widely used in Testing of Feeble Signals principle in phaselocked loop, including two processes of multiplication and low-pass filtering.For The lock imaging of digital picture, multiplication and low-pass filtering then become digital multiplication and digital low-pass filtering computing, can use software Realize.Lock imaging is generally possible to will be less than the weak image signal of more than 200 times of noise and extracts；And optical filter can be with About 90% bias light is filtered.Image capture technologies that both optically filtering and number lock imaging are combined are referred to as into laser Lock imaging technology.This technology has unrivaled suppression background light ability.Experiment shows, swashs than target scattering in bias light In the case that light intensity is big 104 times, laser lock imaging can obtain the weak laser signal of target scattering, simply use locking It is imaged or simply uses optically filtering and does not all reach so high to-noise ratio.

It is from side illumination electromotor using the linear array laser of modulation based on the aircraft engine drive end unit measurement of machine vision Afterbody, with two imageing sensors laser lighting image is obtained, and each image sensor field of view covering part contour images leads to Cross image co-registration and obtain complete profile diagram.

Further illustrate technical scheme below in conjunction with the accompanying drawings, but the content protected of the present invention be not limited to It is lower described.

As shown in Figure 1 and Figure 2, the aircraft engine drive end unit contour outline measuring set based on machine vision, in electromotor rear side The relative position in face is provided with laser beam emitting head, is respectively equipped with the relative position of obliquely downward above electromotor rear side is retreaded Ccd video camera；

Further, computer, pulse generator, linear array semiconductor laser and manipulator are also included, computer Controlled output connects ccd video camera by delay circuit, and the controlled output of computer is also connected with pulse generator, pulse generation The output of device is connected respectively with ccd video camera and linear array semiconductor laser, the line laser battle array of linear array semiconductor laser Intensity modulation is carried out into manipulator, the line laser battle array after modulators modulate is by laser beam emitting head vertical illumination to starting Drive end unit side, ccd video camera capture electromotor afterbody linear array profile diagram, and the image for obtaining is uploaded by image pick-up card To computer.

Further, described laser beam emitting head is coplanar, and ccd video camera is coplanar, and Laser emission head plane is imaged with CCD Machine plane is parallel.

Further, to avoid ccd video camera in saturation, under the irradiation of strong direct light source, must add before ccd video camera Optical attenuator and optically filtering piece, with weaken into ccd video camera light intensity and eliminate bias light, but by filter plate simultaneously Strong bias light can not be completely eliminated, flame image is still too strong, profile diagram can be obtained from high light with laser lock imaging. The digital pulse signal that linear array semiconductor laser is sent by computer, target scattering enters ccd video camera focal plane arrays (FPA) Light intensity be to determine frequency sinusoidal variations signal, corresponding grey scale signal is also sinusoidal variations, and bias light is then different, Corresponding grey scale signal Changing Pattern is uncertain.Some width images are taken in a cycle of modulating frequency, and is stored in Sinusoidal signal in calculator memory carries out multiplication and low pass filter operation, and the gray scale of bias light is filtered, and only retains laser Grey scale signal.Because multiplication and low pass filter process are the phase demodulation processes in phaselocked loop, so referred to as laser lock imaging.It is logical Cross laser lock imaging, the grey scale signal in the only region of laser lighting is retained, bias light (including detector dark current) Filtered completely.

Because the present invention is applied in aircraft engine monitoring, because area of detection is excessive, jet pipe nozzle temperature is high, ring About 60～200 DEG C of border temperature, the close 2000K of gas flow temperature, jet pipe exhaust velocity is fast, and tail jet luminous intensity is big and hot Jet pipe does some improvement in motion (contraction, extensional motion and axial movement) state, needs in original technical foundation：Will The power of linear array semiconductor laser increases to 1W from 100mW；Line laser is set to into line laser battle array, to cover engine jet pipe Dynamic range；The use of time of exposure is 1ms high speed cameras；Using certain cooling water circulation measure protection equipment.

The aircraft engine drive end unit contour measuring method based on machine vision of the present invention, comprises the following steps：

S1：Using principle of triangulation, the image that characteristic point is imaged in ccd video camera, i.e. image coordinate system are obtained in advance Relation, recycle position relationship of the characteristic point in world coordinate system, obtain between world coordinate system and image coordinate system Mapping relations formula；

S2：Image is obtained, linear array semiconductor laser is opened, two ccd video cameras distinguish capture images, ccd video camera The image of acquisition includes afterbody flame figure and profile diagram；

S3：Bias light is eliminated, profile diagram is obtained from high light using laser lock imaging：In a cycle of modulating frequency Some width images are inside taken, and storage sinusoidal signal in a computer carries out multiplication and low pass filter operation, by bias light Gray scale is filtered, and only retains laser grey scale signal, obtains engines tail contouring image；

S4：Image semantic classification, the engines tail contouring image obtained to S3 is filtered, smooths and micronization processes, obtains To single pixel contour images；

S5：Contour correction, using the mapping relations formula between world coordinate system and image coordinate system, by laser light belt image The anti-image coordinate for pushing away world coordinate system of coordinate system, so as to obtain the three-dimensional information of testee；

S6：Image co-registration, the image that two ccd video cameras are obtained is merged, and obtains final product aircraft engine drive end unit 180 degree Profile.

The extraction of engines tail contouring：Two ccd video cameras are arranged at electromotor and tiltedly go up, tiltedly descend two side positions, up and down Both sides line laser battle array vertical irradiation electromotor afterbody, laser irradiance profile region is about 180 degree (because profile is symmetrical Property, only measure a side profile).Ccd video camera optical axis has an angle (being a kind of triangulation method) with laser profile. Therefore the image acquired in each imageing sensor is fault image, needs to carry out demarcation correction to fault image.Such as Fig. 3 institutes Show, O_W-X_WY_WZ_WThe world coordinate system set up with scaling board plane space, i.e. measurement range coordinate system, ZW axles are electromotors Central axis direction；O_C1-X_C1Y_C1Z_C1And O_C2-X_C2Y_C2Z_C2It is two ccd video camera coordinate systems, O-u₁v₁And O-u₂v₂It is image coordinate System, P points be scaling board plane reference points, P1, P2 respectively correspond to two video cameras pixel coordinate point, P points through rigid body translation, Lens distortion, taking the photograph the light choppers such as projective transformation could be in CCD planar imaging, and whole light chopper is one continuous, antithesis Process, therefore can utilize matrix knowledge, whole light chopper matrix is effectively merged, after just being simplified Transformation matrix, i.e. mapping relations of image coordinate system and world coordinate system.

Linear array laser covers electromotor afterbody excursion, and the image that each ccd video camera is obtained includes afterbody fire Flame figure and compartment outline, upper and lower two parts image co-registration are got up, so as to obtain complete profile diagram, as shown in Figure 4.

Further, the detailed process of bias light is eliminated in described step S3 includes following sub-step：

S31：If the grey scale signal function of the consecutive image that ccd video camera is gathered is：

G (m)=G_B(m)+G_L(m) (1)

Wherein, G_BThe gradation of image of m bias light that () is scattered by target, G_LThe image of m laser that () is scattered by target Gray scale；

For Sine Modulated laser, have：

G_L(m)=G_L0(1+ξsin(ωΔtm+φ)) (2)

Wherein, G_L0Be constant with φ, ξ represents modulation degree, ω represents modulation angular frequency, Δ t be between two width images when Between it is poor；

S32：Carry out multiplying：

If：G_BM () is slow change, after integration：

Complex background gray scale G is processed more than_MM () is filtered out, bias light gray scale is disappeared, and is only left target scattering and swashs Light grey scale signal.

The present invention is in terms of two：Wake flame image and afterbody profile variations, study the working condition of electromotor, and increased can By property, operationally, jet pipe, can by monitoring the area change of jet pipe on-line in contraction or expansion state for electromotor To analyze engine behavior, and the brightness of wake flame has very big relation with motor power, monitors the spark in wake flame Can be with assistant analysis engine chamber combustion case, when occurring the spark that occur in wake flame, or engines tail Profile changes at portion's jet pipe, can in time assess the quality of engine performance, and the present invention becomes wake flame image and afterbody profile Change to analyze to combine and can more fully react the service behaviour of electromotor.Due to the technical characterstic of the present invention, regarded based on machine The aircraft engine drive end unit detection method of feel can be not only used for the detection of aircraft engine, can be also used for other aircraft and sends out The detection of motivation, there is the good suitability.

One of ordinary skill in the art will be appreciated that embodiment described here is to aid in reader and understands this Bright principle, it should be understood that protection scope of the present invention is not limited to such especially statement and embodiment.This area It is each that those of ordinary skill can make various other without departing from essence of the invention according to these technologies enlightenment disclosed by the invention Plant concrete deformation and combine, these deformations and combination are still within the scope of the present invention.

Claims (2)

1. the aircraft engine drive end unit contour measuring method of machine vision is based on, it is characterised in that in electromotor afterbody side Relative position is provided with laser beam emitting head, is respectively equipped with CCD with the relative position of obliquely downward above electromotor rear side is retreaded and takes the photograph Camera；Further, computer, pulse generator, linear array semiconductor laser and manipulator, the control of computer are also included Output connects ccd video camera by delay circuit, and the controlled output of computer is also connected with pulse generator, pulse generator Output is connected respectively with ccd video camera and linear array semiconductor laser, and the line laser battle array of linear array semiconductor laser is entered Manipulator carries out intensity modulation, and the line laser battle array after modulators modulate is by laser beam emitting head vertical illumination to engines tail Portion side, ccd video camera capture electromotor afterbody linear array profile diagram, and the image of acquisition is uploaded to into meter by image pick-up card Calculation machine；

Measuring method specifically includes following steps：

S1：Using principle of triangulation, the image that characteristic point is imaged in ccd video camera, the i.e. pass of image coordinate system are obtained in advance System, recycles position relationship of the characteristic point in world coordinate system, obtains the mapping between world coordinate system and image coordinate system Relational expression；

S2：Image is obtained, linear array semiconductor laser is opened, two ccd video cameras distinguish capture images, and ccd video camera is obtained Image include afterbody flame figure and profile diagram；

S3：Bias light is eliminated, profile diagram is obtained from high light using laser lock imaging：Take in a cycle of modulating frequency Some width images, and storage sinusoidal signal in a computer carries out multiplication and low pass filter operation, by the gray scale of bias light Filter, only retain laser grey scale signal, obtain engines tail contouring image；

S4：Image semantic classification, the engines tail contouring image obtained to S3 is filtered, smooths and micronization processes, obtains list Pixel profile image；

S5：Contour correction, using the mapping relations formula between world coordinate system and image coordinate system, by laser light belt image coordinate The anti-image coordinate for pushing away world coordinate system of system, so as to obtain the three-dimensional information of testee；

S6：Image co-registration, the image that two ccd video cameras are obtained is merged, and obtains final product aircraft engine drive end unit 180 degree wheel It is wide.

2. aircraft engine drive end unit contour measuring method according to claim 1, it is characterised in that in described step S3 Eliminating the detailed process of bias light includes following sub-step：

S31：If the grey scale signal function of the consecutive image that ccd video camera is gathered is：

G (m)=G_B(m)+G_L(m) (1)

Wherein, G_BThe gradation of image of m bias light that () is scattered by target, G_LThe image ash of m laser that () is scattered by target Degree；

For Sine Modulated laser, have：

G_L(m)=G_L0(1+ξsin(ωΔtm+φ)) (2)

Wherein, G_L0It is constant with φ, ξ represents modulation degree, and ω represents modulation angular frequency, and Δ t is the time difference between two width images；

S32：Carry out multiplying：

$\begin{array}{c}{G}_M\left(m\right)\∝\left(G_B\right(m)+G_{L0}(1+\mathrm{\ξ}\sin \left(wm\mathrm{\Δ}t+\mathrm{\φ}\right)\left)\right)\×\sin \left(wm\mathrm{\Δ}t\right)\\ =\left(G_B\right(m)+G_{L0})\sin \left(wm\mathrm{\Δ}t\right)+\frac{1}{2}{G}_{L0}\mathrm{\ξ}\left(\cos \right(\mathrm{\φ})+\cos (2wm\mathrm{\Δ}t+\mathrm{\φ}\left)\right)\end{array}---\left(3\right);$

If：G_BM () is slow change, after integration：

$G_I=\underset{m}{\Σ}{G}_M\left(m\right)\∝{\mathrm{\ξG}}_{L0}\left(cos\mathrm{\φ}\right)/2---\left(4\right)$

Complex background gray scale G is processed more than_MM () is filtered out, bias light gray scale is disappeared, and is only left target scattering laser ash Degree signal.