CC BY
70
УДК 681.7.069.24
Yu.V. Chugui, S.V. Plotnikov, A.K. Potashnikov, A.G. Verkhogliad TDI SIE SB RAS, Novosibirsk
NOVEL OPTICAL MEASURING SYSTEMS AND LASER TECHNOLOGIES FOR SCIENCE AND INDUSTRY
The novel results of the R & D activity of TDI SIE SB RAS in the field of the optical measuring technologies, as well as laser technologies for solving safety problems are presented. To measure the rocks stress and to prevent the mountain impact, as well as for basic investigations, a set of optical-electronic deformers and systems was developed and produced. For permanent noncontact bearing position inspection of oil-drilling platforms on Sakhalin coast (Russia) we have developed optical-electronic method and system SAKHALIN with cumulative traveled distance (3 km) measurement error less than 0.03 %. Multifunctional laser technological system LSP-2000 equipped by two Nd-YAG lasers was developed for cutting, welding and surface micro profiling with ablation process (working
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range of 3 x 2 x 0.6 m , positioning error less than 10 mkm). Safety of Russian nuclear reactors takes 100 % noncontact 3D dimensional inspection of all parts of fuel assemblies, including grid spacers. Results of development and testing the specialized high productive laser measuring machine, based on structured illumination, for 3D inspection of grid spacers with micron resolution are presented. Ensuring the safety of running trains is the actual task for railways. Using high-speed laser noncontact method on the base of triangulation position sensors, TDI SIE has developed and produced automatic laser diagnostic system COMPLEX for inspection of geometric parameters of wheel pairs (train speed up to 60 km/hr.), which are used successfully on Russian railroads. Experimental results on measuring and laser technological systems testing are presented.
Keywords: optical measuring technology, laser technology, safety, mining, oil and railway industries, nuclear reactor, grid spacer, structured illumination method, wheel pairs, triangulation method
1. INTRODUCTION
Modern industry and science take novel optical measuring systems and laser technologies for solving actual tasks, including safety problems for mining, oil, atomic and railroad industries [1-5]. The novel TDI SIE’s results in these trends are presented.
Effective investigation of non-linear processes in block structures of geo medium requires comprehensive measurement of wave, deformation and power parameters using the multi-channel measuring systems [2]. These systems ensure the data collection and processing from sensors (accelerometers, dynamometers, resistive-strain sensors, and displacement sensors) in real time. The development of universal technical means (with enhanced metrological characteristics) for automatic measurement of these parameters in nature and laboratory conditions
under the physical experiments is very actual. For measurement the rocks stress and prevention the mountain impact we have developed a set of optical-electronic deformers and systems for modeling and investigation of nonlinear deformation wave processes.
Oil-drilling platforms on Sakhalin coast (Russia) have seismic protection systems using massive platform (28 000 tons) and the four friction pendulum bearings. They have limited cumulative traveled distance (about 3 km). As soon as this distance exceeds that value, the bearings should be replaced. We have developed optical-electronic system SAKHALIN for permanent non-contact bearing position inspection and traveled distance measurement (error no less than 0.03%) under operating extreme temperature range from - 40° C up to + 40° C. Functional possibilities and experimental results for SAKHALIN are presented and discussed.
Laser material processing (cutting, welding) of 3D large-size objects and treatment (ablation) of their surfaces take multifunctional universal laser technological system. Such system (LSP-2000) was developed at TDI SIE. It has 5-coordinate (X-Y-Z-cp-0) table with Computer Numerical Control system, table
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displacement range of 3 x 2 x 0,6 m (position error less than 10 mkm) and changeable Nd-YAG lasers for material processing and treatment. Below the LSP-2000 technical peculiarities and performances are given.
Safety of nuclear reactors VVER-1000 and VVER-440 [4] and ensuring their high exploitation reliability takes 100 % noncontact inspection of all parts of fuel assemblies, including grid spacers (more than 300 cells with diameter 9 mm and in height of 20 mm). We have developed and produced the specialized laser measuring machine, based on structured illumination, which enable 3D inspection of grid spacers with micron resolution and high productivity (some hundred times faster than CMM).
Ensuring the safety of running trains is the actual task of railways exploitation and transport of passengers and cargoes all over the world. We have developed high-speed laser noncontact method for geometrical parameters inspection of moving 3D objects on the base of triangulation position sensors using fast-response PSD linear arrays and produced automatic laser diagnostic system COMPLEX for noncontact inspection of geometric parameters of wheel pairs, including width and thickness of wheel rim; distance between inner sides of wheels; thickness of wheel flange; uniform rolling; wheel diameter; axle sliding-off [5]. Measurements are fulfilled at freight cars speed up to 60 km/hr (the range of working temperatures is from -50° up to +50° C). Principle of self-scanning for running freight cars and testing results for system COMPLEX are given.
2. ROCKS NONLINEAR GEOMECHANICAL STUDY
BY MEASURING TECHNIQUES
In order to reveal the mechanisms of rock bursts in mines, it is necessary to study mining-induced movements of structural inhomogeneities of rocks, rock stratum displacement, and deformations. It is required to measure displacements of geoblocks and strains at different points of a massif depending on location of these
points relative to underground working contour in geomedia with both natural and induced jointing, and with allowance for structural features (disintegration zones, tectonic faults, pillars or filling masses failed by rock pressure or blasting, etc.). Institute of Mining and TDI SIE SB RAS have developed a prototype of a borehole multichannel optical-electronic longitudinal deformometer (from here on meter) [6].
The technical solution of measuring displacements of geoblocks in a rock mass is based on a “slide gauge idea”. The idea is realized using a measuring bar, which is fastened inside the massif in a borehole, and a position sensor with his sensing element attached to the rock and capable of moving freely along the bar. The bar consists of sections connected by pipe couplings. The sensor is set on a section of the bar. By doing so, we ensure the modular gathering of the instrument.
Measurements in rock masses are frequently conducted using horizontal boreholes drilled in mine working walls towards the section to be inspected. In this case, the borehole (Fig. 1) usually intersects rock blocks C1 ..., Ci formed by disintegration zones [3] and gets deeper in an intact massif part Cn. Prior to installation, we need to choose a reference point O in Cn, check points in geoblocks C1, C2,..., Ci between the zones of disintegration, and number of sensors.
The bar sections and sensors together is a pickup probe. Measuring bar 2 is fastened at the reference point O via support 1 (Fig. 1). According to the number of measured blocks, sensors 3 are installed on the bar with the sensing elements fastened to the rock at the points C1, C2,..., Cn. Having such arrangement, displacement of the i-th block under inspection will cause the same displacement of the sensing element of the corresponding sensor along the bar, which is recorded by an electron device.
Fig. 1. Scheme of measuring bar and sensors in borehole.
The position sensor is based on an electron photosensitive recording device such as the position-sensing S3270-type photodetector PSD produced by Hamamatsu Co with a resistive layer and electrodes. The sensor equipped by LED has the following characteristics: the measurement range is ± 17.5 mm; the measurement error is ± 0.02 mm.
The sensor has the following design (Fig. 2): insertion 1 built-in into the bar section and movable bushing 2 mounted on the insertion so that to move longitudinally along the guide [6]. The current position of the bushing relative to
the insertion is determined by the position of the spotlight on the photodetector. Such design allows minimization of the sensor size, simplifies fastening device, and decreases the mass and overall dimensions of the instrument. Using these sensors (Fig. 3) we have developed the measuring system providing automatic measurements of longitude shifts and deformations in rocks (actual tests in mine working).
1 - insertion, 2 - movable bushing, 3 photodetector, 4 - LED.
Fig. 3. Position sensor.
Modern phenomenological theory of pendulumtype waves, based on studies of geomechanical wave processes in structurally inhomogeneous rock masses, takes carrying out the detailed laboratory testing of models of block geomedia under uniaxial and biaxial loading. In contrast to in situ experiments, stand trial conditions can be varied widely, and it is possible to analyze effects of stress state, strain rate as well as properties and behavior of rocks under complex loading modes. The obtained measurement data need being processed both in the course of experiment and after its completion. For these purposes we have developed a prototype of a micrometer position display sensor with a microprocessor data collection system.
When measuring equipment for the geomechanical stand, the main attention has been focused on an electronic micrometer display sensor and its design with the use of a photosensitive charge-coupled device (CCD) with a LED. As a recorder, we employed a commercial position photoreceiver ILX511 produced by SONY. The photoreceiver contains 2048 photosensitive elements spaced at d = 14 mkm and forming a bar of photoreceivers 28 mm long. A photosensitive element contains a photodiode, pre-gain circuit and plugboard chart, and is intended to convert optical radiation to an electric signal. The photoreceiver ILX511 differs from the analogous functional area facilities by low electrical noise and small-scattered photosensitivity of separate elements, which ensures high metrological characteristics of measuring equipment based on the device discussed.
The sensor consists of two parts (Fig. 4): a casing serving a basis guide and a mobile stem capable of displacing along the guide. The LED is installed on the stem, and the photoreceiver, i.e. CCD-bar is arranged inside the casing along the guide. When the stem displaces, its current position relative to the casing is determined by the coordinate of the LED-generated spotlight on the photoreceiver. The micrometer sensor has been tested to determine precision of its characteristics. It is shown that the error is no more than ± 3 mkm, and with due regard for the
gauging characteristic based on the average curves of repeatability, the sensor error can be reduced
to 1 mkm.
The information measuring system on the base of electronic micrometers as a laboratory equipment (providing the investigations on the processes models that take place on structured rocks) has been developed.
Fig. 4. Functional arrangement of sensor:
1 - mobile stem; 2 - light source; 3 - CCD-bar; 4 - CCD-bar control; light source control; 6 - synchronization input; 7 -synchronization output; 8 - KLM-1 microcontroller; 9 - USB
output.
The system ensures the data collection within the process of model objects disintegration as well as their transmission on USB channels into personal computer. This system has 8 functionally finished position sensors, unified into the common system using the switchboard. The quantity of sensors can be increased when needed. It is provided by system architecture.
3. Friction pendulum bearing displacement measuring technology for oil platform
As it is known, the mining of oil and gas offshore is carried out using the drilling platforms, which are extremely massive and inert (Fig. 5). In order to avoid excessive stresses on platform it consists of few large parts (normally base and legs). Four friction pendulum bearings are used for mechanical link between the base and legs. The bearings functionality is to provide the protection of the platform from all possible mechanical loadings on the legs that might affect the base with the drill and other sensitive equipment (seismic movements, ice shifts, etc.).
Normally in the majority of regions around the world the bearings lifetime is at least 30 years of continuous use. The corresponding lifetime for the Sakhalin shelf, according to the estimations of scientists, can be from one to ten years, which is much shorter that
Topside of the Platform
Weight: 28 000 tons ,
• • 2 Dimension ~ 80x100 m
the normal service life period of the drilling platform. The most important parameter, which allows estimation the bearing resource, is measuring the cumulative
Friction Pendulum. Bearing
Platform Leg linkedje-sSabed
)ed -—^
Fig. 5. An oil-drilling platform scheme.
distance traveled by the bearing from the beginning of its service (no more than 3 km). As soon as cumulative travel exceeds that distance the bearings should be replaced.
Fig. 6. Measurement system location:
1 - slider bearing, 2 - support, 3 - platform, 4 - image unit, 5 - target.
For measurements of bearings movements the automatic optical-electronic system SAKHALIN was developed. Its main aim is
continuous noncontact
measurement of the bearing
location and calculation of the total distance traveled by the bearing for any defined time period.
Measuring principle of the system (Fig. 6) is based on optical image processing. The passive part of the system (optical target) is fixed on one part of construction, while active
part - a field measurement sensor - is installed on another part of construction that moves relative to the first one. This sensor continuously captures and processes the image of optical target. On the output, after processing the relative displacement these two parts of construction is obtained with high degree of accuracy.
The system SAKHALIN (Fig. 7) is certified as a measuring tool as well as for the use in explosive environments (for gas and oil industry). It is designed for continuous 24-hour operation during 30 years. Its main technical characteristics are the following: measurement range on the X and Y axes is ± 350 mm; absolute error in the measurement range is ±
0.6mm; measurement rate is 30 meas./s.; maximum movement speed of the objects under measurement without accuracy loss is from 0 up to 4 m/s.; working temperature for control panel is from 0 up to + 40°C. This system was put through tests accepted by customer.
This system SAKHALIN can also be used for the 24-hour monitoring of shifts and deformations of different parts of another mechanical and engineering
Fig. 7. System SAKHALIN: optical measuring and electronic units.
constructions. It has capability to provide alerts in emergency cases, i.e. excessive construction strains, displacements, earthquake, tsunami events, etc.
4. LASER TECHNOLOGICAL SYSTEM LSP-2000
We have developed the multifunctional laser technological system LSP-2000 for processing and treatment of 3D articles: cutting, welding and surface micro profiling with ablation process. The LSP-2000 system is equipped by two Nd-YAG lasers. The robotics for the laser head positioning and CNC control interface are provided for processing and treatment of parts with arbitrary topology. The system
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spatial working range is about 3 x 3 x 0.6 m . Inside this range all types of laser processing operations can be performed with contour displacement accuracy about ± 10 mkm for any point of trajectory. The general view of the system is presented
in the Fig. 8. The LSP-2000 was developed as the universal laser processing
system with unique combination of the certain parameters / technical characteristics. These characteristics are listed below:
- Multifunctionality. It means the ability to perform a range of technological and processing operations.
Each operation using custom laser processing heads, requires custom positioning accuracy, different positioning speed and movement patterns depending on the operation.
This requirement was fulfilled using two types of
technological lasers. The first laser MLTI-500 for cutting and welding (produced by
“Tulamashzavod”) has the following parameters: the
pulses repetition frequency is 300 Hz, average power output is 500 Wt, laser wavelength is 1.064 mkm. Its purpose is laser cutting and laser welding of any metals with thickness of less then 6 mm. The second laser for ablation of thin metal films on dielectric surfaces has pulses repetition frequency of 300 Hz,
n
high pulses power (>10 Wt), laser wavelength is 0.532 mkm, and average power output is 10 Wt.
- Large processing working field (3 x 3 x 0.6 ms). The absolute positioning accuracy in the whole working field is better than 20 mkm. The special XYZ movement stage was developed in order to move the tool (laser processing heads, etc) to anywhere in the working field with required accuracy. The stages movements are controlled by the special CNC system. The positioning of each
Fig. 8. Laser technological system LSP-2000 and enlarged fragment of its working processing head.
stage is feedback-controlled and based on the linear incremental optical sensors, which provide the required stage position information (position error 1 mkm).
- The ability to process the articles with the arbitrary surface shapes. For
that purpose the processing head can make the movements with 5 degrees of freedom. The processing head can be moved by XYZ carriage for bringing the head to the desired processing region. Also, two more possible movements are added in polar coordinates system. The head could rotate azimuthally and vertically (C and B coordinates) in the processing region thus it allows to orient the
head perpendicularly to any of surface element of the arbitrary 3D object, which is
under processing.
- Long term parameters stability. One of the main tasks of the current system is micro profiling of the large-size articles. The expected time for the single article processing is approximately 30 hours. The system is designed for continuous 24 hour work. At the same time it is required to keep high reproducibility and high processing accuracy for the all service life of the current system without any additional tuning. The long term stability of this device was provided using the linear motors and sliding parts having the air gap. The air gap in the moving parts makes the system mechanics frictionless and it is provided with the compressed air or pneumatic bearing principle.
The LSP-2000 system has the following technical performances:
Coordinate table travel range 3 x 3 x 0.6 m3
Maximum size of the processing parts 3 x 3 x 0.6 m3
Geometrical shapes of the processing parts arbitrary
Uncertainty of system positioning in start-stop regime < 2 mkm
Uncertainty of system positioning
along arbitrary movement loop <10 mkm
Maximum head movement speed 10 m/min
The material for ablation Al, Nl-Cr alloy
Optical head weight < 6 kg
The material for laser cutting and welding Ti, stainless steel
The maximum cutting thickness (for Ti) 6 mm
At the present time LSP-2000 is under industrial operation.
5. 3D grid spacers inspection technology
As known, a grid spacer for reactor VVER-1000 is multicell piece like honeycombed cellular structure (Fig. 9). Each cell of the grid spacer represents a hollow thin-walled integral prism, 20 mm in height, with three cylindrical protrusions in the direction of the cell center. The measuring technology must allow to inspect the following parameters of grid spacers (Fig. 10): diameters Dc(n) of the circumferences inscribed in the cells; diameters Dch(m) of the circumferences inscribed in the guide channels; the distances between neighboring cells L(k) (center-to-center distances), i.e. distances between the centers of the inscribed circumferences in the cells; the centers shifts of the inscribed circumferences for cells relative to grid spacer design drawing S(q) (the position shifts); overall dimensions B(p) “for spanner”.
Since the use of existing universal contact coordinate measuring machines (CMM) for 3D measurements of grid spacer geometry is associated with high time expenditures (up to 4 hours), we have created the specialized noncontact high productive laser measuring machine (LMM) [4].
For solving this task we have developed the modified method, which is based on a multipoint structured illumination. It ensures fast, noncontact, automated 3D-measurements of many objects. The multipoint structured illumination is light distribution as a 2D array matrix of laser beams (Fig. 11), which may be generated by kinoform elements such as, e.g., two crossed Dammann arrays. In order to overcome
Fig. 9. A grid spacer for reactor VVER-1000.
Fig. 10. Grid spacer geometric parameters under inspection.
uncertainty in determining the object position and shape, we have introduced singularity into the laser beam matrix structure as period malfunction.
In the case of 3D inspection of grid spacer cells, consisting of three protrusions, it takes three 2D laser beams matrixes (for simplicity only one light matrix is shown).
The laser measuring machine includes the three-channel laser-electronic measuring head for cell and channel holes perception, scanning X-Y table, electronics and software (Fig. 12). The scanning X-Y
illumination 3D inspection method applied to a single segment of grid spacer cell.
table with the working displacements 300 x 300 mm (OFL-2121 SM) ensures a controlled displacement of the grid spacer in the view of the photoreceiver unit in the direction of X and Y coordinates and a rotation of the grid spacer in the X-Y plane.
Fig. 12. Laser measuring Fig. 13. Individual geometric information from
machine under operation. LMM about every cell hole of the grid spacer:
its 3D image, the diameters Dc(j) and the centers coordinates Xc(j), Yc(j).
Three methods of visualization and inspection of measurement results are envisaged. The first of them represents diameters in the form of a cartogram of the grid spacer with color distinction between cells and channel holes. According to the second visualization method, shifts of centers cell and channel holes (S(q)) are represented as grid spacer cartograms with vectors going out of cell and channel centers. The module of vectors and their directions on appropriate scale illustrate the shifts, the color of vectors designate their belonging to the tolerance. And, finally, in the representation of the distances between neighboring cells (center-to-center distances) L(k), one can see on the screen the grid spacer “skeleton”: dashed lines connecting the drawn centers of cells and channel holes designate normal situations (within the tolerance), while solid lines designate distances between cells going beyond the tolerance gap.
In all the representation methods, one can inspect the individual sizes and a 3D configuration of any cell or channel hole. The result of the measurement of one cell is shown in Fig. 13. Here, diameters Dc(j) and coordinates Xc(j), Yc(j) of the inscribed circumferences centers in 16 cross-sections (1 < j < 16), as well as 2D graphs and 3D configuration of the cell hole are presented.
The laser measuring machine for 3D inspection of grid spacers has gone through a complete cycle of tests at the Novosibirsk plant JSC NCCP. The time of measurement of the indicated grid spacer parameters does not exceed 12 min, which is more than 300 times faster than existing universal contact coordinate measuring machines. At present LMM is under operation at the Novosibirsk plant JSC NCCP.
6. LASER WHEEL PAIRS DIAGNOSTIC INSPECTION FOR RUNNING TRAINS
a)
b)
Wheel
PSD
Rail
Sensor
rT^T//f7P
Fig. 14. The principle of self-scanning of running freight car wheel (a) using active measuring sensors of the triangulation type (b).
For regular
dimension inspection of wheels we have developed high-speed laser noncontact
method and measuring technology for
geometrical parameters inspection of moving 3D objects on the base of triangulation
position sensors using fast-response position sensor detector PSD (50 000 meas/s) [5].
This method is based on the principle of wheel self-scanning (Fig. 14a) by using
active measuring sensors of the triangulation type. In this case, a beam produced by a laser diode is focused on the surface of the moving object under inspection. The scattered beam is gathered by the aperture of a receiving objective. The objective forms an image of the illuminated surface zone in the PSD plane (Fig. 14b).
Using this method TDI SIE has produced automatic laser diagnostic system COMPLEX for noncontact inspection of geometric parameters of wheel pairs (Fig. 15), including: width (A) and thickness (B) of wheel rim; distance between inner sides of wheels (E); thickness of wheel flange (C); uniform rolling (F); wheel diameter (D); difference of diameters of wheels in a wheel pair D=D1-D2. Measuring error is about 0,5 mm. Measurements are fulfilled at freight cars speed up to 60 km/hr. The range of working temperatures is from -50° up to +50° C.
a)
b)
Fig. 15. Wheel parameters under inspection.
Figure 16 shows an example of the wheel reconstructed profile (crosssection). The required geometrical parameters are calculated from the reconstructed profile, in so doing, the algorithm of calculating the parameters follows the method of their measurement by means of a standard contact meter.
External view of this system COMPLEX is presented in Fig. 17. The developed diagnostic system COMPLEX corresponds to the best world prototypes. At the present time, COMPLEX more than two years is in operation at West-Siberian Railway. Today 20 systems COMPLEX are in operation on 6 Russian regional Railways (from Moscow to Far East). There were inspected more than 23 million wheel pairs for the period of system COMPLEX exploitation. 300000 alarming reports were received, more than 17000 carriages were rejected. The application of these systems allowed to improve the safety of railway industry in Russia.
Fig. 16. A wheel reconstruction profile Fig. 17. System COMPLEX under
(cross-section). operation in winter (West-Siberian
railway).
CONCLUSION
Solving many actual safety problems in mining, oil, atomic and railway industry as well as in science takes noncontact optical measurement technologies with micron resolution and productivity from 500 to 10 000 meas/s. We have developed, implemented and tested some novel optical measuring systems and laser technologies. For mining industry applications there were developed and produced two types of sensors: one position sensor for displacement measurement of geoblocks using horizontal drilling boreholes and another precision sensor for laboratory testing of models of geo medium blocks under loading. For the first time the developed system SAKHALIN can also be used for the 24-hour monitoring of shifts and deformations of very huge mechanical and engineering constructions in emergency cases, i.e. excessive construction strains, displacements, earthquakes, tsunami events, etc. Multifunctional laser technological system LSP-2000 is effective equipment for material processing and 3D treatment. If one built-in additionally the measuring probes, LSP-2000 can be used as coordinate measuring machine with very large measuring volume. In atomic industry the developed and produced laser measuring machine has allowed
to obtain objective information about the geometry of grid spacers which were subsequently used for further improvement of production of fuel assemblies for Russian nuclear reactors VVER-1000 and VVER-440. Application of automatic laser diagnostic system COMPLEX for noncontact wheel pairs dimensional inspection for running trains makes possible to increase the safety of Russian railways. The obtained results are applied to many industrial fields, including mechanical engineering, automobile industry, hydropower engineering and etc.
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2. From the first in the world AES to the atomic power of XXI century, Proc. 10th Annual Conf. of Russian Nuclear Society, Publishing house Rity “FEN” (1999) (in Russian).
3. M.V. Kurlenya, V.N. Oparin, and A.A. Eremenko, “Relation of linear block dimensions of rock to crack opening in the structural hierarchy of masses”, Fiz.-Tekh. Probl. Razrab. Polezn. Iskop., 3 (1993).
4. O.I. Bityutsky, I.G. Chapaev, Yu.V. Chugui et al, “Laser measuring machine for 3D noncontact inspection of geometrical parameters of grid spacers for nuclear reactors VVER-1000”, Proc. SPIE, 4900, 202-212 (2002).
5. A.N. Baibakov, V.M. Gurenko, V.I. Paterikin, S.P. Yunoshev, S.V. Plotnikov, V.V. Sotnikov, and Yu.V. Chugui, “Automatic control of geometrical parameters of wheel pairs during train operation”, Optoelectronics, Instrumentation and Data Processing, 40 (5), 75-82 (2004).
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© Yu.V. Chugui, S.V. Plotnikov, A.K. Potashnikov, A.G. Verkhogliad, 2006
