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On-sate calibration method of target distance of the sky screen target velocity measuring system
Optik - International Journal for Light and Electron Optics 178 (2019) 483–487
Contents lists available at ScienceDirect
Optik journal homepage: www.elsevier.com/locate/ijleo
Original research article
On-sate calibration method of target distance of the sky screen target velocity measuring system
T
⁎
Zhichao Wu , Xiuli Zhang Xi'An Technological University, Xi'An, 710032, China
A R T IC LE I N F O
ABS TRA CT
Keywords: Sky screen target Target distance On-sate calibration Uncertainty evaluation
For the projectile velocity accuracy problem of sky screen target velocity measurement system under the condition of shooting range test site environment, a calibration method of the target distance parameter of sky screen target velocity measuring system is proposed in this paper. According to the characteristics of the screen of sky screen target, reference plane and distance measuring datum plane components are designed, which include laser plane projection apparatus, plane normal laser projector, high precision laser rangefinder, precision platform and tripod. The target distance parameter calibration is completed cooperate with theodolite and precision optical instruments, etc. The standard uncertainty and synthesis of uncertainty of various parameters are evaluated. The expanded uncertainty of measuring target distance of 3000 mm is 1.4 mm. The gas bullets live-fire test verifies the feasibility and correctness of the calibration method.
1. Introduction The muzzle velocity of projectile is the most important parameter that determines the precision of weapon system. It is the necessary parameter of the internal ballistics and exterior ballistic test of conventional weapons. The accuracy of the test equipment is the precondition to ensure the accuracy and reliability of the test data. At present, the most important measuring device used to obtain muzzle velocity of projectile is zone-block velocity measuring system [1–3]. The system provides accurate data for the verification, finalization and acceptance of most guns and ammunition in various test ranges, and the measurement accuracy of the test equipment will have a great impact on the evaluation of the performance of the weapon system [4–6]. The sky screen target [7] belongs to the zone-block velocity measuring system. It is the precision measuring equipment which is the main measuring speed of the conventional range. Because the sky screen target velocity measuring system is a set of pairings in use, the basic parameters related to the installation of the equipment are limited by the field conditions, such as the target distance and the parallelism of the light screen of the two targets. Therefore, it is necessary to measure and calibrate the target distance parameters of the device. At present, the foreign production of the target is mainly the type of AVL460 produced by AVL company in Austria. There are not found the relevant report on verification or calibration method for the sky screen target. In China, the target is mainly used JYJ-90 type and XGK-08 type produced by Xi'an Technological University and GD-96 type produced by 203 weapons production. The existing method of target verification and calibration of the sky screen [8,9] is mainly referred to the vertification regulation of the sky screen target (WJ 2504-98) issued by China Ordnance Industry Corporation in 1999. The verification regulation [10] is only
⁎
Corresponding author. E-mail address: [email protected] (Z. Wu).
https://doi.org/10.1016/j.ijleo.2018.09.150 Received 28 July 2018; Accepted 26 September 2018 0030-4026/ © 2018 Elsevier GmbH. All rights reserved.
Optik - International Journal for Light and Electron Optics 178 (2019) 483–487
Z. Wu, X. Zhang
Fig. 1. Diagram of target distance measurement. (a) Datum plane components (b) Ranging datum plane components.
limited to the static verification of the single sky screen target in the laboratory, and the verification of the target distance parameters of the set of sky screen targets is not included. It is not possible to assess the speed accuracy of the test system in the outfield and not meet the actual demand of the target range. The measurement accuracy of the velocity measurement is greatly limited. This is not compatible with rapid development of national defense industry. In order to meet the technical requirements of high-precision testing, the portable, high-precision, easy-to-operate calibration device and method are urgently needed for the conventional weapons testing. 2. Calibration method of target distance of sky screen target Target distance of sky screen target is directly related to the accuracy of measurement, the factors that affect the measurement accuracy include results of the factory verification, the perpendicularity of the light screen plane to the horizontal plane, the parallelism of the light screen plane, the distance datum deviation, the value of the measuring instrument itself, visual factors. Therefore, the accurate calibration of the target distance is very necessary. The laser that indicated sky screen on the sky screen target has been calibrated strictly, so, the main object of calibration and measurement of the target distance is the distance of two laser planes, and the keys to calibration are their perpendicularity, parallelism, and spacing. The calibration device of the target distance of the sky screen target mainly consists of the datum plane components and the ranging datum plane components, as shown in Fig. 1. The datum plane component includes laser plane projectors, plane normal laser projector, precision platform and tripod. The range datum plane components include laser plane projectors, planar normal laser projector, high-precision laser rangefinder, precision platform and tripod. The design of lateral exploration structure has the function of adjustable pitch, rotation and translation, which can also be used to obtain the target distance of the frame measurement system such as the sky screen target and laser target. The light screen of the laser plane projectors coincides with the range datum in the calibration device by using the adjustment of theodolite. The indicating laser screen of the sky screen target coincides with the laser plane emitted by the flat projectors. According to the position relation between the laser beam and the center of the sky screen target, the flatness of the screen surface can be calculated. According to the direction angle of the laser beams projected by plane normal laser projector of two components, the parallelism of the two screen surfaces is calculated. If the flatness and parallelism of screen surfaces are in the allowable error range, the distance of two screen surfaces can be accurately measured by the laser rangefinder. 3. Test and results In the calibration device, the laser plane projectors are the linear lasers with wavelength of 635 nm, power of 90 W and the light angle of 90 degrees to 120 degrees. The straightness is better than that of 1/5000, and the line width is less than 0.5 mm. The plane normal projector is the point laser with wavelength of 650 nm and the output power of 3 mW. The power stability is better than 5%, and the beam divergence is better than 0.6 mrad. The starting plane of distance measurement coincides with the datum plane by using the theodolite. The measuring accuracy of the laser rangefinder is 1 mm, and the power of the laser range finder is 1mw. The calibration method of target distance of the sky screen target velocity measurement system is verified by compared with the integrated optical screen target on the gas bullet test. The target distance of the integrated optical screen target is fixed, and strictly calibrated. The timing mechanism principle of two sets of measuring devices is the same or similar, therefore, if the deviation of the 484
Optik - International Journal for Light and Electron Optics 178 (2019) 483–487
Z. Wu, X. Zhang
Table 1 Experimental results of target distance. serial number
target distance (S/mm)
serial number
target distance (S/mm)
1 2 3 4 5
3000 3001 3001 3000 3001
6 7 8 9 10
3001 3001 3000 3001 3000
The effective target distance is 3000.6 mm.
test results to the same velocity of projectile is very small by two sets of the velocity measurement device, the calibration of target distance of the sky screen target is accurate. Two sky screen targets are placed and adjusted the level in the test. The screen planes of two sky screen targets are parallel to each other. By adjusting the calibration device of sky screen target, the screen planes of the two sky screen targets overlap with the laser beam projected by laser plane projectors of the datum plane components and the ranging datum plane components, respectively. The screen planes of projected by two plane normal laser projectors are parallel to each other. The target distance is measured. The final effective target distance is the average of multiple measurement results in different location. The target distance data measured in different positions are as follows (Table 1): During the comparison test, the sky screen target velocity measurement system is located on the outside of the integrated optical target. The center points of the two systems are the same. Schematic diagram of the comparison test is shown in Fig. 2. The speed test data of the two sets of targets are shown in Table 2. Thev1is the speed measured by the integrated optical target. The v2 is the speed measured by the sky screen target. The Δv is the speed deviation measured by the two targets. The data results of the gas bullet show that the data deviation of two measurement systems is very small. Due to the same or similar principle of the timing mechanism of the two measuring devices, the shooting test verified the accuracy and feasibility of the distance measurement method to some extent. 4. Evaluation of measurement uncertainty a) a) Source analysis of uncertainty The factors affecting the measurement accuracy of the target distance mainly includes: deviation of the range datum, the value of measuring instrument itself, the visual interpretation, etc. The deviation of the range datum includes the overlap between the light screen plane and the plane projectors, the recombination of light screen position line and the actual light screen, the inhomogeneity of the thickness of the light screen. In the practice of measurement, it is necessary to make a reasonable evaluation of the measurement uncertainty. According to the nature of each uncertainty component, class A and class B can be evaluated. Class A uncertainty evaluation: The components are statistically analyzed through a series of observed data. According to the measurement data of target distance of the sky screen target test system in the test, the standard deviation of single measurement is calculated by Bessel method:
Fig. 2. Schematic diagram of the comparison test. 485
Optik - International Journal for Light and Electron Optics 178 (2019) 483–487
Z. Wu, X. Zhang
Table 2 Test results of the gas bullet. serial number
v1/(m/s)
v 2 /(m/s)
Δv / (m/s)
1 2 3 4 5 6 7 8 9
145.57 150.27 159.95 137.54 127.25 152.51 161.11 133.87 142.17
145.61 150.26 159.95 137.54 127.21 152.51 161.08 133.88 142.15
−0.04 0.01 0 0 0.04 0 0.03 −0.01 0.02
10
σ=
∑i= 1 (Si−S)2 10-1
= 0.20mm
The class A uncertainty evaluation uA was 0.2 mm. Class B uncertainty evaluation: The components are not evaluated by a series of statistics, but by the probability of getting information based on experience or other channels. (1) The uncertainty component introduced by the point laser u1: According to the design scheme of the calibration system, the point laser has a positioning error. The measurement error range is 0.2 mm, which subjects to uniform distribution. The half width of distribution range is 0.2, and the coverage factor is 3 . Standard uncertainty of point laser:
u1 =
0.2 = 0.12mm 3
(2) The uncertainty component introduced by a line laser u2: The straightness of line laser is greater than or equal to 1/5000. The distance used in the scheme is calculated by 3 m. The half width of distribution range is 0.5, and the coverage factor is 3 . Standard uncertainty of line laser:
u2 =
0.5 = 0.29mm 3
(3) Uncertainty component introduced by theodolite u3: The laser alignment is completed by using theodolite with accuracy of 2″. The measurement error obeys uniform distribution. The half width of distribution range is 0.021 mm, and the coverage factor is 3 . Standard uncertainty component introduced by theodolite:
u3 = 0.012mm (4) The uncertainty component introduced by laser rangefinder u4: The accuracy of Leica laser rangefinder is 1 mm. The measurement error obeys uniform distribution. The half width of distribution range is 1 mm, and the coverage factor is 3 . Standard uncertainty component introduced by laser rangefinder:
u4 = 0.58mm (5) The uncertainty component introduced by range datum u5: The deviation of the range includes the overlap between the light screen plane and the plane projectors, the recombination of light screen position line and the actual light screen, the inhomogeneity of the thickness of the light screen, the parallelism of the two light screens and the recombination of the laser rangefinder and the range datum, etc. Despite the strict adjustment, there are still some errors. Considering the above factors, the uncertainty component of 0.24 mm is introduced. (6) The uncertainty component introduced by visual interpretation u6: The recombination of the calibrating device and the laser of sky screen target observed by the naked eye. The eye can distinguish the angle of 20″, combined with the edge judgment of laser line. The visual interpretation precision is about 0.3 mm. The Standard uncertainty component introduced by visual interpretation: u6 = 0.17mm. b) Composite uncertainty:
Uc =
uA2 + u12 + u22 + u32 + u42 + u52 + u62 = 0.71
c) When the confidence probability is 95% and k = 2, the expanded uncertainty is: 486
Optik - International Journal for Light and Electron Optics 178 (2019) 483–487
Z. Wu, X. Zhang
U = 0.71 × 2 ≈ 1.4mm d) The measurement uncertainty report of the target range. The extended uncertainty of measurement results of the target distance is 1.4 mm, then, S =(3000.6 ± 1.4)mm. The confidence probability is 95%. 5. Conclusions In this article, according to the principle and characteristics of sky screen target speed measurement system, the on-sate calibration scheme of target range in the test field is designed. Using laser plane projection apparatus, plane normal laser projector, high precision laser rangefinder, precision platform and tripod, the target distance parameter calibration is competed cooperate with theodolite and precision optical instruments. This paper analyzes the main factors affecting the target distance measurement and calibration, carries out the measurement uncertainty evaluation, and gives the evaluation report of uncertainty S =(3000.6 ± 1.4) mm, The confidence probability is 95%. Based on the test gas bullet firing on sky screen target and integrated optical target, the maximum deviation of speed test results is 0.04 m/s. Because the principle of the two sets of targets is basically the same, the measurement error is mainly caused by the target distance. Therefore, the consistency of the two sets of targets test data proves the feasibility of the target range calibration scheme of the test site, and ensures the accuracy and reliability of the sky screen target speed measurement system. Acknowledgements Funding: This work was supported by the National Natural Science Foundation of China [grant numbers 61471289]. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10]
T. Dong, H. Li, Sl. Ma, Improved distance measurement of wide-angle sky screen, J. Xi’An Technol. Univ. 28 (2008) 212–214. D.G. Zhao, H.C. Zhou, J. Liu, et al., High-precision velocity measuring system for projectiles based on retro -reflective laser screen, Optik 124 (2013) 544–548. J.P. Ni, J.K. Wei, Advances in sky screen technology, J. Xi’An Inst. Technol. 31 (2011) 589–596. C.L. Yi, C.R. Zhao, L. Zhou, et al., The assessment method of zone-block velocity measuring system’s calibration and measuring uncertainty, J. Project. Rock. Missil. Guid. 35 (2015) 181–183. J.G. Su, Precision analysis for measuring the velocity of projectile by P. C. C, J. Ballist. 2 (1994) 47. Y. An, T.L. Wang, The wide angle sky screen accuracy analysis, J. Xi’An Inst. Technol. 17 (1997) 46. H.S. Li, Space target optical characteristics and SNR calculation model on sky screen, IEEE Sens. J. 16 (2016) 912–917. Z.C. Wu, J.P. Ni, X.L. Zhang, et al., Study on verification device of screen spatial location parameters of sky screen target, Optik 125 (2014) 3770–3773. R. Chen, J.P. Ni, Calibration method of light-screen plane equation of sky screen vertical target, Optik 155 (2018) 276–284. H.F. Shi, T.L. Wang, Y. An, et al., WJ2504-1998. Verification Regulation of Sky Screen Target, Chinese Ordnance industry Corporation, Beijing, 1998.
487
Contents lists available at ScienceDirect
Optik journal homepage: www.elsevier.com/locate/ijleo
Original research article
On-sate calibration method of target distance of the sky screen target velocity measuring system
T
⁎
Zhichao Wu , Xiuli Zhang Xi'An Technological University, Xi'An, 710032, China
A R T IC LE I N F O
ABS TRA CT
Keywords: Sky screen target Target distance On-sate calibration Uncertainty evaluation
For the projectile velocity accuracy problem of sky screen target velocity measurement system under the condition of shooting range test site environment, a calibration method of the target distance parameter of sky screen target velocity measuring system is proposed in this paper. According to the characteristics of the screen of sky screen target, reference plane and distance measuring datum plane components are designed, which include laser plane projection apparatus, plane normal laser projector, high precision laser rangefinder, precision platform and tripod. The target distance parameter calibration is completed cooperate with theodolite and precision optical instruments, etc. The standard uncertainty and synthesis of uncertainty of various parameters are evaluated. The expanded uncertainty of measuring target distance of 3000 mm is 1.4 mm. The gas bullets live-fire test verifies the feasibility and correctness of the calibration method.
1. Introduction The muzzle velocity of projectile is the most important parameter that determines the precision of weapon system. It is the necessary parameter of the internal ballistics and exterior ballistic test of conventional weapons. The accuracy of the test equipment is the precondition to ensure the accuracy and reliability of the test data. At present, the most important measuring device used to obtain muzzle velocity of projectile is zone-block velocity measuring system [1–3]. The system provides accurate data for the verification, finalization and acceptance of most guns and ammunition in various test ranges, and the measurement accuracy of the test equipment will have a great impact on the evaluation of the performance of the weapon system [4–6]. The sky screen target [7] belongs to the zone-block velocity measuring system. It is the precision measuring equipment which is the main measuring speed of the conventional range. Because the sky screen target velocity measuring system is a set of pairings in use, the basic parameters related to the installation of the equipment are limited by the field conditions, such as the target distance and the parallelism of the light screen of the two targets. Therefore, it is necessary to measure and calibrate the target distance parameters of the device. At present, the foreign production of the target is mainly the type of AVL460 produced by AVL company in Austria. There are not found the relevant report on verification or calibration method for the sky screen target. In China, the target is mainly used JYJ-90 type and XGK-08 type produced by Xi'an Technological University and GD-96 type produced by 203 weapons production. The existing method of target verification and calibration of the sky screen [8,9] is mainly referred to the vertification regulation of the sky screen target (WJ 2504-98) issued by China Ordnance Industry Corporation in 1999. The verification regulation [10] is only
⁎
Corresponding author. E-mail address: [email protected] (Z. Wu).
https://doi.org/10.1016/j.ijleo.2018.09.150 Received 28 July 2018; Accepted 26 September 2018 0030-4026/ © 2018 Elsevier GmbH. All rights reserved.
Optik - International Journal for Light and Electron Optics 178 (2019) 483–487
Z. Wu, X. Zhang
Fig. 1. Diagram of target distance measurement. (a) Datum plane components (b) Ranging datum plane components.
limited to the static verification of the single sky screen target in the laboratory, and the verification of the target distance parameters of the set of sky screen targets is not included. It is not possible to assess the speed accuracy of the test system in the outfield and not meet the actual demand of the target range. The measurement accuracy of the velocity measurement is greatly limited. This is not compatible with rapid development of national defense industry. In order to meet the technical requirements of high-precision testing, the portable, high-precision, easy-to-operate calibration device and method are urgently needed for the conventional weapons testing. 2. Calibration method of target distance of sky screen target Target distance of sky screen target is directly related to the accuracy of measurement, the factors that affect the measurement accuracy include results of the factory verification, the perpendicularity of the light screen plane to the horizontal plane, the parallelism of the light screen plane, the distance datum deviation, the value of the measuring instrument itself, visual factors. Therefore, the accurate calibration of the target distance is very necessary. The laser that indicated sky screen on the sky screen target has been calibrated strictly, so, the main object of calibration and measurement of the target distance is the distance of two laser planes, and the keys to calibration are their perpendicularity, parallelism, and spacing. The calibration device of the target distance of the sky screen target mainly consists of the datum plane components and the ranging datum plane components, as shown in Fig. 1. The datum plane component includes laser plane projectors, plane normal laser projector, precision platform and tripod. The range datum plane components include laser plane projectors, planar normal laser projector, high-precision laser rangefinder, precision platform and tripod. The design of lateral exploration structure has the function of adjustable pitch, rotation and translation, which can also be used to obtain the target distance of the frame measurement system such as the sky screen target and laser target. The light screen of the laser plane projectors coincides with the range datum in the calibration device by using the adjustment of theodolite. The indicating laser screen of the sky screen target coincides with the laser plane emitted by the flat projectors. According to the position relation between the laser beam and the center of the sky screen target, the flatness of the screen surface can be calculated. According to the direction angle of the laser beams projected by plane normal laser projector of two components, the parallelism of the two screen surfaces is calculated. If the flatness and parallelism of screen surfaces are in the allowable error range, the distance of two screen surfaces can be accurately measured by the laser rangefinder. 3. Test and results In the calibration device, the laser plane projectors are the linear lasers with wavelength of 635 nm, power of 90 W and the light angle of 90 degrees to 120 degrees. The straightness is better than that of 1/5000, and the line width is less than 0.5 mm. The plane normal projector is the point laser with wavelength of 650 nm and the output power of 3 mW. The power stability is better than 5%, and the beam divergence is better than 0.6 mrad. The starting plane of distance measurement coincides with the datum plane by using the theodolite. The measuring accuracy of the laser rangefinder is 1 mm, and the power of the laser range finder is 1mw. The calibration method of target distance of the sky screen target velocity measurement system is verified by compared with the integrated optical screen target on the gas bullet test. The target distance of the integrated optical screen target is fixed, and strictly calibrated. The timing mechanism principle of two sets of measuring devices is the same or similar, therefore, if the deviation of the 484
Optik - International Journal for Light and Electron Optics 178 (2019) 483–487
Z. Wu, X. Zhang
Table 1 Experimental results of target distance. serial number
target distance (S/mm)
serial number
target distance (S/mm)
1 2 3 4 5
3000 3001 3001 3000 3001
6 7 8 9 10
3001 3001 3000 3001 3000
The effective target distance is 3000.6 mm.
test results to the same velocity of projectile is very small by two sets of the velocity measurement device, the calibration of target distance of the sky screen target is accurate. Two sky screen targets are placed and adjusted the level in the test. The screen planes of two sky screen targets are parallel to each other. By adjusting the calibration device of sky screen target, the screen planes of the two sky screen targets overlap with the laser beam projected by laser plane projectors of the datum plane components and the ranging datum plane components, respectively. The screen planes of projected by two plane normal laser projectors are parallel to each other. The target distance is measured. The final effective target distance is the average of multiple measurement results in different location. The target distance data measured in different positions are as follows (Table 1): During the comparison test, the sky screen target velocity measurement system is located on the outside of the integrated optical target. The center points of the two systems are the same. Schematic diagram of the comparison test is shown in Fig. 2. The speed test data of the two sets of targets are shown in Table 2. Thev1is the speed measured by the integrated optical target. The v2 is the speed measured by the sky screen target. The Δv is the speed deviation measured by the two targets. The data results of the gas bullet show that the data deviation of two measurement systems is very small. Due to the same or similar principle of the timing mechanism of the two measuring devices, the shooting test verified the accuracy and feasibility of the distance measurement method to some extent. 4. Evaluation of measurement uncertainty a) a) Source analysis of uncertainty The factors affecting the measurement accuracy of the target distance mainly includes: deviation of the range datum, the value of measuring instrument itself, the visual interpretation, etc. The deviation of the range datum includes the overlap between the light screen plane and the plane projectors, the recombination of light screen position line and the actual light screen, the inhomogeneity of the thickness of the light screen. In the practice of measurement, it is necessary to make a reasonable evaluation of the measurement uncertainty. According to the nature of each uncertainty component, class A and class B can be evaluated. Class A uncertainty evaluation: The components are statistically analyzed through a series of observed data. According to the measurement data of target distance of the sky screen target test system in the test, the standard deviation of single measurement is calculated by Bessel method:
Fig. 2. Schematic diagram of the comparison test. 485
Optik - International Journal for Light and Electron Optics 178 (2019) 483–487
Z. Wu, X. Zhang
Table 2 Test results of the gas bullet. serial number
v1/(m/s)
v 2 /(m/s)
Δv / (m/s)
1 2 3 4 5 6 7 8 9
145.57 150.27 159.95 137.54 127.25 152.51 161.11 133.87 142.17
145.61 150.26 159.95 137.54 127.21 152.51 161.08 133.88 142.15
−0.04 0.01 0 0 0.04 0 0.03 −0.01 0.02
10
σ=
∑i= 1 (Si−S)2 10-1
= 0.20mm
The class A uncertainty evaluation uA was 0.2 mm. Class B uncertainty evaluation: The components are not evaluated by a series of statistics, but by the probability of getting information based on experience or other channels. (1) The uncertainty component introduced by the point laser u1: According to the design scheme of the calibration system, the point laser has a positioning error. The measurement error range is 0.2 mm, which subjects to uniform distribution. The half width of distribution range is 0.2, and the coverage factor is 3 . Standard uncertainty of point laser:
u1 =
0.2 = 0.12mm 3
(2) The uncertainty component introduced by a line laser u2: The straightness of line laser is greater than or equal to 1/5000. The distance used in the scheme is calculated by 3 m. The half width of distribution range is 0.5, and the coverage factor is 3 . Standard uncertainty of line laser:
u2 =
0.5 = 0.29mm 3
(3) Uncertainty component introduced by theodolite u3: The laser alignment is completed by using theodolite with accuracy of 2″. The measurement error obeys uniform distribution. The half width of distribution range is 0.021 mm, and the coverage factor is 3 . Standard uncertainty component introduced by theodolite:
u3 = 0.012mm (4) The uncertainty component introduced by laser rangefinder u4: The accuracy of Leica laser rangefinder is 1 mm. The measurement error obeys uniform distribution. The half width of distribution range is 1 mm, and the coverage factor is 3 . Standard uncertainty component introduced by laser rangefinder:
u4 = 0.58mm (5) The uncertainty component introduced by range datum u5: The deviation of the range includes the overlap between the light screen plane and the plane projectors, the recombination of light screen position line and the actual light screen, the inhomogeneity of the thickness of the light screen, the parallelism of the two light screens and the recombination of the laser rangefinder and the range datum, etc. Despite the strict adjustment, there are still some errors. Considering the above factors, the uncertainty component of 0.24 mm is introduced. (6) The uncertainty component introduced by visual interpretation u6: The recombination of the calibrating device and the laser of sky screen target observed by the naked eye. The eye can distinguish the angle of 20″, combined with the edge judgment of laser line. The visual interpretation precision is about 0.3 mm. The Standard uncertainty component introduced by visual interpretation: u6 = 0.17mm. b) Composite uncertainty:
Uc =
uA2 + u12 + u22 + u32 + u42 + u52 + u62 = 0.71
c) When the confidence probability is 95% and k = 2, the expanded uncertainty is: 486
Optik - International Journal for Light and Electron Optics 178 (2019) 483–487
Z. Wu, X. Zhang
U = 0.71 × 2 ≈ 1.4mm d) The measurement uncertainty report of the target range. The extended uncertainty of measurement results of the target distance is 1.4 mm, then, S =(3000.6 ± 1.4)mm. The confidence probability is 95%. 5. Conclusions In this article, according to the principle and characteristics of sky screen target speed measurement system, the on-sate calibration scheme of target range in the test field is designed. Using laser plane projection apparatus, plane normal laser projector, high precision laser rangefinder, precision platform and tripod, the target distance parameter calibration is competed cooperate with theodolite and precision optical instruments. This paper analyzes the main factors affecting the target distance measurement and calibration, carries out the measurement uncertainty evaluation, and gives the evaluation report of uncertainty S =(3000.6 ± 1.4) mm, The confidence probability is 95%. Based on the test gas bullet firing on sky screen target and integrated optical target, the maximum deviation of speed test results is 0.04 m/s. Because the principle of the two sets of targets is basically the same, the measurement error is mainly caused by the target distance. Therefore, the consistency of the two sets of targets test data proves the feasibility of the target range calibration scheme of the test site, and ensures the accuracy and reliability of the sky screen target speed measurement system. Acknowledgements Funding: This work was supported by the National Natural Science Foundation of China [grant numbers 61471289]. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10]
T. Dong, H. Li, Sl. Ma, Improved distance measurement of wide-angle sky screen, J. Xi’An Technol. Univ. 28 (2008) 212–214. D.G. Zhao, H.C. Zhou, J. Liu, et al., High-precision velocity measuring system for projectiles based on retro -reflective laser screen, Optik 124 (2013) 544–548. J.P. Ni, J.K. Wei, Advances in sky screen technology, J. Xi’An Inst. Technol. 31 (2011) 589–596. C.L. Yi, C.R. Zhao, L. Zhou, et al., The assessment method of zone-block velocity measuring system’s calibration and measuring uncertainty, J. Project. Rock. Missil. Guid. 35 (2015) 181–183. J.G. Su, Precision analysis for measuring the velocity of projectile by P. C. C, J. Ballist. 2 (1994) 47. Y. An, T.L. Wang, The wide angle sky screen accuracy analysis, J. Xi’An Inst. Technol. 17 (1997) 46. H.S. Li, Space target optical characteristics and SNR calculation model on sky screen, IEEE Sens. J. 16 (2016) 912–917. Z.C. Wu, J.P. Ni, X.L. Zhang, et al., Study on verification device of screen spatial location parameters of sky screen target, Optik 125 (2014) 3770–3773. R. Chen, J.P. Ni, Calibration method of light-screen plane equation of sky screen vertical target, Optik 155 (2018) 276–284. H.F. Shi, T.L. Wang, Y. An, et al., WJ2504-1998. Verification Regulation of Sky Screen Target, Chinese Ordnance industry Corporation, Beijing, 1998.
487