Kornilin D. V.

Kornilin D. V., Kudryavtsev I. A., Medvedev M. V.

Kudryavtsev I. A.

Medvedev M. V.

English

Samara University

Session 5. Design and construction of small satellites and its systems 126 SYSTEM OF VISUAL MONITORING OF PAYLOAD SEPARATION PARAMETERS D.V. Kornilin, I.A. Kudryavtsev, M.V. Medvedev Samara State Aerospace University, Samara, Russia kornilin@mail.ru One of the most important problems in the control of the process of separation of the pay-load and launch vehicle is a visual control. It important in order to determine the presence of colli-sions, and monitor the parameters of detachement as well. One of such parameters is the velocity of separation, as well as the angular speed. At the moment there are no sufficiently simple and effec-tive systems (in Russia) able to solve the problem of visual control of the process of separation of such objects. The proposed system [1] consists of two cameras mounted on the payload and rocket re-spectively, modem for data transmission, with compression capabilities and video processing mod-ule based on the embedded DSP. For the purpose of video recording in the absence of natural light, there are colored light-emitting diodes along the circumference of the top side of satellite and the launch vehicle[2,3]. At the same time camcorder captures not a whole image of the object, but only the outlines. This requires less power, and simultaneously simplifies analysis of the motion of the object [3]. We define the basic requirements for video recording system from the perspective of the analysis of motion parameters. We consider two variants of the motion of the payload:  1 Uniform removal without rotation  2 Uniform rotation about a fixed longitudinal axis. 1 Uniform removal without rotation  With a uniform disengagement of the satellite from the launch vehicle, the size of object image de-creases smoothly. The size of the image can be calculated as:  phhph  (1) where ph – the number of pixels per whole image at particular time;  hp – the height of a single pixel of the matrix, m.  Then the size of one pixel can be calculated by formula: pnhp (2) where n – matrix size m;  p – number of pixels in the matrix.   On the basis of (1) and (2), as well as the relations between the size of the object H and distance L with the focal length f [4,5,6], we obtain: nppfHLh  (3)  Let’s consider two distances L1 и L2 for which the numbers of pixels per object are equal respectively to ph1 и ph2. Then we can find the change of distance between objects ΔL. Since the objects are moving off, L2 > L1. nppppfHppfHLLLhhhh212112  (4)  Session 5. Design and construction of small satellites and its systems 127 In rectilinear uniform motion of the instantaneous velocity of mutual recession can be cal-culated according to the formula: êtLV (5) where Δtк – time interval between frames, on which the image of the object decreased by ph1 – ph2 pixels, sec. Minimal speed, which the system can catch, we propose to calculate using following: 111221hhhhpppp These equations describe differences between two frames. It should be one pixel at least. Then the formula (5) takes the form: êhhêtnpppfHtLV11)1( (6)  From the formula (6) it can be seen that a minimal speed for the case where ph1 = p. Thus, the expression (6) takes the form: êtnpfHV)1(min (7)   p = 24001234560,03 0,04 0,04 0,04 0,05 0,05 0,06 0,06 0,07 0,08 0,1 0,13 0,17 0,25 0,5 2 8Δtк, сVmin, м/сn = 3,4 мм n = 3,6 мм n = 4 мм n = 4,3 мм n = 4,8 ммn = 5,3 мм n = 6,6 мм n = 13 мм n = 15,1 мм n = 15,6 ммn = 15,7 мм n = 15,8 мм n = 24 мм  Fig. 1 - The dependence of the recorded minimal speed Vmin on time between frames Δtк for various matrices with the number of pixels p = 240  Fig. 1-3 show curves which are based on (7) for selecting the resolution of the matrix de-pending on the magnitude of the required minimal speed recorded Vmin , and at a particular time be-tween frames Δtк.  Session 5. Design and construction of small satellites and its systems 128 p = 64000,511,522,50,03 0,04 0,04 0,04 0,05 0,05 0,06 0,06 0,07 0,08 0,1 0,13 0,17 0,25 0,5 2 8Δtк, сVmin, м/сn = 3,4 мм n = 3,6 мм n = 4 мм n = 4,3 мм n = 4,8 ммn = 5,3 мм n = 6,6 мм n = 13 мм n = 15,1 мм n = 15,6 ммn = 15,7 мм n = 15,8 мм n = 24 мм  Fig. 2 - The dependence of the recorded minimal speed Vmin on time between frames Δtк for various matrices with the number of pixels p = 640  p = 76800,20,40,60,811,21,41,61,820,03 0,04 0,04 0,04 0,05 0,05 0,06 0,06 0,07 0,08 0,1 0,13 0,17 0,25 0,5 2 8Δtк, сVmin, м/сn = 3,4 мм n = 3,6 мм n = 4 мм n = 4,3 мм n = 4,8 ммn = 5,3 мм n = 6,6 мм n = 13 мм n = 15,1 мм n = 15,6 ммn = 15,7 мм n = 15,8 мм n = 24 мм  Fig. 3 - The dependence of the recorded minimal speed Vmin on time between frames Δtк for various matrices with the number of pixels p = 768  Thus, the existing video camera system allows registration of the detachment process of payloads with a minimal speed of 0.04 m / s.  Session 5. Design and construction of small satellites and its systems 129 2 Uniform rotation about a fixed longitudinal axis  Fig. 4 shows a schematic image of a separating payload. There are LEDs  mounted on the front part of it. The distance between LEDs is A. The direction of rotation is indicated by the arrow.  Fig. 4 - Schematic representation of the rotation model payload  Let’s assume that if payload rotates at the angle of φ, the image of LEDs is shifted by the distance A in pixels. The area of  such isosceles triangle can be calculated as follows: )sin(21 2  pS  (8) )21)(21(21 ApApAS   (9)   Let’s  equate the right-hand sides of formulae (8) and (9) and express the angle φ: ))21)(21(arcsin(2pApApA   (10)  The angular velocity is calculated by the formula: Session 5. Design and construction of small satellites and its systems 130 êtpApApAw))21)(21(arcsin(2 (11)  where w –  the angular velocity of the satellite, deg / s; Δtк – the time between two frames, which corresponds to movement A of LED.   The minimal speed, which can be caught by the system, we can find if  we assume A = 1. Then the formula (11) takes the form: êtppw)25.0arcsin(2min (12)  Fig. 5 shows the dependence of minimal detectable angular velocity wmin the time between frames Δtк for different numbers of pixels p.  0123456780,03 0,04 0,04 0,04 0,05 0,05 0,06 0,06 0,07 0,08 0,1 0,13 0,17 0,25 0,5 2 8Δtк, сw, град/сp = 240 p = 480 p = 512 p = 640 p = 720 p = 768 Fig. 5 - The dependence of the minimum angular velocity wmin on the time between frames Δtк for different numbers of pixels p  Thus, the minimal detectable angular velocity in the proposed system will be about 0.2 de-grees / sec.  On the basis of these results it can be concluded that the proposed system allows to record the movement of the detachable part of the launch vehicle with suitable parameters for such a sys-tem. This work was supported by the Ministry of Education and Science of the RF  Session 5. Design and construction of small satellites and its systems 131 References  1. Medvedev MV, Kornilin DV. Visual control system of the separation of the payload from the third stage of the launch vehicle // Scientific and technological experiments on unmanned space vehicles and small satellites: Abstracts of the Second International Conference "Scientific and technological experiments on unmanned space vehicles and small satellites." Samara, June 27-30, 2011 - Samara, Acad CUP Academy of Sciences, 2011 - 402 .; s. 386. 2. Medvedev MV, Kornilin DV. Evaluation of the illumination surface rocket system using visual inspection of the separation of the payload. // Regional Scientific and Practical Conference Dedicated to the 50th anniversary of the first manned kosmos.Samara, April 14-15, 2011 .: abstracts. - Samara Publisher Samara State Aerospace University, 2011 - 298 p .; s. 190-191. 3.  Medvedev MV, Kornilin DV. Estimation of the parameters of video recording of the separation of the payload in the absence of natural light // Information Technology. Radio engineering. Telecommunications: Sb. Articles I international extramural scientific and technical conference / Volga State. Univ of service. - Moscow: Publishing House of PVGUS, 2011 - 352 c. ; s. 247-254. 4.   Medvedev MV, Kornilin DV. Requirements for the lens system of visual control of the separation of the payload from the third stage of the launch vehicle .// Reshetnev read: Materials XV International Scientific Conference dedicated to the memory of chief designer of space rocket systems Academician MF Reshetnev (10-12 November 2011, Krasnoyarsk): In 2 parts. Under the general editorship of JJ Loginov; Siberian State Aerospace University - Krasnoyarsk, 2011 - Part 2: p. 584-585. 5.  Yashtold-Govorko, VA .: Photographing and processing. Shooting, formulas, terms, recipes. Ed. 4th, abbr. [Text] - M .: "Art", 1977. 6.  Volosov, DS .: photographic optics. [Text] - M .: "Art", 1971.  

System of visual monitoring of payload separation parameters

http://repo.ssau.ru/bitstream/Nauchnye-i-tehnologicheskie-eksperimenty-na-avtomaticheskih-kosmicheskih-apparatah/System-of-visual-monitoring-of-payload-separation-parameters-82247/1/%d0%9d%d0%b0%d1%83%d1%87%d0%bd%d1%8b%d0%b5%20%d0%b8%20%d1%82%d0%b5%d1%85%d0%bd%d0%be%d0%bb%d0%be%d0%b3%d0%b8%d1%87%d0%b5%d1%81%d0%ba%d0%b8%d0%b5-126-131.pdf

System of visual monitoring of payload separation parameters

Abstract

Similar works

Full text

Available Versions

Samara University