EP0628782B1 - Optische Vorrichtung zur eindeutigen Messung des Rollwinkels eines Geschosses - Google Patents

Optische Vorrichtung zur eindeutigen Messung des Rollwinkels eines Geschosses Download PDF

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Publication number
EP0628782B1
EP0628782B1 EP94401232A EP94401232A EP0628782B1 EP 0628782 B1 EP0628782 B1 EP 0628782B1 EP 94401232 A EP94401232 A EP 94401232A EP 94401232 A EP94401232 A EP 94401232A EP 0628782 B1 EP0628782 B1 EP 0628782B1
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EP
European Patent Office
Prior art keywords
projectile
polarizer
angle
index
roll angle
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Expired - Lifetime
Application number
EP94401232A
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English (en)
French (fr)
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EP0628782A1 (de
Inventor
Patrice Jano
Sylvie Rat
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Thales SA
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Thomson CSF SA
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Publication date
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F41—WEAPONS
    • F41G—WEAPON SIGHTS; AIMING
    • F41G7/00—Direction control systems for self-propelled missiles
    • F41G7/20—Direction control systems for self-propelled missiles based on continuous observation of target position
    • F41G7/30—Command link guidance systems
    • F41G7/301—Details
    • F41G7/305—Details for spin-stabilized missiles

Definitions

  • the present invention relates to the measurement of the roll angle of a projectile.
  • control surfaces control surfaces, impellers, jets of gas ... and therefore know their orientation relative to a plane passing through a horizontal or vertical axis and the longitudinal axis of the projectile or missile that is to say the angle of roll.
  • this optical measurement of the roll angle of a projectile has an ambiguity of ⁇ .
  • it is known either to be based on prior knowledge of the initial roll angle, ie, according to document EP 485,292, add an additional optical device on the back of the projectile, such as that a reflective dihedral which is unmasked vis-à-vis the source of illumination only once per roll revolution.
  • the object of the present invention is an optical measurement of the angle rolling of an unambiguous projectile requiring minimal of elements on board the projectile or missile.
  • Its object is an unambiguous optical measurement system the roll angle of a projectile launched by launching means located in a shooting station.
  • This device comprises, on the rear of the projectile, a reflector equipped with a polarizer and, at the shooting station, a light source which is laterally offset from the firing axis of the projectile and whose beam illuminates the back of the projectile, and a light flux analyzer operating on the luminous flux reflected from the rear of the projectile.
  • the polarizer is a break index polarizer arranged on the back of the projectile, in front of the reflector, with an angle of inclination between the direction normal to its index variation plane and the longitudinal axis of the chosen projectile greater than the Brewster angle, in a range of monotonic variation of the transmission coefficient.
  • the lateral offset of the light source relative to the shooting axis of the projectile causes the angle of incidence of the light beam on the polarizer varies around the value of the tilt angle of the polarizer as a function of the roll angle of the projectile. This causes a variation in the coefficient of transmission of the polarizer resulting in beam intensity modulation light reflected from the rear of the projectile whose period corresponds to a roll.
  • the transmission coefficient of the polarizer goes through a maximum or a minimum to distinguish the two possible roll angle values.
  • the analyzer it is enough to design the analyzer so that its detected signal passes through a maximum when the direction of polarization of the beam reflected by the projectile passes in the plane defined by the axis of fire and the line of sight of the source bright because this maximum will take two different values for the two possible roll angle values.
  • the polarizer with index break is advantageously constituted of one or more overlapping blades of transparent index material greater than 1. It can also be a polarizer with dielectric layers or a Glan-Thompson polarizer.
  • FIG. 1 there is a shooting station 1 equipped with a gun 2 having just launched a guided projectile 3 towards a target 4.
  • the device lens for measuring the roll angle of the guided projectile 3 comprises, at shooting station 1, a light source 5 consisting of a laser pointed at the rear of the guided projectile 3 and a light flux analyzer 6 which is mechanically coupled to the light source 5 and which analyzes the direction of polarization of the luminous flux reflected by the rear of the guided projectile 3 to deduce its roll angle at any time.
  • the laser constituting the light source 5 is pointed at the projectile guided 3 by a conventional tracking system. Besides, it operates in pulses to transmit control orders to the guided projectile 3.
  • the guided projectile 3 is ejected from the barrel 2 with a movement of roll rotation. It includes, as shown in Figure 2, at least a lateral impeller consisting of a lateral gas ejection orifice 10 which may or may not be placed at the center of gravity and which is coupled to a gas generator on board the projectile via a valve opened by pulses under the control of a piloting device responding to orders transmitted by laser pulses. On demand, the valve lets out a short burst of gas propulsion through the side ejection orifice. This moves the projectile 3 which is deflected in the direction where the thrust of the puff of gas and leaves its old trajectory 11 to adopt one new 12. Obviously, to be able to use the impeller (s) sideways wisely, it is necessary to know at all times the angle of projectile roll 3.
  • the guided projectile 3 is equipped on its rear face, as shown in Figure 3, a reflector 15 preceded by a polarizer 16.
  • the reflector 15 can be, as shown, a trihedron reflector made using a cube corner. It is an optical invariant which returns the light beams received in their directions of incidence.
  • the polarizer 16, which will be detailed later, does not allow a light beam as the component of rectilinear polarization parallel to its own direction of polarization which is related to the roll angle of the projectile.
  • the light source 5 generating the incident beam may be rectilinear polarization.
  • the polarizer 16 assumed to be perfect, does not allow the beam to pass as the component parallel to its polarization direction. In the case of intended use, where the reflector is uniformly lit, this will reflects on the reflector without changing the polarization direction then back through the polarizer in the direction of the incident light flux independently of the attitude of the projectile according to the other angles of pitch and yaw.
  • the analyzer 6 which is, in this case, a simple receiver optical sensitive to the intensity of the light flux received, detects the intensity of this luminous flux component returned by the projectile 3 and puts in evidence its intensity variation law which is a function in square cosine the roll angle (Malus law).
  • the light source 5 generating the incident beam can also be unpolarized or circularly polarized.
  • the polarizer 16 assumed perfect, always only lets the beam through the component parallel to its direction of polarization which is reflected on the reflector without changing the direction of polarization then crosses the polarizer again the direction of the incident light flux regardless of the attitude of the projectile 3 according to the other angles of pitch and yaw.
  • the analyzer 6 in this case includes a polarizer arranged as a polarization analyzer in front of an optical receiver sensitive to the intensity of the light flux received. he detects the direction of polarization of the luminous flux returned by the projectile 3 and generates a signal whose level varies according to a cosine function roll angle square (Malus law).
  • a polarizer at break in index which is available on the rear face of the projectile 3 of way that the direction normal to its index variation plane and the axis longitudinal of the projectile 3 make an angle of inclination greater than the Brewster angle value and the light source is shifted laterally 1 and the analyzer 6 so that the angle of incidence of the source beam light 1 on the index variation plane of the polarizer varies slightly on either side of the angle of inclination as a function of the roll angle.
  • the coefficient of polarizer transmission has two distinct values one more larger than the other. If you set the polarization direction of the source light or that of the analyzer's polarizer to obtain maximum measurement signal for this direction of polarization, this maximum will take, due to the two possible values of the transmission coefficient, two separate values for the two values at ⁇ near the roll angle corresponding to this direction of polarization which will make it possible to lift the ambiguity of ⁇ .
  • a polarizer with an index break can be schematized, as in FIG. 4, by a polarizing plate 20.
  • This reflects the component perpendicular to the plane of incidence defined by the normal to the surface of the plate and the direction of the incident wave, and lets itself be traversed by the component parallel to the plane of incidence.
  • the transmission of the component parallel to the plane of incidence of two rays R 1 , R 2 falling on the polarizing plate 20 is shown at a point A.
  • the one R 1 of the rays made with the normal N at point A an angle of incidence i 1 and has its polarized component parallel to the plane of incidence which crosses the plate 20 at an angle of refraction r 1 .
  • the other R 2 of the rays made with the normal N at point A an angle of incidence i 2 and has its component with polarization parallel to the plane of incidence which crosses the plate 20 at an angle of refraction r 2 .
  • the transmission T remains close to one, increasing with the angle of incidence up to a maximum value reached for a value of angle of incidence said Brewster's neighbor here by 57 ° then decreases monotonically for cancel for an angle of incidence of 90 °.
  • the transmission factor T presents significant variations while retaining high values. By being in this range of operation, it is possible to perform intensity modulation without however absorb too much light energy.
  • an intensity modulation of the light beam reflected by the projectile as a function of the roll angle we have the polarizer blade (s) on the back of the projectile with a tilt angle corresponding to the chosen average angle of incidence and laterally shifts the light source and the analyzer relative to the axis of firing to obtain an offset angle of the order of three at medium distance degrees. For example, we can shift the light source laterally and the 25-meter analyzer in relation to the shooting station, which provides an offset angle of 3 degrees when the projectile is aimed at 500 meters distance.
  • the marked amplitude difference between the two maxima that presents the measurement signal for the same polarization direction of the beam reflected by the projectile but for two opposite angle values of roll allows an easy removal of the ambiguity of ⁇ in the case where one has dealing with a projectile spinning on itself which is where ambiguity most problematic because it cannot be easily lifted from the knowledge of the initial attitude of the projectile. It suffices to locate among two consecutive maxima the largest or the smallest of them. We can then assign a roll angle value known to within 2 ⁇ . That can be done for example by equipping the analyzer's output with a detector relative maximum followed by a level comparator.
  • this ambiguity based on difference level existing between two consecutive maxima in the measurement signal due to the intensity modulation takes place at the time of hanging of the light beam on the projectile, at a distance of the order of 500 meters. Because, below this distance, the modulation rate is more important but the pursuit of the projectile is difficult to ensure, especially if this last one is fast, and beyond this distance, the modulation rate decreases since the offset angle under which the light source targets the projectile diminishes with the distance of the projectile.
  • break index polarizer In the embodiments described, no mention has been made of break index polarizer than blade polarizers but it's fine obvious that break index polarizers of another type such as dielectric layer or Glan-Thompson polarizers are suitable also.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • General Engineering & Computer Science (AREA)
  • Optical Radar Systems And Details Thereof (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Claims (5)

  1. Optisches System zum eindeutigen Messen des Rollwinkels eines Projektils (3), das von Abschußmitteln (2) abgeschossen wurde, die in einer Schießstation (1) angeordnet sind, mit einem mit einem Polarisator (16) versehenen Rückstrahler (15) am hinteren Abschnitt des Projektils (3), einer Lichtquelle (5) an der Schießstation (1), die bezüglich der Schußachse des Projektils (3) seitlich versetzt ist und deren Lichtstrahl den hinteren Abschnitt des Projektils beleuchtet, und einer Lichtstromanalysevorrichtung (6), welche mit dem vom hinteren Abschnitt des Projektils (3) reflektierten Lichtstrom arbeitet, dadurch gekennzeichnet, daß der Polarisator (16) ein Polarisator mit starker Änderung des Brechungsindexes ist, der am hinteren Abschnitt des Projektils (3) vor dem Rückstrahler (15) mit einem Neigungswinkel zwischen der zu seiner Ebene der Änderung des Brechungsindexes senkrechten Richtung und der Längsachse des Projektils (3) angeordnet ist, der in einem Bereich monotoner Änderung des Durchlaßfaktors größer als der Brewster-Winkel gewählt ist, wobei der seitliche Versatz der Lichtquelle (5) bezüglich der Schußachse des Projektils (3) bewirkt, daß der Einfallswinkel des Lichtstrahls auf den Polarisator (16) sich um den Wert des Neigungswinkels des Polarisators (16) herum in Abhängigkeit vom Rollwinkel ändert, was der Änderung der Polarisationsrichtung des von dem Projektil (3) zurückgeworfenen Lichtstrahls, die bis auf π vom Rollwinkel abhängt, eine Intensitätsmodulation hinzufügt, die bis auf 2π vom Rollwinkel abhängt, daß die Lichtquelle (5) und die Lichtstromanalysevorrichtung (6) so geregelt sind, daß ein Meßsignal für die Polarisationsrichtung geliefert wird, dessen Maxima, die zwei um π getrennten Werten des Rollwinkels entsprechen, mit dem Maximum und dem Minimum der Intensitätsmodulation zusammenfallen, und daß die Lichtstromanalysevorrichtung (6) Mittel enthält, um die beiden möglichen Maxima des Meßsignals mittels ihrer unterschiedlichen relativen Höhen zu unterscheiden.
  2. System nach Anspruch 1, dadurch gekennzeichnet, daß der Polarisator mit starker Änderung des Brechungsindexes ein Polarisator mit transparentem Plättchen ist.
  3. System nach Anspruch 1, dadurch gekennzeichnet, daß der Polarisator mit starker Änderung des Brechungsindexes durch Übereinanderlegen von mehreren transparenten Plättchen gebildet ist.
  4. System nach Anspruch 1, dadurch gekennzeichnet, daß der Polarisator mit starker Änderung des Brechungsindexes ein Polarisator mit mehreren dielektrischen Schichten ist.
  5. System nach Anspruch 1, dadurch gekennzeichnet, daß der Polarisator mit starker Änderung des Brechungsindexes ein Glan-Thompson-Polarisator ist.
EP94401232A 1993-06-08 1994-06-03 Optische Vorrichtung zur eindeutigen Messung des Rollwinkels eines Geschosses Expired - Lifetime EP0628782B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9306833A FR2706205B1 (fr) 1993-06-08 1993-06-08 Dispositif optique de mesure sans ambiguité de l'angle de roulis d'un projectile.
FR9306833 1993-06-08

Publications (2)

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EP0628782A1 EP0628782A1 (de) 1994-12-14
EP0628782B1 true EP0628782B1 (de) 1998-05-06

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EP94401232A Expired - Lifetime EP0628782B1 (de) 1993-06-08 1994-06-03 Optische Vorrichtung zur eindeutigen Messung des Rollwinkels eines Geschosses

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US (1) US5490643A (de)
EP (1) EP0628782B1 (de)
DE (1) DE69410013T2 (de)
FR (1) FR2706205B1 (de)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4416211C2 (de) * 1994-05-07 1996-09-26 Rheinmetall Ind Gmbh Verfahren und Vorrichtung zur Flugbahnkorrektur von Geschossen
FR2733326B1 (fr) * 1995-04-24 1997-06-06 Aerospatiale Systeme pour determiner la position et l'angle de roulis d'un mobile
FR2751797B1 (fr) * 1996-07-23 1999-02-05 Thomson Csf Dispositif de mesure d'alignement d'une chaine d'amplification laser
FR2759208B1 (fr) * 1997-01-31 1999-05-07 Thomson Csf Dispositif de controle du pointage et de la focalisation des chaines laser sur une cible
FR2802652B1 (fr) 1999-12-15 2002-03-22 Thomson Csf Dispositif de mesure non ambigue du roulis d'un projectile, et application a la correction de trajectoire d'un projectile
US6851645B1 (en) * 2003-12-05 2005-02-08 Lockheed Martin Corporation Non-coherent fresnel direction finding method and apparatus
US7589663B1 (en) * 2006-01-20 2009-09-15 The United States Of America As Represented By The Secretary Of The Army System and method for the measurement of the unambiguous roll angle of a projectile
US10259607B2 (en) * 2008-03-04 2019-04-16 Vanrx Pharmasystems Inc. Aseptic robotic filling system and method
US8093539B2 (en) * 2009-05-21 2012-01-10 Omnitek Partners Llc Integrated reference source and target designator system for high-precision guidance of guided munitions
DE102010004820A1 (de) * 2010-01-15 2011-07-21 Rheinmetall Air Defence Ag Verfahren zur Flugbahnkorrektur eines insbesondere endphasengelenkten Geschosses sowie Geschoss zur Durchführung des Verfahrens
US10962990B2 (en) * 2019-08-07 2021-03-30 Bae Systems Information And Electronic Systems Integration Inc. Attitude determination by pulse beacon and low cost inertial measuring unit

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Publication number Priority date Publication date Assignee Title
US3995792A (en) * 1974-10-15 1976-12-07 The United States Of America As Represented By The Secretary Of The Army Laser missile guidance system
DE2650139C2 (de) * 1976-10-30 1982-04-22 Eltro GmbH, Gesellschaft für Strahlungstechnik, 6900 Heidelberg Verfahren und Vorrichtung zur Korrektur der Flugbahn eines Geschosses
US4072281A (en) * 1976-12-27 1978-02-07 The United States Of America As Represented By The Secretary Of The Army Optical attitude reference
NL8501616A (nl) * 1985-06-05 1987-01-02 Hollandse Signaalapparaten Bv Inrichting voor het bepalen van de rotatiestand van een om haar lengteas roterend voorwerp.
FR2669108B1 (fr) * 1990-11-09 1997-01-03 Thomson Csf Dispositif optique de mesure de l'angle de roulis d'un projectile.

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Publication number Publication date
FR2706205A1 (fr) 1994-12-16
DE69410013T2 (de) 1998-09-03
DE69410013D1 (de) 1998-06-10
US5490643A (en) 1996-02-13
EP0628782A1 (de) 1994-12-14
FR2706205B1 (fr) 1995-07-21

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