EP2518433B1 - Method for automatic control of a seeker head mounted on a flying apparatus, especially a missile - Google Patents

Description

The present invention relates to a method for automatic management of a component-type self-steering device connected to the frame, which is mounted on a flying machine, and a flying machine, in particular an air-to-air missile, which is provided with such a homing device .

A "component linked to the frame" ("strapdown") self-redirector has, in the usual way, a fixed direction of observation, which is linked to the axes of the flying machine on which it is mounted.

We know that a typical homing device of a missile represents a very significant part of the total cost of this missile and can correspond to the most expensive part (sometimes up to half the cost), due in particular to the complexity of the mechanisms guidance, the details required for this orientation, and their control.

A homodirector of "component-linked components" makes it possible, by releasing these mechanisms, to reduce their cost considerably (generally by a factor of 3 to 10), which justifies the interest of such a device. seeker on a low-cost missile. The field of view of a component-type self-redirector linked to the frame is generally larger than that of a conventional self-redirecting optical aiming device, to allow the missile to continue to see the target despite an impact and / or missile slip, and despite the speed of the target.

• une dérive de la navigation de l'engin volant, en position comme en attitude. Dans ce cas, l'engin volant n'arrive pas à l'endroit où il est censé arriver et/ou il est mal orienté, et ne voit pas la cible ;
• un déplacement de la cible. La cible peut s'être déplacée et ne plus se trouver dans la zone d'observation prévue de l'autodirecteur à la fin de la phase mi-course.

For a "Lock-On After Launch"("LOAL") missile for which, by definition, the homing device locks on the target after launch, the missile does not yet see the target at the beginning of the mission . The mission starts with a so-called "half-way" guide phase ", Whose purpose is to bring the missile at a distance sufficiently close to the target so that the latter can then be detected by the homing (snapping). Nevertheless, several phenomena can lead, independently or jointly, to the absence of the target in the field of view of the homing device during this planned phase of attachment (and thus to make the mission fail):

• a drift of the navigation of the flying machine, in position as in attitude. In this case, the flying machine does not arrive at the place where it is supposed to arrive and / or it is misdirected, and does not see the target;
• a displacement of the target. The target may have moved and no longer be in the predicted viewing area of the homing device at the end of the mid-race phase.

These two phenomena therefore limit the range of the missile.

1. a) augmenter la taille du champ de l'autodirecteur ou sa portée, ce qui permet de réaliser une détection plus tôt, et suppose donc moins d'erreurs ou de déplacement de la cible à rattraper ;
2. b) améliorer les capacités de navigation pour réduire le terme d'erreur de dérive inertielle ; et
3. c) équiper le missile d'une liaison de transmission de données pour mettre à jour les coordonnées de la cible et réduire l'erreur due à cette dernière.

Several solutions are known to make the attachment phase more robust to these two phenomena of drift and displacement of the target (which naturally increases the acceptable duration of the mid-race phase, and therefore the range and capabilities missile). The following solutions can notably be cited:

1. a) increase the size of the field of the homing or its range, which makes it possible to realize a detection earlier, and thus supposes less errors or displacement of the target to catch up;
2. (b) improve navigation capabilities to reduce the term of inertial drift error; and
3. c) equip the missile with a data link to update the coordinates of the target and reduce the error due to the target.

1. a) à iso-coût, augmenter la taille du champ de l'autodirecteur se fait au détriment de la portée et de la précision, et réciproquement, l'amélioration gagnée sur l'un des paramètres se paie sur les autres, limitant (voire annulant) l'intérêt de cette solution, sauf à augmenter la qualité générale du capteur, ce qui soulève le problème du coût, mais également de la capacité technologique. En raison des contraintes induites par l'utilisation d'un autodirecteur de type à composants liés au bâti, le champ requis est déjà grand (et présente donc une faible précision), et il devient d'autant plus difficile de l'agrandir encore (problème d'encombrement optique, de précision de l'écartométrie générée) ;
2. b) concernant l'amélioration des capacités de navigation pour réduire le terme d'erreur de dérive inertielle, au-delà de l'éventuel problème de coût de cette solution (en cas d'adjonction d'un capteur additionnel (GPS par exemple) ou de choix d'une meilleure centrale de navigation), seule une partie des erreurs sont corrigées par ce biais. En outre, l'éventuel déplacement de la cible n'est pas traité ; et
3. c) concernant le fait d'équiper le missile d'une liaison de transmission de données pour mettre à jour les coordonnées de la cible, cette solution soulève des problèmes de coût, d'encombrement dans le missile, et de capacité opérationnelle (contrainte système). Elle ne permet pas non plus de corriger les erreurs dues à la dérive de navigation.

However, these various usual solutions have disadvantages. In particular :

1. a) at iso-cost, to increase the size of the field of the homing device is to the detriment of the range and the precision, and vice versa, the improvement gained on one of the parameters is paid on the others, limiting (or canceling) the interest of this solution, except to increase the general quality of the sensor, which raises the problem of cost, but also the technological capacity. Due to the constraints of using a frame-type component-type homing device, the required field is already large (and thus of low precision), and it becomes even more difficult to enlarge further ( problem of optical size, accuracy of the deviation measurement generated);
2. b) concerning the improvement of the navigation capacities to reduce the term of error of inertial drift, beyond the possible problem of cost of this solution (in case of addition of an additional sensor (GPS for example) or choosing a better navigation center), only a part of the errors are corrected by this means. In addition, the possible displacement of the target is not treated; and
3. c) concerning the fact of equipping the missile with a data transmission link to update the coordinates of the target, this solution raises problems of cost, of congestion in the missile, and of operational capacity (system constraint ). It also does not correct errors due to navigation drift.

These usual solutions are therefore not completely satisfactory.

The present invention aims to overcome these disadvantages. It relates to a method of automatic management of a component-type self-steering device connected to the frame, which is mounted on a flying machine, in particular an air missile, which has a hooking phase during which it seeks to detect a target and which comprises an observation direction, said observation direction being fixed with respect to the machine and being directed along the longitudinal axis of the latter, this management method making it possible to increase the capabilities of detection (hanging) of the target, regardless of the nature of any error (navigation error or error due to the displacement of the target), and this by avoiding the use of any sensor or additional cost.

DE 36 02 456 A1 and EP 0 714 013 A1 are cited as prior art. The document DE 36 02 456 A1 shows a homing device comprising a searcher head fixedly mounted in the guided missile. To increase the size of the homing field, the searcher head sweeps the objective area in a spiral pattern.

The document EP 0 714 013 A1 shows a control device which makes it possible to subject a flying machine to two controls intended to vary two angles: the angle between the longitudinal axis of the machine and a first axis of the transverse machine as well as the angle between the longitudinal axis of the machine and a second axis of the transverse machine, these two transverse axes defining a plane which is perpendicular to the longitudinal axis of the flying machine.

For this purpose, according to the invention, said method is remarkable in that it controls (or pilot) automatically said flying machine so as to describe the longitudinal axis of said flying machine, during the attachment phase of the 'homing, a circle of increasing radius as a function of time, and this until the detection of the target.

Thus, by this control of the flying machine intended to make him describe a circle growing around its direction of flight, it increases the area that is scanned by the seeker during the phase of attachment, whose direction of observation is fixed along the longitudinal axis of the flying machine. Consequently, the detection (catching) capabilities of the target are considerably increased, regardless of the nature of a possible error (navigation error or error due to the displacement of the target), and this by avoiding the use of any sensor or additional cost.

The invention can be applied to any type of missile homodirectector component type linked to the frame (or "strapdown") and whose attachment (observation and tracking of the target) is after shooting, type LOAL ( "Lock-On After Launch"), without any other constraint (scope, employment concept, ...), including a low-cost air-to-ground missile.

Advantageously, the initial amplitude of the control depends on the field of the homing device, and is for example equal to the half-field of said homing device.

In a preferred embodiment, the flying machine is subjected to two commands intended to vary, respectively, on the one hand the angle between a steering vector linked to the longitudinal axis of the flying machine and a first gear axis. , and on the other hand the angle between said director vector and a second gear axis, these two gear axes defining a plane which is perpendicular to the longitudinal axis of the flying machine, and these two commands are such that said angular variations are sinusoidal and out of phase by π / 2. Thus, the entire machine is imparted an oscillatory movement of its axis, to allow the homing device to scan an observation area which is considerably larger than the only field of view of the latter.

Advantageously, the period of said sinusoidal angular variations increases slightly over time to allow the flying machine to widen the search area.

The present invention also relates to a flying machine, in particular an air-to-air missile, provided with a component type self-redirector connected to the frame, which has a hooking phase during which it seeks to detect a target and which comprises a direction of observation, said observation direction being fixed relative to the flying machine and being directed along the longitudinal axis thereof.

According to the invention, said flying machine is remarkable in that it comprises automatic control means for controlling (or piloting) said flying machine so as to describe its longitudinal axis, during a flight of the flying machine during the attachment phase of the homing, a circle of increasing radius as a function of time, and this until the detection of the target.

In a preferred embodiment, said automatic control means are formed so as to subject the flying machine simultaneously to two commands intended to vary, respectively, firstly the angle between the director vector linked to the longitudinal axis. of the flying machine and a first gear axis, and secondly the angle between said steering vector and a second gear axis, these two gear axes defining a plane which is perpendicular to the longitudinal axis of the flying machine, and these two commands are such that said angular variations are sinusoidal and out of phase by π / 2.

In addition, advantageously, said automatic control means are part of an automatic control system of said flying machine, which comprises in a usual manner all the means necessary to fly the flying machine and guide it.

• La figure 1 montre de façon très schématique un missile pourvu d'un autodirecteur, auquel on applique la présente invention.
• La figure 2 est un graphique permettant d'expliquer les caractéristiques d'un mode de commande préféré d'un missile.

The figures of the appended drawing will make it clear how the invention can be realized. In these figures, identical references designate similar elements.

• The figure 1 shows very schematically a missile provided with a homing device, to which the present invention is applied.
• The figure 2 is a graph to explain the characteristics of a preferred mode of control of a missile.

The present invention is applied to a flying machine 1, in particular an air missile, shown schematically on the figure 1 , and is intended to manage the operation of a component-type self-steering device 2 connected to the frame, which is mounted on said flying machine 1.

In the usual way, such a self-redirector 2 has a hooking phase during which it seeks to detect a target C, in particular a moving target. This autodirector 2 has an observation direction 3 which is fixed relative to the flying vehicle 1 and is directed along the longitudinal axis 4 of the latter.

This flying machine 1 comprises usual control means 5 which are part of a usual control system 6 (connected by a link 7 to the homing device 2 and represented very schematically on the figure 1 ) and which comprise all the elements necessary to guide and control the flying vehicle 1 so that it can reach a target C, generally mobile. These control means 5 include information processing means which automatically generate data. piloting orders allowing the flying machine 1 to follow an intercept trajectory of the target C and control means (not shown) such as control surfaces or any other type of known elements, which automatically apply these control commands to the flying machine 1. All these usual means (of the system 6) are well known and will not be further described hereinafter.

Preferably, said flying machine 1 is a "LOAL" ("Lock-On After Launch") missile for which, by definition, the homing device 2 locks on the target C after the launch. This missile does not see target C at the beginning of the mission. Usually, the mission begins with a so-called "mid-course" guidance phase, the purpose of which is to bring the said missile at a distance sufficiently close to the target C so that the latter can then be detected by the homing device 2 .

According to the invention, said flying machine 1 further comprises automatic control means 8 for controlling (or piloting) said flying machine 1 so as to describe to the longitudinal axis 4 of said flying machine 1, during a during the attachment phase of the homing device 2 (that is to say during the search for the target C), a circle of increasing radius as a function of time. This control is implemented until the detection of the target C. Thus, thanks to the invention, the flying machine 1 is guided and controlled according to a usual trajectory by the means 5, to which guidance and control usual adds to the control implemented by the control means 8 to describe the flying vehicle 1 a circle around its direction of flight.

Thus, by this control of the flying machine 1 intended to make him describe a growing circle, the area which is observed by the self-steering 2 during the hooking phase is increased. The homing device 2 is, in fact, able to scan an observation area which is much larger than its only field of view of fixed dimensions. By therefore, the capabilities of the homing 2 to detect the target C are considerably increased, regardless of the nature of any error (navigation error or error due to the displacement of the target), and this while avoiding the use of any sensor or additional cost.

In a preferred embodiment, said automatic control means 8 are part of said automatic control system 6, which comprises in a usual manner all the means necessary to fly the flying machine 1 and guide it towards a target C.

le trièdre défini par les axes engin à l'instant où l'on souhaite débuter l'application de la commande de guidage. Comme représenté sur la figure 1, ces deux axes engin vo et $\overrightarrow{\mathit{wo}}$

définissent un plan P qui est perpendiculaire à l'axe longitudinal 4 de l'engin volant 1. On considère $\overrightarrow{\mathit{u}}$

le vecteur directeur qui lié à l'axe longitudinal 4 de l'engin 1, et on définit αv l'angle $\left(\overrightarrow{\mathit{vo}}\overrightarrow{\mathit{u}}\right)$

et αw l'angle $\left(\overrightarrow{\mathit{wo}}\overrightarrow{\mathit{u}}\right)\mathrm{.}$

Ces deux angles vérifient les relations suivantes : αv = arcsin $\left(\overrightarrow{\mathit{u}}\mathrm{.}\overrightarrow{\mathit{vo}}\right)$

et αw = arcsin $\left(\overrightarrow{\mathit{u}}\mathrm{.}\overrightarrow{\mathit{wo}}\right)\mathrm{.}$

We consider $\left(\overrightarrow{\mathit{uo}}\overrightarrow{\mathit{vo}}\overrightarrow{\mathit{wo}}\right)$

the trihedron defined by the machine axes at the moment when it is desired to start the application of the guidance command. As shown on the figure 1 , these two axes engin vo and $\overrightarrow{\mathit{wo}}$

define a plane P which is perpendicular to the longitudinal axis 4 of the flying machine 1. $\overrightarrow{\mathit{u}}$

the director vector which is linked to the longitudinal axis 4 of the machine 1, and the angle αv is defined $\left(\overrightarrow{\mathit{vo}}\overrightarrow{\mathit{u}}\right)$

and αw the angle $\left(\overrightarrow{\mathit{wo}}\overrightarrow{\mathit{u}}\right)\mathrm{.}$

These two angles satisfy the following relations: αv = arcsin $\left(\overrightarrow{\mathit{u}}\mathrm{.}\overrightarrow{\mathit{vo}}\right)$

and αw = arcsin $\left(\overrightarrow{\mathit{u}}\mathrm{.}\overrightarrow{\mathit{wo}}\right)\mathrm{.}$

The control means 8 are intended to vary these two angles αv and αw.

The principle according to the invention being to describe to the gear axis a circle of increasing radius with time, the commands generated by the control means 8 to obtain said angular variations are sinusoidal and phase shifted by π / 2, as shown on the figure 2 which shows the angular variations α (expressed in °) as a function of time t (expressed in seconds) for αv and αw. In addition, the maximum values of αv and αw increase at each half-period.

The amplitude of the angular control is preferably initially close to the value of the field of view of the homing device 2 (and may in particular be equal to the half-field of the latter, for example 15 °), which ensures the coverage of a large angular area, without creating a blind spot in the center.

The period is chosen according to the time required for observation on the zone to ensure the detection of the target C and is only given as an example on the figure 2 . It can also slowly increase over time to provide the opportunity for the flying machine 1 to expand the search area if a first pass has been unsuccessful.

The present invention, which thus widens the search area, makes it possible to reduce the impact of the drift of navigation as well as that of the displacement of the target C, and not (as the usual solutions mentioned above) only one of these two. phenomena.

In addition, it provides a significant gain, since it has been observed for a self-guided to which we have applied the present invention the performance of attachment equivalent to that of a homing device of higher capacities (same range and accuracy, but field of 48 ° instead of 33 °).

Claims (5)

1. Method for automatically managing a strapdown homing device (2), which is mounted on a projectile (1), in particular an air missile, which has a lock-on phase during which it tries to detect a target (C) and which comprises a viewing direction (3), said viewing direction (3) being fixed relative to the projectile (1) and being directed along the longitudinal axis (4) thereof, characterized in that said projectile (1) is controlled automatically so as to cause a circle, the radius of which increases over time, to be traced at the longitudinal axis (4) of said projectile (1), during the lock-on phase of the homing device (2), until the target (C) is detected.
2. Method according to claim 1, characterized in that the projectile (1) is subjected simultaneously to two controls designed to cause a variation on the one hand in the angle (αv) between a direction vector associated with the longitudinal axis of the projectile and a first projectile axis, and on the other hand in the angle (αw) between said direction vector and a second projectile axis, respectively, these two projectile axes defining a plane (P) which is perpendicular to the longitudinal axis (4) of the projectile (1), and these two controls are such that said angular variations (αv, αw) are sinusoidal and shifted by π/2.
3. Projectile, in particular an air missile, provided with a strapdown homing device (2), which has a lock-on phase during which it tries to detect a target (C) and which comprises a viewing direction (3), said viewing direction (3) being fixed relative to the projectile (1) and being directed along the longitudinal axis (4) thereof, characterized in that it comprises automatic control means (8) for automatically controlling said projectile (1) so as to cause a circle, the radius of which increases over time, to be traced at the longitudinal axis (4) of said projectile (1), in flight and during the lock-on phase of the homing device (2), until the target (C) is detected.
4. Projectile according to claim 3, characterized in that said automatic control means (8) are formed so as to subject the projectile (1) simultaneously to two controls designed to cause a variation on the one hand in the angle (av) between a direction vector associated with the longitudinal axis of the projectile and a first projectile axis and on the other hand in the angle (αw) between said direction vector and a second projectile axis, respectively, these two projectile axes defining a plane (P) which is perpendicular to the longitudinal axis (4) of the projectile (1), and in that these two controls are such that said angular variations (αv, αw) are sinusoidal and shifted by π/2.
5. Projectile according to any one of claims 3 and 4, characterized in that said automatic control means (8) form part of an automatic control system (6) of said projectile (1).

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