EP2009387A1 - Method of controlling the triggering of an attack module and device implementing such a method - Google Patents

Abstract

The process involves programming coordinates of a target (3) into a fixed terrestrial reference (4) before firing or on trajectory, and determining the orientation of direction of action (WH) in the fixed terrestrial reference on the trajectory. The initiation of an attack module (2) e.g. projectile, is authorized, if the direction of action is oriented in the direction of target. The determination of the orientation of the direction of action is made by measuring the orientation of the attack module with respect to the components of the terrestrial magnetic field. An independent claim is also included for an initiation control device for an attack module.

Description

The technical field of the invention is that of devices for controlling the triggering of a driver module having at least one determined direction of action.

By attack module having a determined direction of action is meant a projectile or subproject which acts in a preferential manner in a given direction of space.

This is the case of projectiles or subprojects with a formed charge (hollow charge or nucleus generating charge). In this case the direction of action is the one in which the core or the hollow charge jet is projected. For example, the patent FR2793314 describes a sub-projectile with a known nucleus generating charge.

This is also the case for projectiles or sub-projectiles comprising a splinter generator designed to project the splinters only in a given average direction. For example, it is known to replace the charge liner in a core-generating charge with a housing containing pre-formed chips.

The initiation of this charge projects a sheaf of fragments in a given direction which is the axis of the charge. The chips scatter slightly around the projection axis and result in an impact surface on a target that has a given area (depending on the charge / target distance). The patent EP1045222 describes such a load projecting splinters in a given direction.

The projectiles or sub-projectiles thus having a determined direction of action are particularly interesting because they allow a control of the risk zone. Collateral damage can be minimized, only the targeted target is in principle destroyed.

These attack modules thus make it possible to limit the effects to a well-defined sector, which was not the case with conventional projectiles or projectiles, for example explosive artillery shells that generate bursts in all directions of the space surrounding the axis of the shell.

One of the problems posed by the attack modules having a determined direction of action is however that it is necessary to orient them towards the desired target.

Projectiles are thus known that are brought into contact with or near the target, either by direct fire (shell-shaped shells fired in tight fire without guidance) or by indirect fire.

In the case of indirect fire, however, it is necessary to provide guidance and steering means for bringing the projectile to the target, for example steerable control surfaces controlled by a homing device. We can consult patents EP905473 or FR2847033 who describe such guided projectiles.

Also known are sub-projectiles devoid of control means but which are designed to scan a field area with a target sensor (for example an infrared sensor). In this case the shot is fired when the sub-projectile detects a target having the desired silhouette characteristics. Licences GB2090950 and US4858532 describe such known subproils.

These sub-projectiles devoid of control means however still have disadvantages.

They can only attack targets with a well-defined and recognizable signature. They can not therefore be used against undetectable targets.

In addition, these sub-projectiles have the risk of inadvertent triggering by false targets (lures or targets already reached by another sub-projectile) or by friendly targets.

The object of the invention is to propose a device for triggering an attack module (such as a projectile or a sub-projectile) making it possible to increase the control of the risk zone.

The device according to the invention can be implemented with projectiles or under projectiles devoid of control means and also lacking target detection means, which makes it possible to reduce the susceptibilities of these projectiles or under projectiles to jamming or masking. .

The device nevertheless ensures that these projectiles or sub-projectiles have a perfect control of the dimensions of the risk zone.

The invention can also be implemented in a projectile or under projectile which is already provided with detection means.

In this case, the invention makes it possible to provide an additional firing condition that leads to improving the overall control of the efficiency zone of the driving modules. One can thus avoid any nuisance tripping and / or impose a well defined attack zone.

• on programme avant tir ou sur trajectoire les coordonnées d'au moins une cible dans un repère terrestre fixe,
• on réalise au moins une détermination sur trajectoire de l'orientation de la ou des direction(s) d'action dans le repère terrestre fixe,
• on n'autorise le déclenchement du module d'attaque que si la direction d'action se trouve orientée en direction de la cible.

Thus, the subject of the invention is a method for controlling the triggering of an attack module, such as a projectile or a sub-projectile, a driving module having at least one determined direction of action, characterized by the following steps:

• the coordinates of at least one target in a fixed terrestrial reference are programmed before firing or on trajectory,
• at least one trajectory determination of the orientation of the direction (s) of action in the fixed terrestrial reference,
• the triggering of the attack module is only allowed if the direction of action is oriented toward the target.

Advantageously, the determination of the orientation of the direction of action relative to the fixed terrestrial reference will be performed by measuring the orientation of the drive module with respect to at least two components of the Earth's magnetic field, the components of the Earth's magnetic field. otherwise known in the fixed terrestrial reference.

It will also be possible to measure a target / target module distance from the coordinates of the target in the fixed terrestrial frame, programmed before firing or on trajectory, and measurements of the coordinates of the driver module in the fixed terrestrial reference system, measurements made on the trajectory by a satellite positioning system or transmitted to the driver module from a platform equipped with tracking means .

More particularly, in order to adapt the invention to a projectile having a non-vertical trajectory, the coordinates of the attack / target module vector, calculated from the preprogrammed target coordinates as well as from the target coordinates, are calculated on a trajectory and in a fixed terrestrial reference. of those measured of the drive module and determined by means of a triaxial magnetic compass the orientation of the direction of action of the drive module in a fixed terrestrial reference.

To determine the orientation of the direction of action of the driving module in a fixed terrestrial reference, the coefficients of a matrix of passage of a reference linked to the driving module towards the fixed terrestrial reference will be calculated, these components being calculated by associating, for the points of the trajectory considered, the measurement of the components of the earth's magnetic field in a reference frame linked to the driving module and the values of the components of the magnetic field in the terrestrial frame, the latter values being known and preprogrammed in the driver module, the calculation indetermination being raised by the determination of at least one direction in the terrestrial reference of one of the axes of a reference linked to the driving module.

To remove the indetermination, we will calculate the orientation of the longitudinal axis of the attack module from a calculation of the angle of incidence of the projectile, which will be calculated from the measurements of the trajectory followed, from the speed in the terrestrial reference, as well as from the knowledge of the aerodynamic transfer function of the projectile.

To adapt the invention to a sub-projectile dispersed over a terrain zone by a carrier and animated by a descent movement along a substantially vertical axis and a rotational movement about the vertical axis the direction of action is inclined relative to the vertical axis of a given angle, a determination of the orientation of the direction of action in the fixed terrestrial reference will be made from the measurement of the components of the magnetic field in a horizontal plane, which plane is defined by two magnetic sensors carried by the driving module, the orientation of the direction of action relative to this plane being otherwise known as well as the orientation of the magnetic field in the fixed terrestrial reference.

According to one variant, it will also be possible to implement target detection means at the level of the driving module and the triggering of the attack module will only be triggered if the authorization conditions are fulfilled and a target is otherwise detected.

The invention also relates to a device for controlling the triggering of an attack module having at least one determined direction of action, and implementing such a method.

This device is characterized in that it comprises means for storing the coordinates of at least one target in a fixed terrestrial reference, means for measuring the coordinates of the drive module in the fixed terrestrial reference, as well as calculation means making it possible to determine, on a trajectory, the orientation of the direction of action of the driving module in the fixed terrestrial reference, the means ensuring the triggering of the driving module being coupled to the calculation means so as not to allow such a trigger that if the direction of action is oriented toward the target.

The means for measuring the coordinates of the driver module in the fixed terrestrial fixture may include a GPS receiver and / or a location data receiver transmitted from a remote platform.

The device may comprise at least two fixed magnetic sensors for determining the orientation of the direction of action of the driver module relative to the earth's magnetic field, memory means providing in addition, the components of the Earth's magnetic field in the fixed terrestrial reference.

When it is more particularly suited to a projectile having a non-vertical trajectory, the device is characterized in that the driving module incorporates at least three magnetic sensors and memory means making it possible to know the values of the terrestrial magnetic field in a reference frame. fixed earth for the different points of the trajectory, calculation means making it possible to determine from the different values of the earth magnetic field, the orientation of the reference linked to the driving module with respect to the terrestrial reference as well as the coordinates of the vector module attack / target in a fixed terrestrial reference, and those of the direction of action of the attack module.

When it is more particularly adapted to a sub-projectile intended to be dispersed over a terrain zone by a carrier and animated after dispersion of a downward movement along a substantially vertical axis and a rotational movement around this vertical axis (the direction of action is also inclined relative to the vertical axis of a given angle), the device is characterized in that the drive module comprises at least two magnetic sensors arranged in two directions. axes of a reference linked to the driving module, the two axes defined by these sensors thus determining a plane which will be perpendicular to the expected vertical fall axis, the orientation of the direction of action of the drive module by relative to this horizontal plane being known.

• la figure 1 schématise la mise en oeuvre d'un module d'attaque selon un premier mode de réalisation de l'invention à partir d'une plate-forme terrestre,
• la figure 2 est un schéma synoptique du dispositif de déclenchement selon l'invention,
• la figure 3 montre les différents axes, angles et vecteurs pour un module d'attaque constitué par un projectile ayant une trajectoire balistique,
• les figures 4 et 5 sont des logigrammes synthétisant les principales étapes du procédé selon l'invention,
• la figure 6 montre un mode particulier de réalisation suivant lequel on utilise un sous projectile qui est animé d'un mouvement de descente au-dessus d'une zone de terrain suivant un axe sensiblement vertical,
• la figure 7 est une vue plus détaillée du sous projectile permettant de repérer les différents axes, angles et vecteurs,
• la figure 8 est une vue analogue à la figure 7 mais

dans laquelle les vecteurs sont représentés en projection suivant un plan horizontal.The invention will be better understood on reading the following description of various embodiments, a description given with reference to the appended drawings and in which:

• the figure 1 schematizes the implementation of a driver module according to a first embodiment of the invention from a terrestrial platform,
• the figure 2 is a block diagram of the trigger device according to the invention,
• the figure 3 shows the different axes, angles and vectors for an attack module constituted by a projectile having a ballistic trajectory,
• the figures 4 and 5 are logigrams synthesizing the main steps of the process according to the invention,
• the figure 6 shows a particular embodiment according to which a sub-projectile is used which is animated by a descent movement over a terrain zone along a substantially vertical axis,
• the figure 7 is a more detailed view of the sub-projectile for locating the different axes, angles and vectors,
• the figure 8 is a view similar to the figure 7 But

in which the vectors are represented in projection along a horizontal plane.

The figure 1 shows a weapon system or shooting platform 1 (here a self-propelled artillery) which sends a projectile 2 to a target 3 in order to destroy it. This projectile 2 constitutes a driving module having a determined direction of action W _H which forms here an angle with the axis 19 of the projectile 2.

The latter follows a ballistic trajectory 5 and it also turns around its axis.

We have shown on the figure 1 a fixed terrestrial reference 4 of XYZ axes. In this frame the coordinates of the firing platform 1 are X _w Y _W Z _W , the coordinates of the projectile 2 are X _p Y _p Z _p , and those of the target 3 are X _t Y _t Z _t .

For the sake of clarity, we are talking here about point coordinates (target, platform, projectile). It is understood that the targeted targets have a certain ground surface and that the target point corresponds for example to the center of gravity of the real target. In the same way the coordinates of the projectile are for example those of its center of gravity or those of the focus of its military head.

The following description is based on theoretical geometric considerations. The skilled person can easily adapt the principles that will be described to deal with particular cases of real attack modules.

The driver module 2 incorporates a device 6 for controlling its tripping. This device ensures that the trigger will intervene only when optimal conditions are met, conditions to limit collateral damage.

The attack module 2 may include one or more formed charges (not shown) which will be projected in the direction of action W _H. It may also include a load projecting a sheaf of splinters in the mean direction W _H.

The presentation will be limited to dealing with the case of a single mean action direction W _H. A burst charge projects splinters in a substantially conical sheaf centered on this direction of action. The principles to be described can be easily adapted to the determination of the surfaces reached at ground level and to the comparison of this theoretically achieved surface with the global footprint (known and programmed) of a target to be treated.

The pyrotechnic means ensuring the end effect (firing charge formed or splinters projection) are not the subject of the present invention and will not be described in detail.

These means are well known to those skilled in the art.

The figure 2 schematically represents the structure of the control device 6. This device essentially comprises calculation means 7 which incorporate different calculation modules made in the form of algorithms stored in memories or registers.

These calculation means 7 are connected to means 20 for triggering the firing of the pyrotechnic charge of the driver module 2 (for example an electronic fuse causing the initiation of a detonator). These known means are not the subject of the present invention and will therefore not be described in detail.

The control device 6 also comprises memory means or registers (incorporated in the calculation means 7) for storing the coordinates X _t Y _t Z _t of at least one target 3 in the fixed terrestrial reference 4.

The coordinates of the target or targets 3 are introduced into the calculation means 7 from an appropriate interface 8. They are provided by a programming means 9 which is integral with the shooting platform 1.

For example, it is possible to program these coordinates before firing using electrical contacts carried by the platform 1 and connected to the programming means 9. It will also be possible to carry out the programming by inductive coupling and to associate a fixed induction loop. secured to the platform 1, loop intended to cooperate with another loop carried by the projectile 2.

It will also be possible to transmit the coordinates to the projectile 2 on its trajectory by means of a transmitter means 10 integral with the platform 1 (for example a radio signal transmitter). The interface 8 will then include a receiving antenna (not shown).

According to a characteristic of the invention, the device 6 also comprises means 11 making it possible to measure the X _p Y _p Z _p coordinates of the driver module in the fixed terrestrial reference frame 4. These means 11 may be constituted by a receiver of a satellite positioning system (or GPS).

Alternatively, the GPS receiver embedded in the projectile 2 can be replaced by a simple receiver 12 of signals supplied by a transmitter 10 (identical or different from that previously described) and integral with the platform 1. This transmitter 10 will then be coupled to a trajectory means 13 also secured to the platform 1.

The device according to the invention also comprises fixed magnetic sensors 14 (for example magneto resistors). These sensors make it possible to measure the components of the Earth's magnetic field along two or three axes of a marker linked to the projectile 2.

The measurement of the components of the Earth's magnetic field will make it possible, by means of appropriate algorithms, to position the reference linked to the projectile with respect to the terrestrial reference 4.

Moreover, the calculation means 7 also comprise memory means or registers for memorizing the components of the terrestrial magnetic field H in a fixed terrestrial reference 4 and in all points of the trajectory provided for the projectile 2.

We have shown on the figure 3 the projectile 2 equipped with three magnetic sensors 14 which define the axes GXmYmZm of a marker (here orthonormal) linked to the projectile 2.

The magnetic field H thus has, in this reference linked to the projectile, the three components H _Xm , H _Ym and H _Zm which are measured along the trajectory 5.

The same magnetic field H has also in the fixed terrestrial reference 4, positioned at the point G of the trajectory 5, components H _X , H _Y and H _Z.

The vector Vt is the velocity vector of the projectile 2 on its trajectory 5. The components of this vector in the fixed reference frame 4 as well as the coordinates of the point G at which the projectile 2 is located are known thanks to the positioning means 11 (or to the means tracking).

Since the coordinates of the point G are known on the trajectory and the coordinates of the target 3 have been programmed, the calculation means 7 can therefore at any time calculate, in the fixed reference frame 4, the coordinates of the vector Δ which connects the attack module. 2 to target 3 (vector whose standard expresses the distance from the attack module to the target).

We have shown on the figure 3 the vector W _H which is the one defining the direction of action of the projectile (or module of attack) 2. This direction of action W _H is a fixed data in the reference XmYmZm related to the projectile. This data is determined during the construction of the projectile 2. It is known, for a given projectile or attack module, how the magnetic sensors 14 are placed with respect to the military head and the direction of action of the projectile is also known. the military head with respect to the projectile body 2. The coordinates of the vector W _H in the reference linked to the projectile 2 are incorporated in memory in the calculation means 7.

According to the invention, the orientation of this direction of action W _H in the fixed terrestrial reference 4 will be determined on a trajectory.

The drive / target module distance, which is the norm of the vector Δ, is also determined by calculation.

It will then be allowed to trigger the driving module 2 if the direction of action W _H is oriented toward the target 3, ie if the vectors W _H and Δ are collinear and in the same direction, and if furthermore, the distance from the driver module 2 to the target 3 is less than or equal to the range of action of the driver module.

Indeed, the known attack modules (incorporating shaped charges or focussed flashes) have an efficiency that will depend on the distance that separates them from their target at the moment of their initiation. It is useless to trigger them at an excessive distance. It will suffice to verify that the norm of the vector Δ is less than or equal to a programmed value which is the radius of action Ra for the drive module considered and which corresponds to a suitable distance for controlling the triggering with respect to a target.

It will be noted that in the case where an attack module having a large action distance (for example between 200 meters and 500 meters) is used, it will be possible to trigger the shot when the collinearity (of the same direction) of the vectors W _H and Δ is ensured (without checking the value of the norm of Δ with respect to a radius of action).

Indeed the probability that these vectors are collinear for a distance greater than 500 meters is almost zero when flying a projectile following a ballistic trajectory.

The long range attack modules are for example those equipped with core generating charges.

The figure 4 is a logic diagram that summarizes the main steps of the method according to the invention.

Step A corresponds to the calculation of the coordinates of the vector Δ in the fixed terrestrial reference 4 (distance vector attack module / target). The standard of this vector Δ will be calculated at the same stage.

Step B corresponds to calculating the coordinates of the vector W _H (orientation of the direction of action) in the fixed terrestrial frame 4. This calculation implements steps which will be detailed later.

The test C verifies the collinearity and the same direction of the vectors W _H and Δ.

The test D satisfies (possibly) that the norm of the vector Δ is less than or equal to a reference value (radius of action Ra).

When the two tests are conclusive, step E corresponds to the triggering authorization of the attack module 2.

If either test is negative, the calculation steps continue (steps A and B).

The order of tests C and D is of course indifferent and steps A and B can be conducted simultaneously.

According to one characteristic of the method according to the invention, step B will determine the orientation of the direction of action W _H relative to the fixed terrestrial reference 4 by measuring the orientation of the driving module 2 by ratio to at least two components of the Earth's magnetic field.

We see on the figure 3 that, to know the orientation of the vector W _H in the fixed reference 4, it is sufficient to know the orientation of the reference GXmYmZm related to the projectile 2 relative to the fixed terrestrial reference 4 (the orientation of W _H in the reference linked to the projectile 2 is indeed fixed and known).

Calculations of moving from a movable marker to a fixed marker implement the Euler angles which are well known to those skilled in the art. They intervene in the determination of the coefficients of a transition matrix T allowing the computation of the coordinates of points or vectors in the fixed reference frame from the known coordinates in the movable reference linked to the projectile 2.

We can thus write the relation: $$\left({\mathrm{H}}_{\mathrm{X}}{\mathrm{H}}_{\mathrm{Y}}{\mathrm{H}}_{\mathrm{Z}}\right)\mathrm{=}\mathrm{T}\mathrm{.}\left({\mathrm{H}}_{\mathrm{Xm}}{\mathrm{H}}_{\mathrm{Ym}}{\mathrm{H}}_{\mathrm{Zm}}\right)$$

(H _X , H _Y , H _Z ) being the coordinates of the terrestrial magnetic field vector in the fixed reference frame and (H _Xm , H _Ym , H _zm ) being the coordinates of this same vector in the reference linked to the projectile.

The coefficients of the matrix T (thus the angles of Euler) depend, of course, on the attitude of the projectile 2 on trajectory, and therefore flight conditions. They vary on trajectory and must be determined in a continuous (or periodic) way.

In the field of missiles or aeronautics, these Euler angles and the coefficients of the transit matrix T are determined using inertial systems associating gyrometers and accelerometers, which are fragile and expensive equipments (which do not resist firing by a cannon).

With the method according to the invention, the known values (H _X , H _Y , H _Z ) and preprogrammed components of the magnetic field at the different points of the planned trajectory and the values (H _Xm , H _Ym , H _Zm ) that are measured by the sensors 14.

As a first approximation for the usual artillery ranges, the components of the Earth's magnetic field may be considered constant over the entire trajectory 5 of the projectile 2 and during flight time.

It is mathematically shown that the computation of the coefficients of the matrix T can not be thus solved without the knowledge of a complementary characteristic of the reference linked to the projectile 2. There exists indeed an infinity of combinations of angles of Euler making it possible to solve the equation (H _X , H _Y , H _Z ) = T. (H _Xm , H _Ym , H _Zm ).

According to the invention, this indetermination will be solved by calculating the orientation of the axis GXm of the reference linked to the projectile 2.

The axis 19 of the projectile 2 itself will be chosen as axis GXm and a conventional flight mechanics calculation will be used to determine the orientation of this axis in the terrestrial reference frame 4.

It is indeed possible thanks to the GPS positioning means 11 (or the tracking means) to know in the terrestrial reference the coordinates of the velocity vector Vt associated with the coordinates of the different points of the trajectory 5.

The classical equations of the mechanics of the flight of a projectile then make it possible to calculate in the terrestrial reference the coordinates of the axis of the projectile (vector GXm) with respect to those of the velocity vector Vt.

Indeed, the knowledge of the trajectory 5 and the speed Vt makes it possible to know the curvature of the trajectory and the acceleration to which the projectile 2 is subjected. The latter also has an aerodynamic transfer function Fta which depends on its geometry. , its mass and its matrix of inertia and which is fixed to the construction.

The implementation of the aerodynamic and flight mechanics equations allows to determine the angle of incidence Inc which separates the vectors Vt and Gxm from the transfer function Fta and the components of the acceleration calculated on trajectory. This angle Inc is a resultant angle of incidence which is measured in the plane of the vectors Vt and Gxm, which plane is perpendicular to the vector of instantaneous rotation of the projectile on its trajectory.

As a first approximation, it may be considered in certain cases that the angle Inc is zero (vector Vt collinear with the axis Gxm).

These calculations are well known to those skilled in the art and it is not necessary to detail them here.

The figure 5 is a logic diagram that details step B corresponding to the calculation of the coordinates of the vector W _H (orientation of the direction of action) in the fixed terrestrial reference 4.

The block F corresponds to the measurement by the positioning means 11, and in the terrestrial frame 4, coordinates of the vector Vt associated with the different points of the trajectory 5 located as well as calculation by derivation, (or else by determination of the radius curvature of the trajectory) accelerations to which the projectile is subjected.

The block G corresponds to the calculation of the coordinates in the fixed terrestrial reference 4 of the main axis of the projectile GXm. This calculation implements the calculations resulting from the block F as well as the aerodynamic transfer function (Fta) of the projectile 2.

The block H _M corresponds to the measurement by the sensors 14 of the components of the magnetic field in the marker of the projectile 2. The block H _RT corresponds to the determination (by reading in memories or registers of the computer 7) of the components of the terrestrial magnetic field in the terrestrial reference point at the point considered on the trajectory. On the figure 5 this block is connected to the block F to remind that the memory of the data of the magnetic field must be read with reference to the coordinates of the point considered on the trajectory of the projectile (coordinates provided by the positioning means 11).

The T block is that of calculating the coefficients of the matrix T allowing the passage of a marker linked to the projectile to a fixed terrestrial reference.

Finally, the block W _H corresponds to the computation of the coordinates of the direction of action vector W _H with respect to the fixed terrestrial reference 4.

According to a particular embodiment, the invention may advantageously be implemented for an attack module which is constituted by a sub-projectile dispersed over a terrain zone by a carrier, for example a cargo shell of artillery, drone or rocket (not shown).

Such sub-projectiles are well known to those skilled in the art.

Diagrammatically shown on the figure 6 such a sub-projectile 15. It is animated by a descent movement along a substantially vertical axis 16 and a rotational movement (speed Ω) around this vertical axis of descent.

The direction of action W _H is inclined with respect to the vertical axis 16 of a given angle β which is fixed by construction.

Thus, during the descent of the sub-projectile 15, its direction of action W _H sweeps the ground in a spiral 17 whose radius R decreases with the altitude Zp of the sub-projectile 15.

We have shown on the figure 6 the coordinates of the different points in a fixed terrestrial reference 4.

(Xp, Yp, Zp) are the coordinates of the sub-projectile 15.

(Xt, Yt, Zt) are the coordinates of the target 3.

(Xf, Yf, Zf) are the coordinates of the point of intersection with the ground of the vector direction of action W _H of the sub-projectile 15. This point corresponds to the point of theoretical impact 18 on the ground of the nucleus or the sheaf of splinters generated during the initiation of the sub-projectile 15.

The radius R is connected to the altitude Zp of the sub-projectile 15 by the trigonometric relation R = Zp.tan (β).

We have shown on the figure 6 the vector Δ (distance vector attack / target module).

The coordinates of this vector in the terrestrial reference frame are easily calculated from the coordinates (Xp, Yp, Zp) of the sub-projectile 15 (measured by the positioning means 11) and those (Xt, Yt, Zt) of the target 3 (programmed before shooting).

As in the previous embodiment, the standard of this vector Δ will be the value of a distance of attack / target module.

In accordance with the invention, it will be sought to detect the collinearity of the vectors W _H and Δ to authorize the triggering of the shot (the vectors must also have of course the same orientation).

With the particular case of a sub-projectile animated with a vertical fall motion combined with a rotation, when the vectors W _H and Δ are collinear they also have the same norm.

It is therefore generally not necessary to implement a range condition to be respected for the distance Δ. Indeed, the operational action distance of the known sub-projectiles is sufficiently large (several hundred meters) to ensure the terminal efficiency on the target. The D test ( figure 4 ) is then useless.

In some cases, for example when the sub-projectiles are dispersed at a very large distance from the ground (greater than 800 m), a test complementary to the collinearity measurement of the vectors W _H and Δ may nevertheless be provided. This test will make it possible to verify that the value of the norm of the vector Δ is less than or equal to a predefined radius of action Ra.

Alternatively, the altitude of the sub-projectile relative to the ground could be tested (using an altimeter).

The vertical drop of the sub-projectile makes it possible to simplify considerably the implementation of the method according to the invention.

In fact, the sub-projectile follows a vertical trajectory and is not subject to any lateral acceleration. It is then easy to remove the indeterminacy in the calculation of the passage matrix T allowing to go from the reference linked to the sub-projectile to the terrestrial reference. It is sufficient to consider that the axis GZm of the reference linked to the projectile is vertical. The coordinates of the axis GZm in the terrestrial reference are easily known from the sole determination of the coordinates of the point G (data by the positioning means 11).

The figure 7 shows the sub-projectile 15 as well as the positioning of two sensors 14 of the magnetic field.

The reference GXmYmZm linked to sub-projectile 15 has a privileged axis GZm which is the vertical axis.

The magnetic sensors 14 are arranged in the sub-projectile 15 so as to materialize two directions GXm and GYm which define a horizontal plane during the fall of the sub-projectile (plane perpendicular to the direction GZm).

Given the geometry of the sub-projectile 15 it is easy to control the position of the sensors 14 so that they define such a plane during the fall of the submunition.

Here an orthonormal coordinate system has been defined, but any other reference would be possible provided that the plane GXmYm is orthogonal to the vertical GZm.

As in the previous embodiment the location of the direction of action W _H with respect to the sub-projectile 15, so compared to the sensors 14 is a fixed construction data.

It is therefore easy to determine the orientation of the direction of action W _H in the fixed terrestrial reference 4 from the measurement of the components of the magnetic field in the plane GXmYm and the knowledge of the components of this field in the terrestrial reference fixed, at the measurement point considered, as they were stored in memory before firing.

The matrix of passage T allowing the change of reference is thus easily defined. The determination is all the easier with the choice of a marker linked to the projectile and having a vertical axis and a horizontal plane, it is sufficient to know a single angle of Euler, the angle α of rotation to pass from the fixed terrestrial axis GX (centered at G to the sub-projectile 15) to the axis GXm, to determine the orientation in the terrestrial reference of the sub-projectile 15 (hence its direction of action W _H ).

Two magnetic sensors 14 are sufficient to calculate the value of the angle αn formed by the projection N of the magnetic field vector with the axis GXm. We can deduce the angle α through the knowledge of the coordinates of the magnetic field in the terrestrial reference. In fact a single sensor would in principle be sufficient but, given the measurement errors of a magnetic sensor, it is necessary to use two sensors.

Such a configuration is simpler than that described above where it was necessary to measure three components of the Earth's magnetic field.

We have shown on the figure 7 the vector terrestrial magnetic field H and its projection N on the plane GXmYm defined by the sensors 14. The angle αn separates in this same plane the axis GXm and the vector N.

By way of non-limiting example, figure 8 shows how it is possible to easily calculate the orientation of the action direction W _H and to check the conditions allowing to allow or not the trigger of the attack module.

With this embodiment of the invention it is indeed wise to conduct the various calculations in the horizontal plane GXmYm.

The figure 8 thus shows the different vectors in projection in the horizontal plane. It has been arbitrarily chosen to confuse the axis GXm of the marker linked to the sub-projectile 15 with the projection W _HN of the direction of action W _H on this plane.

Such an arrangement is convenient for simplifying the equations and physically corresponds to a particular positioning of the sensor 14 with respect to the direction of action W _H. It is of course possible in practice not to confuse W _HN and GXm. What is important is to know the relative position of these two directions (position which is a fixed data of construction of the sub-projectile 15).

Αr is the angle that makes (in the horizontal plane) the projection N of the magnetic field vector H with respect to the axis GX of the fixed reference. This value is deduced from the coordinates of the magnetic field in the terrestrial frame as preprogrammed for the considered point G of the trajectory. We see that it would be possible in this case to simply memorize in the calculation means 7 only the angles αr and not the complete components of the magnetic field vector.

The angle αn formed by the projection N of the magnetic field vector with the axis GXm is measured using the sensors 14.

The vector Δ _N (projection of the vector connecting the sub-projectile 15 to the target 3) is easily determined from the coordinates Xp, Yp of the sub-projectile (given by the positioning means 11 and those Xt, Yt of the target 3 ( preprogrammed).

The norm of the vector Δ _N is such that: $${{\mathrm{\Delta }}_{\mathrm{NOT}}}^{\mathrm{2}}\mathrm{=}\mathrm{(}\mathrm{xt}\mathrm{-}\mathrm{xp}{\mathrm{)}}^{\mathrm{2}}\mathrm{+}\mathrm{(}\mathrm{yt}\mathrm{-}\mathrm{yp}{\mathrm{)}}^{\mathrm{2}}$$

And the angle αk between the vector N and the vector Δ _N is calculated from the preprogrammed value of the angle αr for the point considered and the coordinates of the sub-projectile 15 and the target 3 by: $$\mathrm{ak}\mathrm{=}\mathrm{\alpha r}\mathrm{-}\arctan \left[\left(\mathrm{yt}\mathrm{-}\mathrm{yp}\right)\mathrm{/}\left(\mathrm{xt}\mathrm{-}\mathrm{xp}\right)\right]$$

The tangent arc being defined on ± π / 2 One will of course use conventional algorithms allowing the raising of doubt on the value of the calculated arc.

• 1 la vérification d'une condition d'égalité d'angles:
  • αk = αn → les vecteurs W_H et Δ sont dans un même plan vertical,
• 2 la vérification d'une égalité de longueur (en projection dans le plan horizontal):
  • W_HN = Δ_N = Rc → en effet, dans le cas d'une chute verticale, la projection Δ_N du vecteur Δ sur le plan horizontal est une constante Rc (voir figure 6) qui est calculée sur trajectoire en fonction des coordonnées relatives du sous projectile et de la cible.

With the simplifications of calculation thus presented, we see that the conditions under which the triggering is allowed if the vectors Wh and Δ are collinear in the same direction is translated by:

• 1 the verification of a condition of equality of angles:
  • αk = αn → the vectors W _H and Δ are in the same vertical plane,
• 2 verification of equality of length (in projection in the horizontal plane):
  • W _HN = Δ _N = Rc → indeed, in the case of a vertical fall, the projection Δ _N of the vector Δ on the horizontal plane is a constant Rc (see figure 6 ) which is calculated on trajectory as a function of the relative coordinates of the sub-projectile and the target.

It should also be noted that, regardless of its orientation, and as already mentioned with reference to the figure 6 , the length W _HN is easily calculated from the altitude of the sub-projectile 15: $${\mathrm{W}}_{\mathrm{HN}}\mathrm{=}\mathrm{R}\mathrm{=}\mathrm{Zp}\mathrm{.}\tan \left(\mathrm{\beta }\right)\mathrm{.}$$

As a measurement control, it will therefore be possible to use an altimeter (for example of laser technology) to measure Zp and to check the calculated value of the W _HN standard.

As a digital application, if the invention is implemented for a sub-projectile 15 which is driven by a descent speed of 45 meters per second, a rotational speed of 15 revolutions per second and having an angle of inclination of its direction W _H : β = 30 °, we obtain with a firing initiation altitude of 100 meters a firing accuracy (radius of the circle equiprobable): CEP = 6 meters.

Such a result is obtained with standard deviations on the measurements of the GPS positioner 11 of the order of 3m, a standard deviation on the calculated angles of the order of 2 °, and a standard deviation on the altitude of the order of 5 meters.

The shooting accuracy obtained is remarkable while the sub-projectile 15 is totally devoid of target detection means.

As a variant, the method according to the invention can be implemented for a driver module that is already provided with target detection means, for example an infrared sensor.

In this case step E of the figure 4 will be followed by another test which will correspond to the verification of the presence of a target having the expected infrared characteristics (such a detection means is conventional and already implemented today).

The method according to the invention does not itself control the triggering of the attack module but it brings an additional condition to the simple target detection.

It can thus be ensured that, whatever the potential targets present in the field, the triggering of the attack module will only occur in the direction of a well-defined and programmed zone of terrain before shooting or on trajectory.

This increases the security of use of attack modules and limits the collateral effects of attacks.

Other embodiments are possible without departing from the scope of the invention. It is thus possible to implement the invention with an attack module comprising several directions of action W _H. Examples of attack modules with multi-mode loads programmable before shooting or trajectory. The calculations described above can be made for several directions of action of a given attack module. It will suffice to define which is the direction of operational action, therefore on which it is necessary to apply the conditions of authorization of shooting allowed by the invention.

The examples described have referred to the determination of a direction of action W _H whose intersection at ground level is punctual. It is of course possible, in particular when the drive module incorporates a chip load, to determine, in addition to the mean orientation of the vector W _H , the value of the ground level surface that is covered by the sheaf. splinters. This surface is easy to calculate by introducing into the projectile or under projectile the value of the opening angle of the cone of the generated sheaf (solid angle centered on the direction W _H ).

During the initial programming of the attack module, it will be possible to give not the coordinates of a point target on the ground, but the coordinates of a ground surface in which firing is authorized.

The algorithm described above will then make it possible to check whether the generated sheaf of bursts will be located or not in the authorized firing surface.

Claims (13)

Method for controlling the triggering of an attack module (2,15), such as a projectile (2) or a sub-projectile (15), a driving module having at least one determined direction of action (W _H ), characterized by the following steps: - Program before shooting or trajectory the coordinates of at least one target (3) in a fixed terrestrial reference (4), at least one trajectory determination of the orientation of the direction (s) of action (W _H ) in the fixed terrestrial reference (4) is carried out, the triggering of the driving module (2.15) is only authorized if the direction of action (W _H ) is oriented in the direction of the target (3). A method of controlling the triggering of a driving module according to claim 1, characterized in that the determination of the orientation of the direction of action (W _H ) relative to the fixed terrestrial reference (4) is performed by measuring the orientation of the driving module (2,15) with respect to at least two components of the earth's magnetic field, the components of the earth's magnetic field being known in the fixed terrestrial reference system (4). A method of controlling the triggering of a driving module according to one of claims 1 or 2, characterized in that a measurement of a driving module distance (2, 15) / target (3) is carried out on the basis of coordinates (X _t Y _t Z _t ) of the target in the fixed terrestrial reference, programmed before firing or on trajectory, and measurements of the coordinates (X _p Y _p Z _p ) of the driving module (2, 15) in the fixed terrestrial reference (4), measurements made on a trajectory by a satellite positioning system (11) or transmitted to the driving module from a platform (1) equipped with tracking means (13). A method of controlling the triggering of a driving module according to claim 3 and more particularly adapted to a projectile (2) having a non-vertical trajectory, characterized in that it is calculated on trajectory and in a fixed terrestrial reference (4) the coordinates of the vector (Δ) driving module (2) / target (3), calculated from the coordinates (X _t Y _t Z _t ) of the preprogrammed target as well as of those (X _p Y _p Z _p ) measured from the driving module (2) and using a triaxial magnetic compass to determine the direction of the direction of action (W _H ) of the modulus d attack (2) in a fixed terrestrial reference (4). Method for controlling the triggering of a driving module according to Claim 4, characterized in that , for determining the orientation of the direction of action (W _H ) of the driving module (2) in a fixed terrestrial reference (4) calculating the coefficients of a matrix (T) passing from a marker linked to the driving module (2) to the fixed terrestrial reference (4), these components being calculated by associating, for the points of the trajectory (5) considered, the measurement of the components (H _Xm , H _Ym , H _Zm ) of the Earth's magnetic field in a reference linked to the driving module (2) and the values of the components (H _X , H _Y , H _Z ) of the magnetic field in the terrestrial frame (4), the latter values being known and preprogrammed in the driving module (2), the calculation indetermination being raised by the determination of at least one direction in the terrestrial frame of one of the axes of a reference linked to the driving module (2). A method of controlling the triggering of a driving module according to claim 5, characterized in that to lift the indetermination the orientation of the longitudinal axis (GXm) of the driving module (2) is calculated from a calculation of the angle of incidence (Inc) of the projectile, calculated from the measurements of the trajectory (5) followed, the speed (Vt) in the terrestrial reference (4), as well as from knowledge of the aerodynamic transfer function of the projectile (2). A method of controlling the triggering of a driving module according to one of claims 2 or 3 and more particularly adapted to a sub-projectile (15) dispersed over a terrain zone by a carrier and animated by a movement downwardly along a substantially vertical axis (16) and a rotational movement about the axis vertical direction of descent, the direction of action (W _H ) being inclined relative to the vertical axis (16) of a given angle (β), characterized in that the determination of the orientation of the direction of action (W _H ) in the fixed terrestrial reference (4) is then performed from the measurement of the components of the magnetic field in a horizontal plane which is defined by two magnetic sensors (14) carried by the driver (15), the orientation of the direction of action (W _H ) relative to this plane being otherwise known as well as the orientation of the magnetic field in the fixed terrestrial reference (4). A method of triggering a module control circuit according one of claims 1 to 7, characterized in that it also implements at the drive module (2,15) of the target detection means and what is does not cause triggering of the drive module if the authorization conditions are met and that a target is also detected. Device for controlling the triggering of a driving module (2,15) having at least one determined direction of action, and implementing the method according to one of the preceding claims, characterized in that it comprises means ( 7) for storing the coordinates of at least one target (3) in a fixed terrestrial reference (4), means (11) for measuring the coordinates (X _p Y _p Z _p ) of the driver module (2). , 15) in the fixed terrestrial reference (4), as well as calculation means (7) making it possible to determine, on a trajectory, the orientation of the direction of action of the driving module in the fixed terrestrial reference, the means (20) ) triggering the driving module (2) being coupled to the computing means (7) so as to allow such a trigger only if the direction of action (W _H ) is oriented towards the target ( 3). Device for controlling the triggering of a driving module according to claim 9, characterized in that the means for measuring the coordinates of the driving module (2,15) in the fixed terrestrial reference frame comprise a GPS receiver (11) and / or a receiver (12) of location data transmitted from a remote platform. Device for controlling the triggering of a driving module according to one of claims 9 or 10, characterized in that it comprises at least two fixed magnetic sensors (14) making it possible to determine the orientation of the direction of action of the module driving (2,15) with respect to the Earth's magnetic field, memory means (7) further providing the components of the Earth's magnetic field in the fixed terrestrial reference (4). Device for controlling the triggering of a driving module according to claim 11, and more particularly adapted to a projectile (2) having a non-vertical trajectory, characterized in that the driving module (2) incorporates at least three magnetic sensors (14) and memory means making it possible to know the values of the terrestrial magnetic field in a fixed terrestrial reference (4) for the various points of the trajectory (5), calculation means (7) making it possible to determine from the different values of the terrestrial magnetic field, the orientation of the reference linked to the driving module (2) with respect to the terrestrial reference (4) as well as the coordinates of the vector (Δ) driving module (2) / target (3) in a fixed terrestrial reference (4), and those of the action direction (W _H ) of the driver module. Device for controlling the triggering of a driving module according to claim 11, and more particularly adapted to a sub-projectile (15) intended to be dispersed over a terrain zone by a carrier and animated after dispersion of a downward movement along a substantially vertical axis (16) as well as a rotational movement about this vertical axis, the direction of action (W _H ) being inclined with respect to the vertical axis of an angle (β) given device, characterized in that the driving module (15) comprises at least two magnetic sensors (14) arranged along two axes (GXm, Gym) of a reference linked to the driving module (15), the two axes defined by these sensors thus determining a plane which will be perpendicular to the axis (16) predicted vertical drop, the orientation of the direction of action (W _H ) of the drive module (15) relative to this horizontal plane being known.

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