WO1996001404A1

WO1996001404A1 - Personal weapon sharpshooting aid

Info

Publication number: WO1996001404A1
Application number: PCT/FR1995/000878
Authority: WO
Inventors: Claude Michel; Patrick Regnault
Original assignee: Thomson-Csf
Priority date: 1994-07-05
Filing date: 1995-06-30
Publication date: 1996-01-18
Also published as: FR2722280A1; FR2722280B1

Abstract

A personal weapon (30) with a sight (31) in which a computer (7) controls a collimated reticle (10) to move it onto the future point of impact between a target and a projectile fired from the weapon. Said reticle (10) consists of line drawing means (9, 14, 20, 22, 40) continuously movable by means of electrical units (13, 21, 23, 40) that receive control inputs from the computer (7), and said computer is provided with an electrical input control program for imperceptibly moving the reticle (10) onto the future point of impact and locking it on.

Description

PRECISION SHOOTING AID FOR AN INDIVIDUAL WEAPON

The invention is in the field of individual weapons, it relates more particularly to individual weapons intended for precision shooting, in particular at long range, and equipped for this purpose with improved aiming devices.

A known device for anti-tank rocket launcher comprises an aiming telescope intended to provide a magnification of the distant optical image, angular speed sensors intended to measure the rotation speed of the weapon, wind speed sensors and a rangefinder. Aiming with such a device is carried out as follows:

In a first phase, the shooter follows the target, this means that he keeps the crosshair of the weapon fixed on the target. This first action makes it possible to measure an angular speed of movement of the target. During this phase, two measurements of the target distance are also made. These two measurements, separated by a known time, make it possible to know the distance from the target and to calculate its distance or approach speed. All these data are entered into a calculator which calculates the angular deflection to be given to the weapon so that the projectile fired meets its target. In a second phase, the computer controls means for moving a mirror placed in the optical means. The function of this mirror is to angularly move the image seen by the shooter through the optical means, without moving the reticle. The lighting of a signaling diode warns the shooter that the weapon is ready to fire. In a third phase, the shooter replaces the image of the reticle on the image of the target and shoots.

It can be seen that with such a device, the firing must rapidly follow the lighting of the diode, because if the firing lags too long, the data used for the calculation of the angular depointing are no longer current. We also see that due to the sudden displacement of the image seen by the shooter, the latter must redo a search for the target and a repointing. This necessity can lead, when several similar targets are present in the field, to a target confusion and to a choice of a false target for which the data acquired during the first phase are of no use. The subject of the present invention is an individual weapon equipped with an aiming device of the kind which has just been described, in which the image of the reticle marking the target and the image comprising the target have an insensitive relative displacement without suddenly, during the target follow-up phase, so that at the end of the follow-up phase, without the reticle having the appearance of leaving the target for the shooter, the line of sight and the axis of fire of the weapon are offset by an angle representing the angle of target depointing. It will be recalled that the deflection angle is the angle necessary between the line of sight and the firing axis of the weapon for a projectile fired by the weapon to reach the target. The aiming angle takes into account in the particular conditions of each shot, the movement of the target and the factors influencing the trajectory of the projectile. The invention therefore relates to an individual weapon comprising a barrel and an aiming device comprising a collimated reticle, optical means capturing an image of the landscape, a targeted point of the landscape being defined by the position of the reticle in the image, gun angular speed sensors intended to measure the angular speed of a target C on which the reticle would be kept, a rangefinder intended to measure the distance of this target C and a computer, the computer being provided with a program allowing it to calculating a point of impact of a munition in target C and receiving for this purpose the information coming from the angular speed sensors and from the range finder, the computer controlling means of relative displacement of the image and the reticle to reveal the reticle at the future point of impact characterized in that the reticle is constituted by means of constituting lines, these means being displaceable d e continuously or almost continuously by electrical means receiving electrical control quantities, these quantities being controllable by the computer, and in that the computer is equipped with a program for controlling electrical quantities making it possible to imperceptibly move the reticle for the '' bring it to the future point of impact and keep it there. The displacement of the line forming means is said to be continuous or almost continuous because in one of the embodiments which will be described later, the lines move in a physically discontinuous manner, the discontinuity being however not apparent to the eye. of the shooter. The displacement of the means of constituting lines, together constituting the reticle is said to be insensitive insofar as it is imperceptible to the shooter. This implies that the displacement of the reticle from an initial position to a final position is relatively slow and gradual.

The general principle of the invention and variant embodiments will now be described with reference to the appended drawings in which:

- Figure 1 is a diagram for explaining the principle of the invention;

- Figures 2 to 4 each show an embodiment of the line forming means; - Figures 5 and 6 show an individual weapon equipped with a sighting device according to the invention;

- Figure 7 shows the angles which are taken into account for the rallying of the reticle on the target;

- Figure 8 is a graph showing two ways of joining the reticle.

Figure 1 shows in the form of functions all the means contributing to the production of a weapon according to the invention. The device includes:

a means 1 for measuring the distance from the target. In the embodiment which will be described in relation to FIG. 5, it will be a laser mini-rangefinder, integral with the weapon.

a means 2 for measuring the speed of rotation of the barrel of the weapon, achievable, for example, using “solid state” mini-gyroscopes integrated in the weapon, or by image processing means in particular when the optical means for acquiring the external image is a video camera.

a means 3 for measuring the cant of the weapon, for example, an inclinometer or a static accelerometer, integral with the weapon.

a means 4 for measuring the wind speed and direction, for example a miniature anemometer secured to the weapon.

- A means 5 intended to supply a computer with data relating to the type of ammunition which will be fired. It may for example be a semiconductor read-only memory. The results of the measurements carried out by the means 1 to 4 feed a computer 6, which also receives the data relating to the ammunition from the means 5.

The computer 6 calculates, as a function of the data received, by means of dedicated software, periodically, the apparent trajectory of the target, the point of impact of the ammunition and the position shift of the reticle.

This position data is transmitted to a control block 7. This control block delivers the control voltages or currents which will supply means for moving the line-making means. The lines constituting means have not been shown in Figure 1. A conventional reticle 10 has been shown in the form of two lines 9, seen in the eyepiece 8 of a telescopic sight.

In image 8 of the eyepiece, the crossing point of two perpendicular axes 11 materializes the pointing direction of the barrel of the weapon. The axis crossing point 12 materializes the aiming axis. The crossing point of the axes 12 represents for a target moving in the direction materialized by an arrow x the correction in Δx and Δy whose reticle must be moved so that when the reticle thus displaced is positioned on the target, the axis of the cannon be shifted forward and generally above the target of Δx and Δy respectively. In the device of the prior art described above, the reticle appears actually offset by an amount Δx, Δy and the shooter must by a sudden movement catch up with the offset thus revealed. In the device according to the invention, the reticle is moved behind and generally below the target progressively at a rate imperceptible to the eye so that the shooter always has the impression of following the target. The reticle reaches the position represented by the crossing of the axes 12 after a period necessary for acquiring the target and rallying the reticle, but the shooter never had the impression of letting go of the target. Indications on the type of calculation to be introduced into the calculator to obtain this result will be given later.

FIG. 2 represents a first example of means for constituting lines. The lines are each made up of a style 14. The two styles are crossed at 90 °. The plane of Figure 2 is a longitudinal axial plane of the telescope parallel to one of the styles and perpendicular to the other. One of the styles 14 has therefore been represented in the form of a line, and the second as a point. Each of these styles is carried by a style carriage 15, only one of which has been shown. These style carriages 15 are mounted on endless screws 16. These endless screws 16 are rotated by reducing micromotors 13. The control voltages from the computer control the rotation of the motor and therefore the position of styles 14. The crossing point of the styles 14 represents the position of the reticle 10. The two styles 14 are located in the image plane 17 of a target 19 of a rifle scope mounted in a known manner on the rifle. In FIG. 2, the image plane 17 has been represented by a dotted line and the bezel by a set of two lenses, an ocular lens 18 and an objective lens 19. In this simple case, the objective 19 is the optical means picking up the image of the landscape.

FIG. 3 describes another embodiment of the line-making means. In this mode, the lines materializing the reticle 10 consist of the needles 20 of two identical galvanometers 21. The needles 20 are placed so as to be at rest perpendicular to each other in the image plane 17 of the objective 19 of a telescope shown in FIG. 3 also by its eyepiece 18 and its objective 19.

FIG. 4 describes a preferred embodiment of the line making means. These means consist of a medium whose optical characteristics change according to the value of the electromagnetic fields to which the medium is subjected. The medium may for example be constituted, in a known manner, by liquid crystals arranged between transparent plates, the field being created by a matrix network of transparent electrodes. Figure 4 shows such a device. It consists of a high definition liquid crystal screen 22 placed in the image plane 17 of the objective 19 of a telescopic sight represented by its eyepiece 18 and its objective 19. Networks of transparent electrodes 23 placed on either side on the other side of the screen allow the local modification of the optical characteristics of the crystals. It is thus possible to materialize lines which together constitute the design of the reticle 10. By controlling the electrodes from the control computer 7, it is possible to move the reticle almost continuously for the shooter. It is said almost continuously because in reality the displacement is a discontinuous displacement whose pitch is that of the matrix networks of electrodes 23. If this step is small enough, the displacement has, for the shooter the appearance of a continuous displacement.

FIG. 5 represents an individual weapon, for example a rifle 30, equipped with a device according to the invention produced according to the preferred mode. The rifle 30 is equipped with a telescopic sight 31 comprising a objective 19 and an eyepiece 18. The telescopic sight comprises in an image plane of the objective a liquid crystal screen 22 controlled by electrodes 23. The rifle is also equipped with 'a laser rangefinder 1, sensors for the rotation speed of the weapon in elevation and azimuth 2 and 2', an inclinometer 3 intended to measure the cant of the weapon and an anemometer 4 intended to measure the relative speed of the wind relative to the weapon. The parameters relating to the ammunition are introduced in the form of a plug-in card 5 in a reader 5 '. Unrepresented connections link the sensors 1 to 4 and the reader 5 ′ to a computer 6, a module 7 of which controls, by connections not shown, the electrodes 23, determining the position of the reticle 10 and the appearance of a sign indicating that the reticle is in the firing position. The other components of the weapon known in themselves such as the barrel 32 have been shown in simplified form easily recognizable by a person skilled in the art. In another preferred embodiment shown in FIG. 6 and suitable for night shooting, the telescope is replaced by a thermal camera 40. In this case, the means of constituting lines consist of a set of pixels whose gray level is controlled by the calculator to be in contrast with the background of the image. Instructions necessary for programming the computer to imperceptibly rally the reticle 10 to the target will now be given. For the following explanations, it is assumed that the shooter is pointing at a target animated with a constant speed moving at a constant distance from the shooter. After an initial phase of pursuit of the target by the shooter, the system gradually and gradually shifts the reticle behind the target. At this instant the shooter accelerates the speed of rotation of his weapon to maintain the reticle on the target. (The weapon rotation speed becomes higher than that of the target). A simple calculation shows that if no precaution is taken, this apparent acceleration of the target will be taken into account to calculate a position too far back of the reticle, then for inverse reasons too far.

We will be in the presence of a generally damped oscillatory movement. It is therefore necessary to introduce a law of rallying of the reticle to its position behind the target which avoids oscillatory movements.

The solution of such a problem is well known in servomechanism, it is given below and for all practical purposes a method of treatment.

FIG. 7 is intended to materialize the different angles which are used for the calculation. The following simplifying assumptions are made:

1. Target C moves at a constant distance De from shooter A;

2. The target has a constant speed (rotation). We set: w _c : target speed of rotation; w _c = cte for example (= 0.5 deg / sec) w _a (t): weapon rotation speed as a function of time α _c (t): target rotation angle as a function of time α _a (t) : angle of rotation of the weapon as a function of time α _m (t): angle of rotation of the reticle as a function of time D _c : target / shooter distance assumed to be constant Tp: Time of flight of the bullet to cover the distance D _c ; Tp is assumed to be constant, for example 1 second. δ: angular offset between the angle of the reticle and the angle of the weapon [δ = a _m (t) - a _a {t)}

Under these conditions and according to the assumptions: δ = -w _a (t) .T _p (1) cc, „(0 = cc _a (t) + δ (2) _c (t) = w _c . T + cte ( 3)

That said, imagine the following scenario shown in Figure 8.

1. The shooter spots a target. He will adjust his aim by bringing the crosshair to the target and initiate a chase. In this phase, the reticle remains in the center of the viewfinder (it is not updated) but the acquisition sequence of all the parameters is initialized and the calculation blocks 6 are quickly able to visualize the point of impact of the ball if the shot was fired at that time. At the end of this phase we have: ^w a (0 = ^w c = ^cte ( ⁴ )

2. As soon as the shooter considers that the target is well hooked, he informs the computer by pressing lightly on the trigger tail which corresponds to the instant t = 0 on the graph in figure 8.

The reticle must then shift by an amount: δ = w _a . T _p = - w _c . T _p

During this movement, the shooter who continues to follow the target with his reticle will give the rifle an accelerated speed of rotation. To avoid oscillating movements of rallying to the new position, rallying must be done asymptotically or tangentially.

This point is illustrated by the graph in FIG. 8. In this figure, time is represented on the abscissa and the value of the angles on the ordinate, all measured from the same axis of arbitrary origin. In this figure the angle a _c (t) which represents the angular displacement of the target is represented by a straight line CC since by assumption the angular speed of the target is constant.

The angle which the axis of the rifle must follow, the angle _a (t) corresponds to an angle increased with respect to a _c (t) by the quantity δ = w _a .T _p . It is therefore a straight line AA 'parallel to CC but offset according to the ordinate of a positive quantity δf. This offset will be obtained by shifting the reticle backwards by a negative quantity δf. The position in the final phase of the reticle is therefore represented by the line RR '. The line RR 'is symmetrical with the line AA' with respect to the line CC. At the instant 0 which corresponds to the moment when the computer 6 determined the value of δf, the reticle and the axis of the barrel are aligned and we have δ = 0. We will have to grow δ negatively to its value δf. This corresponds to a displacement behind the reticle up to δf. If the displacement is carried out in such a way that δf asymptotically joins the straight line RR 'and if the shooter continues to maintain the reticle on the target then the gun moves in front of the target and asymptotically reaches the straight line AA' at the same instant t “ j. These displacements of the reticle and the barrel are represented by the curves DE and DF.

We know that there are infinitely many solutions for DE to join RR 'asymptotically. If we choose to make δ grow from 0 to δf according to an exponential then the value of the exponent will determine the speed and therefore the time after which δ will be practically equal to δf. It will be necessary to take a time constant (the exponent of the exponential) which represents a compromise between a rapid transition between 0 and δf which is desirable, and too great acceleration from D which is likely to disturb the shooter.

It is also possible to take families of curves such as DH which are tangent to the line CC at point 0 and to the line RR 'at a point H. The abscissa of point H is also a function of the joining speed. The curve DG which represents the rallying of the barrel will also be tangent in D to the line CC and in G of the same abscissa as H to the line AA '. There will thus be a smooth and jerk-free transition in acceleration between the initial position and the final position.

The explanations above are intended to show that the problem posed is soluble on the one hand and to show the elements leading to a possible solution.

The DE or DH curves can be calculated point by point or preferably as the result of simple functions.

Claims

1. Individual weapon (30) comprising a barrel (32) and a sighting device (31) comprising a collimated reticle (10), optical means (19.40) capturing an image of the landscape, a targeted point of the landscape being defined by the position of the reticle (10) in the image, angular speed sensors (2,2 ′) of the gun intended to measure the angular speed of a target (C) on which the reticle (10) would be kept, a rangefinder (1) intended to measure the distance of this target (C) and a calculator (6,7), the calculator (6,7) being provided with a program allowing it to calculate a point of impact of a munition in the target (C) and receiving for this purpose the information coming from the angular speed sensors (2,2 ') and from the rangefinder (1), the computer controlling means of relative displacement of the image and the reticle (10 ) to reveal the reticle (10) at the future point of impact characterized in that the reticle (10) is constituted by means of constitutions of lines (9,14,20,22,40), these means being continuously or almost continuously movable by electrical means (13,21, 23,40) receiving electrical control quantities, these quantities being controllable by the computer (7), and in that the computer (6,7) is equipped with a program for controlling the electrical quantities making it possible to imperceptibly move the reticle (10) to bring it to the future point of impact and l 'keep it there.

2. Individual weapon (30) according to claim 1 characterized in that the optical means capturing a landscape image are constituted by a telescopic sight (31) comprising a lens (19) and an eyepiece (18), the means of constitutions of lines (14, 20, 22) constituting the lines in the image focal plane (17) of the objective (19).

3. Individual weapon (30) according to claim 2 characterized in that the means of constituting lines are composed of two styles (14) crossed, the means of movement of each style being constituted by an electric micromotor (13) receiving voltages supply controlled by the computer (6,7).

4. Individual weapon (30) according to claim 2 characterized in that the means of constituting lines consist of two needles (20) crossed, each needle (20) being the needle of a galvanometer (21) receiving a current supply controlled by the computer (7).

5. Individual weapon (30) according to claim 2 characterized in that the means of constituting lines are constituted by contrast obtained by means of a transparent medium (22) optically sensitive to a variation of electric field the means of displacement of the lines being constituted by an array of electrodes (23) acting on the electric field of the optically sensitive medium (22), the inter-electrode voltages being controlled by the computer (7).

6. Individual weapon according to claim 1 characterized in that the optical means capturing an image of the landscape consist of a video camera (40) coupled to a display screen comprising pixels, the luminance of each pixel being a function of a voltage assigned to a pixel and the means for constituting lines being constituted by pixels receiving a voltage controlled by the computer.