Weapon aiming system - Patent Review 5456157

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This invention relates to weapons, especially machine guns which are pivotally mounted and aimed manually, and is especially concerned with aiming of such weapons.

Generally, the invention is applicable to so-called "crew-served" weapons operated by one or two persons, which typically includes "light" machine guns, which fire non-explosive rounds, and "heavy" machine guns, which fire larger rounds or grenades. Hitherto, such machine guns have been aimed at the target by sighting by means of a direct-view sight on the weapon barrel, which limits the effectiveness of such weapons, especially with battlefield conditions becoming increasingly complicated.

OBJECT OF THE INVENTION

An object of the present invention is to provide an improved aiming system suitable for machine guns and like weapons.

SUMMARY OF THE INVENTION

To this end, according to the present invention, there is provided a machine gun unit comprising a machine gun mounted upon a support by means of a mounting permitting pivoting of the machine gun relative to the support in azimuth and/or elevation, and position sensing means for providing signals representing angular displacement of the machine gun relative to the support. The unit also includes an aiming system comprising sensor means for providing a video signal representing a field of view for the aiming system, display means for displaying the field of view for an operator, input means, graphics artifact generation means, and signal processing means responsive to the input means for controlling the graphics artifact generation means to combine the output of the video artifact generation means with the output of the sensor means for display by the display means. The signal processing means determines the position of the graphics artifact in the display in dependence upon the signals from the position sensors.

When using a machine gun, it is often desirable to set limits to its field-of-fire so as to avoid fratricide and/or improve effectiveness by avoiding overlap between fields of fire of other machine guns.

Accordingly, one aspect of the present invention comprises:

a gun mounted upon a support by means of a mounting permitting pivoting of the gun relative to the support means in at least one of azimuth and elevation;

position sensing means for providing position signals representing one or both of the azimuthal and elevational angular displacement of the weapon;

sensor means for providing a scene signal representing a field of view for the aiming system;

graphics artifact generation means for providing signals representing a graphics artifact comprising at least one mask delimiting an area of the field of view;

display means responsive to the sensor means and the graphics artifact generation means for displaying an image of the field of view and the graphics artifact;

user-operable input means; and

signal processing means operable in response to the input of limit signals via the input means to record specific azimuthal and/or elevational orientations of the machine gun as boundaries of said area and subsequently responsive to the position sensing means initially to control the graphics artifact generation means to display at least a part of said at least one mask when the aiming point of the gun traverses one of said boundaries and thereafter to adjust the extent of said part in dependence upon further pivoting of the gun.

The graphics means may conveniently comprise a video generator and a video memory, while the position sensing means may conveniently comprise angle encoders.

Embodiments of this aspect of the invention enable the gunner to preset a field-of-fire, namely those areas of the field of view which are not masked. In one preferred embodiment, the signal processing means stores an azimuth reading as the limit of the field-of-fire and generates the mask to overlay any part of the image having an azimuthal reading in excess of the stored azimuthal reading. Preferably, provision is made for storing right-most and left-most limits and generating overlay masks in the form of curtains for image areas to the right and to the left, respectively, of the right-most and left-most limits.

The mask may take the form of a grille or other relatively transparent graphics artifact which will allow the underlying features of the scene in the field of view to be seen.

A second aspect of the invention concerns heavy machine guns which fire grenades or the like and so require substantial superelevation of the machine gun before a round is fired. It is desirable for the required degree of superelevation of the weapon to be determined quickly, at least approximately, so as to avoid wasting several rounds.

To this end, according to a second embodiment of the invention, a machine gun unit comprises:

a machine gun mounted upon a support by means of a mounting comprising a part pivotable in azimuthal directions relative to the support, the machine gun being mounted upon said part, and pivotable in elevation relative thereto;

sensor means for providing a signal representing a field of view of the sensor means;

position sensing means for providing a position signal representing at least the elevation of the weapon;

means for providing a signal representing range to a designated target;

graphics artifact generation means for providing an artifact signal representing a cursor;

display means responsive to the sensor means and the graphics artifact generation means for displaying an image of the field of view and the cursor; and

signal processing means responsive to the range signal and stored ballistics data to compute a required degree of superelevation for the machine gun and apply a corresponding offset to the position signal, thereby offsetting the cursor downwards relative to the image of the field of view by an amount corresponding to the required superelevation.

In use, the user will pivot the weapon upwards until the cursor is again on the target and then fire the round. The angle through which the user must pivot the weapon to restore the cursor is, of course, the required degree of superelevation.

A third aspect of the invention concerns visual indication of the landing point of rounds fired by the weapon. Conventionally, such visual indication is provided by interspersing tracer rounds, which comprise magnesium or other suitable combustible material, with the live rounds fired by the weapon. The tracer rounds burn during flight and allow the user to see their trajectory and where they land. Such tracers have disadvantages, however, since they replace live rounds, reduce the machine gun barrel life because they ignite before leaving the barrel, and may temporarily blind the user, especially when night vision equipment is being used. With the object of overcoming these disadvantages, there is provided according to a third aspect of the invention, a machine gun unit comprising:

a machine gun mounted upon a support by means of a mounting permitting pivoting of the machine gun relative to the support in at least one of azimuth and elevation;

position sensing means for providing signals representing displacement of the machine gun relative to the support in at least one of azimuth and elevation; and

an aiming system comprising sensor means for providing a scene signal representing a field of view for the aiming system, display means responsive to the sensor means for displaying the field of view, input means, graphics artifact generation means, and signal processing means, the signal processing means being responsive to the position sensing means for controlling the graphics artifact generation means to combine the output of the graphics artifact generation means with the output of the sensor means for display by the display means, the signal processing means being further operable in response to a signal from the input means to compute parameters for a trajectory of a round and supply parameters to said graphics artifact generation means, the graphics artifact generation means being operable to generate therefrom a graphics artifact representing an image of a tracer round and combine it with the scene displayed by the display means.

The signal processing means may be arranged to reduce the size and/or brightness of the graphics artifacts progressively in successive frames.

Yet another aspect of the invention concerns detecting and displaying motion of potential targets and/or the source of opposing fire while the attention of the user is otherwise engaged.

Thus, according to another aspect of the invention, there is provided a machine gun unit comprising a machine gun mounted upon a support by means of a mounting permitting pivoting of the machine gun relative to the support in azimuth and/or elevation, and position sensing means for providing signals representing angular displacement of the machine gun relative to the support. The unit also includes an aiming system, comprising sensor means for providing a video signal representing a field of view for the aiming system, display means for displaying the field of view for an operator, input means, graphics artifact generation means, and signal processing means responsive to the position sensing means and the input means for controlling the graphics artifact generation means to combine the output of the video artifact generation means with the output of sensor means for display by the display means. The signal processing means comprises interframe detection means for detecting differences between pixels of a current frame of the video signal with corresponding pixels of a preceding frame of the video signal. The signal processing means records data corresponding to the differing pixels. The graphics artifact generator uses the data for generation of corresponding graphics artifacts.

In embodiments for detecting motion, the interframe difference detecting means detects both positive and negative differences in magnitude/intensity of corresponding pixels in successive frames. In embodiments for detecting sources of opposing fire, the interframe difference detecting means may detect only positive changes in magnitude/intensity indicating muzzle flashes.

Weapons embodying one or more of the foregoing aspects of the invention may be equipped with a data interface enabling them to communicate with a central command post. According to yet another aspect of the invention there is provided a weapon system comprising a plurality of weapons and a central command post, each weapon comprising:

a gun mounted upon a support means by means of a mounting permitting pivoting of the gun relative to the support means in at least one of azimuth and elevation;

position sensing means for providing position signals representing one or both of the azimuthal and elevational angular displacement of the weapon;

sensor means for providing a signal representing a field of view of the sensor means;

graphics artifact generation means for providing signals representing graphics artifacts;

display means responsive to the sensor means and the graphics artifact generation means for displaying a combined image of the field of view and the graphics artifacts;

user-operable input means;

signal processing means operable in response to the user-operable input means and position signals to control the graphics artifact generator thereby to determine the position of the graphics artifact relative to the displayed scene;

and a data interface coupled to said central command station, the data interface being arranged to convey signals between said weapon and said central command post.

Further features of the invention will become apparent from the following description of preferred embodiments, which are described by way of example only and with reference to the accompanying drawings, in which:

FIG. 1 illustrates a machine gun unit according to one embodiment of the invention;

FIG. 2 is a block schematic diagram of an aiming system of the unit of FIG. 1;

FIG. 3 illustrates the display seen by a user of the unit, showing an overlay for limiting field-of-fire;

FIG. 4 illustrates an alternative overlay for designating a field-of-fire "corridor";

FIGS. 5A, 5B and 5C illustrate operation of a second embodiment of the invention involving superelevation of the weapon;

FIG. 6 is a flowchart illustrating processing in the second embodiment;

FIG. 7 depicts video tracers generated in a further embodiment of the invention;

FIG. 8 is a flowchart for the video tracer embodiment;

FIG. 9 illustrates a fourth embodiment of the invention for detecting and indicating target motion;

FIG. 10 is a flowchart for the embodiment of FIG. 9; and

FIG. 11 illustrates coordination of the field-of-fire of several of the weapons by way of a central command post;

In FIG. 1, which is a general diagram applicable to several embodiments of the invention, a machine gun 10 is shown mounted upon a support, in the form of a tripod 12, by means of a mounting comprising a base 14 and a cradle part 16. The base 14 couples the cradle part 16 to the tripod 12 and includes a bearing permitting azimuthal rotation of the cradle part 16 relative to the tripod 12. The cradle part 16 is secured to the machine gun body 18 by a pair of pivots 20 (only one of which is shown) permitting pivoting of the machine gun 10, relative to the tripod 12, to elevate the machine gun barrel. A first position sensor 22, coupled to base 14, detects azimuthal rotation of the machine gun 10 relative to the tripod 12. A second position sensor 24, coupled to cradle part 16, detects elevational pivoting of the machine gun 10 relative to the cradle part 16.

The position sensors 22 and 24 supply azimuth and elevation signals, respectively, to a signal processing unit 26 which could, and usually would, be mounted upon the body of the machine gun 10, but is shown separate for convenience of illustration.

An image sensor 28 is mounted upon the machine gun 10 and is "bore-sighted" i.e. has its optical axis aligned with the bore axis of the machine gun. The image sensor 28 is of the CCD array kind used in portable video cameras and supplies an analogue video signal representing the field-of-view. The output of sensor 28 is coupled to the signal processing unit 26 which relays the video signal to a display device 30. The display device 30 comprises a miniature cathode ray tube (CRT) e