GB2540569A

GB2540569A - Methods and systems for determining an aim adjustment to be made when launching a projectile from a projectile launcher

Info

Publication number: GB2540569A
Application number: GB1512847.3A
Authority: GB
Inventors: Green Michael
Original assignee: Thales Holdings UK PLC
Current assignee: Thales Holdings UK PLC
Priority date: 2015-07-21
Filing date: 2015-07-21
Publication date: 2017-01-25
Anticipated expiration: 2035-07-21
Also published as: GB2540569B; GB201804581D0; GB2559058B; GB2559058A; GB201512847D0

Abstract

A method of adjusting aim when firing projectiles towards a target from a projectile launcher comprises: receiving, at a receiver, light reflected by a retro-reflective projectile, the reflected light comprising a portion of a laser information field (LIF) projected across a region of space in which the target is located; determining, based on the received portion of light, a position of the retro-reflective projectile with respect to the LIF; and determining an adjustment of the aim of the projectile launcher based on the determined position of the projectile with respect to the LIF. The required aim adjustment may be presented on a visual display. It is also disclosed that the system may be used with an ammunition feed, in which one or more projectiles comprise a retro-reflective element. The system thus allows a gunner to correct the aim of his fire without the use of tracer rounds, overcoming several disadvantages of such rounds.

Description

Methods and systems for determining an aim adjustment to be made when launching a projectile from a projectile launcher

FIELD

Embodiments described herein relate to methods and systems for determining an aim adjustment to be made when launching a projectile from a projectile launcher.

BACKGROUND

Gunners typically use fall of shot (i.e. determining where a projectile lands relative to a target) in order to adjust the aim for subsequent shots. The fall of shot may be difficult to see in certain terrains and impossible when engaging air targets. To address this, guns may use tracer ammunition, which allows the aimer to visualize the flight path of bullets. Typically, the tracer rounds are incorporated as every fifth round in an ammunition feed. Each tracer round has a pyrotechnic charge in its base which burns when the projectile is fired giving a trace which the gunner can use to correct the aim-point.

The use of tracer rounds presents a number of problems. First, the tracer rounds are visible to enemy troops, giving away the gunner’s position. Secondly, any correction in aim is based on the gunner’s interpretation of the flight path and is, therefore, likely to be inaccurate and slow. Thirdly, the weight of the tracer load varies as its charge burns, causing it to follow a different trajectory from the other projectiles.

SUMMARY

According to a first embodiment, there is provided a method of determining an aim adjustment to be made when launching a projectile from a projectile launcher, the method comprising: receiving, at a receiver, light reflected by a retro-reflective projectile launched from the projectile launcher towards a target, the reflected light comprising a portion of a laser information field projected across a region of space in which the target is located; determining, based on the received portion of light, a position of the retro-reflective projectile with respect to the laser information field; and determining, based on the position of the retro-reflective projectile with respect to the laser information field, an aim adjustment for the projectile launcher.

The retro-reflective projectile may comprise a retro-reflective element for reflecting light in the laser information field. The retro-reflective element may be positioned to be at the rear of the projectile when the projectile is in flight.

In some embodiments, the method further comprises displaying the aim adjustment on a visual display.

In some embodiments, the method further comprises adjusting the aim of the projectile launcher based on the determined aim adjustment.

According to a second embodiment, there is provided a system for determining an aim adjustment to be made when launching a projectile from a projectile launcher, the system comprising: a light sensor for receiving light reflected by a retro-reflective projectile launched from the projectile launcher towards a target, the reflected light comprising a portion of a laser information field projected across a region of space in which the target is located; a position calculator for determining, based on the received light, a position of the retro-reflective projectile with respect to the laser information field; and an aim correction calculator for determining, based on the position of the retro-reflective projectile with respect to the laser information field, an aim adjustment for the projectile launcher.

The system may further comprise a laser for projecting the laser information field into said region of space.

In some embodiments, the laser is operable to generate the laser information field by scanning a pulsed laser beam across said region of space, the intervals between successive laser pulses being varied as the laser scans across the region of space; wherein the position of the retro-reflective projectile within the laser information field is determined based on the time interval between receiving successive laser pulses at the light sensor.

According to a third embodiment, there is provided a projectile launcher comprising a system according to the second embodiment. The projectile launcher may comprise an aiming device. The light sensor may be bore-sighted to the aiming device.

According to a fourth embodiment, there is provided a projectile for launching from a projectile launcher, the projectile comprising a retro-reflective element for reflecting laser light in a laser information field towards a receiver. The retro-reflective element may be positioned to be at the rear of the projectile when the projectile is in flight. The retro-reflective element may be a corner cube.

In some embodiments, the projectile launcher is a gun or missile launcher.

According to a fifth embodiment, there is provided an ammunition feed comprising a plurality of rounds of ammunition and one or more projectiles according to the fourth embodiment. The one or more projectiles may have substantially the same mass as the rounds. The one or more projectiles may have the same weight distribution as the rounds.

In some embodiments, the ammunition feed comprises two or more of the projectiles, the projectiles being dispersed at intervals among the rounds. The round in the ammunition feed may be bullets.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 shows a system for determining an aim adjustment to be made when launching a projectile towards a target, according to an embodiment;

Figure 2 shows components of the receiver of Figure 1 in more detail;

Figure 3 shows a flow-chart of steps for determining an aim adjustment to be made when launching a projectile towards a target, according to an embodiment; and

Figure 4 shows an example of a projectile having a retro-reflective element according to an embodiment.

DETAILED DESCRIPTION

Embodiments described herein provide a retro-reflective projectile which when fired into a coded laser information field can provide accurate electronically coded position information of the projectile’s trajectory with respect to a target. The information can be used by a gunner for aim-point correction. In one embodiment, the information can be used as an offset in the control of a remotely operated gun turret.

Figure 1 shows a system for determining an aim adjustment to be made when launching a projectile towards a target, according to an embodiment. The system comprises a laser beam transmitter 101, which is used to project a coded laser information field 103 onto a region of space in which the target 105 is located. The laser information field 103 may be similar to that used in a conventional laser beam riding (LBR) missile guidance system. For example, the laser information field 103 may be generated by operating the laser beam transmitter 101 in a pulsed mode and scanning the beam in the horizontal and vertical directions, perpendicular to the beam’s direction of propagation. As the beam is scanned, the intervals between successive laser pulses may be varied across the height and width of the laser information field 103. In this way, the laser information field can be seen to comprise a grid or array of points, in which each point has an associated laser pulse interval. A projectile launcher 107 (in this case, a gun) is used to fire rounds of ammunition (e.g. bullets) at the target 105. Retro-reflective projectiles are included at intervals in the ammunition feed. When a retro-reflective projectile is fired, light from a portion 109 of the laser information field that intercepts the retro-reflective projectile is reflected back towards the laser beam transmitter 101. A receiver 111, located close to the laser beam transmitter 101, receives the reflected laser signal 113 from the retro-reflective projectile.

Figure 2 shows the components of the receiver 111 in more detail. The receiver includes a light sensor 201 for detecting the reflected light signal and a position calculator 203. The position calculator 203 includes processing electronics that determine, based on the characteristics of the received signal, the position of the projectile within the laser information field 103. For example, depending on the pulse-to-pulse interval in the reflected laser signal, the position calculator is able to determine the position of the retro-reflective projectile with respect to the centre of the laser information field.

The receiver also includes an aim-point correction calculator 205. The aim-point correction calculator 205 receives as input the position of the retro-reflective projectile within the laser information field and determines an offset between the retro-reflective projectile’s position and the target. The offset is then used to indicate the correction in aim required in order for subsequent rounds to hit the target.

In the present embodiment, the receiver also comprises a display 207 for presenting the correction to the gun operator. The display 207 may be one of any number of known optical displays including, for example, an LCD or LED display. The display is used to indicate the extent to which the gun needs to be moved upwards or downwards, and / or left or right in order to remain on target.

In some embodiments, rather than presenting the correction to an operator on a display, the offset as determined by the aim-point correction calculator may be used to provide an aim-point correction within the control loop of a powered gun turret.

The steps discussed above are summarised in the flow chart of Figure 3. In step S301, the retro-reflective projectile is launched towards the target. In step S302, a portion of the laser information field is reflected by the projectile back towards the receiver. In step S303, the receiver determines the location of the projectile in the laser information field, based on the information encoded in the reflected light signal. The position is then used to determine the spatial offset between the retro-reflective projectile and the target (step S304). In step S305, the offset is used to determine an aim-correction for launching subsequent rounds of ammunition.

Figure 4 shows a schematic of a retro-reflective projectile 401 according to an embodiment. The retro-reflective projectile includes a retro-reflective element 403 in its base for reflecting a large part of the laser signal back towards the transmitter (depending on the geometry of the projectile, it is conceivable that the retro-reflective element may be positioned at other points on the projectile, besides the base).

The term “retro-reflective element” as used herein will be understood to refer to a device or surface that reflects light with a minimum of scattering. A ray of light incident on the retro-reflector will be reflected back along a path that is substantially parallel with that of the incident ray. Thus, by providing the projectile with a retro-reflective element, it is possible to ensure that a substantial part of the incident laser light will be reflected back along the same path, in turn ensuring that the detector can receive the reflected light signal with sufficient signal to noise ratio.

In the embodiment shown in Figure 4, the reflective element comprises a corner cube, but other retro-reflective devices may also be used. Such retro-reflective devices include, for example, a lens/mirror combination, a combination of refractive optics with a reflective element positioned at a focal plane, or a transparent sphere such as might be used in a “cat’s eye”.

Unlike conventional tracer rounds, the retro-reflective projectile will not be visible to enemy troops. Moreover, the retro-reflective projectile can be engineered to have the same mass and centre of gravity as other rounds in the ammunition feed (which may be, for example, conventional bullets, etc.) The position of each retro-reflective projectile can be accurately tracked to give easily understood aim-point correction commands to the gunner. The coordinates of the retro-reflective projectile in the laser information field may be encoded in an electronic format suitable for incorporation into the control loop of a remotely operated gun turret.

In some embodiments, the laser beam transmitter and receiver may be included together in a single unit. The receiver may be bore-sighted to a suitable aiming device, such as a rifle scope or TV camera, for example.

Embodiments may be used by sniper teams. A spotter may point the laser transmitter/receiver, bore-sighted to their spotting scope, at an intended target. A retro-reflective projectile may be fired as an initial shot, and its location in the laser information field determined and used to compute a correction in the sniper’s aim for the next shot.

While certain embodiments have been described, these embodiments have been presented by way of example only and are not intended to limit the scope of the invention. Indeed, the novel methods, devices and systems described herein may be embodied in a variety of forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the scope of the invention. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope of the invention.

Claims

1. A method of determining an aim adjustment to be made when launching a projectile from a projectile launcher, the method comprising: receiving, at a receiver, light reflected by a retro-reflective projectile launched from the projectile launcher towards a target, the reflected light comprising a portion of a laser information field projected across a region of space in which the target is located; determining, based on the received portion of light, a position of the retro-reflective projectile with respect to the laser information field; and determining, based on the position of the retro-reflective projectile with respect to the laser information field, an aim adjustment for the projectile launcher.

2. A method according to claim 1, wherein the retro-reflective projectile comprises a retro-reflective element for reflecting light in the laser information field, the retro-reflective element being positioned to be at the rear of the projectile when the projectile is in flight.

3. A method according to claim 1 or 2, further comprising displaying the aim adjustment on a visual display.

4. A method according to any one of the preceding claims, further comprising adjusting the aim of the projectile launcher based on the determined aim adjustment.

5. A system for determining an aim adjustment to be made when launching a projectile from a projectile launcher, the system comprising: a light sensor for receiving light reflected by a retro-reflective projectile launched from the projectile launcher towards a target, the reflected light comprising a portion of a laser information field projected across a region of space in which the target is located; a position calculator for determining, based on the received light, a position of the retro-reflective projectile with respect to the laser information field; and an aim correction calculator for determining, based on the position of the retro-reflective projectile with respect to the laser information field, an aim adjustment for the projectile launcher.

6. A system according to claim 5, further comprising a laser for projecting the laser information field into said region of space.

7. A system according to claim 5 or 6, wherein the laser is operable to generate the laser information field by scanning a pulsed laser beam across said region of space, the intervals between successive laser pulses being varied as the laser scans across the region of space; wherein the position of the retro-reflective projectile within the laser information field is determined based on the time interval between receiving successive laser pulses at the light sensor.

8. A projectile launcher comprising a system according to any one of claims 5 to 7.

9. A projectile launcher according to claim 8, wherein the projectile launcher comprises an aiming device and the light sensor is bore-sighted to the aiming device.

10. A projectile for launching from a projectile launcher, the projectile comprising a retro-reflective element for reflecting laser light in a laser information field towards a receiver.

11. A projectile according to claim 10, wherein the retro-reflective element is a corner cube.

12. A projectile according to claim 10 or 11, wherein the projectile launcher is a gun or missile launcher.

13. An ammunition feed comprising a plurality of rounds of ammunition and one or more projectiles according to any one of claims 10 to 12.

14. An ammunition feed according to claim 13, wherein the one or more projectiles have substantially the same mass as the rounds.

15. An ammunition feed according to claim 13 or 14, wherein the one or more projectiles have the same weight distribution as the rounds.

16. An ammunition feed according to any one of claims 13 to 15, comprising two or more of the projectiles, the projectiles being dispersed at intervals among the rounds.

17. An ammunition feed according to any one of claims 13 to 16, wherein the rounds are bullets.