EP4015980A1

EP4015980A1 - Trajectory adjustments

Info

Publication number: EP4015980A1
Application number: EP20275183.0A
Authority: EP
Inventors: designation of the inventor has not yet been filed The
Original assignee: BAE Systems PLC
Current assignee: BAE Systems PLC
Priority date: 2020-12-16
Filing date: 2020-12-16
Publication date: 2022-06-22

Abstract

A method for regulating a trajectory of a projectile (100) comprises adjusting the position of a mass (105) within a cavity (103) defined by a jacket (101) of the projectile, whereby to modify a centre of gravity of the projectile.

Description

TECHNICAL FIELD

Aspects relate, in general, to methods and system for adjusting or regulating trajectories, and more particularly, although not exclusively, to regulating trajectories of projectiles.

BACKGROUND

A projectile, such as a bullet, can be propelled from the barrel of a gun using propellant in the form of, e.g., a chemical explosive. The projectile can reach speeds in excess of 1000mph. Once ejected from the barrel of the gun, the projectile follows a ballistic trajectory dictated by various factors which act on the projectile. For example, gravity will exert a downward acceleration on the projectile, air resistance will decelerate the projectile, and wind, if present will cause the projectile deviate from its intended trajectory. Accordingly, during flight, the trajectory of a projectile will be affected, even in the case that it is spin stabilised, and it is typically necessary to factor in compensation in order to offset the effects of external forces in order to ensure that a projectile follows a desired trajectory.

SUMMARY

According to a first aspect, there is provided a method for regulating a trajectory of a projectile, the method comprising adjusting the position of a mass within a cavity defined by a jacket of the projectile, whereby to modify a centre of gravity of the projectile. The position of the mass can be adjusted in an axial direction of the projectile. The position can be adjusted by actuating a gear arrangement of the projectile. In an example, the position of the mass can be adjusted in a radial direction of the projectile. The position of the mass can be adjusted in a radial direction by translating the mass parallel to a radial axis of the projectile. The position of the mass can be adjusted in a radial direction by rotating the mass around a pivot point.
According to a second aspect, there is provided a projectile, comprising a jacket defining an internal cavity, and a trajectory modification structure provided within the cavity configured to adjust the position of a mass, whereby to modify a centre of gravity of the projectile. The trajectory modification structure can comprise a gear arrangement configured to adjust the position of the mass in an axial direction. Means to adjust the position of the mass in a radial direction can be provided. For example, a leadscrew mechanism can be used to translate and/or rotate the mass about a pivot point in a radial direction.
In an implementation of the second aspect, the gear arrangement can comprise a leadscrew mechanism configured to enable adjustment of the position of the mass in the axial direction. In an example, an electromagnetic actuator can be configured to adjust the position of the mass within the internal cavity.
According to a third aspect, there is provided a non-transitory machine-readable storage medium encoded with instructions for regulating a trajectory of a projectile, the instructions executable by a processor of a machine whereby to cause the machine to adjust the position of a mass within a cavity defined by a jacket of the projectile, whereby to modify a centre of gravity of the projectile. The non-transitory machine-readable storage medium can be further encoded with instructions executable by a processor of a machine whereby to cause the machine to adjust the position of the mass in an axial direction of the projectile; actuate a gear arrangement of the projectile; adjust the position of the mass in a radial direction of the projectile.

BRIEF DESCRIPTION OF THE DRAWINGS

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

Figures 1 to 4 are schematic representations of a projectile according to an example; and
Figure 5 is a schematic representation of a controller according to an example.

DESCRIPTION

Example embodiments are described below in sufficient detail to enable those of ordinary skill in the art to embody and implement the systems and processes herein described. It is important to understand that embodiments can be provided in many alternate forms and should not be construed as limited to the examples set forth herein.
Accordingly, while embodiments can be modified in various ways and take on various alternative forms, specific embodiments thereof are shown in the drawings and described in detail below as examples. There is no intent to limit to the particular forms disclosed. On the contrary, all modifications, equivalents, and alternatives falling within the scope of the appended claims should be included. Elements of the example embodiments are consistently denoted by the same reference numerals throughout the drawings and detailed description where appropriate.
The terminology used herein to describe embodiments is not intended to limit the scope. The articles "a," "an," and "the" are singular in that they have a single referent, however the use of the singular form in the present document should not preclude the presence of more than one referent. In other words, elements referred to in the singular can number one or more, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes," and/or "including," when used herein, specify the presence of stated features, items, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, items, steps, operations, elements, components, and/or groups thereof.
Unless otherwise defined, all terms (including technical and scientific terms) used herein are to be interpreted as is customary in the art. It will be further understood that terms in common usage should also be interpreted as is customary in the relevant art and not in an idealized or overly formal sense unless expressly so defined herein.
Self-guided projectiles can be used with laser target designators that illuminate a target. In combination with optical sensors, guidance electronics and control surfaces (such as projectile fins etc., that can be actively manoeuvred during projectile flight) projectiles can be guided to their targets. Generally speaking, such guidance systems are used on larger ballistic projectiles because the size, weight, volume and cost constraints make them impractical for use with small arms projectiles (e.g., of the order of 50 calibre).
In order to provide some degree of control over the path of smaller projectiles, drag inducing control surfaces can be used to alter the trajectory of the projectile in flight. However, such control surfaces are difficult to implement in projectiles that are spin-stabilised (e.g., by way of rifling on the inner surface of the barrel from which the projectile is propelled in order to provide aerodynamic stability) and also introduce performance penalties by, e.g., reducing projectile velocity and range. It is therefore generally the case that relatively small arms projectiles are not actively guided, since the mechanisms to implement such guidance is either cost prohibitive, or incompatible with the intended use. For example, an incendiary projectile, such as a tracer round for example, can include a pyrotechnic agent that, once ignited (e.g., upon propulsion of the round), burns at high intensity. Typically, combustion of the pyrotechnic agent is so intense that the tracer can be damaged as it traverses its path. Accordingly, any external structural features of the projectile that are geared to enable its trajectory to be modified, such as those noted above, may be at risk in such incendiary devices.
According to an example, there is provided a method for regulating a trajectory of a projectile. That is, the method enables the trajectory of a projectile to be modified. The modification may be effected as the projectile is in flight, or prior to its ejection from a firing system, such as a gun for example. According to an example, the method comprises adjusting the position of a mass within a cavity defined by a jacket of the projectile, whereby to modify a centre of gravity of the projectile. Such trajectory modification can provide a mechanism to purposefully enable programmatic alteration of trajectory of a projectile in-flight to, e.g., fire around/over obstacles.
Figure 1 is a schematic representation of a projectile according to an example. The projectile 100 may form part of a larger cartridge (not shown) comprising a housing for a propellant that can be ignited using a primer in order to propel the projectile 100. Projectile 100 comprises a jacket 101. The jacket 109, forming an outer casing for the projectile 100, defines an inner compartment or cavity 103. In an example, the interior of the projectile may comprise a filling material, such as lead for example, in which case the cavity 103 may be provided within the filling material that is encased by the jacket 101. A mass 105 is provided within the cavity. In an example, the mass 105 is so positioned as to be linearly translatable along an axis A of the projectile. Axis A can be the central axis of the projectile. Accordingly, translation of the mass 105 along the axis A affects the centre of mass of the projectile in an axial direction. Translation of the mass 105 along axis A can be controlled using a controller 107, as will be described in more detail below.
Figure 2 is a schematic representation of a projectile according to an example. In the example of figure 2 a gear arrangement is provided. The gear arrangement can comprise a linear actuator. For example, the gear arrangement can comprise a member 201 such as a leadscrew (translation screw), screw thread or worm. The gear arrangement enables the position of the mass 105 to be adjusted along the axis A by way of actuation of the gear arrangement. In an example, a bore through the centre of the mass 105 can be so profiled as to engage with the thread of the member 201. That is, the bore can comprise the male (or female) counterpart of the female (or male) thread of the member 201 of the gear arrangement. Thus, the mass 105 effectively forms the nut to the gear arrangement's screw.
In order to translate rotational movement of the member 201 to a linear (translational) movement of the mass 105, mass 105 may be rotationally constrained. That is, mass 105 can be constrained to one degree of freedom so as to move only back and forth along axis A whilst being prevented from rotating around axis A. In this way, with an inner profile of the bore of the mass comprising a thread that meshes with the profile of the member 201, the mass is forced along axis A when the worm 201 is rotated. Mass 105 may be rotationally constrained by way of a protrusion 205 from the mass that sits within a channel 207 for example. Although only one such arrangement is depicted in figure 2 for the sake of clarity, it will be appreciated that multiple such arrangements may be provided in order to rotationally constrain mass 105.
The extremities of the member 201 can dictate the maximum travel of the mass 105 in either direction along the axis A. Alternatively, stops (not shown) may be provided in order to limit movement of the mass 105 in the axial direction. Further alternatively, controller 107 can be used to programmatically limit movement of the mass 105 in the axial direction such that translation of the mass 105, by way of actuation of the gear arrangement, falls within a predetermined range. In an example, member 201 can be rotated using a motor 203. An alternative would be to enable mass 105 to rotate around an otherwise stationary member 201.
Controller 107 can be used to control the gear arrangement. For example, controller 107 can be used to actuate a motor 203 that can be used to rotate the member 201. As the mass 105 is meshed with the member 201, rotation of the member causes it to rotate around axis A, thereby causing translation of the mass 105 in an axial direction A. Member 201 may be rotated in either direction in order to cause the mass 105 to be translated back and forth along the axis A as desired. Controller 107 can be programmed with a set of instructions that map to desired translations/positions of the mass 105. For example, the controller 107 can be programmed to cause the mass 105, by way of the gear arrangement, to move along axis A as the projectile is in flight for example by a predetermined amount at a predetermined time, thereby altering the centre of mass of the projectile at that time to a specified degree, thus triggering a corresponding change in the trajectory of the projectile. Multiple such adjustments can be made using controller 107 in order to generate any number of modifications to the trajectory of the projectile in flight. In an example, the controller 107 can be programmed to position the mass 105 in a position along axis A that will affect its trajectory in a known manner before the projectile is fired. Subsequent modifications may be made once the projectile is airborne. Controller 107 and motor 203 may be powered by a power source 209, which may be any suitable power source such as a battery/coin cell battery for example.
According to an example, the position of the mass 105 can initially be set, such as at the point of manufacture, to a position in which it is restrained by, e.g., a magnet so as to prevent unintentional movement thereof. The force exerted by the magnet may be overcome by the action of the motor 203 on the member 201 in order to release the mass 105 from this initial position.
Figure 3 is a schematic representation of a projectile according to an example. Figure 3 shows the projectile viewed from its tip 109 (i.e., along axis A). Mass 105 is depicted on member 201. A protrusion 205 is depicted in a channel 207, as described above with reference to figure 2.
According to an example, a radial movement of the mass can be provided. That is, mass 105 may be moved parallel to axis B (figure 1). With reference to figure 2, motor 203 can be used to drive the lead screw 201 to move the mass 105 along the axis A. In an example, motor 203, lead screw 201 and components 205/207 can form an arrangement that may be translated in a radial direction.
Figure 4 is a schematic representation of a projectile according to an example. In the example of figure 4, motor 203, lead screw 201, mass 105, protrusion 205 and channel 207 for an arrangement 401. The arrangement 401 is moveable within the cavity defined by the housing of the projectile. For example, arrangement 401 can be translated parallel to axis B and/or rotated about point C using a motor 403 that can be used to actuate another lead screw structure 402 that is configured to move the arrangement 401 in a radial direction (either by translating the entire arrangement 401, which may be provided on bearings in a set of channels for example, in a radial direction, or by rotating it about pivot point C. The effect of movement the mass 105 about C will be more pronounced the further mass is away from C as the relative distance of the mass 105 from the central axis A is greater the further away from point C it is. Accordingly, in order to effect a trajectory change of the projectile by way of radial adjustment of the mass when the axial position of the mass is close to C may require the time that the mass is in an adjusted radial position to vary according to its position along the axis A. For example, it will need to spend relatively longer in a radially displaced position to effect a given change of trajectory when closer to point C than it would when further from point C.
In another example, arrangement 401 may be moved by way of electromagnetic actuation. For example, a MEMS magnetic actuator may be used in place of motor 403 and lead screw 402 to move the arrangement 401. Controller 107 can be used to control the system used for adjusting the radial position of the mass.
Radial movement of the mass 105 provides an additional degree of movement for adjusting the centre of mass of the projectile in an axial direction. Accordingly, it is possible to adjust the direction of flight of the projectile in three dimensions by moving the mass along axes A and B as desired.
Examples in the present disclosure can be provided as methods, systems or machine-readable instructions, such as any combination of software, hardware, firmware or the like. Such machine-readable instructions may be included on a computer readable storage medium (including but not limited to disc storage, CD-ROM, optical storage, etc.) having computer readable program codes therein or thereon.
The present disclosure is described with reference to flow charts and/or block diagrams of the method, devices and systems according to examples of the present disclosure. Although the flow diagrams described above show a specific order of execution, the order of execution may differ from that which is depicted. Blocks described in relation to one flow chart may be combined with those of another flow chart. In some examples, some blocks of the flow diagrams may not be necessary and/or additional blocks may be added. It shall be understood that each flow and/or block in the flow charts and/or block diagrams, as well as combinations of the flows and/or diagrams in the flow charts and/or block diagrams can be realized by machine readable instructions.
The machine-readable instructions may, for example, be executed by a general-purpose computer, a special purpose computer, an embedded processor or processors of other programmable data processing devices to realize the functions described in the description and diagrams. In particular, a processor or processing apparatus may execute the machine-readable instructions. Thus, modules of apparatus may be implemented by a processor executing machine readable instructions stored in a memory, or a processor operating in accordance with instructions embedded in logic circuitry. The term 'processor' is to be interpreted broadly to include a CPU, processing unit, ASIC, logic unit, or programmable gate set etc. The methods and modules may all be performed by a single processor or divided amongst several processors.
Such machine-readable instructions may also be stored in a computer readable storage that can guide the computer or other programmable data processing devices to operate in a specific mode. For example, the instructions may be provided on a non-transitory computer readable storage medium encoded with instructions, executable by a processor.
Such machine-readable instructions may also be loaded onto a computer or other programmable data processing devices, so that the computer or other programmable data processing devices perform a series of operations to produce computer-implemented processing, thus the instructions executed on the computer or other programmable devices provide a operation for realizing functions specified by flow(s) in the flow charts and/or block(s) in the block diagrams.
Figure 5 is schematic representation of a controller according to an example. Controller 107 comprises a processor 501 and a memory 503 storing instructions 505. In an example, controller 107 can be provided as part of a projectile, such as a projectile described with reference to figures 1 to 4 for example. The instructions 505 are executable by the processor 501.
The memory 503 can store data representing a set of positions for a mass 105 at predetermined times and/or projectile positions. That is, the memory 503 can store data 506 representing a set of positions for the mass 105 that cause the projectile to follow a desired trajectory. Accordingly, the position of the mass can be moved in accordance with the data representing the set of positions in order to alter the trajectory of the projectile. This may be performed at certain times relative to, e.g., a selected point in time (such as the time the projectile was fired for example) and/or at certain positions of the projectile, which may be determine using, e.g., GPS positioning. Controller 107 may therefore include a clock 507 that can be used to trigger a change in the position of the mass according to the data 506 at predetermined times. As such, data 506 can comprise a position for the mass with a timestamp representing the time, measured using clock 507, at which the mass should be moved to implement the desired change in trajectory.
The instructions 505 can comprise instructions to adjust the position of a mass within a cavity defined by a jacket of the projectile, whereby to modify a centre of gravity of the projectile; adjust the position of the mass in an axial direction of the projectile; actuate a gear arrangement of the projectile; adjust the position of the mass in a radial direction of the projectile.
Further, the teachings herein may be implemented in the form of a computer software product, the computer software product being stored in a storage medium and comprising a plurality of instructions for making a computer device implement the methods recited in the examples of the present disclosure.

Claims

A method for regulating a trajectory of a projectile, the method comprising:
adjusting the position of a mass within a cavity defined by a jacket of the projectile, whereby to modify a centre of gravity of the projectile.
The method as claimed in claim 1, further comprising:
adjusting the position of the mass in an axial direction of the projectile.
The method as claimed in claim 2, wherein adjusting the position comprises actuating a gear arrangement of the projectile.
The method as claimed in claim 2 or 3, further comprising:
adjusting the position of the mass in a radial direction of the projectile.
The method as claimed in claim 4, wherein adjusting the position of the mass in a radial direction comprises translating the mass parallel to a radial axis of the projectile.
The method as claimed in claim 4 or 5, wherein adjusting the position of the mass in a radial direction comprises rotating the mass around a pivot point.
A projectile, comprising:
a jacket defining an internal cavity; and

a trajectory modification structure provided within the cavity configured to adjust the position of a mass, whereby to modify a centre of gravity of the projectile.
The projectile as claimed in claim 7, wherein the trajectory modification structure comprises:
a gear arrangement configured to adjust the position of the mass in an axial direction.
The projectile as claimed in claim 7 or 8, further comprising means to adjust the position of the mass in a radial direction.
The projectile as claimed in claim 8, wherein the gear arrangement comprises a leadscrew mechanism configured to enable adjustment of the position of the mass in the axial direction.
The projectile as claimed in any of claims 7 to 10, further comprising an electromagnetic actuator configured to adjust the position of the mass within the internal cavity.
A non-transitory machine-readable storage medium encoded with instructions for regulating a trajectory of a projectile, the instructions executable by a processor of a machine whereby to cause the machine to:
adjust the position of a mass within a cavity defined by a jacket of the projectile, whereby to modify a centre of gravity of the projectile.
The non-transitory machine-readable storage medium as claimed in claim 12, further encoded with instructions executable by a processor of a machine whereby to cause the machine to:
adjust the position of the mass in an axial direction of the projectile.
The non-transitory machine-readable storage medium as claimed in claim 12 or 13, further encoded with instructions executable by a processor of a machine whereby to cause the machine to:
actuate a gear arrangement of the projectile.
The non-transitory machine-readable storage medium as claimed in any of claims 12 to 14, further encoded with instructions executable by a processor of a machine whereby to cause the machine to:
adjust the position of the mass in a radial direction of the projectile.