FIELD
[0001] The present invention relates generally to a fuze system, in particular to a fuze
system for a munition. A related munition and method are also provided.
BACKGROUND
[0002] Munitions are provided in a number of different forms, for a number of different
applications. Typically, a particular munition will be used for a particular application
or intention. For the purposes of this patent application, munitions are taken to
include but are not limited to artillery shells and charges, missiles, rockets, and
mortar rounds.
[0003] Grazing impact occurs when there is a small relative angle between the direction
of travel of the munition and the local surface of the target. Grazing impacts may
occur in munitions that follow ballistic trajectories and also in direct-fire projectiles.
[0004] Conventional munition fuze systems employ a variety of mechanisms arranged to sense
accelerations in the direction of travel of the munition (which may be known as "the
longitudinal axis of the munition", or "an axial sense of the munition"). The sensitivity
of such mechanisms must be sufficiently low to allow the munition to travel through
non-target obstacles, such as rain, hail, and foliage, without triggering the explosive
payload. As the acceleration magnitude in the longitudinal axis of the munition can
be relatively low during grazing impacts, it is possible that conventional fuze systems
may not be sufficiently sensitive to trigger the fuze. As a result, it is possible
for a grazing impact to occur without triggering the payload (e.g., an explosive or
non-explosive payload).
[0005] The munition may remain substantially intact and continue to travel, possibly with
a change in trajectory depending on the nature of the impact. This can result in the
projectile either exploding at a location that was not the intended target, or indeed
not exploding at all if the forward speed has reduced such that the mechanism cannot
function on subsequent impact. It will be appreciated that both scenarios can result
in hazardous outcomes, such as collateral damage and unexploded ordnance (UXO) hazards.
This is highly undesirable.
[0006] It is one aim of the present invention, amongst others, to provide an improved fuze
system, munition and/or method, and/or address one or more of the problems discussed
above, or discussed elsewhere, or to at least provide an alternative fuze system,
munition and/or method
SUMMARY
[0007] According to a first aspect of the present invention, there is provided a fuze system
for a munition, the fuze system comprising an impact sensor arrangement arranged to
sense a component of acceleration in an axis away from a munition travel direction
in which the munition is configured to travel, the impact sensor arrangement configured
to provide a first output based on the sensing of the component of acceleration in
the axis away from the munition travel direction.
[0008] In one example, the axis away from the munition travel direction is an axis away
from (e.g., in a different direction to) the longitudinal axis of the munition. In
one example, the munition travel direction is the direction in which the munition
is configured to travel, e.g., when fired or during its trajectory.
[0009] In one example, the component of acceleration in an axis away from the munition travel
direction is a component of acceleration in an axis transverse to the munition travel
direction.
[0010] In one example, the fuze system is configured to trigger an explosive charge.
[0011] In one example, the fuze system is configured to, in response to the first output
of the impact sensor arrangement being greater than or equal to a first threshold
value, trigger the explosive charge.
[0012] In one example, the impact sensor arrangement is arranged to sense a component of
acceleration in the axis of the munition travel direction, and the impact sensor arrangement
is configured to provide a second output based on the sensing of the component of
acceleration in the munition travel direction, wherein the fuze system is configured
to: trigger the explosive charge in response to the second output being greater than
or equal to a second threshold value.
[0013] In one example, the impact sensor arrangement is arranged to sense a component of
acceleration in the munition travel direction, and the impact sensor arrangement is
configured to provide a second output based on the sensing of the component of acceleration
in the munition travel direction, wherein the fuze system is configured to: trigger
the explosive charge in response to the second output being less than a second threshold
value.
[0014] In one example, the fuze system is configured not to trigger the explosive charge
in response to the first output being less than the first threshold value and the
second output being less than the second threshold value.
[0015] In one example, the impact sensor arrangement comprises two orthogonally oriented
sensors, or two sensing components, each arranged to sense a component of acceleration
in an axis away from the munition travel direction.
[0016] In one example, the impact sensor arrangement comprises more than two sensors each
arranged to sense a component of acceleration in an axis away from the munition travel
direction.
[0017] In one example, the fuze system is configured to detect peaks or frequency of the
output of the impact sensor arrangement.
[0018] In one example, the impact sensor arrangement comprises one or more accelerometers,
capacitive accelerometers, piezoresistive accelerometers, piezoelectric sensors, magnetostrictive
sensors, electromagnetic sensors, electromechanical switches, strain gauges and/or
optical interference sensors.
[0019] According to a second aspect of the present invention, there is provided a munition
comprising the fuze system according to the first aspect of the present invention.
[0020] The munition of the second aspect of the present invention may comprise any or all
of the features of the fuze system of the first aspect of the present invention, as
desired or as appropriate.
[0021] In one example, the munition is a projectile, optionally an unpropelled projectile.
[0022] In one example, the projectile comprises an artillery munition, a mortar munition,
or a tank munition.
[0023] According to a third aspect of the present invention, there is provided a method
of using a fuze system for a munition, the method comprising: arranging an impact
sensor arrangement to sense a component of acceleration in an axis away from a munition
travel direction in which the munition is configured to travel; and providing a first
output from the impact sensor arrangement based on the sensing of the component of
acceleration in the axis away from the munition travel direction.
[0024] In one example, the axis away from the munition travel direction is an axis away
from (e.g., in a different direction to) the longitudinal axis of the munition. In
one example, the munition travel direction is the direction in which the munition
is configured to travel, e.g., when fired or during its trajectory.
BRIEF DESCRIPTION OF THE FIGURES
[0025] Embodiments of the invention will now be described by way of example only with reference
to the figures, in which:
Figure 1 shows a munition and fuze system according to the prior art;
Figure 2 shows a munition and fuze system according to the present invention; and
Figure 3 shows a cross section of an example of the munition and fuze system of Figure
2;
Figure 4 shows a cross section of an example of the munition and fuze system of Figure
2;
Figure 5 shows a schematic of a munition; and
Figure 6 shows general methodology principles.
DETAILED DESCRIPTION
[0026] In overview, a fuze system, munition and method is described which overcomes problems
faced when a munition is subject to grazing impact, which may otherwise be referred
to as a "low angle impact". As discussed above, conventional fuze systems are sensitive
only to a component of acceleration, or force, in the axis of the munition travel
direction. During a grazing impact, the component of acceleration in the axis of the
munition travel direction may be low, and thus the conventional fuze system may not
be sufficiently sensitive to trigger the fuze as a result of the grazing impact, and/or
may have a minimum sensitivity dictated by the need to prevent detonation prior to
the munition arriving at the intended target, which prevents triggering of the fuze
due to a grazing impact. The present fuze system, munition and method overcomes this
problem, and also provides a number of advantages over conventional fuze systems,
munitions and methods. In particular, the present fuze system comprises an impact
sensor arrangement arranged to sense a component of acceleration in an axis away from
a munition travel direction (i.e., sense a component of acceleration in an axis away
from the direction in which the munition is configured to travel when fired). This
contrasts with conventional fuze systems, which sense acceleration in the axis of
the munition travel direction. By the present fuze system, grazing impacts can be
detected as the fuze system is sensitive to acceleration in axis away from the munition
travel direction, which is indicative of a grazing impact. It will be appreciated
that acceleration referred to in the specification herein may be a deceleration of
the munition. Instead of acceleration, it may alternatively be appropriate to refer
to force, or force experienced by the munition.
[0027] Referring to Figure 1, a prior art fuze system 10 is shown, and will be briefly described
herein. The fuze system 10 is provided in a munition 20. The munition 20 is subject
to a direct impact at a target 50. A direct impact may otherwise be known as a "head-on"
impact. In the illustrated example, direct impact involves an impact at an angle of
approximately 90 degrees between the munition travel direction 30 and the surface
52 of the target that the munition 20 is to impact. During the direct impact at the
target 50, high acceleration is experienced in the axis of the munition travel direction
30. The axis of the munition travel direction 30 is indicated generally at numeral
32. It will be appreciated that the axis 32 of the munition travel direction 30 may
be colinear with the munition travel direction 30. The fuze system 10 is arranged
to sense acceleration in the axis 32 of the munition travel direction 30, which may
otherwise be known as a longitudinal axis of the munition 20, or in the munition axial
sense. In this way, when the direct impact is sensed, the fuze is triggered.
[0028] Angled impacts may also occur. An angled impact may involve an impact at an angle
within a range of less than 90 degrees to approximately 10 degrees. In this event,
the acceleration may be separated into a component of acceleration in the axis of
the munition travel direction 30 and a component of acceleration in an axis transverse
to the munition travel direction 30. The combined magnitude of acceleration may be
relatively high. Nevertheless, in prior art fuze systems 10 subjected to angled impacts,
the fuze of the fuze system 10 will only be triggered if the acceleration in the axis
32 of the munition travel direction 30 exceeds the necessary threshold for triggering
the fuze.
[0029] The prior art munition 20 may be subject to a grazing impact at the target 50. In
such an event, the acceleration forces experienced in the axis 32 of the munition
travel direction 30 may be low, or comparably low relative to the expected acceleration
in the axis 32 of the munition travel direction 30 due to direct impact or angled
impact. This sensed acceleration may be insufficient to trigger the fuze of the fuze
system 10. The munition may rebound whilst remaining intact, and continue to travel
without detonating. Post-impact trajectory is less predictable, and the munition may
travel to an unintended location. Furthermore, as the fuze system 10 is only arranged
to sense acceleration in the axis 32 of the munition travel direction 30, the fuze
system 10 is unable to distinguish a direct impact event from a grazing impact event
or angled impact event.
[0030] Referring to Figure 2, a fuze system 100 according to an embodiment of the present
invention is shown. The fuze system 100 is for a munition 200.
[0031] The fuze system 100 comprises an impact sensor arrangement 110. The impact sensor
arrangement 110 is arranged to sense a component of acceleration in an axis away from
the munition travel direction 300. The axis away from the munition travel direction
300 is indicated generally at numeral 134. It will be appreciated that the axis 134
away from the munition travel direction 300 is not colinear with the munition travel
direction 300, but is angled away from the munition travel direction 300. It will
be appreciated that the munition travel direction 300 is the direction in which the
munition 200 is configured to travel when it is fired, when it is travelling, or during
its trajectory. The munition travel direction 300 may be the intended, or expected,
munition travel direction. The person skilled in the art will appreciate that the
munition travel direction 300 may be (and indeed, preferably is) a longitudinal axis
of the munition 200. That is, the munition 200 may be configured (i.e., deliberately
configured or designed) to travel in a munition travel direction 300, and the impact
sensor arrangement 110 arranged to sense a component of acceleration in an axis 134
away from said munition travel direction 300.
[0032] In this way, by the impact sensor arrangement 110 being arranged to sense a component
of acceleration in an axis 134 away from the munition travel direction 300, an improved
fuze system 100 is provided which is sensitive to non-direct impacts (that is, impacts
which occur at angles away from direct impact). An example of a non-direct impact
is shown in Figure 2, where the munition 200 is subject to a grazing impact at a target
500, but it will be appreciated that other angled impacts may be detected using the
fuze system 100. Furthermore, the fuze system 100 can distinguish between grazing
impact and low velocity direct impact. Thresholds for triggering the fuze of the fuze
system 100 can be set accordingly, enabling safer and more robust operation of the
fuze system 100 and munition 200.
[0033] The impact sensor arrangement 110 is configured to provide a first output based on
the sensing of the component of acceleration in the axis 134 away from the munition
travel direction 300. As above, the axis 134 away from the munition travel direction
300 may be the axis 134 away from the intended munition travel direction 300, and/or
the axis 134 away from the longitudinal axis of the munition 200.
[0034] In this way, the first output may be used by the fuze system 100 to trigger the fuze,
thereby to trigger the explosive payload.
[0035] The component of acceleration in the axis 134 away from the munition travel direction
300 may be a component of acceleration in an axis transverse to the munition travel
direction 300. For avoidance of doubt, an axis transverse to the munition travel direction
300 is an example of an axis away from the munition travel direction 300. That is,
the impact sensor arrangement 110 may be arranged, or configured, to sense the component
of acceleration in an axis transverse to the munition travel direction 300, or longitudinal
axis of the munition 200. The axis transverse to the munition travel direction 300
is indicated generally at 136. In this advantageous embodiment, the impact sensor
arrangement 110 (i.e., sensors and/or components thereof) are arranged to sense acceleration
along, or in, the transverse axis 136.
[0036] This is a highly advantageous arrangement. In contrast to prior art fuze systems
which are only arranged to sense the component of acceleration in the axis of the
munition travel direction, by sensing the component of acceleration in an axis 136
transverse to the munition travel direction 300, a grazing impact can be detected
or sensed. This is because during a grazing impact event, the component of acceleration
in an axis 136 transverse to the munition travel direction 300 is relatively high
compared with the component of acceleration in an axis of the munition travel direction
300.
[0037] The fuze system 100 may be configured to trigger an explosive charge 400. The fuze
system 100 may be configured to trigger the explosive charge 400 based on the first
output.
[0038] In this way, safety is improved as the explosive charge may be triggered when a non-direct
impact is detected or sensed.
[0039] The fuze system 100 may be configured to trigger the explosive charge 400 in response
to the first output of the impact sensor arrangement 110 being greater than or equal
to a first threshold value.
[0040] In this way, when the sensed component of acceleration in the axis 134 away from
the munition travel direction is greater than or equal to a first threshold value,
the explosive charge is triggered, which may occur due to a grazing impact with a
target.
[0041] The impact sensor arrangement 110 may be further arranged to sense a component of
acceleration in the axis of the munition travel direction 300. The axis of the munition
travel direction 300 is indicated generally at numeral 132. It will be appreciated
that the axis 132 of the munition travel direction 300 may be colinear with the munition
travel direction 300. That is, the impact sensor arrangement 110 may comprise the
functionality of the prior art, in addition to that of the present invention wherein
the impact sensor arrangement is arranged to sense a component of acceleration in
an axis 134 away from the munition travel direction 300.
[0042] In respect of this, the impact sensor arrangement 110 may comprise a first-type impact
sensor 112 (which may be taken to include, or be, a subarrangement of first-type impact
sensors, e.g., comprising one or more first-type impact sensors) arranged to sense
a component of acceleration in an axis 134 away from a munition travel direction 300.
The impact sensor arrangement 110 may further comprise a second-type impact sensor
114 (which may be taken to include, or be, a subarrangement of second-type impact
sensors, e.g., comprising one or more second-type impact sensors) arranged to sense
a component of acceleration in the axis 132 of the munition travel direction 300.
[0043] It will be appreciated from the above that the fuze system 100 may only be provided
with an impact sensor arrangement 110 arranged to sense a component of acceleration
in an axis away from a munition travel direction 300. As above, this is advantageous
in sensing, and appropriate functioning in response to, grazing impacts. However,
by the impact sensor arrangement 110 being additionally arranged to sense the component
of acceleration in the munition travel direction 300, further advantages are provided.
In particular, it may be easier to distinguish between grazing impacts, angled impacts,
direct impacts, and also non-target impacts.
[0044] The impact sensor arrangement 110 may be configured to provide a second output based
on the sensing of the component of acceleration in axis of the munition travel direction
300. The second output may be provided by the second-type impact sensor 114.
[0045] The fuze system 100 may be configured to trigger the explosive charge in response
to the second output (i.e., provided by the second-type impact sensor 114) being greater
than or equal to a second threshold value and the first output (i.e., provided by
the first-type impact sensor 112) being greater than or equal to a first threshold
value.
[0046] In this way, the fuze system 100 may thus appropriately trigger the explosive charge
in response to a direct or angled impact, resulting in improved safety of the fuze
system 100 and munition 200. Furthermore, where a grazing impact occurs or is expected
to occur, the threshold value for the second output could be set to be relatively
low, as long as the threshold value for the first output is set to be relatively high.
[0047] In another example in which the impact sensor arrangement 110 is configured to provide
a second output based on the sensing of the component of acceleration in the axis
of the munition travel direction 300, the fuze system 100 may be configured to trigger
the explosive charge in response to the second output being less than a second threshold
value and the first output of the impact sensor arrangement 110 being greater than
or equal to a first threshold value.
[0048] In this way, a grazing impact may be determined, and the explosive charge appropriately
triggered.
[0049] The fuze system 100 may be configured not to trigger the explosive charge in response
to the first output being less than the first threshold value and the second output
being less than the second threshold value.
[0050] In this way, safety is improved as it is established that both the component of acceleration
in the axis of the munition travel direction and the component of acceleration in
the axis away from the munition travel direction is insufficient to indicate that
an impact event of any kind with a target-of-interest has taken place. This may prevent
any kind of impact with rain, hail, foliage, or the like from triggering the explosive
charge.
[0051] In another example in which the impact sensor arrangement 110 is configured to provide
a second output based on the sensing of the component of acceleration in the axis
132 of the munition travel direction 300, the fuze system 100 may be configured to
trigger the explosive charge in response to the second output being greater than or
equal to a second threshold value and the first output of the impact sensor arrangement
110 being less than or equal to a first threshold value.
[0052] In this way, a direct impact event can trigger the explosive charge.
[0053] Where threshold values are referred to above, the first threshold values may be the
same first threshold values and the second threshold values may be the same second
threshold values. The first threshold values and second threshold values may be different.
Appropriate threshold values may be selected, used or set for the particular use case.
[0054] As describe above, the fuze system 100 is configured to compare outputs from the
impact sensor arrangement 110 with threshold values. In respect of this, the fuze
system 100 may comprise a processor (not shown) to perform the comparison. The fuze
system 100 may further comprise a memory (not shown) configured to store threshold
values. The processor may compare the output of the impact sensor arrangement 110
with the threshold value stored in the memory. The processor may provide a signal
to a fuze of the fuze system 100 to trigger the explosive charge.
[0055] Referring to Figure 3, an exemplary construction of the munition 200 is shown in
a front cross-section, viewed along the axis 132 of the munition travel direction
300 (e.g., along the longitudinal axis of the munition 200). In the example illustrated,
the impact sensor arrangement 110 comprises two sensors 112a, 112b which are orthogonally
oriented with respect to one another. The two sensors 112a, 112b may be provided by
two sensing components, which may be two components of the same sensor. The two sensors
112a, 112b may form part of the first-type impact sensor 112.
[0056] Each sensor 112a, 112b may be arranged to sense a component of acceleration in an
axis 134 away from the munition travel direction 300. In this example shown, each
sensor 112a, 112b is arranged to sense a component of acceleration in an axis 136a,
136b transverse to the munition travel direction 300. Each sensor 112a, 112b may be
arranged to sense an orthogonal component of acceleration.
[0057] Such a construction is highly advantageous in a munition which is configured to spin
(or rotate) during its trajectory. Such munitions may be known as spin-stabilised
munitions. In such cases, the sign and magnitude of the component of acceleration
in the axis 136a, 136b away from the munition travel direction 300 may be affected
by the relative orientation between the sensing axis 136a, 136b of the impact sensor
arrangement 110, the degree of rotation and the point and duration of impact. That
is, in an example where the impact sensor arrangement 110 is arranged to sense a component
of acceleration in an axis 136a, 136b transverse to the munition travel direction
300, if a grazing impact occurs when the sensing axis is perpendicular to the transverse
impact axis with the surface of the target, the impact sensor arrangement 110 would
not sense the grazing impact. In this way, null zones may result, and grazing impact
may not be detectable. This may occur twice per rotation of the munition 200. By providing
two orthogonally oriented sensors 112a, 112b, this problem is addressed, as at least
one of the sensors 112a, 112b would always sense the component of acceleration. Providing
two sensors 112a, 112b may also be advantageous in redundancy, thereby to ensure safe
operation of the munition 200. It is further possible to calculate the magnitude of
the acceleration due to grazing impact by adding the acceleration vectors determined
from the output of the two sensors 112a, 112b.
[0058] It will be appreciated by the skilled person that in spin-stabilised munitions, the
impact of centrifugal acceleration on the response of the impact sensor arrangement
110 may need to be considered, for example by setting appropriate thresholds such
that centrifugal acceleration alone is insufficient to trigger the fuze of the fuze
system 100.
[0059] Referring to Figure 4, an exemplary construction of the munition 200 is shown in
a front cross-section, viewed along the axis 132 of the munition travel direction
300 (e.g., along the longitudinal axis of the munition 200). In the example illustrated,
the impact sensor arrangement 110 comprises more than two sensors. In the illustrated
example, the impact sensor arrangement 110 comprises three sensors 112c, 112d, 112e.
The sensors 112c, 112d, 112e may be provided by a corresponding number of sensing
components, which may be components of the same sensor. The more than two sensors
112c, 112d, 112e may form part of the first-type impact sensor 112. The sensors 112c,
112d, 112e may be radially arranged, for example spaced by 360/n degrees, where n
is the number of sensors 112c - 112e. Advantageously, providing more than two sensors
may facilitate use of sensor types with more limited capabilities, for example non-ratiometric
and/or non-directional sensors. The combined output from these sensors may then be
used to derive a measurement of the component of acceleration in the axis away from
the munition travel direction 300 (e.g., the transverse acceleration).
[0060] In a further example of the fuze system 100, a single first-type impact sensor 112
arranged to sense a component of acceleration in an axis 134 away from a munition
travel direction 300 may be sampled over a relatively long period, which may be at
least one rotation period, and peak detection used to determine an impact event. Advantageously,
in this way, the impact of the null zones may be reduced. Furthermore, this may reduce
the need for multiple sensors in the impact sensor arrangement 110.
[0061] In a further example of the fuze system 100, the frequency component of a single
sensor 112 arranged to sense a component of acceleration in an axis 134 away from
a munition travel direction 300 could also be exploited, and the typical rotation
rate range of the munition could be used to improve discrimination of impact type.
Furthermore, this may reduce the need for multiple sensors in the impact sensor arrangement
110.
[0062] The sensing of the impact sensor arrangement 110 may be used to determine a ratio
of the components of acceleration. This may be dependent on the location and orientation
of sensors, nature of sensor outputs, number of sensors, and other factors. In an
example, the output of a first-type impact sensor 112 and the output of a second-type
impact sensor 114 can be used to determine a ratio of the components of acceleration.
The first-type impact sensor 112 and second-type impact sensor 114 may be orthogonally
arranged. The magnitudes of the ratiometric outputs of both sensors may be on the
same relative scale. Trigonometric calculation can be used to define ratios for particular
angles of impact, according to the equation
tan(impact angle) = output of the second type impact sensor 114 /
output of the first type impact sensor 112. In such an example, if a further orthogonal sensor (e.g., a third impact sensor)
is incorporated, the three outputs can be resolved into a single instantaneous acceleration
vector, using a similar trigonometric calculation. Applicable here, and throughout
the disclosure, taking into account the ratio of acceleration components rather than
absolute magnitudes thereof may be advantageous as impact events may occur over a
wide range of velocities.
[0063] It is possible for the impact sensor arrangement 110 to make use of many different
types of impact sensors. Different types of impact sensors, and their operation, suitability
and functionality, will be well understood by those skilled in the art. The impact
sensor arrangement 110 may comprise one or more accelerometers, which may be capacitive
accelerometers and/or piezoresistive accelerometers. The impact sensor arrangement
110 may additionally or alternatively comprise one or more piezoelectric sensors,
magnetostrictive sensors, electromagnetic sensors, electromechanical switches, strain
gauges and/or optical interference sensors.
[0064] Referring to Figure 5, a munition 200 is schematically illustrated. The munition
200 comprises a fuze system 100 in accordance with that described herein. That is,
the fuze system 100 may comprise any or all of the features described herein.
[0065] The munition may be a projectile. The projectile may be an unpropelled projectile.
The projectile may comprise an artillery munition, a mortar munition, or a tank munition.
[0066] Referring to Figure 6, a method is schematically shown. The method is a method of
using a fuze system for a munition. Step S610 comprises arranging an impact sensor
arrangement to sense a component of acceleration in an axis away from a munition travel
direction in which the munition is configured to travel. Step S620 comprises providing
a first output from the impact sensor arrangement based on the sensing of the component
of acceleration in the axis away from the munition travel direction.
1. A fuze system for a munition, the fuze system comprising an impact sensor arrangement
arranged to sense a component of acceleration in an axis away from a munition travel
direction in which the munition is configured to travel, the impact sensor arrangement
configured to provide a first output based on the sensing of the component of acceleration
in the axis away from the munition travel direction.
2. The fuze system according to claim 1, wherein the component of acceleration in an
axis away from the munition travel direction is a component of acceleration in an
axis transverse to the munition travel direction.
3. The fuze system according to claim 1 or claim 2, wherein the fuze system is configured
to trigger an explosive charge.
4. The fuze system according to claim 3, wherein the fuze system is configured to, in
response to the first output of the impact sensor arrangement being greater than or
equal to a first threshold value, trigger the explosive charge.
5. The fuze system according to claim 4, wherein the impact sensor arrangement is arranged
to sense a component of acceleration in the axis of the munition travel direction,
and the impact sensor arrangement is configured to provide a second output based on
the sensing of the component of acceleration in the munition travel direction, wherein
the fuze system is configured to:
trigger the explosive charge in response to the second output being greater than or
equal to a second threshold value.
6. The fuze system according to claim 4, wherein the impact sensor arrangement is arranged
to sense a component of acceleration in the munition travel direction, and the impact
sensor arrangement is configured to provide a second output based on the sensing of
the component of acceleration in the munition travel direction, wherein the fuze system
is configured to:
trigger the explosive charge in response to the second output being less than a second
threshold value.
7. The fuze system according to claim 5 or claim 6, wherein the fuze system is configured
not to trigger the explosive charge in response to the first output being less than
the first threshold value and the second output being less than the second threshold
value.
8. The fuze system according to any one of the preceding claims, wherein the impact sensor
arrangement comprises two orthogonally oriented sensors, or two sensing components,
each arranged to sense a component of acceleration in an axis away from the munition
travel direction.
9. The fuze system according to any one of the preceding claims, wherein the impact sensor
arrangement comprises more than two sensors each arranged to sense a component of
acceleration in an axis away from the munition travel direction.
10. The fuze system according to any one of the preceding claims, wherein the fuze system
is configured to detect peaks or frequency of the output of the impact sensor arrangement.
11. The fuze system according to any one of the preceding claims, wherein the impact sensor
arrangement comprises one or more accelerometers, capacitive accelerometers, piezoresistive
accelerometers, piezoelectric sensors, magnetostrictive sensors, electromagnetic sensors,
electromechanical switches, strain gauges and/or optical interference sensors.
12. A munition comprising the fuze system according to any one of the preceding claims.
13. The munition of claim 12, wherein the munition is a projectile, optionally an unpropelled
projectile.
14. The munition of claim 13, wherein the projectile comprises an artillery munition,
a mortar munition, or a tank munition.
15. A method of using a fuze system for a munition, the method comprising:
arranging an impact sensor arrangement to sense a component of acceleration in an
axis away from a munition travel direction in which the munition is configured to
travel; and
providing a first output from the impact sensor arrangement based on the sensing of
the component of acceleration in the axis away from the munition travel direction.