U.S. patent application number 17/602672 was filed with the patent office on 2022-06-09 for method of controlling ejection of a missile from a canister and system therefor.
This patent application is currently assigned to ISRAEL AEROSPACE INDUSTRIES LTD.. The applicant listed for this patent is ISRAEL AEROSPACE INDUSTRIES LTD.. Invention is credited to Ofer AVISHAI, Rabin SHALTIEL.
Application Number | 20220178658 17/602672 |
Document ID | / |
Family ID | |
Filed Date | 2022-06-09 |
United States Patent
Application |
20220178658 |
Kind Code |
A1 |
SHALTIEL; Rabin ; et
al. |
June 9, 2022 |
METHOD OF CONTROLLING EJECTION OF A MISSILE FROM A CANISTER AND
SYSTEM THEREFOR
Abstract
A method for reducing or eliminating "Missile Tip-off Effect"
(MTE) of a missile ejected from a canister. The method includes:
receiving data of desired canister state in response to a launch
command. The method further include perform repeatedly until an MTE
control criterion is met: (a) receiving, from a sensor associated
with the canister, data of measured canister state, and (b)
processing the data of the measured canister state and desired
canister state, for outputting data indicative of a command to an
actuator associated with the canister for modifying at least the
angular position of the canister, thereby reducing or eliminating
the (MTE) effect.
Inventors: |
SHALTIEL; Rabin; (Rehovot,
IL) ; AVISHAI; Ofer; (Yehud, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ISRAEL AEROSPACE INDUSTRIES LTD. |
Lod |
|
IL |
|
|
Assignee: |
ISRAEL AEROSPACE INDUSTRIES
LTD.
Lod
IL
|
Appl. No.: |
17/602672 |
Filed: |
March 19, 2020 |
PCT Filed: |
March 19, 2020 |
PCT NO: |
PCT/IL2020/050324 |
371 Date: |
October 8, 2021 |
International
Class: |
F41G 7/00 20060101
F41G007/00; F41G 3/14 20060101 F41G003/14; F42B 30/00 20060101
F42B030/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 11, 2019 |
IL |
265993 |
Claims
1. A method for reducing or eliminating "Missile Tip-off Effect"
(MTE) of a missile ejected from a canister comprising, by a
processor and associated storage: a. receiving data indicative of
desired canister state in response to a launch command, perform
repeatedly until an MTE control criterion is met: b. receiving,
from at least one sensor associated with the canister, data
indicative of measured canister state; c. processing at least said
data indicative of measured canister state and desired canister
state, for outputting data indicative of a command to at least one
actuator associated with the canister for modifying at least the
angular position of the canister; thereby reducing or eliminating
said (MTE) effect.
2. The method according to claim 1, wherein said measured canister
state includes measured canister angle and wherein desired canister
state includes desired canister angle.
3. The method according to claim 1 or 2, wherein said measured
canister state includes measured canister rate and wherein desired
canister state includes desired canister rate.
4. The method according to claim 3, wherein said processing for
outputting data indicative of said command complies with Equation
1: M c = - K ( I z .times. z c .times. a .times. n .times. i
.times. s .times. t .times. e .times. r ( 2 .xi. .omega. n ( q -
.theta. . c .times. o .times. m ) + ( .omega. n 2 - K c .times. a
.times. n .times. i .times. s .times. t .times. e .times. r I z
.times. z - c .times. a .times. n .times. i .times. s .times. t
.times. e .times. r ) ( .theta. canist .times. e .times. r -
.theta. c .times. o .times. m ) ) ) ##EQU00005##
5. The method according to any one of the preceding claims, wherein
said measured canister state includes measured missile angle and
wherein desired canister state includes desired canister angle.
6. The method according to claim 3, wherein said measured canister
state includes measured missile rate and wherein desired canister
state includes desired canister rate.
7. The method according to claim 6, wherein said processing for
outputting data indicative of said command complies with Equation
2: M c = - K canister ( I z .times. z c .times. a .times. n .times.
i .times. s .times. t .times. e .times. r ( 2 .xi. .omega. n ( q c
.times. a .times. n .times. i .times. s .times. t .times. e .times.
r - .theta. . c .times. o .times. m ) + ( .omega. n 2 - K c .times.
a .times. n .times. i .times. s .times. t .times. e .times. r I z
.times. z - c .times. a .times. n .times. i .times. s .times. t
.times. e .times. r ) ( .theta. canist .times. e .times. r -
.theta. c .times. o .times. m ) ) ) + - K m .times. i .times. ssile
( I z .times. z c .times. a .times. n .times. i .times. s .times. t
.times. e .times. r ( 2 .xi. .omega. n ( q missile - .theta. . c
.times. o .times. m ) + ( .omega. n 2 - K c .times. a .times. n
.times. i .times. s .times. t .times. e .times. r I z .times. z - c
.times. a .times. n .times. i .times. s .times. t .times. e .times.
r ) ( .theta. m .times. i .times. s .times. s .times. i .times. l
.times. e - .theta. c .times. o .times. m ) ) ) ##EQU00006##
8. The method according to any one of the preceding claims, wherein
the larger the difference between the desired canister state and
the measured canister state, the larger is said command.
9. The method according to any one of the preceding claims, wherein
said measured canister state includes data indicate of remaining
flight time of the missile in the canister, such that for the same
difference in measured angle or rate vs. desired angle or rate, the
shorter the remaining flight time, the larger the command.
10. The method according to any one of the preceding claims,
further comprising modifying on-the-fly said data indicative of
desired canister state.
11. The method according to any one of the preceding claims,
wherein at least one of said sensors is fitted on the canister.
12. The method according to any one of the preceding claims,
wherein at least one of said sensors is fitted on the missile.
13. The method according to any one of the preceding claims,
further comprising an array of canisters.
14. The method according to claim 13, wherein said data indicative
of measured canister state is obtained by averaging the data
indicative of the canister state of each canister of said
array.
15. A system for reducing or eliminating "Missile Tip-off Effect"
(MTE) of a missile ejected from a canister comprising, a processor
and associated storage configured to: receiving data indicative of
desired canister state in response to a launch command, perform
repeatedly until an MTE control criterion is met: a. receiving,
from at least one sensor associated with the canister, data
indicative of measured canister state; b. processing at least said
data indicative of measured canister state and desired canister
state, for outputting data indicative of a command to at least one
actuator associated with the canister for modifying at least the
angular position of the canister; thereby reducing or eliminating
said (MTE) effect.
16. A non-transitory computer-readable memory tangibly embodying a
program of instructions executable by the processor for executing
the method of any one of claims 1 to 14.
Description
TECHNICAL FIELD
[0001] The presently disclosed subject matter relates to a method
of controlling ejection of a missile from a canister and a system
therefor.
BACKGROUND
[0002] While ejecting a missile from a canister, the missile may
develop angles and angular rates due to parasitic initial
conditions. There are several parasitic effects that the missile
may encounter while ejecting from the canister. These effects are
commonly known as the "Missile Tip-off Effect" (MTE).
MTE may occur due to various reasons, such as: [0003] Acoustic
effects and canister-missile elasticity can resonate in the
canister whilst the missile is ejecting. The canister interacts
with the missile, and due to contact between the canister and the
missile, MTE develops. [0004] When the missile's centre of gravity
passes outside the canister upper plane, and if the canister is not
aligned with the vector of gravity. The reaction due to contact
between the missile and canister and the gravity force creates a
moment that develops angular rates, and hence MTE. [0005] Missile
geometric tolerances such as missile centre of gravity not aligned
with the symmetry axis, thrust misalignment, etc. [0006] Flow
turbulences due to gas ejecting from the missile, and aerodynamic
effects, may cause forces and moments that cause MTE.
[0007] Solving each of the above causes of MTE may be complex and
thus very costly. Therefore most solutions deal with controlling
the missile after launch.
[0008] Common solutions for MTE may use known per se existing or
improved missile actuators, or add a Thrust Vector Control (TVC)
that alleviates the MTE effect. If the current actuators are
aerodynamic actuators, they may not effectively deal with MTE,
since they are effective only at high velocities. In order to
render the aerodynamic actuators effective at low velocities, the
aerodynamic fins need to be redesigned. Such redesign can decrease
missile performance at higher velocities. If one chooses to
integrate into the missile design TVC units such as jet-vanes, a
gimbaled nuzzle etc., MTE may be reduced. However, such TVC units
are costly and add extra weight to the missile, and hence decrease
missile performance.
[0009] There is thus a need in the art to provide for a new
technique for controlling ejection of a missile from a
canister.
[0010] The discussion above teach background information that may
be applicable to the presently disclosed subject matter.
GENERAL DESCRIPTION
[0011] According to one aspect of the presently disclosed subject
matter there is provided a method for reducing or eliminating
"Missile Tip-off Effect" (MTE) of a missile ejected from a canister
comprising, by a processor and associated storage: [0012] a.
receiving data indicative of desired canister state in response to
a launch command, [0013] perform repeatedly until an MTE control
criterion is met: [0014] b. receiving, from at least one sensor
associated with the canister, data indicative of measured canister
state; [0015] c. processing at least said data indicative of
measured canister state and desired canister state, for outputting
data indicative of a command to at least one actuator associated
with the canister for modifying at least the angular position of
the canister; [0016] thereby reducing or eliminating said (MTE)
effect.
[0017] In addition to the above features, the system according to
this aspect of the presently disclosed subject matter can comprise
one or more of features listed below, in any desired combination or
permutation which is technically possible: [0018] The measured
canister state includes measured canister angle and wherein desired
canister state includes desired canister angle. [0019] The measured
canister state includes measured canister rate and wherein desired
canister state includes desired canister rate. [0020] The
processing for outputting data indicative of said command complies
with Equation 1:
[0020] M c = - K ( I z .times. z c .times. a .times. n .times. i
.times. s .times. t .times. e .times. r ( 2 .xi. .omega. n ( q -
.theta. . c .times. o .times. m ) + ( .omega. n 2 - K c .times. a
.times. n .times. i .times. s .times. t .times. e .times. r I z
.times. z - c .times. a .times. n .times. i .times. s .times. t
.times. e .times. r ) ( .theta. canist .times. e .times. r -
.theta. c .times. o .times. m ) ) ) ##EQU00001## [0021] The said
measured canister state includes measured missile angle and wherein
desired canister state includes desired canister angle. [0022] The
measured canister state includes measured missile rate and wherein
desired canister state includes desired canister rate. [0023] The
processing for outputting data indicative of said command complies
with Equation 2:
[0023] M c = - K canister ( I z .times. z c .times. a .times. n
.times. i .times. s .times. t .times. e .times. r ( 2 .xi. .omega.
n ( q canister - .theta. . c .times. o .times. m ) + ( .omega. n 2
- K canister I zz - canister ) ( .theta. canister - .theta. com ) )
) + - K missile ( I zz canister ( 2 .xi. .omega. n ( q missile -
.theta. . com ) + ( .omega. n 2 - K canister I zz - canister ) (
.theta. missile - .theta. com ) ) ) ##EQU00002## [0024] The larger
the difference between the desired canister state and the measured
canister state, the larger is said command [0025] The measured
canister state includes data indicate of remaining flight time of
the missile in the canister, such that for the same difference in
measured angle or rate vs. desired angle or rate, the shorter the
remaining flight time, the larger the command. [0026] Modifying
on-the-fly said data indicative of desired canister state. [0027]
At least one of said sensors is fitted on the canister. [0028] At
least one of said sensors is fitted on the missile. [0029] An array
of canisters. [0030] The data indicative of measured canister state
is obtained by averaging the data indicative of the canister state
of each canister of said array. [0031] According to one aspect of
the presently disclosed subject matter there is provided a system
for reducing or eliminating "Missile Tip-off Effect" (MTE) of a
missile ejected from a canister comprising, a processor and
associated storage configured to: [0032] receiving data indicative
of desired canister state in response to a launch command, perform
repeatedly until an MTE control criterion is met: [0033] a.
receiving, from at least one sensor associated with the canister,
data indicative of measured canister state; [0034] b. processing at
least said data indicative of measured canister state and desired
canister state, for outputting data indicative of a command to at
least one actuator associated with the canister for modifying at
least the angular position of the canister; [0035] thereby reducing
or eliminating said (MTE) effect.
[0036] This aspect of the disclosed subject matter can comprise one
or more of features listed above and applied to the system, mutatis
mutandis, in any desired combination or permutation which is
technically possible.
[0037] According to another aspect of the presently disclosed
subject matter there is provided a non-transitory program storage
device readable by a computer, tangibly embodying computer readable
instructions executable by the computer to perform a method for
reducing or eliminating "Missile Tip-off Effect" (MTE) of a missile
ejected from a canister.
[0038] This aspect of the disclosed subject matter can comprise one
or more of features listed above and applied to the non-transitory
program storage device, mutatis mutandis, in any desired
combination or permutation which is technically possible.
[0039] Among advantages of certain embodiments of the presently
disclosed subject matter is the use of sensors fitted on the
canister (rather than on the missile) and utilization of the
canister's actuator, thereby utilizing a lighter missile
considering that the need to fit larger and heavier actuators on
the missile (as is the case in some prior art solutions) may be
obviated. Yet another non-limiting advantage is the "shift" of
using hardware components (such as sensors and actuators) to a
sustainable multi-use canister assembly rather than fitting them
for one-time use on a disposable missile, thereby drastically
reducing the overall system costs.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] In order to understand the invention and to see how it can
be carried out in practice, embodiments will be described, by way
of non-limiting examples, with reference to the accompanying
drawings, in which:
[0041] FIG. 1 illustrates an exemplary operational scenario, in
accordance with certain embodiments of the presently disclosed
subject matter;
[0042] FIG. 2 illustrates a schematic illustration of a system, in
accordance with certain embodiments of the presently disclosed
subject matter;
[0043] FIG. 3 illustrates a functional block diagram of a system in
accordance with certain embodiments of the presently disclosed
subject matter;
[0044] FIG. 4 illustrates a functional block diagram of a control
system in accordance with certain embodiments of the presently
disclosed subject matter;
[0045] FIG. 6 illustrates a generalized flow-chart of a system in
accordance with certain embodiments of the presently disclosed
subject matter;
[0046] FIG. 7 illustrates schematically a simplified chart
comparing canister configuration with and without utilization of a
technique in accordance with certain embodiments of the presently
disclosed subject matter;
[0047] FIG. 8 illustrates a generalized flow-chart of a system in
accordance with certain other embodiments of the presently
disclosed subject matter; and
[0048] FIG. 9 illustrates schematically a simplified chart
comparing canister configuration with and without utilization of a
technique in accordance with certain other embodiments of the
presently disclosed subject matter.
DETAILED DESCRIPTION
[0049] In the following detailed description, numerous specific
details are set forth in order to provide a thorough understanding
of the invention. However, it will be understood by those skilled
in the art that the presently disclosed subject matter may be
practiced without these specific details. In other instances,
well-known methods, procedures, components and circuits have not
been described in detail so as not to obscure the presently
disclosed subject matter.
[0050] Unless specifically stated otherwise, as apparent from the
following discussions, it is appreciated that throughout the
specification discussions utilizing terms such as "processing",
"computing", "representing", "comparing", "generating",
"assessing", "matching", "updating", "reducing", "eliminating",
"outputting", "modifying", receiving", "obtaining" or the like,
refer to the action(s) and/or process(es) of a computer that
manipulate and/or transform data into other data, said data
represented as physical, such as electronic, quantities and/or said
data representing the physical objects. The term "computer" should
be expansively construed to cover any kind of hardware-based
electronic device with data processing capabilities including, by
way of non-limiting example, the processor disclosed in the present
application.
[0051] The terms "non-transitory memory" and "non-transitory
storage medium" used herein should be expansively construed to
cover any volatile or non-volatile computer memory suitable to the
presently disclosed subject matter.
[0052] The operations in accordance with the teachings herein may
be performed by a computer specially constructed for the desired
purposes or by a general-purpose computer specially configured for
the desired purpose by a computer program stored in a
non-transitory computer-readable storage medium.
[0053] Embodiments of the presently disclosed subject matter are
not described with reference to any particular programming
language. It will be appreciated that a variety of programming
languages may be used to implement the teachings of the presently
disclosed subject matter as described herein.
[0054] As used herein, the phrase "for example," "such as", "for
instance" and variants thereof describe non-limiting embodiments of
the presently disclosed subject matter. Reference in the
specification to "one case", "some cases", "other cases", "one
example", "some examples", "other examples" or variants thereof
means that a particular described method, procedure, component,
structure, feature or characteristic described in connection with
the embodiment(s) is included in at least one embodiment of the
presently disclosed subject matter, but not necessarily in all
embodiments. The appearance of the same term does not necessarily
refer to the same embodiment(s) or example(s).
[0055] Usage of conditional language, such as "may", "might", or
variants thereof should be construed as conveying that one or more
examples of the subject matter may include, while one or more other
examples of the subject matter may not necessarily include, certain
methods, procedures, components and features. Thus such conditional
language is not generally intended to imply that a particular
described method, procedure, component or circuit is necessarily
included in all examples of the subject matter. Moreover, the usage
of non-conditional language does not necessarily imply that a
particular described method, procedure, component or circuit is
necessarily included in all examples of the subject matter.
[0056] Attention is first drawn to FIG. 1, illustrating an
exemplary operational scenario, in accordance with certain
embodiments of the presently disclosed subject matter. As shown, a
missile 4 is ejected from a canister 2 in an array of canisters
3.
[0057] Note that by virtue of the MTE, the missile may be ejected
in an undesired angle e.g. as depicted schematically in 5.
[0058] Turning now to FIG. 2, it illustrates a schematic
illustration of a system, in accordance with certain embodiments of
the presently disclosed subject matter. Thus, in order to cope with
the specified Missile Tipoff Effect (MTE) (as will be explained in
greater detail below), in response to a launch command (including
meeting certain conditions such as time elapse after launch), the
angular position of the canister 21 (fitted on carrier 22) may be
modified by an actuator 23 in response to data indicative of an
appropriate command. The command is determined based on processing
data indicative of canister state as measured by at least one
canister sensor measurements (depicted schematically as 24) and/or
at least one missile sensor measurement depicted schematically as
25. Note that the sensor associated with the canister may be e.g.
fitted on the canister and/or the missile and may generate data
indicative of canister state (e.g. canister angle and/or canister
angular rate and/or missile's angle and/or missile's angular
rate).
[0059] Note that for simplicity of explanation, the description
below focuses on the specified non-limiting examples of measured
canister state. There may be other factors that are included in the
measured canister's state, such as data indicative of the remaining
flight of the missile inside the canister.
[0060] Note also that there may be more than one canister sensor,
and, likewise, more than one missile sensor, depending upon the
particular application. The specified sensor or sensors may be
mounted on the canister and/or the missile in a known per se manner
(e.g. the sensors may be fitted e.g. in/on the canister, and/or
in/on the missile).
[0061] Note also that in certain embodiments there may be an array
of canisters configured to launch a plurality of missiles.
Operation of the system may be adapted to utilize the input from
the plurality of sensors fitted on the array of canisters, all as
will be explained in greater detail below.
[0062] Note that whenever reference is made to "an actuator", "a
canister", or "a sensor", this may likewise apply to actuators or
canisters, mutatis mutandis.
[0063] Note also that the structure of the (canister's) carrier, as
well the operation of an actuator (in response to a command), is
generally known per se.
[0064] Note also that the term "measured" may embrace also other
operations such as pertinent processing of raw measured data.
[0065] Bearing this in mind, attention is drawn to FIG. 3,
illustrating a functional diagram of a system 300. The illustrated
system includes a control system 301 operatively coupled to a
canister's actuator 302. The canister's actuator controls the
angular position of the canister 303 (e.g. angle and/or angular
rate).
[0066] The control system 301 is also operatively coupled to the
canister's sensor(s) 304 and missile's sensors 305 for obtaining
data indicative of measured canister state (utilizing the canister
and/or missile sensors) as well as desired canister's state (e.g.
extracted from to database 307) for outputting a command to the
actuator affecting the canister's angular position (angle and/or
rate), and consequently also modifying the missile's angular
position (305). The whole sequence is repeated, e.g. in a closed
loop fashion until a Missile Tip-off Effect (MTE) control criterion
is met. This occurs for example when data indicative of the
measured canister state matches data indicative of the desired
canister state.
[0067] The desired canister's state (e.g. desired angle of
canister) is determined for instance in a manner that guarantees
that when the missile is ejected from the canister, its flight
trajectory "compensates" for the inherent parasitic effects that
the missile encounters while ejecting from the canister, thereby
reducing or eliminating the undesired MTE effect. As a result, the
missile may fly in a designated trajectory, obviating the need to
utilize cumbersome hardware, such as large steering surfaces, for
coping with the MTE effect, as is the case in prior art
solutions.
[0068] Note that when reference is made to sensing, measuring,
receiving and/or processing data from sensors, this should be
construed (whenever applicable) to include "data indicative of . .
. ", for instance following A/D, if necessary, and/or possible
preprocessing of the data.
[0069] Turning now to FIG. 4, it illustrates a functional block
diagram of a control system (CS) (301) in accordance with certain
embodiments of the presently disclosed subject matter.
[0070] The CS system 301 may in some examples be a computer. It
may, by way of non-limiting example, comprise a processing
circuitry 405. Processing circuitry 405 may comprise at least one
processor 401 (e.g. a general purpose processor), and memory 402.
Processor 401 may be specially configured for the desired purpose
by a computer program stored in a non-transitory computer-readable
storage medium.
[0071] Each may be configured to execute several functional modules
in accordance with computer-readable instructions, e.g. in
accordance with flow charts disclosed with reference to FIGS. 6 and
8.
[0072] The CS system may include input/output (I/O) 407, that may
have conventional input/output peripherals such as a keyboard,
mouse or touchscreen and/or other peripherals. System 301 may also
include network interface 409 to provide connectivity to network
110 for sending or receiving data. The CS may reside fully or
partially on board the system 10 or be placed at least partially in
a remote location and communicate with other portions thereof
residing in system 10.
[0073] It is noted that the teachings of the presently disclosed
subject matter are not bound by the system described with reference
to FIGS. 3 and 4. Equivalent and/or modified functionality can be
consolidated or divided in another manner and can be implemented in
any appropriate combination of software with firmware and/or
hardware and executed on a suitable device.
[0074] The equation below describes, by way of example, data
indicative of the actuation command to the canister actuator, and
assumes, for simplicity, that only canister sensor(s) are
utilized.
[0075] Thus,
M c = - K ( I zz .times. .times. _ .times. .times. canister ( 2
.xi. .omega. n ( q - .theta. . c .times. o .times. m ) + ( .omega.
n 2 - K c .times. a .times. n .times. i .times. s .times. t .times.
e .times. r I z .times. z - c .times. a .times. n .times. i .times.
s .times. t .times. e .times. r ) ( .theta. canist .times. e
.times. r - .theta. c .times. o .times. m ) ) ) Eq1 .
##EQU00003##
Where:
[0076] M.sub.c--an actuation command to the canister's actuator for
modifying the angular position of the canister.
[0077] K--normalizing gain
[0078] Izz_canister--canister moment of inertia around
perpendicular to missile ideal ejection direction
[0079] .xi.--desired closed loop damping coefficient
[0080] .omega..sub.n--desired natural frequency mode
[0081] K.sub.canister--canister stiffness
[0082] q--measured canister angular rate
[0083] {dot over (.theta.)}.sub.com--desired canister angular
rate
[0084] .theta..sub.canister--measured canister angle
[0085] .theta..sub.com--desired canister angle
[0086] Note, that the measured canister angle .theta..sub.canister
may be obtained from the canister's sensor and the measured
canister's angular rate q may be measured or calculated
therefrom.
[0087] Note also that the desired canister angle .theta..sub.com is
obtained and the desired {dot over (.theta.)}.sub.com canister
angular rate may be obtained or calculated therefrom. It is thus
noted that whenever a reference is made to "measured" e.g. angle or
rate, it encompasses also processing. Note that the resulting
activation command M.sub.c that is fed to the canister actuator
will result in modification of its angular position (angle and
possibly rate). In the latter example illustrated with reference to
Eq. 1, both the measured angular rate q and the angle position
.theta..sub.canister are controlled in the sense that the
activation command will be nulled in cases where both the angular
rate and angle match their corresponding desired values {dot over
(.theta.)}.sub.com and .theta..sub.com. In accordance with certain
other embodiments, only the angle is considered, e.g.
.theta..sub.canister (measured) vs. .theta..sub.com(desired),
yielding possibly a different flight trajectory of the missile for
eliminating or reducing the MTE effect. The latter are obviously
only non-limiting examples for overcoming the MTE effect. These
examples are not limiting (e.g. only the rate may be controlled)
and/or other parameters for control may be added or modified, all
depending upon the particular application.
[0088] As readily arises from the equation above, there are various
coefficients (including in the non-limiting example above: K,
Izz_canister, .xi., .omega..sub.n, K.sub.canister) and the command
M.sub.c is based by this example on the difference between the
measured canister angle and the desired one, as well as on the
difference between the respective rates. Note that the other
coefficients (e.g. K) may also affect the missile trajectory as it
ejects from the canister for coping with the MTE effect, all
depending upon the particular application.
[0089] The invention is not bound by the specified
coefficients.
[0090] Note also that the control may cease in case the "MTE
control criterion is met". This criterion may be met, e.g. in cases
where the desired and measured controlled parameters (e.g. angular
position and/or rate) match, or when the missile ejects from the
canister, or when the command to the actuators violates system
specifications (e.g. is overly large), to the extent that following
it may damage the canister and/or missile, and/or others, depending
upon the particular application.
[0091] Note that whenever the term match (or alike) is used, it may
embrace also a possible error, say .+-.up to 10% or in accordance
with other embodiments .+-.up to 5%.
[0092] Note also that the specified Eq. 1 is by no means binding.
Thus, by way of non-limiting example, if additional parameters are
monitored, such as, for instance, the position of the missile
within the canister, and the remaining flight duration of the
missile within the canister, a more accurate control (e.g. applied
by way of non-limiting example mutatis mutandis to equation I or
II--see below) may be achieved with possibly better results for
coping with the MTE effect.
[0093] Note also that in case of an array of canisters, the
actuation command may depend upon input from sensors fitted on two
or more of the canisters and/or two or more of the missiles. Thus,
by way of non-limiting example, measured canister angular rate (q)
may refer to averaging the measured canister angular rates as
obtained (or derived) from two or more sensors that are fitted on
respective two or more canisters of the array. The same holds true
for averaging canister's angle(s) over an array of canisters,
mutatis mutandis. Averaging is, of course, only a non-limiting
example.
[0094] Referring to FIG. 6, there is illustrated a generalized flow
chart of a sequence of operations in accordance with certain
embodiments of the presently disclosed subject matter. The
specified Eq. 1, illustrates a non-limiting example of the
specified sequence of operations.
[0095] Note that the flow chart with reference to FIG. 6 assumes,
for simplicity, that only canister sensors are utilized.
[0096] Thus, in step 601, data indicative of desired canister state
(e.g. desired canister's angle and angular rate) is received in
response to a launch command.
[0097] Then, until an MTE control criterion is met (602,603):
[0098] Data indicative of a measured canister state (e.g.
canister's rate and angle) is received from at least one sensor
associated with the canister (604); [0099] Thereafter, the data
indicative of measured canister state (e.g. canister's rate and
angle), and desired canister state, is processed (e.g. in
compliance with Eq. 1), for outputting data indicative of a command
to at least one actuator associated with the canister, for
modifying at least the angular position of the canister 605.
[0100] As will be exemplified in greater detail below, the MTE
criterion may be modified, depending upon the particular
application.
[0101] By way of non-limiting example, the specified Equation (Eq.
1) exemplifies, in a non-limiting manner, the specified steps
601-605.
[0102] By way of non-limiting example, the specified Equation (Eq.
1) exemplifies in a non-limiting manner the specified steps 601-605
and the MTE criterion may be met if the measured and desired values
match, or when the missile is ejected from the canister.
[0103] Turning to FIG. 7, this illustrates schematically a
simplified chart comparing canister configuration with and without
utilization of a technique in accordance with certain embodiments
of the presently disclosed subject matter.
[0104] Before moving on, note that the solid line graphs 703, 704,
706 and 707 in charts 710, 720, 730 and 740, respectively indicate,
as will be explained in detail below, the behaviour of the canister
(angle and angular rate), as well as the missile flying inside the
canister (angle and angular rate) in an unsupervised mode of
operation, i.e. without utilizing the technique in accordance with
certain embodiments of the presently disclosed subject matter. The
hashed line graphs 7005, 7003, 7007 and 7011 (in charts 710, 720,
730 and 740, respectively) indicate, as will be explained in detail
below, the behaviour of the canister (angle and angular rate), as
well as the missile flying inside the canister (angle and angular
rate) when utilizing the technique in accordance with certain
embodiments of the presently disclosed subject matter, e.g. in
accordance with Eq. 1 described above.
[0105] Bearing this in mind, and as shown by oscillating graph 703
(in chart 710), an unsupervised angular position of the canister
stems e.g. from an unsupervised angular rate thereof see graph 704
in chart 720 (wherein the ordinate represents angular rate).
[0106] It is noted that the oscillating angular position of the
canister by no means converges to the desired angle position 902
indicated by straight line n chart 910.
[0107] The angle and the rate of the missile (charts 730 and 740,
respectively) substantially follow suit. Namely, the angle (see
graph 706 in chart 730) and angular rate (see graph 707 in chart
740) of the missile flying inside (and constrained by) the canister
follow more or less the respective angle (graph 703) and angular
rate (graph 704) of the canister (excluding some lateral degree of
freedom of the missile inside the canister--as shown for instance
by interferences 708 and 709).
[0108] The net effect is that, at the point of ejection, when the
missile departs from the canister (see 7001 in chart 730), the
missile has a certain angular rate above 0 (7002 in chart 740)
which results in an ever-increasing angle 7010 while flying in the
boost phase, thereby intensifying the undue tip-off effect.
[0109] In contrast, and as readily arises from graph 7003, by
following the sequence of operation (e.g. in accordance with FIG.
6--for instance in compliance with Eq. 1--utilizing canister
sensor(s)), the angular rate of the canister will coincide with the
desired angular rate of the canister, e.g. 0, while the actual
angle 7005 coincides with the desired angle 702. The missile
angular rate will substantially follow suit (graph 7011 in chart
740) and coincides with the desired angular rate 7006 (in chart
740), e.g. 0, while the actual missile's angle coincides (matches)
with the desired missile's angle (7007 and 7008 of chart 730).
[0110] The net effect is that unlike the variable angular position
of the missile (7010 in chart 730) in the unsupervised mode of
operation, in accordance with certain embodiments of the invention,
by virtue of the desired angular rate (e.g. 0--see 7006 in chart
740) the missile's angular position will retain the desired angular
position after departing from the canister, e.g. 0 (see 7009 in
chart 730) (constituting an example of meeting the specified MTE
control criterion, when the desired and measured value match, or
when the missile ejects from the canister, thereby substantially
reducing or eliminating the tip-off effect.
[0111] Note that in the latter example, the measured canister's
state embraces measured canister angle and angular rate, and the
desired canister's state embraces desired canister angle and
angular rate.
[0112] The equation below describes, by way of yet another
non-limiting example, the actuation command to the canister
actuator, and assumes, for simplicity, that canister sensor(s) and
missile sensors are utilized.
M c = - K c .times. a .times. n .times. i .times. s .times. t
.times. e .times. r ( I z .times. z canister ( 2 .xi. .omega. n ( q
caniste .times. r - .theta. . c .times. o .times. m ) + ( .omega. n
2 - K c .times. a .times. n .times. i .times. s .times. t .times. e
.times. r I z .times. z - c .times. a .times. n .times. i .times. s
.times. t .times. e .times. r ) ( .theta. c .times. a .times. n
.times. i .times. s .times. t .times. e .times. r - .theta. c
.times. o .times. m ) ) ) + - K m .times. i .times. s .times. s
.times. i .times. l .times. e ( I z .times. z canister ( 2 .xi.
.omega. n ( q m .times. i .times. ssile - .theta. . c .times. o
.times. m ) + ( .omega. n 2 - K c .times. a .times. n .times. i
.times. s .times. t .times. e .times. r I z .times. z - c .times. a
.times. n .times. i .times. s .times. t .times. e .times. r ) (
.theta. missile - .theta. c .times. o .times. m ) ) ) Eq .times.
.times. 2. ##EQU00004##
[0113] Where:
[0114] M.sub.c--an actuation command to the canister's actuator for
modifying the angular position and the angular rate of the
canister.
[0115] K.sub.canister--normalizing gain for the canister
[0116] K.sub.missile--normalizing gain for the missile
[0117] Izz_canister--canister moment of inertia around
perpendicular to missile ideal ejection direction
[0118] .xi.--desired closed loop damping coefficient
[0119] .omega..sub.n--desired natural frequency mode
[0120] K.sub.canister--canister stiffness
[0121] q.sub.canister--measured canister angular rate
[0122] q.sub.missile--measured missile angular rate
[0123] {dot over (.theta.)}.sub.com--desired canister angular rate
.theta..sub.canister--measured canister angle
[0124] .theta..sub.missile--measured missile angle
[0125] .theta..sub.com--desired canister angle
[0126] Note, that the measured canister angle .theta..sub.canister
may be obtained from the canister's sensor and the measured
canister's angular rate q.sub.canister may be measured or processed
therefrom.
[0127] Note also that the measured missile angle
.theta..sub.canister may be obtained from the canister's sensor and
the measured canister's angular rate q.sub.missile may be measured
or calculated therefrom.
[0128] Note also that the desired canister angle .theta..sub.com is
obtained (received or calculated) and the desired {dot over
(.theta.)}.sub.com canister angular rate may be received or
calculated therefrom.
[0129] It is thus noted that whenever a reference is made to
"measured" e.g. angle or rate, it encompasses also processing.
[0130] Similarly to Eq. 1 described above, note that the resulting
activation command M.sub.c that is fed to the canister actuator
will result in modification of its angular position (angle and
possibly rate). In the latter example illustrated with reference to
Eq. 1, both the measured angular rate q and the angle
.theta..sub.canister are controlled in the sense that the
activation command will be nulled in the case that both the rate
and angle will match their corresponding desired values {dot over
(.theta.)}.sub.com and .theta..sub.com and also when the measured
angle and angular rate of the missile will match the corresponding
desired angle and angular rate of the canister. The latter
conditions, if met, exemplify meeting the MTE control
criterion.
[0131] In accordance with certain other embodiments, only the angle
is controlled (constituting a different MTE control criterion),
e.g. .theta..sub.canister (measured) vs. .theta..sub.com (desired)
and .theta..sub.missile (measured) vs. .theta..sub.com (desired),
yielding possibly a different flight trajectory of the missile for
eliminating or reducing the MTE effect. The latter are obviously
only non-limiting examples for overcoming the MTE effect. These
examples are not limiting (e.g. only the rate of either or both or
the missile and the canister are controlled; the missile measured
angle may be compared to the missile's desired angle rather than to
the canister's desired angular position, and, similarly, the
measured and desired rates of the missile are compared; and/or
other parameters for control may be added or modified, all
depending upon the particular application.
[0132] Those versed in the art will readily appreciate that in
accordance with certain embodiments, the MTE control criterion may
be changed depending upon some or all of the parameters that are
measures and/or controlled.
[0133] As readily arises from the equation above, there are various
coefficients (including in the non-limiting example above: K,
Izz_canister, .xi., .omega..sub.n, K.sub.canister, K.sub.missile)
and the command M.sub.c is based by this example on the difference
between the actual canister angle and the desired one, as well as
on the difference between the respective rates, and, by the same
token, on the difference between the measured missile angle and the
desired canister angle, as well as on the difference between the
respective rates.
[0134] Note that the other coefficients (e.g. K) may also affect
the missile trajectory as it ejects from the canister for coping
with the MTE effect, all depending upon the particular
application.
[0135] Note also that the control may cease in case the MTE control
criterion is met. This criterion may be met in case that the
desired and measured controlled parameters (e.g. angular position
and/or rate) match, or when the missile ejects from the canister,
or when the command to the actuators violates system specifications
(e.g. is overly large to the extent that following it may damage
the canister and/or missile.
[0136] Note also that the specified equation is by no means
binding. Thus, for example, in accordance with certain embodiments,
using K.sub.canister and K.sub.missile one can choose how to
incorporate the amount of data fusion between the two sensors. By
assigning K.sub.missile to be zero, the algorithm will use data
only from the canister, and by assigning K.sub.canister to be zero,
the algorithm will use data only from the missile. Any other
combination will fuse data from both of the sensors.
[0137] Referring to FIG. 8, there is illustrated a generalized flow
chart of a sequence of operations in accordance with certain
embodiments of the presently disclosed subject matter. The
specified Eq. 2, illustrates a non-limiting example of the
specified sequence of operations.
[0138] Thus, in step 801, data indicative of desired canister state
(e.g. desired canister's angle and angular rate) is received in
response to a launch command.
[0139] Then, until an MTE control criterion is met (802,803):
[0140] Data indicative of measured canister state (e.g. measured
canister's rate and angle, as well as measured missile's angle and
angular position) is received from at least one sensor associated
with the canister (804); [0141] Thereafter, the data indicative of
measured canister state and desired canister state is processed
(e.g. in compliance with Eq. 2), for outputting data indicative of
a command to at least one actuator associated with the canister,
for modifying at least the angular position of the canister
805.
[0142] Note that the command may be issued based on e.g. at least
one of: angular position of the canister (measured and desired),
angular position of the missile (measured and desired), angular
rate of the canister (measured and desired), angular rate of the
missile (measured and desired); possibly other parameters, such as
for instance, the position of the missile within the canister,
remaining flight duration of missile within the canister having a
more accurate control (e.g. applied by way of non-limiting example
mutatis mutandis to Equation 1 or 2--see below), and others.
[0143] As specified above, control may cease in case of a MTE
control criterion being met. This criterion may be met also e.g.
when the missile ejects from the canister, or e.g. when the command
to the actuators violates system specifications (e.g. is overly
large to the extent that following it may damage the canister
and/or missile).
[0144] By way of non-limiting example, the specified Equation (Eq.
2) exemplifies, in a non-limiting manner, the specified steps
801-805.
[0145] The same modifications apply mutatis mutandis to the
sequence of operations described with reference to FIG. 6.
[0146] Turning to FIG. 9, this illustrates schematically a
simplified chart comparing canister configuration with and without
utilization of a technique in accordance with certain embodiments
of the presently disclosed subject matter.
[0147] Before moving on, note that the solid line graphs 903, 904,
906 and 907 in charts 710, 720, 730 and 740, respectively indicate,
as will be explained in detail below, the behaviour of the canister
(angle and angular rate) as well as the missile flying inside the
canister (angle and angular rate) in an unsupervised mode of
operation, i.e. without utilizing the technique in accordance with
certain embodiments of the presently disclosed subject matter. The
hashed line graphs 9005, 9003, 9007 and 9011 (in charts 910, 920,
930 and 940, respectively) indicate, as will be explained in detail
below, the behaviour of the canister (angle and angular rate) as
well as the missile flying inside the canister (angle and angular
rate) when utilizing the technique in accordance with certain
embodiments of the presently disclosed subject matter, e.g. in
accordance with Eq. 2 described above.
[0148] Bearing this in mind, and as shown by oscillating graph 903
(in chart 910), an unsupervised angular position of the canister
stems e.g. from an unsupervised angular rate thereof see graph 904
in chart 920 (wherein the ordinate represents angular rate).
[0149] It is noted that the fluctuating angle of the canister by no
means converges to the desired angle 902 indicated by straight line
n chart 910.
[0150] The angle and the rate of the missile (charts 930 and 940,
respectively) substantially follow suit. Namely, the angle (see
graph 906 in chart 930) and angular rate (see graph 907 in chart
940) of the missile flying inside (and constrained by) the canister
follow more or less the respective angle (graph 903) and angular
rate (graph 904) of the canister (excluding some lateral degree of
freedom of the missile inside the canister--as shown for instance
by interferences 908 and 909).
[0151] The net effect is that at the point of ejection, when the
missile departs from the canister (see 9001 in Chart 930), the
missile has a certain angular rate above 0 (9002 in chart 940)
which results in an ever increasing angle 9010 while flying in
boost phase, thereby intensifying the undue tip-off effect.
[0152] In contrast, and as readily arises from graph 9003, by
following the sequence of operation (e.g. in accordance with FIG.
8--for instance in compliance with Eq. 2--utilizing canister
sensor(s) and missile sensors(s)), the angular rate of the canister
will coincide with the desired angular rate of the canister, e.g.
0, while the actual angle 9005 coincides with the desired angle
902. The missile angular rate will substantially follow suit (graph
9011 in chart 940) and substantially coincides with the desired
canister rate 9006 (in chart 940), e.g. 0, while the measured
missile's angle coincides with the desired canister angle (9007 and
9008 of chart 930).
[0153] Note incidentally that in accordance with certain
embodiments, there are minor fluctuations (e.g. graph 9011 around
9006, and 9007 around 9008), stemming from the fact that the
missile motion is measured, and, based thereon, the canister's
actuators are controlled.
[0154] The net effect is that unlike the variable angular position
of the missile (9010 in chart 930) in the unsupervised mode of
operation, in accordance with certain embodiments of the invention,
by virtue of the desired angular rate (e.g. 0--see 9011 in chart
940) the missile's angle will retain the desired angle after
departing from the canister, e.g. 0 (see 9009 in chart 930, IF 9011
9009), thereby substantially reducing or eliminating the tip-off
effect.
[0155] It is noted that the teachings of the presently disclosed
subject matter are not bound by the flow chart illustrated in FIGS.
8 and 9 and that the illustrated operations can occur out of the
illustrated order. It is also noted that whilst the flow chart is
described with reference to control system (301), this is by no
means binding, and the operations can be performed by elements
other than those described herein.
[0156] It is to be understood that the invention is not limited in
its application to the details set forth in the description
contained herein or illustrated in the drawings. The invention is
capable of other embodiments and of being practiced and carried out
in various ways. Hence, it is to be understood that the phraseology
and terminology employed herein are for the purpose of description
and should not be regarded as limiting. As such, those skilled in
the art will appreciate that the conception upon which this
disclosure is based may readily be utilized as a basis for
designing other structures, methods, and systems for carrying out
the several purposes of the presently disclosed subject matter.
[0157] It will also be understood that the system according to the
invention may be, at least partly, implemented on a suitably
programmed computer. Likewise, the invention contemplates a
computer program being readable by a computer for executing the
method of the invention. The invention further contemplates a
non-transitory computer-readable memory tangibly embodying a
program of instructions executable by the computer for executing
the method of the invention.
[0158] Those skilled in the art will readily appreciate that
various modifications and changes can be applied to the embodiments
of the invention as hereinbefore described without departing from
its scope, defined in and by the appended claims.
* * * * *