U.S. patent application number 14/822897 was filed with the patent office on 2016-06-30 for methods and devices for guidance and control of high-spin stabilized rounds.
The applicant listed for this patent is Jacques Fischer, Jahangir S Rastegar. Invention is credited to Jacques Fischer, Jahangir S Rastegar.
Application Number | 20160187111 14/822897 |
Document ID | / |
Family ID | 56163753 |
Filed Date | 2016-06-30 |
United States Patent
Application |
20160187111 |
Kind Code |
A1 |
Rastegar; Jahangir S ; et
al. |
June 30, 2016 |
Methods and Devices For Guidance and Control of High-Spin
Stabilized Rounds
Abstract
A method for deploying a control surface from an exterior
surface of a spinning projectile during flight is provided. The
method including: moving the control surface in an interior of the
projectile such that a portion of the movement retracts the control
surface into the interior and a portion of the movement extends the
control surface from the exterior surface of the projectile;
determining a roll angle of the projectile; and synchronizing the
movement of the control surface with the roll angle of the
projectile.
Inventors: |
Rastegar; Jahangir S; (Stony
Brook, NY) ; Fischer; Jacques; (Sound Beach,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Rastegar; Jahangir S
Fischer; Jacques |
Stony Brook
Sound Beach |
NY
NY |
US
US |
|
|
Family ID: |
56163753 |
Appl. No.: |
14/822897 |
Filed: |
August 10, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62035483 |
Aug 10, 2014 |
|
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|
Current U.S.
Class: |
102/438 |
Current CPC
Class: |
F42B 10/64 20130101;
F42B 17/00 20130101 |
International
Class: |
F42B 10/26 20060101
F42B010/26; F42B 5/03 20060101 F42B005/03 |
Claims
1. A control actuation device for a munition, the actuation device
comprising: a body having a cavity with an open end exposed to an
exterior; a slug/charge stack disposed in the cavity, the
slug/charge stack comprising: a first slug retained in the cavity
and a corresponding first charge positioned in the cavity such that
initiation of the first charge burns propellant contained in the
first charge to produce pressure to eject the first slug from the
open end to the exterior; and one or more second slugs retained in
the cavity and one or more corresponding second charges positioned
in the cavity such that initiation of the one or more second
charges burns propellant contained in the one or more second
charges to produce pressure to eject the one or more second slugs
from the open end to the exterior, the one or more second slugs
being one or more positioned or sized so as to not interfere with
portions of the cavity when being ejected from the open end; and an
initiator corresponding to each of the first charge and one or more
second charges for selectively initiating the first charge and one
or more second charges.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit to U.S. Provisional
Application No. 62/035,483 filed on Feb. 10, 2013, the entire
contents of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to guidance and
control systems, and more particularly, to methods and devices for
providing guidance and control of low and high-spin rounds.
[0004] 2. Prior Art
[0005] Guidance and control of high-spin stabilized rounds presents
major challenges. These challenges may be divided into two basic
categories. The first category includes the need for onboard
sensors for direct and precise measurement of the round
orientation, particularly in roll, for generating the required
control action. The need for precise roll angle measurement is
particularly critical for relatively short range direct fire
applications and for targeting during the terminal guidance phase
of larger frame munitions such as smart artillery and mortars. The
second category of challenges is related to the need for actuation
devices that are very low volume, do not rely on de-spinning of the
entire or a section of the round, can provide short duration
actuation for terminal guidance and occasional mid-flight course
correction as well as for continuously applied control action for
longer range munitions and dynamic retargeting, and that can
operate at spin rates of 200 Hz and possibly higher.
[0006] Since the introduction of 155 mm guided artillery
projectiles in the 1980's, numerous methods and devices have been
developed or are under development for guidance and control of
subsonic and supersonic rounds. These include different
technologies and related components such as actuation devices,
position and angular orientation sensors, and guidance and control
hardware and algorithms. The majority of these devices have been
developed based on missile and aircraft technologies, which are in
many cases difficult or impractical to implement on gun-fired
projectiles and mortars. This is particularly true in the case of
actuation devices, where electric motors of various types,
including various electric motor designs with or without gearing,
voice coil motors or solenoid type actuation devices used directly
to actuate control surfaces have dominated the guidance and control
of most guided weaponry. Thrusters of various types have also been
successfully employed. However, currently available thrusters are
suitable only for low or no-spin rounds due to their limitations in
terms of relatively long pulse widths and unpredictable actuation
delays as well as the required large volume and surface area that
needs to be covered to achieve enough number of actuation impulses
that are needed for high-spin round control action even for one
second of actuation control for terminal guidance purposes. Other
currently available actuation technologies developed for munitions
applications are suitable for non-spinning rounds or for rounds
with very low spinning rates.
[0007] Current guidance and control technologies and those under
development are not effective for flight trajectory
correction/modification of high-spin guided munitions. Such spin
stabilized rounds may have spinning rates of 200 Hz or higher,
which pose numerous challenging sensing, actuation and control
force generation and control algorithm and processing issues that
need to be effectively addressed using innovative approaches. In
addition, unlike missiles, all gun-fired spinning rounds are
provided with initial kinetic energy through the pressurized gasses
inside the barrel and are provided with flight stability through
spinning and/or fins. As a result, they do not require in-flight
control action for stability and if not provided with trajectory
altering control actions, such as those provided with control
surfaces or thrusters, they would simply follow a ballistic
trajectory. This is still true if other means such as
electromagnetic forces are used to accelerate the projectile during
the launch or if the projectile is equipped with range extending
rockets. As a result, unlike missiles, control inputs for guidance
and control is required only later during the flight and in many
cases as the projectile approaches the target.
[0008] In recent years, alternative methods of actuation for flight
trajectory correction have been explored, some using smart (active)
materials such as piezoelectric ceramics, active polymers,
electrostrictive materials, magnetostrictive materials or shape
memory alloys, and others using various devices developed based on
micro-electro-mechanical (MEMS) and fluidics technologies. In
general, the available smart (active) materials such as
piezoelectric ceramics, electrostrictive materials and
magnetostrictive materials (including various inch-worm designs and
ultrasound type motors) need to increase their strain capability by
at least several orders of magnitude to become potential candidates
for actuation applications for guidance and control, particularly
for gun-fired munitions and mortars. In addition, even if the
strain rate problems of currently available active materials are
solved, their application to gun-fired projectiles and mortars will
be very limited due to their very high electrical energy
requirements and the volume of the required electrical and
electronics gear. Shape memory alloys have good strain
characteristics but their dynamic response characteristics
(bandwidth) and constitutive behaviour need significant improvement
before becoming a viable candidate for actuation devices in general
and for munitions in particular, even those with very low spin
rates.
[0009] All currently available actuation devices based on
electrical motors of various types, including various electrical
motor types, voice coil motors and solenoids, with or without
different gearing or other mechanical mechanisms that are used to
amplify motion or force (torque), and the aforementioned recently
developed novel methods and devices (based on active materials,
such as piezoelectric elements, including various inch-worm type
and ultrasound type motors), or those known to be under development
for guidance and control of airborne vehicles such as missiles,
suffer from the basic shortcoming of not being capable of providing
the dynamic response levels that are required for guidance and
control of high-spin rounds with spin rates of up to 200 Hz or
higher. This fact is readily illustrated by noting that, for
example, a round spinning at 200 Hz would undergo 72 degrees of
rotation in only 1 msec. This means that if the pulse duration is
even 1 msec and its unpredictable initiation time (pulse starting
time) is off by 1 msec, then the direction of the effective impulse
acting on the round could be off by over 90 degrees, i.e., when a
command is given to divert the round to the right, the round may
instead be diverted up or down. Such a level of uncertainty in the
"plant" (round) trajectory correction response makes even the
smartest feedback control system totally ineffective.
[0010] For guidance and control system of all gun-fired munitions
and in particular high-spin rounds in which even the problematic
de-spinning options are not practical, the only feasible actuation
options are either the proposed high-precision and very short
duration impulse based actuation devices or the proposed
intermittently deployed control surface or drag element based
actuation devices. For guidance and control system of all high-spin
rounds as well as for terminal guidance of all gun-fired munitions
and mortars, the most important sensory input is that of the roll
angle measuring sensor. Roll angle measurement in munitions has
been a challenge to guided munitions designers in general and for
high-spin rounds in particular. The currently available laser gyros
are impractical for use in munitions due to size, cost and
survivability as well as for initialization of the roll angle
measurement. Magnetometers are also impractical since they can only
measure angle in two independent directions, which may not be
aligned for roll angle measurement at all times during the flight.
Their angle measurement is also not precise and requires a local
map and is susceptible to environment in the field. Inertial based
gyros may be used, but require initiation at regular time intervals
to overcome initial settling and drift issues.
[0011] In summary, the currently available guidance and control
systems and their components suffer from one or more of the
following major shortcomings that make them impractical for
application to high-spin guided munitions: [0012] 1. Limited
dynamic response: The munitions with high spin rates demand control
actuation systems that can provide either very short duration
(sub-milisecond) impulses or intermittently deployed control
surface or drag producing elements with very precise timing in
order for the control action to be applied over a limited range of
munitions roll angle. For example when an impulse type actuation
device is being used in a round spinning at 200 Hz, if the control
actuation is to be applied over a 10 degrees range of roll angle,
then the control actuation must be applied for only around 0.14
miliseconds, or at an equivalent frequency of around 7,200 Hz. This
would obviously eliminate any of the aforementioned currently
available actuation devices for such high-spin round guidance and
control applications, even in the presence of a highly precise roll
angle measurement sensor. [0013] 2. Impulse type actuation timing
and duration: In addition to the above dynamic response
limitations, the fastest thruster or impulse type guidance and
control actuation devices that are currently available suffer from
two basic shortcomings: (1) actuation impulse timing precision; and
(2) impulse width precision. The first shortcoming is mainly due to
unpredictable delays in the initiation devices, while the second
shortcoming is mainly due to the relatively long pulse durations in
currently available impulse generator and thruster technologies.
[0014] 3. Control surface and drag-based actuation device: Current
control surface based as well as drag-based actuation devices are
usually used in either non-spinning rounds or are mounted in a
de-spun section of an otherwise spin stabilized round, which are
either impractical or highly costly in terms of volume and power
requirements in high-spin rounds. Intermittently deployed drag
generating elements have been used in spinning rounds but not with
high spin rates. Drag generation based control is however highly
inefficient since it would reduce the munitions range. In addition,
currently studied and available drag-based devices using solenoids
and voice coil motors consume large amounts of power and are
problematic in terms of dynamic response, volume requirement and
survivability. [0015] 4. Roll angle measurement: An effective
guidance and control technology for high-spin rounds requires
sensors for onboard measurement of the projectile roll angle. The
roll angle sensor has to provide the required precision and should
not be subject to drift or other similar effects that over time
during the flight causes error to accumulate and render roll angle
measurement unreliable. It is also appreciated that one may use
roll angle sensors that are subject to drift and exhibit relatively
long settling times, but in such cases, appropriate means have to
be provided for initialization of the sensors at regular time
intervals. [0016] 5. High power requirement: All currently used
actuation mechanisms working with electrical motors and/or
solenoids of different types as well as actuators based on active
materials, such as piezoelectric materials and electrostrictive
materials and magnetostrictive materials (including various
inch-worm designs and ultrasound type motors) and shape memory
based actuator designs, are only applicable to munitions with low
spin rates. But even in such applications, they demand high
electrical power for their operation. [0017] 6. Occupy large
munitions volume: One solution that has been employed or has been
considered for high-spin guidance and control has been de-spinning
the entire round or a section of the round where the control
surfaces or the like are positioned. As a result, the
aforementioned dynamic response issues are resolved. Such solutions
are, however, impractical for medium caliber munitions due to the
lack of space to provide the means to de-spin the round. Such
solutions are practical for larger caliber rounds, but even for
these cases they are highly undesirable for the following reasons.
Firstly, the actuation devices and mechanisms required for
de-spinning occupy a significant portion of the round volume. The
available volume for payload is also further reduced since fins or
other stabilizing means must also be provided to ensure stable
flight. As a result, the weapon lethality is significantly reduced.
In addition, a significant amount of power has to be provided for
de-spinning of the round. [0018] 7. High cost of the existing
technologies, which results in very high-cost rounds, thereby
making them impractical for large-scale fielding. [0019] 8.
Relative technical complexity for the implementation of the current
guidance and control technologies for high-spin rounds such as for
de-spinning of the entire round or its guidance and control
section, which results in increased munitions cost.
SUMMARY OF THE INVENTION
[0020] The proposed technologies for guidance and control of
high-spin stabilized munitions include two classes of novel
actuation devices that are particularly suitable for high-spin
rounds. The first class of actuation concepts is based on
detonation of small amounts of charges to achieve short duration
impulses with highly predictable timing and duration. The second
class of actuation concepts is highly innovative and provides
intermittently deployed control-surface-based control action that
are driven by electric motors with rotary speeds that are a
fraction of the spin rate of the round. The deployed control
surfaces provide control action over a large range of roll cycle
while adapting to the roll angle positioning of the round to
maximize control action performance. The intermittent control
surface deployment mechanism may also be used to deploy drag-based
control elements in place of commonly used solenoids with orders of
magnitude increase in efficiency and dynamic response as well as
with orders of magnitude reduction in power consumption due to the
use of continuously rotating and balanced electric motors.
[0021] The proposed control technologies for guidance and control
of high-spin stabilized munitions also includes polarized RF
sensors with electronic scanning reference sources for onboard
direct and precision measurement of roll angle for control action
timing and magnitude control. The provision of onboard and
precision roll angle information provides the means to maximize the
effectiveness of the applied control action and minimize the
actuation system size and power requirements. Also provided is the
related control algorithms that would account for issues that are
specific to high-spin rounds for achieving optimal control
action.
[0022] Not included in this proposal are concepts that require
de-spinning of the entire or a section of the round since such
concepts have been shown to occupy a significant volume of the
round, thereby significantly reduce lethality; require a very large
amount of power to operate; are very costly to implement; and are
generally impractical for medium caliber munitions.
[0023] The proposed novel guidance and control technology concepts
for guided high-spin munitions provide the following novel features
and basic characteristics: [0024] 1. Provide novel integrated
guidance and control technology concepts that would address all
major challenges that are currently facing guided munitions
designers for high-spin rounds, including provision of two novel
classes of actuation concepts and sensors for direct and precision
measurement of roll angle for closing feedback guidance and control
loop. [0025] 2. For control action, two novel classes of concepts,
one impulse-based and the other based on intermittent deployment of
control surfaces (or drag producing elements) are proposed. [0026]
3. The first class of actuation concepts are based on detonation of
small amounts of charges to achieve short duration impulses with
highly predictable timing and duration. Unlike commonly used
thrusters in munitions, this class of impulse based actuation
devices are multistage, thereby occupying a fraction of munitions
volume and surface area for a desired number of actuation impulses.
This class of actuation device concepts provide very short duration
impulses with very high timing precision and repeatability--of the
order of 100-200 microsecond duration. The proposed impulse-type
actuation devices can provide impulses equivalent (several pulses
in one second) of 10 N-sec to 140 N-sec for up to 2 milliseconds.
For the development of the detonation charges and its integration
into the present impulse type actuation devices, Omnitek has teamed
up with Hanley Industries, a leading developer and manufacturer of
explosive charges and devices.sup.1. .sup.1 See letter of support
from Hanley Industries, Inc. of Alton, Ill. at the end of this
proposal, page 39. [0027] 4. The second class of actuation concepts
are highly innovative and provide intermittently deployed control
surfaces. This class of actuation devices are powered by electric
motors without requiring de-spinning of the entire or even a
section of the round. One of the novel features of this class of
intermittently deployed control surface actuation devices is the
capability of the actuation mechanisms to be driven by electric
motors that run at a fraction of the spin rate of the round,
thereby making them suitable for very high spin rate applications.
For example, the driving electric motor of several of such proposed
concepts can be driven at less than one tenth of the sound spin
rate, thereby requiring readily achievable motor speeds of around
20 Hz (1,200 rpm) for a round spinning at 200 Hz (12,000 rpm). When
desired, the mechanisms for intermittent deployment of control
surfaces may also be used to deploy drag-based control elements
instead of commonly used solenoids, thereby significantly
increasing their dynamic response while significantly reducing the
size and power requirement due to continuously rotating driving
electric motors. [0028] 5. Provide onboard sensors for direct and
precision measurement of the round roll angle to enable munitions
guidance and control system to precisely time the required control
action for trajectory correction/modification. For indirect fire
applications where pitch and yaw angles may also be required for
guidance and control purposes, the proposed angular orientation
sensors can also be used for their direct measurements. The sensors
can also be used for onboard position measurement without requiring
GPS signals. The sensory system is provided with innovative
scanning reference sources that can also be used to set up a full
local position and orientation referencing system for guided
munitions, weapon platforms, target designation, as well as for
soldiers. [0029] 6. The two detonation-based actuation concepts
provide high impulse levels with very short durations and with
minimal unpredictable impulse initiation and duration times to
provide control action for flight trajectory correction and/or
modification for high-spin munitions. The two concepts integrate a
novel and very fast and low power electrical initiation technology
with multi-shot detonation based impulse units to achieve very fast
acting and short duration impulses that can be timed with
appropriate precision to provide control action for the proposed
novel guidance and control technology. [0030] 7. The novel
intermittently deployable control surface actuation concepts
provide "quasi-continuous" control action with pitch control. They
are driven by continuously rotating electric motors that operate at
speeds that are a fraction of the round spin rate, thereby making
them suitable for spin rates of 200 Hz or even higher. When
desired, these intermittently deployed control surface concepts may
be used to generate lift type control action to minimally affect
munitions range or may be used to generate drag to generate
aerodynamic forces/torques. [0031] 8. The impulse-based actuation
devices require a fraction of one mJ of electrical energy to
operate for each impulse shot. The power requirement for the
intermittently deployed control surface based actuation devices is
also orders of magnitude less than currently used electrical motor
or solenoid driven actuation devices since they are driven mostly
at nearly constant rates, can be dynamically balanced to require
minimal force/torque to operate. The onboard polarized RF roll
angle sensors also require low power to operate since they are not
required to make continuous roll angle measurement since their
measurement is direct and free of error accumulation. [0032] 9. The
proposed actuation devices can be readily hardened to survive
setback shock loading of well over 50 KG. The two detonation-based
actuation concepts are essentially integrated into the structure of
the munitions as load-bearing structures, thereby occupy minimal
added volume and can be designed to withstand shock of well over 50
KG. The intermittently deployed control surface based actuators use
very small electric motors, similar to which have already been used
in gun-fired munitions. The control surfaces as well as their
deployment mechanisms are locked in placed during the launch and
deployed later during the flight. [0033] 10. The proposed novel
actuation device concepts are very simple in design, and are
constructed with relatively few moving parts, thereby making them
highly reliable even following very long storage times of over 20
years. [0034] 11. The proposed novel actuation device concepts are
very simple in design and utilize existing manufacturing processes
and components. As a result, the proposed actuation devices should
provide the means to develop highly effective but low cost guidance
and control systems for high-spin guided gun-fired projectiles.
[0035] 12. The proposed guidance and control technologies,
including their actuation devices and roll angle sensors, are shown
to be scalable to medium as well as large caliber munitions. [0036]
13. All components of the proposed guidance and control
technologies, including their actuation devices and roll angle
sensor electronics, have been used in munitions and have been shown
to operate in the temperature range of -65 to 165 degrees F. [0037]
14. The proposed novel guidance and control technologies actuators
can be used in both subsonic and supersonic spinning
projectiles.
[0038] A need therefore exists for the development of innovative,
low-cost guidance and control technologies for high-spin rounds
that address the aforementioned limitations of currently available
technologies in a manner that leaves sufficient volume inside
munitions for other components such as communications electronics
and fusing, as well as the explosive payload to satisfy the
lethality requirements of the munitions. The critical enabling
technologies for guidance and control of high spin munitions are
those related to precision roll angle measurement and to actuation
devices that can provide control action without requiring a section
of the round to be de-spun.
[0039] Such guidance and control technologies must consider the
relatively short flight duration for most gun-fired projectiles and
mortar rounds, which leaves a very short period of time within
which trajectory correction/modification has to be executed. Even
for longer range munitions, even though some control action may be
desirable in mid-flight but it is mostly required for terminal
guidance.
[0040] This means that for impulse based control actuation, such
devices must be capable of providing either very short duration
impulse-based actuation (of the order of 100-200 microseconds for
spin rates of around 200 Hz) at precisely prescribed and repeatable
roll angles--preferably within a range of less than 10 degrees.
This requirement translates to relatively large impulses of the
order of 10 N-sec to 140 N-sec for 100-200 microseconds for spin
rates of around 200 Hz and up to 2 milliseconds for low spin rates
of 10-20 Hz. In addition, to achieve an effective guidance and
control system for high-spin rounds, the system roll sensor must
also be very accurate (precision of the order of 1-2 degrees or
better) to be capable of providing initiating and/or
synchronization timing for the impulse actuation.
[0041] For intermittently deployed control surface and drag
producing type actuation devices, current technologies require
electric motors or solenoids to deploy the control element during a
very small portion of the round roll, preferably at most 30-60
degrees, i.e., during 1/12.sup.th to 1/6.sup.th of a roll cycle.
This means that the driving motor or solenoid must rotate at
several times the spin rate of the round. For example, if a
solenoid is used for such deployments, one cycle of solenoid action
would correspond to 1/12.sup.th to 1/6.sup.th of the round cycle,
therefore requiring a dynamic response of 2400 to 1200 Hz from the
solenoid for rounds with a 200 Hz spin rate, which is not realistic
to expect. Similarly high rotation rates are required for current
electric motor driven intermittently deployed actuation
devices.
[0042] The proposed novel actuation device concepts, the
feasibility of which were studied as part of the present Phase I
SBIR efforts, may be divided into two distinct classes, those that
are impulse based and those that are based on intermittent
deployment of control surface. The latter group may also be used to
deploy drag generating elements to produce the desired control
action. The drag-based control action is not emphasized in the
present proposal due to the aforementioned shortcoming of such
devices in reducing the munitions range. The Phase I feasibility
studies of this project presented later in this proposal clearly
indicate the feasibility of the proposed concepts to be developed
as part of the project Phase II efforts.
[0043] The guidance and control technologies and their components
must also consider problems related to hardening of their various
components for survivability at high firing setback shock loading,
high spin rates and the harsh firing environment. They must also be
scalable to medium caliber rounds. Reliability is also of much
concern since the rounds need to have a shelf life of up to 20
years and could generally be stored at temperatures in the range of
-65 to 165 degrees F.
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] These and other features, aspects, and advantages of the
apparatus and methods of the present invention will become better
understood with regard to the following description, appended
claims, and accompanying drawings where:
[0045] FIG. 1 illustrates a multi-stage slug-shot impulse base
control actuator.
[0046] FIG. 2 illustrates another embodiment.
[0047] FIG. 3 illustrates an operation of intermittently deployed
control surfaces for guidance and control of smart and guided
high-spin rounds.
[0048] FIG. 4 illustrates a preferred deployment of intermittently
deployed control surfaces during half of the spin cycle.
[0049] FIG. 5 illustrates an isometric view of the double-crank
intermittently deployed control surface actuator for guidance and
control of high speed guided and smart munitions.
[0050] FIG. 6 illustrates a side view of the double-crank
intermittently deployed control surface actuator for guidance and
control of high speed guided and smart munitions of FIG. 5.
[0051] FIG. 7 illustrates the control surface deployment and
retraction linkage mechanism with parallel link orientation
retainment cam.
[0052] FIG. 8 illustrates isometric view of the double-cam operated
intermittently deployed control surface actuator for guidance and
control of high speed guided and smart munitions.
[0053] FIG. 9 illustrates side view of the intermittently deployed
control surface actuator of FIG. 7.
[0054] FIG. 10 illustrates side views of the intermittently
deployed control surface actuator of FIGS. 8 and 9 as partially and
fully retracted by the device cams.
[0055] FIG. 11 illustrates side view of the first alternative cam
operated intermittently deployed and retracting control surface
actuator (left) and isometric view of the double sided cam.
[0056] FIG. 12 illustrates side view of the deployed control
Surfaces.
[0057] FIG. 13: Side view of the second alternative cam operated
intermittently deployed and retracting control surface actuator and
isometric view of the cams.
[0058] FIG. 14: Side view of the control surfaces deployed by the
pair of cam surfaces provided on the rotating cam disc (FIG.
13--left).
[0059] FIG. 15: Frontal view of the cam-mechanism operated
intermittently deployed and retracted control surface actuator in
deployed configuration.
[0060] FIG. 16: The deployment and retraction cam motion during
four full spin cycles of the round and one rotation cycle of the
arm of the driving planetary gear.
[0061] FIG. 17: Frontal view of the fixed gear driven
intermittently deployed and retracted control surface actuator in
deployed configuration.
[0062] FIG. 18: Control surface deployment and retraction cycle
during one full spin cycle of the round and corresponding one-half
rotation cycle of the gear platform.
[0063] FIG. 19: Frontal view of the gear-pinion driven
intermittently deployed and retracted control surface actuator in
deployed configuration.
[0064] FIG. 20: Control surface deployment and retraction cycle
during one full spin cycle of the round and corresponding 90
degrees rotation cycle of the main gear.
[0065] FIG. 21 illustrates polarized RF sensors.
[0066] FIG. 22 illustrates the sensors of FIG. 21 disposed on a
munition.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The Proposed Two Novel Classes of Actuation Device Concepts for
High-Spin Munitions
[0067] In this section, the design and operation of the
aforementioned two classes of actuation concepts for guidance and
control systems of high-spin guided munitions, the feasibility of
which were investigated during the Phase I period of this SBIR
project, are described. The first class of actuation concepts are
based on detonation of small charges to achieve short duration
impulses with highly predictable timing and duration. The second
class of actuation concepts provide intermittently deployed
control-surface-based control action with pitch control that are
driven by electric motors with rotary speeds that are a fraction of
the spin rate of the round. The deployed control surfaces provide
control action over a large range of roll cycle while adapting to
the roll angle positioning of the round to maximize control action
performance. The intermittent control surface deployment mechanisms
may also be used to deploy drag-based control elements in place of
commonly used solenoids with orders of magnitude increase in
efficiency and dynamic response as well as with orders of magnitude
reduction in power consumption due to the use of continuously
rotating and balanced electric motors.
1.1.1. Multi-Stage Impulse Based Guidance and Control Actuators
a) Multi-Stage Slug-Shot Impulse Based Control Actuators
[0068] The schematic drawing of such a novel slug-shot impulse
based guidance and control actuator for high-spin rounds is shown
in FIG. 1. To generate a very short duration shot, the endmost
(largest) slug is ejected by igniting the charge behind it
(initiator not shown in figure for the sake of clarity). The
pressure of the burning propellant will rise until the threads
which engage the plug to the housing tube fail, allowing the slug
to be ejected (shot) and the high-pressure propulsion charge to
flow into the lower-pressure surrounding atmosphere, thereby
generating a very short duration and high amplitude impulse. The
two remaining charges are protected against sympathetic initiation
by the second (middle) threaded slug. When the next slug is
commanded to fire, the process will be identical to that of the
first slug. The second slug's smaller diameter will ensure that the
second slug does not have a long path of mangled threads to
interfere with its exit path. The third slug will fire and be
ejected similarly.sup.2. .sup.2 Omnitek Partners, LLC has developed
and tested methods of designing single slug-shot, short duration
impulse generating actuation devices under a U.S. Army SBIR Phase
I, II and Enhancement funding in collaboration with its
sub-contractor, Custom Analytical Engineering Systems, Inc. of
Flinstone, Md. An instrumented impulse measurement machine was also
developed under this program for precision measurement of the
impulse duration and value as well as delay firing initiation
signal. Multi-stage thruster technology was developed as part of
this effort. The present novel technology combines these two
technologies to achieve multi-stage slug shot actuation.
[0069] It is noted that in FIG. 1 the diameter of the second and
third slugs are shown to be significantly smaller than the diameter
of the front slug for the purpose of clearly demonstrating the
present concept. In an actual device the diameter of each slug
needs to be only slightly small than those in front to clear the
threaded portions that it has to pass through. In addition, less or
more than three slugs may also be employed. It is also noted that
the main purpose of the thread is to ensure that pressure and
temperature builds up behind each slug following ignition of the
charges and thereby increasing the speed of burn and increasing the
level of generated impulse. Omnitek's previous one-shot impulse
actuation device design and testing efforts.sup.6 has shown that
the proposed impulse-based actuation devices can provide impulses
equivalent to (several pulses in one second) of 10 N-sec to 140
N-sec for up to 2 milliseconds.
[0070] Omnitek has also developed patented solid-state electrical
initiation devices with safety circuitry and logic in collaboration
with the U.S. Army Research Laboratory (ARL) that have been tested
to show initiation of the secondary pyrotechnic material in 10-15
microseconds. In this project, Omnitek intends to distribute
several of these miniature and very low power initiation devices
around the aforementioned detonation charges to achieve very short
duration, high impulse level, reliable, and highly predictable
(within a maximum of 10-15 microsecond) pulses.
b) Multi-Shot Impulse Thrusters Based Control Actuators
[0071] The schematic drawing of a typical multi-shot impulse
thruster for guidance and control of high-spin rounds is shown in
FIG. 2. This thruster concept is a modification of omnitek's
aforementioned developed multi-stage thruster technology.sup.6.
This modification is intended to significantly increase the
generated impulse, decrease its duration and make it more
predictable. This is accomplished as described below.
[0072] This multi-stage impulse actuation device is constructed
with several "impulse" units (in this case three such units). Each
unit is packaged in a relatively solid pyrotechnic housing, within
which is packaged the primary propellant charges. Each unit is
capped with a relatively brittle cap with scored frontal face, such
that back pressure generated by the ignition of the primary
propellant charges would shatter the cap into small enough pieces
that could be discharged through the thruster nozzle. In operation,
the front impulse unit is first initiated. The initiation is
achieved electrically by the initiation of the aforementioned
low-energy and very fast electrical initiation (not shown in FIG. 2
for clarity), with unfolding wires provided through a side channel
to each impulse unit. Following initiation of each impulse unit,
the next impulse unit is pushed forward by the aft compressively
preloaded spring, for the purpose of ensuring minimal volume space
in which the gasses generated by each impulse unit have to expand,
thereby increasing pressure and temperature at which the generated
gasses begin to exit the nozzle to produce actuation impulse. The
impulse unit caps have dual purpose, firstly to prevent sympathetic
ignition of the next impulse units, and secondly to allow pressure
and temperature rise inside the initiated impulse unit before the
generated gasses are released into the nozzle volume, thereby
increasing the rate of propellant burn and decreasing the generated
impulse duration and to make impulse timing more predictable.
1.1.2. Novel Intermittently Deployable Control Surface Concepts for
Guidance and Control Actuation
[0073] This class of actuation concepts are highly innovative and
provide intermittently deployed control surfaces for control
action. These actuators are driven by electric motors with rotary
speeds that are a fraction of the spin rate of the round. The
deployed control surfaces are designed to provide control action
with pitch control during the flight over a large range of the
munitions roll cycle while adapting to the roll angle positioning
of the round to maximize control action performance. This class of
actuation devices will provide a quasi-continuous fin or canard
lift based control action for high-spin rounds, thereby making them
suitable for short as well as longer range guided and smart
gun-fired munitions without affecting their range.
[0074] The basic operation of this class of intermittently deployed
control surface actuation devices in spinning rounds during the
flight is shown in FIG. 3. In FIG. 3 and from left to the right the
round is shown during the flight during one cycle of its roll in 90
degrees rotational increments. A pointing triangle drawn on the
base of the round indicates its relative roll angle positioning of
the round.
[0075] As can be seen in FIG. 3, in the first position indicated by
(a), the control surfaces are fully deployed. In this position, the
roll angle position indicator triangle on the base of the round is
at its up position. Then as the round rotates in the clockwise
direction as shown by the arrow by 90 degrees to the position
indicated as (b), the control surface is slowly retracted into the
round. The control surfaces remain retracted for 180 degrees
through the roll positions indicated by (c) and (d). Then from the
roll positioning indicated by (d) up to the completion of one roll
cycle indicated by (e) in FIG. 3, the control surfaces are again
deployed. As a result, during half of a full roll angle cycle, the
control surfaces are deployed and retracted once.
[0076] In this class of intermittently deployed actuation devices,
control surfaces are deployed only during a certain range of roll
angle positioning of the round and are retracted during the
remaining range of the roll angles. For example for the full spin
cycle of FIG. 3, the control surfaces would begin to be deployed
from around the roll positioning (d), providing fully deployed
control surfaces at the roll positioning (e). Then from the roll
positioning (e)--which is the same positioning indicated as (a)--to
the roll positioning (b), the control surfaces are retracted. The
control surfaces will then remain contracted until the indicated
roll positioning (d), when the above cycle begins to be
repeated.
[0077] To achieve as close to maximum performance as possible, the
developed intermittently deployable control surface concepts have
to provide at least one of the following two basic
capabilities.
[0078] The first capability is related to the provision of the
means of keeping the deployed control surfaces as close to their
optimal lift generation direction as possible. For maximum
effectiveness during each cycle of deployment, the control surfaces
must obviously also be deployed during as much of the spin cycle as
possible. For example, if the desired direction of the lift is in
the vertical direction, then the control surfaces are desired to
stay as close to horizontal plane as possible during their entire
period of deployment which is also desired to be as large a portion
of the full spin (roll) cycle as possible. Such an intermittently
deployed control surface feature is shown in the longitudinal view
of a spinning round in FIG. 4. In FIG. 4, the round position from
its initial position (a) is shown where the control surfaces are
fully retracted. This roll position of the clockwise rotating round
is marked by the indicated triangle. As can be seen, during the
entire deployed phase of (a) to (g), which corresponds to half of
round spin (roll) cycle, the control surfaces stay in the indicated
horizontal (or whatever prescribed) plane, thereby keeping the
direction of the lift vector fixed, i.e., upward in the case of
FIG. 4.
[0079] In the schematics of FIG. 4, the control surfaces are shown
to begin to continuously deploy from the indicated position (a),
becoming fully deployed after 90 degrees of spin (roll) as
indicated in the position (d). The control surfaces are then
continuously retracted from the position (d), until after another
90 degrees of roll, the control surfaces are fully retracted as
shown in the position (g). Then during the remaining 180 degrees of
roll from the position shown in (g) to that of (a), the control
surfaces remain retracted. It is noted that while deployed, the
control surfaces undergo their motion while staying parallel to the
prescribed direction to keep the generated lift is at its maximum
and in the prescribed upwards direction.
[0080] The second capability is related to the provision of the
means to vary the control surface pitch angle to make it possible
provide a continuously varying lift, i.e., control action, for the
guidance and control system.
[0081] To make intermittently deployable control concepts suitable
for high spin rounds, such as those with spin rates of up to 200 Hz
and even higher, a further and important feature would be the
capability to deploy the control surfaces during one cycle of roll
and skipping one or more cycles of the roll. This capability would
provide the means to run the control surface deployment mechanism
at speeds that are significantly lower than the spin rate of the
round and would thereby allow higher spin rates to be
accommodated.
[0082] Another general feature that is desirable for almost all
intermittently deployable control surface base control action
devices for guidance and control of high spin rounds is their
capability of being driven by electric motors at lower speeds than
the round spin rate and that they should run at relatively constant
speed to minimize their power requirement.
[0083] In addition, almost all intermittently deployable control
surface base control action devices for guidance and control of
high spin rounds must be capable of being activated as well as
deactivated at the desired time during the flight.
[0084] In the following section of the proposal, detailed
preliminary design of several of the developed intermittently
deployable control surface concepts that have been developed and
were studied for feasibility for guidance and control of high speed
rounds are presented. The presented concepts are those with the
highest potential for successful development for the indicated
ranges of spin rates. The specific features of each design concept
that might make them for different caliber guided munitions and the
results of preliminary calculations of their performance are also
presented and their general size and volume requirements are also
provided.
a) Double-Crank Operated Intermittently Control Surface Deploying
Mechanism
[0085] The preliminary design of the first intermittently deployed
control surface based actuation device for guidance and control of
high spin rounds is shown in the solid model views of FIGS. 5 and
6. In FIG. 5 an isometric view of the device is shown with all its
covers removed to show the internal components of the device. The
structure of the device is considered to be an integral part of the
intended high spin stabilized projectile body. The indicated
control surface and pitch control mechanism driving motors are both
double shaft motors that are attached to the structure (body) of
the spinning round. One shaft of the control surface drive motor is
attached through the indicated set of driving gears to the
crankshaft that deploys one control surface and the other shaft to
the crankshaft that deploys the opposite control surface. The pitch
control motor is also double shaft and is used to rotate the "pitch
control mechanism arm", FIG. 6, which would in turn translate
upward the "pitch control mechanism link" on one side of the
"control surface orientation holding mechanism" and downward the
"control surface orientation holding mechanism" on the other side
of the "control surface orientation holding mechanism", FIG. 5,
thereby providing the means to vary the pitch of both control
surface.
[0086] The operation of the control surface deployment and
retraction mechanism is here described using the kinematic diagram
of the mechanism shown in FIG. 7. The mechanism is shown to be a
five-bar linkage mechanism with a cam that is used to reduce its
degrees-of-freedom from two to one, while forcing the control
surfaces to move in parallel during the spin (roll) cycle of the
round as shown schematically in FIG. 4. In the kinematic diagram of
FIG. 7, the deployment and retraction mechanism of only one of the
control surfaces is shown in different positioning of the input
crank, which is driven by the indicated driving motor and its
gearing, FIG. 5.
[0087] As can be seen in view (b) of FIG. 7, the control surface
linkage deployment and retraction mechanism is a "four-bar" linkage
with one of the grounded links varying as the opposite grounded
link is driven by the electric motor attached to the round. Here,
the ground is intended to indicate the structure (spinning body) of
the round. In this mechanism, as the said length varying link
rotates relative to the round, the "control surface orienting cam",
which is fixed to the round, will force the indicated cam follower
to vary the length of the link, thereby causing the coupler link to
which the control surface is attached to rotate. In this mechanism,
the control surface orienting cam profile is designed such that as
the round rolls, the deployed control surface, i.e., the coupler
link of the "four-bar" linkage, translate in parallel, thereby be
oriented as was shown in FIG. 4. The control surface orientation
while retracted is arbitrary and is designed to minimize dynamic
forces acting on the mechanism to allow higher speed motions. In
FIG. 7, the provided tringle is considered to be fixed to the
round. The configuration of the fully deployed control surface is
shown in view (a). Then as the round rotates 45 degrees, view (b),
the control surface is continuously retracted while the cam
mechanism forces the control surface to undergo parallel
translation. The control surface is then fully retracted, view (c),
as the round spins from 45 to 90 degrees roll angle. The control
surface will then continue its motion inside the round from 90 to
270 degrees roll angle, views (c) through (e), respectively, and
then begins to be oriented parallel to its deployed orientation,
views (a) and (f), and around 325 degrees roll angle it begins to
be deployed while staying parallel to its desired deployed
orientation of views (a), (b) and (f).
[0088] It is noted that several different implementation of the
basic intermittently deployed control surface actuation devices
shown in FIGS. 5 and 6 are possible and optimal for different
caliber munitions and spin rate. The preliminary design shown in
FIGS. 5 and 6 is developed for 81 mm rounds and can therefore be
readily scaled to the munitions caliber. This design concept is not
suitable for medium caliber rounds without major modifications.
b) Double-Cam Operated Intermittently Control Surface Deploying
Mechanism
[0089] The preliminary design of the second intermittently deployed
control surface based actuation device for guidance and control of
high spin rounds is shown in the solid model views of FIGS. 8 and
9. In FIG. 8 an isometric view of the device is shown with all its
covers and shell structure either removed or are made transparent
to show the internal components of the device. The structure of the
device is considered to be an integral part of the intended high
spin stabilized projectile body. The indicated control surface
driving motor drives a gear box which would in turn drive two
control surface deployment cams via a double counter-rotating inner
and outer shafts. In a more compact design, the cams are mounted on
the same gearbox shaft and the profile of the follower section of
the rotating control surfaces are designed to achieve the same
control surface motion. The pitch control mechanism driving motor
is a double shaft motor which is used to simultaneously vary the
control surface pitch angles of both control surfaces to achieve a
smooth and symmetrically operating mechanism. Both said motors and
gear box are attached to the structure (body) of the spinning
round.
[0090] In the intermittently deployable control surface concept of
FIGS. 8 and 9, the mechanism cams are used to retract the control
surfaces while a spring is used to simultaneously deploy the
control surfaces. In FIG. 10, the control surfaces are shown in the
views (a) and (b) as they are partially and fully retracted by the
aforementioned cams, respectively.
[0091] The pitch control motor is used to rotate the input link of
the pitch control linkage, FIG. 8, which is effectively a four-bar
linkage mechanism, which would in turn rotate the rotating shaft of
the control surface element to vary its pitch. The said control
surface shaft is connected to the "control surface deployment arm"
via a swivel joint to allow it to rotate to deploy and retract, as
well as rotate (about a perpendicular direction) for pitch angle
adjustment.
[0092] It is noted that in the intermittently deployed control
surface mechanism of FIGS. 8-10, the mechanism cams are used to
retract the control surfaces while the indicated spring element is
used to rapidly deploy the control surfaces. It is obvious that the
role of these elements can be reversed, i.e., the cams may be used
to deploy the control surfaces and the spring to retract them.
[0093] It is noted that in the intermittently deployed control
surface mechanism of FIGS. 8-10 and clearly observed in FIG. 10,
during each roll (spin) cycle of the round, the control surfaces
are deployed and retracted once. This means that the control
surface driving cams have to rotate at the same speed as the round
spin rate. However, by providing multiple deploy/retract profiles
on the control surface retract/deploy cams, the required speed of
the cams can be proportionally reduced. For example, by providing
three such deploy/retract profiles on the control surface
retract/deploy cams, the required rotational speed of the cam will
be reduced by a factor of three, thereby making the mechanism
suitable for higher spin rate munitions. It is noted that the
function of the gearbox is to lower the required motor speed.
Therefore at relatively low spin rates (order of 40-50 Hz), the
gearbox can be eliminated and the cams can be driven directly by
the control surface driving motor.
[0094] It is noted that different implementations of the basic
intermittently deployed control surface actuation devices shown in
FIGS. 8-10 are possible and optimal for different caliber munitions
and spin rate. The preliminary design shown in FIGS. 8-10 is
developed for 81 mm rounds and can therefore be readily scaled up
to larger caliber munitions or down to medium caliber munitions.
This design concept allows for longer control surfaces and due to
its mode of operation, it can be readily adapted for use in medium
caliber spinning rounds. Two such modified versions of the
intermittently deployed control surface actuation devices, one more
suitable for larger caliber and one more suitable for medium
caliber rounds are presented next.
b.1) First Alternative Cam-Operated Intermittently Deploying
Control Surface Mechanism
[0095] In this alternative cam operated mechanism for
intermittently deploying control surfaces, all features of the
design are identical to those of the preliminary design shown in
FIGS. 8-10, except for the design of its deployment and retraction
cam mechanism which is shown in FIGS. 11 and 12. In the side view
of FIG. 11 (left), the control surface deploying and retracting cam
disc is shown to be provided with a single pair of "control surface
cams", which in this configuration is positioned between the
control surface lever "followers", forcing them into retracted
configuration. Then as the cam disc driving motor rotates the cam
disc further, the pair of "control surface cams" (right) are
rotated out of engagement with the said control surface lever
"followers", and the control surface deploying spring (FIG. 9)
would rapidly deploy the control surfaces as shown in the side view
of FIG. 12. The control pitch angle adjustment mechanism is
identical to the concept presented in FIG. 8.
[0096] In the isometric view of FIG. 11 (right), the cam disc is
provided with three pairs of "control surface cams". By using such
a cam disc instead of the its one cam pair of version of FIG. 11
(left), during each three cycles of spin, the cam disc has to
rotate only once. This means that the cam disc driving motor speed
would need to be one-third of that of the round spin rate.
Obviously by increasing the number of pairs of "control surface
cams", the required rotary speed of the cam disc and its driving
electric motor can be proportionally further reduced.
b.2) Second Alternative Cam-Operated Intermittently Deploying
Control Surface Mechanism
[0097] In this alternative cam operated mechanism for
intermittently deploying control surfaces, all features of the
design are identical to those of the preliminary design shown in
FIGS. 8-10, except for the design of the deployment and retraction
cam mechanism. This control surface deployment and retraction
mechanism is shown in FIGS. 13 and 14.
[0098] In the side view of FIG. 13 (left), the control surface
deploying and retracting cam disc is shown to be provided with a
single pair of "control surface cams", which in this configuration
is shown to be positioned 90 degrees away from the control surface
lever "followers". In this design concept, the "control surface
deploying cams" provide the means to deploy retracted control
surfaces as shown in FIG. 14. Here as the cam disc driving motor
rotates the cam disc further, the pair of "control surface
deploying cams" engage the control surface lever followers, and
cause them to rotate and deploy the control surfaces. In this
design, the control surface deploying spring of FIG. 9 has the
function of providing the required retracting forces.
[0099] In FIG. 13 (right), the cam disc is shown with two pairs of
"control surface cams". By using such a cam disc instead of the one
with only one pair of "control surface cams" shown in the side view
of FIG. 13 (left), during each two cycles of round spin, the cam
disc has to rotate only once. This means that the cam disc driving
motor speed would need to be one-half of that of the round spin
rate. Obviously by increasing the number of pairs of "control
surface cams", the required rotary speed of the cam disc and its
driving electric motor can be proportionally further reduced. The
pitch angle varying mechanism is identical to the concept of FIG.
8.
c) Cam-Mechanism Operated Intermittently Deploying Control Surface
Concept
[0100] The basic design of this intermittently deployed control
surface based actuation device for high spin rounds is shown in the
frontal view of FIG. 15. In this design concept, the deploying
control surfaces are driven by a four-bar linkage mechanism. The
mechanism of keeping the control surfaces oriented for parallel
motion as the round rolls is as shown in FIG. 4 is not shown but is
designed to rotate the control surfaces which are hinged to the
coupler link via a cam fixed to one of the grounded links. The
pitch control is also achieved using a mechanism similar to the
mechanism shown in either FIG. 4 or FIG. 8. One control surface
deployment mechanism assembly is used for each control surface.
[0101] It is noted that in this design concept, the planetary gear
and driving motor assembly is connected to the round structure. In
addition, the control surfaces are deployed from the same site at
all times, thereby the size of the opening on the round becomes
small. In the concept of FIG. 15, each planetary gear rotated cam
is used to push against the indicated follower mounted on the
indicated mechanism link. The resulting "outward" rotation of the
link will then deploy the control surface while the round is at the
desired roll angle. The retraction of the link is achieved by the
pulling of the provided preloaded tensile springs (not shown for
clarity).
[0102] One of the main advantages of this concept is that the
deploying cam profile can be designed to work with the selected
gear ratio of the planetary gear such that after several full spin
cycles the control surfaces are deployed only once. Such a design
makes it possible to accommodate very high spin rates. For example,
if the mechanism is designed to deploy and retract the control
surfaces once every four full spin cycles of the round, then the
deployment and retraction drive has to run at one-fourth of the
spin rate. For example, if the round is spinning at 200 Hz, then
the electric motor driving the control surface deployment and
retraction system has to operate at 50 Hz, which is considerably
easier to achieve.
[0103] In the present feasibility study, such a control surface
deployment and retraction mechanism was designed in which during
four full spin cycle of the round the control surfaces are deployed
only once. The control surface deployment cam and its planetary
gearing is shown in FIG. 16. The driving motor is considered to be
driving at one-fourth the spin rate and is driving the planetary
gear arm. The triangular marking on the planetary gear arm (yellow)
shows its orientation relative to an observer on the ground. In
FIG. 16 and in the position (a), the planetary gear arm is shown to
be positioned with its triangular marking pointing to the left.
Then after one full spin cycle of the round (i.e., after the round
has rolled 360 degrees), the planetary gear arm rotation at
one-fourth of the spin rate has turned 90 degrees as shown in the
view (b). At this point, the cam has been retracted (from the
control surface deployed position shown in FIG. 15--i.e., from view
(a) in FIG. 16). After a second full spin cycle of the round, the
planetary gear arm has rotated 180 degrees, view (c), and after
another full spin cycle, the planetary gear arm has rotated 270
degrees, view (d). Then during the next spin cycle of the round, at
some point the cam will begin to deploy the control surface,
reaching at its full deployed position after the first full
rotation of the planetary gear arm has been completed as shown in
the view (e). The control surface will then begin to be retracted
as the round begins to undergo its next full cycle.
d) Fixed Gear with Driven Platform with a Double-Gear Train Control
Surface Deployment and Retraction Mechanism
[0104] The basic design of this intermittently deployed control
surface based actuation device for guidance and control of high
spin rounds is shown in the frontal view of FIG. 17. In this design
concept, the deploying and retracting control surfaces are attached
to the outer gears (pinions) that are mounted on a motor driven
gear platform. The control surface pinions are engaged with the
main gear via idler gears as shown in FIG. 17. The main gear is
fixed to the round and as a result with the selected gear ratios,
the control surfaces always exit from the provided openings in the
round shell. In this section, the mechanism of keeping the control
surfaces oriented to undergo parallel motion as the round rolls as
shown in FIG. 4 is not shown for the sake of saving space but is
designed to rotate the control surfaces which are hinged to the
outer pinions via cams driven by the idler gears. The pitch control
is also achieved using a mechanism similar to the mechanism shown
in either FIG. 4 or FIG. 8.
[0105] There are two features of this concept that makes it
suitable for high spin round applications. Firstly, since the main
gear is fixed to the round, with proper gear ratios, the control
surfaces deploy at the same location on the round, requiring small
openings for deployment. Secondly, similar to the previous section,
with properly selected gear ratios, after several full spin cycles
of the round, the control surfaces are deployed only once. Such a
design will similarly make it possible for the present mechanism to
accommodate very high spin rates.
[0106] In the present feasibility study, the gear ratio of the
control surface deployment and retraction mechanism was selected
for control surfaces to deploy once during each two spin cycle of
the round. The control surface deployment cycle during one full
cycle of spin is shown in FIG. 18. The driving motor is considered
to be driving the gear platform at half the spin rate. The
triangular markings on the main gear and the gear platform show
their relative position.
[0107] In FIG. 18 and in the position (a), the gear platform, the
round (and its attached main gear) are shown in their indicated
positioned by triangular marking, all pointing upwards. Then after
90 degrees of spin shown in the view (b), the control surfaces are
withdrawn and the gear platform has been rotated 45 degrees
relative to the main gear (and round). After 180 degrees rotation
of the round, view (c), the gear platform has rotated only 90
degrees relative to the main gear. After 270 and full roll of the
round shown in views (d) and (e), the gear platform is shown to
have rotated 135 and 180 degrees, respectively. As a result, during
one full spin cycle, the gear platform and its driving motor has
made only half a turn. It is noted that the control surface
orienting cam will prevent deployment of views (c)-(d), thereby
ensuring that during each two full spin cycle of the round, the
control surfaces are deployed and retracted only once.
e) Gear Driven Mechanism with Round-Fixed Pinions for Control
Surface Deployment and Retraction
[0108] The basic design of this intermittently deployed control
surface based actuation device for guidance and control of high
spin rounds is shown in the frontal view of FIG. 19. In this design
concept, the deploying and retracting control surfaces are attached
to the gears (pinions) that are mounted onto the round structure,
thereby ensuring that the control surfaces deploy through the same
opening area of the round at all times. The control surface pinions
are engaged with the main gear which is driven by a motor attached
to the round structure. The gear ratio between the main gear and
the pinions determines the number control surface deployment per
cycles of round spin. In the example shown in FIG. 19, the gear
ratio results in one cycle of control surface deployment per four
cycles of round spin. As a result, the main gear has to be driven
at one-fourth of the spin rate. Here, the mechanism of keeping the
control surfaces oriented to undergo parallel motion as the round
rolls as shown in FIG. 4 is not shown for saving space but is
designed to rotate the control surfaces which are hinged to the
pinions via cams also driven by the main gear. The pitch control is
also achieved using a mechanism similar to the mechanism shown in
either FIG. 4 or FIG. 8.
[0109] This concept also enjoys the two features of the previous
concept, making it suitable for high spin round applications.
Firstly, since the control surface gear is fixed to the round, the
control surfaces always deploy at the same location on the round,
thereby requiring small openings for control surface deployment.
Secondly, by proper selection of the gear ratio, after several full
spin cycles of the round, the control surfaces are deployed only
once. Such a design will similarly make it possible for the present
mechanism to accommodate very high spin rates.
[0110] In the present feasibility study, the gear ratio of the
control surface deployment and retraction mechanism was selected
such that the control surfaces are deployed once every four spin
cycles. The control surface deployment cycle during one full cycle
of spin is shown in FIG. 20. The driving motor is driving the main
gear at one-fourth of the spin rate. The triangular marking on the
main gear and the round show their relative position as the round
rolls.
[0111] In FIG. 20, position (a), the main gear and the round are in
the positions indicated by the triangular marking (pointing
upwards). Then after 90 degrees of spin, view (b), the control
surfaces are withdrawn and the main gear has rotated 22.5 degrees
relative to the round. After 180 degrees rotation of the round,
view (c), the main gear has rotated 45 degrees relative to the
round. After 270 and full roll of the round shown in views (d) and
(e), respectively, the main gear is shown to have rotated 67.5 and
90 degrees, respectively. As a result, during one full spin cycle,
the main gear and its driving motor have rotated only 90 degrees or
one quarter of a turn.
1.1.3. Novel Intermittently Deployable Drag Element Concepts for
Guidance and Control
[0112] The intermittent control surface deployment mechanisms
described in the previous section may also be used to deploy
drag-based control elements in place of commonly used solenoids and
voice coil motors with orders of magnitude increase in efficiency
and dynamic response as well as with orders of magnitude reduction
in power consumption due to the use of continuously rotating and
balanced electric motors.
[0113] In general, only a single such drag deploying mechanism is
needed in a round since it can be deployed at the required roll
during each and every spin cycle or after one or more spin cycles
depending on the design of the drag element and the amount of drag
that it produces during each deployment. The shape and size and
duration is dependent on the spin rate and size of the round and
the amount of diverting drag force that is desired to be
generated.
[0114] It is noted that as was described in the introduction
section, drag element deployment based actuation guidance and
control is generally not highly desirable for most munitions since
it decreases the munitions range. However, in those applications in
which the reduction in the range can be tolerated, then the methods
and concepts described in Section 1.3.2 may be used in place of the
currently used methods to achieve highly efficient and low power
drag based guidance and control action for high spin rounds.
1.2. The Novel Roll Angle Measurement Sensor
[0115] Omnitek has developed polarized RF angular orientation
sensors.sup.3 constructed with geometrical cavities that operate
with scanning polarized RF reference sources in a configuration
shown in FIG. 21. In this sensory system, a polarized RF reference
source transmits electromagnetic waves with polarization planes
parallel to the Y.sub.refZ.sub.ref plane of the reference
coordinate system X.sub.refY.sub.refZ.sub.ref, FIG. 21. When the
reference source is used to scan a prescribed pattern, the measured
signal at the sensor cavity positioned, for example, on the base of
the projectile, and the pattern of the signal provides the actual
roll angle orientation of the sensor relative to the reference
source onboard munitions (see indicated patents for detail). .sup.3
U.S. Pat. Nos. 8,587,473; 8,259,292; 8,258,999; 8,164,745;
8,093,539; 8,076,621 and 7,425,918 and others pending.
[0116] Through modeling and computer simulation, anechoic chamber
and range tests, Omnitek has shown that such a polarized RF sensory
system allows the roll angle of high-spin rounds to be measured
with high precision directly onboard munitions in line-of-sight as
well as non-line-of-sight conditions. In general, due to symmetry
in the propagated electromagnetic wave, "up and down" of the
rolling projectile orientation cannot be differentiated. This issue
can be readily resolved for spinning rounds as described
below.sup.4. .sup.4 Omnitek Partners, LLC U.S. Pat. No.
8,587,473.
[0117] In the simplest concept, a polarized RF reference source
transmits electromagnetic waves with polarization planes parallel
to the Y.sub.refZ.sub.ref (i.e., the horizontal) plane of the
Cartesian reference coordinate system X.sub.refY.sub.refZ.sub.ref
shown in FIG. 21. Two identical polarized RF cavity sensors are
embedded into the projectile at angles .beta..sub.1 and
.beta..sub.2 as shown in FIG. 22. Each one of the sensors can be
used to measure the roll angle with an appropriately patterned
scanning reference source, but without being able to differentiate
"up and down" as previously indicated. However, since the reference
source is on the ground, by making the angles .beta..sub.1 and
.beta..sub.2 significantly different, at each of their horizontal
roll angle positioning, the one that is more closely lined up with
the direction of the reference source will receive larger amplitude
signals. By comparing the relative amplitudes of the received
signals, up and down orientation of the round in roll is thereby
differentiated. In addition, since the actual angles .beta..sub.1
and .beta..sub.2 are known, the difference between the (average)
magnitudes of the two measured signals would provide an indication
of the projectile pitch angle.
[0118] As part of the proposed efforts, methods for optimal design
of the proposed roll angle sensors and roll angle measurement
algorithms will also be developed. Prototypes will be fabricated
and tested in anechoic chamber and in range testing with
instrumented spinning round models and will be readied together
with its electronics for insertion and testing in selected
munitions models.
1.3. Pulsed Actuation Impulse Magnitude and Dynamic Response
[0119] The proposed actuations concepts, including the multi-stage
slug-shot; multi-stage impulse thruster; and the intermittently
deployed control surface actuation device concepts provide pulsed
control action with very high dynamic response characteristics.
[0120] The multi-stage slug-shot and the multi-stage impulse
thruster based control action producing devices for guidance and
control of munitions are impulse producing actuation devices which
are based on detonation of small charges that are initiated with
highly reliable electrical initiators. The electrical initiators to
be used for this purpose were developed by Omnitek jointly with ARL
and have been shown to be capable of providing detonation within
20-50 microseconds, thereby making them suitable for high spin
munitions applications. Omnitek slug-shot impulse actuation
providing around 10 N-sec with sub-millisecond durations have been
designed and tested and with higher energy explosive charges are
expected to provide significantly larger impulse and shorter
duration, thereby considering that several of these impulses can be
provided per second during each revolution of the munitions, it is
obvious that these multi-stage pulsed actuation devices can readily
be sized to provide the required impulses in the range of 10 N-sec
to 140 N-sec. The multi-stage slug-shot and the multi-stage impulse
thruster based control actions are suitable mainly for terminal
guidance applications due to the limited number of units that can
be provided on each round.
[0121] The intermittently deployed control surface based control
actions for guidance and control of munitions can be readily sized
to provide equivalent of 10-140 N-sec impulse levels and even
significantly higher equivalent impulse levels for control action,
particularly by providing them as canards. The quasi-continuous
control action provided by such actuation concepts can be used a
portion or the entire flight. The control action is also readily
varied by varying the control surface pitch. The control surface
based control actions are particularly suitable for longer range
munitions since they would minimally affect range.
[0122] As it was previously discussed in Section 1.3.3, the
mechanisms used to intermittently deploy control surfaces can also
be used to deploy drag elements to produce control action. In
general, drag based control action would cause the munitions range
to be reduced. However, in applications that such effects can be
tolerated, one may also use the developed concepts to generate
drag-based control action. In such applications, the pitch control
mechanism may be used to vary the level of generated drag.
[0123] While there has been shown and described what is considered
to be preferred embodiments of the invention, it will, of course,
be understood that various modifications and changes in form or
detail could readily be made without departing from the spirit of
the invention. It is therefore intended that the invention be not
limited to the exact forms described and illustrated, but should be
constructed to cover all modifications that may fall within the
scope of the appended claims.
* * * * *