ELECTROMAGNETIC INERTIAL ACTUATOR
CROSS-REFERENCE TO RELATED APPLICATIONS
[OOO 1 ] This application claims priority to PCT International Application Serial No.
PCT/US2009/063193, filed November 4, 2009, which the priority is herein claimed,
and herein incorporated by reference.
FIELD
[OOO2] The present invention relates generally to active vibration control devices
and more specifically to inertial actuators.
BACKGROUND
[0003] Inertial actuators are used to actively control vibrations of a structure, e.g.,
an aircraft fuselage. An inertial actuator is attached to the structure whose vibrations
are to be controlled and operated to impart a force on the structure that counteracts
the vibrations of the structure. Sensors may be attached to the structure to measure
vibrations of the structure. The output of the sensors may be used to control the
inertial actuator to generate the force required to counteract the vibrations of the
structure. Inertial actuators are based on the principle that accelerating a suspended
mass results in a reaction force on the supporting structure. An inertial actuator
includes a mass that is connected to a rigid supporting structure by means of a
compliant spring. Force is applied to the mass to accelerate the mass and thereby
produce the reaction force on the supporting structure. The inertial actuator behaves
as a force generator for frequencies above its suspension frequency. Typical inertial
actuators are electromagnetic, electrodynamic, or piezoelectric actuators. The
present invention relates to electromagnetic inertial actuators.
[0004] U.S. Patent Number 7,288,861 (the '861 patent) discloses an
electromagnetic inertial actuator for active vibration control that uses a cylindrical
voice coil motor. In the '861 patent, a moving armature is suspended above a base
by an array of flexure stacks. The array of flexure stacks is coupled at its center to
the moving armature and at its ends to the top ends of vertical support flexures. The
lower ends of the vertical support flexures are fastened to the base. The moving
armature includes a tubular shell sleeve coaxially surrounding a cylindrical core,
which is made of two permanent magnets and corresponding pole plates. A soft iron
shell yoke plate attached to one of the magnets and the top end of the tubular shell
sleeve magnetically and mechanically links the cylindrical core to the tubular shell
sleeve. The two permanent magnets provide two magnetically-charged annular gaps
between the pole plates and the inner wall of the tubular shell sleeve. Two voice
coils, mounted on the base, are centered in the annular gaps. When the coils are
energized, the windings in the coils interact with the magnetic flux in the annular
gaps to vibrate the moving armature in a vertical direction as enabled by flexing of
the flexure stacks and vertical support flexures.
[0005] U.S. Patent Number 7,550,880 (the '880 patent) discloses a folded flexure
system for cylindrical voice coil motors. The folded flexure system may be
implemented in one or more tiers, with each tier of the folded flexure system
comprising two or more triad array members. Quad array members are also
disclosed. Each triad array member includes three compliant span elements-the
two outer span elements are half-width while the central span element is full width.
In one disclosed embodiment, the outer span elements are attached to the armature
shell of a voice coil motor at one end and to a yokelidler fastening at another end.
The central span element is attached to a pedestal of the base at one end and to a
yokelidler fastening at another end. A permanent magnet within the armature shell
sets up a magnetically charged annular gap between its circular pole piece and the
inner wall of the armature shell. A coillbobbin assembly attached to the base
supports a coil in the annular magnetically charged gap. As in the '861 patent, when
the coil is energized, the windings in the coil interact with the magnetic flux in the air
gap to exert force that drives the armature mass along a vertical stroke axis. The
vertical motion of the armature mass is enabled by symmetrical flexing of the folded
flexure system.
SUMMARY
[0006] In a first aspect of the invention, an electromagnetic inertial actuator
includes a support part and a parallel arrangement of a first flexure part, a voice coil
motor part, and a second flexure part, where the parallel arrangement is cantilevered
from the support part.
[0007] In a second aspect of the invention, an aircraft has an aircraft structure
and a plurality of troublesome vibrations. The aircraft includes an electromagnetic
inertial actuator support part, which is physically grounded to the aircraft structure.
The aircraft further includes an electromagnetic inertial actuator parallel arrangement
of a first flexure part, a voice coil motor part, and a second flexure part, where the
electromagnetic inertial actuator parallel arrangement is cantilevered from the
electromagnetic inertial actuator support part.
[0008] In a third aspect of the invention, a method for controlling troublesome
aircraft vibrations of an aircraft includes providing an electromagnetic inertial
actuator, which includes a support part and a parallel arrangement of a first flexure
part, a voice coil motor part, and a second flexure part, where the parallel
arrangement is cantilevered from the support. The method further includes
physically grounding the support part to an aircraft structure of the aircraft and
electromagnetically driving the electromagnetic inertial actuator, wherein the parallel
arrangement traces an arc relative to the support part.
[0009] In an embodiment the invention includes a method of making an
electromagnetic actuator including providing a base, providing a coil, grounding the
coil with the base, providing a parallel arrangement of flexures and a voice coil
motor, and cantilevering the parallel arrangement from the base.
[OO 1 01 These aspects and certain embodiments of the present invention will be
described in more detail below.
BRIEF DESCRIPTION OF DRAWINGS
[OOI I ] The following is a description of the figures in the accompanying drawings.
The figures are not necessarily to scale, and certain features and certain views of
the figures may be shown exaggerated in scale or in schematic in the interest of
clarity and conciseness.
[OO 1 21 FIG. 1 is a perspective view of an electromagnetic inertial actuator.
[OO 1 31 FIG. 2 is a perspective view of a bottom half of the electromagnetic inertial
actuator shown in FIG. 1.
[OO 1 41 FIG. 3 is a perspective view of a flat voice coil motor.
[OO 1 51 FIG. 4 is a rear view of the flat voice coil motor shown in FIG. 3.
[OO 1 61 FIG. 5 is a perspective view of a left half of the flat voice coil motor shown
in FIG. 3.
[OOI 71 FIG. 6 shows the electromagnetic inertial actuator with the flat voice coil
motor in a down position.
[OO 1 81 FIG. 7 shows the electromagnetic inertial actuator with the flat voice coil
motor in an up position.
[OO 1 91 FIG. 8 shows magnetic flux in the flat voice coil motor.
[0020] FIG. 9 is a plot showing force generated by the flat voice coil motor versus
stroke of the motor.
[OO2 1 ] FIG. 10 is a perspective view of a flexure stack.
[0022] FIGS. 11A-11 N show voice coillmagnet arrangements for a voice coil
motor of an electromagnetic inertial actuator.
[0023] FIG. 12 shows an aircraft including a vibration control system.
[0024] FIG. 13 is a perspective view of a variant of the electromagnetic inertial
actuator shown in FIG. 1.
[0025] FIG. 14 is a perspective view of a variant of the electromagnetic inertial
actuator shown in FIG. 1.
DETAILED DESCRIPTION
[0026] In the following detailed description, numerous specific details may be set
forth in order to provide a thorough understanding of embodiments of the invention.
However, it will be clear to one skilled in the art when embodiments of the invention
may be practiced without some or all of these specific details. In other instances,
well-known features or processes may not be described in detail so as not to
unnecessarily obscure the invention. In addition, like or identical reference numerals
may be used to identify common or similar elements.
[0027] FIG. 1 shows an electromagnetic inertial actuator 1 according to one
aspect of the present invention. The electromagnetic inertial actuator 1 includes a
support base 3, which has an attachment plate 2 and mounting base 4. The
attachment plate 2 may be integrally formed or otherwise attached to the mounting
base 4. The bottom of the mounting base 4 can be attached to a structure, such as
an aircraft structure, e.g., by bolts or other suitable attachment means. The
electromagnetic inertial actuator 1 also includes a parallel arrangement 5 of a first
flexure part 7, a voice coil motor part 9, and a second flexure part 11. A "voice coil
motor" is a positioning device that uses a coil of wire in a permanent magnetic field.
In the parallel arrangement 5, the first flexure part 7 is spaced apart from the second
flexure part 11, and the voice coil motor part 9 is disposed in the space between the
flexure parts 7, 11. The parallel arrangement 5 is cantilevered from the support base
3, i.e., the flexure parts 7, 11 and the voice coil motor part 9 extend outward from the
support base 3 in the manner of a cantilever. The ends 8, 12 of the flexure parts 7,
11, respectively, which are coupled to the support base 3, are the fixed or supported
ends of the flexure parts 7, 11. The ends 10, 14 of the flexure parts 7, 11,
respectively, which are unattached to the support base 3, are the moving or
unsupported ends of the flexure parts 7, 11. The unsupported ends 10, 14 of the
flexure parts 7, 11, respectively, are coupled to a magnet part 13 of the voice coil
motor part 9. In addition to the magnet part 13, the voice coil motor 9 also includes
an interacting driving coil part (15 in FIGS. 2, 3). The interacting driving coil part (15
in FIGS. 2, 3) is preferably physically grounded to the support base 3, with the
interacting driving coil part (15 in FIGS. 2, 3) being physically separated from the
magnet part 13 and its associated cantilevered flexure-supported members,
preferably with an air space gap. In the spring-mass actuator system, the
cantilevered flexure-supported magnet part 13 and its associated cantilevered
flexure-supported moving mass members represent a sprung moving mass, and the
flexure parts 7, 11 represent a spring. The magnet part 13 creates a magnetic field.
When alternating current is supplied to the physically grounded non-sprung, nonmoving
coil part 15, the coil part 15 interacts with the magnetic field created by the
sprung moving mass magnet part 13 to generate an electromagnetic driving force
that vibrates the cantilevered flexure-supported sprung moving mass magnet part
13. The sprung moving mass magnet part 13 moves in an arc as it is
electromagnetically driven (i.e., moves up and down along a vertical direction in
relation to the support base 3 (and the grounded coil 15) and in and out relative to
the support base 3 at the same time to trace an arc). If the frequency of the
alternating current supplied to the coil part (15 in FIGS. 2, 3) is the same as the
natural frequency of the spring-mass system, the excursions of the magnet part 13
can become quite large. The larger the excursions, the higher the output force of the
electromagnetic inertial actuator 1.
[0028] FIG. 2 shows a cut through the electromagnetic inertial actuator 1, which
allows a view of the interior of the voice coil motor part 9. In the embodiment shown
in FIG. 2, the voice coil motor part 9 is a rectangular voice coil motor. The magnet
part 13 includes permanent magnets 17, 19, 21, 23. Each of the permanent magnets
17, 19, 21, 23 is flat (planar) and has a rectangular cross-section. In the embodiment
of FIG. 2, the magnet part 13 has four permanent magnets. In alternate
embodiments, the magnet part 13 could have more or fewer permanent magnets (as
will be shown below with reference to FIGS. 11A-11 N). In general, the four magnets
provide a good balance between weight and magnetic gauss field. The permanent
magnets 17, 19, 21, 23 are in a parallel arrangement with each other and are
spaced apart. Referring to FIG. 3, a gap 25 is defined between the adjacent
permanent magnets 17, 19, and a gap 27 is defined between the adjacent
permanent magnets 21, 23. A vertical plate 31 made of ferromagnetic material, such
as low carbon steel, is disposed between the permanent magnets 19, 21. Vertical
plates 33, 35 made of ferromagnetic material are also disposed adjacent to the
permanent magnets 17, 23. In FIG. 3, horizontal plates 37, 39 made of
ferromagnetic material are disposed adjacent to the tops and bottoms of the
permanent magnets 17, 19, 21, 23. In FIG. 3, the ferromagnetic plates 31, 33, 35,
37, 39 are secured together, e.g., by means of bolts, to form an enclosure around
the permanent magnets 17, 19, 21, 23 and thereby direct the magnetic flux path. In
alternate embodiments, the ferromagnetic plates 31, 33, 35, 37, 39 could be
integrated together, i.e., instead of being provided as separate pieces, into a unitary
housing. In FIG. 3, the permanent magnets 17, 19, 21, 23 are held firmly in place,
adjacent to the ferromagnetic plates 31, 33, 35, 37, 39, by friction. In alternate
embodiments, the permanent magnets could be bonded to the ferromagnetic plates
to thereby secure the permanent magnets in place.
[0029] Still referring to FIG. 3, the coil part 15 of the voice coil motor part 9
includes a coil 41 positioned in the gaps 25, 27. In the embodiment shown in FIG. 3,
the coil 41 is wound on a bobbin 43. The coil 41 is wound in an oval or rectangular
shape, as is best seen in FIG. 2. The coil 41 may be made of copper wire or other
suitable conducting wire material. In FIG. 4, the bobbin 43 has flanges 45 with holes
formed in them. The flanges 45 are used to attach the bobbin 43 to the support (3 in
FIGS. 1 and 2). In FIG. 2, the bolts 46 indicate where the bobbin 43 is attached to
the support base 3. Other techniques for attaching the bobbin 43 to the support base
3 besides bolts and flanges may be used. In general, the bobbin 43 should be
attached to the support base 3 such that it is cantilevered from the support base 3
and in parallel arrangement with the flexure parts 7, 11. In alternate embodiments,
the bobbin 43 may be omitted and the coil 41 may be wound into the desired shape
without the aid of a bobbin. In this case, the coil 41 will be free to move in the gaps
25, 27. In FIG. 2, it should be noted that there is an adjustable gap 47 between the
distal ends of the coil 43 and magnet part 13. The gap 47 allows the magnet part 13
to move curvilinearly relative to the support base 3, preferably tracing an arc from
the combination of a vertical movement and an axial in-and-out movement.
Preferably, the electromagnetic inertial actuator curvilinearly arcing moving mass is
electromagnetically driven to move curvilinearly to trace out an arc. Also, in FIG. 2,
a yoke (i.e., a frame that couples together) 49 is coupled to the magnet part 13. For
example, such coupling could include bolting the yoke 49 to the ferromagnetic plates
33, 35. Other means of coupling the yoke 49 to the magnet part 13 could be used
provided the integrity of the coupling remains intact as the magnet part 13 moves.
[0030] FIG. 5 shows a cut through the voice coil motor part 9. In FIG. 5, B
indicates the magnetic field created by the magnets 17, 19, 21, 23 in the gaps 25,
27. When alternating current i is supplied to the coil 41, the windings in the coil 41
interact with the magnetic field B in the gaps to exert a force f that drives (moves)
the magnet part 13. Returning to FIG. 1, the flexure parts 7, 9 coupled to the magnet
part 13 allow motion of the magnet part 13 along a vertical direction. Because of the
cantilevered arrangement of the flexure parts 7, 9, the magnet part 13 moves in and
out along an axial direction as it moves up and down along the vertical direction,
thereby providing a curvilinear moving mass trace, preferably tracing an arc. FIG. 6
shows the magnet part 13 in a down position, with the flexure parts 7, 11 deflected
downwardly. FIG. 7 shows the magnet part 13 in an up position, with the flexure
parts 7, 11 deflected upwardly. The magnet part 13 moves in and out along the axial
direction as it moves up and down along the vertical direction. As explained above,
there is a gap (47 in FIG. 2) between the magnet part 13 and the coil (41 in FIG. 2)
to accommodate axial motion of the magnet part 13 relative to the support base 3.
FIG. 8 shows magnetic flux path in the ferromagnetic plates 31, 33, 35, 37, 39 when
the windings in the coil 41 interact with the magnetic field created in the gaps 25, 27
by the permanent magnets 17, 19, 21, 23. FIG. 9 shows an example plot of force
generated by the motor as a function of stroke of the motor. FIG. 9 shows that the
force generated by the voice coil motor as described above is essentially linear, with
very small force reduction at the ends of the stroke. In use, the force generated by
the voice coil motor is transmitted to the support (3 in FIG. 1). If the support is
attached to a structure, the force transmitted to the support can be used to
counteract vibrations of the structure.
[003 1 ] Returning to FIG. 1, each of the flexure parts 7, 11 is made up of two
flexure stacks 50. In alternate embodiments, more or fewer flexure stacks may be
included in each of the flexure parts 7, 11. FIG. 10 shows a flexure stack 50
according to one embodiment of the present invention. In the embodiment of FIG.
10, the flexure stack 50 includes flexures 52 interleaved with shims 54. In a
preferred embodiment the shims 54 are proximate the ends of the flexures 52 and
do not extend along the flexure length with the middle of the stacks 50 free of the
shims 54 (relatively short shims preferably bonded proximate ends of flexures and
clamps 58 and do not extend the full length of the flexures through the mid-region of
the flexure). Each flexure 52 is in the form of a beam plate. The flexures 52 may be
made of a non-elastomeric material, which may be metallic, non-metallic, or
composite. Preferably, the flexures 52 are made of a composite or non-metallic
material. In one embodiment, a composite material suitable for the flexures is
comprised of reinforcing fibers in a polymer resin. In another embodiment, a
composite material suitable for the flexures is comprised of a carbon-fiber reinforced
composite. In another embodiment, the carbon-fiber reinforced composite is
comprised of carbon fibers in a cured polymer matrix. In another embodiment, the
carbon-reinforced fiber composite is comprised of carbon fibers in a cured epoxy
matrix. The shims 54 could be made of metal or elastomer, with elastomer being
preferred. In a preferred embodiment the elastomeric material for the shims is postvulcanized
rubber. The shims 54 in a preferred embodiment are bonded to the
flexures 54 proximate their ends and the clamps 58, with the shims inhibiting a
fretting of the flexures as they move with the stroke of the voice coil motor.
Preferably the bonded elastomeric shims 54 are provided to inhibit a fretting of the
flexures 54.
[0032] The distal ends of the flexure stack 50 are inserted into apertures 56 in
flexure clamps 58 and held in the apertures 56, e.g., by friction. The flexure clamps
58 have a double row bolt arrangement 60 (i.e., two rows of bolts, with the rows
positioned on opposite sides of the clamps), and with this arrangement the flexure
stack 50 can be firmly attached to the bracket (49 in FIG. I ) and the vertical support
(3 in FIG. 1). The double row bolt arrangement (60 in FIG. 10) improves the clamp
stiffness and reduces the moment loads on the bolts (of the double row bolt
arrangement) when the clamp 58 is secured to the bracket or vertical support.
Returning to FIG. 1, the flexure stacks 50 span the full length of the inertial actuator
1, thereby allowing large strokes of the voice coil motor part 9. Large strokes result
in large output forces of the actuator. The flexure stacks 50 are very stiff in five
directions (lateral, longitudinal, and three rotations) but flexible in the vertical
direction, allowing curvilinear movement of the magnet part 13 of the voice coil
motor part 9. The cantilevered arrangement of the flexure parts 7, 11 and voice coil
motor part 9 retains the parallel orientation of the voice coil motor part 9 relative to
the flexure parts 7, 11 throughout the stroke of the voice coil motor part 9.
[0033] FIGS. 11A-11 N show various examples voice coillmagnet arrangements
usable in the voice coil motor part (9 in FIG. 1) of the electromagnetic inertial
actuator (1 in FIG. 1). Each of these arrangements includes a ferromagnetic housing
34, or a plurality of ferromagnetic plates 34, defining a gap or a plurality of parallel
gaps. Each of these arrangements further includes one or more permanent magnets
36 disposed in gap(s) and one or more coils 38 disposed adjacent to the permanent
magnet(s) 36. The coils 38 are typically annular or rectangular in shape as described
above. Multiple coils 38 may be used in a stacked arrangement, such as shown in
FIGS. 1 1 K-11 N. The arrangement shown in FIG. 1 1 A is similar to the one described
above with reference to FIGS. 5 and 8.
[0034] FIG. 12 shows an aircraft 61 having a rotary wing system with at least one
rotating blade rotating about a rotation axis. In use, the rotary wing system
generates troublesome structural vibrations. A vibration control system for the
aircraft 61 includes one or more vibration sensors 63 (e.g., accelerometers) mounted
on the aircraft to sense the troublesome structural vibrations. The vibration control
system also includes one or more electromagnetic inertial actuators 1 cantilevermounted
on the aircraft 61. The vibration control system also includes a controller
65. The controller 65 is shown outside of the aircraft for illustration purposes only. In
practice, the controller 65 would be on-board the aircraft. The controller 65 receives
signals from the vibration sensor(s) 63 representative of the troublesome structural
vibrations. The controller 65 then sends signals to the electromagnetic inertial
actuators 1, instructing the electromagnetic inertial actuator(s) 1 to generate a force
that counteracts the troublesome structural vibrations. Preferably the controller
drives a plurality of electromagnetic inertial actuators with the actuators' sprung
moving mass magnet part 13 tracing curvilinear arcs relative to their support bases,
the support bases being physically grounded to the aircraft structure. Preferably the
actuators' sprung moving mass magnet part 13 are cantilevered sprung supported
with the composite flexures with the bonded elastomer end fret inhibiting shims.
[0035] FIG. 13 shows a variant 1A of the electromagnetic inertial actuator 1 of
FIG. 1. In FIG. 13, weights 70, e.g., made of a metal such as steel, are coupled to
the voice coil motor part 9. The weights 70 add mass to the sprung moving mass.
Mounting base 4A of the support base 3A shown in FIG. 13 is different from the
mounting base 4 shown in FIG. 1. The base 4A of FIG. 13 has ears or flanges 72
that allows mounting of the base 4A to a structure through a side of the base 4A. (In
comparison, the base 4 of FIG. 1 can be mounted to a structure through a bottom of
the base.) In FIG. 13, the flexure clamps 58A at the support base 3A are different
from the flexure clamps 58 at the support base 3 shown in FIG. 1. Each of the
flexure clamps 58A shown in FIG. 13 can receive ends of multiple flexure stacks.
The flexure clamps 58 shown in FIG. 1 can only receive one end of a single flexure
stack.
[0036] FIG. 14 shows a variant 1 B of the electromagnetic inertial actuator 1 of
FIG. 1. The variant 1 B differs from the embodiment shown in FIG. 1 primarily in
terms of the support base. In FIG. 14, the support base 3B includes parallel plates
74, 76. The flexure stacks 50 at one end are coupled to the parallel plate 76, via
attachment of the flexure clamps 58 to the parallel plate 76. The flexure stacks 50 at
the other end are free to move and are not coupled to the parallel plate 74. The
parallel plates 74, 76 are attached to a frame 78, thereby ensuring the rigidity of the
support base 3B. The parallel plates 74, 76 include ears or flanges 74A, 76A that
can be connected to a structure. The support base 3B allows the electromagnetic
inertial actuator 1 B to be mounted sideways to a structure. The cantilevered parallel
arrangement of the flexure stacks 50 and voice coil motor 9 is maintained by fixing
the arrangement to only one of the parallel plates, i.e., parallel plate 76.
[0037] While the invention has been described with respect to a limited number
of embodiments, those skilled in the art, having benefit of this disclosure, will
appreciate that other embodiments can be devised which do not depart from the
scope of the invention as disclosed herein. Accordingly, the scope of the invention
should be limited only by the attached claims.

What is claimed is:
1. An electromagnetic inertial actuator, comprising:
a support base; and
a parallel arrangement of a first flexure part, a voice coil motor part, and a
second flexure part, the parallel arrangement being cantilevered from the
support base.
2. The electromagnetic inertial actuator of claim 1, wherein the voice coil motor part
comprises a magnet part and a coil part, the magnet part comprising a plurality of
permanent magnets, the coil part comprising a coil.
3. The electromagnetic inertial actuator of claim 2, wherein each of the flexure parts
has opposing first and second ends, the first ends being coupled to the support
base, the second ends being coupled to the magnet part.
4. The electromagnetic inertial actuator of claim 3, wherein the magnet part further
comprises ferromagnetic material disposed adjacent to each of the permanent
magnets.
5. The electromagnetic inertial actuators of claim 4, wherein each of the permanent
magnets is flat.
6. The electromagnetic inertial actuator of claim 4, wherein each of the permanent
magnet has a rectangular or triangular cross-section.
7. The electromagnetic inertial actuator of claim 4, wherein the permanent magnets
define at least one gap for receiving the coil.
8. The electromagnetic inertial actuator of claim 7, wherein the permanent magnets
define two parallel gaps for receiving the coil.
9. The electromagnetic inertial actuator of claim 7, wherein distal ends of the
magnet part and coil define an adjustable gap to accommodate arc motion of the
parallel arrangement relative to the support base when the electromagnetic
inertial actuator is driven.
10. The electromagnetic inertial actuator of claim 7, wherein the first flexure part
comprises a first flexure stack and the second flexure part comprises a second
flexure stack.
11. The electromagnetic inertial actuator of claim 10, further comprising a first clamp
engaged with the first end of the first flexure stack and a second clamp engaged
with the first end of the second flexure stack, each of the first clamp and the
second clamp being attached to the support base at a plurality of points, thereby
coupling first ends of the first and second flexure parts to the support base.
12. The electromagnetic inertial actuator of claim 10, further comprising a yoke
coupled to the magnet part and to a second end of the first flexure stack and a
second end of the second flexure stack, thereby coupling second ends of the of
the flexure parts to the magnet part.
13. The electromagnetic inertial actuator of claim 12, further comprising a third clamp
engaged with the second end of the first flexure stack and a fourth clamp
engaged with the second end of the second flexure stack, each of the third clamp
and the fourth clamp being attached to the yoke at a plurality of points, thereby
coupling the second ends of the first and second flexure stacks to the yoke.
14. The electromagnetic inertial actuator of claim 13, wherein the first flexure part
comprises a plurality of first flexure stacks and the second flexure part
comprises a plurality of second flexure stacks with said yoke in between said first
flexure stacks and in between said second flexure stacks.
15. The electromagnetic inertial actuator of claim 10, wherein each of the first flexure
stack and second flexure stack comprises a plurality of flexures interleaved with
a plurality of shims.
16. The electromagnetic inertial actuator of claim 15, wherein the shims are bonded
elastomeric end shims.
17. The electromagnetic inertial actuator of claim 16, wherein the flexures are
composite flexures and the bonded elastomeric end shims are fret-inhibiting
shims..
18. The electromagnetic inertial actuator of claim 9, wherein the coil is physically
grounded to the support base.
19. An aircraft, said aircraft having an aircraft structure and a plurality of troublesome
structure vibrations, said aircraft including an electromagnetic inertial actuator
support base, said electromagnetic inertial actuator support base being
physically grounded to said aircraft structure, said aircraft comprising:
an electromagnetic inertial actuator parallel arrangement of a first flexure part, a
voice coil motor part, and a second flexure part, the parallel arrangement
being cantilevered from the electromagnetic inertial actuator support base.
20. The aircraft of claim 19, wherein said aircraft includes a rotary wing system with
at least one rotating blade rotating about a rotation axis, the rotary wing system
generating said troublesome structure vibrations
The aircraft of claim 19, wherein said aircraft includes a vibration sensor, said
vibration sensor sensing said troublesome structure vibrations, and inertial
actuator controller, said vibration sensor outputting vibration sensor signals to
said inertial actuator controller wherein said inertial actuator controller
electromagnetically drives said electromagnetic inertial actuator parallel
arrangement relative to an electromagnetic coil physically grounded to the
support base to minimize said troublesome structure vibrations sensed by said
vibration sensor.
22. The aircraft of claim 19, wherein the first flexure part comprises a plurality of first
flexure stacks and the second flexure part comprises a plurality of second flexure
stacks, each of the first flexure stack and second flexure stack comprises a
plurality of flexures interleaved with a plurality of shims.
23. The aircraft of claim 22, wherein the shims are bonded elastomeric end shims.
24. The aircraft of claim 23, wherein the flexures are composite flexures and said
bonded elastomeric end shims are fret-inhibiting shims.
25. The aircraft of claim 21, wherein the electromagnetic inertial actuator parallel
arrangement traces an arc relative to the electromagnetic inertial actuator
support base when driven the electromagnetic inertial actuator is driven.
26. A method for controlling troublesome aircraft vibrations of an aircraft, said
method including:
providing an electromagnetic inertial actuator, said electromagnetic inertial
actuator including a support base and a parallel arrangement of a first
flexure part, a voice coil motor part, and a second flexure part, the parallel
arrangement being cantilevered from the support base;
physically grounding said electromagnetic inertial actuator support base to an
aircraft structure of said aircraft; and
electromagnetically driving said electromagnetic inertial actuator wherein said
parallel arrangement traces an arc relative to said support base.
27. A method of making an electromagnetic inertial actuator, comprising:
proving a support base;
providing a coil part;
physically grounding said coil part with said support base;
providing a parallel arrangement of at least a first flexure part, and a voice coil
motor part; and
cantilevering said parallel arrangement from the support base.
28. The method of claim 27, wherein providing said voice coil motor part comprises
providing a magnet part comprising a plurality of permanent magnets and a coil
part comprising a coil.
29. The method of claim 28 , wherein said at least first flexure has opposing first and
second ends, the first ends being attached to the support base, the second ends
being coupled to the magnet part.
30. The method of claim 29, wherein the parallel arrangement is cantilevered such
that the parallel arrangement traces an arc relative to the support base when the
electromagnetic inertial actuator is driven.
31. The method of claim 30, wherein the distal ends of the magnet part and coil
define an adjustable gap to accommodate arc motion of the magnet part relative
to the support base.
32. The method of claim 29, wherein each of the permanent magnets is flat.
Dated this 1st day of June 2012.