EP0805984A4 - Coupled resonator vibratory rate sensor - Google Patents
Coupled resonator vibratory rate sensorInfo
- Publication number
- EP0805984A4 EP0805984A4 EP96908464A EP96908464A EP0805984A4 EP 0805984 A4 EP0805984 A4 EP 0805984A4 EP 96908464 A EP96908464 A EP 96908464A EP 96908464 A EP96908464 A EP 96908464A EP 0805984 A4 EP0805984 A4 EP 0805984A4
- Authority
- EP
- European Patent Office
- Prior art keywords
- resonator
- iars
- mechanical
- tines
- symmetrical
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
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- 238000010168 coupling process Methods 0.000 claims description 15
- 238000005859 coupling reaction Methods 0.000 claims description 15
- 230000033001 locomotion Effects 0.000 claims description 14
- 230000005284 excitation Effects 0.000 description 26
- 230000001133 acceleration Effects 0.000 description 9
- 238000000034 method Methods 0.000 description 8
- 230000007246 mechanism Effects 0.000 description 5
- 230000035945 sensitivity Effects 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/56—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
- G01C19/5607—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using vibrating tuning forks
- G01C19/5621—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using vibrating tuning forks the devices involving a micromechanical structure
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/24—Constructional features of resonators of material which is not piezoelectric, electrostrictive, or magnetostrictive
- H03H9/2405—Constructional features of resonators of material which is not piezoelectric, electrostrictive, or magnetostrictive of microelectro-mechanical resonators
- H03H9/2468—Tuning fork resonators
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/24—Constructional features of resonators of material which is not piezoelectric, electrostrictive, or magnetostrictive
- H03H9/2405—Constructional features of resonators of material which is not piezoelectric, electrostrictive, or magnetostrictive of microelectro-mechanical resonators
- H03H9/2468—Tuning fork resonators
- H03H9/2494—H-shaped, i.e. two tuning forks with common base
Definitions
- This invention relates to symmetrical mechanical resonators and in
- classical tuning fork includes two tines connected to a common stem
- piezoelectric crystalline quartz They have also been used as angular
- tines combines with the inertial rotation of the tuning-fork base to induce
- vibration modes in the conventional tuning fork these being:
- the second and fourth modes are parasitic and lead to
- It is a still further object of the invention is to provide a 2-axis rate
- a symmetrical mechanical resonator is
- the said mechanical resonator may be, in particular, a tuning fork
- resonator a frame-type resonator, or any planar resonator.
- coupling means also comprises means for indirectly exciting said movable masses by applying at least one force that acts on said mechanical coupling
- a planar symmetrical mechanical resonator in a further embodiment, is provided.
- inertial angular rare sensor comprises a mechanical resonator
- Fig. 1 illustrates a prior art tuning fork.
- Fig. 2 illustrates an H-type conventional tuning fork.
- Fig. 3 illustrates a conventional frame-type symmetrical resonator.
- Fig. 4 illustrates a tuning fork according to the present invention.
- Fig. 5 illustrates an idealized equivalent of a tuning fork according
- Fig. 6 illustrates an H-type tuning fork according to the present
- Fig. 7 illustrates a frame-type double tuning fork resonator
- Fig. 8 illustrates a frame-type symmetrical resonator according to
- Fig. 9 illustrates another frame-type symmetrical resonator
- Fig. 10 shows a modified flexible element employed in the gyro
- Fig. 11 shows a flexible element as in Fig. 10 but including two
- Fig. 12 illustrates a centrally excited tuning fork according to the
- Fig. 13 illustrates a centrally excited H-type tuning fork according
- Fig. 14 illustrates a centrally excited frame-type symmetrical
- Fig. 15 illustrates a 2-axis rate-sensor according to the present
- Fig. 16 illustrates a modified 2-axis rate-sensor according to the
- Fig. 1 illustrates a conventional, prior art, tuning fork mechanism
- asymmetrical mode is indicated by long arrows.
- Stem 12 is optional and
- the tines may be directly connected to the mounting base.
- Fig. 2 illustrates a two-ended conventional tuning fork, as described
- a mounting structure 16 is common to all the tines.
- Fig. 3 illustrates a frame type, double-tuning fork resonator
- the purpose of the present invention is to provide symmetrical
- Fig. 4 illustrates a tuning fork according to the present
- the tuning fork includes tines 20 and 21, a mounting base 61,
- the purpose of the coupling is to force the two tines to
- apertures portions will be found in the following embodiments as well.
- the two tines 20 and 21 are stiff and are
- the spring 28 represent the equivalent
- Fig. 6 illustrates an H-type tuning fork according to the present
- the respective tines are coupled as before and stems 29 and 30 allow torsional motion of the tuning fork around its line of symmetry.
- Fig. 7 illustrates a frame-type resonator according to the present
- the structure is essentially two tuning forks with their
- 64 and 65 indicate two mounting bases.
- Fig. 8 illustrates another frame-type resonator according to the
- each mechanism comprising bars 34, 35, 36, 37. 66,
- mechamcal couplings 37 are coupled on either side by mechamcal couplings 37 (two altogether), as
- Fig. 9 illustrates a modified frame-type resonator of Fig. 8 where
- Fig. 10 the modified flexible element is employed in the gyro
- the flexible element comprises two flexible elements
- Fig. 12 illustrates an
- the excitation frequency should be one half the
- the electrode set could be of the comb type described in "A
- piezoelectric crystalline sensor is by deflecting element 42 by means of
- Fig. 13 illustrates the application of the above excitation concept to
- Fig. 14 illustrates the application of the above excitation method to
- Fig. 15 illustrates a two-axis vibratory
- rate-sensor including four vibrating
- the four tines are linked with mechamcal couplings 49, 50, 51, and 52,
- Fig. 16 illustrates a modified two-axis angular rate sensor
Landscapes
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Gyroscopes (AREA)
Abstract
An inertial angular rate sensor (IARS) which includes a symmetrical mechanical resonator. The rate sensor includes one or more pair of vibrating masses (20, 21). The sensor further includes a mechanical coupler (24) which forces the masses to move in a symmetrical manner despite mechanical tolerances.
Description
COUPLED RESONATOR VIBRATORY RATE SENSOR
FIELD OF THE INVENTION
This invention relates to symmetrical mechanical resonators and in
particular to vibratory or Coriolis type rate sensors employing the same.
BACKGROUND OF THE INVENTION
The terms "tuning forks" and "symmetrical mechanical resonators"
are used herein as synonyms and both can be defined as signifying
mechanical structures that include two masses that are counter-oscillating
in such a manner that their common center-of-mass is ideally stationary
and their total linear and angular momentums are zero at any time. The
classical tuning fork includes two tines connected to a common stem,
which in turn is connected to a stationary base. The purpose of the stem
is to decouple the tines as much as possible from the base and to couple
them to each other, so that they have a common resonance frequency and
a minimum energy is dissipated to the stationary base.
Tuning forks have been used as frequency standards by employing
piezoelectric crystalline quartz. They have also been used as angular
inertial rate sensors, wherein the excited vibrational counter-motion of the
tines combines with the inertial rotation of the tuning-fork base to induce
in the tines so-called Coriolis accelerations which are perpendicular to the
plane of the excited vibrations and of opposite sense in each of the two
tines. These accelerations induce vibratory motions in the tines
perpendicular to the excited vibrations, the difference of which is
indicative of the input angular inertial rate. Although each of the tines
responds to said inertial rotation, it also responds to vibratory motion of
the mounting base that would lead to an output error that is
indistinguishable from the rate signal; however, by processing the
differential induced vibrations, the error is ideally eliminated. The earliest
application of a tuning fork resonant structure for angular inertial rate
sensing is described in "New space rate sensing instrument, " by J. Lyman
in Aeronautical engineering review, Vol. 12, pp. 24-30, 1953. A
modified rate sensor that utilizes a double tuning fork is described in
"Reduction of errors in vibratory Gyroscopes by Double Modulation" by
R.W. Bush and G.C. Newton, Jr. in IEEE Transactions on automatic
control, October 1964 pp. 525-535. Numerous other rate sensors are
based on vibrating structures that are essentially constituted by two
counter-oscillating masses of various structures. In order to decrease the
cost of vibratory rate sensors, they are often manufactured as monolithic
structures by employing photolithographic microfabrication techniques.
All monolithic tuning fork geometries utilized in the prior art belong to
either of the following three families:
Single tuning-fork, as in US Patent 5.343.749.
H-shaped structures that are essentially two tuning forks with a
common base, as in US Patents 4.524.619 and 5.056.366.
Vibrating frame constructions that can be regarded as two
tuning-forks with the ends of the ends of their corresponding tines
connected, as in US Patents 4.654.663 and 5.349.855.
It is obvious to those skilled in the art that there are four main
vibration modes in the conventional tuning fork, these being:
1. An in-plane, symmetrical, vibration mode depicted with short
arrows in Fig. 1.
2. An asymmetrical, in-plane vibration mode depicted with long
arrows in Fig. 1.
3. A symmetrical vibration mode perpendicular to the plane of the
tuning fork.
4. An asymmetrical vibration mode perpendicular to the plane of
the tuning fork.
The first and third modes are referred to as the excitation mode and
the output or Coriolis mode, and are the only modes relevant to rate
sensing. The second and fourth modes are parasitic and lead to
sensitivities of the rate sensor to linear accelerations. It is well known,
however, to those skilled in the art that, regardless of the specific
geometry of the tuning fork, there are additional, higher order, vibration
modes, that are, however, of little consequence to its applications as a rate
sensor.
A shortcoming of all prior art implementations of the tuning fork
resonators is that excitation of the first mode may be accompanied by an
undesirable excitation of the second mode due to asymmetry in the
excitation forces applied to the two tines or due to asymmetry in the mass
or stiffness of the tines as a result of manufacturing tolerances. This
results in vibrational energy that is transferred to the mounting base
through the stem and may lead to output errors in rate sensors of this type.
It may also combine with linear oscillations to further deteriorate the
fidelity of the output signal.
It is an object of the present invention to provide an improved
tuning fork and other symmetrical resonator topologies that is relatively
insensitive to mechanical asymmetries, suitable for inertial rate sensors.
It is another object of the invention to provide other improved
symmetrical resonator structures that are relatively insensitive to
mechanical asymmetries.
It is a further object of the invention to provide such resonator
structures that are more complex and include more than two moving
masses.
It is a still further object of the invention to provide a symmetrical
resonator wherein the second excitation mode is essentially eliminated by
mechanically constraining the two oscillating masses to move in opposite
directions.
It is a still further object of the invention to provide tuning fork
mechanisms wherein the excitation of a pair of tines is effected indirectly
by applying force to a single point.
It is a still further object of the invention to provide an improved
single-axis rate sensor.
It is a still further object of the invention is to provide a 2-axis rate
sensor.
Further objects and advantages of the invention will become
apparent as the description proceeds.
SUMMARY OF THE INVENTION
According to the invention, a symmetrical mechanical resonator is
provided, which comprises at least one pair of vibrating masses and
includes one or more mechanical coupling means that force the masses to
move in a symmetrical manner despite mechanical tolerances.
The said mechanical resonator may be, in particular, a tuning fork
resonator, a frame-type resonator, or any planar resonator.
According to a preferred embodiment of the invention, the said
symmetrical mechamcal resonator, comprising the said mechamcal
coupling means, also comprises means for indirectly exciting said movable
masses by applying at least one force that acts on said mechanical coupling
means.
In a further embodiment, a planar symmetrical mechanical resonator
is provided wherein said force is applied by parametrically modulating the
effective length of a mechanical member.
According to a further embodiment of the invention, a single axis
inertial angular rare sensor is provided, comprises a mechanical resonator
having one or more of the aforesaid characteristics.
A still further embodiment of the invention is a planar mechanical
resonator comprising four arms assembled in a cruciform shape, each pair
of adjacent arms being connected by mechanical coupling means that force
the masses to move in a symmetrical manner, whereby said arms are
vibrated in a scissors mode. Preferably said arms are indirectly excited
by forces applied in the plane of the resonator along at least one of its axes
of symmetry, which forces are more preferably generated by
parametrically modulating the effective length of a mechanical member.
A resonator according to this embodiment may be comprised in a dual axis
inertial angular rate sensor.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 illustrates a prior art tuning fork.
Fig. 2 illustrates an H-type conventional tuning fork.
Fig. 3 illustrates a conventional frame-type symmetrical resonator.
Fig. 4 illustrates a tuning fork according to the present invention.
Fig. 5 illustrates an idealized equivalent of a tuning fork according
to the present invention.
Fig. 6 illustrates an H-type tuning fork according to the present
invention.
Fig. 7 illustrates a frame-type double tuning fork resonator
according to the present invention.
Fig. 8 illustrates a frame-type symmetrical resonator according to
the present invention.
Fig. 9 illustrates another frame-type symmetrical resonator
according to the present invention.
Fig. 10 shows a modified flexible element employed in the gyro
geometry of Fig. 9.
Fig. 11 shows a flexible element as in Fig. 10 but including two
flexible elements.
Fig. 12 illustrates a centrally excited tuning fork according to the
present invention.
Fig. 13 illustrates a centrally excited H-type tuning fork according
to the present invention.
Fig. 14 illustrates a centrally excited frame-type symmetrical
resonator according to the present invention.
Fig. 15 illustrates a 2-axis rate-sensor according to the present
invention.
Fig. 16 illustrates a modified 2-axis rate-sensor according to the
present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Fig. 1 illustrates a conventional, prior art, tuning fork mechanism
including tines 10 and 10', stem 12 and mounting base 13. The first
symmetrical vibrational mode is indicated by short arrows, the second
asymmetrical mode is indicated by long arrows. Stem 12 is optional and
the tines may be directly connected to the mounting base.
Fig. 2 illustrates a two-ended conventional tuning fork, as described
in US Patent 4.524.619, which includes tines 14 and 14' at one end and
tines 15 and 15' at the other end and is provided with mounting bases 60,
60'. A mounting structure 16 is common to all the tines.
Fig. 3 illustrates a frame type, double-tuning fork resonator,
including counter moving masses 17 and 17', that are supported by a
flexible beam structure that is anchored by mounting bases 18.
All of the above resonator based rate sensors have a left-right
symmetry, and are typically excited by applying electrostatic or
piezoelectrically generated symmetrical opposing forces on the tines or
masses, in order to ideally obtain symmetrical motion. This symmetry is
important in order to minimize coupling of vibrational energy to the
mounting base by unbalanced reaction forces. Also, the tines static
deflection in the presence of external accelerations may combine with the
asymmetrical vibrational mode to cause sensitivity of the Coriolis output
to acceleration or gravity. In practice, the motion of the tines is never
symmetrical, because, due to mechanical tolerances, the tines have
different natural resonance frequencies, but since they are excited at a
common natural frequency, they do not react symmetrically, i.e., they
react with different amplitudes and different phases. The stiffer the stem,
the more sensitive is the differential motion to the mechamcal tolerances;
however, decreasing the stiffness of the stem lowers the frequency of the
asymmetrical mode and increases the sensitivity of the structure to external
accelerations. The above phenomena may be aggravated by asymmetrical
excitation forces on the tines due, for example, to tolerances in the
excitation electrodes deposited on the tines that also tends to excite the
asymmetrical mode.
A description of the excitation of the asymmetric mode due to
asymmetries in a frame-type resonator rate sensor is described in the
article: "A Micro machined Comb-Drive Tuning fork Rate Gyroscope" by
M. Weinberg et al. which appeared in the Proceedings of the 49th Annual
Meeting of the Institute of Navigation, June 21-23, 1993 page 599.
The purpose of the present invention is to provide symmetrical
resonators for inertial angular rate sensors where the excited motion is
essentially symmetrical in spite of asymmetries in the structure and the
excitation forces. Fig. 4 illustrates a tuning fork according to the present
invention. The tuning fork includes tines 20 and 21, a mounting base 61,
flexible links 22 and 23, and a flexible mechanical coupling 24 between
the two tines. The purpose of the coupling is to force the two tines to
move as a mirror image of each other and thus to essentially eliminate the
asymmetrical mode. The bases of the two tines have portions 20' and 21'
which have apertures for the purpose of reducing weight. Similar
apertures portions will be found in the following embodiments as well.
The operation of the coupling in Fig. 4 is easier to understand with
the aid of Fig. 5, where an idealized equivalent of the tuning fork of the
present invention is illustrated. The two tines 20 and 21 are stiff and are
mounted on pivots 25 and 26 that represent the flexible links 22 and 23.
They are also coupled by means of a third pivot 27 that forces their
motion to be symmetrically equal. The spring 28 represent the equivalent
spring rate of all the flexible 22, 23, 24 links in Fig 4. It is obvious that,
regardless of the symmetry of the forces applied to the tines or their
dimensional symmetry, their motion will be essentially symmetrical.
Fig. 6 illustrates an H-type tuning fork according to the present
invention. The respective tines are coupled as before and stems 29 and 30
allow torsional motion of the tuning fork around its line of symmetry. 62
and 63 indicate two mounting bases.
Fig. 7 illustrates a frame-type resonator according to the present
invention. The structure is essentially two tuning forks with their
5 respective tines (20-21 and 20a-21a) connected. The notches 31 are
provided in order to eliminate excessive tension in the tines when
deflected. 64 and 65 indicate two mounting bases.
Fig. 8 illustrates another frame-type resonator according to the
present invention, each mechanism comprising bars 34, 35, 36, 37. 66,
10 66', 67, 67', and 68, 68' indicate mounting bases. The two masses 32
and 33 are supported on either of its sides by parallel-motion bar
mechanisms (four altogether) well known to those skilled in the art, and
is coupled on either side by mechamcal couplings 37 (two altogether), as
in Fig. 4, that forces their motion to be the mirror image of each other,
15 as desired.
Fig. 9 illustrates a modified frame-type resonator of Fig. 8 where
the two masses are mounted on a simpler bar mechanism comprising bars
38, 39 and tension relief elements 40, 41. 69 and 70 indicate two
mounting bases.
20 The flexible link 24 in Fig. 4 can be modified so that it will be
stressed in compression and tension rather than in flexure, and thus further
increase the stiffness of the tines to non symmetrical motion, this is
achieved by employing a flexible element perpendicular to its original
orientation.
In Fig. 10 the modified flexible element is employed in the gyro
geometry in Fig. 9 - wherein the flexible element comprises a single
element. In Fig. 11 the flexible element comprises two flexible elements
to restore the symmetrical construction.
In prior art tuning forks and symmetrical resonators the two masses
are excited by two opposing forces individually applied to them, the forces
are typically electrostatic magnetic or piezoelectric. Fig. 12 illustrates an
excitation method according to the present invention applied to the tuning
fork in Fig. 4, wherein the tines are deflected by applying a single force
on the mechanical linkage 24 through member 42. 71 indicates a
mounting base. A preferred method for the excitation as in Fig. 12 is by
piezoelectrically modulating the length of element 42 at the resonant
frequency of the tuning fork. An alternative method is by modulating the
apparent length of member 42 by applying a force on its center which is
perpendicular to the plane of the paper. In this method, referred to as
parametric excitation, the excitation frequency should be one half the
resonant frequency of the tuning fork. A possible implementation of this
method, applicable to micromechanical devices, is by means of
electrostatic attraction forces applied to element 42. This may be effected
by constituting a capacitor that comprises a first stationary planar electrode
set and a second electrode set deposited on a planar surface of element 42,
and applying an alternating excitation voltage on the resulting capacitor.
Alternatively, the electrode set could be of the comb type described in "A
Micro machined Comb-Drive Tuning fork Rate Gyroscope" by M.
Weinberg et al. which appeared in the Proceedings of the 49th Annual
Meeting of the Institute of Navigation, June 21-23, 1993 page 599,
wherein the force is applied in the plan of the sensor.
Another preferable parametric excitation method applicable to
piezoelectric crystalline sensor is by deflecting element 42 by means of
shear forces generated with a set of electrodes deposited on it.
Fig. 13 illustrates the application of the above excitation concept to
the double-ended H-type tuning fork of Fig. 6, where the excitation is
applied differentially between the two individual tuning forks by means of
member 43'. 72 and 72' indicate two mounting bases.
Fig. 14 illustrates the application of the above excitation method to
the frame-type resonator of Fig. 7, where the excitation is applied
differentially between the two individual tuning forks by means of member
43. 73 and 73' indicate two mounting bases. In a similar manner the
excitation can be applied to the configurations in Figs. 8 and 9.
Until now the discussion was limited to single-axis rate sensors
where Coriolis forces are the result of inertial rotation around a single
sensitive axis which is parallel to the axis of symmetry of each of the
structures. A typical application of single-axis rate-sensors is automotive
vehicle yaw-sensors for skid sensing.
In many applications, e.g. optical line-of-sight stabilization,
two-axis inertial rate measurement is necessary. Therefore, if the
advantages of vibratory rate sensors are desired, two single axis sensors
would be used, alternatively, a single two-axis rate sensor would be
advantageous in such applications. Fig. 15 illustrates a two-axis vibratory
rate-sensor according to the present invention, including four vibrating
tines 44, 45, 46, and 47 and a mounting base 74. The arrows indicate the
polarity of the motion at a specific instant. As long as the four excitation
amplitudes are equal, the total net angular momentum of the sensor is
zero, and the structure is similar to two center-mounted beams that move
in a scissors-like motion. The zero total angular momentum ensures no
angular vibratory interaction with the mounting base 48 around an axis
perpendicular to the plane of the paper.
When the two-axes sensor in Fig. 15 experiences inertial rate
around the x-axis, i.e. around tines 46, 47 - or around the y-axis parallel
to tines 44 and 45, Coriolis accelerations will induce the tines to vibrate
perpendicular to the plane of the paper and in opposite phase. The
amplitude of the Coriolis accelerations will be equal if the excitation
amplitude of the tines were equal. In that case, subtracting Coriolis
induced deflections will provide an inertial angular rate signal that is
insensitive to extraneous linear vibrations of the mounting base along the
axis perpendicular to the plane of the paper, that might otherwise interfere
with the output signal. This is so, since the extraneous accelerations act
similarly on the two tines and their effect will thus be nullified by the
subtraction. It is thus obvious that the amplitude of the excitation should
be equal in the four tines. In order to ensure that the amplitude of the
four tines is equal in spite of practical imperfections, as described above,
the four tines are linked with mechamcal couplings 49, 50, 51, and 52,
that evenly distribute the excitation forces and equalize the arms'
deflection.
Fig. 16 illustrates a modified two-axis angular rate sensor,
according to the present invention, provided with a mounting base 75,
wherein the tines are indirectly excited by means of elements 53 and 54,
in a manner similar to that illustrated in Fig. 12. The operation of this
embodiment is self-explanatory, but it should be emphasized that,
depending on the specific design, four such excitation elements may be
used.
While preferred embodiments of the invention have been described,
it should be understood that the invention may be carried out with many
modifications, variations and adaptations by persons skilled in the art,
without departing from its spirit or exceeding the scope of its claims.
Claims
WHAT IS CLAIMED IS:
1. An inertial angular rate sensor (IARS), including a
symmetrical mechanical resonator, comprising at least one pair of
vibrating masses and including mechanical coupling means that force the
masses to move in a symmetrical manner despite mechanical tolerances.
2. An IARS including a tuning fork resonator with a mechanical
coupling as in claim 1.
3. An IARS including a frame-type resonator with a mechanical
coupling as in claim 1.
4. An IARS including a planar resonator as in claims 1, 2 and
3.
5. An IARS including an H-type tuning fork, comprising two
pairs of tines, the tines of each pair being coupled as in claim 1 , and stems
29 and 30 allowing torsional motion of the tuning fork around its line of
symmetry.
6. An IARS including a frame-type resonator, comprising two
tuning forks according to claim 1 , with their respective tines connected.
7. An IARS including a frame-type resonator, comprising two
masses supported by parallel-motion bar mechamsms and coupled on either
side by mechanical couplings, as in claim 1.
8. An IARS including a symmetrical mechanical resonator,
according to any one of claims 1 to 7, comprising means for exciting the
vibrating masses by applying at least one force to the mechanical coupling
means.
9. An IARS including a planar symmetrical mechamcal
resonator as in claim 8, wherein the force is applied by parametrically
modulating the effective length of a mechamcal member.
10. A two-axis IARS including a planar mechanical resonator,
comprising four arms assembled in a cruciform shape and means for
vibrating said arms in a scissors mode, wherein each pair of adjacent arms
are coupled as in claim 1.
11. A two-axis IARS including a mechanical resonator as in
claim 10, wherein the arms are indirectly excited by means of forces
applied in the plane of the resonator along at least one of its axes of
symmetry.
12. A two-axis IARS including a mechanical resonator as in
claim 11 , wherein said force is generated by parametrically modulating the
effective length of a mechanical member.
13. A IARS according to claim 1 , substantially as described and
illustrated.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IL11277095A IL112770A0 (en) | 1995-02-23 | 1995-02-23 | Coupled resonator vibratory rate sensor |
IL11277095 | 1995-02-23 | ||
PCT/US1996/001716 WO1996026445A1 (en) | 1995-02-23 | 1996-02-08 | Coupled resonator vibratory rate sensor |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0805984A1 EP0805984A1 (en) | 1997-11-12 |
EP0805984A4 true EP0805984A4 (en) | 1999-04-28 |
Family
ID=11067127
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP96908464A Withdrawn EP0805984A4 (en) | 1995-02-23 | 1996-02-08 | Coupled resonator vibratory rate sensor |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0805984A4 (en) |
AU (1) | AU5169796A (en) |
IL (1) | IL112770A0 (en) |
WO (1) | WO1996026445A1 (en) |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6018212A (en) | 1996-11-26 | 2000-01-25 | Ngk Insulators, Ltd. | Vibrator, vibratory gyroscope, and vibration adjusting method |
US6437483B2 (en) | 1996-11-26 | 2002-08-20 | Ngk Insulators, Ltd. | Vibrator, vibratory gyroscope, and vibration adjusting method |
US5998911A (en) * | 1996-11-26 | 1999-12-07 | Ngk Insulators, Ltd. | Vibrator, vibratory gyroscope, and vibration adjusting method |
US6747393B2 (en) | 1996-11-26 | 2004-06-08 | Ngk Insulators, Ltd. | Vibrator, vibratory gyroscope, and vibration adjusting method |
US6262520B1 (en) * | 1999-09-15 | 2001-07-17 | Bei Technologies, Inc. | Inertial rate sensor tuning fork |
US6858972B2 (en) | 2002-06-21 | 2005-02-22 | Ngk Insulators, Ltd. | Vibrator, vibratory gyroscope, and vibration adjusting method |
KR100712758B1 (en) | 2004-09-24 | 2007-04-30 | 세이코 엡슨 가부시키가이샤 | Piezoelectric resonator element and piezoelectric device |
JP4709260B2 (en) * | 2008-10-16 | 2011-06-22 | 日本電波工業株式会社 | Piezoelectric vibrating piece and piezoelectric device |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4958519A (en) * | 1982-01-25 | 1990-09-25 | The Board Of Regents Of The University Of Nebraska | Velocimeter |
US5367217A (en) * | 1992-11-18 | 1994-11-22 | Alliedsignal Inc. | Four bar resonating force transducer |
-
1995
- 1995-02-23 IL IL11277095A patent/IL112770A0/en unknown
-
1996
- 1996-02-08 EP EP96908464A patent/EP0805984A4/en not_active Withdrawn
- 1996-02-08 AU AU51697/96A patent/AU5169796A/en not_active Abandoned
- 1996-02-08 WO PCT/US1996/001716 patent/WO1996026445A1/en not_active Application Discontinuation
Non-Patent Citations (1)
Title |
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No further relevant documents disclosed * |
Also Published As
Publication number | Publication date |
---|---|
IL112770A0 (en) | 1996-06-18 |
WO1996026445A1 (en) | 1996-08-29 |
EP0805984A1 (en) | 1997-11-12 |
AU5169796A (en) | 1996-09-11 |
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