U.S. patent application number 14/331124 was filed with the patent office on 2014-11-27 for microgyroscope for determining rotational movements about three spatial axes which are perpendicular to one another.
This patent application is currently assigned to Maxim Integrated Products, GMbH. The applicant listed for this patent is Maxim Integrated Products, GMbH. Invention is credited to Hanno Hammer.
Application Number | 20140345379 14/331124 |
Document ID | / |
Family ID | 42227734 |
Filed Date | 2014-11-27 |
United States Patent
Application |
20140345379 |
Kind Code |
A1 |
Hammer; Hanno |
November 27, 2014 |
Microgyroscope for Determining Rotational Movements About Three
Spatial Axes which are Perpendicular to One Another
Abstract
A micro gyroscope for determining rotational movements about
three spatial axes x, y and z, which are perpendicular to one
another has a substrate (I) on which a plurality of masses (2, 3)
oscillating tangentially about the z axis, which is perpendicular
to the substrate (I), are arranged. The oscillating masses (2, 3)
are fastened on the substrate (I) by means of springs (5, 6, 8) and
tie bolts (7, 9). Driving elements (II) serve to maintain
oscillating, tangential vibrations of the masses (2, 3) about the z
axis, as a result of which, upon rotation of the substrate (I)
about any spatial axis, the masses (2, 3) are subjected to Corolis
forces and deflections caused as a result. Sensor elements detect
the deflections of the masses (2, 3) on the basis of the Corolis
forces generated. Some of the masses (2, 3) oscillating about the z
axis are mounted in a tiltable manner substantially about the x
axis which runs parallel to the substrate (I). Others of the masses
(2, 3) oscillating about the z axis are mountable in a tiltable
manner substantially about the y axis, which likewise runs parallel
to the substrate (I). At least one other of the oscillating masses
(2, 3) can be additionally at least partially deflected
substantially radially to the z axis in the x-y plane parallel to
the plane of the substrate (I). Said additionally radially
deflectable z mass (3) is assigned a sensor element (12) which can
likewise be deflected radially with respect to the z axis but does
not oscillate about the z axis.
Inventors: |
Hammer; Hanno;
(Graz-Lebring, AT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Maxim Integrated Products, GMbH |
San Jose |
CA |
US |
|
|
Assignee: |
Maxim Integrated Products,
GMbH
San Jose
CA
|
Family ID: |
42227734 |
Appl. No.: |
14/331124 |
Filed: |
July 14, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13258177 |
Sep 21, 2011 |
8776599 |
|
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PCT/EP2010/052880 |
Mar 8, 2010 |
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14331124 |
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Current U.S.
Class: |
73/504.12 |
Current CPC
Class: |
G01C 19/5712
20130101 |
Class at
Publication: |
73/504.12 |
International
Class: |
G01C 19/5712 20060101
G01C019/5712 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 26, 2009 |
DE |
10 2009 001 922.7 |
Claims
1. A gyroscope for detecting movement around a z axis, the
gyroscope comprising: a substrate; at least one anchor coupled to
the substrate; a first driving mass coupled to the at least one
anchor, the first driving mass radially oscillate with respect to a
location on the substrate; a second driving mass coupled to the at
least one anchor, the second driving mass radially oscillate with
respect to a location on the substrate; a first sensor electrode
coupled to the first driving mass, the first sensor electrode
detects a first capacitive change caused by a rotational movement
around the z-axis and generates a first signal; and a second sensor
electrode coupled to the first driving mass, the second sensor
electrode detects a second capacitive change caused by the
rotational movement around the z-axis and generates a second
signal, the first and second signals relate to a differential
measurement of the rotational movement around the z-axis.
2. The gyroscope of claim 1 wherein the first sensor electrode
comprises a first plate electrode located above the first driving
mass.
3. The gyroscope of claim 2 wherein the first plate electrode moves
in response to rotational motion about the z-axis, the first plate
electrode movement causes the first capacitive change within the
first sensor electrode.
4. The gyroscope of claim 3 wherein the first plate electrode and
the first sensor electrode are in the same plane.
5. The gyroscope of claim 3 wherein the first plate electrode is on
a side surface of the first driving mass and the first sensor
electrode is located adjacent to and in the same plane as the first
driving mass.
6. The gyroscope of claim 1 wherein the second sensor electrode
comprises first and second plates, the first and second sensor
electrodes move relative to each other to detect in-plane
capacitive movement between the first and second plates.
7. The gyroscope of claim 1 wherein oscillation of the first and
second driving masses are synchronized with each other using at
least one spring.
8. The gyroscope of claim 7 wherein the first and second driving
masses oscillate along a first axis and are 180 degrees out of
phase from each other.
9. The gyroscope of claim 7 wherein the first and second driving
masses are separated by the central anchor and that oscillate at
180 degrees out of phase from each other.
10. A method for detecting rotational rate about a z-axis, the
method comprising: causing radial oscillation of a first pair of
driving masses relative to a location on a substrate, the first
pair of driving masses oscillating 180 degrees out of phase with
each other and along a first axis; detecting a first capacitance
change within a first sensor electrode associated with a first
driving mass within the first pair of driving masses; detecting a
second capacitance change within a second sensor electrode
associated with a second driving mass within the second pair of
driving masses; and determining a first rotation rate about the
z-axis based at least in part on the first and second capacitance
changes.
11. The method of claim 10 wherein the first pair of driving masses
are coupled using a plurality of springs.
12. The method of claim 10 wherein the first pair of driving masses
are coupled using a first joint at the location on the substrate,
the first joint allowing the first pair of driving masses to
deflect and sense differential measurements related to the first
rotational rate.
13. The method of claim 10 wherein the oscillation of the first
pair of driving masses is at least partially controlled by a
plurality of springs.
14. The method of claim 13 wherein the plurality of springs
provides synchronized oscillation of the first pair of driving
masses.
15. The method of claim 10 wherein at least two driving electrodes
drive the radial oscillation of the first pair of driving
masses.
16. A gyroscope comprising: a substrate; an anchor coupled to the
substrate; a first drive mass coupled to the anchor, the first
drive mass radially oscillates along a first axis; a second drive
mass coupled to the anchor, the second drive mass radially
oscillates along the first axis and is synchronized with the first
drive mass; and a first synchronization spring coupling the first
and second drive masses, the synchronized radial oscillation of the
first and second drive masses being at least partially controlled
by the first synchronization spring.
17. The gyroscope of claim 16 further comprising: a first sensor
coupled to the first drive mass, the first sensor detects movement
around a z-axis; a second sensor coupled to the second mass, the
second sensor detects movement around the z-axis; and wherein the
first and second sensors generate signals from which a first
differential measurement is derived.
18. The gyroscope of claim 17 further comprising: a first sensor
electrode associated with the first sensor, the first sensor
electrode detects a first capacitive change caused by a first
movement around the z-axis; and a second sensor electrode
associated with the second sensor, the second sensor electrode
detects a second capacitive change caused by the first movement
around the z-axis.
19. The gyroscope of claim 18 wherein the first sensor electrode
comprises a first plate electrode and a second plate electrode that
move tangentially to each other.
20. The gyroscope of claim 16 further comprising: a first drive
element coupled to the first drive mass, the first drive element
causing the first drive mass to radially oscillate along the first
axis; and a second drive element couple to the second drive mass,
the second drive element causing the second drive mass to radially
oscillate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of copending application
Ser. No. 13/258,177, filed Sep. 21, 2011, which is the U.S. 371
National Phase of International Application PCT/EP2010/052880,
filed Mar. 8, 2010, which claims priority to German Application No.
102009001922.7, filed Mar. 26, 2009, which applications are hereby
incorporated herein by reference in their entireties and from which
applications priority is hereby claimed.
[0002] This invention refers to a micro gyroscope for determining
rotational movements about three perpendicularly stacked spatial
axes x, y and z with a substrate on which several tangentially
oscillating masses are arranged about the z axis perpendicularly
standing on the substrate, whereby the oscillating masses are
fastened to the substrate with springs and tie bolts and have drive
elements for maintaining the oscillating tangential vibrations of
the masses about the z axis, as a result of which the masses are
subject to Coriolis forces and the deflections caused by them when
the substrate rotates around any spatial axis, and with sensor
elements for determining the deflection of the masses owing to the
generated Coriolis forces.
[0003] In an x-y-z coordinate system, micro gyroscopes are
generally used for determining a rotational movement about an axis.
In order to determine the system's rotations about every one of the
three axes, three such micro gyroscopes are therefore needed. This
is not only very expensive, but it it's difficult to control them
and process the data.
[0004] A triaxial micro electro-mechanical sensor (MEMS) gyroscope
is known from TW 286201 BB in which masses are arranged on a
central tie bolt and set into an oscillating rotational motion.
These masses are arranged on a substrate and tilted about the x or
y axis owing to a Coriolis force generated about the y or x axis,
something made possible by a corresponding suspension of these
drive masses to the substrate. When there is a rotation about the z
axis, partial masses can in turn be translationally deflected by
their corresponding suspension on the pivoted masses. Both the
tilting movements and the translator movement can be determined
with sensors, and owing to their proportionality to the substrate's
rotation, it can be used as measure for the respective rotation
about the x, y or z axis. The corresponding deflections, however,
can be determined only with great difficulty.
[0005] So a tridimensional gyroscope can be created, in which
rotations about all three axes can be determined, D. Wood and
collaborators suggested in an article published in 1996 ("A
Monolithic Silicon Gyroscope Capable of Sensing about Three Axes
Simultaneously") a gyroscope with oscillating masses arranged
circularly about a central tie bolt. These masses are capable of
executing both tilting and rotational movements owing to the
generated Coriolis forces. The disadvantage, however, is that the
manufacturing of such a sensor and the actuation of the moved
masses are difficult. The movements of the individual sensor
components influence each other, so that measurements of the
gyroscope movement in x, y or z direction are insufficiently
accurate.
[0006] The task of this invention is to create a highly accurate
micro gyroscope for determining rotational movements about three
perpendicularly stacked spatial axes x, y and z for determining the
deflections in the individual rotational directions and providing
no false readings owing to movements in the directions to be
determined and the others, especially not through the actuation of
the masses.
[0007] The task is solved with a micro gyroscope having the
characteristics of claim 1.
[0008] The micro gyroscope according to the invention serves for
determining rotations about three stacked perpendicular spatial
axes x, y and z. It has a substrate on which several tangentially
oscillating masses are arranged about the z axis placed
perpendicularly on the substrate, whereby the oscillating masses
are fastened to the substrate by means of springs and tie bolts.
The drive elements move the masses about the z axis and maintain an
oscillating tangential vibration of the masses about the z axis.
When the substrate is rotating about any spatial axis, Coriolis
forces are generated that cause a deflection of the driven masses.
Sensor elements are arranged in the area of the masses to register
their deflections caused by the Coriolis forces that were generated
by the substrate's rotational movement.
[0009] According to the invention, some of the masses oscillating
about the z axis are arranged essentially in tilted fashion about
the x axis running parallel to the substrate. Other masses
oscillating about the z axis are also arranged in tilted fashion
about they axis running parallel to the substrate. In addition, at
least another one of the oscillating masses can be deflected
radially with respect to the z axis, and in the x-y plane parallel
to the plane of the substrate. Hereinafter, such masses will be
named "z masses". An oscillating sensor element that can also be
deflected radially with respect to the z axis, but not about the z
axis, is arranged on this z mass that can be additionally deflected
radially.
[0010] Especially owing to the separation of the z axis from the
sensor element, a decoupling of the tangential drive movement from
the radial sensor movement can be accomplished very favorably. The
sensor element itself is not tangentially actuated; therefore, only
the radial movement of the sensor element can be registered to
determine a rotation of the substrate about the z axis. The z mass
is moved about the z axis together with the other masses and
deflected in radial direction when a rotation of the substrate
about the z axis occurs due to the resulting Coriolis force
generated by this. The z mass then completes both a tangential and
radial movement, but only the radial movement is transferred to the
sensor element. This sole movement direction of the sensor element
in radial direction can be very easily registered without
superimposition with other movements. As a result of this, the
recording accuracy has been greatly improved compared to the
state-of-the-art solutions.
[0011] In accordance with an advantageous design of the invention,
the gyroscope consists essentially of eight masses oscillating
tangentially about the z axis, in which case four of these masses
can be additionally moved radially about the z axis and are
therefore called z masses. The arrangement of eight oscillating
masses from which four are z masses creates a balanced gyroscope
with respect to the occurring forces. The Coriolis forces can be
registered relatively easy and the respective cause of a rotation
about a certain axis can be reliably determined. A particularly
balanced system is achieved especially when the eight masses are
distributed uniformly along the perimeter and the oscillating
masses are oriented essentially only tangentially about the z axis
along the x and y directions and the remaining z masses are
arranged between the x and y axes. As all masses participating in
the drive movement, the z masses are also driven tangentially about
the z axis, but can also be deflected radially to the z axis. These
masses are preferably held by semi-open frames and set into the
tangential drive movement. The Coriolis force merely affects the z
mass mobility in radial direction--thus causing, in turn, the
deflection of the sensor element for determining a rotational speed
about the z axis.
[0012] In a favorable design of the invention, the masses that
oscillate largely tangentially about the z axis are tilting plates
for registering the substrate's rotation about the x or axis. As
soon as a Coriolis force occurs due to the substrate's rotation
about the x or y axis, these masses that oscillate only
tangentially about the z axis are tilted about the y or x axis.
This tilting movement can be converted to electrical signals with
capacitive sensors allocated to the masses.
[0013] Advantageously, the both radially and tangentially movable z
mass about the z axis can be coupled to a frame so it can be set in
tangential motion about the z axis. On the one hand, the frame
ensures the tangential drive of the z mass and, on the other hand,
a stable suspension of the mass so a movement in radial direction
can take place. Owing to the special frame design, the z mass can
be made sufficiently large so it can show a noticeable reaction to
the Coriolis forces and be deflected in radial direction. This
design variant shows clearly that the main feature of the z mass is
essentially the deflection in radial direction, which on the one
hand can occur only when the entire frame and z mass combination is
driven tangentially as primary movement. However, the secondary
movement in radial direction is especially important here. The
frame-like design makes it possible to implement these features
very advantageously.
[0014] It is especially favorable for the z mass that moves both
radially and tangentially about the z axis to be connected to at
least another sensor element for registering its radial deflection
caused by the Coriolis forces. As a result of this, the deflections
do not have to be measured at the z mass itself (which moves both
in radial and tangential direction) but the occurring Coriolis
forces that cause the z mass to be radially deflected can be
registered by the sensor element that moves only in radial
direction. This leads to a clear improvement of the measuring
results to be registered because there are no superimpositions with
other movements. A movement of the sensor element indicates
exclusively a Coriolis force in radial direction. The signal
registered in this way can therefore be very easily evaluated.
[0015] In an advantageous embodiment of the invention, the frame is
anchored to the substrate with springs, especially two, that can be
tangentially moved about the z axis. Since the frame is essentially
stationary in all directions except the tangential one, it is only
capable of oscillating in tangential direction. The Coriolis forces
acting on the frame cannot deflect it radially. Accordingly, the
frame or the springs are thus built stiffly in radial direction.
Preferably, the frame does not move out of the x or y plane either,
and therefore does not react to the Coriolis forces that occur as a
result of the rotational speeds about the x or y axis. The
stiffness in this direction, however, is not always required; it
can be tolerated for the frame and the z mass to move out of the
x-y plane when it is ensured that this movement will not be
transferred to the sensor element and affect its measurement.
[0016] To obtain a micro gyroscope with a well-balanced system with
regard to the reaction forces and reaction torques occurring
between the masses being moved, it is better to arrange the frames
between the masses oscillating tangentially about the z axis or
tilting plates.
[0017] The z masses, which can be moved both radially and
tangentially about the z axis, are connected to their respective
frame with at least one spring, preferably with four springs. This
creates a stable arrangement of the z axis within the frame to
advantageously ensure that the z mass can be moved only radially
relative to the frame. Here, the z mass reacts merely to the
rotational speeds about the z axis, eliciting a clear reaction of
the sensor element allocated to the z mass and a correspondingly
unambiguous measurement result owing to the resulting electric
signal.
[0018] If in an advantageous design of the invention the frames are
anchored to the substrate and can be moved mostly tangentially
about the z axis, then the primary movement in the frames can be
clearly initiated as a rotation in tangential direction about the z
axis in the frame. An oscillation in radial direction of the z mass
movably arranged within the frame is the resulting secondary
movement.
[0019] The dynamic behavior of the micro gyroscope is significantly
enhanced when the tilting plates and the frames are connected to
one another with springs. These springs act as synchronization
springs and cause the primary movement (which takes place
tangentially about the z axis) to be executed by the tilting plates
and the frame in the same fashion. As a result of this, a common
mode of oscillation of the tilting plates and the frame takes
place, in which case all masses involved oscillate with equal
frequency and phase.
[0020] Preferably, the springs (which connect the tilting plates
and the frames with each other) are executed stiffly in tangential
direction, but non-rigidly in the other directions. Therefore, it
is possible for the primary movement occurring in the tilting
plates and frames to establish a common mode of oscillation with
equal frequency, but the resulting plate tilting out of the x-y
plane during an indication of a rotational speed in x or y
direction is not impeded by the synchronization springs. Thus, the
tilting plates can be largely moved independently out of the frame,
remaining preferably on the x-y plane without having a large spring
resistance that could counteract this.
[0021] For the clear indication of a rotational speed about the x
or y axis, it has been advantageously intended for some of the
masses or tilting plates oscillating tangentially about the z axis
and other masses or tilting plates to be tiltably anchored to the
substrate only about the y axis. The masses or tilting plates,
which are farther away from the x axis or lie on the y axis and
move out of the x-y plane, therefore indicate a rotational speed
about the y axis. On the other hand, the masses or tilting plates
farther away from the y axis or lying on the x axis indicate, while
they tilt about the y axis or when they move out of the x-y axis, a
rotational speed of the sensor about the x axis.
[0022] Drive elements that initiate the primary oscillation are
preferably arranged on the masses that oscillate only tangentially
about the z axis and/or on the frame. These drive elements initiate
a drive oscillation in the structural parts that is a primary
oscillation about the z axis.
[0023] In an advantageous design of the invention, the drive
elements needed for maintaining the drive oscillation about the z
axis are electrodes of comb capacitors equipped with the suitable
switching drive voltages. Parts of the drive elements are fastened
to the substrate for accomplishing this, other parts are in turn
fastened to the structural elements to be driven. When AC voltage
is applied, the electrodes are mutually attracted and this
generates the oscillating primary oscillation of the structural
parts.
[0024] Sensor elements are preferably arranged below the tilting
plates for registering the deflection of the tilting plates. These
sensor elements can be plate capacitors, for example, whose one
movable half is executed on the substrate surface by a tilting
plate and whose other, static half, by an extended conductor line
below the tilting plate. The change of the capacity during the
registration of a measured movement brings about a corresponding
change of an electrical measured signal.
[0025] If sensor elements are allocated to the z masses for
registering the radial deflections caused by the Coriolis forces,
then the rotational speeds about the sensor's z axis above these
sensor elements can be very easily and unmistakably determined.
[0026] Preferably, the sensor elements allocated to the z masses
consist of movable measuring electrodes of capacitors whose static
counterparts are rigidly connected to the substrate. One part of
the measuring electrodes therefore also completes the movement of
the sensor elements and, when doing this, either approaches or
moves away from the static counterparts of the measuring
electrodes. This spacing change is converted to a changeable
electrical signal, which allows one to draw conclusions about the
sensor's rotational speed about the z axis.
[0027] The movable measuring electrodes of the sensor elements are
preferably executed as frames movable in radial direction. This
creates a stable structural element that can reliably signal the
movement.
[0028] It is especially advantageous for the z masses to be as far
away from the sensor's center as possible because a stronger
Coriolis force can act on them and consequently they can deliver a
larger oscillation amplitude to the allocated sensor element. As a
result of this, small rotational speeds can already be measured. In
addition, the sensor can nonetheless be built very compactly and
with a small surface and deliver clear signals for the
corresponding rotational speeds.
[0029] To ensure that the sensor element is decoupled as far as
possible from the tangential movement of the z mass allocated to
it, it has been advantageously intended for the z mass and the
sensor element to be connected with springs, a non-rigid one in
tangential direction and a stiff one in radial direction. The
radial movement of the z mass is thus transferred to the sensor
element and both radial oscillations jointly produce the secondary
oscillation without the tangential primary movement of the z mass
being capable of interconnecting on the sensor element.
[0030] So the sensor element allocated to the z mass can be stably
arranged, especially to make it resistant to influences acting on
directions other than the intended one as well, it is proposed to
fasten the sensor element to the substrate by means of (preferably)
four springs. In this case, the springs are executed in a way to
allow a radial movement of the sensor element but impede movements
in other directions as much as possible.
[0031] Preferably, the tilting plate is arranged on the substrate
with springs that allow a tangential-rotational movement of the
tilting plate in the x-y plane and a tilting movement of the
tilting plate out of the x-y plane. For this purpose, the springs
are preferably fixed close to the center with a tie bolt.
[0032] A preferred design of the sensor's basic form is an
essentially circular one for its exterior for supporting the
rotation of the primary movement and so the sensor can also fit in
a very small structural space.
[0033] Other advantages of the invention are described with the
help of the embodiments shown in the following figures, which show
the figures as later described.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] FIG. 1 is a top view of a gyroscope according to the
invention,
[0035] FIG. 2 is a top view of the tilting plates of the gyroscope
according to FIG. 1,
[0036] FIG. 3 is the connection of the tilting plates according to
FIG. 2,
[0037] FIG. 4 is a top view of the z sensor device of the gyroscope
shown in FIG. 1,
[0038] FIG. 5 is a top view of a z sensor device of the gyroscope
according to FIG. 1,
[0039] FIG. 6 is a sketch of the primary movement of the sensor
according to FIG. 1,
[0040] FIG. 7 is a secondary movement for determining a y
rotational speed of the gyroscope according to FIG. 1, and
[0041] FIG. 8 is the determination of a z rotational speed of the
gyroscope according to FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0042] The top view of FIG. 1 shows the overview of all components
of a micro electromechanical gyroscope in accordance with this
invention. The figures explain in more detail the individual
components as well as the types of oscillation of the gyroscope
while rotational speeds are being registered.
[0043] The gyroscope consists especially of elements for
registering a rotational speed about the x axis and the y axis,
which lie on the drawing plane. Further structural groups of the
gyroscope lying on this plane refer to the detection of the z
rotational speed. Parallel to and below this plane, there is a
substrate on which the structural parts shown are arranged, as
described below.
[0044] Tilting plates 2 are intended for registering the x and y
rotational speeds. For determining a z rotational speed (i.e. a
rotation of the gyroscope about the z axis) a z mass 3 is
essentially placed between two tilting plates 2. The z mass 3 is
located in a frame 4 and fastened to it with four springs 5. The
frame 4 hangs over two frame springs 6 on two frame tie bolts 7
that are fixed to the substrate.
[0045] The tilting plates 2 are on the one hand fastened to the
substrate with tilting springs 8 and a tie bolt 9. On the other
hand, each tilting plate 2 is held between two frames 4 with two
synchronization springs 10.
[0046] The tilting plates 2 and the z masses 3 with the frame 4 are
set into an oscillating rotational tangential motion about the z
axis as an oscillating primary movement. In this example, the drive
takes place with the help of two comb electrodes 11 and 11'. Here,
the comb electrodes 11 and 11' are fastened to the movable parts,
namely the tilting plates 2 and the frame 4, while the
corresponding counter electrodes 11' are stationary fixed on the
substrate. The application of alternating voltage elicits the
mutual attraction of the electrodes 11 and 11' that are on the
opposite sides and this causes the tangential oscillation of the
tilting plates 2 as well as of the z masses 3 and frame 4 in terms
of the primary movement. In order to maintain the oscillating
rotation of the individual elements in synchrony and the tilting
plates 2 and the frame 4 stable, synchronization springs 10 located
between the tilting plates 2 and the frame 4 are intended.
[0047] If the gyroscope now starts rotating about the x axis,
Coriolis forces occur that make the tilting plates 2 arranged on
the x axis to protrude from the x-y plane. Owing to the
predetermined elasticity of the tilting springs 8 and the
synchronization springs 10, the tilting plates 2 lying on the x
axis rotate about the y axis or about the tilting springs 8 into
and out of the drawing plane. For this purpose, the tilting springs
8 have been executed in a way to allow, on the one hand, the
driving movement of the tilting plates 2 about the z axis and, on
the other hand, to not substantially impede the tilting about the y
axis. About the x axis, however, the tilting springs 8 are largely
rigid on the tilting plates 2 located on the x axis. The same
applies to a rotational speed of the gyroscope about they axis. In
this case, the tilting plates 2 located on they axis tilt out of
the x-y plane and indicate the corresponding Coriolis force acting
upon the tilting plates 2. The corresponding tilting springs 8 of
these tilting plates 2 are executed analogously to the other
tilting springs; owing to their arrangement and design, they allow
a rotation of the tilting plates 2 positioned on the y axis about
the z axis and a tilting movement about the x axis. On the other
hand, they have an essentially rigid design about the y axis. The
synchronization springs 10 are designed in a way to also allow the
tilting movement of the tilting plates 2 out of the x, y drawing
plane. However, they pass on the tangential movement about the z
axis to the neighboring structural part. Accordingly, they have
been designed largely rigid for the forces that act in tangential
direction.
[0048] The z mass 3 and the frame 4, among other, serve as
indicators of the gyroscope's z rotational speed. The primary
movement completes itself together with the tilting plates 2 in
tangential direction about the z axis too. The drive takes place
with comb electrodes 11 and 11', in which case the comb electrodes
11 are arranged on the frame 4, whereas the comb electrodes 11' are
stationary fastened on the substrate. The tangential movement about
the z axis is supported by the frame springs 6, which allow the
tangential movement, but largely impede a radial movement of the
frame 4 in this direction owing to their respective rigidity.
[0049] Due to the tangential primary movement, Coriolis forces
occur in radial direction as soon as the gyroscope rotates about
the z axis. The frame 4 cannot yield in radial direction owing to
the suspension on the frame springs 6 and the synchronization
springs 10. The z mass 3, on the other hand, has been suspended
from the frame 4 with its springs 5 in such a way that it can yield
in radial direction of the Coriolis force. The springs 5 with which
the z mass 3 is fastened to the frame 4 have been set in such a way
to each other that z mass 3 is made more insensitive against
parasitic rotational torques that occur solely from the primary
tangential movement. As a result of this, the z mass 3 reacts
essentially only to Coriolis forces that occur due to a rotational
speed along the z axis.
[0050] To determine the z rotational speed without interference,
the z mass 3 is connected to a sensor element 12. This sensor
element 12 is fastened to the tie bolt 9 and to two tie bolts 14
with sensor springs 13. In addition, the sensor element 12 is
connected to the z mass 3 via a coupling spring 15. The coupling
spring 15 is executed non-rigidly in tangential direction and
stiffer in radial direction. As a result of this, a decoupling
between the drive movement of the z mass in tangential direction
and the sensor and secondary movement in radial direction occurs.
While the z mass is driven in tangential direction without this
having a significant effect on the sensor element 12, when a
Coriolis force occurs the z mass 3 is moved outwards and inwards,
and while doing so it carries the sensor element 12 due to the
corresponding spring stiffness of the coupling spring 15. With
respect to their spring stiffness, the sensor springs 13 are
likewise executed in such a way that they hardly impede the sensor
element 12 in radial direction--in other words, that in this
direction they have a relatively low (and in any case precisely
adjustable) spring stiffness and at the same time they largely
impede the movements of the sensor element 12 in tangential
direction. This decouples the primary movement from the secondary
movement, so that the sensor element 12 can indicate a Coriolis
force occurring in radial direction only through a corresponding
oscillating movement in radial direction. The mesh structure of the
sensor element 12 thus implements the movable electrode of a
capacitor whose static opposite pole is fixed on the substrate
within the recesses and not drawn. This variable capacity serves
the purpose of converting the registered movement into an electric
signal.
[0051] For a better understanding, the following figures show the
gyroscope's individual elements detached from the other structural
elements.
[0052] FIG. 2 shows the tilting plates 2. Every tilting plate 2 is
fastened to two tie bolts 9 with the help of two tilting springs 8.
The tilting springs 8 allow on the one hand the tangential
oscillating primary movement of the tilting plates 2 and, on the
other hand, they also allow the tilting of the tilting plates 2 out
of the x-y plane around the tilting springs 8. In radial direction,
on the other hand, the tilting springs 8 have been stiffly executed
so that the tilting plates 2 are not significantly deflected by a
Coriolis force acting in radial direction that indicates a z
rotation of the gyroscope. Therefore, a predetermined deflection of
the tilting plates 2 occurs due to a rotational speed about the x
or y axis.
[0053] According to FIG. 3, the tilting plates 2 of FIG. 2 are
connected with the frame 4 and synchronization springs 10. The unit
shown here is set into a synchronous tangential motion about the z
axis as primary movement. The connecting springs 10 synchronize the
tangential movement of the tilting plates 2 and the frame 4. Speed
differences among the components, which could possibly occur owing
to tolerances in the production of the gyroscope, are offset by the
synchronization springs 10. The individual structural parts thus
oscillate with a common resonance frequency and therefore indicate
rotational speeds in the same way.
[0054] FIG. 4 shows the structural parts that are essential for
registering a z rotational speed. In the primary movement, the z
mass 3 is set into an oscillating tangential motion about the z
axis together with the frame 4 (not shown here). Reacting to the
gyroscope's rotation about the z axis, the z mass 3 is stimulated
to a radial oscillation. The z mass 3 is connected to the sensor
element 12 via the coupling spring 15. Sensor springs 13 fasten the
sensor element 12 to the tie bolts 9 and 14. The sensor springs 13
allow the sensor element 12 to make a radial movement, which during
the course of registering a rotational speed about the z axis is
coupled by the radial oscillation of the z mass 3. The transfer of
the radial movement from the z mass 3 to the sensor element 12 is
made possible by the coupling spring 15, which is on the one hand
sufficiently non-rigid for not transferring the tangential primary
movement of the z mass 3 to the sensor element 12 and on the other
hand sufficiently rigid to make the secondary movement of the z
mass 3 a radial movement of the sensor element 12. Four of the
corresponding structural parts have been arranged on the
gyroscope's substrate at a 90-degree angle to one another. Here,
they are located between the x and y axis on the median line.
[0055] A detailed view of the structural elements for determining
the z rotational speed is shown once again in FIG. 5. The z mass 3
is fastened to the frame 4 with springs 5. The frame 4 is fastened
to the frame tie bolt 7 via the frame springs 6 that are non-rigid
in tangential direction. Apart from being fastened to the tie bolt
9, the sensor element 12 is also arranged on the tie bolts 14.
These tie bolts 14 can, in addition to their function as fixation
points for springs 13, also serve as stoppers for the primary
movement of the frame 4 and the tilting plates 2 too. The radial
movement of the z mass 3 is transferred via the coupling spring 15
to the sensor element 12, which is also set into a radial
oscillating motion together with the z mass 3 as soon as a Coriolis
force indicates a z rotational speed.
[0056] FIG. 6 shows a schematic view of the gyroscope's primary
movement. It becomes apparent that the tilting plates 2 and the
frames 4 are set into an oscillating rotation about the z axis with
the z masses 3. In this case, the tie bolts 14 serve as stoppers of
the tilting plates 2 and the frame 4. In this primary movement, the
sensor elements 12 remain arranged on the substrate without moving.
The drawing is schematic as in the following figures, which is why
the details can be a little inaccurate.
[0057] FIG. 7 shows the deflection of the tilting plates 2 located
on the x axis, and this deflection indicates the gyroscope's x
rotational speed. The tilting plates 2 located on the x axis are
tilted out of the x-y plane around the tilting springs 8 with which
they are fastened to the tie bolts 9. The tilting elements 2
located on they axis, on the other hand, remain on this plane.
Owing to the spring stiffness of the synchronization springs 10,
the frames 4 and the z masses 3 are also tilted in this embodiment,
but due to the softness of the coupling springs 15, these
deflections do not disrupt the sensor element 12. Thanks to plate
capacitors (whose movable one-half is formed by the tilting plate 2
itself) and their static one-half located below the allocated
tilting plate 2 on the substrate, the respective tilting movements
can be converted to an electric signal. Due to the softness of the
coupling springs 15, these movements have no effect on the sensor
elements 12. Similarly, a y rotational speed can be registered. In
this case, the tilting plates 2 (which are arranged along they
axis) tilt out of the x-y plane. If applicable, as a result of
this, the z masses 3 and the frames 4 (which are fastened to the
tilting plates 2 via the synchronization springs 10) are also moved
out of the x-y plane, at least partially.
[0058] FIG. 8 shows a schematic view of how a gyroscope's z
rotational speed is registered. Here, the Coriolis force sets the z
masses 3 into oscillating motions going in radial direction, as
already described above. In this movement of the z mass 3, the
coupling spring 15 causes the sensor element 12 to move in radially
oscillating fashion too. The corresponding springs are designed so
the sensor element 12 can be moved slightly in radial direction,
but stay rigid in a direction out of the x-y plane or in tangential
direction about the z axis. The radial movement of the sensor
element 12 can be determined on its mesh structure with the
corresponding electrodes that are fastened in stationary fashion on
the substrate. For registering the z rotational speed, both the
tilting plates 2 and the frame 4 remain largely rigid. If need be,
however, and depending on the respective spring constants, the
frame 4 can be slightly deflected in radial direction.
[0059] This invention is not restricted to the embodiments shown.
In particular, modifications such as the design of the individual
structural parts and their mutual arrangement are possible in a
manner different from the one shown here, as far as they remain
within the framework of the applicable patent claims.
REFERENCE LIST
[0060] 1 Substrate
[0061] 2 Tilting plate
[0062] 3 zmass
[0063] 4 Frame
[0064] 5 Spring
[0065] 6 Frame spring
[0066] 7 Frame tie bolt
[0067] 8 Tilting spring
[0068] 9 Tie bolt
[0069] 10 Synchronization spring
[0070] 11 Comb electrode
[0071] 11' Counter electrode
[0072] 12 Sensor element
[0073] 13 Sensor spring
[0074] 14 Tie bolt
[0075] 15 Coupling spring.
* * * * *