US20030159510A1 - Phase insensitive quadrature nulling method and apparatus for coriolis angular rate sensors - Google Patents
Phase insensitive quadrature nulling method and apparatus for coriolis angular rate sensors Download PDFInfo
- Publication number
- US20030159510A1 US20030159510A1 US09/915,026 US91502601A US2003159510A1 US 20030159510 A1 US20030159510 A1 US 20030159510A1 US 91502601 A US91502601 A US 91502601A US 2003159510 A1 US2003159510 A1 US 2003159510A1
- Authority
- US
- United States
- Prior art keywords
- proof mass
- mass
- control voltage
- dither
- minus
- 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.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims description 30
- 238000006073 displacement reaction Methods 0.000 claims description 17
- 241000237509 Patinopecten sp. Species 0.000 claims 15
- 235000020637 scallop Nutrition 0.000 claims 15
- 230000001133 acceleration Effects 0.000 abstract description 12
- 230000010355 oscillation Effects 0.000 abstract description 9
- 238000004519 manufacturing process Methods 0.000 abstract description 8
- 238000005530 etching Methods 0.000 description 4
- 239000011521 glass Substances 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 3
- RZVAJINKPMORJF-UHFFFAOYSA-N Acetaminophen Chemical compound CC(=O)NC1=CC=C(O)C=C1 RZVAJINKPMORJF-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 239000005297 pyrex Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000003534 oscillatory effect Effects 0.000 description 1
- 230000002040 relaxant effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
Images
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
- G01C19/5705—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using masses driven in reciprocating rotary motion about an axis
-
- 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
- G01C19/5719—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using planar vibrating masses driven in a translation vibration along an axis
- G01C19/5733—Structural details or topology
- G01C19/5755—Structural details or topology the devices having a single sensing mass
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
- G01P15/14—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of gyroscopes
Definitions
- the present invention relates to an inertial instrument and more specifically pertains to vibrating accelerometers used as multi-sensors for measuring linear acceleration and rate of rotation of a moving body.
- Gyroscopes are well known for use as angular velocity and acceleration sensors for sensing angular velocity and acceleration which information is necessary for determining location, direction, position and velocity of a moving vehicle.
- the present invention utilizes two masses in tandem, a dither mass and a proof mass, or pendulum. Each mass has only a single degree of freedom. It is desired to have the dither mass move along an axis that is parallel to the plane of the housing. The driving forces on the dither mass causing its vibration do not act directly on the pendulum. These forces, however cause the dither mass to move out of the plane of the housing due to dither beam misalignments. This out-of-plane motion generates error signals which are in quadrature with the signals generated by rate inputs. Therefore, a high degree of phase discrimination is required to separate the rate signal from the quadrature signal.
- This invention uses a new quadrature nulling technique which eliminates the requirement for accurate phase and relaxes control of the dither beam alignment tolerances which generate out of plane motion.
- the present invention applies vibration driving signals to the dither mass to vibrate the dither mass and the proof mass at a combined resonant frequency, and applies a restoring force to the proof mass which is in phase with its dithered displacement.
- vibration driving signals are applied to the dither mass to vibrate the dither mass and proof mass which are in an X-Y plane at a combined resonant frequency about the Z axis of the X-Y plane.
- a restoring torque is applied to the proof mass which is in phase with its dithered displacement.
- FIG. 1 is a top plane view of the driven and sensing element of an accelerometer according to the present invention
- FIG. 2 is a cross-section of the quadrature nulling projection on the end of the pendulum of FIG. 4;
- FIG. 3 is a diagrammatic illustration of the functional relationship of portions of the accelerometer of FIG. 1 and FIG. 4;
- FIG. 4 is a diagrammatic illustration of the pendulum and dither mass or vibrating structure of the present invention.
- FIG. 5 is a top plan view of an alternate configuration for the proof mass and dither mass of the present invention.
- FIG. 6 is a partial broken-away perspective of the configuration of FIG. 5 showing the relationship between the disc-shaped proof mass and the ring-shaped dither mass.
- FIG. 7 is a partial perspective showing the relationship between the proof mass of FIG. 5 with its top cover and the quadrature nulling electrodes;
- FIG. 8 is a top plan view of the disc-shaped proof mass with multiple teeth formed by etching grooves around its circumference;
- FIG. 9 is a left side plan view showing the edge of the disc-shaped proof mass between its top and bottom covers, each cover containing quadrature nulling electrodes;
- FIG. 10 is a right side plan view showing the edge of the disc-shaped proof mass between its top and bottom covers, each cover containing quadrature nulling electrodes.
- the accelerometer gyro disclosed in an application for Micromachined Silicon Gyro Using Tuned-Accelerometer having U.S. patent application Ser. No. 09/778,434 filed on Feb. 7, 2001 and assigned to the same assignee as the present application illustrates a micromachined accelerometer-gyro having a pendulous mass or proof mass suspended within a dither mass that provides improved performance as the result of a considerable decrease in manufacturing flaws that affects performance of the accelerometer gyro.
- the present invention goes beyond structural improvement of the proof mass and dither base assembly and the manufacture thereof by providing a means for nulling the error created from manufacturing tolerances and electronic phase uncertainty.
- FIG. 4 a conceptual schematic of the structure of the pendulum or proof mass 87 in association with the dither mass 93 is shown.
- the proof mass 87 is attached to the dither mass 93 by pendulum flexure points 89 .
- the dither mass 93 moves back and forth in the direction 109 .
- the dither mass motion 109 is not exactly along the X axis 103 of the pendulum 87 .
- the actual dither mass motion 109 is off-axis by a dither misalignment angle 111 , causing slight oscillation in the Y direction 105 .
- Quadrature error is very similar in that both are sinusoidal signals centered at the frequency of oscillation. However, quadrature error can be distinguished from Coriolis acceleration by the phase relative to the driven oscillation.
- bias voltage applied to these fingers results in a net force applied to the proof mass that is directly proportional to the position of the proof mass thereby forcing the proof mass to vibrate along the desired dither axis, in other words, parallel to the X axis which is the housing axis for the proof mass.
- FIG. 4 illustrates in schematic form the structure of the dither mass or vibrating structure and the proof mass or pendulum structure of the present invention.
- the dither mass 93 which is the vibrating structure for the pendulum 87 oscillates off-axis by an angle 111 along direction 109 .
- This off-axis vibration of the dither mass 93 is inherent in the construction of the rate sensor of the present invention. This is the best that can be done in the manufacturing process.
- the dither mass and pendulum will naturally dither in the direction which is primarily along the X axis 103 but will also dither along Y axis 105 because of a misalignment angle 111 caused by mechanical imperfections of the dither driving beams during the etching phase of the fabrication.
- the pendulum 87 is attached to the dither base 93 by the pendulum flexures 89 .
- the pendulum 87 senses Coriolis acceleration causing the pendulum to rotate about the flexure 89 .
- the present invention in contrast to the approach in the above noted article, rather than forcing the dither base 93 and pendulum 87 to vibrate along the desired dither or X axis 103 , which is parallel to the housing axis, allows the dither base 93 to vibrate along the misaligned direction 109 .
- the quadrature control electrodes 107 of the present invention do not force the dither base 93 to vibrate along the X axis 103 .
- the quadrature control electrodes 107 only exert forces on the pendulum mass 87 to cause pendulum motion about the flexure axis 89 so that the pendulum continuously centers within the housing 81 as sensed by the pickoff. In this manner, neither the dither base 93 nor the pendulum mass 87 are coerced to move along a certain axis, like X axis 103 .
- the angular rate sensor is constructed to have a pendulum or sensing element 87 which is attached by flexures 89 to the dither mass or vibrating structure 93 which has dither drive and pickoff electrodes elements 83 mounted thereon.
- the dither mass 93 is mounted for motion within the plane of the paper of FIG. 1 within a frame 81 .
- the dither mass 93 has a plurality of flexure suspensions 85 therein to permit the dither motion along the X axis 103 .
- the mechanical misalignment illustrated graphically in FIG. 4, along with phase error of the dither reference signal are the major source of bias instability, non-repeatability and temperature sensitivity of tuned Coriolis angular rate sensors.
- the present invention provides a method to servo the quadrature error signal to null. Since the servo signal is d.c., there is no resulting phase sensitivity. The result is improved bias stability, repeatability and reduced temperature sensitivity, in addition to relaxing the tolerance requirements on etching the dither beams and the tolerance requirements on the system digital electronics phase stability.
- the present invention is contrary to the traditional manner of controlling bias error. The traditional approach was to attempt exceptionally close tolerances on the etching of the dither beams and attempt to achieve exceptionally close system tolerances on the digital electronics phase stability circuitry.
- the concept of the invention is to introduce a torque to the sensing element or pendulum 87 by the application of d.c. signals which results in an a.c. restoring force that is in phase with the dither displacement.
- a torque or forcer can be used to servo the quadrature error signal to null because the quadrature signal is in phase with acceleration which in turn is in phase with the dither displacement.
- FIG. 2 is a diagram of a quadrature nulling forcer as envisioned by the present invention.
- FIG. 2 is a cross-section of the present invention taken through the region containing the top electrodes 95 , 97 , and bottom electrodes 99 , 101 and the scalloped edge 91 of the sensing element 87 .
- the top electrodes 95 , 97 and bottom electrodes 91 , 101 are divided into segments having alternate polarities. Each electrode segment 95 , 97 on the top, and 91 , 101 on the bottom, are aligned with respect to the scalloped edge 91 of the sensing element so that both polarities of the alternate segments have equal areas overlapping each projection along the scalloped edge 91 of the sensing element 87 when the dither motion is not excited.
- the quadrature nulling forcer exerts a force as depicted in the graph of FIG. 3.
- a bias voltage +V is applied to the sensing element and plus or minus d.c. control voltages v are applied to the top electrodes 95 and 97 and the bottom electrodes 99 and 101 .
- the sensing element 87 translates to the right from the position shown in FIG. 2, it will experience an upward force proportional to its displacement, and the control voltage v on the top and bottom electrodes.
- the sensing element and its scalloped edge projections 91 translate to the left from the position shown in FIG. 2, it will experience a downward force.
- the peak force will be experienced at the peak displacement and will be in phase with the peak quadrature force.
- a closed loop servo system (not shown), of a type well known in the art is utilized to adjust the control voltages v on the upper electrodes and lower electrodes to null the quadrature portion of the sensing element pickoff. Because this control voltage is d.c., there is no phase instability. Referring to FIG. 4, this means that the quadrature control 107 , which is adjusted to null the quadrature portion of the sensing element cause the pendulum to move about its flexure axis 89 to be continuously centered within the housing 81 . In this manner, neither the dither mass 93 nor the pendulum sensing mass 87 are coerced to move parallel to the housing axis 103 while still nulling quadrature error.
- FIGS. 5 - 10 An alternate preferred embodiment of the present invention is shown in FIGS. 5 - 10 .
- These figures illustrate a rotationally dithered proof mass which is disc-shaped.
- This disc-shaped proof mass is mounted within a ring-like dither mass which is suspended within a frame for rotational dither motion.
- the dither mass dithers about its Z axis which is perpendicular to the X-Y plane within which the ring shaped dither mass is located.
- a proof mass is mounted within the ring-shaped dither mass in the X-Y plane and rotates about an output axis Y for an input rate about the X axis. In other words, the proof mass oscillates about the Y torsion bar axis for an input rate on the X axis.
- FIGS. 5 and 6 which shows the general relationship between the disc-like proof mass 129 mounted within the ring-like dither mass 123 by a pair of torsion bar suspensions 127 , which lie along the Y axis of the proof mass 129 and dither mass 123 .
- the dither mass 123 is suspended by a plurality of dither drive beams 125 which, in this preferred embodiment, are four in number, to a frame 121 .
- the ring-like dither mass 123 is driven rotationally about a Z axis which is perpendicular to the X-Y plane, which is the plane of the paper, in a positive and negative direction 124 causing the proof mass 129 to also be rotationally dithered.
- the proof mass contains a plurality of teeth 131 around its circumference, creating a scalloped edge, the purpose of which will be explained hereinafter.
- a plurality of electrodes 135 located in the cover for the dither mass 123 forces the dither mass to rotationally dither about the Z axis.
- FIG. 6 is a three-dimensional partially broken away perspective showing the relationship of the proof mass 129 suspended within the ring-like dither mass 123 .
- the dither mass 123 is suspended by a plurality of dither drive beams 125 which is the only attachment to a frame 121 .
- the proof mass 129 is attached to the internal circumference of the ring-like dither mass 123 by a pair of torsion bars 127 , which lie along a Y axis 143 of the X-Y plane 147 , 143 within which the proof mass 129 and dither mass 123 lie.
- the bottom cover 135 which contains electrodes 138 therein for driving the dither mass in a back and forth dither motion 124 about the Z axis 145 .
- This rotational dither motion about the Z axis 145 also dithers the proof mass in the directions 149 , 151 .
- a plurality of quadrature nulling electrodes 137 which interact with the bottom teeth-like grooves 133 located about the circumference of the disc-like proof mass 129 .
- Teeth 131 are also located on the top surface of proof mass 129 around its circumference.
- the quadrature nulling electrodes 137 located in a semicircle in the cover are located with respect to the bottom teeth-like grooves 133 on the proof mass 129 .
- the electrodes 137 are preferably deposited titanium and gold electrodes on glass, like pyrex glass, for example.
- the top and bottom covers for the accelerometer-gyro are preferably made of pyrex glass.
- a positive d.c. voltage is supplied to half of the electrodes along the perimeter of the proof mass disc on line 139 .
- a negative d.c. voltage is supplied to the remaining electrodes on line 141 .
- the Z dither axis 145 may not be exactly perpendicular to the Y torsion axis 143 , causing unwanted oscillation to act about the Y torsion axis 143 as a result of this misalignment.
- the dither mass 123 is being driven in a rotational dither direction 124 about Z axis 145 , causing the proof mass 129 to be likewise dithered in the direction 149 on its right side, and the direction 151 on its left side.
- the top cover 136 for the accelerometer-gyro is illustrated as being fabricated from silicon with protruding teeth thereon that interact with the teeth 131 along the circumference of the disc-like proof mass 129 .
- the displacement of the teeth in the right side top cover 136 B, with respect to the teeth 131 and the displacement of the teeth in the left side top cover 136 A, with respect to the teeth 131 in the proof mass 129 are illustrated for the case of a peak positive dither amplitude.
- the forces 157 parallel to the Z axis on the left side top cover of the proof mass 129 are strong because the teeth are aligned, while the forces 158 on the right side top cover of the proof mass 129 are weak because the teeth are staggered.
- This differential creates a torque 153 about Y torsion bar axis 143 . Since the Y torsion bar axis 143 is the output axis for the accelerometer-gyro, this torque cancels the effect due to the unwanted oscillation from the misalignment of the Z dither axis 195 .
- FIGS. 8, 9, and 10 illustrate the relationship between the proof mass 129 and its teeth 131 around its perimeter with the electrodes 136 located on the top cover 136 A and 136 B and the electrodes 137 located on the bottom cover 135 A and 135 B.
- FIGS. 8, 9, and 10 illustrate the relationship between the proof mass 129 and the top and bottom covers and their respective electrodes when the dither motion 124 is at zero amplitude as a starting point.
- the dither mass 123 is at null about the Z axis 145 .
Abstract
Description
- 1. Field of the Invention
- The present invention relates to an inertial instrument and more specifically pertains to vibrating accelerometers used as multi-sensors for measuring linear acceleration and rate of rotation of a moving body.
- 2. Description of Prior Art
- Gyroscopes are well known for use as angular velocity and acceleration sensors for sensing angular velocity and acceleration which information is necessary for determining location, direction, position and velocity of a moving vehicle.
- The present invention utilizes two masses in tandem, a dither mass and a proof mass, or pendulum. Each mass has only a single degree of freedom. It is desired to have the dither mass move along an axis that is parallel to the plane of the housing. The driving forces on the dither mass causing its vibration do not act directly on the pendulum. These forces, however cause the dither mass to move out of the plane of the housing due to dither beam misalignments. This out-of-plane motion generates error signals which are in quadrature with the signals generated by rate inputs. Therefore, a high degree of phase discrimination is required to separate the rate signal from the quadrature signal. This invention uses a new quadrature nulling technique which eliminates the requirement for accurate phase and relaxes control of the dither beam alignment tolerances which generate out of plane motion. The present invention applies vibration driving signals to the dither mass to vibrate the dither mass and the proof mass at a combined resonant frequency, and applies a restoring force to the proof mass which is in phase with its dithered displacement. In an alternate embodiment, vibration driving signals are applied to the dither mass to vibrate the dither mass and proof mass which are in an X-Y plane at a combined resonant frequency about the Z axis of the X-Y plane. A restoring torque is applied to the proof mass which is in phase with its dithered displacement.
- The exact nature of this invention as well as its objects and advantages will become readily apparent from consideration of the following specification in relation to the accompanying drawings in which like reference numerals designate like parts throughout the figures thereof and wherein:
- FIG. 1 is a top plane view of the driven and sensing element of an accelerometer according to the present invention;
- FIG. 2 is a cross-section of the quadrature nulling projection on the end of the pendulum of FIG. 4;
- FIG. 3 is a diagrammatic illustration of the functional relationship of portions of the accelerometer of FIG. 1 and FIG. 4;
- FIG. 4 is a diagrammatic illustration of the pendulum and dither mass or vibrating structure of the present invention;
- FIG. 5 is a top plan view of an alternate configuration for the proof mass and dither mass of the present invention;
- FIG. 6 is a partial broken-away perspective of the configuration of FIG. 5 showing the relationship between the disc-shaped proof mass and the ring-shaped dither mass.
- FIG. 7 is a partial perspective showing the relationship between the proof mass of FIG. 5 with its top cover and the quadrature nulling electrodes;
- FIG. 8 is a top plan view of the disc-shaped proof mass with multiple teeth formed by etching grooves around its circumference;
- FIG. 9 is a left side plan view showing the edge of the disc-shaped proof mass between its top and bottom covers, each cover containing quadrature nulling electrodes; and
- FIG. 10 is a right side plan view showing the edge of the disc-shaped proof mass between its top and bottom covers, each cover containing quadrature nulling electrodes.
- The accelerometer gyro disclosed in an application for Micromachined Silicon Gyro Using Tuned-Accelerometer having U.S. patent application Ser. No. 09/778,434 filed on Feb. 7, 2001 and assigned to the same assignee as the present application illustrates a micromachined accelerometer-gyro having a pendulous mass or proof mass suspended within a dither mass that provides improved performance as the result of a considerable decrease in manufacturing flaws that affects performance of the accelerometer gyro.
- The present invention goes beyond structural improvement of the proof mass and dither base assembly and the manufacture thereof by providing a means for nulling the error created from manufacturing tolerances and electronic phase uncertainty. Referring to FIG. 4, a conceptual schematic of the structure of the pendulum or
proof mass 87 in association with thedither mass 93 is shown. Theproof mass 87 is attached to thedither mass 93 bypendulum flexure points 89. As illustrated, thedither mass 93 moves back and forth in thedirection 109. Because of the manufacturing flaws, the dithermass motion 109 is not exactly along theX axis 103 of thependulum 87. The actual dithermass motion 109 is off-axis by a dither misalignment angle 111, causing slight oscillation in theY direction 105. - If this displacement along the Y axis is differentiated twice, this acceleration is known as quadrature error. Quadrature error and Coriolis acceleration are very similar in that both are sinusoidal signals centered at the frequency of oscillation. However, quadrature error can be distinguished from Coriolis acceleration by the phase relative to the driven oscillation.
- A prior art approach to solving the problem presented by quadrature error is discussed in an article entitledSurface Micromachined Z-Axis Vibrating Rate Gyroscope authored by William A. Clark, Roger T. Howe, and Roberto Horwitz and published as a paper in Solid State Sensor And Actuator Workshop held in Hilton Head, S.C., Jun. 2-6, 1996. The approach suggested in the paper to null quadrature error is to apply a balancing force that is exactly proportional to position of the proof mass. The paper suggests that this can be achieved by using interdigitated position sensing fingers that sense position of the proof mass. As this proof mass oscillates, the position sensing fingers, which are position sense capacitors, change proportionately. A slight modification in the d.c. bias voltage applied to these fingers results in a net force applied to the proof mass that is directly proportional to the position of the proof mass thereby forcing the proof mass to vibrate along the desired dither axis, in other words, parallel to the X axis which is the housing axis for the proof mass.
- FIG. 4 illustrates in schematic form the structure of the dither mass or vibrating structure and the proof mass or pendulum structure of the present invention. In normal operation, the
dither mass 93 which is the vibrating structure for thependulum 87 oscillates off-axis by an angle 111 alongdirection 109. This off-axis vibration of thedither mass 93 is inherent in the construction of the rate sensor of the present invention. This is the best that can be done in the manufacturing process. This means that the dither mass and pendulum will naturally dither in the direction which is primarily along theX axis 103 but will also dither alongY axis 105 because of a misalignment angle 111 caused by mechanical imperfections of the dither driving beams during the etching phase of the fabrication. - As will be noted, the
pendulum 87 is attached to thedither base 93 by thependulum flexures 89. In operation, thependulum 87 senses Coriolis acceleration causing the pendulum to rotate about theflexure 89. The present invention, in contrast to the approach in the above noted article, rather than forcing thedither base 93 andpendulum 87 to vibrate along the desired dither orX axis 103, which is parallel to the housing axis, allows thedither base 93 to vibrate along themisaligned direction 109. Thequadrature control electrodes 107 of the present invention do not force thedither base 93 to vibrate along theX axis 103. Thequadrature control electrodes 107 only exert forces on thependulum mass 87 to cause pendulum motion about theflexure axis 89 so that the pendulum continuously centers within thehousing 81 as sensed by the pickoff. In this manner, neither thedither base 93 nor thependulum mass 87 are coerced to move along a certain axis, likeX axis 103. - As shown in FIG. 1, the angular rate sensor according to the present invention is constructed to have a pendulum or
sensing element 87 which is attached byflexures 89 to the dither mass orvibrating structure 93 which has dither drive andpickoff electrodes elements 83 mounted thereon. Thedither mass 93 is mounted for motion within the plane of the paper of FIG. 1 within aframe 81. Thedither mass 93 has a plurality offlexure suspensions 85 therein to permit the dither motion along theX axis 103. - The mechanical misalignment illustrated graphically in FIG. 4, along with phase error of the dither reference signal are the major source of bias instability, non-repeatability and temperature sensitivity of tuned Coriolis angular rate sensors. The present invention provides a method to servo the quadrature error signal to null. Since the servo signal is d.c., there is no resulting phase sensitivity. The result is improved bias stability, repeatability and reduced temperature sensitivity, in addition to relaxing the tolerance requirements on etching the dither beams and the tolerance requirements on the system digital electronics phase stability. The present invention is contrary to the traditional manner of controlling bias error. The traditional approach was to attempt exceptionally close tolerances on the etching of the dither beams and attempt to achieve exceptionally close system tolerances on the digital electronics phase stability circuitry.
- The concept of the invention is to introduce a torque to the sensing element or
pendulum 87 by the application of d.c. signals which results in an a.c. restoring force that is in phase with the dither displacement. Such a torque or forcer can be used to servo the quadrature error signal to null because the quadrature signal is in phase with acceleration which in turn is in phase with the dither displacement. - FIG. 2 is a diagram of a quadrature nulling forcer as envisioned by the present invention. FIG. 2 is a cross-section of the present invention taken through the region containing the
top electrodes bottom electrodes scalloped edge 91 of thesensing element 87. - The
top electrodes bottom electrodes electrode segment edge 91 of the sensing element so that both polarities of the alternate segments have equal areas overlapping each projection along the scallopededge 91 of thesensing element 87 when the dither motion is not excited. - In operation, the quadrature nulling forcer exerts a force as depicted in the graph of FIG. 3. Assuming that the quadrature acceleration is in phase with displacement of the sensing element (pendulum87), a bias voltage +V is applied to the sensing element and plus or minus d.c. control voltages v are applied to the
top electrodes bottom electrodes sensing element 87 translates to the right from the position shown in FIG. 2, it will experience an upward force proportional to its displacement, and the control voltage v on the top and bottom electrodes. Conversely, as the sensing element and itsscalloped edge projections 91 translate to the left from the position shown in FIG. 2, it will experience a downward force. The peak force will be experienced at the peak displacement and will be in phase with the peak quadrature force. - In operation, a closed loop servo system (not shown), of a type well known in the art is utilized to adjust the control voltages v on the upper electrodes and lower electrodes to null the quadrature portion of the sensing element pickoff. Because this control voltage is d.c., there is no phase instability. Referring to FIG. 4, this means that the
quadrature control 107, which is adjusted to null the quadrature portion of the sensing element cause the pendulum to move about itsflexure axis 89 to be continuously centered within thehousing 81. In this manner, neither thedither mass 93 nor thependulum sensing mass 87 are coerced to move parallel to thehousing axis 103 while still nulling quadrature error. This allows thedither mass 93 to move along itsmisaligned path 109 relative to the housing generating motion along theY output axis 105 but still have the resulting quadrature error nulled. This approach to quadrature error nulling is generally applicable to rate sensors having a certain structure. - This quadrature error nulling method is possible because the two masses in operation in the present rate sensor structure are in tandem, with each mass having only a single degree of freedom. In other words, the
dither mass 93 is attached to thependulous mass 87 by theflexure 89. As a result, the dither forces act only on the dither mass and not on thependulous mass 87. - An alternate preferred embodiment of the present invention is shown in FIGS.5-10. These figures illustrate a rotationally dithered proof mass which is disc-shaped. This disc-shaped proof mass is mounted within a ring-like dither mass which is suspended within a frame for rotational dither motion. The dither mass dithers about its Z axis which is perpendicular to the X-Y plane within which the ring shaped dither mass is located. A proof mass is mounted within the ring-shaped dither mass in the X-Y plane and rotates about an output axis Y for an input rate about the X axis. In other words, the proof mass oscillates about the Y torsion bar axis for an input rate on the X axis.
- Referring first to FIGS. 5 and 6, which shows the general relationship between the disc-
like proof mass 129 mounted within the ring-like dither mass 123 by a pair oftorsion bar suspensions 127, which lie along the Y axis of theproof mass 129 and dithermass 123. Thedither mass 123 is suspended by a plurality of dither drive beams 125 which, in this preferred embodiment, are four in number, to aframe 121. - The ring-
like dither mass 123 is driven rotationally about a Z axis which is perpendicular to the X-Y plane, which is the plane of the paper, in a positive andnegative direction 124 causing theproof mass 129 to also be rotationally dithered. The proof mass contains a plurality ofteeth 131 around its circumference, creating a scalloped edge, the purpose of which will be explained hereinafter. A plurality ofelectrodes 135 located in the cover for thedither mass 123 forces the dither mass to rotationally dither about the Z axis. - FIG. 6 is a three-dimensional partially broken away perspective showing the relationship of the
proof mass 129 suspended within the ring-like dither mass 123. Thedither mass 123 is suspended by a plurality of dither drive beams 125 which is the only attachment to aframe 121. Theproof mass 129, in turn, is attached to the internal circumference of the ring-like dither mass 123 by a pair oftorsion bars 127, which lie along aY axis 143 of theX-Y plane proof mass 129 and dithermass 123 lie. - Shown partially broken away is the
bottom cover 135 which containselectrodes 138 therein for driving the dither mass in a back and forth dithermotion 124 about theZ axis 145. This rotational dither motion about theZ axis 145 also dithers the proof mass in thedirections - Also located in the
bottom cover 135 are a plurality ofquadrature nulling electrodes 137 which interact with the bottom teeth-like grooves 133 located about the circumference of the disc-like proof mass 129.Teeth 131 are also located on the top surface ofproof mass 129 around its circumference. - The
quadrature nulling electrodes 137 located in a semicircle in the cover are located with respect to the bottom teeth-like grooves 133 on theproof mass 129. Theelectrodes 137 are preferably deposited titanium and gold electrodes on glass, like pyrex glass, for example. The top and bottom covers for the accelerometer-gyro are preferably made of pyrex glass. A positive d.c. voltage is supplied to half of the electrodes along the perimeter of the proof mass disc online 139. A negative d.c. voltage is supplied to the remaining electrodes online 141. These d.c. voltages effectuate quadrature nulling in a manner which will be more fully explained hereinafter. - In operation, while the ring-
like dither mass 123 is rotationally dithered about the Z axis causing theproof mass 129 to also be dithered about the Z axis, an input rate along theX axis 147 will cause theproof mass 129 to oscillate about theY torsion axis 143 in anoscillatory motion 153 about theY torsion axis 143. - Because of manufacturing tolerances, the
Z dither axis 145 may not be exactly perpendicular to theY torsion axis 143, causing unwanted oscillation to act about theY torsion axis 143 as a result of this misalignment. As shown in FIG. 7, thedither mass 123 is being driven in arotational dither direction 124 aboutZ axis 145, causing theproof mass 129 to be likewise dithered in thedirection 149 on its right side, and thedirection 151 on its left side. Thetop cover 136 for the accelerometer-gyro is illustrated as being fabricated from silicon with protruding teeth thereon that interact with theteeth 131 along the circumference of the disc-like proof mass 129. The displacement of the teeth in the right sidetop cover 136B, with respect to theteeth 131 and the displacement of the teeth in the left sidetop cover 136A, with respect to theteeth 131 in theproof mass 129 are illustrated for the case of a peak positive dither amplitude. In this situation, theforces 157 parallel to the Z axis on the left side top cover of theproof mass 129 are strong because the teeth are aligned, while theforces 158 on the right side top cover of theproof mass 129 are weak because the teeth are staggered. This differential creates atorque 153 about Ytorsion bar axis 143. Since the Ytorsion bar axis 143 is the output axis for the accelerometer-gyro, this torque cancels the effect due to the unwanted oscillation from the misalignment of the Z dither axis 195. - FIGS. 8, 9, and10, illustrate the relationship between the
proof mass 129 and itsteeth 131 around its perimeter with theelectrodes 136 located on thetop cover electrodes 137 located on thebottom cover 135A and 135B. - FIGS. 8, 9, and10, illustrate the relationship between the
proof mass 129 and the top and bottom covers and their respective electrodes when thedither motion 124 is at zero amplitude as a starting point. In other words, thedither mass 123 is at null about theZ axis 145. - As the dither mass moves from this null position in a positive direction causing the
proof mass 129 to also move in apositive direction 149, the capacitance 179 betweenelectrodes 136 and theteeth 131 of theproof mass 129 gets bigger because the teeth are becoming more aligned with the electrodes. At the same time, the capacitance 177 betweenelectrodes 136 and theteeth 131 of theproof mass 129 on the left side become smaller. This causes the upward force FTR on the right side acting on the paddle to increase, while the upward force FTL on the left side becomes quite low. This difference in upward force between the left and right side of theproof mass 129 causes a torque to be developed about thetorsion Y axis 143 which, in turn, causes theproof mass 129 to rotate about thetorsion Y axis 143. - When the dither mass goes into a negative direction causing
proof mass 129 to also go in anegative direction 151, the capacitance 179 on the right side gets smaller, while the capacitance 177 on the left side gets larger. This causes the upward force FTL on the left side to become large and the upward force FTR on the right side to become low, thereby reversing the torque on theY axis 143 of the proof mass, which causes theproof mass 129 to move in the opposite direction about the Ytorsion bar axis 143. In essence then, a sinusoidal torque acts on theproof mass 129 causing it to oscillate about the Ytorsion bar axis 143 exactly in phase with the dither amplitude. That is, peak torque on theproof mass 129 occurs exactly when there is peak displacement for thedither motion 124 aboutZ axis 145. - These oscillating forces, FTR and FTL, acting on the
proof mass 129 can be servoed by automatically controlling the voltages VQ onlines lines 171 and 173 on the top cover, to thereby cancel the torque aboutY axis 143, which is due to misalignment of theZ dither axis 145. - The cancellation of the torque generated about the torsion
bar Y axis 143, as a result of theZ dither axis 145 not being perpendicular to theY axis 143, results in considerably improved performance.
Claims (42)
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/915,026 US6619121B1 (en) | 2001-07-25 | 2001-07-25 | Phase insensitive quadrature nulling method and apparatus for coriolis angular rate sensors |
TW091110196A TW534991B (en) | 2001-07-25 | 2002-05-16 | Phase insensitive quadrature nulling method and apparatus for Coriolis angular rate sensors |
EP02759137A EP1412698A1 (en) | 2001-07-25 | 2002-06-04 | Phase insensitive quadrature nulling method and apparatus for coriolis angular rate sensors |
PCT/US2002/022073 WO2003010492A1 (en) | 2001-07-25 | 2002-06-04 | Phase insensitive quadrature nulling method and apparatus for coriolis angular rate sensors |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/915,026 US6619121B1 (en) | 2001-07-25 | 2001-07-25 | Phase insensitive quadrature nulling method and apparatus for coriolis angular rate sensors |
Publications (2)
Publication Number | Publication Date |
---|---|
US20030159510A1 true US20030159510A1 (en) | 2003-08-28 |
US6619121B1 US6619121B1 (en) | 2003-09-16 |
Family
ID=25435097
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/915,026 Expired - Lifetime US6619121B1 (en) | 2001-07-25 | 2001-07-25 | Phase insensitive quadrature nulling method and apparatus for coriolis angular rate sensors |
Country Status (4)
Country | Link |
---|---|
US (1) | US6619121B1 (en) |
EP (1) | EP1412698A1 (en) |
TW (1) | TW534991B (en) |
WO (1) | WO2003010492A1 (en) |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2005066585A1 (en) * | 2003-12-23 | 2005-07-21 | Litef Gmbh | Method for compensating a coriolis gyroscope quadrature bias and a coriolis gyroscope for carrying out said method |
WO2009043967A1 (en) * | 2007-10-05 | 2009-04-09 | Vti Technologies Oy | Vibrating micromechanical sensor of angular velocity |
DE102009019318A1 (en) * | 2009-04-30 | 2011-03-24 | Continental Teves Ag & Co. Ohg | Method for precise measurement operation of a micromechanical rotation rate sensor |
US20130199263A1 (en) * | 2010-03-17 | 2013-08-08 | Continental Teves Ag & Co. Ohg | Method for the decoupled control of the quadrature and the resonance frequency of a micro-mechanical gyroscope |
US20140144231A1 (en) * | 2012-11-28 | 2014-05-29 | Freescale Semiconductor, Inc. | Inertial sensor and method of levitation effect compensation |
US9535084B2 (en) | 2010-03-17 | 2017-01-03 | Continental Teves Ag & Co. Ohg | Method for the decoupled control of the quadrature and the resonance frequency of a micro-mechanical rotation rate sensor by means of sigma-delta-modulation |
US20170016724A1 (en) * | 2014-04-23 | 2017-01-19 | Denso Corporation | Angular velocity sensor |
US20180031601A1 (en) * | 2016-07-27 | 2018-02-01 | Lumedyne Technologies Incorporated | Composite vibratory in-plane accelerometer |
US10234476B2 (en) | 2015-05-20 | 2019-03-19 | Google Llc | Extracting inertial information from nonlinear periodic signals |
Families Citing this family (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6474160B1 (en) | 2001-05-24 | 2002-11-05 | Northrop Grumman Corporation | Counterbalanced silicon tuned multiple accelerometer-gyro |
US6854315B2 (en) * | 2002-04-22 | 2005-02-15 | Northrop Grumman Corporation | Quadrature compensation technique for vibrating gyroscopes |
US6868725B2 (en) * | 2003-04-23 | 2005-03-22 | Northrop Grumman Corporation | Hinge position location that causes pendulous axis to be substantially parallel with drive component direction |
JP4534741B2 (en) * | 2004-12-10 | 2010-09-01 | 株式会社デンソー | Gyro sensor |
FI116544B (en) * | 2004-12-31 | 2005-12-15 | Vti Technologies Oy | Oscillating, micro-mechanical angular velocity sensor has stationary electrode pairs together with surface of mass forming two capacitance which varies as function of angle of rotation of primary motion of mass |
US7231824B2 (en) * | 2005-03-22 | 2007-06-19 | Honeywell International Inc. | Use of electrodes to cancel lift effects in inertial sensors |
US7213458B2 (en) * | 2005-03-22 | 2007-05-08 | Honeywell International Inc. | Quadrature reduction in MEMS gyro devices using quad steering voltages |
US7251900B2 (en) * | 2005-10-26 | 2007-08-07 | Guy Thomas Varty | Methods and systems utilizing intermediate frequencies to control multiple coriolis gyroscopes |
US7296468B2 (en) * | 2005-10-26 | 2007-11-20 | Litton Systems, Inc. | Digital coriolis gyroscope |
US7444868B2 (en) | 2006-06-29 | 2008-11-04 | Honeywell International Inc. | Force rebalancing for MEMS inertial sensors using time-varying voltages |
CN100439864C (en) * | 2007-06-01 | 2008-12-03 | 北京沃尔康科技有限责任公司 | Novel silicon micromechanical peg-top |
EP2098823B1 (en) | 2008-03-05 | 2016-10-19 | Colibrys S.A. | Accelerometer with offset compensation |
EP2098822B8 (en) * | 2008-03-05 | 2015-08-12 | Colibrys S.A. | Vibrating gyroscope with quadrature signals reduction |
DE102008044053B4 (en) | 2008-11-25 | 2022-07-14 | Robert Bosch Gmbh | Quadrature compensation for a yaw rate sensor |
TWI592779B (en) * | 2010-04-21 | 2017-07-21 | 三角設計公司 | System and method for accelerating a device |
Family Cites Families (35)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4336718A (en) | 1980-09-08 | 1982-06-29 | Lear Siegler, Inc. | Control circuit for accelerometer |
CH642461A5 (en) | 1981-07-02 | 1984-04-13 | Centre Electron Horloger | ACCELEROMETER. |
US4553436A (en) | 1982-11-09 | 1985-11-19 | Texas Instruments Incorporated | Silicon accelerometer |
FR2541775B1 (en) | 1983-02-28 | 1985-10-04 | Onera (Off Nat Aerospatiale) | ELECTROSTATIC SUSPENSION ACCELEROMETERS |
US4510802A (en) | 1983-09-02 | 1985-04-16 | Sundstrand Data Control, Inc. | Angular rate sensor utilizing two vibrating accelerometers secured to a parallelogram linkage |
US4512192A (en) | 1983-09-02 | 1985-04-23 | Sundstrand Data Control, Inc. | Two axis angular rate and specific force sensor utilizing vibrating accelerometers |
US4592233A (en) | 1983-09-02 | 1986-06-03 | Sundstrand Data Control, Inc. | Angular base sensor utilizing parallel vibrating accelerometers |
GB2146697B (en) | 1983-09-17 | 1986-11-05 | Stc Plc | Flexible hinge device |
US4584885A (en) | 1984-01-20 | 1986-04-29 | Harry E. Aine | Capacitive detector for transducers |
US4699006A (en) | 1984-03-19 | 1987-10-13 | The Charles Stark Draper Laboratory, Inc. | Vibratory digital integrating accelerometer |
US4679434A (en) | 1985-07-25 | 1987-07-14 | Litton Systems, Inc. | Integrated force balanced accelerometer |
US4744248A (en) | 1985-07-25 | 1988-05-17 | Litton Systems, Inc. | Vibrating accelerometer-multisensor |
JPS6293668A (en) | 1985-10-21 | 1987-04-30 | Hitachi Ltd | Angular speed/acceleration detector |
US4795258A (en) | 1987-04-06 | 1989-01-03 | Litton Systems, Inc. | Nonplanar three-axis ring laser gyro with shared mirror faces |
US4841773A (en) | 1987-05-01 | 1989-06-27 | Litton Systems, Inc. | Miniature inertial measurement unit |
US4766768A (en) | 1987-10-22 | 1988-08-30 | Sundstrand Data Control, Inc. | Accelerometer with isolator for common mode inputs |
US5016072A (en) | 1988-01-13 | 1991-05-14 | The Charles Stark Draper Laboratory, Inc. | Semiconductor chip gyroscopic transducer |
US4945765A (en) | 1988-08-31 | 1990-08-07 | Kearfott Guidance & Navigation Corp. | Silicon micromachined accelerometer |
US5007289A (en) | 1988-09-30 | 1991-04-16 | Litton Systems, Inc. | Three axis inertial measurement unit with counterbalanced, low inertia mechanical oscillator |
US5025346A (en) | 1989-02-17 | 1991-06-18 | Regents Of The University Of California | Laterally driven resonant microstructures |
US4996877A (en) | 1989-02-24 | 1991-03-05 | Litton Systems, Inc. | Three axis inertial measurement unit with counterbalanced mechanical oscillator |
US5008774A (en) | 1989-02-28 | 1991-04-16 | United Technologies Corporation | Capacitive accelerometer with mid-plane proof mass |
US5006487A (en) | 1989-07-27 | 1991-04-09 | Honeywell Inc. | Method of making an electrostatic silicon accelerometer |
US5065627A (en) | 1990-03-20 | 1991-11-19 | Litton Systems, Inc. | Three axis inertial measurement unit with counterbalanced, low inertia mechanical oscillator |
US5277053A (en) * | 1990-04-25 | 1994-01-11 | Litton Systems, Inc. | Square law controller for an electrostatic force balanced accelerometer |
US5205171A (en) | 1991-01-11 | 1993-04-27 | Northrop Corporation | Miniature silicon accelerometer and method |
US5241861A (en) | 1991-02-08 | 1993-09-07 | Sundstrand Corporation | Micromachined rate and acceleration sensor |
US5481914A (en) * | 1994-03-28 | 1996-01-09 | The Charles Stark Draper Laboratory, Inc. | Electronics for coriolis force and other sensors |
US5987986A (en) | 1994-07-29 | 1999-11-23 | Litton Systems, Inc. | Navigation grade micromachined rotation sensor system |
US5992233A (en) * | 1996-05-31 | 1999-11-30 | The Regents Of The University Of California | Micromachined Z-axis vibratory rate gyroscope |
US5932803A (en) | 1997-08-01 | 1999-08-03 | Litton Systems, Inc. | Counterbalanced triaxial multisensor with resonant accelerometers |
US6122961A (en) * | 1997-09-02 | 2000-09-26 | Analog Devices, Inc. | Micromachined gyros |
US6230563B1 (en) | 1998-06-09 | 2001-05-15 | Integrated Micro Instruments, Inc. | Dual-mass vibratory rate gyroscope with suppressed translational acceleration response and quadrature-error correction capability |
DE19939399A1 (en) | 1999-08-19 | 2001-02-22 | Niehoff Kg Maschf | Annealing device for annealing metallic billets containing aluminum has contact elements made of electrically conducting material electrically connected to a voltage source |
DE19939998A1 (en) | 1999-08-24 | 2001-03-01 | Bosch Gmbh Robert | Device for generating bias voltage for a vibrating yaw rate sensor |
-
2001
- 2001-07-25 US US09/915,026 patent/US6619121B1/en not_active Expired - Lifetime
-
2002
- 2002-05-16 TW TW091110196A patent/TW534991B/en not_active IP Right Cessation
- 2002-06-04 WO PCT/US2002/022073 patent/WO2003010492A1/en not_active Application Discontinuation
- 2002-06-04 EP EP02759137A patent/EP1412698A1/en not_active Withdrawn
Cited By (20)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2005066585A1 (en) * | 2003-12-23 | 2005-07-21 | Litef Gmbh | Method for compensating a coriolis gyroscope quadrature bias and a coriolis gyroscope for carrying out said method |
US20070144255A1 (en) * | 2003-12-23 | 2007-06-28 | Eberhard Handrich | Method for quadrature-bias compensation in a coriolis gyro, as well as a coriolis gyro which is suitable for this purpose |
US7481110B2 (en) | 2003-12-23 | 2009-01-27 | Litef Gmbh | Method for quadrature-bias compensation in a Coriolis gyro, as well as a Coriolis gyro which is suitable for this purpose |
US8104343B2 (en) | 2007-10-05 | 2012-01-31 | Vti Technologies Oy | Vibrating micromechanical sensor of angular velocity |
US20090165553A1 (en) * | 2007-10-05 | 2009-07-02 | Vti Technologies Oy | Vibrating micromechanical sensor of angular velocity |
US8635909B2 (en) | 2007-10-05 | 2014-01-28 | Murata Electronics Oy | Vibrating micromechanical sensor of angular velocity |
US8646333B2 (en) | 2007-10-05 | 2014-02-11 | Murata Electronics Oy | Vibrating micromechanical sensor of angular velocity |
WO2009043967A1 (en) * | 2007-10-05 | 2009-04-09 | Vti Technologies Oy | Vibrating micromechanical sensor of angular velocity |
DE102009019318A1 (en) * | 2009-04-30 | 2011-03-24 | Continental Teves Ag & Co. Ohg | Method for precise measurement operation of a micromechanical rotation rate sensor |
US8794047B2 (en) | 2009-04-30 | 2014-08-05 | Continental Teves Ag & Co. Ohg | Method for the precise measuring operation of a micromechanical rotation rate sensor |
US9377483B2 (en) * | 2010-03-17 | 2016-06-28 | Continental Teves Ag & Co. Ohg | Method for the decoupled control of the quadrature and the resonance frequency of a micro-mechanical gyroscope |
US20130199263A1 (en) * | 2010-03-17 | 2013-08-08 | Continental Teves Ag & Co. Ohg | Method for the decoupled control of the quadrature and the resonance frequency of a micro-mechanical gyroscope |
US9535084B2 (en) | 2010-03-17 | 2017-01-03 | Continental Teves Ag & Co. Ohg | Method for the decoupled control of the quadrature and the resonance frequency of a micro-mechanical rotation rate sensor by means of sigma-delta-modulation |
US20140144231A1 (en) * | 2012-11-28 | 2014-05-29 | Freescale Semiconductor, Inc. | Inertial sensor and method of levitation effect compensation |
US9335170B2 (en) * | 2012-11-28 | 2016-05-10 | Freescale Semiconductor, Inc. | Inertial sensor and method of levitation effect compensation |
US20170016724A1 (en) * | 2014-04-23 | 2017-01-19 | Denso Corporation | Angular velocity sensor |
US10132631B2 (en) * | 2014-04-23 | 2018-11-20 | Denso Corporation | Angular velocity sensor |
US10234476B2 (en) | 2015-05-20 | 2019-03-19 | Google Llc | Extracting inertial information from nonlinear periodic signals |
US20180031601A1 (en) * | 2016-07-27 | 2018-02-01 | Lumedyne Technologies Incorporated | Composite vibratory in-plane accelerometer |
US10234477B2 (en) * | 2016-07-27 | 2019-03-19 | Google Llc | Composite vibratory in-plane accelerometer |
Also Published As
Publication number | Publication date |
---|---|
TW534991B (en) | 2003-06-01 |
US6619121B1 (en) | 2003-09-16 |
EP1412698A1 (en) | 2004-04-28 |
WO2003010492A1 (en) | 2003-02-06 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6619121B1 (en) | Phase insensitive quadrature nulling method and apparatus for coriolis angular rate sensors | |
US6561029B2 (en) | Rotational rate gyroscope with decoupled orthogonal primary and secondary oscillations | |
US5392650A (en) | Micromachined accelerometer gyroscope | |
US6883361B2 (en) | Quadrature compensation technique for vibrating gyroscopes | |
US6250156B1 (en) | Dual-mass micromachined vibratory rate gyroscope | |
EP2467675B1 (en) | Offset detection and compensation for micromachined inertial sensors | |
US6481283B1 (en) | Coriolis oscillating gyroscopic instrument | |
US5987986A (en) | Navigation grade micromachined rotation sensor system | |
US6837107B2 (en) | Micro-machined multi-sensor providing 1-axis of acceleration sensing and 2-axes of angular rate sensing | |
US6860151B2 (en) | Methods and systems for controlling movement within MEMS structures | |
US7565839B2 (en) | Bias and quadrature reduction in class II coriolis vibratory gyros | |
US7213458B2 (en) | Quadrature reduction in MEMS gyro devices using quad steering voltages | |
US6701786B2 (en) | Closed loop analog gyro rate sensor | |
JP3834397B2 (en) | Rate sensor | |
EP1440321B1 (en) | Angular rate sensor having a sense element constrained to motion about a single axis and flexibly attached to a rotary drive mass | |
US6715352B2 (en) | Method of designing a flexure system for tuning the modal response of a decoupled micromachined gyroscope and a gyroscoped designed according to the method | |
US6474160B1 (en) | Counterbalanced silicon tuned multiple accelerometer-gyro | |
US6374672B1 (en) | Silicon gyro with integrated driving and sensing structures | |
US20040129076A1 (en) | Methods and systems for actively controlling movement within mems structures | |
EP3798642B1 (en) | Coriolis vibratory accelerometer system | |
WO2000006971A1 (en) | Micromachined rotation sensor with modular sensor elements |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: LITTON SYSTEMS, INC., CALIFORNIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:STEWART, ROBERT E.;WYSE, STANLEY F.;REEL/FRAME:012027/0229 Effective date: 20010719 |
|
AS | Assignment |
Owner name: NORTHROP GRUMANN CORPORATION, CALIFORNIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:LITTON SYSTEMS, INC.;REEL/FRAME:012895/0674 Effective date: 20020429 |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
AS | Assignment |
Owner name: LITTON SYSTEMS, INC., CALIFORNIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:NORTHROP GRUMMAN CORPORATION;REEL/FRAME:018148/0388 Effective date: 20060621 |
|
FPAY | Fee payment |
Year of fee payment: 4 |
|
FEPP | Fee payment procedure |
Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
AS | Assignment |
Owner name: NORTHROP GRUMMAN SYSTEMS CORPORATION, CALIFORNIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:NORTHROP GRUMMAN CORPORATION;REEL/FRAME:025597/0505 Effective date: 20110104 |
|
FPAY | Fee payment |
Year of fee payment: 8 |
|
FPAY | Fee payment |
Year of fee payment: 12 |