阅读说明：本技术 一种减小偏置漂移的多轴陀螺仪
(Multi-axis gyroscope capable of reducing bias drift
) 是由 森克·阿卡尔
布伦顿·罗丝·西蒙
散蒂帕·迈蒂 于 2019-11-01 设计创作，主要内容包括：一种微机械陀螺仪,包括悬挂在附接到衬底上的至少一个锚上的动态质量块。动态质量块包括一第一质量块和一第二质量块；一第一驱动致动器,其被配置成在陀螺仪的旋转振荡模式下在第一方向上驱动第一质量块；以及一第二驱动致动器,其被配置成在陀螺仪的旋转振荡模式中以相反方向驱动第二质量块。(A micromachined gyroscope includes a dynamic mass suspended from at least one anchor attached to a substrate. The dynamic mass block comprises a first mass block and a second mass block; a first drive actuator configured to drive the first mass in a first direction in a rotational oscillation mode of the gyroscope; and a second drive actuator configured to drive the second mass in an opposite direction in a rotational oscillation mode of the gyroscope.)
1. A micromachined gyroscope, comprising:
a substrate;
a dynamic mass suspended from at least one anchor attached to the substrate, the dynamic mass comprising a first mass and a second mass;
a first drive actuator configured to drive the first proof mass in one direction in a rotational oscillation mode of the gyroscope; and
a second drive actuator configured to drive the second proof mass in an opposite direction in a rotational oscillation mode of the gyroscope.
2. The micromachined gyroscope of claim 1, wherein the first proof-mass and the second proof-mass are flexure coupled by opposing phase suspensions that expand and contract to accommodate mechanical displacement of the proof-masses toward and away from each other.
3. The micromachined gyroscope of claim 1, wherein the first portion of the first proof-mass is distributed over a first quadrant, the second portion of the first proof-mass is distributed over a third pair of quadrants of the gyroscope, and the first portion and the second portion are connected by a beam at a central region of the gyroscope.
4. The micromachined gyroscope of claim 1, wherein the first portion of the second proof-mass is distributed over a second quadrant, the second portion of the second proof-mass is distributed over a fourth pair of quadrants of the gyroscope, and a beam along an edge of the gyroscope connects the first and second portions of the second proof-mass.
5. The micromachined gyroscope of claim 1, further comprising:
one or more out-of-plane sense electrodes disposed on the substrate for detecting X-axis and Y-axis accelerations of the proof mass.
6. The micromachined gyroscope of claim 5, wherein one or more out-of-plane sense electrodes for detecting X-axis and Y-axis accelerations of the proof mass are disposed on the substrate midway between the gyroscope center and the gyroscope edges.
7. The micromachined gyroscope of claim 6, wherein the first drive actuator, second drive actuator, and drive sense electrodes are arranged in a plane of the proof mass toward the edges of the gyroscope a distance from the center of the gyroscope that is greater than a distance at which the one or more out-of-plane sense electrodes are arranged.
8. The micromachined gyroscope of claim 1, wherein the first proof mass has an X-shape with arms extending from a center of the gyroscope to four corners of the gyroscope.
9. The micromachined gyroscope of claim 8, wherein the second proof-mass is flexibly suspended on the first proof-mass via a gyroscope central suspension, the second proof-mass having four portions distributed inward from gyroscope edges in four valleys formed by the X-shape of the first proof-mass, wherein the second proof-mass further comprises beams disposed along the gyroscope edges, the beams connecting the four portions of the second proof-mass.
10. The micromachined gyroscope of claim 9, wherein the first drive actuator, second drive actuator, and a drive sense electrode are disposed in the plane of the proof mass between the center of the gyroscope and the edge of the gyroscope.
11. The micromachined gyroscope of claim 10, further comprising:
one or more out-of-plane sense electrodes configured to detect X-axis and Y-axis accelerations of the proof mass, the one or more out-of-plane sense electrodes disposed on the substrate towards an edge of the gyroscope.
12. A micromachined gyroscope, comprising:
a substrate;
a static mass block fixed on the substrate; and
a dynamic mass comprising a first, a second, a third and a fourth wedge-shaped mass, each of the four wedge-shaped masses being distributed over a respective quadrant of the gyroscope and being suspended in flexure from the static mass by a central suspension of the gyroscope.
13. The micromachined gyroscope of claim 12, wherein each wedge-shaped mass is coupled to an adjacent wedge-shaped mass by an anti-phase suspension flexure that expands and contracts to accommodate mechanical displacement of the masses toward and away from each other.
14. The micromachined gyroscope of claim 13, wherein the first and second drive actuators are disposed on the first wedge-shaped proof-mass, the first and second drive actuators configured to drive the first wedge-shaped proof-mass toward and away from an adjacent wedge-shaped proof-mass in a rotational oscillation mode of the gyroscope.
15. The micromachined gyroscope of claim 14, wherein drive sense electrodes are disposed on a third wedge mass in a quadrant opposite the first wedge mass.
16. The micromachined gyroscope of claim 14, further comprising:
one or more out-of-plane sense electrodes configured to detect X-axis and Y-axis accelerations of the proof mass, the one or more out-of-plane sense electrodes disposed on the substrate toward an edge of the gyroscope.
17. The micromachined gyroscope of claim 14, further comprising: a beam disposed along the gyroscope edge connecting the four wedge-shaped mass beams.
18. A method, comprising:
suspending a dynamic mass arrangement of a gyroscope from at least one anchor attached to a substrate;
providing a plurality of masses in the dynamic mass configuration;
providing a plurality of drive actuators to drive the plurality of masses in a rotational oscillation mode of the gyroscope; and
the mass distribution of the plurality of masses is configured to have an equivalent contribution to angular momentum when the plurality of masses are driven at respective angular velocities by the drive actuator at a resonant state of the rotational oscillation mode.
19. The method of claim 18, wherein the plurality of masses comprises coupled pairs of adjacent masses having anti-phase suspension flexures.
20. The method of claim 19, further comprising:
in a resonant state of the rotational oscillation mode, adjacent masses are back-driven to cancel angular momentum of the dynamic mass configuration.
Technical Field
The invention relates to a micromechanical multi-axis gyroscope.
Background
A micromechanical gyroscope is an inertial sensor used to measure angular rate. Multiple single-axis or multi-axis micromechanical systems (MEMS) gyroscopes have been integrated into various systems, such as, but not limited to, smartphones, wearable electronic systems, augmented reality virtual reality devices, gaming machines, drones, and the like. However, output bias drift can affect the accuracy and precision of the information generated by the MEMS gyroscope. One major source of such bias drift is the energy leakage of the gyroscope drive motion driving the sense mode.
Drawings
Fig. 1 shows a 3 degree of freedom (3 degrees of freedom) Inertial Measurement Unit (IMU).
Fig. 2 shows an example gyroscope with a first dynamic mass configuration of two masses.
Fig. 3 shows a view of the anchor suspension flexures and center suspension flexure in the gyroscope of fig. 2.
Fig. 4 shows a first state of counterclockwise rotation of the first mass and clockwise rotation of the second mass in the gyroscope of fig. 2.
Fig. 5 shows a second state of clockwise rotation of the first mass and counterclockwise rotation of the second mass in the gyroscope of fig. 2.
FIG. 6 illustrates compressive motion of the gyroscope of FIG. 2 driven by Z-axis rate sensing electrodes to sense a Coriolis rate response.
FIG. 7 illustrates the expansive motion of the gyroscope of FIG. 2 driven by Z-axis rate sensing electrodes to sense the Coriolis rate response.
Fig. 8 and 9 illustrate examples of motion of the gyroscope of fig. 2 driven by X-axis rate sense electrodes and by Y-axis rate sense electrodes, respectively, to sense a coriolis rate response.
FIG. 10 shows tilt displacement of the gyroscope of FIG. 2 driven by X-axis rate sensing electrodes to sense the Coriolis rate response.
FIG. 11 shows an example gyroscope with a second dynamic mass configuration having two masses with a sense node sensing on only one of the two masses.
Fig. 12 shows a first state of clockwise rotation of the inner mass and counterclockwise rotation of the outer mass in the gyroscope of fig. 11.
Fig. 13 shows a second state in which the inner mass rotates counterclockwise and the outer mass rotates clockwise in the gyroscope of fig. 11.
FIG. 14 shows an example gyroscope with a third dynamic mass configuration comprising four independent masses.
Fig. 15 shows a first rotational state of four independent masses in the gyroscope of fig. 14.
Fig. 16 shows a second rotational state of the four independent masses in the gyroscope of fig. 14.
FIG. 17 shows an example gyroscope with a fourth dynamic mass configuration comprising four independent masses.
FIG. 18 illustrates an example method for balancing the angular momentum of a mass in a gyroscope.
Detailed Description
The micromechanical gyroscope may comprise a mechanical component made of silicon. These mechanical structures may include components on the order of several microns to tens of microns thick in size. Typically, micromechanical gyroscopes are packaged in MEMS packages that can be fabricated using off-the-shelf packaging techniques and materials in the semiconductor microelectronics field. For example, a MEMS package may provide some mechanical support, environmental protection, and electrical connection to other system components. However, MEMS packages may be subject to mechanical and/or thermal stresses that propagate to and warp the enclosed gyroscope substrate and/or its components. Such package-induced stresses or substrate-induced deformation of the gyroscope components (e.g., for high performance gyroscopes) remains a concern, as such deformation can directly affect the performance of the enclosed micromechanical gyroscope in operation.
One source of output bias drift in closed micromachined gyroscopes is the energy leakage drive pass-side mode generated by the drive motion in the closed micromachined gyroscope. This energy may propagate into the substrate and package in the form of stress waves, then enter the Printed Circuit Board (PCB), interact with the surrounding environment and reflect, then return to the gyroscope and generate a response within the sensing mode. The response may be detected as an output bias. Such biasing is susceptible to variations in the printed circuit board, intermittent contacts, and varying thermal stress conditions.
The present invention relates to exemplary micromechanical, multi-axis gyroscope structures (e.g., formed in the X-Y plane of a device layer) that may have torsional drive motions of a proof-mass that are balanced in angular momentum. The balance of the drive motion angular momentum reduces the leakage of drive energy to the substrate, thereby reducing reflections from the surrounding environment, and thus reducing output bias drift. The balancing of the angular momentum of the driving motion may be achieved by balancing the opposing mass motions in different mass arrangements of the gyroscope configuration described below.
In one example, a tri-axis gyroscope may have a single planar proof-mass design that provides a tri-axis gyroscope mode of operation. For example, in accordance with the principles of the present disclosure, a planar proof-mass in a device layer may be symmetrically suspended on (or anchored to) a substrate using a geometrically distributed anchor and one or more symmetrical flexure bearings (which may be referred to as flexure bearings) arrangement. In one embodiment, the planar proof-mass is suspended from a set of four anchors attached to the substrate. Further, the flexure may include an X-axis flexure bearing, a Y-axis flexure bearing, and a Z-axis flexure bearing.
Such multiple geometrically distributed anchors can track substrate deformation and can physically modify the out-of-plane capacitive gaps of the measurement electrodes in a gyroscope that measures the X-axis and Y-axis velocities (angular velocities) of the proof mass to compensate for substrate deformation. For example, the out-of-plane capacitive gap of the electrodes may be averaged over two anchors per X and Y dimension.
FIG. 1 is a schematic cross-sectional view of a 3-degree of freedom (3-DOF) Inertial Measurement Unit (IMU)100 in accordance with the principles of the present invention.
The IMU100 includes a 3-DOF gyroscope or 3-DOF micromechanical accelerometer formed in a chip scale package that includes a cap wafer 101, a device layer 105 including micromechanical structures (e.g., micromechanical 3-DOF IMUs), and a substrate or via wafer 103. The device layer 105 may be sandwiched between the cap wafer 101 and the via wafer 103, and the cavity between the device layer 105 and the cap wafer 101 may be sealed at the wafer level under vacuum.
In one example, cap wafer 101 may be bonded to device layer 105 using, for example, metal adhesive 102. The metal adhesive 102 may include a fusion adhesive, such as a non-high temperature fusion adhesive, to allow the getter to maintain a long-term vacuum, and an anti-friction coating to prevent friction that may occur in a low g acceleration sensor. In one example, metal bond 102 may create thermal stress between cap wafer 101 and device layer 105 during operation of device layer 105. In some examples, one or more features may be added to the device layer 105 to isolate the micromechanical structures in the device layer 105 from thermal stress, such as one or more stresses that reduce a trench formed around the micromechanical structures. In one example, the via wafer 103 can be bonded to the device layer 105 (e.g., silicon-silicon fusion bonding, etc.) to relieve thermal stress between the via wafer 103 and the device layer 105.
In one example, the via wafer 103 may include one or more isolation regions, such as a first isolation region 107, the first isolation region 107 isolating a Through Silicon Via (TSV) (e.g., a first TSV 108, which is isolated from the via wafer 103 using a dielectric material 109) from one or other regions of the via wafer 103, for example using one or more TSVs. In certain examples, the one or more isolation regions may be used as electrodes to sense or drive an out-of-plane mode of operation of the triaxial inertial sensor, and the one or more TSVs may be configured to provide electrical connections from the device layer 105 to outside the IMU 100. Further, the via wafer 103 may include one or more contacts, such as first contacts 110, that are selectively isolated from one or more portions of the via wafer 103 using the dielectric layer 104 and configured to provide electrical connections between one or more of the isolated regions or TSVs of the via wafer 103 to one or more external elements (e.g., an ASIC wafer) using bumps, wire bonds, or one or other electrical connections.
In accordance with the principles of the present invention, a 3-degree of freedom (3-DOF) gyroscope or micromechanical accelerometer in the device layer 105 may be supported or fixed by bonding the device layer 105 to a plurality of protruding portions of the through-hole wafer 103, such as the anchor 106a and the anchor 106b shown in the cross-sectional view of fig. 1. . The plurality of projections (e.g., anchors 106a and 106b) of the via wafer 103 can be located at a substantial distance from the center of the via wafer 103, and the device layer 105 can be fusion bonded to the anchors 106a and 106b, for example (e.g., eliminating or reducing problems associated with metal fatigue).
In one embodiment, four off-center anchors may be symmetrically located at the corners of a geometric square (e.g., each anchor having the same radial distance from the center of the square) to support a gyroscope or micro-mechanical accelerometer in the device layer 105 on the via wafer 103. The four eccentric anchors may include two anchors (e.g., anchor 106a and anchor 106b) shown in the cross-sectional view of fig. 1 and two anchors (not shown) in a plane perpendicular to fig. 1.
The 3-degree-of-freedom (3-DOF) gyroscope structures described herein may have two masses in the X-Y plane: a dynamic mass that can be driven (e.g., by drive electrodes) to resonate; a static mass may be used as a platform. The dynamic mass may be connected to the static mass, and the static mass may be connected to the substrate. The platform may be anchored to the substrate at four locations of four eccentric anchors placed symmetrically. Suspending the platform and connecting dynamic mass from four geometrically distributed anchors effectively averages out-of-plane displacement of the dynamic mass relative to stress-induced substrate warpage or substrate bending at these four locations, thereby reducing stress-induced asymmetric gap variations.
A 3-degree of freedom (3-DOF) gyroscope in the device layer 105 may be implemented in the device layer 105 with different dynamic proof-mass configurations. In accordance with the principles of the present invention, each dynamic mass configuration described herein includes a plurality of masses arranged to create a rotational oscillatory driving motion that is balanced in angular momentum.
In a first dynamic mass configuration, the dynamic mass comprises two masses, each having a sensing node thereon. The second dynamic mass arrangement, such as the first dynamic mass arrangement, comprises two masses. However, in the second dynamic mass configuration, there is a sensing node on only one of the two masses. In the third dynamic mass configuration, there are four independent masses. In the fourth dynamic mass configuration, as in the third dynamic mass configuration, there are four independent masses which are further secured together by an outer ring. The outer ring adds inertia to each of the four independent masses. In all four dynamic mass configurations described herein, the plurality of masses may be arranged to balance the angular momentum of the driving motion of the masses.
FIG. 2 illustrates an example gyroscope 200 having a first dynamic proof-mass configuration of two proof-masses in accordance with the principles of the present invention. Fig. 3 shows an exploded view of an example anchor suspension flexure and an example central suspension flexure that may be used with example gyroscope 200.
A gyroscope 200 that may be fabricated in a device layer (e.g., device layer 105, fig. 1) includes a static proof mass 201 and a dynamic proof mass 202 (including proof mass 202a and proof mass 202b) in the X-Y plane.
A static proof-mass 201, which may have an X-shape (cross-shape), is supported on a substrate (e.g., wafer 103) by four eccentric anchors (e.g., anchors 21) via anchor suspension flexures (e.g., flexures 22). In an embodiment, the flexure 22 may include one or more rectangular elastic hinges 22e (e.g., as shown in fig. 3).
In the gyroscope 200, a dynamic mass 202 is suspended around a static mass 201 by a gyroscope central suspension flexure 23. A gyroscope central suspension flexure 23 (which may be a c-beam flexure) attaches the dynamic mass 202 to the static mass 201, at the bottom of the four X-shaped recesses of the static mass 201. In an embodiment, the gyroscope central suspension flexure 23 may comprise one or more C-shaped spring-like elements (e.g., C-beam flexures 23C) (fig. 3).
The dynamic mass 202 may include two masses 202a and 202b distributed over four quadrants (a, b, c, and d) of the gyroscope 200. The mass 202a may be distributed, for example, on opposing quadrants a and c, wherein a portion (half) of the mass 202a corresponds to the quadrants a and c coupled by the central beam 39 of the central region (center 35) of the gyroscope 200. The mass 202b may be distributed, for example, over opposing quadrants b and d, wherein a portion (half) of the mass 202b corresponds to quadrants b and d, which are coupled by the beams 39 along the perimeter (edge 37) of the gyroscope 200. The mass 202a may be loosely mechanically coupled to the mass 202b by the anti-phase suspension flexures 43 (except for the central suspension flexure 23). The anti-phase suspension flexures 43 may expand or contract to elastically absorb or modulate the mechanical displacement of the masses relative to each other (e.g., in a rotational oscillation mode).
In the example gyroscope 200, out-of-plane X-axis sense electrodes 27 and Y-axis sense electrodes 28 (which are disposed via the via wafer 103 underlying the device layer 105) are placed near the center of the gyroscope 200 (e.g., at about a middle location between the center 35 and the edge 37 of the gyroscope 200). Furthermore, the center of mass of the X-axis and Y-axis sensing electrodes is approximately the same radial distance from the center of the gyroscope 200 as the four anchors (i.e., anchors 21) attaching the static proof-mass 201 to the substrate.
As shown in FIG. 2, gyroscope 200 also includes various in-plane drive and sense electrodes. For example, gyroscope 200 includes two pairs of drive electrodes (e.g., a first pair of drive electrodes including an in-phase (clockwise) drive actuator 24a and an anti-phase (counterclockwise) drive actuator 24b, and a second pair of drive electrodes including an in-phase drive actuator 25a and an anti-phase drive actuator 25b), a pair of sense electrodes (e.g., drive oscillation sense electrodes 26), and a pair of Z-axis rate sense electrodes 29. These in-plane electrodes and sense electrodes are arranged at a radial distance from the center of gyroscope 200 to an outer edge (e.g., edge 37) of gyroscope 200 that is greater than the radial distances of the out-of-plane X-axis and Y-axis sense electrodes from the center of the gyroscope.
For example, the drive actuators (24a, 24b), the drive actuators (25a, 25b), the drive oscillation sensing electrode 26, and the Z-axis rate sensing electrode 29 may be comb finger structures. Beams 39 (which run along edges 37 of the gyroscope) mechanically couple quadrants b and d of proof mass 202b together, and may also force Z-axis rate sensing electrodes 29 to move proof mass 202b in the same direction.
In gyroscope 200, various in-plane drive and sense electrodes (e.g., drive actuators (24a, 24b), drive actuators (25a, 25b), drive oscillation sense electrode 26, and Z-axis rate sense electrode 29) are connected to a substrate (e.g., wafer 103), for example, by anchors (e.g., anchor 30).
For example, the proof mass 202a and the proof mass 202b may be driven close to and away from each other in a rotational oscillation mode by driving the Z-axis rotational oscillation mode of the gyroscope 200 using the driving actuators (24a, 24b) and the driving actuators (25a, 25 b). The drive oscillation sense electrodes 26 may sense oscillations of the dynamic mass 202 and provide feedback to drive circuitry (not shown) that drives in-phase and anti-phase drive actuators (24a, 24b, 25a, 25 b). For example, the dynamic masses 202 ( masses 202a and 202b) are driven to resonate in a rotational oscillation mode.
Fig. 4 shows a schematic diagram of the first half cycle state of the counterclockwise rotation of the mass 202a and the clockwise rotation of the mass 202 b. Fig. 5 shows a schematic diagram of the latter half cycle state of clockwise rotation of the mass 202a and counterclockwise rotation of the mass 202 b. The in- phase drive actuators 24a, 24b and the anti-phase drive actuators 25a, 25b can be used to switch between two half-cycle states to establish the vibrational rotational motion of the two masses relative to each other in the anti-phase resonance state of the Z-axis rotational vibration model.
In an example implementation, each of the two masses 202a and 202b in the gyroscope 200 may have a mass distribution that has an equivalent magnitude displacement (i.e., an equivalent contribution to angular momentum (moment of inertia X angular velocity)) when driven at its respective angular velocity in a resonant state of the Z-axis rotational oscillation mode by the drive actuator. In the resonant state of the Z-axis rotational oscillation mode, the angular momenta of the two masses (which rotate in opposite directions) balance each other and (so that the net angular momentum of the dynamic mass configuration is about zero).
In operation, the Z-axis rotational oscillation driver on gyroscope 200 may be a high amplitude driver. A symmetric c-beam flexure at the center of gyroscope 200, such as gyroscope central suspension flexure 23), may provide mechanical quadrature cancellation.
Furthermore, in-plane differential comb finger electrodes for the Z-axis rate sensing electrodes 29 may be used to sense the coriolis rate response (e.g., external rotation of the gyroscope).
Fig. 6 shows an example of a first half-cycle state of the Z-axis sensing motion of the gyroscope 200, and fig. 7 shows an example of a second half-cycle state of the Z-axis sensing motion of the gyroscope 200. In accordance with the principles of the present invention, the differential capacitance measured by a pair of Z-axis rate sensing electrodes 29 is used to sense the coriolis rate response. In addition, out-of-plane X-axis rate sensing electrodes 27(X-) and 27(X +), out-of-plane Y-axis rate sensing electrodes 28(Y-) and 28(Y +) may sense the Coriolis rate response (e.g., due to tilt of gyroscope 200).
Fig. 8 shows an example of the first half cycle state of the X-axis sensing motion of the gyroscope 200 in a perspective view. The response of the coriolis rate to the X angular velocity is measured using the differential capacitance measured by the X-axis rate sensing sense electrode 27 pair. In addition, fig. 10 shows a cross-sectional view of the torsional displacement of the gyroscope at the second half-cycle of the X-axis sensing motion.
Fig. 9 shows an example of the first half cycle state of the Y-axis sensing motion of the gyroscope 200 in a perspective view. The response of the coriolis rate to the Y angular velocity is measured using the differential capacitance measured by the Y-axis rate sensing sense electrode 28 pair.
FIG. 11 illustrates an example gyroscope 1100 in accordance with the principles of the invention, the example gyroscope 1100 having a second dynamic mass configuration with two masses with sense node sensing on only one of the masses.
Gyroscope 1100 may be fabricated in a device layer (e.g., device layer 105, FIG. 1) that includes a dynamic mass 1102 in an X-Y plane. The dynamic mass 1102 is supported on the substrate (e.g., wafer 13) via a gyroscope central suspension flexure 1123 by two anchors (e.g., anchors 1161a, 1161 b). As shown in fig. 11, the inner mass 1102a may be X-shaped with arms of the X extending, for example, from the center of the gyroscope 1100 to the four corners of the gyroscope. The two portions (e.g., the lower and upper portions) of inner mass 1102a are coupled by a beam 1139 that passes through the central region of the gyroscope.
In gyroscope 1100, an outer mass 1102b surrounds and is suspended from inner mass 1102a by a gyroscope central suspension flexure 1123. The four portions or substantial material portions of the outer mass 1102b may be distributed inward along the perimeter (e.g., edges 1137) of the gyroscope in the four valleys formed by the X-shape of the inner mass 1102 a. Fig. 11 shows four trapezoidal portions AA, BB, CC, and DD arranged on the edge 1137 along the X-axis (AA, CC) or the Y-axis (BB, DD). The outer mass 1102b may also include beams 1139 running along the perimeter or edges (e.g., edges 1137) of the gyroscope to connect the four trapezoidal sections (AA, BB, CC, and DD) of the outer mass.
The outer mass 1102b may also be loosely mechanically coupled to the inner mass 1102b by an anti-phase suspension flexure 1143 (in addition to the central suspension flexure 1123). The anti-phase suspension flexures 1143 may expand or contract to elastically absorb or adjust (e.g., under rotational oscillation) mechanical displacements of the inner and outer masses toward or away from each other.
Gyroscope 1100, like gyroscope 200, also includes various in-plane drive and sense electrodes. For example, gyroscope 1100 includes two pairs of drive electrodes (e.g., a first pair of drive electrodes including counterclockwise-drive actuator 1124a and clockwise-drive actuator 1124b, and a second pair of drive electrodes including clockwise-drive actuator 1125a and counterclockwise-drive actuator 1125b), a pair of sense electrodes sensing (e.g., driving oscillation sense electrodes 1126) and a pair of Z-axis rate sense electrodes 1129. These in-plane electrodes and sense sensing electrodes are disposed at a radial distance that is approximately midway between the center 1135 and the edge 1137 of gyroscope 1100.
For example, fig. 11 shows that a pair of Z-axis rate sensing electrodes 1129 may be arranged (along the X-axis), e.g., midway between the center and the edge 1137 of the gyroscope. In the example shown, a pair of Z-axis rate sensing electrodes 1129 are coupled to outer mass 1102 b.
Drive actuators 1124a, 1124b, drive actuators 1125a, 1125b, drive oscillation sense electrode 1126, and Z-axis rate sense electrode 1129 may be comb finger structures. In gyroscope 1100, various in-plane drive and sense electrodes (e.g., drive actuators (1124a, 1124b), drive actuators (1125a, 1125b), drive oscillation sense electrodes 1126, and Z-axis rate sense electrodes 1129) are attached to a substrate (e.g., wafer 103), for example, by anchors (e.g., anchor 1130).
For example, the Z-axis rotational oscillation mode of gyroscope 1100 may be driven by driving proof masses 1102a and 1102b in opposite directions in a rotational oscillation mode using drive actuators 1124a, 1124b and drive actuators 1125a, 1125 b. The drive oscillation sense electrodes 1126 may sense oscillations of the dynamic mass 1102 and provide feedback to drive circuitry (not shown) that drives in-phase and anti-phase drive actuators 1124a, 1124b, 1125a, 1125b, to drive the dynamic mass 1102 ( masses 1102a and 1102b) to resonate, for example, in a rotational oscillation mode.
In this example gyroscope 1100, the out-of-plane X-axis rate sense electrodes (i.e., electrodes 1127(X-) and 1127(X +)) and the out-of-plane Y-axis rate sense electrodes (i.e., electrodes 1128(Y-) and 1128(Y +)) disposed on wafer 103 under device layer 105 are near the outer edge of gyroscope 1100, away from the center of gyroscope 1100. These out-of-plane electrodes are arranged at a distance from the center of gyroscope 1100 to an outer edge (e.g., edge 1137) of gyroscope 1100 that is greater than the distance between the in-plane electrodes (i.e., drive actuators (1124a, 1124b), drive actuators (1125a, 1125b), drive oscillation sense electrodes 1126, and Z-axis rate sense electrodes 1129) and the center of the gyroscope.
As shown in fig. 11, out-of-plane X-axis rate sensing electrodes (i.e., electrodes 1127(X-) and 1127(X +)) and out-of-plane Y-axis rate sensing electrodes (i.e., electrodes 1128(Y-) and 1128(Y +)) may be disposed on the wafer 103 of the device layer 105 under the four trapezoidal portions (AA, BB, CC, and DD) of the outer mass on the edge 1137 of the gyroscope.
The Z-axis rotational oscillation mode of gyroscope 1100 may be driven, for example, by driving inner mass 1102a in a counterclockwise direction using drive actuator 1124a, and driving outer mass 1102b in a counterclockwise direction using drive actuator 1124 b. Drive actuators 1125a and 1125b may be used to reverse the direction of rotation (e.g., drive inner mass 1102a in a clockwise direction and outer mass 1102b in a counter-clockwise direction) to establish a rotational oscillation mode.
Fig. 12 shows a schematic diagram of the first half cycle state with the inner mass 1102a rotated clockwise and the outer mass 1102b rotated counterclockwise. Fig. 13 shows a schematic diagram of the latter half cycle of the counterclockwise rotation of the inner mass 1102a and the clockwise rotation of the outer mass 1102 b. In-phase and anti-phase drive actuators (1124a, 1124b, 1125a, 1125b) may be used to switch between two states to set an oscillatory rotational motion of the two masses toward and away from each other in a resonant state of the Z-axis rotational oscillation mode.
The drive oscillation sense electrode 1126 may sense drive oscillations and provide feedback to a drive circuit (not shown) that drives the clockwise drive actuator and the counterclockwise drive actuator.
In an example implementation, each of the two masses 1102a and 1102b in gyroscope 1100 has a mass distribution of equivalent magnitude displacement (e.g., equivalent angular momentum contribution (moment of inertia X angular velocity)) when driven by a drive actuator in response.
In-plane Z-axis rate sensing sense electrodes 1129, out-of-plane X-axis rate sensing sense electrodes (i.e., electrodes 1127(X-) and 1127(X +)) and out-of-plane Y-axis rate sensing sense electrodes (i.e., electrodes 1128(Y-) and 1128(Y +)) may be used to sense the Coriolis rate response of gyroscope 1100 (e.g., using Z-axis rate sensing electrodes 29, out-of-plane X-axis rate sensing sense electrodes (i.e., electrodes 27(X-) and 27(X +)) and out-of-plane Y-axis rate sensing sense electrodes (i.e., electrodes 28(Y-) and 28(Y +)) to sense the Coriolis rate response in gyroscope 200, as described above with reference to FIGS. 6-10).
FIG. 14 illustrates an example gyroscope 1400 having a third dynamic mass configuration including four independent masses in accordance with the principles of the present invention.
The gyroscope 1400 may be fabricated in a device layer (e.g., device layer 105, fig. 1) including a static mass 1401 and a dynamic mass 1402 in an X-Y plane. The dynamic mass 1402 includes independent masses (i.e., mass 1402a, mass 1402b, mass 1402c, and mass 1402 d). Each of the four masses may be wedge-shaped. For example, the static mass 1401, which may be rectangular (e.g., square), may be supported on a substrate (e.g., wafer 103).
The dynamic mass 1402 is suspended around the static mass 1401 by the gyroscope central suspension flexures 1423. In embodiments, the flexure 22 may include more than one rectangular elastic hinge 22e (e.g., as shown in fig. 3).
Each of the four masses in the dynamic mass block 1402 (i.e., mass block 1402a, mass block 1402b, mass block 1402c, and mass block 1402d) may be suspended from a respective side or face of the square static mass block 1401 via a gyroscope central suspension flexure 1423, and may occupy a respective geometric quadrant (e.g., a a a, bbb, ccc, and ddd) of the gyroscope 1400. Each of the four masses (i.e., mass 1402a, mass 1402b, mass 1402c) in its respective quadrant can be loosely mechanically coupled to the masses in the adjacent quadrant by the anti-phase suspension flexures 1443 (in addition to the central suspension flexure 1423). The anti-phase suspension flexures 1443 may expand or contract to elastically absorb or adjust adjacent masses for mechanical displacement (e.g., in a rotational oscillation mode) toward or away from each other.
Gyroscope 1400, like gyroscope 200 and gyroscope 1100, also includes various in-plane drive and sense electrodes. For example, gyroscope 1400 includes a pair of drive electrodes, e.g., a clockwise drive actuator 1424a and a counterclockwise drive actuator 1424b (disposed in one of the four quadrants of gyroscope 1400 (e.g., quadrant aaa including proof mass 1402 a), a pair of sense electrodes (e.g., drive oscillation sense electrodes 1426) (disposed in the opposite quadrant of gyroscope 1400) (e.g., quadrant ccc including proof mass 1402c), gyroscope 1400 further includes a pair of Z-axis rate sense electrodes 1429 disposed in the remaining two quadrants of gyroscope 1400 (e.g., quadrant bbb including proof mass 1402b and quadrant ddd including proof mass 1402 d). these in-plane electrodes and sense electrodes are disposed at a radial distance approximately midway between the center 1435 and edge 1437 of gyroscope 1400, as shown in fig. 14.
For example, the in-plane and sense electrodes (i.e., drive actuators (1424a, 1424b), drive oscillation sense electrodes 1426, and Z-axis rate sense electrodes 1429) may be comb finger structures. In gyroscope 1400, various in-plane drive and sense electrodes are connected to a substrate (e.g., wafer 103), for example, by anchors (e.g., anchors 1430).
For example, a Z-axis rotational oscillation mode of gyroscope 1400 may be driven by driving adjacent masses (e.g., mass blocks 1402a and 1402b, mass block 1402b and 1402c, mass block 1402c and mass block 1402d) in opposite directions using drive actuators (1424a, 1424b) in a rotational oscillation mode. The drive oscillation sense electrodes 1426 may sense oscillations of the dynamic mass block 1402 and provide feedback to a drive circuit (not shown) that drives the in-phase and anti-phase drive actuators 1424a, 1424b, e.g., to drive the dynamic mass block 1402 (comprising four independent mass blocks — mass block 1402a, mass block 1402b, mass block 1402c, and mass block 1402d) into resonance in a rotational oscillation mode.
In this example gyroscope 1400, out-of-plane X-axis rate sense electrodes (i.e., electrodes 1427(X-) and 1427(X +)) and out-of-plane Y-axis rate sense electrodes (i.e., electrodes 1428(Y-) and 1428(Y +), which are disposed via wafer 103 under device layer 105) are placed near the outer edge of gyroscope 1100, away from the center of gyroscope 1400 these out-of-plane electrodes are disposed at a distance from the center of gyroscope 1400 to the outer edge (e.g., edge 1137) of gyroscope 1100 that is greater than the distance between in-plane electrodes (e.g., drive actuators (1424a, 1124b), drive oscillation sense electrodes 1126, and Z-axis rate sense electrodes 1429) and the center of the gyroscope.
As shown in FIG. 14, for example, out-of-plane X-axis rate sense electrodes 1427(X-) and 1427(X +), out-of-plane Y-axis rate sense electrodes 1428(Y-) and 1128(Y +) may be disposed under the wedge-shaped proof-masses (1402a, 1402b, 1402c, and 1402d) (on the wafer 103 under the device layer 105) near the edge 1437 of the gyroscope.
For example, adjacent pairs of four independent masses 1402a, 1402b, 1402c, and 1402d may be driven in opposite directions to establish a rotational oscillation mode by driving the Z-axis rotational oscillation mode of gyroscope 1400 using in-phase (clockwise) drive actuator 1424a and anti-phase drive actuator 1124 b.
Fig. 15 shows a schematic diagram of a first rotational state of four independent masses 1402a, 1402b, 1402c, 1402d with respect to a static mass 1401. As shown in fig. 15, in this first state, the mass 1402a and the mass 1402c rotate counterclockwise, and the mass 1402c and the mass 1402d rotate clockwise. Fig. 16 shows a schematic diagram of a second rotation state of four independent masses 1402a, 1402b, 1402c, and 1402d with respect to a static mass 1401. As shown in fig. 16, in the second state, the mass block 1402a and the mass block 1402c rotate clockwise, and the mass block 1402b and the mass block 1402d rotate counterclockwise. In-phase and anti-phase drive actuators 1424a, 1424b may be used to switch between two states to establish a vibratory rotational motion of adjacent pairs of four masses toward and away from each other to establish a resonant state of the Z-axis rotational oscillation mode.
Drive oscillation sense electrode 1426 may sense drive oscillations of gyroscope 1400 and provide feedback to a drive circuit (not shown) that drives in-phase and anti-phase drive actuators 1424a, 1424 b.
In an example implementation, each of the four masses 1402a, 1402b, 1402c, and 1402d in the gyroscope 1400 may have a mass distribution of equivalent magnitude displacement (e.g., equivalent contribution to angular momentum (rotational inertia X angular velocity)) when driven by the drive actuators 1424a, 1424b at respective angular velocities in a resonant state of a Z-axis rotational oscillation mode.
In the resonant state of the Z-axis rotational oscillation mode, the angular momenta of the four masses (two adjacent mass pairs rotating in opposite directions) balance or cancel each other out (so that the net angular momentum of the dynamic mass configuration is about zero).
An in-plane Z-axis rate sense electrode 1429, out-of-plane X-axis rate sense electrodes 1427(X-) and 1427(X +), and out-of-plane Y-axis rate sense electrodes 1428(Y-) and 1428(Y +). May be used to sense the coriolis rate response of gyroscope 1400 (e.g., out-of-plane X-axis velocity sense electrodes 27(X-) and 27(X +), and out-of-plane Y-axis velocity sense electrodes 28(Y-) and 28(Y +), in a manner similar to that used with Z-axis rate sense electrodes 29, for sensing the coriolis rate response in gyroscope 200, as described above with reference to fig. 6-10.
FIG. 17 illustrates an example gyroscope 1700 having a fourth dynamic mass configuration including four independent masses in accordance with the principles of the present invention.
Gyroscope 1700, like gyroscope 1400, may include static masses 1401 and dynamic masses 1702 in the X-Y plane. The dynamic mass 1702, like the dynamic mass 1402, includes four wedge-shaped independent masses 1402a, 1402b, 1402c, and 1402d suspended around the static mass 1401 by a gyroscope central suspension flexure 1423. The dynamic mass 1702 may also include stiffening beams 1741 running along the perimeter or edges (e.g., edge 1737) of the gyroscope to connect the four wedge-shaped individual masses (i.e., mass 1402a, mass 1402b, mass 1402c, and mass 1402 d). Stiffening beam 1741 may equivalently add inertia to each of the four masses and may stiffen one or more undesired resonance modes of gyroscope 1700.
Gyroscope 1700, like gyroscope 1400, also includes various in-plane drive and sense electrodes. For example, gyroscope 1700 includes a pair of drive electrodes including a clockwise drive actuator 1424a and a counterclockwise drive actuator 1424b arranged in one of the four quadrants of the gyroscope (e.g., quadrant aaa including proof mass 1402 a), a pair of sense electrodes (e.g., drive oscillation sense electrodes 1126) arranged in the opposite quadrant of the gyroscope (e.g., quadrant ccc including proof mass 1402 c). Gyroscope 1700 also includes a pair of Z-axis rate sense electrodes 1429 arranged in the remaining two quadrants of the gyroscope (e.g., quadrant bbb and quadrant ccc).
For gyroscope 1400 discussed above, the Z-axis rotational oscillation mode of gyroscope 1700 may be driven in opposite directions in the rotational oscillation mode, e.g., by driving adjacent masses (e.g., masses 1402a and 1402b, masses 1402b and 1402c, masses 1402c and 1402d) using drive drivers 1424a, 1424 b.
As in gyroscope 1400, each of the four masses 1402a, 1402b, 1402c, and 1402d in gyroscope 1700 may have a mass with an equivalent magnitude displacement when driven by a drive actuator. The angular momenta of the four masses (two adjacent masses rotating in opposite directions) balance or cancel each other out. Stiffening beam 1741 equivalently adds inertia to each of the four masses, which may suppress one or more undesirable resonance modes of gyroscope 1700.
Fig. 18 shows an example method 1800 for balancing the angular momentum of a mass in a micromechanical gyroscope.
Method 1800 includes suspending a dynamic mass configuration of a micromachined gyroscope in a plane (e.g., an X-Y plane) on a substrate from at least one anchor connected to the substrate (1810).
The method 1800 may further include providing a plurality of masses (1820) in the dynamic mass configuration, providing a plurality of drive actuators to drive the plurality of masses (1830) in a rotational oscillation mode (e.g., a Z-axis rotational oscillation mode) of the gyroscope, configuring a distribution of the masses of the plurality of masses to have an equivalent contribution to an angular momentum of the dynamic mass configuration when the plurality of masses are driven by the drive actuators at respective angular velocities at a resonant state of the rotational oscillation mode (1840), and back-driving adjacent masses in the rotational oscillation mode to cancel the angular momentum of the dynamic mass configuration (1850).
In the method 1800, providing a plurality of masses in a dynamic mass configuration (1820) may include providing anti-phase suspension flexures to pairs of adjacent masses. The anti-phase suspension flexures (e.g., under rotational oscillation) may expand or contract to elastically absorb or accommodate mechanical displacement of adjacent masses toward or away from each other.
It will also be understood that when an element such as a transistor or resistor or gyroscope assembly is referred to as being turned on, connected, electrically connected, coupled or electrically coupled to another element, it can be directly turned on, connected or coupled to the other element or one or more intervening elements may be present. In contrast, when an element is referred to as being directly on, directly connected to, or directly coupled to another element or layer, there are no intervening elements or layers present. Although terms directly located, directly connected, or directly coupled may not be used throughout the detailed description, elements shown as directly located, directly connected, or directly coupled may be referred to as directly located, directly connected, or directly coupled elements. The claims of this application, if included, may be amended to recite the exemplary relationships described in the specification or illustrated in the drawings.
As used in this specification, the singular form may include the plural form unless the context clearly dictates otherwise. Spatially relative terms (e.g., above, below, and the like) are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. In some implementations, relative terms above and below may include vertically above and vertically below, respectively. In some implementations, the term abutting can include lateral abutting or horizontal abutting.
Implementations of the various techniques described herein may be implemented in (e.g., included in) digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. Portions of the methods may also be performed by, and apparatus may be implemented as, special purpose logic circuitry, e.g., fpga (field programmable gate array) or asic (application-specific integrated circuit).
May be implemented in a computing system that includes an industrial motor drive, a solar inverter, a ballast, a universal half-bridge topology, an auxiliary and/or traction motor inverter drive, a switching power supply, an on-board charger, an Uninterruptible Power Supply (UPS), a back-end component (e.g., a data server), or include a middleware component, such as an application server, or include a front-end component, such as a client computer having a graphical user interface or a web browser through which a user can interact with an implementation, the components can be interconnected by any form or medium of digital data communication (e.g., a communication network). examples of communication networks include a local area network (lan) and a wide area network (wan), such as the Internet.
While certain features of the described implementations have been illustrated as described herein, many modifications, substitutions, changes, and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims, if any, are intended to cover all such modifications and changes as fall within the true scope of the implementations. It is to be understood that they have been presented by way of example only, and not limitation, and various changes in form and details may be made. Any portions of the apparatus and/or methods described herein may be combined in any combination, except mutually exclusive combinations. Implementations described herein may include various combinations and/or subcombinations of the functions, components, and/or features of the different implementations described.
