Abstract: Sensing motion of multiple degrees of freedom for an integral inertial measurement unit provided through the operation of a single centrally mounted planar disc resonator having a single driven mode in a single vacuum enclosure is disclosed. The resonator comprises a circumferentially slotted disc having multiple internal capacitive electrodes within the slots in order to excite a single in-plane driven vibration and sense in-plane vibration modes or motion of the resonator. In addition, vertical electrodes disposed below and/or above the resonator may also be used to sense out-of-plane vibration or motion. Acceleration sensing in three orthogonal axes can be obtained by sensing two lateral modes of the disc resonator in the plane of the disc from the internal electrodes and a vertical mode from the vertical electrodes.

Abstract: Techniques for reducing the frequency split between the Coriolis-coupled modes in disc resonator gyroscopes (DRGs) by perturbing the mass distribution on the disc resonator based on an identified model are disclosed. A model-identification method of tuning a resonator comprises perturbing the mass and measuring a frequency response matrix of the resonator. The frequency response matrix includes a plurality of inputs and a plurality of outputs and the resonator has a plurality of coupled resonance modes. A reduced structural mechanics matrix model of the resonator in sensor and actuator coordinates is identified from the measured frequency response matrix and analyzed to determine generalized eigenvectors of the structural mechanics model and their variations due to selected mass perturbations which is then estimated to improve degeneracy of the plurality of coupled resonance modes based on the generalized eigenvectors of the mass and the stiffness.

Abstract: Tuning an axisymmetric resonator such as in a disc resonator gyroscope (DRG) is disclosed. Frequency tuning a DRG in a single step informed by a systematic physical model of the resonator structure, sensing and actuation elements, such as a finite element model, is provided. The sensitivity of selected trimming positions on the resonator to reducing asymmetry terms is determined via perturbations of the systematic model. As well, the dependence of the parameters of model transfer functions between actuation and sensing elements on resonator asymmetry are systematically determined. One or two measured transfer functions may then be analyzed according to the systematic model to fully determine the needed asymmetry correction components of the DRG. One or two of four groups of four electrostatic bias electrodes or four groups of four laser trimming locations for the DRG are utilized to correct the asymmetry components which can give rise to mistuning.

Abstract: An inertial sensor includes a mesoscaled disc resonator comprised of micro-machined substantially thermally non-conductive wafer with low coefficient of thermal expansion for sensing substantially in-plane vibration, a rigid support coupled to the resonator at a central mounting point of the resonator, at least one excitation electrode within an interior of the resonator to excite internal in-plane vibration of the resonator, and at least one sensing electrode within the interior of the resonator for sensing the internal in-plane vibration of the resonator. The inertial sensor is fabricated by etching a baseplate, bonding the substantially thermally non-conductive wafer to the etched baseplate, through-etching the wafer using deep reactive ion etching to form the resonator, depositing a thin conductive film on the through-etched wafer.

Abstract: Operation of a planar resonator gyroscope with in-plane parasitic modes of vibration to obtain improved performance is disclosed. A planar resonator gyroscope, such as a disc resonator gyroscope, may be operated with embedded electrodes. The embedded electrodes may be disposed adjacent to the planar resonator and proximate to one or more anti-nodes of a parasitic vibration mode. A sensed amplitude of the parasitic mode is applied in differential signals used to operate the gyroscope. A feedback controller for damping the parasitic mode applies a drive voltage generated from the proportional voltage to one or more drive electrodes adjacent to the planar resonator disposed proximate to one or more anti-nodes of the parasitic vibration mode of the planar resonator. Parasitic in-plane modes may be thus damped in operating the gyroscope with active damping applied through an analog operational amplifier or digital feedback.

Abstract: Packaging techniques for planar resonator gyroscopes, such as disc resonator gyroscopes (DRGs) are disclosed. A gyroscope die may be attached to its package substrate on a central disc area that is inboard of its embedded electrodes. This configuration eliminates contact of the die with the package substrate beneath the embedded electrodes allowing the internal electrode support structure to expand or contract freely without stress as its temperature changes. The central attachment can also be used diminish the package temperature gradients on the periphery of the die, if the thermal conductivity of the central disc attachment material is higher than the package substrate. Temperature gradients across the resonator also lead to thermoelastic damping asymmetry and rate drift. In addition, the electrical connections to the die may be formed by vertical vias within the central disc attachment area or by thin wirebonds to peripheral I/O pads on the gyro chip.

Abstract: Parametrically disciplined operation of a symmetric nearly degenerate mode vibratory gyroscope is disclosed. A parametrically-disciplined inertial wave gyroscope having a natural oscillation frequency in the neighborhood of a sub-harmonic of an external stable clock reference is produced by driving an electrostatic bias electrode at approximately twice this sub-harmonic frequency to achieve disciplined frequency and phase operation of the resonator. A nearly symmetric parametrically-disciplined inertial wave gyroscope that can oscillate in any transverse direction and has more than one bias electrostatic electrode that can be independently driven at twice its oscillation frequency at an amplitude and phase that disciplines its damping to zero in any vibration direction. In addition, operation of a parametrically-disciplined inertial wave gyroscope is taught in which the precession rate of the driven vibration pattern is digitally disciplined to a prescribed non-zero reference value.

Abstract: The present invention discloses an inertial sensor comprising a planar mechanical resonator with embedded sensing and actuation for substantially in-plane vibration and having a central rigid support for the resonator. At least one excitation or torquer electrode is disposed within an interior of the resonator to excite in-plane vibration of the resonator and at least one sensing or pickoff electrode is disposed within the interior of the resonator for sensing the motion of the excited resonator. In one embodiment, the planar resonator includes a plurality of slots in an annular pattern; in another embodiment, the planar mechanical resonator comprises four masses; each embodiment having a simple degenerate pair of in-plane vibration modes.

Abstract: A Multiple Internal Seal Ring (MISR) Micro-Electro-Mechanical System (MEMS) vacuum packaging method that hermetically seals MEMS devices using MISR. The method bonds a capping plate having metal seal rings to a base plate having metal seal rings by wafer bonding the capping plate wafer to the base plate wafer. Bulk electrodes may be used to provide conductive paths between the seal rings on the base plate and the capping plate. All seals are made using only metal-to-metal seal rings deposited on the polished surfaces of the base plate and capping plate wafers. However, multiple electrical feed-through metal traces are provided by fabricating via holes through the capping plate for electrical connection from the outside of the package through the via-holes to the inside of the package. Each metal seal ring serves the dual purposes of hermetic sealing and providing the electrical feed-through metal trace.

Abstract: Operation of a planar resonator gyroscope with in-plane parasitic modes of vibration to obtain improved performance is disclosed. A planar resonator gyroscope, such as a disc resonator gyroscope, may be operated with embedded electrodes. The embedded electrodes may be disposed adjacent to the planar resonator and proximate to one or more anti-nodes of a parasitic vibration mode. A sensed amplitude of the parasitic mode is applied in differential signals used to operate the gyroscope. A feedback controller for damping the parasitic mode applies a drive voltage generated from the proportional voltage to one or more drive electrodes adjacent to the planar resonator disposed proximate to one or more anti-nodes of the parasitic vibration mode of the planar resonator. Parasitic in-plane modes may be thus damped in operating the gyroscope with active damping applied through an analog operational amplifier or digital feedback.

Abstract: The present invention discloses an inertial sensor having an integral resonator. A typical sensor comprises a planar mechanical resonator for sensing motion of the inertial sensor and a case for housing the resonator. The resonator and a wall of the case are defined through an etching process. A typical method of producing the resonator includes etching a baseplate, bonding a wafer to the etched baseplate, through etching the wafer to form a planar mechanical resonator and the wall of the case and bonding an end cap wafer to the wall to complete the case.

Abstract: A Multiple Internal Seal Ring (MISR) Micro-Electro-Mechanical System (MEMS) vacuum package that hermetically seals MEMS devices using MISR. The method bonds a capping plate having metal seal rings to a base plate having metal seal rings by wafer bonding the capping plate wafer to the base plate wafer. Bulk electrodes may be used to provide conductive paths between the seal rings on the base plate and the capping plate. All seals are made using only metal-to-metal seal rings deposited on the polished surfaces of the base plate and capping plate wafers. However, multiple electrical feed-through metal traces are provided by fabricating via holes through the capping plate for electrical connection from the outside of the package through the via-holes to the inside of the package. Each metal seal ring serves the dual purposes of hermetic sealing and providing the electrical feed-through metal trace.

Abstract: An inertial sensor includes a mesoscaled disc resonator comprised of micro-machined substantially thermally non-conductive wafer with low coefficient of thermal expansion for sensing substantially in-plane vibration, a rigid support coupled to the resonator at a central mounting point of the resonator, at least one excitation electrode within an interior of the resonator to excite internal in-plane vibration of the resonator, and at least one sensing electrode within the interior of the resonator for sensing the internal in-plane vibration of the resonator. The inertial sensor is fabricated by etching a baseplate, bonding the substantially thermally non-conductive wafer to the etched baseplate, through-etching the wafer using deep reactive ion etching to form the resonator, depositing a thin conductive film on the through-etched wafer.

Abstract: A micro-gyroscope (10) having closed loop output operation by a control voltage (Vty), that is demodulated by a drive axis (x-axis) signal Vthx of the sense electrodes (S1, S2), providing Coriolis torque rebalance to prevent displacement of the micro-gyroscope (10) on the output axis (y-axis) Vthy˜0. Closed loop drive axis torque, Vtx maintains a constant drive axis amplitude signal, Vthx. The present invention provides independent alignment and tuning of the micro-gyroscope by using separate electrodes and electrostatic bias voltages to adjust alignment and tuning. A quadrature amplitude signal, or cross-axis transfer function peak amplitude is used to detect misalignment that is corrected to zero by an electrostatic bias voltage adjustment. The cross-axis transfer function is either Vthy/Vty or Vtnx/Vtx.

Abstract: The present invention discloses a resonator gyroscope comprising a resonator including two bodies, each with a center of mass and transverse inertia symmetry about an axis that are substantially coincident and each supported by one or more elastic elements and wherein the bodies together forming two differential rocking modes of vibration transverse to the axis with substantially equal frequencies and wherein the two bodies transfer substantially no net momentum to the baseplate when the resonator is excited. The gyroscope further includes a baseplate affixed to the resonator by the one or more elastic elements.

Abstract: The present invention discloses a resonator gyroscope comprising a vibrationally isolated resonator including a proof mass, a counterbalancing plate having an extensive planar region, and one or more flexures interconnecting the proof mass and counterbalancing plate. A baseplate is affixed to the resonator by the one or more flexures and sense and drive electrodes are affixed to the baseplate proximate to the extensive planar region of the counterbalancing plate for exciting the resonator and sensing movement of the gyroscope. The isolated resonator transfers substantially no net momentum to the baseplate when the resonator is excited.

Abstract: The present invention discloses an inertial sensor comprising a planar mechanical resonator with embedded sensing and actuation for substantially in-plane vibration and having a central rigid support for the resonator. At least one excitation or torquer electrode is disposed within an interior of the resonator to excite in-plane vibration of the resonator and at least one sensing or pickoff electrode is disposed within the interior of the resonator for sensing the motion of the excited resonator. In one embodiment, the planar resonator includes a plurality of slots in an annular pattern; in another embodiment, the planar mechanical resonator comprises four masses; each embodiment having a simple degenerate pair of in-plane vibration modes.

Abstract: The present invention discloses a resonator gyroscope comprising a vibrationally isolated resonator including a proof mass, a counterbalancing plate having an extensive planar region, and one or more flexures interconnecting the proof mass and counterbalancing plate. A baseplate is affixed to the resonator by the one or more flexures and sense and drive electrodes are affixed to the baseplate proximate to the extensive planar region of the counterbalancing plate for exciting the resonator and sensing movement of the gyroscope. The isolated resonator transfers substantially no net momentum to the baseplate when the resonator is excited.

Abstract: The present invention discloses a robotic manipulator, comprising at least one joint, each joint having a drive axis and at least one microelectromechanical system (MEMS) inertial sensor aligned with at least one drive axis providing sensing of a relative position of the drive axis. The robotic manipulator can include an inertial measurement unit (IMU) coupled to the robotic manipulator for determining the end effector position and orientation. A controller can be used, receiving a signal from at least one MEMS inertial sensor and controlling at least one joint drive axis in response to the signal to change the relative position of the joint drive axis. Rate information from MEMS sensors can be integrated to determine the position of their respective drive axes.

Abstract: The present invention discloses a resonator gyroscope including an isolated resonator. One or more flexures support the isolated resonator and a baseplate is affixed to the resonator by the flexures. Drive and sense elements are affixed to the baseplate and used to excite the resonator and sense movement of the gyroscope. In addition, at least one secondary element (e.g., another electrode) is affixed to the baseplate and used for trimming isolation of the resonator. The resonator operates such that it transfers substantially no net momentum to the baseplate when the resonator is excited. Typically, the isolated resonator comprises a proof mass and a counterbalancing plate.