An extensional mode electrostatic microelectromechanical systems (MEMS) gyroscope is described. The MEMS gyroscope operates in an extensional mode. The MEMS gyroscope comprises a vibrating ring structure that is electrostatically excited in the extensional mode.

A vibrating structure gyroscope includes a permanent magnet, a structure arranged in a magnetic field of the permanent magnet and arranged to vibrate under stimulation from at least one primary drive electrode and a drive system that includes: one primary drive electrode arranged at least one primary sense electrode arranged to sense motion in the vibrating structure and a drive control loop controlling the primary drive electrode dependent on the primary sense electrode. The structure also includes a compensation unit arranged to receive a signal from the drive system representative of a gain in the drive control loop and arranged to output a scale factor correction based on that signal. As the magnet degrades (e.g. naturally over time as the material ages), the magnetic field weakens. To compensate for this, the primary drive control loop will automatically increase the gain.

A vibrating structure gyroscope includes a permanent magnet, a structure arranged in a magnetic field of the permanent magnet and arranged to vibrate under stimulation from at least one primary drive electrode and a drive system that includes: one primary drive electrode arranged at least one primary sense electrode arranged to sense motion in the vibrating structure and a drive control loop controlling the primary drive electrode dependent on the primary sense electrode. The structure also includes a compensation unit arranged to receive a signal from the drive system representative of a gain in the drive control loop and arranged to output a scale factor correction based on that signal. As the magnet degrades (e.g. naturally over time as the material ages), the magnetic field weakens. To compensate for this, the primary drive control loop will automatically increase the gain.

An inertial sensor includes a substantially planar, rotationally symmetric proof mass, a capacitive pick-off circuit connected to the proof mass, an electrical drive circuit connected to the four pairs of electrodes. The drive circuit is arranged to apply first in-phase and anti-phase pulse width modulation (PWM) drive signals with a first frequency to the first and third electrode pairs, such that one electrode in each pair is provided with in-phase PWM drive signals and the other electrode in each pair is provided with anti-phase PWM drive signals and to apply second in-phase and anti-phase PWM drive signals with a second frequency, different to the first frequency, to the second and fourth electrode pairs, such that one electrode in each pair is provided with in-phase PWM drive signals and the other electrode in each pair is provided with anti-phase PWM drive signals.

A bulk acoustic wave resonator apparatus includes a resonator member, at least one anchor structure coupling the resonator member to a substrate, and a comb-drive element connected to the resonator member. The comb-drive element includes first comb fingers protruding from the resonator member, and second comb fingers of a different material than the first comb fingers interdigitated with the first comb fingers to define sub-micron capacitive gaps therebetween. Respective sidewalls of the first comb fingers are oppositely-tapered relative to respective sidewalls of the second comb fingers along respective lengths thereof, such that operation of the comb-drive element varies the sub-micron capacitive gaps at the respective sidewalls thereof. Respective tuning electrodes, which are slanted at respective angles parallel to an angle of respective sidewalls of the resonator member, may also be provided for quadrature tuning between different resonance modes of the resonator member. Related devices and fabrication methods are also discussed.

A gyroscope comprising a resonator, a plurality of transducers configured to drive a vibrational mode in the resonator and detect vibrations of the resonator, a base configured to support the resonator, the base including attachment points for attachment to an external system, and a vibration isolator for isolating the resonator from the external system, the vibration isolator being formed from resilient material and being located radially inward of the attachment points.

A gyroscope comprising a resonator, a plurality of transducers configured to drive a vibrational mode in the resonator and detect vibrations of the resonator, a base configured to support the resonator, the base including attachment points for attachment to an external system, and a vibration isolator for isolating the resonator from the external system, the vibration isolator being formed from resilient material and being located radially inward of the attachment points.

A ring gyroscope which comprises first and second transversal symmetry axes and first and second diagonal symmetry axes in the ring plane. The gyroscope further comprises one or more primary piezoelectric split transducers configured to drive the ring into resonance oscillation and one or more secondary piezoelectric split transducers configured to sense the oscillation of the ring. The gyroscope further comprises four or more mass elements which form a symmetrical mass distribution in relation to both the first and second transversal symmetry axes and to the first and second diagonal symmetry axes, wherein each mass element is attached to the ring from a bridge connector and the bridge connectors are evenly distributed along the ring.

A ring gyroscope which comprises first and second transversal symmetry axes and first and second diagonal symmetry axes in the ring plane. The gyroscope further comprises one or more primary piezoelectric split transducers configured to drive the ring into resonance oscillation and one or more secondary piezoelectric split transducers configured to sense the oscillation of the ring. The gyroscope further comprises four or more mass elements which form a symmetrical mass distribution in relation to both the first and second transversal symmetry axes and to the first and second diagonal symmetry axes, wherein each mass element is attached to the ring from a bridge connector and the bridge connectors are evenly distributed along the ring.

A method of tuning a vibratory gyroscope, the method comprising the steps of: a) applying an AC drive signal to the drive electrode, the drive signal comprising a plurality of frequencies; b) sensing the response of the resonator to the drive signal at the first and second sense electrodes; c) determining a frequency of maximum response for the first mode of vibration, and determining a frequency of maximum response for the second mode of vibration; d) deriving a comparison result from a comparison of the frequency of maximum response for the first mode of vibration with the frequency of maximum response for the second mode of vibration; and e) applying a biasing voltage to one or more of the tuning electrodes dependent on the comparison result.