Dual-Axis Resonator Gyroscope Tangential Coupling
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Solution Overview
Problem
Resonator gyroscopes face limitations in in-plane coupling, resonant frequency matching, vibration amplitude, and long-term stability due to geometric constraints and material properties, which affect sensitivity and accuracy.
Innovation Solution
A dual-axis resonator gyroscope design featuring tangentially linked oscillators with integral spring formations and torsion beams to enhance coupling efficiency, reduce mechanical stress, and allow for flexible resonant frequency adjustment, along with a force balance loop and self-test mechanisms to stabilize resonant frequencies and eliminate signal waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radial coupling elements are used to link oscillators, then mechanical coupling is achieved, but stress concentration occurs and in-plane coupling is limited to about 10%
Solution Approach 1:
The coupling elements are designed with tangential curvature rather than radial straight lines, creating U-shaped or arc-shaped structures that follow the circumferential direction. This curvature distributes mechanical stress along the arc path, eliminating stress concentration at the oscillator bases and enabling reliable mechanical coupling without breaking under vibration loads.
Solution Approach 2:
The coupling elements are positioned and oriented asymmetrically relative to the oscillator centers, specifically aligned tangentially to the effective center of rotation rather than radially. This asymmetric tangential arrangement optimizes the coupling mechanism by aligning the force transmission path with the direction of motion, achieving superior in-plane coupling exceeding 10% while reducing stress on the oscillators.
2Measurement precision
If wafer thickness is increased to increase vibrating mass, then sensitivity improves, but resonant frequency increases
Solution Approach 1:
The resonator structure employs non-uniform thickness distribution, with the wafer being thinner at the oscillator locations and thicker at the anchor regions. This local quality variation allows the oscillating mass to be sufficiently large for sensitivity while the thinner sections at the oscillators maintain lower resonant frequencies. The differential thickness optimizes both sensitivity and frequency characteristics by placing mass where needed without uniformly increasing inertia.
3Measurement precision
If flexing length is increased to allow larger vibration amplitude, then Coriolis deflection increases, but in-plane coupling decreases
Solution Approach 1:
The coupling mechanism transitions from in-plane radial coupling to out-of-plane tangential coupling. The coupling elements extend in the circumferential direction and utilize out-of-plane flexing modes to transmit motion between oscillators. This dimensional change allows the oscillators to have longer effective flexing lengths for larger amplitude Coriolis deflection while the tangential coupling path maintains efficient in-plane coupling through the out-of-plane motion component.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves improved in-plane coupling, increased vibration amplitudes, and enhanced long-term stability of resonant frequency matching, leading to increased sensitivity and accuracy in inertial rotation rate measurements.
Implementation Method 1
the mechanical linking elements induce an opposite angular in-plane deflection of adjacent ones of the oscillators, wherein the linking elements are configured to include at least one portion extending substantially tangentially relative to the effective center of rotation, thereby reducing stresses in the oscillators
Implementation Method 2
the integral spring formation for each of the oscillators includes a torsion beam deployed to reduce mechanical resistance to out-of-plane deflection of the oscillator
Implementation Method 3
Resonator (Coriolis) gyroscopes are well known
Implementation Method 4
the sensitivity of a resonator gyroscope is maximized when the resonant frequencies of the drive and the Coriolis modes—are nearly matched
Data Source
AI summary
The present invention discloses an improved planar, dual-axis, resonator gyroscope with mechanical coupling of adjacent vibrating members. The primary-mode flexible hinges include a tangential torsion element that largely decouples the out-of-plane resonant frequency from the wafer thickness. The use of separate plates for the force-balance and for the electric spring enables decoupling of the two functions. The invention also provides resonant frequency servo-loop for locking of the sense-mode resonant frequency to the drive-mode frequency, an online self-test, a split force balance loop for self cancellation of the quadrature signal, decoupling of the force-balance and resonant frequency servo-loops and stabilization of the inertial rate-sensing sensitivity—when operated in an open loop mode, all without interfering with the normal operation of the gyroscope. An optional sensing of the Z-axis acceleration perpendicular to the sensor plane is also provided which can be used for compensating acceleration-induced errors.