Vibratory Gyroscope Resonator Geometry for Parasitic Mode Separation
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Solution Overview
Problem
Existing vibratory gyroscope sensors suffer from parasitic modes that interfere with high-bandwidth control electronics, leading to unstable measurements and measurement errors, particularly in the presence of external vibrations, and current solutions either increase complexity and cost or are prone to mechanical issues.
Innovation Solution
A vibratory gyroscope sensor design featuring a resonator with a sidewall that has a proximal portion widening from a central foot to a distal portion, which is frustoconical in shape, effectively separating parasitic modes from primary and secondary modes by maintaining their frequencies significantly higher, and incorporating piezoelectric elements on the proximal portion for excitation and detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat-bottomed pot design or mushroom-shaped resonator is used, then manufacturing cost is reduced and dimensions are minimized, but parasitic structural modes (drum mode, flexural mode, rotational mode) appear that interfere with measurement accuracy and control stability
Solution Approach 1:
The resonator sidewall is designed with an asymmetric profile featuring a proximal portion that progressively widens from the foot towards the distal portion, rather than a uniform cylindrical shape. This asymmetric geometry modifies the structural modes and pushes parasitic modes (drum mode, flexural mode, rotational mode) to higher frequencies, reducing their interference with the primary measurement modes while maintaining manufacturing simplicity.
2Measurement precision
If more piezoelectric elements are added to reject parasitic mode signals, then signal rejection improves, but device complexity and cost increase
Solution Approach 1:
Instead of adding more piezoelectric elements, the invention changes the geometric parameters of the resonator sidewall by introducing a progressive widening profile. This parameter change in the structural geometry naturally shifts the frequencies of parasitic modes away from the measurement bandwidth, achieving signal rejection through frequency separation rather than through additional sensing elements.
3Object-affected harmful factors
If elastomeric vibration isolators are integrated to the base, then external vibration interference is reduced, but the system becomes excessively expensive and may cause rocking motion under transverse linear accelerations
Solution Approach 1:
The invention extracts the vibration isolation function from separate elastomeric isolators and integrates it directly into the resonator structure itself. The progressive widening sidewall profile inherently provides vibration isolation by modifying the structural modes and reducing coupling to external vibrations, eliminating the need for additional isolator components while avoiding the complexity and cost of separate isolation systems.
4Ease of manufacture
If a cylindrical sidewall is used, then manufacturing is simple, but parasitic modes occur at frequencies close to primary and secondary modes, causing control loop instability
Solution Approach 1:
The sidewall profile is made asymmetric by progressively widening from the foot towards the distal portion, breaking the uniform cylindrical symmetry. This asymmetric geometry modifies the structural modes and pushes parasitic modes (drum mode, flexural mode, rotational mode) to higher frequencies, reducing their interference with the primary measurement modes while maintaining manufacturing simplicity.
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 robust, accurate, and efficient angular velocity measurements by clearly distinguishing primary and secondary modes from parasitic modes, reducing measurement errors, and maintaining high-frequency parasitic modes away from the operational range, while being compact, lightweight, and cost-effective to manufacture.
Implementation Method 1
Piezoelectric elements are arranged on and against said cylindrical sidewall to excite the resonator into vibration
Implementation Method 2
Piezoelectric elements are arranged on and against said cylindrical sidewall to excite the resonator into vibration and detect the vibrations of the latter
Implementation Method 3
These vibratory gyrometers are based on Coriolis effect, which causes a vibrating object, having a 2nd-order resonance mode divided into a primary mode and a secondary mode that are modally orthogonal to each other, to undergo a force, when it rotates
Data Source
AI summary
A vibratory gyroscope sensor is provided. The vibratory gyroscope sensor consists of a base, and a resonator that includes a central foot attached to the base and a sidewall that rises from the foot up to a free end edge delimiting an opening. The sidewall has a proximal portion that extends from and around the foot and a cylindrical distal portion that extends in line with the proximal portion up to the free edge with the proximal portion progressively widening from the foot towards the distal portion.