Coriolis Vibratory Gyroscope Self-Calibration via Damping Axis Modulation
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Solution Overview
Problem
Coriolis vibratory gyroscopes (CVGs) face challenges with bias drift, which can lead to errors in rotation rate measurement and navigation systems, particularly due to the requirement for an atomic clock or stable frequency reference and the need for redundant sensors, limiting their continuous and online operation.
Innovation Solution
A Coriolis Vibratory Gyroscope control system employing Partial Input Axis Reversal (PIAR) and modulation of damping axes to induce a partial reversal of the gyroscope input axis, allowing for continuous bias drift estimation and cancellation without requiring an atomic clock or redundant sensors, using feedback loops to equalize damping rates and modulate damping time constants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If locking to atomic clock or stable frequency reference is used to reduce bias drift, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The gyroscope system performs self-calibration by automatically detecting and correcting its own bias drift through continuous mode reversal operations, eliminating the need for external atomic clocks or stable frequency references. The system uses its own operational characteristics to generate calibration signals and adjust its output accordingly.
Solution Approach 2:
The system changes operational parameters by dynamically reversing the gyroscope input axis modes, switching between different operational states to generate calibration data. This parameter modulation allows the system to extract bias information and correct it without requiring external frequency standards.
2Measurement precision
If continuous mode reversal is implemented to separate gyro bias from rate measurement, then measurement precision is improved, but productivity decreases due to switching periods
Solution Approach 1:
The system performs continuous calibration by seamlessly transitioning between calibration and measurement modes without interruption. The bias estimation and correction processes occur continuously during normal operation, eliminating dead time and maintaining uninterrupted useful action.
Solution Approach 2:
The system dynamically adjusts its operational state, continuously modulating between different measurement modes to perform calibration. This dynamic operation allows real-time bias estimation and correction without requiring static switching periods, maintaining continuous productivity.
3Reliability
If full mode reversal is used to eliminate bias drift, then reliability is improved, but device complexity increases due to redundant sensors
Solution Approach 1:
A single gyroscope sensor performs self-calibration by exploiting its own operational characteristics. The system generates calibration signals through controlled mode reversal and uses these signals to estimate and correct its own bias, eliminating the need for redundant sensors while maintaining high reliability.
Solution Approach 2:
The single gyroscope sensor serves multiple functions: it performs both normal rate measurement and self-calibration operations. By dynamically reversing its input axis modes, the same sensor generates the data needed for bias estimation and correction, making the system universally functional without redundancy.
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
Enables continuous and online operation of CVGs with reduced bias drift, improving measurement accuracy and eliminating the need for redundant sensors or atomic clocks, thereby enhancing navigation system reliability.
Implementation Method 1
When the device rotates about a particular body-fixed axis, the resulting Coriolis forces acting on the body's vibrating mass elements excite a different resonant mode.
Implementation Method 2
one of the resonant modes of an elastic body or resonator is excited to a prescribed amplitude
Implementation Method 3
different first and second damping rates; first and second damping feedback circuits arranged for: generating first and second damping feedback signals proportional respectively to the first and second damping rates
Data Source
AI summary
A CVG having first and second degenerate resonator modes with each a damping rate; drive circuits for causing the resonator to oscillate in the first and second modes in response to first and second drive signals; first and second sense circuits for generating first and second sense signals in response to the resonator oscillating in the first and second modes; a signal processing circuit having control loops for generating the first and second drive signals based on the first and second sense signals; and first and second damping feedback circuits for generating first and second damping feedback signals proportional to the first and second damping rates; an adding the damping feedback signals to the first and second drive signals.