Dual-Mode MEMS Gyroscope Readout for High Range and Resolution
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Solution Overview
Problem
Gyroscopes face a trade-off between high dynamic range and rate resolution, where high angular rate measurement capabilities come at the cost of poor resolution, and high-resolution gyroscopes have limited range, making them inadequate for applications requiring both.
Innovation Solution
A Coriolis vibratory gyroscope with a dual-mode readout system, comprising a coarse readout circuit for initial angular rate measurement and a fine readout circuit that adjusts drive frequencies and natural frequencies to derive a high-resolution difference, enabling both high range and fine resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a gyroscope is designed to operate at high angular rates, then the range is improved, but the resolution deteriorates
Solution Approach 1:
The gyroscope measurement system is segmented into two independent measurement paths: a first measurement path using a first pair of normal modes for coarse angular rate measurement, and a second measurement path using a second pair of normal modes for fine angular rate measurement. This segmentation allows each path to be optimized for its specific function, with the first path handling high-rate measurements and the second path providing high-resolution measurements, thereby resolving the contradiction between range and resolution.
2Measurement precision
If the resolution of the ADC is increased to improve rate resolution, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The measurement function is segmented between two ADCs: a first ADC with lower resolution (e.g., 16-bit) handling the coarse measurement from the first pair of modes, and a second ADC with higher resolution (e.g., 24-bit) handling the fine measurement from the second pair of modes. This segmentation allows the system to achieve high overall resolution without requiring a single high-resolution ADC across the full dynamic range, thereby reducing overall device complexity while maintaining measurement precision.
3Device complexity
If a single measurement system is used for both high range and fine resolution, then the device complexity is reduced, but the measurement precision deteriorates
Solution Approach 1:
The measurement system is divided into two parallel measurement paths using different pairs of normal modes. The first measurement path (first pair of modes) provides coarse measurement for high-rate accuracy, while the second measurement path (second pair of modes) provides fine measurement for high-resolution accuracy. By segmenting the measurement function across two specialized paths rather than using a single general-purpose system, the invention achieves both high range and fine resolution without compromising measurement precision.
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 dual-mode system achieves a high dynamic range with 19-bit resolution, allowing accurate angular rate measurement across a wide range, suitable for maneuverable aircraft and missiles.
Implementation Method 1
A Coriolis vibratory gyroscope with a dual-mode readout system, comprising a coarse readout circuit for initial angular rate measurement and a fine readout circuit that adjusts drive frequencies and natural frequencies to derive a high-resolution difference
Data Source
AI summary
A sensor includes an acceleration or magnetic field sensitive microelectromechanical systems (MEMS) resonator, configured to oscillate in at least a first normal mode and a second normal mode. The sensor further includes: a coarse readout circuit configured to drive the first normal mode, measure a motion of the first normal mode, and derive from the measured motion a coarse measurement of the true acceleration or true external magnetic field; and a fine readout circuit configured to drive the second normal mode, measure a motion of the second normal mode, and derive from the measured motion and the coarse measurement a measurement of the difference between the true acceleration or true external magnetic field and the coarse measurement.