Gyroscope Bias Error Rejection via Continuous Mode Reversal
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Solution Overview
Problem
Current gyroscopes face challenges with bias error due to environmental variations like temperature and pressure, requiring frequent recalibration and being inadequate for precision applications, especially in navigation where they are sensitive to ambient conditions.
Innovation Solution
The method involves continuous time modulation to shift bias error from DC to a higher frequency, allowing for its removal through filtering, and uses dual-axis excitation and sensing in vibratory gyroscopes to cancel bias errors without interrupting the measurement process or requiring a reference angular rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration is utilized to cancel gyroscope offset, then gyroscope bias error is reduced, but periodic recalibration is required due to environmental variations
Solution Approach 1:
The patent applies periodic modulation at a specific frequency (e.g., 100 Hz) to the gyroscope sensing element. This periodic action shifts the bias error to a higher frequency domain where it can be separated from the DC component through filtering, enabling continuous bias rejection without periodic recalibration interruptions.
Solution Approach 2:
The patent uses a model of the bias error behavior to create a reference signal that copies the characteristics of the drift. By generating this reference signal at the modulation frequency and using it in the filtering process, the system can continuously track and reject bias errors without requiring external calibration references or interrupting normal operation.
2Measurement precision
If conventional calibration methods are used, then gyroscope offset is canceled, but the process interrupts the ordinary rate measurement process
Solution Approach 1:
The patent implements continuous bias rejection by modulating the sensing element throughout the entire measurement process. The modulation and subsequent filtering occur continuously alongside normal rate measurements, eliminating the need to interrupt measurements for calibration and maintaining uninterrupted productivity.
3Reliability
If conventional gyroscopes are used in navigation applications, then basic orientation measurement is achieved, but bias error and sensitivity to ambient variations remain problematic
Solution Approach 1:
By applying periodic modulation to the gyroscope operation, the patent shifts bias errors to a frequency where they can be continuously rejected through filtering. This resolves the contradiction by maintaining reliable navigation performance while significantly reducing bias error through the frequency-domain separation technique.
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
This approach results in gyroscopes with significantly reduced bias error, suitable for navigation and other applications, providing continuous calibration and improved sensitivity to ambient variations.
Implementation Method 1
a first mode of vibration in a first axis of motion and an associated first natural frequency, and a second mode of vibration in a second axis of motion having an associated second natural frequency, wherein angular rate of motion input couples energy between the first mode of vibration and the second mode of vibration
Data Source
AI summary
A vibratory gyroscope system is described which utilizes a mechanical resonator having a first mode of vibration and an associated first natural frequency, and a second mode of vibration having an associated second natural frequency. The angular rate of motion input couples energy between the first and second modes of vibration. The gyroscope has driver circuits, sensors and actuators for the first and second modes. The invention utilizes a bias error shifting method which provides for shifting the bias error away from DC to a higher frequency, where it can be removed by low pass filtering. As a result of the inventive method, gyroscope systems can be produced with significantly lower bias error.