Self-Calibrating Gyroscope System for Bias Error Compensation
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Solution Overview
Problem
Hemispherical resonator gyroscopes (HRGs) face limitations due to bias and scale factor errors caused by imperfections in the resonator shape, electrodes, and signal processing systems, which are difficult to correct, especially in applications where manual recalibration is not feasible, such as in space vehicles or under rapid environmental changes.
Innovation Solution
A self-calibrating gyroscope system comprising a plurality of non-coaxial gyroscopes with a control system that employs mode reversal for bias error determination and random closed-loop scale factor estimation to compensate for errors, allowing continuous operation and accurate rate estimates in three dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual calibration is performed during manufacturing or testing, then initial bias and scale factor errors are corrected, but the system cannot be recalibrated in space applications or under rapid environmental changes
Solution Approach 1:
The gyroscope system performs self-calibration using redundant sensors and algorithms to automatically determine and correct bias and scale factor errors without external intervention. The system uses its own redundant measurements to identify and compensate for errors, enabling continuous operation in space applications where manual recalibration is impossible.
Solution Approach 2:
The system employs feedback mechanisms where measurements from redundant gyroscopes are continuously compared and used to adjust calibration parameters. The calibration process uses real-time performance data to iteratively improve accuracy, allowing the system to adapt to environmental changes and maintain precision throughout the mission.
2Measurement precision
If redundant gyroscopes are added to enable self-calibration, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The calibration function is segmented from the main measurement function, allowing redundant gyroscopes to be dedicated specifically to calibration tasks while other gyroscopes provide primary measurements. This division enables error compensation without requiring all gyroscopes to simultaneously perform both measurement and calibration functions.
Solution Approach 2:
The redundant gyroscope array serves multiple functions: primary angular rate sensing, bias error determination, scale factor calibration, and fault detection. Each gyroscope can be dynamically allocated to different functions based on system needs, maximizing the utility of the redundant hardware and reducing overall system complexity.
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 system effectively minimizes scale factor and bias errors through continuous self-calibration, ensuring reliable angular rate measurements even in environments where manual recalibration is impractical, maintaining accuracy over time and under varying conditions.
Implementation Method 1
The resonator is typically caused to vibrate by applying an oscillating forcing signal at a frequency near the resonant frequency of the resonator
Implementation Method 2
The signal may be an electrical signal and may be coupled to the resonator electrostatically
Data Source
AI summary
A self-calibrating gyroscope system provides improved estimates of, and compensation or calibration for, scale factor errors and bias errors. The gyroscope system employs a plurality of gyroscope units having sense or input axes in a mutually non-parallel arrangement. The number of gyroscope units is preferably at least one more than the number of axes for which rate estimates is required. A Mode Reversal technique is used to obtain an estimate of bias error for a selected gyroscope. A Random Closed-Loop Scale Factor technique is used to obtain an estimate of scale factor error for a selected gyroscope. Because the Mode Reversal technique temporarily disrupts operation of the affected gyroscope, each of the gyroscopes may be taken offline temporarily, in turn, for calibration, and thereafter returned to normal operation. Because at least one redundant gyroscope is provided, when a selected gyroscope is offline, rate information from the remaining operating gyroscopes can be used to derive a reference rate about the axis of the offline gyroscope.