Vibrating Angular Inertial Sensor Drift Correction by Wave Rotation
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Solution Overview
Problem
Existing vibrating inertial sensors suffer from measurement errors and drifts due to production errors and rotation commands, leading to reduced precision, and existing correction methods either introduce new errors or require additional reference sensors, making them costly and inefficient.
Innovation Solution
A method for correcting inertial sensor measurements by commanding a controlled rotation of the vibration wave, allowing for the subtraction of measurement errors without an additional reference sensor, using a correction method that involves commanding an electrical rotation of the vibration wave over a specific angular range and calculating the mean of measured angular values to determine the actual angular velocity and drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing correction methods are applied to reduce measurement errors, then measurement precision is improved, but new errors are introduced or additional reference sensors are required
Solution Approach 1:
The patent applies a rotation command to the vibration wave, which intentionally introduces a known error into the measurement. By knowing the exact rotation command applied, the system can subtract this known error from the measurement to obtain the true angular velocity. This converts the harmful effect of rotation-induced measurement errors into a beneficial correction mechanism, eliminating drift and scale factor errors without requiring additional sensors.
2Measurement precision
If additional reference sensors are used to correct measurements, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the inertial sensor self-correcting by using its own rotation command as the correction reference. The system applies a rotation command to the vibration wave and uses the known characteristics of this command to eliminate measurement errors. This self-service approach eliminates the need for additional reference sensors, reducing device complexity and cost while maintaining high measurement precision.
3Measurement precision
If rotation command is applied to correct measurements, then measurement precision is improved, but measurement errors occur during the correction process
Solution Approach 1:
The patent implements a feedback mechanism where the rotation command applied to the vibration wave is continuously monitored and its effect on the measurement is calculated. The system uses this feedback information to subtract the known error from the measurement in real-time, ensuring that the correction process itself does not compromise measurement reliability. The feedback loop ensures that any errors introduced during correction are immediately compensated.
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 method effectively reduces measurement errors and drifts, providing more precise angular velocity and angle measurements without the need for additional sensors, enhancing precision and reducing costs.
Implementation Method 1
The two masses are excited so as to vibrate in tuning fork mode in the plane of the plate (the xy plane in FIG. 1) via one or more excitation transducers
Implementation Method 2
When the sensor rotates about the z-axis perpendicular to the xy plane, with the z-axis being called 'sensitive axis ', the composition of the forced vibration with the angular rotation vector generates, by the Coriolis effect, forces that cause the movable masses to naturally vibrate perpendicular to the excitation vibration and to the sensitive axis
Data Source
AI summary
A measurement of a vibrating inertial sensor disposed on a carrier and includes a resonator extending around two mutually perpendicular x and y axes defining an xy sensor frame of reference and comprising: at least one vibrating movable mass comprising at least two portions configured to vibrate in phase opposition in a direction x′ defining an x′y′ wave frame of reference, with the vibration wave forming an electrical angle θ relative to the x-axis; at least a pair of excitation transducers and a pair of detection transducers operating along the two axes x and y; the correction method being applied when the sensor is operating with a vibration wave vibrating along the x′-axis and comprising the following steps, when the carrier is substantially stationary: A commanding an electrical rotation of the vibration wave according to a commanded angular velocity Ωc, such that the electrical angle θ scans at least one angular range of kπ radians; then B retrieving the measured angular values Ωe measured by the inertial sensor over the angular range, and determining the mean Ωem of the angular values measured; then C subtracting the commanded angular velocity Ωc from the mean Ωem; with steps A to C being carried out for at least two different commanded angular velocities so as to determine at least two means of the measured angular values; then D determining: the mean electrical scale factor error FEem, and the actual angular value Ωv of the carrier plus a drift value Dm of the sensor, the determining being carried out on the basis of the commanded angular velocity Ωc and of the means Ωem of the measured angular values, according to the following formula:Ωem−Ωc=(Ωv+Dm)+FEem·Ωc.