Gyroscopic Sensor Calibration for Vibration-Mode Scale-Factor Errors
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Solution Overview
Problem
Existing gyroscopic measurement methods suffer from measurement errors due to various defects, including stiffness and damping anisotropies, electronic control component defects, and reference voltage instabilities, which are not effectively addressed by existing calibration techniques, leading to non-zero mean errors over sensor rotation periods.
Innovation Solution
A gyroscopic measurement method and sensor that controls the alternating rotation of pilot and detection modes, utilizing a calibration process involving servoing of vibration amplitudes and forces to minimize harmonic errors, where a stable force is exerted in phase quadrature with the actual force to estimate and correct measurement errors without explicit force values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If command signals are used to rotate the geometrical vibration position of the gyroscope, then the calibration of the gyroscope is improved, but measurement errors due to conversion chain errors and voltage instabilities are not eliminated
Solution Approach 1:
The patent replaces the electronic command signal-based rotation control with a mechanical rotation of the entire sensor housing. By physically rotating the housing at a known angular velocity, the system eliminates errors from the conversion chain (electronic components, voltage instabilities) while maintaining the ability to control vibration position rotation for calibration purposes.
Solution Approach 2:
The patent introduces a mechanical rotation stage as an intermediary between the inertial reference and the gyroscope sensor. This intermediary provides a known, stable rotational motion that decouples the calibration process from the unstable electronic command signals, allowing accurate determination of scale factor without exposure to electronic errors.
2Measurement precision
If the direction of rotation of the sensor is periodically alternated, then scale factor errors are reduced, but the measurement process becomes more complex
Solution Approach 1:
The patent implements periodic alternation of the sensor rotation direction, rotating the housing in one direction during calibration phases and in the opposite direction during other calibration phases. This periodic reversal allows the system to measure and eliminate scale factor errors while maintaining a relatively simple measurement process compared to complex electronic control schemes.
3Measurement precision
If electrostatic means are used to modify the geometrical vibration position, then calibration is improved, but errors in the conversion chain and reference voltage instabilities persist
Solution Approach 1:
The patent replaces electrostatic means of modifying vibration position with a purely mechanical approach. By rotating the entire housing mechanically, the system achieves position modification without relying on electrostatic actuators, thereby eliminating errors from the conversion chain and reference voltage instabilities that affect electrostatic control.
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 reduces measurement errors, particularly scale factor errors, by stabilizing the force applied to the sensor, allowing for accurate determination of angular speed without relying on unstable command signals, thus improving measurement precision.
Implementation Method 1
the displacement of the vibrating element along the direction of the pilot mode generates a Coriolis force. Said force excites the vibrating element along the direction of the detection mode, at an amplitude which is proportional to the component along the axis of sensitivity of the instantaneous speed of rotation vector.
Data Source
AI summary
The present invention relates to a sensor (10) comprising a housing (12) and a vibrating element (15) apt to vibrate relative to the housing (12), comprising:an initialization (410), to provide a pilot amplitude (xmax), a detection amplitude (ymax), an adjustment command (Tth) of predetermined spectral signature, and a calibration angular speed (Ωcal);a calibration (420), comprising the servoing to the pilot amplitude and to the detection amplitude of the vibrations of the vibrating element (15) along the direction (x) of the pilot mode and the direction (y) of the detection mode, and simultaneously the exertion of a first stable force (Fy,phase,suppapp) configured not to disturb the measurement of the sensor (10) from the adjustment command (Tth), as well as the application of a second force (Fy,quadapp) determined on the basis of the spectral signature of the adjustment command so as to cause a rotation of the direction of the pilot mode, an instantaneous angular speed (Ω(t)) of the housing (12) being imposed as equal to the calibration angular speed (Ωcal), and the determination of a reference angular speed (Ωref);an acquisition (430), analogous to the calibration but with a free instantaneous angular speed (Ω(t)); a determination (440) of a measured instantaneous angular speed (Ωmes(t)).