Gyroscope Field Calibration via Accelerometer Magnetometer Feedback
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Solution Overview
Problem
Micro-Electro-Mechanical Systems (MEMS) rate gyros are susceptible to bias and gain errors, which can lead to significant drift and accuracy issues in navigation devices, necessitating periodic recalibration in the field due to time-varying biases and gain errors that factory calibration cannot permanently correct.
Innovation Solution
A field calibration system that uses a sensor platform with gyroscopes, accelerometers, and magnetometers to determine rotation vectors, allowing for the calculation of compensation gains and biases by comparing measured gyroscope outputs with derived rotations from changes in the Earth's gravitational and magnetic fields, enabling accurate recalibration without specialized tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gyroscope is calibrated at the factory before installation, then initial accuracy is improved, but long-term accuracy deteriorates due to time-varying bias errors
Solution Approach 1:
The system performs preliminary calibration actions by rotating the sensor platform through known orientations and using the accelerometer and magnetometer to determine the expected rotation vectors before calculating gyroscope compensation parameters
Solution Approach 2:
The system continuously monitors gyroscope output and compares it with expected values derived from accelerometer and magnetometer data, using this feedback to calculate and apply compensation parameters that correct bias and gain errors
2Measurement precision
If the gyroscope is recalibrated periodically in the field, then long-term accuracy is maintained, but operational complexity increases
Solution Approach 1:
The sensor platform performs multiple functions simultaneously: the accelerometer measures gravitational changes for orientation determination, the magnetometer measures magnetic field changes for orientation determination, and the gyroscope measures rotation, all within the same calibration procedure
Solution Approach 2:
The system uses its own internal sensors (accelerometer, magnetometer, and gyroscope) to perform self-calibration without requiring external specialized calibration equipment or facilities
3Measurement precision
If specialized calibration tools are used, then calibration precision is improved, but accessibility deteriorates
Solution Approach 1:
The system performs self-calibration using its own integrated sensors (accelerometer, magnetometer, and gyroscope) without requiring external specialized calibration equipment, making the process accessible in field conditions
Solution Approach 2:
The accelerometer and magnetometer serve as intermediaries to determine the sensor platform's orientation and the expected rotation vectors, enabling indirect calibration of the gyroscope without direct access to precision rotation tables
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 method allows for effective compensation of bias and gain errors in gyroscopes, maintaining accuracy over time by recalibrating them in the field, even without precise control over the sensor platform's orientation, thereby reducing drift errors and ensuring reliable navigation device performance.
Implementation Method 1
at least one accelerometer mounted on the sensor platform and configured to sense changes in the earth's gravitational field due to rotation
Implementation Method 2
at least one magnetometer mounted on the sensor platform and configured to sense changes in the earth's magnetic field due to the rotation of the sensor platform
Data Source
AI summary
A method that compensates gyroscopes comprises rotating a sensor platform with three gyroscopes, three accelerometers and three magnetometers thereon; determining a first rotation vector Og based upon the rotation sensed by at least one of the three gyroscopes; determining a second rotation vector Om vector based upon the rotation sensed by the three accelerometers and the three magnetometers; and determining a compensation gain and a compensation bias for the at least one gyroscope based upon the first rotation vector and the second rotation vector.