MEMS Gyroscope Self-Calibration via Sensor Fusion
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Solution Overview
Problem
MEMS gyroscopes in consumer devices are susceptible to bias and gain errors, leading to inaccurate angular rotation measurements, especially in navigation applications, and require recalibration to maintain accuracy, which is challenging in the field without controlled laboratory conditions.
Innovation Solution
A mechanism using data from accelerometers and magnetometers to calculate rotation matrices and angular changes, allowing for the calculation of gyroscope trim parameters through linear regression analysis, enabling self-trimming and recalibration of MEMS gyroscopes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If MEMS gyroscope is used in consumer devices, then device functionality and motion sensing capability are improved, but bias errors and gain errors occur leading to measurement inaccuracy
Solution Approach 1:
The system uses feedback from accelerometer and magnetometer measurements to continuously monitor and correct gyroscope output. By comparing the gyroscope-derived orientation with the sensor fusion result from accelerometer and magnetometer, the system generates correction signals to eliminate bias and gain errors in real-time
Solution Approach 2:
The gyroscope calibration system is self-contained and operates autonomously using only the device's existing sensors. The system performs self-calibration by processing data from the accelerometer and magnetometer to generate correction parameters, eliminating the need for external calibration equipment or controlled environments
2Reliability
If gyroscope recalibration is performed in the field without controlled laboratory conditions, then device accuracy can be maintained over time, but the calibration process becomes complex and difficult to implement
Solution Approach 1:
The calibration system leverages the existing accelerometer and magnetometer, which are already present in consumer devices for other functions. By making these sensors serve the additional calibration function, the system avoids adding dedicated calibration hardware, thus reducing overall device complexity while enabling field recalibration
Solution Approach 2:
The system performs automatic self-calibration using algorithms that process sensor data and compute correction parameters without user intervention. The calibration process is embedded in the device software and executes autonomously, eliminating the need for complex manual procedures or specialized equipment
3Manufacturing precision
If manufacturer calibration is performed prior to shipping, then initial gyroscope accuracy is achieved, but the gyroscope requires field recalibration to maintain accuracy over time
Solution Approach 1:
The system implements continuous calibration by periodically updating gyroscope correction parameters using ongoing accelerometer and magnetometer measurements. This continuous process maintains accuracy over time by constantly adapting to drift and environmental changes, eliminating the need for periodic manual recalibration
Data Source
AI summary
A mechanism by which a MEMS gyroscope sensor can be calibrated using data gathered from other sensors in a system incorporating the MEMS gyroscope sensor is provided. Data gathered from an accelerometer and a magnetometer in fixed orientation relative to the gyroscope is used to calculate changes in orientation of a system. A constant acceleration vector measured by the accelerometer and a constant magnetic vector measured by the magnetometer are used as reference vectors in a solution to Wahba's problem to calculate a rotation matrix providing the system's orientation with respect to those two constant vectors. By comparing changes in orientation from one time to a next time, measured rates of angular change can be calculated. The measured rates of angular change can be used along with observed gyroscope rates of angular change as input to a linear regression algorithm, which can be used to compute gyroscope trim parameters.