Gyroscope Error Estimation Using Magnetometer and Rotational Rate
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Solution Overview
Problem
Consumer-grade gyroscopes in portable navigation devices suffer from time-varying errors, which cannot be effectively mitigated by Global Navigation Satellite System (GNSS) technology in signal-degraded environments like indoors, due to man-made and environmental interference.
Innovation Solution
The use of magnetometers to detect a quasi-static magnetic field and combine it with the rotational rate of the device to estimate and correct for gyroscope errors, employing an Extended Kalman Filter for accurate bias estimation and error compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If consumer-grade gyroscopes are used in portable navigation devices, then device cost is reduced, but gyroscope accuracy deteriorates due to time-varying errors
Solution Approach 1:
The patent introduces magnetometers as an intermediary sensor to detect the local magnetic field. By combining magnetic field measurements with gyroscope data, the system creates a mediator mechanism that helps identify and compensate for gyroscope errors, thereby improving accuracy without increasing device cost
Solution Approach 2:
The system implements feedback by continuously monitoring the magnetic field and comparing expected versus actual gyroscope behavior. When discrepancies are detected, the system generates correction signals that feed back to compensate for gyroscope errors, maintaining accuracy over time
2Measurement precision
If GNSS technology is used to compensate for sensor errors, then navigation accuracy is improved, but reliability deteriorates in signal-degraded environments
Solution Approach 1:
The system performs self-service by using its own onboard magnetometer and gyroscope to detect and compensate for errors autonomously. This self-contained error mitigation mechanism does not rely on external GNSS signals, ensuring reliable operation in signal-degraded environments
Solution Approach 2:
The system dynamically adapts by continuously monitoring magnetic field changes and adjusting error compensation in real-time. This dynamic approach allows the system to maintain navigation accuracy under varying environmental conditions without requiring GNSS signals
3Measurement precision
If magnetometers are used to estimate gyroscope errors, then gyroscope accuracy is improved, but device complexity increases
Solution Approach 1:
The magnetometer serves multiple functions: it detects the local magnetic field for orientation determination, identifies quasi-static periods for error estimation, and provides data for compensating gyroscope errors. This multi-functionality reduces overall system complexity by eliminating the need for dedicated error detection hardware
4Ease of operation
If the IMU location is not body-fixed in PND applications, then ease of operation is improved, but error mitigation capability deteriorates
Solution Approach 1:
The magnetic field serves as an intermediary reference that is independent of IMU location. By using the Earth's magnetic field as a stable reference frame, the system can compensate for gyroscope errors regardless of whether the IMU is body-fixed or handheld, maintaining error mitigation capability while preserving ease of operation
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 significantly improves the accuracy of gyroscope bias estimation and trajectory tracking, enabling effective navigation in various environments by compensating for time-varying gyroscope errors, even in areas with significant magnetic perturbations.
Implementation Method 1
uses magnetometers to detect and measure a magnetic field local to a personal navigation device
Implementation Method 2
When the local magnetic field is quasi-static, the rate of change of the magnetic field is combined with the rotational rate of change of the device. This generates an estimated gyroscope error.
Data Source
AI summary
Methods and systems for compensating for gyroscopic errors. A system uses magnetometers to detect and measure a magnetic field local to a personal navigation device. When the local magnetic field is quasi-static, the rate of change of the magnetic field is combined with the rotational rate of change of the device. This generates an estimated gyroscope error. The error can then be used to correct for time-varying inherent gyroscope errors.