Inertial Navigation System Fault Detection via Dual-Path Comparison
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Solution Overview
Problem
Conventional inertial navigation systems (INS) face challenges in accurately detecting and correcting for faults in gyroscope and accelerometer measurements, leading to potential navigation performance losses due to uncorrected errors and biases.
Innovation Solution
A vehicle system with a primary and secondary INS unit, where the secondary unit calculates kinematic state vectors without GNSS signals, allowing for the identification of IMU faults by comparing the two sets of state vectors, enabling more accurate error detection and correction through a health management system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional approaches use aiding sensors to correct navigation errors, then navigation performance is improved, but the system cannot detect or correct accelerometer and gyroscope measurement faults
Solution Approach 1:
The system segments the navigation solution into two independent paths: a primary INS solution that uses all available sensors including GNSS for high accuracy, and a secondary INS solution that uses only inertial sensors without GNSS. This segmentation allows the primary solution to maintain high navigation accuracy while the secondary solution provides a fault-detection reference, resolving the contradiction between measurement precision and reliability.
2Difficulty of detecting and measuring
If the secondary INS allows errors to grow without bound, then fault identification becomes easier, but navigation accuracy deteriorates
Solution Approach 1:
The system introduces a health management system as an intermediary that compares the primary and secondary INS solutions. The secondary INS serves as a deliberate intermediary with degraded accuracy that allows errors to grow, making faults detectable. The health management system mediates between the two solutions, using their differences to identify faults while maintaining overall navigation accuracy through the primary solution.
3Device complexity
If a single INS unit is used, then system complexity is reduced, but the ability to identify IMU faults is limited
Solution Approach 1:
The system creates a copy of the INS computation path (secondary INS) that deliberately excludes GNSS inputs. This copy serves as a reference model for detecting faults in the primary INS. By maintaining this simplified copy, the system gains fault identification capability without requiring complex additional hardware, as the secondary INS uses the same inertial sensors but follows a different computational path.
Data Source
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AI summary
An inertial navigation system (INS) includes a primary inertial navigation system (INS) unit configured to receive accelerometer measurements from an accelerometer and angular velocity measurements from a gyroscope. The primary INS unit is further configured to receive global navigation satellite system (GNSS) signals from a GNSS sensor and to determine a first set of kinematic state vectors based on the accelerometer measurements, the angular velocity measurements, and the GNSS signals. The INS further includes a secondary INS unit configured to receive the accelerometer measurements and the angular velocity measurements and to determine a second set of kinematic state vectors of the vehicle based on the accelerometer measurements and the angular velocity measurements. A health management system is configured to compare the first set of kinematic state vectors and the second set of kinematic state vectors to determine faults associated with the accelerometer or the gyroscope based on the comparison.