Aircraft Navigation Hybridization Correcting Ionospheric Errors
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Solution Overview
Problem
Current navigation systems, particularly during aircraft approach and take-off phases, face challenges in achieving the required precision and integrity due to ionospheric errors and multipath effects, which are not adequately addressed by existing satellite navigation systems or hybridization techniques using inertial sensors and GNSS measurements.
Innovation Solution
A mobile navigation system that combines inertial sensor measurements with multi-channel radio frequency receivers, utilizing Kalman filters for hybridization to correct errors caused by ionospheric biases, multipaths, satellite clock errors, and receiver internal errors, while also accounting for dynamic aircraft dynamics and signal noise, to provide accurate and reliable positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If satellite navigation systems (GNSS) are used for aircraft navigation, then positioning coverage is improved, but measurement precision deteriorates due to ionospheric errors and multipath effects
Solution Approach 1:
The patent combines multiple positioning systems (GNSS, inertial sensors, barometric altimeter) into a hybrid navigation system that integrates their measurements through a Kalman filter, thereby maintaining the coverage advantage of GNSS while compensating for its precision limitations through complementary sensor data
Solution Approach 2:
The patent introduces an ionospheric error modeling component as an intermediary that specifically addresses and corrects ionospheric delays affecting GNSS signals, allowing the system to maintain GNSS coverage while eliminating the primary source of measurement error
2Adaptability or versatility
If hybridization techniques combining inertial sensors and GNSS measurements are used, then positioning coverage is improved, but measurement precision deteriorates due to uncorrected ionospheric and multipath errors
Solution Approach 1:
The patent introduces specific intermediaries (ionospheric error model, multipath error model) that act between the raw GNSS measurements and the final positioning solution, correcting these systematic errors before integration with other sensor data in the Kalman filter
Solution Approach 2:
The patent changes the parameters being measured and corrected by incorporating carrier phase measurements in addition to code measurements, and by explicitly modeling and correcting for ionospheric delay parameters and multipath error parameters in the state vector of the Kalman filter
3Ease of operation
If classic hybridization techniques are used during approach and take-off phases, then navigation capability is maintained, but measurement precision deteriorates significantly due to ionospheric propagation errors and multipaths
Solution Approach 1:
The patent introduces error correction intermediaries (ionospheric model, multipath model) that specifically target and correct the dominant error sources during critical flight phases, enabling reliable navigation when precision requirements are highest
Solution Approach 2:
The patent applies preliminary corrections for ionospheric delays and multipath errors to GNSS measurements before they are integrated into the navigation solution, proactively eliminating error sources rather than reacting to their effects
Data Source
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AI summary
The invention relates to a navigation system for an aircraft that comprises inertial sensors, a GNSS receiver and optionally a baro-altimeter. The measures of the inertial sensors are hybridised with the code and phase measures of the receiver within a main Kalman filter and optionally secondary filters. Said measures are corrected for several types of errors, in particular those due to the crossing of ionosphere layers by satellite signals. The precision in the determination of the aircraft position is significantly improved, both for the horizontal plane and in the vertical direction. This is also the case for corresponding protection rays, which allows for the creation of margins in order to satisfy the integrity requirements of the navigation solution.