GNSS Receiver Positioning Quality via Adaptive Smoothing
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Solution Overview
Problem
Navigation receivers operating in differential navigation mode face challenges in maintaining positioning quality when accuracy estimates change, leading to disruptions in communication with base stations or external influences, resulting in reduced accuracy and increased errors.
Innovation Solution
A two-branch algorithm is employed to generate smoothed estimates of coordinates, using primary estimates and accuracy estimates from previous epochs, with threshold accuracy adjustments and error signal corrections to maintain positioning quality during changes in accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If differential navigation mode is used to improve positioning accuracy, then positioning quality is improved, but the system becomes vulnerable to disruptions in communication with base stations or external influences
Solution Approach 1:
The system dynamically changes the smoothing parameter alpha based on the reliability of primary estimates. When accuracy estimates indicate good quality, alpha is set to emphasize primary estimates (higher weight). When accuracy deteriorates due to disruptions, alpha is adjusted to rely more on extended estimates. This adaptive parameter adjustment resolves the contradiction by optimizing the balance between using accurate primary estimates and maintaining stability during disruptions.
Solution Approach 2:
The system uses accuracy estimates as feedback to monitor the quality of primary estimates in real-time. This feedback mechanism detects when disruptions occur and triggers adaptive adjustment of the smoothing algorithm parameters. The feedback loop enables the system to automatically respond to changing conditions, maintaining reliability while preserving positioning accuracy when possible.
2Measurement precision
If primary estimates are used to improve positioning accuracy, then measurement precision is improved, but smoothness of coordinate estimates deteriorates when accuracy changes occur
Solution Approach 1:
The smoothing parameter alpha is made dynamic rather than fixed. It adapts its value based on the reliability of primary estimates, allowing the system to optimize the trade-off between accuracy and smoothness in real-time. When primary estimates are reliable, the system dynamically increases their weight; when reliability drops, it dynamically reduces their weight to maintain smoothness.
3Stability of the object's composition
If smoothing is increased to improve coordinate smoothness, then stability of estimates is improved, but responsiveness to actual position changes deteriorates
Solution Approach 1:
The smoothing parameter alpha is adjusted dynamically based on accuracy estimates. When primary estimates are reliable, alpha is set to allow faster response to position changes (lower smoothing). When accuracy deteriorates, alpha is increased to provide stronger smoothing and stability. This resolves the contradiction by making the smoothing level adaptive rather than fixed.
Data Source
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AI summary
A navigation receiver operating in a differential navigation mode transmits primary estimates of coordinates with an accuracy estimate that can vary during operation. To improve the positioning quality when the accuracy estimate changes, smoothed estimates of coordinates are generated according to a two-branch algorithm. The current-epoch accuracy estimate is compared to a current-epoch value of threshold accuracy. Upon determining that the current-epoch accuracy estimate is greater than or equal to the current-epoch value of threshold accuracy, the current-epoch smoothed estimates of coordinates are set equal to the current- epoch extended estimates of coordinates calculated from the sum of the previous smoothed estimates of coordinates and coordinate increments calculated from carrier phases. Upon determining that the current-epoch accuracy estimate is less than the current-epoch value of threshold accuracy, the current-epoch smoothed estimates of coordinates are generated based on the sum of the current-epoch extended estimates of coordinates and a correction signal.