Dual RTK Engine Position Estimation for Signal Quality Issues
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Solution Overview
Problem
Location-determining receivers, such as GPS receivers, face challenges in accurately estimating the position and attitude of objects or vehicles due to imprecise pseudo-range and carrier phase measurements, especially when receiving satellite signals of low signal strength or poor quality, as existing error-reducing filters and RAIM techniques do not fully address these issues.
Innovation Solution
The method involves using dual real-time kinematic (RTK) engines with a primary and secondary engine, where the primary engine estimates a primary integer ambiguity set and the secondary engine estimates a secondary integer ambiguity set, with reinitialization and swapping of roles based on reliability tests and error evaluation to enhance accuracy, especially during periods of poor signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single RTK engine is used for position estimation, then the system complexity is low, but the reliability deteriorates when signal quality is poor or the engine states become corrupt
Solution Approach 1:
The system divides the single RTK engine into two separate RTK engines (first and second) that operate independently. Each engine processes carrier phase measurements separately, allowing one to compensate when the other fails or produces corrupt results, thereby improving reliability without requiring a complete system redesign
Solution Approach 2:
The system performs preliminary reliability testing on integer ambiguity solutions before final position estimation. The quality evaluator assesses the validity of solutions from both RTK engines before they are used, preventing corrupt data from degrading the overall position estimation reliability
2Measurement precision
If error-reducing filters or RAIM techniques are used, then some measurement errors are reduced, but the accuracy deteriorates when receiving satellite signals of low signal strength or poor signal quality
Solution Approach 1:
The system implements a feedback mechanism where the quality evaluator continuously monitors the output of both RTK engines and the carrier phase measurements. When measurement precision degrades due to poor signal quality, the feedback loop detects this through reliability testing and triggers reinitialization or engine swapping to maintain position estimation reliability
Solution Approach 2:
The system changes the operational parameters of the RTK engines dynamically. When signal quality deteriorates, the system reinitializes engines at different time offsets or swaps which engine is primary, effectively changing the operational state to adapt to poor measurement conditions and maintain reliability
3Reliability
If the RTK engine is reinitialized frequently to address corrupt states, then the reliability improves, but the loss of time increases due to reinitialization overhead
Solution Approach 1:
The system performs preliminary reliability testing on integer ambiguity solutions before they are committed to position estimation. By detecting potential corruption early through quality evaluation, the system can address issues before they cause complete failure, reducing the need for full reinitialization and minimizing time loss
Solution Approach 2:
The system maintains a backup RTK engine that can take over immediately when the primary engine fails or produces corrupt results. This copying approach allows for faster recovery compared to reinitializing the same engine, as the backup engine already has valid state information ready to use
4Reliability
If dual RTK engines are used with different start-up times, then the reliability improves through diverse ambiguity solutions, but the device complexity increases
Solution Approach 1:
The system segments the RTK processing into two independent engine instances with distinct start-up times. This segmentation creates diversity in the integer ambiguity solutions produced by each engine, allowing the quality evaluator to select the more reliable solution while the structural complexity remains manageable through modular design
Solution Approach 2:
The dual RTK engine system is designed with universal functionality where either engine can serve as the primary position estimation source. The quality evaluator and controller manage both engines uniformly, allowing the system to adapt to different operational conditions without requiring complex engine-specific management logic
Data Source
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AI summary
A method and system for estimating the position comprises measuring a first carrier phase of a first carrier signal and a second carrier phase of a second carrier signal received by a location-determining receiver (10). A primary real time kinematic (RTK) engine (18) or receiver data processing system (16) estimates a primary integer ambiguity set associated with at least one of the measured first carrier phase and the measured second carrier phase. A quality evaluator (22) determines if a primary integer ambiguity set is resolved correctly to the predefined reliability rate during an earlier evaluation period. A secondary real time kinematic (RTK) engine (20) or receiver data processing system (16) estimates a secondary integer ambiguity set associated with at least one of the measured first carrier phase and the measured second carrier phase during a later period following the earlier evaluation period.