GPS Navigation Position Correction Using Error Range Logic
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Solution Overview
Problem
Existing navigation systems face increased error when correcting GPS-measured positions, as they either ignore slight differences when the position is slightly out of the estimated error range or incorrectly correct positions when the actual position is far out of the range, leading to inaccuracies in positioning and travel direction.
Innovation Solution
A navigation system that includes a GPS receiver, an error-range setting section, and a position correction section, which sets an estimated error range based on velocity and travel angle, and corrects the measured position by considering the relative positional relationship to ensure the corrected position lies within the error range, thereby improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the estimated error range is set centering at the estimated measured position, then the navigation system can use the estimated measured position when the current measured position is out of the estimated error range, but the estimated measured position is inevitably set at the center of the estimated error range, causing error to increase when the actual measured position is slightly out of the estimated error range
Solution Approach 1:
The patent applies local quality by differentiating the correction approach based on the specific positional relationship between the actual measured position and the estimated error range. When the actual measured position is slightly out of the estimated error range, the system performs correction to bring it within the range. When the actual measured position is greatly out of the estimated error range, the system uses the estimated measured position without correction. This localized differentiation of correction strategies optimizes positioning precision for different error scenarios while maintaining overall reliability.
2Measurement precision
If the navigation system uses the actual measured position when it is in the estimated error range, then positioning can be accurate, but when the actual measured position is greatly out of the estimated error range, the corrected measured position may be out of the estimated error range, increasing error
Solution Approach 1:
The patent inverts the conventional correction approach by not blindly applying correction to all out-of-range positions. Instead, it inverts the logic to say: when the actual measured position is greatly out of the estimated error range, do not correct it, but use the estimated measured position. This inversion of the correction strategy for extreme cases prevents creating new errors while maintaining the benefit of correction for moderate errors.
Solution Approach 2:
The patent changes the parameter of correction application based on the degree of position deviation. It introduces a threshold-based parameter change: for small deviations (actual position slightly out of range), apply correction; for large deviations (actual position greatly out of range), do not apply correction. This parameter change in the correction strategy optimizes both precision and reliability by adapting the correction behavior to the severity of the error.
3Measurement precision
If the navigation system corrects the measured position by adding the estimated measured position and the actual measured position through predetermined weighting, then correction can be applied, but the corrected measured position may be out of the estimated error range when the actual measured position is greatly out of the estimated error range
Solution Approach 1:
The patent applies local quality by implementing different correction strategies based on the specific condition of the actual measured position. When the actual measured position is slightly out of the estimated error range, the system applies correction to improve precision. When the actual measured position is greatly out of the estimated error range, the system switches to using the estimated measured position without correction. This localized differentiation prevents the weighted average correction from producing inaccurate results in extreme cases.
Data Source
AI summary
A navigation system includes a GPS receiver for receiving radio waves transmitted from multiple GPS satellites and producing a measured position, an error-range setting unit for setting an estimated error range in which a measured position at the time of current positioning by the GPS receiver is included, a relative-position determining unit, and a position correcting unit. The relative-position determining unit and the position correcting unit correct the measured position by using an actual measured position, when the actual measured position produced by the GPS receiver at the current positioning time is in the estimated error range. The relative-position determining unit and the position correcting unit correct the measured position in accordance with a relative positional relationship between the actual measured position and the estimated error range, when the actual measured position is out of the estimated error range.