Hybrid Vehicle Positioning System with Inertial Navigation
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Solution Overview
Problem
Existing GPS positioning systems struggle to accurately determine a vehicle's position when radio signals from a sufficient number of GPS satellites are not available, particularly due to altitude variations and imprecise clock synchronization, leading to decreased accuracy in position estimation.
Innovation Solution
A positioning system that combines radio signals from artificial satellites with inertial navigation to estimate a vehicle's position, using the point closest to the inertial-navigation-based position as the satellite-based position when fewer than three GPS satellites are available, and correcting this position based on inertial navigation to ensure accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If GPS positioning is used with fewer than three satellites, then positioning can be performed in satellite-denied environments, but positioning accuracy deteriorates due to altitude variations and clock errors
Solution Approach 1:
The patent combines satellite-based positioning with inertial navigation to create a hybrid positioning system. When satellite signals are insufficient (fewer than three satellites), the inertial navigation component compensates for the loss of accuracy by providing alternative position estimation based on previous position and motion data, thus maintaining positioning availability while mitigating accuracy deterioration
Solution Approach 2:
The patent introduces map matching as an intermediary mechanism between the raw satellite position data and the final position output. When satellite signals are weak, the system uses map matching to constrain the position estimate to valid locations on the road network, thereby improving positioning accuracy without requiring additional satellites
2Measurement precision
If four GPS satellites are used to correct time errors, then positioning accuracy is improved, but positioning becomes impossible when fewer than four satellites are available
Solution Approach 1:
The system performs preliminary position estimation using inertial navigation before satellite data becomes available or when satellite availability is low. The inertial navigation system continuously updates the position estimate based on acceleration and orientation data, so when satellite signals arrive (even if fewer than four), the system already has a refined position estimate to work with, reducing the need for time error correction
Solution Approach 2:
The patent dynamically changes the positioning parameters based on satellite availability. When four or more satellites are available, the system uses full GPS positioning with time error correction. When fewer than four satellites are available, the system switches to inertial navigation mode with adjusted parameters, thereby maintaining positioning availability across different satellite conditions
Data Source
AI summary
A positioning system 10 includes a positioning unit 15 configured to perform position estimation based on radio signals from artificial satellites and an autonomous navigation unit 14 configured to perform position estimation by autonomous navigation. In the positioning system 10, the positioning unit 15 and the autonomous navigation unit 14 estimate the position of a mobile body in cooperation with each other; and when the number of the artificial satellites available is less than three, the positioning unit determines a point in an area calculated based on the radio signals which point is closest to an inertial-navigation-based position calculated by autonomous navigation, and uses the determined point as a satellite-based position estimated based on the radio signals.