Mobile Object Position Estimation Using Inertial and Map Data Fusion
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Solution Overview
Problem
Conventional mobile object position estimation systems, relying on GPS and inertial navigation sensors, face accuracy limitations due to poor map information accuracy and 'node skipping', leading to significant position errors, especially when GPS signals are weak, which can compromise vehicle control systems.
Innovation Solution
A mobile object position estimation apparatus that synthesizes data from inertial navigation sensors and map information, using node information for accurate direction estimation and interpolation to correct for road contour inaccuracies, allowing for high-accuracy position estimation independent of road contours and environmental influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If map matching processing is performed to correct position errors, then position estimation accuracy is improved, but the accuracy is limited by the accuracy of map information itself which contains node skipping and incomplete road contour representation
Solution Approach 1:
The patent introduces an intermediary approach by using inertial navigation sensor outputs as a mediator between GPS position estimates and map information. Instead of directly correcting GPS positions using potentially inaccurate map data, the system uses inertial navigation data as an intermediate reference that can be continuously updated without being constrained by map node skipping or incomplete road contour representations, thereby resolving the limitation where map matching accuracy is capped by map information accuracy
Solution Approach 2:
The patent replaces the conventional mechanical map matching process with a hybrid navigation system that substitutes pure map-based correction with a combination of inertial navigation and GPS data fusion. This substitution allows the system to maintain position estimation accuracy independent of map information completeness, as the inertial navigation system can operate autonomously without requiring complete road contour data
2Adaptability or versatility
If inertial navigation sensors are used to estimate position, then position can be estimated during poor GPS reception, but accuracy deteriorates with time due to drift
Solution Approach 1:
The patent merges multiple navigation systems (GPS and inertial navigation) into a hybrid system that combines their strengths. The GPS provides absolute position references when available, while the inertial navigation system provides continuous position estimation during GPS outages. By merging these systems through data fusion, the patent achieves both adaptability to poor GPS conditions and maintained accuracy through continuous correction opportunities
Solution Approach 2:
The patent implements feedback mechanisms where the system continuously monitors GPS availability and uses inertial navigation data to compensate for GPS outages. The system provides feedback by constantly updating the position estimate using available sensors and correcting drift through GPS fixes when available, creating a closed-loop navigation system that maintains accuracy while adapting to changing GPS reception conditions
3Measurement precision
If map information is used for position correction, then position can be constrained to road contours, but additional inaccuracy is introduced due to node skipping and incomplete road representation
Solution Approach 1:
The patent extracts the essential navigation functionality from the incomplete map data by using inertial navigation sensors to independently estimate position and orientation. This extraction allows the system to obtain accurate position information without relying on complete road contour representations, effectively separating the navigation function from the incomplete map infrastructure and eliminating the inaccuracy introduced by node skipping
Data Source
Figure 1A~1B
Figure 2
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AI summary
A mobile object position estimation apparatus (200) mounted in a mobile object has a first estimation means for estimating the mobile object position based on the outputs from an inertial navigation sensor devices (acceleration sensors, and yaw rate sensors or the like) (203) mounted on the mobile object, a storage means (204) for storing map information including at least node information, a second estimation means for estimating the mobile object position based on a predicted path of traveling of the mobile object predicted from the node information, and a synthesis means for determining the final estimated mobile object position by synthesizing the mobile object position estimated by the first estimation means and the mobile object position estimated by the second estimation means.