Dead Reckoning and GNSS Map-Matching for Vehicle Positioning
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Solution Overview
Problem
Conventional car navigation systems face inaccuracies and reliability issues in environments with degraded GNSS signal reception, such as tunnels, construction zones, and lane-change maneuvers, where they struggle to maintain accurate positioning and correct for heading errors.
Innovation Solution
The integration of dead reckoning data into GNSS-aided map-matching navigation systems, which uses a state estimator and a map-match navigation module to provide feedback, incorporating inertial sensor data and recent vehicle motion history to improve positioning accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional GNSS-based navigation is used, then the system is simple and cost-effective, but positioning accuracy deteriorates in environments with degraded GNSS signal reception
Solution Approach 1:
The patent combines GNSS reception with dead reckoning navigation systems into a unified navigation apparatus. The GNSS module and dead reckoning module work together, with the GNSS providing position fixes when available and the dead reckoning module filling in during signal degradation. This merging allows the system to maintain positioning accuracy in challenging environments without requiring completely separate systems.
Solution Approach 2:
The patent introduces map-matching technology as an intermediary layer that processes and validates position data from both GNSS and dead reckoning modules. The map-matching module compares calculated positions with known map data to correct errors and maintain accuracy. This intermediary layer harmonizes the outputs of different navigation modules, ensuring consistent and accurate positioning information is provided to the user.
2Reliability
If dead reckoning is used alone, then navigation can function without GNSS signals, but heading errors accumulate over time reducing accuracy
Solution Approach 1:
The patent implements a feedback mechanism where the navigation apparatus continuously monitors GNSS signal availability and automatically adjusts between GNSS-based positioning and dead reckoning positioning. When GNSS signals are degraded or unavailable, the system switches to dead reckoning mode. When GNSS signals improve, the system uses GNSS data to correct accumulated dead reckoning errors and reset the positioning baseline, thereby maintaining long-term accuracy.
Solution Approach 2:
The patent performs preliminary actions by establishing multiple positioning baselines using map-matching technology before actual navigation occurs. The system pre-loads map data and prepares correction algorithms that can be quickly applied when signal degradation is detected. This preliminary preparation allows the dead reckoning module to maintain accuracy by referencing pre-established geographic information and correction parameters.
Data Source
AI summary
Dead reckoning combined with GNSS-aided map-matching improves accuracy and reliability of vehicle navigation. A map-match navigation module in a handheld device sends map-match feedback messages to a vehicle state estimator via a port. The module also accepts vehicle speed and inertial navigation data from sensors mounted in the vehicle.