Vehicle Positioning Using Range-Finder Cross-Correlation
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Solution Overview
Problem
Current navigation systems are insufficient for highly and fully automated driving applications, as they lack the precision needed to determine a vehicle's position relative to a digital map at sub-meter accuracy, especially when traveling at high speeds, which can lead to catastrophic errors.
Innovation Solution
A method that involves receiving real-time scan data from the vehicle's environment, comparing it to pre-existing localisation reference scan data obtained from previous traversals, and adjusting the vehicle's position based on the longitudinal offset to ensure accurate positioning on a digital map, using range-finder sensors and cross-correlation calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional GNSS-based positioning is used, then the system is simple and cost-effective, but the positioning accuracy is insufficient for automated driving applications
Solution Approach 1:
The patent introduces an intermediary reference scan database that mediates between the vehicle's current scan and the digital map. This reference database, populated by pre-traversed routes with known positions, serves as a mediator to align current scan data with map data, enabling sub-meter positioning accuracy without requiring complex real-time mapping systems.
Solution Approach 2:
The system performs preliminary action by pre-traversing routes and creating reference scan data before the actual positioning operation. This reference data is stored in association with digital map segments, allowing the vehicle to use this pre-prepared information during actual navigation to achieve high positioning accuracy without complex real-time processing.
2Measurement precision
If real-time scan data comparison is performed continuously, then positioning accuracy is maintained at sub-meter level, but computational resources and processing time increase
Solution Approach 1:
The system performs preliminary computation by pre-calculating and storing reference scan data for various routes in association with digital map segments. This pre-processing eliminates the need for complex real-time computations, allowing the vehicle to simply compare current scans against pre-computed references during actual navigation, thus reducing processing time while maintaining accuracy.
Solution Approach 2:
The patent uses copying by creating a reference copy of scan data from pre-traversed routes and storing it in association with digital map segments. During actual positioning, the system compares the current scan against this copied reference data, avoiding the need for complex real-time registration and significantly reducing computational requirements while maintaining sub-meter positioning accuracy.
3Measurement precision
If reference scan data is stored for all digital map segments, then positioning can be continuously determined with high accuracy, but data storage requirements increase significantly
Solution Approach 1:
The patent applies local quality by storing reference scan data selectively only for digital map segments that correspond to actually traversed routes, rather than attempting to store reference data for the entire digital map. This selective approach reduces the overall data volume while maintaining the ability to provide continuous high-accuracy positioning for the routes the vehicle actually travels through.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for continuous, high-accuracy determination of a vehicle's position relative to a digital map, reducing errors and ensuring safe operation in automated driving scenarios by using real-time and reference data comparisons.
Implementation Method 1
The at least one range-finder sensor is configured as a time-of-flight laser range-finder so as to measure a distance to each position of incidence of the laser beam on the object surface
Implementation Method 2
The laser scanner 6 is configured to scan a laser beam in 3D across the environment and to create a point cloud representative of the environment
Implementation Method 3
a relative positioning device 22 including an inertial measurement unit (IMU) and a distance measurement instrument (DMI)
Data Source
AI summary
A method of determining a longitudinal position of a vehicle (100) relative to a digital map is disclosed in which real time scan data (200, 202) is determined by scanning a lateral environment around the vehicle using at least one range-finder sensor, said real time scan data comprising one or more depth maps, each depth map representing the measured lateral distance to surfaces in the lateral environment for a plurality of longitudinal positions and elevations. Localization reference data associated with the digital map for a deemed current longitudinal position of the vehicle (100) in relation to the digital map is retrieved, and compared to the real time scan data (200, 202) by calculating a cross-correlation to determine a longitudinal offset. The deemed current longitudinal position is adjusted based on said longitudinal offset to determine the longitudinal position of the vehicle (100) relative to the digital map.