Navigation System Narrow-Angle Branch Point Positioning
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Solution Overview
Problem
Navigation systems face challenges in accurately calculating the current position after a road branches at a narrow angle, especially when the distance between branch points is short, leading to incorrect positioning on subsequent roads.
Innovation Solution
A navigation system that performs two-dimensional map-matching by calculating the degree of certainty for each route after passing a narrow-angle branch point, using an inclination angle sensor to match road gradients and determine the current position on routes with a predetermined level of certainty, and includes a mechanism to switch between first and second current position calculation processing based on this certainty.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If map-matching in altitude direction is performed with each candidate road after passing a narrow-angle branch point, then positioning accuracy on the first branch road is improved, but positioning accuracy on subsequent roads deteriorates when branch points are close together
Solution Approach 1:
The system performs preliminary actions by calculating positions on all candidate roads in advance before the vehicle actually reaches them. When a narrow-angle branch point is detected, the system proactively calculates positions on multiple candidate roads extending forward, not just the immediately selected road. This preliminary calculation ensures that when the vehicle reaches subsequent branch points, the position information is already available, preventing positioning failures.
Solution Approach 2:
The system dynamically adjusts the candidate road calculation scope based on the distance to the next branch point. When branch points are detected to be close together, the system extends the calculation range to include roads beyond the immediate next branch point. This dynamic adaptation ensures that sufficient candidate roads are available for calculation even in complex branching scenarios, maintaining positioning reliability.
2Device complexity
If the distance between branch points is short, then road network complexity is reduced, but the ability to calculate correct positions on subsequent roads deteriorates
Solution Approach 1:
The system performs preliminary calculations for all candidate roads extending from the narrow-angle branch point, regardless of the short distance to subsequent branch points. By proactively calculating positions on multiple candidate roads in advance, the system ensures that position information is available even when branch points are closely spaced, maintaining calculation accuracy despite reduced road network complexity.
Solution Approach 2:
The system transitions from two-dimensional map-matching to three-dimensional map-matching by incorporating altitude direction calculations. This dimensional expansion allows the system to distinguish between closely spaced branch points that may appear similar in 2D space, maintaining position calculation accuracy even when branch points are close together.
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
Enables accurate calculation of the current position even when branch points are close, ensuring correct positioning on roads that branch from narrow-angle points by prioritizing routes with high matching degrees, thereby preventing miscalculations.
Implementation Method 1
an inclination angle calculation unit configured to detect an inclination angle of the automobile
Data Source
AI summary
When a narrow-angle branch point PA at which a road branches at a narrow angle gets closer, routes from the narrow-angle branch point to all points a-c reachable by traveling for a distance L after passing of the narrow-angle branch point in a current traveling direction. When the narrow-angle branch point is passed, processing to calculate, as a matching degree of each route, a matching degree between each of the gradients G1-G3 of routes R1-R3, which are indicated by map data, and history Ang of an inclination angle of a vehicle is performed until a route with a matching degree equal to or higher than a predetermined threshold is generated or until a distance L is traveled after the passing of the narrow-angle branch point. When the route with the matching degree equal to or higher than the predetermined threshold is generated, a current position is calculated on the route.