On-board Road Grade Calculation Using Adaptive Altitude Points
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Solution Overview
Problem
Existing road grade calculation methods in vehicles are prone to errors due to altitude measurement inaccuracies, especially when using mesh altitude data, leading to significant discrepancies in calculated road grades.
Innovation Solution
An on-board apparatus that calculates road grades by utilizing altitude information from specific geographical points ahead and behind the target point, with adjustable separating distances based on location, road type, and intersection types, to minimize measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mesh altitude data is used to calculate road grade, then the calculation can be performed using pre-stored data, but measurement precision deteriorates because the altitude data does not necessarily match the actual altitude at the virtual point
Solution Approach 1:
The patent applies local quality by selecting altitude data from specific geographical points (ahead and behind the target point) rather than using generic mesh data. The separating distance is adjusted based on local conditions such as area type, road type, and intersection types to optimize accuracy for each specific location context.
Solution Approach 2:
The patent changes the parameter of separating distance dynamically based on multiple factors including area type, road type, and intersection types. This allows the system to adapt the altitude data selection strategy to local conditions, improving measurement precision while maintaining calculation efficiency.
2Measurement precision
If altitude data in fine increments is measured to calculate road grade at a specific geographical point, then measurement precision improves, but reliability deteriorates because the calculation is greatly affected by any error in altitude measurement
Solution Approach 1:
The patent uses an intermediary approach by introducing a separating distance parameter that mediates between the target geographical point and the altitude measurement points. By selecting points at an optimized separating distance and using multiple points (ahead and behind), the system reduces the impact of individual measurement errors on the final road grade calculation.
Solution Approach 2:
The patent applies beforehand cushioning by pre-determining optimal separating distances based on area type, road type, and intersection types before performing the calculation. This pre-optimization cushions against potential measurement errors by establishing a robust calculation framework that anticipates and compensates for common sources of error.
3Device complexity
If the separating distance is fixed for all locations, then device complexity is reduced, but measurement precision deteriorates because it cannot adapt to different location conditions
Solution Approach 1:
The patent applies dynamics by making the separating distance adjustable rather than fixed. The system dynamically determines the separating distance based on real-time detection of area type, road type, and intersection types, allowing optimal accuracy for each specific location condition while maintaining a relatively simple calculation structure.
Data Source
AI summary
An on-board apparatus includes: a map data storage unit in which map data that include altitude information are stored; a subject vehicle position detection unit that detects a subject vehicle position; and a calculation target geographical point setting unit that sets a calculation target geographical point based upon the subject vehicle position, wherein a road grade at the calculation target geographical point is calculated based upon altitudes of a plurality of geographical points that include at least a geographical point present ahead of the calculation target geographical point and a geographical point present behind the calculation target geographical point.