Vehicle Longitudinal Position Estimation via Pitch Angle
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Solution Overview
Problem
Vehicle localization systems face challenges in accurately estimating the longitudinal position of a vehicle when landmarks are not detectable due to environmental conditions like rain or backlight, and when no landmarks are present around the vehicle, leading to reduced accuracy in position estimation.
Innovation Solution
A vehicle localization system that utilizes an electronic control unit to estimate the longitudinal position by comparing the rate of change in pitch angle of the vehicle with the rate of change in height on the map, using a map database with height and grade information, and determines if the vehicle is near a characteristic height change section to improve estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vehicle localization uses landmarks captured by camera, then lateral position can be estimated, but longitudinal position accuracy deteriorates when landmarks are not detectable due to rain, backlight, or absence
Solution Approach 1:
The patent introduces map height information as an intermediary element to bridge the gap between vehicle pitch angle measurements and longitudinal position estimation. By comparing the rate of change in pitch angle with the rate of change in map height, the system can estimate longitudinal position without relying on landmarks, thus resolving the contradiction between measurement precision and reliability
Solution Approach 2:
The patent changes the parameter used for longitudinal position estimation from landmark-based visual features to physics-based pitch angle measurements combined with map height data. This parameter change allows the system to maintain estimation accuracy under conditions where traditional landmark-based methods fail
2Measurement precision
If the system continuously estimates longitudinal position using pitch angle and map height comparison, then accuracy improves, but computational load increases unnecessarily on flat roads
Solution Approach 1:
The patent performs preliminary analysis by checking whether the vehicle is located near a characteristic height change section before executing the full estimation algorithm. This preliminary action allows the system to avoid unnecessary computations on flat roads while maintaining high accuracy when needed, effectively resolving the contradiction between measurement precision and device complexity
Data Source
AI summary
A vehicle localization system includes: an electronic control unit estimating a vehicle position including a longitudinal position on a map in an extension direction of a road on which the vehicle is traveling and a lateral position on the map in a lateral direction of the road; and a storage device storing a map database including map information. The electronic control unit obtains a vehicle speed and a pitch angle of the vehicle, perceives a measured position of the vehicle on the map based on a measurement result of a positioning device mounted on the vehicle and the vehicle speed, and estimates the longitudinal position from comparison between a rate of change in pitch angle of the vehicle along the road and a rate of change in height on the map along the road, based on the measured position, the map information, and the pitch angle.