GNSS Localization EKF Engine Absorbing Position Jumps
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Solution Overview
Problem
Global Navigation Satellite Systems (GNSS) face challenges in providing accurate and smooth global localization due to environmental noise, leading to undesirable 'jumps' in vehicle position, which can result in abnormal motion control and loss of smoothness in localization output.
Innovation Solution
A system and method utilizing a single Extended Kalman Filter (EKF) engine that converts between earth-centered, earth-fixed (ECEF) and east-north-up (ENU) coordinates, where the ENU reference pose is modified to absorb jumps, ensuring smooth local pose output while maintaining accurate global pose in ECEF coordinates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GNSS measurement is used for vehicle localization, then global positioning accuracy is improved, but position jumps occur due to environmental noise and multipath reflections
Solution Approach 1:
The system segments the localization problem into two independent coordinate systems: ECEF for global positioning accuracy and ENU for local smoothness. Each coordinate system handles different aspects of the localization task, allowing the system to maintain both global accuracy and local stability simultaneously.
Solution Approach 2:
The ENU coordinate system acts as an intermediary between the noisy GNSS measurements and the vehicle control system. By transforming positions to ENU and applying smoothing algorithms, the system filters out jumps while preserving the essential localization information for control purposes.
2Manufacturing precision
If multiple EKF engines are used to maintain smoothness and accuracy, then localization quality is improved, but device complexity increases
Solution Approach 1:
The system uses a single EKF engine that segments the computation into two coordinate systems rather than using multiple EKF engines. This approach achieves the same smoothing and accuracy benefits while reducing system complexity by eliminating redundant filter instances.
Solution Approach 2:
The single EKF engine performs multiple functions by computing positions in both ECEF and ENU coordinates simultaneously. This multi-functionality allows one engine to replace what would traditionally require multiple specialized engines, reducing overall system complexity.
Data Source
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AI summary
An apparatus and a method for providing a global localization output are provided. When the appartaus receives navigation signals, the apparatus processes the signals to determine, based on a fixed earth-centered, earth-fixed (ECEF) reference pose of a reference point in an ECEF coordinate, a new ECEF pose, and to convert the fixed ECEF reference pose to an east-north-up (ENU) reference pose in an ENU coordinate. When the apparatus determines that a jump occurs in the new ECEF pose based on a pose change between the new ECEF pose and a previous ECEF pose, the apparatus calculates a reference shift of the ENU reference pose based on the pose change to absorb the jump in the ENU coordinate, and updates the ENU reference pose based on the reference shift. Thus, a new ENU local pose may be obtained using the ENU reference pose.