Latency Compensation in Inertial Navigation Systems
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Solution Overview
Problem
Inertial navigation systems in autonomous vehicles face latency issues due to the intermittent and delayed reception of Global Navigation Satellite System (GNSS) data, leading to outdated location estimates as the vehicle travels during the time gap between data reception and processing.
Innovation Solution
A method and system that adjust GNSS data by identifying the previously estimated location with a timestamp closest to the new GNSS data and the most recent timestamp, calculating the difference, and compensating the GNSS data to account for the latency, allowing for more accurate current location estimation using a processing device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GNSS data is received and processed with latency compensation, then location estimation accuracy is improved, but data processing complexity increases
Solution Approach 1:
The system performs preliminary actions by storing multiple previously estimated locations with timestamps before processing new GNSS data. This allows the system to identify the closest and most recent locations in advance, preparing the necessary reference data before the actual latency compensation calculation is needed.
Solution Approach 2:
The patent introduces previously estimated locations as intermediary elements between the raw GNSS data and the final location estimation. These intermediary locations serve as reference points that facilitate the latency compensation process by providing a basis for calculating time differences and adjusting the GNSS measurements accordingly.
2Loss of time
If GNSS data is used for location estimation after propagation time, then location data becomes outdated, but using it immediately would require real-time processing capability
Solution Approach 1:
The system implements feedback by continuously updating previously estimated locations with new IMU-based estimates between GNSS updates. This feedback mechanism allows the system to track vehicle movement during the GNSS data propagation delay, providing increasingly accurate reference locations that compensate for the time lag in GNSS processing.
Solution Approach 2:
The system performs preliminary location estimation using IMU data before the actual GNSS data is processed. By calculating intermediate locations in advance based on vehicle motion models, the system prepares reference data that accounts for the time difference between GNSS reception and processing, effectively compensating for propagation delays.
Data Source
AI summary
In one embodiment, a method for calculating a location of an autonomous driving vehicle includes receiving new global navigation satellite system (GNSS) data. The method further includes identifying a first previously estimated location from a plurality of previously estimated locations with a timestamp that is closest to the timestamp of the new GNSS data and identifying a second previously estimated location from the plurality of previously estimated locations with a most recent timestamp. The method further includes calculating a difference between the first previously estimated location and the second previously estimated location, adjusting the new GNSS data based on the difference; and calculating a current estimated location of the ADV based on the adjusted GNSS data.