Vehicle Attitude Constraints for Extended Dead Reckoning Accuracy
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Solution Overview
Problem
Inertial navigation systems (INS) experience attitude drift during periods of GNSS degradation or unavailability, leading to poor dead reckoning performance due to uncorrected errors that accumulate and contaminate velocity and position estimates.
Innovation Solution
Applying constraints to modify roll, pitch, and yaw angles of computed vehicle attitude based on known road conditions and other information to mitigate attitude drift, using inertial measurement units (IMUs) and global navigation satellite system (GNSS) measurements for improved dead reckoning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inertial navigation system operates during GNSS degradation or unavailability, then navigation continuity is maintained, but attitude drift accumulates and degrades position and velocity estimation accuracy
Solution Approach 1:
The system applies feedback by using measured constraints (such as roll angle constraints from road geometry models or pitch angle constraints from grade information) to correct the INS attitude estimates. The constraint application module continuously compares the INS-derived attitude with the constrained attitude and applies corrections to reduce drift, thereby maintaining measurement precision while operating independently from GNSS
Solution Approach 2:
The system performs preliminary action by pre-establishing constraint models (such as road geometry models, vehicle dynamics models, or operational constraints) that can be applied to the INS data. These constraints are prepared in advance based on known road conditions, vehicle characteristics, or typical operating scenarios, and are then applied to correct attitude drift during GNSS outages
2Adaptability or versatility
If dead reckoning is used for extended periods without GNSS updates, then navigation is maintained in GNSS-denied environments, but error accumulation contaminates velocity and position estimates
Solution Approach 1:
The system introduces an intermediary constraint application module that acts as a mediator between the INS and the final navigation solution. This module applies various constraints (such as road alignment constraints, curvature constraints, or grade constraints) to the INS-derived position and velocity estimates, thereby maintaining measurement precision while enabling extended operation in GNSS-denied environments
Solution Approach 2:
The system applies parameter changes by modifying the attitude parameters (roll, pitch, yaw angles) of the INS based on constrained values derived from road geometry models, vehicle dynamics models, or operational constraints. By changing these attitude parameters to satisfy known constraints, the system prevents error accumulation in the derived position and velocity estimates
Data Source
AI summary
Techniques for vehicular navigation include determining a first attitude of a vehicle with respect to a reference frame at a first epoch, the determined first attitude including a determined first roll angle; computing an attitude of the INS at a second epoch that is subsequent to the first epoch; determining a second attitude of the vehicle at the second epoch; updating the determined second attitude of the vehicle, based on a determination that an absolute change in a yaw angle of the vehicle between the first epoch and the second epoch is less than a predetermined threshold, by setting a roll angle of the determined second attitude of the vehicle to equal the determined first roll angle; and based on the updated second attitude of the vehicle, determining an updated attitude of the INS. Applications relating to road vehicular (e.g., automobile) use are described.