Autonomous Vehicle GPS Time Verification Using Sensor Position Checks
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Solution Overview
Problem
Autonomous vehicles face challenges in accurately verifying GPS time when GPS signals are unavailable, leading to clock drift, which affects synchronization and precision in radar and laser systems.
Innovation Solution
The autonomous vehicle compares a sensor-based position, determined using onboard sensors and a digital map, to a GPS computed position to verify the accuracy of GPS time before updating the internal clock, ensuring synchronization and precision in radar and laser systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS time is used to update the clock, then synchronization accuracy is improved, but reliability deteriorates when GPS signals are unavailable
Solution Approach 1:
The system performs preliminary verification by comparing sensor-based position with GPS computed position before accepting GPS time updates. This preliminary check ensures that GPS signals are authentic and accurate before the clock is updated, preventing drift from spoofed or erroneous GPS signals.
Solution Approach 2:
The system implements a feedback mechanism where the sensor-based position (independent of GPS) provides continuous verification of GPS computed position. When the positions diverge beyond a threshold, the system rejects the GPS time update, creating a closed-loop verification system that maintains reliability.
2Measurement precision
If sensor-based position verification is performed, then GPS time accuracy is verified, but device complexity increases
Solution Approach 1:
The sensor system serves multiple functions: it provides primary navigation when GPS is unavailable, verifies GPS position accuracy when GPS is available, and enables threshold-based acceptance/rejection of GPS time updates. This multi-functionality reduces the need for separate verification hardware.
Solution Approach 2:
The sensor-based position acts as an intermediary verification layer between the GPS system and the clock. Instead of directly trusting GPS time, the system uses sensor position as a mediator to indirectly verify GPS signal integrity through position comparison.
Data Source
AI summary
A method of updating a clock associated with an autonomous vehicle includes determining, at a processor, a sensor-based position of the autonomous vehicle, which is determined based on data from one or more sensors and based on a digital map. The method also includes determining, at the processor, a global positioning system (GPS) computed position of the autonomous vehicle and a GPS time. The GPS computed position and the GPS time are determined based on a plurality of GPS signals received from GPS satellites. The method further includes comparing the sensor-based position to the GPS computed position to determine whether the sensor-based position is within a threshold distance from the GPS computed position. The method also includes updating the clock associated with the autonomous vehicle based on the GPS time in response to a determination that the sensor-based position is within the threshold distance from the GPS computed position.