Vehicle Sensor Time Synchronization for Triggering
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Solution Overview
Problem
Modern systems for triggering personal protection devices face challenges due to variable latency times and data age uncertainty, leading to conservative assumptions and increased uncertainty in triggering decisions, especially in pre-crash scenarios, which can result in lost usefulness and potential false triggering.
Innovation Solution
Implementing a common time base for sensors and the control unit, synchronized using the Network Time Protocol, to accurately determine the age of data and improve the accuracy of relative speed estimation at the time of impact, thereby reducing uncertainty and minimizing false triggering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large time window is used to increase the possibility of triggering personal protection devices, then the usefulness is improved, but the risk of false triggering increases
Solution Approach 1:
The system performs preliminary actions by estimating the time of impact and relative speed in advance using surround sensors before the actual collision occurs. This allows the control unit to prepare triggering decisions proactively, enabling earlier activation of personal protection devices while maintaining accuracy through continuous updates until impact
Solution Approach 2:
The system dynamically adjusts the time window for triggering decisions based on real-time sensor data. Instead of using a fixed large time window that increases false triggering risk, the system continuously updates the estimated time of impact and relative speed, allowing the time window to adapt to changing conditions. This dynamic approach maintains high usefulness by being responsive to actual collision threats while reducing false triggering by tightening the time window when not needed
2Reliability
If conservative estimates are used to reduce false triggering, then the reliability is improved, but the uncertainty in triggering decisions increases
Solution Approach 1:
The system implements continuous feedback by constantly monitoring surround sensor data and updating the estimated time of impact and relative speed. This feedback loop allows the control unit to refine triggering decisions in real-time, reducing uncertainty by incorporating the latest sensor information while maintaining reliability through validated estimation algorithms that only trigger when confidence thresholds are met
3Device complexity
If variable latency times are not accounted for, then the device complexity is reduced, but the measurement precision of data age deteriorates
Solution Approach 1:
The patent introduces a time synchronization intermediary that coordinates the clocks of surround sensors and the control unit. This intermediary mechanism, implemented through standardized time synchronization protocols, accurately tracks variable latency times without requiring complex custom synchronization logic in each component. The intermediary provides a unified time reference that simplifies the overall system while delivering precise data age measurements
Data Source
AI summary
Triggering personal protection devices for a vehicle with the aid of a sensor having a local sensor time set with respect to a common system time.