Vehicle Time Synchronization Using Grandmaster Direct Path
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ensuring safety integrity in time synchronization across communication networks in automated vehicles, particularly when a non-safe ECU is involved in the synchronization chain.
Innovation Solution
A method utilizing a hierarchical master-slave architecture with a grandmaster, a first slave acting as a boundary clock, and a second slave, where the first slave generates a time tuple based on the grandmaster clock and its own clock, and sends this information to the second slave for verification, ensuring synchronization with safety integrity even if the first slave lacks safety integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a non-safe ECU (first slave) is installed in the synchronization chain to extend network coverage, then the adaptability and coverage of the time synchronization system is improved, but the reliability and safety integrity of the time synchronization is degraded
Solution Approach 1:
The grandmaster ECU acts as an intermediary that directly provides timestamp information to the second slave ECU, bypassing the non-safe first slave ECU for the critical time reference. This allows the non-safe ECU to remain in the network for coverage purposes while the safe time synchronization path is maintained through the grandmaster's direct communication with the second slave.
Solution Approach 2:
The patent creates an asymmetric synchronization architecture where the grandmaster ECU establishes different synchronization paths: one through the non-safe first slave for network coverage, and another direct path to the second slave for safety-critical time reference. This asymmetric approach allows different parts of the system to have different safety levels appropriate to their function.
2Measurement precision
If direct synchronization between grandmaster and second slave is implemented, then the reliability and measurement precision of time synchronization is improved, but the device complexity increases due to additional communication paths
Solution Approach 1:
The grandmaster ECU performs multiple functions: it acts as a time source for the first slave, as a time reference for the second slave, and as a validator for time tuples from both slaves. This multi-functionality allows the direct synchronization path to be established without requiring a separate dedicated time reference device, thereby reducing overall system complexity.
Solution Approach 2:
The patent implements a feedback mechanism where the grandmaster ECU receives time tuples from both the first and second slaves, validates their consistency, and can detect discrepancies. This feedback loop ensures the accuracy of the direct synchronization path while providing a mechanism to identify and handle issues in the indirect path through the non-safe ECU.
Data Source
AI summary
Provided is a method for time distribution in a communication network of a vehicle. The method includes: sending, from a grandmaster to a first slave, a first time stamp taken from a grandmaster clock; generating, at the first slave, a first time tuple including the first time stamp and a second time stamp taken from a first slave clock at the time of receiving the first time stamp; sending, from the first slave to a second slave a third time stamp taken from the first slave clock, a fourth time stamp calculated based on the third time stamp and the first time tuple using a predefined calculation method, and the first time tuple; calculating, at the second slave, a fifth time stamp based on the third time stamp and the first time tuple; and comparing, at the second slave, the fifth time stamp to the fourth time stamp.