Autonomous Vehicle Time Synchronization via Backup Channels
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Solution Overview
Problem
In autonomous vehicles with multiple computing nodes, ensuring accurate and reliable time synchronization is crucial for functional safety, but existing methods lack a backup plan for synchronization failures, particularly in complex communication channel and topology configurations.
Innovation Solution
The method involves calibrating the timing of computing nodes using external time sources and transmitting timing messages through various communication channels (Ethernet, PCIe, GPIO) with protocols like NTP or PTP, and automatically switching to alternative message types or channels if synchronization fails, allowing for flexible topologies such as common master or chain configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple computing nodes are used in autonomous vehicles, then functional safety and reliability are improved, but time synchronization complexity increases and backup plans are needed for synchronization failures
Solution Approach 1:
The system segments time synchronization into multiple independent communication channels (first channel and second channel) between computing nodes. Each channel can operate independently, allowing the system to divide the synchronization task into separable paths that can be managed and monitored individually, thus reducing overall complexity while maintaining reliability.
Solution Approach 2:
The patent implements backup communication channels and alternative timing messages in advance before synchronization failures occur. When the primary synchronization channel fails, the system can immediately switch to pre-configured alternative channels or message types, providing a cushion against synchronization failures without requiring complex real-time decision-making.
2Reliability
If backup synchronization channels are implemented, then reliability is improved, but device complexity and communication overhead increase
Solution Approach 1:
The communication channels are designed to be multi-functional, serving both primary synchronization and backup functions. The same physical communication infrastructure can carry different types of timing messages (such as PTP and NTP protocols) through different logical channels, reducing the need for separate dedicated hardware paths for each synchronization method.
Solution Approach 2:
The system changes parameters of existing communication channels dynamically, such as switching between different protocol types (PTP, NTP) or adjusting message priorities, rather than requiring completely separate communication paths. This allows the same physical channel to serve multiple synchronization purposes by modifying its operational parameters.
3Adaptability or versatility
If multiple communication protocols are used for timing messages, then adaptability is improved, but difficulty of detecting and measuring synchronization status increases
Solution Approach 1:
The patent introduces an intermediary timing message structure that standardizes the interface between different communication protocols and the synchronization system. Regardless of whether PTP, NTP, or other protocols are used, they all communicate through a unified message format and processing interface, making synchronization status detection consistent across different protocol types.
4Reliability
If automatic switching between timing messages is implemented, then reliability is improved, but processing time and complexity increase
Solution Approach 1:
The system performs preliminary actions by pre-configuring alternative timing messages and backup communication channels before failures occur. When synchronization failure is detected, the system can immediately activate pre-prepared alternative messages without requiring complex real-time generation or conversion, significantly reducing switching delay.
Solution Approach 2:
Backup timing messages and alternative synchronization paths are prepared in advance as a cushion against failures. The system maintains ready-to-use alternative synchronization mechanisms that can be activated immediately when primary methods fail, avoiding time loss associated with creating backup solutions on-demand.
Data Source
AI summary
A method, apparatus, and system for timing synchronization between multiple computing nodes in an autonomous vehicle host system is disclosed. Timing of a first computing node of an autonomous vehicle host system is calibrated based on an external time source. A first timing message is transmitted from the first computing node to a second computing node of the autonomous vehicle host system via a first communication channel between the first computing node and the second computing node. Timing of the second computing node is calibrated based on the first timing message, wherein immediately subsequent to the calibration of timing of the second computing node, timing of the first computing node and of the second computing node is synchronized.