Cross-Network Time Sync via Gateway ECU for FlexRay and CAN
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Solution Overview
Problem
Existing vehicle bus protocols like CAN and FlexRay have limitations in synchronization and data delivery, particularly in ensuring timely and high-speed data exchange across multiple networks, which is crucial for advanced control applications in modern vehicles.
Innovation Solution
A system and method for cross-network synchronization that periodically samples time from a FlexRay network, transmits this notion of time to nodes on a CAN network, and updates their local clocks, enabling coordinated activity across both FlexRay and CAN networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If CAN-bus protocol is used for vehicle communication, then ease of operation and robustness are improved, but synchronization precision and data delivery speed deteriorate
Solution Approach 1:
The patent introduces a gateway ECU as an intermediary between CAN-bus and FlexRay networks. This gateway samples the global time from FlexRay and transmits it to CAN nodes, enabling CAN devices to achieve synchronized timing without requiring direct FlexRay connectivity, thus resolving the contradiction between ease of operation and synchronization precision
Solution Approach 2:
The patent segments the vehicle network into different functional zones: FlexRay for high-speed synchronized communication and CAN-bus for robust event-driven communication. By dividing the network architecture and assigning appropriate protocols to different segments, the system achieves both high synchronization precision where needed and maintains ease of operation in other areas
2Measurement precision
If FlexRay protocol is used for vehicle communication, then synchronization precision and data delivery speed are improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic time synchronization where the gateway ECU periodically samples the global time from FlexRay and dynamically updates CAN nodes. This dynamic approach allows CAN nodes to achieve FlexRay-level synchronization precision without permanently complex device architecture, as they only need basic clock sampling and update capabilities
Solution Approach 2:
The gateway ECU serves multiple functions: it acts as a time server for CAN nodes, a protocol converter between FlexRay and CAN, and a coordination point for cross-network communication. By consolidating these functions in a single device, the patent reduces overall system complexity while maintaining high synchronization precision
3Adaptability or versatility
If event-triggered protocol is used for vehicle communication, then adaptability is improved, but reliability of timely data delivery deteriorates
Solution Approach 1:
The patent implements periodic time synchronization where the gateway ECU samples the global time from FlexRay at regular intervals and transmits these time stamps to CAN nodes. This periodic action ensures that CAN nodes receive timely synchronization updates, guaranteeing reliable data delivery timing while preserving the event-triggered adaptability of CAN communication
Data Source
AI summary
A system and method for implementing cross-network synchronization of nodes on a vehicle bus includes periodically sampling a notion of time from a first network, transmitting a message from the first network to a node on a second network, wherein the message includes the notion of time, and updating a local clock on the second network node based on the notion of time in the message.