CAN Bus Synchronization via Dynamic Target Time Allocation
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Solution Overview
Problem
Controller Area Network (CAN) nodes lack synchronization, leading to overwritten and absent messages due to differing clock times and message burst duration changes, which are cumbersome and error-prone to coordinate across multiple nodes or organizations.
Innovation Solution
A synchronization scheme where sync slave nodes report their message burst transmission durations to a sync master node, which calculates and communicates transmission target times, facilitating automatic adjustments and reducing human coordination errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sync message target receiving times are pre-configured into slave nodes, then synchronization is achieved, but any change in message burst duration requires cumbersome reconfiguration across all nodes
Solution Approach 1:
The patent transforms the static pre-configured sync message target receiving time into a dynamic value that is automatically calculated and updated by the master node based on actual message burst durations. The master node receives duration reports from slave nodes, recalculates target times, and communicates updated values to maintain synchronization without manual reconfiguration.
Solution Approach 2:
The system enables automatic self-adjustment where slave nodes automatically report their message burst durations to the master node, which then automatically recalculates and redistributes updated sync message target receiving times. This eliminates the need for manual human coordination and reconfiguration when changes occur.
2Reliability
If manual reconfiguration is performed when message burst duration changes, then synchronization is maintained, but human coordination errors and time consumption increase
Solution Approach 1:
The patent implements a feedback mechanism where slave nodes automatically report their message burst durations to the master node. The master node uses this feedback to dynamically recalculate sync message target receiving times and communicate updates back to slave nodes, creating a closed-loop system that automatically adapts to changes without manual intervention.
Solution Approach 2:
The system performs preliminary automatic recalculation of sync message target receiving times as soon as duration changes are detected, before synchronization errors can occur. The master node proactively updates slave nodes with new target times, preventing message overlap or gaps before they happen.
3Reliability
If sync message target receiving times are fixed, then initial synchronization is achieved, but adaptability to node additions or message changes is lost
Solution Approach 1:
The patent makes the sync message target receiving time a dynamic parameter that automatically adapts to network changes. When new nodes are added or messages are modified, the master node receives updated duration reports, recalculates target times, and redistributes them to maintain synchronization, enabling the system to adapt to any network configuration changes.
Data Source
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AI summary
A CAN network synchronization method identifies a sync master node from a plurality of nodes, and designates each of the remaining nodes as a sync slave node (304). The method further designates a message from the sync master node (302) as a sync message (408), and assigns a lowest number to the message ID of the sync message (408). The method further assigns a unique node ID to each sync slave node, and assigns a unique message ID to a transmission duration report message from a sync slave node. The method further assigns a unique message ID to a transmission target time allocation message from the sync master node. The method also performs a handshake operation between the sync slave nodes and the sync master node to exchange message burst transmission durations (Tsst), transmission target times (TTXtarget), and a common time reference point, and conducts time adjustment on each sync slave node (304).