On-board Network Abnormality Detection During Power-Saving Transitions
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Solution Overview
Problem
Conventional on-board network systems struggle to accurately detect operation abnormalities in electronic control units (ECUs) during power-saving states, as they cannot differentiate between normal operation and malfunctioning nodes based solely on the absence of network management messages.
Innovation Solution
The system introduces a master node that monitors and detects abnormalities by tracking the transmission of sleep-entered messages from nodes transitioning to power-saving states, allowing for efficient detection of operational issues during both normal and bus-sleep operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If nodes transition to power-saving state by stopping NM message transmission, then power consumption is reduced, but abnormality detection capability deteriorates
Solution Approach 1:
The system performs preliminary actions by having nodes transmit a sleep-entered message before transitioning to the power-saving state. This allows the master node to record the node's normal operation state in advance, enabling subsequent abnormality detection without requiring continuous NM message transmission during sleep mode.
Solution Approach 2:
The master node implements feedback by monitoring whether sleep-entered messages are received from nodes during power-saving states. By comparing the recorded normal operation state with the actual message reception status, the system can detect abnormalities and provide feedback about node health status.
2Use of energy by moving object
If NM message transmission is stopped during power-saving state, then energy efficiency is improved, but measurement precision of node operation status deteriorates
Solution Approach 1:
The system records the normal operation state of each node in advance before it transitions to power-saving mode. This preliminary recording of expected message transmission patterns enables accurate operation status measurement without requiring continuous messaging during the low-power state.
Solution Approach 2:
Nodes autonomously transmit a sleep-entered message to indicate their transition to power-saving state, and the master node uses this self-reported information combined with the recorded normal state to determine operation status, eliminating the need for continuous external monitoring.
3Reliability
If continuous NM message transmission is maintained for abnormality detection, then detection accuracy is improved, but power consumption increases
Solution Approach 1:
The system performs the detection function in advance by recording the normal operation state before nodes enter power-saving mode. This allows the master node to compare expected versus actual message reception patterns without requiring continuous transmission, achieving detection accuracy with reduced energy consumption.
Solution Approach 2:
Instead of continuous NM message transmission, the system uses periodic sleep-entered message transmission at specific transition points (when entering power-saving state). This periodic action maintains detection capability while significantly reducing overall power consumption compared to continuous messaging.
Data Source
AI summary
An on-board network system is presented. The on-board network system sends a sleep-entered message to a communication bus. The sleep-entered message is sent under a condition that a sleep condition is satisfied on a basis that a network management (NM) message is ceased during state transition process in which node's state transfers from a normal state to a power-saving state. A monitoring ECU corresponding to a master performs an abnormality detection process. In the abnormality detection process, the monitoring ECU detects an abnormality state of the state transition process based on whether or not the sleep-entered message is sent from any one of nodes, thereby it is possible to detect the abnormality state not only during each node is a normal state but also during a bus-sleep state.