ECU Temperature Detection via Ethernet Time Synchronization
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Solution Overview
Problem
The challenge of heat dissipation and temperature monitoring in high-performance server ECUs in vehicles, which are critical for autonomous driving, is exacerbated by the reliance on temperature sensors that can fail, leading to immediate ECU failure and the need for redundant diagnostic options.
Innovation Solution
A method using the Ethernet-based IEEE 802.1AS time synchronization protocol to monitor temperature changes in ECUs without additional sensors by analyzing the clock rate of quartz crystals, which are influenced by ambient temperature, allowing early detection of errors and potential attacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature sensors are used to monitor ECU temperature, then temperature monitoring capability is provided, but the system becomes vulnerable to sensor failure leading to immediate ECU failure
Solution Approach 1:
The patent uses time synchronization message exchange as an intermediary mechanism to indirectly monitor ECU temperature. Instead of directly reading temperature sensors, the system analyzes the clock rate deviations in time synchronization messages, which are affected by temperature-induced quartz crystal frequency changes. This intermediary approach provides redundant monitoring without direct sensor dependency.
Solution Approach 2:
The patent replaces the mechanical/electrical temperature sensor measurement system with a signal processing approach based on time synchronization protocol analysis. By substituting direct physical measurement with indirect temporal analysis of communication messages, the system achieves temperature monitoring without vulnerable hardware sensors.
2Reliability
If additional temperature sensors or monitoring systems are added to ECUs, then redundant diagnostic capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the time synchronization protocol serve multiple functions: its primary function for clock synchronization and an additional function for temperature monitoring. By analyzing clock rate deviations in the same time synchronization messages used for timing, the system achieves dual-purpose utilization without adding dedicated temperature monitoring infrastructure.
Solution Approach 2:
The ECU uses its own time synchronization communication infrastructure to monitor its temperature. The existing clock and communication systems serve themselves by providing temperature information through their inherent operational characteristics, eliminating the need for separate monitoring systems.
3Reliability
If time synchronization protocol messages are used for temperature monitoring, then redundant diagnostic capability is achieved without additional hardware, but message processing complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the ECU analyzes the arrival times and clock rates in time synchronization messages to detect temperature-induced frequency deviations. This feedback loop continuously monitors the health of the ECU by comparing expected versus actual timing behavior, enabling proactive diagnostic response.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables cost-effective, redundant temperature monitoring and secure time synchronization, reducing the risk of ECU failure and enhancing diagnostic capabilities without additional hardware or bus load, ensuring reliable operation and data security in vehicle networks.
Implementation Method 1
the clock rate of quartz crystals, which are influenced by ambient temperature
Data Source
Figure 1a~1b
Figure 2
Figure 3
AI summary
The invention relates to a method for determining the control unit temperature in a motor vehicle by means of Ethernet, comprising the steps of: determining a transit time of a first signal on a first connection path between a first server ECU of the Ethernet vehicle electrical system and a second server ECU of the Ethernet vehicle electrical system; determining a maximum speed of the first connection path on the basis of the transit time; identifying at least a first server ECU of the Ethernet vehicle electrical system; synchronising at least a first server ECU of the Ethernet vehicle electrical system; determining the synchronisation interval; determining a timestamp of the first server ECU; reading a timestamp or querying the clock time of the first server ECU; comparing the timestamp with a reference clock of the Ethernet vehicle electrical system; carrying out a transit time measurement; determining the speed of the associated clock generator; determining the time difference of the synchronisation interval; determining the last synchronisation.