In-Vehicle Ethernet Node Timing Calculation
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Solution Overview
Problem
In Ethernet on-board networks for motor vehicles, especially with the 10 Mbit/s standard, nodes lack information about transmission delays and bus access times, leading to increased costs in ECU design and communication planning, and limiting flexibility and precision in high-precision applications like ADAS and automated driving.
Innovation Solution
A method to determine the number of nodes in an Ethernet on-board network by calculating the cycle length and transmission windows using a transmit opportunity timer, allowing each node to predict when it can transmit again, thereby optimizing communication scheduling and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a bus Ethernet implementation is used to reduce system costs, then hardware complexity is reduced, but nodes lack information about transmission delays and bus access times
Solution Approach 1:
The patent implements a feedback mechanism where ECU nodes exchange timing information about bus access delays and transmission windows. Each node receives feedback from other nodes regarding their transmission timing, allowing nodes to calculate their own transmission delays and bus access times based on this feedback information.
Solution Approach 2:
The patent employs preliminary actions by having nodes pre-calculate and exchange timing parameters before actual data transmission occurs. Nodes determine transmission delays and bus access times in advance through beacon messages and timing exchanges, so that when data transmission is needed, the timing information is already available for scheduling.
2Reliability
If nodes wait for bus access according to round-robin method, then fair access is achieved, but transmission timing becomes unpredictable
Solution Approach 1:
The patent introduces dynamic timing adjustments where nodes can adapt their transmission schedules based on real-time network conditions. While the round-robin method provides fair access, nodes dynamically calculate and adjust their transmission windows based on measured delays, making the system both fair and predictable.
Solution Approach 2:
Nodes perform preliminary timing calculations and exchanges to determine their transmission windows in advance. By pre-calculating bus access times and transmission delays through beacon messages and timing feedback, nodes can schedule transmissions predictably while maintaining fair round-robin access.
3Ease of operation
If transmission timing information is unavailable, then bus access is simplified, but communication planning costs increase
Solution Approach 1:
ECU nodes perform self-service by autonomously calculating their own transmission delays and bus access times based on feedback from other nodes. Each node independently determines timing parameters without requiring complex centralized planning, reducing communication planning costs while maintaining operational simplicity.
Solution Approach 2:
Nodes engage in preliminary timing exchanges and calculations before data transmission occurs. Through beacon messages and timing feedback mechanisms, nodes pre-determine their transmission schedules, eliminating the need for complex real-time communication planning while keeping bus access simple.
4Adaptability or versatility
If maximum delay information is unknown, then node independence is maintained, but high-precision applications are limited
Solution Approach 1:
The patent uses feedback mechanisms where nodes exchange timing information to determine maximum delays in the network. Each node receives feedback about transmission delays from other nodes, allowing independent nodes to collectively determine the maximum delay parameter needed for high-precision applications like ADAS.
Solution Approach 2:
Nodes perform preliminary timing measurements and exchanges to determine network-wide maximum delay values before high-precision operations occur. This preliminary action allows nodes to maintain independence while acquiring the timing information necessary for precise communication in safety-critical applications.
Data Source
AI summary
A method for determining components of a sensor network within an Ethernet on-board network in a motor vehicle between at least two ECU nodes and at least one further ECU node. The at least one ECU node responds to a received payload with a payload only after a delay time, the delay time satisfying the condition tBUS≥tB+(tP+tC) n, where tB denotes a beacon time of the ECU node, tC denotes the commit time of the further ECU node, tP denotes the maximum payload with the maximum length, and n denotes the number of ECU nodes.