ECU Priority Buffer Segmentation for CAN-Ethernet Data Routing
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Solution Overview
Problem
Existing onboard network systems face challenges in efficiently managing data transmission between vehicles' control and information networks, particularly in prioritizing critical travel control data over non-essential data like images, due to differences in communication protocols and potential network abnormalities.
Innovation Solution
An electronic control unit (ECU) is connected to both a CAN network for travel control data and an Ethernet network for larger data types, featuring reception and transmission buffers, processors, and priority control mechanisms to ensure that travel control data is transmitted with priority, using priority transmission and readout controls to manage data flow based on network conditions and protocol differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If priority transmission control is implemented to transmit travel control data with priority, then the reliability of critical data transmission is improved, but the device complexity increases due to multiple buffers and control mechanisms
Solution Approach 1:
The transmission buffer is divided into multiple regions: a first buffer region for travel control data and a second buffer region for other data. This segmentation allows independent management and priority handling of critical data without affecting other data transmission, resolving the contradiction by organizing complexity into manageable segments while ensuring reliability through dedicated buffer space for priority data.
Solution Approach 2:
A reception buffer is introduced as an intermediary between the receiver and the transmission buffer. This intermediary component decouples the reception process from the transmission process, allowing the system to manage priority transmission control independently while maintaining reliable data flow. The reception buffer acts as a mediator that facilitates priority-based transmission without directly complicating the core transmission mechanism.
2Productivity
If multiple buffers and priority control mechanisms are added to manage data transmission, then the productivity of data processing is improved, but the device complexity increases
Solution Approach 1:
The transmission buffer is segmented into distinct regions for different data types, enabling parallel processing and efficient data management. This segmentation improves productivity by allowing the system to handle multiple data streams simultaneously while maintaining clear organizational structure, thus avoiding the complexity overhead of unsegmented buffer management.
Solution Approach 2:
Different buffer regions are allocated with different characteristics and management strategies based on local requirements. The first buffer region for travel control data receives priority treatment with specific management rules, while the second buffer region handles other data with different rules. This local quality approach optimizes processing efficiency for each data type without requiring complex global management mechanisms.
3Reliability
If travel control data is given transmission priority, then the safety of vehicle operation is improved, but the loss of time for transmitting other data increases
Solution Approach 1:
The transmission buffer is divided into priority and non-priority regions, allowing the system to transmit travel control data immediately when available while queuing other data for subsequent transmission. This segmentation ensures that safety-critical data experiences minimal delay while non-priority data transmission is deferred, accepting time loss for non-critical data to maintain vehicle operation safety.
Solution Approach 2:
The transmission control operates in periodic cycles, where each cycle checks for priority data in the first buffer region and transmits it if present, then proceeds to transmit data from the second buffer region. This periodic action pattern ensures regular opportunities for non-priority data transmission while maintaining priority handling for safety-critical data, balancing safety requirements with overall system throughput.
Data Source
AI summary
An electronic control unit connected to a bus of a first network where first-type frames are transmitted following a first communication protocol and a second network where second-type frames are transmitted following a second communication protocol in an onboard network system. The electronic control unit sequentially receives the first-type and the second-type frames from the bus and the second network respectively, and stores in first and second reception buffers, respectively. The electronic control unit sequentially generates first-type data and second-type data by referencing the contents of the first reception buffer and the second reception buffer, and stores the first-type and second-type data in first and second transmission buffers, respectively. The first-type data is traveling control data for a vehicle, and the second-type data is other data. The first-type or second-type data that is priority type data is transmitted with priority.