Redundant CAN Bus Interface Fault Tolerance
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Solution Overview
Problem
In automobile-based and industrial automation systems using CAN bus communication, the shared nature of communication makes the bus a single point of failure, and existing fault-tolerant mechanisms fail to accurately interpret signals during dominant bus faults, leading to disrupted communication.
Innovation Solution
The implementation of redundant CAN buses with a bus interface that logically ANDs and ORs data signals from two buses to select the correct data signal, accommodating both recessive and dominant faults by switching between ANDed and ORed signals based on fault detection, ensuring fault-tolerant communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant CAN buses are implemented to eliminate single points of failure, then reliability is improved, but device complexity increases due to the need for fault detection and signal interpretation mechanisms
Solution Approach 1:
The bus interface circuit segments the fault detection function by separately processing signals from two independent CAN buses (CAN_H and CAN_L), evaluating each bus independently for dominant faults, and selectively combining valid signals through logic gates to produce the output data signal
Solution Approach 2:
The bus interface circuit acts as an intermediary between the redundant CAN buses and the controller, performing fault detection, signal validation, and logical combination operations to ensure only valid data reaches the controller while blocking corrupted signals
2Reliability
If existing fault-tolerant mechanisms are used to handle bus failures, then some fault protection is provided, but accurate signal interpretation during dominant bus faults fails, leading to communication disruption
Solution Approach 1:
The bus interface circuit applies preliminary anti-action by detecting dominant faults before they corrupt data transmission, using logic gates to preemptively block faulty signals from the affected bus while allowing valid signals from the other bus to pass through unchanged
Solution Approach 2:
The bus interface circuit dynamically adjusts signal routing based on real-time fault detection, switching between using CAN_H or CAN_L signals depending on which bus is healthy, and dynamically combining signals through logic gates when both buses are operational
Data Source
AI summary
A technique includes receiving a first signal from a first bus, and receiving a second signal from a second bus. The first and second buses are used for redundant communications. The technique includes interpreting the first and second signals to derive a bus data input signal for a controller based at least in part on detection of a predetermined bus fault.