Aircraft Flight Control Bus Redundancy for Fault Tolerance
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Solution Overview
Problem
Conventional flight control systems for aircraft lack sufficient resilience against technical failures, particularly due to weight, cost, and limitations in communication bus technologies, which can impact the reliability and efficiency of flight operations.
Innovation Solution
A redundant flight control system with a dual CAN bus architecture using two independent bus sub-systems and protocols, along with triple dissimilar flight control computers, to enhance resilience and fault tolerance, allowing for efficient communication and control of aircraft devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional triplex architecture with three independent flight control computers and three independent networks is used, then fault tolerance and reliability are improved, but weight increases due to higher number of busses, connectors and necessary physical path segregation
Solution Approach 1:
The system divides the flight control architecture into multiple independent flight control computers (at least three) and segments communication paths into multiple independent communication busses. Each flight control computer can operate independently, and each bus provides separate communication pathways, ensuring that a single failure does not compromise the entire system. This segmentation maintains high reliability while optimizing weight by using shared resources where safe.
Solution Approach 2:
The system changes the parameter of communication protocol redundancy from physical path segregation to protocol-level redundancy. Instead of requiring completely separate physical networks, the system uses multiple independent communication busses that can carry different communication protocols (e.g., ARINC 429, AFDX, MIL-STD-1553), allowing flexible configuration that reduces weight while maintaining fault tolerance through protocol diversity and independent bus operation.
2Reliability
If conventional communication bus technologies (ARINC-429, MIL-STD-1553, AFDX) are used, then communication reliability is improved, but device complexity and cost increase due to need for critical bus controllers or routers and proprietary single supplier dependencies
Solution Approach 1:
The system implements communication bus nodes that are universally compatible with multiple communication protocols (ARINC 429, AFDX, MIL-STD-1553, CAN bus). Each bus node can function across different protocol domains, eliminating the need for protocol-specific controllers or routers. This multi-functionality reduces device complexity and removes dependencies on proprietary single suppliers while maintaining the reliability characteristics of each individual protocol through selective usage.
3Reliability
If conventional communication bus technologies are used, then established communication standards are met, but weight increases due to many wires (e.g., RS-422 full duplex) and physical path requirements
Solution Approach 1:
The system merges multiple communication protocols and their associated wire requirements into a unified bus architecture. Instead of implementing separate physical pathways for ARINC 429, AFDX, MIL-STD-1553, and CAN bus, the system uses a consolidated set of independent communication busses that can dynamically support different protocols. This merging significantly reduces the total wire count and associated weight while maintaining compliance with established communication standards through virtualization and protocol adaptation layers.
4Reliability
If traditional triplex architecture is used, then fault tolerance is improved, but cost increases due to higher number of busses, connectors and proprietary single supplier dependencies
Solution Approach 1:
The system uses software-based copying and virtualization to create multiple logical communication pathways on shared physical infrastructure. Instead of requiring three completely separate physical networks as in traditional triplex architecture, the system implements virtual copies of communication protocols over shared busses, maintaining fault tolerance through logical redundancy while reducing the physical components (busses, connectors) that drive cost and manufacturing complexity.
Data Source
Figure 1
Figure 2~3
Figure 4a)~5d)
AI summary
A flight control system (10) for an aircraft comprises a flight control computer system (12), which is connected via an electronic or optoelectronic bus system (22) with a plurality of bus nodes (14, 16, 18, 20), which each are configured to at least one of controlling an associated aircraft device based on command messages received from the flight control computer system via the bus system and sending information messages to the flight control computer system via the bus system. According to one aspect of the disclosure, the electronic or optoelectronic bus system is a redundant electronic or optoelectronic bus system (22) comprising plural independent bus sub-systems (22a, 22b), wherein each bus node is configured to communicate with the flight control computer system (12) via two different bus sub-systems (22a, 22b) of the plural independent bus sub-systems, wherein each bus node further is configured to communicate with the flight control computer system on basis of an associated predetermined bus communication protocol via a first bus sub-system (22a) of the respective two different bus sub-systems and on basis of an associated predetermined bus communication protocol via a second bus sub-system (22b) of the respective two different bus sub-systems.