Flight Control Bus Architecture for Common-Mode Failure Backup
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Solution Overview
Problem
Conventional flight control systems face high development and cost challenges due to complex hardware and software requirements for redundant data networks, and are vulnerable to common-mode errors that can lead to aircraft control surface failure.
Innovation Solution
A flight control system with multiple actuators and remote electronics units, utilizing a primary data bus system with two redundant data buses of the same technology and a backup data bus of different technology to ensure continued functionality in case of primary system failure, reducing development effort and cost while enhancing system availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dissimilar redundant data networks are implemented to eliminate common-mode errors, then system reliability is improved, but device complexity and development cost increase significantly
Solution Approach 1:
The system segments the data network into two functional layers: a primary data network for normal operation and a backup data network for failure scenarios. This segmentation allows each layer to be optimized independently, with the primary network using cost-effective similar redundancy and the backup network providing dissimilar protection against common-mode errors.
Solution Approach 2:
The backup data network is configured in advance with dissimilar technology to cushion against potential common-mode errors in the primary network. This prior cushioning ensures that when primary network failures occur, the system already has a pre-prepared, technologically different backup path ready to prevent catastrophic failure.
2Reliability
If dissimilar redundant data networks are implemented to eliminate common-mode errors, then system reliability is improved, but development cost increases significantly
Solution Approach 1:
The system segments the data network into two functional layers: a primary data network for normal operation and a backup data network for failure scenarios. This segmentation allows each layer to be optimized independently, with the primary network using cost-effective similar redundancy and the backup network providing dissimilar protection against common-mode errors.
Solution Approach 2:
The backup data network uses a different, potentially simpler or more specialized technology that would be cost-prohibitive to implement throughout the entire system. By using this dissimilar technology only in the backup capacity, the system achieves common-mode error protection at a fraction of the cost of implementing it universally.
3Reliability
If integrated dissimilar data network types are implemented, then common-mode errors are eliminated, but integration difficulty increases
Solution Approach 1:
The actuator control electronics serve as an intermediary between the primary and backup data networks. This intermediary component manages the complexity of integrating different data network technologies by providing standardized interfaces and coordination logic, isolating the integration complexity from the rest of the flight control system.
Solution Approach 2:
The system segments the data network into two functional layers: a primary data network for normal operation and a backup data network for failure scenarios. This segmentation allows each layer to be optimized independently, with the primary network using cost-effective similar redundancy and the backup network providing dissimilar protection against common-mode errors.
Data Source
Figure 1
AI summary
The invention relates to a flight control system (1) for actuating a control surface (2) of an aircraft, comprising: a plurality of actuators (3) for the redundant actuation of a control surface (2) of the aircraft; actuator control electronics (4) for receiving, calculating and forwarding control signals for the control surface (2) to be actuated by means of the plurality of actuators (3); a plurality of remote electronic units (5), each provided for controlling and monitoring a corresponding actuator (3); and a first data bus system (10) for transferring data between the actuator control electronics (4) and the plurality of remote electronic units (5), the first data bus system (10) comprising a first data bus (11) for transferring data between the actuator control electronics (4) and a first of the plurality of remote electronic units (5) and comprising a second data bus (12) for transferring data between the actuator control electronics (4) and a second of the plurality of the remote electronic units (5), the first data bus (11) and the second data bus (12) being based on the same bus technology, the first data bus system (10) also comprising a backup data bus (13) for transferring data between the actuator control electronics (4) and the first remote electronic unit (5), and the backup data bus (13) being different in the bus technology thereof from the first data bus (11) and the second data bus (12). Because of the high system availability and device availability which are provided by means of the duplex architecture of the main bus, the backup data bus is limited only to data exchange between the computers which exclusively are required as a minimum configuration for safe flight operation. System components and associated electronic devices not required for the minimum configuration (minimum control) are also not integrated into the backup network. This leads to a reduction in the complexity, the cabling expense, the cable weight, and the installation costs.