Aircraft Brake Control Unit Disable via Dual Enable Signals
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Solution Overview
Problem
Aircraft brake systems face challenges in ensuring reliable braking operations when the Brake Control Unit (BCU) fails, as existing systems lack effective redundancy to enable other controllers or systems to take control and maintain safe braking.
Innovation Solution
The proposed brake system includes a Vehicle Management System (VMS) communicating with a controller, a shutoff valve, and a servo valve, using dual enable signals to trigger a disable interrupt service routine that prevents the controller from communicating with the valve, allowing the VMS to take full control and reboot the system in case of BCU failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the BCU is given full control of the brake system, then normal braking operations are simplified and efficient, but the system becomes vulnerable to failures when the BCU malfunctions
Solution Approach 1:
The system pre-configures two independent enable signals (first enable signal via first wire, second enable signal via second wire) that can independently disable the BCU. This preliminary arrangement ensures that if the BCU fails, the VMS can immediately take control without needing to diagnose the failure first, thus maintaining reliability while preserving normal operational efficiency.
Solution Approach 2:
The VMS acts as an intermediary system that can intervene in the BCU-valve communication path. By introducing the VMS as a mediator with the authority to disable the BCU through dual enable signals, the system allows normal BCU operation while providing a safety mechanism for failure scenarios.
2Reliability
If the VMS is given the ability to take control from the BCU, then system reliability under failure conditions improves, but the control architecture becomes more complex
Solution Approach 1:
The control architecture is segmented into distinct functional components: the BCU for normal operation, the VMS for supervisory control, and two separate communication paths (first wire and second wire) for enable signals. This segmentation allows the system to maintain simple normal operations while embedding complexity only in the failure recovery path.
Solution Approach 2:
The complexity of dual-wire enable signals and VMS intervention capability is localized only to the control arbitration mechanism, while the actual braking operation remains simple and unchanged. The BCU continues to control valves normally during healthy operation, and the complex VMS takeover logic is only activated locally when failure conditions are detected.
3Reliability
If dual enable signals are used to disable the BCU, then control authority can be reliably transferred to the VMS, but the wiring and control logic become more complex
Solution Approach 1:
The disable functionality is extracted as a separate, dedicated mechanism independent of normal braking control. The two enable signals are taken out as distinct communication channels (first wire and second wire) that operate separately from the main control path, allowing reliable control transfer without complicating the primary braking operation logic.
Data Source
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AI summary
A brake system may comprise a controller (280), a vehicle management system (VMS) (270) in communication with the controller, a valve (242) in communication with the controller, and a tangible, non-transitory memory configured to communicate with the controller, the tangible, non-transitory memory having instructions stored thereon that, in response to execution by the controller, cause the controller to perform operations comprising determining, by the controller, that a first enable signal is received by the controller from the VMS, determining, by the controller, that a second enable signal is received by the controller from the VMS, and disabling, by the controller, the controller from control of the valve in response to the first enable signal and the second enable signal.