Aircraft Flight Control Computers With Dual-Tolerance Autopilot
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Solution Overview
Problem
Modern aircraft flight control systems face challenges in maintaining continuous availability of auto-pilot mode without increasing the number of computers, which is crucial for new generations of aircraft, especially autonomous ones, where the probability of auto-pilot law loss must be extremely low, and existing systems are limited by the complexity of secondary computers that only allow manual control.
Innovation Solution
A flight control system comprising main computers of two hardware types, where all main computers are configured to implement auto-pilot laws, with one type controlling actuators at a high precision tolerance level and the other at a less stringent level, allowing continuous auto-pilot availability while reducing the risk of failure due to complexity, and utilizing software partitions for independent monitoring and deactivation of functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If secondary computers are used to control rudder actuators, then reliability is improved, but device complexity increases and auto-pilot laws cannot be implemented
Solution Approach 1:
The patent creates a virtual copy of the primary computer's auto-pilot functionality within the backup computer. When primary computers fail, the backup computer can assume the auto-pilot role by executing the same control laws, effectively copying the critical functionality to maintain system capability without requiring separate dedicated auto-pilot hardware.
Solution Approach 2:
The backup computer is designed with multi-functionality, capable of performing both its traditional backup role and the auto-pilot control function. This universal design allows a single computer to serve multiple purposes: monitoring system status, taking over from failed primary computers, and implementing auto-pilot laws when needed, thereby reducing overall system complexity.
2Reliability
If the number of computers is increased to improve auto-pilot availability, then auto-pilot availability is improved, but system complexity and mass increase
Solution Approach 1:
The system implements dynamic reconfiguration where the backup computer can transition between different operational modes depending on system needs. The backup computer dynamically switches between monitoring mode, primary computer replacement mode, and auto-pilot execution mode, allowing the system to adapt to various failure scenarios without requiring static additional hardware for each potential function.
Solution Approach 2:
The patent changes the operational parameters of the backup computer based on system conditions. By modifying the backup computer's functional state rather than its physical configuration, the system achieves multiple operational capabilities from a single hardware platform, avoiding the mass and complexity penalties of adding physical computers for each function.
3Extent of automation
If primary computers are used, then auto-pilot mode is available, but reliability decreases when failures occur
Solution Approach 1:
The system prepares the backup computer in advance with the capability to execute auto-pilot laws, cushioning against potential primary computer failures. By pre-configuring the backup computer with the necessary computational resources and control algorithms, the system ensures that auto-pilot functionality remains available even when primary computers fail, without requiring last-minute system reconfiguration.
Data Source
AI summary
A flight control system for an aircraft comprises a set of actuators for controlling the aircraft and a set of flight control computers only made up of a set of duplex type main computers and of at least one backup computer. All the main computers are configured to implement auto-pilot laws for the aircraft. The set of main computers comprises two computers from a first hardware type, configured to control actuators of the set of actuators as per a first tolerance level and two computers from a second hardware type, different from the first hardware type, configured to control actuators of the set of actuators as per a second tolerance level, less stringent than the first tolerance level.