Angle-of-Attack Fault Detection for Pitot Tube Blockage
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Solution Overview
Problem
Current flight control systems face challenges in accurately detecting faults in pitot tubes, particularly when a majority are blocked, leading to inaccurate airspeed calculations and potential false alarms, which can cause unnecessary mode switches in aircraft operations.
Innovation Solution
A flight control system that compares the measured angle of attack with an estimated angle of attack based on total pressure from pitot tubes, switching to the estimated value when the error exceeds a threshold, allowing for continued normal operation even if pitot tubes are blocked, and using an extended Kalman filter to determine dynamic pressure and angle of attack independently of pitot tube measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pitot tubes are used to measure airspeed, then airspeed data can be obtained, but false alarms occur when pitot tubes are blocked leading to unnecessary mode switches
Solution Approach 1:
The system introduces an intermediary fault detection mechanism that compares measured angle of attack with estimated angle of attack derived from independent total pressure and static pressure sensors. This intermediary comparison system identifies pitot tube blockages before they cause false airspeed alarms, allowing the system to switch to alternative calculation methods and prevent harmful false alarms while maintaining reliable airspeed measurement.
2Reliability
If multiple pitot tubes are blocked, then accurate airspeed calculation becomes difficult, but the system needs to maintain normal operation
Solution Approach 1:
The system changes the calculation parameters for airspeed by switching from relying on differential pressure from potentially blocked pitot tubes to using total pressure and static pressure from independent sources combined with angle of attack data. When blockage is detected through the angle of attack comparison method, the system transforms the calculation approach to maintain accurate airspeed determination and continuous normal operation despite pitot tube failures.
3Measurement precision
If the system switches to estimated angle of attack when error exceeds threshold, then fault detection accuracy improves, but system complexity increases
Solution Approach 1:
The system achieves multi-functionality by using the same total pressure and static pressure sensors for both normal airspeed calculation and fault detection through estimated angle of attack computation. The existing sensors serve dual purposes: providing data for routine operations and enabling independent verification when faults occur. This universal use of sensors improves fault detection precision without requiring additional dedicated hardware, thereby limiting the increase in system complexity.
Data Source
AI summary
A flight control system for an aircraft is disclosed and includes one or more processors and a memory coupled to the processors. The memory stores data comprising a database and program code that, when executed by the one or more processors, causes the flight control system to receive as input a measured angle of attack that is based on a raw angle of attack and an estimated angle of attack based on a total pressure. The flight control system is further caused to compare the measured angle of attack with the estimated angle of attack to determine an error. In response to determining that the error between the measured angle of attack and the estimated angle of attack exceeds a threshold value, the flight control system determines the presence of a fault with an angle of attack value.