Blended Angle of Attack Estimation via Sensor Fusion
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Solution Overview
Problem
Current angle of attack (AOA) measurement systems in aircraft rely on expensive and prone-to-damage sensors like vanes or 5-hole/3-hole probes, necessitating the development of alternative methods for determining AOA without direct measurement using these sensors.
Innovation Solution
A system utilizing an airspeed sensor, inertial reference system (IRS) or attitude and heading reference system (AHRS), and a controller to compute kinematic and aerodynamic AOA signals, applying low-pass and band-pass filters respectively, and summing these signals to determine the blended AOA.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external sensors (vanes or 5-hole/3-hole probes) are used to measure AOA, then measurement precision is improved, but device complexity and maintenance cost increase
Solution Approach 1:
The patent creates a computational model that copies the function of external AOA sensors by using existing onboard sensors (accelerometers, airspeed sensors) to calculate AOA. Instead of physically measuring AOA with external probes, the system copies the measurement capability through mathematical modeling and data fusion from available sensors, eliminating the need for complex external sensor installation while maintaining AOA measurement precision
Solution Approach 2:
The patent replaces the mechanical external sensor system (vanes or probes that physically interact with airflow) with an electronic computational system. The mechanical measurement approach is substituted with electronic sensor data processing and mathematical algorithms that compute AOA from accelerometer and airspeed data, thereby eliminating the mechanical complexity and vulnerability of external sensors
2Measurement precision
If external sensors are used for AOA measurement, then AOA data accuracy is improved, but reliability deteriorates due to damage and deterioration
Solution Approach 1:
The system uses existing onboard sensors (accelerometers and airspeed sensors) that are already part of the aircraft's standard equipment to self-determine AOA. These internal sensors are protected by the aircraft structure and do not protrude externally, making them immune to the damage and deterioration that affect external AOA sensors. The system serves itself by utilizing resources already available on the aircraft without requiring vulnerable external additions
Solution Approach 2:
The patent protects against the reliability issues of external sensors by using internal sensors that are shielded by the aircraft structure before any potential damage can occur. The accelerometers and airspeed sensors are housed within the aircraft fuselage, providing beforehand protection against environmental factors, bird strikes, ice accumulation, and other hazards that plague external AOA sensors
3Measurement precision
If external AOA sensors are installed, then AOA measurement capability is improved, but ease of manufacture and installation worsens
Solution Approach 1:
The patent makes the AOA measurement system universal by using accelerometers and airspeed sensors that are already standard equipment on most modern aircraft. These multi-functional sensors serve both their primary navigation/flight control functions and AOA measurement functions simultaneously. This eliminates the need for specialized AOA sensor installation and calibration, as the system repurposes existing universal aircraft instrumentation for dual purposes
Data Source
AI summary
Systems and methods for determining angle of attack (AOA) for an aircraft are disclosed. In implementations, a kinematic AOA signal and an aerodynamic AOA signal are determined based on measurements received from an airspeed sensor and an inertial reference system (IRS) or attitude and heading reference system (AHRS). The kinematic AOA signal is low pass filtered and the aerodynamic AOA signal is band-pass filtered. A blended AOA signal for the aircraft is then determined by summing the filtered kinematic AOA and aerodynamic AOA signals.