Air Data Attitude Reference With Inertial Drift Correction
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Solution Overview
Problem
Existing air data systems using inertial sensors for aircraft attitude estimation suffer from sensor errors that accumulate over time, particularly turn-on to turn-on biases and scale factor errors, which are unpredictable and cannot be effectively compensated using predefined correction factors.
Innovation Solution
A system utilizing multiple air data computers with inertial sensor assemblies that exchange attitude and acceleration information to correct for bias and scale factor errors, incorporating a Kalman estimator for iterative error correction and blending angular rates to enhance accuracy, and enabling fault detection and graceful degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If integration techniques are used to determine aircraft attitude from inertial sensor outputs, then attitude information can be generated, but sensor errors compound over time reducing accuracy
Solution Approach 1:
The system uses barometric altitude measurements as a feedback reference to detect and correct drift in inertial sensor integration. The air data computer compares integrated attitude information against barometric altitude data to identify sensor errors and apply corrections, preventing error accumulation over time.
Solution Approach 2:
Barometric altitude measurements serve as an intermediary reference system. Instead of directly trusting inertial sensor integration, the system uses barometric data as a mediator to detect and correct inertial sensor errors, bridging the gap between the two measurement systems.
2Measurement precision
If multiple air data computers are used to exchange attitude and acceleration information, then error correction improves, but system complexity increases
Solution Approach 1:
The system merges data from multiple air data computers by having them exchange attitude and acceleration information. This combination allows cross-validation and error correction while distributing the computational load, achieving improved precision without proportionally increasing overall system complexity.
Data Source
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AI summary
An air data computer (10A, 10B) senses acceleration and rotational rate of an aircraft with an inertial sensor assembly of the air data computer (10A, 10B). The air data computer (10A, 10B) determines first attitude information of the aircraft based on the acceleration and rotational rate sensed with the inertial sensor assembly. The air data computer (10A, 10B) receives second attitude information of the aircraft from a source external to the air data computer (10A, 10B), and determines attitude correction values based on the first attitude information and the second attitude information. The air data computer (10A, 10B) applies the attitude correction values to the first attitude information to produce error-corrected attitude information that is output from the air data computer (10A, 10B).