Adaptive Altimeter Filtering for Noise and Response Trade-offs
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Solution Overview
Problem
Traditional altimeter systems face challenges in reducing noise and responding to rapid altitude changes and varying terrain conditions, leading to unreliable altitude measurements, especially in complex aircraft operations.
Innovation Solution
Adaptive filtering is implemented within the altimeter to selectively compensate for sensor measurement noise based on current altitude, using filter mode selections from an external avionics system to provide stable altitude measurements by updating filter coefficients in real-time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional post-processed filtering methods are used to stabilize altitude measurements, then measurement noise is reduced, but responsiveness to rapid changes in aircraft altitude deteriorates
Solution Approach 1:
The filter coefficients are made dynamic and adaptive rather than fixed. The system continuously adjusts the filter characteristics based on current flight conditions, allowing the filter to be more aggressive during stable conditions and more conservative during rapid changes, thus resolving the contradiction between noise reduction and responsiveness
Solution Approach 2:
The system changes the filter parameters (coefficients) based on the measured altitude rate of change and other flight conditions. By dynamically adjusting these parameters, the system optimizes the balance between smoothing noise and preserving rapid altitude change information
2Device complexity
If traditional filtering methods are applied uniformly across all operating conditions, then implementation simplicity is maintained, but measurement reliability deteriorates in specific conditions like hover mode or complex terrain
Solution Approach 1:
The system applies different filter characteristics tailored to specific flight conditions and terrain types. Rather than a uniform filter, the system adapts its filtering behavior locally to match the requirements of hover mode, forward flight, mountainous terrain, or flat terrain, thereby improving reliability without excessive complexity
Solution Approach 2:
The system uses feedback from the measured altitude data, altitude rate of change, and flight mode information to continuously adjust the filter coefficients. This closed-loop approach ensures the filter adapts to current conditions, improving reliability while maintaining manageable system complexity through algorithmic rather than hardware complexity
Data Source
AI summary
A method of processing altitude measurements for an aircraft is disclosed. The method involves filtering raw altimeter data within an altimeter to substantially limit random variations in the altitude measurements for one or more altimeter measurement profiles.