Mutual Alignment of Inertial Measurement Units in Aircraft
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Solution Overview
Problem
Current aircraft piloting aid instruments face challenges in aligning inertial measurement units without external information sources, especially when the aircraft is in motion, which complicates the process and can lead to errors in attitude determination.
Innovation Solution
A system comprising two combined standby instruments with communication means allows for mutual alignment of inertial measurement units based on relative positions and synchronized measurements during the same period, using adaptive filters to correct for drift and transform data between the instruments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an alignment phase is implemented to converge towards accurate drift estimates, then attitude determination accuracy is improved, but the alignment process requires several tens of seconds and imposes immobility requirements that are difficult to achieve in flight
Solution Approach 1:
The system uses feedback from communication means between the two instruments to continuously exchange alignment information and drift estimates. Each instrument receives feedback from the other's measurements and adjusts its own drift estimates accordingly, enabling continuous alignment without requiring immobility or external references.
Solution Approach 2:
Each inertial measurement unit performs alignment using its own measurements combined with information from the other instrument. The system is self-sufficient, requiring no external information sources or references. The instruments serve each other's alignment needs through mutual information exchange, eliminating the need for external alignment aids.
2Measurement precision
If external information sources are used for estimating aircraft movements during alignment, then alignment accuracy is improved, but the autonomy of the combined standby instrument is reduced
Solution Approach 1:
The alignment system is completely autonomous, using only measurements from the two instruments themselves. Each instrument contributes its own measurement data and uses the other's data for alignment, eliminating any dependency on external information sources. This maintains full autonomy while achieving accurate alignment through mutual correction of drifts.
3Reliability
If two combined emergency instruments are installed for redundant display, then system reliability is improved, but the complexity of aligning multiple inertial measurement units increases
Solution Approach 1:
The alignment functions of both instruments are merged into a single mutual alignment process. Instead of each instrument having separate alignment systems, the two instruments work together in a unified alignment procedure where they exchange information and jointly determine their relative drifts, simplifying the overall system complexity while maintaining redundancy.
Solution Approach 2:
The communication means serve multiple functions: they enable data exchange for display redundancy and simultaneously provide the alignment function for both inertial measurement units. This multi-functionality reduces the need for separate alignment systems, thereby reducing overall device complexity while maintaining the reliability benefits of having two instruments.
Data Source
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AI summary
The invention relates to aircraft pilot assistance instruments and more particularly to a system that comprises two instruments (ICS1, ICS2) for displaying flight parameters, in particular the altitude of the aircraft. Each instrument includes an inertial measurement unit (121, 122). The invention can be used for aligning the inertial measurement units (121, 122) in an independent manner even when the aircraft is moving. The alignment can be carried out without using external information sources. To this end, the alignment is carried out mutually for both inertial measurement units (121, 122) from a relative position of each instrument (ICS1, ICS2) and from measures (O1, O2, ?i, ?2) made by each instrument (ICS1, ICS2) during an identical time period.