Inertial Measurement Unit Alignment for Unstable Aircraft Platforms
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Solution Overview
Problem
The existing methods for aligning inertial measurement units on aircraft are inefficient, particularly when the aircraft is on unstable platforms or in flight, as they require restarting the alignment process due to detected movements, leading to wasted time and potential drift falsification, and cannot be completed in situations with persistent platform movements.
Innovation Solution
A method that determines the aircraft's status and environment to adapt the alignment process, allowing for flight, ground, or sea alignments, thereby ensuring precise alignment regardless of the conditions, by distinguishing between flight and non-flight states and assessing stability to choose appropriate alignment procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the existing alignment method is used on unstable platforms or during flight, then the alignment process must be restarted due to detected movements, but this leads to wasted time and potential drift falsification
Solution Approach 1:
The alignment method dynamically adapts to the aircraft's operational state by detecting whether the aircraft is in flight or on the ground, and whether it is on a stable or unstable platform. The method adjusts the alignment procedure accordingly, allowing continuous alignment during flight and on unstable platforms, rather than requiring restarts. This dynamic adaptation resolves the contradiction by making the system flexible enough to maintain accuracy without time loss in various operational conditions.
Solution Approach 2:
The invention changes the alignment parameters based on the detected operational conditions. When flight is detected, the method uses flight-specific alignment parameters that account for aerodynamic forces and flight dynamics. When on the ground, it uses ground-specific parameters. This parameter adaptation allows the alignment to remain accurate without requiring restarts, thus resolving the contradiction between reliability and time loss.
2Reliability
If the alignment process is restarted due to detected movements, then alignment accuracy may be maintained, but the availability of stand-by instruments for take-off is compromised
Solution Approach 1:
The method dynamically adjusts the alignment procedure based on operational conditions, allowing the stand-by instrument to complete alignment successfully during flight and on unstable platforms without restarts. This dynamic approach ensures both alignment accuracy and instrument availability, as the system adapts to rather than rejects movement conditions.
Solution Approach 2:
The invention converts the previously harmful effect of detected movements (which caused alignment restarts) into a beneficial condition by developing alignment methods specifically tailored for flight and unstable platform conditions. By embracing these movement conditions and creating appropriate alignment procedures for them, the system maintains accuracy while ensuring availability, thus converting what was previously a problem into a solution.
3Reliability
If the existing alignment method is used on unstable platforms, then alignment can be completed, but it requires waiting for platform movements to stop, which is harmful to aircraft profitability
Solution Approach 1:
The method implements dynamic adaptation to unstable platform conditions by detecting whether the aircraft is on a stable or unstable platform and selecting the appropriate alignment procedure. For unstable platforms, it uses a specialized alignment method that accounts for continuous movements, allowing alignment to proceed without waiting for stability. This resolves the contradiction by enabling alignment completion without time loss.
Solution Approach 2:
The system performs preliminary detection of the operational state (flight or ground, stable or unstable platform) and prepares the appropriate alignment procedure in advance. This preliminary action allows the system to immediately execute the correct alignment method without delays, resolving the contradiction between alignment completion and wait time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables precise alignment of inertial measurement units under various conditions, reducing the risk of drift falsification and ensuring the availability of stand-by instruments for take-off, even on unstable platforms, by allowing continuous alignment without the need for restarts.
Implementation Method 1
The inertial measurement unit comprises for example three gyrometers and two or three accelerometers. The gyrometers measure the speeds of rotation of the sensor's reference system
Implementation Method 2
The accelerometers measure non-gravitational forces applied to the aircraft, from which are derived accelerations of translation of the reference system
Implementation Method 3
By integration of the rotation speeds, it is possible to know the orientation of the stand-by instrument with respect to the inertial reference system
Implementation Method 4
This initialization comprises an alignment phase notably consisting in estimating a drift of each gyrometer, that is to say a rotation speed measured by the gyrometer in question in the absence of any movement of the latter
Data Source
AI summary
A method for independent alignment of an inertial measurement unit for a stand-by instrument in an aircraft includes: determining a status of the aircraft, that is to say whether or not the aircraft is in flight, and in the case where the aircraft is detected as being in flight, carrying out a flight alignment, and in the case where the aircraft is not detected as being in flight, determining a stability of the aircraft, that is to say whether the aircraft is on the ground or at sea, and in the case where the aircraft is detected as being on the ground, carrying out a ground alignment, and in the case where the aircraft is detected as being at sea, carrying out a sea alignment.