Aerospace Roll Angle Orientation Using Dynamic Motion Bias Correction
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Solution Overview
Problem
Existing aerospace platforms face challenges in accurately determining the roll angle orientation due to high bias drift rates in rate gyros, which are not easily corrected, especially when integrated with less-costly MEMS gyros, and require frequent human intervention or rely on external systems like GPS, which may not provide sufficient integrity.
Innovation Solution
A method and system that utilize predetermined dynamic motion of the platform, where the roll axis is perpendicular to a certain plane, allowing the determination of the roll orientation angle by measuring the direction of the lateral rotation rate vector or its derivatives with respect to an external reference frame, using sensors that revolve about the longitudinal axis to suppress bias drift errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If highly accurate rate gyros (ring laser gyros or fiber optic gyros) are used to minimize bias drift, then measurement precision is improved, but device cost increases significantly
Solution Approach 1:
The patent employs inexpensive MEMS gyros with high bias drift rates instead of expensive ring laser or fiber optic gyros. The system accepts that these cheap sensors will accumulate bias errors over time, but compensates through periodic correction using external reference systems (GPS, magnetometers, accelerometers) to reset the bias, effectively making the sensor system economically viable despite its limitations
Solution Approach 2:
The patent implements a feedback mechanism where external reference systems (GPS positioning, magnetometer measurements, accelerometer data) continuously monitor the platform orientation and provide correction signals to compensate for the bias drift in MEMS gyros. This feedback loop allows the use of low-cost sensors while maintaining acceptable accuracy over extended periods
2Measurement precision
If frequent bias corrections are performed using external systems (GPS, magnetometers), then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent integrates multiple sensor types (GPS receiver, magnetometers, accelerometers) that serve dual purposes: they provide primary navigation and positioning functions while simultaneously serving as reference systems for correcting gyro bias drift. This multi-functionality reduces the need for dedicated correction hardware, thereby limiting the increase in system complexity
Solution Approach 2:
The system uses its own existing sensor suite (magnetometers, accelerometers, GPS) to self-correct the bias drift of the gyros without requiring external correction equipment. The platform's own sensors provide the reference data needed to maintain accuracy, reducing overall system complexity
3Productivity
If integration of rotation rate measurements is performed over extensive periods of time, then productivity is improved, but measurement precision deteriorates due to bias drift accumulation
Solution Approach 1:
The patent performs preliminary bias correction at regular intervals using external reference systems before the bias drift accumulates to unacceptable levels. By proactively resetting the bias using GPS, magnetometer, and accelerometer data, the system maintains measurement precision over extended operational periods without requiring frequent manual intervention
Data Source
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AI summary
A method and system are presented for use in determination of the orientation of an aerospace platform with respect to a first rotation axis. A direction of a rotation rate vector of said aerospace platform within a lateral plane intersecting with said first rotation axis is measured and the measured data is analyzed to determine an orientation angle of said aerospace platform about said first rotation axis. The measurement of the direction of the rotation rate vector comprises the following: A predetermined-dynamic state movement of said aerospace platform with respect to an external reference frame is provided, said predetermined-dynamic state movement being characterized by a certain direction of the rotation rate of the platform in said lateral plane, and/or of any time derivative thereof associated with a certain known direction within said external reference frame. While the aerospace platform is in said predetermined-dynamic state movement, said certain direction is determined by measuring a direction of the rotation rate of the aerospace platform within said lateral plane by a sensor assembly mounted on said platform and comprising at least one rotation rate sensor. An orientation of the platform with respect to said first axis is determined by determining a relation between said certain direction and said known direction within said external reference frame.