Airborne Array Antenna Positional State Determination
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Solution Overview
Problem
Large flexible airborne array antennas face challenges in determining their positional state due to the impracticality of co-located inertial instruments and the inability of optical systems to provide the necessary temporal and spatial resolution for beam forming in electronically scanned array (ESA) radars.
Innovation Solution
A system utilizing distributed accelerometers coupled with processing circuitry and an inertial navigation system (INS) to calculate the positional state of the array, allowing for beam steering and motion compensation, with the accelerometers being tri-axial MEMS devices positioned at a high spatial density to capture significant motion frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a co-located inertial instrument is used to measure array motion, then motion measurement accuracy is improved, but device complexity and packaging difficulty increase due to the large size and flexible nature of the array
Solution Approach 1:
The patent divides the measurement system into multiple distributed accelerometers positioned at different locations across the array structure. Instead of using a single co-located inertial instrument, the system segments the measurement function across multiple simplified sensor nodes, making the system more adaptable to the large-scale flexible array while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces a processing system that acts as an intermediary between the distributed accelerometers and the final motion determination. This processing system integrates data from multiple accelerometers and combines it with information from an inertial navigation system, mediating the complex task of determining array motion without requiring a single complex co-located instrument.
2Measurement precision
If optical systems are used to measure array shape and orientation, then spatial resolution is improved, but temporal resolution is insufficient for beam forming requirements in ESA radars
Solution Approach 1:
The patent replaces optical measurement systems with a mechanical sensing approach using distributed accelerometers. These accelerometers directly measure motion and position at high temporal rates, substituting the slower optical measurement process with a faster mechanical sensing system that meets the temporal requirements for beam forming in ESA radars.
Solution Approach 2:
The patent changes the measurement parameter from direct position/orientation measurement (optical) to acceleration measurement (inertial). By measuring acceleration and integrating over time, the system achieves both the required spatial resolution and temporal resolution, as accelerometers can operate at high sampling rates while still providing position information through integration.
3Ease of manufacture
If the array structure is made flexible to reduce weight and complexity, then ease of manufacture is improved, but the ability to rigidly attach inertial instruments deteriorates
Solution Approach 1:
The patent segments the inertial measurement function across multiple distributed accelerometers rather than relying on a single attachment point. This segmentation allows the flexible array structure to be manufactured as intended, while the distributed sensor network maintains reliable measurement capability by not depending on rigid attachment at any single location.
Solution Approach 2:
The patent changes from measuring position directly (which requires rigid attachment) to measuring acceleration (which can be done with flexible mounting). The accelerometers measure local motion at their positions, and the system integrates this information to determine overall array motion, eliminating the need for rigid attachment while maintaining measurement reliability.
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
Enables accurate determination of the array's position and orientation, improving beam steering and motion compensation, even in large flexible arrays where traditional inertial instruments are impractical, by integrating data from multiple accelerometers and INS, enhancing the array's dynamic motion understanding.
Implementation Method 1
The positional state determining systems include an array of accelerometers distributed about the array antenna and coupled to processing circuitry
Implementation Method 2
an inertial navigation service that uses either inertial instruments (usually an integrated navigation system or INS)
Data Source
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AI summary
Systems and methods for determining a positional state of an airborne array antenna using distributed accelerometers are described. One such method includes receiving and formatting acceleration data from each of a plurality of accelerometers mounted at different locations along the array antenna, receiving position and orientation data from an inertial navigation service (INS) mounted on the array antenna, generating an INS estimated position for each accelerometer based on the position and orientation data from the INS, generating an accelerometer estimated position for each accelerometer based on the acceleration data, determining a position and orientation of each accelerometer based on the respective INS estimated position and the respective accelerometer estimated position, determining an estimated position of a center and an orientation of the array antenna based on the determined position and orientation of each accelerometer, and adjusting a direction of the array antenna based on the estimated position of the array antenna.