Inertial Frame Alignment for Reassembled On-Board Equipment
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Solution Overview
Problem
Current methods for harmonizing the position and orientation of equipment on a mobile carrier, such as airborne radar systems, are either mechanically precise but impractical for frequent reassembly or rely on environmental-dependent digital processing, which is not always reliable.
Innovation Solution
An automatic system using inertial unit measurements and three-axis accelerometers to calculate and adjust the position and orientation of equipment relative to the mobile carrier's frame of reference, without requiring additional measurements or adjustments, utilizing a geometric transformation defined by translation and rotation parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If precise mechanical calibration using centering pins or shims is used to fix the position and orientation of equipment on the mobile carrier, then manufacturing precision is improved, but device complexity and ease of operation deteriorate due to requiring mechanical parts and precise assembly
Solution Approach 1:
The patent replaces mechanical calibration systems (centering pins, shims, dedicated mechanical parts) with an inertial measurement-based digital calibration system. The method uses inertial measurements from the mobile carrier and on-board equipment, combined with digital processing to calculate position and orientation parameters, eliminating the need for complex mechanical calibration components and procedures.
Solution Approach 2:
The calibration system uses the mobile carrier's own inertial measurement unit and the on-board equipment's inertial measurements to perform self-calibration. The system automatically calculates the geometric transformation parameters between reference frames using inertial data collected during flight maneuvers, without requiring external mechanical calibration tools or procedures.
2Manufacturing precision
If mechanical calibration with centering pins and shims is used, then manufacturing precision is improved, but ease of repair and adaptability worsen when systems are disassembled and reassembled
Solution Approach 1:
The patent replaces mechanical calibration systems (centering pins, shims, dedicated mechanical parts) with an inertial measurement-based digital calibration system. The method uses inertial measurements from the mobile carrier and on-board equipment, combined with digital processing to calculate position and orientation parameters, eliminating the need for complex mechanical calibration components and procedures.
Solution Approach 2:
The system performs preliminary inertial measurement collection during flight maneuvers to establish the geometric transformation parameters. By collecting inertial data during controlled flight maneuvers and calculating the transformation parameters in advance, the system prepares the calibration data before normal operation, making the system ready for immediate use without requiring repeated mechanical calibration during maintenance.
3Extent of automation
If digital compensation methods using multiple image acquisitions and environmental measurements are used, then automation is improved, but reliability worsens due to environmental dependencies
Solution Approach 1:
The patent extracts the calibration measurements from environmental dependencies (optical crosshairs, ground-based reference systems) and relocates them to the mobile carrier itself through inertial measurement units. By using inertial measurements from the carrier and on-board equipment, the system removes the dependency on external environmental factors and ground-based measurement infrastructure.
Solution Approach 2:
The patent introduces inertial measurement units as intermediary devices that measure the motion and orientation of both the mobile carrier and on-board equipment independently of environmental factors. The inertial measurements serve as an intermediary that bridges the gap between the carrier and equipment reference frames without requiring direct environmental references or optical crosshairs.
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 precise and independent harmonization of equipment orientation, reducing the need for mechanical calibration and environmental dependencies, facilitating efficient operation and data compensation in radar systems and other on-board equipment.
Implementation Method 1
calculations on measurements made on the one hand by the inertial unit on board the carrier
Implementation Method 2
by the accelerometer(s) fixed on the on-board equipment
Data Source
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AI summary
The invention relates to a system and a method for automatically harmonising the position and/or orientation between an apparatus (6, 10) on board a mobile carrier (4) and a reference frame of the mobile carrier, the mobile carrier (4) being provided with an inertial unit (8) suitable for providing measurements in the reference frame. The system (2) comprises: - at least one accelerometer (12) mechanically coupled to the on-board apparatus (6, 10) and providing acceleration measurements in a reference frame referred to as the associated on-board apparatus, - a reception unit (14) configured to receive measurements provided by the inertial unit (8) and measurements provided by the accelerometer (12), - a computing unit (20) configured to compute values of parameters defining a geometric transformation for moving from the reference frame of the carrier to the reference frame of the on-board apparatus, from the measurements, carried out for at least two different flight orientations, by the inertial unit (8) and by the accelerometer (12).