Accelerometer Assembly With Digital Misalignment Compensation
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Solution Overview
Problem
Existing accelerometers with transverse insensitivity face prohibitive alignment errors during assembly, necessitating costly mechanical adjustments and manual operations to achieve precision within 3 mrad for sensitive axis alignment, which is crucial for applications like certified civil aviation.
Innovation Solution
An acceleration-measuring sensor assembly comprising a single-axis principal accelerometer with transverse insensitivity, a secondary two-axis accelerometer forming an orthonormal trihedron, and an electronic processing unit to calculate compensation using the relationship S=SprA-μCalZ·SsecX+μCalX·SsecZ, allowing for misalignments up to 50 mrad without mechanical adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single-axis principal accelerometer with transverse insensitivity is used, then measurement precision along the sensitive axis is improved, but alignment error during assembly increases
Solution Approach 1:
The system is divided into two independent accelerometer components: a principal single-axis accelerometer for measuring acceleration along the sensitive axis, and a secondary two-axis accelerometer for measuring transverse accelerations. This segmentation allows each component to be optimized independently - the principal accelerometer achieves high measurement precision while the secondary accelerometer captures alignment errors, resolving the contradiction between measurement precision and manufacturing precision.
Solution Approach 2:
The secondary two-axis accelerometer acts as an intermediary device that measures the misalignment between the sensitive axis and the reference axis. By introducing this intermediary measurement system, the patent enables digital compensation of alignment errors without requiring mechanical precision during assembly, thus resolving the contradiction between measurement precision and manufacturing precision.
2Manufacturing precision
If mechanical alignment adjustments are performed to achieve 3 mrad precision, then axis alignment is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces mechanical alignment adjustment systems with a digital compensation system. Instead of using complex mechanical devices to physically align the sensitive axis with the reference axis to 3 mrad precision, the system uses two accelerometers to measure the actual alignment state and digitally compensates for the misalignment through calculation, thereby eliminating mechanical complexity while maintaining measurement precision.
Solution Approach 2:
The system changes the approach from physical parameter adjustment (mechanical alignment) to digital parameter compensation. By measuring the actual alignment parameters with the secondary accelerometer and using these parameters in digital calculations to compensate for misalignment, the patent achieves the desired precision without the complexity of mechanical adjustment operations.
3Measurement precision
If manual alignment operations are performed, then measurement accuracy is improved, but productivity decreases
Solution Approach 1:
The system enables self-alignment through the secondary two-axis accelerometer automatically measuring the misalignment state during assembly. The measured parameters are then used by the electronic processing unit to digitally compensate for alignment errors, eliminating the need for manual alignment operations while maintaining measurement accuracy, thus resolving the contradiction between measurement precision and productivity.
Solution Approach 2:
The patent replaces manual mechanical alignment operations with an automated digital compensation system. The secondary accelerometer provides automatic measurement of alignment state, and the electronic processing unit performs automatic calculation and compensation, thereby maintaining measurement accuracy while significantly improving assembly productivity by eliminating manual operations.
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
Achieves precise acceleration measurements within the desired error budget of less than 1 mg by compensating for transverse accelerations through digital calculation, reducing costs and eliminating the need for costly mechanical alignment operations.
Implementation Method 1
a seismic mass (1) capable of moving translationally along the sensitive axis A
Implementation Method 2
amplifying means (2) for amplifying the force that generates this translational movement, which is measured by means of two vibrating beams (30)
Data Source
AI summary
An acceleration-measuring sensor assembly includes an accelerometer subassembly with three measurement axes, mounted in a housing equipped with securing elements, and configured to determine an acceleration along a principal axis A, the assembly comprising: a single-axis principal accelerometer with a seismic mass moving in a straight line along a principal axis A, measuring acceleration along the principal axis A which is misaligned with respect to a reference axis Y by at most 50 mrad, a secondary accelerometer having at least two measurement axes and measuring respectively along two axes X and Z which with the reference axis Y form a direct orthonormal trihedron (O, X, Y, Z), the measurement precision of the two-axis accelerometer along each of its axes being at least ten times inferior to the measurement precision of the single-axis accelerometer, and an electronic processing unit configured to calculate a compensated acceleration S.