Multi-axis Accelerometer Using Integrated Permanent Magnet Biasing
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Solution Overview
Problem
Existing acceleration sensors require an additional biasing magnetic field to function properly, which complicates the detection of accelerations in both planar and perpendicular directions, and are susceptible to temperature and external field disturbances.
Innovation Solution
A sensor arrangement with separate field detectors, each sensitive to specific directions, eliminates the need for a biasing magnetic field by using a field generator and detectors configured to detect components of the magnetic field in a plane and perpendicular to it, with the first detector more sensitive to accelerations perpendicular to the plane and the second more sensitive to in-plane accelerations, and optionally includes a third detector for additional axes, along with a movable object and elastic material to stabilize the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an additional biasing magnetic field is used to improve sensitivity and linearity, then the acceleration sensor functions properly, but the device complexity increases and temperature disturbances worsen
Solution Approach 1:
The invention extracts the biasing magnetic field function from an external source and integrates it into the movable object itself through a permanent magnet. This eliminates the need for separate biasing field generation while maintaining the required sensitivity and linearity for proper sensor operation.
Solution Approach 2:
The invention combines the biasing magnetic field source with the movable object by integrating a permanent magnet into it. This merging reduces device complexity by eliminating separate biasing field components while maintaining measurement precision through the combined structure.
2Measurement precision
If an additional biasing magnetic field is used to improve sensitivity and linearity, then the acceleration sensor functions properly, but temperature disturbances increase
Solution Approach 1:
The movable object generates its own biasing magnetic field through an integrated permanent magnet, making the system self-sufficient. This self-service approach reduces dependence on external fields that may introduce temperature-related instability, thereby improving linearity while minimizing temperature disturbances.
3Measurement precision
If separate field detectors are used for different directions, then measurement precision improves, but device complexity increases
Solution Approach 1:
The invention makes the movable object multi-functional by integrating both the field generator (permanent magnet) and the field detector (magneto-resistive elements) within it. This universal structure performs multiple functions - generating the biasing field, detecting acceleration in multiple directions, and maintaining sensitivity - thereby improving detection accuracy without proportionally increasing device complexity.
Solution Approach 2:
The invention employs a nested structure where magneto-resistive elements are positioned within or around the movable object that contains the permanent magnet. This nesting allows separate field detectors for different directions to be integrated compactly, improving measurement precision while minimizing the increase in device complexity.
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 configuration enhances sensitivity and linearity while minimizing temperature and external field disturbances, allowing accurate detection of accelerations without additional magnetic fields, thereby improving the sensor's performance and reliability.
Implementation Method 1
four magneto-resistive elements. These four magneto-resistive elements detect components of the magnetic field originating from the magnetic body
Implementation Method 2
a permanent magnet arranged relative to the four magneto-resistive elements such that the permanent magnet generates a magnetic field
Data Source
AI summary
Devices (1) are provided with sensor arrangements (2) comprising field generators (10) for generating magnetic fields and first/second/third field detectors (11,12,13) comprising first/second/third elements (R1-R4, S1-S4, T1-T4) for detecting first/second/third components of the magnetic fields in a plane and movable objects (14) for, in response to first/second/third accelerations of the movable objects (14) in first/second/third directions, changing the first/second/ third components of the magnetic fields in the plane. The first (second, third) field detector (11,12,13) is more sensitive to the first (second, third) acceleration than to the other accelerations. Such devices (1) have a good sensitivity and a good linearity. The elements (R1-R4, S1-S4 , T1-T4) form part of bridges. The first elements (R1-R4) surround the second and third elements (S1-S4 , T1-T4) , or vice versa. The first elements (R1-R4) may be in round or rectangular form and the second and third elements (S1-S4, T1-T4) may be in the form of sun beams leaving a sun. The first elements are non-saturated barberpole magnetoresistive elements measuring the field strength which varies in response to accelerations in a direction perpendicular to the plane. The second and third elements are saturated barberpole magnetoresistive elements measuring changes in the direction of the magnetic field in response to accelerations in directions parallel to the plane.