Accelerometer Calibration via Magnetic Field Substitution
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Solution Overview
Problem
Conventional methods for testing and calibrating built-in accelerometers in portable electronic devices require a physical connection to an external test system, making high-volume manufacturing challenging due to alignment constraints and increased production time, especially since accurate alignment of sensing axes to less than 1 degree is difficult to achieve.
Innovation Solution
A method and system using a custom test fixture and software that allows for contactless testing and calibration of accelerometers, where the device is placed in a nest within the fixture, and offset values are calculated and stored without the need for a physical connection to an external system, utilizing an inclinometer, optical switch, and magnetic sensor to determine levelness and calculate offset values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a physical connection to an external test system is used for accelerometer calibration, then measurement accuracy can be achieved, but production time increases and alignment precision becomes difficult to maintain
Solution Approach 1:
The patent replaces the mechanical physical connection system with a magnetic field-based wireless communication system. The test system uses magnetic fields to transmit calibration data to the accelerometer without requiring physical contact or alignment, thereby eliminating the time-consuming mechanical connection process while maintaining calibration accuracy.
Solution Approach 2:
The patent introduces magnetic fields as an intermediary medium between the external test system and the accelerometer. This intermediary enables data transmission and calibration without direct physical contact, resolving the contradiction by providing a non-mechanical pathway that is both accurate and time-efficient.
2Measurement precision
If a physical connection to an external test system is used for accelerometer calibration, then calibration can be performed, but device complexity and alignment requirements increase
Solution Approach 1:
The patent substitutes complex mechanical alignment systems with a simpler magnetic field-based system. The magnetic intermediary naturally handles the coupling between the test system and accelerometer without requiring precise mechanical alignment, thereby reducing device complexity while maintaining calibration precision.
3Measurement precision
If conventional testing methods with physical connections are used, then accelerometer calibration is achievable, but manufacturing efficiency decreases
Solution Approach 1:
The patent replaces mechanical connection-based testing with wireless magnetic field communication, eliminating the need for time-consuming physical setup and teardown processes. This substitution maintains calibration accuracy while dramatically improving manufacturing efficiency by enabling faster, contactless calibration operations.
Solution Approach 2:
The magnetic field-based system enables continuous calibration operations without the interruptions inherent in mechanical connection methods. The wireless magnetic communication allows for uninterrupted data transmission and calibration processes, thereby enhancing manufacturing efficiency while preserving measurement precision.
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 approach reduces production time and costs by enabling efficient, high-volume manufacturing of portable electronic devices with accurate accelerometer calibration, improving user interaction by providing more precise and repeatable measurements.
Implementation Method 1
an inclinometer (414) connected to the controller (420), wherein the controller (420) is configured to determine a levelness of the test fixture (400) using the inclinometer (414)
Implementation Method 2
wherein the electronic device, in a testing and calibrating mode, is configured to automatically calculate an offset value for each sensing axis of the accelerometer in response to the magnetic sensor (162) detecting the electromagnetic field
Data Source
AI summary
A method and system for testing and calibrating an accelerometer of an electronic device are provided. In accordance with one embodiment, there is a test system for an electronic device having an accelerometer with three mutually orthogonal sensing axes, the test system comprising: a test fixture having: a nest defining a cavity for receiving an electronic device; wherein the nest is configured so that, when the test fixture is substantially horizontal, a two-dimensional sensing plane defined by two of the sensing axes of the accelerometer is substantially horizontal and the third sensing axis is perpendicular to the two-dimensional sensing plane and substantially parallel to the force of gravity.