Vehicle Accelerometer Axis Alignment via Computational Transformation
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Solution Overview
Problem
Existing accelerometer installations in vehicles often fail to align the coordinate frame of the accelerometer with the vehicle's coordinate frame, especially in consumer-grade vehicles, where precise orientation is not feasible, leading to inaccurate acceleration measurements.
Innovation Solution
A method to align the accelerometer's axes with the vehicle's axes without external data, using transformation equations and analysis of acceleration events, such as stopping events, to determine the necessary rotation angles, allowing for the transformation of measured acceleration values into the vehicle's coordinate frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If precise physical placement and securing of the accelerometer is performed to guarantee orientation alignment, then measurement precision is improved, but device complexity and ease of installation deteriorate
Solution Approach 1:
The patent replaces the mechanical alignment system (physical placement and securing of the accelerometer to guarantee orientation) with a computational transformation system. The system uses measured acceleration values from the accelerometer, applies coordinate transformation equations with calculated transformation parameters, and outputs transformed acceleration values aligned with the vehicle coordinate frame. This substitution allows the accelerometer to be mounted in any orientation while achieving accurate measurements through software-based coordinate frame transformation.
2Measurement precision
If precise physical alignment of the accelerometer coordinate frame with the vehicle coordinate frame is performed, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent replaces the mechanical alignment operation (careful physical placement and securing) with an automated computational operation. The system automatically calculates transformation parameters from measured acceleration values and applies coordinate transformations without requiring manual orientation adjustment. This makes the installation process simpler while maintaining measurement accuracy through software-based alignment.
3Measurement precision
If external data or systems like GPS are used to determine coordinate frame relationship, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system determines the coordinate frame relationship self-sufficiently using only the acceleration values measured by the accelerometer itself. The transformation parameters are calculated from the measured acceleration data without requiring external data sources like GPS or additional sensing systems. This self-service approach reduces device complexity while achieving accurate coordinate frame alignment.
Data Source
AI summary
The axes of an accelerometer, installed in a vehicle at an arbitrary orientation, may be realigned to the coordinate frame of the vehicle. In one implementation, a method may include determining, based on acceleration measurements from the accelerometer that likely corresponds to stopping, a dominant orientation of the accelerometer in relation to gravity, including calculating a first transformation angle and a second transformation angle as parameters to perform coordinate realignment of a coordinate frame of the accelerometer to a coordinate frame of the vehicle. The method may further include identifying, based on the acceleration measurements, an occurrence of acceleration events of the vehicle; determining, based on an analysis of the acceleration events, a third transformation angle; and storing the first, second, and third transformation angles.