Accelerometer Calibration for Step Count Accuracy
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Solution Overview
Problem
Existing wireless sensor devices for posture detection and activity monitoring lack accuracy due to non-calibrated accelerometer data, which can be arbitrarily positioned relative to the body axes, leading to less effective posture detection and activity level monitoring.
Innovation Solution
A wireless sensor device with a calibration procedure that aligns the accelerometer axes with the body axes, using automatic, manual, or sleep study calibration methods to determine the vertical axis and subsequently calibrate the other axes, enabling accurate detection of body transitions, activities, and rest positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If accelerometer data is used without calibration, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent implements calibration procedures (automatic, manual, or sleep study-based) that are performed before normal operation to pre-align the accelerometer axes with the body axes. This preliminary action ensures that subsequent posture detection and activity monitoring operate on accurately oriented data, resolving the contradiction by accepting temporary increased complexity during setup in exchange for sustained high measurement precision during use.
2Measurement precision
If calibration procedures are implemented, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs automatic calibration methods that enable the device to self-calibrate without requiring user intervention or external equipment. The system autonomously performs calibration routines, identifies body axes, and configures the accelerometer orientation, thereby improving measurement precision while minimizing the increase in device complexity by eliminating the need for complex manual calibration interfaces or additional calibration hardware.
3Ease of manufacture
If accelerometer axes are misaligned with body axes, then ease of manufacture is improved, but measurement precision deteriorates
Solution Approach 1:
The patent addresses the misalignment issue by dynamically changing the reference frame parameters through calibration. Instead of requiring precise mechanical alignment during manufacturing, the system adjusts the coordinate system parameters (rotation angles, axis orientations) based on calibration data collected during automatic, manual, or sleep study procedures. This allows easy manufacturing of the sensor assembly while achieving precise posture detection through software-based parameter adjustment.
Data Source
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AI summary
A method for determining step count is disclosed. The method comprises: receiving sensor data; detecting an activity of a body based on the sensor data; classifying the activity of the body based on the sensor data; and determining step count based on classification of the activity. Also a body sensor device for determining step count is disclosed.