Wrist Accelerometer Arm Swing Angle Calculation
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Solution Overview
Problem
Existing wearable electronic devices struggle to accurately measure and evaluate arm swing angles during running or walking, often requiring multiple sensors and complex processes, which increases cost, weight, and processing complexity.
Innovation Solution
An electronic device with a processor that identifies cyclic changes in three-dimensional acceleration measured at the wrist, defines a two-dimensional plane containing the arm swing, and calculates the arm swing angle without the need for additional sensors like gyroscopes, by extracting gravitational and centrifugal acceleration components and integrating movement velocity to determine the arm swing angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors (acceleration sensors and angular velocity sensors) are used to measure arm swing, then measurement precision is improved, but device complexity and weight increase
Solution Approach 1:
The patent extracts and eliminates the need for angular velocity sensors (gyroscopes) from the measurement system. By using only acceleration sensors and applying signal processing techniques (FFT analysis, coordinate transformation, integration), the system achieves accurate arm swing angle measurement without the complexity and weight of multiple sensor types.
Solution Approach 2:
The patent replaces the mechanical/physical sensor system (angular velocity sensors) with a computational approach. By processing acceleration sensor data through mathematical operations (coordinate system transformations, double integration), the system substitutes physical measurement devices with computational methods to achieve the same measurement goal.
2Measurement precision
If multiple sensors are used to measure arm swing, then measurement precision is improved, but device weight increases
Solution Approach 1:
The patent removes angular velocity sensors from the device configuration, retaining only acceleration sensors. This extraction of unnecessary components directly reduces device weight while maintaining measurement precision through alternative computational methods.
3Measurement precision
If complex measurement processes are used, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent implements automated signal processing where the system automatically performs coordinate system transformations, FFT analysis, and integration operations without requiring manual intervention. The processor automatically identifies arm swing cycles, transforms acceleration data to the arm swing coordinate system, and calculates angles, making the complex process transparent to the user.
4Measurement precision
If additional sensors are added, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent eliminates the need for expensive angular velocity sensors, using only acceleration sensors which are more cost-effective. This extraction of costly components directly reduces manufacturing costs while maintaining measurement precision through computational alternatives.
Solution Approach 2:
The patent makes the acceleration sensor perform multiple functions: detecting both linear acceleration and, through computational processing, angular motion characteristics. This multi-functionality eliminates the need for separate angular velocity sensors, reducing component count and manufacturing cost.
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 solution allows for accurate and simplified measurement and evaluation of arm swing angles, reducing device weight and complexity while providing users with meaningful arm swing information without the need for additional sensors, thus enhancing user feedback and reducing costs.
Implementation Method 1
identifies a cyclic change related to an arm swing of a user from a three-dimensional acceleration measured by a first measurer
Implementation Method 2
extracting gravitational and centrifugal acceleration components
Data Source
AI summary
An electronic device includes at least one processor that identifies a cyclic change related to an arm swing of a user from a three-dimensional acceleration measured by a first measurer. The at least one processor defines a two-dimensional plane containing a plane of the arm swing of the user from the three-dimensional acceleration measured at a wrist of the user, detects the cyclic change as a motion on an arc centered at a shoulder of the user in the two-dimensional plane, and obtains an angle of the arm swing.