Head-worn Accelerometer Direction Detection via Gravity Vector Cross Products
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Solution Overview
Problem
Conventional sensors analyzing human posture using accelerometers struggle to distinguish front-back and left-right directions, leading to challenges in integrating them into wearable devices due to power consumption issues and size limitations, especially in applications like health trackers where accurate posture assessment is necessary.
Innovation Solution
A method using an accelerometer worn on the head to measure accelerations at different angles, calculating vectors in the left-right and front-back directions through cross products of gravity vectors, reducing power consumption and enhancing accuracy without the need for a gyroscope.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a gyroscope is added to distinguish front-back and left-right directions, then measurement precision is improved, but use of energy increases significantly
Solution Approach 1:
The patent extracts and removes the gyroscope component from the sensor system, achieving direction detection using only an accelerometer. By eliminating the high-power gyroscope while maintaining the essential functionality through clever algorithmic processing of accelerometer data, the system resolves the contradiction between measurement precision and power consumption.
Solution Approach 2:
The patent replaces the mechanical gyroscope sensor with a computational approach using accelerometer data. Instead of relying on mechanical rotation sensing, the system uses mathematical processing of acceleration vectors to derive directional information, substituting a mechanical sensing system with a computational one that consumes less power.
2Measurement precision
If a gyroscope is integrated into wearable devices, then front-back and left-right direction detection is enabled, but device size and complexity increase
Solution Approach 1:
The patent extracts the gyroscope from the sensor configuration, simplifying the device architecture. By removing this complex component and relying solely on the accelerometer with enhanced processing algorithms, the system reduces device complexity while maintaining the capability to detect front-back and left-right directions.
Solution Approach 2:
The patent makes the accelerometer perform multiple functions - not only detecting magnitude of acceleration but also deriving directional information that would traditionally require a gyroscope. This multi-functionality approach allows a single sensor type to replace what would otherwise require multiple specialized sensors.
3Use of energy by moving object
If only an accelerometer is used, then power consumption is reduced, but ability to distinguish front-back and left-right directions is lost
Solution Approach 1:
The patent introduces mathematical processing algorithms as an intermediary between the accelerometer sensor and the direction detection function. These algorithms act as a mediator that transforms raw acceleration data into meaningful directional information, enabling the accelerometer to achieve directional detection capabilities without requiring a gyroscope.
Solution Approach 2:
The patent changes the processing parameters and computational approaches applied to accelerometer data. By implementing specific algorithms that analyze acceleration patterns, timing, and vector relationships, the system extracts directional information that would otherwise be inaccessible from accelerometer data alone, effectively changing how the sensor output is interpreted.
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 significantly improves the accuracy of motion posture analysis by distinguishing user movements in up-down, front-back, and left-right directions using only an accelerometer, reducing power consumption and enabling precise posture assessment in wearable devices.
Implementation Method 1
measuring, by an accelerometer worn on the head of the user, a first acceleration at a time point at which the user stares at the front; measuring, by the accelerometer, a second acceleration at a time point at which the user stares at an angle other than the front
Data Source
AI summary
According to the present invention, a method, for determining front-back and left-right directions of a pose sensor worn on a head of a user, may comprise: measuring a first acceleration at a time point where the user stares at the front; measuring a second acceleration at a time point where the user stares at an angle other than the front; measuring a first and second gravity vectors respectively corresponding to the time points at which the first and the second accelerations were measured when an index of variation of each of the first and second acceleration satisfies a predetermined condition; and calculating vectors in the left-right direction and the front-back direction by performing cross product on the first and second gravity vectors, wherein the angle other than the front includes an angle rotated with respect to an axis of any one of an up-down, left-right, and front-back directions.