Fall Detection Using Acceleration Magnitude Difference
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Solution Overview
Problem
Existing fall detection devices face challenges in accurately determining the start of a fall and predicting falls due to the complexity of using multiple thresholds and susceptibility to centrifugal forces and simple shocks, leading to increased processing load and erroneous determinations.
Innovation Solution
A fall detection device that uses acceleration sensors to detect accelerations in three orthogonal axes and calculates an evaluation value based on the difference between steady-state and fall-state accelerations, allowing for reliable fall detection and prediction without the need for multiple thresholds or heavy calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple thresholds are used to determine fall state, then the determination accuracy is improved, but the processing load and complexity increase
Solution Approach 1:
The patent extracts the essential feature for fall detection by using only a single threshold comparison on acceleration magnitude, removing the complex multi-threshold differentiation approach. This simplifies the processing while maintaining the ability to distinguish fall states from normal operation.
Solution Approach 2:
The patent changes the detection parameter from using differential signals with multiple thresholds to using raw acceleration magnitude with a single threshold. This parameter transformation reduces computational complexity while preserving detection accuracy.
2Difficulty of detecting and measuring
If acceleration sensor is used to detect fall, then the detection capability is improved, but the susceptibility to centrifugal force and simple shock increases
Solution Approach 1:
Instead of analyzing the differential signal to detect falls, the patent inverts the approach by directly monitoring the magnitude of acceleration itself. When a fall occurs, the acceleration magnitude drops below gravity level, creating a detectable signal without being affected by centrifugal forces or simple shocks.
Solution Approach 2:
The patent converts the constant gravity acceleration into a beneficial reference level. By comparing acceleration magnitude against this inherent reference, the system can distinguish true falls from false triggers caused by centrifugal forces or simple shocks, as these produce different acceleration patterns.
3Measurement precision
If offset adjustment is performed on acceleration sensor, then the measurement accuracy is improved, but the processing time increases
Solution Approach 1:
The patent performs offset adjustment preliminarily during device initialization or calibration phases, storing the corrected values for later use. This eliminates the need for real-time offset calculations during fall detection, reducing processing time while maintaining measurement accuracy.
4Speed
If fall prediction is implemented, then the response time is improved, but the false detection rate increases
Solution Approach 1:
The patent implements a feedback mechanism where the single-threshold detection result is continuously monitored and validated against subsequent acceleration readings. This feedback loop confirms true falls while filtering out false predictions, maintaining both fast response and high reliability.
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 reduces processing load, enables accurate determination of fall start and prediction, and effectively distinguishes between fall and simple shock, improving the reliability of fall detection in devices like magnetic disk drives and portable electronics.
Implementation Method 1
acceleration detection means that obtains accelerations in three orthogonal axis directions
Data Source
AI summary
A fall detection device that is allowed to reduce the processing load put when making a determination using software, to reliably determine the start of a fall, and to make a fall prediction as necessary, and a magnetic disk drive and a portable electronic apparatus that each include the fall detection device are configured. Accelerations are obtained in three orthogonal axis directions (ax, ay, az), and an evaluation value is obtained with respect to each of the accelerations (ax, ay, az) on the basis of an evaluation function, by which an evaluation value is increased as the difference increases between accelerations (ax0, ay0, az0) at a steady time and accelerations (ax, ay, az) at a fall determination time, and whether a fall has started is determined on the basis of whether this evaluation value exceeds a predetermined value.