Activity State Analysis Device Transient Error Correction
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Solution Overview
Problem
Conventional techniques for determining the activity state of a person using acceleration sensors often result in erroneous determinations, particularly when the person transitions between standing and lying positions, leading to inaccuracies in measuring continuation times of activity states, which is problematic for lifestyle investigations and rehabilitation where prolonged states are critical.
Innovation Solution
An activity state analysis device and method that includes a measurement unit, tilt calculation unit, posture determination unit, body motion calculation unit, activity state determination unit, activity state correction unit, and time correction unit, which measure and analyze accelerations to accurately distinguish between rising and lying states by considering both posture and body motion, and corrects for transient state transitions using a predetermined time threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional acceleration sensor techniques are used to determine posture, then the device complexity is low, but the measurement precision deteriorates due to erroneous determination during transient movements
Solution Approach 1:
The system segments the activity determination into multiple independent components: posture determination unit analyzes tilt angle, body motion determination unit analyzes acceleration magnitude, and activity state determination unit integrates both. This segmentation allows each component to focus on specific aspects, improving overall measurement precision without requiring a complete system redesign
Solution Approach 2:
The system performs preliminary determination of posture and body motion separately before final activity state determination. By pre-processing the acceleration data into posture and motion components, the system establishes a foundation for more accurate activity state classification, reducing errors from transient movements
2Reliability
If transient state transitions are included in activity state measurement, then the productivity of data collection is high, but the reliability deteriorates due to transient errors
Solution Approach 1:
The system requires continuous satisfaction of both posture and body motion conditions for a sustained period to confirm an activity state transition. This continuity requirement filters out transient errors while maintaining reliable data collection, as genuine activity changes naturally satisfy the conditions continuously rather than momentarily
Solution Approach 2:
The system uses feedback from both posture determination and body motion determination to validate activity state transitions. The activity state determination unit continuously monitors both inputs and only confirms transitions when both conditions are satisfied, creating a feedback mechanism that eliminates transient errors while preserving true activity data
3Measurement precision
If only posture information is used for activity state determination, then the ease of operation is high, but the measurement precision deteriorates during transitional movements
Solution Approach 1:
The system segments acceleration data analysis into two distinct tasks: posture determination (tilt angle calculation) and body motion determination (acceleration magnitude analysis). This segmentation allows each processing unit to specialize, improving precision during transitions while keeping individual processing steps relatively simple and manageable
Data Source
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AI summary
A measurement unit (101) is attached to a measurement target person and measures an acceleration. A body motion calculation unit (104) obtains the magnitude of a body motion of the measurement target person based on the acceleration measured by the measurement unit (101). An activity state determination unit (105) time-serially obtains an activity state representing whether the measurement target person is in a first state (rising state) or a second state (lying state), based on a posture decided by a posture decision unit (103) and the magnitude of the body motion calculated by the body motion calculation unit (104). If the activity state after the activity state has transitioned continues for a predetermined time defined in advance, an activity state correction unit (106) determines that the transition of the activity state obtained by the activity state determination unit (105) has been done. A time correction unit (107) returns the transition time of the activity state determined by the activity state correction unit (106) by the predetermined time.