Limb Length Estimation via Arc Trajectory Radius Calculation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for accurately measuring limb length require complex calibration motions, making it difficult to measure without specialized knowledge or strict adherence to specific bending and positioning protocols.
Innovation Solution
A measurement device that calculates the length and central angle of an arc trajectory using sensor data from a simple motion, estimating the limb length by determining the radius of the arc based on these calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a strict calibration motion with series of bending motions is performed, then measurement precision is improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The patent extracts the essential measurement function from the complex calibration motion sequence. Instead of requiring the complete series of bending motions (calibration motion), the invention uses only the necessary arc trajectory data obtained during a simpler motion to calculate limb length, thereby maintaining measurement precision while reducing operational complexity
Solution Approach 2:
The patent inverts the traditional calibration approach by not requiring the user to perform complex calibration motions to establish reference data. Instead, the system calculates limb length directly from the arc trajectory parameters (radius, central angle) obtained during the measurement motion itself, eliminating the need for separate calibration procedures
2Measurement precision
If a strict calibration motion with series of bending motions is performed, then measurement precision is improved, but device complexity deteriorates
Solution Approach 1:
The patent extracts only the essential arc trajectory calculation functionality from the complex calibration motion sequence. The system uses the radius and central angle of the arc trajectory directly obtained during measurement to calculate limb length, eliminating the need for complex calibration procedures and reducing overall system complexity
Solution Approach 2:
The patent changes the measurement approach from using complex motion sequences to using simple arc trajectory parameters (radius and central angle). This parameter transformation allows the system to achieve measurement precision without requiring complex calibration motions, thereby reducing device and operational complexity
3Measurement precision
If specialized knowledge and strict calibration protocols are required, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent enables the measurement system to perform accurate limb length measurement autonomously without requiring specialized knowledge or strict calibration protocols from the user. The system automatically calculates limb length from the arc trajectory data obtained during simple motion, making the measurement process accessible to ordinary users while maintaining precision
Data Source
AI summary
A measurement device that includes a calculation unit that calculates, using sensor data measured by a sensor according to a measurement motion regarding a limb of a user, the sensor being attached to the user at a predetermined attachment site, a length and a central angle of an arc related to a trajectory of the sensor in a period of the measurement motion, and an estimation unit that estimates a radius of the arc calculated using the calculated length and the calculated central angle of the arc as a length of the limb of the user.