Force Waveform Analysis for Weight Measurement During Motion
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Solution Overview
Problem
Conventional methods for measuring the weight of persons or animals while walking are complex and prone to errors due to the need for accurate placement of center of mass acceleration sensors and Inertial Motion Unit (IMU) sensors, which are susceptible to measurement errors from repeated foot impacts.
Innovation Solution
A method that uses force sensors to measure the force exerted between the subject's feet and the surface, processing these measurements to determine peak, valley, and range values to estimate weight without additional center of mass acceleration sensors or IMU sensors, leveraging a relationship between force range and center of mass acceleration to calculate weight accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional methods use CoM acceleration sensors and IMU sensors to measure weight while walking, then weight measurement can be performed during motion, but the device complexity increases and measurement precision deteriorates due to sensor placement requirements and susceptibility to foot impact errors
Solution Approach 1:
The patent extracts the center of mass acceleration measurement function from separate CoM acceleration sensors and IMU sensors, and instead derives it mathematically from force sensor measurements. By removing the need for additional acceleration sensors and using only force sensors, the device complexity is reduced while maintaining the capability to measure weight during motion.
Solution Approach 2:
The force sensors are made multi-functional by using them not only to measure vertical forces but also to derive center of mass acceleration information through mathematical processing of force waveforms. This eliminates the need for separate acceleration sensors, reducing device complexity while maintaining measurement capabilities.
2Ease of operation
If CoM acceleration sensors and IMU sensors are used to determine best point of measurement, then weight can be measured during walking, but measurement precision deteriorates due to repeated foot impact on IMU sensors
Solution Approach 1:
The patent converts the harmful effect of foot impacts on IMU sensors into a beneficial approach by eliminating IMU sensors entirely and using only force sensors that are naturally suited for measuring impact forces. The force sensors' ability to withstand and measure impact forces becomes the advantage, improving measurement precision during walking.
Solution Approach 2:
The patent replaces expensive and sensitive IMU sensors with more robust force sensors that are better suited for the application. Force sensors are more tolerant of the harsh conditions during walking and do not suffer from the same measurement errors as IMU sensors under repeated impact.
3Device complexity
If force sensors alone are used to measure weight during motion, then device complexity is reduced, but measurement precision was previously insufficient without additional acceleration sensors
Solution Approach 1:
The patent introduces mathematical processing of force waveforms as an intermediary mechanism that bridges the gap between simple force sensor measurements and accurate weight estimation. By analyzing peak and valley levels of force waveforms and calculating force ranges, the system derives center of mass acceleration information without needing separate acceleration sensors, thus maintaining measurement precision while reducing device complexity.
Solution Approach 2:
The patent changes the approach from directly measuring acceleration with sensors to deriving acceleration parameters from force measurements. By processing force waveform parameters (peak levels, valley levels, force ranges) mathematically, the system achieves accurate weight estimation using only force sensors, resolving the contradiction between device simplicity and measurement accuracy.
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 reduces complexity and maintains high accuracy in weight measurement while walking, eliminating the need for additional sensors and improving measurement reliability.
Implementation Method 1
one or more force sensors are attached to the subject such that the force sensors measure a force exerted between each foot of the subject and a surface on which the subject is positioned
Data Source
AI summary
A method for estimating the weight of a subject while moving includes attaching one or more force sensors to the subject such that the force sensors measure a force exerted between each foot of the subject and a surface on which the subject is positioned, monitoring the one or more force sensors while the subject is moving to obtain a moving force measurement, processing the moving force measurement to determine a peak level of the moving force, a valley level of the moving force measurement, and a force range of the moving force measurement, determining an acceleration of center of mass of the subject from the force range, and estimating the weight of the subject while moving from the valley level and the acceleration of center of mass.