Wheelchair Force Position Estimation Using Six-Axis Sensor
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Solution Overview
Problem
Conventional wheelchair measurement systems using strain gauges can measure the magnitude of force applied to the hand rim but not the precise position of force application, which is a limitation for accurate training in racing and marathon scenarios.
Innovation Solution
A driving force applied position estimation system that includes a multi-axis force detection part, posture recognition part, and applied position estimation part, utilizing translational force, moment, and rotation angle data from sensors like six-axis force sensors, acceleration sensors, and angular velocity sensors to accurately estimate the force position without requiring complex equipment or processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a strain gauge is used to measure the magnitude of force applied to the hand rim, then the force measurement capability is improved, but the ability to measure the applied position of the force deteriorates
Solution Approach 1:
The patent segments the measurement function into two distinct components: a strain gauge for measuring force magnitude and a posture recognition part (using sensors like accelerometers and gyroscopes) for detecting the rotation angle of the driving wheel. This segmentation allows each component to specialize in one aspect of measurement, thereby resolving the contradiction between force measurement capability and applied position information.
Solution Approach 2:
The patent introduces an intermediary computational process that combines the output from the strain gauge (force magnitude) and the posture recognition part (rotation angle) to estimate the applied position. This intermediary calculation acts as a mediator that synthesizes information from both sources to provide comprehensive measurement capability without requiring direct physical sensors for position detection.
2Measurement precision
If complex equipment or processes are used to accurately estimate force position, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent makes the posture recognition part multi-functional by using it for both detecting the rotation angle (which is necessary for position estimation) and potentially other monitoring functions. The same sensor system serves multiple purposes, reducing the need for additional specialized equipment and thereby maintaining measurement precision without proportionally increasing device complexity.
Solution Approach 2:
The patent changes the approach from direct physical measurement of applied position to indirect estimation through parameter calculation. By using readily available parameters (force magnitude from strain gauge and rotation angle from posture sensors) and computing the applied position through mathematical relationships, the system achieves high measurement precision without requiring complex specialized measurement equipment.
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
Enables precise estimation of the applied force position on the hand rim, allowing for improved training and performance in racing and marathon wheelchairs without the need for large processing devices or complex image processing, using commonly used and lightweight sensors.
Implementation Method 1
a multi-axis force detection part which is provided between the driving wheel and the hand rim and which detects a translational force and a moment related to application of a driving force from the hand rim side
Data Source
AI summary
The disclosure provides a driving force applied position estimation system that can accurately estimate an applied position of a driving force from an occupant. A measurement system includes a six-axis force sensor provided in a wheelchair, a rotation angle recognition part which recognizes a rotation angle of the six-axis force sensor, and a COP estimation part which estimates a COP that is the applied position of the driving force from the occupant to the wheelchair. The COP estimation part estimates the COP based on a translational force and a moment detected by the six-axis force sensor and based on the rotation angle recognized by the rotation angle recognition part to improve estimation accuracy of the COP estimation part and measurement accuracy of the measurement system.