Angled Single-Axis Load Cells for 3D Ground Reaction Force Measurement
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Solution Overview
Problem
Existing ground reaction force plates are either expensive and complex, limiting their scalability, or provide limited information by only measuring force in the vertical direction.
Innovation Solution
A ground reaction force plate apparatus with a plurality of single-axis load cells arranged at angles to measure three-dimensional force vectors, combined with a data collection controller and machine learning processing to evaluate the three-dimensional ground reaction force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiaxial load cells with strain gauges are used to measure three-dimensional ground reaction forces, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent divides the complex three-dimensional force measurement task into multiple simpler uniaxial load cell measurements. By segmenting the measurement function across multiple single-axis sensors arranged at specific angles, the system achieves 3D force capability without requiring complex multiaxial load cells at each position.
Solution Approach 2:
The patent combines measurements from multiple uniaxial load cells to achieve three-dimensional force measurement capability. By merging the data from several simple sensors arranged geometrically, the system integrates their outputs to reconstruct full 3D force vectors, replacing the need for individual complex multiaxial sensors.
2Measurement precision
If multiple multiaxial load cells are arranged to achieve desired force plate performance, then measurement precision is improved, but cost increases significantly
Solution Approach 1:
The patent replaces expensive multiaxial load cells with cheaper uniaxial load cells. By using multiple inexpensive single-axis sensors instead of fewer costly multi-axis sensors, the system achieves comparable measurement capability at reduced cost, making the technology economically viable for scalable applications.
Solution Approach 2:
The uniaxial load cells are designed to serve multiple functions through their angular arrangement. Each simple sensor contributes to multiple force component measurements when combined with others, maximizing the utility of each inexpensive component and reducing the total cost of the measurement system.
3Device complexity
If four uniaxial load cells are arranged vertically at corners to reduce cost, then device complexity is reduced, but measurement precision is worsened due to limited vertical direction measurement
Solution Approach 1:
The patent introduces asymmetry in the load cell arrangement by positioning uniaxial load cells at specific non-vertical angles rather than symmetrically vertically. This asymmetric angular configuration enables the simple uniaxial sensors to capture three-dimensional force information, breaking the limitation of vertical-only measurement while maintaining system simplicity.
Solution Approach 2:
The patent transitions from one-dimensional vertical measurement to three-dimensional force measurement by changing the spatial arrangement of the load cells. By orienting uniaxial sensors in three-dimensional space at specific angles, the system adds dimensional measurement capability without requiring complex multiaxial sensors, achieving 3D measurement through geometric configuration rather than sensor complexity.
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
The system provides accurate, robust, and inexpensive measurement of three-dimensional ground reaction forces, allowing for scalable applications and detailed biomechanical analysis.
Implementation Method 1
Multiaxial load cells use strain gauges that rely on the use of the material properties (such as stress and strain) to determine the force
Data Source
AI summary
A ground reaction force plate apparatus and measuring system are provided. The apparatus includes a plate for receiving a force to be measured as applied by a subject to the plate and a plurality of load cells in an arrangement supporting the plate, each load cell being a single-axis sensor with the axis provided at an angle to a plane of the plate and oriented towards a centre of the plate. The load cells are configured to measure data relating to a force vector at the angled single-axis sensor when the subject applies a force to the plate. A data collection controller is provided for logging time series measurements of the load cells over a time in which the subject applies a force to the plate. The system applies machine learning processing to output the load cell measurements as a three-dimensional ground reaction force on the plate by a subject.