Directional Force Sensing Element Using Segmented Strain Gages
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Solution Overview
Problem
Measuring real-world static and dynamic loads on service members is difficult, making it impossible to quantify performance degradation and musculoskeletal injuries due to overload in the field, which hinders efficient planning and combat effectiveness and leads to increased injuries.
Innovation Solution
A directional force sensing system using a flexible leaf spring with strain gages and an analog-to-digital converter to measure both perpendicular and shear forces, integrated with a controller and additional sensors for environmental data, allowing for accurate force measurement and data processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional load sensing methods are used, then measurement simplicity is maintained, but measurement precision and capability to quantify directional forces are insufficient
Solution Approach 1:
The sensing element is divided into multiple strain gages positioned at different locations and orientations on the wave washer. Each strain gage measures force in a specific direction, and the combined readings from multiple segments enable precise determination of both magnitude and direction of applied forces.
Solution Approach 2:
The patent transitions from single-dimensional load measurement to multi-dimensional force sensing by arranging strain gages in different orientations (e.g., 0°, 45°, 90°) on the wave washer. This dimensional expansion allows the system to resolve forces in multiple directions simultaneously, providing comprehensive force vector measurement.
2Measurement precision
If strain gages are positioned to measure directional forces, then force measurement precision is improved, but device complexity increases due to multiple sensors and signal processing requirements
Solution Approach 1:
Multiple strain gage measurements are combined through signal processing algorithms that integrate readings from gages at different orientations. The controller merges these individual measurements to calculate the magnitude and direction of applied forces, reducing the complexity of having multiple separate measurement systems.
Solution Approach 2:
The system incorporates a controller that processes strain gage signals and provides feedback on force magnitude and direction. This feedback mechanism enables real-time monitoring and adjustment, allowing the system to maintain measurement accuracy while managing the complexity of multi-directional force detection.
3Adaptability or versatility
If multiple strain gages are used to detect force direction, then measurement capability is improved, but manufacturing precision requirements increase
Solution Approach 1:
Each strain gage is positioned at a specific location and orientation on the wave washer to measure force components in particular directions. The local quality of each measurement point is optimized for its specific function, with gages placed at strategic locations (e.g., radial and tangential positions) to capture different force components.
Solution Approach 2:
The wave washer structure serves multiple functions: it acts as the sensing element, the mounting substrate for strain gages, and the mechanical component that transmits forces. This multi-functionality reduces the need for separate precision positioning mechanisms, as the wave washer's inherent geometry provides the reference framework for strain gage placement.
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 quantification of forces applied to service members, improving injury prevention, equipment design, and combat effectiveness by providing detailed force data and environmental insights.
Implementation Method 1
The strain gages are affixed to the ends of the flexible arms... in response to a force applied to the leaf spring, the one or more load sensors provide a signal
Data Source
AI summary
A directional force sensor and sensing system are described. The directional force sensor includes a leaf spring and one or more load sensors disposed about the leaf spring such that in response to a force applied to the leaf spring, the one or more load sensors provide a signal. A controller is coupled to receive signals from the one or more directional force sensors and determines characteristics of forces applied to the directional force sensors.