Force Measurement System Using Global Calibration Matrix
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Solution Overview
Problem
Conventional load transducers face limitations in accurately measuring forces and moments due to issues like crosstalk between channels, sensitivity to ambient temperature, and variability in measurement accuracy based on load position, requiring a more versatile and accurate force measurement system that can correct for these factors.
Innovation Solution
A force measurement system with a data processing device that utilizes a global calibration matrix and local calibration information to determine the load location and compute output forces or moments, divided into multiple load regions to improve accuracy and reduce errors, especially near the periphery or on non-standard shaped force plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional load transducers are used to measure forces and moments, then the basic measurement function is achieved, but measurement accuracy deteriorates due to crosstalk between channels and temperature sensitivity
Solution Approach 1:
The patent implements feedback by using the measured force and moment components along with the determined load location to compute correction factors that account for crosstalk and temperature effects. These correction factors are then applied to improve the accuracy of the measurement readings, creating a closed-loop system that continuously refines measurement precision based on actual operating conditions.
Solution Approach 2:
The patent changes the parameters used for measurement by determining the load location on the force plate and using this positional information to select appropriate calibration data and correction factors. Instead of using fixed calibration values, the system dynamically adjusts measurement parameters based on where the load is applied, thereby compensating for crosstalk and temperature effects that vary with load position.
2Adaptability or versatility
If conventional load transducers are used with varying force plate sizes, then different custom transducers must be fabricated for each size, but this increases material costs and device complexity
Solution Approach 1:
The patent achieves universality by designing a single load transducer configuration that can be used with force plates of various sizes and shapes. Instead of creating custom transducers for each force plate specification, the system uses one standardized transducer design with a universal calibration approach that adapts to different force plate geometries through software-based calibration matrices and load location determination.
Solution Approach 2:
The patent applies preliminary action by pre-computing calibration matrices for different load regions on the force plate before actual use. During calibration, the system determines the load location and selects the appropriate pre-computed calibration data, eliminating the need for real-time complex calculations and allowing the same transducer design to work across multiple force plate configurations.
3Area of stationary object
If conventional load transducers span the full length of force plates, then coverage is achieved, but excessive material is used increasing cost and weight
Solution Approach 1:
The patent applies segmentation by dividing the force plate surface into multiple load regions and using calibration matrices specific to each region. This allows the use of a more compact load transducer design that doesn't need to span the entire force plate length, as the segmented calibration approach compensates for position-dependent measurement variations, thereby reducing material usage while maintaining 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
The system enhances measurement accuracy by correcting for crosstalk and temperature effects, allowing for precise force determination regardless of load position, thereby improving the versatility and reliability of force measurements across various force plate sizes and shapes.
Implementation Method 1
A transducer can incorporate one or more load channels. Each load channel measures one of the load components, and is comprised of one or more strain gages mounted to one or more elastic elements that deform under the applied load. An appropriate circuitry relates the resistance change in each set of gages to the applied force or moment.
Data Source
AI summary
A force measurement system is disclosed herein. The force measurement system includes a force measurement assembly and a data processing device operatively coupled to the force measurement assembly. In one or more embodiments, the data processing device is configured to reference a stored global calibration matrix for the force measurement assembly, to determine a location of an applied load on the surface of the force measurement assembly using the stored global calibration matrix, to assign the applied load to one or more of a plurality of different load regions based upon the location of the applied load, and to compute one or more output forces or moments of the applied load using stored local calibration information for the one or more of the plurality of different load regions. A method of calibrating a force measurement system is also disclosed herein.