ASTM F3109-23
(Practice)Standard Practice for Verification of Multi-Axis Force Measuring Platforms
Standard Practice for Verification of Multi-Axis Force Measuring Platforms
SIGNIFICANCE AND USE
5.1 Multi-axis force measuring platforms are used to measure the ground reaction forces produced at the interface between a subject's foot or shoe and the supporting ground surface. These platforms are used in various settings ranging from research laboratories to healthcare facilities. The use of force platforms has become particularly important in gait analysis where clinical evaluations have become a billable clinical service.
5.2 Of particular importance is the application of force platforms in the treatment of cerebral palsy (CP) (1, 2).3 An estimated 8000 to 10 000 infants born each year will develop CP (3) while today’s affected population is over 764 000 patients (4). Quantitative gait analysis, using force platforms and motion capture systems, provides a valuable tool in evaluating the pathomechanics of children with CP. This type of mechanical evaluation provides a quantitative basis for treating neuromuscular conditions. In other words, surgical decisions are in part guided by information gained from the use of force platform measurements (5, 6).
5.3 Another application is treatment of spina bifida. According to the Gait and Clinical Movement Analysis Society (GCMAS) (7), an instrumented gait analysis is the standard of expert care for children with gait abnormalities secondary to spina bifida. The main objective of diagnostic gait analysis is to define the pathological consequences of neural tube defects as they relate to gait. The use of instrumented gait analysis allows physicians to determine which surgical or non-surgical interventions would provide the best outcome.
5.4 More recently, force platforms have been used for pre- and post-surgical evaluation of TKA (total knee arthroplasty) and THA (total hip arthroplasty) patients. Such data provides an objective measure of the mechanical outcome of the surgical procedure.
5.5 In addition to the clinical applications there are numerous medical and human performance research activities which r...
SCOPE
1.1 This standard recommends practices for performance verification of multi-axis force platforms commonly used for measuring ground reaction forces during gait, balance, and other activities.
1.1.1 This standard provides a method to quantify the relationship between applied input force and force platform output signals across the manufacturer’s defined spatial working surface and specified force operating range.
1.1.2 This standard provides definitions of the critical parameters necessary to quantify the behavior of multi-axis force measuring platforms and the methods to measure the parameters.
1.1.3 This standard presents methods for the quantification of spatially distributed errors and absolute measuring performance of the force platform at discrete spatial intervals and discrete force levels on the working surface of the platform.
1.1.4 This standard further defines certain important derived parameters, notably COP (center of pressure) and methods to quantify and report the measuring performance of such derived parameters at spatial intervals and force levels across the working range of the force platform.
1.1.5 This standard defines the requirements for a report suitable to characterize the force platform’s performance and provide traceable documentation to be distributed by the manufacturer or calibration facility to the users of such platforms.
1.1.6 Dynamic characteristics and applications where the force platform is incorporated in other equipment, such as instrumented treadmills and stairs, are beyond the scope of this standard.
1.1.7 This standard is written for purposes of multi-axis force platform verification. However, the methods and procedures are applicable to calibration of force platforms by manufacturers.
1.2 The values stated in SI units are to be regarded as the standard. Other metric and inch-pound values are regarded as equivalent when required.
1.3 This standard does n...
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F3109 − 23
Standard Practice for
1
Verification of Multi-Axis Force Measuring Platforms
This standard is issued under the fixed designation F3109; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 1.2 The values stated in SI units are to be regarded as the
standard. Other metric and inch-pound values are regarded as
1.1 This standard recommends practices for performance
equivalent when required.
verification of multi-axis force platforms commonly used for
1.3 This standard does not purport to address all of the
measuring ground reaction forces during gait, balance, and
safety concerns, if any, associated with its use. It is the
other activities.
responsibility of the user of this standard to establish appro-
1.1.1 This standard provides a method to quantify the
priate safety, health, and environmental practices and deter-
relationship between applied input force and force platform
mine the applicability of regulatory limitations prior to use.
output signals across the manufacturer’s defined spatial work-
1.4 This international standard was developed in accor-
ing surface and specified force operating range.
dance with internationally recognized principles on standard-
1.1.2 This standard provides definitions of the critical pa-
ization established in the Decision on Principles for the
rameters necessary to quantify the behavior of multi-axis force
Development of International Standards, Guides and Recom-
measuring platforms and the methods to measure the param-
mendations issued by the World Trade Organization Technical
eters.
Barriers to Trade (TBT) Committee.
1.1.3 This standard presents methods for the quantification
2. Referenced Documents
of spatially distributed errors and absolute measuring perfor-
2
mance of the force platform at discrete spatial intervals and
2.1 ASTM Standards:
discrete force levels on the working surface of the platform.
E4 Practices for Force Calibration and Verification of Test-
1.1.4 This standard further defines certain important derived ing Machines
parameters, notably COP (center of pressure) and methods to
E74 Practices for Calibration and Verification for Force-
quantify and report the measuring performance of such derived Measuring Instruments
parameters at spatial intervals and force levels across the
3. Terminology
working range of the force platform.
3.1 Definitions of Terms Specific to This Standard:
1.1.5 This standard defines the requirements for a report
suitable to characterize the force platform’s performance and 3.1.1 center of pressure (COP), n—the spatial point on the
surface of a force platform at which a single equivalent force
provide traceable documentation to be distributed by the
manufacturer or calibration facility to the users of such has the same static effect as the sum of the distributed forces
and the distributed moments acting on the system.
platforms.
1.1.6 Dynamic characteristics and applications where the
3.1.2 COP error, n—difference between the COP x-y posi-
force platform is incorporated in other equipment, such as tion reported by the force platform (or calculated from the
force platform outputs) and the actual x-y location of the
instrumented treadmills and stairs, are beyond the scope of this
standard. applied Fz verification force.
1.1.7 This standard is written for purposes of multi-axis 3.1.3 crosstalk or crosstalk error, n—response of an output
force platform verification. However, the methods and proce-
channel corresponding to an unloaded axis when a force or a
dures are applicable to calibration of force platforms by moment is applied to a different axis.
manufacturers.
3.1.4 force platform origin, n—the position on the force
platform, specified by the manufacturer, where x, y, and z = 0.
The origin serves as a reference position for the COP x and
1
This practice is under the jurisdiction of ASTM Committee F04 on Medical and
Surgical Materials and Devices and is the direct responsibility of Subcommittee
2
F04.15 on Material Test Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved March 1, 2023. Published March 2023. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2016. Last previous edition approved in 2022 as F3109 – 22. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/F3109-23. the ASTM website.
*A Summary of Change
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: F3109 − 22 F3109 − 23
Standard Practice for
1
Verification of Multi-Axis Force Measuring Platforms
This standard is issued under the fixed designation F3109; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This standard recommends practices for performance verification of multi-axis force platforms commonly used for measuring
ground reaction forces during gait, balance, and other activities.
1.1.1 This standard provides a method to quantify the relationship between applied input force and force platform output signals
across the manufacturer’s defined spatial working surface and specified force operating range.
1.1.2 This standard provides definitions of the critical parameters necessary to quantify the behavior of multi-axis force measuring
platforms and the methods to measure the parameters.
1.1.3 This standard presents methods for the quantification of spatially distributed errors and absolute measuring performance of
the force platform at discrete spatial intervals and discrete force levels on the working surface of the platform.
1.1.4 This standard further defines certain important derived parameters, notably COP (center of pressure) and methods to quantify
and report the measuring performance of such derived parameters at spatial intervals and force levels across the working range of
the force platform.
1.1.5 This standard defines the requirements for a report suitable to characterize the force platform’s performance and provide
traceable documentation to be distributed by the manufacturer or calibration facility to the users of such platforms.
1.1.6 Dynamic characteristics and applications where the force platform is incorporated in other equipment, such as instrumented
treadmills and stairs, are beyond the scope of this standard.
1.1.7 This standard is written for purposes of multi-axis force platform verification. However, the methods and procedures are
applicable to calibration of force platforms by manufacturers.
1.2 The values stated in SI units are to be regarded as the standard. Other metric and inch-pound values are regarded as equivalent
when required.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
1
This practice is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility of Subcommittee F04.15
on Material Test Methods.
Current edition approved Sept. 1, 2022March 1, 2023. Published October 2022March 2023. Originally approved in 2016. Last previous edition approved in 20162022 as
F3109 – 16.F3109 – 22. DOI: 10.1520/F3109-22.10.1520/F3109-23.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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F3109 − 23
2. Referenced Documents
2
2.1 ASTM Standards:
E4 Practices for Force Calibration and Verification of Testing Machines
E74 Practices for Calibration and Verification for Force-Measuring Instruments
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 center of pressure (COP), n—the spatial point on the surface of a force platform at which a single equivalent force has the
same static effect as the sum of the distributed forces and the distributed moments acting on the system.
3.1.2 COP error, n—difference between the COP x-y position reported by the force platform (or calculated from the force platform
outputs) and the actual x-y location of the applied Fz verification force.
3.1.3 crosstalk or crosstalk error, n—response of an output channel corresponding to an unloaded axis when a force or a moment
is applied to a different axis.
3.1.4 force platform origin,
...
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