visual3d:documentation:kinematics_and_kinetics:external_forces:force_representation
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| visual3d:documentation:kinematics_and_kinetics:external_forces:force_representation [2024/06/17 18:16] – created sgranger | visual3d:documentation:kinematics_and_kinetics:external_forces:force_representation [2024/07/17 15:45] (current) – created sgranger | ||
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| + | ====== Force Representation ====== | ||
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| In order to perform an inverse dynamics analysis it is necessary to have 9 variables to define the reaction force completely (e.g. Force Vector (Fx, Fy, Fz), Center of Pressure (CPx, CPy, CPz), and Free Moments (Tx, Ty, Tz)). Most force platforms measure only 6 signals of the 9 required. This is not a limitation in gait laboratories because for studies of walking it is possible to make valid assumptions about 3 of the signals, thus providing all of the signals necessary for an Inverse Dynamics analysis of walking on the force platform (The assumptions are: CPz=top surface of the force platform, and Tx=Ty=0). | In order to perform an inverse dynamics analysis it is necessary to have 9 variables to define the reaction force completely (e.g. Force Vector (Fx, Fy, Fz), Center of Pressure (CPx, CPy, CPz), and Free Moments (Tx, Ty, Tz)). Most force platforms measure only 6 signals of the 9 required. This is not a limitation in gait laboratories because for studies of walking it is possible to make valid assumptions about 3 of the signals, thus providing all of the signals necessary for an Inverse Dynamics analysis of walking on the force platform (The assumptions are: CPz=top surface of the force platform, and Tx=Ty=0). | ||
| - | [[ForceSchematic.gif]] | + | {{:ForceSchematic.gif}} |
| Note: The assumption that the two free moments are equal to zero are not valid for handles instrumented with 6 degree of freedom load cells, wheel chair rims, or any circumstance in which the person can wrench the force platform, or pull up on it. | Note: The assumption that the two free moments are equal to zero are not valid for handles instrumented with 6 degree of freedom load cells, wheel chair rims, or any circumstance in which the person can wrench the force platform, or pull up on it. | ||
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visual3d/documentation/kinematics_and_kinetics/external_forces/force_representation.1718648184.txt.gz · Last modified: 2024/06/17 18:16 by sgranger