visual3d:documentation:kinematics_and_kinetics:external_forces:force_structures
Differences
This shows you the differences between two versions of the page.
Both sides previous revisionPrevious revisionNext revision | Previous revision | ||
visual3d:documentation:kinematics_and_kinetics:external_forces:force_structures [2024/07/17 15:10] – sgranger | visual3d:documentation:kinematics_and_kinetics:external_forces:force_structures [2025/09/12 19:04] (current) – [Structure consisting of 2 force platforms and 1 surface] wikisysop | ||
---|---|---|---|
Line 1: | Line 1: | ||
- | ====== | + | ====== |
Force Structures were conceived as a mechanism for combining force platform data (e.g. treating several contiguous platforms as a single platform), and for accommodating structures that are attached to the force platform as a super-structure such as the stairs manufactured by AMTI. | Force Structures were conceived as a mechanism for combining force platform data (e.g. treating several contiguous platforms as a single platform), and for accommodating structures that are attached to the force platform as a super-structure such as the stairs manufactured by AMTI. | ||
Line 9: | Line 9: | ||
External forces require the specification of 9 components | External forces require the specification of 9 components | ||
- | Force= (Fx, Fy, Fz) | + | Force= (Fx, Fy, Fz)\\ |
- | Center of Pressure= (COPx, COPy, COPz) | + | Center of Pressure= (COPx, COPy, COPz)\\ |
- | Free Moment= (Tx, Ty, Tz) | + | Free Moment= (Tx, Ty, Tz)\\ |
Only 6 pieces of information, | Only 6 pieces of information, | ||
For a typical platform: | For a typical platform: | ||
- | Tx and Ty are assumed to be zero. This means that we assume that the subject is **not** pulling up on the platform. | + | Tx and Ty are assumed to be zero. This means that we assume that the subject is **not** pulling up on the platform.\\ |
- | COPz is assumed to be on the top surface of the platform. | + | COPz is assumed to be on the top surface of the platform.\\ |
For a surface (e.g. a step) placed on top of the force platform, the COP is translated along the Force Vector to the new surface. (e.g. the intersection of the force with the new surface). | For a surface (e.g. a step) placed on top of the force platform, the COP is translated along the Force Vector to the new surface. (e.g. the intersection of the force with the new surface). | ||
- | {{: | + | {{: |
This figure shows a picture of an oblique force applied to a step. This figure shows one type of force platform, but the concept applies equally to all platforms. | This figure shows a picture of an oblique force applied to a step. This figure shows one type of force platform, but the concept applies equally to all platforms. | ||
Line 48: | Line 48: | ||
=== Modify_Force_Structure_Parameters === | === Modify_Force_Structure_Parameters === | ||
- | **Modify_Force_Structure_Parameters** | + | < |
+ | Modify_Force_Structure_Parameters | ||
/USED= Number of Force Structures Used | /USED= Number of Force Structures Used | ||
! /TYPE= Not currently used | ! /TYPE= Not currently used | ||
Line 63: | Line 64: | ||
/ | / | ||
/ | / | ||
- | ! /[[Visual3D: | + | ! / |
- | **;** | + | ; |
+ | </ | ||
For example, the following force structure has one surface attached to two force platforms. | For example, the following force structure has one surface attached to two force platforms. | ||
{{: | {{: | ||
- | |||
- | \\ | ||
- | **Modify_Force_Structure_Parameters** | + | < |
+ | Modify_Force_Structure_Parameters | ||
/USED=2 | /USED=2 | ||
/TYPE=0+0 | /TYPE=0+0 | ||
Line 88: | Line 90: | ||
/ | / | ||
! / | ! / | ||
- | **;** | + | ; |
+ | </ | ||
See also [[Visual3D: | See also [[Visual3D: | ||
Line 111: | Line 114: | ||
**COP_1**, **FORCE_1** and **FREEMOMENT_1** | **COP_1**, **FORCE_1** and **FREEMOMENT_1** | ||
+ | |||
{{: | {{: | ||
Line 121: | Line 125: | ||
The following dialog creates a force structure that is comprised of 1 surface spanning 2 force platforms. | The following dialog creates a force structure that is comprised of 1 surface spanning 2 force platforms. | ||
- | {{:ForceStructureDig1x2.jpg}} | + | {{:ForceStructureDlg1x2.jpg}} |
The user has the option to treat each force independently, | The user has the option to treat each force independently, | ||
Line 142: | Line 146: | ||
* Transform these values back into the laboratory coordinate system | * Transform these values back into the laboratory coordinate system | ||
- | If there are two force platforms, the resulting signal will appear in the data tree as | + | If there are two force platforms, the resulting signal will appear in the data tree as: |
**FS1_1** and **FS1_2** | **FS1_1** and **FS1_2** | ||
+ | |||
This is interpreted as Force Structure 1 contribution from Force platform 1, and Force Structure 1contribution from force platform 2. | This is interpreted as Force Structure 1 contribution from Force platform 1, and Force Structure 1contribution from force platform 2. | ||
- | \\ | + | If, for example, instead of FP1 and FP2, there was FP1 and FP3, the signals would be: |
- | If, for example, instead of FP1 and FP2, there was FP1 and FP3, the signals would be | + | |
**FS1_1** and **FS1_3** | **FS1_1** and **FS1_3** | ||
- | \\ | + | |
- | if the option to combine all input forces is selected, there will be one resulting signal | + | If the option to combine all input forces is selected, there will be one resulting signal: |
**FS1_1** | **FS1_1** |
visual3d/documentation/kinematics_and_kinetics/external_forces/force_structures.1721229028.txt.gz · Last modified: 2024/07/17 15:10 by sgranger