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visual3d:documentation:kinematics_and_kinetics:external_forces:force_structures [2024/06/18 13:28] – sgrangervisual3d:documentation:kinematics_and_kinetics:external_forces:force_structures [2024/07/17 15:45] (current) – created sgranger
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 +====== Force Structures ======
 +
 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.
  
 Our original implementation treated these "entities" as different FORCE_PLATFORM types, but this decision caused problems with other manufacturers that didn't recognize the new types. After consideration we determined that the introduction of a new C3D parameter group for FORCE_STRUCTURES was a more general solution because it didn't affect the force platform parameters. Our original implementation treated these "entities" as different FORCE_PLATFORM types, but this decision caused problems with other manufacturers that didn't recognize the new types. After consideration we determined that the introduction of a new C3D parameter group for FORCE_STRUCTURES was a more general solution because it didn't affect the force platform parameters.
  
-===== Theory =====+==== Theory ====
  
 External forces require the specification of 9 components External forces require the specification of 9 components
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 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).
  
-{{Force_Structure.jpg}}+{{:Force_Structure.jpg}}
  
 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.
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 A consequence of this is that it is important to filter the ANALOG signals rather than filtering the FORCE, COP, and FREEMOMENT signals. Remember to select the Settings Option to use Processed Analog signals for computing the force vectors. A consequence of this is that it is important to filter the ANALOG signals rather than filtering the FORCE, COP, and FREEMOMENT signals. Remember to select the Settings Option to use Processed Analog signals for computing the force vectors.
  
-===== Pipeline Command =====+==== Pipeline Command ====
  
 The edit dialog invoked either by selected Modify Force Structures under the Force Menu or by the Pipeline command [[Visual3D:Documentation:Pipeline:Force_Commands:Modify_Force_Structure_Parameters|Modify_Force_Structure_Parameters]] as follows. The edit dialog invoked either by selected Modify Force Structures under the Force Menu or by the Pipeline command [[Visual3D:Documentation:Pipeline:Force_Commands:Modify_Force_Structure_Parameters|Modify_Force_Structure_Parameters]] as follows.
  
-{{AMTI_steps2.jpg}}+{{:AMTI_steps2.jpg}}
  
 Each structure is defined as a plane (or polygon) defined by four corners. Each structure is defined as a plane (or polygon) defined by four corners.
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 If the force structure is not a single plane, but multiple planes, each surface should be defined in the Force Structure Surfaces list box If the force structure is not a single plane, but multiple planes, each surface should be defined in the Force Structure Surfaces list box
  
-==== Modify_Force_Structure_Parameters ====+=== Modify_Force_Structure_Parameters ===
  
 **Modify_Force_Structure_Parameters** **Modify_Force_Structure_Parameters**
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 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.
  
-{{ForceStructureDlg1x2.jpg}}+{{:ForceStructureDlg1x2.jpg}}
  
 \\ \\
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 See also [[Visual3D:Documentation:Pipeline:Force_Commands:Modify_Force_Structure_Parameters|Modify_Force_Structure_Parameters]] See also [[Visual3D:Documentation:Pipeline:Force_Commands:Modify_Force_Structure_Parameters|Modify_Force_Structure_Parameters]]
  
-===== Structure consisting of 1 force platform and 2 surfaces =====+==== Structure consisting of 1 force platform and 2 surfaces ====
  
 The following dialog creates a force structure that is comprised of 2 surfaces attached to the same platform. The following dialog creates a force structure that is comprised of 2 surfaces attached to the same platform.
  
-{{AMTI_steps3.jpg}}+{{:AMTI_steps3.jpg}}
  
 Visual3D creates two surfaces, so it creates two force signals. Visual3D creates two surfaces, so it creates two force signals.
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 **COP_1**, **FORCE_1** and **FREEMOMENT_1** **COP_1**, **FORCE_1** and **FREEMOMENT_1**
-{{ForceStructureDataTree.jpg}}+{{:ForceStructureDataTree.jpg}}
  
 In the following figure the right foot makes contact with 2 steps In the following figure the right foot makes contact with 2 steps
  
-{{ForceStructureGraph.jpg}}+{{:ForceStructureGraph.jpg}}
  
-===== Structure consisting of 2 force platforms and 1 surface =====+==== Structure consisting of 2 force platforms and 1 surface ====
  
 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.
  
-[[index.php?title=Special:Upload&wpDestFile=ForceStructureDig1x2.jpg|File:ForceStructureDig1x2.jpg]]+{{:ForceStructureDig1x2.jpg}}
  
 The user has the option to treat each force independently, which means that each force FP1 and FP2 could be assigned to the same segment. The user has the option to treat each force independently, which means that each force FP1 and FP2 could be assigned to the same segment.
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   * solve the following 6 equations for the resultant force and moment   * solve the following 6 equations for the resultant force and moment
  
-{{ForceStructureEqn1.jpg}} solve for the 3 components of the force+{{:ForceStructureEqn1.jpg}} solve for the 3 components of the force
  
-{{ForceStructureEqn2.jpg}} assume the resultant center of pressure lies on the output surface, and that the Free Moment is computed only about the normal to the surface+{{:ForceStructureEqn2.jpg}} assume the resultant center of pressure lies on the output surface, and that the Free Moment is computed only about the normal to the surface
  
   * solve for the x and y component of the COP on the surface   * solve for the x and y component of the COP on the surface
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 **FS1_1** **FS1_1**
-===== Curved Surfaces =====+==== Curved Surfaces ====
  
 If the force structure is actually a continuous curved surface, it must be approximated by a series of contiguous surfaces. If the force structure is actually a continuous curved surface, it must be approximated by a series of contiguous surfaces.
visual3d/documentation/kinematics_and_kinetics/external_forces/force_structures.1718717297.txt.gz · Last modified: 2024/06/18 13:28 by sgranger