====== FP Type 5 ======

A Type 5 Force platform names its four corners A, B, C, and D.

{{:FP_Type_5.png}}

==== Channels and CalMatrix ====
A Type 5 force platform records 8 ANALOG channels containing the following information:
<code>
[Original Analog] = [CZ, DZ, AZ, BZ, YAC, XDC, XAB, YBD]
</code>

The 6x8 CalMatrix for a Type 5 force platform is shown in the figure below:

{{:FP_Type_5_CalMatrix.png}}

The entries in the CalMatrix are referred to below according their row and column, so entry Src is the entry located in the rth row and cth column of the CalMatrix.

**Note:** Visual3D expects units consistent with the .c3d file. It is therefore important that the CalMatrix is also consistent with those units.

==== Calculating the Force Signals ====

Calculating the desired force signals in the force platform's coordinate system consists of the following steps:

  - Compute baselines by averaging the analog signals for the specified [[Visual3D:Documentation:Pipeline:Force_Commands:FP_ZERO|FP_ZERO]] frames
  - Subtract each channel's baseline from its recorded signal
  - Calculate the the Ground Reaction Force
  - Apply a threshold
  - Transform the signals into the [[visual3d:documentation:definitions:laboratory_coordinate_system|Laboratory Coordinate System]]

=== Force Vector ===

The Force vector for a Type 5 force platform is calculated (in units of inches) as follows:
<code>
Force[X]= (Cz*S11)+(Dz*S12)+(Az*S13)+(Bz*S14)+(YAC*S15)+(XDC*S16)+(XAB*S17)+(YBD*S18)
Force[Y]= (Cz*S21)+(Dz*S22)+(Az*S23)+(Bz*S24)+(YAC*S25)+(XDC*S26)+(XAB*S27)+(YBD*S28)
Force[Z]= (Cz*S31)+(Dz*S32)+(Az*S33)+(Bz*S34)+(YAC*S35)+(XDC*S36)+(XAB*S37)+(YBD*S38)
</code>

The following moments of force are in Inch-pounds.
<code>
M[X]= (Cz*S41)+(Dz*S42)+(Az*S43)+(Bz*S44)+(YAC*S45)+(XDC*S46)+(XAB*S47)+(YBD*S48)
M[Y]= (Cz*S51)+(Dz*S52)+(Az*S53)+(Bz*S54)+(YAC*S55)+(XDC*S56)+(XAB*S57)+(YBD*S58)
M[Z]= (Cz*S61)+(Dz*S62)+(Az*S63)+(Bz*S64)+(YAC*S65)+(XDC*S66)+(XAB*S67)+(YBD*S68)
</code>

For Type 5 force platforms the LengthConversion term (the point units conversion to meters) is 0.0254 from inches and the force conversion from Lbs to N is 4.448.

==== Compute Centre of Pressure ====

The COFP signal for a Type 5 force platform is calculated as follows:
<code>
COP[X]= (ORIGIN[Z]*Force[X] - My) / Force[Z]
COP[Y]= (Mx + ORIGIN[Z]*Force[Y]) / Force[Z]
COP[Z]= ORIGIN[Z]
</code>

==== Compute Free Moment ====

The FreeMoment signal for a Type 5 force platform is calculated as follows:
<code>
FreeMoment[X]= 0
FreeMoment[Y]= 0
FreeMoment[Z]= Mz - ( COP[X]*Force[Y] - COP[Y]*Force[Z] )
</code>

=== Transforming Signals into the Laboratory Coordinate System ===

The transformation is defined by the location of the force platform corners, and is common to all force platforms