Gait BoS CoordinateSystem

This elements extends the Gait CoordinateSystem with functionality to work with bottom of support estimations.

A <GaitBaseCoordinateSystem> element defines a specialized coordinate system with its z-Axis is the vertical axis, its x-Axis is the gait direction and its y-Axis is defined by a cross-product of these two axes and its direction from right to left side.

The content of the element is a mathematical formula which defines a point. The gait direction is defined by the vector defined by the position of this point at two different frames: start and end of a stride phase, as defined by the <GaitPhases> element. That means that the gait direction changes at every heel strike event of a given side. For frames before the first heel strike event and after the last heel strike event gait direction is extrapolated.

Attributes

Attribute Description Required 
name
 name of the element Yes
 
leftHanded
 The default orientation of the coordinate system is right-handed. If you set this attribute to "true" than the sign of the y-axis is changed to create a left-handed coordinate system.
 No 
gaitdirection
 Schön wäre es ein Attribut zu haben mit dem ich explizit die Gangrichtung hineinstecken könnte. Per Default erbt die Klasse ja
von GaitDirectionStrideBased und so brauche ich in der Regel dieses Attribut nicht.
 No 
visibleVectorLength
 Wenn das Flag isVisible="true" gesetzt wurde, kann mit diesem Attribut die Länge der Vektoren zur Darstellung der Tripoden geändert werden. Der Default-Wert ist 100. No 
ForefootLength
 
BackfootLength
 
ForefootWidth
 
ForefootAngle
 
BackfootWidth
 
RightForefootPosition
 
RightBackfootPosition
 
LeftForefootPosition
 
LeftBackfootPosition

Attributes inherited by GaitDirectionStrideBased

Attribute Default Description Required 
stride
 
RStride
 name of the stride used No 
side
 
right
 left or right No

Note

The orientation of the axes is equivalent to the definition used by MoMo from Jan Simon. 

Generated trajectories

name type description 
<name>
 3x3 matrix 
<name>_X
 3d vector first column of the matrix <name> 
<name>_Y
 3d vector second column of the matrix <name> 
<name>_Z
 3d vector third column of the matrix <name> 
<name>Position
 3d vector origin of the coordinate system 
<name>xv
 3d vector vectors in direction of the coordinate system axes and with the length defined by the value of  the attribute visibleVectorLength 
<name>yv
 
<name>zv
 
<name>X0
 3d vector Points which represents end points of the arrows of coordinate axis. If an external visualization tool (Vicon Workstation) can visualize only points and not directly vectors, these points can be used in combination with the coordinates system origin to visualizes the axes by three lines with different length. 
<name>Y0
 
<name>Z0

Note

is the value of the elements name attribute.

 Trajectories inherited from GaitDirectionCalcElement

name type description 
<name>GaitDirection
 gait direction, equal to <name>_X 
<name>GaitDirectionAngle

Examples

<GaitPhases name="GaitPhases"/>
<GaitCoordinateSystem name="RGait">(SACR+RASI+LASI)/3.0</GaitCoordinateSystem>

Gait phases must be defined first to use this element. 

This definition is based on default values and defines a right handed gait coordinate system based on the stride defined by "RStride" phase type and the midpoint of the pelic.