Transform force platform data into ground reaction wrenches. More...

#include <btkGroundReactionWrenchFilter.h>

Inheritance diagram for btk::GroundReactionWrenchFilter:

Public Types
typedef btkSharedPtr< const GroundReactionWrenchFilter >	ConstPointer

typedef btkSharedPtr < GroundReactionWrenchFilter >	Pointer

Public Types inherited from btk::ForcePlatformWrenchFilter
typedef btkSharedPtr< const ForcePlatformWrenchFilter >	ConstPointer

typedef btkSharedPtr < ForcePlatformWrenchFilter >	Pointer

Public Types inherited from btk::ProcessObject
typedef btkSharedPtr< const ProcessObject >	ConstPointer

typedef btkSharedPtr < ProcessObject >	Pointer

Public Types inherited from btk::Object
typedef btkSharedPtr< const Object >	ConstPointer

typedef btkSharedPtr< Object >	Pointer

Public Member Functions
bool	GetThresholdState () const

double	GetThresholdValue () const

void	SetThresholdState (bool activated=false)

void	SetThresholdValue (double v)

Public Member Functions inherited from btk::ForcePlatformWrenchFilter
ForcePlatformCollection::Pointer	GetInput ()

WrenchCollection::Pointer	GetOutput ()

bool	GetTransformToGlobalFrame () const

void	SetInput (ForcePlatform::Pointer input)

void	SetInput (ForcePlatformCollection::Pointer input)

void	SetTransformToGlobalFrame (bool activation=false)

Public Member Functions inherited from btk::ProcessObject
int	GetInputNumber () const

int	GetOutputNumber () const

int	GetValidInputNumber () const

void	ResetState ()

void	Update ()

Public Member Functions inherited from btk::Object
unsigned long int	GetTimestamp () const

Static Public Member Functions
static Pointer	New ()

Static Public Member Functions inherited from btk::ForcePlatformWrenchFilter
static Pointer	New ()

Protected Member Functions
	GroundReactionWrenchFilter ()

Protected Member Functions inherited from btk::ForcePlatformWrenchFilter
	ForcePlatformWrenchFilter ()

virtual void	GenerateData ()

ForcePlatformCollection::Pointer	GetInput (int idx)

WrenchCollection::Pointer	GetOutput (int idx)

virtual DataObject::Pointer	MakeOutput (int idx)

Protected Member Functions inherited from btk::ProcessObject
int	GetInputIndex (DataObject::Pointer input)

DataObject::Pointer	GetNthInput (int idx)

DataObject::ConstPointer	GetNthInput (int idx) const

DataObject::Pointer	GetNthOutput (int idx)

DataObject::ConstPointer	GetNthOutput (int idx) const

int	GetOutputIndex (DataObject::Pointer output)

bool	IsModified () const

void	Modified ()

	ProcessObject ()

void	SetInputNumber (int num)

virtual void	SetNthInput (int idx, DataObject::Pointer input)

virtual void	SetNthOutput (int idx, DataObject::Pointer output)

void	SetOutputNumber (int num)

virtual	~ProcessObject ()

Protected Member Functions inherited from btk::Object
	Object ()

	Object (const Object &toCopy)

virtual	~Object ()

Additional Inherited Members
Protected Attributes inherited from btk::Object
unsigned long int	m_Timestamp

Detailed Description

Transform force platform data into ground reaction wrenches.

Theses wrenches are expressed in the global frame. The point of application (PWA) of each wrench is calculated from Shimba (1984). Compared to the center of pressure (COP), the PWA take into account all the forces and moments (and does not assume any null forces).

Note: For gait analysis, the COP and PWA are very similar.

Because the computation of the PWA (as the COP) is sensitive to small (vertical) forces, the methods SetThresholdValue and SetThresholdState() are provided to not compute the PWA if the vertical forces is the threshold. You first need to set the value and then activate the threshold method. By default, this threshold is not activated and the values is set to 0. As for example:

* btk::GroundReactionWrenchFilter::Pointer grwf = btk::GroundReactionWrenchFilter::New()
* grwf->SetThresholdValue(5.0); // 5 newtons
* grwf->SetThresholdState(true);
* 

Finally, you can also use the method SetTransformToGlobalFrame() to have the wrench expressed in the frame of the force platform.

Reference: Shimba T.
An estimation of center of gravity from force platform data.
Journal of Biomechanics, 1984, 17(1), 53–60.

Member Typedef Documentation

btk::GroundReactionWrenchFilter::ConstPointer

Smart pointer associated with a const GroundReactionWrenchFilter object.

btk::GroundReactionWrenchFilter::Pointer

Smart pointer associated with a GroundReactionWrenchFilter object.

Constructor & Destructor Documentation

btk::GroundReactionWrenchFilter::GroundReactionWrenchFilter ( )

protected

Constructor. Sets the number of inputs and outputs to 1.

Member Function Documentation

bool btk::GroundReactionWrenchFilter::GetThresholdState ( ) const

inline

Returns the state of the threshold used to suppress false PWA.

double btk::GroundReactionWrenchFilter::GetThresholdValue ( ) const

inline

Returns the value used to suppress PWA computed with a Fz value lower or equal than it.

The threshold must be activated (see GroundReactionWrenchFilter::SetThresholdState) to be used during the computation of the PWA.

static Pointer btk::GroundReactionWrenchFilter::New ( )

inlinestatic

Creates a smart pointer associated with a GroundReactionWrenchFilter object.

void btk::GroundReactionWrenchFilter::SetThresholdState ( bool activated = false )

Sets the threshold state.

void btk::GroundReactionWrenchFilter::SetThresholdValue ( double v )

Sets the threshold value.

The threshold must be activated (see GroundReactionWrenchFilter::SetThresholdState) to be used during the computation of the PWA.

Public Types

Public Member Functions

Static Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Member Typedef Documentation

Constructor & Destructor Documentation

Member Function Documentation