btk::VerticalGroundReactionForceGaitEventDetector Class Reference

Detect heel strike and toe-off events during gait from vertical ground reaction wrench. More...

Inheritance diagram for btk::VerticalGroundReactionForceGaitEventDetector:

Public Types
typedef btkSharedPtr< const VerticalGroundReactionForceGaitEventDetector >	ConstPointer
typedef btkSharedPtr < VerticalGroundReactionForceGaitEventDetector >	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
void	GetAcquisitionInformation (int &firstFrame, double &freq, std::string &subjectName)
const std::vector< std::string > &	GetForceplateContextMapping () const
WrenchCollection::Pointer	GetInput ()
EventCollection::Pointer	GetOutput ()
const int *	GetRegionOfInterest () const
int	GetThresholdValue () const
void	SetAcquisitionInformation (int firstFrame, double freq, const std::string &subjectName)
void	SetForceplateContextMapping (const std::vector< std::string > &mapping)
void	SetInput (Wrench::Pointer input)
void	SetInput (WrenchCollection::Pointer input)
void	SetRegionOfInterest (int lb=-1, int ub=-1)
void	SetThresholdValue (int threshold)
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 ()

Protected Member Functions
virtual void	GenerateData ()
WrenchCollection::Pointer	GetInput (int idx)
EventCollection::Pointer	GetOutput (int idx)
virtual DataObject::Pointer	MakeOutput (int idx)
	VerticalGroundReactionForceGaitEventDetector ()
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

Detect heel strike and toe-off events during gait from vertical ground reaction wrench.

To fill exactly the detected events, you need to give some extra information to this filter:

• The value of the first frame of the acquisition where the force platform data were extracted (to be added to the detected frames' index).
• The acquisition's frequency used by the force platform data (to calculate the time related to the event's frame).
• The subject's label (optional). All these informations have to be given to the method SetAcquisitionInformation().

To detect the heel strike and toe-off events you can set some options:

• The threshold value used to known when an event occurred (see SetThresholdValue()).
• The mapping between the force plates and the side (left, right, general) of the events detected (see SetForceplateContextMapping()).
• The region of interest where to detect the events (see SetRegionOfInterest()).

The algorithm works as following: Based on the region of interest, the maximum is searched. If the maximum is higher than the threshold set, then the frame of the value on the left side of this maximum lower than the threshold is used to create a heel strike event. On the other hand, the value on the right side of the maximum lower than the threshold is used to create a toe-off event.

Note

: The design of this class is not perfect as it cannot be used in a pipeline without to update the part before to know some acquisition's information (first frame, sample frequency, subject's name). This class (or the pipeline mechanism) could be modified in a future version of BTK to make up this problem.

Member Typedef Documentation

btk::VerticalGroundReactionForceGaitEventDetector::ConstPointer

Smart pointer associated with a const VerticalGroundReactionForceGaitEventDetector object.

btk::VerticalGroundReactionForceGaitEventDetector::Pointer

Smart pointer associated with a VerticalGroundReactionForceGaitEventDetector object.

Constructor & Destructor Documentation

btk::VerticalGroundReactionForceGaitEventDetector::VerticalGroundReactionForceGaitEventDetector ( )

protected

Constructor. By default, the treshold is set to 10 newtons and the algoritm search events on all the frames.

Member Function Documentation

void btk::VerticalGroundReactionForceGaitEventDetector::GenerateData ( )

protectedvirtual

Algorithm used to detect events during the gait.

Implements btk::ProcessObject.

void btk::VerticalGroundReactionForceGaitEventDetector::GetAcquisitionInformation	(	int &	firstFrame,
		double &	freq,
		std::string &	subjectName
	)

Returns the informations required to set correctly the detected events.

const std::vector< std::string > & btk::VerticalGroundReactionForceGaitEventDetector::GetForceplateContextMapping ( ) const

inline

Returns the mapping between the wrenches in the input and the gait events to detect.

EventCollection::Pointer btk::VerticalGroundReactionForceGaitEventDetector::GetInput ( )

inline

Gets the input registered with this process.

Acquisition::Pointer btk::VerticalGroundReactionForceGaitEventDetector::GetInput ( int  idx )

inlineprotected

Returns the input at the index idx.

EventCollection::Pointer btk::VerticalGroundReactionForceGaitEventDetector::GetOutput ( )

inline

Gets the output created with this process.

Acquisition::Pointer btk::VerticalGroundReactionForceGaitEventDetector::GetOutput ( int  idx )

inlineprotected

Returns the output at the index idx.

const int * btk::VerticalGroundReactionForceGaitEventDetector::GetRegionOfInterest ( ) const

inline

Returns the region of interest to use to detect gait events.

int btk::VerticalGroundReactionForceGaitEventDetector::GetThresholdValue ( ) const

inline

Returns the threshold used to detect gait events.

DataObject::Pointer btk::VerticalGroundReactionForceGaitEventDetector::MakeOutput ( int  idx )

protectedvirtual

Generate the output used by this filter.

Implements btk::ProcessObject.

static Pointer btk::VerticalGroundReactionForceGaitEventDetector::New ( )

inlinestatic

Creates a smart pointer associated with a VerticalGroundReactionForceGaitEventDetector object.

void btk::VerticalGroundReactionForceGaitEventDetector::SetAcquisitionInformation	(	int	firstFrame,
		double	freq,
		const std::string &	subjectName
	)

Set the informations required to set correctly the detected events.

void btk::VerticalGroundReactionForceGaitEventDetector::SetForceplateContextMapping

(

const std::vector< std::string > &

mapping

)

Sets the mapping between the given wrenches and the side of the detected events. If no mapping is given, then all the detected events will be set as "General" events.

void btk::VerticalGroundReactionForceGaitEventDetector::SetInput ( Wrench::Pointer  input )

inline

Sets the input required with this process. This input is transformed in a collection wrenches with a single force platform.

void btk::VerticalGroundReactionForceGaitEventDetector::SetInput ( WrenchCollection::Pointer  input )

inline

Sets the input required with this process.

void btk::VerticalGroundReactionForceGaitEventDetector::SetRegionOfInterest	(	int	lb = -1,
		int	ub = -1
	)

Sets the region of interest to use to detect gait events.

Warning

The boundaries must be set using zero-based indices.

void btk::VerticalGroundReactionForceGaitEventDetector::SetThresholdValue

(

int

threshold

)

Sets the threshold used to detect gait events.