This class serves as a serializable ForceVelocityInverseCurve for use in equilibrium muscle models. More...

#include <ForceVelocityInverseCurve.h>

Inheritance diagram for OpenSim::ForceVelocityInverseCurve:

Public Member Functions
	ForceVelocityInverseCurve ()
	The default constructor creates an inverse force-velocity curve using the default property values and assigns a default name.
	ForceVelocityInverseCurve (double concentricSlopeAtVmax, double concentricSlopeNearVmax, double isometricSlope, double eccentricSlopeAtVmax, double eccentricSlopeNearVmax, double maxEccentricVelocityForceMultiplier, double concentricCurviness, double eccentricCurviness)
	Constructs an inverse force-velocity curve using the provided parameters and assigns a default name.
double	getConcentricSlopeAtVmax () const
double	getConcentricSlopeNearVmax () const
double	getIsometricSlope () const
double	getEccentricSlopeAtVmax () const
double	getEccentricSlopeNearVmax () const
double	getMaxEccentricVelocityForceMultiplier () const
double	getConcentricCurviness () const
double	getEccentricCurviness () const
void	setCurveShape (double aConcentricSlopeAtVmax, double aConcentricSlopeNearVmax, double aIsometricSlope, double aEccentricSlopeAtVmax, double aEccentricSlopeNearVmax, double aMaxForceMultiplier)
void	setConcentricCurviness (double aConcentricCurviness)
void	setEccentricCurviness (double aEccentricCurviness)
double	calcValue (const SimTK::Vector &x) const override
	Implement the generic OpenSim::Function interface.
double	calcValue (double aForceVelocityMultiplier) const
	Evaluates the inverse force-velocity curve at a force-velocity multiplier value of 'aForceVelocityMultiplier'.
double	calcDerivative (double aForceVelocityMultiplier, int order) const
	Calculates the derivative of the inverse force-velocity curve with respect to the force-velocity multiplier.
SimTK::Vec2	getCurveDomain () const
	Returns a SimTK::Vec2 containing the lower (0th element) and upper (1st element) bounds on the domain of the curve.
void	printMuscleCurveToCSVFile (const std::string &path)
	Generates a .csv file with a name that matches the curve name (e.g., "bicepsfemoris_ForceVelocityInverseCurve.csv").
void	ensureCurveUpToDate ()
Property declarations
These are the serializable properties associated with this class.
	OpenSim_DECLARE_PROPERTY (concentric_slope_at_vmax, double,"Slope of force-velocity curve at the maximum normalized concentric (shortening) velocity (normalized velocity of -1)")
	OpenSim_DECLARE_PROPERTY (concentric_slope_near_vmax, double,"Slope of force-velocity curve just before reaching concentric_slope_at_vmax")
	OpenSim_DECLARE_PROPERTY (isometric_slope, double,"Slope of force-velocity curve at isometric (normalized velocity of 0)")
	OpenSim_DECLARE_PROPERTY (eccentric_slope_at_vmax, double,"Slope of force-velocity curve at the maximum normalized eccentric (lengthening) velocity (normalized velocity of 1)")
	OpenSim_DECLARE_PROPERTY (eccentric_slope_near_vmax, double,"Slope of force-velocity curve just before reaching eccentric_slope_at_vmax")
	OpenSim_DECLARE_PROPERTY (max_eccentric_velocity_force_multiplier, double,"Value of force-velocity curve at the maximum normalized eccentric contraction velocity")
	OpenSim_DECLARE_PROPERTY (concentric_curviness, double,"Shape of concentric branch of force-velocity curve, from linear (0) to maximal curve (1)")
	OpenSim_DECLARE_PROPERTY (eccentric_curviness, double,"Shape of eccentric branch of force-velocity curve, from linear (0) to maximal curve (1)")
Public Member Functions inherited from OpenSim::Function
	Function ()
	Function (const Function &aFunction)
virtual	~Function ()
virtual void	init (Function *aFunction)
Function &	operator= (const Function &aFunction)
virtual double	calcDerivative (const std::vector< int > &derivComponents, const SimTK::Vector &x) const
	Calculate a partial derivative of this function at a particular point.
virtual int	getArgumentSize () const
	Get the number of components expected in the input vector.
virtual int	getMaxDerivativeOrder () const
	Get the maximum derivative order this Function object can calculate.
virtual SimTK::Function *	createSimTKFunction () const =0
Public Member Functions inherited from OpenSim::Object
virtual	~Object ()
	Virtual destructor for cleanup.
virtual Object *	clone () const =0
	Create a new heap-allocated copy of the concrete object to which this Object refers.
virtual const std::string &	getConcreteClassName () const =0
	Returns the class name of the concrete Object-derived class of the actual object referenced by this Object, as a string.
virtual const VisibleObject *	getDisplayer () const
	Methods to support making the object displayable in the GUI or Visualizer Implemented only in few objects.
virtual VisibleObject *	updDisplayer ()
	get Non const pointer to VisibleObject
bool	isEqualTo (const Object &aObject) const
	Equality operator wrapper for use from languages not supporting operator overloading.
Object &	operator= (const Object &aObject)
	Copy assignment copies he base class fields, including the properties.
virtual bool	operator== (const Object &aObject) const
	Determine if two objects are equal.
virtual bool	operator< (const Object &aObject) const
	Provide an ordering for objects so they can be put in sorted containers.
void	setName (const std::string &name)
	Set the name of the Object.
const std::string &	getName () const
	Get the name of this Object.
void	setDescription (const std::string &description)
	Set description, a one-liner summary.
const std::string &	getDescription () const
	Get description, a one-liner summary.
const std::string &	getAuthors () const
	Get Authors of this Object.
void	setAuthors (const std::string &authors)
	Set Authors of this object, call this method in your constructor if needed.
const std::string &	getReferences () const
	Get references or publications to cite if using this object.
void	setReferences (const std::string &references)
	Set references or publications to cite if using this object.
int	getNumProperties () const
	Determine how many properties are stored with this Object.
const AbstractProperty &	getPropertyByIndex (int propertyIndex) const
	Get a const reference to a property by its index number, returned as an AbstractProperty.
AbstractProperty &	updPropertyByIndex (int propertyIndex)
	Get a writable reference to a property by its index number, returned as an AbstractProperty.
bool	hasProperty (const std::string &name) const
	Return true if this Object has a property of any type with the given name, which must not be empty.
const AbstractProperty &	getPropertyByName (const std::string &name) const
	Get a const reference to a property by its name, returned as an AbstractProperty.
AbstractProperty &	updPropertyByName (const std::string &name)
	Get a writable reference to a property by its name, returned as an AbstractProperty.
template<class T >
bool	hasProperty () const
	Return true if this Object contains an unnamed, one-object property that contains objects of the given template type T.
template<class T >
const Property< T > &	getProperty (const PropertyIndex &index) const
	Get property of known type Property<T> as a const reference; the property must be present and have the right type.
template<class T >
Property< T > &	updProperty (const PropertyIndex &index)
	Get property of known type Property<T> as a writable reference; the property must be present and have the right type.
void	setObjectIsUpToDateWithProperties ()
	When an object is initialized using the current values of its properties, it can set a flag indicating that it is up to date.
bool	isObjectUpToDateWithProperties () const
	Returns `true` if no property's value has changed since the last time setObjectIsUpToDateWithProperties() was called.
void	readObjectFromXMLNodeOrFile (SimTK::Xml::Element &objectElement, int versionNumber)
	We're given an XML element from which we are to populate this Object.
virtual void	updateFromXMLNode (SimTK::Xml::Element &objectElement, int versionNumber)
	Use this method to deserialize an object from a SimTK::Xml::Element.
virtual void	updateXMLNode (SimTK::Xml::Element &parent)
	Serialize this object into the XML node that represents it.
bool	getInlined () const
	Inlined means an in-memory Object that is not associated with an XMLDocument.
void	setInlined (bool aInlined, const std::string &aFileName="")
	Mark this as inlined or not and optionally provide a file name to associate with the new XMLDocument for the non-inline case.
std::string	getDocumentFileName () const
	If there is a document associated with this object then return the file name maintained by the document.
void	setAllPropertiesUseDefault (bool aUseDefault)
bool	print (const std::string &fileName)
	Write this Object into an XML file of the given name; conventionally the suffix to use is ".osim".
std::string	dump (bool dumpName=false)
	dump the XML representation of this Object into an std::string and return it.
void	clearObjectIsUpToDateWithProperties ()
	For testing or debugging purposes, manually clear the "object is up to date with respect to properties" flag.
virtual bool	isA (const char *type) const
	The default implementation returns true only if the supplied string is "Object"; each Object-derived class overrides this to match its own class name.
const std::string &	toString () const
	Wrapper to be used on Java side to display objects in tree; this returns just the object's name.
PropertySet &	getPropertySet ()
	OBSOLETE: Get a reference to the PropertySet maintained by the Object.
const PropertySet &	getPropertySet () const

Additional Inherited Members
Static Public Member Functions inherited from OpenSim::Function
static Function *	makeFunctionOfType (Function *aFunction, const std::string &aNewTypeName)
Static Public Attributes inherited from OpenSim::Object
static const std::string	DEFAULT_NAME
	Name used for default objects when they are serialized.
Protected Member Functions inherited from OpenSim::Function
void	resetFunction ()
	This should be called whenever this object has been modified.
Protected Attributes inherited from OpenSim::Function
SimTK::Function *	_function
Related Functions inherited from OpenSim::Object
#define	OpenSim_DECLARE_CONCRETE_OBJECT(ConcreteClass, SuperClass)
	Macro to be included as the first line of the class declaration for any non-templatized, concrete class that derives from OpenSim::Object.
#define	OpenSim_DECLARE_ABSTRACT_OBJECT(ConcreteClass, SuperClass)
	Macro to be included as the first line of the class declaration for any still-abstract class that derives from OpenSim::Object.
#define	OpenSim_DECLARE_CONCRETE_OBJECT_T(ConcreteClass, TArg, SuperClass)
	Macro to be included as the first line of the class declaration for any templatized, concrete class that derives from OpenSim::Object, like Set<T>.
#define	OpenSim_DECLARE_ABSTRACT_OBJECT_T(ConcreteClass, TArg, SuperClass)
	Macro to be included as the first line of the class declaration for any templatized, still-abstract class that derives from OpenSim::Object.

Detailed Description

This class serves as a serializable ForceVelocityInverseCurve for use in equilibrium muscle models.

The inverse force-velocity curve is dimensionless: force is normalized to maximum isometric force and velocity is normalized to the maximum muscle contraction velocity (vmax), where vmax is expressed in units of optimal_fiber_lengths per second. Negative normalized velocities correspond to concentric contraction (i.e., shortening). The inverse force-velocity curve is constructed from 8 properties, which are identical to those used to construct the corresponding force-velocity curve. See ForceVelocityCurve for descriptions of these parameters.

Parameters

concentricSlopeAtVmax	An exception will be thrown if this parameter is set to 0.
concentricSlopeNearVmax	An exception will be thrown if this parameter is set to 0.
isometricSlope
eccentricSlopeAtVmax	An exception will be thrown if this parameter is set to 0.
eccentricSlopeNearVmax	An exception will be thrown if this parameter is set to 0.
maxEccentricVelocityForceMultiplier
concentricCurviness
eccentricCurviness

Conditions

1a)  0 < concentricSlopeAtVmax < 1
1b)  concentricSlopeAtVmax < concentricSlopeNearVmax < 1
2a)  1 < isometricSlope
2b)  (maxEccentricVelocityForceMultiplier-1)/1 < isometricSlope
 3)  0 < eccentricSlopeAtVmax < (maxEccentricVelocityForceMultiplier-1)/1
 4)  1 < maxEccentricVelocityForceMultiplier
 5)  0 <= concentricCurviness <= 1
 6)  0 <= eccentricCurviness <= 1

Default Parameter Values

concentricSlopeAtVmax .................. 0.1
concentricSlopeNearVmax ................ 0.25
isometricSlope ......................... 5.0
eccentricSlopeAtVmax ................... 0.1
eccentricSlopeNearVmax ................. 0.15
maxEccentricVelocityForceMultiplier .... 1.4
concentricCurviness .................... 0.6
eccentricCurviness ..................... 0.9

Example

ForceVelocityInverseCurve fvInvCurve(0.1, 0.25, 5.0, 0.1, 0.15, 1.4, 0.6, 0.9);
double fvInvVal  = fvInvCurve.calcValue(1.0);
double dfvInvVal = fvInvCurve.calcDerivative(1.0, 1);

Note that this object should be updated through the set methods provided. These set methods will take care of rebuilding the curve correctly. If you modify the properties directly, the curve will not be rebuilt, and upon calling a function like calcValue, calcDerivative, or printCurveToCSVFile, an exception will be thrown because the curve is out-of-date with its properties.

Author: Matt Millard

Constructor & Destructor Documentation

OpenSim::ForceVelocityInverseCurve::ForceVelocityInverseCurve ( )

The default constructor creates an inverse force-velocity curve using the default property values and assigns a default name.

OpenSim::ForceVelocityInverseCurve::ForceVelocityInverseCurve	(	double	concentricSlopeAtVmax,
		double	concentricSlopeNearVmax,
		double	isometricSlope,
		double	eccentricSlopeAtVmax,
		double	eccentricSlopeNearVmax,
		double	maxEccentricVelocityForceMultiplier,
		double	concentricCurviness,
		double	eccentricCurviness
	)

Constructs an inverse force-velocity curve using the provided parameters and assigns a default name.

Member Function Documentation

double OpenSim::ForceVelocityInverseCurve::calcDerivative	(	double	aForceVelocityMultiplier,
		int	order
	)		const

Calculates the derivative of the inverse force-velocity curve with respect to the force-velocity multiplier.

Parameters

aForceVelocityMultiplier	The force-velocity multiplier value.
order	The order of the derivative. Only values of 0, 1, and 2 are acceptable.

Returns: The derivative of the inverse force-velocity curve with respect to the force-velocity multiplier.

double OpenSim::ForceVelocityInverseCurve::calcValue ( const SimTK::Vector & x ) const

inlineoverridevirtual

Implement the generic OpenSim::Function interface.

Reimplemented from OpenSim::Function.

double OpenSim::ForceVelocityInverseCurve::calcValue ( double aForceVelocityMultiplier ) const

Evaluates the inverse force-velocity curve at a force-velocity multiplier value of 'aForceVelocityMultiplier'.

void OpenSim::ForceVelocityInverseCurve::ensureCurveUpToDate ( )

double OpenSim::ForceVelocityInverseCurve::getConcentricCurviness ( ) const

Returns: A dimensionless parameter between 0 and 1 that describes the shape of the concentric branch of the force-velocity curve: a value of 0 indicates that the curve is very close to a straight line segment and a value of 1 indicates a curve that smoothly fills the corner formed by the linear extrapolation of 'concentricSlopeNearVmax' and 'isometricSlope', as shown in the figure in the class description.

double OpenSim::ForceVelocityInverseCurve::getConcentricSlopeAtVmax ( ) const

Returns: The slope of the force-velocity curve at a normalized velocity of -1, which is the minimum slope of the concentric side of the force-velocity curve.

double OpenSim::ForceVelocityInverseCurve::getConcentricSlopeNearVmax ( ) const

Returns: The slope of the force-velocity curve near the maximum normalized concentric (shortening) contraction velocity (between approximately -0.8 and -1).

SimTK::Vec2 OpenSim::ForceVelocityInverseCurve::getCurveDomain ( ) const

Returns a SimTK::Vec2 containing the lower (0th element) and upper (1st element) bounds on the domain of the curve.

Outside this domain, the curve is approximated using linear extrapolation.

Returns: The minimum and maximum value of the domain, x, of the curve y(x). Within this range, y(x) is a curve; outside this range, the function y(x) is a C2-continuous linear extrapolation.

double OpenSim::ForceVelocityInverseCurve::getEccentricCurviness ( ) const

Returns: A dimensionless parameter between 0 and 1 that describes the shape of the eccentric branch of the force-velocity curve: a value of 0 indicates that the curve is very close to a straight line segment and a value of 1 indicates a curve that smoothly fills the corner formed by the linear extrapolation of 'isometricSlope' and 'eccentricSlopeNearVmax', as shown in the figure in the class description.

double OpenSim::ForceVelocityInverseCurve::getEccentricSlopeAtVmax ( ) const

Returns: The slope of the force-velocity curve at a normalized velocity of 1, which is the minimum slope of the eccentric side of the force-velocity curve.

double OpenSim::ForceVelocityInverseCurve::getEccentricSlopeNearVmax ( ) const

Returns: The slope of the force-velocity curve near the maximum normalized eccentric (lengthening) contraction velocity (between approximately 0.8 and 1).

double OpenSim::ForceVelocityInverseCurve::getIsometricSlope ( ) const

Returns: The slope of the force-velocity curve at a normalized velocity of 0, which is the maximum slope of the force-velocity curve.

double OpenSim::ForceVelocityInverseCurve::getMaxEccentricVelocityForceMultiplier ( ) const

Returns: The value of the force-velocity curve (i.e., the force-velocity multiplier) at the maximum eccentric contraction velocity.

OpenSim::ForceVelocityInverseCurve::OpenSim_DECLARE_PROPERTY	(	concentric_slope_at_vmax	,
		double	,
		"Slope of force-velocity curve at the maximum normalized concentric (shortening) velocity (normalized velocity of -1)"
	)

OpenSim::ForceVelocityInverseCurve::OpenSim_DECLARE_PROPERTY	(	concentric_slope_near_vmax	,
		double	,
		"Slope of force-velocity curve just before reaching concentric_slope_at_vmax"
	)

OpenSim::ForceVelocityInverseCurve::OpenSim_DECLARE_PROPERTY	(	isometric_slope	,
		double	,
		"Slope of force-velocity curve at isometric (normalized velocity of 0)"
	)

OpenSim::ForceVelocityInverseCurve::OpenSim_DECLARE_PROPERTY	(	eccentric_slope_at_vmax	,
		double	,
		"Slope of force-velocity curve at the maximum normalized eccentric (lengthening) velocity (normalized velocity of 1)"
	)

OpenSim::ForceVelocityInverseCurve::OpenSim_DECLARE_PROPERTY	(	eccentric_slope_near_vmax	,
		double	,
		"Slope of force-velocity curve just before reaching eccentric_slope_at_vmax"
	)

OpenSim::ForceVelocityInverseCurve::OpenSim_DECLARE_PROPERTY	(	max_eccentric_velocity_force_multiplier	,
		double	,
		"Value of force-velocity curve at the maximum normalized eccentric contraction velocity"
	)

OpenSim::ForceVelocityInverseCurve::OpenSim_DECLARE_PROPERTY	(	concentric_curviness	,
		double	,
		"Shape of concentric branch of force-velocity	curve,
		from linear(0) to maximal curve(1)"
	)

OpenSim::ForceVelocityInverseCurve::OpenSim_DECLARE_PROPERTY	(	eccentric_curviness	,
		double	,
		"Shape of eccentric branch of force-velocity	curve,
		from linear(0) to maximal curve(1)"
	)

void OpenSim::ForceVelocityInverseCurve::printMuscleCurveToCSVFile ( const std::string & path )

Generates a .csv file with a name that matches the curve name (e.g., "bicepsfemoris_ForceVelocityInverseCurve.csv").

This function is not const to permit the curve to be rebuilt if it is out-of-date with its properties.

Parameters

path	The full destination path. Note that forward slashes ('/') must be used and there should not be a slash after the last folder.

The file will contain the following data:

column: 1 | 2 |     3 |       4
  data: x | y | dy/dx | d2y/dx2

Samples will be taken from the concentric linear extrapolation region (the region with normalized fiber velocities < -1), through the curve, out to the eccentric linear extrapolation region (the region with normalized fiber velocities > 1). The width of each linear extrapolation region is 10% of the curve domain, or 0.1*(x1-x0). The curve is sampled quite densely: the inverse force-velocity .csv file will have 200+20 rows.

Example To read the .csv file into Matlab, you need to set csvread to ignore the header row. Since csvread is 0-indexed, the following example will begin reading the .csv file from the first column of the second row:

data = csvread('bicepsfemoris_ForceVelocityInverseCurve.csv', 1, 0);

void OpenSim::ForceVelocityInverseCurve::setConcentricCurviness ( double aConcentricCurviness )

Parameters

aConcentricCurviness A dimensionless parameter between 0 and 1 that describes the shape of the concentric branch of the force-velocity curve: a value of 0 indicates that the curve is very close to a straight line segment and a value of 1 indicates a curve that smoothly fills the corner formed by the linear extrapolation of 'concentricSlopeNearVmax' and 'isometricSlope', as shown in the figure in the class description.

Conditions

0 <= concentricCurviness <= 1

void OpenSim::ForceVelocityInverseCurve::setCurveShape	(	double	aConcentricSlopeAtVmax,
		double	aConcentricSlopeNearVmax,
		double	aIsometricSlope,
		double	aEccentricSlopeAtVmax,
		double	aEccentricSlopeNearVmax,
		double	aMaxForceMultiplier
	)

Parameters

aConcentricSlopeAtVmax	The slope of the force-velocity curve at a normalized velocity of -1, which is the minimum slope of the concentric side of the force-velocity curve.
aConcentricSlopeNearVmax	The slope of the force-velocity curve near the maximum normalized concentric (shortening) contraction velocity (between approximately -0.8 and -1).
aIsometricSlope	The slope of the force-velocity curve at a normalized velocity of 0, which is the maximum slope of the force-velocity curve.
aEccentricSlopeAtVmax	The slope of the force-velocity curve at a normalized velocity of 1, which is the minimum slope of the eccentric side of the force-velocity curve.
aEccentricSlopeNearVmax	The slope of the force-velocity curve near the maximum normalized eccentric (lengthening) contraction velocity (between approximately 0.8 and 1).
aMaxForceMultiplier	The value of the force-velocity curve (i.e., the force-velocity multiplier) at the maximum eccentric contraction velocity.

Conditions

1a)  0 < concentricSlopeAtVmax < 1
1b)  concentricSlopeAtVmax < concentricSlopeNearVmax < 1
2a)  1 < isometricSlope
2b)  (maxEccentricVelocityForceMultiplier-1)/1 < isometricMaxSlope
3a)  0 < eccentricSlopeAtVmax < (maxEccentricVelocityForceMultiplier-1)/1
3b)  eccentricSlopeAtVmax < eccentricSlopeNearVmax < (maxEccentricVelocityForceMultiplier-1)/1
 4)  1 < maxEccentricVelocityForceMultiplier

void OpenSim::ForceVelocityInverseCurve::setEccentricCurviness ( double aEccentricCurviness )

Parameters

aEccentricCurviness A dimensionless parameter between 0 and 1 that describes the shape of the eccentric branch of the force-velocity curve: a value of 0 indicates that the curve is very close to a straight line segment and a value of 1 indicates a curve that smoothly fills the corner formed by the linear extrapolation of 'isometricSlope' and 'eccentricSlopeNearVmax', as shown in the figure in the class description.

Conditions

0 <= eccentricCurviness <= 1

The documentation for this class was generated from the following file:

E:/Projects/OpenSimTrunk/OpenSim/Actuators/ForceVelocityInverseCurve.h

Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation