This class serves as a serializable FiberCompressiveForceCosPennationCurve, which is used to ensure that the pennation angle approaches but never reaches an angle of 90 degrees. More...

#include <FiberCompressiveForceCosPennationCurve.h>

Inheritance diagram for OpenSim::FiberCompressiveForceCosPennationCurve:

Public Member Functions
	FiberCompressiveForceCosPennationCurve ()
	Default constructor creates an curve with the default property values, and assigns it a default name
	FiberCompressiveForceCosPennationCurve (double engagementAngleInDegrees, double stiffnessAtPerpendicular, double curviness, const std::string &muscleName)
	Constructs a C2 continuous compressive fiber force cos pennation curve.
	FiberCompressiveForceCosPennationCurve (double engagementAngleInDegrees, const std::string &muscleName)
	Constructs a C2 continuous compressive fiber force cos pennation curve using only the manditory property, engagmentAngleInDegrees.
double	getEngagementAngleInDegrees () const
double	getStiffnessAtPerpendicularInUse () const
double	getCurvinessInUse () const
bool	isFittedCurveBeingUsed () const
void	setEngagementAngleInDegrees (double aEngagementAngleInDegrees)
void	setOptionalProperties (double aStiffnessAtPerpendicular, double aCurviness)
double	calcValue (double cosPennationAngle) const
	Calculates the value of the curve evaluated at cosPennationAngle.
double	calcDerivative (double cosPennationAngle, int order) const
	Calculates the derivative of the fiber compressive force pennation angle curve w.r.t.
double	calcIntegral (double cosPennationAngle) const
	This function returns a SimTK::Vec2 that contains in its 0th element the lowest value of the curve domain, and in its 1st element the highest value in the curve domain of the curve.
SimTK::Vec2	getCurveDomain () const
void	printMuscleCurveToCSVFile (const std::string &path) const
	This function will generate a csv file with a name that matches the curve name (e.g.
Property declarations
These are the serializable properties associated with this class.
	OpenSim_DECLARE_PROPERTY (engagement_angle_in_degrees, double,"Engagement angle of the compressive pennation spring in degrees")
	OpenSim_DECLARE_OPTIONAL_PROPERTY (stiffness_at_perpendicular, double,"Stiffness of the curve at pennation angle of 90 degrees")
	OpenSim_DECLARE_OPTIONAL_PROPERTY (curviness, double,"Fiber curve bend, from linear to maximum bend (0-1)")
Public Member Functions inherited from OpenSim::ModelComponent
	ModelComponent ()
	Default constructor.
	ModelComponent (const std::string &aFileName, bool aUpdateFromXMLNode=true) SWIG_DECLARE_EXCEPTION
	Construct ModelComponent from an XML file.
	ModelComponent (SimTK::Xml::Element &aNode)
	Construct ModelComponent from a specific node in an XML document.
	ModelComponent (const ModelComponent &source)
	Construct ModelComponent with its contents copied from another ModelComponent; this is a deep copy so nothing is shared with the source after the copy.
virtual	~ModelComponent ()
	Destructor is virtual to allow concrete model component cleanup.
ModelComponent &	operator= (const ModelComponent &aModelComponent)
	Assignment operator to copy contents of an existing component.
const Model &	getModel () const
	Get a const reference to the Model this component is part of.
Model &	updModel ()
	Get a modifiable reference to the Model this component is part of.
virtual void	updateDisplayer (const SimTK::State &s)
	In case the ModelComponent has a visual representation (VisualObject), override this method to update it.
virtual int	getNumStateVariables () const
	Get the number of "Continuous" state variables maintained by the ModelComponent and its specified subcomponents.
virtual Array< std::string >	getStateVariableNames () const
	Get the names of "continuous" state variables maintained by the ModelComponent and its subcomponents.
virtual SimTK::SystemYIndex	getStateVariableSystemIndex (const std::string &stateVariableName) const
	Get the System Index of a state variable allocated by this ModelComponent.
int	getModelingOption (const SimTK::State &state, const std::string &name) const
	Get a ModelingOption flag for this ModelComponent by name.
void	setModelingOption (SimTK::State &state, const std::string &name, int flag) const
	Set the value of a ModelingOption flag for this ModelComponent.
double	getStateVariable (const SimTK::State &state, const std::string &name) const
	Get the value of a state variable allocated by this ModelComponent.
void	setStateVariable (SimTK::State &state, const std::string &name, double value) const
	Set the value of a state variable allocated by this ModelComponent by name.
double	getDiscreteVariable (const SimTK::State &state, const std::string &name) const
	Get the value of a discrete variable allocated by this ModelComponent by name.
void	setDiscreteVariable (SimTK::State &state, const std::string &name, double value) const
	Set the value of a discrete variable allocated by this ModelComponent by name.
template<typename T >
const T &	getCacheVariable (const SimTK::State &state, const std::string &name) const
	Get the value of a cache variable allocated by this ModelComponent by name.
template<typename T >
T &	updCacheVariable (const SimTK::State &state, const std::string &name) const
	Obtain a writable cache variable value allocated by this ModelComponent by name.
void	markCacheVariableValid (const SimTK::State &state, const std::string &name) const
	After updating a cache variable value allocated by this ModelComponent, you can mark its value as valid, which will not change until the realization stage falls below the minimum set at the time the cache variable was created.
void	markCacheVariableInvalid (const SimTK::State &state, const std::string &name) const
	Mark a cache variable value allocated by this ModelComponent as invalid.
bool	isCacheVariableValid (const SimTK::State &state, const std::string &name) const
	Enables the to monitor the validity of the cache variable value using the returned flag.
template<typename T >
void	setCacheVariable (const SimTK::State &state, const std::string &name, T &value) const
	Set cache variable value allocated by this ModelComponent by name.
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 \c true if any 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

Protected Member Functions
void	connectToModel (Model &aModel) override
	ModelComponent Interface required function.
void	initStateFromProperties (SimTK::State &s) const override
	ModelComponent Interface required function.
void	addToSystem (SimTK::MultibodySystem &system) const override
	ModelComponent is being used for this one function, which is called just prior to a simulation beginning.
void	setPropertiesFromState (const SimTK::State &state)
	ModelComponent Interface required function.
Protected Member Functions inherited from OpenSim::ModelComponent
virtual SimTK::Vector	computeStateVariableDerivatives (const SimTK::State &s) const
	If a model component has allocated any continuous state variables using the addStateVariable() method, then computeStateVariableDerivatives() must be implemented to provide time derivatives for those states.
virtual void	generateDecorations (bool fixed, const ModelDisplayHints &hints, const SimTK::State &state, SimTK::Array_< SimTK::DecorativeGeometry > &appendToThis) const
	Optional method for generating arbitrary display geometry that reflects this ModelComponent at the specified state.
void	includeAsSubComponent (ModelComponent *aComponent)
	Include another ModelComponent as a Subcomponent of this ModelComponent.
void	addModelingOption (const std::string &optionName, int maxFlagValue) const
	Add a modeling option (integer flag stored in the State) for use by this ModelComponent.
void	addStateVariable (const std::string &stateVariableName, SimTK::Stage invalidatesStage=SimTK::Stage::Dynamics) const
	Add a continuous system state variable belonging to this ModelComponent, and assign a name by which to refer to it.
void	addDiscreteVariable (const std::string &discreteVariableName, SimTK::Stage invalidatesStage) const
	Add a system discrete variable belonging to this ModelComponent, give it a name by which it can be referenced, and declare the lowest Stage that should be invalidated if this variable's value is changed.
template<class T >
void	addCacheVariable (const std::string &cacheVariableName, const T &variablePrototype, SimTK::Stage dependsOnStage) const
	Add a state cache entry belonging to this ModelComponent to hold calculated values that must be automatically invalidated when certain state values change.
const int	getStateIndex (const std::string &name) const
	Get the index of a ModelComponent's continuous state variable in the Subsystem for allocations.
const SimTK::DiscreteVariableIndex	getDiscreteVariableIndex (const std::string &name) const
	Get the index of a ModelComponent's discrete variable in the Subsystem for allocations.
const SimTK::CacheEntryIndex	getCacheVariableIndex (const std::string &name) const
	Get the index of a ModelComponent's cache variable in the Subsystem for allocations.
Protected Member Functions inherited from OpenSim::Object
	Object ()
	The default constructor is only for use by constructors of derived types.
	Object (const std::string &fileName, bool aUpdateFromXMLNode=true) SWIG_DECLARE_EXCEPTION
	Constructor from a file, to be called from other constructors that take a file as input.
	Object (const Object &source)
	Copy constructor is invoked automatically by derived classes with default copy constructors; otherwise it must be invoked explicitly.
	Object (SimTK::Xml::Element &aElement)
	Construct the base class portion of an %Object from a given Xml element that describes this Object.
template<class T >
PropertyIndex	addProperty (const std::string &name, const std::string &comment, const T &value)
	Define a new single-value property of known type T, with the given name, associated comment, and initial value.
template<class T >
PropertyIndex	addOptionalProperty (const std::string &name, const std::string &comment)
	Add an optional property, meaning it can contain either no value or a single value.
template<class T >
PropertyIndex	addOptionalProperty (const std::string &name, const std::string &comment, const T &value)
	Add an optional property, meaning it can contain either no value or a single value.
template<class T >
PropertyIndex	addListProperty (const std::string &name, const std::string &comment, int minSize, int maxSize)
	Define a new list-valued property of known type T, with the given name, associated comment, minimum (==0) and maximum (>0) allowable list lengths, and a zero-length initial value.
template<class T , template< class > class Container>
PropertyIndex	addListProperty (const std::string &name, const std::string &comment, int minSize, int maxSize, const Container< T > &valueList)
	Define a new list-valued property as above, but assigning an initial value via some templatized container class that supports size() and indexing.
PropertyIndex	getPropertyIndex (const std::string &name) const
	Look up a property by name and return its PropertyIndex if it is found.
template<class T >
PropertyIndex	getPropertyIndex () const
	Look up an unnamed property by the type of object it contains, and return its PropertyIndex if it is found.
void	updateFromXMLDocument ()
	Use this method only if you're deserializing from a file and the object is at the top level; that is, primarily in constructors that take a file name as input.
void	setDocument (XMLDocument *doc)
	Unconditionally set the XMLDocument associated with this object.
const XMLDocument *	getDocument () const
	Get a const pointer to the document (if any) associated with this object.
XMLDocument *	updDocument ()
	Get a writable pointer to the document (if any) associated with this object.

Additional Inherited Members
Static Public Member Functions inherited from OpenSim::Object
static void	registerType (const Object &defaultObject)
	Register an instance of a class; if the class is already registered it will be replaced.
static void	renameType (const std::string &oldTypeName, const std::string &newTypeName)
	Support versioning by associating the current %Object type with an old name.
static const Object *	getDefaultInstanceOfType (const std::string &concreteClassName)
	Return a pointer to the default instance of the registered (concrete) Object whose class name is given, or NULL if the type is not registered.
template<class T >
static bool	isObjectTypeDerivedFrom (const std::string &concreteClassName)
	Return true if the given concrete object type represents a subclass of the template object type T, and thus could be referenced with a T*.
static Object *	newInstanceOfType (const std::string &concreteClassName)
	Create a new instance of the concrete %Object type whose class name is given as concreteClassName.
static void	getRegisteredTypenames (Array< std::string > &typeNames)
	Retrieve all the typenames registered so far.
template<class T >
static void	getRegisteredObjectsOfGivenType (ArrayPtrs< T > &rArray)
	Return an array of pointers to the default instances of all registered (concrete) Object types that derive from a given Object-derived type that does not have to be concrete.
static void	PrintPropertyInfo (std::ostream &os, const std::string &classNameDotPropertyName)
	Dump formatted property information to a given output stream, useful for creating a "help" facility for registered objects.
static void	PrintPropertyInfo (std::ostream &os, const std::string &className, const std::string &propertyName)
	Same as the other signature but the class name and property name are provided as two separate strings.
static Object *	makeObjectFromFile (const std::string &fileName)
	Create an %OpenSim object whose type is based on the tag at the root node of the XML file passed in.
static const std::string &	getClassName ()
	Return the name of this class as a string; i.e., "Object".
static void	setSerializeAllDefaults (bool shouldSerializeDefaults)
	Static function to control whether all registered objects and their properties are written to the defaults section of output files rather than only those values for which the default was explicitly overwritten when read in from an input file or set programmatically.
static bool	getSerializeAllDefaults ()
	Report the value of the "serialize all defaults" flag.
static bool	isKindOf (const char *type)
	Returns true if the passed-in string is "Object"; each %Object-derived class defines a method of this name for its own class name.
static void	setDebugLevel (int newLevel)
	Set the debug level to get verbose output.
static int	getDebugLevel ()
	Get current setting of debug level.
static Object *	SafeCopy (const Object *aObject)
	Use the clone() method to duplicate the given object unless the pointer is null in which case null is returned.
static void	RegisterType (const Object &defaultObject)
	OBSOLETE alternate name for registerType().
static void	RenameType (const std::string &oldName, const std::string &newName)
	OBSOLETE alternate name for renameType().
Static Public Attributes inherited from OpenSim::Object
static const std::string	DEFAULT_NAME
	Name used for default objects when they are serialized.
Protected Attributes inherited from OpenSim::ModelComponent
Model *	_model
	The model this component belongs to.
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 FiberCompressiveForceCosPennationCurve, which is used to ensure that the pennation angle approaches but never reaches an angle of 90 degrees.

Preventing the fibers from achivieving a pennation angle of 90 degrees is important for equilibrium muscle models which have a singularity at this value.

This curve is designed to work with the muscle model in such a way that it acts like a spring that the pennated muscle fibers contact it as the fiber rotates (circuled in red). When the spring engages it will exert a force on the fiber that will prevent it from shortening further, thus preventing the pennation angle from reaching 90 degrees.

Author: Matt Millard

Constructor & Destructor Documentation

OpenSim::FiberCompressiveForceCosPennationCurve::FiberCompressiveForceCosPennationCurve ( )

 Default constructor creates an curve with the default property values,

and assigns it a default name

OpenSim::FiberCompressiveForceCosPennationCurve::FiberCompressiveForceCosPennationCurve	(	double	engagementAngleInDegrees,
		double	stiffnessAtPerpendicular,
		double	curviness,
		const std::string &	muscleName
	)

Constructs a C2 continuous compressive fiber force cos pennation curve.

The sole purpose of this curve is to prevent the pennation angle from reaching an angle of 90 degrees. Details to appear in Millard et al. 2012.

Parameters

engagementAngleInDegrees	The pennation angle engagement angle of the fiber compressive force pennation curve. Making the spring engage too far from 90 degrees may unrealistically limit the force production capability of the muscle. An engagement angle of 80 degrees is a good place to start.
stiffnessAtPerpendicular	This is the stiffness of the compressive elastic force length spring when the pennation angle reaches 90 degrees. Note that the units of this stiffness are (normalized force) / cos(engagmentAngleInDegrees). If the engagement angle is 80 degrees, a good stiffness to start with is -2*(1/cosd(engagementAngleInDegrees))
curviness	A dimensionless parameter between [0-1] that controls how the curve is drawn: 0 will create a curve that is very close to a straight line segment while a value of 1 will create a curve that smoothly fills the corner formed by the linear extrapolation of 'stiffnessAtPerpendicularFiber' and the x axis as shown in the figure. A good curviness parameter value to start with is 0.5.
muscleName	The name of the muscle this curve belongs to. This name is used to create the name of this curve, which is formed simply by appending "_FiberCompressiveForceCosPennationCurve" to the string in muscleName. This name is used for making intelligible error messages and also for naming the XML version of this curve when it is serialized.

Conditions:

        0 < engagmentAngleInDegrees < 90
        stiffnessAtPerpendicular < -1/engagmentAngleInDegrees
        0 <= curviness <= 1

Computational Costs

        ~174,100 flops

Default Parameter Values

         engagmentAngleInDegrees = 80

Example:

OpenSim::FiberCompressiveForceCosPennationCurve::FiberCompressiveForceCosPennationCurve	(	double	engagementAngleInDegrees,
		const std::string &	muscleName
	)

Constructs a C2 continuous compressive fiber force cos pennation curve using only the manditory property, engagmentAngleInDegrees.

The sole purpose of this curve is to prevent the pennation angle from reaching an angle of 90 degrees. Details to appear in Millard et al. 2012.

Parameters

engagementAngleInDegrees	The pennation angle engagement angle of the fiber compressive force pennation curve. Making the spring engage too far from 90 degrees may unrealistically limit the force production capability of the muscle. An engagement angle of 80 degrees is a good place to start.
muscleName	The name of the muscle this curve belongs to. This name is used to create the name of this curve, which is formed simply by appending "_FiberCompressiveForceCosPennationCurve" to the string in muscleName. This name is used for making intelligible error messages and also for naming the XML version of this curve when it is serialized.

Optional Parameters If the optional parameters have not yet been set, they are computed when functions getStiffnessAtPerpendicularInUse(), and getCurvinessInUse() are called. See the documentation for these functions for details

Conditions:

        0 < engagmentAngleInDegrees < 90

Computational Costs

        ~174,100 flops

Default Parameter Values

         engagmentAngleInDegrees = 80

Example:

Member Function Documentation

void OpenSim::FiberCompressiveForceCosPennationCurve::addToSystem ( SimTK::MultibodySystem & system ) const

overrideprotectedvirtual

ModelComponent is being used for this one function, which is called just prior to a simulation beginning.

This is the ideal time to actually create the curve because

The curve parameters cannot change anymore
This function is only called just prior to simulation, so the expensive task of creating the curve will only be done when it is absolutely necessary

Reimplemented from OpenSim::ModelComponent.

double OpenSim::FiberCompressiveForceCosPennationCurve::calcDerivative	(	double	cosPennationAngle,
		int	order
	)		const

Calculates the derivative of the fiber compressive force pennation angle curve w.r.t.

to cosPennationAngle. Note that if the curve is out of date it is rebuilt (at a cost of ~20,500 flops).

Parameters

cosPennationAngle,:	The cosine of the fiber pennation angle
order,:	the order of the derivative. Only values of 0,1 and 2 are acceptable.

Returns: the derivative of the fiber compressive force pennation angle curve w.r.t. to cosPennationAngle

Computational Costs

    x in curve domain  : ~391 flops
    x in linear section:   ~2 flops

double OpenSim::FiberCompressiveForceCosPennationCurve::calcIntegral ( double cosPennationAngle ) const

This function returns a SimTK::Vec2 that contains in its 0th element the lowest value of the curve domain, and in its 1st element the highest value in the curve domain of the curve.

Outside of this domain the curve is approximated using linear extrapolation. Note that if the curve is out of date is rebuilt (which will cost ~20,500 flops).

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

Parameters

aNormLength The cosine of the pennation angle

Returns: Computes the normalized area under the curve. For this curve, this quantity corresponds to the normalized potential energy stored in the fiber compressive force cos pennation spring - simply multiply this quantity by the number of NormForce (where NormForce corresponds to the number of Newtons that 1 normalized force corresponds to) to obtain the potental energy stored in the fiber in units of Joules. Note that NormDistance is omitted because the length dimension of this curve is not normalized, only the force dimension.

Computational Costs

    x in curve domain  : ~13 flops
    x in linear section: ~19 flops

double OpenSim::FiberCompressiveForceCosPennationCurve::calcValue ( double cosPennationAngle ) const

Calculates the value of the curve evaluated at cosPennationAngle.

Note that if the curve is out of date it is rebuilt (at a cost of ~20,500 flops).

Parameters

cosPennationAngle,: The cosine of the fiber pennation angle

Returns: the normalized force generated by the compressive force element

Computational Costs

    x in curve domain  : ~282 flops
    x in linear section:   ~5 flops

void OpenSim::FiberCompressiveForceCosPennationCurve::connectToModel ( Model & aModel )

overrideprotectedvirtual

ModelComponent Interface required function.

Reimplemented from OpenSim::ModelComponent.

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

double OpenSim::FiberCompressiveForceCosPennationCurve::getCurvinessInUse ( ) const

Returns: A dimensionless parameter between [0-1] that controls how the curve is drawn: 0 will create a curve that is very close to a straight line segment while a value of 1 will create a curve that smoothly fills the corner formed by the linear extrapolation of 'StiffnessAtPerpendicularFiber'.

If this property is empty, then a value is computed and returned. The value is computed using the following:

           curviness = 0.1

double OpenSim::FiberCompressiveForceCosPennationCurve::getEngagementAngleInDegrees ( ) const

Returns: The pennation angle engagement angle of the fiber compressive force pennation curve.

double OpenSim::FiberCompressiveForceCosPennationCurve::getStiffnessAtPerpendicularInUse ( ) const

Returns: This is the stiffness of the compressive elastic force length spring when the pennation angle reaches 90 degrees. If this property has been set, the property value is returned. If this property is empty, then a value is computed and returned. The value is computed using the following:

           stiffnessAtPerpendicular = -2 * 1/cosd(engagementAngleInDegrees)

where cosd is a cosine function that takes its argument in units of degrees

void OpenSim::FiberCompressiveForceCosPennationCurve::initStateFromProperties ( SimTK::State & s ) const

overrideprotectedvirtual

ModelComponent Interface required function.

Reimplemented from OpenSim::ModelComponent.

bool OpenSim::FiberCompressiveForceCosPennationCurve::isFittedCurveBeingUsed ( ) const

OpenSim::FiberCompressiveForceCosPennationCurve::OpenSim_DECLARE_OPTIONAL_PROPERTY	(	stiffness_at_perpendicular	,
		double	,
		"Stiffness of the curve at pennation angle of 90 degrees"
	)

OpenSim::FiberCompressiveForceCosPennationCurve::OpenSim_DECLARE_OPTIONAL_PROPERTY	(	curviness	,
		double	,
		"Fiber curve	bend,
		from linear to maximum bend(0-1)"
	)

OpenSim::FiberCompressiveForceCosPennationCurve::OpenSim_DECLARE_PROPERTY	(	engagement_angle_in_degrees	,
		double	,
		"Engagement angle of the compressive pennation spring in degrees"
	)

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

This function will generate a csv file with a name that matches the curve name (e.g.

"bicepfemoris_FiberCompressiveForceCosPennationCurve.csv"); Note that if the curve is out of date is rebuilt (which will cost ~20,500 flops).

Parameters

path	The full path to the location. Note '/' slashes must be used, and do not put a '/' after the last folder.

The file will contain the following columns:

Col# 1, 2,     3,       4,  
     x, y, dy/dx, d2y/dx2,

The curve will be sampled from its linear extrapolation region (the region with normalized fiber velocities < -1), through the curve, out to the other linear extrapolation region (the region with normalized fiber velocities > 1). The width of each linear extrapolation region is 10% of the entire range of x, or 0.1*(x1-x0).

The curve is sampled quite densely: there are 200+20 rows

Computational Costs

     ~194,800 flops

Example To read the csv file with a header in from Matlab, you need to use csvread set so that it will ignore the header row. This is accomplished by using the extra two numerical arguments for csvread to tell the function to begin reading from the 1st row, and the 0th index (csvread is 0 indexed). This is necessary to skip reading in the text header

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

void OpenSim::FiberCompressiveForceCosPennationCurve::setEngagementAngleInDegrees ( double aEngagementAngleInDegrees )

Parameters

aEngagementAngleInDegrees Sets the pennation angle engagement angle of the fiber compressive force pennation curve.

void OpenSim::FiberCompressiveForceCosPennationCurve::setOptionalProperties	(	double	aStiffnessAtPerpendicular,
		double	aCurviness
	)

Parameters

aStiffnessAtPerpendicular	This is the stiffness of the compressive elastic force length spring when the pennation angle reaches 90 degrees.
aCurviness	A dimensionless parameter between [0-1] that controls how the curve is drawn: 0 will create a curve that is very close to a straight line segment while a value of 1 will create a curve that smoothly fills the corner formed by the linear extrapolation of 'stiffnessAtOneNormForce' and the x axis as shown in the figure.

void OpenSim::FiberCompressiveForceCosPennationCurve::setPropertiesFromState ( const SimTK::State & state )

inlineprotectedvirtual

ModelComponent Interface required function.

Reimplemented from OpenSim::ModelComponent.

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

E:/Projects/OpenSim30Br/OpenSim30/OpenSim/Actuators/FiberCompressiveForceCosPennationCurve.h

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