OpenSim::Thelen2003Muscle Class Reference

A class implementing a SIMM muscle. More...

#include <Thelen2003Muscle.h>

Inheritance diagram for OpenSim::Thelen2003Muscle:

List of all members.

Public Member Functions
	Thelen2003Muscle ()
	Default constructor.
	Thelen2003Muscle (const std::string &aName, double aMaxIsometricForce, double aOptimalFiberLength, double aTendonSlackLength, double aPennationAngle)
	Constructor.
	Thelen2003Muscle (const Thelen2003Muscle &aMuscle)
	Copy constructor.
virtual	~Thelen2003Muscle ()
	Destructor.
virtual Object *	copy () const
	Copy this muscle point and return a pointer to the copy.
Thelen2003Muscle &	operator= (const Thelen2003Muscle &aMuscle)
	Assignment operator.
void	copyData (const Thelen2003Muscle &aMuscle)
	Copy data members from one Thelen2003Muscle to another.
virtual double	getActivationTimeConstant () const
virtual double	getDeactivationTimeConstant () const
virtual double	getVmax () const
virtual double	getVmax0 () const
virtual double	getFmaxTendonStrain () const
virtual double	getFmaxMuscleStrain () const
virtual double	getKshapeActive () const
virtual double	getKshapePassive () const
virtual double	getDamping () const
virtual double	getAf () const
virtual double	getFlen () const
virtual bool	setActivationTimeConstant (double aActivationTimeConstant)
	Set the time constant for ramping up of muscle force.
virtual bool	setDeactivationTimeConstant (double aDeactivationTimeConstant)
	Set the time constant for ramping down of muscle force.
virtual bool	setVmax (double aVmax)
	Set the maximum contraction velocity of the fibers, in optimal fiber lengths per second.
virtual bool	setVmax0 (double aVmax0)
	Set the maximum contraction velocity at low activation of the fibers, in optimal fiber lengths per second.
virtual bool	setFmaxTendonStrain (double aFmaxTendonStrain)
	Set the tendon strain due to maximum isometric muscle force.
virtual bool	setFmaxMuscleStrain (double aFmaxMuscleStrain)
	Set the passive muscle strain due to maximum isometric muscle force.
virtual bool	setKshapeActive (double aKShapeActive)
	Set the shape factor for Gaussian active muscle force-length relationship.
virtual bool	setKshapePassive (double aKshapePassive)
	Set the shape factor for Gaussian passive muscle force-length relationship.
virtual bool	setDamping (double aDamping)
	Set the damping factor related to maximum contraction velocity.
virtual bool	setAf (double aAf)
	Set the force-velocity shape factor.
virtual bool	setFlen (double aFlen)
	Set the maximum normalized lengthening force.
virtual void	computeEquilibrium (SimTK::State &s) const
	Compute the equilibrium states.
virtual double	computeActuation (const SimTK::State &s) const
	Compute the actuation for the muscle.
double	calcTendonForce (const SimTK::State &s, double aNormTendonLength) const
	From cmg_dt.c - calc_tendon_force_dt.
double	calcPassiveForce (const SimTK::State &s, double aNormFiberLength) const
	From gmc.dt.c - calc_passive_fiber_force_dt.
double	calcActiveForce (const SimTK::State &s, double aNormFiberLength) const
	From gmc.dt.c - calc_active_force_dt.
double	calcFiberVelocity (const SimTK::State &s, double aActivation, double aActiveForce, double aVelocityDependentForce) const
	From gmc_dt.c - calc_norm_fiber_velocity_dt.
virtual double	computeIsometricForce (SimTK::State &s, double activation) const
	Find the force produced by an actuator (the musculotendon unit), assuming static equilibrium.
virtual int	getStateVariableYIndex (int index) const
	Get the YIndex of a state variable allocated by this ModelComponent.
	OPENSIM_DECLARE_DERIVED (Thelen2003Muscle, ActivationFiberLengthMuscle)
Protected Member Functions
virtual void	setup (Model &aModel)
	Perform some set up functions that happen after the object has been deserialized or copied.
virtual void	createSystem (SimTK::MultibodySystem &system) const
	allocate and initialize the SimTK state for this acuator.
virtual SimTK::Vector	computeStateVariableDerivatives (const SimTK::State &s) const
	Compute the derivatives of the muscle states.
Protected Attributes
PropertyDbl	_activationTimeConstantProp
	Activation time constant.
double &	_activationTimeConstant
PropertyDbl	_deactivationTimeConstantProp
	Deactivation time constant.
double &	_deactivationTimeConstant
PropertyDbl	_vmaxProp
	Max contraction velocity full activation in fiber lengths per second.
double &	_vmax
PropertyDbl	_vmax0Prop
	Max contraction velocity at low activation.
double &	_vmax0
PropertyDbl	_fmaxTendonStrainProp
	Tendon strain due to maximum isometric muscle force.
double &	_fmaxTendonStrain
PropertyDbl	_fmaxMuscleStrainProp
	Passive muscle strain due to maximum isometric muscle force.
double &	_fmaxMuscleStrain
PropertyDbl	_kShapeActiveProp
	Shape factor for Gaussian active muscle force-length relationship.
double &	_kShapeActive
PropertyDbl	_kShapePassiveProp
	Exponential shape factor for passive force-length relationship.
double &	_kShapePassive
PropertyDbl	_dampingProp
	Passive damping included in the force-velocity relationship.
double &	_damping
PropertyDbl	_afProp
	Force-velocity shape factor.
double &	_af
PropertyDbl	_flenProp
	Maximum normalized lengthening force.
double &	_flen
Static Protected Attributes
static const int	STATE_ACTIVATION = 0
static const int	STATE_FIBER_LENGTH = 1

---

Detailed Description

A class implementing a SIMM muscle.

Author:

Peter Loan

Version:

1.0

---

Constructor & Destructor Documentation

Thelen2003Muscle::Thelen2003Muscle

(

)

Default constructor.

Thelen2003Muscle::Thelen2003Muscle	(	const std::string &	aName,
		double	aMaxIsometricForce,
		double	aOptimalFiberLength,
		double	aTendonSlackLength,
		double	aPennationAngle
	)

Constructor.

Thelen2003Muscle::Thelen2003Muscle

(

const Thelen2003Muscle &

aMuscle

)

Copy constructor.

Parameters:

aMuscle

Thelen2003Muscle to be copied.

Thelen2003Muscle::~Thelen2003Muscle

(

)

[virtual]

Destructor.

---

Member Function Documentation

double Thelen2003Muscle::calcActiveForce	(	const SimTK::State &	s,
		double	aNormFiberLength
	)			const

From gmc.dt.c - calc_active_force_dt.

CALC_ACTIVE_FORCE_DT: this routine calculates the active component of force in the muscle fibers. It uses the current fiber length to interpolate the active force-length curve - described by Gaussian curve as in Thelen, JBME 2003 *

Parameters:

aNormFiberLength

Normalized length of the muscle fiber.

Returns:

The active force in the muscle fibers.

double Thelen2003Muscle::calcFiberVelocity	(	const SimTK::State &	s,
		double	aActivation,
		double	aActiveForce,
		double	aVelocityDependentForce
	)			const

From gmc_dt.c - calc_norm_fiber_velocity_dt.

CALC_NORM_FIBER_VELOCITY_DT: written by Darryl Thelen this routine calculates the normalized fiber velocity (scaled to Vmax) by inverting the muscle force-velocity-activation relationship (Thelen, JBME 2003) This equation is parameterized using the following dynamic parameters which must be specified in the muscle file Dynamic Parameters: damping - normalized passive damping in parallel with contractile element Af - velocity shape factor from Hill's equation Flen - Maximum normalized force when muscle is lengthening

Parameters:

	aActivation	Activation of the muscle.
	aActiveForce	Active force in the muscle fibers.
	aVelocityDependentForce	Force value that depends on fiber velocity.

Returns:

The velocity of the muscle fibers.

double Thelen2003Muscle::calcPassiveForce	(	const SimTK::State &	s,
		double	aNormFiberLength
	)			const

From gmc.dt.c - calc_passive_fiber_force_dt.

CALC_PASSIVE_FIBER_FORCE_DT: written by Darryl Thelen this routine calculates the passive force in the muscle fibers using an exponential-linear function instead of cubic splines. It always returns a non-zero force for all muscle lengths This equation is parameterized using the following dynamic parameters which must be specified in the muscle file Dynamic Parameters: FmaxMuscleStrain - passive muscle strain due to the application of maximum isometric muscle force KshapePassive - exponential shape factor

The normalized force due to passive stretch is given by For L < (1+maxStrain)*Lo f/f0 = exp(ks*(L-1)/maxStrain) / exp(ks)

Parameters:

aNormFiberLength

Normalized length of the muscle fiber.

Returns:

The passive force in the muscle fibers.

double Thelen2003Muscle::calcTendonForce	(	const SimTK::State &	s,
		double	aNormTendonLength
	)			const

From cmg_dt.c - calc_tendon_force_dt.

CALC_TENDON_FORCE_DT: this routine calculates the force in tendon by finding tendon strain and using it in an exponential function (JBME 2003 - Thelen) FmaxTendonStrain - Function is parameterized by the tendon strain due to maximum isometric muscle force This should be specified as a dynamic parameter in the muscle file

Parameters:

aNormTendonLength

Normalized length of the tendon.

Returns:

The force in the tendon.

double Thelen2003Muscle::computeActuation

(

const SimTK::State &

s

)

const [virtual]

Compute the actuation for the muscle.

This function assumes that computeDerivatives has already been called.

This function is based on muscle_deriv_func9 from derivs.c (old pipeline code)

Implements OpenSim::ActivationFiberLengthMuscle.

void Thelen2003Muscle::computeEquilibrium

(

SimTK::State &

s

)

const [virtual]

Compute the equilibrium states.

This method computes a fiber length for the muscle that is consistent with the muscle's activation level.

Reimplemented from OpenSim::Actuator_.

double Thelen2003Muscle::computeIsometricForce	(	SimTK::State &	s,
		double	aActivation
	)			const [virtual]

Find the force produced by an actuator (the musculotendon unit), assuming static equilibrium.

Using the total muscle-tendon length, it finds the fiber and tendon lengths so that the forces in each match. This routine takes pennation angle into account, so its definition of static equilibrium is when tendon_force = fiber_force * cos(pennation_angle). This funcion will modify the object's values for length, fiberLength, activeForce, and passiveForce.

Parameters:

aActivation

Activation of the muscle.

Returns:

The isometric force in the muscle.

Implements OpenSim::ActivationFiberLengthMuscle.

SimTK::Vector Thelen2003Muscle::computeStateVariableDerivatives

(

const SimTK::State &

s

)

const [protected, virtual]

Compute the derivatives of the muscle states.

Parameters:

	s	system state
	index

Reimplemented from OpenSim::ModelComponent.

Object * Thelen2003Muscle::copy

(

)

const [virtual]

Copy this muscle point and return a pointer to the copy.

The copy constructor for this class is used.

Returns:

Pointer to a copy of this Thelen2003Muscle.

Implements OpenSim::ActivationFiberLengthMuscle.

void Thelen2003Muscle::copyData

(

const Thelen2003Muscle &

aMuscle

)

Copy data members from one Thelen2003Muscle to another.

Parameters:

aMuscle

Thelen2003Muscle to be copied.

Reimplemented from OpenSim::ActivationFiberLengthMuscle.

void Thelen2003Muscle::createSystem

(

SimTK::MultibodySystem &

system

)

const [protected, virtual]

allocate and initialize the SimTK state for this acuator.

Reimplemented from OpenSim::ActivationFiberLengthMuscle.

virtual double OpenSim::Thelen2003Muscle::getActivationTimeConstant

(

)

const [inline, virtual]

virtual double OpenSim::Thelen2003Muscle::getAf

(

)

const [inline, virtual]

virtual double OpenSim::Thelen2003Muscle::getDamping

(

)

const [inline, virtual]

virtual double OpenSim::Thelen2003Muscle::getDeactivationTimeConstant

(

)

const [inline, virtual]

virtual double OpenSim::Thelen2003Muscle::getFlen

(

)

const [inline, virtual]

virtual double OpenSim::Thelen2003Muscle::getFmaxMuscleStrain

(

)

const [inline, virtual]

virtual double OpenSim::Thelen2003Muscle::getFmaxTendonStrain

(

)

const [inline, virtual]

virtual double OpenSim::Thelen2003Muscle::getKshapeActive

(

)

const [inline, virtual]

virtual double OpenSim::Thelen2003Muscle::getKshapePassive

(

)

const [inline, virtual]

int Thelen2003Muscle::getStateVariableYIndex

(

int

index

)

const [virtual]

Get the YIndex of a state variable allocated by this ModelComponent.

The default implementation throws an exception, so subclasses that allocate state variables must override it.

Parameters:

index

the index of the state variable (0 to getNumStateVariables()-1)

Reimplemented from OpenSim::ModelComponent.

virtual double OpenSim::Thelen2003Muscle::getVmax

(

)

const [inline, virtual]

virtual double OpenSim::Thelen2003Muscle::getVmax0

(

)

const [inline, virtual]

OpenSim::Thelen2003Muscle::OPENSIM_DECLARE_DERIVED	(	Thelen2003Muscle	,
		ActivationFiberLengthMuscle
	)

Thelen2003Muscle & Thelen2003Muscle::operator=

(

const Thelen2003Muscle &

aMuscle

)

Assignment operator.

Returns:

Reference to this object.

Reimplemented from OpenSim::ActivationFiberLengthMuscle.

bool Thelen2003Muscle::setActivationTimeConstant

(

double

aActivationTimeConstant

)

[virtual]

Set the time constant for ramping up of muscle force.

Parameters:

aActivationTimeConstant

The time constant for ramping up of muscle force.

Returns:

Whether the time constant was successfully changed.

bool Thelen2003Muscle::setAf

(

double

aAf

)

[virtual]

Set the force-velocity shape factor.

Parameters:

aAf

The force-velocity shape factor.

Returns:

Whether the shape factor was successfully changed.

bool Thelen2003Muscle::setDamping

(

double

aDamping

)

[virtual]

Set the damping factor related to maximum contraction velocity.

Parameters:

aDamping

The damping factor related to maximum contraction velocity.

Returns:

Whether the damping factor was successfully changed.

bool Thelen2003Muscle::setDeactivationTimeConstant

(

double

aDeactivationTimeConstant

)

[virtual]

Set the time constant for ramping down of muscle force.

Parameters:

aDeactivationTimeConstant

The time constant for ramping down of muscle force.

Returns:

Whether the time constant was successfully changed.

bool Thelen2003Muscle::setFlen

(

double

aFlen

)

[virtual]

Set the maximum normalized lengthening force.

Parameters:

aFlen

The maximum normalized lengthening force.

Returns:

Whether the maximum normalized lengthening force was successfully changed.

bool Thelen2003Muscle::setFmaxMuscleStrain

(

double

aFmaxMuscleStrain

)

[virtual]

Set the passive muscle strain due to maximum isometric muscle force.

Parameters:

aFmaxMuscleStrain

The passive muscle strain due to maximum isometric muscle force.

Returns:

Whether the passive muscle strain was successfully changed.

bool Thelen2003Muscle::setFmaxTendonStrain

(

double

aFmaxTendonStrain

)

[virtual]

Set the tendon strain due to maximum isometric muscle force.

Parameters:

aFmaxTendonStrain

The tendon strain due to maximum isometric muscle force.

Returns:

Whether the tendon strain was successfully changed.

bool Thelen2003Muscle::setKshapeActive

(

double

aKShapeActive

)

[virtual]

Set the shape factor for Gaussian active muscle force-length relationship.

Parameters:

aKShapeActive

The shape factor for Gaussian active muscle force-length relationship.

Returns:

Whether the shape factor was successfully changed.

bool Thelen2003Muscle::setKshapePassive

(

double

aKshapePassive

)

[virtual]

Set the shape factor for Gaussian passive muscle force-length relationship.

Parameters:

aKshapePassive

The shape factor for Gaussian passive muscle force-length relationship.

Returns:

Whether the shape factor was successfully changed.

void Thelen2003Muscle::setup

(

Model &

aModel

)

[protected, virtual]

Perform some set up functions that happen after the object has been deserialized or copied.

Parameters:

aModel

model containing this Thelen2003Muscle.

Reimplemented from OpenSim::ActivationFiberLengthMuscle.

bool Thelen2003Muscle::setVmax

(

double

aVmax

)

[virtual]

Set the maximum contraction velocity of the fibers, in optimal fiber lengths per second.

Parameters:

aVmax

The maximum contraction velocity of the fibers, in optimal fiber lengths per second.

Returns:

Whether the maximum contraction velocity was successfully changed.

bool Thelen2003Muscle::setVmax0

(

double

aVmax0

)

[virtual]

Set the maximum contraction velocity at low activation of the fibers, in optimal fiber lengths per second.

Parameters:

aVmax

The maximum contraction velocity at low activation of the fibers, in optimal fiber lengths per second.

Returns:

Whether the maximum contraction velocity was successfully changed.

---

Member Data Documentation

double& OpenSim::Thelen2003Muscle::_activationTimeConstant [protected]

PropertyDbl OpenSim::Thelen2003Muscle::_activationTimeConstantProp [protected]

Activation time constant.

double& OpenSim::Thelen2003Muscle::_af [protected]

PropertyDbl OpenSim::Thelen2003Muscle::_afProp [protected]

Force-velocity shape factor.

double& OpenSim::Thelen2003Muscle::_damping [protected]

PropertyDbl OpenSim::Thelen2003Muscle::_dampingProp [protected]

Passive damping included in the force-velocity relationship.

double& OpenSim::Thelen2003Muscle::_deactivationTimeConstant [protected]

PropertyDbl OpenSim::Thelen2003Muscle::_deactivationTimeConstantProp [protected]

Deactivation time constant.

double& OpenSim::Thelen2003Muscle::_flen [protected]

PropertyDbl OpenSim::Thelen2003Muscle::_flenProp [protected]

Maximum normalized lengthening force.

double& OpenSim::Thelen2003Muscle::_fmaxMuscleStrain [protected]

PropertyDbl OpenSim::Thelen2003Muscle::_fmaxMuscleStrainProp [protected]

Passive muscle strain due to maximum isometric muscle force.

double& OpenSim::Thelen2003Muscle::_fmaxTendonStrain [protected]

PropertyDbl OpenSim::Thelen2003Muscle::_fmaxTendonStrainProp [protected]

Tendon strain due to maximum isometric muscle force.

double& OpenSim::Thelen2003Muscle::_kShapeActive [protected]

PropertyDbl OpenSim::Thelen2003Muscle::_kShapeActiveProp [protected]

Shape factor for Gaussian active muscle force-length relationship.

double& OpenSim::Thelen2003Muscle::_kShapePassive [protected]

PropertyDbl OpenSim::Thelen2003Muscle::_kShapePassiveProp [protected]

Exponential shape factor for passive force-length relationship.

double& OpenSim::Thelen2003Muscle::_vmax [protected]

double& OpenSim::Thelen2003Muscle::_vmax0 [protected]

PropertyDbl OpenSim::Thelen2003Muscle::_vmax0Prop [protected]

Max contraction velocity at low activation.

PropertyDbl OpenSim::Thelen2003Muscle::_vmaxProp [protected]

Max contraction velocity full activation in fiber lengths per second.

const int Thelen2003Muscle::STATE_ACTIVATION = 0 [static, protected]

Reimplemented from OpenSim::ActivationFiberLengthMuscle.

const int Thelen2003Muscle::STATE_FIBER_LENGTH = 1 [static, protected]

Reimplemented from OpenSim::ActivationFiberLengthMuscle.

---

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

• OpenSim/Actuators/Thelen2003Muscle.h
• OpenSim/Actuators/Thelen2003Muscle.cpp