artisynth.core.materials

Class Thelen2003AxialMuscle

java.lang.Object

artisynth.core.materials.MaterialBase

artisynth.core.materials.AxialMaterial

artisynth.core.materials.AxialMuscleMaterialBase

artisynth.core.materials.EquilibriumAxialMuscle

artisynth.core.materials.Thelen2003AxialMuscle

All Implemented Interfaces:

HasMaterialState, HasNumericState, PostScannable, ScalableUnits, java.lang.Cloneable, CompositeProperty, HasProperties, Clonable, Scannable

public class Thelen2003AxialMuscle
extends EquilibriumAxialMuscle

Implements the Thelen2003Muscle from OpenSim. One should consult the OpenSim API documentation for a detailed explanation of the muscle model's parameters and behavior. The names of this class's muscle parameter properties should match the OpenSim equivalents closely enough to be unambiguous.

The force velocity curve has been modified to remove a derivative discontinuity at vn = 0, where vn is the normalized velocity.

Equilbrium muscle models contain a muscle component and tendon component in series. The muscle and tendon lengths sum to the combined length l that is supplied the the method EquilibriumAxialMuscle.computeF(double, double, double, double), which computes the muacle tension, while the equilibrum condition implies that the tension from the muscle and tendon components must both equal the value returned by EquilibriumAxialMuscle.computeF(double, double, double, double). To implement this, we store the muscle length as a state variable which is updated at each time step to ensure that the equilbrium condition is satisfied. We do this differently from OpenSim: rather than solving for and then integrating the muscle velocity, the velocity inferred by dividing the cnange in muscle length by the time step size. This avoids the singularity that arises in the OpenSim method at zero activation, and so removes the need for always ensuring that the activation is non-zero.

We also a support, via the rigidTendon property, a mode where the tendon is considered to be rigid (via the rigidTendon property), which simplifies the computation in situations where this approximation is acceptable.

Field Summary

Fields

Modifier and Type	Field and Description
static double	DEFAULT_AF
static double	DEFAULT_FLEN
static double	DEFAULT_FMAX_MUSCLE_STRAIN
static double	DEFAULT_FMAX_TENDON_STRAIN
static double	DEFAULT_FV_LINEAR_EXTRAP_THRESHOLD
static double	DEFAULT_K_SHAPE_ACTIVE
static double	DEFAULT_K_SHAPE_PASSIVE
static double	DEFAULT_MAX_PENNATION_ANGLE
static double	DEFAULT_MINIMUM_ACTIVATION
static PropertyList	myProps

Fields inherited from class artisynth.core.materials.EquilibriumAxialMuscle

debug, DEFAULT_COMPUTE_LMDOT_FROM_LDOT, DEFAULT_FIBRE_DAMPING, DEFAULT_IGNORE_FORCE_VELOCITY, DEFAULT_MAX_CONTRACTION_VELOCITY, DEFAULT_MAX_ISO_FORCE, DEFAULT_MUSCLE_LENGTH, DEFAULT_OPT_FIBRE_LENGTH, DEFAULT_OPT_PENNATION_ANGLE, DEFAULT_RIGID_TENDON, DEFAULT_TENDON_SLACK_LENGTH, useFindLm, useNewtonSolver, vmFromTendon

Constructor Summary

Constructors

Constructor and Description
Thelen2003AxialMuscle()
Thelen2003AxialMuscle(double fmax, double lopt, double tslack, double optPenAng)

Method Summary

Modifier and Type	Method and Description
Thelen2003AxialMuscle	clone() Returns a clone of this composite property.
double	getAf()
PropertyList	getAllPropertyInfo() Returns a list giving static information about all properties exported by this object.
double	getFlen()
double	getFmaxMuscleStrain()
double	getFmaxTendonStrain()
double	getFvLinearExtrapThreshold()
double	getKShapeActive()
double	getKShapePassive()
double	getMaxPennationAngle()
double	getMinimumActivation()
static void	main(java.lang.String[] args)
void	setAf(double af)
void	setFlen(double flen)
void	setFmaxMuscleStrain(double fts)
void	setFmaxTendonStrain(double fts)
void	setFvLinearExtrapThreshold(double thresh)
void	setKShapeActive(double kshape)
void	setKShapePassive(double kshape)
void	setMaxPennationAngle(double ang)
void	setMinimumActivation(double mina)

Methods inherited from class artisynth.core.materials.EquilibriumAxialMuscle

advanceState, computeDFdl, computeDFdldot, computeF, computeG, computeLmWithConstantVm, computeLmWithVmFromLm, computePassiveF, computeVmFromLdot, fibreToMuscleLength, getComputeLmDotFromLDot, getFibreDamping, getIgnoreForceVelocity, getIgnoreTendonCompliance, getLength, getMaxContractionVelocity, getMaxIsoForce, getMuscleLength, getOptFibreLength, getOptPennationAngle, getState, getStateVersion, getTendonLength, getTendonSlackLength, hasRigidTendon, hasState, initializeLmPrevFromLdot, isDFdldotZero, requiresAdvance, scaleDistance, scaleMass, setComputeLmDotFromLDot, setFibreDamping, setIgnoreForceVelocity, setIgnoreTendonCompliance, setLength, setMaxContractionVelocity, setMaxIsoForce, setMuscleLength, setOptFibreLength, setOptPennationAngle, setRigidTendon, setState, setTendonSlackLength, writeActiveForceLengthCurve, writeForceVelocityCurve, writePassiveForceLengthCurve, writeTendonForceLengthCurve

Methods inherited from class artisynth.core.materials.AxialMaterial

equals, equals, getSubClasses

Methods inherited from class artisynth.core.materials.MaterialBase

advanceState, createStateObject, getProperty, getPropertyHost, getPropertyInfo, hasProperty, hasSymmetricTangent, isWritable, postscan, scan, setPropertyHost, setPropertyInfo, symmetryOrStateChanged, updateMaterial, write, writeItems

Methods inherited from class java.lang.Object

getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface artisynth.core.modelbase.HasNumericState

getAuxVarDerivative, getAuxVarState, numAuxVars, setAuxVarState

Field Detail

DEFAULT_FMAX_TENDON_STRAIN

public static double DEFAULT_FMAX_TENDON_STRAIN

DEFAULT_FMAX_MUSCLE_STRAIN

public static double DEFAULT_FMAX_MUSCLE_STRAIN

DEFAULT_K_SHAPE_ACTIVE

public static double DEFAULT_K_SHAPE_ACTIVE

DEFAULT_K_SHAPE_PASSIVE

public static double DEFAULT_K_SHAPE_PASSIVE

DEFAULT_AF

public static double DEFAULT_AF

DEFAULT_FLEN

public static double DEFAULT_FLEN

DEFAULT_FV_LINEAR_EXTRAP_THRESHOLD

public static double DEFAULT_FV_LINEAR_EXTRAP_THRESHOLD

DEFAULT_MAX_PENNATION_ANGLE

public static double DEFAULT_MAX_PENNATION_ANGLE

DEFAULT_MINIMUM_ACTIVATION

public static double DEFAULT_MINIMUM_ACTIVATION

myProps

public static PropertyList myProps

Constructor Detail

Thelen2003AxialMuscle

public Thelen2003AxialMuscle()

Thelen2003AxialMuscle

public Thelen2003AxialMuscle(double fmax,
                             double lopt,
                             double tslack,
                             double optPenAng)

Method Detail

getAllPropertyInfo

public PropertyList getAllPropertyInfo()

Description copied from interface: HasProperties

Returns a list giving static information about all properties exported by this object.

Specified by:

getAllPropertyInfo in interface HasProperties

Overrides:

getAllPropertyInfo in class EquilibriumAxialMuscle

Returns:

static information for all exported properties

getFmaxTendonStrain

public double getFmaxTendonStrain()

setFmaxTendonStrain

public void setFmaxTendonStrain(double fts)

getFmaxMuscleStrain

public double getFmaxMuscleStrain()

setFmaxMuscleStrain

public void setFmaxMuscleStrain(double fts)

getKShapeActive

public double getKShapeActive()

setKShapeActive

public void setKShapeActive(double kshape)

getKShapePassive

public double getKShapePassive()

setKShapePassive

public void setKShapePassive(double kshape)

getAf

public double getAf()

setAf

public void setAf(double af)

getFlen

public double getFlen()

setFlen

public void setFlen(double flen)

getFvLinearExtrapThreshold

public double getFvLinearExtrapThreshold()

setFvLinearExtrapThreshold

public void setFvLinearExtrapThreshold(double thresh)

getMaxPennationAngle

public double getMaxPennationAngle()

setMaxPennationAngle

public void setMaxPennationAngle(double ang)

getMinimumActivation

public double getMinimumActivation()

setMinimumActivation

public void setMinimumActivation(double mina)

clone

public Thelen2003AxialMuscle clone()

Description copied from interface: CompositeProperty

Returns a clone of this composite property.

Specified by:

clone in interface CompositeProperty

Specified by:

clone in interface Clonable

Overrides:

clone in class AxialMaterial

Returns:

clone of this property

main

public static void main(java.lang.String[] args)
                 throws java.io.IOException

Throws:

java.io.IOException