artisynth.core.materials

Class Millard2012AxialMuscle

java.lang.Object

artisynth.core.materials.MaterialBase

artisynth.core.materials.AxialMaterial

artisynth.core.materials.AxialMuscleMaterialBase

artisynth.core.materials.EquilibriumAxialMuscle

artisynth.core.materials.Millard2012AxialMuscle

All Implemented Interfaces:

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

public class Millard2012AxialMuscle
extends EquilibriumAxialMuscle
implements HasNumericState

Implements the Millard2012EquilibriumMuscle 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.

Equilbrium mus1cle 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.

As with the OpenSim model, 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_DEFAULT_MIN_FLC_VALUE
static double	DEFAULT_MAX_PENNATION_ANGLE
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
Millard2012AxialMuscle()
Millard2012AxialMuscle(double fmax, double lopt, double tslack, double optPenAng)

Method Summary

Modifier and Type	Method and Description
Millard2012AxialMuscle	clone() Returns a clone of this composite property.
static CubicHermiteSpline1d	createActiveForceLengthCurve(double minActiveNormFiberLength, double transitionNormFiberLength, double maxActiveNormFiberLength, double shallowAscendingSlope, double minimumValue)
static CubicHermiteSpline1d	createForceVelocityCurve(double concentricSlopeAtVmax, double concentricSlopeNearVmax, double isometricSlope, double eccentricSlopeAtVmax, double eccentricSlopeNearVmax, double maxEccentricVelocityForceMultiplier, double concentricCurviness, double eccentricCurviness)
static CubicHermiteSpline1d	createPassiveForceLengthCurve(double strainAtZeroForce, double strainAtOneNormForce, double stiffnessAtLowForce, double stiffnessAtOneNormForce, double curviness)
static CubicHermiteSpline1d	createTendonForceLengthCurve(double strainAtOneNormForce, double stiffnessAtOneNormForce, double normForceAtToeEnd, double curviness)
CubicHermiteSpline1d	getActiveForceLengthCurve() Queries the active force length curve for this material.
PropertyList	getAllPropertyInfo() Returns a list giving static information about all properties exported by this object.
static CubicHermiteSpline1d	getDefaultActiveForceLengthCurve()
static CubicHermiteSpline1d	getDefaultForceVelocityCurve()
static double	getDefaultMinFlcValue()
static CubicHermiteSpline1d	getDefaultPassiveForceLengthCurve()
static CubicHermiteSpline1d	getDefaultTendonForceLengthCurve()
CubicHermiteSpline1d	getForceVelocityCurve() Queries the force velocity curve for this material.
double	getMaxPennationAngle()
CubicHermiteSpline1d	getPassiveForceLengthCurve() Queries the passive force length curve for this material.
CubicHermiteSpline1d	getTendonForceLengthCurve() Queries the tendon force length curve for this material.
static void	main(java.lang.String[] args)
void	setActiveForceLengthCurve(CubicHermiteSpline1d curve) Sets the active force length curve for this material, or removes it if curve is set to null.
static void	setDefaultMinFlcValue(double min)
void	setForceVelocityCurve(CubicHermiteSpline1d curve) Sets the force velocity curve for this material, or removes it if curve is set to null.
void	setMaxPennationAngle(double ang)
void	setPassiveForceLengthCurve(CubicHermiteSpline1d curve) Sets the passive force length curve for this material, or removes it if curve is set to null.
void	setTendonForceLengthCurve(CubicHermiteSpline1d curve) Sets the tendon force length curve for this material, or removes it if curve is set to null.
void	writeItems(java.io.PrintWriter pw, NumberFormat fmt, CompositeComponent ancestor)

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, 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

Methods inherited from class java.lang.Object

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

Methods inherited from interface artisynth.core.modelbase.HasNumericState

advanceState, getAuxVarDerivative, getAuxVarState, getState, getStateVersion, hasState, numAuxVars, requiresAdvance, setAuxVarState, setState

Field Detail

DEFAULT_MAX_PENNATION_ANGLE

public static double DEFAULT_MAX_PENNATION_ANGLE

DEFAULT_DEFAULT_MIN_FLC_VALUE

public static double DEFAULT_DEFAULT_MIN_FLC_VALUE

myProps

public static PropertyList myProps

Constructor Detail

Millard2012AxialMuscle

public Millard2012AxialMuscle()

Millard2012AxialMuscle

public Millard2012AxialMuscle(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

getDefaultActiveForceLengthCurve

public static CubicHermiteSpline1d getDefaultActiveForceLengthCurve()

getDefaultPassiveForceLengthCurve

public static CubicHermiteSpline1d getDefaultPassiveForceLengthCurve()

getDefaultForceVelocityCurve

public static CubicHermiteSpline1d getDefaultForceVelocityCurve()

getDefaultTendonForceLengthCurve

public static CubicHermiteSpline1d getDefaultTendonForceLengthCurve()

getMaxPennationAngle

public double getMaxPennationAngle()

setMaxPennationAngle

public void setMaxPennationAngle(double ang)

getDefaultMinFlcValue

public static double getDefaultMinFlcValue()

setDefaultMinFlcValue

public static void setDefaultMinFlcValue(double min)

getActiveForceLengthCurve

public CubicHermiteSpline1d getActiveForceLengthCurve()

Queries the active force length curve for this material. Returns null if this curve has not been set.

Returns:

current active force length curve

setActiveForceLengthCurve

public void setActiveForceLengthCurve(CubicHermiteSpline1d curve)

Sets the active force length curve for this material, or removes it if curve is set to null. Any specified curve is copied internally.

Parameters:

curve - new active force length curve

getPassiveForceLengthCurve

public CubicHermiteSpline1d getPassiveForceLengthCurve()

Queries the passive force length curve for this material. Returns null if this curve has not been set.

Returns:

current passive force length curve

setPassiveForceLengthCurve

public void setPassiveForceLengthCurve(CubicHermiteSpline1d curve)

Sets the passive force length curve for this material, or removes it if curve is set to null. Any specified curve is copied internally.

Parameters:

curve - new passive force length curve

getTendonForceLengthCurve

public CubicHermiteSpline1d getTendonForceLengthCurve()

Queries the tendon force length curve for this material. Returns null if this curve has not been set.

Returns:

current tendon force length curve

setTendonForceLengthCurve

public void setTendonForceLengthCurve(CubicHermiteSpline1d curve)

Sets the tendon force length curve for this material, or removes it if curve is set to null. Any specified curve is copied internally.

Parameters:

curve - new tendon force length curve

getForceVelocityCurve

public CubicHermiteSpline1d getForceVelocityCurve()

Queries the force velocity curve for this material. Returns null if this curve has not been set.

Returns:

current force velocity curve

setForceVelocityCurve

public void setForceVelocityCurve(CubicHermiteSpline1d curve)

Sets the force velocity curve for this material, or removes it if curve is set to null. Any specified curve is copied internally.

Parameters:

curve - new force velocity curve

createActiveForceLengthCurve

public static CubicHermiteSpline1d createActiveForceLengthCurve(double minActiveNormFiberLength,
                                                                double transitionNormFiberLength,
                                                                double maxActiveNormFiberLength,
                                                                double shallowAscendingSlope,
                                                                double minimumValue)

createForceVelocityCurve

public static CubicHermiteSpline1d createForceVelocityCurve(double concentricSlopeAtVmax,
                                                            double concentricSlopeNearVmax,
                                                            double isometricSlope,
                                                            double eccentricSlopeAtVmax,
                                                            double eccentricSlopeNearVmax,
                                                            double maxEccentricVelocityForceMultiplier,
                                                            double concentricCurviness,
                                                            double eccentricCurviness)

createTendonForceLengthCurve

public static CubicHermiteSpline1d createTendonForceLengthCurve(double strainAtOneNormForce,
                                                                double stiffnessAtOneNormForce,
                                                                double normForceAtToeEnd,
                                                                double curviness)

createPassiveForceLengthCurve

public static CubicHermiteSpline1d createPassiveForceLengthCurve(double strainAtZeroForce,
                                                                 double strainAtOneNormForce,
                                                                 double stiffnessAtLowForce,
                                                                 double stiffnessAtOneNormForce,
                                                                 double curviness)

writeItems

public void writeItems(java.io.PrintWriter pw,
                       NumberFormat fmt,
                       CompositeComponent ancestor)
                throws java.io.IOException

Overrides:

writeItems in class MaterialBase

Throws:

java.io.IOException

clone

public Millard2012AxialMuscle 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