artisynth.core.mechmodels

Class JointLimitForce

java.lang.Object

artisynth.core.modelbase.ModelComponentBase

artisynth.core.mechmodels.JointLimitForce

All Implemented Interfaces:

ForceComponent, ForceEffector, ModelComponent, PostScannable, java.lang.Cloneable, HasProperties, HierarchyNode, Scannable

public class JointLimitForce
extends ModelComponentBase
implements ForceComponent

Applies a restoring force to a joint coordinate when its value falls outside a specfied range. This is used to implement ``soft'' limits on joint coordinates.

The applied force is nominally linear. If x and v are the coordinate value and speed, then for an upper limit ul the force is nominally given by

 f = - Ku (x - ul) - Du v
 

where Ku and Du are the stiffness and damping coefficients associated with the upper limit, while for a lower limit ll it is

 f = - Kl (ll - x) - Dl v
 

where Kl and Dl are the coefficients for the lower limit. However, each limit can also be associated with a transition region tau. If tau > 0, then the restoring force is applied more gradually in the intervals [ul, ul+tau] (for the upper limit) and [ll-tau, ll] (for the lower limit).

Nested Class Summary

Nested classes/interfaces inherited from interface artisynth.core.modelbase.ModelComponent

ModelComponent.NavpanelVisibility

Field Summary

Fields

Modifier and Type	Field and Description
static double	DEFAULT_DAMPING
static double	DEFAULT_LIMIT
static double	DEFAULT_STIFFNESS
static double	DEFAULT_TRANSITION
static PropertyList	myProps

Fields inherited from class artisynth.core.modelbase.ModelComponentBase

enforceUniqueCompositeNames, enforceUniqueNames, myNumber, NULL_OBJ, useCompactPathNames

Constructor Summary

Constructors

Constructor and Description
JointLimitForce()
JointLimitForce(JointCoordinateHandle ch)
JointLimitForce(java.lang.String name, JointCoordinateHandle ch)

Method Summary

Modifier and Type	Method and Description
void	addPosJacobian(SparseNumberedBlockMatrix M, double s) Scales the components of the position Jacobian associated with this force effector and adds it to the supplied solve matrix M.
void	addSolveBlocks(SparseNumberedBlockMatrix M) Adds any needed blocks to a solve matrix in order to accomodate the Jacobian terms associated with this force effector.
void	addVelJacobian(SparseNumberedBlockMatrix M, double s) Scales the components of the velocity Jacobian associated with this force effector and adds it to the supplied solve matrix M.
void	applyForces(double t) Adds forces to the components affected by this force effector at a particular time.
PropertyList	getAllPropertyInfo() Returns a list giving static information about all properties exported by this object.
int	getJacobianType() Returns a code indicating the matrix type that results when the Jacobian terms of this force effector are added to the solve matrix.
double	getLowerDamping() Queries the damping parameter for the lower limit restoring force.
double	getLowerLimit() Queries the lower limit for the joint coordinate.
double	getLowerStiffness() Queries the stiffness for the lower limit restoring force.
double	getLowerTransition() Queries the transition region size for the lower limit restoring force.
double	getUpperDamping() Queries the damping parameter for the upper limit restoring force.
double	getUpperLimit() Queries the upper limit for the joint coordinate.
double	getUpperStiffness() Queries the stiffness for the upper limit restoring force.
double	getUpperTransition() Queries the transition region size for the upper limit restoring force.
void	setLower(double ll, double k, double d, double tau) Set all the lower limit parameters.
void	setLowerDamping(double d) Sets the damping parameter for the lower limit restoring force.
void	setLowerLimit(double ll) Sets the lower limit for the joint coordinate, beyond which a restoring force will be applied.
void	setLowerStiffness(double k) Sets the stiffness for the lower limit restoring force.
void	setLowerTransition(double tau) Sets the transition region size for the lower limit restoring force.
void	setUpper(double ul, double k, double d, double tau) Set all the upper limit parameters.
void	setUpperDamping(double d) Sets the damping parameter for the upper limit restoring force.
void	setUpperLimit(double ul) Sets the upper limit for the joint coordinate, beyond which a restoring force will be applied.
void	setUpperStiffness(double k) Sets the stiffness for the upper limit restoring force.
void	setUpperTransition(double tau) Sets the transition region size for the upper limit restoring force.

Methods inherited from class artisynth.core.modelbase.ModelComponentBase

checkFlag, checkName, checkNameUniqueness, clearFlag, clone, connectToHierarchy, copy, createTempFlag, disconnectFromHierarchy, getChildren, getGrandParent, getHardReferences, getName, getNameRange, getNavpanelVisibility, getNavpanelVisibility, getNumber, getParent, getProperty, getSoftReferences, hasChildren, hasState, isFixed, isMarked, isScanning, isSelected, isWritable, makeValidName, makeValidName, notifyParentOfChange, postscan, printReferences, recursivelyContained, recursivelyContains, removeTempFlag, scan, setFixed, setFlag, setMarked, setName, setNavpanelVisibility, setNavpanelVisibility, setNumber, setParent, setScanning, setSelected, setWritable, updateReferences, write

Methods inherited from class java.lang.Object

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

Methods inherited from interface artisynth.core.modelbase.ModelComponent

connectToHierarchy, disconnectFromHierarchy, getHardReferences, getName, getNavpanelVisibility, getNumber, getParent, getSoftReferences, hasState, isFixed, isMarked, isSelected, notifyParentOfChange, scan, setFixed, setMarked, setName, setNumber, setParent, setSelected, setWritable, updateReferences

Methods inherited from interface maspack.properties.HasProperties

getProperty

Methods inherited from interface maspack.properties.HierarchyNode

getChildren, hasChildren

Methods inherited from interface artisynth.core.modelbase.PostScannable

postscan

Methods inherited from interface maspack.util.Scannable

isWritable, write

Field Detail

DEFAULT_LIMIT

public static final double DEFAULT_LIMIT

See Also:

Constant Field Values

DEFAULT_STIFFNESS

public static final double DEFAULT_STIFFNESS

See Also:

Constant Field Values

DEFAULT_DAMPING

public static final double DEFAULT_DAMPING

See Also:

Constant Field Values

DEFAULT_TRANSITION

public static final double DEFAULT_TRANSITION

See Also:

Constant Field Values

myProps

public static PropertyList myProps

Constructor Detail

JointLimitForce

public JointLimitForce()

JointLimitForce

public JointLimitForce(JointCoordinateHandle ch)

JointLimitForce

public JointLimitForce(java.lang.String name,
                       JointCoordinateHandle ch)

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 ModelComponentBase

Returns:

static information for all exported properties

setUpperLimit

public void setUpperLimit(double ul)

Sets the upper limit for the joint coordinate, beyond which a restoring force will be applied. The default value is infinity (no upper limit).

Parameters:

ul - new upper coordinate limit,

getUpperLimit

public double getUpperLimit()

Queries the upper limit for the joint coordinate.

Returns:

upper coordinate limit,

setUpperStiffness

public void setUpperStiffness(double k)

Sets the stiffness for the upper limit restoring force. The default value is 0 (no stiffness force).

Parameters:

k - new upper limit stiffness,

getUpperStiffness

public double getUpperStiffness()

Queries the stiffness for the upper limit restoring force.

Returns:

upper limit stiffness,

setUpperDamping

public void setUpperDamping(double d)

Sets the damping parameter for the upper limit restoring force. The default value is 0 (no damping force).

Parameters:

d - new upper limit damping

getUpperDamping

public double getUpperDamping()

Queries the damping parameter for the upper limit restoring force.

Returns:

upper limit damping

setUpperTransition

public void setUpperTransition(double tau)

Sets the transition region size for the upper limit restoring force. The default valus is 0 (no transition region).

Parameters:

tau - new upper limit transition region

getUpperTransition

public double getUpperTransition()

Queries the transition region size for the upper limit restoring force.

Returns:

upper limit transition region

setLowerLimit

public void setLowerLimit(double ll)

Sets the lower limit for the joint coordinate, beyond which a restoring force will be applied. The default value is -infinity (no lower limit).

Parameters:

ll - new lower coordinate limit,

getLowerLimit

public double getLowerLimit()

Queries the lower limit for the joint coordinate.

Returns:

lower coordinate limit,

setLowerStiffness

public void setLowerStiffness(double k)

Sets the stiffness for the lower limit restoring force. The default value is 0 (no stiffness force).

Parameters:

k - new lower limit stiffness,

getLowerStiffness

public double getLowerStiffness()

Queries the stiffness for the lower limit restoring force.

Returns:

lower limit stiffness,

setLowerDamping

public void setLowerDamping(double d)

Sets the damping parameter for the lower limit restoring force. The default value is 0 (no damping force).

Parameters:

d - new lower limit damping

getLowerDamping

public double getLowerDamping()

Queries the damping parameter for the lower limit restoring force.

Returns:

lower limit damping

setLowerTransition

public void setLowerTransition(double tau)

Sets the transition region size for the lower limit restoring force. The default valus is 0 (no transition region).

Parameters:

tau - new lower limit transition region

getLowerTransition

public double getLowerTransition()

Queries the transition region size for the lower limit restoring force.

Returns:

lower limit transition region

setUpper

public void setUpper(double ul,
                     double k,
                     double d,
                     double tau)

Set all the upper limit parameters.

Parameters:

ul - upper limit

k - stiffness

d - damping factor

tau - transition region size

setLower

public void setLower(double ll,
                     double k,
                     double d,
                     double tau)

Set all the lower limit parameters.

Parameters:

ll - upper limit

k - stiffness

d - damping factor

tau - transition region size

applyForces

public void applyForces(double t)

Adds forces to the components affected by this force effector at a particular time. Component forces should be added and not set, since other forces may be added to the same components by other force effectors.

Specified by:

applyForces in interface ForceEffector

Parameters:

t - time (seconds)

addSolveBlocks

public void addSolveBlocks(SparseNumberedBlockMatrix M)

Adds any needed blocks to a solve matrix in order to accomodate the Jacobian terms associated with this force effector. In general, blocks will be need to be added at locations given by the block indices (bi, bj), where bi and bj correspond to the solve indices (as returned by getSolveIndex) for all dynamic or attached components affected by this force effector.

Specified by:

addSolveBlocks in interface ForceEffector

Parameters:

M - solve matrix to which blocks should be added

addPosJacobian

public void addPosJacobian(SparseNumberedBlockMatrix M,
                           double s)

Scales the components of the position Jacobian associated with this force effector and adds it to the supplied solve matrix M.

M is guaranteed to be the same matrix supplied in the most recent call to addSolveBlocks, and so implementations may choose to cache the relevant matrix blocks from that call, instead of retrieving them directly from M.

Specified by:

addPosJacobian in interface ForceEffector

Parameters:

M - solve matrix to which scaled position Jacobian is to be added

s - scaling factor for position Jacobian

addVelJacobian

public void addVelJacobian(SparseNumberedBlockMatrix M,
                           double s)

Scales the components of the velocity Jacobian associated with this force effector and adds it to the supplied solve matrix M.

M is guaranteed to be the same matrix supplied in the most recent call to addSolveBlocks, and so implementations may choose to cache the relevant matrix blocks from that call, instead of retrieving them directly from M.

Specified by:

addVelJacobian in interface ForceEffector

Parameters:

M - solve matrix to which scaled velocity Jacobian is to be added

s - scaling factor for velocity Jacobian

getJacobianType

public int getJacobianType()

Returns a code indicating the matrix type that results when the Jacobian terms of this force effector are added to the solve matrix. This should be a logical or-ing of either Matrix.SYMMETRIC or Matrix.POSITIVE_DEFINITE. The former should be set if adding the Jacobian terms preserves symmetry, and the latter should be set if positive definiteness if preserved. Both should be set if there is no Jacobian for this effector (i.e., the Jacobian methods are not implemented). Matrix types from all the force effectors are logically and-ed together to determine the type for the entire solve matrix.

Specified by:

getJacobianType in interface ForceEffector

Returns:

solve matrix type resulting from adding Jacobian terms