---

rdSetPoint Class Reference

A class that supports a contact force with a moving set point or spring zero. More...

#include <rdSetPoint.h>

Inheritance diagram for rdSetPoint:

List of all members.

Public Member Functions
	rdSetPoint (int aBodyA=0, int aBodyB=0, int aNYP=3)
	Default constructor.
	rdSetPoint (IDOM_Element *aElement, int aNYP=3)
	Construct an actuator from an XML node.
	rdSetPoint (const rdSetPoint &aContact)
	Copy constructor.
virtual	~rdSetPoint ()
	Destructor.
rdSetPoint &	operator= (const rdSetPoint &aSetPoint)
	Assignment operator.
virtual void	setPseudoStates (const double aYP[])
	Set the current values of the pseudostates.
virtual void	getPseudoStates (double rYP[]) const
	Get the current values of the pseudostates.
void	setTangentialStiffness (double aKTP)
	Set tangential stiffness.
double	getTangentialStiffness () const
	Get tangential stiffness.
void	setTangentialViscosity (double aKTV)
	Set tangential viscosity.
double	getTangentialViscosity () const
	Get tangential viscosity.
void	setFriction (double aMU)
	Set friction coefficient.
double	getFriction () const
	Get friction coefficient.
virtual void	updatePseudoStates ()
	Update the pseudostates.
virtual bool	check () const
	Check that this force actuator has a valid set of states.
double	computeTangentialForce (double aNormalForce, double rTangentForce[3], double rDFFric[3])
	Compute the tangential contact force exerted on BodyB expressed in the local frame of BodyA.
bool	computeNewSetPoint (double aTangentForce, double rSetPoint[3]) const
	Compute the setpoint (PointA) so that it is consistent with the displacement of PointB amd the elastic properties of the tangential spring.
virtual void	updateObject (bool aDeep=true)
	Update this object based on its XML node.
virtual void	updateNode (bool aDeep=true)
	Update the XML node representing this object.
virtual void	generateNode (IDOM_Element *aParent)
	Generate an XML node representing this object.
void	updateData ()
	Update the member data of this object based on its XML node.
Static Public Attributes
const char	PROP_TANGENTIAL_STIFFNESS [] = "tangential_stiffness"
const char	PROP_TANGENTIAL_VISCOSITY [] = "tangential_viscosity"
const char	PROP_FRICTION [] = "coefficient_of_friction"
Protected Attributes
double	_mu
	Coefficient of friction.
Private Member Functions
void	setNull ()
	Set the data members of this actuator to their null values.

---

Detailed Description

A class that supports a contact force with a moving set point or spring zero.

The set point moves on the body whose direction and surface normal are active.

Author:

Frank C. Anderson

Version:

1.0

---

Constructor & Destructor Documentation

rdSetPoint::rdSetPoint (  int  aBodyA = 0, int  aBodyB = 0, int  aNYP = 3 )

Default constructor. rdSetPoint has three pseudo-states, which are the coordinates of contact PointA. Derived classes should be aware of this. Parameters: aBodyA  Contact BodyA. aBodyB  Contact BodyB. aNYP  Number of pseudo-states (3, by default).

rdSetPoint::rdSetPoint (  IDOM_Element *  aElement, int  aNYP = 3 )

Construct an actuator from an XML node. rdSetPoint has three pseudo-states, which are the coordinates of contact PointA. Derived classes should be aware of this. Parameters: aElement  XML node representing this setpoint object. aNYP  Number of pseudo-states (3, by default).

rdSetPoint::rdSetPoint (  const rdSetPoint &  aContact  )

Copy constructor. Parameters: aForce  Force to be copied.

---

Member Function Documentation

bool rdSetPoint::computeNewSetPoint (  double  aTangentForce, double  rSetPoint[3] )  const

Compute the setpoint (PointA) so that it is consistent with the displacement of PointB amd the elastic properties of the tangential spring. The viscous properties are not considered in this calculation. Parameters: aNormalForce  Normal force. rSetPoint  Setpoint (PointA) in the local frame of BodyA. Returns: True if a new set point was computed, False otherwise.

double rdSetPoint::computeTangentialForce (  double  aNormalForce, double  rTangentForce[3], double  rDFFric[3] )

Compute the tangential contact force exerted on BodyB expressed in the local frame of BodyA. Note that because of damping, the tangential force vector does not necessarily lie along the line directed from PointA to PointB. This method returns the correction made to the tangential force in order to maintain friction constraints. NOTE that this method neither sets the tangential force or friction correction in base class rdForce (rdForce::_ftA and rdForce::_dfFric). It is left to derived classes to set these member variables. This method does set the values of the elastic and viscous components of the tangent force. Corrections are not made to these quantities to enforce frictional constraints. Only the resultant tangential force has been changed to satisfy friction constraints. Parameters: aNormalForce  Normal force currently exerted by the contact force. The tangential force is not allowed to exceed the coefficient of friction times the normal force. rFT  Total tangential force exerted on BodyA expressed in the local frame of BodyA. rDFFric  Change in the force exerted on BodyA to enforce friction constraints expressed in the local frame of BodyA (i.e., rDFFric = rTangentForce - TangentForce(uncorrected), where |rTangentForce| = mu * aNormalForce). If no correction is needed rDFFric = {0,0,0}. Returns: Magnitude of the tangential force.

void rdSetPoint::generateNode (  IDOM_Element *  aParent  )  [virtual]

Generate an XML node representing this object. Parameters: aParent  Intended parent of the node to be generated. If aParent is NULL, the intent is for this object to serve as the root element of a new document. See also: rdObject::generateNode() Reimplemented from rdContactForce. Reimplemented in rdLinearSetPoint, and rdPolynomialSetPoint.

double rdSetPoint::getFriction (   )  const

Get friction coefficient. Returns: Tangent viscosity.

virtual void rdSetPoint::getPseudoStates (  double  rYP[]  )  const [virtual]

Get the current values of the pseudostates. Parameters: rYP  Array of pseudostate values. Reimplemented from rdActuator.

double rdSetPoint::getTangentialStiffness (   )  const

Get tangential stiffness. Returns: Tangential stiffness.

double rdSetPoint::getTangentialViscosity (   )  const

Get tangential viscosity. Returns: Tangential viscosity.

rdSetPoint & rdSetPoint::operator= (  const rdSetPoint &  aSetPoint  )

Assignment operator. Returns: Reference to this object.

void rdSetPoint::setFriction (  double  aMU  )

Set friction coefficient. Sliding occurs when the tangential force exceeds the product of the fricitonal coefficient and the normal force. Parameters: aMU  Coefficient of Friction. Must be positive. If aMU is negative, the fricition coefficient is set to 0.0. A fricition coefficient greater than 1.0 corresponds to stiction.

virtual void rdSetPoint::setPseudoStates (  const double  aYP[]  )  [virtual]

Set the current values of the pseudostates. Parameters: aYP  Array of pseudostate values. Reimplemented from rdActuator.

void rdSetPoint::setTangentialStiffness (  double  aKTP  )

Set tangential stiffness. Parameters: aKTP  Tangential stiffness- must be positive.

void rdSetPoint::setTangentialViscosity (  double  aKTV  )

Set tangential viscosity. Parameters: aKTV  Tangential viscosity- must be positive.

void rdSetPoint::updateData (   )

Update the member data of this object based on its XML node. Member objects (children) are not updated. Reimplemented from rdContactForce. Reimplemented in rdLinearSetPoint, and rdPolynomialSetPoint.

void rdSetPoint::updateNode (  bool  aDeep = true  )  [virtual]

Update the XML node representing this object. Parameters: aDeep  If true, update the XML node of this object AND the XML nodes of all class members that are rdObjects (child nodes); if false, update only the XML node of this object without updating the XML nodes of its children. Reimplemented from rdContactForce. Reimplemented in rdLinearSetPoint, and rdPolynomialSetPoint.

void rdSetPoint::updateObject (  bool  aDeep = true  )  [virtual]

Update this object based on its XML node. Parameters: aDeep  If true, update this object and all its child objects (that is, member variables that are rdObject's); if false, update only the member variables that are not rdObject's. Reimplemented from rdContactForce. Reimplemented in rdLinearSetPoint, and rdPolynomialSetPoint.

void rdSetPoint::updatePseudoStates (   )  [virtual]

Update the pseudostates. Pseudostates are quantities that are not integrated but that depend on the time history of an integration (e.g., spring set points). This method assumes that the model states are up-to-date (i.e., that model->set(t,x,y) or a similar method has been called). rdSetPoint has three pseudostates that are the coordinates of the contact point on BodyA. See also: rdForce::setPointA() Implements rdContactForce.

---

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

• rdSetPoint.h
• rdSetPoint.cpp

---