Simbody  3.7
SimTK::Force::TwoPointLinearSpring Class Reference

A linear spring between two points, specified as a station on each of two bodies. More...

+ Inheritance diagram for SimTK::Force::TwoPointLinearSpring:

Public Member Functions

 TwoPointLinearSpring (GeneralForceSubsystem &forces, const MobilizedBody &body1, const Vec3 &station1, const MobilizedBody &body2, const Vec3 &station2, Real k, Real x0)
 Create a TwoPointLinearSpring. More...
 
 TwoPointLinearSpring ()
 Default constructor creates an empty handle. More...
 
 SimTK_INSERT_DERIVED_HANDLE_DECLARATIONS (TwoPointLinearSpring, TwoPointLinearSpringImpl, Force)
 
- Public Member Functions inherited from SimTK::Force
void disable (State &) const
 Disable this force element, effectively removing it from the System for computational purposes (it is still using its ForceIndex, however). More...
 
void enable (State &) const
 Enable this force element if it was previously disabled. More...
 
bool isDisabled (const State &) const
 Test whether this force element is currently disabled in the supplied State. More...
 
void setDisabledByDefault (bool shouldBeDisabled)
 Normally force elements are enabled when defined and can be disabled later. More...
 
bool isDisabledByDefault () const
 Test whether this force element is disabled by default in which case it must be explicitly enabled before it will take effect. More...
 
void calcForceContribution (const State &state, Vector_< SpatialVec > &bodyForces, Vector_< Vec3 > &particleForces, Vector &mobilityForces) const
 Calculate the force that would be applied by this force element if the given state were realized to Dynamics stage. More...
 
Real calcPotentialEnergyContribution (const State &state) const
 Calculate the potential energy contribution that is made by this force element at the given state. More...
 
 Force ()
 Default constructor for Force handle base class does nothing. More...
 
 operator ForceIndex () const
 Implicit conversion to ForceIndex when needed. More...
 
const GeneralForceSubsystemgetForceSubsystem () const
 Get the GeneralForceSubsystem of which this Force is an element. More...
 
ForceIndex getForceIndex () const
 Get the index of this force element within its parent force subsystem. More...
 
- Public Member Functions inherited from SimTK::PIMPLHandle< Force, ForceImpl, true >
bool isEmptyHandle () const
 Returns true if this handle is empty, that is, does not refer to any implementation object. More...
 
bool isOwnerHandle () const
 Returns true if this handle is the owner of the implementation object to which it refers. More...
 
bool isSameHandle (const Force &other) const
 Determine whether the supplied handle is the same object as "this" PIMPLHandle. More...
 
void disown (Force &newOwner)
 Give up ownership of the implementation to an empty handle. More...
 
PIMPLHandlereferenceAssign (const Force &source)
 "Copy" assignment but with shallow (pointer) semantics. More...
 
PIMPLHandlecopyAssign (const Force &source)
 This is real copy assignment, with ordinary C++ object ("value") semantics. More...
 
void clearHandle ()
 Make this an empty handle, deleting the implementation object if this handle is the owner of it. More...
 
const ForceImpl & getImpl () const
 Get a const reference to the implementation associated with this Handle. More...
 
ForceImpl & updImpl ()
 Get a writable reference to the implementation associated with this Handle. More...
 
int getImplHandleCount () const
 Return the number of handles the implementation believes are referencing it. More...
 

Additional Inherited Members

- Public Types inherited from SimTK::PIMPLHandle< Force, ForceImpl, true >
typedef PIMPLHandle< Force, ForceImpl, PTR > HandleBase
 
typedef HandleBase ParentHandle
 
- Protected Member Functions inherited from SimTK::Force
 Force (ForceImpl *r)
 Use this in a derived Force handle class constructor to supply the concrete implementation object to be stored in the handle base. More...
 
- Protected Member Functions inherited from SimTK::PIMPLHandle< Force, ForceImpl, true >
 PIMPLHandle ()
 The default constructor makes this an empty handle. More...
 
 PIMPLHandle (ForceImpl *p)
 This provides consruction of a handle referencing an existing implementation object. More...
 
 PIMPLHandle (const PIMPLHandle &source)
 The copy constructor makes either a deep (value) or shallow (reference) copy of the supplied source PIMPL object, based on whether this is a "pointer semantics" (PTR=true) or "object (value) semantics" (PTR=false, default) class. More...
 
 ~PIMPLHandle ()
 Note that the destructor is non-virtual. More...
 
PIMPLHandleoperator= (const PIMPLHandle &source)
 Copy assignment makes the current handle either a deep (value) or shallow (reference) copy of the supplied source PIMPL object, based on whether this is a "pointer sematics" (PTR=true) or "object (value) semantics" (PTR=false, default) class. More...
 
void setImpl (ForceImpl *p)
 Set the implementation for this empty handle. More...
 
bool hasSameImplementation (const Force &other) const
 Determine whether the supplied handle is a reference to the same implementation object as is referenced by "this" PIMPLHandle. More...
 

Detailed Description

A linear spring between two points, specified as a station on each of two bodies.

The stiffness k and unstretched length x0 are provided. Then if d is the unit vector from point1 to point2, and x the current separation, we have f = k(x-x0) and we apply a force f*d to point1 and -f*d to point2. This contributes to potential energy: pe = 1/2 k (x-x0)^2. It is an error if the two points become coincident, since we are unable to determine a direction for the force in that case.

Constructor & Destructor Documentation

◆ TwoPointLinearSpring() [1/2]

SimTK::Force::TwoPointLinearSpring::TwoPointLinearSpring ( GeneralForceSubsystem forces,
const MobilizedBody body1,
const Vec3 station1,
const MobilizedBody body2,
const Vec3 station2,
Real  k,
Real  x0 
)

Create a TwoPointLinearSpring.

Parameters
forcesthe subsystem to which this force should be added
body1the first body to which the force should be applied
station1the location on the first body at which the force should be applied
body2the second body to which the force should be applied
station2the location on the second body at which the force should be applied
kthe spring constant
x0the distance at which the force is 0

◆ TwoPointLinearSpring() [2/2]

Default constructor creates an empty handle.

Member Function Documentation

◆ SimTK_INSERT_DERIVED_HANDLE_DECLARATIONS()

SimTK::Force::TwoPointLinearSpring::SimTK_INSERT_DERIVED_HANDLE_DECLARATIONS ( TwoPointLinearSpring  ,
TwoPointLinearSpringImpl  ,
Force   
)

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