chrono::ChLinkMarkers Class Reference

Description

Class for links which connect two 'markers'.

The markers are two ChMarker objects each belonging to the two linked ChBody parts. Many specialized classes are based on this ChLinkMarkers class, for example the ChLinkSpring and all the family of the ChLinkLock classes - see them-. Also, ChLinkMarkers class allows an optional force vector and torque vector to be set between the two connected markers.

#include <ChLinkMarkers.h>

Inheritance diagram for chrono::ChLinkMarkers:
Collaboration diagram for chrono::ChLinkMarkers:

Public Member Functions

 ChLinkMarkers (const ChLinkMarkers &other)
 
virtual ChLinkMarkersClone () const override
 "Virtual" copy constructor (covariant return type).
 
ChMarkerGetMarker1 ()
 Return the 1st referenced marker (the 'slave' marker, owned by 1st body)
 
ChMarkerGetMarker2 ()
 Return the 2nd referenced marker (the 'master' marker, owned by 2nd body)
 
virtual void SetUpMarkers (ChMarker *mark1, ChMarker *mark2)
 set the two markers associated with this link
 
void SetMarkID1 (int mid)
 
void SetMarkID2 (int mid)
 
int GetMarkID1 ()
 
int GetMarkID2 ()
 
bool ReferenceMarkers (ChMarker *mark1, ChMarker *mark2)
 Shortcut: set markers and marker IDs at once.
 
virtual void Initialize (std::shared_ptr< ChMarker > mark1, std::shared_ptr< ChMarker > mark2)
 Use this function after link creation, to initialize the link from two markers to join. More...
 
virtual void Initialize (std::shared_ptr< ChBody > mbody1, std::shared_ptr< ChBody > mbody2, const ChCoordsys<> &mpos)
 Use this function after link creation, to initialize the link from two joined rigid bodies. More...
 
virtual void Initialize (std::shared_ptr< ChBody > mbody1, std::shared_ptr< ChBody > mbody2, bool pos_are_relative, const ChCoordsys<> &mpos1, const ChCoordsys<> &mpos2)
 Use this function after link creation, to initialize the link from two joined rigid bodies. More...
 
virtual ChCoordsys GetLinkRelativeCoords () override
 Get the link coordinate system, expressed relative to Body2 (the 'master' body). More...
 
virtual ChFrame GetAssetsFrame (unsigned int nclone=0) override
 Get the master coordinate system for the assets (this will return the absolute coordinate system of the 'master' marker2)
 
virtual void UpdateRelMarkerCoords ()
 Updates auxiliary vars relM, relM_dt, relM_dtdt, dist, dist_dt et similia. More...
 
virtual void UpdateForces (double mytime)
 Updates auxiliary forces caused by springs/dampers/etc. More...
 
virtual void Update (double mytime, bool update_assets=true) override
 This is an important function, which is called by the owner ChSystem at least once per integration step. More...
 
virtual void IntLoadResidual_F (const unsigned int off, ChVectorDynamic<> &R, const double c) override
 Adds force to residual R, as R*= F*c NOTE: here the off ofset in R is NOT used because add F at the TWO offsets of the two connected bodies, so it is assumed that offsets for Body1 and Body2 variables have been already set properly!
 
virtual void ConstraintsFbLoadForces (double factor=1) override
 Overrides the empty behaviour of the parent ChLink implementation, which does not consider any user-imposed force between the two bodies. More...
 
const CoordsysGetRelM () const
 Relative position of marker 1 respect to marker 2.
 
const CoordsysGetRelM_dt () const
 Relative speed of marker 1 respect to marker 2.
 
const CoordsysGetRelM_dtdt () const
 Relative acceleration of marker 1 respect to marker 2.
 
double GetRelAngle () const
 Relative rotation angle of marker 1 respect to marker 2 (best with revolute joints..).
 
const ChVectorGetRelAxis () const
 Relative finite rotation axis of marker 1 respect to marker 2.
 
const ChVectorGetRelRotaxis () const
 
const ChVectorGetRelWvel () const
 Relative angular speed of marker 1 respect to marker 2.
 
const ChVectorGetRelWacc () const
 Relative angular acceleration of marker 1 respect to marker 2.
 
double GetDist () const
 Relative 'polar' distance of marker 1 respect to marker 2.
 
double GetDist_dt () const
 Relative speed of marker 1 respect to marker 2, along the polar distance vector.
 
const ChVectorGet_Scr_force () const
 To get & set the 'script' force buffers(only accessed by external scripts, so it's up to the script to remember to set& reset them -link class just add them to C_force etc. More...
 
const ChVectorGet_Scr_torque () const
 
void Set_Scr_force (const ChVector<> &mf)
 
void Set_Scr_torque (const ChVector<> &mf)
 
const ChVectorGetC_force () const
 Get the total applied force accumulators (force, momentum) in link coords. More...
 
const ChVectorGetC_torque () const
 
virtual void ArchiveOUT (ChArchiveOut &marchive) override
 Method to allow serialization of transient data to archives.
 
virtual void ArchiveIN (ChArchiveIn &marchive) override
 Method to allow deserialization of transient data from archives. More...
 
- Public Member Functions inherited from chrono::ChPhysicsItem
 ChPhysicsItem (const ChPhysicsItem &other)
 
ChSystemGetSystem () const
 Get the pointer to the parent ChSystem()
 
virtual void SetSystem (ChSystem *m_system)
 Set the pointer to the parent ChSystem() and also add to new collision system / remove from old coll.system.
 
void AddAsset (std::shared_ptr< ChAsset > masset)
 Add an optional asset (it can be used to define visualization shapes, es ChSphereShape, or textures, or custom attached properties that the user can define by creating his class inherited from ChAsset)
 
std::vector< std::shared_ptr
< ChAsset > > & 
GetAssets ()
 Access to the list of optional assets.
 
std::shared_ptr< ChAssetGetAssetN (unsigned int num)
 Access the Nth asset in the list of optional assets.
 
virtual unsigned int GetAssetsFrameNclones ()
 Optionally, a ChPhysicsItem can return multiple asset coordinate systems; this can be helpful if, for example, when a ChPhysicsItem contains 'clones' with the same assets (ex. More...
 
virtual bool GetCollide () const
 Tell if the object is subject to collision. More...
 
virtual void SyncCollisionModels ()
 If this physical item contains one or more collision models, sinchronize their coordinates and bounding boxes to the state of the item. More...
 
virtual void AddCollisionModelsToSystem ()
 If this physical item contains one or more collision models, add them to the system's collision engine. More...
 
virtual void RemoveCollisionModelsFromSystem ()
 If this physical item contains one or more collision models, remove them from the system's collision engine. More...
 
virtual void GetTotalAABB (ChVector<> &bbmin, ChVector<> &bbmax)
 Get the entire AABB axis-aligned bounding box of the object. More...
 
virtual void GetCenter (ChVector<> &mcenter)
 Get a symbolic 'center' of the object. More...
 
virtual void StreamINstate (ChStreamInBinary &mstream)
 Method to deserialize only the state (position, speed) Must be implemented by child classes. More...
 
virtual void StreamOUTstate (ChStreamOutBinary &mstream)
 Method to serialize only the state (position, speed) Must be implemented by child classes. More...
 
virtual void Setup ()
 This might recompute the number of coordinates, DOFs, constraints, in case this might change (ex in ChAssembly), as well as state offsets of contained items (ex in ChMesh)
 
virtual void SetNoSpeedNoAcceleration ()
 Set zero speed (and zero accelerations) in state, without changing the position. More...
 
virtual int GetDOF ()
 Get the number of scalar coordinates (variables), if any, in this item. More...
 
virtual int GetDOF_w ()
 Get the number of scalar coordinates of variables derivatives (usually = DOF, but might be different than DOF, ex. More...
 
virtual int GetDOC ()
 Get the number of scalar constraints, if any, in this item.
 
virtual int GetDOC_c ()
 Get the number of scalar constraints, if any, in this item (only bilateral constr.) Children classes might override this. More...
 
virtual int GetDOC_d ()
 Get the number of scalar constraints, if any, in this item (only unilateral constr.) Children classes might override this. More...
 
unsigned int GetOffset_x ()
 Get offset in the state vector (position part)
 
unsigned int GetOffset_w ()
 Get offset in the state vector (speed part)
 
unsigned int GetOffset_L ()
 Get offset in the lagrangian multipliers.
 
void SetOffset_x (const unsigned int moff)
 Set offset in the state vector (position part) Note: only the ChSystem::Setup function should use this.
 
void SetOffset_w (const unsigned int moff)
 Set offset in the state vector (speed part) Note: only the ChSystem::Setup function should use this.
 
void SetOffset_L (const unsigned int moff)
 Set offset in the lagrangian multipliers Note: only the ChSystem::Setup function should use this.
 
virtual void IntStateGather (const unsigned int off_x, ChState &x, const unsigned int off_v, ChStateDelta &v, double &T)
 From item's state to global state vectors y={x,v} pasting the states at the specified offsets. More...
 
virtual void IntStateScatter (const unsigned int off_x, const ChState &x, const unsigned int off_v, const ChStateDelta &v, const double T)
 From global state vectors y={x,v} to item's state (and update) fetching the states at the specified offsets. More...
 
virtual void IntStateGatherAcceleration (const unsigned int off_a, ChStateDelta &a)
 From item's state acceleration to global acceleration vector. More...
 
virtual void IntStateScatterAcceleration (const unsigned int off_a, const ChStateDelta &a)
 From global acceleration vector to item's state acceleration. More...
 
virtual void IntStateGatherReactions (const unsigned int off_L, ChVectorDynamic<> &L)
 From item's reaction forces to global reaction vector. More...
 
virtual void IntStateScatterReactions (const unsigned int off_L, const ChVectorDynamic<> &L)
 From global reaction vector to item's reaction forces. More...
 
virtual void IntStateIncrement (const unsigned int off_x, ChState &x_new, const ChState &x, const unsigned int off_v, const ChStateDelta &Dv)
 Computes x_new = x + Dt , using vectors at specified offsets. More...
 
virtual void IntLoadResidual_Mv (const unsigned int off, ChVectorDynamic<> &R, const ChVectorDynamic<> &w, const double c)
 Takes the M*v term, multiplying mass by a vector, scale and adds to R at given offset: R += c*M*w. More...
 
virtual void IntLoadResidual_CqL (const unsigned int off_L, ChVectorDynamic<> &R, const ChVectorDynamic<> &L, const double c)
 Takes the term Cq'*L, scale and adds to R at given offset: R += c*Cq'*L. More...
 
virtual void IntLoadConstraint_C (const unsigned int off, ChVectorDynamic<> &Qc, const double c, bool do_clamp, double recovery_clamp)
 Takes the term C, scale and adds to Qc at given offset: Qc += c*C. More...
 
virtual void IntLoadConstraint_Ct (const unsigned int off, ChVectorDynamic<> &Qc, const double c)
 Takes the term Ct, scale and adds to Qc at given offset: Qc += c*Ct. More...
 
virtual void IntToDescriptor (const unsigned int off_v, const ChStateDelta &v, const ChVectorDynamic<> &R, const unsigned int off_L, const ChVectorDynamic<> &L, const ChVectorDynamic<> &Qc)
 Prepare variables and constraints for a solution: From a vector R into the F 'force' term of the variables From a vector Qc into the Qb 'constraint' term of the constraints From a vector v into the q 'unknowns' term of the variables (for warm starting) From a vector L into the L 'lagrangian ' term of the constraints (for warm starting) More...
 
virtual void IntFromDescriptor (const unsigned int off_v, ChStateDelta &v, const unsigned int off_L, ChVectorDynamic<> &L)
 After a solver solution, fetch values from variables and constraints: To a vector v from the q 'unknowns' term of the variables To a vector L from the L 'lagrangian ' term of the constraints. More...
 
virtual void VariablesFbReset ()
 Sets the 'fb' part (the known term) of the encapsulated ChVariables to zero.
 
virtual void VariablesFbLoadForces (double factor=1)
 Adds the current forces (applied to item) into the encapsulated ChVariables, in the 'fb' part: qf+=forces*factor.
 
virtual void VariablesQbLoadSpeed ()
 Initialize the 'qb' part of the ChVariables with the current value of speeds. More...
 
virtual void VariablesFbIncrementMq ()
 Adds M*q (masses multiplied current 'qb') to Fb, ex. More...
 
virtual void VariablesQbSetSpeed (double step=0)
 Fetches the item speed (ex. More...
 
virtual void VariablesQbIncrementPosition (double step)
 Increment item positions by the 'qb' part of the ChVariables, multiplied by a 'step' factor. More...
 
virtual void InjectVariables (ChSystemDescriptor &mdescriptor)
 Tell to a system descriptor that there are variables of type ChVariables in this object (for further passing it to a solver) Basically does nothing, but maybe that inherited classes may specialize this. More...
 
virtual void InjectConstraints (ChSystemDescriptor &mdescriptor)
 Tell to a system descriptor that there are contraints of type ChConstraint in this object (for further passing it to a solver) Basically does nothing, but maybe that inherited classes may specialize this. More...
 
virtual void ConstraintsBiReset ()
 Sets to zero the known term (b_i) of encapsulated ChConstraints.
 
virtual void ConstraintsBiLoad_C (double factor=1, double recovery_clamp=0.1, bool do_clamp=false)
 Adds the current C (constraint violation) to the known term (b_i) of encapsulated ChConstraints.
 
virtual void ConstraintsBiLoad_Ct (double factor=1)
 Adds the current Ct (partial t-derivative, as in C_dt=0-> [Cq]*q_dt=-Ct) to the known term (b_i) of encapsulated ChConstraints.
 
virtual void ConstraintsBiLoad_Qc (double factor=1)
 Adds the current Qc (the vector of C_dtdt=0 -> [Cq]*q_dtdt=Qc ) to the known term (b_i) of encapsulated ChConstraints.
 
virtual void ConstraintsLoadJacobians ()
 Adds the current jacobians in encapsulated ChConstraints.
 
virtual void ConstraintsFetch_react (double factor=1)
 Fetches the reactions from the lagrangian multiplier (l_i) of encapsulated ChConstraints. More...
 
virtual void InjectKRMmatrices (ChSystemDescriptor &mdescriptor)
 Tell to a system descriptor that there are items of type ChKblock in this object (for further passing it to a solver) Basically does nothing, but maybe that inherited classes may specialize this. More...
 
virtual void KRMmatricesLoad (double Kfactor, double Rfactor, double Mfactor)
 Adds the current stiffness K and damping R and mass M matrices in encapsulated ChKblock item(s), if any. More...
 
- Public Member Functions inherited from chrono::ChObj
 ChObj (const ChObj &other)
 
int GetIdentifier () const
 Gets the numerical identifier of the object.
 
void SetIdentifier (int id)
 Sets the numerical identifier of the object.
 
double GetChTime () const
 Gets the simulation time of this object.
 
void SetChTime (double m_time)
 Sets the simulation time of this object.
 
const char * GetName () const
 Gets the name of the object as C Ascii null-terminated string -for reading only!
 
void SetName (const char myname[])
 Sets the name of this object, as ascii string.
 
std::string GetNameString () const
 Gets the name of the object as C Ascii null-terminated string.
 
void SetNameString (const std::string &myname)
 Sets the name of this object, as std::string.
 
void MFlagsSetAllOFF (int &mflag)
 
void MFlagsSetAllON (int &mflag)
 
void MFlagSetON (int &mflag, int mask)
 
void MFlagSetOFF (int &mflag, int mask)
 
int MFlagGet (int &mflag, int mask)
 

Protected Attributes

ChMarkermarker1
 slave coordsys
 
ChMarkermarker2
 master coordsys, =0 if liked to ground
 
int markID1
 unique identifier for markers 1 & 2,
 
int markID2
 when using plugin dynamic hierarchies
 
Coordsys relM
 relative marker position 2-1
 
Coordsys relM_dt
 relative marker speed
 
Coordsys relM_dtdt
 relative marker acceleration
 
double relAngle
 relative angle of rotation
 
ChVector relAxis
 relative axis of rotation
 
ChVector relRotaxis
 relative rotaion vector =angle*axis
 
ChVector relWvel
 relative angular speed
 
ChVector relWacc
 relative angular acceleration
 
double dist
 the distance between the two origins of markers,
 
double dist_dt
 the speed between the two origins of markers
 
ChVector Scr_force
 internal force set by script only (just added to C_force)
 
ChVector Scr_torque
 internal torque set by script only (just added to C_force)
 
ChVector C_force
 internal force applied by springs/dampers/actuators
 
ChVector C_torque
 internal torque applied by springs/dampers/actuators
 
- Protected Attributes inherited from chrono::ChPhysicsItem
ChSystemsystem
 parent system
 
std::vector< std::shared_ptr
< ChAsset > > 
assets
 set of assets
 
unsigned int offset_x
 offset in vector of state (position part)
 
unsigned int offset_w
 offset in vector of state (speed part)
 
unsigned int offset_L
 offset in vector of lagrangian multipliers
 
- Protected Attributes inherited from chrono::ChObj
double ChTime
 the time of simulation for the object
 

Member Function Documentation

void chrono::ChLinkMarkers::ArchiveIN ( ChArchiveIn marchive)
overridevirtual
void chrono::ChLinkMarkers::ConstraintsFbLoadForces ( double  factor = 1)
overridevirtual

Overrides the empty behaviour of the parent ChLink implementation, which does not consider any user-imposed force between the two bodies.

It adds the current link-forces, if any, (caused by springs, etc.) to the 'fb' vectors of the ChVariables referenced by encapsulated ChConstraints. In details, it adds the effect caused by C_force and C_torque. Both C_force and C_torque these forces are considered expressed in the reference coordsystem of marker2 (the MAIN marker), and their application point is the origin of marker1 (the SLAVE marker).

Reimplemented from chrono::ChPhysicsItem.

const ChVector& chrono::ChLinkMarkers::Get_Scr_force ( ) const

To get & set the 'script' force buffers(only accessed by external scripts, so it's up to the script to remember to set& reset them -link class just add them to C_force etc.

const ChVector& chrono::ChLinkMarkers::GetC_force ( ) const

Get the total applied force accumulators (force, momentum) in link coords.

These forces might be affected by additional springs, dampers, etc. but they do not include the reaction forces.

virtual ChCoordsys chrono::ChLinkMarkers::GetLinkRelativeCoords ( )
overridevirtual

Get the link coordinate system, expressed relative to Body2 (the 'master' body).

This represents the 'main' reference of the link: reaction forces and torques are expressed in this coordinate system. (It is the coordinate system of the 'master' marker2 relative to Body2)

Reimplemented from chrono::ChLink.

void chrono::ChLinkMarkers::Initialize ( std::shared_ptr< ChMarker mark1,
std::shared_ptr< ChMarker mark2 
)
virtual

Use this function after link creation, to initialize the link from two markers to join.

Each marker must belong to a rigid body, and both rigid bodies must belong to the same ChSystem. The position of mark2 is used as link's position and main reference.

Parameters
mark1first marker to join
mark2second marker to join (master)
void chrono::ChLinkMarkers::Initialize ( std::shared_ptr< ChBody mbody1,
std::shared_ptr< ChBody mbody2,
const ChCoordsys<> &  mpos 
)
virtual

Use this function after link creation, to initialize the link from two joined rigid bodies.

Both rigid bodies must belong to the same ChSystem. Two markers will be created and added to the rigid bodies (later, you can use GetMarker1() and GetMarker2() to access them. To specify the (absolute) position of link and markers, use 'mpos'.

Parameters
mbody1first body to join
mbody2second body to join
mposthe current absolute pos.& alignment.
void chrono::ChLinkMarkers::Initialize ( std::shared_ptr< ChBody mbody1,
std::shared_ptr< ChBody mbody2,
bool  pos_are_relative,
const ChCoordsys<> &  mpos1,
const ChCoordsys<> &  mpos2 
)
virtual

Use this function after link creation, to initialize the link from two joined rigid bodies.

Both rigid bodies must belong to the same ChSystem. Two markers will be created and added to the rigid bodies (later, you can use GetMarker1() and GetMarker2() to access them. To specify the (absolute) position of link and markers, use 'mpos'.

Parameters
mbody1first body to join
mbody2second body to join
pos_are_relativeif =true, following two positions are relative to bodies. If false, are absolute.
mpos1the position & alignment of 1st marker (relative to body1 cords, or absolute)
mpos2the position & alignment of 2nd marker (relative to body2 cords, or absolute)
void chrono::ChLinkMarkers::Update ( double  mytime,
bool  update_assets = true 
)
overridevirtual

This is an important function, which is called by the owner ChSystem at least once per integration step.

It may update all auxiliary data of the link, such as matrices if any, etc. The inherited classes, for example the ChLinkMask, often implement specialized versions of this Update(time) function, because they might need to update inner states, forces, springs, etc. This base version, by default, simply updates the time.

Reimplemented from chrono::ChLink.

Reimplemented in chrono::ChLinkMasked.

void chrono::ChLinkMarkers::UpdateForces ( double  mytime)
virtual

Updates auxiliary forces caused by springs/dampers/etc.

which may be connected between the two bodies of the link. By default, it adds the forces which might have been added by the user using Set_Scr_force() and Set_Scr_torque(). Note, these forces are considered in the reference coordsystem of marker2 (the MAIN marker), and their application point is the origin of marker1 (the SLAVE marker).

Reimplemented in chrono::ChLinkMasked, chrono::ChLinkLock, chrono::ChLinkSpring, chrono::ChLinkEngine, chrono::ChLinkSpringCB, chrono::ChLinkRotSpringCB, chrono::ChLinkPneumaticActuator, chrono::ChLinkBrake, and chrono::ChLinkClearance.

void chrono::ChLinkMarkers::UpdateRelMarkerCoords ( )
virtual

Updates auxiliary vars relM, relM_dt, relM_dtdt, dist, dist_dt et similia.

Reimplemented in chrono::ChLinkLock.