chrono::ChExternalDynamics Class Reference

Description

Physics element that carries its own dynamics, described as a system of ODEs.

The internal states are integrated simultaneous with the containing system and they can be accessed and used coupled with other physics elements.

#include <ChExternalDynamics.h>

Inheritance diagram for chrono::ChExternalDynamics:
Collaboration diagram for chrono::ChExternalDynamics:

Public Member Functions

virtual ChExternalDynamicsClone () const override
 "Virtual" copy constructor (covariant return type).
 
void Initialize ()
 Initialize the physics item.
 
ChVectorDynamic GetInitialStates ()
 Get the initial values (state at initial time).
 
const ChVectorDynamicGetStates () const
 Get current states.
 
- 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(). More...
 
void AddVisualModel (std::shared_ptr< ChVisualModel > model)
 Add an (optional) visualization model. More...
 
std::shared_ptr< ChVisualModelGetVisualModel () const
 Access the visualization model (if any). More...
 
void AddVisualShape (std::shared_ptr< ChVisualShape > shape, const ChFrame<> &frame=ChFrame<>())
 Add the specified visual shape to the visualization model. More...
 
std::shared_ptr< ChVisualShapeGetVisualShape (unsigned int i) const
 Access the specified visualization shape in the visualization model (if any). More...
 
void AddVisualShapeFEA (std::shared_ptr< ChVisualShapeFEA > shapeFEA)
 Add the specified FEA visualization object to the visualization model. More...
 
std::shared_ptr< ChVisualShapeFEAGetVisualShapeFEA (unsigned int i) const
 Access the specified FEA visualization object in the visualization model (if any). More...
 
virtual ChFrame GetVisualModelFrame (unsigned int nclone=0)
 Get the reference frame (expressed in and relative to the absolute frame) of the visual model. More...
 
virtual unsigned int GetNumVisualModelClones () const
 Return the number of clones of the visual model associated with this physics item. More...
 
void AddCamera (std::shared_ptr< ChCamera > camera)
 Attach a ChCamera to this physical item. More...
 
std::vector< std::shared_ptr< ChCamera > > GetCameras () const
 Get the set of cameras attached to this physics item.
 
virtual bool IsActive () const
 Return true if the object is active and included in dynamics.
 
virtual bool GetCollide () const
 Tell if the object is subject to collision. More...
 
virtual void AddCollisionModelsToSystem (ChCollisionSystem *coll_sys) const
 Add to the provided collision system any collision models managed by this physics item. More...
 
virtual void RemoveCollisionModelsFromSystem (ChCollisionSystem *coll_sys) const
 Remove from the provided collision system any collision models managed by this physics item. More...
 
virtual void SyncCollisionModels ()
 Synchronize the position and bounding box of any collsion models managed by this physics item.
 
virtual geometry::ChAABB GetTotalAABB ()
 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.
 
virtual void StreamOutstate (ChStreamOutBinary &mstream)
 Method to serialize only the state (position, speed) Must be implemented by child classes.
 
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 Update (bool update_assets=true)
 As above, but does not require updating of time-dependent data. More...
 
virtual void SetNoSpeedNoAcceleration ()
 Set zero speed (and zero accelerations) in state, without changing the position. 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.
 
virtual int GetDOC_d ()
 Get the number of scalar constraints, if any, in this item (only unilateral constr.) Children classes might override this.
 
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 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 IntStateGetIncrement (const unsigned int off_x, const ChState &x_new, const ChState &x, const unsigned int off_v, ChStateDelta &Dv)
 Computes Dt = x_new - x, using vectors at specified offsets. 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 InjectConstraints (ChSystemDescriptor &mdescriptor)
 Tell to a system descriptor that there are constraints of type ChConstraint in this object (for further passing it to a solver) Basically does nothing, but maybe that inherited classes may specialize this.
 
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 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::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)
 
virtual std::string & ArchiveContainerName ()
 

Protected Member Functions

virtual bool IsStiff () const
 Declare as stiff (default: false). More...
 
virtual int GetNumStates () const
 Specify number of states (dimension of y).
 
virtual void SetInitialConditions (ChVectorDynamic<> &y0)
 Set initial conditions. More...
 
virtual void CalculateRHS (double time, const ChVectorDynamic<> &y, ChVectorDynamic<> &rhs)
 Calculate and return the ODE right-hand side at the provided time and states. More...
 
virtual bool CalculateJac (double time, const ChVectorDynamic<> &y, const ChVectorDynamic<> &rhs, ChMatrixDynamic<> &J)
 Calculate the Jacobian of the ODE right-hand side with respect to the ODE states. More...
 
virtual void Update (double time, 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 int GetDOF () override
 Get the number of scalar coordinates (variables), if any, in this item. More...
 
ChVariablesVariables ()
 
virtual void InjectVariables (ChSystemDescriptor &descriptor) override
 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.
 
virtual void InjectKRMmatrices (ChSystemDescriptor &descriptor) override
 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.
 
virtual void IntStateGather (const unsigned int off_x, ChState &x, const unsigned int off_v, ChStateDelta &v, double &T) override
 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, bool full_update) override
 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) override
 From item's state acceleration to global acceleration vector. More...
 
virtual void IntStateScatterAcceleration (const unsigned int off_a, const ChStateDelta &a) override
 From global acceleration vector to item's state acceleration. More...
 
virtual void IntLoadResidual_F (const unsigned int off, ChVectorDynamic<> &R, const double c) override
 Takes the F force term, scale and adds to R at given offset: R += c*F. More...
 
virtual void IntLoadResidual_Mv (const unsigned int off, ChVectorDynamic<> &R, const ChVectorDynamic<> &v, const double c) override
 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 IntLoadLumpedMass_Md (const unsigned int off, ChVectorDynamic<> &Md, double &err, const double c) override
 Adds the lumped mass to a Md vector, representing a mass diagonal matrix. 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) override
 Prepare variables and constraints to accommodate a solution: More...
 
virtual void IntFromDescriptor (const unsigned int off_v, ChStateDelta &v, const unsigned int off_L, ChVectorDynamic<> &L) override
 After a solver solution, fetch values from variables and constraints into vectors: More...
 
virtual void KRMmatricesLoad (double Kfactor, double Rfactor, double Mfactor) override
 Adds the current stiffness K and damping R and mass M matrices in encapsulated ChKblock item(s), if any. More...
 
virtual void VariablesFbReset () override
 Sets the 'fb' part (the known term) of the encapsulated ChVariables to zero.
 
virtual void VariablesFbLoadForces (double factor=1) override
 Adds the current forces (applied to item) into the encapsulated ChVariables, in the 'fb' part: qf+=forces*factor.
 
virtual void VariablesQbLoadSpeed () override
 Initialize the 'qb' part of the ChVariables with the current value of speeds. More...
 
virtual void VariablesQbSetSpeed (double step=0) override
 Fetches the item speed (ex. More...
 
virtual void VariablesFbIncrementMq () override
 Adds M*q (masses multiplied current 'qb') to Fb, ex. More...
 
virtual void VariablesQbIncrementPosition (double step) override
 Increment item positions by the 'qb' part of the ChVariables, multiplied by a 'step' factor. More...
 
virtual void ConstraintsFbLoadForces (double factor=1) override
 Adds the current link-forces, if any, (caused by springs, etc.) to the 'fb' vectors of the ChVariables referenced by encapsulated ChConstraints.
 
void ComputeJac (double time)
 Compute the Jacobian at the current time and state.
 

Additional Inherited Members

- Protected Attributes inherited from chrono::ChPhysicsItem
ChSystemsystem
 parent system
 
std::shared_ptr< ChVisualModelInstancevis_model_instance
 instantiated visualization model
 
std::vector< std::shared_ptr< ChCamera > > cameras
 set of cameras
 
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

◆ CalculateJac()

virtual bool chrono::ChExternalDynamics::CalculateJac ( double  time,
const ChVectorDynamic<> &  y,
const ChVectorDynamic<> &  rhs,
ChMatrixDynamic<> &  J 
)
inlineprotectedvirtual

Calculate the Jacobian of the ODE right-hand side with respect to the ODE states.

Must load J = df/dy. Only used if the physics item is declared as stiff. If provided, load df/dy into the provided matrix 'jac' (already set to zero before the call) and return 'true'. In that case, the user-provided Jacobian will overwrite the default finite-difference approximation.

Parameters
timecurrent time
ycurrent ODE states
rhscurrent ODE right-hand side vector
Joutput Jacobian matrix

◆ CalculateRHS()

virtual void chrono::ChExternalDynamics::CalculateRHS ( double  time,
const ChVectorDynamic<> &  y,
ChVectorDynamic<> &  rhs 
)
inlineprotectedvirtual

Calculate and return the ODE right-hand side at the provided time and states.

Must load rhs = f(t,y).

Parameters
timecurrent time
ycurrent ODE states
rhsoutput ODE right-hand side vector

◆ GetDOF()

virtual int chrono::ChExternalDynamics::GetDOF ( )
inlineoverrideprotectedvirtual

Get the number of scalar coordinates (variables), if any, in this item.

Children classes must override this.

Reimplemented from chrono::ChPhysicsItem.

◆ IntFromDescriptor()

void chrono::ChExternalDynamics::IntFromDescriptor ( const unsigned int  off_v,
ChStateDelta v,
const unsigned int  off_L,
ChVectorDynamic<> &  L 
)
overrideprotectedvirtual

After a solver solution, fetch values from variables and constraints into vectors:

Parameters
off_voffset for v
vvector to where the q 'unknowns' term of the variables will be copied
off_Loffset for L
Lvector to where L 'lagrangian ' term of the constraints will be copied

Reimplemented from chrono::ChPhysicsItem.

◆ IntLoadLumpedMass_Md()

void chrono::ChExternalDynamics::IntLoadLumpedMass_Md ( const unsigned int  off,
ChVectorDynamic<> &  Md,
double &  err,
const double  c 
)
overrideprotectedvirtual

Adds the lumped mass to a Md vector, representing a mass diagonal matrix.

Used by lumped explicit integrators. If mass lumping is impossible or approximate, adds scalar error to "error" parameter. Md += c*diag(M)

Parameters
offoffset in Md vector
Mdresult: Md vector, diagonal of the lumped mass matrix
errresult: not touched if lumping does not introduce errors
ca scaling factor

Reimplemented from chrono::ChPhysicsItem.

◆ IntLoadResidual_F()

void chrono::ChExternalDynamics::IntLoadResidual_F ( const unsigned int  off,
ChVectorDynamic<> &  R,
const double  c 
)
overrideprotectedvirtual

Takes the F force term, scale and adds to R at given offset: R += c*F.

Parameters
offoffset in R residual
Rresult: the R residual, R += c*F
ca scaling factor

Reimplemented from chrono::ChPhysicsItem.

Reimplemented in chrono::ChHydraulicActuatorBase.

◆ IntLoadResidual_Mv()

void chrono::ChExternalDynamics::IntLoadResidual_Mv ( const unsigned int  off,
ChVectorDynamic<> &  R,
const ChVectorDynamic<> &  w,
const double  c 
)
overrideprotectedvirtual

Takes the M*v term, multiplying mass by a vector, scale and adds to R at given offset: R += c*M*w.

Parameters
offoffset in R residual
Rresult: the R residual, R += c*M*v
wthe w vector
ca scaling factor

Reimplemented from chrono::ChPhysicsItem.

◆ IntStateGather()

void chrono::ChExternalDynamics::IntStateGather ( const unsigned int  off_x,
ChState x,
const unsigned int  off_v,
ChStateDelta v,
double &  T 
)
overrideprotectedvirtual

From item's state to global state vectors y={x,v} pasting the states at the specified offsets.

Parameters
off_xoffset in x state vector
xstate vector, position part
off_voffset in v state vector
vstate vector, speed part
Ttime

Reimplemented from chrono::ChPhysicsItem.

◆ IntStateGatherAcceleration()

void chrono::ChExternalDynamics::IntStateGatherAcceleration ( const unsigned int  off_a,
ChStateDelta a 
)
overrideprotectedvirtual

From item's state acceleration to global acceleration vector.

Parameters
off_aoffset in a accel. vector
aacceleration part of state vector derivative

Reimplemented from chrono::ChPhysicsItem.

◆ IntStateScatter()

void chrono::ChExternalDynamics::IntStateScatter ( const unsigned int  off_x,
const ChState x,
const unsigned int  off_v,
const ChStateDelta v,
const double  T,
bool  full_update 
)
overrideprotectedvirtual

From global state vectors y={x,v} to item's state (and update) fetching the states at the specified offsets.

Parameters
off_xoffset in x state vector
xstate vector, position part
off_voffset in v state vector
vstate vector, speed part
Ttime
full_updateperform complete update

Reimplemented from chrono::ChPhysicsItem.

◆ IntStateScatterAcceleration()

void chrono::ChExternalDynamics::IntStateScatterAcceleration ( const unsigned int  off_a,
const ChStateDelta a 
)
overrideprotectedvirtual

From global acceleration vector to item's state acceleration.

Parameters
off_aoffset in a accel. vector
aacceleration part of state vector derivative

Reimplemented from chrono::ChPhysicsItem.

◆ IntToDescriptor()

void chrono::ChExternalDynamics::IntToDescriptor ( const unsigned int  off_v,
const ChStateDelta v,
const ChVectorDynamic<> &  R,
const unsigned int  off_L,
const ChVectorDynamic<> &  L,
const ChVectorDynamic<> &  Qc 
)
overrideprotectedvirtual

Prepare variables and constraints to accommodate a solution:

Parameters
off_voffset for v and R
vvector copied into the q 'unknowns' term of the variables
Rvector copied into the F 'force' term of the variables
off_Loffset for L and Qc
Lvector copied into the L 'lagrangian ' term of the constraints
Qcvector copied into the Qb 'constraint' term of the constraints

Reimplemented from chrono::ChPhysicsItem.

◆ IsStiff()

virtual bool chrono::ChExternalDynamics::IsStiff ( ) const
inlineprotectedvirtual

Declare as stiff (default: false).

If stiff, Jacobian information will be generated.

Reimplemented in chrono::ChHydraulicActuatorBase.

◆ KRMmatricesLoad()

void chrono::ChExternalDynamics::KRMmatricesLoad ( double  Kfactor,
double  Rfactor,
double  Mfactor 
)
overrideprotectedvirtual

Adds the current stiffness K and damping R and mass M matrices in encapsulated ChKblock item(s), if any.

The K, R, M matrices are added with scaling values Kfactor, Rfactor, Mfactor. NOTE: signs are flipped respect to the ChTimestepper dF/dx terms: K = -dF/dq, R = -dF/dv

Reimplemented from chrono::ChPhysicsItem.

◆ SetInitialConditions()

virtual void chrono::ChExternalDynamics::SetInitialConditions ( ChVectorDynamic<> &  y0)
inlineprotectedvirtual

Set initial conditions.

Must load y0 = y(0).

◆ Update()

void chrono::ChExternalDynamics::Update ( double  mytime,
bool  update_assets = true 
)
overrideprotectedvirtual

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 item, such as matrices if any, etc., depending on the current coordinates. 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 item's time, and update the asset tree, if any.

Reimplemented from chrono::ChPhysicsItem.

Reimplemented in chrono::ChHydraulicActuatorBase.

◆ VariablesFbIncrementMq()

void chrono::ChExternalDynamics::VariablesFbIncrementMq ( )
overrideprotectedvirtual

Adds M*q (masses multiplied current 'qb') to Fb, ex.

if qb is initialized with v_old using VariablesQbLoadSpeed, this method can be used in timestepping schemes that do: M*v_new = M*v_old + forces*dt

Reimplemented from chrono::ChPhysicsItem.

◆ VariablesQbIncrementPosition()

void chrono::ChExternalDynamics::VariablesQbIncrementPosition ( double  step)
overrideprotectedvirtual

Increment item positions by the 'qb' part of the ChVariables, multiplied by a 'step' factor.

pos+=qb*step If qb is a speed, this behaves like a single step of 1-st order numerical integration (Eulero integration).

Reimplemented from chrono::ChPhysicsItem.

◆ VariablesQbLoadSpeed()

void chrono::ChExternalDynamics::VariablesQbLoadSpeed ( )
overrideprotectedvirtual

Initialize the 'qb' part of the ChVariables with the current value of speeds.

Note: since 'qb' is the unknown, this function seems unnecessary, unless used before VariablesFbIncrementMq()

Reimplemented from chrono::ChPhysicsItem.

◆ VariablesQbSetSpeed()

void chrono::ChExternalDynamics::VariablesQbSetSpeed ( double  step = 0)
overrideprotectedvirtual

Fetches the item speed (ex.

linear and angular vel.in rigid bodies) from the 'qb' part of the ChVariables and sets it as the current item speed. If 'step' is not 0, also should compute the approximate acceleration of the item using backward differences, that is accel=(new_speed-old_speed)/step. Mostly used after the solver provided the solution in ChVariables.

Reimplemented from chrono::ChPhysicsItem.


The documentation for this class was generated from the following files:
  • /builds/uwsbel/chrono/src/chrono/physics/ChExternalDynamics.h
  • /builds/uwsbel/chrono/src/chrono/physics/ChExternalDynamics.cpp