Description

Physical system.

This class is used to represent a multibody physical system, so it acts also as a database for most items involved in simulations, most noticeably objects of ChBody and ChLink classes, which are used to represent mechanisms.

Moreover, it also owns some global settings and features, like the gravity acceleration, the global time and so on.

This object will be responsible of performing the entire physical simulation (dynamics, kinematics, statics, etc.), so you need at least one ChSystem object in your program, in order to perform simulations (you'll insert rigid bodies and links into it..)

Note that this is an abstract class, in your code you must create a system from one of the concrete classes: chrono::ChSystemNSC (for non-smooth contacts) or chrono::ChSystemSMC (for smooth 'penalty' contacts).

Further info at the Simulation system manual page.

#include <ChSystem.h>

Inheritance diagram for chrono::ChSystem:

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Collaboration diagram for chrono::ChSystem:

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Classes
class	CustomCollisionCallback
	Class to be used as a callback interface for user defined actions performed at each collision detection step. More...

Public Member Functions
	ChSystem ()
	Create a physical system.

	ChSystem (const ChSystem &other)
	Copy constructor.

virtual	~ChSystem ()
	Destructor.

void	SetStep (double m_step)
	Sets the time step used for integration (dynamical simulation). More...

double	GetStep () const
	Gets the current time step used for the integration (dynamical simulation).

void	SetEndTime (double m_end_time)
	Sets the end of simulation.

double	GetEndTime () const
	Gets the end of the simulation.

void	SetStepMin (double m_step_min)
	Sets the lower limit for time step (only needed if using integration methods which support time step adaption).

double	GetStepMin () const
	Gets the lower limit for time step.

void	SetStepMax (double m_step_max)
	Sets the upper limit for time step (only needed if using integration methods which support time step adaption).

double	GetStepMax () const
	Gets the upper limit for time step.

void	SetTimestepperType (ChTimestepper::Type type)
	Set the method for time integration (time stepper type). More...

ChTimestepper::Type	GetTimestepperType () const
	Get the current method for time integration (time stepper type).

void	SetTimestepper (std::shared_ptr< ChTimestepper > mstepper)
	Set the timestepper object to be used for time integration.

std::shared_ptr< ChTimestepper >	GetTimestepper () const
	Get the timestepper currently used for time integration.

void	SetMaxiter (int m_maxiter)
	Sets outer iteration limit for assembly constraints. More...

int	GetMaxiter () const
	Gets iteration limit for assembly constraints.

void	SetMaterialCompositionStrategy (std::unique_ptr< ChMaterialCompositionStrategy< float >> &&strategy)
	Change the default composition laws for contact surface materials (coefficient of friction, cohesion, compliance, etc.)

const ChMaterialCompositionStrategy< float > &	GetMaterialCompositionStrategy () const
	Accessor for the current composition laws for contact surface material.

void	SetMinBounceSpeed (double mval)
	For elastic collisions, with objects that have nonzero restitution coefficient: objects will rebounce only if their relative colliding speed is above this threshold. More...

double	GetMinBounceSpeed () const
	Objects will rebounce only if their relative colliding speed is above this threshold.

void	SetMaxPenetrationRecoverySpeed (double mval)
	For the default stepper, you can limit the speed of exiting from penetration situations. More...

double	GetMaxPenetrationRecoverySpeed () const
	Get the limit on the speed for exiting from penetration situations (for Anitescu stepper)

virtual void	SetSolver (std::shared_ptr< ChSolver > newsolver)
	Attach a solver (derived from ChSolver) for use by this system.

virtual std::shared_ptr< ChSolver >	GetSolver ()
	Access the solver currently associated with this system.

virtual void	SetSolverType (ChSolver::Type type)
	Choose the solver type, to be used for the simultaneous solution of the constraints in dynamical simulations (as well as in kinematics, statics, etc.) More...

ChSolver::Type	GetSolverType () const
	Gets the current solver type.

void	SetSolverMaxIterations (int max_iters)
	Set the maximum number of iterations, if using an iterative solver. More...

int	GetSolverMaxIterations () const
	Get the current maximum number of iterations, if using an iterative solver. More...

void	SetSolverTolerance (double tolerance)
	Set the solver tolerance threshold (used with iterative solvers only). More...

double	GetSolverTolerance () const
	Get the current tolerance value (used with iterative solvers only).

void	SetSolverForceTolerance (double tolerance)
	Set a solver tolerance threshold at force level (default: not specified). More...

double	GetSolverForceTolerance () const
	Get the current value of the force-level tolerance (used with iterative solvers only).

void	SetSystemDescriptor (std::shared_ptr< ChSystemDescriptor > newdescriptor)
	Instead of using the default 'system descriptor', you can create your own custom descriptor (inherited from ChSystemDescriptor) and plug it into the system using this function.

std::shared_ptr< ChSystemDescriptor >	GetSystemDescriptor ()
	Access directly the 'system descriptor'.

void	Set_G_acc (const ChVector<> &m_acc)
	Sets the G (gravity) acceleration vector, affecting all the bodies in the system.

const ChVector &	Get_G_acc () const
	Gets the G (gravity) acceleration vector affecting all the bodies in the system.

void	Clear ()
	Removes all bodies/marker/forces/links/contacts, also resets timers and events.

virtual ChMaterialSurface::ContactMethod	GetContactMethod () const =0
	Return the contact method supported by this system. More...

virtual ChBody *	NewBody ()=0
	Create and return the pointer to a new body. More...

virtual ChBodyAuxRef *	NewBodyAuxRef ()=0
	Create and return the pointer to a new body with auxiliary reference frame. More...

virtual void	SetContactContainer (std::shared_ptr< ChContactContainer > container)
	Replace the contact container.

std::shared_ptr< ChContactContainer >	GetContactContainer ()
	Get the contact container.

void	Reference_LM_byID ()
	Given inserted markers and links, restores the pointers of links to markers given the information about the marker IDs. More...

int	GetNcontacts ()
	Gets the number of contacts.

virtual double	GetTimerStep () const
	Return the time (in seconds) spent for computing the time step.

virtual double	GetTimerAdvance () const
	Return the time (in seconds) for time integration, within the time step.

virtual double	GetTimerSolver () const
	Return the time (in seconds) for the solver, within the time step. More...

virtual double	GetTimerSetup () const
	Return the time (in seconds) for the solver Setup phase, within the time step.

virtual double	GetTimerJacobian () const
	Return the time (in seconds) for calculating/loading Jacobian information, within the time step.

virtual double	GetTimerCollision () const
	Return the time (in seconds) for runnning the collision detection step, within the time step.

virtual double	GetTimerUpdate () const
	Return the time (in seconds) for updating auxiliary data, within the time step.

double	GetTimerCollisionBroad () const
	Return the time (in seconds) for broadphase collision detection, within the time step.

double	GetTimerCollisionNarrow () const
	Return the time (in seconds) for narrowphase collision detection, within the time step.

void	ResetTimers ()
	Resets the timers.

virtual void	Setup () override
	Counts the number of bodies and links. More...

virtual void	Update (bool update_assets=true) override
	Updates all the auxiliary data and children of bodies, forces, links, given their current state.

void	ForceUpdate ()
	In normal usage, no system update is necessary at the beginning of a new dynamics step (since an update is performed at the end of a step). More...

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) 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	IntStateGatherReactions (const unsigned int off_L, ChVectorDynamic<> &L) override
	From item's reaction forces to global reaction vector. More...

virtual void	IntStateScatterReactions (const unsigned int off_L, const ChVectorDynamic<> &L) override
	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) override
	Computes x_new = x + Dt , using vectors at specified offsets. 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<> &w, const double c) override
	Takes the Mv term, multiplying mass by a vector, scale and adds to R at given offset: R += cM*w. More...

virtual void	IntLoadResidual_CqL (const unsigned int off_L, ChVectorDynamic<> &R, const ChVectorDynamic<> &L, const double c) override
	Takes the term Cq'L, scale and adds to R at given offset: R += cCq'*L. More...

virtual void	IntLoadConstraint_C (const unsigned int off, ChVectorDynamic<> &Qc, const double c, bool do_clamp, double recovery_clamp) override
	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) override
	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) 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	InjectVariables (ChSystemDescriptor &mdescriptor) 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	InjectConstraints (ChSystemDescriptor &mdescriptor) override
	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	ConstraintsLoadJacobians () override
	Adds the current jacobians in encapsulated ChConstraints.

virtual void	InjectKRMmatrices (ChSystemDescriptor &mdescriptor) 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	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	VariablesFbIncrementMq () override
	Adds M*q (masses multiplied current 'qb') to Fb, ex. More...

virtual void	VariablesQbSetSpeed (double step=0) override
	Fetches the item speed (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	ConstraintsBiReset () override
	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) override
	Adds the current C (constraint violation) to the known term (b_i) of encapsulated ChConstraints.

virtual void	ConstraintsBiLoad_Ct (double factor=1) override
	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) override
	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	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.

virtual void	ConstraintsFetch_react (double factor=1) override
	Fetches the reactions from the lagrangian multiplier (l_i) of encapsulated ChConstraints. More...

virtual int	GetNcoords_x () override
	Tells the number of position coordinates x in y = {x, v}.

virtual int	GetNcoords_v () override
	Tells the number of speed coordinates of v in y = {x, v} and dy/dt={v, a}.

virtual int	GetNconstr () override
	Tells the number of lagrangian multipliers (constraints)

virtual void	StateGather (ChState &x, ChStateDelta &v, double &T) override
	From system to state y={x,v}.

virtual void	StateScatter (const ChState &x, const ChStateDelta &v, const double T) override
	From state Y={x,v} to system.

virtual void	StateGatherAcceleration (ChStateDelta &a) override
	From system to state derivative (acceleration), some timesteppers might need last computed accel.

virtual void	StateScatterAcceleration (const ChStateDelta &a) override
	From state derivative (acceleration) to system, sometimes might be needed.

virtual void	StateGatherReactions (ChVectorDynamic<> &L) override
	From system to reaction forces (last computed) - some timestepper might need this.

virtual void	StateScatterReactions (const ChVectorDynamic<> &L) override
	From reaction forces to system, ex. store last computed reactions in ChLink objects for plotting etc.

virtual void	StateIncrementX (ChState &x_new, const ChState &x, const ChStateDelta &Dx) override
	Perform x_new = x + dx, for x in Y = {x, dx/dt}. More...

virtual bool	StateSolveCorrection (ChStateDelta &Dv, ChVectorDynamic<> &L, const ChVectorDynamic<> &R, const ChVectorDynamic<> &Qc, const double c_a, const double c_v, const double c_x, const ChState &x, const ChStateDelta &v, const double T, bool force_state_scatter=true, bool force_setup=true) override
	Assuming a DAE of the form. More...

virtual void	LoadResidual_F (ChVectorDynamic<> &R, const double c) override
	Increment a vector R with the term cF: R += cF. More...

virtual void	LoadResidual_Mv (ChVectorDynamic<> &R, const ChVectorDynamic<> &w, const double c) override
	Increment a vector R with a term that has M multiplied a given vector w: R += cMw. More...

virtual void	LoadResidual_CqL (ChVectorDynamic<> &R, const ChVectorDynamic<> &L, const double c) override
	Increment a vectorR with the term Cq'L: R += cCq'*L. More...

virtual void	LoadConstraint_C (ChVectorDynamic<> &Qc, const double c, const bool do_clamp=false, const double mclam=1e30) override
	Increment a vector Qc with the term C: Qc += c*C. More...

virtual void	LoadConstraint_Ct (ChVectorDynamic<> &Qc, const double c) override
	Increment a vector Qc with the term Ct = partial derivative dC/dt: Qc += c*Ct. More...

virtual void	CustomEndOfStep ()
	Executes custom processing at the end of step. More...

void	SynchronizeLastCollPositions ()
	All bodies with collision detection data are requested to store the current position as "last position collision-checked".

double	ComputeCollisions ()
	Perform the collision detection. More...

void	RegisterCustomCollisionCallback (CustomCollisionCallback *mcallb)
	Specify a callback object to be invoked at each collision detection step. More...

void	SetCollisionSystem (std::shared_ptr< collision::ChCollisionSystem > newcollsystem)
	For higher performance (ex. More...

std::shared_ptr< collision::ChCollisionSystem >	GetCollisionSystem () const
	Access the collision system, the engine which computes the contact points (usually you don't need to access it, since it is automatically handled by the client ChSystem object).

void	SetUseSleeping (bool ms)
	Turn on this feature to let the system put to sleep the bodies whose motion has almost come to a rest. More...

bool	GetUseSleeping () const
	Tell if the system will put to sleep the bodies whose motion has almost come to a rest.

int	DoStepDynamics (double m_step)
	Advances the dynamical simulation for a single step, of length m_step. More...

bool	DoFrameDynamics (double m_endtime)
	Performs integration until the m_endtime is exactly reached, but current time step may be automatically "retouched" to meet exactly the m_endtime after n steps. More...

bool	DoEntireDynamics ()
	Given the current state, the sw simulates the dynamical behavior of the system, until the end time is reached, repeating many steps (maybe the step size will be automatically changed if the integrator method supports step size adaption).

bool	DoEntireUniformDynamics (double frame_step)
	Like "DoEntireDynamics", but results are provided at uniform steps "frame_step", using the DoFrameDynamics() many times.

size_t	GetStepcount () const
	Return the total number of time steps taken so far.

void	ResetStepcount ()
	Reset to 0 the total number of time steps.

int	GetSolverCallsCount () const
	Return the number of calls to the solver's Solve() function. More...

int	GetSolverSetupCount () const
	Return the number of calls to the solver's Setup() function. More...

void	SetDumpSolverMatrices (bool md)
	Set this to "true" to enable automatic saving of solver matrices at each time step, for debugging purposes. More...

bool	GetDumpSolverMatrices () const

void	DumpSystemMatrices (bool save_M, bool save_K, bool save_R, bool save_Cq, const char *path)
	Dump the current M mass matrix, K damping matrix, R damping matrix, Cq constraint jacobian matrix (at the current configuration). More...

void	GetMassMatrix (ChSparseMatrix *M)
	Compute the system-level mass matrix. More...

void	GetStiffnessMatrix (ChSparseMatrix *K)
	Compute the system-level stiffness matrix, i.e. More...

void	GetDampingMatrix (ChSparseMatrix *R)
	Compute the system-level damping matrix, i.e. More...

void	GetConstraintJacobianMatrix (ChSparseMatrix *Cq)
	Compute the system-level constraint jacobian matrix, i.e. More...

bool	DoStepKinematics (double m_step)
	Advances the kinematic simulation for a single step, of length m_step. More...

bool	DoFrameKinematics (double m_endtime)
	Performs kinematics until the m_endtime is exactly reached, but current time step may be automatically "retouched" to meet exactly the m_endtime after n steps.

bool	DoEntireKinematics ()
	Given the current state, this kinematic simulation satisfies all the constraints with the "DoStepKinematics" procedure for each time step, from the current time to the end time.

bool	DoAssembly (int action)
	Given the current time and state, attempt to satisfy all constraints, using a Newton-Raphson iteration loop. More...

bool	DoFullAssembly ()
	Shortcut for full position/velocity/acceleration assembly.

bool	DoStaticLinear ()
	Solve the position of static equilibrium (and the reactions). More...

bool	DoStaticNonlinear (int nsteps=10, bool verbose=false)
	Solve the position of static equilibrium (and the reactions). More...

bool	DoStaticNonlinear (std::shared_ptr< ChStaticNonLinearAnalysis > analysis)
	Solve the position of static equilibrium (and the reactions). More...

bool	DoStaticRelaxing (int nsteps=10)
	Finds the position of static equilibrium (and the reactions) starting from the current position. 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.

int	FileProcessChR (ChStreamInBinary &m_file)
	Process a ".chr" binary file containing the full system object hierarchy as exported -for example- by the R3D modeler, with chrono plug-in version, or by using the FileWriteChR() function.

int	FileWriteChR (ChStreamOutBinary &m_file)
	Write a ".chr" binary file containing the full system object hierarchy (bodies, forces, links, etc.) (deprecated function - obsolete)

Public Member Functions inherited from chrono::ChAssembly
	ChAssembly (const ChAssembly &other)

virtual ChAssembly *	Clone () const override
	"Virtual" copy constructor (covariant return type).

void	Clear ()
	Removes all inserted items: bodies, links, etc.

virtual void	AddBody (std::shared_ptr< ChBody > body)
	Attach a body to this assembly.

virtual void	AddLink (std::shared_ptr< ChLinkBase > link)
	Attach a link to this assembly.

virtual void	AddMesh (std::shared_ptr< fea::ChMesh > mesh)
	Attach a mesh to this assembly.

virtual void	AddOtherPhysicsItem (std::shared_ptr< ChPhysicsItem > item)
	Attach a ChPhysicsItem object that is not a body, link, or mesh.

void	Add (std::shared_ptr< ChPhysicsItem > item)
	Attach an arbitrary ChPhysicsItem (e.g. More...

void	AddBatch (std::shared_ptr< ChPhysicsItem > item)
	Items added in this way are added like in the Add() method, but not instantly, they are simply queued in a batch of 'to add' items, that are added automatically at the first Setup() call. More...

void	FlushBatch ()
	If some items are queued for addition in the assembly, using AddBatch(), this will effectively add them and clean the batch. More...

virtual void	RemoveBody (std::shared_ptr< ChBody > body)
	Remove a body from this assembly.

virtual void	RemoveLink (std::shared_ptr< ChLinkBase > link)
	Remove a link from this assembly.

virtual void	RemoveMesh (std::shared_ptr< fea::ChMesh > mesh)
	Remove a mesh from the assembly.

virtual void	RemoveOtherPhysicsItem (std::shared_ptr< ChPhysicsItem > item)
	Remove a ChPhysicsItem object that is not a body or a link.

void	Remove (std::shared_ptr< ChPhysicsItem > item)
	Remove arbitrary ChPhysicsItem that was added to the assembly.

void	RemoveAllBodies ()
	Remove all bodies from this assembly.

void	RemoveAllLinks ()
	Remove all links from this assembly.

void	RemoveAllMeshes ()
	Remove all meshes from this assembly.

void	RemoveAllOtherPhysicsItems ()
	Remove all physics items not in the body, link, or mesh lists.

const std::vector< std::shared_ptr< ChBody > > &	Get_bodylist () const
	Get the list of bodies.

const std::vector< std::shared_ptr< ChLinkBase > > &	Get_linklist () const
	Get the list of links.

const std::vector< std::shared_ptr< fea::ChMesh > > &	Get_meshlist () const
	Get the list of meshes.

const std::vector< std::shared_ptr< ChPhysicsItem > > &	Get_otherphysicslist () const
	Get the list of physics items that are not in the body or link lists.

std::shared_ptr< ChBody >	SearchBody (const char *name)
	Search a body by its name.

std::shared_ptr< ChLinkBase >	SearchLink (const char *name)
	Search a link by its name.

std::shared_ptr< fea::ChMesh >	SearchMesh (const char *name)
	Search a mesh by its name.

std::shared_ptr< ChPhysicsItem >	SearchOtherPhysicsItem (const char *name)
	Search from other ChPhysics items (not bodies, links, or meshes) by name.

std::shared_ptr< ChPhysicsItem >	Search (const char *name)
	Search an item (body, link or other ChPhysics items) by name.

std::shared_ptr< ChBody >	SearchBodyID (int markID)
	Search a body by its ID.

std::shared_ptr< ChMarker >	SearchMarker (const char *name)
	Search a marker by its name.

std::shared_ptr< ChMarker >	SearchMarker (int markID)
	Search a marker by its unique ID.

int	GetNbodies () const
	Get the number of active bodies (so, excluding those that are sleeping or are fixed to ground).

int	GetNbodiesSleeping () const
	Get the number of bodies that are in sleeping mode (excluding fixed bodies).

int	GetNbodiesFixed () const
	Get the number of bodies that are fixed to ground.

int	GetNbodiesTotal () const
	Get the total number of bodies added to the assembly, including the grounded and sleeping bodies.

int	GetNlinks () const
	Get the number of links.

int	GetNmeshes () const
	Get the number of meshes.

int	GetNphysicsItems () const
	Get the number of other physics items (other than bodies, links, or meshes).

int	GetNcoords () const
	Get the number of coordinates (considering 7 coords for rigid bodies because of the 4 dof of quaternions).

int	GetNdof () const
	Get the number of degrees of freedom of the assembly.

int	GetNdoc () const
	Get the number of scalar constraints added to the assembly, including constraints on quaternion norms.

int	GetNsysvars () const
	Get the number of system variables (coordinates plus the constraint multipliers, in case of quaternions).

int	GetNcoords_w () const
	Get the number of coordinates (considering 6 coords for rigid bodies, 3 transl.+3rot.)

int	GetNdoc_w () const
	Get the number of scalar constraints added to the assembly.

int	GetNdoc_w_C () const
	Get the number of scalar constraints added to the assembly (only bilaterals).

int	GetNdoc_w_D () const
	Get the number of scalar constraints added to the assembly (only unilaterals).

int	GetNsysvars_w () const
	Get the number of system variables (coordinates plus the constraint multipliers).

virtual void	SetSystem (ChSystem *m_system) override
	Set the pointer to the parent ChSystem() and also add to new collision system / remove from old coll.system.

virtual void	SyncCollisionModels () override
	If this physical item contains one or more collision models, synchronize their coordinates and bounding boxes to the state of the item.

virtual void	Update (double mytime, bool update_assets=true) override
	Updates all the auxiliary data and children of bodies, forces, links, given their current state.

virtual void	SetNoSpeedNoAcceleration () override
	Set zero speed (and zero accelerations) in state, without changing the position.

virtual int	GetDOF () override
	Get the number of scalar coordinates (ex. dim of position vector)

virtual int	GetDOF_w () override
	Get the number of scalar coordinates of variables derivatives (ex. dim of speed vector)

virtual int	GetDOC () override
	Get the number of scalar constraints, if any, in this item.

virtual int	GetDOC_c () override
	Get the number of scalar constraints, if any, in this item (only bilateral constr.)

virtual int	GetDOC_d () override
	Get the number of scalar constraints, if any, in this item (only unilateral constr.)

void	ShowHierarchy (ChStreamOutAscii &m_file, int level=0)
	Writes the hierarchy of contained bodies, markers, etc. More...

Public Member Functions inherited from chrono::ChPhysicsItem
	ChPhysicsItem (const ChPhysicsItem &other)

ChSystem *	GetSystem () const
	Get the pointer to the parent ChSystem()

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< ChAsset >	GetAssetN (unsigned int num)
	Access the Nth asset in the list of optional assets.

virtual ChFrame	GetAssetsFrame (unsigned int nclone=0)
	Get the master coordinate system for assets that have some geometric meaning. More...

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	AddCollisionModelsToSystem ()
	If this physical item contains one or more collision models, add them to the system's collision engine.

virtual void	RemoveCollisionModelsFromSystem ()
	If this physical item contains one or more collision models, remove them from the system's collision engine.

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.

virtual void	StreamOUTstate (ChStreamOutBinary &mstream)
	Method to serialize only the state (position, speed) Must be implemented by child classes.

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.

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 ()

Public Member Functions inherited from chrono::ChIntegrableIIorder
virtual int	GetNcoords_a ()
	Return the number of acceleration coordinates of a in dy/dt={v, a} This is a default implementation that works in almost all cases, as dim(a) = dim(v),.

virtual void	StateSetup (ChState &x, ChStateDelta &v, ChStateDelta &a)
	Set up the system state with separate II order components x, v, a for y = {x, v} and dy/dt={v, a}.

virtual bool	StateSolveA (ChStateDelta &Dvdt, ChVectorDynamic<> &L, const ChState &x, const ChStateDelta &v, const double T, const double dt, bool force_state_scatter=true)
	Solve for accelerations: a = f(x,v,t) Given current state y={x,v} , computes acceleration a in the state derivative dy/dt={v,a} and lagrangian multipliers L (if any). More...

virtual int	GetNcoords_y () override
	Return the number of coordinates in the state Y. More...

virtual int	GetNcoords_dy () override
	Return the number of coordinates in the state increment. More...

virtual void	StateGather (ChState &y, double &T) override
	Gather system state in specified array. More...

virtual void	StateScatter (const ChState &y, const double T) override
	Scatter the states from the provided array to the system. More...

virtual void	StateGatherDerivative (ChStateDelta &Dydt) override
	Gather from the system the state derivatives in specified array. More...

virtual void	StateScatterDerivative (const ChStateDelta &Dydt) override
	Scatter the state derivatives from the provided array to the system. More...

virtual void	StateIncrement (ChState &y_new, const ChState &y, const ChStateDelta &Dy) override
	Increment state array: y_new = y + Dy. More...

virtual bool	StateSolve (ChStateDelta &dydt, ChVectorDynamic<> &L, const ChState &y, const double T, const double dt, bool force_state_scatter=true) override
	Solve for state derivatives: dy/dt = f(y,t). More...

virtual bool	StateSolveCorrection (ChStateDelta &Dy, ChVectorDynamic<> &L, const ChVectorDynamic<> &R, const ChVectorDynamic<> &Qc, const double a, const double b, const ChState &y, const double T, const double dt, bool force_state_scatter=true, bool force_setup=true) override
	This was for Ist order implicit integrators, but here we disable it.

Public Member Functions inherited from chrono::ChIntegrable
virtual void	StateSetup (ChState &y, ChStateDelta &dy)
	Set up the system state.

virtual void	LoadResidual_Hv (ChVectorDynamic<> &R, const ChVectorDynamic<> &v, const double c)
	Increment a vector R (usually the residual in a Newton Raphson iteration for solving an implicit integration step) with a term that has H multiplied a given vector w: R += cHw. More...

Protected Member Functions
virtual void	DescriptorPrepareInject (ChSystemDescriptor &mdescriptor)
	Pushes all ChConstraints and ChVariables contained in links, bodies, etc. into the system descriptor.

Protected Attributes
std::shared_ptr< ChContactContainer >	contact_container
	the container of contacts

ChVector	G_acc
	gravitational acceleration

bool	is_initialized
	if false, an initial setup is required (i.e. a call to SetupInitial)

bool	is_updated
	if false, a new update is required (i.e. a call to Update)

double	end_time
	end of simulation

double	step
	time step

double	step_min
	min time step

double	step_max
	max time step

double	tol_force
	tolerance for forces (used to obtain a tolerance for impulses)

int	maxiter
	max iterations for nonlinear convergence in DoAssembly()

bool	use_sleeping
	if true, put to sleep objects that come to rest

std::shared_ptr< ChSystemDescriptor >	descriptor
	system descriptor

std::shared_ptr< ChSolver >	solver
	solver for DVI or DAE problem

double	min_bounce_speed
	minimum speed for rebounce after impacts. Lower speeds are clamped to 0

double	max_penetration_recovery_speed
	limit for the speed of penetration recovery (positive, speed of exiting)

size_t	stepcount
	internal counter for steps

int	setupcount
	number of calls to the solver's Setup()

int	solvecount
	number of StateSolveCorrection (reset to 0 at each timestep of static analysis)

bool	dump_matrices
	for debugging

int	ncontacts
	total number of contacts

std::shared_ptr< collision::ChCollisionSystem >	collision_system
	collision engine

std::vector< CustomCollisionCallback * >	collision_callbacks

std::unique_ptr< ChMaterialCompositionStrategy< float > >	composition_strategy

ChTimer< double >	timer_step
	material composition strategy More...

ChTimer< double >	timer_advance
	timer for time integration

ChTimer< double >	timer_solver
	timer for solver (excluding setup phase)

ChTimer< double >	timer_setup
	timer for solver setup

ChTimer< double >	timer_jacobian
	timer for computing/loading Jacobian information

ChTimer< double >	timer_collision
	timer for collision detection

ChTimer< double >	timer_update
	timer for system update

std::shared_ptr< ChTimestepper >	timestepper
	time-stepper object

bool	last_err
	indicates error over the last kinematic/dynamics/statics

Protected Attributes inherited from chrono::ChAssembly
std::vector< std::shared_ptr< ChBody > >	bodylist
	list of rigid bodies

std::vector< std::shared_ptr< ChLinkBase > >	linklist
	list of joints (links)

std::vector< std::shared_ptr< fea::ChMesh > >	meshlist
	list of meshes

std::vector< std::shared_ptr< ChPhysicsItem > >	otherphysicslist
	list of other physics objects

std::vector< std::shared_ptr< ChPhysicsItem > >	batch_to_insert
	list of items to insert at once

int	nbodies
	number of bodies (currently active)

int	nlinks
	number of links

int	nmeshes
	number of meshes

int	nphysicsitems
	number of other physics items

int	ncoords
	number of scalar coordinates (including 4th dimension of quaternions) for all active bodies

int	ndoc
	number of scalar constraints (including constr. on quaternions)

int	nsysvars
	number of variables (coords+lagrangian mult.), i.e. = ncoords+ndoc for all active bodies

int	ncoords_w
	number of scalar coordinates when using 3 rot. dof. per body; for all active bodies

int	ndoc_w
	number of scalar constraints when using 3 rot. dof. per body; for all active bodies

int	nsysvars_w
	number of variables when using 3 rot. dof. per body; i.e. = ncoords_w+ndoc_w

int	ndof
	number of degrees of freedom, = ncoords-ndoc = ncoords_w-ndoc_w ,

int	ndoc_w_C
	number of scalar constraints C, when using 3 rot. dof. per body (excluding unilaterals)

int	ndoc_w_D
	number of scalar constraints D, when using 3 rot. dof. per body (only unilaterals)

int	nbodies_sleep
	number of bodies that are sleeping

int	nbodies_fixed
	number of bodies that are fixed

Protected Attributes inherited from chrono::ChPhysicsItem
ChSystem *	system
	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

Friends
class	ChAssembly

class	ChBody

class	fea::ChMesh

template<class Ta , class Tb >
class	ChContactNSC

template<class Ta , class Tb >
class	ChContactNSCrolling

template<class Ta , class Tb >
class	ChContactSMC

Member Function Documentation

◆ ComputeCollisions()

double chrono::ChSystem::ComputeCollisions ( )

Perform the collision detection.

New contacts are inserted in the ChContactContainer object(s), and old ones are removed. This is mostly called automatically by time integration.

◆ ConstraintsFetch_react()

void chrono::ChSystem::ConstraintsFetch_react ( double factor = 1 )

overridevirtual

Fetches the reactions from the lagrangian multiplier (l_i) of encapsulated ChConstraints.

Mostly used after the solver provided the solution in ChConstraints. Also, should convert the reactions obtained from dynamical simulation, from link space to intuitive react_force and react_torque.

Reimplemented from chrono::ChAssembly.

◆ CustomEndOfStep()

virtual void chrono::ChSystem::CustomEndOfStep ( )

inlinevirtual

Executes custom processing at the end of step.

By default it does nothing, but if you inherit a special ChSystem you can implement this.

◆ DoAssembly()

bool chrono::ChSystem::DoAssembly ( int action )

Given the current time and state, attempt to satisfy all constraints, using a Newton-Raphson iteration loop.

Used iteratively in inverse kinematics. Action can be one of AssemblyLevel::POSITION, AssemblyLevel::VELOCITY, or AssemblyLevel::ACCELERATION (or a combination of these) Returns true if no errors and false if an error occurred (impossible assembly?)

◆ DoFrameDynamics()

bool chrono::ChSystem::DoFrameDynamics ( double m_endtime )

Performs integration until the m_endtime is exactly reached, but current time step may be automatically "retouched" to meet exactly the m_endtime after n steps.

Useful when you want to advance the simulation in a simulations (3d modeling software etc.) which needs updates of the screen at a fixed rate (ex.30th of second) while the integration must use more steps.

◆ DoStaticLinear()

bool chrono::ChSystem::DoStaticLinear ( )

Solve the position of static equilibrium (and the reactions).

This is a one-step only approach that solves the linear equilibrium. Appropriate mostly for FEM problems with small deformations.

◆ DoStaticNonlinear() [1/2]

bool chrono::ChSystem::DoStaticNonlinear	(	int	nsteps = `10`,
		bool	verbose = `false`
	)

Solve the position of static equilibrium (and the reactions).

This function solves the equilibrium for the nonlinear problem (large displacements). This version uses a nonlinear static analysis solver with default parameters.

◆ DoStaticNonlinear() [2/2]

bool chrono::ChSystem::DoStaticNonlinear ( std::shared_ptr< ChStaticNonLinearAnalysis > analysis )

Solve the position of static equilibrium (and the reactions).

This function solves the equilibrium for the nonlinear problem (large displacements). This version uses the provided nonlinear static analysis solver.

◆ DoStaticRelaxing()

bool chrono::ChSystem::DoStaticRelaxing ( int nsteps = 10 )

Finds the position of static equilibrium (and the reactions) starting from the current position.

Since a truncated iterative method is used, you may need to call this method multiple times in case of large nonlinearities before coming to the precise static solution.

◆ DoStepDynamics()

int chrono::ChSystem::DoStepDynamics ( double m_step )

Advances the dynamical simulation for a single step, of length m_step.

You can call this function many times in order to simulate up to a desired end time. This is the most important function for analysis, you can use it, for example, once per screen refresh in VR and interactive realtime applications, etc.

◆ DoStepKinematics()

bool chrono::ChSystem::DoStepKinematics ( double m_step )

Advances the kinematic simulation for a single step, of length m_step.

You can call this function many times in order to simulate up to a desired end time.

◆ DumpSystemMatrices()

void chrono::ChSystem::DumpSystemMatrices	(	bool	save_M,
		bool	save_K,
		bool	save_R,
		bool	save_Cq,
		const char *	path
	)

Dump the current M mass matrix, K damping matrix, R damping matrix, Cq constraint jacobian matrix (at the current configuration).

These can be later used for linearized motion, modal analysis, buckling analysis, etc. The name of the files will be [path]_M.dat [path]_K.dat [path]_R.dat [path]_Cq.dat Might throw ChException if file can't be saved.

◆ ForceUpdate()

void chrono::ChSystem::ForceUpdate ( )

In normal usage, no system update is necessary at the beginning of a new dynamics step (since an update is performed at the end of a step).

However, this is not the case if external changes to the system are made. Most such changes are discovered automatically (addition/removal of items, input of mesh loads). For special cases, this function allows the user to trigger a system update at the beginning of the step immediately following this call.

◆ GetConstraintJacobianMatrix()

void chrono::ChSystem::GetConstraintJacobianMatrix ( ChSparseMatrix * Cq )

Compute the system-level constraint jacobian matrix, i.e.

the jacobian Cq=-dC/dq where C are constraints (the lower left part of the KKT matrix). This function has a small overhead, because it must assembly the sparse matrix -which is used only for the purpose of this function. fill this system damping matrix

◆ GetContactMethod()

virtual ChMaterialSurface::ContactMethod chrono::ChSystem::GetContactMethod ( ) const

pure virtual

Return the contact method supported by this system.

Bodies added to this system must be compatible.

Implemented in chrono::ChSystemParallelSMC, chrono::ChSystemParallelNSC, chrono::ChSystemSMC, and chrono::ChSystemNSC.

◆ GetDampingMatrix()

void chrono::ChSystem::GetDampingMatrix ( ChSparseMatrix * R )

Compute the system-level damping matrix, i.e.

the jacobian -dF/dv where F are stiff loads. Note that not all loads provide a jacobian, as this is optional in their implementation. This function has a small overhead, because it must assembly the sparse matrix -which is used only for the purpose of this function. fill this system damping matrix

◆ GetMassMatrix()

void chrono::ChSystem::GetMassMatrix ( ChSparseMatrix * M )

Compute the system-level mass matrix.

This function has a small overhead, because it must assembly the sparse matrix -which is used only for the purpose of this function. fill this system mass matrix

◆ GetSolverCallsCount()

int chrono::ChSystem::GetSolverCallsCount ( ) const

inline

Return the number of calls to the solver's Solve() function.

This counter is reset at each timestep.

◆ GetSolverMaxIterations()

int chrono::ChSystem::GetSolverMaxIterations ( ) const

Get the current maximum number of iterations, if using an iterative solver.

Deprecated:: Prefer using GetSolver and accessing solver statistics directly.

◆ GetSolverSetupCount()

int chrono::ChSystem::GetSolverSetupCount ( ) const

inline

Return the number of calls to the solver's Setup() function.

This counter is reset at each timestep.

◆ GetStiffnessMatrix()

void chrono::ChSystem::GetStiffnessMatrix ( ChSparseMatrix * K )

Compute the system-level stiffness matrix, i.e.

the jacobian -dF/dq where F are stiff loads. Note that not all loads provide a jacobian, as this is optional in their implementation. This function has a small overhead, because it must assembly the sparse matrix -which is used only for the purpose of this function. fill this system stiffness matrix

◆ GetTimerSolver()

virtual double chrono::ChSystem::GetTimerSolver ( ) const

inlinevirtual

Return the time (in seconds) for the solver, within the time step.

Note that this time excludes any calls to the solver's Setup function.

Reimplemented in chrono::ChSystemParallel.

◆ IntFromDescriptor()

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

overridevirtual

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

Parameters

off_v	offset for v
v	vector to where the q 'unknowns' term of the variables will be copied
off_L	offset for L
L	vector to where L 'lagrangian ' term of the constraints will be copied

Reimplemented from chrono::ChAssembly.

◆ IntLoadConstraint_C()

void chrono::ChSystem::IntLoadConstraint_C	(	const unsigned int	off,
		ChVectorDynamic<> &	Qc,
		const double	c,
		bool	do_clamp,
		double	recovery_clamp
	)

overridevirtual

Takes the term C, scale and adds to Qc at given offset: Qc += c*C.

Parameters

off	offset in Qc residual
Qc	result: the Qc residual, Qc += c*C
c	a scaling factor
do_clamp	apply clamping to c*C?
recovery_clamp	value for min/max clamping of c*C

Reimplemented from chrono::ChAssembly.

◆ IntLoadConstraint_Ct()

void chrono::ChSystem::IntLoadConstraint_Ct	(	const unsigned int	off,
		ChVectorDynamic<> &	Qc,
		const double	c
	)

overridevirtual

Takes the term Ct, scale and adds to Qc at given offset: Qc += c*Ct.

Parameters

off	offset in Qc residual
Qc	result: the Qc residual, Qc += c*Ct
c	a scaling factor

Reimplemented from chrono::ChAssembly.

◆ IntLoadResidual_CqL()

void chrono::ChSystem::IntLoadResidual_CqL	(	const unsigned int	off_L,
		ChVectorDynamic<> &	R,
		const ChVectorDynamic<> &	L,
		const double	c
	)

overridevirtual

Takes the term Cq'*L, scale and adds to R at given offset: R += c*Cq'*L.

Parameters

off_L	offset in L multipliers
R	result: the R residual, R += cCq'L
L	the L vector
c	a scaling factor

Reimplemented from chrono::ChAssembly.

◆ IntLoadResidual_F()

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

overridevirtual

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

Parameters

off	offset in R residual
R	result: the R residual, R += c*F
c	a scaling factor

Reimplemented from chrono::ChAssembly.

◆ IntLoadResidual_Mv()

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

overridevirtual

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

Parameters

off	offset in R residual
R	result: the R residual, R += cMv
w	the w vector
c	a scaling factor

Reimplemented from chrono::ChAssembly.

◆ IntStateGather()

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

overridevirtual

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

Parameters

off_x	offset in x state vector
x	state vector, position part
off_v	offset in v state vector
v	state vector, speed part
T	time

Reimplemented from chrono::ChAssembly.

◆ IntStateGatherAcceleration()

void chrono::ChSystem::IntStateGatherAcceleration	(	const unsigned int	off_a,
		ChStateDelta &	a
	)

overridevirtual

From item's state acceleration to global acceleration vector.

Parameters

off_a	offset in a accel. vector
a	acceleration part of state vector derivative

Reimplemented from chrono::ChAssembly.

◆ IntStateGatherReactions()

void chrono::ChSystem::IntStateGatherReactions	(	const unsigned int	off_L,
		ChVectorDynamic<> &	L
	)

overridevirtual

From item's reaction forces to global reaction vector.

Parameters

off_L	offset in L vector
L	L vector of reaction forces

Reimplemented from chrono::ChAssembly.

◆ IntStateIncrement()

void chrono::ChSystem::IntStateIncrement	(	const unsigned int	off_x,
		ChState &	x_new,
		const ChState &	x,
		const unsigned int	off_v,
		const ChStateDelta &	Dv
	)

overridevirtual

Computes x_new = x + Dt , using vectors at specified offsets.

By default, when DOF = DOF_w, it does just the sum, but in some cases (ex when using quaternions for rotations) it could do more complex stuff, and children classes might overload it.

Parameters

off_x	offset in x state vector
x_new	state vector, position part, incremented result
x	state vector, initial position part
off_v	offset in v state vector
Dv	state vector, increment

Reimplemented from chrono::ChAssembly.

◆ IntStateScatter()

void chrono::ChSystem::IntStateScatter	(	const unsigned int	off_x,
		const ChState &	x,
		const unsigned int	off_v,
		const ChStateDelta &	v,
		const double	T
	)

overridevirtual

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

Parameters

off_x	offset in x state vector
x	state vector, position part
off_v	offset in v state vector
v	state vector, speed part
T	time

Reimplemented from chrono::ChAssembly.

◆ IntStateScatterAcceleration()

void chrono::ChSystem::IntStateScatterAcceleration	(	const unsigned int	off_a,
		const ChStateDelta &	a
	)

overridevirtual

From global acceleration vector to item's state acceleration.

Parameters

off_a	offset in a accel. vector
a	acceleration part of state vector derivative

Reimplemented from chrono::ChAssembly.

◆ IntStateScatterReactions()

void chrono::ChSystem::IntStateScatterReactions	(	const unsigned int	off_L,
		const ChVectorDynamic<> &	L
	)

overridevirtual

From global reaction vector to item's reaction forces.

Parameters

off_L	offset in L vector
L	L vector of reaction forces

Reimplemented from chrono::ChAssembly.

◆ IntToDescriptor()

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

overridevirtual

Prepare variables and constraints to accommodate a solution:

Parameters

off_v	offset for v and R
v	vector that will be copied into the q 'unknowns' term of the variables (for warm starting)
R	vector that will be copied into the F 'force' term of the variables
off_L	offset for L and Qc
L	vector that will be copied into the L 'lagrangian ' term of the constraints (for warm starting)
Qc	vector that will be copied into the Qb 'constraint' term of the constraints

Reimplemented from chrono::ChAssembly.

◆ KRMmatricesLoad()

void chrono::ChSystem::KRMmatricesLoad	(	double	Kfactor,
		double	Rfactor,
		double	Mfactor
	)

overridevirtual

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::ChAssembly.

◆ LoadConstraint_C()

void chrono::ChSystem::LoadConstraint_C	(	ChVectorDynamic<> &	Qc,
		const double	c,
		const bool	do_clamp = `false`,
		const double	mclam = `1e30`
	)

overridevirtual

Increment a vector Qc with the term C: Qc += c*C.

Parameters

Qc	result: the Qc residual, Qc += c*C
c	a scaling factor
do_clamp	enable optional clamping of Qc
mclam	clamping value

Reimplemented from chrono::ChIntegrableIIorder.

◆ LoadConstraint_Ct()

void chrono::ChSystem::LoadConstraint_Ct	(	ChVectorDynamic<> &	Qc,
		const double	c
	)

overridevirtual

Increment a vector Qc with the term Ct = partial derivative dC/dt: Qc += c*Ct.

Parameters

Qc	result: the Qc residual, Qc += c*Ct
c	a scaling factor

Reimplemented from chrono::ChIntegrableIIorder.

◆ LoadResidual_CqL()

void chrono::ChSystem::LoadResidual_CqL	(	ChVectorDynamic<> &	R,
		const ChVectorDynamic<> &	L,
		const double	c
	)

overridevirtual

Increment a vectorR with the term Cq'*L: R += c*Cq'*L.

Parameters

R	result: the R residual, R += cCq'L
L	the L vector
c	a scaling factor

Reimplemented from chrono::ChIntegrableIIorder.

◆ LoadResidual_F()

void chrono::ChSystem::LoadResidual_F	(	ChVectorDynamic<> &	R,
		const double	c
	)

overridevirtual

Increment a vector R with the term c*F: R += c*F.

Parameters

R	result: the R residual, R += c*F
c	a scaling factor

Reimplemented from chrono::ChIntegrableIIorder.

◆ LoadResidual_Mv()

void chrono::ChSystem::LoadResidual_Mv	(	ChVectorDynamic<> &	R,
		const ChVectorDynamic<> &	w,
		const double	c
	)

overridevirtual

Increment a vector R with a term that has M multiplied a given vector w: R += c*M*w.

Parameters

R	result: the R residual, R += cMv
w	the w vector
c	a scaling factor

Reimplemented from chrono::ChIntegrableIIorder.

◆ NewBody()

virtual ChBody* chrono::ChSystem::NewBody ( )

pure virtual

Create and return the pointer to a new body.

The returned body is created with a contact model consistent with the type of this ChSystem and with the collision system currently associated with this ChSystem. Note that the body is not attached to this system.

Implemented in chrono::ChSystemParallelSMC, chrono::ChSystemParallelNSC, chrono::ChSystemDistributed, chrono::ChSystemSMC, and chrono::ChSystemNSC.

◆ NewBodyAuxRef()

virtual ChBodyAuxRef* chrono::ChSystem::NewBodyAuxRef ( )

pure virtual

Create and return the pointer to a new body with auxiliary reference frame.

The returned body is created with a contact model consistent with the type of this ChSystem and with the collision system currently associated with this ChSystem. Note that the body is not attached to this system.

Implemented in chrono::ChSystemParallelSMC, chrono::ChSystemParallelNSC, chrono::ChSystemDistributed, chrono::ChSystemSMC, and chrono::ChSystemNSC.

◆ Reference_LM_byID()

void chrono::ChSystem::Reference_LM_byID ( )

Given inserted markers and links, restores the pointers of links to markers given the information about the marker IDs.

Will be made obsolete in future with new serialization systems.

◆ RegisterCustomCollisionCallback()

void chrono::ChSystem::RegisterCustomCollisionCallback ( CustomCollisionCallback * mcallb )

inline

Specify a callback object to be invoked at each collision detection step.

Multiple such callback objects can be registered with a system. If present, their OnCustomCollision() method is invoked Use this if you want that some specific callback function is executed at each collision detection step (ex. all the times that ComputeCollisions() is automatically called by the integration method). For example some other collision engine could add further contacts using this callback.

◆ SetCollisionSystem()

void chrono::ChSystem::SetCollisionSystem ( std::shared_ptr< collision::ChCollisionSystem > newcollsystem )

For higher performance (ex.

when GPU coprocessors are available) you can create your own custom collision engine (inherited from ChCollisionSystem) and plug it into the system using this function. Note: use only before you start adding colliding bodies to the system!

◆ SetDumpSolverMatrices()

void chrono::ChSystem::SetDumpSolverMatrices ( bool md )

inline

Set this to "true" to enable automatic saving of solver matrices at each time step, for debugging purposes.

Note that matrices will be saved in the working directory of the exe, with format 0001_01_H.dat 0002_01_H.dat (if the timestepper requires multiple solves, also 0001_01. 0001_02.. etc.) The matrices being saved are: dump_Z.dat has the assembled optimization matrix (Matlab sparse format) dump_rhs.dat has the assembled RHS dump_H.dat has usually H=M (mass), but could be also H=a*M+b*K+c*R or such. (Matlab sparse format) dump_Cq.dat has the jacobians (Matlab sparse format) dump_E.dat has the constr.compliance (Matlab sparse format) dump_f.dat has the applied loads dump_b.dat has the constraint rhs as passed to the solver in the problem

 | H -Cq'|*|q|- | f|= |0|
 | Cq -E | |l|  |-b|  |c|

where l \(\in Y, c \in Ny\), normal cone to Y

◆ SetMaxiter()

void chrono::ChSystem::SetMaxiter ( int m_maxiter )

inline

Sets outer iteration limit for assembly constraints.

When trying to keep constraints together, the iterative process is stopped if this max.number of iterations (or tolerance) is reached.

◆ SetMaxPenetrationRecoverySpeed()

void chrono::ChSystem::SetMaxPenetrationRecoverySpeed ( double mval )

inline

For the default stepper, you can limit the speed of exiting from penetration situations.

Usually set a positive value, about 0.1 .. 2 . (as exiting speed, in m/s)

◆ SetMinBounceSpeed()

void chrono::ChSystem::SetMinBounceSpeed ( double mval )

inline

For elastic collisions, with objects that have nonzero restitution coefficient: objects will rebounce only if their relative colliding speed is above this threshold.

Default 0.15 m/s. If this is too low, aliasing problems can happen with small high frequency rebounces, and settling to static stacking might be more difficult.

◆ SetSolverForceTolerance()

void chrono::ChSystem::SetSolverForceTolerance ( double tolerance )

inline

Set a solver tolerance threshold at force level (default: not specified).

Specify this value only if solving the problem at velocity level (e.g. solving a DVI problem). If this tolerance is specified, it is multiplied by the current integration stepsize and overwrites the current solver tolerance. By default, this tolerance is invalid and hence the solver's own tolerance threshold is used.

◆ SetSolverMaxIterations()

void chrono::ChSystem::SetSolverMaxIterations ( int max_iters )

Set the maximum number of iterations, if using an iterative solver.

Deprecated:: Prefer using SetSolver and setting solver parameters directly.

◆ SetSolverTolerance()

void chrono::ChSystem::SetSolverTolerance ( double tolerance )

Set the solver tolerance threshold (used with iterative solvers only).

Note that the stopping criteria differs from solver to solver.

◆ SetSolverType()

void chrono::ChSystem::SetSolverType ( ChSolver::Type type )

virtual

Choose the solver type, to be used for the simultaneous solution of the constraints in dynamical simulations (as well as in kinematics, statics, etc.)

Suggested solver for speed, but lower precision: PSOR
Suggested solver for higher precision: BARZILAIBORWEIN or APGD
For problems that involve a stiffness matrix: GMRES, MINRES

Notes:

This function is a shortcut, internally equivalent to a call to SetSolver().
Only a subset of available Chrono solvers can be set through this mechanism.
Prefer explicitly creating a solver, setting solver parameters, and then attaching the solver with SetSolver.

Deprecated:: This function does not support all available Chrono solvers. Prefer using SetSolver.

◆ SetStep()

void chrono::ChSystem::SetStep ( double m_step )

inline

Sets the time step used for integration (dynamical simulation).

The lower this value, the more precise the simulation. Usually, values about 0.01 s are enough for simple simulations. It may be modified automatically by integration methods, if they support automatic time adaption.

◆ SetTimestepperType()

void chrono::ChSystem::SetTimestepperType ( ChTimestepper::Type type )

Set the method for time integration (time stepper type).

Suggested for fast dynamics with hard (NSC) contacts: EULER_IMPLICIT_LINEARIZED
Suggested for fast dynamics with hard (NSC) contacts and low inter-penetration: EULER_IMPLICIT_PROJECTED
Suggested for finite element smooth dynamics: HHT, EULER_IMPLICIT_LINEARIZED

Notes:

for more advanced customization, use SetTimestepper()
old methods ANITESCU and TASORA were replaced by EULER_IMPLICIT_LINEARIZED and EULER_IMPLICIT_PROJECTED, respectively

◆ Setup()

void chrono::ChSystem::Setup ( )

overridevirtual

Counts the number of bodies and links.

Computes the offsets of object states in the global state. Assumes that offset_x, offset_w, and offset_L are already set as starting point for offsetting all the contained sub objects.

Reimplemented from chrono::ChAssembly.

Reimplemented in chrono::ChSystemParallelSMC, and chrono::ChSystemParallel.

◆ SetUseSleeping()

void chrono::ChSystem::SetUseSleeping ( bool ms )

inline

Turn on this feature to let the system put to sleep the bodies whose motion has almost come to a rest.

This feature will allow faster simulation of large scenarios for real-time purposes, but it will affect the precision! This functionality can be turned off selectively for specific ChBodies.

◆ StateIncrementX()

void chrono::ChSystem::StateIncrementX	(	ChState &	x_new,
		const ChState &	x,
		const ChStateDelta &	Dx
	)

overridevirtual

Perform x_new = x + dx, for x in Y = {x, dx/dt}.

It takes care of the fact that x has quaternions, dx has angular vel etc. NOTE: the system is not updated automatically after the state increment, so one might need to call StateScatter() if needed.

Parameters

x_new	resulting x_new = x + Dx
x	initial state x
Dx	state increment Dx

Reimplemented from chrono::ChIntegrableIIorder.

◆ StateSolveCorrection()

bool chrono::ChSystem::StateSolveCorrection	(	ChStateDelta &	Dv,
		ChVectorDynamic<> &	L,
		const ChVectorDynamic<> &	R,
		const ChVectorDynamic<> &	Qc,
		const double	c_a,
		const double	c_v,
		const double	c_x,
		const ChState &	x,
		const ChStateDelta &	v,
		const double	T,
		bool	force_state_scatter = `true`,
		bool	force_setup = `true`
	)

overridevirtual

Assuming a DAE of the form.

      M*a = F(x,v,t) + Cq'*L
      C(x,t) = 0

this function computes the solution of the change Du (in a or v or x) for a Newton iteration within an implicit integration scheme.

 |Du| = [ G   Cq' ]^-1 * | R |
 |DL|   [ Cq  0   ]      | Qc|

for residual R and G = [ c_a*M + c_v*dF/dv + c_x*dF/dx ].
This function returns true if successful and false otherwise.

Parameters

Dv	result: computed Dv
L	result: computed lagrangian multipliers, if any
R	the R residual
Qc	the Qc residual
c_a	the factor in c_a*M
c_v	the factor in c_v*dF/dv
c_x	the factor in c_x*dF/dv
x	current state, x part
v	current state, v part
T	current time T
force_state_scatter	if false, x,v and T are not scattered to the system
force_setup	if true, call the solver's Setup() function

Reimplemented from chrono::ChIntegrableIIorder.

◆ VariablesFbIncrementMq()

void chrono::ChSystem::VariablesFbIncrementMq ( )

overridevirtual

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::ChAssembly.

◆ VariablesQbIncrementPosition()

void chrono::ChSystem::VariablesQbIncrementPosition ( double step )

overridevirtual

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::ChAssembly.

◆ VariablesQbLoadSpeed()

void chrono::ChSystem::VariablesQbLoadSpeed ( )

overridevirtual

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::ChAssembly.

◆ VariablesQbSetSpeed()

void chrono::ChSystem::VariablesQbSetSpeed ( double step = 0 )

overridevirtual

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::ChAssembly.

Member Data Documentation

◆ timer_step

ChTimer<double> chrono::ChSystem::timer_step

protected

material composition strategy

timer for integration step

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

/builds/uwsbel/chrono/src/chrono/physics/ChSystem.h
/builds/uwsbel/chrono/src/chrono/physics/ChSystem.cpp

Description

Classes

Public Member Functions

Protected Member Functions

Protected Attributes

Friends

Member Function Documentation

◆ ComputeCollisions()

◆ ConstraintsFetch_react()

◆ CustomEndOfStep()

◆ DoAssembly()

◆ DoFrameDynamics()

◆ DoStaticLinear()

◆ DoStaticNonlinear() [1/2]

◆ DoStaticNonlinear() [2/2]

◆ DoStaticRelaxing()

◆ DoStepDynamics()

◆ DoStepKinematics()

◆ DumpSystemMatrices()

◆ ForceUpdate()

◆ GetConstraintJacobianMatrix()

◆ GetContactMethod()

◆ GetDampingMatrix()

◆ GetMassMatrix()

◆ GetSolverCallsCount()

◆ GetSolverMaxIterations()

◆ GetSolverSetupCount()

◆ GetStiffnessMatrix()

◆ GetTimerSolver()

◆ IntFromDescriptor()

◆ IntLoadConstraint_C()

◆ IntLoadConstraint_Ct()

◆ IntLoadResidual_CqL()

◆ IntLoadResidual_F()

◆ IntLoadResidual_Mv()

◆ IntStateGather()

◆ IntStateGatherAcceleration()

◆ IntStateGatherReactions()

◆ IntStateIncrement()

◆ IntStateScatter()

◆ IntStateScatterAcceleration()

◆ IntStateScatterReactions()

◆ IntToDescriptor()

◆ KRMmatricesLoad()

◆ LoadConstraint_C()

◆ LoadConstraint_Ct()

◆ LoadResidual_CqL()

◆ LoadResidual_F()

◆ LoadResidual_Mv()

◆ NewBody()

◆ NewBodyAuxRef()

◆ Reference_LM_byID()

◆ RegisterCustomCollisionCallback()

◆ SetCollisionSystem()

◆ SetDumpSolverMatrices()

◆ SetMaxiter()

◆ SetMaxPenetrationRecoverySpeed()

◆ SetMinBounceSpeed()

◆ SetSolverForceTolerance()

◆ SetSolverMaxIterations()

◆ SetSolverTolerance()

◆ SetSolverType()

◆ SetStep()

◆ SetTimestepperType()

◆ Setup()

◆ SetUseSleeping()

◆ StateIncrementX()

◆ StateSolveCorrection()

◆ VariablesFbIncrementMq()

◆ VariablesQbIncrementPosition()

◆ VariablesQbLoadSpeed()

◆ VariablesQbSetSpeed()

Member Data Documentation

◆ timer_step