chrono::ChShaft Class Reference

Description

Class for one-degree-of-freedom mechanical parts with associated inertia (mass or moment of rotational inertia).

In most cases these represent shafts that can be used to build 1D models of power trains. This is more efficient than simulating power trains modeled with full 3D ChBody objects.

#include <ChShaft.h>

Inheritance diagram for chrono::ChShaft:
Collaboration diagram for chrono::ChShaft:

Public Member Functions

 ChShaft (const ChShaft &other)
 
virtual ChShaftClone () const override
 "Virtual" copy constructor (covariant return type).
 
void ForceToRest () override
 Set no speed and no accelerations (but does not change the position)
 
void SetAppliedLoad (double applied_load)
 Set the load applied to the shaft. More...
 
double GetAppliedLoad () const
 Get the load applied to the shaft. More...
 
void SetPos (double mp)
 Set the shaft position. More...
 
double GetPos () const
 Get the shaft position. More...
 
void SetPosDt (double mp)
 Set the shaft velocity. More...
 
double GetPosDt () const
 Get the shaft velocity. More...
 
void SetPosDt2 (double mp)
 Set the shaft acceleration. More...
 
double GetPosDt2 () const
 Get the shaft acceleration. More...
 
void SetInertia (double newJ)
 Inertia property of the shaft (must be a positive value). More...
 
double GetInertia () const
 Get the shaft inertia property.
 
void SetMaxSpeed (float m_max_speed)
 Set the maximum shaft speed (beyond this limit, the speed it will be clamped).
 
void ClampSpeed ()
 Clamp the shaft speed shaft is clamped to the range specified by SetMaxSpeed. More...
 
void SetSleepTime (float time)
 Set the duration before automatically placing the shaft in sleep mode when shaft movement is small.
 
void SetSleepMinSpeed (float speed)
 Set the max linear speed to be kept for 'sleep_time' before freezing.
 
void SetFixed (bool fixed)
 Fix or release this shaft. More...
 
bool IsFixed () const
 Return true if the shaft is set to fixed.
 
void SetLimitSpeed (bool limit)
 Enable limit on shaft speed (default: false).
 
void SetSleepingAllowed (bool sleeping)
 If use sleeping= true, shafts which do not rotate for too long time will be deactivated, for optimization. More...
 
bool IsSleepingAllowed () const
 Return true if this shaft is allowed to go to sleep.
 
void SetSleeping (bool ms)
 Force the shaft in sleeping mode or not. More...
 
bool IsSleeping () const
 Tell if the shaft is actually in sleeping state.
 
bool TrySleeping ()
 Put the shaft in sleeping state if requirements are satisfied.
 
virtual bool IsActive () const override
 Return true if the shaft is currently active and thereofre included into the system solver. More...
 
ChVariablesShaftVariables ()
 Returns reference to the encapsulated ChVariables,.
 
virtual void ArchiveOut (ChArchiveOut &archive_out) override
 Method to allow serialization of transient data to archives.
 
virtual void ArchiveIn (ChArchiveIn &archive_in) override
 Method to allow deserialization of transient data from archives.
 
unsigned int GetIndex () const
 Get the unique sequential shaft index (internal use only).
 
virtual unsigned int GetNumCoordsPosLevel () override
 Number of coordinates of the shaft.
 
virtual void InjectVariables (ChSystemDescriptor &descriptor) override
 Register with the given system descriptor any ChVariable objects associated with this item.
 
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 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<> &w, 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 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 unsigned int GetLoadableNumCoordsPosLevel () override
 Gets the number of DOFs affected by this element (position part)
 
virtual unsigned int GetLoadableNumCoordsVelLevel () override
 Gets the number of DOFs affected by this element (speed part)
 
virtual void LoadableGetStateBlockPosLevel (int block_offset, ChState &mD) override
 Gets all the DOFs packed in a single vector (position part)
 
virtual void LoadableGetStateBlockVelLevel (int block_offset, ChStateDelta &mD) override
 Gets all the DOFs packed in a single vector (speed part)
 
virtual void LoadableStateIncrement (const unsigned int off_x, ChState &x_new, const ChState &x, const unsigned int off_v, const ChStateDelta &Dv) override
 Increment all DOFs using a delta. More...
 
virtual unsigned int GetNumFieldCoords () override
 Number of coordinates in the interpolated field (e.g., 3 for a tetrahedron, 1 for a thermal problem, etc.).
 
virtual unsigned int GetNumSubBlocks () override
 Get the number of DOFs sub-blocks (e.g., 1 for a body, 4 for a tetrahedron, etc.).
 
virtual unsigned int GetSubBlockOffset (unsigned int nblock) override
 Get the offset of the specified sub-block of DOFs in global vector.
 
virtual unsigned int GetSubBlockSize (unsigned int nblock) override
 Get the size of the specified sub-block of DOFs in global vector.
 
virtual bool IsSubBlockActive (unsigned int nblock) const override
 Check if the specified sub-block of DOFs is active.
 
virtual void LoadableGetVariables (std::vector< ChVariables * > &mvars) override
 Get the pointers to the contained ChVariables, appending to the mvars vector.
 
- 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 IsCollisionEnabled () 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 ChAABB GetTotalAABB ()
 Get the entire AABB axis-aligned bounding box of the object. More...
 
virtual void GetCenter (ChVector3d &mcenter)
 Get a symbolic 'center' of the object. 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 Update (bool update_assets=true)
 As above, but does not require updating of time-dependent data. More...
 
virtual unsigned int GetNumCoordsVelLevel ()
 Get the number of coordinates at the velocity level. More...
 
virtual unsigned int GetNumConstraints ()
 Get the number of scalar constraints.
 
virtual unsigned int GetNumConstraintsBilateral ()
 Get the number of bilateral scalar constraints.
 
virtual unsigned int GetNumConstraintsUnilateral ()
 Get the number of unilateral scalar constraints.
 
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 &descriptor)
 Register with the given system descriptor any ChConstraint objects associated with this item.
 
virtual void LoadConstraintJacobians ()
 Compute and load current Jacobians in encapsulated ChConstraint objects.
 
virtual void InjectKRMMatrices (ChSystemDescriptor &descriptor)
 Register with the given system descriptor any ChKRMBlock objects associated with this item.
 
virtual void LoadKRMMatrices (double Kfactor, double Rfactor, double Mfactor)
 Compute and load current stiffnes (K), damping (R), and mass (M) matrices in encapsulated ChKRMBlock objects. 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 ConstraintsFbLoadForces (double factor=1)
 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)
 Fetches the reactions from the lagrangian multiplier (l_i) of encapsulated ChConstraints. More...
 
- Public Member Functions inherited from chrono::ChObj
 ChObj (const ChObj &other)
 
int GetIdentifier () const
 Get the unique integer identifier of this object. More...
 
void SetTag (int tag)
 Set an object integer tag (default: -1). More...
 
int GetTag () const
 Get the tag of this object.
 
void SetName (const std::string &myname)
 Set the name of this object.
 
std::string GetName () const
 Get the name of this object.
 
double GetChTime () const
 Gets the simulation time of this object.
 
void SetChTime (double m_time)
 Sets the simulation time of this object.
 
virtual std::string & ArchiveContainerName ()
 

Friends

class ChSystem
 
class ChSystemMulticore
 

Additional Inherited Members

- Protected Member Functions inherited from chrono::ChObj
int GenerateUniqueIdentifier ()
 
- 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
 object simulation time
 
std::string m_name
 object name
 
int m_identifier
 object unique identifier
 
int m_tag
 user-supplied tag
 

Member Function Documentation

◆ ClampSpeed()

void chrono::ChShaft::ClampSpeed ( )

Clamp the shaft speed shaft is clamped to the range specified by SetMaxSpeed.

The speed limit must be enabled (i.e., call first SetLimitSpeed(true)).

◆ GetAppliedLoad()

double chrono::ChShaft::GetAppliedLoad ( ) const
inline

Get the load applied to the shaft.

For shafts with a rotational degree of freedom, this represents the applied torque. For shafts with a translational degree of freedom, this is the applied force.

◆ GetPos()

double chrono::ChShaft::GetPos ( ) const
inline

Get the shaft position.

For shafts with a rotational degree of freedom, this represents an angle. For shafts with a translational degree of freedom, this represents a displacement.

◆ GetPosDt()

double chrono::ChShaft::GetPosDt ( ) const
inline

Get the shaft velocity.

For shafts with a rotational degree of freedom, this represents an angular velocity. For shafts with a translational degree of freedom, this represents a linear velocity.

◆ GetPosDt2()

double chrono::ChShaft::GetPosDt2 ( ) const
inline

Get the shaft acceleration.

For shafts with a rotational degree of freedom, this represents an angular acceleration. For shafts with a translational degree of freedom, this represents a linear acceleration.

◆ IntFromDescriptor()

void chrono::ChShaft::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_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::ChShaft::IntLoadLumpedMass_Md ( const unsigned int  off,
ChVectorDynamic<> &  Md,
double &  err,
const double  c 
)
overridevirtual

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

Reimplemented from chrono::ChPhysicsItem.

◆ IntLoadResidual_Mv()

void chrono::ChShaft::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
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::ChShaft::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_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::ChShaft::IntStateGatherAcceleration ( const unsigned int  off_a,
ChStateDelta a 
)
overridevirtual

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::ChShaft::IntStateScatter ( const unsigned int  off_x,
const ChState x,
const unsigned int  off_v,
const ChStateDelta v,
const double  T,
bool  full_update 
)
overridevirtual

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::ChShaft::IntStateScatterAcceleration ( const unsigned int  off_a,
const ChStateDelta a 
)
overridevirtual

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::ChShaft::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_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.

◆ IsActive()

virtual bool chrono::ChShaft::IsActive ( ) const
inlineoverridevirtual

Return true if the shaft is currently active and thereofre included into the system solver.

A shaft is inactive if it is fixed to ground or is in sleep mode.

Reimplemented from chrono::ChPhysicsItem.

◆ LoadableStateIncrement()

virtual void chrono::ChShaft::LoadableStateIncrement ( const unsigned int  off_x,
ChState x_new,
const ChState x,
const unsigned int  off_v,
const ChStateDelta Dv 
)
inlineoverridevirtual

Increment all DOFs using a delta.

Default is sum, but may override if ndof_x is different than ndof_w, for example with rotation quaternions and angular w vel. This could be invoked, for example, by the BDF differentiation that computes the jacobians.

Implements chrono::ChLoadable.

◆ SetAppliedLoad()

void chrono::ChShaft::SetAppliedLoad ( double  applied_load)
inline

Set the load applied to the shaft.

For shafts with a rotational degree of freedom, this represents the applied torque. For shafts with a translational degree of freedom, this is the applied force.

◆ SetFixed()

void chrono::ChShaft::SetFixed ( bool  fixed)

Fix or release this shaft.

If set to true, the shaft does not move, regardless of applied loads.

◆ SetInertia()

void chrono::ChShaft::SetInertia ( double  newJ)

Inertia property of the shaft (must be a positive value).

For rotational shafts, this is a moment of inertia. For translational shafts, this is a mass. Try not to mix physics items with too widely different inertia values, for numerical stability.

◆ SetPos()

void chrono::ChShaft::SetPos ( double  mp)
inline

Set the shaft position.

For shafts with a rotational degree of freedom, this represents an angle. For shafts with a translational degree of freedom, this represents a displacement.

◆ SetPosDt()

void chrono::ChShaft::SetPosDt ( double  mp)
inline

Set the shaft velocity.

For shafts with a rotational degree of freedom, this represents an angular velocity. For shafts with a translational degree of freedom, this represents a linear velocity.

◆ SetPosDt2()

void chrono::ChShaft::SetPosDt2 ( double  mp)
inline

Set the shaft acceleration.

For shafts with a rotational degree of freedom, this represents an angular acceleration. For shafts with a translational degree of freedom, this represents a linear acceleration.

◆ SetSleeping()

void chrono::ChShaft::SetSleeping ( bool  ms)
inline

Force the shaft in sleeping mode or not.

Note: Usually this state change is not handled by users, because it is mostly automatic.

◆ SetSleepingAllowed()

void chrono::ChShaft::SetSleepingAllowed ( bool  sleeping)
inline

If use sleeping= true, shafts which do not rotate for too long time will be deactivated, for optimization.

The realism is limited, but the simulation is faster.

◆ Update()

void chrono::ChShaft::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 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.

◆ VariablesFbIncrementMq()

void chrono::ChShaft::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::ChPhysicsItem.

◆ VariablesQbIncrementPosition()

void chrono::ChShaft::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 (Euler integration).

Reimplemented from chrono::ChPhysicsItem.

◆ VariablesQbLoadSpeed()

void chrono::ChShaft::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::ChPhysicsItem.

◆ VariablesQbSetSpeed()

void chrono::ChShaft::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::ChPhysicsItem.


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