chrono::ChShaft Class Reference

Description

Class for one-degree-of-freedom mechanical parts with associated inertia (mass, or J moment of intertial for rotating parts).

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 SetShaftFixed (bool mev)
 Sets the 'fixed' state of the shaft. More...
 
bool GetShaftFixed () const
 
void SetLimitSpeed (bool mlimit)
 Trick. More...
 
bool GetLimitSpeed () const
 
void SetUseSleeping (bool ms)
 Trick. More...
 
bool GetUseSleeping () const
 
void SetSleeping (bool ms)
 Force the shaft in sleeping mode or not (usually this state change is not handled by users, anyway, because it is mostly automatic). More...
 
bool GetSleeping () const
 Tell if the shaft is actually in sleeping state.
 
bool TrySleeping ()
 Put the shaft in sleeping state if requirements are satisfied.
 
bool IsActive () const
 Tell if the body is active, i.e. More...
 
void SetId (unsigned int identifier)
 Set the shaft id for indexing (only used internally)
 
unsigned int GetId () const
 Get the shaft id for indexing (only used internally)
 
virtual int GetDOF () override
 Number of coordinates of the shaft.
 
ChVariablesShaftVariables ()
 Returns reference to the encapsulated ChVariables,.
 
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.
 
virtual void IntStateScatterAcceleration (const unsigned int off_a, const ChStateDelta &a) override
 From global acceleration vector to item's state acceleration.
 
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.
 
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.
 
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 for a solution: From a vector R into the F 'force' term of the variables From a vector Qc into the Qb 'constraint' term of the constraints From a vector v into the q 'unknowns' term of the variables (for warm starting) From a vector L into the L 'lagrangian ' term of the constraints (for warm starting)
 
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: To a vector v from the q 'unknowns' term of the variables To a vector L from the L 'lagrangian ' term of the constraints.
 
virtual void VariablesFbReset () override
 Sets the 'fb' part of the encapsulated ChVariables to zero.
 
virtual void VariablesFbLoadForces (double factor=1) override
 Adds the current torques in the 'fb' part: qf+=torques*factor.
 
virtual void VariablesQbLoadSpeed () override
 Initialize the 'qb' part of the ChVariables with the current value of shaft speed. 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 shaft speed from the 'qb' part of the ChVariables (does not updates the full shaft state) and sets it as the current shaft speed. More...
 
virtual void VariablesQbIncrementPosition (double step) override
 Increment shaft position by the 'qb' part of the ChVariables, multiplied by a 'step' factor. 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)
 
void SetNoSpeedNoAcceleration () override
 Set no speed and no accelerations (but does not change the position)
 
void SetAppliedTorque (double mtorque)
 Set the torque applied to the shaft.
 
double GetAppliedTorque () const
 Get the torque applied to the shaft.
 
void SetPos (double mp)
 Set the angular position.
 
double GetPos () const
 Get the angular position.
 
void SetPos_dt (double mp)
 Set the angular velocity.
 
double GetPos_dt () const
 Get the angular velocity.
 
void SetPos_dtdt (double mp)
 Set the angular acceleration.
 
double GetPos_dtdt () const
 Get the angular acceleration.
 
void SetInertia (double newJ)
 Inertia of the shaft. More...
 
double GetInertia () const
 
void SetMaxSpeed (float m_max_speed)
 Trick. More...
 
float GetMaxSpeed () const
 
void ClampSpeed ()
 When this function is called, the speed of the shaft is clamped into limits posed by max_speed and max_wvel - but remember to put the shaft in the SetLimitSpeed(true) mode. More...
 
void SetSleepTime (float m_t)
 Set the amount of time which must pass before going automatically in sleep mode when the shaft has very small movements. More...
 
float GetSleepTime () const
 
void SetSleepMinSpeed (float m_t)
 Set the max linear speed to be kept for 'sleep_time' before freezing.
 
float GetSleepMinSpeed () const
 
void SetSleepMinWvel (float m_t)
 Set the max linear speed to be kept for 'sleep_time' before freezing.
 
float GetSleepMinWvel () const
 
virtual void Update (double mytime, bool update_assets=true) override
 Update all auxiliary data of the shaft at given time.
 
virtual void ArchiveOUT (ChArchiveOut &marchive) override
 Method to allow serialization of transient data to archives.
 
virtual void ArchiveIN (ChArchiveIn &marchive) override
 Method to allow deserialization of transient data from archives. More...
 
- Public Member Functions inherited from chrono::ChPhysicsItem
 ChPhysicsItem (const ChPhysicsItem &other)
 
ChSystemGetSystem () const
 Get the pointer to the parent ChSystem()
 
virtual void SetSystem (ChSystem *m_system)
 Set the pointer to the parent ChSystem() and also add to new collision system / remove from old coll.system.
 
void AddAsset (std::shared_ptr< ChAsset > masset)
 Add an optional asset (it can be used to define visualization shapes, es ChSphereShape, or textures, or custom attached properties that the user can define by creating his class inherited from ChAsset)
 
std::vector< std::shared_ptr
< ChAsset > > & 
GetAssets ()
 Access to the list of optional assets.
 
std::shared_ptr< ChAssetGetAssetN (unsigned int num)
 Access the Nth asset in the list of optional assets.
 
virtual 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 SyncCollisionModels ()
 If this physical item contains one or more collision models, sinchronize their coordinates and bounding boxes to the state of the item. More...
 
virtual void AddCollisionModelsToSystem ()
 If this physical item contains one or more collision models, add them to the system's collision engine. More...
 
virtual void RemoveCollisionModelsFromSystem ()
 If this physical item contains one or more collision models, remove them from the system's collision engine. More...
 
virtual void GetTotalAABB (ChVector<> &bbmin, ChVector<> &bbmax)
 Get the entire AABB axis-aligned bounding box of the object. More...
 
virtual void GetCenter (ChVector<> &mcenter)
 Get a symbolic 'center' of the object. More...
 
virtual void StreamINstate (ChStreamInBinary &mstream)
 Method to deserialize only the state (position, speed) Must be implemented by child classes. More...
 
virtual void StreamOUTstate (ChStreamOutBinary &mstream)
 Method to serialize only the state (position, speed) Must be implemented by child classes. More...
 
virtual void Setup ()
 This might recompute the number of coordinates, DOFs, constraints, in case this might change (ex in ChAssembly), as well as state offsets of contained items (ex in ChMesh)
 
virtual void Update (bool update_assets=true)
 As above, but does not require updating of time-dependent data. More...
 
virtual int GetDOF_w ()
 Get the number of scalar coordinates of variables derivatives (usually = DOF, but might be different than DOF, ex. More...
 
virtual int GetDOC ()
 Get the number of scalar constraints, if any, in this item.
 
virtual int GetDOC_c ()
 Get the number of scalar constraints, if any, in this item (only bilateral constr.) Children classes might override this. More...
 
virtual int GetDOC_d ()
 Get the number of scalar constraints, if any, in this item (only unilateral constr.) Children classes might override this. More...
 
unsigned int GetOffset_x ()
 Get offset in the state vector (position part)
 
unsigned int GetOffset_w ()
 Get offset in the state vector (speed part)
 
unsigned int GetOffset_L ()
 Get offset in the lagrangian multipliers.
 
void SetOffset_x (const unsigned int moff)
 Set offset in the state vector (position part) Note: only the ChSystem::Setup function should use this.
 
void SetOffset_w (const unsigned int moff)
 Set offset in the state vector (speed part) Note: only the ChSystem::Setup function should use this.
 
void SetOffset_L (const unsigned int moff)
 Set offset in the lagrangian multipliers Note: only the ChSystem::Setup function should use this.
 
virtual void IntStateGatherReactions (const unsigned int off_L, ChVectorDynamic<> &L)
 From item's reaction forces to global reaction vector. More...
 
virtual void IntStateScatterReactions (const unsigned int off_L, const ChVectorDynamic<> &L)
 From global reaction vector to item's reaction forces. More...
 
virtual void IntStateIncrement (const unsigned int off_x, ChState &x_new, const ChState &x, const unsigned int off_v, const ChStateDelta &Dv)
 Computes x_new = x + Dt , using vectors at specified offsets. More...
 
virtual void IntLoadResidual_CqL (const unsigned int off_L, ChVectorDynamic<> &R, const ChVectorDynamic<> &L, const double c)
 Takes the term Cq'*L, scale and adds to R at given offset: R += c*Cq'*L. More...
 
virtual void IntLoadConstraint_C (const unsigned int off, ChVectorDynamic<> &Qc, const double c, bool do_clamp, double recovery_clamp)
 Takes the term C, scale and adds to Qc at given offset: Qc += c*C. More...
 
virtual void IntLoadConstraint_Ct (const unsigned int off, ChVectorDynamic<> &Qc, const double c)
 Takes the term Ct, scale and adds to Qc at given offset: Qc += c*Ct. More...
 
virtual void InjectConstraints (ChSystemDescriptor &mdescriptor)
 Tell to a system descriptor that there are contraints of type ChConstraint in this object (for further passing it to a solver) Basically does nothing, but maybe that inherited classes may specialize this. More...
 
virtual void ConstraintsBiReset ()
 Sets to zero the known term (b_i) of encapsulated ChConstraints.
 
virtual void ConstraintsBiLoad_C (double factor=1, double recovery_clamp=0.1, bool do_clamp=false)
 Adds the current C (constraint violation) to the known term (b_i) of encapsulated ChConstraints.
 
virtual void ConstraintsBiLoad_Ct (double factor=1)
 Adds the current Ct (partial t-derivative, as in C_dt=0-> [Cq]*q_dt=-Ct) to the known term (b_i) of encapsulated ChConstraints.
 
virtual void ConstraintsBiLoad_Qc (double factor=1)
 Adds the current Qc (the vector of C_dtdt=0 -> [Cq]*q_dtdt=Qc ) to the known term (b_i) of encapsulated ChConstraints.
 
virtual void 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 ConstraintsLoadJacobians ()
 Adds the current jacobians in encapsulated ChConstraints.
 
virtual void ConstraintsFetch_react (double factor=1)
 Fetches the reactions from the lagrangian multiplier (l_i) of encapsulated ChConstraints. More...
 
virtual void InjectKRMmatrices (ChSystemDescriptor &mdescriptor)
 Tell to a system descriptor that there are items of type ChKblock in this object (for further passing it to a solver) Basically does nothing, but maybe that inherited classes may specialize this. More...
 
virtual void KRMmatricesLoad (double Kfactor, double Rfactor, double Mfactor)
 Adds the current stiffness K and damping R and mass M matrices in encapsulated ChKblock item(s), if any. More...
 
- Public Member Functions inherited from chrono::ChObj
 ChObj (const ChObj &other)
 
int GetIdentifier () const
 Gets the numerical identifier of the object.
 
void SetIdentifier (int id)
 Sets the numerical identifier of the object.
 
double GetChTime () const
 Gets the simulation time of this object.
 
void SetChTime (double m_time)
 Sets the simulation time of this object.
 
const char * GetName () const
 Gets the name of the object as C Ascii null-terminated string -for reading only!
 
void SetName (const char myname[])
 Sets the name of this object, as ascii string.
 
std::string GetNameString () const
 Gets the name of the object as C Ascii null-terminated string.
 
void SetNameString (const std::string &myname)
 Sets the name of this object, as std::string.
 
void MFlagsSetAllOFF (int &mflag)
 
void MFlagsSetAllON (int &mflag)
 
void MFlagSetON (int &mflag, int mask)
 
void MFlagSetOFF (int &mflag, int mask)
 
int MFlagGet (int &mflag, int mask)
 

Additional Inherited Members

- Protected Attributes inherited from chrono::ChPhysicsItem
ChSystemsystem
 parent system
 
std::vector< std::shared_ptr
< ChAsset > > 
assets
 set of assets
 
unsigned int offset_x
 offset in vector of state (position part)
 
unsigned int offset_w
 offset in vector of state (speed part)
 
unsigned int offset_L
 offset in vector of lagrangian multipliers
 
- Protected Attributes inherited from chrono::ChObj
double ChTime
 the time of simulation for the object
 

Member Function Documentation

void chrono::ChShaft::ArchiveIN ( ChArchiveIn marchive)
overridevirtual

Method to allow deserialization of transient data from archives.

Method to allow de serialization of transient data from archives.

Reimplemented from chrono::ChPhysicsItem.

void chrono::ChShaft::ClampSpeed ( )

When this function is called, the speed of the shaft is clamped into limits posed by max_speed and max_wvel - but remember to put the shaft in the SetLimitSpeed(true) mode.

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.

Reimplemented from chrono::ChPhysicsItem.

void chrono::ChShaft::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.

Reimplemented from chrono::ChPhysicsItem.

bool chrono::ChShaft::IsActive ( ) const

Tell if the body is active, i.e.

it is neither fixed to ground nor it is in sleep mode.

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

Inertia of the shaft.

Must be positive. Try not to mix bodies with too high/too low values of mass, for numerical stability.

void chrono::ChShaft::SetLimitSpeed ( bool  mlimit)

Trick.

Set the maximum shaft velocity (beyond this limit it will be clamped). This is useful in virtual reality and real-time simulations. The realism is limited, but the simulation is more stable.

void chrono::ChShaft::SetMaxSpeed ( float  m_max_speed)

Trick.

Set the maximum velocity (beyond this limit it will be clamped). This is useful in virtual reality and real-time simulations, to increase robustness at the cost of realism. This limit is active only if you set SetLimitSpeed(true);

void chrono::ChShaft::SetShaftFixed ( bool  mev)

Sets the 'fixed' state of the shaft.

If true, it does not rotate despite constraints, forces, etc.

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

Force the shaft in sleeping mode or not (usually this state change is not handled by users, anyway, because it is mostly automatic).

void chrono::ChShaft::SetSleepTime ( float  m_t)

Set the amount of time which must pass before going automatically in sleep mode when the shaft has very small movements.

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

Trick.

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.

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.

void chrono::ChShaft::VariablesQbIncrementPosition ( double  step)
overridevirtual

Increment shaft position by the 'qb' part of the ChVariables, multiplied by a 'step' factor.

pos+=qb*step

Reimplemented from chrono::ChPhysicsItem.

void chrono::ChShaft::VariablesQbLoadSpeed ( )
overridevirtual

Initialize the 'qb' part of the ChVariables with the current value of shaft speed.

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

Reimplemented from chrono::ChPhysicsItem.

void chrono::ChShaft::VariablesQbSetSpeed ( double  step = 0)
overridevirtual

Fetches the shaft speed from the 'qb' part of the ChVariables (does not updates the full shaft state) and sets it as the current shaft speed.

If 'step' is not 0, also computes the approximate acceleration of the shaft using backward differences, that is accel=(new_speed-old_speed)/step.

Reimplemented from chrono::ChPhysicsItem.