Description

Class for links representing engines between two rigid bodies.

Note that the engine can be in 'impose relative rotation' mode, as well as in 'impose speed' etc. It can also be used to represent an engine with a torque/speed custom curve. etc.

#include <ChLinkEngine.h>

Inheritance diagram for chrono::ChLinkEngine:
Collaboration diagram for chrono::ChLinkEngine:

Public Types

enum  eCh_eng_mode {
  ENG_MODE_ROTATION = 0, ENG_MODE_SPEED, ENG_MODE_TORQUE, ENG_MODE_KEY_ROTATION,
  ENG_MODE_KEY_POLAR, ENG_MODE_TO_POWERTRAIN_SHAFT
}
 
enum  eCh_shaft_mode {
  ENG_SHAFT_LOCK = 0, ENG_SHAFT_PRISM, ENG_SHAFT_OLDHAM, ENG_SHAFT_UNIVERSAL,
  ENG_SHAFT_CARDANO
}
 

Public Member Functions

 ChLinkEngine (const ChLinkEngine &other)
 
virtual ChLinkEngineClone () const override
 "Virtual" copy constructor (covariant return type).
 
virtual void UpdateTime (double mytime) override
 Updates motion laws, etc. for the impose rotation / impose speed modes.
 
virtual void UpdateForces (double mytime) override
 Updates torque for the impose torque mode.
 
virtual void UpdatedExternalTime (double prevtime, double time) override
 Updates the r3d time, so perform differentiation for computing speed in case of keyframed motion.
 
virtual void SetUpMarkers (ChMarker *mark1, ChMarker *mark2) override
 Sets up the markers associated with the engine link.
 
std::shared_ptr< ChFunctionGet_rot_funct () const
 
std::shared_ptr< ChFunctionGet_spe_funct () const
 
std::shared_ptr< ChFunctionGet_tor_funct () const
 
std::shared_ptr< ChFunctionGet_torque_w_funct () const
 
void Set_rot_funct (std::shared_ptr< ChFunction > mf)
 
void Set_spe_funct (std::shared_ptr< ChFunction > mf)
 
void Set_tor_funct (std::shared_ptr< ChFunction > mf)
 
void Set_torque_w_funct (std::shared_ptr< ChFunction > mf)
 
std::shared_ptr< ChFunctionGet_rot_funct_x () const
 
std::shared_ptr< ChFunctionGet_rot_funct_y () const
 
const QuaternionGetKeyedPolarRotation () const
 
void Set_rot_funct_x (std::shared_ptr< ChFunction > mf)
 
void Set_rot_funct_y (std::shared_ptr< ChFunction > mf)
 
void SetKeyedPolarRotation (const Quaternion &mq)
 
bool Get_learn () const
 
bool Get_impose_reducer () const
 
void Set_learn (bool mset)
 
void Set_impose_reducer (bool mset)
 
eCh_eng_mode Get_eng_mode () const
 
void Set_eng_mode (eCh_eng_mode mset)
 
eCh_shaft_mode Get_shaft_mode () const
 
void Set_shaft_mode (eCh_shaft_mode mset)
 
double Get_mot_rot () const
 
double Get_mot_rot_dt () const
 
double Get_mot_rot_dtdt () const
 
double Get_mot_torque () const
 
double Get_mot_rerot () const
 
double Get_mot_rerot_dt () const
 
double Get_mot_rerot_dtdt () const
 
double Get_mot_retorque () const
 
double Get_mot_tau () const
 
double Get_mot_eta () const
 
double Get_mot_inertia () const
 
void Set_mot_tau (double mtau)
 
void Set_mot_eta (double meta)
 
void Set_mot_inertia (double min)
 
std::shared_ptr< ChShaftGetInnerShaft1 () const
 
std::shared_ptr< ChShaftGetInnerShaft2 () const
 
double GetInnerTorque1 () const
 
double GetInnerTorque2 () const
 
virtual int GetDOF () override
 Get the number of scalar coordinates (variables), if any, in this item. More...
 
virtual int GetDOC_c () override
 Get the number of scalar constraints, if any, in this item (only bilateral constr.) Children classes might override this. 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.
 
virtual void IntStateScatterAcceleration (const unsigned int off_a, const ChStateDelta &a) override
 From global acceleration vector to item's state acceleration.
 
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 IntStateGatherReactions (const unsigned int off_L, ChVectorDynamic<> &L) override
 Specialize the following respect to ChLinkMasked base because there might be some active ChLinkLimit.
 
virtual void IntStateScatterReactions (const unsigned int off_L, const ChVectorDynamic<> &L) override
 Specialize the following respect to ChLinkMasked base ,in order to update intuitive react_torque and react_force.
 
virtual void IntLoadResidual_F (const unsigned int off, ChVectorDynamic<> &R, const double c) override
 Adds force to residual R, as R*= F*c NOTE: here the off ofset in R is NOT used because add F at the TWO offsets of the two connected bodies, so it is assumed that offsets for Body1 and Body2 variables have been already set properly!
 
virtual void 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 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 += c*Cq'*L.
 
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.
 
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.
 
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 InjectConstraints (ChSystemDescriptor &mdescriptor) override
 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 () 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 ConstraintsLoadJacobians () override
 Adds the current jacobians in encapsulated ChConstraints.
 
virtual void ConstraintsFetch_react (double factor=1) override
 Fetches the reactions from the lagrangian multiplier (l_i) of encapsulated ChConstraints. 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. 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 ArchiveOUT (ChArchiveOut &marchive) override
 Method to allow serialization of transient data to archives.
 
virtual void ArchiveIN (ChArchiveIn &marchive) override
 Method to allow deserialization of transient data from archives. More...
 
- Public Member Functions inherited from chrono::ChPhysicsItem
 ChPhysicsItem (const ChPhysicsItem &other)
 
ChSystemGetSystem () const
 Get the pointer to the parent ChSystem()
 
virtual void SetSystem (ChSystem *m_system)
 Set the pointer to the parent ChSystem() and also add to new collision system / remove from old coll.system.
 
void AddAsset (std::shared_ptr< ChAsset > masset)
 Add an optional asset (it can be used to define visualization shapes, es ChSphereShape, or textures, or custom attached properties that the user can define by creating his class inherited from ChAsset)
 
std::vector< std::shared_ptr
< ChAsset > > & 
GetAssets ()
 Access to the list of optional assets.
 
std::shared_ptr< ChAssetGetAssetN (unsigned int num)
 Access the Nth asset in the list of optional assets.
 
virtual unsigned int GetAssetsFrameNclones ()
 Optionally, a ChPhysicsItem can return multiple asset coordinate systems; this can be helpful if, for example, when a ChPhysicsItem contains 'clones' with the same assets (ex. More...
 
virtual bool GetCollide () const
 Tell if the object is subject to collision. More...
 
virtual void SyncCollisionModels ()
 If this physical item contains one or more collision models, sinchronize their coordinates and bounding boxes to the state of the item. More...
 
virtual void AddCollisionModelsToSystem ()
 If this physical item contains one or more collision models, add them to the system's collision engine. More...
 
virtual void RemoveCollisionModelsFromSystem ()
 If this physical item contains one or more collision models, remove them from the system's collision engine. More...
 
virtual void GetTotalAABB (ChVector<> &bbmin, ChVector<> &bbmax)
 Get the entire AABB axis-aligned bounding box of the object. More...
 
virtual void GetCenter (ChVector<> &mcenter)
 Get a symbolic 'center' of the object. More...
 
virtual void StreamINstate (ChStreamInBinary &mstream)
 Method to deserialize only the state (position, speed) Must be implemented by child classes. More...
 
virtual void StreamOUTstate (ChStreamOutBinary &mstream)
 Method to serialize only the state (position, speed) Must be implemented by child classes. More...
 
virtual void Setup ()
 This might recompute the number of coordinates, DOFs, constraints, in case this might change (ex in ChAssembly), as well as state offsets of contained items (ex in ChMesh)
 
virtual void SetNoSpeedNoAcceleration ()
 Set zero speed (and zero accelerations) in state, without changing the position. More...
 
virtual int GetDOF_w ()
 Get the number of scalar coordinates of variables derivatives (usually = DOF, but might be different than DOF, ex. 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 InjectKRMmatrices (ChSystemDescriptor &mdescriptor)
 Tell to a system descriptor that there are items of type ChKblock in this object (for further passing it to a solver) Basically does nothing, but maybe that inherited classes may specialize this. More...
 
virtual void KRMmatricesLoad (double Kfactor, double Rfactor, double Mfactor)
 Adds the current stiffness K and damping R and mass M matrices in encapsulated ChKblock item(s), if any. More...
 
- Public Member Functions inherited from chrono::ChObj
 ChObj (const ChObj &other)
 
int GetIdentifier () const
 Gets the numerical identifier of the object.
 
void SetIdentifier (int id)
 Sets the numerical identifier of the object.
 
double GetChTime () const
 Gets the simulation time of this object.
 
void SetChTime (double m_time)
 Sets the simulation time of this object.
 
const char * GetName () const
 Gets the name of the object as C Ascii null-terminated string -for reading only!
 
void SetName (const char myname[])
 Sets the name of this object, as ascii string.
 
std::string GetNameString () const
 Gets the name of the object as C Ascii null-terminated string.
 
void SetNameString (const std::string &myname)
 Sets the name of this object, as std::string.
 
void MFlagsSetAllOFF (int &mflag)
 
void MFlagsSetAllON (int &mflag)
 
void MFlagSetON (int &mflag, int mask)
 
void MFlagSetOFF (int &mflag, int mask)
 
int MFlagGet (int &mflag, int mask)
 

Protected Attributes

std::shared_ptr< ChFunctionrot_funct
 rotation(t) function
 
std::shared_ptr< ChFunctionspe_funct
 speed(t) function
 
std::shared_ptr< ChFunctiontor_funct
 torque(t) function
 
std::shared_ptr< ChFunctiontorque_w
 torque(w) function
 
bool learn
 if true, the actuator does not apply constraint, just records the motion into its rot_function.
 
bool impose_reducer
 if true, speed torque or rotation are imposed to the fast (motor) shaft, before reducer!
 
double mot_rot
 current rotation (read only)
 
double mot_rot_dt
 current ang speed (read only)
 
double mot_rot_dtdt
 current ang acc (read only)
 
double mot_torque
 current motor torque (read only)
 
double mot_rerot
 current rotation (read only) before reducer
 
double mot_rerot_dt
 current ang speed (read only) before reducer
 
double mot_rerot_dtdt
 current ang acc (read only) before reducer
 
double mot_retorque
 current motor torque (read only) before reducer
 
double mot_tau
 motor: transmission ratio
 
double mot_eta
 motor: transmission efficiency
 
double mot_inertia
 motor: inertia (added to system)
 
eCh_eng_mode eng_mode
 mode of controlling the motor (by rotation, speed etc.)
 
eCh_shaft_mode shaft_mode
 mode of imposing constraints on extra (non-z) degrees of freedom
 
std::shared_ptr< ChFunctionrot_funct_x
 rotation(t) function for keyframe polar motor
 
std::shared_ptr< ChFunctionrot_funct_y
 rotation(t) function for keyframe polar motor
 
double last_r3time
 internal:for backward differentiation to compute speed in keyframe mode
 
double last_r3mot_rot
 internal:for backward differentiation to compute speed in keyframe mode
 
double last_r3mot_rot_dt
 internal:for backward differentiation to compute speed in keyframe mode
 
Quaternion last_r3relm_rot
 internal:for backward differentiation to compute speed in keyframe mode
 
Quaternion last_r3relm_rot_dt
 internal
 
Quaternion keyed_polar_rotation
 internal
 
std::shared_ptr< ChShaftinnershaft1
 used in ENG_MODE_TO_POWERTRAIN_SHAFT
 
std::shared_ptr< ChShaftinnershaft2
 used in ENG_MODE_TO_POWERTRAIN_SHAFT
 
std::shared_ptr< ChShaftsBodyinnerconstraint1
 used in ENG_MODE_TO_POWERTRAIN_SHAFT
 
std::shared_ptr< ChShaftsBodyinnerconstraint2
 used in ENG_MODE_TO_POWERTRAIN_SHAFT
 
double torque_react1
 
double torque_react2
 
- 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
 

Additional Inherited Members

 Type of link-lock.

Member Enumeration Documentation

Enumerator
ENG_SHAFT_LOCK 

shafts of motor and user (markers 1 and 2) are stiffly joined

ENG_SHAFT_PRISM 

shafts of motor and user (markers 1 and 2) can shift along shaft (Z axis)

ENG_SHAFT_OLDHAM 

shafts of motor and user (markers 1 and 2) may be parallel shifting on X and Y

ENG_SHAFT_UNIVERSAL 

not yet used

ENG_SHAFT_CARDANO 

not yet used

Member Function Documentation

void chrono::ChLinkEngine::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::ChLinkLock.

void chrono::ChLinkEngine::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::ChLinkLock.

int chrono::ChLinkEngine::GetDOC_c ( )
overridevirtual

Get the number of scalar constraints, if any, in this item (only bilateral constr.) Children classes might override this.

Reimplemented from chrono::ChLinkMasked.

int chrono::ChLinkEngine::GetDOF ( )
overridevirtual

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

Children classes must override this.

Reimplemented from chrono::ChPhysicsItem.

void chrono::ChLinkEngine::InjectConstraints ( ChSystemDescriptor mdescriptor)
overridevirtual

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.

Reimplemented from chrono::ChLinkLock.

void chrono::ChLinkEngine::InjectVariables ( ChSystemDescriptor mdescriptor)
overridevirtual

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.

Reimplemented from chrono::ChPhysicsItem.

void chrono::ChLinkEngine::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::ChLinkEngine::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.

Reimplemented from chrono::ChPhysicsItem.

void chrono::ChLinkEngine::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.

void chrono::ChLinkEngine::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::ChLinkEngine::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::ChPhysicsItem.

void chrono::ChLinkEngine::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.

void chrono::ChLinkEngine::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.