Description
Class for defining a planetary gear between three one-degree-of-freedom parts; i.e., shafts that can be used to build 1D models of powertrains; this is more efficient than simulating power trains modeled full 3D ChBody objects).
Planetary gears can be used to make, for instance, the differentials of cars. While traditional gear reducers have one input and one output, the planetary gear have two inputs and one output (or, if you prefer, one input and two outputs). Note that you can use this class also to make a gearbox if you are interested in knowing the reaction torque transmitted to the truss (whereas the basic ChLinkGear cannot do this because it has only in and out); in this case you just use the shaft n.1 as truss and fix it.
#include <ChShaftsPlanetary.h>
Public Member Functions | |
ChShaftsPlanetary (const ChShaftsPlanetary &other) | |
virtual ChShaftsPlanetary * | Clone () const override |
"Virtual" copy constructor (covariant return type). | |
virtual int | GetNumCoords () const |
Get the number of scalar variables affected by constraints in this link. | |
virtual int | GetDOC_c () override |
Number of scalar constraints. | |
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 | 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. 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 | 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 | 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 | 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... | |
bool | Initialize (std::shared_ptr< ChShaft > mshaft1, std::shared_ptr< ChShaft > mshaft2, std::shared_ptr< ChShaft > mshaft3) |
Use this function after planetary gear creation, to initialize it, given three shafts to join. More... | |
ChShaft * | GetShaft1 () |
Get the first shaft (carrier wheel) | |
ChShaft * | GetShaft2 () |
Get the second shaft. | |
ChShaft * | GetShaft3 () |
Get the third shaft. | |
double | GetSpeedShaft1 () const |
Return the speed of the first shaft (carrier wheel). | |
double | GetSpeedShaft2 () const |
Return the speed of the second shaft. | |
double | GetSpeedShaft3 () const |
Return the speed of the third shaft. | |
void | SetTransmissionRatios (double mr1, double mr2, double mr3) |
Set the transmission ratios r1 r2 r3 as in r1*w1 + r2*w2 + r3*w3 = 0 For example, for the car differential, if you assume that shaft 1 is the carrier and shafts 2 and 3 go to the wheel hubs, you must use r1=-2, r2=1, r3=1 to satisfy the kinematics -2*w1+w2+w3=0 of the differential; equivalently, you may use r1=1, r2=-0.5, r3=-0.5 (the equation would hold the same). | |
void | SetTransmissionRatioOrdinary (double t0) |
Setting the transmission ratios r1 r2 r3 for r1*w1 + r2*w2 + r3*w3 = 0 may be cumbersome, but when you deal with typical planetary devices, this function provides a shortcut to setting them for you, given a single parameter t0, that is the speed ratio t'=w3'/w2' of the inverted planetary. More... | |
double | GetTransmissionRatioOrdinary () const |
Get the t0 transmission ratio of the equivalent ordinary gearbox, ie. More... | |
double | GetTransmissionR1 () const |
Get the transmission ratio r1, as in r1*w1+r2*w2+r3*w3 = 0. | |
double | GetTransmissionR2 () const |
Get the transmission ratio r1, as in r1*w1+r2*w2+r3*w3 = 0. | |
double | GetTransmissionR3 () const |
Get the transmission ratio r1, as in r1*w1+r2*w2+r3*w3 = 0. | |
void | SetAvoidPhaseDrift (bool mb) |
Set if the constraint must avoid phase drift. More... | |
bool | GetAvoidPhaseDrift () |
Set if the constraint is in "avoid phase drift" mode. | |
double | GetTorqueReactionOn1 () const |
Get the reaction torque considered as applied to the 1st axis. | |
double | GetTorqueReactionOn2 () const |
Get the reaction torque considered as applied to the 2nd axis. | |
double | GetTorqueReactionOn3 () const |
Get the reaction torque considered as applied to the 3rd axis. | |
virtual void | Update (double mytime, bool update_assets=true) override |
Update all auxiliary data of the gear transmission 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) | |
ChSystem * | GetSystem () 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< 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 | SyncCollisionModels () |
If this physical item contains one or more collision models, synchronize their coordinates and bounding boxes to the state of the item. | |
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. | |
virtual void | Setup () |
This might recompute the number of coordinates, DOFs, constraints, in case this might change (ex in ChAssembly), as well as state offsets of contained items (ex in ChMesh) | |
virtual void | Update (bool update_assets=true) |
As above, but does not require updating of time-dependent data. More... | |
virtual void | SetNoSpeedNoAcceleration () |
Set zero speed (and zero accelerations) in state, without changing the position. More... | |
virtual int | GetDOF () |
Get the number of scalar coordinates (variables), if any, in this item. 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_d () |
Get the number of scalar constraints, if any, in this item (only unilateral constr.) Children classes might override this. | |
unsigned int | GetOffset_x () |
Get offset in the state vector (position part) | |
unsigned int | GetOffset_w () |
Get offset in the state vector (speed part) | |
unsigned int | GetOffset_L () |
Get offset in the lagrangian multipliers. | |
void | SetOffset_x (const unsigned int moff) |
Set offset in the state vector (position part) Note: only the ChSystem::Setup function should use this. | |
void | SetOffset_w (const unsigned int moff) |
Set offset in the state vector (speed part) Note: only the ChSystem::Setup function should use this. | |
void | SetOffset_L (const unsigned int moff) |
Set offset in the lagrangian multipliers Note: only the ChSystem::Setup function should use this. | |
virtual void | IntStateGather (const unsigned int off_x, ChState &x, const unsigned int off_v, ChStateDelta &v, double &T) |
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) |
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) |
From item's state acceleration to global acceleration vector. More... | |
virtual void | IntStateScatterAcceleration (const unsigned int off_a, const ChStateDelta &a) |
From global acceleration vector to item's state acceleration. 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_F (const unsigned int off, ChVectorDynamic<> &R, const double c) |
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) |
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 | 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 | VariablesFbReset () |
Sets the 'fb' part (the known term) of the encapsulated ChVariables to zero. | |
virtual void | VariablesFbLoadForces (double factor=1) |
Adds the current forces (applied to item) into the encapsulated ChVariables, in the 'fb' part: qf+=forces*factor. | |
virtual void | VariablesQbLoadSpeed () |
Initialize the 'qb' part of the ChVariables with the current value of speeds. More... | |
virtual void | VariablesFbIncrementMq () |
Adds M*q (masses multiplied current 'qb') to Fb, ex. More... | |
virtual void | VariablesQbSetSpeed (double step=0) |
Fetches the item speed (ex. More... | |
virtual void | VariablesQbIncrementPosition (double step) |
Increment item positions by the 'qb' part of the ChVariables, multiplied by a 'step' factor. More... | |
virtual void | InjectVariables (ChSystemDescriptor &mdescriptor) |
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 | 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 | 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. | |
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) |
virtual std::string & | ArchiveContainerName () |
Additional Inherited Members | |
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 | |
Member Function Documentation
◆ ArchiveIN()
|
overridevirtual |
Method to allow deserialization of transient data from archives.
Method to allow de serialization of transient data from archives.
Reimplemented from chrono::ChPhysicsItem.
◆ ConstraintsFetch_react()
|
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::ChPhysicsItem.
◆ GetTransmissionRatioOrdinary()
|
inline |
Get the t0 transmission ratio of the equivalent ordinary gearbox, ie.
the inverted planetary, that is the ratio t0=w3'/w2' assuming that the carrier (shaft 1) is hold fixed.
◆ Initialize()
bool chrono::ChShaftsPlanetary::Initialize | ( | std::shared_ptr< ChShaft > | mshaft1, |
std::shared_ptr< ChShaft > | mshaft2, | ||
std::shared_ptr< ChShaft > | mshaft3 | ||
) |
Use this function after planetary gear creation, to initialize it, given three shafts to join.
Although there's no special requirement, you may think of the three typical moving parts of an epicycloidal reducer: the carrier, the input gear, and the gear with inner teeth that usually is kept fixed (but the ChShaftsPlanetary does not require that one shaft is fixed - it's up to you) Each shaft must belong to the same ChSystem.
- Parameters
-
mshaft1 first shaft to join (carrier wheel) mshaft2 second shaft to join (wheel) mshaft3 third shaft to join (wheel)
◆ IntFromDescriptor()
|
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::ChPhysicsItem.
◆ IntLoadConstraint_C()
|
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::ChPhysicsItem.
◆ IntLoadResidual_CqL()
|
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 += c*Cq'*L L the L vector c a scaling factor
Reimplemented from chrono::ChPhysicsItem.
◆ IntStateGatherReactions()
|
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::ChPhysicsItem.
◆ IntStateScatterReactions()
|
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::ChPhysicsItem.
◆ IntToDescriptor()
|
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::ChPhysicsItem.
◆ SetAvoidPhaseDrift()
|
inline |
Set if the constraint must avoid phase drift.
If true, phasing is always tracked and the constraint is satisfied also at the position level. If false, microslipping can accumulate (as in friction wheels). Default is enabled.
◆ SetTransmissionRatioOrdinary()
|
inline |
Setting the transmission ratios r1 r2 r3 for r1*w1 + r2*w2 + r3*w3 = 0 may be cumbersome, but when you deal with typical planetary devices, this function provides a shortcut to setting them for you, given a single parameter t0, that is the speed ratio t'=w3'/w2' of the inverted planetary.
That ratio is simple to get: to invert the planetary, imagine to hold fixed the carrier of shaft 1 (that is w1' =0), move the shaft 2 and see which is the speed of shaft 3, to get the ratio t0=w3'/w2'. Generally, shaft 1 is called the 'carrier'. For example, in normal operation of an epicycloidal reducer, the carrier (shaft 1) is used as output, shaft 2 is the input, and shaft 3 is hold fixed to get one degree of freedom only; but in 'inverted' operation imagine the carrier is fixed, so t0 can be easily got as t0=-z2/z3, with z=n.of teeth. In a car differential, again with shaft 1 as carrier, one can see that t0=w3'/w2' so t0=-1. See the Willis theory for more details on these formulas. Note that t0 should be different from 1 (singularity). Once you get t0, simply use this function and it will set r1 r2 r3 automatically.
The documentation for this class was generated from the following files:
- /builds/uwsbel/chrono/src/chrono/physics/ChShaftsPlanetary.h
- /builds/uwsbel/chrono/src/chrono/physics/ChShaftsPlanetary.cpp