## Description

A motor that enforces the rotation angle r(t) between two frames on two bodies, using a rheonomic constraint.

The r(t) angle of frame A rotating on Z axis of frame B, is imposed via an exact function of time f(t), and an optional angle offset: r(t) = f(t) + offset Note: no compliance is allowed, so if the actuator hits an undeformable obstacle it hits a pathological situation and the solver result can be unstable/unpredictable. Think at it as a servo drive with "infinitely stiff" control. This type of motor is very easy to use, stable and efficient, and should be used if the 'infinitely stiff' control assumption is a good approximation of what you simulate (e.g., very good and reactive controllers). By default it is initialized with linear ramp: df/dt= 1. Use SetAngleFunction() to change to other motion functions.

#include <ChLinkMotorRotationAngle.h>

## Public Member Functions

"Virtual" copy constructor (covariant return type).

void SetAngleFunction (const std::shared_ptr< ChFunction > function)
Set the rotation angle function of time a(t). More...

std::shared_ptr< ChFunctionGetAngleFunction () const
Get the rotation angle function f(t).

void SetAngleOffset (double mo)
Get initial angle offset for f(t)=0, in [rad]. More...

double GetAngleOffset ()
Get initial offset for f(t)=0, in [rad].

virtual double GetMotorTorque () const override
Get the current actuator reaction torque [Nm].

void Update (double mytime, bool update_assets) override

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 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 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 ()

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, synchronize their coordinates and bounding boxes to the state of the item.

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 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...

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 VariablesFbReset ()
Sets the 'fb' part (the known term) of the encapsulated ChVariables to zero.

Adds the current forces (applied to item) into the encapsulated ChVariables, in the 'fb' part: qf+=forces*factor.

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.

Adds the current Qc (the vector of C_dtdt=0 -> [Cq]*q_dtdt=Qc ) to the known term (b_i) of encapsulated ChConstraints.

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 ()

Type of guide constraint.
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

## ◆ ArchiveIN()

 void chrono::ChLinkMotorRotationAngle::ArchiveIN ( ChArchiveIn & marchive )
overridevirtual

Method to allow deserialization of transient data from archives.

Method to allow de serialization of transient data from archives.

 void chrono::ChLinkMotorRotationAngle::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

## ◆ SetAngleFunction()

 void chrono::ChLinkMotorRotationAngle::SetAngleFunction ( const std::shared_ptr< ChFunction > function )
inline

Set the rotation angle function of time a(t).

This function should be C0 continuous and, to prevent acceleration spikes, it should ideally be C1 continuous.

## ◆ SetAngleOffset()

 void chrono::ChLinkMotorRotationAngle::SetAngleOffset ( double mo )
inline

Get initial angle offset for f(t)=0, in [rad].

Rotation on Z of the two axes will be r(t) = f(t) + offset. By default, offset = 0

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