Class LagrangianDS

Defined in Program listing for file kernel/src/modelingTools/LagrangianDS.hpp

class LagrangianDS : public SecondOrderDS

Lagrangian non linear dynamical systems - \(M(q,z) \dot v = F(v, q, t, z) + p \).

This class defines and computes a generic ndof-dimensional Lagrangian Non Linear Dynamical System of the form :

\[\begin{split}M(q,z) \dot v + F_{gyr}(v, q, z) + F_{int}(v , q , t, z) = F_{ext}(t, z) + p \\ \dot q = v\end{split}\]

where

  • \(q \in R^{ndof} \) is the set of the generalized coordinates,

  • \( \dot q =v \in R^{ndof} \) the velocity, i. e. the time derivative of the generalized coordinates (Lagrangian systems).

  • \( \ddot q =\dot v \in R^{ndof} \) the acceleration, i. e. the second time derivative of the generalized coordinates.

  • \( p \in R^{ndof} \) the reaction forces due to the Non Smooth Interaction.

  • \( M(q) \in R^{ndof \times ndof} \) is the inertia term (access : mass() method).

  • \( F_{gyr}(\dot q, q) \in R^{ndof}\) is the non linear inertia term (access fGyr() method).

  • \( F_{int}(\dot q , q , t) \in R^{ndof} \) are the internal forces (access fInt() method).

  • \( F_{ext}(t) \in R^{ndof} \) are the external forces (access fExt() method).

  • \( z \in R^{zSize}\) is a vector of arbitrary algebraic variables, some sort of discrete state.

The equation of motion is also shortly denoted as \( M(q,z) \dot v = F(v, q, t, z) + p\)

where \(F(v, q, t, z) \in R^{ndof} \) collects the total forces acting on the system, that is \( F(v, q, t, z) = F_{ext}(t, z) - F_{gyr}(v, q, z) + F_{int}(v, q , t, z) \).

This vector is saved and may be accessed using forces() method.

q[i] is the derivative number i of q. Thus: q[0]= \( q \), global coordinates, q[1]= \( \dot q\), velocity, q[2]= \( \ddot q \), acceleration.

The following operators (and their jacobians) can be plugged, in the usual way (see User Guide, ‘User-defined plugins’)

If required (e.g. for Event-Driven like simulation), formulation as a first-order system is also available, and writes:

  • \( n= 2 ndof \)

  • \( x = \left[\begin{array}{c}q \\ \dot q\end{array}\right]\)

  • rhs given by:

\[\begin{split}\dot x = \left[\begin{array}{c} \dot q\\ \ddot q = M^{-1}(q)\left[F(v, q , t, z) + p \right]\\ \end{array}\right]\end{split}\]

  • jacobian of the rhs, with respect to x

\[\begin{split}\nabla_{x}rhs(x,t) = \left[\begin{array}{cc} 0 & I \\ \nabla_{q}(M^{-1}(q)F(v, q , t, z)) & \nabla_{\dot q}(M^{-1}(q)F(v, q , t, z)) \\ \end{array}\right]\end{split}\]

with the input due to the non smooth law:

\[\begin{split}\left[\begin{array}{c} 0 \\ p \end{array}\right]\end{split}\]

In that case, use the following methods:

Subclassed by LagrangianLinearDiagonalDS, LagrangianLinearTIDS

Right-hand side computation

void resetToInitialState()

reset the state to the initial state

void initRhs(double time)

allocate (if needed) and compute rhs and its jacobian.

Parameters
  • time: of initialization

void initializeNonSmoothInput(unsigned int level)

set nonsmooth input to zero

Parameters
  • level: input-level to be initialized.

virtual void computeRhs(double time)

update right-hand side for the current state

Parameters
  • time: of interest

virtual void computeJacobianRhsx(double time)

update \(\nabla_x rhs\) for the current state

Parameters
  • time: of interest

void resetAllNonSmoothParts()

reset non-smooth part of the rhs (i.e.

p), for all ‘levels’

void resetNonSmoothPart(unsigned int level)

set nonsmooth part of the rhs (i.e.

p) to zero for a given level

Parameters
  • level:

void setRhs(const SiconosVector &newValue)

set the value of the right-hand side, \( \dot x \)

Parameters

void setRhsPtr(SP::SiconosVector newPtr)

set right-hand side, \( \dot x \) (pointer link)

Parameters
  • newPtr: SP::SiconosVector

virtual void computeForces(double time, SP::SiconosVector q, SP::SiconosVector velocity)

function to compute \(F(v,q,t,z)\) for the current state

Parameters
  • time: the current timeCompute \(F(v,q,t,z)\)

  • time: the current time

  • q: SP::SiconosVector: pointers on q

  • velocity: SP::SiconosVector: pointers on velocity

virtual void computeJacobianqForces(double time)

Compute \(\nabla_qF(v,q,t,z)\) for current \(q,v\) Default function to compute forces.

Parameters
  • time: the current time

virtual void computeJacobianqDotForces(double time)

Compute \(\nabla_{\dot q}F(v,q,t,z)\) for current \(q,v\).

Parameters
  • time: the current time

virtual void computeJacobianvForces(double time)

Compute \(\nabla_{\dot q}F(v,q,t,z)\) for current \(q,v\).

Parameters
  • time: the current time

Attributes access

SP::SiconosVector q() const

generalized coordinates of the system (vector of size dimension())

Return

pointer on a SiconosVector

void setQ(const SiconosVector &newValue)

set value of generalized coordinates vector (copy)

Parameters
  • newValue:

void setQPtr(SP::SiconosVector newPtr)

set value of generalized coordinates vector (pointer link)

Parameters
  • newPtr:

void setQ0(const SiconosVector &newValue)

set initial state (copy)

Parameters
  • newValue:

void setQ0Ptr(SP::SiconosVector newPtr)

set initial state (pointer link)

Parameters
  • newPtr:

SP::SiconosVector velocity() const

get velocity vector (pointer link)

Return

pointer on a SiconosVector

void setVelocity(const SiconosVector &newValue)

set velocity vector (copy)

Parameters
  • newValue:

void setVelocityPtr(SP::SiconosVector newPtr)

set velocity vector (pointer link)

Parameters
  • newPtr:

SP::SiconosVector velocity0() const

get initial velocity (pointer)

Return

pointer on a SiconosVector

void setVelocity0(const SiconosVector &newValue)

set initial velocity (copy)

Parameters
  • newValue:

void setVelocity0Ptr(SP::SiconosVector newPtr)

set initial velocity (pointer link)

Parameters
  • newPtr:

SP::SiconosVector acceleration() const

get acceleration (pointer link)

Return

pointer on a SiconosVector

SP::SiconosVector fInt() const

get $F_{int}$ (pointer link)

Return

pointer on a plugged vector

void setFIntPtr(SP::SiconosVector newPtr)

set $F_{int}$ (pointer link)

Parameters
  • newPtr: a SP to plugged vector

SP::SiconosVector fExt() const

get \(F_{ext}\), (pointer link)

Return

pointer on a plugged vector

void setFExtPtr(SP::SiconosVector newPtr)

set \(F_{ext}\), (pointer link)

Parameters
  • newPtr: a SP to a Simple vector

SP::SiconosVector fGyr() const

get \(F_{gyr}\), (pointer link)

Return

pointer on a plugged vector

void setFGyrPtr(SP::SiconosVector newPtr)

set \(F_{gyr}\), (pointer link)

Parameters
  • newPtr: a SP to plugged vector

SP::SiconosMatrix jacobianFIntq() const

get \(\nabla_qF_{int}\), (pointer link)

Return

pointer on a SiconosMatrix

SP::SiconosMatrix jacobianFIntqDot() const

get \(\nabla_{\dot q}F_{int}\), (pointer link)

Return

pointer on a SiconosMatrix

void setJacobianFIntqPtr(SP::SiconosMatrix newPtr)

set \(\nabla_{q}F_{int}\), (pointer link)

Parameters
  • newPtr: a SP SiconosMatrix

void setJacobianFIntqDotPtr(SP::SiconosMatrix newPtr)

set \(\nabla_{\dot q}F_{int}\), (pointer link)

Parameters
  • newPtr: a SP SiconosMatrix

SP::SiconosMatrix jacobianFGyrq() const

get \(\nabla_{q}F_{gyr}\), (pointer link)

Return

pointer on a SiconosMatrix

SP::SiconosMatrix jacobianFGyrqDot() const

get \(\nabla_{\dot q}F_{gyr}\), (pointer link)

Return

pointer on a SiconosMatrix

void setJacobianFGyrqPtr(SP::SiconosMatrix newPtr)

get \(\nabla_{q}F_{gyr}\), (pointer link)

Parameters
  • newPtr: a SP SiconosMatrix

void setJacobianFGyrqDotPtr(SP::SiconosMatrix newPtr)

get \(\nabla_{\dot q}F_{gyr}\), (pointer link)

Parameters
  • newPtr: a SP SiconosMatrix

SP::SiconosVector forces() const

get \( F(v,q,t,z)\) (pointer link)

Return

pointer on a SiconosVector

virtual SP::SiconosMatrix jacobianqForces() const

get \( \nabla_qF(v,q,t,z)\) (pointer link)

Return

pointer on a SiconosMatrix

virtual SP::SiconosMatrix jacobianvForces() const

get \( \nabla_{\dot q}F(v,q,t,z)\) (pointer link)

Return

pointer on a SiconosMatrix

Memory vectors management

const SiconosMemory &qMemory()

get all the values of the state vector q stored in memory.

note: not const due to SchatzmanPaoliOSI::initializeWorkVectorsForDS

Return

a memory

const SiconosMemory &velocityMemory()

get all the values of the state vector velocity stored in memory.

note: not const due to SchatzmanPaoliOSI::initializeWorkVectorsForDS

Return

a memory

const SiconosMemory &pMemory(unsigned int level)

get all the values of the state vector p stored in memory

Return

a memory

Parameters
  • level:

const SiconosMemory &forcesMemory()

get forces in memory buff

Return

pointer on a SiconosMemory

void initMemory(unsigned int size)

initialize the SiconosMemory objects with a positive size.

Parameters
  • size: the size of the SiconosMemory. must be >= 0

void swapInMemory()

push the current values of x, q and r in the stored previous values xMemory, qMemory, rMemory,

Plugins management

void setComputeMassFunction(const std::string &pluginPath, const std::string &functionName)

allow to set a specified function to compute the mass

Parameters
  • pluginPath: std::string : the complete path to the plugin

  • functionName: std::string : the name of the function to use in this plugin

void setComputeMassFunction(FPtr7 fct)

set a specified function to compute Mass

Parameters
  • fct: a pointer on the plugin function

void setComputeFIntFunction(const std::string &pluginPath, const std::string &functionName)

allow to set a specified function to compute FInt

Parameters
  • pluginPath: std::string : the complete path to the plugin

  • functionName: std::string : the name of the function to use in this plugin

void setComputeFIntFunction(FPtr6 fct)

set a specified function to compute fInt

Parameters
  • fct: a pointer on the plugin function

void setComputeFExtFunction(const std::string &pluginPath, const std::string &functionName)

allow to set a specified function to compute Fext

Parameters
  • pluginPath: std::string : the complete path to the plugin

  • functionName: std::string : the name of the function to use in this plugin

void setComputeFExtFunction(VectorFunctionOfTime fct)

set a specified function to compute fExt

Parameters
  • fct: a pointer on the plugin function

void setComputeFGyrFunction(const std::string &pluginPath, const std::string &functionName)

allow to set a specified function to compute the inertia

Parameters
  • pluginPath: std::string : the complete path to the plugin

  • functionName: std::string : the name of the function to use in this plugin

void setComputeFGyrFunction(FPtr5 fct)

set a specified function to compute FGyr

Parameters
  • fct: a pointer on the plugin function

void setComputeJacobianFIntqFunction(const std::string &pluginPath, const std::string &functionName)

allow to set a specified function to compute the jacobian w.r.t q of the internal forces

Parameters
  • pluginPath: std::string : the complete path to the plugin

  • functionName: std::string : the name of the function to use in this plugin

void setComputeJacobianFIntqDotFunction(const std::string &pluginPath, const std::string &functionName)

allow to set a specified function to compute the jacobian following qDot of the internal forces w.r.t.

Parameters
  • pluginPath: std::string : the complete path to the plugin

  • functionName: std::string : the name of the function to use in this plugin

void setComputeJacobianFIntqFunction(FPtr6 fct)

set a specified function to compute jacobian following q of the FInt

Parameters
  • fct: a pointer on the plugin function

void setComputeJacobianFIntqDotFunction(FPtr6 fct)

set a specified function to compute jacobian following qDot of the FInt

Parameters
  • fct: a pointer on the plugin function

void setComputeJacobianFGyrqFunction(const std::string &pluginPath, const std::string &functionName)

allow to set a specified function to compute the jacobian w.r.t q of the the external forces

Parameters
  • pluginPath: std::string : the complete path to the plugin

  • functionName: std::string : the name of the function to use in this plugin

void setComputeJacobianFGyrqDotFunction(const std::string &pluginPath, const std::string &functionName)

allow to set a specified function to compute the jacobian w.r.t qDot of the the external strength

Parameters
  • pluginPath: std::string : the complete path to the plugin

  • functionName: std::string : the name of the function to use in this plugin

void setComputeJacobianFGyrqFunction(FPtr5 fct)

set a specified function to compute the jacobian following q of FGyr

Parameters
  • fct: a pointer on the plugin function

void setComputeJacobianFGyrqDotFunction(FPtr5 fct)

set a specified function to compute the jacobian following qDot of FGyr

Parameters
  • fct: a pointer on the plugin function

virtual void computeMass()

default function to compute the mass

virtual void computeMass(SP::SiconosVector position)

function to compute the mass

Parameters
  • position: value used to evaluate the mass matrix

virtual void computeFInt(double time)

default function to compute the internal strengths

Parameters
  • time: the current time

virtual void computeFInt(double time, SP::SiconosVector position, SP::SiconosVector velocity)

function to compute the internal strengths with some specific values for position and velocity (ie not those of the current state).

Parameters
  • time: the current time,

  • position: value used to evaluate the internal forces

  • velocity: value used to evaluate the internal forces

virtual void computeFExt(double time)

default function to compute the external strengths

Parameters
  • time: the current time

virtual void computeFGyr()

default function to compute the inertia

virtual void computeFGyr(SP::SiconosVector position, SP::SiconosVector velocity)

function to compute the inertia with some specific values for q and velocity (ie not those of the current state).

Parameters
  • position: value used to evaluate the inertia forces

  • velocity: value used to evaluate the inertia forces

virtual void computeJacobianFIntq(double time)

To compute the jacobian w.r.t q of the internal forces.

Parameters
  • time: the current time

virtual void computeJacobianFIntqDot(double time)

To compute the jacobian w.r.t qDot of the internal forces.

Parameters
  • time: the current time

virtual void computeJacobianFIntq(double time, SP::SiconosVector position, SP::SiconosVector velocity)

To compute the jacobian w.r.t q of the internal forces.

Parameters
  • time: the current time

  • position: value used to evaluate the jacobian

  • velocity: value used to evaluate the jacobian

virtual void computeJacobianFIntqDot(double time, SP::SiconosVector position, SP::SiconosVector velocity)

To compute the jacobian w.r.t.

qDot of the internal forces

Parameters
  • time: the current time

  • position: value used to evaluate the jacobian

  • velocity: value used to evaluate the jacobian

virtual void computeJacobianFGyrq()

function to compute the jacobian w.r.t.

q of the inertia forces

virtual void computeJacobianFGyrqDot()

function to compute the jacobian w.r.t.

qDot of the inertia forces

virtual void computeJacobianFGyrq(SP::SiconosVector position, SP::SiconosVector velocity)

function to compute the jacobian w.r.t.

q of the inertia forces

Parameters
  • position: value used to evaluate the jacobian

  • velocity: value used to evaluate the jacobian

virtual void computeJacobianFGyrqDot(SP::SiconosVector position, SP::SiconosVector velocity)

function to compute the jacobian w.r.t.

qDot of the inertia forces

Parameters
  • position: value used to evaluate the jacobian

  • velocity: value used to evaluate the jacobian

virtual void updatePlugins(double time)

default function to update the plugins functions using a new time:

Parameters
  • time: the current time

Miscellaneous public methods

double computeKineticEnergy()

To compute the kinetic energy.

void display(bool brief = true) const

print the data of the dynamical system on the standard output

void computePostImpactVelocity()

Computes post-impact velocity, using pre-impact velocity and impulse (p) value.

Used in EventDriven (LsodarOSI->updateState)

void init_generalized_coordinates(unsigned int level)

Allocate memory for q[level], level > 1 Useful for some integrators that need q[2] or other coordinates vectors.

Parameters
  • level: the required level

void init_inverse_mass()

Allocate memory for the lu factorization of the mass of the system.

Useful for some integrators with system inversion involving the mass

void update_inverse_mass()

Update the content of the lu factorization of the mass of the system, if required.

void init_forces()

Allocate memory for forces and its jacobian.

Public Functions

LagrangianDS(SP::SiconosVector position, SP::SiconosVector velocity)

constructor from initial state only, \(dv = p \)

Parameters

LagrangianDS(SP::SiconosVector position, SP::SiconosVector velocity, SP::SiconosMatrix mass)

constructor from initial state and mass, \(Mdv = p \)

Parameters

LagrangianDS(SP::SiconosVector position, SP::SiconosVector velocity, const std::string &plugin)

constructor from initial state and mass (plugin) \(Mdv = p \)

Parameters

virtual ~LagrangianDS()

destructor