Recursive newton euler forward dynamics solver. More...

#include <chainfdsolver_recursive_newton_euler.hpp>

Inheritance diagram for KDL::ChainFdSolver_RNE:

Public Member Functions
int	CartToJnt (const JntArray &q, const JntArray &q_dot, const JntArray &torques, const Wrenches &f_ext, JntArray &q_dotdot)

	ChainFdSolver_RNE (const Chain &chain, Vector grav)

void	RK4Integrator (unsigned int &nj, const double &t, double &dt, KDL::JntArray &q, KDL::JntArray &q_dot, KDL::JntArray &torques, KDL::Wrenches &f_ext, KDL::ChainFdSolver_RNE &fdsolver, KDL::JntArray &q_dotdot, KDL::JntArray &dq, KDL::JntArray &dq_dot, KDL::JntArray &q_temp, KDL::JntArray &q_dot_temp)

virtual void	updateInternalDataStructures ()

	~ChainFdSolver_RNE ()

Public Member Functions inherited from KDL::SolverI
virtual int	getError () const
	Return the latest error. More...

	SolverI ()
	Initialize latest error to E_NOERROR. More...

virtual const char *	strError (const int error) const

virtual	~SolverI ()

Private Attributes
Eigen::VectorXd	acc_eig

const Chain &	chain

Eigen::VectorXd	D_eig

ChainDynParam	DynSolver

JntSpaceInertiaMatrix	H

Eigen::MatrixXd	H_eig

ChainIdSolver_RNE	IdSolver

Eigen::MatrixXd	L_eig

unsigned int	nj

unsigned int	ns

Eigen::VectorXd	r_eig

JntArray	Tzeroacc

Eigen::VectorXd	Tzeroacc_eig

Additional Inherited Members
Public Types inherited from KDL::SolverI
enum	{ E_DEGRADED = +1, E_NOERROR = 0, E_NO_CONVERGE = -1, E_UNDEFINED = -2, E_NOT_UP_TO_DATE = -3, E_SIZE_MISMATCH = -4, E_MAX_ITERATIONS_EXCEEDED = -5, E_OUT_OF_RANGE = -6, E_NOT_IMPLEMENTED = -7, E_SVD_FAILED = -8 }

Protected Attributes inherited from KDL::SolverI
int	error
	Latest error, initialized to E_NOERROR in constructor. More...

Detailed Description

Recursive newton euler forward dynamics solver.

The algorithm implementation is based on the book "Rigid Body Dynamics Algorithms" of Roy Featherstone, 2008 (ISBN:978-0-387-74314-1) See Chapter 6 for basic algorithm.

It calculates the accelerations for the joints (qdotdot), given the position and velocity of the joints (q,qdot,qdotdot), external forces on the segments (expressed in the segments reference frame), and the dynamical parameters of the segments.

Definition at line 42 of file chainfdsolver_recursive_newton_euler.hpp.

Constructor & Destructor Documentation

KDL::ChainFdSolver_RNE::ChainFdSolver_RNE	(	const Chain &	chain,
		Vector	grav
	)

Constructor for the solver, it will allocate all the necessary memory

Parameters

chain	The kinematic chain to calculate the forward dynamics for, an internal copy will be made.
grav	The gravity vector to use during the calculation.

Definition at line 29 of file chainfdsolver_recursive_newton_euler.cpp.

KDL::ChainFdSolver_RNE::~ChainFdSolver_RNE ( )

inline

Definition at line 50 of file chainfdsolver_recursive_newton_euler.hpp.

Member Function Documentation

int KDL::ChainFdSolver_RNE::CartToJnt	(	const JntArray &	q,
		const JntArray &	q_dot,
		const JntArray &	torques,
		const Wrenches &	f_ext,
		JntArray &	q_dotdot
	)

virtual

Function to calculate from Cartesian forces to joint torques. Input parameters;

Parameters

q	The current joint positions
q_dot	The current joint velocities
torques	The current joint torques (applied by controller)
f_ext	The external forces (no gravity) on the segments Output parameters:
q_dotdot	The resulting joint accelerations

Implements KDL::ChainFdSolver.

Definition at line 51 of file chainfdsolver_recursive_newton_euler.cpp.

void KDL::ChainFdSolver_RNE::RK4Integrator	(	unsigned int &	nj,
		const double &	t,
		double &	dt,
		KDL::JntArray &	q,
		KDL::JntArray &	q_dot,
		KDL::JntArray &	torques,
		KDL::Wrenches &	f_ext,
		KDL::ChainFdSolver_RNE &	fdsolver,
		KDL::JntArray &	q_dotdot,
		KDL::JntArray &	dq,
		KDL::JntArray &	dq_dot,
		KDL::JntArray &	q_temp,
		KDL::JntArray &	q_dot_temp
	)

Function to integrate the joint accelerations resulting from the forward dynamics solver. Input parameters;

Parameters

nj	The number of joints
t	The current time
dt	The integration period
q	The current joint positions
q_dot	The current joint velocities
torques	The current joint torques (applied by controller)
f_ext	The external forces (no gravity) on the segments
fdsolver	The forward dynamics solver Output parameters:
t	The updated time
q	The updated joint positions
q_dot	The updated joint velocities
q_dotdot	The current joint accelerations
dq	The joint position increment
dq_dot	The joint velocity increment Temporary parameters:
qtemp	Intermediate joint positions
qdtemp	Intermediate joint velocities

Definition at line 95 of file chainfdsolver_recursive_newton_euler.cpp.

void KDL::ChainFdSolver_RNE::updateInternalDataStructures ( )

virtual

Update the internal data structures. This is required if the number of segments or number of joints of a chain/tree have changed. This provides a single point of contact for solver memory allocations.

Implements KDL::SolverI.

Definition at line 46 of file chainfdsolver_recursive_newton_euler.cpp.